US20240040555A1 - Apparatus and method for inter-band pairing of carriers for time division duplex transmit- and receive-switching and its application to multiplexing of different transmission time intervals - Google Patents

Abstract

Aspects of the present disclosure provide for the pairing of an inter-band carrier with a time division duplex (TDD) carrier. If the paired band is a frequency division duplex (FDD) band, then base stations and mobile devices may transmit and receive additional thin control channels on FDD carriers to enable full duplex operations. If the paired band is a TDD band, then a conjugate or inverse carrier may be used such that full duplex, or a close approximation thereto, is achieved. With the introduction of a paired channel and fast control channels, rapid uplink/downlink switching may be achieved for TDD carriers efficiently and effectively. Other aspects, embodiments, and features are also claimed and described.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a Continuation of Non-Provisional application Ser. No. 17/321,223 filed in the United States Patent and Trademark Office on May 14, 2021. Application Ser. No. 17/321,223 is a continuation of Non-Provisional application Ser. No. 14/567,985, filed Dec. 11, 2014, which claims the benefit of Provisional Patent Application No. 62/000,454, filed May 19, 2014, and Provisional Patent Application No. 62/000,443, filed May 19, 2014, the entire contents of each of which is incorporated herein by reference as if fully set forth below in its entirety and for all applicable purposes.
TECHNICAL FIELD
• Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to pairing an inter-band carrier with a time division duplex (TDD) carrier to achieve full duplex communication.
BACKGROUND
• Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources.
• Within such wireless networks a variety of data services may be provided, including voice, video, and emails. More recently, wireless communication networks are being utilized for an even broader range of services, including mission critical applications and remote control applications such as tele-surgery, where real-time feedback is necessary. In such applications, very low latency is critical to enable a suitably high quality of service. That is, the time for information to be transmitted from a communication device, and a response received back at the communication device, may need to be extremely rapid, on the order of milliseconds.
• As the demand for mobile broadband access continues to increase, research and development continue to advance wireless communication technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience.
BRIEF SUMMARY OF SOME EXAMPLES
• The following presents a simplified summary of one or more aspects of the present disclosure, in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated features of the disclosure, and is intended neither to identify key or critical elements of all aspects of the disclosure nor to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in a simplified form as a prelude to the more detailed description that is presented later.
• Various aspects of the present disclosure provide for the pairing of an inter-band carrier with a time division duplex (TDD) carrier. If the paired band is a frequency division duplex (FDD) band, then base stations and mobile devices may transmit and receive additional thin control channels on FDD carriers to enable full duplex operations. If the paired band is a TDD band, then a conjugate or inverse carrier may be used such that full duplex, or a close approximation thereto, is achieved. With the introduction of a paired channel and fast control channels, rapid uplink/downlink switching may be achieved for TDD carriers efficiently and effectively.
• In one aspect, the disclosure provides a method, apparatus, and computer-readable medium having code for implementing wireless communication utilizing an algorithm for pairing inter-band carriers for transmit- and receive switching. Here, a scheduling entity may wirelessly communicate utilizing a first transmission time interval (TTI) over a first carrier, the first carrier being a time division duplex (TDD) carrier. Further, the scheduling entity may wirelessly communicate utilizing a second TTI different from the first TTI and at least partially overlapping the first TTI, over a second carrier paired with the first carrier but separated from the first carrier in frequency.
• These and other aspects of the invention will become more fully understood upon a review of the detailed description, which follows. Other aspects, features, and embodiments of the present invention will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary embodiments of the present invention in conjunction with the accompanying figures. While features of the present invention may be discussed relative to certain embodiments and figures below, all embodiments of the present invention can include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various embodiments of the invention discussed herein. In similar fashion, while exemplary embodiments may be discussed below as device, system, or method embodiments it should be understood that such exemplary embodiments can be implemented in various devices, systems, and methods.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG.1 is a block diagram conceptually illustrating an example of a scheduling entity communicating with one or more subordinate entities according to some embodiments.
• FIG.2 is a block diagram illustrating an example of a hardware implementation for a scheduling entity employing a processing system according to some embodiments.
• FIG.3 is a block diagram illustrating an example of a hardware implementation for a subordinate entity employing a processing system according to some embodiments.
• FIG.4 is a schematic diagram illustrating a synchronous multiple access channel structure in a full duplex system for multiplexing low latency uplink data with regular uplink data according to one example.
• FIG.5 is a schematic diagram illustrating a synchronous multiple access channel structure with a time division duplex (TDD) carrier being paired with a frequency division duplex (FDD) carrier for multiplexing low latency uplink data with regular uplink data according to one example.
• FIG.6 is a call flow diagram illustrating an example of multiplexing low latency uplink data with regular uplink data utilizing a thin control channel according to some embodiments.
• FIG.7 is a flow chart illustrating an example of multiplexing low latency uplink data with regular uplink data utilizing a thin control channel from the point of view of a scheduling entity, according to some embodiments.
• FIG.8 is a schematic diagram illustrating a synchronous multiple access channel structure with a TDD carrier being paired with an FDD carrier for multiplexing low latency downlink data with regular uplink data according to one example.
• FIG.9 is a call flow diagram illustrating an example of multiplexing low latency downlink data with regular uplink data utilizing a thin control channel according to some embodiments.
• FIG.10 is a flow chart illustrating an example of multiplexing low latency downlink data with regular uplink data utilizing a thin control channel from the point of view of a scheduling entity, according to some embodiments.
• FIG.11 is a schematic diagram illustrating a synchronous multiple access channel structure with a TDD carrier being paired with an FDD carrier for multiplexing low latency uplink data with regular downlink data according to one example.
• FIG.12 is a call flow diagram illustrating an example of multiplexing low latency uplink data with regular downlink data utilizing a thin control channel according to some embodiments.
• FIG.13 is a flow chart illustrating an example of multiplexing low latency uplink data with regular downlink data utilizing a thin control channel from the point of view of a scheduling entity, according to some embodiments.
• FIG.14 is a schematic diagram illustrating inverse (conjugate) pairing of time division duplex carriers according to one example.
• FIG.15 is a schematic diagram illustrating inverse (conjugate) pairing of time division duplex carriers according to another example.
• FIG.16 is a schematic diagram illustrating a synchronous multiple access channel structure with paired TDD carriers for multiplexing low latency uplink data with regular uplink data according to one example.
• FIG.17 is a call flow diagram illustrating an example of multiplexing low latency uplink data with regular uplink data utilizing a thin control channel according to some embodiments.
• FIG.18 is a flow chart illustrating an example of multiplexing low latency uplink data with regular uplink data utilizing a thin control channel from the point of view of a scheduling entity, according to some embodiments.
• FIG.19 is a schematic diagram illustrating a synchronous multiple access channel structure with paired TDD carriers for multiplexing low latency downlink data with regular uplink data according to one example.
• FIG.20 is a call flow diagram illustrating an example of multiplexing low latency downlink data with regular uplink data utilizing a thin control channel according to some embodiments.
• FIG.21 is a flow chart illustrating an example of multiplexing low latency downlink data with regular uplink data utilizing a thin control channel from the point of view of a scheduling entity, according to some embodiments.
• FIG.22 is a schematic diagram illustrating a synchronous multiple access channel structure with paired TDD carriers for multiplexing low latency uplink data with regular downlink data according to one example.
• FIG.23 is a call flow diagram illustrating an example of multiplexing low latency uplink data with regular downlink data utilizing a thin control channel according to some embodiments.
• FIG.24 is a flow chart illustrating an example of multiplexing low latency uplink data with regular downlink data utilizing a thin control channel from the point of view of a scheduling entity, according to some embodiments.
• FIG.25 is a flow chart illustrating an example of wireless communication utilizing a TDD carrier paired with a second carrier, and multiplexing long and short TTIs, according to some embodiments.
• FIG.26 is a flow chart illustrating an example of wireless communication utilizing a pair of TDD carriers for full duplex communication, according to some embodiments.
DETAILED DESCRIPTION
• The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.
• The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. For example, the 3^rdGeneration Partnership Project (3GPP) is a standards body that defines several wireless communication standards for networks involving the evolved packet system (EPS), frequently referred to as long-term evolution (LTE) networks. LTE networks can provide end-to-end latency between a transmitting device and a receiving device on the order of 50 ms, with over-the-air latency for a particular packet being in the range of 10 ms. Currently known LTE functionality provides for a round trip time (RTT) for certain feedback signaling (i.e., hybrid automatic repeat request (HARQ) signaling) of at least about 8 ms, using a transmission time interval (TTI) of 1 ms. (Here, a TTI corresponds to a minimum duration of a unit of information that can be decoded.) For time division duplex (TDD) LTE configurations, the uplink/downlink configuration has a relatively fixed configuration, which takes around 10 ms to change. In general, LTE provides for a one-size-fits-all approach, with all services and packets relying on these same latency ranges.
• Evolved versions of the LTE network, such as a fifth-generation (5G) network, may provide for many different types of services or applications, including but not limited to web browsing, video streaming, VoIP, mission critical applications, multi-hop networks, remote operations with real-time feedback (e.g., tele-surgery), etc. Here, these different sets of services may benefit from having multiple latency targets that are drastically different from one another. However, the one-size-fits-all aspects of the LTE network described above can make the multiplexing of traffic with different latency targets very difficult.
• The spectrum compatibility of a system that supports such diverse latency targets can be challenging. For example, the time multiplexing of regular/low latency traffic could violate the requirements of low latency packets. Furthermore, reserved frequency domain resources for low latency traffic would limit the peak rate and trunking efficiency. Thus, for next generation networks there is a need for new ways to support the ability to multiplex various types, classes, and categories traffic and services, including but not limited to traffic having drastically different latency characteristics.
• According to some aspects of the present disclosure, apparatus, methods, and computer instructions are disclosed, providing for the pairing of an inter-band carrier with a time division duplex (TDD) carrier. If the paired band is a frequency division duplex (FDD) band, then base stations and mobile devices may transmit and receive additional thin control channels on FDD carriers to enable full duplex operations. If the paired band is another TDD band, then a conjugate or inverse carrier may be used such that full duplex communication is achieved. With the introduction of the paired channel and fast control channels, rapid uplink/downlink switching may be achieved for TDD carriers efficiently and effectively, enabling the multiplexing of various types, classes, and categories of traffic and services.
• Referring now toFIG.1, a block diagram is provided illustrating ascheduling entity102 and a plurality ofsubordinate entities104 engaged in wireless communication utilizingthin control channels108/112 and athin feedback channel114, described in further detail below. Of course, the channels illustrated inFIG.1 are not necessarily all of the channels that may be utilized between ascheduling entity102 andsubordinate entities104, and those of ordinary skill in the art will recognize that other channels may be utilized in addition to those illustrated, such as other control and feedback channels. As illustrated inFIG.1, thescheduling entity102 may broadcastdownlink data106 to one or moresubordinate entities104. In accordance with aspects of the present disclosure, the term downlink may refer to a point-to-multipoint transmission originating at thescheduling entity102. Broadly, thescheduling entity102 is a node or device responsible for scheduling traffic in a wireless communication network, including the downlink transmissions and, in some examples,uplink data110 from one or more subordinate entities to thescheduling entity102. (Another way to describe the scheme may be to use the term broadcast channel multiplexing.) In accordance with aspects of the present disclosure, the term uplink may refer to a point-to-point transmission originating at asubordinate entity104. Broadly, thesubordinate entity104 is a node or device that receives scheduling control information, including but not limited to scheduling grants, synchronization or timing information, or other control information from another entity in the wireless communication network such as thescheduling entity102.
• In a further aspect of the disclosure, thescheduling entity102 may broadcast athin control channel108 and/or112 to one or moresubordinate entities104. As described herein below, the use of athin control channel108/112 can enable modification/puncturing of uplink and/or downlink data being transmitted using a first, long transmission time interval (TTI), with other data (e.g., low latency (LoLat) packets) utilizing a second, short TTI.
• Furthermore, thesubordinate entities104 may transmit athin feedback channel114 to thescheduling entity102. The thin feedback channel may in some examples include a request for the scheduling entity to modify/puncture a first, long TTI with LoLat packets utilizing a second, short TTI. Here, in response to the request transmitted on thethin feedback channel114, thescheduling entity102 may transmit in thethin control channel112 information that may schedule modification/puncturing of the long, first TTI with LoLat packets utilizing the second, short TTI.
• FIG.2 is a conceptual diagram illustrating an example of a hardware implementation for ascheduling entity102 employing aprocessing system214. In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with aprocessing system214 that includes one ormore processors204.
• In various aspects of the disclosure, the apparatus200 may be any suitable radio transceiver apparatus, and in some examples, may be embodied by a base station (BS), a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), a Node B, an eNode B (eNB), mesh node, relay, or some other suitable terminology. Within the present document, a base station may be referred to as a scheduling entity, indicating that the base station provides scheduling information to one or more subordinate entities.
• In other examples, the apparatus200 may be embodied by a wireless user equipment (UE). Examples of a UE include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a personal digital assistant (PDA), a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, an entertainment device, a vehicle component, a wearable computing device (e.g., a smart watch, a health or fitness tracker, etc.), an appliance, a sensor, a vending machine, or any other similar functioning device. The UE may also be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. Within the present document, a UE may be referred to either as a scheduling entity, or a subordinate entity. That is, in various aspects of the present disclosure, a wireless UE may operate as a scheduling entity providing scheduling information to one or more subordinate entities, or may operate as a subordinate entity in accordance with scheduling information provided by a scheduling entity.
• Examples ofprocessors204 include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. That is, theprocessor204, as utilized in an apparatus200, may be used to implement any one or more of the processes described below and illustrated inFIGS.5-26.
• In this example, theprocessing system214 may be implemented with a bus architecture, represented generally by thebus202. Thebus202 may include any number of interconnecting buses and bridges depending on the specific application of theprocessing system214 and the overall design constraints. Thebus202 links together various circuits including one or more processors (represented generally by the processor204), amemory205, and computer-readable media (represented generally by the computer-readable medium206). Thebus202 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. Abus interface208 provides an interface between thebus202 and atransceiver210. Thetransceiver210 provides a means for communicating with various other apparatus over a transmission medium. Depending upon the nature of the apparatus, a user interface212 (e.g., keypad, display, speaker, microphone, joystick) may also be provided.
• In some aspects of the disclosure, theprocessor204 may include resource assignment andTTI control circuitry241, configured to generate, schedule, and modify a resource assignment or grant of time-frequency resources. The resource assignment andTTI control circuitry241 may further be configured to determine the TTI to utilize for uplink and downlink transmissions, e.g., whether data transmissions should utilize a first, long TTI, or a second, short TTI. The resource assignment andTTI control circuitry241 may operate in coordination with resource assignment andTTI control software251. Theprocessor204 may further include data and control channel generation andtransmission circuitry242, configured to generate and transmit uplink and downlink data and control channels, as well as uplink feedback channels and downlink control channels, including but not limited to a thin control channel, a thin feedback channel, a LoLat grant channel, a grant modification channel, and an assignment channel. The data and control channel generation andtransmission circuitry242 may operate in coordination with data and control channel generation andtransmission software252. Theprocessor204 may further include thin feedback reception andprocessing circuitry243, configured to receive scheduling requests on an uplink feedback channel, the scheduling requests being configured to request a grant of time-frequency resources for uplink user data transmissions. The thin feedback reception andprocessing circuitry243 may operate in coordination with thin feedback reception andprocessing software253. Theprocessor204 may further include data channel reception andprocessing circuitry244, configured to receive and process user data on uplink data channels from one or more subordinate entities. The data channel reception andprocessing circuitry244 may operate in coordination with data channel and reception andprocessing software254. Theprocessor204 may further includeTDD control circuitry245 andFDD control circuitry246, configured to control wireless communication (e.g., transmission and/or reception of data and/or control channels) on one or more TDD or FDD carriers, respectively. The TDD control circuitry may operate in coordination withTDD control software255. The FDD control circuitry may operate in coordination withFDD control software256.
• Theprocessor204 is responsible for managing thebus202 and general processing, including the execution of software stored on the computer-readable medium206. The software, when executed by theprocessor204, causes theprocessing system214 to perform the various functions described below for any particular apparatus. The computer-readable medium206 may also be used for storing data that is manipulated by theprocessor204 when executing software.
• One ormore processors204 in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium206. The computer-readable medium206 may be a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., a compact disc (CD) or a digital versatile disc (DVD)), a smart card, a flash memory device (e.g., a card, a stick, or a key drive), a random access memory (RAM), a read only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. The computer-readable medium may also include, by way of example, a carrier wave, a transmission line, and any other suitable medium for transmitting software and/or instructions that may be accessed and read by a computer. The computer-readable medium206 may reside in theprocessing system214, external to theprocessing system214, or distributed across multiple entities including theprocessing system214. The computer-readable medium206 may be embodied in a computer program product. By way of example, a computer program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.
• FIG.3 is a conceptual diagram illustrating an example of a hardware implementation for an exemplarysubordinate entity104 employing aprocessing system314. In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a processing system414 that includes one ormore processors304.
• Theprocessing system314 may be substantially the same as theprocessing system214 illustrated inFIG.2, including abus interface308, abus302,memory305, aprocessor304, and a computer-readable medium306. Furthermore, thesubordinate entity304 may include auser interface312 and atransceiver310 substantially similar to those described above inFIG.2. Theprocessor304, as utilized in asubordinate entity104, may be used to implement any one or more of the processes described below and illustrated inFIGS.5-26.
• In some aspects of the disclosure, theprocessor304 may include fast suspension ofuplink transmissions circuitry341, configured for quickly suspending uplink transmissions, e.g., by driving a zero input to a power amplifier within thetransceiver310, or in another example, being capable of quickly turning off the power amplifier in thetransceiver310. The fast suspension ofuplink transmissions circuitry341 may operate in coordination with fast suspension ofuplink transmissions software351. Theprocessor304 may further include data and control channel generation andtransmission circuitry342, configured to generate and transmit uplink data on a data channel, and to generate and transmit uplink control information and feedback information on control and feedback channels. The data and control channel generation andtransmission circuitry342 may operate in coordination with data and control channel generation andtransmission software352. Theprocessor304 may further include data and control channel reception andprocessing circuitry343, configured for receiving and processing downlink data on a data channel, and to receive and process control information on one or more downlink control channels. In some examples, received downlink data and/or control information may be temporarily stored in a data buffer withinmemory305. The data and control channel reception andprocessing circuitry343 may operate in coordination with data and control channel reception andprocessing software353. Theprocessor304 may further includeTDD control circuitry344 andFDD control circuitry345, configured to control wireless communication (e.g., transmission and/or reception of data and/or control channels) on one or more TDD or FDD carriers, respectively. The TDD control circuitry may operate in coordination withTDD control software354. The FDD control circuitry may operate in coordination withFDD control software355.
• As described below, some aspects of the disclosure provide for wireless communication utilizing a TDD carrier paired with a second carrier, and multiplexing long and short TTIs on the paired carriers. Further aspects of the disclosure provide for wireless communication utilizing a pair of TDD carriers for full duplex communication.
• Of course, these examples are merely provided to illustrate certain concepts of the invention. Those of ordinary skill in the art will comprehend that these are merely exemplary in nature, and other examples may fall within the scope of the disclosure and the appended claims.
Thin Control Channel in a Full Duplex System
• Some aspects of the present disclosure provide for synchronous multiplexing of different classes of services and traffic having different latency targets. For example, multiplexing may be enabled by utilizing a certain “thin control channel,” described below. This thin control channel may provide for fast signaling to enable the multiplexing of data with short TTIs and other data with long TTIs. As one example, high priority, low latency (LoLat) data having a short TTI may be enabled to interrupt regular traffic having a long TTI.FIG.4 is a schematic diagram illustrating an example of a synchronous multiple access channel structure including a “thin” control channel as it may be implemented according to some aspects of the present disclosure. As illustrated inFIG.4, the channel structure may be applicable to an uplink data transmission, i.e., a transmission from asubordinate entity104 to ascheduling entity102. Of course, this channel structure is not limited to such a scheme, but rather may be generalized to be applicable to any link where the receiving device is scheduling the traffic.
• In the illustration, the horizontal axis (t) represents time, while the vertical axis (f) generally represents frequency (not to scale). Channel resources for various users of the air interface occupy given areas within the channel, as outlined in the different blocks. For example, some of the time-frequency resources may be utilized by “regular” users402, which have less stringent latency requirements for their communication. In the illustration, as one example, six regular users402 labeled User A, B, C, D, E, and F are each scheduled time-frequency resources as indicated by their respectfully labeled blocks. Of course, in various examples any number of users may be scheduled the use of resources. Further, while in the illustration all of the time-frequency resources are shown being assigned to regular users, in various examples some or even all of the time-frequency resources may be unassigned, or assigned for another purpose other than for regular user data.
• In the context of the present disclosure, a regular user402 may be asubordinate entity104 that receives a resource assignment from ascheduling entity102, where the resource assignment indicates for thesubordinate entity104 to utilize a long transmission time interval (TTI). Such regular users402 may be more tolerant to latency in their communication, and may in some examples be more optimized for capacity. Accordingly, these users may utilize such longer TTIs for packets that can tolerate more latency than other users or other types of communication that might require low latency (LoLat) communication. A long TTI may broadly be any TTI that is longer than a short TTI, described in further detail below. In some examples, a long TTI may be a TTI that has a duration of a plurality of data symbols, or time slots. Some non-limiting examples of a long TTI may have a duration of 100 μs, 240 μs, or 1 ms. Of course, any suitable duration for a long TTI may be utilized within the scope of the disclosure.
• Furthermore, as illustrated inFIG.4, in addition to the uplink data traffic channels used by the regular users402, a “thin”feedback channel407 in the uplink direction may be utilized as illustrated. Here, thethin feedback channel407 may be the same as thethin feedback channel114 described above and illustrated inFIG.1. Within the present disclosure, the thin feedback channel may lie in one or more frequency sub-band(s) outside of (e.g., above) the frequency sub-bands utilized by the uplink traffic transmissions, such as the allocated time-frequency resources described above for regular users A-F402. The width of thethin feedback channel407 in the frequency direction may be reduced or minimized so as to reduce or minimize the amount of overhead utilized by thethin feedback channel407.
• Still further, as illustrated inFIG.4, in addition to the uplink traffic and feedback channels, athin control channel406 may be utilized in the downlink direction as illustrated. Here, thethin control channel406 may be the same as one or both of thethin control channels108/112 described above and illustrated inFIG.1. Within the present disclosure, the thin control channel may lie in one or more frequency sub-band(s) outside of the frequency sub-bands utilized by the uplink traffic and feedback transmissions, such as the allocated time-frequency resources described above for regular users A-F402 and thethin feedback channel407. For example, in a frequency division duplex (FDD) system, thethin control channel406 may be in a different band than the uplink traffic and feedback channels. The width of thethin control channel406 in the frequency direction may be reduced or minimized so as to reduce or minimize the amount of overhead utilized by thecontrol channel406. In a further aspect, all active users (e.g.,subordinate entities104 including but not necessarily limited to the regular users402) in communication with thescheduling entity102 that broadcasts thethin control channel406 may monitor (and, in some examples, buffer) thethin control channel406 shown herein.
• As illustrated inFIG.4, each time slot, symbol, or unit of thethin control channel406 may correspond to the duration of a short TTI. That is, in some examples, the short TTI may correspond to the time duration of a single symbol. Some non-limiting examples of a short TTI may have a duration of 10 μs, 20 μs, 100 μs, or any other suitable duration that is shorter than the long TTI. In some examples, the long TTI may represent an integer multiple of short TTIs. In some examples, a common symbol duration may be utilized within both the long TTI and the short TTI, or in other examples, different symbol durations may be utilized within the long TTI and the short TTI. The duration of information symbols carried within either of the long or short TTIs may also take any suitable duration, with one example being a 10 μs duration for each symbol. In an example wherein orthogonal frequency division multiplexing is adopted, an additional 1 μs cyclic prefix may be added to the symbol duration.
• In an aspect of the present disclosure, thisthin control channel406 can enable dynamic multiplexing of the traffic for theLoLat users404, who utilize the short TTI, and the traffic for the regular users402, who utilize the long TTI. That is, a plurality of regular users402 may be transmitting uplink communications utilizing an existing assignment of time-frequency resources. Here, any suitable control channel, including but not necessarily limited to thethin control channel406, may be utilized to grant resources to the various entities in the network, such that thosesubordinate entities104 may transmit uplink data according to their respective assignments utilizing the long TTI.
• Here, it may be the case that a subordinate entity in the network wishes to transmit LoLat data. Here, in order to maintain orthogonality among a plurality of subordinate entities, a central, scheduling entity may be utilized to schedule the uplink transmissions by each of the subordinate entities, and they may generally not randomly transmit uplink data without receiving assigned time-frequency resources for such transmission. Accordingly, when a subordinate entity determines that it has traffic (e.g., high priority traffic) that it wishes to be transmitted with a lower latency, then the subordinate entity may transmit aLoLat scheduling request409 on thethin feedback channel407. TheLoLat scheduling request409 is illustrated as occupying a single short TTI, although this is not necessarily always the case, and various LoLat scheduling requests might occupy any suitable number of short TTIs or symbol lengths. The contents of theLoLat scheduling request409 may include information about the LoLat data that the transmitting entity wishes to transmit, such as, for example, length, data type, priority, latency, or any other suitable information relating to the LoLat data.
• In response to theLoLat scheduling request409, the receiving end of the LoLat scheduling request409 (e.g., the scheduling entity) may accordingly determine to grant a scheduling adjustment. In this way, the scheduling entity may make resources available for the requesting subordinate entity to make its LoLat transmission. Thus, the scheduling entity may transmit, on thethin control channel406, anuplink grant modification408 to its regular users402. Theuplink grant modification408 may notify the regular users402 that their grant is being modified, and that the previously allocated long TTI time-frequency resources will be punctured, and that the resources will not be used by the regular users402. Here, puncturing the resources of the regular user402 may in some examples mean that the regular user402 ceases transmitting during the time associated with the re-assigned short TTI. In other examples, where one or more means of channel multiplexing may be used (including but not limited to frequency division multiplexing and code division multiplexing), puncturing the resources of the regular user402 may mean that the regular user402 ceases using punctured resources but may continue transmitting uplink data utilizing another frequency or another scrambling code, other than the resource granted to theLoLat user404, in order to maintain orthogonality. As described above, thethin control channel406 may be a point-to-multipoint broadcast channel monitored by all subordinate entities in communication with the scheduling entity. In this way, any user or users having their formerly granted time-frequency resources punctured by theuplink grant modification408 can be informed or instructed not to transmit their uplink transmission utilizing the particular time-frequency resource now allocated to aLoLat user404.
• In a further aspect, theuplink grant modification408 may not only include grant modification information directed to the regular users402, but in some examples may further include grant information directed to the requestingLoLat user404 indicating that the punctured time-frequency resources have been allocated to theLoLat user404. In another example within the scope of the present disclosure, the grant information directed to the requestingLoLat user404 may be carried on a separate uplink grant channel (not illustrated). That is, the thin control channel may in some examples exclude grant information for theLoLat user404, this information being transmitted on any suitable downlink channel readable by the requestingLoLat user404. In any case, grant information directed to the requestingLoLat user404 may include information identifying theLoLat user404, identifying one or more time-frequency resources, modulation and coding schemes, transmission schemes, or any other suitable information relating to the granted resource for the requestingLoLat user404.
• In the illustration ofFIG.10, theLoLat user404 transmits theLoLat scheduling request409, but all subordinate entities, including the regular users402, receive theuplink grant modification408. Here, in a further aspect of the disclosure, the regular users402 may be configured such that they are capable of decoding theuplink grant modification408 relatively quickly, so that they can promptly cease transmitting (e.g., puncture their transmissions) during the re-allocated short TTI(s). In this way, the time-frequency resources may quickly be made available for theLoLat user404 to transmit its LoLat symbols.
• The illustrated example ofFIG.4 applies to a full-duplex scheme, wherein downlink channels such as thethin control channel406 may be utilized at the same time as uplink channels such as the uplink data channels. In this scheme, because communication in both directions simultaneously is enabled, all of the active users may monitor (and, in some examples, buffer) thethin control channel406 shown herein. However, in a half-duplex scheme, such as a time division duplex (TDD) channel structure, multiplexing of data having different TTIs necessitates additional considerations.
Thin Control Channels in a TDD System—Paired Carriers
• Thin control channels such as thethin control channel406 described above have been identified as an enabling feature for many potential uses. For example, by utilizing a thin control channel, a communication system can be provided with low-latency data rate control, coordinated multi-point (CoMP) solutions, and improved access to unlicensed bands. Of course, these are merely some examples of features that may be enabled with the use of a thin control channel, and those of ordinary skill in the art will comprehend that other features may be enabled by way of the thin control channel. One relevant feature provided by the use of the thin control channel is opportunistic transmission/reception switching, wherein the thin control channel in one direction may be utilized to rapidly modify data communication in the other direction.
• Time division duplexing (TDD) is a well-known duplexing technique that provides for two-way communication between devices by applying time division multiplexing to separate the signals going in different directions from one another. As an example, channel resources may be divided into time slots, where some of the time slots are allocated for uplink transmissions, and other time slots are allocated for downlink transmissions. In this TDD scheme, only uplink or downlink transmissions, and not both, may take place during any particular time slot within that TDD band. One drawback of the TDD scheme is that it is only a half-duplex scheme, because only one direction of communication is possible at any given instant. Because of its half-duplex nature, opportunistic transmission/reception switching with a fast control channel during the middle of an ongoing transmission/reception, as described above in relation toFIG.4 with the introduction of a thin control channel, is in general not possible. That is, referring again toFIG.4, if a particular user (e.g., User D) is transmitting its uplink at the time when theuplink grant modification408 is transmitted, this user would not receive theuplink grant modification408, and thus, would not be informed of the grant modification, prohibiting the puncturing of its uplink transmission to make room for theLoLat user404.
• One exception, wherein TDD alone may be sufficient, may be in the case of the multiplexing of resources with different TTIs on downlink communications (e.g., downlink/downlink multiplexing, where one downlink transmission of a first TTI may be interrupted by another downlink transmission of a second TTI), which can be achieved without full duplex operation. That is, in this case, the transmission of a thin control channel and a data channel would be in the same downlink direction, and thus, the transmitter could continue transmitting, and the receiver could continue receiving, in a one-direction (or half-duplex) configuration.
• Therefore, to provide for improved functionality from a thin control channel in the case of uplink/uplink multiplexing, downlink/uplink multiplexing, or uplink/downlink multiplexing, the enablement of full duplex operation and functionality, even on a TDD spectrum, would be desirable.
• Referring again toFIG.4, this example of thin control for uplink data (i.e., transmissions from a subordinate entity) includes bi-directional full duplex communication, including regular user data402 and athin feedback channel407 in the uplink direction, as well as athin control channel406 in the downlink direction. Here, it can be seen that thethin control channel406 may transmit during each short TTI, and in addition, if a transmitting device (e.g., subordinate entity) wishes to interrupt and transmitLoLat data404, then at the same time as one of the thin control channel transmissions in the downlink direction, theLoLat user404 may transmit in the uplink direction aLoLat scheduling request409. (Additionally, the inserted LoLat packets may be downlink packets, or any other variation from the uplink packets that were interrupted).
• In a strict TDD system, this scheme would not be possible, because the device could not autonomously (without informing the other side of the link) interrupt transmissions in one direction with transmissions in the other direction. Similarly, if the UE is undertaking uplink transmissions, if it is a strict TDD system, the UE would not be aware of any attempt by the receiving device to modify the grant, because while transmitting the uplink it would not be receiving anything on the downlink at all.
• Therefore, in accordance with some aspects of the present disclosure, a channel structure is provided that incorporates a pairing of a TDD carrier with a second carrier, wherein the TDD carrier and the second carrier may be in different bands from one another (inter-band carriers). When the paired carrier provides an inverse, conjugate, or complementary direction of communication as that of the TDD carrier, full-duplex communication can be achieved, at least in some of the time slots, by simultaneous utilization of an uplink direction of communication in one carrier and a downlink direction of communication in the other carrier.
• In some examples, the paired (second) carrier may be in a frequency division duplex (FDD) band, which is capable of full duplex communication. That is, if the paired carrier is an FDD carrier, the paired carrier can include a plurality of carriers, such as an uplink component carrier and a downlink component carrier. Accordingly, if the paired carrier is in an FDD band, then both ends of the link (scheduling and subordinate) can simultaneously transmit and receive a thin control channel on the FDD carrier.
• In other examples, the paired carrier may be in a TDD band. In this case, in an aspect of the present disclosure, the two paired TDD carriers may implement conjugate or inverse duplexing, such that full duplex is achieved. This conjugate duplexing generally establishes that during some or all of the time slots or frames in one of the carriers, when those frames are configured for communication in one direction, then at that same time, a corresponding time slot or frame in the paired carrier is configured for communication in the other direction. In this way, by implementing paired carriers and fast (thin) control channels, among other functions, rapid uplink/downlink switching and multiplexing can be achieved for TDD carriers in an efficient and effective manner.
Downlink/Downlink Multiplexing
• In an aspect of the disclosure, described above, downlink/downlink multiplexing (e.g., enabling fast and dynamic switching between long and short TTIs) for data transmitted on a TDD carrier, need not necessarily utilize paired carriers. That is, because a thin control channel may be carried in the same direction, and at the same time as the downlink data on a TDD carrier, dynamic switching of TTIs can be accomplished on the fly by the scheduling entity that is transmitting the downlink utilizing a single TDD carrier.
FDD-TDD Carrier Pairing
• In some aspects of the disclosure, a TDD carrier may be paired with a second carrier that lies in a frequency division duplex (FDD) band, wherein the FDD carrier may include paired uplink and downlink component carriers that provide for full duplex communication in the FDD band. As described in further detail below, with this pairing, dynamic uplink/downlink switching can be achieved on data channels on the TDD carrier with the help of control channels on the FDD carrier.
FDD-TDD Carrier Pairing: Multiplexing LoLat UL on a Regular UL
• FIG.5 illustrates one example of pairing a TDD carrier with an FDD carrier, providing for multiplexing of LoLat uplink transmissions with regular uplink transmissions (i.e., transmissions from a subordinate entity) on the TDD carrier. In the illustrated example, the TDD carrier is illustrated in much the same way as the TDD carrier inFIG.4, with uplink resources allocated to different users being represented by the large blocks spanning a long TTI. Here, as will be described in further detail below, a subordinate entity (e.g., a UE) may request, and be granted, resources for a LoLat transmission that may be multiplexed with the “regular” uplink transmissions from other users. At the top of the figure, resources on an FDD band are allocated, including an uplink component carrier and a downlink component carrier.
• In the illustrated example, control channels for controlling the TDD uplink data are carried on the FDD component carriers. That is, the FDD band includes in its uplink component carrier athin feedback channel506 that a subordinate entity can utilize to transmit information such as a low latency (LoLat)scheduling request507. The FDD band further includes, in its downlink component carrier, athin control channel508, which may carry uplinkgrant modification information509 that modifies an uplink resource grant corresponding to the subordinate entity uplink transmission on the TDD carrier. Still further, the FDD band includes, in its downlink component carrier, aLoLat grant channel510, which may carrygrant information511 for the subordinate entity that requested LoLat scheduling to utilize in a LoLat uplink transmission on the TDD carrier.
• In addition to the illustrated channels, time-frequency resources corresponding to the long TTI may be granted for uplink transmissions on the TDD carrier to one or more subordinate entities (e.g., Users A-F) by utilizing any suitable downlink grant channel (not necessarily one of the illustrated channels). As these uplink transmissions are ongoing, if a particular subordinate entity, denoted as theLoLat user504, wishes to request resources for a LoLat uplink transmission, this subordinate entity may transmit aLoLat scheduling request507 on thethin feedback channel506 on the FDD uplink component carrier. Here, theLoLat scheduling request507 may utilize the short TTI, although this is not necessarily always the case. In response, if the scheduling entity wishes to grant the requested LoLat resource, thescheduling entity102 may transmit, on the FDD downlink component carrier, anuplink grant modification509 on thethin control channel508, and aLoLat grant511 on theLoLat grant channel511. Here, the anuplink grant modification509 on thethin control channel508 may be configured to inform all of the subordinate entities that are utilizing an existing grant of uplink time-frequency resources that some or all of their granted resources are being modified or removed, to make way for the LoLat transmission. Further, theLoLat grant511 on theLoLat grant channel510 may be configured to inform the subordinate entity that transmitted the LoLat scheduling request (i.e., the LoLat user504) of its granted time-frequency resources. In the illustration, theLoLat grant511 is shown as occupying a wider bandwidth than theUL grant modification509. This represents that, while theUL grant modification509 may simply be a few bits representing the frequency resources that are being re-allocated away from aregular user502, and a number of short TTIs, theLoLat grant511 may include more precise information relating to the LoLat resource assignment such as a user ID, the assignment information, a modulation and coding scheme, etc. Accordingly, theLoLat user504 may transmit its LoLat uplink transmission on the TDD carrier, while other “regular” users502 (such as Users D, E, and F) may cease their uplink transmissions, resulting in an orthogonal multiple access scheme between regular and LoLat uplink transmissions on the TDD carrier.
• In this example, the regular users502 (e.g., subordinate entities104), whose uplink resources were punctured, may benefit from having an ability to quickly decode theuplink grant modification509. That is, the time from when theuplink grant modification509 is received at theregular user502, until that user ceases its uplink transmissions, may be very short. To accommodate the quick reaction time, thesubordinate entity104 may be configured for a fast suspension of its uplink transmissions, e.g., by driving a zero input to a power amplifier within thetransceiver310, or in another example, being capable of quickly turning off the power amplifier. Furthermore, theLoLat user504 also may have only a brief time from the receiving of itsLoLat uplink grant511, and its transmission of LoLat uplink data. Accordingly, fast processing of theLoLat grant511 and transmission utilizing the scheduled time-frequency resources would be beneficial and reduce latency.
• FIG.6 is a call flow diagram illustrating an exemplary resource assignment and re-assignment procedure as it might occur in accordance with one example for multiplexing uplink data with different latency targets utilizing a TDD data carrier paired with FDD component carriers for control information. In this illustration, time moves forward in the downward direction, and communication signals between the illustrated entities are denoted with arrows between the lines below the respective entities. As illustrated, ascheduling entity501 is in communication with a plurality ofsubordinate entities104, including aregular user502 and aLoLat user504. Eachentity501,502, and504 is configured for communication over a TDD carrier, and an FDD carrier. The respective TDD and FDD carriers are illustrated schematically with the two vertical lines extending down from each respective entity.
• FIG.6 is described below in conjunction with a flow chart illustrated inFIG.7. That is,FIG.7 is a flow chart illustrating anexemplary process700 for resource assignment and re-assignment in accordance with some aspects of the present disclosure. Theprocess700 is described from the point-of-view of ascheduling entity501, and may accordingly, as described in conjunction withFIG.6, be operational at thescheduling entity102 described above in conjunction withFIGS.1 and/or2. In other examples within the scope of the present disclosure, theprocess700 may be operational by a general purpose processor, aprocessing system214 as described above and illustrated inFIG.2, or any suitable means for carrying out the described functions. The specific order of steps or blocks shown inFIG.7 is merely exemplary in nature, and in various aspects of the disclosure, these steps or blocks may occur in any suitable order, with some examples including two or more steps or blocks occurring simultaneously.
• Atblock702, thescheduling entity501 may transmit a first assignment or grant510 of time-frequency resources to at least one subordinate entity on the FDD downlink component carrier. Any suitable control channel on the FDD downlink component carrier may be utilized for the first resource assignment, such as a downlink assignment channel. Here, thefirst resource assignment510 may be configured to indicate which time-frequency resource or resources are assigned to the respective subordinate entities for regular transmissions of uplink data, that is, transmissions utilizing the long TTI. In accordance with thefirst resource assignment510, atblock704, thescheduling entity501 may receiveregular uplink data512 on the TDD uplink carrier from the at least one subordinate entity (e.g., thesubordinate entities502 and504) utilizing the long TTI. Here, with reference toFIG.5, thisregular uplink data512 may correspond to the transmissions fromregular users502. As illustrated inFIG.6 with the dashed-line arrow, regular uplink data may optionally be transmitted from the secondsubordinate entity504, depending on the contents of thefirst resource assignment510 and whether the secondsubordinate entity504 is configured to transmit uplink data transmissions utilizing the long TTI.
• Theblocks702 and704 may repeat, or be iterated a plurality of times in various examples, asregular uplink data512 may continue to be transmitted from the subordinate entities. However, at any given time, it may arise that the subordinate entity504 (i.e., the LoLat user504) may wish to transmit LoLat data to thescheduling entity501. Accordingly, atblock706, thescheduling entity501 may receive aLoLat scheduling request507 on thethin feedback channel506 on the FDD uplink component carrier from the LoLat user504 (i.e., the second subordinate entity504). TheLoLat scheduling request507 may include information identifying the requestingsubordinate entity504, and including any pertinent information relating to the LoLat data desired to be transmitted.
• Atblock708, thescheduling entity501 may transmit an uplinkscheduling grant modification509 on thethin control channel508 on the FDD downlink component carrier. Here, the uplinkscheduling grant modification509 may instruct the regular users such as the firstsubordinate entity502, having granted time-frequency resources for long-TTI uplink transmissions, to puncture their uplink transmissions during at least one designated short TTI. Further atblock710, thescheduling entity501 may transmit a second resource assignment or grant511 of time-frequency resources to the requesting subordinate entity (i.e., the LoLat user504) on theLoLat grant channel510 on the FDD downlink component carrier. Here, thesecond resource assignment511 may include information identifying the requestingsubordinate entity504, and information identifying time-frequency resources granted on the TDD uplink carrier for the LoLat uplink transmission. In some examples, the transmission of the uplinkscheduling grant modification509 atblock708, and the transmission of thesecond resource assignment511 atblock710, may occur simultaneously. That is, these transmissions may be multiplexed, for example, utilizing different time-frequency resources. In other examples, these transmissions may be at different times, according to the details of a particular implementation.
• Block712 represents operations at one or more subordinate entities, such asregular users502 and LoLat user(s)504. That is, in response to theuplink grant modification509, the regular users (i.e., the first subordinate entity502) may puncture their previously scheduled uplink data transmissions that utilize the long TTI. Further, in response to thesecond resource assignment511, the LoLat user(s) (i.e., the second subordinate entity504) may transmit theLoLat uplink data514 utilizing the assigned time-frequency resources on the TDD carrier.
• Atblock714, thescheduling entity501 may receive theLoLat uplink data514 transmitted from the requestingsubordinate entity504 utilizing the short TTI on the TDD carrier.
• Block716 represents operations at one or more subordinate entities, such as theregular users502 and, in some examples, LoLat user(s)504. That is, the regular subordinate entities may resume their regular uplink data transmissions on the TDD uplink carrier when transmission of the LoLat uplink data has been completed. Accordingly, at block718, thescheduling entity502 may resume receiving regular uplink data on the TDD uplink carrier from one or more subordinate entities utilizing the long TTI.
• By utilizing the above scheme, pairing a TDD carrier for uplink data transmissions with FDD carriers for control channel transmissions, athin control channel508 can enable a scheduling entity to multiplex at least two different data types or categories, having different TTIs, for uplink transmissions from a set of subordinate entities.
FDD-TDD Carrier Pairing: Multiplexing LoLat DL on Regular UL
• FIG.8 illustrates another example of pairing a TDD carrier with an FDD carrier, providing for multiplexing of LoLat downlink transmissions (i.e., transmissions from a scheduling entity) with regular uplink transmissions (i.e., transmissions from a subordinate entity) on the TDD carrier. In the illustrated example, the TDD carrier is illustrated in much the same way as the TDD carrier inFIG.4, with uplink resources shown with a plurality of users (subordinate entities) transmitting “regular” uplink data utilizing a long TTI. Here, as will be described in further detail below, the scheduling entity may modify the scheduling assignment or grant of time-frequency resources, interrupting the ongoing uplink transmissions on the TDD carrier, with downlink transmissions on the TDD carrier.
• In the illustrated example, a control channel for controlling the user data carried on the TDD carrier is carried on an FDD downlink component carrier. That is, the FDD band includes in its downlink component carrier aLoLat grant channel808, in which a subordinate entity may receive information such as aLoLat downlink grant810.
• In this example, because an FDD carrier is paired with the TDD carrier, the subordinate entity may always be receiving a control channel in the downlink direction on the FDD carrier, even while uplink transmissions are ongoing on the TDD carrier. Furthermore, in an aspect of the disclosure, if a particular subordinate entity is not currently transmitting uplink data on the TDD carrier, then that particular user may be configured always to listen for downlink data on the TDD carrier.
• In addition to the illustrated channels, time-frequency resources corresponding to the long TTI may be granted for uplink transmissions on the TDD carrier to one or more subordinate entities (e.g., Users A-F) by utilizing any suitable downlink grant channel (not necessarily one of the illustrated channels).
• At any given time, during the regular users'802 transmission of the uplink data on the TDD carrier, the scheduling entity may determine to transmit LoLat downlink data on the TDD carrier. That is, at any time, one or more subordinate entities in communication with the scheduling entity, such as aLoLat user804, may come to need LoLat communication with the network, wherein more stringent latency requirements for communication are needed than the relatively long latency resulting from the communication by regular users utilizing the long TTI. Thus, in an aspect of the present disclosure, the availability of theLoLat grant channel808 on the FDD downlink component carrier may enable dynamic multiplexing of the traffic for one or more subordinate entities that desire low latency communication (hereinafter referred to as LoLat users804), who can utilize a short TTI for data traffic, and the traffic for theregular users802, who utilize the long TTI for data traffic.
• Accordingly, on theLoLat grant channel808 on the FDD downlink component carrier, at any given time, the scheduling entity may broadcast aLoLat downlink grant810. TheLoLat downlink grant810 may be structured in any suitable manner. As one example, theLoLat downlink grant810 may include information to identify one or more LoLat users for which LoLat downlink data is being granted, information identifying time-frequency resources being allocated to the user, and any other suitable information regarding receiving and decoding of the downlink data.
• At the same time, on the TDD carrier, the scheduling entity may broadcast LoLat downlink data to the LoLat user(s)804, in accordance with theLoLat downlink grant810. That is, in some examples, theLoLat downlink grant810 and the LoLat downlink data may be transmitted at the same time, i.e., during the same short TTI. However, this is not necessarily the case, and in other examples, theLoLat downlink grant810 and the LoLat downlink data may be transmitted during completely non-overlapping short TTIs, or, as illustrated inFIG.8, a single short TTI may be utilized for theLoLat downlink grant810, which may overlap with any number (including zero) of short TTIs during which the LoLat downlink data is transmitted on the TDD carrier.
• That is, the LoLat user804 (i.e., the subordinate entity addressed in the LoLat grant810) may be configured to receive and buffer the frame on the TDD carrier, even if it is not actively receiving the regular downlink data on the TDD carrier. Upon processing the LoLat downlink grant (which may occur at the end of each long TTI), if acorresponding LoLat grant810 is received on theLoLat grant channel808, thatLoLat user804 may accordingly decode the LoLat downlink data transmitted on the TDD carrier.
• At the scheduling entity, prior to the LoLat downlink data transmission on the TDD carrier, it is receiving the regular uplink transmissions fromregular users802. At the time of the LoLat transmission, to accommodate the downlink transmission of the LoLat data on the TDD carrier, the scheduling entity may cease receiving any regular uplink data transmissions on the TDD carrier, and may begin transmitting the downlink LoLat data on the TDD carrier. Here, theregular users802 may continue transmitting their regular uplink data on the TDD carrier, since they may not have received any advance warning or indication that the scheduling entity would not be listening to their uplink transmissions on the TDD carrier during the corresponding short TTIs. Following completion of the LoLat downlink transmissions on the TDD carrier, the scheduling entity may switch back and turn its receiver on, to receive the ongoing further regular uplink data transmissions on the TDD carrier.
• In some aspects of the disclosure, theregular users802 that were interrupted by the LoLat downlink transmission might not have any indication that they were, in fact, interrupted and that their uplink transmissions were temporarily ignored. That is, the scheduling entity need not necessarily inform theregular users802 that their uplink transmissions are being interrupted/ignored to accommodate the LoLat downlink transmission.
• One potential impact of this scheme may be some degree of inter-cell interference caused by the scheduling entity, when it transmits its LoLat downlink transmission on the TDD carrier, upon other neighboring scheduling entities (e.g., where two high-power base stations neighbor one another). Furthermore, inter-user interference may occur, wherein theregular users802, which may continue to transmit their uplink data on the TDD carrier, may impact the reception performance of theLoLat user804.
• Accordingly, in a further aspect of the disclosure, theregular users802 may have the capability to monitor the FDD downlink carrier, including transmissions on theLoLat grant channel808, during their transmissions of regular uplink data on the TDD carrier. Here, in some examples, the FDD downlink carrier may include further control information directed to theregular users802, which may indicate to those users that their uplink transmissions on the TDD carrier are being interrupted for a LoLat user. In this way, theregular users802 may be enabled to cease their uplink transmissions on the TDD carrier, reducing or preventing their potential jamming of the LoLat user's804 reception of the LoLat downlink data on the TDD carrier. In a further aspect of the disclosure, a guard time806 may be utilized after the end of the LoLat downlink transmission, before theregular users802 resume their transmissions of regular uplink data on the TDD carrier. The guard time806 may be eliminated in some examples.
• FIG.9 is a call flow diagram illustrating an exemplary resource assignment and re-assignment procedure as it might occur in accordance with one example for multiplexing uplink and downlink data with different latency targets utilizing a TDD data carrier paired with FDD component carriers for control information. In this illustration, time moves forward in the downward direction, and communication signals between the illustrated entities are denoted with arrows between the lines below the respective entities. As illustrated, ascheduling entity801 is in communication with a plurality ofsubordinate entities104, including aregular user802 and aLoLat user804. Eachentity801,802, and804 is configured for communication over a TDD carrier, and an FDD carrier. The respective TDD and FDD carriers are illustrated schematically with the two vertical lines extending down from each respective entity.
• FIG.9 is described below in conjunction with a flow chart illustrated inFIG.10. That is,FIG.10 is a flow chart illustrating anexemplary process1000 for resource assignment and re-assignment utilizing a TDD data carrier paired with FDD component carriers for control information in accordance with some aspects of the present disclosure. Theprocess1000 is described from the point-of-view of ascheduling entity801, and may accordingly, as described in conjunction withFIG.9, be operational at thescheduling entity102 described above in conjunction withFIGS.1 and/or2. In other examples within the scope of the present disclosure, theprocess1000 may be operational by a general purpose processor, aprocessing system214 as described above and illustrated inFIG.2, or any suitable means for carrying out the described functions. The specific order of steps or blocks shown inFIG.10 is merely exemplary in nature, and in various aspects of the disclosure, these steps or blocks may occur in any suitable order, with some examples including two or more steps or blocks occurring simultaneously.
• Atblock1002, thescheduling entity801 may transmit a first assignment or grant820 of time-frequency resources to at least one subordinate entity on the FDD downlink component carrier. Any suitable control channel on the FDD downlink component carrier may be utilized for the first resource assignment, such as a downlink assignment channel. Here, thefirst resource assignment820 may be configured to indicate which time-frequency resource or resources are assigned to the respective subordinate entities for regular transmissions of uplink data, that is, transmissions utilizing the long TTI. In accordance with thefirst resource assignment820, at block1004, thescheduling entity801 may receiveregular uplink data822 on the TDD uplink carrier from the at least one subordinate entity (e.g., thesubordinate entities802 and804) utilizing the long TTI. Here, with reference toFIG.8, thisregular uplink data822 may correspond to the transmissions fromregular users802. As illustrated inFIG.9 with the dashed-line arrow, regular uplink data may optionally be transmitted from the secondsubordinate entity804, depending on the contents of thefirst resource assignment820 and whether the secondsubordinate entity804 is configured to transmit uplink data transmissions utilizing the long TTI.
• Theblocks1002 and1004 may repeat, or be iterated a plurality of times in various examples, asregular uplink data822 may continue to be transmitted from the subordinate entities. However, at any given time, it may arise that thescheduling entity801 may wish to transmit LoLat data to a particular subordinate entity (i.e., the LoLat user804). Accordingly, atblock1006, thescheduling entity801 may transmit an assignment or grant820 of time-frequency resources on theLoLat grant channel808 on the FDD downlink component carrier, to at least one subordinate entity (e.g., the LoLat user804). Here, theresource assignment810 may indicate for theLoLat user804 to receive LoLat downlink data from thescheduling entity801 utilizing at least one short TTJ. Specifically, theresource assignment810 may include information identifying a particularsubordinate entity804, and information identifying time-frequency resources granted on the TDD carrier for the LoLat downlink transmission.
• Atblock1008, thescheduling entity801 may optionally (as indicated by the dashed-line box1008) transmit an uplinkscheduling grant modification809 on any suitable channel on the FDD downlink component carrier. Here, the uplinkscheduling grant modification809 may instruct the regular users such as the firstsubordinate entity802, having granted time-frequency resources for long-TTI uplink transmissions, to puncture their uplink transmissions during at least one designated short TTI (i.e., the short TTI(s) corresponding to the LoLat grant810).
• Block1010 represents operations at one or more subordinate entities, such asregular users802 and LoLat user(s)804. That is, in response to theuplink grant modification809, the regular users (e.g., the first subordinate entity802) may optionally puncture their previously scheduled uplink data transmissions that utilize the long TTI. The puncturing is an optional step, operable on subordinate entities configured to monitor the control channels on the FDD downlink component carrier while transmitting uplink data on the TDD carrier.
• Atblock1012, in accordance with theresource assignment810, thescheduling entity801 may transmit theLoLat downlink data824 on the TDD carrier. In some examples, the transmission of theLoLat grant810 and theLoLat downlink data824 may occur at the same time, i.e., during the same short TTI. However, this is not necessarily the case, and in other examples, theLoLat downlink grant810 and the LoLat downlink data may be transmitted during completely non-overlapping short TTIs, or, as illustrated inFIG.8, a single short TTI may be utilized for theLoLat downlink grant810, which may overlap with any number (including zero) of short TTIs during which the LoLat downlink data is transmitted on the TDD carrier.
• Blocks1014 and1016 represent operations at one or more subordinate entities, such as theregular users802 and, in some examples, LoLat user(s)804. That is, atblock1014, the regular subordinate entities may optionally wait for a suitable gap or guard time806, after the end of the scheduledLoLat downlink transmissions824. This guard time806 may for example compensate for any propagation delay or other air interface delay, allowing full completion of the LoLat downlink transmissions to all users in the service area prior to resumption of any uplink transmissions on the TDD carrier. Atblock1016, the regular subordinate entities (i.e., regular user802) may resume their regular uplink data transmissions on the TDD carrier when transmission of the LoLat downlink data has been completed (and optionally after the guard time806). Accordingly, at block1018, thescheduling entity802 may resume receiving regular uplink data on the TDD carrier from one or more subordinate entities utilizing the long TTI.
• By utilizing the above scheme, pairing a TDD carrier for data transmissions with an FDD carrier for control channel transmissions, a thinLoLat grant channel808 can enable a scheduling entity to rapidly and dynamically control the multiplexing of uplink and downlink data on the TDD carrier having at least two different data types or categories, from a set of subordinate entities.
FDD-TDD Carrier Pairing: Multiplexing LoLat UL on Regular DL
• FIG.11 illustrates yet another example of pairing a TDD carrier with an FDD carrier, providing for multiplexing of LoLat uplink transmissions (i.e., transmissions from a subordinate entity) with regular downlink transmissions (i.e., transmissions from a scheduling entity). In the illustrated example, the TDD carrier is illustrated in much the same way as the TDD carrier inFIG.8, with downlink resources shown with a scheduling entity transmitting “regular” downlink data utilizing a long TTI to plurality of users (subordinate entities). Here, as will be described in further detail below, at the request of a subordinate entity, the scheduling entity may modify the scheduling assignment or grant of time-frequency resources, interrupting the ongoing downlink transmissions on the TDD carrier, to enable uplink transmissions (e.g., LoLat data transmissions) on the TDD carrier.
• In the illustrated example, a control channel for controlling the data carried on the TDD carrier is carried on an FDD downlink component carrier. That is, the FDD band includes in its downlink component carrier aLoLat grant channel1108 in which a subordinate entity may receive information such as aLoLat uplink grant1110, which may carry grant information for theLoLat user1104 that requested LoLat scheduling to utilize for transmitting a LoLat uplink transmission. The FDD band further includes in its downlink component carrier athin control channel1112 that may carry adownlink grant modification1114, which modifies a downlink time-frequency resource grant corresponding to the regular users'1102 downlink data reception on the TDD carrier.
• In the illustration, theLoLat grant1110 is shown as occupying a wider bandwidth than theDL grant modification1114. This represents that, while theDL grant modification1114 may simply be a few bits representing the frequency resources that are being re-allocated away from aregular user1102, and a number of short TTIs, theLoLat grant1110 may include more precise information relating to the LoLat resource assignment such as a user ID, the assignment information, a modulation and coding scheme, etc.
• Furthermore, a control channel for enabling subordinate entities to quickly send information to the scheduling entity is carried on an FDD uplink component carrier. That is, the FDD band includes in its uplink component carrier athin feedback channel1116 in which the scheduling entity may receive feedback information from subordinate entities such as aLoLat scheduling request1118.
• In addition to the illustrated channels, time-frequency resources corresponding to the long TTI may be granted for downlink transmissions on the TDD carrier to one or more subordinate entities (e.g., Users A-F) by utilizing any suitable downlink grant channel (not necessarily one of the illustrated channels). As these downlink transmissions are ongoing, if a particular subordinate entity, denoted as theLoLat user1104, wishes to request resources for a LoLat uplink transmission, this subordinate entity may transmit aLoLat scheduling request1118 on thethin feedback channel1116 on the FDD uplink component carrier. Here, theLoLat scheduling request1118 may utilize the short TTI, although this is not necessarily always the case. In response, if the scheduling entity wishes to grant the requested LoLat resource, thescheduling entity102 may transmit, on the FDD downlink component carrier, aLoLat grant1110 that informs theLoLat user1104 that transmitted the LoLatuser scheduling request1118 of its granted resources. After a suitable delay to enable the LoLat user to receive and process theLoLat grant1110 and prepare for its LoLat uplink transmission, the scheduling entity may further transmit, on thethin control channel1112, a downlink grant modification that informs theregular users1102 that are receiving downlink data transmissions on the TDD carrier, that some or all of their granted resources are being modified or removed to make way for the LoLat transmission.
• Because the data carrier is a TDD carrier, during transmission of the uplink data by theLoLat user1104, the downlink data transmissions to theregular users1102 utilizing the long TTI are punctured, ceased, or suspended. During this time, theLoLat user1104 may transmit its LoLat uplink transmission on the TDD carrier, resulting in an orthogonal multiple access scheme between regular downlink transmissions and LoLat uplink transmissions on the TDD carrier.
• In some examples, just prior to the time at which LoLat uplink transmissions are scheduled to commence, the scheduling entity may suspend its regular downlink data transmissions on the TDD carrier. That is, a gap orguard time1106 may optionally be utilized when multiplexing LoLat uplink transmissions and regular downlink transmissions on the TDD carrier. Here, thisguard time1106 may for example compensate for any propagation delay or other air interface delay, allowing full completion of the regular downlink transmissions to all users in the service area prior to the time when the LoLat uplink transmissions commence on the TDD carrier.
• In the illustration, the downlink grant modification is illustrated as appearing at the same time as the downlink resources are modified. The need for advance timing of the grant modification can be avoided because the downlink grant modification and the downlink data may be buffered and post-processed by the receiving regular UEs, as described above.
• FIG.12 is a call flow diagram illustrating an exemplary resource assignment and re-assignment procedure as it might occur in accordance with one example for multiplexing uplink and downlink data with different latency targets utilizing a TDD data carrier paired with FDD component carriers for control information. In this illustration, time moves forward in the downward direction, and communication signals between the illustrated entities are denoted with arrows between the lines below the respective entities. As illustrated, ascheduling entity1101 is in communication with a plurality ofsubordinate entities104, including aregular user1102 and aLoLat user1104. Eachentity1101,1102, and1104 is configured for communication over a TDD carrier, and an FDD carrier. The respective TDD and FDD carriers are illustrated schematically with the two vertical lines extending down from each respective entity.
• FIG.12 is described below in conjunction with a flow chart illustrated inFIG.13. That is,FIG.13 is a flow chart illustrating anexemplary process1300 for resource assignment and re-assignment utilizing a TDD data carrier paired with FDD component carriers for control information in accordance with some aspects of the present disclosure. Theprocess1300 is described from the point-of-view of ascheduling entity1101, and may accordingly, as described in conjunction withFIG.12, be operational at thescheduling entity102 described above in conjunction withFIGS.1 and/or2. In other examples within the scope of the present disclosure, theprocess1300 may be operational by a general purpose processor, aprocessing system214 as described above and illustrated inFIG.2, or any suitable means for carrying out the described functions. The specific order of steps or blocks shown inFIG.13 is merely exemplary in nature, and in various aspects of the disclosure, these steps or blocks may occur in any suitable order, with some examples including two or more steps or blocks occurring simultaneously.
• Atblock1302, thescheduling entity1101 may transmit a first assignment orgrant1120 of time-frequency resources to at least one subordinate entity on the FDD downlink component carrier. Any suitable control channel on the FDD downlink component carrier may be utilized for the first resource assignment, such as a downlink assignment channel. Here, thefirst resource assignment1120 may be configured to indicate which time-frequency resource or resources are assigned to the respective subordinate entities for receiving regular transmissions of downlink data, that is, transmissions utilizing the long TTI. In accordance with thefirst resource assignment1120, atblock1304, thescheduling entity1101 may transmitregular downlink data1122 on the TDD downlink carrier to the at least one subordinate entity (e.g., thesubordinate entities1102 and1104) utilizing the long TTI. Here, with reference toFIG.11, thisregular uplink data1122 may correspond to the downlink transmissions toregular users1102. As illustrated inFIG.12 with the dashed-line arrow, regular downlink data may optionally be transmitted to the secondsubordinate entity1104, depending on the contents of thefirst resource assignment1120 and whether the secondsubordinate entity1104 is configured to receive downlink data transmissions utilizing the long TTI.
• Theblocks1302 and1304 may repeat, or be iterated a plurality of times in various examples, asregular downlink data1122 may continue to be transmitted to the subordinate entities. However, at any given time, it may arise that the subordinate entity1104 (i.e., the LoLat user1104) may wish to transmit LoLat uplink data to thescheduling entity1101. Accordingly, atblock1306, thescheduling entity1101 may receive aLoLat scheduling request1118 on thethin feedback channel1116 on the FDD uplink component carrier from the LoLat user1104 (i.e., the second subordinate entity1104). TheLoLat scheduling request1118 may include information identifying the requestingsubordinate entity1104, and including any pertinent information relating to the LoLat data desired to be transmitted.
• Atblock1308, thescheduling entity1101 may transmit a second assignment orgrant1110 of time-frequency resources on aLoLat grant channel1108 on the FDD downlink component carrier, to the requestingsubordinate entity1104. Here, thesecond resource assignment1110 may include information identifying the requestingsubordinate entity1104, and information identifying time-frequency resources granted on the TDD uplink carrier for the LoLat uplink transmission.
• Atoptional block1310, thescheduling entity1101 may suspend its regulardownlink data transmissions1122 on the TDD carrier just prior to the time at which LoLat uplink transmissions are scheduled to commence. That is, a gap orguard time1106 may optionally be utilized when multiplexingLoLat uplink transmissions1124 andregular downlink transmissions1122 on the TDD carrier.
• Atblock1312, thescheduling entity1101 may transmit a downlinkscheduling grant modification1114 on thethin control channel1112 on the FDD downlink component carrier. Here, the downlinkscheduling grant modification1114 may instruct the regular users such as the firstsubordinate entity1102, having granted time-frequency resources for long-TTI downlink transmissions, to ignore any uplink transmissions during at least one designated short TTI. That is, since the transmissions during that TTI will be LoLat uplink transmissions from theLoLat user1104, not directed to theregular user1102, the data may not be decodable by theregular user1102 and can be ignored by theregular user1102 during post-processing of the corresponding long TTI.
• Block1314 represents operations at one or more subordinate entities, such as theLoLat user1104. That is, in response to thesecond resource assignment1110, the LoLat user (i.e., the second subordinate entity1104) may transmit theLoLat uplink data1124 utilizing the assigned time-frequency resources on the TDD carrier.
• In some examples, the transmission of the downlinkscheduling grant modification1114 atblock1312, and the transmission of theLoLat uplink data1124 on the TDD carrier at block1314 (and the corresponding suspension of downlink data transmissions on the TDD carrier, not including any guard time that may be added), may occur simultaneously. That is, these transmissions may be multiplexed, for example, utilizing different time-frequency resources. In other examples, these transmissions may be at different times, according to the details of a particular implementation. That is, theregular users1102 may be configured to buffer or cache the contents of thethin control channel1112 and the TDD carrier, such that the ignoring of data during the designated short TTI(s) may be performed during post-processing by theregular users1102.
• At block1316, thescheduling entity1101 may receive theLoLat uplink data1124 transmitted from the requestingsubordinate entity1104 utilizing the short TTI on the TDD carrier. At block1318, thescheduling entity1101 may resume transmitting theregular downlink data1122 on the TDD carrier, to one or more subordinate entities, such as theregular user1102 utilizing the long TTI.
• By utilizing the above scheme, pairing a TDD carrier for uplink data transmissions with FDD carriers for control channel transmissions, athin control channel1112 can enable a scheduling entity to multiplex uplink and downlink data having at least two different data types or categories, for set of subordinate entities.
TDD-TDD Carrier Pairing
• In a further aspect of the disclosure, rather than pairing an FDD carrier with a TDD carrier, two TDD carriers may be paired with one another in a way that can enable full duplex communication.FIG.14 illustrates one example of a pairing of two TDD component carriers (CC). In this illustration, a first CC (component carrier 1 or CC1) is paired with a second CC (component carrier 2 or CC2). The horizontal axis represents time, and the vertical axis represents frequency (not to scale). Both CC1 and CC2 are TDD carriers, wherein uplink time slots, indicated with a U, are time-multiplexed with downlink time slots, indicated with a D on each respective carrier. Additionally, some time slots are identified as special time slots, and indicated with an S, described further below. Herein, a time slot may correspond to any suitable duration of time, and may correspond to other nomenclature such as a transmission time interval (TTI), subframe, frame, symbol duration, etc.
• If only CC1 were usable by a communication device, it is seen that only downlink, uplink, or special time slots exist at any single time. The illustration shows two different types of frames, identified as Configuration A and Configuration B. In the first frame, identified as Configuration A, there is the same number of uplink time slots U and downlink time slots D, with two of the time slots identified as special time slots S. In the second frame, identified as Configuration B, most of the time slots are downlink time slots D, with one uplink time slot U and one special time slot S. The third frame is shown as another Configuration A frame. These configurations are merely one example, which corresponds to some existing configurations defined in TD-LTE standards.
• At any moment, for example, during the second frame identified as Configuration B, if the communication device has a need to send feedback on the uplink, it may not be presented with such an opportunity, because it is faced with a long stretch of downlink-only time slots. Here, the feedback would need to be buffered at least until the next opportunity is presented in the third time slot of the third frame.
• Therefore, in an aspect of the present disclosure, the first TDD component carrier CC1 may be paired with a second TDD component carrier CC2. Here, CC2 may implement an inverse, conjugate, or complementary transmit/receive organization relative to that of CC1. In the present disclosure, the terms inverse, complementary, and conjugate are utilized interchangeably, generally referring to a configuration wherein at least some of the downlink time slots D in CC1 are paired with uplink time slots U in CC2, and at least some of the uplink time slots U in CC1 are paired with downlink time slots D in CC2. The configuration illustrated is merely exemplary in nature, and other configurations may be utilized within the scope of the present disclosure, some of which may pair all time slots across the two component carriers, and others of which may include some unpaired uplink/downlink time slots.
• As shown, the Configuration A frame is paired with a Configuration −A frame, wherein Configuration −A represents the inverse (or conjugate) of Configuration A. Likewise, the Configuration B frame is paired with a Configuration −B frame.
• The special time slot, indicated with the S, in the illustrated example may be utilized for downlink-to-uplink switching. That is, with reference to communication by asubordinate entity104, when utilizing a TDD carrier, where the timing for both the uplink and downlink transmissions is driven by ascheduling entity102, there may be a need for a certain time gap when transitioning from a downlink time slot D and an uplink time slot U. That is, there is a certain propagation delay between the transmission of the downlink time slot D from thescheduling entity102 to thesubordinate entity104, as well as between the transmission of the uplink time slot U from thesubordinate entity104 to thescheduling entity102. To account for these propagation delays, special time slots S insert a gap between the end of a downlink time slot D and the beginning of an uplink time slot U, so that thescheduling entity102 and thesubordinate entity104 can maintain synchronization. Here, the gap may correspond to a time when neither uplink nor downlink communications occur. The length of the gap in the special time slot S can be configured in accordance with the size of the cell.
• In various aspects of the disclosure, the special time slots S in one component carrier can be paired with any suitable time slot on its paired component carrier, including a downlink time slot D, an uplink time slot U, or another special time slot S. In some examples, such as the illustrated example inFIG.14, each of the special time slots S in one component carrier (CC1) may be mapped (e.g., time-aligned) to a respective downlink time slot in its paired component carrier (CC2). However, this is merely one example, and is not intended to be limiting in nature.
• In a further example, special time slots S may be inserted in the inverse or paired component carrier CC2 as needed, in between transitions from downlink time slots to uplink time slots.
• In some examples, the paired component carriers may be inter-band carriers. That is, each of the component carriers CC1 and CC2 may lie in a different band from that of its paired component carrier. By placing the component carriers in different bands, the RF functionality at a device such as ascheduling entity102 and asubordinate entity104 can be improved, reducing interference and de-sense between the respective carriers. This is not a requirement, however, and intra-band component carriers may be utilized within the scope of the present disclosure; however, it may be beneficial in such case to choose component carriers that are as far apart in frequency as feasible.
• The illustration inFIG.14 shows, as one example, two paired TDD component carriers having essentially the same bandwidth. That is, each component carrier has the same width in the vertical frequency dimension. Here, if two TDD component carriers of the same bandwidth are paired with one another, one of the benefits of a conventional TDD carrier may be lost. That is, conventional TDD has an advantage that, depending on the characteristics of the traffic, it can be decided how many time slots can be used for downlink traffic, and how many time slots can be used for uplink traffic, enabling a dynamic assignment and providing for the most efficient use of available resources. This flexibility would be lost if all time slots in one direction in one component carrier are paired with time slots in the other direction in its paired component carrier, if the paired component carriers have the same bandwidth. That is, with such a configuration the sum of downlink time slots on both component carriers would be equal to the sum of uplink time slots on both component carriers.
• FIG.15 illustrates a conjugate pairing of component carriers in accordance with a further aspect of the present disclosure, configured to afford a degree of flexibility in the allocation of uplink and downlink time slots.
• The reason full duplex is desired is not necessarily for the benefit of the traffic channels. Rather, as described above, full duplex communication may be desirable because it can provide additional control, e.g., by the enablement of thin feedback and a thin grant for dynamic modification of the communication.
• Accordingly, as illustrated inFIG.14, a first TDD component carrier, CC1, having a wide bandwidth (e.g., 100 MHz) may be paired with a second TDD component carrier, CC2, having a narrow bandwidth (e.g., 10 MHz). The ratio between the bandwidth of the two component carriers need not be the 10:1 ratio given here, but any suitable ratio may be utilized within the scope of the present disclosure. The choice of the ratio may be made in accordance with characteristics of the traffic being carried on the uplink and downlink, such as the degree of asymmetry between uplink and downlink traffic. For example, traffic that is substantially heavier on the downlink side could be accommodated by deploying a larger number of downlink time slots on the wider bandwidth component carrier.
• In some examples, the bandwidth of one or both of the TDD component carriers may be selected according to the bandwidth desired or needed; and in some examples, the bandwidth of one or both of the TDD component carriers may be configurable by the scheduling entity or the subordinate entity.
TDD-TDD Carrier Pairing: Multiplexing LoLat UL on Regular UL
• FIG.16 illustrates one example of pairing a first TDD component carrier with a second TDD component carrier, providing for multiplexing of LoLat uplink transmissions with regular uplink transmissions (i.e., transmissions from a subordinate entity) on the primary TDD component carrier. In the illustrated example, the primary TDD component carrier is illustrated in much the same way as the TDD carrier inFIG.5, with uplink resources allocated to different users being represented by the large blocks spanning a long TTI. Here, as will be described in further detail below, a subordinate entity (e.g., a UE) may request, and be granted, resources for a LoLat transmission that may be multiplexed with the regular uplink transmissions from other users. At the bottom of the figure, resources on a second TDD component carrier are allocated for use.
• In the illustrated example, control channels for controlling the uplink data transmissions on the primary TDD component carrier are carried on the secondary TDD component carrier. That is, the secondary TDD component carrier includes athin control channel1606, which may carry uplinkgrant modification information1608 that modifies an uplink resource grant corresponding to the subordinate entity (i.e., the regular user1602) uplink transmission on the primary TDD component carrier. Further, the secondary TDD component carrier includes a LoLat grant channel1610, which may carrygrant information1612 for the subordinate entity that requests LoLat scheduling (i.e., the LoLat user1604) to utilize in a LoLat uplink transmission on the primary TDD component carrier.
• Further, in addition to data carriers, the primary TDD component carrier includes athin feedback channel1614 that a subordinate entity (i.e., the LoLat user1604) can utilize to transmit information such as aLoLat scheduling request1616.
• In addition to the illustrated channels, time-frequency resources corresponding to the long TTI may be granted for uplink transmissions on the primary TDD component carrier to one or more subordinate entities (e.g., Users A-F) by utilizing any suitable downlink grant channel (not necessarily one of the illustrated channels). As these uplink transmissions are ongoing, if a particular subordinate entity, denoted as theLoLat user1604, wishes to request resources for a LoLat uplink transmission, this subordinate entity may transmit aLoLat scheduling request1616 on thethin feedback channel1614 on the primary TDD component carrier. Here, theLoLat scheduling request1616 may utilize the short TTI, although this is not necessarily always the case. In response, if the scheduling entity wishes to grant the requested LoLat resource, thescheduling entity102 may transmit, on the secondary TDD component carrier, anuplink grant modification1608 on thethin control channel1606, and aLoLat grant1612 on the LoLat grant channel1610. Here, the anuplink grant modification1608 on thethin control channel1606 may be configured to inform all of the subordinate entities that are utilizing granted uplink time-frequency resources on the primary TDD component carrier that some or all of their granted resources are being modified or removed, to make way for the LoLat transmission. Further, theLoLat grant1612 on the LoLat grant channel1610 may be configured to inform the subordinate entity that transmitted the LoLat scheduling request (i.e., the LoLat user1604) of its granted time-frequency resources. In the illustration, theLoLat grant1612 is shown as occupying a wider bandwidth than theUL grant modification1608. This represents that, while theUL grant modification1608 may simply be a few bits representing the frequency resources that are being re-allocated away from aregular user1602, and a number of short TTIs, theLoLat grant1612 may include more precise information relating to the LoLat resource assignment such as a user ID, the assignment information, a modulation and coding scheme, etc. Accordingly, theLoLat user1604 may transmit its LoLat uplink transmission on the primary TDD component carrier, while other regular users1602 (such as Users D, E, and F) may cease their uplink transmissions, resulting in an orthogonal multiple access scheme between regular and LoLat uplink transmissions on the TDD carrier.
• In this example, the regular users1602 (e.g., subordinate entities104), whose uplink resources were punctured, may benefit from having an ability to quickly decode theuplink grant modification1608. That is, the time from when theuplink grant modification1608 is received at theregular user1602, until that user ceases its uplink transmissions, may be very short. To accommodate the quick reaction time, thesubordinate entity104 may be configured for a fast suspension of its uplink transmissions, e.g., by driving a zero input to a power amplifier within thetransceiver310, or in another example, being capable of quickly turning off the power amplifier. Furthermore, theLoLat user1604 also may have only a brief time from the receiving of itsLoLat uplink grant1612, and its transmission of LoLat uplink data. Accordingly, fast processing of theLoLat grant1612 and transmission utilizing the scheduled time-frequency resources would be beneficial and reduce latency.
• FIG.17 is a call flow diagram illustrating an exemplary resource assignment and re-assignment procedure as it might occur in accordance with one example for multiplexing uplink data with different latency targets utilizing a primary TDD component carrier paired with a secondary TDD component carrier. In this illustration, time moves forward in the downward direction, and communication signals between the illustrated entities are denoted with arrows between the lines below the respective entities. As illustrated, ascheduling entity1601 is in communication with a plurality ofsubordinate entities104, including aregular user1602 and aLoLat user1604. Eachentity1601,1602, and1604 is configured for communication over a primary TDD component carrier, and a secondary TDD component carrier. The respective primary and secondary TDD component carriers are illustrated schematically with the two vertical lines extending down from each respective entity.
• FIG.17 is described below in conjunction with a flow chart illustrated inFIG.18. That is,FIG.18 is a flow chart illustrating anexemplary process1800 for resource assignment and re-assignment in accordance with some aspects of the present disclosure. Theprocess1800 is described from the point-of-view of ascheduling entity1601, and may accordingly, as described in conjunction withFIG.17, be operational at thescheduling entity102 described above in conjunction withFIGS.1 and/or2. In other examples within the scope of the present disclosure, theprocess1800 may be operational by a general purpose processor, aprocessing system214 as described above and illustrated inFIG.2, or any suitable means for carrying out the described functions. The specific order of steps or blocks shown inFIG.18 is merely exemplary in nature, and in various aspects of the disclosure, these steps or blocks may occur in any suitable order, with some examples including two or more steps or blocks occurring simultaneously.
• Atblock1802, thescheduling entity1601 may transmit a first assignment orgrant1620 of time-frequency resources to at least one subordinate entity on the secondary TDD component carrier. Any suitable control channel may be utilized for the first resource assignment, such as a downlink assignment channel. Here, thefirst resource assignment1620 may be configured to indicate which time-frequency resource or resources are assigned to the respective subordinate entities for regular transmissions of uplink data, that is, transmissions utilizing the long TTI. In accordance with thefirst resource assignment1620, at block1804, thescheduling entity1601 may receiveregular uplink data1622 on the primary TDD component carrier from the at least one subordinate entity (e.g., thesubordinate entities1602 and1604) utilizing the long TTI. Here, with reference toFIG.16, thisregular uplink data1622 may correspond to the transmissions fromregular users1602. As illustrated inFIG.17 with the dashed-line arrow, regular uplink data may optionally be transmitted from the secondsubordinate entity1604, depending on the contents of thefirst resource assignment1620 and whether the secondsubordinate entity1604 is configured to transmit uplink data transmissions utilizing the long TTI.
• Theblocks1802 and1804 may repeat, or be iterated a plurality of times in various examples, asregular uplink data1622 may continue to be transmitted from the subordinate entities. However, at any given time, it may arise that the subordinate entity1604 (i.e., the LoLat user1604) may wish to transmit LoLat data to thescheduling entity1601. Accordingly, at block1806, thescheduling entity1601 may receive aLoLat scheduling request1616 on thethin feedback channel1614 on the primary TDD component carrier from the LoLat user1604 (i.e., the second subordinate entity1604). TheLoLat scheduling request1616 may include information identifying the requestingsubordinate entity1604, and including any pertinent information relating to the LoLat data desired to be transmitted.
• Atblock1808, thescheduling entity1601 may transmit an uplinkscheduling grant modification1608 on thethin control channel1606 on the secondary TDD component carrier. Here, the uplinkscheduling grant modification1608 may instruct the regular users such as the firstsubordinate entity1602, having granted time-frequency resources for long-TTI uplink transmissions, to puncture their uplink transmissions during at least one designated short TTI. Further atblock1810, thescheduling entity1601 may transmit a second resource assignment orgrant1612 of time-frequency resources to the requesting subordinate entity (i.e., the LoLat user1604) on the LoLat grant channel1610 on the secondary TDD component carrier. Here, thesecond resource assignment1612 may include information identifying the requestingsubordinate entity1604, and information identifying time-frequency resources granted on the primary TDD component carrier for the LoLat uplink transmission. In some examples, the transmission of the uplinkscheduling grant modification1608 atblock1808, and the transmission of thesecond resource assignment1612 atblock1810, may occur simultaneously. That is, these transmissions may be multiplexed, for example, utilizing different time-frequency resources. In other examples, these transmissions may be at different times, according to the details of a particular implementation.
• Block1812 represents operations at one or more subordinate entities, such asregular users1602 and LoLat user(s)1604. That is, in response to theuplink grant modification1608, the regular users (i.e., the first subordinate entity1602) may puncture their previously scheduled uplink data transmissions that utilize the long TTI. Further, in response to thesecond resource assignment1612, the LoLat user(s) (i.e., the second subordinate entity1604) may transmit theLoLat uplink data1624 utilizing the assigned time-frequency resources on the primary TDD component carrier.
• Atblock1814, thescheduling entity1601 may receive theLoLat uplink data1624 transmitted from the requestingsubordinate entity1604 utilizing the short TTI on the primary TDD component carrier.
• Block1816 represents operations at one or more subordinate entities, such as theregular users1602 and, in some examples, LoLat user(s)1604. That is, the regular subordinate entities may resume their regular uplink data transmissions on the primary TDD component carrier when transmission of theLoLat uplink data1624 has been completed. Accordingly, atblock1818, thescheduling entity1602 may resume receivingregular uplink data1622 on the primary TDD component carrier from one or more subordinate entities utilizing the long TTI.
• By utilizing the above scheme, pairing a primary TDD carrier for uplink data transmissions and uplink feedback transmissions, with a secondary TDD component carrier for control channel transmissions, athin control channel1606 can enable a scheduling entity to multiplex at least two different data types or categories, having different TTIs, for uplink transmissions from a set of subordinate entities.
TDD-TDD Carrier Pairing: Multiplexing LoLat DL on Regular UL
• FIG.19 illustrates another example of TDD-TDD component carrier pairing, providing for multiplexing of LoLat downlink transmissions (i.e., transmissions from a scheduling entity) with regular uplink transmissions (i.e., transmissions from a subordinate entity) on the primary TDD component carrier. In the illustrated example, the primary TDD component carrier is illustrated in much the same way as the TDD carrier inFIG.4, with uplink resources shown with a plurality of users (subordinate entities) transmitting “regular” uplink data utilizing a long TTI. Here, as will be described in further detail below, the scheduling entity may modify the scheduling assignment or grant of time-frequency resources, interrupting the ongoing uplink transmissions on the primary TDD component carrier, with downlink transmissions on the primary TDD component carrier.
• In the illustrated example, a control channel for controlling the user data carried on the primary TDD component carrier is carried on a secondary TDD component carrier. That is, the secondary TDD component carrier includes aLoLat grant channel1910, in which a subordinate entity may receive information such as aLoLat downlink grant1912.
• In this example, because a secondary TDD component carrier is paired with the primary TDD component carrier (e.g., utilizing the conjugate pairing described above), the subordinate entity may always (or most of the time) be receiving a control channel in the downlink direction on the secondary TDD component carrier, even while uplink transmissions are ongoing on the primary TDD component carrier. Furthermore, in an aspect of the disclosure, if a particular subordinate entity is not currently transmitting uplink data on the primary TDD component carrier, then that particular user may be configured always to listen for downlink data on the primary TDD component carrier.
• In addition to the illustrated channels, time-frequency resources corresponding to the long TTI may be granted for uplink transmissions on the primary TDD component carrier to one or more subordinate entities (e.g., Users A-F) by utilizing any suitable downlink grant channel (not necessarily one of the illustrated channels).
• At any given time, during the regular users'1902 transmission of the uplink data on the primary TDD component carrier, the scheduling entity may determine to transmit LoLat downlink data on the primary TDD component carrier. That is, at any time, one or more subordinate entities in communication with the scheduling entity, such as aLoLat user1904, may come to need LoLat communication with the network, wherein more stringent latency requirements for communication are needed than the relatively long latency resulting from the communication by regular users utilizing the long TTI. Thus, in an aspect of the present disclosure, the availability of theLoLat grant channel1910 on the secondary TDD component carrier may enable dynamic multiplexing of the traffic for one or more subordinate entities that desire low latency communication (hereinafter referred to as LoLat users1904), who can utilize a short TTI for data traffic, and the traffic for theregular users1902, who utilize the long TTI for data traffic.
• Accordingly, on theLoLat grant channel1910 on the secondary TDD component carrier, at any given time, the scheduling entity may broadcast aLoLat downlink grant1912. TheLoLat downlink grant1912 may be structured in any suitable manner. As one example, theLoLat downlink grant1912 may include information to identify one or more LoLat users for which LoLat downlink data is being granted, information identifying time-frequency resources being allocated to the user, and any other suitable information regarding receiving and decoding of the downlink data.
• At the same time, on the primary TDD component carrier, the scheduling entity may broadcast LoLat downlink data to the LoLat user(s)1904, in accordance with theLoLat downlink grant1912. That is, in some examples, theLoLat downlink grant1912 and the LoLat downlink data may be transmitted at the same time, i.e., during the same short TTI. However, this is not necessarily the case, and in other examples, theLoLat downlink grant1912 and the LoLat downlink data may be transmitted during completely non-overlapping short TTIs, or, as illustrated inFIG.19, a single short TTI may be utilized for theLoLat downlink grant1912, which may overlap with any number (including zero) of short TTIs during which the LoLat downlink data is transmitted on the primary TDD component carrier.
• That is, the LoLat user1904 (i.e., the subordinate entity addressed in the LoLat grant1912) may be configured to receive and buffer the frame on the primary TDD component carrier, even if it is not actively receiving the regular downlink data on the primary TDD component carrier. Upon processing the LoLat downlink grant (which may occur at the end of each long TTI), if acorresponding LoLat grant1912 is received on theLoLat grant channel1910, thatLoLat user1904 may accordingly decode the LoLat downlink data transmitted on the primary TDD component carrier.
• At the scheduling entity, prior to the LoLat downlink data transmission on the primary TDD component carrier, it is receiving the regular uplink transmissions fromregular users1902. At the time of the LoLat transmission, to accommodate the downlink transmission of the LoLat data on the primary TDD component carrier, the scheduling entity may cease receiving any regular uplink data transmissions on the primary TDD component carrier, and may begin transmitting the downlink LoLat data on the primary TDD component carrier. Here, theregular users1902 may continue transmitting their regular uplink data on the primary TDD component carrier, since they may not have received any advance warning or indication that the scheduling entity would not be listening to their uplink transmissions on the primary TDD component carrier during the corresponding short TTIs. Following completion of the LoLat downlink transmissions on the primary TDD component carrier, the scheduling entity may switch back and turn its receiver on, to receive the ongoing further regular uplink data transmissions on the primary TDD component carrier.
• In some aspects of the disclosure, theregular users1902 that were interrupted by the LoLat downlink transmission might not have any indication that they were, in fact, interrupted and that their uplink transmissions were temporarily ignored. That is, the scheduling entity need not necessarily inform theregular users1902 that their uplink transmissions are being interrupted/ignored to accommodate the LoLat downlink transmission.
• One potential impact of this scheme may be some degree of inter-cell interference caused by the scheduling entity, when it transmits its LoLat downlink transmission on the primary TDD component carrier, upon other neighboring scheduling entities (e.g., where two high-power base stations neighbor one another). Furthermore, inter-user interference may occur, wherein theregular users1902, which may continue to transmit their uplink data on the primary TDD component carrier, may impact the reception performance of theLoLat user1904.
• Accordingly, in a further aspect of the disclosure, theregular users1902 may have the capability to monitor the secondary TDD component carrier, including transmissions on theLoLat grant channel1910, during their transmissions of regular uplink data on the primary TDD component carrier. Here, in some examples, the secondary TDD component carrier may include further control information directed to theregular users1902, which may indicate to those users that their uplink transmissions on the primary TDD component carrier are being interrupted for a LoLat user. In this way, theregular users1902 may be enabled to cease their uplink transmissions on the primary TDD component carrier, reducing or preventing their potential jamming of the LoLat user's1904 reception of the LoLat downlink data on the primary TDD component carrier. In a further aspect of the disclosure, a guard time1906 may be utilized after the end of the LoLat downlink transmission, before theregular users1902 resume their transmissions of regular uplink data on the primary TDD component carrier. The guard time1906 may be eliminated in some examples.
• FIG.20 is a call flow diagram illustrating an exemplary resource assignment and re-assignment procedure as it might occur in accordance with one example for multiplexing uplink and downlink data with different latency targets utilizing a paired set of primary and secondary TDD carriers. In this illustration, time moves forward in the downward direction, and communication signals between the illustrated entities are denoted with arrows between the lines below the respective entities. As illustrated, ascheduling entity1901 is in communication with a plurality ofsubordinate entities104, including aregular user1902 and aLoLat user1904. Eachentity1901,1902, and1904 is configured for communication over primary and secondary TDD component carriers. The respective primary and secondary TDD component carriers are illustrated schematically with the two vertical lines extending down from each respective entity.
• FIG.20 is described below in conjunction with a flow chart illustrated inFIG.21. That is,FIG.21 is a flow chart illustrating anexemplary process2100 for resource assignment and re-assignment utilizing a paired set of primary and secondary TDD carriers in accordance with some aspects of the present disclosure. Theprocess2100 is described from the point-of-view of ascheduling entity1901, and may accordingly, as described in conjunction withFIG.20, be operational at thescheduling entity102 described above in conjunction withFIGS.1 and/or2. In other examples within the scope of the present disclosure, theprocess2100 may be operational by a general purpose processor, aprocessing system214 as described above and illustrated inFIG.2, or any suitable means for carrying out the described functions. The specific order of steps or blocks shown inFIG.21 is merely exemplary in nature, and in various aspects of the disclosure, these steps or blocks may occur in any suitable order, with some examples including two or more steps or blocks occurring simultaneously.
• Atblock2102, thescheduling entity1901 may transmit a first assignment orgrant1920 of time-frequency resources to at least one subordinate entity on the secondary TDD component carrier. Any suitable control channel on the secondary TDD component carrier may be utilized for thefirst resource assignment1920, such as a downlink assignment channel. Here, thefirst resource assignment1920 may be configured to indicate which time-frequency resource or resources are assigned to the respective subordinate entities for regular transmissions of uplink data, that is, transmissions utilizing the long TTI. In accordance with thefirst resource assignment1920, atblock2104, thescheduling entity1901 may receiveregular uplink data1922 on the primary TDD component carrier from the at least one subordinate entity (e.g., thesubordinate entities1902 and1904) utilizing the long TTI. Here, with reference toFIG.19, thisregular uplink data1922 may correspond to the transmissions fromregular users1902. As illustrated inFIG.20 with the dashed-line arrow,regular uplink data1922 may optionally be transmitted from the secondsubordinate entity1904, depending on the contents of thefirst resource assignment1920 and whether the secondsubordinate entity1904 is configured to transmit uplink data transmissions utilizing the long TTI.
• Theblocks2102 and2104 may repeat, or be iterated a plurality of times in various examples, asregular uplink data1922 may continue to be transmitted from the subordinate entities. However, at any given time, it may arise that thescheduling entity1901 may wish to transmit LoLat data to a particular subordinate entity (i.e., the LoLat user1904). Accordingly, atblock2106, thescheduling entity1901 may transmit an assignment orgrant1912 of time-frequency resources on theLoLat grant channel1910 on the secondary TDD component carrier, to at least one subordinate entity (e.g., the LoLat user1904). Here, theresource assignment1912 may indicate for theLoLat user1904 to receive LoLat downlink data from thescheduling entity1901 utilizing at least one short TTI. Specifically, theresource assignment1912 may include information identifying a particularsubordinate entity1904, and information identifying time-frequency resources granted on the primary TDD component carrier for the LoLat downlink transmission.
• Atblock2108, thescheduling entity1901 may optionally (as indicated by the dashed-line box2108) transmit an uplinkscheduling grant modification1924 on any suitable channel, e.g., on the secondary TDD component carrier. Here, the uplinkscheduling grant modification1924 may instruct the regular users such as the firstsubordinate entity1902, having granted time-frequency resources for long-TTI uplink transmissions, to puncture their uplink transmissions during at least one designated short TTI (i.e., the short TTI(s) corresponding to the LoLat grant1912).
• Block2110 represents operations at one or more subordinate entities, such asregular users1902 and LoLat user(s)1904. That is, in response to theuplink grant modification1924, the regular users (e.g., the first subordinate entity1902) may optionally puncture their previously scheduled uplink data transmissions that utilize the long TTI. The puncturing is an optional step, operable on subordinate entities configured to monitor the control channels on the secondary TDD component carrier while transmitting uplink data on the primary TDD component carrier.
• Atblock2112, in accordance with theresource assignment1912, thescheduling entity1901 may transmit theLoLat downlink data1926 on the primary TDD component carrier. In some examples, the transmission of theLoLat grant1912 and theLoLat downlink data1926 may occur at the same time, i.e., during the same short TTI. However, this is not necessarily the case, and in other examples, theLoLat downlink grant1912 and the LoLat downlink data may be transmitted during completely non-overlapping short TTIs, or, as illustrated inFIG.19, a single short TTI may be utilized for theLoLat downlink grant1912, which may overlap with any number (including zero) of short TTIs during which the LoLat downlink data is transmitted on the primary TDD component carrier.
• Blocks2114 and2116 represent operations at one or more subordinate entities, such as theregular users1902 and, in some examples, LoLat user(s)1904. That is, atblock2114, the regular subordinate entities may optionally wait for a suitable gap or guard time1906, after the end of the scheduledLoLat downlink transmissions1926. This guard time1906 may for example compensate for any propagation delay or other air interface delay, allowing full completion of the LoLat downlink transmissions to all users in the service area prior to resumption of any uplink transmissions on the primary TDD component carrier. Atblock2116, the regular subordinate entities (i.e., regular user1902) may resume their regular uplink data transmissions on the primary TDD component carrier when transmission of the LoLat downlink data has been completed (and optionally after the guard time1906). Accordingly, atblock2118, thescheduling entity1902 may resume receiving regular uplink data on the primary TDD component carrier from one or more subordinate entities utilizing the long TTI.
• By utilizing the above scheme, pairing primary and secondary TDD component carriers, a thinLoLat grant channel1912 can enable a scheduling entity to rapidly and dynamically control the multiplexing of uplink and downlink data on the primary TDD component carrier having at least two different data types or categories, from a set of subordinate entities.
TDD-TDD Carrier Pairing: Multiplexing LoLat UL on Regular DL
• FIG.22 illustrates yet another example of pairing primary and secondary TDD component carriers, providing for multiplexing of LoLat uplink transmissions (i.e., transmissions from a subordinate entity) with regular downlink transmissions (i.e., transmissions from a scheduling entity). In the illustrated example, the primary TDD component carrier is illustrated in much the same way as the TDD carrier inFIG.8, with downlink resources shown with a scheduling entity transmitting regular downlink data utilizing a long TTI to plurality of users (subordinate entities). Here, as will be described in further detail below, at the request of a subordinate entity, the scheduling entity may modify the scheduling assignment or grant of time-frequency resources, interrupting the ongoing downlink transmissions on the primary TDD component carrier, to enable uplink transmissions (e.g., LoLat data transmissions) on the primary TDD component carrier.
• In the illustrated example, control channels for controlling the data carried on the primary TDD component carrier may be carried on either or both of the primary and/or secondary TDD component carriers. For example, as illustrated the primary TDD component carrier includes aLoLat grant channel2212 in which a subordinate entity may receive information such as aLoLat uplink grant2214, which may carry grant information for theLoLat user2204 that requested LoLat scheduling to utilize for transmitting a LoLat uplink transmission. The primary TDD component carrier further includes athin control channel2216 that may carry adownlink grant modification2218, which modifies a downlink time-frequency resource grant corresponding to the regular users'2202 downlink data reception on the primary TDD component carrier.
• In the illustration, theLoLat grant2214 is shown as occupying a wider bandwidth than theDL grant modification2218. This represents that, while theDL grant modification2218 may simply be a few bits representing the frequency resources that are being re-allocated away from aregular user2202, and a number of short TTIs, theLoLat grant2214 may include more precise information relating to the LoLat resource assignment such as a user ID, the assignment information, a modulation and coding scheme, etc.
• Furthermore, a control channel for enabling subordinate entities to quickly send information to the scheduling entity is carried on the secondary TDD component carrier. That is, the secondary TDD component carrier includes athin feedback channel2208 in which the scheduling entity may receive feedback information from subordinate entities such as aLoLat scheduling request2210.
• In addition to the illustrated channels, time-frequency resources corresponding to the long TTI may be granted for downlink transmissions on the primary TDD component carrier to one or more subordinate entities (e.g., Users A-F) by utilizing any suitable downlink grant channel (not necessarily one of the illustrated channels). As these downlink transmissions are ongoing, if a particular subordinate entity, denoted as theLoLat user2204, wishes to request resources for a LoLat uplink transmission, this subordinate entity may transmit aLoLat scheduling request2210 on thethin feedback channel2208 on the secondary TDD component carrier. Here, theLoLat scheduling request2210 may utilize the short TTI, although this is not necessarily always the case. In response, if the scheduling entity wishes to grant the requested LoLat resource, thescheduling entity102 may transmit, on the primary TDD component carrier, aLoLat grant2214 that informs theLoLat user2204 that transmitted the LoLatuser scheduling request2210 of its granted resources. After a suitable delay to enable the LoLat user to receive and process theLoLat grant2214 and prepare for its LoLat uplink transmission, the scheduling entity may further transmit, on thethin control channel2216, adownlink grant modification2218 that informs theregular users2202 that are receiving downlink data transmissions on the primary TDD component carrier, that some or all of their granted resources are being modified or removed to make way for the LoLat transmission.
• Because the data carrier is a TDD carrier, during transmission of the uplink data by theLoLat user2204, the downlink data transmissions to theregular users2202 utilizing the long TTI are punctured, ceased, or suspended. During this time, theLoLat user2204 may transmit its LoLat uplink transmission on the primary TDD component carrier, resulting in an orthogonal multiple access scheme between regular downlink transmissions and LoLat uplink transmissions on the primary TDD component carrier.
• In some examples, just prior to the time at which LoLat uplink transmissions are scheduled to commence, the scheduling entity may suspend its regular downlink data transmissions on the primary TDD component carrier. That is, a gap orguard time2206 may optionally be utilized when multiplexing LoLat uplink transmissions and regular downlink transmissions on the primary TDD component carrier. Here, thisguard time2206 may for example compensate for any propagation delay or other air interface delay, allowing full completion of the regular downlink transmissions to all users in the service area prior to the time when the LoLat uplink transmissions commence on the primary TDD component carrier.
• In the illustration, thedownlink grant modification2218 is illustrated as appearing at the same time as the downlink resources are modified. The need for advance timing of the grant modification can be avoided because thedownlink grant modification2218 and the downlink data may be buffered and post-processed by the receivingregular users2202, as described above.
• FIG.23 is a call flow diagram illustrating an exemplary resource assignment and re-assignment procedure as it might occur in accordance with one example for multiplexing uplink and downlink data with different latency targets utilizing a paired set of primary and secondary TDD component carriers. In this illustration, time moves forward in the downward direction, and communication signals between the illustrated entities are denoted with arrows between the lines below the respective entities. As illustrated, ascheduling entity2201 is in communication with a plurality ofsubordinate entities104, including aregular user2202 and aLoLat user2204. Eachentity2201,2202, and2204 is configured for communication over primary and secondary TDD component carriers. The respective primary and secondary TDD component carriers are illustrated schematically with the two vertical lines extending down from each respective entity.
• FIG.23 is described below in conjunction with a flow chart illustrated inFIG.24. That is,FIG.24 is a flow chart illustrating anexemplary process2400 for resource assignment and re-assignment utilizing a paired set of primary and secondary TDD carriers in accordance with some aspects of the present disclosure. Theprocess2400 is described from the point-of-view of ascheduling entity2201, and may accordingly, as described in conjunction withFIG.23, be operational at thescheduling entity102 described above in conjunction withFIGS.1 and/or2. In other examples within the scope of the present disclosure, theprocess2400 may be operational by a general purpose processor, aprocessing system214 as described above and illustrated inFIG.2, or any suitable means for carrying out the described functions. The specific order of steps or blocks shown inFIG.24 is merely exemplary in nature, and in various aspects of the disclosure, these steps or blocks may occur in any suitable order, with some examples including two or more steps or blocks occurring simultaneously.
• Atblock2402, thescheduling entity2201 may transmit a first assignment orgrant2220 of time-frequency resources to at least one subordinate entity on the secondary TDD component carrier. Any suitable control channel on the secondary TDD component carrier (or, in some examples, on the primary TDD component carrier) may be utilized for thefirst resource assignment2220, such as a downlink assignment channel. Here, thefirst resource assignment2220 may be configured to indicate which time-frequency resource or resources are assigned to the respective subordinate entities for receiving regular transmissions of downlink data, that is, transmissions utilizing the long TTI. In accordance with thefirst resource assignment2220, atblock2404, thescheduling entity2201 may transmitregular downlink data2222 on the primary TDD component carrier to the at least one subordinate entity (e.g., thesubordinate entities2202 and2204) utilizing the long TTI. Here, with reference toFIG.22, thisregular uplink data2222 may correspond to the downlink transmissions toregular users2202. As illustrated inFIG.23 with the dashed-line arrow,regular downlink data2222 may optionally be transmitted to the secondsubordinate entity2204, depending on the contents of thefirst resource assignment2220 and whether the secondsubordinate entity2204 is configured to receive downlink data transmissions utilizing the long TTI.
• Theblocks2402 and2404 may repeat, or be iterated a plurality of times in various examples, asregular downlink data2222 may continue to be transmitted to the subordinate entities. However, at any given time, it may arise that the subordinate entity2204 (i.e., the LoLat user2204) may wish to transmit LoLat uplink data to thescheduling entity2201. Accordingly, atblock2406, thescheduling entity2201 may receive aLoLat scheduling request2210 on thethin feedback channel2208 on the secondary TDD component carrier from the LoLat user2204 (i.e., the second subordinate entity2204). TheLoLat scheduling request2210 may include information identifying the requestingsubordinate entity2204, and including any pertinent information relating to the LoLat data desired to be transmitted.
• Atblock2408, thescheduling entity2201 may transmit a second assignment orgrant2214 of time-frequency resources on aLoLat grant channel2212 on the primary TDD component carrier, to the requestingsubordinate entity2204. Here, thesecond resource assignment2214 may include information identifying the requestingsubordinate entity2204, and information identifying time-frequency resources granted on the TDD uplink carrier for the LoLat uplink transmission.
• Atoptional block2410, thescheduling entity2201 may suspend its regulardownlink data transmissions2222 on the primary TDD component carrier just prior to the time at whichLoLat uplink transmissions2224 are scheduled to commence. That is, a gap orguard time2206 may optionally be utilized when multiplexingLoLat uplink transmissions2224 andregular downlink transmissions2222 on the primary TDD component carrier.
• Atblock2412, thescheduling entity2201 may transmit a downlinkscheduling grant modification2218 on thethin control channel2216 on the primary TDD component carrier. Here, the downlinkscheduling grant modification2218 may instruct the regular users such as the firstsubordinate entity2202, having granted time-frequency resources for long-TTI downlink transmissions, to ignore any uplink transmissions during at least one designated short TTI. That is, since the transmissions during that TTI will beLoLat uplink transmissions2224 from theLoLat user2204, not directed to theregular user2202, the data may not be decodable by theregular user2202 and can be ignored by theregular user2202 during post-processing of the corresponding long TTI.
• Block2414 represents operations at one or more subordinate entities, such as theLoLat user2204. That is, in response to thesecond resource assignment2214, the LoLat user (i.e., the second subordinate entity2204) may transmit theLoLat uplink data2224 utilizing the assigned time-frequency resources on the primary TDD component carrier.
• In some examples, the transmission of the downlinkscheduling grant modification2218 atblock2412, and the transmission of theLoLat uplink data2224 on the primary TDD component carrier at block2414 (and the corresponding suspension of downlink data transmissions on the primary TDD component carrier, not including any guard time that may be added), may occur simultaneously. While this may violate orthogonality, the regular users may be suitably configured to ignore the information corresponding to the time-frequency resources allocated to theLoLat user2204 during post-processing, as indicated in thedownlink grant modification2218. In other examples, these transmissions may be at different times, according to the details of a particular implementation. That is, theregular users2202 may be configured to buffer or cache the contents of thethin control channel2216 and the primary TDD component carrier, such that the ignoring of data during the designated short TTI(s) may be performed during post-processing by theregular users2202.
• At block2416, thescheduling entity2201 may receive theLoLat uplink data2224 transmitted from the requestingsubordinate entity2204 utilizing the short TTI on the primary TDD component carrier. Atblock2418, thescheduling entity2201 may resume transmitting theregular downlink data2222 on the primary TDD component carrier, to one or more subordinate entities, such as theregular user2202 utilizing the long TTI.
• By utilizing the above scheme, pairing primary and secondary TDD component carriers, athin control channel2216 andthin feedback channel2208 can enable a scheduling entity to multiplex uplink and downlink data having at least two different data types or categories, for set of subordinate entities.
• Referring now toFIG.25, a flow chart is provided illustrating anexemplary process2500 of wireless communication utilizing a TDD carrier paired with a second carrier, and multiplexing long and short TTIs, according to some aspects of the disclosure. In various examples, theprocess2500 may be implemented by thescheduling entity102 illustrated inFIGS.1 and2; thescheduling entities501,801,1101,1601,1901, or2201 illustrated inFIGS.5,8,11,16,19, and22, respectively; by aprocessing system214 including aprocessor204; or by any suitable means for carrying out the described functions.
• Atblock2502, ascheduling entity102 may wirelessly communicate with one or moresubordinate entities104 utilizing a first (e.g., long) TTI over a TDD carrier. Here, wirelessly communicating may include transmitting and/or receiving data and/or control information on one or more communication channels, as described above. Further, atblock2504, thescheduling entity102 may wirelessly communicate utilizing a second (e.g., short) TTI that at least partially overlaps with the long TTI, utilizing a second carrier paired with the first carrier but separated from the first carrier in frequency. Here, the second, paired carrier may be an FDD carrier or a TDD carrier.
• Referring now toFIG.26, flow chart is provided illustrating anexemplary process2600 of wireless communication utilizing a pair of TDD carriers for full duplex communication, according to some aspects of the disclosure. In various examples, theprocess2600 may be implemented by thescheduling entity102 illustrated inFIGS.1 and2; thescheduling entities501,801,1101,1601,1901, or2201 illustrated inFIGS.5,8,11,16,19, and22, respectively; by aprocessing system214 including aprocessor204; or by any suitable means for carrying out the described functions.
• Atblock2602, ascheduling entity102 may wirelessly communicate over a first TDD carrier. Here, wirelessly communicating may include transmitting and/or receiving data and/or control information on one or more communication channels, as described above. Further, atblock2604, thescheduling entity102 may wirelessly communicate over a second TDD carrier paired with the first TDD carrier, but separated from the first TDD carrier in frequency. Here, at least a portion of time slots in the first TDD carrier may be complementary in direction to a direction of time-aligned time slots in the second TDD carrier. That is, at least one uplink time slot in the first TDD carrier may be time-aligned with a downlink time slot in the second TDD carrier.
• As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to any suitable telecommunication systems, network architectures and communication standards. By way of example, various aspects may be applied to UMTS systems such as W-CDMA, TD-SCDMA, and TD-CDMA. Various aspects may also be applied to systems employing Long Term Evolution (LTE) (in FDD, TDD, or both modes), LTE-Advanced (LTE-A) (in FDD, TDD, or both modes), CDMA2000, Evolution-Data Optimized (EV-DO), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth, and/or other suitable systems, including those described by yet-to-be defined wide area network standards. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.
• Within the present disclosure, the word “exemplary” is used to mean “serving as an example, instance, or illustration.” Any implementation or aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects of the disclosure. Likewise, the term “aspects” does not require that all aspects of the disclosure include the discussed feature, advantage or mode of operation. The term “coupled” is used herein to refer to the direct or indirect coupling between two objects. For example, if object A physically touches object B, and object B touches object C, then objects A and C may still be considered coupled to one another-even if they do not directly physically touch each other. For instance, a first die may be coupled to a second die in a package even though the first die is never directly physically in contact with the second die. The terms “circuit” and “circuitry” are used broadly, and intended to include both hardware implementations of electrical devices and conductors that, when connected and configured, enable the performance of the functions described in the present disclosure, without limitation as to the type of electronic circuits, as well as software implementations of information and instructions that, when executed by a processor, enable the performance of the functions described in the present disclosure.
• One or more of the components, steps, features and/or functions illustrated inFIGS.1-26 may be rearranged and/or combined into a single component, step, feature or function or embodied in several components, steps, or functions. Additional elements, components, steps, and/or functions may also be added without departing from novel features disclosed herein. The apparatus, devices, and/or components illustrated inFIGS.1-26 may be configured to perform one or more of the methods, features, or steps described herein. The novel algorithms described herein may also be efficiently implemented in software and/or embedded in hardware.
• It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein.
• The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a; b; c; a and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112(f), unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”

Claims (19)

What is claimed is:

1. A method of simultaneous wireless communications operable at a scheduling entity configured to communication with one or more subordinate entities, the method comprising:

transmitting downlink messaging over a first TDD carrier at a first frequency in a first frequency band to one or more subordinate entities; and

receiving uplink messaging from one or more subordinate entities over the first TDD carrier at a second frequency in a second frequency band simultaneous to transmission of the downlink messaging, wherein the first and second frequency bands are spaced apart.

2. The method ofclaim 1, further comprising transmitting the downlink messaging via a thin control channel to communicate control information to the one or more subordinate entities.

3. The method ofclaim 1, further comprising receiving the uplink messaging from the one or more subordinate entities via a thin control channel, wherein the one or more subordinate entities transmit uplink control information in the thin control channel.

4. A method of wireless communication operable at a scheduling entity configured for duplex uplink and downlink transmissions simultaneous in time at varied frequency bands to communicate with one or more other wireless communication devices, the method comprising:

receiving uplink data on a first TDD component carrier in a first frequency band, said uplink data transmitted at a first frequency; and

transmitting downlink data on the first TDD component carrier at a second frequency in a second frequency band at the same time as receiving said uplink data on the first TDD component carrier.

5. The method ofclaim 4, further comprising transmitting the downlink data via a thin control channel to communicate control information to the one or more other wireless communication devices.

6. The method ofclaim 4, further comprising receiving the uplink data from the one or more other wireless communication devices via a thin control channel, wherein the one or more other wireless communication devices transmit uplink control information in the thin control channel.

7. A wireless communication entity configured for simultaneous wireless communications with one or more other wireless communication devices, the wireless communication entity comprising:

a communications interface configured to receive and transmit multiple wireless communications at the same time over a TDD carrier via multiple frequency bands,

wherein the communications interface is coupled to a processor, the processor configured to receive wireless communications from a first subordinate entity at a first frequency band via the TDD carrier and configured to transmit wireless communications to a second subordinate entity over the TDD carrier at a second frequency band, different from the first frequency band such that the first and second frequency bands are arranged at spaced apart frequencies.

8. The wireless communication entity ofclaim 7, wherein the processor is further configured to transmit the wireless communications via a thin control channel to communicate control information to the second subordinate entity.

9. The wireless communication entity ofclaim 7, wherein the processor is further configured to receive the wireless communications from the first subordinate entity via a thin control channel, wherein the first subordinate entity transmits uplink control information in the thin control channel.

10. A method of wireless communication operable at a subordinate entity configured to communicate with one or more scheduling entities, the method comprising:

receiving a resource assignment comprising a grant of time-frequency resources for transmitting wireless messaging on an uplink channel; and

transmitting, over a first TDD carrier at a first frequency in a first frequency band, the wireless messaging on the uplink channel according to the resource assignment,

wherein the wireless messaging on the uplink channel occurs at the same time with a transmission from a scheduling entity to one or more other subordinate entities over the first TDD carrier via a second frequency.

11. The method ofclaim 10, wherein the first TDD carrier is a primary TDD component carrier.

12. The method ofclaim 10, further comprising:

transmitting a scheduling request on a secondary TDD component carrier prior to receiving the resource assignment.

13. The method ofclaim 10, further comprising:

ignoring information received from transmissions of one or more other subordinate entities received over the first TDD carrier via a second frequency occurring at the same time as transmissions occur over the first TDD carrier at the first frequency.

14. The method ofclaim 10, further comprising:

receiving a grant modification indication comprising information indicating that the grant of time-frequency resources is modified and changing communications based on the grant modification indication.

15. A method of wireless communication operable at a subordinate entity, the method comprising:

receiving, from a scheduling entity, a resource assignment comprising a grant of time-frequency resources configured to indicate resources for transmitting wireless messaging on an uplink data channel;

transmitting, over a first TDD carrier in a first frequency band, the wireless messaging on the uplink data channel according to indicated resources associated with the resource assignment; and

receiving a transmission from the scheduling entity to one or more other subordinate entities over the first TDD carrier via a second frequency at the same time as transmitting the wireless messaging on the uplink data channel.

16. The method ofclaim 15, wherein the first TDD carrier is a primary TDD component carrier.

17. The method ofclaim 15, further comprising:

transmitting a scheduling request on a secondary TDD component carrier prior to receiving the resource assignment.

18. The method ofclaim 15, further comprising:

ignoring information received from transmissions of one or more other subordinate entities received over the first TDD carrier via a second frequency occurring at the same time as transmissions occur over the first TDD carrier at the first frequency band.

19. The method ofclaim 15, further comprising:

receiving a grant modification indication comprising information indicating that the grant of time-frequency resources is modified and changing communications based on the grant modification indication.

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