This application claims benefit OF U.S. provisional application No. 62/108,661 entitled "ON THE TRANSMISSION OF laboratory CONTROL INFORMATION" filed ON 28.1.2015, THE entire contents OF which are incorporated herein by reference.
Detailed Description
The present invention will now be described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout, and wherein the illustrated structures and devices are not necessarily drawn to scale. As used herein, the terms "component," "system," "interface," and the like are intended to refer to a computer-related entity, hardware, software (e.g., in execution), and/or firmware. For example, a component may be a processor (e.g., a microprocessor, controller or other processing device), a process running on a processor, a controller, an object, an executable, a program, a storage device, a computer, a tablet PC, and/or a user equipment (e.g., a mobile phone, etc.) having a processing device. By way of illustration, both an application running on a server and the server can be a component. One or more components can reside within a process and a component can be localized on one computer and/or distributed between two or more computers. A collection of elements or other components may be described herein, wherein the term "collection" may be interpreted as "one or more.
Further, for example, these components can execute from various computer readable storage media having various data structures stored thereon (e.g., with modules). The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network such as the internet, a local area network, wide area network, or the like with other systems by way of the signal).
As another example, a component may be an apparatus having a particular functionality provided by mechanical parts operated by electrical or electronic circuitry, where the electrical or electronic circuitry may be operated by a software application or firmware application executed by one or more processors. The one or more processors may be internal or external to the apparatus and may execute at least a portion of a software or firmware application. As yet another example, a component may be a device that provides a particular function through an electronic component without the use of mechanical parts; one or more processors may be included in the electronic components to execute software and/or firmware that at least partially imparts functionality to the electronic components.
The use of the word "exemplary" is intended to present concepts in a concrete fashion. As used in this application, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise, or clear from context, "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, if X employs A; x is B; or X employs both A and B, then "X employs A or B" is satisfied under any of the foregoing circumstances. In addition, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form. Furthermore, to the extent that the terms "includes," including, "" has, "" with, "or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term" comprising.
As used herein, the term "circuitry" may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with, one or more software or firmware modules. In some embodiments, the circuitry may comprise logic at least partially operable in hardware.
The embodiments described herein may be implemented in a system using any suitably configured hardware and/or software. Fig. 1 illustrates one embodiment of exemplary components of a User Equipment (UE) device 100. In some embodiments, the UE device 100 may include application circuitry 102, baseband circuitry 104, Radio Frequency (RF) circuitry 106, Front End Module (FEM) circuitry 108, and one or more antennas 110 coupled together at least as shown.
The application circuitry 102 may include one or more application processors. For example, the application circuitry 102 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor may include any combination of general-purpose processors and special-purpose processors (e.g., graphics processors, application processors, etc.). The processor may be coupled to and/or may include memory/storage and may be configured to execute instructions stored in the memory/storage to cause various applications and/or operating systems to run on the system.
The baseband circuitry 104 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. Baseband circuitry 104 may include one or more baseband processors and/or control logic to process baseband signals received from the receive signal path of RF circuitry 106 and to generate baseband signals for the transmit signal path of RF circuitry 106. Baseband processing circuitry 104 may interact with application circuitry 102 for generating and processing baseband signals and for controlling the operation of RF circuitry 106. For example, in some embodiments, the baseband circuitry 104 may include a second generation (2G) baseband processor 104a, a third (3G) baseband processor 104b, a fourth generation (4G) baseband processor 104c, and/or other baseband processors 104d for other existing, developing, or future developed generations (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry 104 (e.g., one or more baseband processors 104a-d) may handle various radio control functions capable of communicating with one or more radio networks via the RF circuitry 106. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, and the like. In some embodiments, the modulation/demodulation circuitry of the baseband circuitry 104 may include Fast Fourier Transform (FFT), precoding, and/or constellation mapping/demapping functions. In some embodiments, the encoding/decoding circuitry of baseband circuitry 104 may include convolution, tail-biting convolution, turbo, Viterbi (Viterbi), and/or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functions are not limited to these examples, and other suitable functions may be included in other embodiments.
In some embodiments, the baseband circuitry 104 may include elements of a protocol stack (element), such as, for example, elements of an Evolved Universal Terrestrial Radio Access Network (EUTRAN) protocol, including, for example, Physical (PHY), Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and/or Radio Resource Control (RRC) elements. A Central Processing Unit (CPU)104e of the baseband circuitry 104 may be configured to run elements of a protocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. In some embodiments, the baseband circuitry may include one or more audio Digital Signal Processors (DSPs) 104 f. The audio DSP 104f may include elements for compression/decompression and echo cancellation, and may include other suitable processing elements in other embodiments. In some embodiments, the components of the baseband circuitry may be combined on a single chip, a single chipset, or disposed on the same circuit board, as appropriate. In some embodiments, some or all of the constituent components of baseband circuitry 104 and application circuitry 102 may be implemented together, such as on a system on a chip (SOC).
In some embodiments, the baseband circuitry 104 may provide communications compatible with one or more radio technologies. For example, in some embodiments, baseband circuitry 104 may support communication with an Evolved Universal Terrestrial Radio Access Network (EUTRAN) and/or other Wireless Metropolitan Area Networks (WMANs), Wireless Local Area Networks (WLANs), Wireless Personal Area Networks (WPANs). Embodiments in which the baseband circuitry 104 is configured to support radio communications over more than one wireless protocol may be referred to as multi-mode baseband circuitry.
The RF circuitry 106 may enable communication with a wireless network using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 106 may include switches, filters, amplifiers, and the like to facilitate communication with the wireless network. RF circuitry 106 may include a receive signal path that may include circuitry to down-convert (down-convert) an RF signal received from FEM circuitry 108 and provide a baseband signal to baseband circuitry 104. RF circuitry 106 may also include a transmit signal path that may include circuitry to up-convert (up-convert) a baseband signal provided by baseband circuitry 104 and provide an RF output signal to FEM circuitry 108 for transmission.
In some embodiments, the RF circuitry 106 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry 106 may include mixer circuitry 106a, amplifier circuitry 106b, and filter circuitry 106 c. The transmit signal path of the RF circuitry 106 may include a filter circuit 106c and a mixer circuit 106 a. The RF circuitry 106 may also include synthesizer circuitry 106d for synthesizing the frequencies used by the mixer circuitry 106a of the receive signal path and the transmit signal path. In some embodiments, mixer circuit 106a of the receive signal path may be configured to down-convert the RF signal received from FEM circuitry 108 based on the synthesized frequency provided by synthesizer circuit 106 d. The amplifier circuit 106b may be configured to amplify the downconverted signal, and the filter circuit 106c may be a Low Pass Filter (LPF) or a Band Pass Filter (BPF) configured to remove unwanted signals from the downconverted signal to generate an output baseband signal. The output baseband signal may be provided to the baseband circuitry 104 for further processing. In some embodiments, the output baseband signal may be a zero frequency baseband signal, but this is not required. In some embodiments, mixer circuit 106a of the receive signal path may comprise a passive mixer, although the scope of the embodiments is not limited in this respect.
In some embodiments, mixer circuitry 106a of the transmit signal path may be configured to upconvert the input baseband signal based on a synthesis frequency provided by synthesizer circuitry 106d to generate an RF output signal for FEM circuitry 108. The baseband signal may be provided by baseband circuitry 104 and may be filtered by filter circuitry 106 c. The filter circuit 106c may include a Low Pass Filter (LPF), but the scope of the embodiments is not limited in this respect.
In some embodiments, the mixer circuit 106a of the receive signal path and the mixer circuit 106a of the transmit signal path may comprise two or more mixers and may be arranged for quadrature down-conversion and/or up-conversion, respectively. In some embodiments, the mixer circuit 106a of the receive signal path and the mixer circuit 106a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuit 106a and the mixer circuit 106a of the receive signal path may be arranged for direct down-conversion and/or direct up-conversion, respectively. In some embodiments, mixer circuit 106a of the receive signal path and mixer circuit 106a of the transmit signal path may be configured for superheterodyne operation.
In some embodiments, the output baseband signal and the input baseband signal may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternative embodiments, the output baseband signal and the input baseband signal may be digital baseband signals. In these alternative embodiments, RF circuitry 106 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry, and baseband circuitry 104 may include a digital baseband interface for communicating with RF circuitry 106.
In some dual-mode embodiments, separate radio IC circuitry may be provided to process signals for each spectrum, although the scope of the embodiments is not limited in this respect.
In some embodiments, synthesizer circuit 106d may be a fractional-N synthesizer or a fractional-N/N +1 synthesizer, although the scope of the embodiments is not limited in this respect and other types of frequency synthesizers may be suitable. For example, synthesizer circuit 106d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer including a phase locked loop with a frequency divider.
The synthesizer circuit 106d may be configured to synthesize an output frequency for the mixer circuit 106a of the RF circuit 106 based on the frequency input and the frequency division control input. In some embodiments, the synthesizer circuit 106d may be a fractional-N/N +1 synthesizer.
In some embodiments, the frequency input may be provided by a Voltage Controlled Oscillator (VCO), but this is not required. The divider control input may be provided by baseband circuitry 104 or application processor 102 depending on the desired output frequency. In some embodiments, the divider control input (e.g., N) may be determined from a look-up table based on the channel indicated by the application processor 102.
Synthesizer circuit 106d of RF circuit 106 may include a frequency divider, a Delay Locked Loop (DLL), a multiplexer, and a phase accumulator. In some embodiments, the frequency divider may be a dual-mode frequency divider (DMD) and the phase accumulator may be a Digital Phase Accumulator (DPA). In some embodiments, the DMD may be configured to divide an input signal by N or N +1 (e.g., based on a carry out) to provide a fractional divide ratio. In some example embodiments, a DLL may include a set of cascaded, tunable delay elements, a phase detector, a charge pump, and a D-type flip-flop. In these embodiments, the delay elements may be configured to decompose the VCO period into Nd equal phase groups, where Nd is the number of delay elements on the delay line. In this manner, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.
In some embodiments, synthesizer circuit 106d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with a quadrature generator and frequency divider circuit to generate a plurality of signals at the carrier frequency having a plurality of different phases relative to each other. In some embodiments, the output frequency may be the LO frequency (fLO). In some embodiments, the RF circuitry 106 may include an IQ/polar converter.
FEM circuitry 108 may include a receive signal path that may include circuitry configured to operate on RF signals received from one or more antennas 110, amplify the received signals, and provide amplified signals of the received signals to RF circuitry 106 for further processing. FEM circuitry 108 may also include a transmission signal path that may include circuitry configured to amplify signals for transmission provided by RF circuitry 106 for transmission by one or more of one or more antennas 110.
In some embodiments, FEM circuitry 108 may include TX/RX switches to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include a Low Noise Amplifier (LNA) to amplify the received RF signal and provide the amplified received RF signal as an output (e.g., to the RF circuitry 106). The transmit signal path of FEM circuitry 108 may include a Power Amplifier (PA) for amplifying an input RF signal (e.g., provided by RF circuitry 106) and one or more filters for generating an RF signal for subsequent transmission (e.g., by one or more of one or more antennas 110).
In some embodiments, the UE device 100 may include additional elements such as, for example, memory/storage, a display, a camera, sensors, and/or an input/output (I/O) interface.
On a RAN1(RAN WG1 (working group 1)) #79 conference, the following agreement is reached on the transmission of the channel reservation signal for LAA as described in the description of the RAN1#79 conference chairman:
DL [ downlink ] LAA design [ can ] assuming subframe boundary alignment according to Rel-12 [ release 12 ] CA timing relationship between serving cells aggregated by CA
-at least for LBE [ load based device ], some signals may be transmitted by the eNB between the time the eNB is allowed to transmit and the start of the data transmission to reserve at least the channel
This does not mean that data transmission can only be started at a subframe boundary
The possible definition of the starting position of the data transmission can be taken into account
The duration of the signal is a fraction of the maximum transmission duration
Content/additional function/duration of the signal is FFS [ further study ]
This does not mean network synchronization
In various aspects, new LAA burst frame structures and preamble designs may be employed to allow for efficient LAA operation, and embodiments discussed herein may relate to LAA burst control information associated with such LAA bursts. Referring to fig. 2, a frame structure of an exemplary LAA burst is shown that may be employed in connection with the various embodiments discussed herein. The LAA burst frame may include one or more channel reservation signals (indicated by diagonal cross-hatching), an LAA preamble (indicated by wider diagonal hatching), an optional Clear To Send (CTS) (indicated by narrower diagonal hatching), (e) a PDCCH (i.e., PDCCH (physical downlink control channel) and/or ePDCCH (enhanced PDCCH), indicated by vertical and horizontal cross-hatching), and data transmission (e.g., including one or more data payloads (payload)). In various aspects, a channel reservation signal having a variable length may be transmitted at the beginning of an LAA burst after an eNB implements a Clear Channel Assessment (CCA) or an extended CCA and detects that an unlicensed carrier is idle. The LAA preamble may then be transmitted after the channel reservation signal, which may facilitate Automatic Gain Control (AGC), coarse and/or fine synchronization of the UE, and may optionally provide certain information related to the transmission of LAA bursts. In the latter case, the LAA burst control channel may be embedded within the LAA preamble, which may facilitate efficient LAA operation. However, in other aspects, the LAA burst control information may be transmitted in other manners.
According to various embodiments described herein, techniques may be employed to communicate LAA (licensed assisted access) burst control information associated with LAA bursts (e.g., the exemplary LAA burst shown in fig. 2), which may facilitate efficient LAA operation. In various aspects discussed herein, optional content for LAA burst control information is provided along with a number of potential mechanisms for communication (e.g., transmission/reception, etc.) of the LAA burst control information. In aspects in which the LAA burst control information is transmitted over the LAA burst control channel, a number of options for data format and transmission scheme may be employed, including aspects related to channel coding, rate matching, scrambling, modulation, layer mapping, and precoding for the LAA burst control channel.
Referring to fig. 3, a block diagram is illustrated of a system 300 that facilitates communication of LAA burst control information associated with LAA bursts from a base station in accordance with various aspects described herein. System 300 may include a processor 310, a transmitter circuit 320, an optional receiver circuit 330, and a memory 340 (which may include any of a variety of storage media and may store instructions and/or data associated with one or more of processor 310, transmitter circuit 320, or receiver circuit 330). In various aspects, system 300 may be included within an evolved universal terrestrial radio access network (E-UTRAN) node B (evolved node B, eNodeB or eNB) or other base station in a wireless communication network. As described in more detail below, the system 300 can facilitate transmission of LAA burst control information indicating various configuration information for LAA burst transmission.
The processor 310 may construct an LAA burst transmission that may include content similar to that of the exemplary LAA burst in fig. 2. The content may include one or more of the following: a channel reservation signal, a LAA preamble, an optional window for receiving (e.g., at the receiver circuitry 330) Clear To Send (CTS) messages from one or more UEs (e.g., in aspects where the LAA burst includes one or more Request To Send (RTS) messages requesting the CTS message as feedback, etc.), (e) a PDCCH (e.g., a PDCCH (physical downlink control channel) and/or ePDCCH (enhanced PDCCH)) message, and one or more data payloads.
Additionally, the processor 310 can generate LAA burst control information indicating configuration information associated with the LAA burst. The configuration information may include one or more of the following information: length of the LAA burst, cell ID (identification) information about a cell from which the LAA burst is derived, operator ID information about a wireless operator from which the LAA burst is derived, various types of configuration information (e.g., related to Discovery Reference Symbols (DRS), Time Division Duplex (TDD) control of a channel, etc.), Downlink (DL) transmission power information related to transmission power of Reference Symbols (RSs) within the LAA burst, an indicator of whether the LAA burst includes a PBCH (physical broadcast channel) message, etc.
In some aspects, the processor 310 may include a Request To Send (RTS) message within the LAA burst control information with functionality similar to a WiFi RTS message. The RTS message may include receiver address information indicating at least one UE designated to respond to the RTS message with a CTS message. The maximum number of ues (n) that may be indicated (n) may be predetermined (e.g., defined by a specification) or may be configured through higher layer signaling (e.g., SIB (system information block) or RRC (radio resource control), etc.) or may be indicated through LAA burst control information generated by the processor 310. The UE may be indicated in any of a number of ways, such as by its ID (e.g., RNTI (radio network temporary identity), such as C-RNTI (cell RNTI), IMSI (international mobile subscriber identity), etc.) or by a bitmap that associates the UE with bits indicating whether a CTS message is requested as feedback, where the bits associated with each UE in the bitmap may be configured by higher layer signaling. In some aspects in which processor 310 includes an RTS message, the RTS message may optionally indicate Transmission Power Control (TPC) information, which may specify an Uplink (UL) transmission power for at least one of the CTS message or one or more other UL transmissions.
The processor 310 can prepare the LAA burst control information for transmission by encoding the LAA burst control information to the physical layer, which can include selecting a data format and transmission scheme for the LAA burst control information and associated actions (e.g., one or more of channel coding, rate matching, scrambling, modulation, layer mapping, precoding, etc.) in preparing the LAA burst control information for transmission.
The transmitter circuit 320 may transmit physical layer coding of LAA burst control information and may transmit LAA bursts, both of which may be transmitted over unlicensed carriers. In various aspects, the transmitter circuitry 320 may send the LAA burst control information over one or more portions of the LAA burst, depending on the manner in which the processor 310 prepares the LAA burst control information for transmission.
In a first set of embodiments, the LAA burst control information may be prepared as a Downlink Control Information (DCI) message that the transmitter circuitry 320 may transmit over the (e) PDCCH of the LAA burst. Depending on the amount of LAA burst control information, the legacy LTE DCI format may be modified to incorporate LAA burst control information (e.g., for a small amount of LAA burst control information, e.g., only the length of the LAA burst, etc.), or an LAA-specific DCI format may be employed that may include LAA burst control information.
In a second set of embodiments, the LAA burst control information may be embedded in a sequence within the LAA preamble of the LAA burst. This second set of embodiments is better when less LAA burst control information is to be transmitted, since the amount of information that can be carried in the sequence is limited. The sequence may also facilitate coarse and/or fine synchronization of the UE.
In a third set of embodiments, the transmitter circuitry 320 may transmit LAA burst control information over a dedicated LAA burst control channel, which may be embedded in the LAA preamble. The LAA burst control information may be transmitted within an LAA burst control channel message that may include one or more of a header, an LAA burst control payload, or a cyclic redundancy check. Fig. 8, discussed in more detail below, shows a diagram of a format for an exemplary LAA burst control channel message. When included, the header may identify one or more UEs, e.g., UEs that receive data over LAA bursts, UEs that are requested to feed back a CTS message in response to an RTS message, etc. The LAA burst control payload may contain some or all of the LAA burst control information (e.g., some may be inside the header, some inside the LAA burst control payload, all inside the LAA burst control payload, etc.). The CRC may include various parity bits (e.g., 8, 16, 24, etc.), which may depend on the particular embodiment (e.g., the amount of LAA burst control information and the size of the header and/or LAA burst control payload, etc.).
The LAA burst control channel may be channel coded by tail-biting convolutional codes (TBCC) or Turbo Codes (TC), which may depend on the embodiment (e.g., for smaller payload sizes, TBCC performs better than TC), and may be rate matched to fill out (fill out) the available Resource Elements (REs) in the system bandwidth. The LAA burst control channel may be rate matched around the PSS and/or SSS if the LAA preamble includes primary and/or secondary synchronization signals (PSS and/or SSS). The channel coded and rate matched LAA burst control channel may be scrambled based on a similar scrambling procedure as employed for the Physical Broadcast Channel (PBCH), which may be initialized with a scrambling seed (scrambling seed) based on one or more of a cell ID, a frame index, a subframe index, or an OFDM (orthogonal frequency division multiplexing) symbol index. The modulation may be based on a modulation scheme with a low modulation order (e.g., 4 or less, etc.), such as BPSK (binary phase shift keying) or QPSK (quadrature phase shift keying), which may ensure reception of the LAA burst control channel.
When included, the receiver circuitry 330 may monitor the unlicensed carrier in conjunction with a Clear Channel Assessment (CCA) or an extended CCA. Based on the monitoring by the receiver circuit 330, the processor 310 may determine whether the unlicensed carrier is idle based on any of various metrics. Additionally, in aspects in which the LAA burst control information includes an RTS message, the receiver circuitry 330 may receive a CTS message as feedback from one or more UEs in response to the RTS message.
Referring to fig. 4, a block diagram is illustrated of a system 400 that facilitates communicating LAA burst control information associated with LAA bursts to a mobile terminal in accordance with various aspects described herein. System 400 may include a receiver circuit 410, a processor 420, an optional transmitter circuit 430, and a memory 440 (which may include any of a variety of storage media and may store instructions and/or data associated with one or more of receiver circuit 410, processor 420, or transmitter circuit 430). In various aspects, system 400 can be included within a User Equipment (UE). As described in more detail below, the system 400 can facilitate receiving LAA burst control information indicating configuration information for LAA bursts.
The receiver circuitry 410 may receive (over an unlicensed carrier) LAA burst control information from the eNB, which may indicate configuration information (e.g., length, etc.) of the LAA burst transmission from the eNB, and the receiver circuitry 410 may receive the LAA burst transmission. Depending on the particular embodiment, the LAA burst control information may be received through a DCI message transmitted via (e) PDCCH in the LAA burst, may be received in a sequence embedded within the LAA preamble of the LAA burst transmission, or may be received through a dedicated LAA burst control channel, which may be included within the LAA preamble.
The processor 420 may recover the received LAA burst control information in a manner suitable for how the LAA burst control information is received. For example, by decoding, searching for and decoding a DCI message including LAA burst control information or detecting a sequence including LAA burst control information embedded within an LAA preamble.
The processor 420 may determine, from the recovered LAA burst control information, indicated configuration information related to the LAA burst transmission, which may include a length of the LAA burst transmission and/or other configuration information. In aspects in which the LAA burst control information includes an RTS message, processor 420 may determine whether a CTS message is requested as feedback from a UE employing system 400. The processor 420 may accomplish this by determining whether the ID of the UE (e.g., C-RNTI, IMSI, etc.) is indicated in the receiver address information associated with the RTS message, or whether a bit associated with the UE in a bitmap indicates that a CTS message is requested as feedback. In the case where the UE is associated with a bit in the bitmap, the receiver 410 may receive a control message (e.g., by RRC, etc.) that configures which bit is associated with the UE.
When included, the transmitter 430 may transmit a CTS message in response to the RTS message (e.g., which may be based on a determination that the channel is clear via a CCA or extended CCA procedure, etc.). Additionally, transmitter 430 can transmit Uplink (UL) data during any UL grant for a UE employing system 400. In various aspects, the CTS and/or UL data may be transmitted at a power based on Transmit Power Control (TPC) information received as part of the LAA burst control information.
Referring to fig. 5, a flow diagram is illustrated of a method 500 of facilitating communication of LAA burst control information associated with LAA bursts from a base station in accordance with various aspects described herein. In some aspects, method 500 may be implemented at an eNB. In other aspects, a machine-readable medium may store instructions associated with the method 500 that, when executed, may cause an eNB to implement the actions of the method 500.
At 510, a CCA or extended CCA may be implemented on an unlicensed carrier to determine whether the carrier is idle.
At 520, an LAA burst may be constructed, which may include one or more of a channel reservation signal, an LAA preamble, a window for CTS feedback, one or more (e) PDCCH messages, and one or more data payloads.
At 530, LAA burst control information indicating configuration information (e.g., length, etc.) associated with the LAA burst may be generated. In some aspects, the LAA burst control information may include an RTS message requesting a CTS message as feedback from one or more UEs.
At 540, LAA burst control information may be transmitted. In various aspects, the LAA burst control information may be transmitted through (e) a DCI message in a PDCCH (embedded in a sequence in the LAA preamble) or through a dedicated LAA burst control channel in the LAA preamble.
At 550, in aspects in which the LAA burst control information includes an RTS message requesting a CTS message as feedback from one or more UEs, the CTS message may not be received from the UE or may be received from some or all of the one or more UEs.
Referring to fig. 6, a flow diagram is illustrated of a method 600 that facilitates communicating LAA burst control information associated with an LAA burst to a mobile terminal in accordance with various aspects described herein. In some aspects, the method 600 may be implemented at a UE. In other aspects, a machine-readable medium may store instructions associated with method 600 that, when executed, may cause a UE to implement the actions of method 600.
At 610, LAA burst control information may be received from an eNB. In aspects, the burst control information may be received through a DCI message transmitted through (e) PDCCH (as a sequence embedded within an LAA preamble of an LAA burst transmission) or through a dedicated LAA burst control channel, which is embedded within the LAA preamble.
At 620, the LAA burst control information may be recovered from the LAA preamble or (e) PDCCH depending on the manner in which it is received.
At 630, configuration information for the LAA burst may be determined from the LAA burst control information, which may include the length of the LAA burst, etc. In this regard, the LAA burst control information may include an RTS message requesting a CTS message as feedback from one or more UEs.
At 640, in aspects in which the LAA burst control information includes an RTS message requesting a CTS message as feedback from a UE implementing method 600 (e.g., by indicating an ID of the UE via a bit associated with the UE in a bitmap, etc.), the CTS message may be transmitted as feedback in response to determining that the channel is clear (e.g., by CCA or extended CCA).
Additional options, details, and specific embodiments are discussed below.
LAA burst control information
In various aspects, some or all of the following parameters may be included in the LAA burst control information: LAA burst length information, cell ID (identity) information, operator identity, Discovery Reference Symbol (DRS) configuration information, TDD (time division duplex) configuration information, DL (downlink) transmission power information, indication of PBCH (physical broadcast channel) transmission. These parameters will be discussed in more detail below.
When the LAA burst length information field is included, the LAA burst length information field may be expressed in the form of the number of subframes or the number of OFDM (orthogonal frequency division multiplexing) symbols. In this aspect, the LAA burst length information may be Y bits in size. In one example, since the maximum transmission duration of an LAA burst may be 13ms, Y may be designated as 4 when the number of subframes is used, and may be designated as 16 when the number of symbols is used.
When cell ID information is included, the cell ID information may contain all or part of the physical layer cell identification of the cell.
When included, the operator identity may contain all or part of the information of the operator identity. The operator identity may be a Public Land Mobile Network (PLMN) or an evolved cell global identifier (E-CGI). In some embodiments, the operator identity may include both a PLMN and an E-CGI. The operator identification may be received from a PCell (primary cell) SIB (system information block).
When included, the DRS configuration information may contain a configuration for transmission of DRSs within an LAA burst. In one example, a bitmap may be used to indicate transmission of DRSs in an LAA burst. If this field is omitted, the DRS subframe location within the burst may be configured in other ways, e.g., by a combination of one or more of PCell SIB, SCell (secondary cell) SIB, PCellPDSCH (physical downlink shared channel), or SCell PDSCH.
When included, the TDD configuration information may contain information related to TDD configuration within an LAA burst. In this regard, this may allow for dynamic control of downlink and uplink traffic on the unlicensed carriers within the LAA burst. This may also include uplink control configurations such as CCA duration and backoff (backoff) parameters.
When DL transmission power information is included, the DL transmission power information may contain, for example, DL transmission power information that may include transmission power of CRS (common reference symbols) within a burst and transmission power of DRSs within the burst. This information would be useful when the transmission power of each LAA burst is dynamically adjusted on a per burst basis. In such an aspect, the transmission power information may be used to calculate DL path loss and/or RRM (radio resource management).
When the indication of PBCH transmission is included, the indication of PBCH transmission may contain an indication of whether PBCH is transmitted within an LAA burst. In one example, the field may be a single bit, and when the field is set to 1 (or alternatively to 0), the PBCH may be transmitted in subframe 0 within the LAA burst, similar to PBCH transmission in licensed spectrum LTE operation.
In some aspects, the LAA burst control information may include a Request To Send (RTS) message, which may include the functionality of an RTS message employed in WiFi. In such an aspect, the RTS message may optionally include one or more of receiver address information or Transmit Power Control (TPC) information.
When receiver address information is included, the receiver address information may contain information of a receiver address, which may indicate a UE requesting transmission of a CTS (clear to send) message in response to the RTS message. The receiver address may be specified in the form of a unicast, multicast or broadcast address. Referring to fig. 7, two diagrams of example implementations for indicating a receiver address of an RTS message are shown, in accordance with various aspects described herein.
In a first set of embodiments, the receiver address may be expressed in the form of a C-RNTI (cell radio network temporary identity) or an IMSI (International Mobile subscriber identity). In 700, fig. 7 shows a receiver address structure in the form of a C-RNTI for one or more UEs. The number of UEs N employed in such an aspect may be predetermined or dynamic. In the latter case, when the dedicated LAA burst control channel is used for transmission of LAA burst control information, information regarding the number of UEs may be included in a header of the LAA burst control channel message, as discussed in more detail below. In other aspects, the number of UEs may be explicitly indicated in one field of the LAA burst control information.
In a second set of embodiments, a bitmap may be used to indicate which UEs are requested to feed back CTS. For example, "1" may indicate that the UE needs to feed back CTS to the eNB, while "0" may indicate that the UE does not need to feed back CTS (or vice versa). Similar to DCI (downlink control information) format 3/3a, the UE index in the bitmap may be provided via dedicated RRC (radio resource control) signaling.
In various aspects, the bitmap size may be predetermined or dynamic. In the former case, the bitmap size or the number of UEs may be predefined in the specification or may be provided by higher layers through SIB or dedicated RRC signaling. In the latter case, in aspects where a dedicated LAA burst control channel is used for transmission of LAA burst control information, information related to the number of UEs may be included in the header, as discussed in more detail below. Alternatively, the number of UEs may be explicitly indicated in one field of the LAA burst control information. In some aspects, the number of UEs included in this field may be limited to up to N users, such that this information may be transmitted in an allocated set of resources (e.g., 2 symbols, etc.).
In one example, as shown at 710 in fig. 7, N bits may be used for the receiver address bitmap (N ═ 10 in the example of 710), and UE #3 and UE #7 may be associated with bit #2 and bit #6, respectively. As shown in the exemplary bitmap of 710, UE #7 is indicated to feed back CTS, while UE #3 is not.
When Transmit Power Control (TPC) information is included in the RTS message, the TPC information may include a TPC configuration for CTS or uplink data transmission from one or more UEs on an unlicensed carrier. In one example, the nominal transmission power for the CTS transmission and the fractional value a may be included in this field. In another example, this field may also be used for TPC for uplink data transmission.
Transmission of LAA burst control information
The LAA burst control information may be transmitted in any of various ways.
In a first set of embodiments, the LAA burst control information may be transmitted over a dedicated LAA burst control channel. For example, an LAA burst control channel may be embedded in the LAA preamble to provide LAA burst control information related to the transmission of LAA bursts. After successfully decoding the LAA burst control channel, the LAA-enabled UE may determine the start and end positions of the LAA burst and may monitor (e) the PDCCH to check whether the eNB will transmit data in the downlink on the unlicensed carrier. Optional details regarding the design of the LAA burst control channel (e.g., data format and transmission scheme) are described in more detail below.
In a second set of embodiments, LAA burst control information may be transmitted through (e) the PDCCH. In some such aspects, one or more fields may be added to an existing DCI format where the size of the LAA burst control information is small. For example, the LAA burst length may be included in DCI format 1A.
In embodiments where the size of the LAA burst control information is relatively large, a new DCI format containing the LAA burst control information may be defined. Additionally, a new RNTI "LAA-RNTI" may be defined, or an existing RNTI (e.g., SI-RNTI (system information RNTI)) may be reused for the CRC (cyclic redundancy check) mask. To further reduce blind detection attempts by one or more UEs on the unlicensed carrier, a fixed common search space and aggregation level (e.g., having 8 CCEs, etc.) may be specified.
In a third set of embodiments, the LAA burst control information may be embedded in a sequence within the LAA preamble. This option is beneficial in case the size of the LAA burst control information is small, since the information carried by the sequence will be limited. For example, in some embodiments, the LAA burst control information may only contain information about the LAA burst length. After the correct detection sequence, the UE may know the LAA burst duration. Additionally, the sequence may also be used for the purpose of coarse/fine synchronization of the pair of LAA-capable UEs.
LAA burst control channel design
Several mechanisms may be employed for transmission of LAA burst control information. In embodiments employing a dedicated LAA burst control channel, there are several options for data format and transmission scheme (e.g., including modulation, channel coding and scrambling, etc.).
Referring to fig. 8, an exemplary data format for transmitting an LAA burst control channel message 800 (which may include an optional header 810, an LAA burst control channel payload 820 that may include at least a portion of LAA burst control information, and a CRC 830) is shown. The header 810 may be included or omitted depending on the content of the payload 820. In the presence of the header 810, it may contain information of the number of UEs that the eNB intends to transmit data, or may contain a request for feedback Clear To Send (CTS) message. The header 810 may also contain information for a MAC (medium access control) layer, for example, a logical channel id (lcid).
The payload 820 may additionally contain one or more reserved bits of the LAA burst control channel. For CRC, different numbers of parity bits (e.g., 8, 16, or 24, etc.) may be calculated based on the payload 820 and/or the header 810 and appended to the payload 820. In this regard, for the LAA burst control channel, the generator polynomial g discussed in section 5.1.1 of 3GPP TS (technical specification) 36.212 may be employedCRC8(D)、gCRC16(D)、gCRC24A(D) And gCRC24B(D) One of them.
For the LAA burst control channel, tail-biting convolutional codes (TBCC) or Turbo Codes (TC) in the LTE specification may be used for channel coding. Since TBCC performs better than TC when the payload size is relatively small, it is more advantageous to reuse the existing TBCC for LACC burst control channel. After channel coding, rate matching may be achieved to fill in available REs (resource elements) within the system bandwidth. Thus, with a larger system bandwidth, a larger number of repetitions can be achieved for transmission of the LAA burst control channel. In addition, in case of multiplexing PSS (primary synchronization signal) and/or SSS (secondary synchronization signal) in the LAA preamble, the LAA burst control channel may be rate-matched around the PSS and/or SSS signals.
After channel coding and rate matching, scrambling may be implemented to randomize interference. In LAA burst control channel design, a similar scrambling procedure as in the existing LTE specifications for PBCH (physical broadcast channel) may be applied. The scrambling sequence may be initialized in any of a variety of ways, which may depend at least in part on one or more of a cell ID, a frame index, a subframe index, or an OFDM symbol index.
In a first set of embodiments, the scrambling sequence may utilize a seed c with some functionality of cell IDinitTo initialize, e.g.Here, theIs a cell ID.
In a second set of embodiments, the scrambling seed may be defined as a function of one or more of a cell ID, a frame index, a subframe index, or an OFDM symbol number, such as in the following examples: (1)(2)or (3)Where n isFrameIs the frame number, nSFIs indexed by subframe, and nsymbolIs indexed for OFDM symbols within one subframe. In one particular example, the scrambling seed may be given as:
for modulation, in various aspects, a low modulation order, such as BPSK (binary phase shift keying) or QPSK (quadrature phase shift keying), may be employed, which may facilitate robust reception of the LAA burst control channel.
Where multi-antenna transmission is involved, transmit diversity or beamforming may be used for transmission of the LAA burst control channel, depending on the specific Reference Symbol (RS) structure within the LAA preamble.
The number of APs (antenna ports) used in the transmission of the LAA burst control channel may be provided by higher layer signaling from the Pcell through SIB or UE-specific dedicated RRC signaling. This may avoid blind detection of the number of APs on the unlicensed carrier, thereby reducing UE power consumption.
In embodiments where the RS structure enables transmission diversity to be employed, Resource Element Groups (REGs) may be defined for groups of 4 consecutive REs in the frequency domain on each Antenna Port (AP). In addition, the precoding of the transmit diversity transmission of the LAA burst may be similar to the procedure specified in section 6.3.4.1 or 6.3.4.3 in 3GPP TS 36.211. In this regard, in the case of two APs, space-frequency block coding (SFBC) may be employed, and in the case of 4 APs, a combination of SFBC and Frequency Switched Transmit Diversity (FSTD) may be employed.
In embodiments where the RS structure enables beamforming to be employed, beamforming may be employed for transmission of the LAA burst control channel. The beamforming weights may be selected by the eNB to improve performance.
Examples herein may include, for example, the subject matter of a method, an apparatus to implement acts or blocks of a method, at least one machine readable medium comprising executable instructions that when implemented by a machine (e.g., a processor with memory, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), etc.) cause the machine to implement acts of a method or apparatus or system for parallel communication using a variety of communication techniques in accordance with the described embodiments and examples.
Example 1 is an apparatus configured to be employed within an evolved node b (enb), comprising a processor and transmitter circuitry. The processor is configured to: generating a grant assisted access (LAA) burst comprising a channel reservation signal, a LAA preamble, one or more Downlink (DL) control channel messages, and one or more data payloads; generating LAA burst control information associated with the LAA burst, wherein the LAA burst control information indicates a length of the LAA burst; generating a physical layer code of the LAA burst control information; and a transmitter circuit configured to transmit a physical layer encoding of the LAA burst control information over the unlicensed carrier.
Example 2 includes the subject matter of example 1, wherein the transmitter circuitry is configured to transmit the LAA burst control information via a first Downlink Control Information (DCI) message of the one or more DL control channel messages of the LAA burst.
Example 3 includes the subject matter of example 2, wherein the first DCI message has an LAA-specific DCI format.
Example 4 includes the subject matter of example 1, wherein the transmitter circuitry is configured to transmit the LAA burst control information embedded in a sequence within a LAA preamble of the LAA burst.
Example 5 includes the subject matter of example 4, wherein the sequence facilitates synchronization of one or more User Equipments (UEs) with the eNB.
Example 6 includes the subject matter of example 1, wherein the transmitter circuitry is configured to transmit the LAA burst control information over the LAA burst control channel within the LAA preamble of the LAA burst.
Example 7 includes the subject matter of any of examples 1-6, including or omitting the optional features, wherein the LAA burst control information comprises a Request To Send (RTS) message indicating a set of one or more User Equipments (UEs), and wherein the apparatus further comprises receiver circuitry configured to receive a Clear To Send (CTS) message from at least one UE in the set.
Example 8 includes the subject matter of example 7, including or omitting the optional features, wherein the one or more UEs comprise N UEs, wherein N is one of: a predetermined number, a number configured by higher layer signaling, or a number indicated by LAA burst control information.
Example 9 includes the subject matter of any of examples 1-6, including or omitting optional features, wherein the LAA burst control information comprises one or more of: cell identification information, operator identification information, Discovery Reference Symbol (DRS) configuration information, Time Division Duplex (TDD) configuration information, Downlink (DL) and Uplink (UL) transmission power information, or an indication of whether or not to transmit a Physical Broadcast Channel (PBCH) within an LAA burst.
Example 10 includes the subject matter of any of examples 1-8, including or omitting optional features, wherein the LAA burst control information comprises one or more of: cell identification information, operator identification information, Discovery Reference Symbol (DRS) configuration information, Time Division Duplex (TDD) configuration information, Downlink (DL) and Uplink (UL) transmission power information, or an indication of whether or not to transmit a Physical Broadcast Channel (PBCH) within an LAA burst.
Example 11 includes the subject matter of example 1, wherein the LAA burst control information comprises a Request To Send (RTS) message indicating a set of one or more User Equipments (UEs), and wherein the apparatus further comprises receiver circuitry configured to receive a Clear To Send (CTS) message from at least one UE in the set.
Example 12 includes the subject matter of example 1, wherein the LAA burst control information comprises one or more of: cell identification information, operator identification information, Discovery Reference Symbol (DRS) configuration information, Time Division Duplex (TDD) configuration information, Downlink (DL) and Uplink (UL) transmission power information, or an indication of whether or not to transmit a Physical Broadcast Channel (PBCH) within an LAA burst.
Example 13 is a machine-readable medium comprising instructions that, when executed, cause an evolved node b (enb): implementing a Clear Channel Assessment (CCA) or an extended CCA on an unlicensed carrier; constructing a Licensed Assisted Access (LAA) burst comprising a channel reservation signal, a LAA preamble, one or more data payloads, and one or more Physical Downlink Control Channel (PDCCH) or enhanced PDCCH (ePDCCH) messages associated with the one or more data payloads; generating LAA burst control information indicating configuration information associated with the LAA burst; and transmitting the LAA burst and the LAA burst control information through the unlicensed carrier, wherein the LAA burst control information is transmitted through an LAA burst control channel message in an LAA burst control channel embedded in the LAA preamble.
Example 14 includes the subject matter of example 13, wherein the LAA burst control channel message comprises a burst control channel payload comprising at least a portion of the LAA burst control information and a Cyclic Redundancy Check (CRC).
Example 15 includes the subject matter of example 14, wherein the CRC includes N bits, wherein N is one of 8, 16, or 24.
Example 16 includes the subject matter of example 14, wherein the LAA burst control channel message further comprises a header indicating a set of User Equipments (UEs) to which the data is to be transmitted over the LAA burst.
Example 17 includes the subject matter of any of examples 13-16, including or omitting the optional feature, wherein the channel coding is by one of tail-biting convolutional codes (TBCC) or Turbo Codes (TC) for the LAA burst control channel message.
Example 18 includes the subject matter of example 17, including or omitting the optional feature, wherein the channel coded LAA burst control channel message is rate matched to fill available Resource Elements (REs) in a system bandwidth associated with the unlicensed carrier.
Example 19 includes the subject matter of any of examples 13-16, including or omitting the optional feature, wherein the LAA burst control channel message is scrambled by a scrambling sequence initialized with a scrambling seed based at least in part on a cell identity associated with the eNB.
Example 20 includes the subject matter of example 19, including or omitting the optional features, wherein the scrambling seed is additionally based at least in part on one or more of a frame index, a subframe index, or an Orthogonal Frequency Division Multiplexing (OFDM) symbol index.
Example 21 includes the subject matter of examples 13-16, including or omitting the optional feature wherein the LAA burst control channel message is modulated by one of Binary Phase Shift Keying (BPSK) or Quadrature Phase Shift Keying (QPSK).
Example 22 includes the subject matter of any one of examples 13-16, including or omitting the optional feature, wherein the LAA burst control information comprises a Request To Send (RTS) message comprising receiver address information indicating, by a bitmap, whether a Clear To Send (CTS) message is requested from each of the one or more UEs.
Example 23 includes the subject matter of example 13, wherein the LAA burst control channel message is channel coded by one of a tail-biting convolutional code (TBCC) or a Turbo Code (TC).
Example 24 includes the subject matter of example 13, wherein the LAA burst control channel message is scrambled by a scrambling sequence initialized with a scrambling seed, the scrambling seed based at least in part on a cell identity associated with the eNB.
Example 25 includes the subject matter of example 13, wherein the LAA burst control channel message is modulated by one of Binary Phase Shift Keying (BPSK) or Quadrature Phase Shift Keying (QPSK).
Example 26 includes the subject matter of example 13, wherein the LAA burst control information comprises a Request To Send (RTS) message comprising receiver address information indicating, via a bitmap, whether a Clear To Send (CTS) message is requested from each of the one or more UEs.
Example 27 is an apparatus configured to be employed within a User Equipment (UE), comprising receiver circuitry and a processor. The receiver circuitry is configured to receive, over an unlicensed carrier, a Licensed Assisted Access (LAA) preamble and at least one Physical Downlink Control Channel (PDCCH) or enhanced PDCCH (ePDCCH) message for a LAA burst transmission, wherein the LAA preamble or the at least one PDCCH or ePDCCH message includes LAA burst control information indicating configuration information associated with the LAA burst transmission. A processor is operably coupled to the receiver circuit and configured to: recovering LAA burst control information from the LAA preamble or the at least one PDCCH or ePDCCH message; and determining a length of the LAA burst transmission based on the recovered LAA burst control information.
Example 28 includes the subject matter of example 27, wherein the LAA preamble comprises LAA burst control information over a dedicated LAA burst control channel, and wherein the processor is configured to recover the LAA burst control information by decoding the LAA burst control channel.
Example 29 includes the subject matter of any one of examples 27-28, including or omitting the optional feature, wherein the LAA burst control information includes a Request To Send (RTS) message and a receiver address information field indicating the UE, wherein the receiver circuitry is configured to implement a Clear Channel Assessment (CCA) or an extended CCA in response to the RTS message, and wherein the apparatus further comprises transmitter circuitry configured to transmit a Clear To Send (CTS) message in response to the CCA or the extended CCA indicating the unlicensed carrier is clear.
Example 30 includes the subject matter of example 29, including or omitting the optional feature, wherein the receiver address information field indicates the UE through a Radio Network Temporary Identity (RNTI) or an International Mobile Subscriber Identity (IMSI) of the UE.
Example 31 includes the subject matter of example 29, including or omitting the optional feature, wherein the receiver address information field indicates the UE by a bit associated with the UE, and wherein the receiver circuitry is further configured to receive a Radio Resource Control (RRC) signal indicating the bit associated with the UE.
Example 32 includes the subject matter of example 29, including or omitting the optional feature, wherein the LAA burst control information comprises Transmit Power Control (TPC) information, and wherein the transmitter circuitry is configured to transmit at least one of a CTS message or uplink data based on the TPC information.
Example 33 includes the subject matter of any one of examples 27-32, including or omitting the optional feature, wherein the processor is a baseband processor.
Example 34 includes the subject matter of example 27, wherein the LAA burst control information includes a Request To Send (RTS) message and a receiver address information field indicating the UE, wherein the receiver circuitry is configured to implement a Clear Channel Assessment (CCA) or an extended CCA in response to the RTS message, and wherein the apparatus further comprises transmitter circuitry configured to transmit a Clear To Send (CTS) message in response to the CCA or the extended CCA indicating the unlicensed carrier is clear.
Example 35 includes the subject matter of example 27, wherein the processor is a baseband processor.
Example 36 is an apparatus configured to be employed within an evolved node b (enb), comprising means for processing and means for transmitting. The means for processing is configured to: generating a grant assisted access (LAA) burst comprising a channel reservation signal, a LAA preamble, one or more Downlink (DL) control channel messages, and one or more data payloads; generating LAA burst control information associated with the LAA burst, wherein the LAA burst control information indicates a length of the LAA burst; and generating a physical layer coding of the LAA burst control information. The means for transmitting is configured to transmit physical layer coding of the LAA burst control information over the unlicensed carrier.
Example 37 is an apparatus configured to be employed within a User Equipment (UE), comprising means for receiving and means for processing. The means for receiving is configured to receive, over an unlicensed carrier, a Licensed Assisted Access (LAA) preamble and at least one Physical Downlink Control Channel (PDCCH) or enhanced PDCCH (ePDCCH) message for a LAA burst transmission, wherein the LAA preamble or the at least one PDCCH or ePDCCH message includes LAA burst control information indicating configuration information associated with the LAA burst transmission. The means for processing is operatively coupled to the means for receiving and configured to: recovering LAA burst control information from the LAA preamble or the at least one PDCCH or ePDCCH message; and determining a length of the LAA burst transmission based on the recovered LAA burst control information.
The above description of illustrated embodiments of the inventive subject matter, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosed embodiments to the precise forms disclosed. Although specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various modifications are possible within the scope of the embodiments and examples, as those skilled in the relevant art will recognize.
In this regard, while the disclosed subject matter has been described in connection with various embodiments and corresponding figures, it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiment for performing the same, similar, alternative or alternative function of the disclosed subject matter without deviating therefrom. Thus, the disclosed subject matter should not be limited to any single embodiment described herein, but rather construed in breadth and scope in accordance with the appended claims.
In particular regard to the various functions performed by the above described components or structures (assemblies, devices, circuits, systems, etc.), the terms (including a reference to a "means") used to describe such components are intended to correspond, unless otherwise indicated, to any component or structure which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations. In addition, while a particular feature may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.