Disclosure of Invention
The invention aims to provide a wireless communication method, a terminal and an access point aiming at all or part of the problems, so as to accurately and efficiently solve the problem of communication conflict of a multi-terminal access system.
The technical scheme adopted by the invention is as follows:
A wireless communication method is applied to a multi-terminal access system, and comprises the following steps:
In a multi-terminal access system, first information is utilized in a downlink channel to explicitly indicate that an uplink time slot is occupied, so that a terminal which is not accessed to the system pauses in the uplink time slot access system when the first information is detected.
Further, the using the first information to explicitly indicate the occupancy state of the uplink time slot in the downlink channel includes:
And transmitting the first information in a downlink channel corresponding to the downlink time slot of the terminal of the allowed access system so as to explicitly indicate that the uplink time slot of the terminal of the allowed access system is occupied.
Further, the first information explicitly indicates an uplink time slot occupied by the terminal of the allowed access system.
Further, the sending the first information in a downlink timeslot corresponding to a terminal allowed to access the system includes:
And transmitting the first information in downlink time slots corresponding to all uplink time slots occupied by the terminal of the allowed access system.
Further, the method for enabling the terminal of the non-access system to suspend the access system in the uplink time slot when the first information is detected includes:
And enabling the terminal which is not accessed to the system to pause to access the system in the uplink time slot when the first information is detected in the downlink time slot.
Further, the first information is an explicit identifier or information carried in an explicit identifier.
Further, the first information is invalid for a terminal allowed to access the system.
Further, the method also comprises the step of utilizing second information in a downlink channel to explicitly indicate the terminal of the allowed access system so as to indicate the terminal of the allowed access system to disregard the first information.
The invention also provides a terminal applied to a multi-terminal access system, wherein the terminal is configured to:
Before accessing the system, detecting whether the downlink channel contains first information which explicitly indicates that the uplink time slot is occupied, and if the first information is detected, suspending the access of the system in the uplink time slot.
The invention also provides an access point applied to a multi-terminal access system, the access point is configured to:
And using the first information in the downlink channel to explicitly indicate that the uplink time slot is occupied, so that a terminal which is not accessed to the system pauses to access the system in the uplink time slot when the first information is detected.
In summary, due to the adoption of the technical scheme, the beneficial effects of the invention are as follows:
The application utilizes the downlink channel to transmit the busy and idle state of the uplink time slot, so that other terminals in the uplink time slot actively avoid, and compared with the mode of frequently carrying out idle channel assessment by the terminals, on one hand, the application utilizes the first information in the downlink channel to clearly indicate the busy and idle state of the uplink time slot, has extremely high certainty and accuracy, can not cause the problem of detection errors, and can effectively improve the large-scale access performance and the uplink performance under the condition of effectively solving the access conflict. On the other hand, the terminal only needs to perform intermittent information detection in each frame, and does not need to evaluate the channel state frequently, so that the whole energy consumption of the system can be effectively reduced.
Detailed Description
All of the features disclosed in this specification, or all of the steps in a method or process disclosed, may be combined in any combination, except for mutually exclusive features and/or steps.
Any feature disclosed in this specification (including any accompanying claims, abstract) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. That is, each feature is one example only of a generic series of equivalent or similar features, unless expressly stated otherwise.
Aiming at the access conflict phenomenon commonly existing in a multi-terminal access system, the prior art either does not consider the conflict phenomenon and chooses to continuously try to resend data to realize successful transfer of the data, such as communication protocols of LoRa, sigFox and the like, or frequently evaluates the channel state by adopting a mode such as CCA (CLEAR CHANNEL ASSESSMENT, clear channel evaluation) and the like, and accesses the system when the channel is evaluated to be clear, but the mode is seriously influenced by channel environment and the like, the problem of inaccurate channel state evaluation can occur, detection error can be caused, access conflict phenomenon can still occur, or no terminal is accessed when the channel is clear, so that the access performance is poor. Aiming at the defects, the embodiment of the application provides a wireless communication method, a terminal and an access point, which aim to accurately and efficiently solve the problem of access conflict of a multi-terminal access system, further avoid unnecessary access conflict and improve large-scale access performance and uplink performance.
In some embodiments, the wireless communication method provided by the present application includes:
in a multi-terminal access system, first information is utilized in a downlink channel to explicitly indicate that an uplink time slot is occupied, so that a terminal which is not accessed to the system pauses to access the system in the uplink time slot when the first information is detected.
Large-scale terminals may cause access collisions when they access the system at the same time. As shown in fig. 1, when a large-scale terminal prepares to Access a system, access requests are sent to a certain uplink time slot of an uplink channel, and when the system (through an Access Point (AP) node such as a base station) receives each Access request in the uplink time slot, only one terminal is allowed to Access. For a certain terminal, before accessing the system, it will first detect whether the downlink channel of the current frame contains the first information, if so, it is considered that the system cannot be accessed in the current frame, access is paused, the next frame is waited to re-detect whether the downlink channel contains the first information, and the system is accessed in the corresponding uplink time slot of the frame by cycling until the downlink channel of the certain frame does not detect the first information. Therefore, unnecessary channel evaluation and access attempt by the terminal can be avoided, and the overall energy consumption of the system is reduced. In addition, according to the method, the terminal does not need to carry out access attempt according to the channel evaluation result, directly decides whether to suspend access or directly access according to the explicit instruction, and can not cause access conflict or endless idle of the channel due to detection errors, so that the access performance and the uplink performance can be improved.
As an optional implementation manner, the embodiment of the application regards each uplink time slot as a sub-channel which only allows a single terminal to access, and can perform independent control, thereby reducing the time slot waste of unified control. Each uplink time slot may have multiple terminals that want to access the system, so for each occupied uplink time slot, the system needs to explicitly tell that the uplink time slot is occupied in the corresponding downlink time slot. So, the first information is utilized in the downlink channel to explicitly indicate the occupation state of the uplink time slot, including:
The first information is transmitted in the downlink channel corresponding to the downlink time slot of the terminal allowed to access the system to explicitly indicate that the uplink time slot of the terminal allowed to access the system is occupied. Therefore, when a terminal which is not accessed to the system from a certain uplink time slot is planned to be accessed to the system, the idle state of the uplink time slot can be known only by detecting whether the corresponding downlink time slot contains the first information or not, and the detection frequency of the terminal can be further reduced without frequently detecting the first information in the frame structure of the whole downlink channel. And when the terminal of the unaccessed system detects the first information in the downlink time slot (corresponding to the uplink time slot of the planned access system), suspending the terminal of the unaccessed system from accessing the system in the uplink time slot of the planned access system.
As an alternative embodiment, the first information carried in the downlink channel explicitly indicates the uplink time slot occupied by the terminal allowed to access the system. Namely, explicitly indicates which uplink time slot is occupied by the terminal of the access system, so that the idle time slot of the channel can be accurately distinguished, and unnecessary channel resource waste is avoided.
For example, for some frame structures, the downlink time slots and the uplink time slots are configured in a 1:1 relationship, such as the frame structure shown in fig. 2, S represents the synchronization time slot, D represents the downlink time slot, U represents the uplink time slot, G represents the gap time slot, which includes 8 downlink time slots and 8 uplink time slots, so that one downlink time slot corresponds to one uplink time slot. For such a frame structure, only an explicit identifier is used to serve as the first information in the downlink timeslot, so that the corresponding uplink timeslot can be explicitly indicated as being occupied. Correspondingly, the terminal only needs to detect whether the downlink time slot contains the explicit identifier, and can determine whether the uplink time slot to be accessed is occupied.
As a possible implementation manner, a BNACK (slot busy broadcast packet, length is 1/8 of that of a short message) message is sent in a downlink slot to indicate that the corresponding uplink slot is occupied, in the uplink slot, only the uplink data access of the terminal allowed to access is allowed, and after the other terminals receive BNACK message in the downlink slot, the corresponding uplink slot is indicated to be busy, the access plan in the uplink slot is suspended, and if the terminal does not receive BNACK message in the downlink slot, the corresponding uplink slot is indicated to be idle, so that the system can be accessed in the subsequent uplink slot.
For another frame structure, the configuration ratio of the downlink time slot to the uplink time slot is 1:2, i.e. one downlink time slot corresponds to two uplink time slots simultaneously, and the two uplink time slots belong to different groups (groups), which are assumed to be group0 and group1. As shown in the frame structure of fig. 3, 8 downlink slots and 16 uplink slots are configured. For such a frame structure, the occupancy state of the uplink time slot cannot be explicitly indicated only by including the BNACK message, and a corresponding message needs to be further configured in the BNACK message to explicitly indicate the uplink time slot occupied by the terminal allowed to access the system. Correspondingly, the terminals of the two uplink time slot access systems (corresponding to the same downlink time slot) receive the same BNACK message, and the two terminals need to detect BNACK message in the corresponding downlink time slot, and further need to detect the specific information carried in the BNACK message to identify and judge whether the uplink time slot of the planned access is occupied.
As a possible implementation manner, 2bit information is configured in BNACK messages, so as to be used for indicating the busy/idle states of two uplink timeslots corresponding to a downlink timeslot. Assuming that the 2bit information is 0b10, the uplink slot indicating group0 is idle, and the uplink slot of group1 is occupied (or vice versa if it is occupied by 0). The two uplink time slots of the terminal receive the BNACK message, wherein the terminal using the uplink time slot of group0 can access the system, and the terminal using the uplink time slot of group1 pauses access. If the two uplink timeslots are idle, the downlink timeslot may not transmit BNACK or BNACK messages and the information carried therein is 0b00.
For other frame structure configurations, such as a frame structure with a downlink time slot to uplink time slot number ratio of 1:K (K is a positive integer greater than 2), the principle is the same, for example, kbit information is configured in BNACK message to explicitly indicate a specific occupied uplink time slot.
In summary, the first information sent on the downlink channel may be an explicit identifier, for example, BNACK messages, or may be information carried in an explicit identifier, for example, 2bit information carried in BNACK messages.
For a terminal allowed to access the system, uplink data may need to be sent in multiple data frames, that is, occupy corresponding uplink timeslots in multiple consecutive data frames. In some alternative embodiments, the first information is sent in the downlink time slots corresponding to all the uplink time slots occupied by the terminals allowed to access the system.
In some embodiments, the system receives an access request of a terminal (a terminal allowed to access the system) in an uplink timeslot of a certain frame, then marks the uplink timeslots of the following N frames (N is an integer, determined by the amount of data identified in the access request) as occupied according to the access request, i.e. all occupied by the terminal, records terminal information, and starts broadcasting first information in the downlink timeslot corresponding to the next frame (e.g. BNACK messages in the previous embodiment). Before the system arranges the downlink time slot tasks, it checks whether the uplink time slot of the current frame is occupied according to the marked state, if so, it arranges and broadcasts the first information in the downlink time slot corresponding to the uplink time slot. And when the terminal of the uplink time slot access system detects the first information, marking the current frame as a busy state, suspending the access system in the current frame, and continuing to wait for the detection result of the next frame on the first information in the corresponding downlink time slot, so as to circulate until the first information is not detected in the corresponding downlink time slot, and then accessing the corresponding uplink time slot.
In addition, if the communication is abnormal, after the terminal that has originally accessed the system sends uplink data in the uplink time slot of the next frame with the abnormality, the system will re-mark the uplink time slots of the next N frames as occupied, that is, after a certain frame does not receive the subsequent uplink data of the terminal due to the communication abnormality, the system still sends first information in the corresponding downlink time slot of the next N-1 frame, so as to reserve channel resources for retransmitting data for the terminal.
In addition, the first information broadcast by the system in the downlink timeslot can still be detected by the terminal of the allowed access system, so in some alternative embodiments, the first message sent in the downlink timeslot is invalid for the terminal of the allowed access system, so that the terminal of the allowed access system continues to send uplink data, while other terminals that are not accessed in the uplink timeslot suspend access.
In some embodiments, in addition to sending the first information to prevent other terminals from accessing in the downlink channel, second information is also sent to explicitly indicate the terminals allowed to access the system, so as to indicate the terminals allowed to access the system to disregard the first information. The second information is only allowed to be received and decoded by the terminals of the access system.
For example, when multiple terminals send an access request in a certain uplink time slot, the system allows only one terminal to access the system, and broadcasts first information in the corresponding downlink time slot of the next frame to explicitly indicate that the uplink time slot is occupied. In addition, ACK (feedback data packet, length is 1/8 of short message) check information is sent to the terminal of the allowed access system in the downlink time slot, which indicates that the terminal is allowed to access the system. After receiving the ACK checking information, the terminal enters a flow of transmitting uplink data, so that the first information received by the same downlink time slot in the subsequent frame can be disregarded until the transmission of the uplink data is finished.
In some embodiments, the terminal provided by the present application is configured to:
Before accessing the system, detecting whether the downlink channel contains first information which explicitly indicates that the uplink time slot is occupied, and if the first information is detected, suspending the access of the system in the uplink time slot. The configuration information of the terminal, which may refer to the relevant features of the wireless communication method described above, will not be described in detail herein.
As an alternative embodiment, before the terminal accesses the system, it detects whether a downlink time slot of the downlink channel contains the first information, where the downlink time slot corresponds to an uplink time slot in which the terminal plans to access the system.
Fig. 4 shows a specific configuration manner of a terminal according to an embodiment of the present application. In the idle state, if there is data to be transmitted, the terminal detects first information (for example, BNACK messages) in a downlink slot corresponding to an uplink slot of a certain planned access system, if the first information is detected, the terminal pauses access in a current frame, re-detects the first message in a corresponding downlink slot of a next frame until the first information is not detected in a corresponding downlink slot, transmits uplink data in a corresponding uplink slot of the next frame, and then receives ACK check information (serving as second information) in a corresponding downlink slot of the next frame. If the ACK check information is not received, the communication is abnormal, after the terminal randomly backs M frames (M is an integer), the first information is detected in the corresponding downlink time slot again in the M+1st frame and the system is accessed again, if the auxiliary receives the ACK check information, whether the transmission of the uplink data is finished is judged, if the transmission is finished, the idle state is returned, if the transmission is not finished, the uplink data is continuously transmitted in the corresponding uplink time slot of the next frame, and the cycle is repeated until the transmission of the uplink data is finished, and the idle state is returned.
In some embodiments, the access point provided by the present application is configured to:
And using the first information in the downlink channel to explicitly indicate that the uplink time slot is occupied, so that the terminal of the non-access system pauses the access system in the uplink time slot when the first information is detected. The configuration information is triggered after a certain terminal accesses the system in the uplink time slot.
For the configuration information of the access point, reference may be made to the relevant features of the wireless communication method described above, so that detailed description thereof will not be given here.
Fig. 5 shows a specific configuration manner of a terminal according to an embodiment of the present application. In the idle state, if the access point receives access requests (or called uplink data, including access packets or uplink data packets) of a plurality of terminals in one uplink time slot of a certain frame (assumed to be an X-th frame), only one of the terminals is allowed to access the system, that is, only one of the terminals will send ACK check information in response to the corresponding downlink time slot of the next frame (x+1th frame). For the received uplink data, judging whether the received uplink data is the last data packet, namely detecting how many frames of uplink time slots the terminal needs to occupy through an access request. If the data packet is the last data packet, only the corresponding uplink time slot of the next frame (namely the X+1st frame) is marked, and if the data packet is not the last data packet, the corresponding uplink time slot of the N frames after marking is needed to be occupied, namely the corresponding uplink time slot of the X+1st frame to the bottom X+N frame is marked to be occupied. And then, in the next frame, judging whether the current frame is a frame marked as an occupied uplink time slot, if so, transmitting first information in the corresponding downlink time slot of the current frame, judging whether uplink data is received in the corresponding uplink time slot of the current frame, otherwise, directly judging whether the uplink data is received in the corresponding uplink time slot of the current frame, if so, transmitting ACK check information to the corresponding terminal, returning to the process of judging whether the current frame is the last data packet, and otherwise, returning to the process of judging whether the next frame is the frame marked as the occupied uplink time slot.
As a more illustrative example, the configuration information of the access point may perform the following procedure:
The method comprises the steps that an access point receives an access request of a terminal A in one uplink time slot of a first frame, marks that the uplink time slots of the next N frames are all busy (occupied), records information of the access terminal, and sends ACK check information for the terminal A in a corresponding downlink time slot of a second frame.
And step two, before the access point arranges the downlink time slot task, checking whether the state of the uplink time slot corresponding to the downlink time slot of the current frame is busy, and if so, sending a general BNACK message.
And thirdly, when the terminal A receives BNACK messages in the downlink time slot of the second frame, marking that the state of the frame is busy, simultaneously, when the terminal A receives ACK cancellation verification information and marks that the uplink transmission flow is entered, the terminal A can disregard the busy state and continue to transmit uplink data until the data transmission is finished.
And fourthly, the other terminals B receive BNACK messages in the downlink time slot of the second frame or find that the uplink time slot is busy after decoding BNACK messages, mark the state of the frame as busy, consider that the frame cannot send uplink or access, and continue waiting for the detection result of the next frame on the downlink time slot.
And step five, other terminals C, due to abnormal reception, do not receive BNACK messages in the downlink time slot of the second frame, and meanwhile, have data to be transmitted, and transmit an access request.
And step six, the access point continues to receive the uplink data packet of the terminal A in the third frame, and then continues to mark that the uplink time slots of the next N frames are all busy, that is, abnormality occurs in a certain frame, the subsequent uplink data packet of the terminal A is not received, and BNACK messages still need to be sent in the corresponding downlink time slots of the subsequent (N-1) frame, so that a retransmission channel is reserved for the terminal A.
And step seven, the access point receives the access request of the terminal C at the same time in the third frame, and the access request of the terminal C is not responded because the uplink flow of the round is that the terminal A is the object.
And step eight, the access point clears the previous N frame mark when receiving the last data packet of the uplink of the terminal A, marks that the uplink time slot is busy only in the next frame, namely, only needs to send BNACK information in the downlink time slot of the next frame, and returns to the idle state.
And step nine, after the terminal A receives the last ACK check information, ending the uplink transmission flow, clearing the uplink flow mark and returning to an idle state.
The invention is not limited to the specific embodiments described above. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification, as well as to any novel one, or any novel combination, of the steps of the method or process disclosed.