Terminal, access point, and communication method

Abstract

This terminal is provided with: a control circuit that determines, on the basis of a prescribed rule, a carrier sense time for performing carrier sensing in a prescribed time interval; and a transmission circuit that transmits a prescribed type of signal on the basis of the result of the carrier sensing.

Description

Terminal, access point, and communication method

[0001] The present disclosure relates to a terminal, an access point, and a communication method.

[0002] The technical specifications for IEEE 802.11be (hereinafter referred to as "11be") are currently being developed as the successor to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, IEEE 802.11ax (hereinafter referred to as "11ax"). 11ax is also known as "High Efficiency (HE)," and 11be is also known as "Extremely High Throughput (EHT)." The Ultra High Reliability (UHR) Study Group (SG) is also currently discussing the required specifications for the successor to 11be (hereinafter referred to as "UHR").

[0003] IEEE 802.11-23 / 0092r0, Preemption for Low Latency ApplicationIEEE 802.11-23 / 0378r0, Enhanced Scheduling Method for Low Latency TrafficIEEE P802.11be / D3.0

[0004] However, the method for controlling signal transmission in wireless communication such as wireless LAN has not been fully studied.

[0005] Non-limiting embodiments of the present disclosure contribute to providing a terminal, an access point, and a communication method that can improve the efficiency of transmission control in wireless communication.

[0006] A terminal according to one embodiment of the present disclosure includes a control circuit that determines a carrier sense time for performing carrier sense in a predetermined time interval based on a predetermined rule, and a transmission circuit that transmits a predetermined type of signal based on the result of the carrier sense.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0008] According to an embodiment of the present disclosure, for example, it is possible to improve the efficiency of transmission control in wireless communication.

[0009] Further advantages and benefits of one embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features.

[0010] Figure 1: Block diagram showing an example of the configuration of a portion of an access point (AP) Figure 1: Block diagram showing an example of the configuration of a portion of a terminal Figure 1: Diagram showing an example of a sequence for multiple PPDU (PHY protocol data unit) transmission Figure 1: Diagram showing an example of a sequence for multiple PPDU transmission Figure 1: Block diagram showing an example of the configuration of an AP Figure 1: Block diagram showing an example of the configuration of a terminal Figure 1: Diagram showing an example of preemption control information Figure 1: Diagram showing an example of a sequence for notification ... a User Info field in a Multi-User (MU) - Request to Send (RTS) Transmission Opportunity (TXOP) sharing (TXS) Trigger frame Figure 1: Diagram showing an example of preemption control information Figure 1: Diagram showing an example sequence for multiple PPDU transmission Figure 1: Diagram showing an example sequence in a Restricted - Target Wake Time Service Period (R-TWT SP) Figure 1: Example of Request Type field format in the Broadcast TWT Parameter Set field TWT Diagram showing an example of operation Diagram showing an example of a sequence for PPDU transmission Diagram showing an example of preemption by random access Diagram showing an example of preemption by Null data packet (NDP) Feedback Report Poll (NFRP)

[0011] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings.

[0012] In UHR, the need for further reduction in latency (low latency) has been proposed (see, for example, Non-Patent Document 1 or 2). In addition, in UHR, it has been proposed to support aperiodic, unpredictable, dynamically changing traffic requiring low latency (also referred to as, for example, event-based low latency traffic) (see, for example, Non-Patent Document 3).

[0013] In the following, traffic that requires low latency will be referred to as "LL (Low latency) traffic."

[0014] For example, Non-Patent Document 2 discloses that transmission of a long-duration PPDU (PHY protocol data unit, also called a packet) in a transmission opportunity (TXOP) acquired by an access point (AP, also called an "AP STA," or "base station") may increase the delay of a terminal (STA, also called a "non-AP STA") having LL traffic. Non-Patent Document 2 proposes, as a countermeasure against increased delay, dividing and transmitting a PPDU with a limited time length (for example, a short time length) at a predetermined time interval.

[0015] Hereinafter, the non-transmission time (predetermined time period) immediately before the PPDU that the AP plans to transmit within the TXOP will be referred to as the "PPDU transmission gap."

[0016] A terminal having LL traffic can reduce delay by interrupting a PPDU scheduled for transmission with the LL traffic (hereinafter referred to as "preemption") during a PPDU transmission gap.

[0017] For example, if there are multiple terminals with LL traffic, the uplink signals from the multiple terminals may collide, and the AP may not be able to receive all the uplink signals, which may increase the delay.

[0018] In a non-limiting example of the present disclosure, an example of a method for reducing delays in LL traffic by reducing collisions of uplink signals between multiple terminals having LL traffic will be described. For example, in a non-limiting example of the present disclosure, a terminal having LL traffic is permitted to transmit uplink signals by carrier sense for a predetermined period without backoff during a PPDU transmission gap. This can reduce collisions of uplink signals even when multiple terminals having LL traffic exist.

[0019] (Embodiment 1) In this embodiment, for example, an AP sets a predetermined PPDU transmission gap in an acquired TXOP and transmits multiple PPDUs. Furthermore, the AP allows, for example, a terminal having LL traffic to transmit an uplink signal including the LL traffic in the PPDU transmission gap (preemption) without backoff. Furthermore, in this embodiment, the carrier sense time (or transmission timing) performed immediately before the transmission of the uplink signal of each terminal is made different, thereby reducing collisions of uplink signals between multiple terminals.

[0020] [Configuration of Wireless Communication System] The wireless communication system according to this embodiment may include, for example, an AP 100 and a terminal 200. In the wireless communication system, there may be, for example, two or more terminals 200.

[0021] FIG. 1 is a block diagram illustrating an exemplary configuration of a portion of an AP 100 according to an embodiment of the present disclosure. In the AP 100 illustrated in FIG. 1 , a control unit (e.g., corresponding to a control circuit) determines a carrier sense time for performing carrier sense during a predetermined time interval (e.g., a PPDU transmission gap) based on a predetermined rule. A receiving unit (e.g., corresponding to the receiving circuit) receives a signal of a predetermined type (e.g., LL traffic) transmitted in response to the carrier sense result. The AP 100 may also include a transmitting unit (e.g., corresponding to the transmitting circuit). The transmitting unit may transmit a DL PPDU (e.g., downlink transmission data) for each predetermined time interval. The transmitting unit may also transmit preemption control information for the LL traffic determined by the control unit (e.g., carrier sense time and / or information about the predetermined time interval) in a control frame (e.g., an RTS frame, a control frame aggregated within a DL PPDU, etc.) or a management frame.

[0022] FIG. 2 is a block diagram illustrating an exemplary configuration of a portion of a terminal 200 according to an embodiment of the present disclosure. In the terminal 200 illustrated in FIG. 2 , a control unit (e.g., corresponding to a control circuit) determines a carrier sense time for performing carrier sense during a predetermined time interval (e.g., a PPDU transmission gap) based on a predetermined rule. A transmission unit (e.g., corresponding to the transmission circuit) transmits a signal of a predetermined type (e.g., LL traffic) based on the result of the carrier sense. The terminal 200 may also include a receiving unit (e.g., corresponding to the receiving circuit). The receiving unit may receive a control frame (e.g., an RTS frame, a control frame aggregated in a DL PPDU, etc.) or a management frame transmitted by the AP 100, and acquire preemption control information (e.g., information regarding the predetermined time interval (e.g., a PPDU transmission gap) and / or instruction information for the carrier sense time) necessary for determining the carrier sense time.

[0023] For example, the AP 100 permits preemption of upstream signals limited to a predetermined traffic type (for example, LL traffic) in a PPDU transmission gap in a TXOP acquired by the AP 100.

[0024] For example, the terminal 200 receives a downlink PPDU (DL PPDU) transmitted from the AP 100. Then, the terminal 200 may perform preemption based on preemption control information indicated by any one of a preamble, a Medium Access Control (MAC) header, and a trigger frame included in the received PPDU, or a combination thereof. For example, if the terminal 200 has a traffic type for which preemption is permitted and the carrier sense result for a predetermined time is idle, the terminal 200 transmits (preempts) an uplink signal to the AP 100 in a PPDU transmission gap section.

[0025] Here, the preemption control information may include, for example, information regarding at least one of the time length of the TXOP acquired by AP 100, the presence or absence of a response signal (e.g., ACK or Block Ack) immediately after the PPDU, the PPDU transmission gap, the traffic type for which preemption is permitted, and the carrier sense time by terminal 200 (e.g., the carrier sense time to be set or a candidate for a configurable carrier sense time).

[0026] On the other hand, if the terminal 200 does not have a traffic type for which preemption is permitted, or if the carrier sense result is Busy, the terminal 200 determines that the uplink signal is not to be transmitted (preemption is not permitted).

[0027] The LL traffic may be a type that requires low latency, and may also be called, for example, Low Latency Traffic, Latency Sensitive Traffic, or Event-based low latency traffic.

[0028] As an example, an operation example (sequence) will be described in which a predetermined PPDU transmission gap is set in the TXOP acquired by the AP 100 and multiple PPDUs are transmitted (hereinafter referred to as multiple PPDU transmission).

[0029] FIG. 3 shows an example of a sequence of multiple PPDU transmission when terminal 200 does not have a traffic type for which preemption is permitted.

[0030] As shown in Fig. 3, the AP 100 sets the time corresponding to the PPDU transmission gap (for example, the time interval from when the AP 100 transmits a DL PPDU in a TXOP until when it transmits the next DL PPDU) to "SIFS (short interframe space) + 27 us." The AP 100 also transmits three DL PPDUs to the terminal 200 (STA1 in Fig. 3) within the TXOP. Note that in Fig. 3, ACKs for the DL PPDUs are controlled to be notified collectively at the end of the TXOP.

[0031] 3, the AP sets a PPDU transmission gap (e.g., SIFS+27 us) before transmitting each DL PPDU, but in another example, the PPDU transmission gap for the first DL PPDU (the PPDU immediately after receiving the CTS) may be set to SIFS, and the PPDU transmission gaps for the second and subsequent DL PPDUs may be set to SIFS+27 us. This prevents other STAs (e.g., STA2 and STA3) from interrupting transmission after the CTS frame to transmit data other than LL traffic when, for example, they fail to receive an RTS frame (e.g., fail to decode it).

[0032] In FIG. 3 , AP 100 may notify terminal 200 of preemption control information including information about the PPDU transmission gap, for example, by including the information in an RTS (request to send). Note that the signal used to notify the preemption control information is not limited to an RTS, and may be, for example, a trigger frame such as a multi-user (MU)-RTS trigger frame or an MU-RTS TXOP sharing (TXS) trigger frame. Also, the preemption control information may be included in, for example, a preamble (for example, a U-SIG field or an EHT-SIG field) included in a DL PPDU. Also, the preemption control information may be included in, for example, a MAC header (for example, an A-Control subfield of an HT Control field) or a beacon (for example, a Target Wake Time (TWT) element). Note that examples of preemption control information will be described later.

[0033] For example, in FIG. 3, before transmitting a DL PPDU, AP 100 performs carrier sensing in a PPDU transmission gap, and if the carrier sensing result is in the idle state, transmits the DL PPDU, and if it is in the busy state, suspends transmission of the DL PPDU.

[0034] In Figure 3, multiple (e.g., all) terminals 200 (STA1, STA2, and STA3 in Figure 3) connected to AP 100 do not perform preemption in the PPDU transmission gap because they do not have a traffic type (e.g., LL traffic) for which preemption is permitted.

[0035] FIG. 4 shows an example of a sequence of multiple PPDU transmission when terminal 200 has a traffic type for which preemption is permitted.

[0036] As shown in FIG. 4 , the AP 100 sets the time corresponding to the PPDU transmission gap (e.g., the time interval from when the AP 100 transmits a DL PPDU in a TXOP until when it transmits the next DL PPDU) to "SIFS (short interframe space) + 27 us." The AP 100 also schedules the transmission of three DL PPDUs to STA1 within the TXOP. Note that in FIG. 4 , ACKs for the DL PPDUs are controlled to be notified collectively at the end of the TXOP (not shown). Similarly to the example in FIG. 3 , the PPDU transmission gap before the first DL PPDU may be SIFS.

[0037] 4, multiple terminals 200 (STA2 and STA3 in FIG. 4) connected to AP 100 (AP in FIG. 4) have a traffic type for which preemption is permitted (e.g., LL traffic, also referred to as LL packets). Therefore, STA2 and STA3 attempt preemption in the PPDU transmission gap section.

[0038] For example, STA2 and STA3 perform carrier sensing (e.g., carrier sensing time) determined by a predetermined rule, and if the result of the carrier sensing is idle, they preemptively transmit (preempt) an uplink signal including LL traffic, but if it is busy, they do not preemptively transmit (preempt) an uplink signal.

[0039] For example, in the above-mentioned predetermined rule, the carrier sense time of each of STA2 and STA3 is set to be shorter than the PPDU transmission gap (e.g., the length of time until the AP 100 transmits the next DL PPDU). Also, in the above-mentioned predetermined rule, the carrier sense time may be different among multiple terminals 200 that are permitted to transmit uplink signals (e.g., preemption). In the example of Fig. 4, the carrier sense time of STA2 is set to SIFS + 18 us, and the carrier sense time of STA3 is set to SIFS + 9 us.

[0040] In this case, as shown in FIG. 4 , the preemption of STA3, whose carrier sense time is shorter than that of AP 100 (SIFS + 27 us) and STA2 (SIFS + 18 us), is given priority over STA2 and AP 100, so STA3 can transmit an uplink signal including LL traffic to AP 100. Furthermore, in the next PPDU transmission gap shown in the example of FIG. 4 , the preemption of STA2, whose carrier sense time is shorter than that of AP 100 (SIFS + 27 us), is given priority over AP 100, so STA2 can transmit an uplink signal including LL traffic to AP 100. This allows STA2 and STA3 to transmit uplink signals including LL traffic to AP 100, avoiding collision of uplink signals between STA2 and STA3.

[0041] Thus, according to this embodiment, even if there are multiple terminals 200 with LL traffic, collisions of uplink signals between terminals 200 can be reduced by varying the carrier sense time of each terminal 200.

[0042] [Configuration Example of AP 100] FIG. 5 is a block diagram showing a configuration example of the AP 100. As shown in FIG.

[0043] The AP 100 notifies preemption control information to a plurality of terminals 200. Furthermore, the AP 100 permits preemption from terminals 200 limited to some traffic types (e.g., LL traffic) in the PPDU transmission gap in the TXOP acquired by the AP 100.

[0044] The AP 100 shown in Figure 5 may include, for example, a scheduling unit 101, a data generation unit 102, an error correction coding unit 103, a modulation unit 104, a preamble generation unit 105, a PPDU generation unit 106, a radio transmission / reception unit 107, a separation unit 108, a preamble reception unit 109, a demodulation unit 110, and an error correction decoding unit 111.

[0045] At least one of the scheduling unit 101, data generation unit 102, error correction coding unit 103, modulation unit 104, preamble generation unit 105, PPDU generation unit 106, separation unit 108, preamble reception unit 109, demodulation unit 110 and error correction decoding unit 111 shown in Figure 5 may be included in the control unit shown in Figure 1, and the radio transmission / reception unit 107 shown in Figure 5 may be included in the reception unit shown in Figure 1.

[0046] 5, the scheduling unit 101 may perform scheduling for, for example, the terminal 200. For example, the scheduling unit 101 may perform scheduling for the transmission of multiple PPDUs within a TXOP for a destination terminal (for example, the terminal 200 that supports preemption, or an existing terminal that does not support preemption). For example, the scheduling unit 101 determines scheduling information for transmitting multiple downlink signals (for example, DL PPDUs) within a TXOP to the destination terminal, based on reception quality information, a transmission buffer state, etc., fed back from each terminal.

[0047] The scheduling information may include, for example, information regarding the radio resources to be allocated to the destination terminal (e.g., including at least one of the time length of the TXOP, the transmission bandwidth, the signal length of each PPDU, and the number of PPDUs to be transmitted within the TXOP), and the MCS to be applied to the downlink PPDU.

[0048] The scheduling information may also include, for example, preemption control information that is notified to multiple terminals 200 that may perform preemption. The preemption control information may also include, for example, multiple candidates for the carrier sense time to be used for preemption by the terminal 200. Each of the candidate carrier sense times is set to a time length shorter than the PPDU transmission gap time (e.g., SIFS+27 us in the case of FIG. 4 ) corresponding to the non-transmission section before PPDU transmission (e.g., the section between adjacent PPDUs) transmitted by the AP 100 in the TXOP. For example, in the case of FIG. 4 , a time length including SIFS+9 us and SIFS+18 us may be set as the candidate carrier sense time for the terminal 200. Note that the candidate carrier sense times may be notified in advance from the AP 100 to the connected terminals using a beacon or the like, or may be defined in advance in a specification.

[0049] Scheduling section 101 outputs the determined scheduling information to data generation section 102 , error correction coding section 103 , modulation section 104 , preamble generation section 105 and radio transmission / reception section 107 .

[0050] The data generating unit 102 generates data (downlink data) addressed to the destination terminal, and outputs the generated data to the error correction coding unit 103.

[0051] When preemption control information is notified to terminal 200 by a trigger frame, data generation section 102 generates a trigger frame (for example, an MU-RTS TXS trigger frame) and outputs the trigger frame together with data addressed to the destination terminal to error correction coding section 103. When preemption control information is notified to terminal 200 by a MAC header, data generation section 102 generates data in which a MAC header including the preemption control information is added to the data addressed to the destination terminal, and outputs the data to error correction coding section 103 together with the data addressed to the destination terminal.

[0052] The error correction coding unit 103 performs error correction coding on the data signal input from the data generation unit 102 and outputs the coded signal to the modulation unit 104. The coding rate for the data signal in the error correction coding unit 103 may be determined based on the scheduling information input from the scheduling unit 101, for example.

[0053] The modulation unit 104 modulates, for example, the signal input from the error correction coding unit 103 and outputs the modulated signal to the PPDU generation unit 106. Note that the modulation method applied in the modulation unit 104 may be determined based on, for example, the scheduling information input from the scheduling unit 101.

[0054] In addition, if the modulated signal is an OFDM (Orthogonal Frequency Division Multiplexing) signal, AP100 may form the OFDM signal by mapping the modulated signal to a predetermined frequency resource, performing IDFT (Inverse Discrete Fourier Transform) processing, and adding a cyclic prefix (CP).

[0055] The preamble generating unit 105 generates a preamble to be added to data addressed to the destination terminal based on the scheduling information from the scheduling unit 101. The preamble includes, for example, information used by the destination terminal to receive and decode the data. The preamble generating unit 105 outputs the generated preamble signal to the PPDU generating unit 106.

[0056] The PPDU generation unit 106 generates a single PPDU signal by time-multiplexing (e.g., multiplexing the preamble signal from the preamble generation unit 105 and the modulated signal from the modulation unit 104 in the order of preamble signal, modulated signal (OFDM signal)), and outputs the PPDU signal to the radio transmission / reception unit 107.

[0057] The radio transmission / reception unit 107 performs radio transmission processing such as D / A conversion and up-conversion to a carrier frequency on the PPDU signal input from the PPDU generation unit 106, and transmits the signal after radio transmission processing via an antenna. For example, the radio transmission / reception unit 107 may determine the transmission timing of the PPDU based on information (e.g., preemption control information) input from the scheduling unit 101, perform carrier sensing just before the transmission timing, and, if the carrier sensing result indicates an idle state, transmit the signal from the antenna according to the determined transmission timing.

[0058] In addition, the radio transmission / reception unit 107 receives a signal, for example, via an antenna, performs radio reception processing on the received signal, such as down-conversion to baseband and A / D conversion, and outputs the signal after radio reception processing to the separation unit 108.

[0059] The separator 108 separates, for example, a signal (PPDU) input from the radio transmitter / receiver 107 into a preamble signal and a data signal, outputs the preamble signal to the preamble receiver 109 , and outputs the data signal to the demodulator 110 .

[0060] The preamble receiving unit 109 demodulates and decodes the preamble signal from the separating unit 108, and if the signal is addressed to the AP 100, it instructs the demodulating unit 110 and the error correction decoding unit 111 to decode the data, and outputs control information (e.g., MCS, etc.) used for decoding to the demodulating unit 110 and the error correction decoding unit 111.

[0061] The demodulation unit 110 performs demodulation processing on the received data input from the separation unit 108 and outputs the demodulated signal to the error correction decoding unit 111. Note that the modulation scheme applied in the demodulation unit 110 may be determined based on control information input from the preamble receiving unit 109, for example.

[0062] Furthermore, when the signal input to the demodulation unit 110 is an OFDM signal, the AP 100 may perform CP removal processing and DFT processing on the OFDM signal.

[0063] The error correction decoding unit 111, for example, decodes the demodulated signal input from the demodulation unit 110 and outputs the decoded signal as a received data signal. Note that the coding rate applied in the error correction decoding unit 111 may be determined based on, for example, control information input from the preamble receiving unit 109. The received data signal may include, for example, an ACK response (e.g., Block Ack (BA)) from the destination terminal or LL traffic from the terminal 200.

[0064] [Configuration Example of Terminal 200] FIG. 6 is a block diagram showing a configuration example of the terminal 200. As shown in FIG.

[0065] The terminal 200 shown in Figure 6 may include, for example, a radio transceiver unit 201, a separation unit 202, a preamble receiving unit 203, a demodulation unit 204, an error correction decoding unit 205, a preemption control unit 206, a data generation unit 207, a scheduling unit 208, an error correction coding unit 209, a modulation unit 210, a preamble generation unit 211, and a PPDU generation unit 212.

[0066] In addition, at least one of the separation unit 202, preamble receiving unit 203, demodulation unit 204, error correction decoding unit 205, preemption control unit 206, data generation unit 207, scheduling unit 208, error correction coding unit 209, modulation unit 210, preamble generation unit 211, and PPDU generation unit 212 shown in Figure 6 may be included in the control unit shown in Figure 2, and the radio transmission / reception unit 201 shown in Figure 6 may be included in the transmission unit shown in Figure 2.

[0067] 6 , wireless transmission / reception section 201 receives a signal via an antenna, performs wireless reception processing such as down-conversion and A / D conversion on the received signal, and outputs the signal after wireless reception processing to demultiplexing section 202. Wireless transmission / reception section 201 also performs wireless transmission processing such as up-conversion and D / A conversion on a signal input from PPDU generation section 212, and transmits the signal after wireless transmission processing from the antenna.

[0068] For example, the wireless transceiver unit 201 determines the timing of transmitting a PPDU based on information (e.g., preemption control information including a carrier sense time) input from the preemption control unit 206. Furthermore, the wireless transceiver unit 201 may, for example, perform carrier sensing for a predetermined time immediately before the timing of transmitting a PPDU without relying on a back-off counter, and if the carrier sensing result indicates an idle state, transmit a signal including LL traffic generated by the PPDU generation unit 212 to the AP 100 from the antenna in accordance with the transmission timing. In this way, if the carrier sensing result indicates an idle state, the terminal 200 determines that transmission of LL traffic (e.g., preemption) is permitted without relying on a back-off counter, and transmits the permitted LL traffic via preemption.

[0069] The separator 202 separates, for example, a signal (PPDU) input from the radio transmitter / receiver 201 into a preamble signal and a data signal, outputs the preamble signal to the preamble receiver 203 , and outputs the data signal to the demodulator 204 .

[0070] Preamble receiving section 203 demodulates and decodes the preamble signal from demultiplexing section 202, and if the signal is addressed to terminal 200, instructs demodulating section 204 and error correction decoding section 205 to decode the data, and outputs control information used for decoding (for example, MCS) to demodulating section 204 and error correction decoding section 205. Furthermore, if preemption control information is included in the preamble, preamble receiving section 203 outputs the preemption control information to preemption control section 206.

[0071] The demodulation unit 204 performs demodulation processing on the received data input from the separation unit 202, for example, and outputs the demodulated signal to the error correction decoding unit 205. Note that the modulation scheme applied in the demodulation unit 204 may be determined based on control information (e.g., scheduling information) input from the preamble receiving unit 203, for example.

[0072] Furthermore, when the signal input to the demodulation unit 204 is an OFDM signal, the AP 100 may perform CP removal processing and DFT processing on the OFDM signal.

[0073] For example, the error correction decoding unit 205 decodes the demodulated signal input from the demodulation unit 204, and when the decoded signal includes preemption control information, outputs the preemption control information to the preemption control unit 206. Note that the coding rate applied in the error correction decoding unit 205 may be determined based on control information (for example, scheduling information) input from the preamble receiving unit 203, for example.

[0074] The preemption control unit 206 acquires information about the traffic type for which preemption is permitted (e.g., LL traffic) included in the preemption control information input from either or both of the preamble receiving unit 203 and the error correction decoding unit 205. For example, when the terminal 200 has LL traffic, the preemption control unit 206 instructs the data generating unit 207 to generate data. Note that the size of the data generated by the terminal 200 may be determined based on information about at least one of the time length of the TXOP and the time length of the PPDU included in the preemption control information. Furthermore, the transmission bandwidth of the transmission data may be set to, for example, at least a part of the transmission bandwidth of the DL PPDU. Furthermore, the size of the transmission data may be determined based on, for example, the transmission bandwidth.

[0075] Furthermore, the preemption control unit 206 determines, for example, the carrier sense time of the terminal 200 in preemption.

[0076] For example, the preemption control unit 206 may determine one of multiple candidate carrier sense times included in the preemption control information. For example, the preemption control unit 206 may randomly select one time from multiple candidate carrier sense times. The preemption control unit 206 may determine one of the candidate carrier sense times as the carrier sense time to be performed immediately before preemption. For example, in the example of FIG. 4 , STA2 and STA3, which are terminals 200 having LL traffic for which preemption is permitted, use SIFS+18 us and SIFS+9 us as carrier sense times, respectively. This gives priority to the preemption of STA3 in the first PPDU transmission gap, allowing uplink signals to be transmitted between STA2 and STA3 without collision. The carrier sense time selection process may be performed once within a TXOP or for each PPDU transmission gap (each preemption opportunity).

[0077] Alternatively, the preemption control unit 206 may determine the carrier sense time to be performed immediately before preemption based on the carrier sense time (time length) explicitly notified (or set) by the AP 100 to each terminal 200. For example, the AP 100 may set different carrier sense times for the multiple terminals 200, thereby preventing collisions between LL traffic transmissions from each of the multiple terminals 200 to the AP 100.

[0078] The data generator 207 generates uplink data. The uplink data may include, for example, LL traffic. The data generator 207 outputs the generated data signal to the error correction encoder 209.

[0079] The scheduling unit 208 outputs, for example, control information from the preemption control unit 206 (for example, scheduling information including an uplink signal length determined from TXOP information acquired by the AP 100, the number of streams to be applied to data, and MCS) to the error correction coding unit 209, the modulation unit 210, and the preamble generation unit 211. Furthermore, the scheduling unit 208 may determine the PPDU length of the uplink signal based on, for example, the TXOP information from the preemption control unit 206 or a restriction on the size of the PPDU length.

[0080] The error correction coding unit 209 performs error correction coding on the data signal input from the data generation unit 207 and outputs the coded signal to the modulation unit 210. The coding rate for the data signal in the error correction coding unit 209 may be determined based on the scheduling information input from the scheduling unit 208, for example.

[0081] The modulation unit 210 modulates, for example, the signal input from the error correction coding unit 209 and outputs the modulated signal to the PPDU generation unit 212. Note that the modulation method applied in the modulation unit 210 may be determined based on, for example, the scheduling information input from the scheduling unit 208.

[0082] Furthermore, when the modulated signal is an OFDM signal, terminal 200 may form the OFDM signal by mapping the modulated signal to a predetermined frequency resource, performing IDFT processing, and adding a cyclic prefix (CP).

[0083] The preamble generation unit 211 generates a preamble to be added to data addressed to the AP 100 based on the scheduling information from the scheduling unit 208. The preamble includes, for example, information used by the AP 100 to receive and decode the data. The preamble generation unit 211 outputs the generated preamble signal to the PPDU generation unit 212.

[0084] The PPDU generation unit 212 generates one PPDU by time-multiplexing (multiplexing the preamble signal, then the OFDM signal) the preamble signal from the preamble generation unit 211 and the modulated signal (e.g., OFDM signal) from the modulation unit 210, and outputs the PPDU to the radio transmission / reception unit 201.

[0085] The configuration examples of the AP 100 and the terminal 200 have been described above.

[0086] [Method of Notifying Preemption Control Information] Next, an example of a method of notifying preemption control information from the AP 100 to the terminal 200 will be described.

[0087] The preemption control information may include, for example, information regarding at least one of whether preemption is permitted within the TXOP, whether an ACK is present immediately after the PPDU, the PPDU transmission gap until the next PPDU, the traffic type for which preemption is permitted, and the terminal's carrier sense time during preemption (e.g., the setting time or a setting candidate).

[0088] For example, the PPDU transmission gap and carrier sense time may be reported as times in microseconds, or a predetermined Inter Frame Space (IFS) defined in the specifications may be reported. The predetermined IFS may be, for example, any of Short IFS (SIFS), Arbitration IFS (AIFS), Distributed Coordination Function (DCF) IFS (DIFS), and Point Coordination Function (PCF) IFS (PIFS).

[0089] The information regarding the traffic type for which preemption is permitted may be, for example, information in a bitmap format indicating whether or not preemption is permitted for each traffic type (e.g., TID: Traffic Identifier). Furthermore, for example, the traffic for which preemption is permitted (e.g., LL traffic) may be defined in the specifications. When the traffic for which preemption is permitted is defined in the specifications, notification of the traffic type information for which preemption is permitted from the AP 100 to the terminal 200 may be omitted.

[0090] The information regarding the carrier sense time of terminal 200 during preemption may be information indicating multiple candidates for the carrier sense time, for example, when terminal 200 randomly selects one. Alternatively, the information regarding the carrier sense time may be information indicating the carrier sense time (for example, a set value) that terminal 200 performs immediately before preemption transmission.

[0091] The AP 100 notifies the terminal 200 of all or part of the preemption control information using at least one of a preamble, a MAC header, and a trigger frame.

[0092] Note that whether or not preemption is permitted does not need to be explicitly notified to terminal 200. For example, terminal 200 may determine that preemption is permitted when the time length of the PPDU transmission gap notified from AP 100 is equal to or greater than a predetermined value. For example, control may be such that preemption within a TXOP is permitted when the time length of the PPDU transmission gap is greater than SIFS. Note that if preemption is not permitted (if not permitted), AP 100 does not need to notify terminal 200 of other preemption control information.

[0093] An example of notification of preemption control information will be described below.

[0094] <Notification Example 1: Notification by Preamble> In notification example 1, at least a part of the preemption control information is notified by a preamble.

[0095] For example, a part of the preemption control information may be included in a control signal of a preamble that constitutes a DL PPDU transmitted by the AP 100 .

[0096] For example, the Disregard subfield (e.g., 5 bits in the case of 11be) included in the U-SIG field of the preamble may be used to notify the PPDU transmission gap length and carrier sense time candidates, as shown in Fig. 7. In Fig. 7, 2 bits are used for the PPDU transmission gap length (PPDU Gap length subfield), and 3 bits are used for the carrier sense time candidates (CCA candidate subfield).

[0097] 7, one of four time lengths (PPDU Gap length subfield = 0 to 3) is specified as the PPDU transmission gap length. For example, when the PPDU Gap length subfield = 2, the AP 100 can notify the terminal 200 that the PPDU transmission gap length is SIFS + 27 us.

[0098] 7, for example, when the PPDU transmission gap length is SIFS (PPDU Gap length subfield = 0), this may mean that preemption in the PPDU transmission gap is not permitted. In this case, explicit notification of whether preemption is permitted or not may be omitted.

[0099] 7, AP 100 may notify terminal 200 of any time candidate from three patterns as a carrier sense time candidate (CCA candidate subfield) in bitmap format. For example, when each bit (Bit 0, Bit 1, or Bit 2) is 0, the corresponding carrier sense time is not set as a candidate in terminal 200, and when each bit (Bit 0, Bit 1, or Bit 2) is 1, the corresponding carrier sense time may be set as a candidate in terminal 200. For example, when CCA candidate subfield = 6, [Bit 2 Bit 1 Bit 0] is [1 1 0], and the carrier sense time candidates set in terminal 200 do not include SIFS + 9 us, but include SIFS + 18 us and SIFS + 27 us. In this case, terminal 200 may select either SIFS + 18 us or SIFS + 27 us to perform carrier sensing.

[0100] Furthermore, the AP 100 may notify the terminal 200 of individual preemption control information for each PPDU transmitted within a TXOP. For example, as shown in Fig. 8 , in the preamble constituting the DL PPDU transmitted first by the AP 100, preemption in the next PPDU transmission gap is permitted, and the PPDU transmission gap is set to SIFS+27 us.

[0101] On the other hand, as shown in Fig. 8, in the preamble constituting the next PPDU to be transmitted by AP 100 (BA in the example of Fig. 8), preemption in the next PPDU transmission gap is not permitted, and the PPDU transmission gap length is set to SIFS. For example, when LL traffic addressed to STA1 occurs at AP 100, AP 100 may not permit preemption. This allows AP 100 to transmit the LL traffic to STA1 with priority over transmission from terminal 200.

[0102] <Notification Example 2-1: Notification by RTS> In notification example 2-1, at least a part of the preemption control information is notified by RTS.

[0103] For example, at least a portion of the preemption control information may be included in the RTS that the AP 100 transmits first after acquiring the TXOP.

[0104] For example, part or all of the Reserved subfield (e.g., 20 bits in the case of 11be) included in the User Info field of the MU-RTS Trigger frame may be used to notify the PPDU transmission gap length, carrier sense time candidates, and traffic types for which preemption is permitted. As an example, in Fig. 9, 2 bits are used for the PPDU transmission gap length (PPDU Gap length subfield), 3 bits are used for the carrier sense time candidates (CCA candidate subfield), and 8 bits are used for the traffic types for which preemption is permitted (Preemption TID). Note that the notification of the PPDU transmission gap length (PPDU Gap length subfield) and carrier sense time candidates (CCA candidate subfield) shown in Fig. 9 is the same as the example of Fig. 7.

[0105] In the example shown in FIG. 9, the AP 100 may instruct the terminal 200 in bitmap format to select an arbitrary TID from eight types of TID as a TID for which preemption is permitted (Preemption TID subfield).

[0106] For example, as shown in Fig. 10, AP 100 transmits the first RTS signal to be transmitted after acquiring a TXOP in an MU-RTS Trigger frame, and notifies terminal 200 of preemption control information in the TXOP. For example, when terminal 200 is notified of preemption permission, terminal 200 (e.g., STA2 shown in Fig. 10) becomes capable of preemption in the PPDU transmission gap in the TXOP. Note that, similar to the example of Fig. 3, the PPDU transmission gap before the first DL PPDU may be SIFS (i.e., preemption is possible in the gap before the second or subsequent DL PPDU).

[0107] <Notification Example 2-2: Notification by RTS> In notification example 2-2, similarly to notification example 2-1, at least a part of the preemption control information is notified by RTS.

[0108] In Notification Example 2-2, for example, a Reserved subfield (e.g., 10 bits in the case of 11be) included in the User Info field of the MU-RTS TXS (TXOP Sharing) Trigger frame may be used to notify the PPDU transmission gap length and carrier sense time candidates, as shown in FIG. 7.

[0109] In Notification Example 2-2, for example, a new TXOP Sharing mode (e.g., mode 3 in addition to modes 1 and 2 defined in IEEE 802.11be) may be defined. In the new TXOP Sharing mode, for example, sharing of a portion of the TXOP acquired by AP 100 may be limited to communication between AP 100 and a terminal specified by the Trigger frame (STA1 in the example of FIG. 11) and communication between AP 100 and a terminal 200 having LL traffic (STA2 in the example of FIG. 11). For example, in FIG. 11, even if STA2 is not a terminal specified by the Trigger frame, it can share a portion of the TXOP if it has LL traffic.

[0110] For example, as shown in Fig. 11 , AP 100 transmits the first RTS signal to be transmitted after acquiring a TXOP in an MU-RTS TXS Trigger frame, and notifies terminal 200 of preemption control information in the TXOP. For example, when terminal 200 is notified of preemption permission, terminal 200 (e.g., STA2 shown in Fig. 11 ) becomes capable of preemption in the PPDU transmission gap in the TXOP (this may also be referred to as TXOP sharing, for example). Note that, as in the example of Fig. 3 , the PPDU transmission gap before the first DL PPDU may be SIFS (i.e., preemption is possible in the gap before the second or subsequent DL PPDU).

[0111] Note that a new trigger type for UHR may be defined for the trigger frame that transmits the MU-RTS frame including the preemption control information in notification example 2-1 and notification example 2-2. For example, a new trigger type may be specified, and the size of the user information field format and the type of information included in the trigger frame may be newly defined.

[0112] <Combination of Notification Example 1 and Notification Example 2 (Notification Example 2-1 or Notification Example 2-2)> Notification Example 1 and Notification Example 2-1 (or similarly Notification Example 2-2) may be combined.

[0113] For example, some of the preemption control information may be notified by a preamble, and the other information may be notified by an RTS.

[0114] As an example, similar to Notification Example 2-1, at least a portion of the Reserved subfield (e.g., 20 bits in the case of 11be) included in the User Info field of the MU-RTS Trigger frame may be used to notify carrier sense time candidates (CCA candidate subfield) and a traffic type for which preemption is permitted (Preemption TID subfield), as shown in Fig. 12. Also, similar to Notification Example 1, for example, at least a portion of the Disregard subfield (e.g., 5 bits in the case of 11be) included in the U-SIG field of the preamble may be used to notify a PPDU transmission gap length (PPDU Gap length subfield), as shown in Fig. 13.

[0115] For example, as shown in Fig. 14, the AP 100 transmits the first RTS signal to be transmitted after acquiring a TXOP in an MU-RTS Trigger frame, and notifies, as preemption control information commonly applied within the TXOP, candidates for carrier sense times to be performed immediately before preemption transmission and the traffic type for which preemption is permitted. Also, as shown in Fig. 14, the AP 100 notifies, for each PPDU, the PPDU transmission gap length of the next PPDU to be transmitted and whether preemption is permitted, in the preamble constituting the DL PPDU or BA from the AP 100. Note that, as in the example of Fig. 3, the PPDU transmission gap before the first DL PPDU may be SIFS (i.e., preemption is permitted in the gaps before the second and subsequent DL PPDUs).

[0116] This allows AP100 to distinguish and notify preemption control information that is commonly applicable within a TXOP (e.g., carrier sense time candidates, traffic types for which preemption is permitted, etc.) and preemption control information that dynamically changes depending on the LL traffic generation status (e.g., whether preemption is permitted, etc.).

[0117] The same effect can be obtained by using the MU-RTS TXS Trigger frame of Notification Example 2-2 instead of the MU-RTS Trigger frame.

[0118] <Notification Example 3: Notification to Each STA> In notification example 3, at least a part of the preemption control information is notified by the User Info field of the RTS.

[0119] For example, at least a portion of the preemption control information may be included in the User Info field of the RTS signal that the AP 100 transmits first after acquiring the TXOP.

[0120] For example, AP 100 may notify terminals 200 (e.g., preemption transmission candidate terminals) of part of preemption control information in the User Info field of the MU-RTS Trigger frame or the MU-RTS TXS Trigger frame. Also, for example, the preemption candidate flag and carrier sense time for each terminal 200 may be notified individually in the User Info field.

[0121] Fig. 15 shows an example of the User Info field of the MU-RTS TXS Trigger frame according to Notification Example 3. In Fig. 15, the AID12 subfield indicates an AID (Association ID) that identifies the terminal 200 that notifies the control information of the User Info field.

[0122] In FIG. 15 , the Preemption Candidate subfield (e.g., 1 bit) indicates a preemption candidate flag. For example, when the Preemption candidate flag is 0, a CTS signal response is instructed as in existing operations, and when the Preemption candidate flag is 1, it indicates that the terminal specified by the AID12 subfield of the User Info field is a preemption candidate terminal (e.g., a terminal that is permitted preemption if a predetermined condition is satisfied). The predetermined condition may be, for example, a condition that there is traffic that permits preemption (LL traffic) and that the result of carrier sensing for a predetermined time immediately before preemption transmission is an idle state. For example, when terminal 200, which is a preemption candidate terminal, receives an MU-RTS TXS Trigger frame including the User Info field shown in FIG. 15 , it does not need to transmit a CTS response.

[0123] 15, the CCA Duration subfield indicates the duration of carrier sensing performed by terminal 200 specified by the AID12 subfield immediately before preemption transmission. For example, as shown in FIG. 16, the CCA Duration subfield uses three bits, and one of five time lengths (CCA Duration subfield = 0 to 4) is specified as the carrier sensing duration.

[0124] For example, AP 100 determines one carrier sense time for each terminal 200 from the carrier sense time candidates defined as shown in Figure 16 so that the time length differs among multiple terminals 200 indicated by the Trigger frame, and indicates this to terminal 200 using the CCA Duration subfield.

[0125] When the MU-RTS TXS Trigger frame is used, the terminal indicated by the first User Info field means existing TXOP sharing, and the second and subsequent User Info fields may be used for control information for preemption candidate terminals. In this case, the second and subsequent User Info fields may not include notification of a candidate flag (Preemption Candidate subfield).

[0126] In this way, it is possible to set the carrier sense time performed immediately before preemption transmission to be different for each terminal 200, so that collisions can be prevented even when there are multiple terminals 200 having LL traffic.

[0127] An example of a method for notifying preemption control information has been described above.

[0128] Thus, in this embodiment, terminal 200 determines the carrier sense time in a PPDU transmission gap (e.g., a predetermined time interval) based on a predetermined rule (e.g., the relationship with the carrier sense time of AP 100, or the relationship between multiple terminals 200), and transmits a signal of LL traffic (e.g., a predetermined type) with preemption based on the carrier sense result.

[0129] For example, since the carrier sense time for performing preemption differs among multiple terminals 200, even if there are multiple terminals 200 with LL traffic, collision of uplink signals between the multiple terminals 200 can be prevented, thereby preventing AP 100 from being unable to receive all uplink signals and increasing delays.

[0130] Therefore, according to this embodiment, it is possible to improve the efficiency of transmission control in wireless communication.

[0131] (Variation of First Embodiment) The PPDU transmission gap in which preemption is permitted is not limited to the interval (gap) between DL PPDUs as shown in Fig. 3 and Fig. 4. For example, when an immediate response ACK (e.g., BA) is requested immediately after a DL PPDU, as shown in Fig. 17, the interval (non-transmission interval) between the BA (ACK) from terminal 200 or AP 100 and the DL PPDU may be defined as the PPDU transmission gap.

[0132] For example, in FIG. 17 , the PPDU transmission gap may be set to the time interval (SIFS + 27 μs in FIG. 17 ) from when the AP 100 receives a BA signal from STA1 in response to a DL PPDU transmitted from the AP 100 (AP in FIG. 17 ) (e.g., from the end timing of the BA) until the AP 100 transmits the next DL PPDU. Based on the preemption control information notified by the AP 100, if the carrier sense result for a predetermined carrier sense time in the above-mentioned PPDU transmission gap is an idle state, the terminal 200 (STA2 and STA3 in FIG. 17 ) transmits LL traffic to the AP 100 with preemption. As shown in FIG. 17 , if the carrier sense times of STA2 and STA3 are different, collision of their preemption signals can be prevented. Note that, as in the example of FIG. 3 , the PPDU transmission gap before the first DL PPDU may be set to SIFS (i.e., preemption is possible in the gaps before the second and subsequent DL PPDUs).

[0133] The presence or absence of BA and ACK immediately responding to DL PPDU may be notified by, for example, Ack Policy included in QoS Control of MAC header. For example, this can be controlled by indicating No ack (no BA, no ACK) and Implicit BA (with BA, ACK) in the Ack Policy indicator.

[0134] (Embodiment 2) In this embodiment, the AP permits communication (which may be called, for example, preemption) limited to a predetermined type of traffic (for example, LL traffic) for a predetermined terminal group (for example, STA Membership) during a period called R-TWT SP (Restricted-Target Wake Time Service Period) specified for a connected terminal. Note that the R-TWT SP may be notified to the terminal from the AP by, for example, a beacon.

[0135] [Configuration of Wireless Communication System] The wireless communication system according to this embodiment may include, for example, an AP 100 and a terminal 200. Two or more terminals 200 may be present in the wireless communication system.

[0136] For example, the AP 100 permits communication limited to LL traffic for a predetermined terminal group in the R-TWT SP designated by the AP 100.

[0137] In R-TWT SP, when communication is limited to LL traffic with a specific terminal group, terminal 200 determines that transmission of LL traffic is permitted if the carrier sense result for a specific period of time is in the idle state, regardless of the backoff counter, and transmits the permitted LL traffic.

[0138] For example, the terminal 200 receives a beacon from the AP 100 and acquires the R-TWT control information and preemption control information included in the received beacon. The R-TWT control information may include, for example, information such as the R-TWT SP, Membership ID, and traffic type permitted for communication within the R-TWT-SP. The preemption control information may also include, for example, information such as the carrier sense time of the terminal 200 and candidates for the carrier sense time. For example, different carrier sense times may be set for multiple terminals 200 belonging to the same terminal group (for example, the same Broadcast TWT ID).

[0139] In the R-TWT-SP, when terminal 200 has LL traffic for which communication is permitted and the carrier sense result for a predetermined time is Idle, terminal 200 transmits an uplink signal to AP 100. On the other hand, when terminal 200 does not have a traffic type for which communication is permitted or when the carrier sense result is Busy, terminal 200 determines that transmission is not permitted.

[0140] FIG. 18 shows, as an example, an example of a sequence in which terminals 200 (for example, STA1 and STA2) belong to a terminal group permitted to communicate in the R-TWT SP and have LL traffic permitted to communicate.

[0141] 18, multiple terminals 200 (STA1 and STA2) connected to an AP 100 (e.g., AP) belong to a terminal group (e.g., Broadcast TWT ID#X) that is permitted to communicate in the R-TWT SP, and have LL traffic that is permitted to communicate. Therefore, each terminal 200 transmits LL traffic (LL packet) regardless of the backoff counter if the carrier sense time determined by each terminal 200 is idle.

[0142] 18, the carrier sense time of STA1 is SIFS + 9 us and the carrier sense time of STS2 is SIFS + 18 us, so transmission by STA1 takes priority over transmission by STA2. After transmission by STA1, STA2 performs carrier sense from the BA signal from the AP and then transmits LL traffic.

[0143] As shown in FIG. 17, if the carrier sense times of STA2 and STA3 are different, collision of preemption signals in a terminal group permitted to communicate in the R-TWT SP can be prevented.

[0144] [Configuration example of AP 100] The configuration of AP 100 according to this embodiment may be the same as that of AP 100 according to embodiment 1 (for example, FIG. 5). AP 100 according to this embodiment differs from embodiment 1 in the operations of scheduling section 101 and data generation section 102.

[0145] The scheduling unit 101 schedules R-TWT SPs limited to LL traffic communication for a predetermined terminal group including, for example, the terminal 200. For example, the scheduling unit 101 determines scheduling information for the R-TWT SPs based on the transmission buffer state of the LL traffic, etc., fed back from the terminal 200, and outputs the scheduling information to the data generation unit 102.

[0146] Furthermore, scheduling section 101 determines preemption control information to be used for transmission that does not take into account the backoff counter of R-TWT SP (for example, referred to as preemption transmission), and outputs the determined information to data generating section 102. The preemption control information may include, for example, information such as the carrier sense time of terminal 200 and candidates for the carrier sense time.

[0147] Data generation section 102 generates a signal (e.g., a TWT element) to be notified to terminal 200 based on, for example, scheduling information related to R-TWT SP and preemption control information determined in scheduling section 101. Data generation section 102 then generates, for example, a beacon signal including the TWT element and outputs the beacon signal to error correction coding section 103.

[0148] The AP 100 transmits a beacon signal to the terminal 200. The AP 100 also receives and decodes a signal including LL traffic transmitted from the terminal 200 in the R-TWT SP.

[0149] [Configuration Example of Terminal 200] The configuration of terminal 200 according to this embodiment may be the same as that of terminal 200 according to Embodiment 1 (for example, FIG. 6). Terminal 200 according to this embodiment differs from that according to Embodiment 1 in the operation of preemption control unit 206.

[0150] The preemption control unit 206 acquires the scheduling information and preemption control information related to the R-TWT SP input from either or both of the preamble receiving unit 203 and the error correction decoding unit 205 .

[0151] When the terminal 200 has LL traffic permitted for communication in the R-TWT SP, the preemption control unit 206 instructs the data generation unit 207 to generate data.

[0152] Furthermore, the preemption control unit 206 determines the carrier sense time in the R-TWT SP. For example, the preemption control unit 206 may randomly select one time from multiple carrier sense time candidates included in the preemption control information and set the selected time as the carrier sense time in the R-TWT SP. Alternatively, the preemption control unit 206 may set the carrier sense time explicitly notified to each terminal 200 by the AP 100 as the carrier sense time in the R-TWT SP.

[0153] In this way, the terminal 200 receives a beacon signal from the AP 100, and transmits LL traffic to the AP 100 if the carrier sense for the R-TWT SP is in the idle state for a predetermined time immediately before transmission, based on the scheduling information and preemption control information of the R-TWT SP included in the beacon signal.

[0154] [Method of Notifying Preemption Control Information] Next, an example of a method of notifying preemption control information from the AP 100 to the terminal 200 will be described.

[0155] The carrier sense time that each terminal 200 performs before transmitting LL traffic of the R-TWT SP may be notified to the terminal 200 from the AP 100 by a TWT response signal that configures the terminal 200 to join the R-TWT-SP Membership (also called TWT membership).

[0156] For example, the AP 100 can prevent collision of LL traffic from multiple terminals 200 in the R-TWT SP by varying the carrier sense time among multiple terminals 200 that have the same Broadcast TWT ID (Membership ID of the R-TWT SP) set.

[0157] Variations in the notification of preemption control information will be described below.

[0158] <Variation 2-1> In variation 2-1, the terminal 200 may include information regarding whether or not there is LL traffic (or whether or not there is a possibility of having LL traffic) in a frame (e.g., a TWT request) requesting addition to TWT membership. For example, as shown in FIG. 19 , the terminal 200 may notify the AP 100 by including one bit of information regarding whether or not there is LL traffic in the Request Type field (reserved field in FIG. 19 ) of the Broadcast TWT Parameter Set field of the TWT element. For example, a 1-bit value of 0 corresponds to no LL traffic or a possibility of no LL traffic, and a 1-bit value of 1 indicates that there is LL traffic or that there is LL traffic (or a possibility of having LL traffic).

[0159] Based on information regarding whether or not there is LL traffic from terminal 200, AP 100 may classify and associate terminals 200 that have LL traffic (or terminals 200 that may have LL traffic) with different Broadcast TWT IDs (different terminal groups).

[0160] This makes it more likely that terminals with LL traffic (or terminals that may have LL traffic) have different TWT memberships, thereby reducing collisions between terminals with LL traffic in the same R-TWT SP.

[0161] <Variation 2-2> In variation 2-2, the AP 100 may instruct the terminal 200 about preemption control information for each terminal 200 using a frame (for example, a TWT response) that instructs the terminal 200 to be added to the TWT Membership.

[0162] FIG. 20 shows an example of TWT operation.

[0163] As shown in FIG. 20, the AP 100 transmits a TWT response including preemption control information to the terminal 200 (STA1 in FIG. 20) that transmitted the TWT request, for example.

[0164] Furthermore, the AP 100 may transmit a signal including preemption control information (e.g., an unsolicited TWT response (a TWT response transmitted by the AP when there is no TWT request from the terminal)) to a terminal 200 (e.g., STA2 in FIG. 20 ) that the AP 100 has determined to be a candidate terminal for which preemption occurs in the R-TWT SP, based on, for example, the preemption-related capability (processing ability) of the terminal 200 connected to the AP 100 or a notification of the presence or absence of LL traffic.

[0165] Furthermore, the AP 100 may explicitly specify the carrier sense time in the R-TWT-SP for each terminal 200. For example, the TWT Parameter Set field of the TWT element may include the preemption control information, and an individual carrier sense time may be set for each terminal 200. By the AP 100 setting a different carrier sense time for each terminal 200, it is possible to prevent collision of LL traffic in the R-TWT SP.

[0166] 20, as described above, the TWT request frame transmitted by STA1 includes information indicating whether or not there is LL traffic (or whether or not there is a possibility of LL traffic). In response to the TWT request frame (information indicating whether or not there is LL traffic), the AP 100 notifies STA1 of the carrier sense time to be used in R-TWT SP in the TWT response frame.

[0167] As described above, the beacon signal transmitted by the AP 100 includes scheduling information regarding the R-TWT SP (terminal groups permitted to communicate in the R-TWT SP, permitted traffic types).

[0168] An example of notification of preemption control information has been described above.

[0169] As described above, in this embodiment, terminal 200 determines the carrier sense time in an R-TWT SP (e.g., a predetermined time interval) based on a predetermined rule (e.g., the relationship with the carrier sense time of AP 100 or the relationship between multiple terminals 200), and transmits a signal of LL traffic (e.g., a predetermined type) with preemption based on the carrier sense result.

[0170] For example, since the carrier sense time for performing preemption differs among multiple terminals 200, even if there are multiple terminals 200 with LL traffic, collision of uplink signals between the multiple terminals 200 can be prevented, thereby preventing AP 100 from being unable to receive all uplink signals and increasing delays.

[0171] Therefore, according to this embodiment, it is possible to improve the efficiency of transmission control in wireless communication.

[0172] Third Embodiment Configuration of Wireless Communication System A wireless communication system according to this embodiment may include an AP 300 , an AP 400 , and a terminal 500 .

[0173] The terminal 500 is a terminal connected to the AP 400 .

[0174] The AP 300 transmits a downlink signal limited to predetermined traffic (for example, LL traffic) to the terminal 500 .

[0175] AP 400 is an AP having a relay function for relaying a signal received from AP 300 to terminal 500. Note that AP 400 may also be a terminal having a relay function (for example, a non-AP terminal, a non-AP STA).

[0176] For example, this embodiment may be applied to multi-AP transmission in which cooperative transmission is performed by multiple APs (for example, AP 300 and AP 400).

[0177] AP 400, which has a relay function, receives a downlink signal from AP 300. If the carrier sense result for a predetermined time (e.g., SIFS+9 us) that is longer than the carrier sense time of the ACK response from terminal 500 is in the idle state, AP 400 transmits (relays) the received signal to terminal 500. If the carrier sense result is busy, AP 400 stops transmitting (relaying) the signal to terminal 500.

[0178] If the terminal 500 correctly decodes the downlink signal from the AP 300, it transmits (responds to) an ACK to the AP 300 after performing carrier sensing for a predetermined period (for example, a carrier sense time for the ACK response (for example, SIFS)). On the other hand, if the terminal 500 does not correctly decode the downlink signal from the AP 300, it receives a relayed signal from the AP 400. Then, if the terminal 500 correctly decodes the relayed signal, it responds with an ACK to the AP 300.

[0179] The terminal 500 does not send an ACK response if it does not correctly decode the relayed signal from the AP 400. Therefore, the AP 300 may determine that transmission to the terminal 500 is NG and retransmit the downlink signal.

[0180] As described above, in this embodiment, the AP 400 and the terminal 500 perform carrier sensing (e.g., carrier sensing time) determined according to a predetermined rule, and transmit a signal if the carrier sensing result is idle, and do not transmit a signal if the result is busy. For example, according to the above-mentioned predetermined rule, the carrier sensing time of the terminal 500 (e.g., a terminal to which a downlink signal is relayed) is set to be shorter than the carrier sensing time of the AP 400 (e.g., a terminal from which a downlink signal is relayed).

[0181] Figure 21 (a) shows an example of a sequence when terminal 500 (non-AP STA) does not decode the downlink signal from AP300 (AP1) (reception NG), and Figure 21 (b) shows an example of a sequence when terminal 500 correctly decodes the downlink signal from AP300 (reception OK).

[0182] In the examples of FIGS. 21A and 21B, the carrier sense time of AP 400 is set to SIFS+9 us, and the carrier sense time of terminal 500 is set to an SIFS shorter than SIFS+9 us.

[0183] As shown in Figure 21(a), if a non-AP STA cannot decode a downlink signal from AP1 (reception NG), an ACK is not transmitted from the non-AP STA, and therefore, at least in AP2, the carrier sense result does not become "busy" due to the signal transmission from the non-AP STA, and AP2 relays the downlink signal from AP1 to the non-AP STA. On the other hand, as shown in Figure 21(b), if a non-AP STA correctly decodes a downlink signal from AP1 (reception OK), an ACK is transmitted from the non-AP STA, and therefore, in AP2, the carrier sense result becomes "busy" due to the transmission from the non-AP STA, and AP2 does not relay the downlink signal from AP1 to the non-AP STA.

[0184] In this way, when the terminal 500 does not decode the downlink signal from the AP 300 (when reception is not possible), the downlink signal is relayed from the AP 400, and when the terminal 500 decodes the downlink signal from the AP 300 (when reception is OK), the downlink signal is not relayed from the AP 400. As a result, the transmission process of the relayed signal does not always occur, and therefore the delay in communication of the downlink signal including LL traffic from the AP 300 to the terminal 500 can be reduced.

[0185] [Configuration example of AP 300] The configuration of AP 300 according to this embodiment may be the same as that of AP 100 (for example, FIG. 5) according to embodiment 1. AP 300 according to this embodiment differs from embodiment 1 in the operation of scheduling section 101.

[0186] The scheduling unit 101 schedules predetermined traffic (for example, LL traffic) for the AP 400 and the terminal 500, for example.

[0187] In addition, the scheduling unit 101 determines preemption control information including a carrier sense time for transmitting a response signal (e.g., including a BA or relay signal) to the downlink signal to each of the AP 400 and the terminal 500, and outputs the information to the data generation unit 102.

[0188] Here, the carrier sense time for the response signal (e.g., a relayed signal) of AP 400 is set to a time longer than the carrier sense time for the response signal (e.g., a BA) of terminal 500. For example, since an ACK is expected to be the response signal of terminal 500, the carrier sense time may be set to SIFS. Furthermore, since a relayed signal to terminal 500 is expected to be the response signal of AP 400, the carrier sense time may be set to SIFS + 9 us, which is longer than SIFS.

[0189] If the carrier sense time for ACK transmission is specified in the specifications (for example, if the ACK response is specified as SIFS), AP 300 does not need to include the carrier sense time for terminal 500 in the preemption control information.

[0190] In this way, AP 300 transmits a downlink signal including LL traffic to AP 400 and terminal 500. AP 300 also receives and decodes an ACK transmitted when terminal 500 correctly decodes the downlink signal.

[0191] [Configuration Example of AP 400] The configuration of AP 400 having a relay function according to this embodiment may be the same as the configuration of terminal 200 (for example, FIG. 6) according to embodiment 1. AP 400 according to this embodiment differs from embodiment 1 in the operation of preemption control unit 206.

[0192] The preemption control unit 206 of the AP 400 acquires preemption control information input from either or both of the preamble receiving unit 203 and the error correction decoding unit 205 , and a signal from the AP 300 input from the error correction decoding unit 205 .

[0193] Furthermore, the preemption control unit 206 of the AP 400 determines, for example, the carrier sense time until transmitting a relay signal to the terminal 500. For example, the preemption control unit 206 may randomly select one time from multiple carrier sense time candidates included in the preemption control information and set the selected time as the carrier sense time until transmitting the relay signal. Alternatively, the preemption control unit 206 may set the carrier sense time explicitly notified by the AP 300 as the carrier sense time until transmitting the relay signal.

[0194] In this way, AP 400 receives a downlink signal from AP 300, and based on the preemption control information contained in the downlink signal, if the carrier sense performed for a predetermined time immediately before transmitting the relay signal is in an idle state, AP 400 transmits (relays) the downlink signal from AP 300 to terminal 500.

[0195] [Configuration example of terminal 500] The configuration of terminal 500 according to this embodiment may be the same as that of terminal 200 (for example, FIG. 6) according to embodiment 1. Terminal 500 according to this embodiment differs from that according to embodiment 1 in the operation of preemption control unit 206.

[0196] Preemption control unit 206 of terminal 500 acquires preemption control information input from either or both of preamble receiving unit 203 and error correction decoding unit 205, and a signal from AP 300 or AP 400 input from error correction decoding unit 205. Note that if the output result from error correction decoding unit 205 indicates that the received signal cannot be correctly decoded (for example, if NG is detected in FCS (Frame Check Sequence)), transmission of ACK is stopped.

[0197] Furthermore, the preemption control unit 206 of the terminal 500 determines, for example, the carrier sense time until transmitting an ACK in response to the AP 300. For example, the preemption control unit 206 may randomly select one time from multiple carrier sense time candidates included in the preemption control information and set the selected time as the carrier sense time until transmitting the ACK. Alternatively, the preemption control unit 206 may set the carrier sense time explicitly notified by the AP 300 as the carrier sense time until transmitting the ACK. Alternatively, the preemption control unit 206 may apply the carrier sense time for the ACK defined in the specifications.

[0198] In this way, terminal 500 receives a downlink signal from AP 300 or AP 400, and based on the preemption control information contained in the downlink signal, if the carrier sense performed for a predetermined time immediately before transmitting an ACK is in an idle state, terminal 500 transmits an ACK signal to AP 300.

[0199] Thus, in this embodiment, AP 400 and terminal 500 determine the carrier sense time based on a predetermined rule (e.g., the relationship between the carrier sense times between AP 400 and terminal 500), and transmit a signal of LL traffic (e.g., a predetermined type) or a response signal based on the carrier sense result.

[0200] For example, by setting the carrier sense time for transmitting a response signal (e.g., ACK or BA) by terminal 500 to be shorter than the carrier sense time for transmitting a response signal (e.g., relay signal) by AP 400, signal collision between AP 400 (or relay source terminal or transmitting terminal) and terminal 500 (or relay destination terminal or receiving terminal) can be prevented, making it possible to transmit a response signal (e.g., relay signal or ACK).

[0201] Therefore, according to this embodiment, it is possible to improve the efficiency of transmission control in wireless communication.

[0202] (Fourth Embodiment) In this embodiment, for example, random access communication limited to predetermined traffic (for example, LL traffic) is permitted in the PPDU transmission gap in the TXOP acquired by the AP.

[0203] For example, in this embodiment, when random access limited to LL traffic is performed in a PPDU transmission gap, the terminal is allowed to transmit permitted traffic (e.g., LL traffic) if carrier sense is in the idle state for a predetermined time period, regardless of a backoff counter for random access (e.g., an OFDMA random access backoff counter (OBO)) (e.g., OBO counter = 0).

[0204] In this way, by allowing preemption of random access signals limited to LL traffic in the gap between PPDUs, it is possible to reduce collisions of uplink signals between terminals having LL traffic.

[0205] [Configuration of Wireless Communication System] The wireless communication system according to this embodiment may include, for example, an AP 100 and a terminal 200. Two or more terminals 200 may be present in the wireless communication system.

[0206] For example, the AP 100 permits preemption of an uplink random access signal limited to a predetermined traffic type (for example, LL traffic) in a PPDU transmission gap in a TXOP acquired by the AP 100.

[0207] The terminal 200 receives, for example, a downlink PPDU from the AP 100, and controls the preemption of an uplink random access signal based on the preemption control information included in the received PPDU.

[0208] The preemption control information may be indicated by, for example, any one or a combination of a preamble, a MAC header, and a trigger frame. The preemption control information may also include information such as a random access resource (for example, a random access - resource unit (RA-RU)), whether or not an ACK is sent immediately after a PPDU, a PPDU transmission gap time, a traffic type for which preemption is permitted, a carrier sense time of a terminal, or a candidate for a carrier sense time.

[0209] Furthermore, the carrier sense time immediately before transmitting an uplink signal may be set to a fixed value for multiple terminals 200. For example, the carrier sense time set for terminal 200 may be shorter than the carrier sense time set for AP 100. Furthermore, for example, if the carrier sense time immediately before transmitting an uplink signal is SIFS and AP 100 does not instruct terminal 200 to perform carrier sense, carrier sense may not be performed.

[0210] For example, if terminal 200 has a traffic type that allows preemption and the carrier sense result for a specified period of time is idle, terminal 200 selects one RA-RU from the RA-RUs instructed by AP 100 during the PPDU transmission gap period, and preempts the uplink signal to AP 100 using the selected RA-RU.

[0211] On the other hand, for example, if the terminal 200 does not have a traffic type for which preemption is permitted, or if the carrier sense result is Busy when the terminal 200 is requested to perform carrier sense by the AP 100, the terminal 200 determines that preemption is not permitted.

[0212] FIG. 22 shows an example of a sequence in which the terminal 200 performs preemption by random access when it has LL traffic that is permitted to communicate.

[0213] In Fig. 22, AP 100 (AP in Fig. 22) transmits a Trigger frame as a DL PPDU to prompt a terminal to perform random access. Also, as shown in Fig. 2, a value (SIFS + 9 us in Fig. 22) greater than the carrier sense time (SIFS in Fig. 22) immediately before transmitting a random access signal is set for the PPDU transmission gap (for example, the time interval from when AP 100 transmits a DL PPDU in a TXOP until when it transmits the next DL PPDU). Note that, as in the example of Fig. 3, the PPDU transmission gap before the first DL PPDU may be SIFS (i.e., preemption is possible in the gaps before the second and subsequent DL PPDUs).

[0214] A terminal 200 having LL traffic (STA2, STA3 in FIG. 22) selects one from multiple RA-RUs, sets the carrier sense time to be performed immediately before random access transmission to SIFS, and performs carrier sense. If the carrier sense result is in the idle state, the terminal 200 having LL traffic uses the selected RA-RU to transmit an uplink signal including LL traffic to AP 100.

[0215] For example, in the example of FIG. 22 , the AP 100 (AP) uses the AID12 subfield in the User Info field of the Trigger frame to set 0, indicating random access by multiple terminals (Associated STAs) already connected to the AP, and indicates one or more RA-RUs (RU1 to RU4 in FIG. 22 ). Terminals 200 (STA2 and STA3 in FIG. 22 ) with LL traffic randomly select one RA-RU from the RA-RUs RU1 to RU4, regardless of the OBO counter. In FIG. 22 , STA2 selects RU3, and STA3 selects RU1 to transmit LL traffic. In this way, STA2 and STA3 use different RUs to transmit uplink signals (e.g., frequency multiplexed transmission), increasing the likelihood that their uplink signals will be transmitted without collision (orthogonalized).

[0216] [Configuration example of AP 100] The configuration of AP 100 according to this embodiment may be the same as that of AP 100 according to embodiment 1 (for example, FIG. 5). AP 100 according to this embodiment differs from embodiment 1 in the operations of scheduling section 101 and data generation section 102.

[0217] The scheduling unit 101 schedules multiple PPDU transmissions and random access limited to LL traffic communication for multiple terminals including the terminal 200 (e.g., terminals already connected to the AP 100). The random access scheduling information may include, for example, the resource size, number of resources, and resource location of the RA-RU. The random access scheduling information may be, for example, part of preemption control information. The scheduling unit 101 determines, for example, the scheduling information for multiple PPDU transmissions and random access, and outputs the determined scheduling information to the data generation unit 102.

[0218] The data generation unit 102 generates signals (e.g., a trigger frame and a data signal) to be notified to the terminal 200 based on, for example, preemption control information determined in the scheduling unit 101, which includes scheduling information regarding multiple PPDU transmissions and scheduling information for random access, and outputs the signals to the error correction coding unit 103.

[0219] In this way, the AP 100 transmits a DL PPDU including a Trigger frame to the terminal 200. The AP 100 also receives and decodes an uplink signal transmitted from the terminal 200 by random access including LL traffic.

[0220] [Configuration example of terminal 200] The configuration of terminal 200 according to the present embodiment may be the same as the configuration of terminal 200 according to embodiment 1 (for example, FIG. 6). Terminal 200 according to the present embodiment differs from embodiment 1 in the operations of preemption control section 206, scheduling section 208, and modulation section 210.

[0221] The preemption control unit 206 acquires preemption control information including scheduling information related to random access, which is input from either or both of the preamble receiving unit 203 and the error correction decoding unit 205 .

[0222] Furthermore, the preemption control unit 206 determines the carrier sense time immediately before random access. For example, the carrier sense time before random access transmission may be common to all terminals 200, and may be set to a predetermined time length (for example, 1 sine first frame).

[0223] When the terminal 200 has LL traffic that is permitted for communication, the preemption control unit 206 instructs the data generation unit 207 to generate data.

[0224] The scheduling unit 208 randomly determines (selects) one RA-RU based on the random access information from the preemption control unit 206 and outputs it to the modulation unit 210.

[0225] The modulation unit 210 maps the modulated signal to the RA-RU instructed by the scheduling unit 208 , forms an OFDM signal, and outputs the formed OFDM signal to the PPDU generation unit 212 .

[0226] In this way, terminal 200 receives a DL PPDU including a Trigger frame from AP 100, randomly selects one of the RA-RUs limited to the LL traffic indicated in the Trigger frame, and if the carrier sense is in the Idle state for a predetermined period of time immediately before transmission, transmits a random access signal including the LL traffic to AP 100.

[0227] As described above, in the present embodiment, terminal 200 determines the carrier sense time in a PPDU transmission gap (e.g., a predetermined time interval) based on a predetermined rule (e.g., the same setting among multiple terminals 200), and transmits a random access signal including LL traffic (e.g., a predetermined type) with preemption based on the carrier sense result. At this time, terminal 200 determines (e.g., randomly selects) one resource from multiple frequency resource candidates (e.g., multiple RUs), and transmits the random access signal using the determined resource without relying on a random access transmission counter (e.g., an OBO counter).

[0228] By transmitting random access signals using different frequency resources, terminal 200 can prevent collision of uplink signals between multiple terminals 200 even when there are multiple terminals 200 with LL traffic, thereby preventing AP 100 from being unable to receive all uplink signals and increasing delays.

[0229] Therefore, according to this embodiment, it is possible to improve the efficiency of transmission control in wireless communication.

[0230] (Variation of the Fourth Embodiment) Instead of transmitting a trigger frame that prompts random access, the AP 100 may transmit an NDP Feedback Report Poll (NFRP) trigger frame that prompts the terminal 200 to transmit a resource request (uplink resource allocation request signal).

[0231] The NFRP Trigger frame can transmit orthogonal Null Data Packets (NDPs) in units of Tones to a maximum of 18 terminals per 20 MHz, for example.

[0232] For example, a resource request limited to an uplink allocation request for LL traffic may be used to allow preemption in a gap (PPDU transmission gap) between DL PPDUs transmitted by the AP 100. The AP 100 can reduce collisions of uplink signals between the terminals 200 having LL traffic by allocating orthogonal uplink resources to the terminals 200 that have received the resource request.

[0233] For example, as shown in Fig. 23, AP 100 (AP in Fig. 23) transmits an NFRP Trigger frame that prompts a terminal to transmit a Resource request limited to an uplink allocation request for LL traffic as a DL PPDU. The PPDU transmission gap is set to a value (SIFS + 9 us in Fig. 23) that is greater than the carrier sense time (SIFS in Fig. 23) of the response signal (Resource request signal) to the Trigger frame. Note that, similar to the example in Fig. 3, the PPDU transmission gap before the first DL PPDU may be SIFS (i.e., preemption is possible in the gaps before the second and subsequent DL PPDUs).

[0234] A terminal 200 (STA2, STA3 in FIG. 23) having LL traffic selects a specific Tone number (Tone X for STA2 and Tone Y for STA3 in FIG. 23) determined from the terminal ID (e.g., AID) as a transmission resource, sets the carrier sense time to SIFS, and if the carrier sense result is in the Idle state, transmits an uplink signal (NDP) indicating a resource request for LL traffic to AP 100 using the selected Tone number.

[0235] When AP 100 (AP in FIG. 23) receives a Resource request for LL traffic from terminal 200 (STA2 and STA3 in FIG. 23), it transmits a Trigger frame that causes a different RU (e.g., RU1 or RU2) in STA2 and STA3 to transmit an uplink signal.

[0236] Terminal 200 (STA2 and STA3 in FIG. 23) transmits uplink signals including LL traffic using RUs based on a trigger frame from AP 100. This allows STA2 and STA3 to transmit uplink signals using different RUs.

[0237] In this way, by permitting preemption of resource request signals limited to LL traffic in the PPDU transmission gap, it is possible to prevent collision of uplink signals between terminals having LL traffic.

[0238] The embodiments of the present disclosure have been described above.

[0239] In each of the above embodiments, the carrier sense time performed by terminal 200 before transmitting preemption is not limited to SIFS + 9 us × N (N is a positive integer). For example, an existing defined predetermined time length (xIFS) such as SIFS, PIFS, or DIFS may be used as the carrier sense time performed by terminal 200 before transmitting preemption. Furthermore, instead of 9 us, a constant defined in the specifications such as slot time or aSlotTime may be used as the carrier sense time performed by terminal 200 before transmitting preemption.

[0240] Furthermore, in each of the above embodiments, the shorter the allowable delay time (delay budget) of a transmission packet, the shorter the time length of carrier sense performed by terminal 200 before preemption transmission may be set. For example, if the delay budget is X us or less, the time length of carrier sense may be set to SIFS, and if the delay budget is Y us (X < Y) or less, the time length of carrier sense may be set to SIFS + 9 us.

[0241] Furthermore, the smaller the backoff counter, the shorter the time length for carrier sensing performed by terminal 200 before preemption transmission may be set.

[0242] Furthermore, in each of the above embodiments, notification of preemption control information is not limited to notification by the preamble and trigger frame, and may be notification by, for example, the MAC header (for example, defining a new A-Control field).

[0243] In each of the above embodiments, the presence or absence of Ack / BA immediately after the PPDU may be notified by the Ack Policy included in the QoS Control of the MAC header. For example, the Ack Policy indicator may indicate that there is no Ack / BA by "No ack" and that there is Ack / BA by "Implicit BA."

[0244] Furthermore, in each of the above embodiments, the starting point of the carrier sense time performed before transmitting preemption may be defined as follows: (1) When there is an Ack / BA request immediately after the PPDU (for example, in the following cases), the starting point is the end timing of the PPDU including the Ack / BA (similar to FIG. 17): QoS Data addressed to an individual address with an Ack Policy of Immediate Ack Action frame with an Ack Policy other than Action No Ack (2) When there is no Ack / BA request immediately after the PPDU (for example, in the following cases), the starting point is the end timing of the PPDU including the Ack Policy (similar to FIG. 4): QoS Data with an Ack Policy of No Ack Ack Ack frame

[0245] Furthermore, in each of the above embodiments, if the conditions for allowing preemption transmission are met, terminal 200 may transmit an uplink signal regardless of the state of NAV (Network Allocation Vector, transmission prohibition period) (ignoring NAV).

[0246] Furthermore, in each of the above-described embodiments, LL traffic has been described as an example of a predetermined type for which preemption is permitted, but the type for which preemption is permitted is not limited to LL traffic, and may be other types of traffic.

[0247] In addition, in each of the above-described embodiments, the field (or subfield) used for notifying control information (including, for example, preemption control information) is an example, and other fields or subfields may be used. Furthermore, the number of bits used for notifying control information in each field or subfield is an example, and other numbers of bits may be used.

[0248] Furthermore, the signal formats described in each of the above-mentioned embodiments are merely examples, and other configurations may be used in which at least one of other fields is added and some fields is deleted, and other configurations may be used in which at least one of other subfields is added and some subfields are deleted in each of the above-mentioned fields.

[0249] Furthermore, in the above embodiment, as an example, a case based on the format defined in IEEE 802.11 has been described, but the format to which an embodiment of the present disclosure is applied is not limited to the IEEE 802.11 format.

[0250] The present disclosure can be realized by software, hardware, or software in conjunction with hardware. Each functional block used in the description of the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit, and each process described in the above embodiments may be partially or entirely controlled by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may also be called an IC, system LSI, super LSI, or ultra LSI.

[0251] The integrated circuit method is not limited to LSI, and may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

[0252] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology may be used to integrate functional blocks. The application of biotechnology, etc. is also a possibility.

[0253] The present disclosure may be implemented in any type of apparatus, device, or system (collectively referred to as a communications apparatus) that has a communications function. The communications apparatus may include a radio transceiver and processing / control circuitry. The radio transceiver may include a receiver and a transmitter, or both functions. The radio transceiver (transmitter and receiver) may include a radio frequency (RF) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, communication-enabled vehicles or mobile transportation (e.g., cars, airplanes, ships), and combinations of the above devices.

[0254] The communication devices are not limited to portable or mobile devices, but also include any kind of non-portable or fixed equipment, devices, and systems, such as smart home devices (such as home appliances, lighting equipment, smart meters or measuring devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0255] Communications include data communications via cellular systems, wireless LAN systems, communication satellite systems, and the like, as well as data communications via combinations of these.

[0256] A communications apparatus also includes devices such as controllers and sensors connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0257] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0258] A terminal according to one embodiment of the present disclosure includes a control circuit that determines a carrier sense time for performing carrier sense in a predetermined time interval based on a predetermined rule, and a transmission circuit that transmits a predetermined type of signal based on the result of the carrier sense.

[0259] In one embodiment of the present disclosure, the predetermined type is a type that requires low latency.

[0260] In one embodiment of the present disclosure, the predetermined type is event-based latency traffic.

[0261] In one embodiment of the present disclosure, the control circuit determines the carrier sense time based on a time length set by an access point.

[0262] In one embodiment of the present disclosure, the control circuit determines one of a plurality of candidates for the carrier sense time.

[0263] In one embodiment of the present disclosure, the carrier sense time differs among a plurality of terminals permitted to transmit the signal under the predetermined rule.

[0264] In one embodiment of the present disclosure, the predetermined rule is that the carrier sense time is shorter than the length of time until the access point transmits the next signal.

[0265] In one embodiment of the present disclosure, the predetermined rule is such that the carrier sense time of a terminal to which the signal is to be relayed is shorter than the carrier sense time of a terminal from which the signal is to be relayed.

[0266] In one embodiment of the present disclosure, the predetermined time interval is a time interval from when the access point transmits a first signal to when the access point transmits a second signal within a transmission opportunity of the access point.

[0267] In one embodiment of the present disclosure, the predetermined time interval is a time interval during a transmission opportunity of an access point from when the access point receives a response signal to a first signal to when the access point transmits a second signal.

[0268] In one embodiment of the present disclosure, the predetermined time period is a Restricted-Target Wake Time Service Period (R-TWT SP).

[0269] In one embodiment of the present disclosure, when the result of the carrier sense is an idle state, the control circuit determines that transmission of the signal is permitted regardless of a back-off counter.

[0270] In one embodiment of the present disclosure, the carrier sense time is set to a fixed value for multiple terminals, the control circuit determines one resource from multiple frequency resource candidates, and the transmitting circuit transmits the signal using the determined resource.

[0271] In one embodiment of the present disclosure, the plurality of candidates are a plurality of resource units for random access, and the control circuit randomly selects one resource unit from the plurality of resource units without relying on a random access transmission counter.

[0272] An access point according to one embodiment of the present disclosure includes a control circuit that determines a carrier sense time for performing carrier sense during a predetermined time interval based on a predetermined rule, and a receiving circuit that receives the predetermined type of signal transmitted in accordance with the result of the carrier sense.

[0273] In a communication method according to one embodiment of the present disclosure, a terminal determines a carrier sense time for performing carrier sense in a predetermined time interval based on a predetermined rule, and transmits a predetermined type of signal based on the result of the carrier sense.

[0274] In a communication method according to one embodiment of the present disclosure, an access point determines a carrier sense time for performing carrier sense during a predetermined time interval based on a predetermined rule, and receives the predetermined type of signal transmitted in accordance with the result of the carrier sense.

[0275] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2023-102501, filed on June 22, 2023, are incorporated herein by reference in their entirety.

[0276] One embodiment of the present disclosure is useful in wireless communication systems.

[0277] 100, 300, 400 AP 101, 208 Scheduling unit 102, 207 Data generation unit 103, 209 Error correction coding unit 104, 210 Modulation unit 105, 211 Preamble generation unit 106, 212 PPDU generation unit 107, 201 Radio transmission / reception unit 108, 202 Separation unit 109, 203 Preamble reception unit 110, 204 Demodulation unit 111, 205 Error correction decoding unit 200, 500 Terminal 206 Preemption control unit

Claims

1. A terminal comprising: a control circuit that determines a carrier sense time for performing carrier sense during a specified time period based on a specified rule; and a transmission circuit that transmits a specified type of signal based on the result of the carrier sense.

2. The terminal according to claim 1, wherein the predetermined type is a type that requires low latency.

3. The terminal according to claim 1, wherein the predetermined type is event-based latency traffic.

4. The terminal according to claim 1, wherein the control circuit determines the carrier sense time based on a time length set by an access point.

5. The terminal according to claim 1, wherein the control circuit determines any one of a plurality of candidates for the carrier sense time.

6. The terminal according to claim 1, wherein the carrier sense time differs among a plurality of terminals permitted to transmit the signal under the predetermined rule.

7. The terminal according to claim 1, wherein in the predetermined rule, the carrier sense time is shorter than a time length until the access point transmits the next signal.

8. The terminal according to claim 1, wherein, in the predetermined rule, the carrier sense time of a terminal to which the signal is to be relayed is shorter than the carrier sense time of a terminal from which the signal is to be relayed.

9. The terminal according to claim 1, wherein the predetermined time interval is a time interval from when the access point transmits a first signal to when the access point transmits a second signal within a transmission opportunity of the access point.

10. The terminal according to claim 1, wherein the predetermined time interval is a time interval from when the access point receives a response signal to a first signal to when the access point transmits a second signal during a transmission opportunity of the access point.

11. The terminal according to claim 1, wherein the predetermined time period is a Restricted - Target Wake Time Service Period (R-TWT SP).

12. The terminal according to claim 1, wherein the control circuit determines that transmission of the signal is permitted, regardless of a back-off counter, when the result of the carrier sense is an idle state.

13. The terminal according to claim 1, wherein the carrier sense time is set to a fixed value for a plurality of terminals, the control circuit determines one of a plurality of frequency resource candidates, and the transmission circuit transmits the signal using the determined resource.

14. The terminal according to claim 13, wherein the plurality of candidates are a plurality of resource units for random access, and the control circuit randomly selects one resource unit from the plurality of resource units without relying on a random access transmission counter.

15. An access point comprising: a control circuit that determines a carrier sense time for performing carrier sense during a specified time period based on a specified rule; and a receiving circuit that receives the specified type of signal transmitted in response to the result of the carrier sense.

16. A communication method, in which a terminal determines a carrier sense time for performing carrier sense in a specified time period based on a specified rule, and transmits a specified type of signal based on the result of the carrier sense.

17. A communication method, comprising: an access point determining a carrier sense time for performing carrier sensing during a specified time period based on a specified rule; and receiving the specified type of signal transmitted in accordance with the result of the carrier sense.