Access point and terminal

Abstract

An access point according to an embodiment of the present invention comprises a plurality of wireless signal processing units, and a management unit. The management unit uses the plurality of wireless signal processing units to establish a plurality of links with a terminal, and transmits a first wireless signal from each of the plurality of wireless signal processing units to the terminal. In response of one of the plurality of wireless signal processing units having received a second wireless signal transmitted from the terminal in correspondence with the transmission of the first wireless signal, the management unit causes the one of the plurality of wireless signal processing units that has received the second wireless signal to carry out wireless communication with the terminal until the completion of a prescribed period.

Description

Access points and terminals

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to an access point and a terminal.

[0002] A wireless LAN (Local Area Network) is known as a communication system that wirelessly connects an access point (hereinafter referred to as "AP") and a terminal. The AP and terminal, which are radio stations of the wireless LAN, perform carrier sense based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance), and transmit data when they acquire the right to transmit.

[0003] IEEE 802.11be, which is being developed as a successor standard to IEEE 802.11ax, will enable a link set consisting of multiple links to be established between a terminal and an AP. When a link set consisting of multiple links is established, a wireless station performs carrier sensing based on CSMA / CA for each link and transmits a data frame using the link that has acquired the transmission right.

[0004] Here, in a terminal provided with only one STA function corresponding to a wireless signal processing unit, even if multiple links are logically established between the terminal and the AP, it is physically impossible to transmit data to the AP in parallel via the multiple links. In a communication system, when transmitting uplink data, such as traffic requiring low latency, from a terminal provided with only one STA function to an AP, it is required that redundancy be appropriately implemented. In other words, it is required to ensure reliability in data exchange between a terminal provided with only one STA function and an AP.

[0005] IEEE P802.11beTM / D1.5, “35.3.17 Enhanced multi-link single radio operation”, 18, March 2022.

[0006] An object of the present invention is to provide an access point and a terminal that ensure reliability in data exchange between the access point and a terminal provided with only one STA function.

[0007] In one embodiment of the present invention, an access point includes a plurality of radio signal processing units and a management unit. The management unit uses the plurality of radio signal processing units to establish a plurality of links with a terminal and causes each of the plurality of radio signal processing units to transmit a first radio signal to the terminal. Based on reception by one of the plurality of radio signal processing units of a second radio signal transmitted from the terminal in response to transmission of the first radio signal, the management unit causes one of the plurality of radio signal processing units that received the second radio signal to communicate wirelessly with the terminal until the end of a specified period.

[0008] According to the present invention, an access point and a terminal are provided that ensure reliability in data exchange between a terminal provided with only one STA function and the access point.

[0009] FIG. 1 is a block diagram showing an example of the configuration of a communication system according to an embodiment. FIG. 2 is a schematic diagram showing an example of link management information between an AP and a terminal in the communication system according to an embodiment. FIG. 3 is a block diagram showing an example of the hardware configuration of an AP according to an embodiment. FIG. 4 is a block diagram showing an example of the hardware configuration of a terminal according to an embodiment. FIG. 5 is a block diagram showing an example of the functional configuration of an AP according to an embodiment. FIG. 6 is a block diagram showing an example of the functional configuration of a terminal according to an embodiment. FIG. 7 is a schematic diagram showing an example of a format of a beacon frame generated by a beacon management unit of a communication management unit of an AP according to an embodiment. FIG. 8 is a block diagram showing an example of the functional configuration of a channel access function provided in a wireless signal processing unit of an AP according to an embodiment. FIG. 9 is a block diagram showing an example of the functional configuration of a channel access function provided in a wireless signal processing unit of a terminal according to an embodiment. FIG. 10 is a flowchart showing an example of processing performed by a management unit of an AP according to an embodiment when the rTWT function is used. FIG. 11 is a flowchart showing an example of processing performed by a management unit of a terminal according to an embodiment when the rTWT function is used. FIG. 12 is a schematic diagram showing a temporal change in the communication state through a link set between an AP and a terminal in the communication system according to an embodiment. Fig. 13 is a flowchart showing an example of processing performed by a management unit of an AP according to a modified example when the rTWT function is used. Fig. 14 is a flowchart showing an example of processing performed by a management unit of a terminal according to a modified example when the rTWT function is used. Fig. 15 is a schematic diagram showing a change over time in the communication state through a link set between an AP and a terminal in a communication system according to a modified example.

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] FIG. 1 is a block diagram showing an example of the configuration of a communication system 1 according to an embodiment. As shown in FIG. 1, the communication system 1 includes an access point (hereinafter referred to as "AP") 10, a terminal 20, and a network 30. The AP 10 is also called a "base station" of a wireless LAN. The AP 10 communicates with a server (not shown) on the network 30 via wired or wireless communication. The terminal 20 is, for example, any one of a smartphone, a mobile phone, a tablet PC (personal computer), a desktop PC, a laptop PC, and an IoT (Internet of Things) sensor / device.

[0012] The AP 10 can be wirelessly connected to the terminal 20 and communicates wirelessly with the terminal 20. The wireless communication between the terminal 20 and the AP 10 complies with the IEEE 802.11 standard. Note that, in the following description, wireless communication that complies with the IEEE 802.11 standard will be described as an example, but a wireless communication standard other than the IEEE 802.11 standard may also be used.

[0013] Each of the AP 10 and the terminal 20 has a wireless communication function based on the OSI (Open Systems Interconnection) reference model defined in the IEEE 802.11 standard. In the OSI reference model, wireless communication functions are divided into seven layers (Layer 1: Physical Layer, Layer 2: Data Link Layer, Layer 3: Network Layer, Layer 4: Transport Layer, Layer 5: Session Layer, Layer 6: Presentation Layer, and Layer 7: Application Layer). The second layer, the Data Link Layer, includes a Logical Link Control (LLC) sublayer and a Media Access Control (MAC) sublayer.

[0014] In the wireless connection between the AP 10 and the terminal 20, a link set LS consisting of a plurality of links is established. Each of the plurality of links in the link set LS is established using an STA function provided as a functional configuration in each of the AP 10 and the terminal 20. The AP 10 is provided with a plurality of STA functions, while the terminal 20 is provided with only one STA function. In each of the AP 10 and the terminal 20, the STA function corresponds to a wireless signal processing unit, which will be described later.

[0015] To establish one link, one of the STA functions of the AP 10 and the STA function of the terminal 20 are used. Therefore, to establish each of the multiple links of the link set LS, a corresponding one of the multiple STA functions of the AP 10 and the STA function of the terminal 20 are used. Therefore, the only STA function provided in the terminal 20 is used to establish all of the links that make up the link set LS.

[0016] As described above, in the link set LS established between the AP 10 and the terminal 20, data can be transmitted from the AP 10 to the terminal 20 in parallel via multiple links. However, in the link set LS, data cannot be transmitted from the terminal 20 to the AP 10 in parallel via multiple links. In other words, at the same time, upstream data, etc. can be transmitted from the terminal 20 to the AP 10 only through one of the multiple links in the link set LS. The terminal 20 can receive downstream data through multiple links in the link set LS. Note that the terminal 20 can receive management frames (described later) in parallel via the multiple links in the link set LS, but data may be received only through one of the multiple links.

[0017] Here, the STA function provided as a single wireless signal processing unit in the terminal 20 is also referred to as an "ESTA (Enhanced STA) function." A terminal provided with only one ESTA function as an STA function, such as the terminal 20, is also referred to as an "SR (Single Radio) terminal." The function of establishing a link set LS between the AP 10 and the terminal 20, which is an SR terminal, as described above, and performing wireless communication between the AP 10 and the terminal 20 using the link set LS as described above is also referred to as an "EMLSR (Enhanced Multi Link Single Radio) function." The AP 10 and the terminal 20 manage the status of the link between the AP 10 and the terminal 20, including the status of the link set LS, using link management information.

[0018] FIG. 2 is a schematic diagram showing an example of link management information between the AP 10 and the terminal 20 in the communication system 1 according to the embodiment. The link management information indicates, for example, information about a "link ID," a "link," a "frequency band," a "channel ID," a "link set," and "traffic." The "link ID" is an identifier associated with the STA function described above in the AP 10. In the example shown in FIG. 2, three STA functions (STA1, STA2, and STA3) are assigned to the AP 10 for wireless communication with the terminal 20. The information about the "link" indicates whether each of the multiple STA functions in the AP 10 has established a link with the terminal 20. In the example shown in FIG. 2, a state in which each of STA1 to STA3 in the AP 10 has established a link with the terminal 20 is shown.

[0019] The information about "frequency band" indicates a frequency band assigned to each link. For example, the 6 GHz band, the 5 GHz band, and the 2.4 GHz band may be applied as frequency bands. Each of the multiple frequency bands includes multiple channels. "Channel ID" indicates the ID of the channel assigned to each link. In the example of FIG. 2 , the link corresponding to STA1, the link corresponding to STA2, and the link corresponding to STA3 are assigned a 5 GHz band channel CH1, a 5 GHz band channel CH2, and a 5 GHz band channel CH3, respectively. Note that the multiple links in the link set LS may be assigned different frequency bands or different channels in the same frequency band.

[0020] The information about the "link set" indicates whether a link set LS consisting of multiple links has been established between the AP 10 and the terminal 20. Furthermore, if a link set LS has been established, the information about the "link set" indicates which links make up the link set LS. In the example of Figure 2, the link set LS is made up of three links: a link corresponding to STA1, a link corresponding to STA2, and a link corresponding to STA3.

[0021] The information about "traffic" indicates a TID (Traffic Indicator) assigned to each link (each STA function of AP10). The TID is an identifier indicating each type of traffic, and each type of traffic may be associated with an access category. Access categories of traffic include, for example, "VO (Voice)," "VI (Video)," "BE (Best Effort)," "BK (Background)," and "LL (Low Latency)." Access category LL is traffic that requires low latency. In the example of FIG. 2, TID#1 corresponds to any of VO, VI, BE, BK, and LL. TID#1 is assigned to each of the links corresponding to STA1, STA2, and STA3.

[0022] Here, with the link set LS established, data can be transmitted from the AP 10 to the terminal 20 in parallel via multiple links in the link set LS. For example, with respect to downlink data from the AP 10 to the terminal 20, although this is not limited to this, only one link in the link set LS may be assigned to one TID, or multiple links in the link set LS may be assigned. Furthermore, the association between traffic and links (STA function of the AP 10) is set, for example, so that the traffic volume (data volume) is equalized among the multiple links constituting the link set LS. Note that the association between traffic and links is not limited to the example described above. For example, similar types of traffic, such as traffic requiring low latency and traffic not requiring low latency, may be collected on a specific link in the link set LS.

[0023] Furthermore, the AP 10 and the terminal 20 have an rTWT (restricted Target Wake Time) function. By the AP 10 and the terminal 20 utilizing the rTWT function, an opportunity to transmit traffic (uplink data) requiring low latency from the terminal 20 to the AP 10 is secured in the link set LS established between the AP 10 and the terminal 20. The rTWT function sets a service period as a specified period during which transmission and reception of traffic requiring low latency can be prioritized over transmission and reception of traffic not requiring low latency. The service period set as a specified period by the rTWT function is also referred to as an "rTWT-SP (Service Period)."

[0024] 3 is a block diagram showing an example of a hardware configuration of the AP 10 according to the embodiment. As shown in FIG. 3, the AP 10 includes, for example, a central processing unit (CPU) 11, a read-only memory (ROM) 12, a random access memory (RAM) 13, a wireless communication module 14, and a wired communication module 15.

[0025] The CPU 11 is a processing circuit that controls the overall operation of the AP 10. The ROM 12 is, for example, a non-volatile semiconductor memory. The ROM 12 stores programs and data for controlling the AP 10. The RAM 13 is, for example, a volatile semiconductor memory. The RAM 13 is used as a work area for the CPU 11. The wireless communication module 14 is a circuit used to send and receive data via wireless signals. The wireless communication module 14 is connected to an antenna. The wired communication module 15 is a circuit used to send and receive data via wired signals. The wired communication module 15 is connected to the network 30.

[0026] 4 is a block diagram showing an example of a hardware configuration of the terminal 20 according to the embodiment. As shown in FIG. 4, the terminal 20 includes, for example, a CPU 21, a ROM 22, a RAM 23, a wireless communication module 24, a display 25, and a storage 26.

[0027] The CPU 21 is a processing circuit that controls the overall operation of the terminal 20. The ROM 22 is, for example, a non-volatile semiconductor memory. The ROM 22 stores programs and data for controlling the terminal 20. The RAM 23 is, for example, a volatile semiconductor memory. The RAM 23 is used as a work area for the CPU 21. The wireless communication module 24 is a circuit used for transmitting and receiving data via wireless signals. The wireless communication module 24 is connected to an antenna. The display 25 is, for example, an LCD (Liquid Crystal Display) or an EL (Electro-Luminescence) display. The display 25 displays a GUI (Graphical User Interface) corresponding to application software, etc. The storage 26 is a non-volatile storage device. The storage 26 stores system software, etc. of the terminal 20.

[0028] FIG. 5 is a block diagram showing an example of the functional configuration of an AP 10 according to an embodiment. As shown in FIG. 5, the AP 10 includes, for example, an LLC processing unit 100, a management unit 110, and wireless signal processing units 150, 160, and 170. The processing of the LLC processing unit 100 may be realized by, for example, a combination of a CPU 11, a RAM 13, and a wired communication module 15. The processing of each of the management unit 110 and the wireless signal processing units 150, 160, and 170 may be realized by, for example, a combination of a CPU 11, a RAM 13, and a wireless communication module 14. The LLC processing unit 100 performs, for example, processing of the LLC sublayer of layer 2 and processing of layers 3 to 7. The management unit 110 performs processing of the MAC sublayer of layer 2. The wireless signal processing units 150, 160, and 170 perform processing of the MAC sublayer of layer 2 and processing of layer 1. The management unit 110 includes a data processing unit 120 , a communication management unit 130 , and a MAC frame processing unit 140 .

[0029] The LLC processing unit 100 generates LLC packets by adding a DSAP (Destination Service Access Point) header, an SSAP (Source Service Access Point) header, and the like to data received from the network 30. The LLC processing unit 100 then inputs the generated LLC packets to the data processing unit 120. The LLC processing unit 100 also receives LLC packets from the data processing unit 120 and extracts data from the received LLC packets. The LLC processing unit 100 then transmits the extracted data to the network 30.

[0030] The data processing unit 120 generates a MAC frame by adding a MAC header to the LLC packet input from the LLC processing unit 100. The data processing unit 120 then inputs the generated MAC frame to the MAC frame processing unit 140. The data processing unit 120 also receives a MAC frame from the MAC frame processing unit 140 and extracts an LLC packet from the received MAC frame. The data processing unit 120 then inputs the extracted LLC packet to the LLC processing unit 100. In the following description, a MAC frame containing data is also referred to as a "data frame."

[0031] The communication management unit 130 manages the communication status between the AP 10 and the terminal 20, including the status of the link between the AP 10 and the terminal 20. MAC frames containing management information related to wireless communication, such as management information related to links and rTWT, are input and output between the communication management unit 130 and the MAC frame processing unit 140. In the following description, MAC frames containing management information are also referred to as "management frames." By outputting management frames to the MAC frame processing unit 140, the communication management unit 130 can instruct the MAC frame processing unit 140 to execute a predetermined process. The communication management unit 130 includes, for example, link management information 131, a link control unit 132, a beacon management unit 133, and a trigger generation unit 134. The communication management unit 130 also includes a clock or the like and can generate time information.

[0032] When a MAC frame is input from the data processing unit 120 or the communication management unit 130, the MAC frame processing unit 140 associates the input MAC frame with a link. Then, for a MAC frame to be transmitted to the terminal 20, the MAC frame processing unit 140 identifies a link associated with the MAC frame from the links in the link set LS. For example, when a data frame is input as a MAC frame from the data processing unit 120, the MAC frame processing unit 140 identifies a link associated with the TID included in the data frame. Then, the MAC frame processing unit 140 inputs the MAC frame to a radio signal processing unit (corresponding one or more of 150, 160, 170) corresponding to the identified link.

[0033] Furthermore, when a MAC frame is input from any of radio signal processing units 150, 160, and 170, MAC frame processing unit 140 inputs the MAC frame to data processing unit 120 or communication management unit 130 depending on the type of the input MAC frame. If the MAC frame is a data frame, the MAC frame is input to data processing unit 120, and if the MAC frame is a management frame, the MAC frame is input to communication management unit 130.

[0034] The radio signal processing units 150, 160, and 170 correspond to STA1, STA2, and STA3 shown in FIG. 2 , which are STA functions of the AP 10. The radio signal processing units 150, 160, and 170 have similar functional configurations. Each of the radio signal processing units 150, 160, and 170 generates a radio frame by adding a preamble and a PHY (physical layer) header to data input from the MAC frame processing unit 140. Then, each of the radio signal processing units 150, 160, and 170 performs a predetermined modulation operation on the generated radio frame to convert the radio frame into a radio signal, and radiates (transmits) the radio signal via an antenna. The predetermined modulation operation includes, for example, convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform (IFFT), orthogonal frequency division multiplexing (OFDM) modulation, and frequency conversion.

[0035] Each of the radio signal processing units 150, 160, and 170 converts radio signals received from the terminal 20 via an antenna into radio frames by performing a predetermined demodulation operation. The predetermined demodulation operation includes, for example, frequency conversion, OFDM demodulation, fast Fourier transform (FFT), subcarrier demodulation, deinterleaving, and Viterbi decoding. The radio signal processing unit 150 then extracts MAC frames from the radio frames and inputs the extracted MAC frames to the MAC frame processing unit 140. The radio signal processing units 150, 160, and 170 may share the same antenna or may use different antennas.

[0036] FIG. 6 is a block diagram showing an example of the functional configuration of the terminal 20 according to the embodiment. As shown in FIG. 6 , the terminal 20 includes, for example, an application execution unit 280, an LLC processing unit 200, a management unit 210, and a radio signal processing unit 250. The respective processes of the application execution unit 280 and the LLC processing unit 200 may be realized by, for example, a CPU 21 and a RAM 23. The respective processes of the management unit 210 and the radio signal processing unit 250 may be realized by, for example, a combination of the CPU 21, the RAM 23, and a radio communication module 24. The application execution unit 280 performs processing of layer 7, and the LLC processing unit 200 performs processing of the LLC sublayer of layer 2 and processing of layers 3 to 6. The management unit 210 performs processing of the MAC sublayer of layer 2, and the radio signal processing unit 250 performs processing of the MAC sublayer of layer 2 and processing of layer 1. The management unit 210 includes a data processing unit 220, a communication management unit 230, and a MAC frame processing unit 240.

[0037] The application execution unit 280 executes an application based on data input from the LLC processing unit 200. The application execution unit 280 also inputs data to the LLC processing unit 200 in accordance with the operation of the application. The application execution unit 280 can display application information on the display 25. The application execution unit 280 can also execute processing corresponding to operations on the input interface.

[0038] The LLC processing unit 200 generates LLC packets by adding a DSAP header, an SSAP header, and the like to the data received from the application execution unit 280. The LLC processing unit 200 then inputs the generated LLC packets to the data processing unit 220. The LLC processing unit 200 also receives LLC packets from the data processing unit 220 and extracts data from the received LLC packets. The LLC processing unit 200 then inputs the extracted data to the application execution unit 280.

[0039] The data processing unit 220 generates a MAC frame by adding a MAC header to the LLC packet input from the LLC processing unit 200. The data processing unit 220 then inputs the generated MAC frame to the MAC frame processing unit 240. The data processing unit 220 also receives a MAC frame from the MAC frame processing unit 240 and extracts an LLC packet from the received MAC frame. The data processing unit 220 then inputs the extracted LLC packet to the LLC processing unit 200.

[0040] The communication management unit 230 cooperates with the communication management unit 130 of the AP 10 to manage the communication status between the AP 10 and the terminal 20, including the status of the link between the AP 10 and the terminal 20. MAC frames (management frames) including management information related to wireless communication, such as management information related to links and rTWTs, are input and output between the communication management unit 230 and the MAC frame processing unit 240. The communication management unit 230 can instruct the MAC frame processing unit 240 to execute a predetermined process by outputting a management frame to the MAC frame processing unit 240. The communication management unit 230 includes, for example, link management information 231, a link control unit 232, and a beacon management unit 233.

[0041] When a MAC frame is input from the data processing unit 220 or the communication management unit 230, the MAC frame processing unit 240 associates the input MAC frame with a link. Then, for a MAC frame to be transmitted to the AP 10, the MAC frame processing unit 240 identifies a link associated with the MAC frame from the links in the link set LS. For example, when a data frame is input from the data processing unit 220, the MAC frame processing unit 240 identifies a link associated with the TID included in the data frame. Then, the MAC frame processing unit 240 inputs the MAC frame to the wireless signal processing unit 250 together with an instruction to the wireless signal processing unit 250 to transmit the MAC frame via the identified link.

[0042] Furthermore, when a MAC frame is input from radio signal processing unit 250, MAC frame processing unit 240 inputs the MAC frame to data processing unit 220 or communication management unit 230 depending on the type of the input MAC frame. If the MAC frame is a data frame, the MAC frame is input to data processing unit 220, and if the MAC frame is a management frame, the MAC frame is input to communication management unit 230.

[0043] The wireless signal processing unit 250 supports ESTA, which is a STA function provided only once in the terminal 20. Therefore, the wireless signal processing unit 250 establishes multiple links constituting a link set LS between the terminal 20 and the AP 10. The wireless signal processing unit 250 generates a wireless frame by adding a preamble, a PHY (physical layer) header, etc. to the data input from the MAC frame processing unit 240. The wireless signal processing unit 250 then performs a predetermined modulation operation on the wireless frame to convert the wireless frame into a wireless signal, and radiates (transmits) the wireless signal via an antenna. The predetermined modulation operation is performed in the same manner as the predetermined modulation operations performed by the wireless signal processing units 150, 160, and 170, respectively.

[0044] The radio signal processing unit 250 transmits a radio signal using a corresponding one of the multiple links (multiple channels) of the link set LS. As described above, the radio signal processing unit 250 cannot transmit radio signals in parallel to multiple links constituting the link set LS.

[0045] Furthermore, the wireless signal processing unit 250 converts wireless signals received from the AP 10 via the antenna into wireless frames by performing a predetermined demodulation operation. The predetermined demodulation operation is performed in the same manner as the predetermined demodulation operations performed by each of the wireless signal processing units 150, 160, and 170. The wireless signal processing unit 250 then extracts MAC frames from the wireless frames and inputs the extracted MAC frames to the MAC frame processing unit 240. In one example, the wireless signal processing unit 250 monitors each of the links (channels) of the link set LS, and when it detects a wireless signal on one of the links, it inputs a MAC frame corresponding to the detected wireless signal to the MAC frame processing unit 240.

[0046] Furthermore, when the wireless signal processing unit 250 detects a wireless signal from the AP 10 on one of the links, it identifies the link (channel) on which the wireless signal was detected. Then, in addition to the MAC frame corresponding to the wireless signal, information indicating which link received the wireless signal is input to the MAC frame processing unit 240. Furthermore, the wireless signal processing unit 250 can receive wireless signals from multiple links constituting the link set LS in parallel, i.e., at the same timing as each other. Note that the wireless signal processing unit 250 may share an antenna among multiple links (multiple channels) of the link set LS, or may provide one antenna for each of the multiple links.

[0047] 5 and 6 , the link control unit 132 of the AP 10 and the link control unit 232 of the terminal 20 cooperate with each other to control the establishment of a link between the AP 10 and the terminal 20. In controlling the establishment of the link, the link control units 132, 232 execute an association process and an authentication process subsequent to the association process in response to a connection request from the terminal 20 to the AP 10, for example. The link control units 132, 232 control the state of the link established between the AP 10 and the terminal 20. For example, the link control units 132, 232 may determine the association between a TID and a link (STA function of the AP 10) when a link set LS is established between the AP 10 and the terminal 20.

[0048] Furthermore, in controlling the establishment of a link and the control of an established link, the link control unit 132 refers to the link management information 131, and the link control unit 232 refers to the link management information 231. Each of the link management information 131 and 231 includes information related to the link between the AP 10 and the terminal 20, and includes, for example, the information shown in FIG.

[0049] Furthermore, in a state where a link set LS has not been established, the link control units 132 and 232 cooperate with each other to set up the link set LS. In setting up the link set LS, any one of the radio signal processing units 150, 160, and 170 (STA1 to STA3) of the AP 10 communicates with the radio signal processing unit 250 (ESTA) of the terminal 20. In one example, in setting up the link set LS, the link control unit 232 causes the terminal 20 to transmit a probe request to the AP 10, and the link control unit 132 causes the AP 10 to transmit a probe response to the probe request to the terminal 20. Then, when the terminal 20 receives the probe response, the link control unit 232 causes the terminal 20 to transmit an association request for the link set LS to the AP 10.

[0050] When the AP 10 receives the association request, the link control unit 132 performs association processing for the link set LS. At this time, based on the completion of the association processing for two or more STA functions of the AP 10, the link control unit 132 recognizes that a link set LS has been established between the AP 10 and the terminal 20. When the association processing is completed, the link control unit 132 updates the link management information 131. Then, the link control unit 132 causes the AP 10 to transmit a response indicating that the link set LS has been established to the terminal 20. Then, based on the terminal 20 receiving the response indicating the establishment of the link set LS, the link control unit 232 updates the link management information 231.

[0051] Furthermore, in a state where a link set LS has been established between the AP 10 and the terminal 20 as described above, the communication management unit 130 of the AP 10 and the communication management unit 230 of the terminal 20 cooperate with each other to set up the rTWT function. The rTWT function may be set up immediately after the link set LS is set up, or may be set up based on a transmission request from the terminal 20 for traffic requiring low latency. By setting up the rTWT function, parameters related to the rTWT function are set, and the rTWT-SP, which is the aforementioned specified period, is set based on the set parameters. Data exchange between the AP 10 and the terminal 20 in the rTWT-SP is performed using any one of the multiple links constituting the set up link set LS.

[0052] When setting up the rTWT function, parameters related to the rTWT function, such as the rTWT start time, rTWT period, and rTWT duration, are set. The rTWT start time corresponds to the time at which the rTWT-SP starts. The rTWT period corresponds to the period of the rTWT-SP and is also called the "rTWT interval." The rTWT duration corresponds to the length of the rTWT-SP. The rTWT start time can be calculated based on the set rTWT period. For example, the next rTWT start time is the time obtained by adding the set rTWT period to the previous rTWT start time.

[0053] The communication management units 130 and 230 set parameters related to the rTWT function, for example, in correspondence with the transmission period from the terminal 20 of traffic requiring low latency. There are no particular limitations on the method of acquiring the transmission period from the terminal 20 of traffic requiring low latency. In one example, the terminal 20 acquires a data generation period set in an application that generates data requiring low latency, and sets parameters related to the rTWT function.

[0054] The beacon management unit 133 manages information transmitted by the AP 10 as a beacon signal. For example, when the rTWT function is being used, the beacon management unit 133 generates a management frame including management information related to the rTWT function and inputs the generated management frame to the MAC frame processing unit 140. The management information related to the rTWT function includes setting values ​​for parameters related to the rTWT function that have been set as described above. In the following description, the management frame generated by the beacon management unit 133 is also referred to as a "beacon frame."

[0055] FIG. 7 is a schematic diagram showing an example of the format of a beacon frame generated by the beacon management unit 133 of the communication management unit 130 of the AP 10 according to the embodiment. In the example of FIG. 7, the beacon frame includes setting values ​​for the rTWT start time and the rTWT duration as management information related to the rTWT function. Also, in the example of FIG. 7, the beacon frame includes a Quiet frame that causes terminals other than the terminal 20 to refrain from transmitting data to the AP 10. The Quiet frame indicates a transmission suppression period that causes terminals other than the terminal 20 to refrain from transmitting data. The transmission suppression period for terminals other than the terminal 20 is set to a state that matches the rTWT-SP of the terminal 20. The communication management unit 130 converts the beacon frame into a wireless signal, and transmits the beacon signal from the AP 10 to the terminal 20 and the terminals other than the terminal 20.

[0056] 5 and 6 , the beacon management unit 233 of the terminal 20 manages information included in a beacon signal received from the AP 10. For example, when the rTWT function is being used, the beacon frame described above is input to the beacon management unit 233 from the MAC frame processing unit 240. The beacon management unit 233 then extracts management information related to the rTWT function from the input beacon frame. As a result, the beacon management unit 233 acquires setting values ​​for parameters related to the rTWT function and manages management information related to the rTWT function, including the setting values ​​for the parameters related to the rTWT function.

[0057] The trigger generation unit 134 generates a MAC frame including trigger information and inputs it to the MAC frame processing unit 140. The trigger information instructs the terminal 20 to transmit uplink data that requires low latency when using the rTWT function. The trigger information also notifies the terminal 20 that the rTWT-SP has started. The trigger information indicates resources to be allocated to the transmission of uplink data from the terminal 20 in the rTWT-SP. For example, the trigger information indicates, as allocated resources, the link (frequency band and channel), timing, period, etc., to be allocated to the transmission of uplink data from the terminal 20 in the rTWT-SP. In the following description, a management frame including trigger information is also referred to as a "trigger frame."

[0058] Note that instead of generating a trigger frame, the trigger generation unit 134 may instruct the MAC frame processing unit 140 to generate a trigger frame along with specifying the time. Also, when the rTWT function is used, a trigger signal obtained by converting the trigger frame into a wireless signal is transmitted from the AP 10 to the terminal 20. Then, the trigger generation unit 134 generates a trigger frame or instructs the generation of a trigger frame at the start of the rTWT-SP, that is, in a state in which a trigger signal is transmitted from the AP 10 at the rTWT start time. Also, resource allocation for transmitting uplink data from the terminal 20 may be performed by the management unit 110, such as the communication management unit 130 and the MAC frame processing unit 140, or may be performed by the wireless signal processing unit (corresponding one or more of 150, 160, and 170) that transmits the trigger signal.

[0059] FIG. 8 is a block diagram showing an example of the functional configuration of the channel access function of the AP 10 according to the embodiment. In the example of FIG. 8, a channel access function is provided in each of the radio signal processing units 150, 160, and 170 (STA1 to STA3). Each of the three channel access functions checks the status of a corresponding link in the link set LS. Here, FIG. 8 shows the channel access function provided in the radio signal processing unit 150, and the following description will mainly focus on the channel access function of the radio signal processing unit 150. However, the channel access functions provided in each of the radio signal processing units 160 and 170 also perform processing similar to the channel access function of the radio signal processing unit 150. In another example, instead of providing a channel access function in each of the radio signal processing units 150, 160, and 170, the channel access function may be provided in the MAC frame processing unit 140. In this case, the status of all links (all channels) in the link set LS is checked by a single channel access function of the MAC frame processing unit 140. As shown in FIG. 8, the channel access function is configured by, for example, a classification unit 151, queues 152A, 152B, 152C, and 152D, carrier sense execution units 153A, 153B, 153C, and 153D, and an internal collision management unit 154.

[0060] In the example of Fig. 8, when a data frame is input as a MAC frame to the channel access function, the classification unit 151 classifies the input data frame into a plurality of access categories based on the TID included in the MAC header. The classification unit 151 then inputs the data frame into one of the queues 152A to 152D that corresponds to the access category. As a result, the data frame is input into the queue (corresponding one of 152A to 152D) that corresponds to the classified access category. In the example of Fig. 8, data frames whose access categories are VO, VI, BE, and BK are input into queues 152A, 152B, 152C, and 152D, respectively.

[0061] Each of the queues 152A to 152D buffers input data frames. In the example of FIG. 8 , the queues 152A, 152B, 152C, and 152D buffer data frames whose access categories are VO, VI, BE, and BK, respectively. The carrier sense execution units 153A, 153B, 153C, and 153D are provided corresponding to the queues 152A, 152B, 152C, and 152D, respectively. Each of the carrier sense execution units 153A to 153D executes carrier sense based on CSMA / CA in accordance with preset access parameters. The carrier sense execution units 153A, 153B, 153C, and 153D execute carrier sense using VO, VI, BE, and BK as the corresponding access categories, respectively.

[0062] Access parameters are set for each access category, and are set, for example, so that the transmission of radio signals is prioritized in the order of VO, VI, BE, and BK. Examples of access parameters used include CWmin, CWmax, AIFS (Arbitration Inter Frame Space), and TXOP (Transmission Opportunity) Limit. CWmin and CWmax respectively indicate the minimum and maximum values ​​of a contention window, which is a parameter used to set a transmission wait time for collision avoidance. AIFS indicates a fixed transmission wait time set for each access category. TXOPLimit indicates the upper limit of the channel occupancy time TXOP. Therefore, the shorter the CWmin, CWmax, and AIFS values ​​set for an access category, the easier it is to acquire a transmission right, and the larger the TXOPLimit value set for an access category, the larger the amount of data transmitted per transmission right.

[0063] Each of the carrier sense execution units 153A to 153D uses carrier sensing to check the status of one of the multiple links (channels) constituting the link set LS that corresponds to the radio signal processing unit 150. At this time, each of the carrier sense execution units 153A to 153D continues carrier sensing as long as the channel corresponding to the link whose status is being checked is busy, that is, until the channel corresponding to the link whose status is being checked becomes idle. Then, when the channel corresponding to the link whose status is being checked becomes idle and the transmission right is acquired for the link whose status is being checked, each of the carrier sense execution units 153A to 153D retrieves a data frame from the corresponding one of the queues 152A to 152D. Then, each of the carrier sense execution units 153A to 153D transmits the radio signal resulting from the conversion of the data frame to the terminal 20 via the link for which the transmission right has been acquired, that is, from the radio signal processing unit 150.

[0064] Internal collision management unit 154 prevents collisions in data transmission when two or more of carrier sense execution units 153A to 153D acquire the right to transmit on the link corresponding to wireless signal processing unit 150. That is, internal collision management unit 154 adjusts the transmission timing for each of the multiple pieces of data for which STA1 has acquired the right to transmit, and outputs the data to STA1 in order of access category with the highest priority.

[0065] 5, when the rTWT function is used, a trigger frame TF or an instruction to generate a trigger frame TF is input from the trigger generation unit 134 to the MAC frame processing unit 140. At this time, the management unit 110, which includes the MAC frame processing unit 140, checks the status of all links in the link set LS by, for example, having the channel access functions of the radio signal processing units 150, 160, and 170 perform carrier sensing. If all links (channels) in the link set LS are busy, the management unit 110 continues checking the status until one or more links become idle. When one or more links (channels) in the link set LS become idle and the transmission right is acquired for one or more links, the management unit 110 causes the radio signal processing unit (corresponding one or more of 150, 160, and 170) corresponding to the link that has acquired the transmission right to transmit a trigger signal obtained by converting the trigger frame TF to the terminal 20.

[0066] 8, in the channel access function of the radio signal processing unit 150, the classification unit 151 inputs the input trigger frame TF or generation instruction to the internal collision management unit 154 without going through any of the queues 152A to 152D. Therefore, for the trigger frame TF, processing such as acquiring the transmission right is performed with lower latency than for other traffic. When the rTWT function is used, the channel access function acquires the transmission right for the trigger frame TF in a state in which a trigger signal is transmitted at the start of the rTWT-SP (rTWT start time) set as a specified period.

[0067] In one example, when the rTWT function is used, when a trigger frame TF is input to the channel access function of the radio signal processing unit 150, the channel access function sets the trigger frame TF as data with the highest transmission priority and performs carrier sensing or the like on the trigger frame TF. In this case, the channel access function acquires the transmission right for the trigger frame TF, for example, using the highest priority access category of EDCA (Enhanced Distributed Channel Access) or by a preferential transmission procedure different from EDCA, and causes the AP 10 to transmit a trigger signal at the start of the rTWT-SP. In another example, by temporarily stopping the carrier sense of the carrier sense execution units 153A to 153D, the transmission of the VO, VI, BE, and BK data frames is temporarily stopped, and the transmission of the trigger frame TF is given priority.

[0068] In the functional configuration shown in FIG. 5 , as described above, carrier sensing is performed by the channel access functions of the radio signal processing units 150, 160, and 170 in response to input of a trigger frame TF or the like to the MAC frame processing unit 140. At this time, if multiple links (channels) constituting the link set LS are in an idle state, the MAC frame processing unit 140 transmits a trigger signal to the terminal 20 through each of the multiple idle links. When transmitting trigger signals from multiple radio signal processing units 150, 160, and 170, the MAC frame processing unit 140 performs redundancy processing of the trigger frame TF, for example, by duplicating the trigger frame TF. This redundancy processing generates multiple trigger frames TF that are common to each other. The MAC frame processing unit 140 outputs one redundantly processed trigger frame TF to each of the multiple idle links in the link set LS. The trigger signal is then transmitted to the terminal 20 as a first radio signal that is redundantly transmitted to the multiple links.

[0069] Furthermore, when redundantly transmitting trigger signals, the MAC frame processing unit 140 notifies each of the radio signal processing units (two or more corresponding ones of 150, 160, and 170) that transmit the trigger signals of time information generated by the communication management unit 130. Then, the radio signal processing units (two or more corresponding ones of 150, 160, and 170) that have been notified of the time information cooperate with each other to transmit trigger signals to the terminal 20 in parallel (synchronized) with each other via multiple links of the link set LS. In one example, each of the radio signal processing units (two or more corresponding ones of 150, 160, and 170) that transmit the trigger signals is notified of an rTWT start time based on the time information from the communication management unit 130. Then, the radio signal processing units (two or more corresponding ones of 150, 160, and 170) that have been notified of the rTWT start time generate a trigger frame TF so that they can transmit trigger signals in parallel with each other at the start of the rTWT-SP.

[0070] Furthermore, the multiple trigger frames TF that have been subjected to the redundancy process do not need to be completely identical to each other. In one example, in the redundancy process, each trigger frame TF is customized so that it has information specific to each link that transmits a trigger signal. In another example, only information that is common to multiple links is duplicated in the redundancy process. Then, using the information that is common to multiple links, a trigger frame TF is generated for each of the links that transmit a trigger signal, i.e., for multiple corresponding STA1 to STA3. Furthermore, the target on which the redundancy process is performed is not limited to the trigger frame TF; for example, the redundancy process may be similarly performed on beacon frames.

[0071] 5 and 6, when the wireless signal processing unit 250 of the terminal 20 receives a trigger signal from the AP 10, a trigger frame TF is input from the MAC frame processing unit 240 to the communication management unit 230. The input trigger frame TF causes the communication management unit 230 to recognize that it has received an instruction from the AP 10 to transmit uplink data requiring low latency during the rTWT-SP. The communication management unit 230 also recognizes, from the trigger frame TF, the resources allocated for transmitting uplink data requiring low latency in the rTWT-SP.

[0072] Furthermore, when a trigger signal is transmitted through each of the multiple links of the link set LS, the radio signal processing unit 250 of the terminal 20 may receive the trigger signal from each of the multiple links (multiple channels). In this case, when a trigger frame TF is input from each of the multiple links, the MAC frame processing unit 240 may perform a duplication check to check for overlapping information between the multiple input trigger frames TF. When performing the duplication check, the MAC frame processing unit 240 keeps only the information of one trigger frame TF for overlapping information between the multiple trigger frames TF and discards the information of the other trigger frames.

[0073] When a trigger frame is input from the MAC frame processing unit 240, the communication management unit 230 determines a link for transmitting uplink data requiring low latency in the rTWT-SP from the links in the link set LS. If a trigger signal is received from the AP 10 through only one link, the communication management unit 230 sets the link that received the trigger signal as the link for transmitting the uplink data. Then, the management unit 210, which includes the communication management unit 230, causes the wireless signal processing unit 250 to transmit a wireless signal for the uplink data requiring low latency through the link that received the trigger signal, and causes wireless communication with the AP 10 using the link that received the trigger signal until the end of the rTWT-SP, which is the specified period.

[0074] When a trigger signal is received from the AP 10 through each of the multiple links, the communication management unit 230 selects one of the multiple links that received the trigger signal as the link for transmitting uplink data. Then, the management unit 210, which includes the communication management unit 230, causes the wireless signal processing unit 250 to transmit a wireless signal of the uplink data that requires low latency as a second wireless signal through the selected one of the multiple links that received the trigger signal. Then, the communication management unit 230 causes wireless communication with the AP 10 using the selected one of the multiple links that received the trigger signal until the end of the specified period, rTWT-SP.

[0075] The method of selecting one of the multiple links that have received the trigger signal to be used for transmitting uplink data is not particularly limited. In one example, the communication management unit 230 identifies the resource with the earliest transmission timing from the resources for transmitting uplink data allocated in the trigger frame TF. Then, the communication management unit 230 selects the link corresponding to the resource identified as the resource with the earliest transmission timing as the link to be used for transmitting uplink data, i.e., the link to be used for wireless communication with the AP 10 in the rTWT-SP. In another example, the link (channel) with the least interference among the links that have received the trigger signal is selected as the link to be used for transmitting uplink data.

[0076] As described above, in the rTWT-SP, a link is set that the terminal 20 uses for wireless communication with the AP 10, and therefore, when the rTWT function is used, one of the links that constitute the link set LS is determined for each rTWT-SP to be used by the terminal 20 for wireless communication with the AP 10. Therefore, a link that is different from the link that the terminal 20 used for wireless communication with the AP 10 in the previous rTWT-SP may be selected as the link that the terminal 20 uses for wireless communication with the AP 10 in the real-time rTWT-SP.

[0077] The MAC frame processing unit 240 inputs a data frame of traffic requiring low latency to the radio signal processing unit 250 along with information indicating the link to be used for transmitting uplink data in the rTWT-SP. Then, the radio signal processing unit 250 transmits a radio signal of the uplink data requiring low latency to the AP 10 via the link set as the link to be used for transmitting the uplink data. In one example, in response to input of a trigger frame TF to the MAC frame processing unit 240, the MAC frame processing unit 240 of the management unit 210 inputs a data frame requiring low latency to the radio signal processing unit 250. Then, the radio signal processing unit 250 converts the input data frame into a radio signal and transmits it to the AP 10.

[0078] In another example, the MAC frame processing unit 240 acquires the rTWT start time, which is the start time of the rTWT-SP, based on the information included in the beacon frame described above. Then, the MAC frame processing unit 240 inputs a data frame requiring low latency, prior to the start time of the rTWT-SP, to the wireless signal processing unit 250 together with time information indicating the rTWT start time. Then, in response to receiving a trigger signal, the wireless signal processing unit 250 converts the data frame input from the MAC frame processing unit 240 into a wireless signal and transmits the converted wireless signal to the AP 10.

[0079] FIG. 9 is a block diagram showing an example of the functional configuration of a channel access function of a terminal 20, which is an SR terminal according to an embodiment. In the example of FIG. 9, one channel access function is provided in a radio signal processing unit 250, and the channel access function checks the status of one of the data transmissions among the multiple links constituting a link set LS. In one example, the channel access function is provided in the MAC frame processing unit 240 instead of the radio signal processing unit 250. In another example, the radio signal processing unit 250 is provided with the same number of channel access functions as the number of links constituting the link set LS, one channel access function for each of the multiple links in the link set LS. Each of the multiple channel access functions checks the status of a corresponding one of the links in the link set LS. As shown in FIG. 9, the channel access function is composed of, for example, a classification unit 251, queues 252A, 252B, 252C, and 252D, carrier sense execution units 253A, 253B, 253C, 253D, and 253E, and an internal collision management unit 254.

[0080] The basic operation of classification unit 251 is similar to that of classification unit 151 of AP 10, and the basic functions of queues 252A, 252B, 252C, and 252D are similar to those of queues 152A, 152B, 152C, and 152D of AP 10, respectively. The basic operation of carrier sense execution units 253A, 253B, 253C, and 253D is similar to those of carrier sense execution units 153A, 153B, 153C, and 153D of AP 10, respectively, and the basic operation of internal collision management unit 254 is similar to that of internal collision management unit 154 of AP 10.

[0081] Here, a data frame with an access category of LL, which requires low latency, is input to the channel access function of the radio signal processing unit 250 of the terminal 20. The channel access function transmits uplink data with an access category of LL using the rTWT function. By using the rTWT function, the uplink data with an access category of LL is preferentially transmitted from the terminal 20 to the AP 10 during the rTWT-SP. In the rTWT-SP, where transmission of uplink data with an access category of LL is prioritized, transmission of uplink data with access categories other than LL is suppressed. In the example channel access function of FIG. 9 , the classification unit 241 inputs a data frame with an access category of LL to the carrier sense execution unit 253E without passing through any of the queues 252A to 252D.

[0082] Furthermore, in the channel access function of the terminal 20, in addition to the carrier sense execution units 253A to 253D, the carrier sense execution unit 253E also performs carrier sensing in accordance with preset access parameters. The carrier sense execution unit 253E performs carrier sensing on uplink data whose access category is LL. In the channel access function of the terminal 20, for example, the above-mentioned access parameters are set so that the transmission of radio signals is prioritized in the order of LL, VO, VI, BE, and BK. Therefore, in the channel access function of the terminal 20, particularly in rTWT-SP, traffic whose access category is LL performs processes such as acquiring transmission rights with lower latency compared to other traffic. In one example, by temporarily suspending the carrier sense of the carrier sense execution units 253A to 253D, the transmission of traffic of access categories other than LL is temporarily suspended, and the transmission of traffic of the LL access category is prioritized.

[0083] In the functional configurations of Figures 5 and 6, when the rTWT function is used, when a trigger signal (first wireless signal) is transmitted to the terminal 20 from each of the multiple wireless processing units (two or more of 150, 160, and 170) of the AP 10, the management unit 210 of the terminal 20 transmits an uplink data wireless signal (second wireless signal) to the AP 10 through one of the multiple links that received the trigger signal. Therefore, the AP 10 receives the uplink data wireless signal transmitted from the terminal 20 in response to the trigger signal through one of the multiple links that transmitted the trigger signal. That is, in the AP 10, a corresponding one of the wireless signal processing units 150, 160, and 170 (STA1 to STA3) receives the uplink data wireless signal.

[0084] When the AP 10 receives uplink data corresponding to the trigger signal, the management unit 110 (communication management unit 130) causes wireless communication with the terminal 20 through one of the wireless signal processing units 150, 160, 170 (STA1 to STA3) that received the uplink data (second wireless signal) until the end of the rTWT-SP, which is a specified period. Therefore, until the end of the rTWT-SP, the AP 10 communicates wirelessly with the terminal 20 through only one of the links in the link set LS that received the uplink data (second wireless signal).

[0085] For example, in the rTWT-SP, following uplink data received from the terminal 20, downlink data may be transmitted from the AP 10 to the terminal 20. In this case, the MAC frame processing unit 140 inputs a data frame of the downlink data to the radio signal processing unit (corresponding one of 150, 160, and 170) that received the uplink data. Then, the management unit 110 causes the radio signal of the downlink data to be transmitted to the terminal 20 from the radio signal processing unit (corresponding one of 150, 160, and 170) that received the uplink data, i.e., through one of the links in the link set LS that received the uplink data.

[0086] Furthermore, when a trigger signal is transmitted through each of the multiple links, the management unit 110 (communication management unit 130) releases all of the multiple links that have transmitted the trigger signal except for one that has received uplink data from the terminal 20 from wireless communication with the terminal 20. That is, the wireless signal processing units (one or more corresponding units of 150, 160, and 170) that have not received uplink data from the terminal 20 after transmitting the trigger signal are released from resources for wireless communication with the terminal 20 in the rTWT-SP. The management unit 110 notifies the wireless signal processing units (one or more corresponding units of 150, 160, and 170) that have not received uplink data from the terminal 20 after transmitting the trigger signal that they will be released from resources for wireless communication with the terminal 20.

[0087] In one example, a link (channel) released from a resource for wireless communication with terminal 20 is newly assigned as a resource for wireless communication by AP 10 to terminals other than terminal 20 until the end of rTWT-SP. In this case, MAC frame processing unit 140 inputs, for example, a trigger frame indicating a new assignment as a resource for the link released from wireless communication with terminal 20 to a wireless signal processing unit (corresponding one or more of 150, 160, and 170) released from wireless communication with terminal 20. As a result, the link (channel) released from wireless communication with terminal 20 is newly assigned as a resource for wireless communication with terminals other than terminal 20.

[0088] It should be noted that the new allocation of resources for a link released from wireless communication with the terminal 20 does not necessarily have to be performed by the management unit 110. In one example, a wireless signal processing unit (corresponding one or more of 150, 160, and 170) released from wireless communication with the terminal 20 determines the new allocation of resources for the corresponding link (channel).

[0089] Furthermore, in the rTWT-SP, the link used for wireless communication with the terminal 20 and the link released from the wireless communication with the terminal 20 may have channel frequencies that are close enough to each other to cause power leakage. That is, in the rTWT-SP, the link used for wireless communication with the terminal 20 and the link released from the wireless communication with the terminal 20 may have an NSTR (Non-Simultaneous Transmit and Receive) relationship with each other. In this case, it is preferable that the link (channel) released from the wireless communication with the terminal 20 be newly allocated as a resource so that it is not used for transmitting data from the AP 10 to terminals other than the terminal 20.

[0090] 10 is a flowchart showing an example of processing performed by the management unit 110 of the AP 10 according to the embodiment when using the rTWT function. The example processing of FIG. 10 is performed to transmit uplink data requiring low latency to the terminal 20 at each rTWT-SP. Furthermore, when performing the example processing of FIG. 10, it is assumed that immediately before the rTWT-SP, one or more links of the link set LS are in an idle state, and the AP 10 is capable of transmitting wireless signals to the terminal 20 through one or more links of the link set LS. When the example processing of FIG. 10 starts, the management unit 110 determines whether there are multiple idle links (channels) in the link set LS (S301).

[0091] If only one link is in the idle state (S301-No), the management unit 110 transmits the trigger signal to the terminal 20 through the idle link, i.e., from the wireless signal processing unit (corresponding one of 150, 160, and 170) corresponding to the idle link (S302).The management unit 110 then determines whether or not uplink data from the terminal 20 has been received on the link that transmitted the trigger signal (S303).The process waits in S303 until uplink data from the terminal 20 is received.

[0092] Then, when the management unit 110 receives uplink data from the terminal 20 (S303—Yes), the management unit 110 causes wireless communication with the terminal 20 through the link on which the uplink data was received (S304). Therefore, the management unit 110 causes downstream data following the uplink data to be transmitted to the terminal 20 through the link on which the uplink data was received. Then, the management unit 110 determines whether the rTWT-SP has ended (S305). Unless the rTWT-SP has ended (S305—No), the process returns to S304, and the management unit 110 causes wireless communication with the terminal 20 through the link on which the uplink data was received.

[0093] Furthermore, if multiple links are in the idle state in S301 (S301-Yes), the management unit 110 transmits the trigger signal (first wireless signal) to the terminal 20 through each of the multiple idle links, i.e., from each of the wireless signal processing units (two or more corresponding units among 150, 160, and 170) corresponding to the multiple idle links (S311). At this time, the trigger signals are transmitted to the terminal 20 in parallel via the multiple links. The management unit 110 then determines whether or not uplink data from the terminal 20 has been received via any of the multiple links that transmitted the trigger signal (S312). The process waits in S312 until uplink data from the terminal 20 is received via any one of the multiple links.

[0094] Then, when uplink data from terminal 20 is received via one of the multiple links via which the trigger signal was transmitted (S312—Yes), the management unit 110 causes wireless communication with terminal 20 via the link via which the uplink data was received (S313). Therefore, the management unit 110 transmits downstream data following the uplink data to terminal 20 via one of the multiple links via which the uplink data was received. Furthermore, the management unit 110 releases all of the multiple links via which the trigger signal was transmitted, except for the one link via which the uplink data was received, from wireless communication with terminal 20 (S314). At this time, the link released from wireless communication with terminal 20 may be allocated as a resource to be used for wireless communication between terminals other than terminal 20 and AP 10.

[0095] Then, the management unit 110 determines whether the rTWT-SP has ended (S315). Unless the rTWT-SP has ended (S315-No), the process returns to S313. Therefore, until the rTWT-SP ends, the management unit 110 causes wireless communication with the terminal 20 through the link that received the upstream data, and releases links other than the link that received the upstream data from wireless communication with the terminal 20.

[0096] In one example, at the start of an rTWT-SP, the trigger signal is transmitted to the terminal 20 through each of the multiple links of the link set LS, and the trigger signal is not transmitted through only one link. In this case, the processes of S302 to S305 are not performed, and the processes of S311 to S315 are performed sequentially for each rTWT-SP.

[0097] FIG. 11 is a flowchart showing an example of processing performed by the management unit 210 of the terminal 20 according to the embodiment when using the rTWT function. The example processing of FIG. 11 is performed to transmit uplink data requiring low latency to the AP 10 for each rTWT-SP. Furthermore, when performing the example processing of FIG. 11, it is assumed that a trigger signal is transmitted from the AP 10 to the terminal 20 by the example processing of FIG. 10 or the like. When the example processing of FIG. 11 starts, the management unit 210 determines whether a trigger signal from the AP 10 has been received via any of the links (S321). The processing waits in S321 until a trigger signal is received via any of the links. Then, when a trigger signal is received (S321—Yes), the management unit 210 determines whether a trigger signal has been received via multiple links in the link set LS (S322).

[0098] If the trigger signal is received through only one link (S322-No), the management unit 210 causes wireless communication with the AP 10 through the link through which the trigger signal was received (S323). Therefore, the management unit 210 causes uplink data, etc., which require low latency, to be transmitted to the AP 10 through the link through which the trigger signal was received. The management unit 210 then determines whether the rTWT-SP has ended (S324). Unless the rTWT-SP has ended (S324-No), the process returns to S323, and the management unit 210 causes wireless communication with the AP 10 through the link through which the trigger signal was received.

[0099] Furthermore, if trigger signals are received over multiple links in S322 (S322—Yes), the management unit 210 selects one of the links that received the trigger signal to transmit upstream data, etc., requiring low latency (S331). At this time, one link is selected using one of the methods described above. The management unit 210 then controls wireless communication with the AP 10 through the selected link (S332). Therefore, the management unit 210 controls wireless communication with the AP 10 through one of the links that received the trigger signal, requiring low latency. The management unit 210 then determines whether the rTWT-SP has ended (S333). Unless the rTWT-SP has ended (S333—No), the process returns to S332, and the management unit 210 controls wireless communication with the AP 10 through the selected link.

[0100] 12 is a schematic diagram showing temporal changes in the communication state through a link set between an AP 10 and a terminal 20 in a communication system 1 according to an embodiment. In FIG. 12, two STA functions STA1, STA2, and STA3 of the AP 10 form links with the ESTA function of the terminal 20, with link IDs of "STA1," "STA2," and "STA3," respectively, in a link set LS. In the example of FIG. 12, the management unit 110 of the AP 10 causes the AP 10 to transmit a trigger signal to the terminal 20 through each of the three links "STA1," "STA2," and "STA3" at the start of an rTWT-SP.

[0101] Then, the management unit 210 selects the link of "STA1" from the three links that received the trigger signal as the link for transmitting uplink data in the rTWT-SP. Then, the management unit 210 transmits the uplink data through the selected link of "STA1". Then, when the AP 10 receives the uplink data through the link of "STA1", the management unit 210 transmits subsequent downlink data to the terminal 20 through the link of "STA1". Therefore, until the end of the rTWT-SP, the AP 10 and the terminal communicate wirelessly with each other through the link of "STA1". Also, in the example of FIG. 12, the management unit 110 releases the links of "STA2" and "STA3", which were not selected as the links for transmitting uplink data, from wireless communication with the terminal 20.

[0102] As described above, in this embodiment, the management unit 110 of the AP 10 transmits a trigger signal, which serves as a first wireless signal, from each of a plurality of wireless signal processing units (two or more corresponding to 150, 160, and 170), to the terminal 20. Then, the management unit 210 of the terminal 20 transmits a wireless signal of uplink data as a second wireless signal to the AP 10 through one of the plurality of links through which the trigger signal was received. Then, until the end of the specified period, rTWT-SP, the AP 10 and the terminal 20 wirelessly communicate with each other through the one link through which the terminal 20 transmitted the uplink data.

[0103] Since wireless communication in the rTWT-SP is performed as described above, even if a problem occurs in the wireless communication between the AP 10 and the terminal 20 through one of the multiple links, the management unit 210 can transmit uplink data to the AP 10 through another one of the multiple links through which the trigger signal was received. For example, by transmitting a trigger signal to the terminal 20 through each of the three links "STA1", "STA2", and "STA3", even if a problem occurs in the wireless communication through the link of "STA1", it is possible to select either "STA2" or "STA3" as the link for transmitting uplink data.

[0104] Therefore, in this embodiment, redundancy is appropriately achieved even when uplink data is transmitted to an AP from a terminal provided with only one STA function, such as the terminal 20. In other words, even for a terminal that cannot transmit data in parallel over multiple links, it is possible to ensure reliability in transmitting uplink data to the AP 10 and to ensure reliability in data exchange between the terminal 20 and the AP 10.

[0105] Furthermore, in this embodiment, among the links used to transmit the trigger signal, links (channels) that are not selected as links for transmitting uplink data are released by the management unit 110 from wireless communication with the terminal 20. Therefore, links (channels) that are not used to transmit uplink data in the rTWT-SP can also be effectively utilized by using them for wireless communication between the AP 10 and terminals other than the terminal 20.

[0106] In the following modified example, before the start of the rTWT-SP, the management unit 210 selects a link in the link set LS to be used for transmitting uplink data in the rTWT-SP. In this modified example, when the rTWT function is in use, before the start of the rTWT-SP, which is a specified period, the management unit 110 of the AP 10 transmits an RTS (Request To Send) signal as a first wireless signal. At this time, the RTS signal is transmitted to the terminal 20 through each of the multiple links in the link set LS, and is transmitted in parallel (synchronized) from multiple wireless communication units (two or more corresponding to 150, 160, and 170) to each other. The RTS signal notifies terminals 20 other than the terminal 20 that the AP 10 plans to wirelessly communicate with the terminal 20 in the rTWT-SP.

[0107] In this modification, when the terminal 20 receives an RTS signal through each of a plurality of links, the management unit 210 selects one of the plurality of links through which the RTS signal was received. Then, before the rTWT-SP is started, the management unit 210 transmits a CTS (Clear To Send) signal to the AP 10 as a second wireless signal through the selected link. At this time, the CTS signal from the terminal 20 to the AP 10 is not transmitted through any link other than the link through which the CTS signal was transmitted among the links used to transmit the RTS signal. The CTS signal notifies the terminals 20 other than the terminal 20 that the link (channel) through which the CTS signal was transmitted will be used for wireless communication between the AP 10 and the terminal 20 in the rTWT-SP.

[0108] In this modification, the AP 10 receives a CTS signal through one of the links corresponding to the link through which the RTS signal was transmitted, i.e., through one of the wireless signal processing units 150, 160, and 170. Then, at the start of the rTWT-SP, the management unit 110 transmits the aforementioned trigger signal to the terminal 20 through one of the links through which the CTS signal was received among the links through which the RTS signal was transmitted. As a result, the terminal 20 receives the trigger signal through the link through which the CTS signal was transmitted. Then, during the rTWT-SP, which is a specified period, the AP 10 and the terminal 20 wirelessly communicate with each other through the link used to transmit the CTS signal. Furthermore, the management unit 110 releases all of the links through which the RTS signal was transmitted, except for the one through which the CTS signal was received, from wireless communication with the terminal 20 until the end of the rTWT-SP.

[0109] FIG. 13 is a flowchart illustrating an example of processing performed by the management unit 110 of the AP 10 according to the modified example when using the rTWT function. The example processing of FIG. 13 is performed to transmit uplink data requiring low latency to the terminal 20 at each rTWT-SP. Furthermore, when performing the example processing of FIG. 13, it is assumed that immediately before the rTWT-SP, wireless signals can be transmitted from the AP 10 to the terminal 20 via each of the multiple links in the link set LS. When the example processing of FIG. 13 begins, the management unit 110 transmits an RTS signal as a first wireless signal to the terminal 20 via each of the multiple links in the link set LS (S341). Then, the management unit 110 determines whether a CTS signal from the terminal 20 has been received via any of the multiple links to which the RTS signal was transmitted (S342). The processing waits in S342 until a CTS signal from the terminal 20 is received via any one of the multiple links.

[0110] Then, when the management unit 110 receives a CTS signal from the terminal 20 via one of the multiple links through which the RTS signal was transmitted (S342—Yes), the management unit 110 waits until the rTWT start time (the start time of the rTWT-SP) (S343—No). When the rTWT start time arrives (S343—Yes), the management unit 110 transmits a trigger signal to the terminal 20 via the link through which the CTS signal was received (S344). The management unit 110 then wirelessly communicates with the terminal 20 via the link through which the CTS signal was received (S345). Furthermore, the management unit 110 releases all of the multiple links through which the RTS signal was transmitted, except for the one link through which the CTS signal was received, from wireless communication with the terminal 20 (S346).

[0111] Then, the management unit 110 determines whether the rTWT-SP has ended (S347). Unless the rTWT-SP has ended (S347-No), the process returns to S345. Therefore, until the rTWT-SP ends, the management unit 110 allows wireless communication with the terminal 20 through the link that received the CTS signal, and releases links other than the link that received the CTS signal from wireless communication with the terminal 20.

[0112] 14 is a flowchart showing an example of processing performed by the management unit 210 of the terminal 20 according to the modified example of FIG. 13 when using the rTWT function. The example processing of FIG. 14 is performed to transmit uplink data requiring low latency to the AP 10 for each rTWT-SP. Furthermore, when performing the example processing of FIG. 14, it is assumed that an RTS signal is transmitted from the AP 10 to the terminal 20 via each of multiple links, as in the example processing of FIG. 13. When the example processing of FIG. 14 starts, the management unit 210 determines whether the RTS signal transmitted from the AP 10 has been received on each of the multiple links (S351). The processing waits in S351 until the multiple links receive the RTS signal.

[0113] When RTS signals are received over multiple links (S351—Yes), the management unit 210 selects one of the links that received the RTS signal to be used for transmitting uplink data that requires low latency (S352).The management unit 210 then transmits a CTS signal to the AP 10 over the selected link (S353).The management unit 210 then waits until it receives a trigger signal from the AP 10 over the selected link that transmitted the CTS signal (S354—No).

[0114] When the management unit 210 receives a trigger signal through the link that transmitted the CTS signal (S354-Yes), the management unit 210 causes wireless communication with the AP 10 through the selected link that received the trigger signal (S355). Then, unless the rTWT-SP is terminated (S356-No), the process returns to S355, and the management unit 210 causes wireless communication with the AP 10 through the selected link.

[0115] 15 is a schematic diagram showing temporal changes in the communication state through a link set between an AP 10 and a terminal 20 in a communication system 1 according to a modified example. In the example of FIG. 15, the management unit 110 of the AP 10 causes the AP 10 to transmit an RTS signal to the terminal 20 through each of the three links "STA1", "STA2", and "STA3" before the rTWT-SP is started. Then, the management unit 210 selects the link "STA1" from the three links that received the RTS signal as the link for transmitting uplink data in the rTWT-SP. Then, the management unit 210 causes the CTS signal to be transmitted through the selected link "STA1".

[0116] Then, when the AP 10 receives a CTS signal via the link "STA1", the management unit 110 transmits a trigger signal to the terminal 20 via the link "STA1" at the start of the rTWT-SP. As a result, from the start to the end of the rTWT-SP, the AP 10 and the terminal communicate wirelessly with each other via the link "STA1". Therefore, in the rTWT-SP, uplink data to the AP 10 is transmitted via the link "STA1". In addition, in the example of FIG. 15, the management unit 110 releases the links "STA2" and "STA3", which were not selected as links for transmitting uplink data, from wireless communication with the terminal 20.

[0117] The modified example also achieves the same effects and advantages as the above-described embodiment, etc. That is, the modified example also ensures reliability in transmitting uplink data to the AP 10 in a terminal provided with only one STA function, such as the terminal 20, and ensures reliability in exchanging data between the terminal 20 and the AP 10. Furthermore, the modified example also makes it possible to effectively utilize links (channels) that are not used for transmitting uplink data in the rTWT-SP.

[0118] In addition, in the modified example, a link to be used for transmitting uplink data from the terminal 20 to the AP 10 in the rTWT-SP, which is a specified period, is determined before transmitting a trigger signal to the terminal 20. Therefore, it is not necessary to newly allocate resources for the link (channel) released from wireless communication with the terminal 20 in the rTWT-SP after the start of the rTWT-SP, i.e., after transmitting the trigger signal.

[0119] In the above-described embodiment and modified example, the AP 10 communicates wirelessly with the terminal 20 using three STA functions, and the link set LS between the AP 10 and the terminal 20 is composed of three links, but this is not limiting. In the embodiment, etc., if the AP 10 communicates wirelessly with the terminal 20 using multiple STA functions, and the link set LS between the AP 10 and the terminal 20 is composed of multiple links, the above-described functions can be applied and the above-described processes can be executed.

[0120] The processes according to the above-described embodiments and modifications can be stored as a program that can be executed by a processor, which is a computer. The program that executes the above-described processes can be stored and distributed in a storage medium of an external storage device, such as a magnetic disk, an optical disk, or a semiconductor memory. The processor can then read the program stored in the storage medium of the external storage device, and its operation can be controlled by the read program, thereby executing the processes of the embodiments, etc.

[0121] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention.

[0122] 1...Communication system 10...Access point (AP) 20...Terminal 30...Network 11, 21...CPU 12, 22...ROM 13, 23...RAM 14, 24...Wireless communication module 15...Wired communication module 25...Display 26...Storage 100, 200...LLC processing unit 110, 210...Management unit 120, 220...Data processing unit 130, 230...Communication management unit 131, 231...Link management information 132, 232...Link control unit 133, 233...Beacon management unit 134...Trigger generation unit 140, 240...MAC frame processing unit 150, 160, 170, 250...Wireless signal processing unit 151, 251...Classification unit 152A to 152D, 252A to 252D...Queue 153A to 153D, 253A to 253E... Carrier sense execution unit 154, 254... Internal collision management unit 280... Application execution unit

Claims

1. A plurality of radio signal processing units; a management unit that uses the plurality of wireless signal processing units to establish a plurality of links with a terminal and causes each of the plurality of wireless signal processing units to transmit a first wireless signal to the terminal, and that, based on reception by one of the plurality of wireless signal processing units of a second wireless signal transmitted from the terminal in response to the transmission of the first wireless signal, causes one of the plurality of wireless signal processing units that received the second wireless signal to perform wireless communication with the terminal until the end of a specified period; An access point comprising:

2. the management unit causes each of the plurality of radio signal processing units to transmit, as the first radio signal, a trigger signal instructing transmission of uplink data at a start of the specified period; one of the plurality of radio signal processing units receives, during the specified period, uplink data transmitted from the terminal in response to the trigger signal as the second radio signal; The access point of claim 1.

3. the management unit causes each of the plurality of radio signal processing units to transmit an RTS signal or an MU-RTS signal as the first radio signal before the specified period starts; One of the plurality of radio signal processing units receives, as the second radio signal, a CTS signal transmitted from the terminal in response to the RTS signal or the MU-RTS signal before the specified period begins; the management unit causes one of the plurality of wireless signal processing units that has received the CTS signal to transmit a trigger signal instructing transmission of uplink data to the terminal at the start of the specified period; The access point of claim 1.

4. The access point of claim 1, wherein the management unit releases all of the plurality of wireless signal processing units except for the one that received the second wireless signal from wireless communication with the terminal during the period from when one of the plurality of wireless signal processing units receives the second wireless signal to the end of the specified period.

5. A radio signal processing unit; a management unit that uses the wireless signal processing unit to establish a plurality of links with an access point, and causes the wireless signal processing unit to transmit a second wireless signal through one of the plurality of links based on the wireless signal processing unit receiving a first wireless signal transmitted from the access point through each of the plurality of links, and causes wireless communication with the access point using one of the plurality of links through which the second wireless signal was transmitted until the end of a specified period from the transmission of the second wireless signal; A terminal comprising:

6. the wireless signal processing unit receives, as the first wireless signal, a trigger signal that is transmitted from the access point through each of the plurality of links at a start of the specified period and that instructs transmission of uplink data; the management unit, in response to the wireless signal processing unit receiving the trigger signal during the specified period, causes the wireless signal processing unit to transmit uplink data as the second wireless signal to the access point through one of the plurality of links; The terminal of claim 5.

7. the wireless signal processing unit receives, as the first wireless signal, an RTS signal or an MU-RTS signal transmitted from the access point through each of the plurality of links before the specified period starts; the management unit, in response to the radio signal processing unit receiving the RTS signal or the MU-RTS signal before the specified period starts, causes the radio signal processing unit to transmit a CTS signal as the second radio signal to the access point through one of the plurality of links; the wireless signal processing unit receives a trigger signal, which is transmitted from the access point at the start of the specified period and which instructs transmission of uplink data, through one of the multiple links that transmitted the CTS signal; The terminal of claim 5.