Access points and terminals

Abstract

This invention provides an access point and terminal that ensure reliability in data exchange between a terminal equipped with only one STA function and an access point. [Solution] In the communication system, the access point 10 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 link set LS consisting of a plurality of links with the terminal 20, and causes each of the plurality of wireless signal processing units to transmit a first wireless signal to the terminal. Based on the fact that one of the plurality of wireless signal processing units has received a second wireless signal transmitted from the terminal in response to the transmission of the first wireless signal, the management unit causes the one of the plurality of wireless signal processing units that received the second wireless signal to transmit wireless communication to the terminal until the end of a specified period.

Description

Technical Field

[0001] Embodiments of the present invention relate to an access point and a terminal.

Background Art

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

[0003] In IEEE802.11be, which is being formulated as a successor standard to IEEE802.11ax, it becomes possible to establish a link set composed of a plurality of links between a terminal and an AP. When a link set composed of a plurality of 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 right to transmit.

[0004] Here, in a terminal in which only one STA function corresponding to a wireless signal processing unit is provided, even if a plurality of links are logically established with an AP, it is physically impossible to transmit data to the AP in parallel with respect to each other through the plurality of links. In a communication system, when transmitting uplink data such as traffic for which low latency is required from a terminal in which only one STA function is provided to an AP, it is required that redundancy is appropriately performed. That is, it is required to ensure the reliability in the exchange of data between a terminal in which only one STA function is provided and an AP.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

[0006] The object of the present invention is to provide an access point and a terminal that ensure reliability in data exchange between a terminal equipped with only one STA function and an access point. [Means for solving the problem]

[0007] In one embodiment of the present invention, the access point 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 causes each of the plurality of wireless signal processing units to transmit a first wireless signal to the terminal. Based on the fact that one of the plurality of wireless signal processing units has received a second wireless signal transmitted from the terminal in response to the transmission of the first wireless signal, the management unit causes the one of the plurality of wireless signal processing units that received the second wireless signal to transmit wireless signals to the terminal until the end of a specified period. [Effects of the Invention]

[0008] According to the present invention, an access point and a terminal are provided in which reliability is ensured when exchanging data between a terminal equipped with only one STA function and an access point. [Brief explanation of the drawing]

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

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments 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 referred to as a “base station” of a wireless LAN. The AP 10 communicates with a server (not shown) on the network 30 by wire or wirelessly. 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 1 can be wirelessly connected to the terminal 20 and communicates with the terminal 20 wirelessly. The wireless communication between the terminal 20 and the AP 10 complies with the IEEE802.11 standard. In the following description, wireless communication compliant with the IEEE802.11 standard will be described as an example, but a wireless communication standard different from the IEEE80..11 standard may 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 IEEE802.11 standard. In the OSI reference model, the wireless communication function is 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, Layer 7: Application Layer). The data link layer, which is the second layer, includes an LLC (Logical Link Control) sublayer and a MAC (Media Access Control) sublayer.

[0014] In the wireless connection between the AP 10 and the terminal 20, a link set LS composed of a plurality of links is established. Each of the plurality of links in the link set LS is established using the STA function provided as a functional configuration in each of the AP 10 and the terminal 20. A plurality of STA functions are provided in the AP 10, and only one STA function is provided in the terminal 20. In each of the AP 10 and the terminal 20, the STA function corresponds to a wireless signal processing unit 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 plurality of links in the link set LS, one corresponding to the plurality of STA functions of the AP 10 and the STA function of the terminal 20 are used. Therefore, the only one STA function provided in the terminal 20 is used to establish all the links constituting the link set LS.

[0016] As mentioned above, in the link set LS established between AP10 and terminal 20, AP10 can transmit data to terminal 20 in parallel via multiple links. However, in the link set LS, terminal 20 cannot transmit data to AP10 in parallel via multiple links. That is, at the same time, uplink data etc. can only be transmitted from terminal 20 to AP10 through one of the multiple links of the link set LS. Terminal 20 can receive downlink data via multiple links of the link set LS. Although terminal 20 can receive management frames described later in parallel via multiple links of the link set LS, the data can be received via only one of the multiple links.

[0017] Here, the STA function, which is provided as the only wireless signal processing unit in terminal 20, is also called the "ESTA (Enhanced STA) function." Furthermore, terminals like terminal 20, which are provided as the only STA function with the ESTA function, are also called "SR (Single Radio) terminals." The function of establishing a link set LS between AP10 and terminal 20, which is an SR terminal, as described above, and then using the link set LS to wirelessly communicate between AP10 and terminal 20 as described above, is also called the "EMLSR (Enhanced Multi Link Single Radio) function." AP10 and terminal 20 manage the state of the link between AP10 and terminal 20, including the state of the link set LS, using link management information.

[0018] Figure 2 is a schematic diagram showing an example of link management information between AP10 and terminal 20 in a communication system 1 according to an embodiment. The link management information includes, for example, information about “Link ID”, “Link”, “Frequency Band”, “Channel ID”, “Link Set”, and “Traffic”. “Link ID” is an identifier associated with the aforementioned STA function of AP10. In the example in Figure 2, three STA functions (STA1, STA2, STA3) are assigned to wireless communication between AP10 and terminal 20. The information about “Link” indicates whether each of the multiple STA functions of AP10 has established a link with terminal 20. In the example in Figure 2, the state in which each of AP10's STA1 to STA3 has established a link with terminal 20 is shown.

[0019] The "Frequency Band" information indicates the frequency band assigned to each link. For example, the 6GHz band, 5GHz band, and 2.4GHz band may be applicable. Each of the multiple frequency bands contains multiple channels. The "Channel ID" indicates the ID of the channel assigned to each link. In the example in Figure 2, the links corresponding to STA1, STA2, and STA3 are assigned channels CH1, CH2, and CH3 of the 5GHz band, respectively. Note that multiple links in linkset LS may be assigned different frequency bands to each other, or they may be assigned different channels of the same frequency band to each other.

[0020] The information about “Link Set” indicates whether or not a Link Set LS, consisting of multiple links, has been established between AP10 and terminal 20. If a Link Set LS has been established, the information about “Link Set” also indicates which links make up the Link Set LS. In the example in Figure 2, the Link Set LS is composed of three links: the link corresponding to STA1, the link corresponding to STA2, and the link corresponding to STA3.

[0021] The information about “traffic” shows the TID (Traffic Indicator) assigned to each link (each of AP10’s STA functions). The TID is an identifier that identifies each piece of traffic, and each piece of traffic may be associated with an access category. Traffic access categories 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 in Figure 2, TID#1 corresponds to one of VO, VI, BE, BK, and LL. TID#1 is then assigned to the link corresponding to STA1, the link corresponding to STA2, and the link corresponding to STA3, respectively.

[0022] Here, once the link set LS is established, data can be transmitted from AP10 to terminal 20 in parallel across multiple links of the link set LS. For example, for downlink data from AP10 to terminal 20, although not limited to these examples, only one link of the link set LS may be assigned to a single TID, or multiple links of the link set LS may be assigned to it. Furthermore, the association between traffic and links (the STA function of AP10) is set, for example, so that the amount of traffic (amount of data) is equal among the multiple links that make up 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 that does not require low latency, may be grouped together on a specific link of the link set LS.

[0023] Furthermore, AP10 and terminal 20 have rTWT (restricted Target Wake Time) functionality. By utilizing the rTWT functionality, AP10 and terminal 20 ensure that terminal 20 has an opportunity to transmit low-latency traffic (uplink data) to AP10 in the link set LS established between AP10 and terminal 20. The rTWT functionality sets a service period during which the transmission and reception of low-latency traffic is prioritized over the transmission and reception of traffic that does not require low latency. This service period set as a specified period by the rTWT functionality is also called "rTWT-SP (Service Period)".

[0024] Figure 3 is a block diagram showing an example of the hardware configuration of AP10 according to an embodiment. As shown in Figure 3, AP10 includes, for example, a CPU (Central Processing Unit) 11, ROM (Read Only Memory) 12, RAM (Random Access Memory) 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 workspace for the CPU 11. The wireless communication module 14 is a circuit used for transmitting and receiving data via wireless signals. The wireless communication module 14 is connected to an antenna. The wired communication module 15 is a circuit used for transmitting and receiving data via wired signals. The wired communication module 15 is connected to the network 30.

[0026] Figure 4 is a block diagram showing an example of the hardware configuration of terminal 20 according to this embodiment. As shown in Figure 4, terminal 20 includes, for example, a CPU 21, ROM 22, RAM 23, wireless communication module 24, display 25, and 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 workspace for the CPU 21. The wireless communication module 24 is a circuit used for sending 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) or the like corresponding to the application software. The storage 26 is a non-volatile storage device. The storage 26 stores the system software of the terminal 20.

[0028] Figure 5 is a block diagram showing an example of the functional configuration of AP10 according to an embodiment. As shown in Figure 5, AP10 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 can be realized, for example, by a combination of a CPU 11, RAM 13, and a wired communication module 15. The processing of the management unit 110 and the wireless signal processing units 150, 160, and 170 can each be realized, for example, by a combination of a CPU 11, RAM 13, and a wireless communication module 14. The LLC processing unit 100 performs, for example, processing of the LLC sublayer of the second layer and processing of the third to seventh layers. The management unit 110 performs processing of the MAC sublayer of the second layer. The wireless signal processing units 150, 160, and 170 perform processing of the MAC sublayer of the second layer and processing of the first layer. 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 adds DSAP (Destination Service Access Point) headers and SSAP (Source Service Access Point) headers to the data received from the network 30 to generate an LLC packet. The LLC processing unit 100 then inputs the generated LLC packet to the data processing unit 120. The LLC processing unit 100 also receives the LLC packet from the data processing unit 120 and extracts data from the received LLC packet. The LLC processing unit 100 then transmits the extracted data to the network 30.

[0030] The data processing unit 120 adds a MAC header to the LLC packet input from the LLC processing unit 100 to generate a MAC frame. 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 the MAC frame from the MAC frame processing unit 140 and extracts the 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 explanation, the MAC frame containing data will also be referred to as a "data frame".

[0031] The communication management unit 130 manages the communication status between AP10 and terminal 20, including the link status between AP10 and terminal 20. MAC frames containing management information related to wireless communication, such as management information regarding the link 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." The communication management unit 130 can instruct the MAC frame processing unit 140 to execute a predetermined process by outputting management frames to the MAC frame processing unit 140. The communication management unit 130 includes, for example, link management information 131, link control unit 132, beacon management unit 133, and trigger generation unit 134. The communication management unit 130 is also equipped with a clock 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. For MAC frames to be sent to the terminal 20, the MAC frame processing unit 140 identifies the link associated with the MAC frame from the links in link set LS. For example, if a data frame is input as a MAC frame from the data processing unit 120, the MAC frame processing unit 140 identifies the link associated with the TID contained in the data frame. The MAC frame processing unit 140 then inputs the MAC frame to the corresponding wireless signal processing unit (one or more of 150, 160, or 170) that corresponds to the identified link.

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

[0034] The wireless signal processing units 150, 160, and 170 correspond to the STA1, STA2, and STA3 functions of AP10, respectively, as shown in Figure 2. The wireless signal processing units 150, 160, and 170 have similar functional configurations relative to each other. Each of the wireless signal processing units 150, 160, and 170 generates a wireless frame by adding a preamble and a PHY (physical layer) header to the data input from the MAC frame processing unit 140. Then, each of the wireless signal processing units 150, 160, and 170 performs a predetermined modulation operation on the generated wireless frame to convert it into a wireless signal, and radiates (transmits) the wireless signal through the antenna. The predetermined modulation operation includes, for example, convolution coding, interleaving, subcarrier modulation, inverse fast Fourier transform (IFFT), OFDM (Orthogonal Frequency Division Multiplexing) modulation, and frequency conversion.

[0035] Furthermore, each of the wireless signal processing units 150, 160, and 170 converts the wireless signal received from the terminal 20 via the antenna into a wireless frame 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 wireless signal processing unit 150 then extracts MAC frames from the wireless frames and inputs the extracted MAC frames to the MAC frame processing unit 140. Note that the wireless signal processing units 150, 160, and 170 may share the same antenna, or they may use different antennas for each other.

[0036] Figure 6 is a block diagram showing an example of the functional configuration of a terminal 20 according to an embodiment. As shown in Figure 6, the terminal 20 includes, for example, an application execution unit 280, an LLC processing unit 200, a management unit 210, and a wireless signal processing unit 250. The processing of the application execution unit 280 and the LLC processing unit 200 can be realized, for example, by a CPU 21 and a RAM 23. The processing of the management unit 210 and the wireless signal processing unit 250 can be realized, for example, by a combination of a CPU 21, a RAM 23, and a wireless communication module 24. The application execution unit 280 executes processing of the 7th layer, and the LLC processing unit 200 executes processing of the LLC sublayer of the 2nd layer and processing of the 3rd to 6th layers. The management unit 210 executes processing of the MAC sublayer of the 2nd layer, and the wireless signal processing unit 250 executes processing of the MAC sublayer of the 2nd layer and processing of the 1st layer. 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 the application based on the 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 application's operation. The application execution unit 280 can display application information on the display 25. Furthermore, the application execution unit 280 can execute processes corresponding to operations on the input interface.

[0038] The LLC processing unit 200 adds DSAP headers and SSAP headers to the data received from the application execution unit 280 to generate an LLC packet. The LLC processing unit 200 then inputs the generated LLC packet to the data processing unit 220. The LLC processing unit 200 also receives the LLC packet from the data processing unit 220 and extracts data from the received LLC packet. The LLC processing unit 200 then inputs the extracted data to the application execution unit 280.

[0039] The data processing unit 220 adds a MAC header to the LLC packet input from the LLC processing unit 200 to generate a MAC frame. 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 the MAC frame from the MAC frame processing unit 240 and extracts the 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 works in cooperation with the communication management unit 130 of AP10 to manage the communication status between AP10 and terminal 20, including the link status between AP10 and terminal 20. MAC frames (management frames) containing management information related to wireless communication, such as management information regarding links and rTWT, are input and output between the communication management unit 230 and the MAC frame processing unit 240. By outputting management frames to the MAC frame processing unit 240, the communication management unit 230 can instruct the MAC frame processing unit 240 to execute predetermined processes. 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. For MAC frames to be sent to AP10, the MAC frame processing unit 240 identifies the link associated with the MAC frame from the links in link set LS. For example, when a data frame is input from the data processing unit 220, the MAC frame processing unit 240 identifies the link associated with the TID contained in the data frame. The MAC frame processing unit 140 then inputs the MAC frame to the radio signal processing unit 250 along with an instruction to transmit the MAC frame on the identified link.

[0042] Furthermore, when the MAC frame processing unit 240 receives a MAC frame from the wireless signal processing unit 250, it inputs the MAC frame to the data processing unit 220 or the communication management unit 230 according to the type of MAC frame that was input. If the MAC frame is a data frame, the MAC frame is input to the data processing unit 220, and if the MAC frame is a management frame, the MAC frame is input to the communication management unit 230.

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

[0044] The wireless signal processing unit 250 transmits a wireless signal using one of the corresponding links (multiple channels) of the link set LS. However, as mentioned above, it is not possible for the wireless signal processing unit 250 to transmit wireless signals in parallel to each other using multiple links within the link set LS.

[0045] Furthermore, the wireless signal processing unit 250 converts the wireless signal received from AP10 via the antenna into a wireless frame by performing a predetermined demodulation operation. The predetermined demodulation operation is performed in the same manner as the predetermined demodulation operation in 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 link (channel) of the link set LS, and when it detects a wireless signal on any of the links, it inputs the 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 AP10 on any of the links, it identifies the link (channel) on which the wireless signal was detected. The MAC frame processing unit 240 then receives the MAC frame corresponding to the wireless signal, as well as information indicating which link the wireless signal was received on. The wireless signal processing unit 250 can also receive wireless signals in parallel with each other, that is, at the same timing, on multiple links within the link set LS. The wireless signal processing unit 250 may share an antenna across multiple links (multiple channels) of the link set LS, or it may have one antenna for each of the multiple links.

[0047] In the functional configuration shown in Figures 5 and 6, the link control unit 132 of AP10 and the link control unit 232 of terminal 20 cooperate with each other to control the establishment of the link between AP10 and terminal 20. In controlling the establishment of the link, the link control units 132 and 232, for example, respond to a connection request from terminal 20 to AP10 and execute association processing and authentication processing that follows the association processing. The link control units 132 and 232 control the state of the link established between AP10 and terminal 20. For example, when establishing a link set LS between AP10 and terminal 20, the link control units 132 and 232 can determine the association between TID and link (STA function of AP10).

[0048] Furthermore, in controlling the establishment of a link and controlling an established link, the link control unit 132 refers to the link management information 131, and the link control unit 232 also refers to the link management information 231. Each of the link management information 131 and 231 contains information about the link between AP10 and terminal 20, including, for example, the information shown in Figure 2.

[0049] Furthermore, if 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. During the setup of the link set LS, one of the wireless signal processing units 150, 160, or 170 (STA1 to STA3) of AP10 communicates with the wireless signal processing unit 250 (ESTA) of terminal 20. In one example, during the setup of the link set LS, the link control unit 232 causes terminal 20 to send a probe request to AP10, and the link control unit 132 causes AP10 to send a probe response to terminal 20 in response to the probe request. When terminal 20 receives the probe response, the link control unit 232 causes terminal 20 to send an association request about the link set LS to AP10.

[0050] When AP10 receives an association request, the link control unit 132 performs association processing for link set LS. At this time, based on the completion of association processing for two or more STA functions of AP10, the link control unit 132 recognizes that link set LS has been established between AP10 and terminal 20. Once the association processing is complete, the link control unit 132 updates the link management information 131. The link control unit 132 then causes AP10 to send a response to terminal 20 indicating that link set LS has been established. Based on the terminal 20 receiving the response indicating the establishment of link set LS, the link control unit 232 updates the link management information 231.

[0051] Furthermore, once the link set LS is established between AP10 and terminal 20 as described above, the communication management unit 130 of AP10 and the communication management unit 230 of 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 it may be set up based on a transmission request from terminal 20 for traffic requiring low latency. The rTWT function is set up, and the parameters related to the rTWT function are set based on the set parameters, and the rTWT-SP, which is the predetermined period described above, is set. Data exchange between AP10 and terminal 20 during rTWT-SP is performed using one of the multiple links that make up the set up link set LS.

[0052] During the setup of the rTWT function, parameters related to the rTWT function are set, such as the rTWT start time, rTWT period, and rTWT duration. The rTWT start time corresponds to the start time of rTWT-SP. The rTWT period corresponds to the period of rTWT-SP and is also called the "rTWT interval." The rTWT duration corresponds to the length of rTWT-SP. Note that 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 accordance with the transmission cycle from terminal 20 of traffic requiring low latency. The method for obtaining the transmission cycle from terminal 20 of traffic requiring low latency is not particularly limited. In one example, the data generation cycle set in the application that generates data requiring low latency is obtained at terminal 20, and parameters related to the rTWT function are set.

[0054] The beacon management unit 133 manages the information transmitted by AP10 as a beacon signal. For example, when the rTWT function is in use, the beacon management unit 133 generates a management frame containing 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 the setting values ​​for the parameters related to the rTWT function that were 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] Figure 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 AP10 according to this embodiment. In the example in Figure 7, the beacon frame includes the setting values ​​for the rTWT start time and rTWT duration as management information related to the rTWT function. In addition, in the example in Figure 7, a Quiet frame is included in the beacon frame to suppress data transmission to AP10 by terminals other than terminal 20. The Quiet frame indicates the transmission suppression period that suppresses data transmission to terminals other than terminal 20. The transmission suppression period for terminals other than terminal 20 is set to match the rTWT-SP of terminal 20. The communication management unit 130 causes AP10 to transmit the beacon signal, which is the beacon frame converted into a wireless signal, to terminal 20 and terminals other than terminal 20.

[0056] In the functional configuration shown in Figures 5 and 6, the beacon management unit 233 of terminal 20 manages the information contained in the beacon signal received from AP 10. For example, when the rTWT function is in use, the beacon management unit 233 receives the aforementioned beacon frame 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 obtains the setting values ​​for parameters related to the rTWT function and manages management information related to the rTWT function, including the setting values ​​for parameters related to the rTWT function.

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

[0058] The trigger generation unit 134 may, instead of generating a trigger frame, instruct the MAC frame processing unit 140 to generate a trigger frame, along with a time specification. When the rTWT function is used, a trigger signal, which is a trigger frame converted into a wireless signal, is transmitted from AP 10 to terminal 20. The trigger generation unit 134 generates a trigger frame or instructs AP 10 to generate a trigger frame when rTWT-SP starts, i.e., when the trigger signal is transmitted from AP 10 at the rTWT start time. Resource allocation for uplink data transmission from 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 by the wireless signal processing unit (one or more corresponding units of 150, 160, 170) that transmits the trigger signal.

[0059] Figure 8 is a block diagram showing an example of the functional configuration of the channel access function of AP10 according to this embodiment. In the example shown in Figure 8, each of the wireless signal processing units 150, 160, and 170 (STA1 to STA3) is provided with a channel access function. Each of the three channel access functions checks the status of one corresponding link in the link set LS. Here, Figure 8 shows the channel access function provided in the wireless signal processing unit 150, and the following description will mainly focus on the channel access function of the wireless signal processing unit 150. However, the channel access functions provided in each of the wireless signal processing units 160 and 170 perform the same processing as the channel access function of the wireless signal processing unit 150. In another example, instead of providing the channel access function in each of the wireless signal processing units 150, 160, and 170, the MAC frame processing unit 140 may be provided with the channel access function. In this case, the status of all links (all channels) of the link set LS is checked by a single channel access function of the MAC frame processing unit 140. As shown in Figure 8, the channel access function consists of, for example, a classification unit 151, queues 152A, 152B, 152C, 152D, carrier sense execution units 153A, 153B, 153C, 153D, and an internal collision management unit 154.

[0060] In the example shown in Figure 8, when a data frame is input to the channel access function as a MAC frame, the classification unit 151 classifies the input data frame into several access categories based on the TID contained 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 (one of 152A to 152D) corresponding to the classified access category. In the example shown in Figure 8, data frames with access categories VO, VI, BE, and BK are input into queues 152A, 152B, 152C, and 152D, respectively.

[0061] Each of the queues 152A to 152D buffers the input data frame. In the example in Figure 8, queues 152A, 152B, 152C, and 152D buffer data frames whose access categories are VO, VI, BE, and BK, respectively. Carrier sense execution units 153A, 153B, 153C, and 153D are provided corresponding to queues 152A, 152B, 152C, and 152D, respectively. Each of the carrier sense execution units 153A to 153D performs carrier sense based on CSMA / CA according to pre-set access parameters. Carrier sense execution units 153A, 153B, 153C, and 153D perform carrier sense with VO, VI, BE, and BK as the corresponding access categories, respectively.

[0062] Access parameters are set for each access category, for example, to prioritize radio signal transmission in the order of VO, VI, BE, BK. Access parameters used include, for example, CWmin, CWmax, AIFS (Arbitration Inter Frame Space), and TXOP (Transmission Opportunity) Limit. CWmin and CWmax represent the minimum and maximum values ​​of the contention window, respectively, which are parameters used to set the transmission waiting time for collision avoidance. AIFS represents a fixed transmission waiting time set for each access category. TXOPLimit represents the upper limit of the channel occupancy time (TXOP). Therefore, access categories with shorter values ​​for CWmin, CWmax, and AIFS are easier to acquire transmission rights for, and access categories with a larger value for TXOPLimit allow for a larger amount of data to be transmitted in a single transmission right.

[0063] Each of the carrier sense execution units 153A to 153D checks the status of one of the multiple links (channels) constituting the link set LS, corresponding to the wireless signal processing unit 150, using carrier sense. At this time, each of the carrier sense execution units 153A to 153D continues carrier sense 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. When the channel corresponding to the link whose status is being checked becomes idle and transmission rights are acquired on 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 causes the wireless signal converted from the data frame to be transmitted to the terminal 20 through the link on which transmission rights were acquired, that is, from the wireless signal processing unit 150.

[0064] The internal collision management unit 154 prevents data transmission collisions when multiple carrier sense execution units 153A to 153D acquire transmission rights on the link corresponding to the wireless signal processing unit 150. Specifically, the internal collision management unit 154 adjusts the transmission timing for each of the multiple data for which transmission rights have been acquired by STA1, and outputs the data to STA1 in order from the highest priority access category.

[0065] Furthermore, in the functional configuration shown in Figure 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, including the MAC frame processing unit 140, checks the status of each link in the link set LS by having the channel access functions of the wireless signal processing units 150, 160, and 170 perform carrier sensing, etc. If all links (channels) in the link set LS are busy, the management unit 110 continues to check the status until one or more links become idle. When one or more links (channels) in the link set LS become idle and transmission rights are acquired on one or more links, the management unit 110 has the wireless signal processing units (one or more corresponding units of 150, 160, and 170) corresponding to the links that acquired transmission rights send a trigger signal, which is a converted trigger frame TF, to the terminal 20.

[0066] As shown in Figure 8, in the channel access function of the wireless 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. For this reason, the process of acquiring transmission rights for trigger frame TF is performed with low latency compared to other traffic. When using the rTWT function, the channel access function acquires transmission rights for trigger frame TF when the trigger signal is transmitted at the start of rTWT-SP (rTWT start time), which is set as a predetermined period.

[0067] In one example, when using the rTWT function, if a trigger frame TF is input to the channel access function of the wireless signal processing unit 150, the channel access function treats the trigger frame TF as the data with the highest transmission priority and performs carrier sensing on the trigger frame TF. In this case, the channel access function acquires the right to transmit the trigger frame TF, for example, using the highest priority access category of EDCA (Enhanced Distributed Channel Access), or by a different priority transmission procedure than EDCA, and causes AP10 to transmit a trigger signal at the start of rTWT-SP. In another example, by temporarily stopping carrier sensing in the carrier sensing execution units 153A~153D, the transmission of VO, VI, BE, and BK data frames is temporarily stopped, and the transmission of the trigger frame TF is prioritized.

[0068] In the functional configuration shown in Figure 5, as described above, carrier sensing is performed by the channel access functions of the respective wireless signal processing units 150, 160, and 170 in response to inputs to the MAC frame processing unit 140, such as trigger frame TF. At this time, if multiple links (channels) constituting the link set LS are idle, the MAC frame processing unit 140 causes the trigger signal to be sent to the terminal 20 through each of the idle links. When multiple wireless signal processing units 150, 160, and 170 send trigger signals, the MAC frame processing unit 140 performs redundancy processing of the trigger frame TF, such as duplicating the trigger frame TF. Through redundancy processing, multiple trigger frame TFs common to each other are generated. The MAC frame processing unit 140 outputs one of the redundant trigger frame TFs to each of the idle links in the link set LS. Then, the trigger signal is sent to the terminal 20 as the first wireless signal that is transmitted redundantly across multiple links.

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

[0070] Furthermore, the multiple redundant trigger frame TFs do not need to be completely identical to each other. In one example, the redundancy process customizes each trigger frame TF to have information specific to each link that transmits the trigger signal. In another example, only the information common to multiple links is duplicated during the redundancy process. Then, using the information common to multiple links, trigger frame TFs are generated for each link that transmits the trigger signal, i.e., for the corresponding multiple STA1 to STA3. Moreover, the redundancy process is not limited to trigger frame TFs; for example, redundancy processing may be performed on beacon frames in the same manner.

[0071] In the functional configuration shown in Figures 5 and 6, when the wireless signal processing unit 250 of the terminal 20 receives a trigger signal from AP10, the MAC frame processing unit 240 inputs a trigger frame TF to the communication management unit 230. The communication management unit 230 recognizes from the input trigger frame TF that it has received an instruction from AP10 to transmit uplink data requiring low latency between rTWT-SP. The communication management unit 230 also recognizes from the trigger frame TF the resources allocated at rTWT-SP for transmitting uplink data requiring low latency.

[0072] Furthermore, if a trigger signal is transmitted through each of the multiple links of the link set LS, the wireless signal processing unit 250 of the terminal 20 may receive trigger signals from each of the multiple links (multiple channels). In this case, when the MAC frame processing unit 240 receives trigger frame TFs from each of the multiple links, it may perform a duplicate check to confirm whether there is any overlapping information between the multiple input trigger frame TFs. When performing a duplicate check, the MAC frame processing unit 240 discards the information from the other trigger frames, retaining only the information from one trigger frame TF for any overlapping information between the multiple trigger frame TFs.

[0073] When a trigger frame is input from the MAC frame processing unit 240, the communication management unit 230 determines from the links in link set LS which link to transmit uplink data requiring low latency in rTWT-SP. If the trigger signal from AP10 is received through only one link, the communication management unit 230 sets the link that received the trigger signal as the link to transmit uplink data. Then, the management unit 210, including the communication management unit 230, causes the radio signal processing unit 250 to transmit the radio signal for the uplink data requiring low latency through the link that received the trigger signal, and transmits wireless communication to AP10 using the link that received the trigger signal until the end of the rTWT-SP, which is a specified period.

[0074] If the communication management unit 230 receives a trigger signal from AP10 through each of the multiple links, it selects one of the multiple links that received the trigger signal as the link to transmit the uplink data. The management unit 210, including the communication management unit 230, then has the radio signal processing unit 250 transmit a radio signal for the uplink data requiring low latency as a second radio signal through the selected one of the multiple links that received the trigger signal. The communication management unit 230 then uses the selected one of the multiple links that received the trigger signal to communicate wirelessly with AP10 until the end of the specified period, rTWT-SP.

[0075] The method for selecting one of several links that have received a 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 allocated for transmitting uplink data in the trigger frame TF. The communication management unit 230 then selects the link corresponding to the resource identified as having 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 AP10 in 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 mentioned above, in rTWT-SP, the link used by terminal 20 for wireless communication with AP10 is set. Therefore, when using the rTWT function, one link is selected from the links that make up link set LS for terminal 20 to use for wireless communication with AP10 each time rTWT-SP is used. For this reason, a different link from the one used by terminal 20 for wireless communication with AP10 in the previous rTWT-SP may be selected as the link used by terminal 20 for wireless communication with AP10 in real time rTWT-SP.

[0077] The MAC frame processing unit 240 inputs the data frame of traffic requiring low latency, along with information indicating the link used for transmitting uplink data in rTWT-SP, to the wireless signal processing unit 250. The wireless signal processing unit 250 then transmits the wireless signal for the uplink data requiring low latency to AP10 through the link configured for transmitting uplink data. In one example, in response to the 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 the data frame requiring low latency to the wireless signal processing unit 250. The wireless signal processing unit 250 then converts the input data frame into a wireless signal and transmits it to AP10.

[0078] In another example, the MAC frame processing unit 240 obtains the rTWT start time, which is the start time of rTWT-SP, based on the information contained in the beacon frame mentioned above. Then, before the start of rTWT-SP, the MAC frame processing unit 240 inputs a data frame requiring low latency, along with time information indicating the rTWT start time, to the radio signal processing unit 250. Then, in response to receiving the trigger signal, the radio signal processing unit 250 converts the data frame input from the MAC frame processing unit 240 into a radio signal and transmits the converted radio signal to AP10.

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

[0080] The basic operation of the classification unit 251 is the same as that of the classification unit 151 of AP10, and the basic functions of queues 252A, 252B, 252C, and 252D are the same as those of queues 152A, 152B, 152C, and 152D of AP10, respectively. Furthermore, the basic operation of the carrier sense execution units 253A, 253B, 253C, and 253D is the same as those of the carrier sense execution units 153A, 153B, 153C, and 153D of AP10, respectively, and the basic operation of the internal collision management unit 254 is the same as that of the internal collision management unit 154 of AP10.

[0081] Here, the channel access function of the wireless signal processing unit 250 of terminal 20 receives a data frame with an access category of LL, which requires low latency. The channel access function transmits the uplink data with an access category of LL using the rTWT function. By using the rTWT function, uplink data with an access category of LL is preferentially transmitted from terminal 20 to AP10 during the rTWT-SP. In the rTWT-SP, where the transmission of uplink data with an access category of LL is prioritized, the transmission of uplink data other than access category LL is suppressed. In the example channel access function in Figure 9, the classification unit 241 inputs the data frame with an access category of LL to the carrier sense execution unit 253E without going through any of the queues 252A to 252D.

[0082] Furthermore, in the channel access function of terminal 20, in addition to carrier sense execution units 253A to 253D, carrier sense execution unit 253E also performs carrier sense according to pre-set access parameters. Carrier sense execution unit 253E performs carrier sense on uplink data with access category LL. In the channel access function of terminal 20, for example, the aforementioned access parameters are set so that the transmission of wireless signals is prioritized in the order of LL, VO, VI, BE, BK. Therefore, in the channel access function of terminal 20, especially in rTWT-SP, traffic with access category LL is processed with lower latency compared to other traffic, such as acquiring transmission rights. In one example, by temporarily stopping carrier sense of carrier sense execution units 253A to 253D, the transmission of traffic with access categories other than LL is temporarily stopped, and the transmission of traffic with access category LL is prioritized.

[0083] In the functional configurations shown in Figures 5 and 6, when the rTWT function is used, when a trigger signal (first radio signal) is transmitted to the terminal 20 from each of the multiple radio processing units (two or more of 150, 160, and 170) of AP10, the management unit 210 of terminal 20 causes the uplink data radio signal (second radio signal) to be transmitted to AP10 through one of the multiple links that received the trigger signal. Therefore, AP10 receives the uplink data radio signal transmitted from terminal 20 in response to the trigger signal on the corresponding link of the multiple links that transmitted the trigger signal. In other words, in AP10, one of the corresponding radio signal processing units 150, 160, and 170 (STA1 to STA3) receives the uplink data radio signal.

[0084] When AP10 receives uplink data corresponding to the trigger signal, the management unit 110 (communication management unit 130) uses one of the wireless signal processing units 150, 160, 170 (STA1~STA3) that received the uplink data (second wireless signal) to wirelessly communicate with terminal 20 until the end of the specified period rTWT-SP. Therefore, until the end of rTWT-SP, AP10 communicates wirelessly with terminal 20 only through the one link in link set LS that received the uplink data (second wireless signal).

[0085] For example, in rTWT-SP, AP10 may send downlink data to terminal 20 following uplink data received from terminal 20. In this case, MAC frame processing unit 140 inputs the data frame of the downlink data to the radio signal processing unit (one of the corresponding units 150, 160, or 170) that received the uplink data. Then, management unit 110 causes the radio signal processing unit (one of the corresponding units 150, 160, or 170) that received the uplink data to send the radio signal of the downlink data to terminal 20, that is, through the unit that received the uplink data in the link set LS.

[0086] Furthermore, if a trigger signal is transmitted through each of the multiple links, the management unit 110 (communication management unit 130) releases all but one of the multiple links that received the trigger signal from the terminal 20 from wireless communication with the terminal 20. In other words, wireless signal processing units (one or more corresponding units of 150, 160, and 170) that did not receive uplink data from the terminal 20 after transmitting the trigger signal are released from the resources for wireless communication with the terminal 20 in rTWT-SP. The management unit 110 notifies the wireless signal processing units (one or more corresponding units of 150, 160, and 170) that did not receive uplink data from the terminal 20 after transmitting the trigger signal that they are being released from the resources for wireless communication with the terminal 20.

[0087] In one example, a link (channel) released from the resources used for wireless communication to terminal 20 is newly allocated as a resource for AP10 to use for wireless communication to terminals other than terminal 20 until the end of rTWT-SP. In this case, the MAC frame processing unit 140 inputs, for example, a trigger frame indicating the new allocation of the link released from wireless communication to terminal 20 as a resource to the wireless signal processing unit (one or more of the corresponding units 150, 160, 170) released from wireless communication to terminal 20. As a result, the link (channel) released from wireless communication to terminal 20 is newly allocated as a resource for wireless communication to terminals other than terminal 20.

[0088] Furthermore, the management unit 110 does not necessarily have to make new resource allocations for links released from wireless communication to terminal 20. In one example, the wireless signal processing unit (one or more of the corresponding units 150, 160, and 170) released from wireless communication to terminal 20 determines the new resource allocation for the corresponding link (channel).

[0089] Furthermore, in rTWT-SP, the frequencies of the channels allocated to the link used for wireless communication to terminal 20 and the link released from wireless communication to terminal 20 may be close enough that power leakage occurs between them. In other words, in rTWT-SP, the link used for wireless communication to terminal 20 and the link released from wireless communication to terminal 20 may be in an NSTR (Non-Simultaneous Transmit and Receive) relationship with each other. In this case, it is preferable that the link (channel) released from wireless communication to terminal 20 be newly allocated as a resource so that it is not used for transmitting data from AP10 to terminals other than terminal 20.

[0090] Figure 10 is a flowchart illustrating an example of processing performed by the management unit 110 of the AP10 according to this embodiment when using the rTWT function. The processing in the example in Figure 10 is performed each time rTWT-SP is called to send uplink data requiring low latency to the terminal 20. Furthermore, when performing the processing in the example in Figure 10, it is assumed that immediately before rTWT-SP, one or more links in the link set LS are idle, and the AP10 is able to transmit a wireless signal to the terminal 20 through one or more links in the link set LS. When the processing in the example in Figure 10 is started, the management unit 110 determines whether there are multiple idle links (channels) in the link set LS (S301).

[0091] If only one link is idle (S301-No), the management unit 110 causes the aforementioned trigger signal to be sent to the terminal 20 through the idle link, that is, from the wireless signal processing unit corresponding to the idle link (one of the corresponding units 150, 160, or 170) (S302). The management unit 110 then determines whether or not it has received uplink data from the terminal 20 on the link from which the trigger signal was sent (S303). The process waits at S303 until it receives uplink data from the terminal 20.

[0092] Then, upon receiving uplink data from terminal 20 (S303-Yes), the management unit 110 wirelessly transmits data to terminal 20 via the link that received the uplink data (S304). Therefore, the management unit 110 transmits subsequent downlink data to terminal 20 via the link that received the uplink data. The management unit 110 then determines whether rTWT-SP has finished (S305). Unless rTWT-SP has finished (S305-No), the process returns to S304, and the management unit 110 wirelessly transmits data to terminal 20 via the link that received the uplink data.

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

[0094] Then, when uplink data from terminal 20 is received on one of the multiple links that sent the trigger signal (S312-Yes), the management unit 110 wirelessly transmits data to terminal 20 through the link that received the uplink data (S313). Therefore, the management unit 110 transmits subsequent downlink data to terminal 20 through the one of the multiple links that received the uplink data. The management unit 110 also releases all but the one link that received the uplink data from wireless communication with terminal 20 (S314). At this time, the links released from wireless communication with terminal 20 may be allocated as resources used for wireless communication between terminals other than terminal 20 and AP10.

[0095] The management unit 110 then determines whether rTWT-SP has finished (S315). Unless rTWT-SP has finished (S315-No), the process returns to S313. For this reason, until rTWT-SP finishes, the management unit 110 transmits wireless communication to terminal 20 through the link that received the uplink data, and releases all links except the link that received the uplink data from wireless communication to terminal 20.

[0096] In one example, the trigger signal is sent to terminal 20 through each of the multiple links of link set LS at the start of rTWT-SP, and the trigger signal is never sent through only one link. In this case, processing S302 to S305 is not performed, and processing S311 to S315 is performed sequentially each time rTWT-SP is performed.

[0097] Figure 11 is a flowchart showing an example of processing performed by the management unit 210 of the terminal 20 according to this embodiment when using the rTWT function. The processing in the example in Figure 11 is performed each time rTWT-SP is called in order to send uplink data requiring low latency to AP10. When the processing in the example in Figure 11 is performed, it is assumed that a trigger signal has been sent from AP10 to terminal 20 by the processing shown in the example in Figure 10, etc. When the processing in the example in Figure 11 is started, the management unit 210 determines whether or not it has received a trigger signal from AP10 on any link (S321). The processing waits at S321 until a trigger signal is received on any link. When a trigger signal is received (S321-Yes), the management unit 210 determines whether or not it has received a trigger signal on any of the links in the link set LS (S322).

[0098] If the trigger signal is received on only one link (S322-No), the management unit 210 will wirelessly transmit to AP10 through the link that received the trigger signal (S323). Therefore, the management unit 210 will transmit uplink data and other data requiring low latency to AP10 through the link that received the trigger signal. The management unit 210 then determines whether rTWT-SP has finished (S324). Unless rTWT-SP has finished (S324-No), the process returns to S323, and the management unit 210 will wirelessly transmit to AP10 through the link that received the trigger signal.

[0099] Furthermore, if trigger signals are received on multiple links in S322 (S322-Yes), the management unit 210 selects one link from those that received the trigger signals to transmit uplink data requiring low latency (S331). In this case, one link is selected in the same manner as described above. The management unit 210 then transmits wireless communication to AP10 through the selected link (S332). Therefore, the management unit 210 transmits uplink data requiring low latency to AP10 through one of the links that received the trigger signals. The management unit 210 then determines whether rTWT-SP has finished (S333). Unless rTWT-SP has finished (S333-No), the process returns to S332, and the management unit 210 transmits wireless communication to AP10 through the selected link.

[0100] Figure 12 is a schematic diagram showing the temporal changes in the communication state through the link set between AP10 and terminal 20 in a communication system 1 according to an embodiment. In Figure 12, the two STA functions STA1, STA2, and STA3 of AP10 are assumed to form links with link IDs "STA1", "STA2", and "STA3" respectively in the link set LS, with the ESTA function of terminal 20. In an example in Figure 12, the management unit 110 of AP10 causes trigger signals to be sent from AP10 to terminal 20 through each of the three links "STA1", "STA2", and "STA3" at the start of rTWT-SP.

[0101] The management unit 210 then selects the "STA1" link from the three links that received the trigger signal as the link to transmit uplink data in rTWT-SP. The management unit 210 then transmits the uplink data through the selected "STA1" link. When AP10 receives the uplink data on the "STA1" link, the management unit 210 transmits the subsequent downlink data to terminal 20 through the "STA1" link. Therefore, until the end of rTWT-SP, AP10 and terminal communicate wirelessly with each other through the "STA1" link. In the example shown in Figure 12, the management unit 110 also releases the "STA2" and "STA3" links, which were not selected as the link to transmit uplink data, from wireless communication with terminal 20.

[0102] As described above, in this embodiment, the management unit 110 of AP10 transmits a trigger signal, which is the first wireless signal, to terminal 20 from each of the multiple wireless signal processing units (two or more corresponding units of 150, 160, and 170). Then, the management unit 210 of terminal 20 transmits a wireless signal of uplink data as the second wireless signal to AP10 through one of the multiple links that received the trigger signal. Then, until the end of the specified period rTWT-SP, AP10 and terminal 20 communicate wirelessly with each other through the single link from which terminal 20 transmitted the uplink data.

[0103] As described above, wireless communication in rTWT-SP is performed in this manner. Therefore, even if a malfunction occurs in the wireless communication between AP10 and terminal 20 through one of the multiple links, the management unit 210 can transmit uplink data to AP10 through another of the multiple links that received the trigger signal. For example, if a trigger signal is transmitted to terminal 20 through each of the three links, “STA1”, “STA2”, and “STA3”, even if a malfunction occurs in the wireless communication through the “STA1” link, either “STA2”, or “STA3”, can be selected as the link to transmit uplink data.

[0104] Therefore, in this embodiment, even when transmitting uplink data to the AP from a terminal with only one STA function, such as terminal 20, redundancy is properly implemented. In other words, even for terminals that cannot transmit data in parallel on multiple links, it is possible to ensure reliability in transmitting uplink data to AP10 and ensure reliability in data exchange between terminal 20 and AP10.

[0105] Furthermore, in this embodiment, links (channels) that were not selected as links for transmitting uplink data among the links used to transmit the trigger signal are released from wireless communication to terminal 20 by the management unit 110. Therefore, links (channels) that are not used to transmit uplink data in rTWT-SP can be effectively utilized, for example, by using them for wireless communication between terminals other than terminal 20 and AP10.

[0106] In the modified configuration shown below, prior to the start of rTWT-SP, the management unit 210 selects the link in the link set LS that will be used for transmitting uplink data in rTWT-SP. In this modified configuration, when using the rTWT function, before the start of rTWT-SP, which is a specified period, the management unit 110 of AP10 transmits an RTS (Request To Send) signal as the first radio signal. At this time, the RTS signal is transmitted to terminal 20 through each of the multiple links in the link set LS and is transmitted in parallel (synchronously) from multiple wireless communication units (two or more corresponding units of 150, 160, and 170) to each other. The RTS signal notifies terminals 20 other than terminal 20 that AP10 is planning to communicate wirelessly with terminal 20 in rTWT-SP.

[0107] In this modified example, when terminal 20 receives an RTS signal through each of the multiple links, the management unit 210 selects one of the multiple links that received the RTS signal. Then, before rTWT-SP starts, the management unit 210 has AP10 transmit a CTS (Clear To Send) signal as a second wireless signal through the selected link. At this time, CTS signals are not transmitted from terminal 20 to AP10 on any link other than the one that transmitted the CTS signal among the links used to transmit the RTS signal. The CTS signal notifies terminals 20 other than terminal 20 that the link (channel) that transmitted the CTS signal will be used for wireless communication between AP10 and terminal 20 in rTWT-SP.

[0108] In this modified example, AP10 receives the CTS signal on one of the links that transmitted the RTS signal, that is, on one of the corresponding wireless signal processing units 150, 160, and 170. Then, at the start of rTWT-SP, the management unit 110 causes the aforementioned trigger signal to be transmitted to terminal 20 through the link that received the CTS signal among the links that transmitted the RTS signal. As a result, terminal 20 receives the trigger signal through the link that transmitted the CTS signal. During the specified period of rTWT-SP, AP10 and terminal 20 communicate wirelessly with each other through the link used to transmit the CTS signal. Furthermore, the management unit 110 releases all links except the one that received the CTS signal among the links that transmitted the RTS signal from wireless communication with terminal 20 until the end of rTWT-SP.

[0109] Figure 13 is a flowchart showing an example of processing performed by the management unit 110 of AP10 in a modified configuration when using the rTWT function. The processing in the example in Figure 13 is performed to send uplink data requiring low latency to terminal 20 each time rTWT-SP is called. Furthermore, when performing the processing in the example in Figure 13, it is assumed that immediately before rTWT-SP, each of the multiple links in link set LS is capable of transmitting a wireless signal from AP10 to terminal 20. When the processing in the example in Figure 13 is started, the management unit 110 causes each of the multiple links in link set LS to transmit an RTS signal as the first wireless signal to terminal 20 (S341). The management unit 110 then determines whether or not it has received a CTS signal from terminal 20 on any of the multiple links that transmitted the RTS signal (S342). The process waits at S342 until one of the multiple links receives a CTS signal from terminal 20.

[0110] Then, when the management unit 110 receives a CTS signal from terminal 20 on one of the multiple links that transmitted the RTS signal (S342-Yes), the management unit 110 waits until the rTWT start time (when rTWT-SP starts) (S343-No). Then, when the rTWT start time arrives (S343-Yes), the management unit 110 causes terminal 20 to transmit a trigger signal through the link that received the CTS signal (S344). The management unit 110 then transmits wireless communication to terminal 20 through the link that received the CTS signal (S345). The management unit 110 also releases all but the one link that received the CTS signal from wireless communication to terminal 20 (S346).

[0111] The management unit 110 then determines whether rTWT-SP has finished (S347). Unless rTWT-SP has finished (S347-No), the process returns to S345. For this reason, until rTWT-SP finishes, the management unit 110 allows wireless communication to terminal 20 through the link that received the CTS signal, and releases all links except the link that received the CTS signal from wireless communication to terminal 20.

[0112] Figure 14 is a flowchart showing an example of processing performed by the management unit 210 of terminal 20 when using the rTWT function, as shown in a modified version of Figure 13. The processing in the example in Figure 14 is performed each time rTWT-SP is used to send uplink data requiring low latency to AP10. Furthermore, when performing the processing in the example in Figure 14, it is assumed that the RTS signal has been sent from AP10 to terminal 20 through each of the multiple links by the processing shown in the example in Figure 13. When the processing in the example in Figure 14 is started, the management unit 210 determines whether or not the RTS signal sent from AP10 has been received on each of the multiple links (S351). The process waits at S351 until all the links have received the RTS signal.

[0113] If the RTS signal is received on 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 has the AP10 transmit a CTS signal through the selected link (S353). The management unit 210 then waits until it receives a trigger signal from the AP10 on the selected link that transmitted the CTS signal (S354-No).

[0114] When the trigger signal is received on the link that transmitted the CTS signal (S354-Yes), the management unit 210 transmits wireless communication to AP10 through the selected link that received the trigger signal (S355). Unless rTWT-SP has finished (S356-No), the process returns to S355, and the management unit 210 transmits wireless communication to AP10 through the selected link.

[0115] Figure 15 is a schematic diagram showing the temporal changes in the communication state through the link set between AP10 and terminal 20 in a modified communication system 1. In the example shown in Figure 15, the management unit 110 of AP10 causes the AP10 to send an RTS signal to terminal 20 through each of the three links, “STA1”, “STA2”, and “STA3”, before rTWT-SP is started. The management unit 210 then selects the “STA1” link from the three links that received the RTS signal as the link to send uplink data in rTWT-SP. The management unit 210 then causes the CTS signal to be sent through the selected “STA1” link.

[0116] Then, when AP10 receives the CTS signal on the "STA1" link, the management unit 110 causes the terminal 20 to send a trigger signal through the "STA1" link at the start of rTWT-SP. As a result, AP10 and the terminal communicate wirelessly with each other through the "STA1" link from the start to the end of rTWT-SP. Therefore, in rTWT-SP, uplink data is transmitted to AP10 through the "STA1" link. Also, in the example shown in Figure 15, the management unit 110 releases the "STA2" and "STA3" links, which were not selected as links for transmitting uplink data, from wireless communication with the terminal 20.

[0117] The modified configuration also produces the same functions and effects as the embodiments described above. That is, even in the modified configuration, in a terminal like terminal 20 that has only one STA function, it is possible to ensure the reliability of uplink data transmission to AP10 and the reliability of data exchange between terminal 20 and AP10. Furthermore, in the modified configuration, links (channels) that are not used for uplink data transmission in rTWT-SP can be effectively utilized.

[0118] Furthermore, in the modified version, the link used for transmitting uplink data from terminal 20 to AP10 during the specified period of rTWT-SP is determined before the trigger signal is sent to terminal 20. Therefore, there is no need to allocate a new resource for the link (channel) released from wireless communication to terminal 20 during rTWT-SP after the start of rTWT-SP, i.e., after the trigger signal is sent.

[0119] In the embodiments and modifications described above, the AP10 communicates wirelessly with the terminal 20 using three STA functions, and the link set LS between the AP10 and the terminal 20 consists of three links. However, the invention is not limited to this. In the embodiments, if the AP10 communicates wirelessly with the terminal 20 using multiple STA functions, and the link set LS between the AP10 and the terminal 20 consists of multiple links, the functions described above can be applied and the processes described above can be executed.

[0120] Furthermore, the processing described in the embodiments and modifications above can be stored as a program that can be executed by a computer processor. The program that performs the aforementioned processing can also be stored and distributed on a storage medium such as a magnetic disk, optical disk, or semiconductor memory. The processor can then read the program stored on the external storage medium and execute the processing described in the embodiments, etc., by having its operation controlled by the read program.

[0121] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways during implementation without departing from its essence. Furthermore, each embodiment may be combined as appropriate, and in that case, the combined effects can be obtained. Moreover, the above embodiments include various inventions, and various inventions can be extracted by selecting combinations from the multiple constituent elements disclosed. For example, if the problem can be solved and effects obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, then the configuration with these deleted constituent elements can be extracted as an invention. [Explanation of symbols]

[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 2 hours… storage 100,200...LLC Processing Unit 110,210… Management Department 120,220…Data Processing Unit 130,230… Communications Management Department 131,231… Link management information 132,232… Link Control Unit 133,233… Beacon Management Department 134...Trigger generation unit 140,240…MAC frame processing unit 150, 160, 170, 250… Wireless signal processing unit 151,251...Classification section 152A~152D, 252A~252D... Queue 153A~153D, 253A~253E…Career Sense Execution Department 154,254…Internal conflict management department 280...Application execution unit

Claims

1. Multiple wireless 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, wherein, based on the fact that one of the plurality of wireless signal processing units has received a second wireless signal transmitted from the terminal in response to the transmission of the first wireless signal, the management unit causes the one of the plurality of wireless signal processing units that received the second wireless signal to transmit wireless communication to the terminal until the end of a specified period, An access point equipped with the following features.

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

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

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

5. Wireless signal processing unit, A management unit that uses the wireless signal processing unit to establish multiple links with an access point, and, based on the wireless signal processing unit receiving a first wireless signal transmitted from the access point through each of the multiple links, causes the wireless signal processing unit to transmit a second wireless signal through one of the multiple links, and from the time the second wireless signal is transmitted until the end of a specified period, the management unit uses the link that transmitted the second wireless signal to wirelessly transmit to the access point. A terminal equipped with the following.

6. The wireless signal processing unit receives, as the first wireless signal, a trigger signal transmitted from the access point through each of the plurality of links at the start of the specified period, which instructs the 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 the uplink data as the second wireless signal to the access point through one of the plurality of links. The terminal according to claim 5.

7. The wireless signal processing unit receives the RTS signals transmitted from the access point through each of the plurality of links as the first wireless signal before the specified period begins. Before the specified period begins, the management unit, in response to the wireless signal processing unit receiving the RTS signal, causes the CTS signal to be transmitted as the second wireless signal from the wireless signal processing unit to the access point through one of the plurality of links. The wireless signal processing unit receives a trigger signal transmitted from the access point at the start of the specified period, which instructs the transmission of uplink data, through one of the multiple links that transmitted the CTS signal. The terminal according to claim 5.

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