Base station and wireless terminal device

Abstract

A base station of an embodiment includes a first wireless signal processing unit and a link management unit. The link management unit establishes a link with a first wireless terminal device using the first wireless signal processing unit. The link management unit causes the first wireless signal processing unit to emit a wireless signal including a trigger frame in a first period. The link management unit receives first uplink data from the first wireless terminal device and first queue delay time information for the first uplink data in response to a first trigger frame included in a set of trigger frames emitted in the first period, and when the first queue delay time information has exceeded a first threshold, the link management unit changes the period in which the first radio signal processing unit is caused to emit a wireless signal including the trigger frame from the first period to a second period that is shorter than the first period.

Description

[Technical Field]

[0001] The embodiments relate to a base station and a wireless terminal device. [Background technology]

[0002] 2. Description of the Related Art A wireless LAN (Local Area Network) is known as an information communication system that wirelessly connects a base station and a wireless terminal device. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] IEEE Std 802.11TM-2020, “10.47 Target wake time (TWT)”, published 26 February 2021 Summary of the Invention [Problem to be solved by the invention]

[0004] The challenge is to reduce queuing delays for low-latency data transmitted on the uplink. [Means for solving the problem]

[0005] In an embodiment, a base station includes a first radio signal processing unit and a link management unit. The link management unit establishes a link with a first wireless terminal device using the first radio signal processing unit. The link management unit causes the first radio signal processing unit to emit a radio signal including a trigger frame at a first period. The link management unit receives, from the first wireless terminal device, first uplink data and information on a first queuing delay time of the first uplink data in response to a first trigger frame included in a set of trigger frames emitted at the first period, and, if the first queuing delay time exceeds a first threshold, changes the period at which the first radio signal processing unit emits the radio signal including the trigger frame from the first period to a second period shorter than the first period. [Effects of the Invention]

[0006] The base station according to the embodiment can suppress delays in data transmitted on the uplink. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a conceptual diagram showing an example of the overall configuration of an information communication system according to the first embodiment. [Figure 2] FIG. 2 is a conceptual diagram showing an example of frequency bands used in wireless communication in the information communication system according to the first embodiment. [Figure 3] FIG. 3 is a block diagram showing an example of a hardware configuration of a base station included in the information communication system according to the first embodiment. [Figure 4] FIG. 4 is a block diagram showing an example of a hardware configuration of a wireless terminal device included in the information communication system according to the first embodiment. [Figure 5] FIG. 5 is a block diagram showing an example of a functional configuration of a base station included in the information communication system according to the first embodiment. [Figure 6] FIG. 6 is a block diagram showing an example of the functional configuration of the MAC frame processing unit of the base station included in the information communication system according to the first embodiment. [Figure 7] FIG. 7 is a block diagram showing an example of the functional configuration of a wireless terminal device included in the information communication system according to the first embodiment. [Figure 8] FIG. 8 is a block diagram showing an example of the functional configuration of a MAC frame processing unit of the base station included in the information communication system according to the first embodiment. [Figure 9] FIG. 9 is a sequence diagram showing an outline of a method for transmitting uplink data when a TWT (Target Wake Time) function is used in the information communication system according to the first embodiment. [Figure 10] FIG. 10 is a conceptual diagram showing an example of the format of a trigger frame transmitted during a TWT service period in the information communication system according to the first embodiment. [Figure 11] FIG. 11 is a conceptual diagram showing an example of a format of a beacon signal including a TWT setting used in the information communication system according to the first embodiment. [Figure 12] FIG. 12 is a flowchart showing an example of a method for updating the TWT setting in the information communication system according to the first embodiment. [Figure 13] FIG. 13 is a sequence diagram showing a specific example of a method for updating the TWT setting in the information communication system according to the first embodiment. [Figure 14] FIG. 14 is a sequence diagram showing a specific example of a method for updating the TWT setting in an information communication system according to a modified example of the first embodiment. [Figure 15] FIG. 15 is a flowchart showing an example of a method for updating the TWT setting in the information communication system according to the second embodiment. [Figure 16] FIG. 16 is a table showing an example of changing the TWT setting in the information communication system according to the second embodiment. [Figure 17] FIG. 17 is a timing chart showing an example of a method of transmitting uplink data before and after changing the TWT setting in the information communication system according to the second embodiment. [Figure 18]FIG. 18 is a flowchart showing an example of a method for updating the TWT setting in the information communication system according to the third embodiment. [Figure 19] FIG. 19 is a table showing an example of changing the TWT setting in the information communication system according to the third embodiment. [Figure 20] FIG. 20 is a timing chart showing an example of a method of transmitting uplink data before and after changing the TWT setting in the information communication system according to the third embodiment. [Figure 21] FIG. 21 is a table showing an example of a link state between a base station and a wireless terminal device included in an information communication system according to the fourth embodiment. [Figure 22] FIG. 22 is a flowchart showing an example of a multi-link setup method in the information communication system according to the fourth embodiment. [Figure 23] FIG. 23 is a table showing an example of TWT settings in the information communication system according to the fourth embodiment. [Figure 24] FIG. 24 is a table showing an example of channel allocation for each TWT group in the information communication system according to the fourth embodiment. [Figure 25] FIG. 25 is a timing chart showing an example of a method for transmitting uplink data based on TWT setting in the information communication system according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] An information communication system according to an embodiment will be described below with reference to the drawings. Each embodiment illustrates an apparatus or method for embodying the technical idea of ​​the invention. The drawings are schematic or conceptual. In the following description, components having substantially the same functions and configurations are assigned the same reference numerals. Numbers following letters constituting a reference numeral are used to distinguish between elements that are referred to by reference numerals containing the same letters and that have similar configurations. When there is no need to distinguish between elements indicated by reference numerals containing the same letters, these elements are referred to by reference numerals containing only letters.

[0009] <1> First embodiment The information communication system 1 according to the first embodiment will be described below.

[0010] <1-1> Configuration <1-1-1> Overall structure Fig. 1 is a conceptual diagram showing an example of the overall configuration of an information communication system 1 according to the first embodiment. As shown in Fig. 1, the information communication system 1 includes, for example, an access point AP, at least one wireless terminal apparatus WTA, and a server SV.

[0011] The base station AP is a wireless LAN access point or a wireless LAN router. The base station AP is configured to be connectable to a network NW. The base station AP is configured to be able to wirelessly connect to one or more wireless terminal devices WTA using one or more types of bands.

[0012] The wireless terminal device WTA is a wireless terminal such as a smartphone or tablet computer. The wireless terminal device WTA is configured to be able to communicate with the base station AP with which a link has been established. The wireless terminal device WTA may also be an electronic device such as a desktop computer or laptop computer. A terminal identifier AID is assigned to the wireless terminal device WTA. The base station AP can identify multiple wireless terminal devices WTA that are wirelessly connected by the terminal identifier AID. In this example, a wireless terminal device WTA1 with AID=#1 and a wireless terminal device WTA2 with AID=#2 are connected to the base station AP.

[0013] The server SV is a computer configured to be connectable to the network NW. The server SV is configured to be able to communicate with the base station AP via the network NW. The server SV stores, for example, content data intended for the wireless terminal device WTA. The server SV can transmit and receive data to and from the wireless terminal device WTA via the base station AP. Communication between the base station AP and the server SV may use wireless communication, or a combination of wireless communication and wired communication.

[0014] Wireless communication between the base station AP and the wireless terminal device WTA complies with the IEEE 802.11 standard. The IEEE 802.11 standard defines Layer 1 and Layer 2 MAC sublayer of the OSI (Open Systems Interconnection) reference model. In the OSI reference model, 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). Layer 2 (Data Link Layer) includes a Logical Link Control (LLC) sublayer and a Media Access Control (MAC) sublayer. An overview of the LLC sublayer and the MAC sublayer will be provided later.

[0015] Furthermore, the base station AP may use a TWT (Target Wake Time) function for communication with the wireless terminal device WTA. When the TWT function is used, a fixed cycle is set between the base station AP and the wireless terminal device WTA, and the base station AP provides the wireless terminal device WTA with a transmission opportunity at each fixed cycle. The wireless terminal device WTA may reduce power consumption by setting a power-saving state for periods other than the fixed cycle set by the TWT function. In the TWT function, the period during which the base station AP provides the wireless terminal device WTA with a transmission opportunity (hereinafter also referred to as a TWT service period) may be set short when priority is given to reducing power consumption, and set long when priority is given to improving latency. Furthermore, the wireless terminal device WTA may improve the latency of low-latency data by preferentially transmitting data requiring low latency (hereinafter referred to as low-latency data) during the TWT service period. The TWT function in the first embodiment executes processing to further reduce the delay in transmission of uplink data from the wireless terminal device WTA to the base station AP. Detailed operation of the TWT function in the embodiment will be described later.

[0016] (Frequency bands used by base stations AP and wireless terminals WTA) FIG. 2 is a conceptual diagram showing an example of frequency bands used in wireless communication in the information communication system 1 according to the first embodiment. As shown in FIG. 2, wireless communication between the base station AP and the wireless terminal device WTA uses, for example, the 2.4 GHz band, the 5 GHz band, and the 6 GHz band. Each frequency band includes multiple channels. FIG. 2 illustrates a case where each of the 2.4 GHz band, the 5 GHz band, and the 6 GHz band includes three channels CH1, CH2, and CH3. Note that frequency bands other than the 2.4 GHz band, the 5 GHz band, and the 6 GHz band may also be used for wireless communication. It is sufficient that at least one channel CH is assigned to each frequency band.

[0017] <1-1-2> Hardware configuration The hardware configurations of the base station AP and the wireless terminal WTA will be described below.

[0018] (Base station AP hardware configuration) Fig. 3 is a block diagram showing an example of a hardware configuration of a base station AP included in the information communication system 1 according to the first embodiment. As shown in Fig. 3, the base station AP includes, for example, a CPU (Central Processing Unit) 10, a ROM (Read Only Memory) 11, a RAM (Random Access Memory) 12, a wireless communication module 13, and a wired communication module 14.

[0019] The CPU 10 is an integrated circuit capable of executing various programs and controls the overall operation of the base station AP. The ROM 11 is a non-volatile semiconductor memory that stores programs and control data for controlling the base station AP. The RAM 12 is, for example, a volatile semiconductor memory that is used as a work area for the CPU 10. The wireless communication module 13 is a circuit used to transmit and receive data via wireless signals and is configured to be connectable to an antenna. The wireless communication module 13 may also include multiple communication modules corresponding to multiple frequency bands. The wired communication module 14 is a circuit used to transmit and receive data via wired signals and is configured to be connectable to a network NW. The base station AP may have other hardware configurations. For example, when the base station AP is wirelessly connected to the network NW, the wired communication module 14 may be omitted from the base station AP.

[0020] (Hardware configuration of wireless terminal equipment WTA) 4 is a block diagram showing an example of the hardware configuration of the wireless terminal device WTA included in the information communication system 1 according to the first embodiment. As shown in FIG. 4, the wireless terminal device WTA includes, for example, a CPU 20, a ROM 21, a RAM 22, a wireless communication module 23, a display 24, and a storage 25.

[0021] The CPU 20 is an integrated circuit capable of executing various programs and controls the overall operation of the wireless terminal device WTA. The ROM 21 is a non-volatile semiconductor memory that stores programs and control data for controlling the wireless terminal device WTA. The RAM 22 is, for example, a volatile semiconductor memory that serves as a work area for the CPU 20. The wireless communication module 23 is a circuit used to transmit and receive data via wireless signals and is configured to be connectable to an antenna. The wireless communication module 23 may also include, for example, multiple communication modules corresponding to multiple frequency bands. The display 24 displays, for example, a GUI (Graphical User Interface) corresponding to application software. The display 24 may also function as an input interface for the wireless terminal device WTA. The storage 25 is a non-volatile storage device that stores, for example, system software for the wireless terminal device WTA. The wireless terminal device WTA may have other hardware configurations. For example, if the wireless terminal device WTA is an IoT (Internet of Things) terminal or the like, the display 24 may be omitted from the wireless terminal device WTA.

[0022] <1-1-3> Functional configuration The functional configurations of the base station AP and the wireless terminal WTA will be described below.

[0023] (Functional configuration of base station AP) Fig. 5 is a block diagram showing an example of the functional configuration of a base station AP included in the information communication system 1 according to the first embodiment. As shown in Fig. 5, the base station AP includes, for example, an LLC processing unit 110, a data processing unit 120, a management unit 130, a MAC frame processing unit 140, and a wireless signal processing unit 150. The LLC processing unit 110 can be realized, for example, by a combination of a CPU 10 and a wired communication module 14. The processing of each of the data processing unit 120, the management unit 130, the MAC frame processing unit 140, and the wireless signal processing unit 150 can be realized, for example, by a wireless communication module 13, or a combination of the CPU 10 and the wireless communication module 13.

[0024] The LLC processing unit 110 performs, for example, processing of the LLC sublayer of layer 2 and processing of layers 3 to 7 on input data. The data processing unit 120, management unit 130, and MAC frame processing unit 140 perform processing of the MAC sublayer of layer 2 on input data. The radio signal processing unit 150 performs processing of layer 1 on input data. Hereinafter, the set of the data processing unit 120, management unit 130, and MAC frame processing unit 140 provided in the base station AP will also be referred to as the "link management unit MLD of the base station AP."

[0025] The following describes in detail each of the functional components of the base station AP.

[0026] The LLC processing unit 110 receives data from the server SV, for example, via the network NW. Then, the LLC processing unit 110 generates an LLC packet by adding a DSAP (Destination Service Access Point) header, an SSAP (Source Service Access Point) header, and the like to the received data. Then, the LLC processing unit 110 inputs the generated LLC packet to the data processing unit 120. The LLC processing unit 110 also receives the LLC packet from the data processing unit 120 and extracts data from the received LLC packet. Then, the LLC processing unit 110 transmits the extracted data to the server SV via the network NW.

[0027] The data processing unit 120 generates a MAC frame by adding a MAC header to the LLC packet input from the LLC processing unit 110. 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 110. Hereinafter, a MAC frame containing data will also be referred to as a "data frame."

[0028] The management unit 130 manages the state of the link between the base station AP and the wireless terminal device WTA. Information relating to link control, management, and the like can be exchanged between the management unit 130 and the MAC frame processing unit 140. The management unit 130 can also cause the MAC frame processing unit 140 to execute instructions. The management unit 130 includes, for example, link management information 131, an association processing unit 132, an authentication processing unit 133, a link control unit 134, a beacon management unit 135, a trigger generation unit 136, and a delay determination unit 137.

[0029] The link management information 131 is a table containing information about links between the base station AP and the wireless terminal WTA wirelessly connected thereto. The link management information 131 can store settings related to the TWT function.

[0030] When an association request is received from the wireless terminal WTA, the association processing unit 132 executes a protocol related to association.

[0031] The authentication processing unit 133 executes a protocol related to authentication subsequent to association. Hereinafter, a MAC frame including information related to control of association, authentication, etc. will also be referred to as a "management frame."

[0032] The link control unit 134 controls the link state of the STA function of the wirelessly connected wireless terminal device WTA for each AID. The STA function corresponds to the wireless signal processing unit provided in each of the base station AP and the wireless terminal device WTA. The STA function can use one or more channels. In the following description, it is assumed that the STA function uses one channel. One link is formed by a pair of the STA function of the base station AP and the STA function of the wireless terminal device WTA.

[0033] The beacon management unit 135 manages information transmitted by the base station AP as a beacon signal. The beacon management unit 135 generates, for example, a MAC frame including management information and inputs the MAC frame to the MAC frame processing unit 140. The management information includes control values ​​used in the TWT function described later. A beacon is a type of management frame.

[0034] The trigger generation unit 136 generates a MAC frame including trigger information and inputs it to the MAC frame processing unit 140. The trigger information includes information indicating resources (frequency, transmission timing, and period) for transmission to the wireless terminal apparatus WTA that transmits uplink data when using the TWT function. Hereinafter, a MAC frame including trigger information will be referred to as a "trigger frame."

[0035] The delay determination unit 137 determines whether the delay time in the transmission of the traffic exceeds a predetermined threshold based on the delay information included in the MAC frame received by the base station AP, and can notify the link control unit 134 or the like of the determination result.

[0036] The MAC frame processing unit 140 receives MAC frames from the data processing unit 120 or the management unit 130, and temporarily stores (buffers) the received MAC frames. The MAC frame processing unit 140 then performs carrier sensing. Carrier sensing is a process for checking the status of the channel. If the channel is busy, the MAC frame processing unit 140 continues carrier sensing. If the channel is idle, the MAC frame processing unit 140 inputs the MAC frame to the radio signal processing unit 150. The MAC frame processing unit 140 also receives MAC frames from the radio signal processing unit 150, and inputs the MAC frame to the data processing unit 120 or the management unit 130 depending on the type of MAC frame. Specifically, if the MAC frame is a data frame, the MAC frame processing unit 140 inputs the MAC frame to the data processing unit 120, and if the MAC frame is a management frame, the MAC frame processing unit 140 inputs the MAC frame to the management unit 130.

[0037] The radio signal processing unit 150 generates a radio frame by adding a preamble, a PHY (physical layer) header, and the like to the data input from the MAC frame processing unit 140. The radio signal processing unit 150 then performs a predetermined modulation operation on the 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. The radio signal processing unit 150 also receives a radio signal from the wireless terminal device (WTA) via the antenna, and performs a predetermined demodulation operation on the received radio signal to obtain a radio frame. The predetermined demodulation operation includes, for example, frequency conversion, OFDM demodulation, fast Fourier transform (FFT), subcarrier demodulation, deinterleaving, and Viterbi decoding. Then, radio signal processing unit 150 extracts a MAC frame from the radio frame and inputs the extracted MAC frame to MAC frame processing unit 140. Hereinafter, radio signal processing unit 150 will also be referred to as an STA (or STA function) of the base station AP. Note that a base station AP may include multiple radio signal processing units.

[0038] (Functional configuration of the MAC frame processing unit 140 of the base station AP) Fig. 6 is a block diagram showing an example of the functional configuration of MAC frame processing unit 140 of base station AP included in information communication system 1 according to the first embodiment. Fig. 6 shows details of the channel access function of MAC frame processing unit 140. As shown in Fig. 6, MAC frame processing unit 140 includes, for example, classification unit 141, transmission queues 142A, 142B, 142C, and 142D, carrier sense execution units 143A, 143B, 143C, and 143D, and collision management unit 144.

[0039] The classification unit 141 classifies MAC frames received from the data processing unit 120 into a plurality of access categories based on the traffic type (TID) included in the MAC header. The traffic types include, for example, "VO (Voice)," "VI (Video)," "BE (Best Effort)," "BK (Background)," and "LL (Low Latency)." The classification unit 141 then inputs the MAC frame to one of the corresponding transmission queues 142A, 142B, 142C, and 142D. In this example, the classification unit 141 inputs VO data to the transmission queue 142A, VI data to the transmission queue 142B, BE data to the transmission queue 142C, and BK data to the transmission queue 142D. Furthermore, the classification unit 141 inputs the trigger frame TF received from the trigger generation unit 136 or an instruction to generate the trigger frame TF to the collision management unit 144 without going through the transmission queue 142, for example.

[0040] Each of the transmit queues 142A, 142B, 142C, and 142D buffers input MAC frames. In this example, the transmit queues 142A, 142B, 142C, and 142D buffer VO, VI, BE, and BK data, respectively.

[0041] Each of the carrier sense execution units 143A, 143B, 143C, and 143D performs carrier sense based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) in accordance with access parameters preset for each carrier sense execution unit 143. The access parameters are set for each access category, and are set, for example, so that wireless signal transmission is prioritized in the order of "VO," "VI," "BE," and "BK." The carrier sense execution units 143A, 143B, 143C, and 143D perform carrier sense on MAC frames buffered in the transmission queues 142A, 142B, 142C, and 142D, respectively. For example, when the carrier sense execution unit 143A acquires a transmission right (i.e., when the channel is idle), it retrieves a MAC frame from the transmission queue 142A. The carrier sense execution unit 143A then outputs the retrieved MAC frame to the wireless signal processing unit 150 via the collision management unit 144.

[0042] The collision management unit 144 prevents collisions in data transmission when multiple carrier sense execution units 143 acquire the transmission right for the same link. In other words, the collision management unit 144 adjusts the transmission timing of data for which the same STA function has acquired the transmission right, and outputs data of a higher priority access category to the STA function. Note that, because carrier sense is performed on the trigger frame TF without going through the transmission queue 142, the trigger frame TF can be processed with less delay than other traffic. Furthermore, when an instruction to generate a trigger frame TF is input, the collision management unit 144 may output the trigger frame TF to the STA function with priority over other traffic.

[0043] Although the embodiment illustrates a case where the MAC frame processing unit 140 implements the channel access function, this is not limiting. For example, the radio signal processing unit 150 may implement the channel access function. Examples of access parameters used include CWmin, CWmax, AIFS, and TXOPLimit. CWmin and CWmax respectively indicate the minimum and maximum values ​​of a contention window, which is a transmission waiting time for collision avoidance. AIFS (Arbitration Inter Frame Space) indicates a fixed transmission waiting time set for each access category for collision avoidance control with a priority control function. TXOPLimit indicates the upper limit of TXOP (Transmission Opportunity), which corresponds to the channel occupancy time. The shorter the CWmin and CWmax, the easier it is for the transmission queue 142 to obtain a transmission right. The smaller the AIFS, the higher the priority of the transmission queue 142. The larger the value of TXOPLimit, the greater the amount of data transmitted with one transmission right.

[0044] (Functional configuration of wireless terminal device WTA) Fig. 7 is a block diagram showing an example of the functional configuration of the wireless terminal device WTA included in the information communication system 1 according to the first embodiment. As shown in Fig. 7, the wireless terminal device WTA includes, for example, an application execution unit 200, an LLC processing unit 210, a data processing unit 220, a management unit 230, a MAC frame processing unit 240, and a radio signal processing unit 250. The respective processes of the application execution unit 200 and the LLC processing unit 210 may be realized by, for example, the CPU 20 and the RAM 22. The respective processes of the data processing unit 220, the management unit 230, the MAC frame processing unit 240, and the radio signal processing unit 250 may be realized by, for example, a combination of the CPU 20, the RAM 22, and the radio communication module 23.

[0045] The application execution unit 200 performs layer 7 processing on the input data. The LLC processing unit 210 performs layer 2 LLC sublayer processing and layer 3 to layer 6 processing on the input data. The data processing unit 220, management unit 230, and MAC frame processing unit 240 perform layer 2 MAC sublayer processing on the input data. The radio signal processing unit 250 performs layer 1 processing on the input data. Hereinafter, the set of the data processing unit 220, management unit 230, and MAC frame processing unit 240 provided in the wireless terminal apparatus WTA will also be referred to as the "link management unit MLD of the wireless terminal apparatus WTA."

[0046] The following describes in detail each of the functional components of the wireless terminal WTA.

[0047] The application execution unit 200 executes an application that can use data input from the LLC processing unit 210. Furthermore, the application execution unit 200 inputs data to the LLC processing unit 210 and acquires data from the LLC processing unit 210 in accordance with the operation of the application. The application execution unit 200 can display application information on the display 24. Furthermore, the application execution unit 200 can execute processing in accordance with operations performed via an input interface.

[0048] The LLC processing unit 210 generates an LLC packet by adding a DSAP header, an SSAP header, and the like to the data received from the application execution unit 200. Then, the LLC processing unit 210 inputs the generated LLC packet to the data processing unit 220. The LLC processing unit 210 also receives the LLC packet from the data processing unit 220 and extracts data from the received LLC packet. Then, the LLC processing unit 210 inputs the extracted data to the application execution unit 200.

[0049] The data processing unit 220 generates a MAC frame by adding a MAC header to the LLC packet input from the LLC processing unit 210. 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 210.

[0050] The management unit 230 manages the state of the link between the base station AP and the wireless terminal WTA. Information relating to link control and management can be exchanged between the management unit 230 and the MAC frame processing unit 240. The management unit 230 can also instruct the MAC frame processing unit 240 to execute predetermined processing. The management unit 230 includes, for example, link management information 231, an association processing unit 232, an authentication processing unit 233, a link control unit 234, a beacon management unit 235, and a delay measurement unit 236.

[0051] The link management information 231 is a table that includes information about links with wirelessly connected base stations APs. The link management information 231 can store settings related to the TWT function.

[0052] The association processing unit 232 executes a protocol related to association when transmitting a connection request to the base station AP.

[0053] The authentication processing unit 233 executes a protocol related to authentication subsequent to association. The link control unit 234 controls the state of the link with the wirelessly connected base station AP.

[0054] The beacon management unit 235 manages information included in a beacon received from the base station AP. The beacon management unit 235 receives, for example, management information included in the beacon and instructs the link control unit 234 to control the link based on the management information. The beacon management unit 235 may notify the data processing unit 220 of the contents of the management information.

[0055] When the wireless terminal device WTA transmits or receives low latency data (traffic), the delay measurement unit 236 measures the queuing delay of the data, i.e., the queuing delay time QL, and outputs the measured queuing delay time QL to the MAC frame processing unit 240. For example, when low latency data is input to the MAC frame processing unit 240, the queuing delay time QL corresponds to the time from when the data is input to the MAC frame processing unit 240 until when the data is output to the STA function. However, the queuing delay time QL is not limited to this, and other criteria may be used as long as it is possible to evaluate the queuing delay using a certain criterion.

[0056] The MAC frame processing unit 240 receives MAC frames from the data processing unit 220 or the management unit 230, and temporarily stores (buffers) the received MAC frames. The MAC frame processing unit 240 then performs carrier sensing. If the channel is busy, the MAC frame processing unit 240 continues carrier sensing. If the channel is idle, the MAC frame processing unit 240 inputs the MAC frame to the radio signal processing unit 250. The MAC frame processing unit 240 also receives MAC frames from the radio signal processing unit 250, and inputs the MAC frame to the data processing unit 220 or the management unit 230 depending on the type of MAC frame. For example, if the MAC frame is a data frame, the MAC frame processing unit 240 inputs the MAC frame to the data processing unit 220, and if the MAC frame is a management frame, the MAC frame processing unit 240 inputs the MAC frame to the management unit 230.

[0057] The radio signal processing unit 250 generates a radio frame by adding a preamble, a PHY (physical layer) header, etc. to the data input from the MAC frame processing unit 240. Then, the radio signal processing unit 250 performs a predetermined modulation operation on the radio frame to convert the radio frame into a radio signal, and radiates (transmits) the radio signal via an antenna. The radio signal processing unit 250 also receives a radio signal from the radio terminal apparatus WTA via the antenna, and performs a predetermined demodulation operation on the received radio signal to obtain a radio frame. Then, the radio signal processing unit 250 extracts a MAC frame from the radio frame and inputs the extracted MAC frame to the MAC frame processing unit 240. Hereinafter, the radio signal processing unit 250 is also referred to as an STA (or STA function) of the radio terminal apparatus WTA. Note that the radio terminal apparatus WTA may include multiple radio signal processing units.

[0058] (Functional Configuration of MAC Frame Processing Unit 240 of Wireless Terminal Apparatus WTA) Fig. 8 is a block diagram showing an example of the functional configuration of the MAC frame processing unit 240 of the wireless terminal device WTA included in the information communication system 1 according to the first embodiment. Fig. 8 shows details of the channel access function and the downlink data reception function of the MAC frame processing unit 240. As shown in Fig. 8, the MAC frame processing unit 240 includes, for example, a classification unit 241, transmission queues 242A, 242B, 242C, and 242D, carrier sense execution units 243A, 243B, 243C, 243D, and 243E, and a collision management unit 244.

[0059] The classification unit 241 classifies MAC frames received from the data processing unit 220 into a plurality of access categories based on the TID included in the MAC header. Then, the classification unit 241 inputs the MAC frame to one of the corresponding transmission queues 242A, 242B, 242C, and 242D. In this example, the classification unit 241 inputs VO data to the transmission queue 242A, VI data to the transmission queue 242B, BE data to the transmission queue 242C, and BK data to the transmission queue 242D. In addition, the classification unit 241 inputs LL data to the carrier sense execution unit 243E, for example, without passing through the transmission queue 242. LL is traffic (low-delay data) that is set to a higher priority than other traffic and requires low latency.

[0060] Each of the transmit queues 242A, 242B, 242C, and 242D buffers input MAC frames. In this example, the transmit queues 242A, 242B, 242C, and 242D buffer VO, VI, BE, and BK data, respectively.

[0061] Each of the carrier sense execution units 243A, 243B, 243C, 243D, and 243E performs carrier sensing based on CSMA / CA in accordance with access parameters preset for each carrier sense execution unit 243. Each of the carrier sense execution units 243A, 243B, 243C, 243D, and 243E then outputs the MAC frame for which it has acquired the transmission right to the wireless signal processing unit 250 via the collision management unit 244. The access parameters are set, for example, so that wireless signal transmission is prioritized in the order of "LL," "VO," "VI," "BE," and "BK." Each of the carrier sense execution units 243A, 243B, 243C, and 243D performs carrier sensing on the MAC frames buffered in the transmission queues 242A, 242B, 242C, and 242D, respectively. The carrier sense execution unit 243E performs carrier sensing on the LL MAC frame received from the classification unit 241. In this way, the MAC frame of LL can be processed with less delay than other traffic because carrier sense is performed on it without going through the transmission queue 242. Note that the carrier sense execution unit 243E may skip carrier sense when the data transmission is in response to the reception of the trigger frame TF.

[0062] The collision management unit 244 prevents collisions in data transmission when multiple carrier sense execution units 243 acquire the transmission right. In other words, the collision management unit 144 adjusts the transmission timing of the data for which the transmission right has been acquired, and outputs data of the access category with the highest priority to the STA function.

[0063] When the MAC frame processing unit 240 receives a trigger frame TF addressed to the local station, it outputs a MAC claim generated from the low latency data and the queue delay time QL of the MAC frame as a set to the STA function. That is, for low latency data, the MAC frame processing unit 240 outputs the data and the queue delay time together to the STA function as a response to the trigger frame TF, rather than transmitting it using CSMA / CA.

[0064] In the first embodiment, the MAC frame processing unit 240 implements the channel access function, but the present invention is not limited to this. For example, the radio signal processing unit 250 may implement the channel access function.

[0065] <1-2>TWT function The TWT function in the first embodiment will be described in detail below.

[0066] The link management unit MLD of the base station AP or the wireless terminal WTA sets up the TWT function, for example, to exchange low-latency data. The TWT function may be set up when the link is set up, or may be set up based on a low-latency data transmission request from the wireless terminal WTA after the link is established. Parameters used in the TWT function (hereinafter referred to as TWT settings) are set by the link management unit MLD of the base station AP and the wireless terminal WTA, respectively. The TWT settings in the first embodiment are set up and managed for each pair of the base station AP and the wireless terminal WTA. The base station AP may manage the TWT settings for each wireless terminal WTA, or for each group. In the first embodiment, a case will be described in which the base station AP manages the TWT settings for each wireless terminal WTA.

[0067] The TWT settings are managed by the management unit 130 of the base station AP and the management unit 230 of the wireless terminal WTA. The TWT settings include, for example, a TWT start time, a TWT cycle, and a TWT duration. The TWT start time corresponds to the start time of the TWT service period. The TWT cycle corresponds to the cycle of the TWT service period. One cycle of the TWT cycle may be called a "TWT interval." The TWT duration corresponds to the period during which a transmission opportunity is provided to the wireless terminal WTA. During the TWT duration, the link of the wireless terminal WTA that has been provided a transmission opportunity by the base station AP is set to a state in which it can receive a radio signal. When the TWT function is used, one cycle of the TWT service period can be specified by the TWT start time and the TWT duration.

[0068] The link management unit MLD of the wireless terminal WTA waits until the TWT service period begins before transmitting low-latency data, and causes the STA function to transmit low-latency data based on the reception of a trigger frame TF during the TWT service period. The period of the TWT service period is preferably set to match the period of the wireless terminal WTA's low-latency data transmission. Initial values ​​of the TWT settings, including the TWT start time (TWT interval) and TWT duration, can be set in various ways. Traffic attributes, such as the traffic occurrence interval and data volume, notified by an application that generates TWT low-latency traffic (data), may be used to determine the initial values ​​of the TWT settings. The base station AP may notify the server SV on the network NW of the traffic type, thereby obtaining the corresponding traffic attributes and determining the initial values ​​of the TWT settings. Alternatively, default values ​​set in the base station AP or the wireless terminal WTA may be used as the initial values ​​of the TWT settings.

[0069] The TWT start time may be expressed by a TWT period (TWT interval). The wireless terminal device WTA may recognize the time obtained by adding the TWT period to the previous TWT start time as the next TWT start time. In other words, the wireless terminal device WTA may recognize the time obtained by adding the TWT period to the previous TWT start time as the start time of the next TWT duration.

[0070] (Overview of how uplink data is transmitted) 9 is a sequence diagram showing an example of a method for transmitting uplink data when the TWT function is used in the information communication system 1 according to the first embodiment. <1> and <2> 1 illustrates an example in which uplink data is transmitted at each of the TWT intervals TI. <1> and <2> Each of the uplink data transmission methods has a TWT duration TD and a waiting period WP. The waiting period WP corresponds to a period during which no transmission opportunity is provided while the TWT function is in use. An overview of the uplink data transmission method will be described below with reference to FIG. 9.

[0071] The wireless terminal WTA transmits the TWT interval TI <1> Before the TWT interval TI, the uplink data DAT1 is buffered (S10). <1> When the start time of the TWT interval TI arrives, the base station AP transmits a trigger frame TF to the wireless terminal device WTA within the TWT duration TD (S11). The timing at which the trigger frame TF is transmitted is preferably the TWT start time. In order for the trigger frame TF to be transmitted at the TWT start time, the STA function may transmit the trigger frame TF using the highest priority category of EDCA (Enhanced Distributed Channel Access), or may transmit the trigger frame TF by a preferential transmission means different from EDCA. The wireless terminal device WTA transmits uplink data DAT1 to the base station AP based on the reception of the trigger frame TF (S12). When the base station AP successfully receives the uplink data DAT1, it transmits an Ack to the wireless terminal device WTA (S13). By receiving the Ack after transmitting the uplink data DAT1, the wireless terminal device WTA recognizes that the transmission of DAT1 was successful and discards DAT1. The processes of S11 to S13 are performed during the TWT interval TI <1> The TWT is executed within the TWT duration TD.

[0072] TWT interval TI <1> When the TWT duration TD ends within the TWT interval TI, the waiting period WP begins. <1> During the waiting period WP, ​​the wireless terminal WTA buffers the uplink data DAT2 (S14). <2> When the start time of the TWT interval TI arrives, the base station AP transmits a trigger frame TF to the wireless terminal device WTA within the TWT duration TD (S15). The wireless terminal device WTA transmits uplink data DAT2 to the base station AP based on the reception of the trigger frame TF (S16). When the base station AP successfully receives the uplink data DAT2, it transmits an Ack to the wireless terminal device WTA (S17). By receiving an Ack after transmitting the uplink data DAT2, the wireless terminal device WTA recognizes that the transmission of DAT2 was successful and discards DAT2. The processes of S25 to S27 are performed during the TWT interval TI <2> The TWT is performed within the TWT duration TD. <2> There will be a waiting period of WP.

[0073] As described above, when the TWT function is used, the access point AP notifies the wireless terminal WTA of a data transmission opportunity using a trigger frame TF during the TWT duration TD of each TWT interval TI. Then, each time the wireless terminal WTA receives a trigger frame TF, it attempts to transmit buffered data to the access point AP.

[0074] 9, the time from when the wireless terminal device WTA buffers the uplink data DAT1 (S10) until when it transmits it to the base station AP (S12) is shown as a “queue delay time QL1,” and the time from when the wireless terminal device WTA buffers the uplink data DAT2 (S14) until when it transmits it to the base station AP (S16) is shown as a “queue delay time QL2.” Each of the queuing delay times QL1 and QL2 can be measured by the delay measurement unit 236.

[0075] Furthermore, at the TWT start time, the base station AP may temporarily suspend CSMA / CA for other queues in order to transmit the trigger frame TF with the highest priority. For this purpose, the management unit 130 of the base station AP may notify the link (STA function) of the start time of transmission of the trigger frame TF.

[0076] (Trigger frame TF format) 10 is a conceptual diagram showing an example of the format of a trigger frame transmitted during a TWT service period in the information communication system 1 according to the embodiment. As shown in FIG. 10, the multiple fields included in the trigger frame include, for example, a frame control field, a duration field, address fields (RA and TA), a common information field, a user information list field, a padding field, and an FCS (Frame Check Sequence) field.

[0077] The frame control field stores various control information. For example, the frame control field includes information indicating the frame type of the wireless frame. The duration field indicates the planned period for using the wireless link. The address field includes the BSSID, source address, destination address, sender terminal address, receiver terminal address, etc. The common information field includes information indicating the type of trigger frame, etc. The user information list field includes, for example, an "AID" and an "RU (Resource Unit) Allocation." The wireless terminal device WTA recognizes that the allocation is intended for its own station by the AID. The wireless terminal device WTA also recognizes the allocated resources by the RU allocation. The padding is an area used to adjust the data length of the wireless frame. The FCS field stores an error detection code for the MAC header and frame body field pair, and is used to determine whether or not there is an error in the data frame.

[0078] (Beacon signal format) The base station AP uses, for example, a beacon as a method for notifying the wireless terminal WTA of the TWT setting. The beacon including the TWT setting is generated and transmitted, for example, by the beacon management unit 135 of the base station AP. The TWT setting included in the beacon received by the wireless terminal WTA is acquired and managed by the beacon management unit 235. In this way, the beacon management unit 135 of the base station AP can notify the wireless terminal WTA of the TWT service period for transmitting low-latency data.

[0079] FIG. 11 is a conceptual diagram illustrating an example of the format of a beacon including TWT settings used in the information communication system 1 according to the first embodiment. As illustrated in FIG. 11, the beacon may include the AIDs of the wireless terminal devices WTA wirelessly connected to the base station AP and the TWT settings for each AID. Specifically, the beacon stores pairs of AIDs and TWT settings in order, such as “AID#1,” “TWT setting for AID#1,” “AID#2,” and “TWT setting for AID#2.” The wireless terminal device WTA can determine whether the TWT settings are for its own station based on the pair of AIDs and TWT settings. Note that the beacon may have other formats as long as it allows the wireless terminal device WTA to determine the pair of AIDs and TWT settings. Furthermore, when TWT settings are managed by group, the base station AP transmits a beacon including, for example, information about a pair of identifiers of a group of wireless terminal devices WTA sharing TWT settings and the TWT settings associated with the group.

[0080] The TWT setting for each AID included in the beacon includes, for example, a TWT start time, a TWT duration, and a transmission suppression period. The transmission suppression period indicates a period during which uplink data transmission is suppressed or prohibited for the wireless terminal device WTA. The transmission suppression period corresponds to a period that starts at the TWT start time and continues for the TWT duration. In other words, the TWT duration and the transmission suppression period may overlap. When the TWT start time, TWT duration (and transmission suppression period) are input by the management unit 230, the STA function of the wireless terminal device WTA sets the period indicated by this information as the transmission suppression period. In other words, when the STA function of the wireless terminal device WTA acquires a transmission right for data other than low-latency data, it calculates the period required to complete transmission, and if the transmission suppression period overlaps with this period, it suppresses transmission during that period. On the other hand, when a trigger frame TF addressed to the wireless terminal device WTA is received at the TWT start time, it obtains low-latency data from the transmission queue 242E of the LL and transmits it.

[0081] Upon receiving a beacon, the beacon management unit 235 of each wireless terminal WTA acquires the TWT start time, TWT duration, and transmission suppression period, and notifies the link (STA function). This allows the base station AP to autonomously suppress uplink data transmission during the TWT service period in which low-latency data is transmitted for wireless terminal WTAs other than the wireless terminal WTA assigned to transmit low-latency data, among multiple wirelessly connected wireless terminal WTAs.

[0082] (How to update TWT settings) 12 is a flowchart showing an example of a method for updating the TWT setting in the information communication system 1 according to the first embodiment. The method for updating the TWT setting in the first embodiment will be described below with reference to FIG. 12, focusing on the operation of the base station AP.

[0083] When the TWT start time of a certain TWT cycle arrives, the base station AP transmits a trigger frame TF to the wireless terminal device WTA (S100). When low-latency data of uplink data is input, the wireless terminal device WTA measures, for example, the time from input of the low-latency data to reception of the trigger frame TF, and generates a queuing delay time QL. Then, the wireless terminal device WTA transmits the queuing delay time QL and the low-latency data together to the base station AP. That is, the wireless terminal device WTA transmits the low-latency data based on reception of the trigger frame TF, and notifies the base station AP of the queuing delay time QL of the low-latency data.

[0084] Next, the base station AP receives a wireless frame including the queue delay time QL and low latency data from the wireless terminal WTA (S110).

[0085] Next, the base station AP determines whether or not "QL>QLth" is satisfied (S120). Specifically, the base station AP determines (evaluates) whether or not the queue delay time of the traffic exceeds a predetermined threshold QLth, based on the queue delay time QL included in the received MAC frame. QLth is a threshold for queue delay time, and is set for each flow of low-latency data, for example. The base station AP may use, as QLth, a statistical value of past information regarding transmission and reception of low-latency data. A different value may be set for QLth for each wireless terminal device WTA.

[0086] If "QL>QLth" is not satisfied in the process of S120 (S120, NO), the base station AP proceeds to the process of the next TWT cycle without adjusting the TWT setting.

[0087] If "QL>QLth" is satisfied in the process of S120 (YES in S120), the base station AP adjusts the TWT setting of the link (S130). In the process of S130, the base station AP may adjust (update) the TWT start time (TWT interval) and TWT duration. Note that the method of adjusting the TWT setting is not limited to this. For example, the base station AP may calculate the distribution (period and variance) of input and output times of past low-latency data based on the queue delay time and the reception time of the low-latency data, and set the TWT interval and TWT duration so that a predetermined percentage is included. After updating the TWT setting, the base station AP proceeds to process the next TWT cycle.

[0088] When updating (adjusting) the TWT setting, the base station AP notifies the wireless terminal apparatus WTA of the updated TWT setting parameters. The base station AP may notify the wireless terminal apparatus WTA of the updated TWT setting using, for example, a beacon. Alternatively, the base station AP may notify the wireless terminal apparatus WTA of the updated TWT setting during the TWT service period. This allows the base station AP and the wireless terminal apparatus WTA to exchange low-latency data using the TWT function to which the updated TWT setting (e.g., TWT interval and TWT duration) has been applied.

[0089] (Example of how to update TWT settings) Fig. 13 is a sequence diagram showing a specific example of a method for updating the TWT settings in the information communication system 1 according to the first embodiment. Fig. 13 shows an example of the operation when transitioning from a TWT interval TI1 to which a first TWT setting is applied to a TWT interval TI2 to which a second TWT setting is applied. Below, a specific example of a method for updating the TWT settings will be described with reference to Fig. 13.

[0090] Before the TWT interval TI1<1>, the wireless terminal device WTA buffers the uplink data DAT1 (S20). When the start time of the TWT interval TI1<1> arrives, the base station AP transmits a trigger frame TF to the wireless terminal device WTA (S21). Based on receiving the trigger frame TF, the wireless terminal device WTA transmits the uplink data DAT1 and the queue delay time QL1 of the DAT1 to the base station AP (S22). In this example, QL1 is shorter than QLth (QL1 < QLth). When the base station AP successfully receives the DAT1 and QL1, it transmits an Ack to the wireless terminal device WTA (S23). Then, based on receiving the Ack, the wireless terminal device WTA discards the DAT1. Also, in the process of receiving the DAT1, the base station AP confirms that QL1 < QLth and determines that adjustment of the TWT setting is not necessary at this point (S120, NO).

[0091] In this example, the TWT interval TI1 <1> During the waiting period WP, ​​the wireless terminal WTA buffers the uplink data DAT2 (S24). <2> When the start time of the DAT2 arrives, the base station AP transmits a trigger frame TF to the wireless terminal device WTA (S25). Based on receiving the trigger frame TF, the wireless terminal device WTA transmits uplink data DAT2 and the queue delay time QL2 of the DAT2 to the base station AP (S26). In this example, QL2 is longer than QLth (QL2>QLth). When the base station AP successfully receives DAT2 and QL2, it transmits an Ack to the wireless terminal device WTA (S27). Then, based on receiving the Ack, the wireless terminal device WTA discards DAT2. Furthermore, in the process related to the reception of DAT2, the base station AP adjusts the TWT setting based on the fact that QL2>QLth (S120, YES). Then, the base station AP notifies the wireless terminal device WTA of the adjusted TWT setting using a beacon (S28). Thereafter, the wireless terminal WTA changes (updates) its own TWT setting based on the TWT setting included in the received beacon. In this example, the next TWT interval TI2 is set to be shorter than the TWT interval TI1. That is, when the base station AP detects, for example, a large delay in the transmission of low-latency data, it updates the TWT setting so that the cycle of the TWT service period becomes shorter.

[0092] In this example, during the waiting period WP of the TWT interval TI1<2>, the wireless terminal device WTA buffers the uplink data DAT3 (S29). Then, when the start time of the updated TWT interval TI2<1> arrives, the base station AP transmits a trigger frame TF to the wireless terminal device WTA (S30). Based on receiving the trigger frame TF, the wireless terminal device WTA transmits the uplink data DAT3 and the queue delay time QL3 of the DAT3 to the base station AP (S31). In this example, QL3 is longer than QLth (QL3>QLth). When the base station AP successfully receives DAT3 and QL3, it transmits an Ack to the wireless terminal device WTA (S32). Then, based on receiving the Ack, the wireless terminal device WTA discards DAT3. Note that in the process of receiving DAT3, the base station AP may adjust the TWT setting based on QL3>QLth, or may omit the adjustment of the TWT setting based on the fact that it is the TWT service period immediately after the TWT setting is updated.

[0093] In this example, during the waiting period WP of the TWT interval TI2<1>, the wireless terminal device WTA buffers the uplink data DAT4 (S33). Then, when the start time of the TWT interval TI2<2> arrives, the base station AP transmits a trigger frame TF to the wireless terminal device WTA (S34). Based on receiving the trigger frame TF, the wireless terminal device WTA transmits the uplink data DAT4 and the queue delay time QL4 of the DAT4 to the base station AP (S35). In this example, QL4 is shorter than QLth (QL4<QLth). Due to the update of the previous TWT setting which shortens the period of the TWT service period, the queue delay time of the uplink data can be shortened in this way. When the base station AP successfully receives DAT4 and QL4, it transmits an Ack to the wireless terminal device WTA (S36). Then, based on receiving the Ack, the wireless terminal device WTA discards DAT4. Similarly hereinafter, the base station AP can receive the uplink data of the wireless terminal device WTA, for example, by using the TWT function while changing the TWT setting.

[0094] The change in the TWT setting may be applied in the TWT interval TI next after the transmission of a beacon signal notifying the change in the TWT setting, or may be applied in the TWT interval TI a predetermined period later.

[0095] <1-3> Effects of the first embodiment In data communications, it is preferable to operate the link in power saving mode when there is no traffic congestion. However, if the power saving mode is operated for a long period, there is a risk that the delay in transmitting uplink data will increase.

[0096] One possible method for suppressing the delay of low-latency data in the uplink is to allocate periodic transmission of uplink data using the TWT function. Specifically, when uplink data is input periodically, it is preferable to match the period at which the uplink data is input with the period of the TWT service period. This can suppress the queue delay of low-latency data and reduce link power consumption. However, when using the TWT function, if the base station AP cannot know the input time or input period of the uplink data, the TWT period and the input timing of the uplink data may not match. In this case, using the TWT function may increase the delay. In other words, there is a risk that low-latency data may not be transmitted within the desired delay time.

[0097] Therefore, the base station AP according to the first embodiment acquires a queue delay time QL for each piece of data received from a wireless terminal WTA that exchanges low-latency data. If the queue delay time QL exceeds a predetermined threshold QLth, the base station AP adjusts the TWT setting, for example, to shorten the TWT interval (TWT cycle).

[0098] As a result, the base station AP according to the first embodiment can update the TWT setting to match the timing of data generation even when the periodicity of uplink low-latency data is uncertain. Therefore, the base station AP according to the first embodiment can increase (adjust) the frequency at which low-latency data is transmitted based on the queuing delay, thereby suppressing the queuing delay of low-latency data transmitted via uplink.

[0099] <1-4> Modification of the first embodiment In the first embodiment, the base station AP notifies the wireless terminal WTA of a new TWT setting using a beacon, but this is not limiting. The base station AP may also notify the wireless terminal WTA of a new TWT setting by adding TWT setting information to a wireless frame that transmits a trigger frame TF.

[0100] Fig. 14 is a sequence diagram showing a specific example of a method for adjusting TWT settings in an information communication system 1 according to a modification of the first embodiment. The flowchart shown in Fig. 14 has a configuration in which the processes of S20 to S27 in the flowchart shown in Fig. 13 are replaced with processes of S40 to S47, and the process of S28 is omitted. Below, with reference to Fig. 14, differences between the TWT setting update method in the modification of the first embodiment and the first embodiment will be described.

[0101] The wireless terminal WTA transmits the TWT interval TI1 <1> Before the TWT interval TI1, the uplink data DAT1 is buffered (S40). <1> When the start time of the DAT1 service arrives, the base station AP transmits a trigger frame TF to the wireless terminal device WTA (S41). Based on receiving the trigger frame TF, the wireless terminal device WTA transmits uplink data DAT1 and the queue delay time QL1a of the DAT1 to the base station AP (S42). In this example, QL1a is longer than QLth (QL1a>QLth). When the base station AP successfully receives DAT1 and QL1a, it transmits an Ack to the wireless terminal device WTA (S43). Then, based on receiving the Ack, the wireless terminal device WTA discards DAT1. Furthermore, in the process related to the reception of DAT1, the base station AP confirms that QL1a>QLth and generates the next TWT setting. This next TWT setting is, for example, a setting that shortens the cycle of the TWT service period (TWT cycle), as in the first embodiment.

[0102] In this example, the TWT interval TI1 <1> During the waiting period WP, ​​the wireless terminal WTA buffers the uplink data DAT2 (S44). <2> When the start time of the next TWT setting arrives, the base station AP transmits a radio signal including a trigger frame TF and a next TWT setting (Next TWT) to the wireless terminal device WTA (S45). Based on receiving the trigger frame TF, the wireless terminal device WTA transmits uplink data DAT2 and the queue delay time QL2 of the DAT2 to the base station AP (S46). When the base station AP successfully receives DAT2 and QL2, it transmits an Ack to the wireless terminal device WTA (S47). Furthermore, the wireless terminal device WTA applies the next TWT setting received in S45 to itself. After the process of S47, the processes of S29 to S36 are executed in order, for example, as in the first embodiment.

[0103] As described above, the link management unit MLD of the base station AP can notify the wireless terminal device WTA of the period during which the wireless signal processing unit (e.g., STA1) emits a wireless signal including the trigger frame TF after detecting that the queue delay time QL has exceeded the threshold QLth.

[0104] As a result, the base station AP in the modification of the first embodiment can notify the wireless terminal device WTA of the TWT setting without using a beacon, and the wireless terminal device WTA can update the TWT setting. Therefore, the modification of the first embodiment can suppress queuing delays of low-latency data transmitted in the uplink, similar to the first embodiment. Furthermore, the modification of the first embodiment can eliminate the period required for the wireless terminal device WTA to receive a beacon, thereby reducing power consumption of the wireless terminal device WTA more than the first embodiment.

[0105] <2> Second embodiment The configuration of the information communication system 1 according to the second embodiment is the same as that of the information communication system 1 according to the first embodiment. In the second embodiment, TWT settings are managed for each group, and the TWT settings of each group are updated based on the queue delay time QL. Below, the differences between the information communication system 1 according to the second embodiment and the first embodiment will be described.

[0106] <2-1>TWT function A base station AP according to the second embodiment establishes a TWT group GR when establishing links with multiple wireless terminal devices WTA and using the TWT function. A TWT group GR is a group of multiple wireless terminal devices WTA that use a common TWT setting. That is, in the second embodiment, multiple wireless terminal devices WTA belonging to the same TWT group GR share the same TWT setting. Then, as in the first embodiment, the base station AP according to the second embodiment can adjust the TWT setting based on the queue delay time QL acquired from each wireless terminal device WTA. However, the base station AP according to the second embodiment applies the adjusted TWT setting to the TWT group GR, not to each individual wireless terminal device WTA.

[0107] 15 is a flowchart showing an example of a method for updating the TWT settings in the information communication system 1 according to the second embodiment. The method for updating the TWT settings in the second embodiment will be described below with reference to FIG. 15, focusing on the operation of the base station AP associated with TWT group GR1.

[0108] When a TWT period of TWT group GR1 starts, the base station AP transmits a trigger frame TF addressed to a wireless terminal WTA selected within the TWT group GR (S200). Upon receiving the trigger frame TF addressed to itself, the wireless terminal WTA transmits a wireless frame including a queue delay time QL and low-latency data to the base station AP.

[0109] Next, the base station AP receives a wireless frame including the queue delay time QL and low latency data from the selected wireless terminal WTA (S210).

[0110] Next, the base station AP determines whether or not "QL>QLth" is satisfied (S220). The method for setting QLth in the process of S220 is the same as in the first embodiment.

[0111] If "QL>QLth" is not satisfied in the processing of S220 (S220, NO), the base station AP proceeds to processing of the next TWT cycle without adjusting the TWT settings of TWT group GR1.

[0112] If "QL>QLth" is satisfied in the processing of S220 (YES in S220), the base station AP adjusts the TWT settings of the TWT group GR1 (S230). The method of adjusting the TWT settings in the processing of S230 is the same as in the first embodiment. If "QL>QLth" is satisfied, the base station AP reduces the TWT interval to, for example, 1 / 2. After updating the TWT settings, the base station AP proceeds to processing the next TWT cycle.

[0113] Fig. 16 is a table showing an example of a change in TWT settings in the information communication system 1 according to the second embodiment. The table shown in Fig. 16 shows the TWT interval, TWT duration, and AID set for each of TWT groups GR1 and GR2, with strikethroughs and arrows indicating the conditions before and after the TWT settings are updated. In this example, wireless terminal devices WTA1 and WTA2 are assigned to TWT group GR1, and a TWT interval TI1 and a TWT duration TD are set for them. Wireless terminal device WTA3 is assigned to TWT group GR2, and a TWT interval TI2 and a TWT duration TD are set for them.

[0114] When the TWT setting update method of the second embodiment is used in this example, the TWT interval TI1 in TWT group GR1 is changed to, for example, 1 / 2 (i.e., (TI1) / 2) based on the fact that the queue delay time QL in the uplink data of wireless terminal device WTA1 or WTA2 has exceeded QLth. Note that when it is confirmed that QL>QLth, the TWT setting should be set so that at least the TWT period is shortened.

[0115] <2-2> Effects of the second embodiment By managing TWT settings for each TWT group (GR), the base station AP can easily manage the TWT function. Ideally, the TWT settings applied to a TWT group (GR) are set according to the timing and period of traffic generated in each of the multiple wireless terminal devices (WTAs) so that all traffic can be accommodated. However, actual traffic also includes aperiodic traffic. For this reason, it is difficult to accurately set the initial TWT function settings for a TWT group (GR) to which multiple wireless terminal devices (WTAs) are assigned.

[0116] Therefore, when the base station AP of the second embodiment detects low-latency data (traffic) whose queue delay time QL exceeds the threshold QLth, it shortens (e.g., halves) the TWT period in the TWT group GR to which the transmission of the low-latency data is assigned.

[0117] Fig. 17 is a timing chart showing an example of a method of transmitting uplink data before and after a change in the TWT setting in the information communication system 1 according to the second embodiment. (1) and (2) in Fig. 17 correspond to the traffic conditions of wireless terminal devices WTA1 and WTA2 belonging to the same TWT group GR before and after the change in the TWT setting, respectively. Boxes hatched with diagonal lines indicate the transmission timing of trigger frames TF. Boxes hatched with dots indicate the transmission timing of traffic (data DAT). The arrow pointing from the trigger frame TF to the data DAT indicates the data DAT given a transmission opportunity by the trigger frame TF.

[0118] As shown in (1) of FIG. 17, before the TWT setting change, the base station AP has a TWT interval TI1 <1> and <2> In this example, the transmission period of the traffic of the wireless terminal WTA1 coincides with the TWT interval TI1. <1> and <2> On the other hand, the wireless terminal WTA2 can transmit traffic based on the trigger frames TF of the TWT interval TI. <1> However, a transmission opportunity cannot be allocated, resulting in a queue delay (waiting for transmission in FIG. 17).

[0119] When the base station AP according to the second embodiment detects the occurrence of such a queuing delay in the wireless terminal device WTA2 by comparing the queuing delay time QL with a threshold QLth (detecting that QL>QLth), it changes the TWT setting of the TWT group GR that includes the wireless terminal device WTA2. In this example, the TWT period of the TWT group GR is halved, and is shown as "TWT interval (TI1 / 2)."

[0120] As shown in (2) of FIG. 17, after the TWT setting change, the base station AP changes the TWT interval ((TI1) / 2) <1> , <2> and <3> The base station AP transmits a trigger frame TF during each TWT duration TD. After the TWT setting change, the base station AP can allocate transmission opportunities to both the traffic of the wireless terminal device WTA1 and the traffic of the wireless terminal device WTA2 by halving the TWT cycle.

[0121] In this way, the base station AP according to the second embodiment can increase the chances of recovering low-latency traffic exceeding the threshold QLth of the queuing delay time QL when using the TWT function. Therefore, the base station AP according to the second embodiment can suppress queuing delay of low-latency data transmitted in the uplink.

[0122] <3> Third embodiment The configuration of the information communication system 1 according to the third embodiment is the same as that of the information communication system 1 according to the first embodiment. In the third embodiment, TWT settings are managed for each TWT group GR, as in the second embodiment, and the TWT group GR to which the wireless terminal device WTA belongs is changed based on the queue delay time QL. Below, the differences between the information communication system 1 according to the third embodiment and the first and second embodiments will be described.

[0123] <3-1>TWT function A base station AP according to the third embodiment establishes links with multiple wireless terminal devices WTA and sets multiple TWT groups GR when using the TWT function. The base station AP then applies different TWT settings to the multiple TWT groups GR. The multiple TWT groups GR set by the base station AP include, for example, a TWT group GR with a long TWT interval and a TWT group GR with a short TWT interval.

[0124] Then, the base station AP according to the third embodiment changes the setting of the TWT group GR to which each wireless terminal device WTA belongs, based on the queue delay time QL acquired from each wireless terminal device WTA. For example, when the base station AP according to the third embodiment detects low-latency data (traffic) whose queue delay time QL exceeds a threshold QLth, it changes the TWT group GR assigned to the wireless terminal device WTA to which transmission of the low-latency data is assigned to a TWT group GR with a shorter TWT period than the current TWT group GR.

[0125] 18 is a flowchart showing an example of a method for updating the TWT settings in the information communication system 1 according to the third embodiment. The method for updating the TWT settings in the third embodiment will be described below with reference to FIG. 18, focusing on the operation of the base station AP associated with TWT group GR1.

[0126] When a TWT period of TWT group GR1 starts, the base station AP transmits a trigger frame TF addressed to a wireless terminal WTA selected within the TWT group GR (S300). Upon receiving the trigger frame TF addressed to itself, the wireless terminal WTA transmits a wireless frame including a queue delay time QL and low-latency data to the base station AP.

[0127] Next, the base station AP receives a wireless frame including the queue delay time QL and low latency data from the selected wireless terminal WTA (S310).

[0128] Next, the base station AP determines whether or not "QL>QLth" is satisfied (S220). The method for setting QLth in the process of S320 is the same as in the first embodiment.

[0129] If "QL>QLth" is not satisfied in the process of S320 (S320, NO), the base station AP proceeds to the process of the next TWT cycle without adjusting the TWT setting of the selected wireless terminal WTA.

[0130] If "QL>QLth" is satisfied in the processing of S320 (YES in S320), the base station AP changes the TWT group of the selected wireless terminal device WTA (S330). For example, the base station AP changes the TWT group to which the wireless terminal device WTA for which "QL>QLth" is satisfied belongs to a TWT group with a narrower TWT interval (shorter TWT cycle) than the current TWT group. After updating the TWT settings, the base station AP proceeds to processing the next TWT cycle.

[0131] Fig. 19 is a table showing an example of a change in TWT settings in an information communication system 1 according to the third embodiment. The table shown in Fig. 19 shows the TWT interval, TWT duration, and AID set for each of TWT groups GR1 and GR2, with strikethroughs and arrows indicating the state before and after the TWT settings are updated. In this example, wireless terminal device WTA1 is assigned to TWT group GR1, and a TWT interval TI1 and a TWT duration TD are set for it. Wireless terminal device WTA2 is assigned to TWT group GR2, and a TWT interval TI2 and a TWT duration TD are set for it. TWT groups GR1 and GR2 are set to have different TWT service periods. The TWT interval TI2 is set to, for example, half the TWT interval TI1.

[0132] When the TWT setting update method of the third embodiment is used in this example, for example, based on the fact that the queue delay time QL in the uplink data of the wireless terminal device WTA2 has exceeded QLth, the wireless terminal device WTA2, which belonged to TWT group GR1, is changed from TWT group GR1 to TWT group GR2, which has a shorter TWT period than TWT group GR1. Note that it is sufficient that the TWT group GR selected after the change has a TWT period that is at least shorter than that of the TWT group GR before the change.

[0133] <3-2> Effects of the third embodiment Fig. 20 is a timing chart showing an example of a method for transmitting uplink data before and after a change in TWT setting in an information communication system according to the third embodiment. (1) and (2) in Fig. 20 correspond to the traffic conditions of wireless terminal devices WTA belonging to TWT groups GR1 and GR2 before and after a change in TWT setting, respectively. Boxes hatched with diagonal lines indicate the transmission timing of trigger frames TF. Boxes hatched with dots indicate the transmission timing of traffic (data DAT). The arrow pointing from the trigger frame TF to the data DAT indicates the data DAT given a transmission opportunity by the trigger frame TF.

[0134] As shown in (1) of FIG. 20, before the TWT setting change, the base station AP is configured to transmit the TWT interval TI1 of the TWT group GR1. <1> and <2> In this example, the wireless terminal WTA1 transmits a trigger frame TF during each TWT interval TI1. <1> and <2> On the other hand, the wireless terminal WTA2 can transmit traffic based on the trigger frames TF of the TWT interval TI. <1> However, transmission opportunities cannot be allocated, resulting in queuing delays (transmission waiting in FIG. 20). Also, before the TWT setting change, the base station AP had traffic occurring in TWT group GR2 at TWT interval TI2. <1> , <2> and <3> In each of these, a trigger frame TF may be transmitted.

[0135] When the base station AP according to the third embodiment detects the occurrence of such a queuing delay in the wireless terminal device WTA2 by comparing the queuing delay time QL with a threshold QLth (detecting that QL>QLth), it changes the TWT group GR to which the wireless terminal device WTA2 belongs. In this example, the wireless terminal device WTA2, which belongs to TWT group GR1, is changed to TWT group GR2, which has a TWT period half that of TWT group GR1.

[0136] As shown in (2) of FIG. 20, after the TWT setting change, the base station AP changes the TWT interval TI1 of the TWT group GR1. <11> and <12> The base station AP transmits a trigger frame TF during each TWT duration TD, thereby providing a transmission opportunity for each traffic of the wireless terminal device WTA1. After the TWT setting change, the base station AP <11> , <12> and <13> , and a trigger frame TF is transmitted in each of the above cases, thereby providing a transmission opportunity for each traffic of the wireless terminal WTA2.

[0137] In this way, the base station AP according to the third embodiment, like the second embodiment, can increase the chances of relieving low-latency traffic that exceeds the threshold QLth of the queuing delay time QL when using the TWT function. Therefore, the base station AP according to the third embodiment can suppress queuing delay of low-latency data transmitted in the uplink.

[0138] <4> Fourth embodiment The configuration of the information communication system 1 according to the fourth embodiment is the same as that of the information communication system 1 according to the first embodiment. In the fourth embodiment, multilink is used for wireless connection between the base station AP and the wireless terminal device WTA, and TWT settings are managed for each TWT group GR as in the second embodiment, and the TWT group GR is managed in association with one or more channels. Below, the differences between the information communication system 1 according to the fourth embodiment and the first to third embodiments will be described.

[0139] <4-1> About Multilink Multilink is a wireless connection that allows data to be transmitted and received using multiple links. When multilink is used, each of the base station AP and the wireless terminal device WTA has multiple STA functions (wireless signal processing units). In multilink, multiple channels CH are used. The multiple channels CH used in multilink may be in the same frequency band or different frequency bands.

[0140] (Example of link status) Fig. 21 is a table showing an example of link management information 131 held by a base station AP included in an information communication system 1 according to the fourth embodiment. Fig. 21 illustrates a link state relating to a wireless terminal device WTA with AID=#1. As shown in Fig. 21, the link management information 131 includes, for example, information on "STA function," "link," "frequency band," "channel ID," "multi-link," and "TID (Traffic IDentifier)."

[0141] "STA Function" indicates a link identifier (Link ID) associated with the STA function. In this example, three STA functions (STA1, STA2, and STA3) are assigned to wireless communication between the wireless terminal device WTA with AID=#1 and the base station AP.

[0142] "Link" indicates whether a link is established or not. In this example, STA1 and STA2 each indicate that a link is established ("Yes" in FIG. 21), and STA3 indicates that a link is not established ("No" in FIG. 21).

[0143] "Frequency band" indicates the frequency band used for the link. In this example, STA1, STA2, and STA3 are assigned the 6 GHz band, the 5 GHz band, and the 2.4 GHz band, respectively.

[0144] "Channel ID" indicates the ID of the channel used for the link. In this example, STA1 is assigned a channel CH1 in the 6 GHz band, and STA2 is assigned a channel CH2 in the 5 GHz band.

[0145] "Multi-link" indicates whether or not a multi-link has been established. In this example, the pair of STA1 and STA2 has established a multi-link ("◯" in FIG. 21).

[0146] "TID" indicates the traffic type assigned to a link (STA function). Each of #1 to #3 listed in "TID" in FIG. 21 corresponds to one of VO, VI, BE, BK, and LL. In this example, TID#1 is assigned to STA and STA2, TID#2 is assigned to STA1, and TID#3 is assigned to STA2. In this manner, in a multilink, one or more STA functions can be assigned to one TID. The association between traffic and STA functions is set, for example, so that the traffic volume (data volume) is equalized among the multiple links constituting the multilink. This is not limiting, and traffic of similar types (priority / non-priority, etc.) may be collected in a specific link constituting the multilink.

[0147] The link management information 231 held by the wireless terminal apparatus WTA may include, for example, information similar to the information shown in FIG. 21. The link control unit 134 of the base station AP may determine the association between a TID and an STA function when establishing a multi-link. The link control unit 234 of the wireless terminal apparatus WTA may determine the association between a TID and an STA function when establishing a multi-link. The MAC frame processing unit 140 of the base station AP may identify a link associated with the TID of the data included in the MAC frame by referring to the link management information 131. The MAC frame processing unit 240 of the wireless terminal apparatus WTA may identify a link associated with the TID of the data included in the MAC frame by referring to the link management information 231.

[0148] (How to set up Multilink) Fig. 22 is a flowchart showing an example of a multi-link setup method in the information communication system 1 according to the fourth embodiment. The multi-link setup method will be described below with reference to Fig. 22. The multi-link setup is performed between the link management unit MLD of the base station AP and the link management unit MLD of the wireless terminal device WTA by using, for example, a management frame.

[0149] In the process of S50, the wireless terminal device WTA transmits (broadcasts) a probe request to the base station AP. The probe request is a signal that confirms whether or not the base station AP is present in the vicinity of the wireless terminal device WTA. Upon receiving the probe request, the base station AP executes the process of S51.

[0150] In the process of S51, the base station AP transmits a probe response to the wireless terminal device WTA. The probe response is a signal used in response to a probe request from the wireless terminal device WTA, and includes information necessary for establishing a multilink. Upon receiving the probe response, the wireless terminal device WTA executes the process of S52.

[0151] In the process of S52, the wireless terminal device WTA transmits a multilink association request to the base station AP via one of the STA functions of the wireless terminal device WTA. The multilink association request is a signal requesting the base station AP to establish a multilink and includes information for a multilink connection. Upon receiving the multilink association request, the link management unit MLD of the base station AP executes the process of S53.

[0152] In the process of S53, the link management unit MLD of the base station AP executes a multi-link association process. In the multi-link association process, the base station AP first executes an association process of a first STA function with the wireless terminal device WTA. Then, when a wireless connection (link) is established in the first STA function, the link management unit MLD of the base station AP executes an association process of a second STA function using the first STA function with which the link is established. When the association processes of at least two STA functions are completed, the base station AP recognizes that a multi-link with the wireless terminal device WTA has been established, and executes the process of S54.

[0153] In the process of S54, the link management unit MLD of the base station AP updates the link management information 131. After the link management information 131 is updated, the base station AP executes the process of S55.

[0154] In the process of S55, the base station AP transmits a multilink establishment response to the wireless terminal device WTA. The multilink establishment response is a signal used in response to a multilink request from the wireless terminal device WTA. The link management unit MLD of the wireless terminal device WTA recognizes that a multilink with the base station AP has been established based on the reception of the multilink establishment response, and executes the process of S56.

[0155] In the process of S56, the link management unit MLD of the wireless terminal WTA updates the link management information 231. As a result, the link management information is updated in both the base station AP and the wireless terminal WTA, and the multilink setup is completed. Thereafter, the base station AP and the wireless terminal WTA can perform data communication using the multilink.

[0156] The multilink setup may be performed based on a beacon periodically transmitted by the base station AP. In this case, the wireless terminal WTA performs the process of S52 based on receiving the beacon. That is, the processes of S50 and S51 may be omitted. When setting up the multilink, the link management units MLD of the base station AP and the wireless terminal WTA perform mapping between each link included in the multilink and a traffic type (TID). Specifically, the link management unit MLD of the wireless terminal WTA determines the association between traffic and links and requests the link management unit MLD of the base station AP to apply the association. Thereafter, when the wireless terminal WTA receives an acknowledgment for the request from the base station AP, the association between traffic and links is established.

[0157] <4-2>TWT function A base station AP according to the fourth embodiment establishes links with multiple wireless terminal devices WTA and sets multiple TWT groups GR when using the TWT function. The base station AP then applies different TWT settings to the multiple TWT groups GR. The base station AP according to the fourth embodiment also manages the TWT groups GR in association with one or more channels. The wireless terminal device WTA can transmit low-latency data (traffic) using some or all of the channels of the TWT group GR to which the low-latency data is assigned.

[0158] Fig. 23 is a table showing an example of TWT settings in an information communication system 1 according to the fourth embodiment. In the table shown in Fig. 23, the channels assigned to TWT groups GR1 and GR2 are indicated by circles in the drawing. In this example, channels CH1, CH2, and CH3 are assigned to TWT group GR1, and channels CH1 and CH2 are assigned to TWT group GR2. The base station AP can transmit trigger frames TF and the like for all of the associated channels CH in accordance with the TWT period of each TWT group GR.

[0159] Fig. 24 is a table showing an example of channel allocation for each TWT group in the information communication system 1 according to the fourth embodiment. The tables shown in Fig. 24 (1) and (2) correspond to the channel allocation for TWT groups GR1 and GR2, respectively, and the channels allocated to the wireless terminal device WTA under the conditions shown in Fig. 23 are indicated by "○" in the drawing. "Active" indicates that a channel CH is allocated for use in the TWT group GR. "Disable" indicates that a channel CH is not allocated for use in the TWT group GR.

[0160] In this example, as shown in (1) of Figure 24, wireless terminal devices WTA1 and WTA2 are assigned to TWT group GR1. The wireless terminal device WTA1 is assigned to use channels CH1, CH2, and CH3, and the wireless terminal device WTA2 is assigned to use channels CH2 and CH3. Furthermore, as shown in (2) of Figure 24, wireless terminal device WTA3 is assigned to TWT group GR2. The wireless terminal device WTA3 is assigned to use channels CH1 and CH2.

[0161] That is, the wireless terminal device WTA1 can transmit data to the base station AP using all of the channels CH1, CH2, and CH3 assigned to the TWT group GR1. The wireless terminal device WTA2 can transmit data to the base station AP using only channels CH2 and CH3 out of the channels CH1, CH2, and CH3 assigned to the TWT group GR1. The wireless terminal device WTA3 can transmit data to the base station AP using all of the channels CH1 and CH2 assigned to the TWT group GR2.

[0162] Fig. 25 is a timing chart showing an example of a method for transmitting uplink data based on TWT setting in the information communication system 1 according to the fourth embodiment. Fig. 25 shows timings at which traffic of the wireless terminal devices WTA1, WTA2, and WTA3 can be transmitted. Boxes with diagonal hatching indicate the transmission timing of the trigger frame TF. Boxes with dotted hatching indicate the transmission timing of traffic (data DAT).

[0163] As shown in FIG. 25, the base station AP determines the TWT interval TI1 of the TWT group GR1. <1> and <2> In each TWT interval TI1, the wireless terminal WTA1 of TWT group GR1 may transmit a trigger frame TF using channels CH1, CH2, and CH3, respectively. In each TWT interval TI1, the wireless terminal WTA2 of TWT group GR1 may transmit traffic to the base station AP using channels CH2 and CH3, respectively. Meanwhile, the base station AP transmits traffic to the base station AP using channels CH2 and CH3, respectively, in each TWT interval TI2 of TWT group GR2. <1> , <2> and <3> In each TWT interval TI2, the wireless terminal WTA3 in the TWT group GR2 may transmit a trigger frame TF using each of the channels CH2 and CH3. The wireless terminal WTA3 in the TWT group GR2 may transmit traffic to the base station AP using each of the channels CH2 and CH3.

[0164] The channel to be used by the wireless terminal WTA may be determined by the base station AP or by the wireless terminal WTA itself. When the base station AP determines the channel, the base station AP may notify the wireless terminal WTA of the channel to be used by the wireless terminal WTA in a trigger frame TF or in a beacon. When the wireless terminal WTA determines the channel, the wireless terminal WTA notifies (transmits) information about the channel to be used to the base station AP using, for example, an assigned TWT service period.

[0165] <4-3> Effects of the fourth embodiment As described above, the base station AP according to the fourth embodiment manages TWT settings for each TWT group GR. Each wireless terminal device WTA can be assigned one or more channels from among the channels assigned to the TWT group GR to which it belongs. In other words, the correspondence between the TWT group GR and the channel is uniquely defined between the base station AP and the wireless terminal device WTA according to the fourth embodiment.

[0166] This allows the base station AP according to the fourth embodiment to easily manage the channel settings of each wireless terminal WTA. Furthermore, the base station AP according to the fourth embodiment allows each wireless terminal WTA to use some of the channels associated with the TWT group GR, thereby ensuring flexibility in uplink data transmission on the wireless terminal WTA side.

[0167] <5> others The configuration and functional configuration of the information communication system 1 according to the above embodiment may be other configurations. For example, although the base station AP and the wireless terminal device WTA each have three STA functions (wireless signal processing units), the present invention is not limited to this. The base station AP only needs to have at least one wireless signal processing unit. Similarly, the wireless terminal device WTA only needs to have at least one wireless signal processing unit. The number of channels that the STA function can process may be set appropriately depending on the frequency band used. Each of the wireless communication modules 13 and 23 may support wireless communication in multiple frequency bands using multiple communication modules, or a single communication module may support wireless communication in multiple frequency bands. The functional configurations of the base station AP and the wireless terminal device WTA may be named and grouped differently as long as they are capable of performing the operations described in the embodiment.

[0168] In the information communication system 1 according to the above embodiment, the CPU 10 included in the base station AP and the CPU 20 included in the wireless terminal device WTA may each be other circuits. For example, the base station AP and the wireless terminal device WTA may each be equipped with an MPU (Micro Processing Unit) instead of a CPU. Each of the processes described in the embodiment may be realized by dedicated hardware. The processes of the base station AP and the wireless terminal device WTA may be a mixture of processes executed by software and processes executed by hardware, or may be only one of them.

[0169] A base station AP using the TWT setting update method of the third embodiment may include the operations described in this paragraph. The link management unit MLD of the base station AP generates trigger frames TF to be emitted at a first period and addressed to a first group of wireless terminal devices, including the wireless terminal device WTA1. The link management unit MLD of the base station AP then generates trigger frames to be emitted at a second period different from the first period and addressed to a second group of wireless terminal devices. The base station AP then receives uplink data and information about the queuing delay time of the uplink data from the wireless terminal device WTA1 in response to the trigger frame TF included in the set of trigger frames emitted at the first period. If the queuing delay time exceeds a predetermined threshold, the base station AP changes the TWT group assignment of the wireless terminal device WTA1 from the first group to the second group.

[0170] A base station AP using the TWT setting in the fourth embodiment may include the configuration described in this paragraph in addition to the content of the previous paragraph. The link management unit MLD of the base station AP assigns a first radio signal processing unit (e.g., STA1) and a second radio signal processing unit (e.g., STA2) to the emission of a radio signal including a trigger frame TF corresponding to a first group, and assigns one or more radio signal processing units out of the first radio signal processing unit (e.g., STA1) and the second radio signal processing unit (e.g., STA2) to each of the communications between the wireless terminal device WTA1 and the wireless terminal device WTA2. Note that the assignment of each of the communications between the wireless terminal device WTA1 and the wireless terminal device WTA2 may be managed in units of channels assigned to the STA function. In the fourth embodiment, the number of channels assigned to each of the wireless terminal devices WTA1 and WTA2 belonging to the same TWT group GR may differ.

[0171] In the above embodiments, the flowcharts used to explain the operations are merely examples. The order of the processes of each operation described in the embodiments may be changed as far as possible, and other processes may be added. For example, the multi-link setup method described in the first embodiment is merely an example. Furthermore, the wireless frame format described in the first embodiment is merely an example. In the information communication system 1, other formats may be used as long as they are capable of executing the operations described in the embodiments. A wireless communication standard other than the IEEE 802.11 standard may be used for wireless communication between the base station AP and the wireless terminal device WTA.

[0172] 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. [Explanation of symbols]

[0173] AP…Base station WTA: Wireless Terminal Equipment 1. Information and communication systems 10...CPU 11...ROM 12...RAM 13...Wireless communication module 14...Wired communication module 110...LLC Processing Section 120...Data processing unit 130...Management Department 131...Link management information 132...Association processing unit 133...Authentication processing unit 134...Link control unit 135...Beacon Management Department 136...Trigger generation unit 137...Delay determination unit 140...MAC frame processing unit 141...Classification section 142...Transmission queue 143...Career Sense Executive Department 144…Collision Management Department 150...Radio signal processing unit 20...CPU 21...ROM 22...RAM 23...Wireless communication module 24…Display 25…Storage 200...Application execution unit 210...LLC Processing Section 220...Data processing unit 230...Management Department 231...Link management information 232...Association processing unit 233...Authentication processing unit 234...Link control unit 235...Beacon Management Department 236...Delay measurement unit 240...MAC frame processing unit 241...Classification section 242...Transmission queue 243…Career Sense Executive Department 244…Collision Management Department 250...Radio signal processing unit

Claims

1. a first radio signal processing unit; a link management unit that establishes a link with a first wireless terminal device using the first wireless signal processing unit, The link management unit causing the first radio signal processing unit to emit a radio signal including a trigger frame at a first period; receiving, from the first wireless terminal device in response to a first trigger frame included in the set of trigger frames emitted in the first period, first uplink data and information on a first queue delay time of the first uplink data, and, when the first queue delay time exceeds a first threshold, changing a period for causing the first wireless signal processing unit to emit a wireless signal including the trigger frame from the first period to a second period shorter than the first period; Base station.

2. the link management unit notifies the first wireless terminal device of a cycle at which the first wireless signal processing unit emits the trigger frame by using a beacon; The base station of claim 1 .

3. the link management unit, after detecting that the queue delay time has exceeded the threshold, uses a second trigger frame that the link management unit causes the first radio signal processing unit to emit, to notify the first radio terminal device of a period for causing the first radio signal processing unit to emit a radio signal including the trigger frame; The base station of claim 1 .

4. The link management unit establishing a link with a second wireless terminal device using the first wireless signal processing unit; generating the trigger frame emitted at the first period addressed to a first group of wireless terminal devices including the first wireless terminal device and the second wireless terminal device; receiving information on queue delay times from each of the first wireless terminal device and the second wireless terminal device in response to the trigger frame included in the set, and if the queue delay times exceed a second threshold, changing a cycle at which the first wireless signal processing unit emits a wireless signal including the trigger frame from the first cycle to a third cycle shorter than the first cycle; The base station of claim 1 .

5. The link management unit generating the trigger frame emitted at the first period addressed to a first group of wireless terminal devices including the first wireless terminal device; generating a trigger frame to be emitted at a fourth period different from the first period, the trigger frame being addressed to a second group of wireless terminal devices; receiving second uplink data and information on a second queuing delay time of the second uplink data from the first wireless terminal device in response to the trigger frame included in the set, and if the second queuing delay time exceeds a second threshold, changing a group assignment for the first wireless terminal device from the first group to the second group; The base station of claim 1 .

6. further comprising a second radio signal processing unit; the link management unit assigns the first radio signal processing unit and the second radio signal processing unit to radiation of a radio signal including the trigger frame corresponding to the first group, and assigns one or more radio signal processing units of the first radio signal processing unit and the second radio signal processing unit to each of communications between the first radio terminal device and the second radio terminal device; the number of radio signal processing units allocated to the first radio terminal device is different from the number of radio signal processing units allocated to the second radio terminal device; The base station of claim 5.

7. a radio signal processing unit; a link management unit that establishes a link with a base station using the radio signal processing unit, The link management unit causing the radio signal processing unit to receive a radio signal including a trigger frame in a first period; transmits uplink data and information on a queue delay time of the uplink data to the base station using the radio signal processing unit in response to a first trigger frame included in the set of trigger frames received in the first cycle, and when the queue delay time exceeds a first threshold, changes a cycle at which the radio signal processing unit receives a radio signal including the trigger frame from the first cycle to a second cycle shorter than the first cycle; Wireless terminal device.

8. the link management unit, based on the fact that the radio signal processing unit has received a beacon or a trigger frame including information of the second cycle from the base station, sets the radio signal processing unit to a state in which it can receive a radio signal from the base station in accordance with the second cycle.

8. The wireless terminal device according to claim 7.

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