Access Points

Abstract

An access point according to an embodiment of the present invention comprises a wireless signal processing unit and a management unit. The management unit is configured to use the wireless signal processing unit to establish a first link with a first wireless terminal device and a second link with a second wireless terminal device. The management unit sets a first service period in which a first traffic transmission opportunity is provided to the first wireless terminal device at a first cycle, and a second service period in which a second traffic transmission opportunity is provided to the second wireless terminal device at a second cycle. The management unit manages a first transmission priority that is based on a first traffic delay request condition and a second transmission priority that is based on a second traffic delay request condition. When competition between the first service period and the second service period has been detected and it has been confirmed that the first transmission priority is higher than the second transmission priority, the management unit notifies the second wireless terminal device of a change in a setting related to the second service period.

Description

[Technical Field]

[0001] The embodiment is an access point To Regarding. [Background technology]

[0002] A wireless LAN (Local Area Network) is known as a communication system that wirelessly connects an access point and a wireless terminal device. By using a wireless LAN, a wireless terminal device can access a network via an access point within its communication area. In addition, the access point and the wireless terminal device may provide a service period for preferentially exchanging traffic requiring low latency (low latency traffic). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] IEEE P802.11beTM / D1.5, "35.9 Restricted TWT (r-TWT)", March 18, 2022 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem is to control multiple wireless terminal devices so as to satisfy the delay requirements of the low-latency traffic of each of the multiple wireless terminal devices. [Means for solving the problem]

[0005] An access point according to an embodiment includes a wireless signal processing unit and a management unit. The management unit is configured to use the wireless signal processing unit to establish a first link with a first wireless terminal device and a second link with a second wireless terminal device. The management unit sets a first service period in a first cycle to provide the first wireless terminal device with a transmission opportunity for a first traffic, and a second service period in a second cycle to provide the second wireless terminal device with a transmission opportunity for a second traffic. The management unit manages a first transmission priority based on a delay requirement of the first traffic and a second transmission priority based on a delay requirement of the second traffic. When the management unit detects a conflict between the first service period and the second service period and determines that the first transmission priority is higher than the second transmission priority, the management unit notifies the second wireless terminal device of a change in the setting for the second service period. [Effects of the Invention]

[0006] The apparatus of the embodiment can control a plurality of wireless terminal devices to meet the delay requirements of the low-latency traffic of each of the wireless terminal devices. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a communication system according to the first embodiment. [Figure 2] FIG. 2 is a time chart showing an overview of the rTWT function of the communication system according to the first embodiment. [Figure 3] FIG. 3 is a block diagram showing an example of a hardware configuration of an access point included in the 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 communication system according to the first embodiment. [Figure 5] FIG. 5 is a block diagram showing an example of the functional configuration of an access point included in the communication system according to the first embodiment. [Figure 6]FIG. 6 is a block diagram showing an example of a functional configuration of a wireless terminal device included in the communication system according to the first embodiment. [Figure 7] FIG. 7 is a block diagram showing an example of the configuration of a channel access function of an access point included in the communication system according to the first embodiment. [Figure 8] FIG. 8 is a flowchart showing an example of a link setup method in the communication system according to the first embodiment. [Figure 9] FIG. 9 is a schematic diagram showing an example of a format of a beacon frame transmitted by an access point included in the communication system according to the first embodiment. [Figure 10] FIG. 10 is a table showing an example of link management information of an access point included in the communication system according to the first embodiment. [Figure 11] FIG. 11 is a flowchart showing an example of a method for setting an rTWT service period in the communication system according to the first embodiment. [Figure 12] FIG. 12 is a time chart showing a specific example of a frame exchange method using the rTWT function of the communication system according to the first embodiment. [Figure 13] FIG. 13 is a flowchart showing an example of a method for setting an rTWT service period in a communication system according to the second embodiment. [Figure 14] FIG. 14 is a time chart showing a specific example of a frame exchange method using the rTWT function of the communication system according to the second embodiment. [Figure 15] FIG. 15 is a block diagram showing an example of the configuration of a communication system according to the third embodiment. [Figure 16] FIG. 16 is a flowchart showing an example of a communication control method in the communication system according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Each 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, common reference numerals are used to designate components having the same function and configuration.

[0009] <1> First embodiment An access point included in a communication system 1 according to the first embodiment allocates a service period to a wireless terminal device during which traffic requiring low latency can be preferentially exchanged. When the service periods of multiple wireless terminal devices conflict with each other, the access point causes each wireless terminal device to transmit traffic in an order according to its transmission priority. Details of the communication system 1 according to the first embodiment are described below.

[0010] <1-1> Configuration <1-1-1> Overall configuration of communication system 1 Fig. 1 is a block diagram showing an example of the configuration of a communication system 1 according to the first embodiment. As shown in Fig. 1, the communication system 1 includes an access point AP and a wireless terminal device WTA.

[0011] The access point AP is a base station for a wireless LAN, etc. The access point AP is configured to be able to communicate wirelessly with the wireless terminal device WTA. The access point AP is also configured to be able to communicate with a server (not shown) on the network NW.

[0012] The wireless terminal device WTA is a wireless terminal such as a smartphone, a PC (Personal Computer), etc. The wireless terminal device WTA is configured to be able to communicate with a server on the network NW via an access point AP.

[0013] Communications between the access point AP and the wireless terminal device WTA conform to, for example, the IEEE 802.11 standard. The IEEE 802.11 standard has wireless communication functions based on the OSI (Open Systems Interconnection) reference model. In the OSI reference model, wireless communication functions are divided into seven layers (Layer 1: Physical Layer, Layer 2: Data Link Layer, Layer 3: Network Layer, Layer 4: Transport Layer, Layer 5: Session Layer, Layer 6: Presentation Layer, and Layer 7: Application Layer). The data link layer includes a Logical Link Control (LLC) sublayer and a Media Access Control (MAC) sublayer.

[0014] In the communication system 1, each of the access point AP and the wireless terminal device WTA supports a restricted-Target Wake Time (rTWT) function. The rTWT function is a function that allocates a service period to a predetermined wireless terminal device WTA during which low-latency traffic can be preferentially exchanged. Low-latency traffic is traffic (data) that meets a delay time requirement (delay requirement) required by an application. An overview of the rTWT function will be described below with reference to FIG. 2.

[0015] FIG. 2 is a time chart showing an overview of the rTWT function of the communication system 1 according to the first embodiment. As shown in FIG. 2, the access point AP sets an rTWT service period SP at a fixed cycle. The rTWT service period SP corresponds to a service period used for transmitting low-latency traffic. Hereinafter, the cycle in which the rTWT service period SP is set will be referred to as the "rTWT cycle." The interval between adjacent rTWT service periods SP will be referred to as the "rTWT interval TI." The rTWT interval TI corresponds to one cycle of the rTWT cycle. FIG. 2 shows the cycle of consecutive rTWT intervals TI among the rTWT cycles. <1> and T.I. <2> is displayed.

[0016] Each TWT interval TI includes an rTWT service period SP and a period OSP. The period OSP corresponds to a period that does not overlap with the rTWT service period SP, i.e., a period outside the rTWT service period SP. The rTWT service period SP is determined by an rTWT start time TS and an rTWT duration TD. The rTWT start time TS corresponds to the start time of the rTWT service period SP. The rTWT duration TD corresponds to the length of the rTWT service period SP starting from the rTWT start time TS.

[0017] During the rTWT service period SP, the access point AP preferentially provides frame exchange opportunities to wireless terminal devices WTA (STAa in FIG. 2) that support the rTWT function. The frame exchange opportunities correspond to opportunities for transmitting traffic (data) through frame exchange between the access point AP and the wireless terminal devices WTA. On the other hand, the access point AP sets a transmission suppression period QI for wireless terminal devices WTA (STAb in FIG. 2) that do not support the rTWT function. The transmission suppression period QI corresponds to a period during which traffic transmission between the access point AP and the wireless terminal devices WTA is suppressed. The transmission suppression period QI overlaps with the rTWT service period SP. Furthermore, the transmission suppression period QI is set to be the same length as or shorter than the rTWT service period SP.

[0018] The wireless terminal WTA may recognize a time based on the rTWT start time TS and the rTWT period (or rTWT interval TI) as the rTWT start time TS of the next rTWT service period SP. The wireless terminal WTA transmits low-latency traffic to the access point AP, for example, based on receiving a trigger frame from the access point AP during the rTWT service period SP. The trigger frame is a frame used when the access point AP requests the wireless terminal WTA to transmit traffic. The access point AP may transmit the trigger frame to the wireless terminal WTA at the rTWT start time TS. During the rTWT service period SP, the wireless terminal WTA can transmit low-latency traffic with priority, thereby improving the latency of the low-latency traffic.

[0019] The access point AP may set rTWT function parameters (hereinafter also referred to as "rTWT settings") such as the rTWT start time TS and the rTWT duration TD for each link or may manage them for each group of links. Frame exchange during the rTWT service period SP may be performed using CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance). The access point AP preferably sets the rTWT period to match the transmission period of low-latency traffic. For example, the access point AP may set the rTWT function parameters based on traffic attributes. In this case, the access point AP notifies a server on the network NW of the traffic type to acquire the corresponding traffic attributes. Then, the access point AP determines the rTWT function parameters based on the acquired traffic attributes. Examples of traffic attributes include the traffic occurrence interval and data volume notified by the application that generates the low-latency traffic.

[0020] <1-1-2> Hardware configuration of communication system 1 (Access point AP hardware configuration) Fig. 3 is a block diagram showing an example of a hardware configuration of an access point AP included in the communication system 1 according to the first embodiment. As shown in Fig. 3, the access point AP includes, for example, a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, a wireless communication module 14, and a wired communication module 15.

[0021] The CPU 11 is an integrated circuit capable of executing various programs and controls the overall operation of the access point AP. The ROM 12 is a non-volatile semiconductor memory that stores programs and control data for controlling the access point AP. The RAM 13 is, for example, a volatile semiconductor memory that is used as a work area for the CPU 11. The wireless communication module 14 is a circuit used for transmitting and receiving data via wireless signals and is configured to be connectable to an antenna. The wired communication module 15 is a circuit used for transmitting and receiving data via wired signals and is configured to be connectable to a network NW. The access point AP may have other hardware configurations. For example, when the access point AP is wirelessly connected to the network NW, the wired communication module 15 may be omitted from the access point AP.

[0022] (Hardware configuration of wireless terminal equipment WTA) 4 is a block diagram showing an example of a hardware configuration of the wireless terminal device WTA included in the communication system 1 according to the first embodiment. As shown in FIG. 4, the wireless terminal device WTA includes, for example, a CPU 21, a ROM 22, a RAM 23, a wireless communication module 24, a display 25, and a storage 26.

[0023] The CPU 21 is an integrated circuit capable of executing various programs and controls the overall operation of the wireless terminal device WTA. The ROM 22 is a non-volatile semiconductor memory that stores programs and control data for controlling the wireless terminal device WTA. The RAM 23 is, for example, a volatile semiconductor memory that is used as a work area for the CPU 21. The wireless communication module 24 is a circuit used to send and receive data via wireless signals and is configured to be connectable to an antenna. The display 25 displays, for example, a graphical user interface (GUI) corresponding to application software. The display 25 may also function as an input interface for the wireless terminal device WTA. The storage 26 is a non-volatile storage device that stores, for example, system software for the wireless terminal device WTA. Note that 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 25 may be omitted from the wireless terminal device WTA.

[0024] <1-1-3> Functional configuration of communication system 1 (Access point AP functional configuration) Fig. 5 is a block diagram showing an example of the functional configuration of an access point AP included in the communication system 1 according to the first embodiment. As shown in Fig. 5, the access point AP functions as a computer including, for example, an LLC processing unit 110, a data processing unit 120, a management unit 130, a MAC frame processing unit 140, and a radio signal processing unit 150. The LLC processing unit 110 is a functional block that executes processing corresponding to the LLC sublayer of the second layer and layers 3 to 7. The data processing unit 120, the management unit 130, and the MAC frame processing unit 140 are functional blocks that execute processing corresponding to the MAC sublayer of the second layer. The radio signal processing unit 150 is a functional block that executes processing corresponding to the MAC sublayer of the second layer and layer 1.

[0025] The LLC processing unit 110 generates LLC packets by, for example, adding a DSAP (Destination Service Access Point) header, an SSAP (Source Service Access Point) header, etc. to data received from the network NW. Then, the LLC processing unit 110 inputs the generated LLC packets to the data processing unit 120. The LLC processing unit 110 also extracts data from the LLC packets input from the data processing unit 120. Then, the LLC processing unit 110 transmits the extracted data to the network NW.

[0026] 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 extracts the LLC packet from the MAC frame input from the MAC frame processing unit 140. The data processing unit 120 then inputs the extracted LLC packet to the LLC processing unit 110. A MAC frame containing data is also called a "data frame."

[0027] The management unit 130 manages the state of the link between the access point AP and the wireless terminal device WTA. MAC frames containing management information related to the link, rTWT function, etc. are input and output between the management unit 130 and the MAC frame processing unit 140. MAC frames containing management information are also called "management frames." The management unit 130 includes, for example, link management information 131, a link control unit 132, a beacon management unit 133, and an rTWT setting management unit 134.

[0028] The link management information 131 includes information about the link between the access point AP and the wireless terminal device WTA connected wirelessly. The link management information 131 may also include information about rTWT function settings such as the rTWT start time TS, the rTWT duration TD, and transmission priority. The transmission priority indicates the priority of traffic to be transmitted when multiple wireless terminal devices WTA use the rTWT function and conflict occurs over the rTWT service period SP. The transmission priority is determined based on, for example, the delay requirement of low-latency traffic, the traffic priority (SCS: Stream Classification Service), and a TID (Traffic Identifier). The access point AP manages multiple wireless terminal devices WTA connected wirelessly using the link management information 131.

[0029] The link control unit 132 controls the establishment of a link between the access point AP and the wireless terminal WTA. For example, the link control unit 132 executes association processing and subsequent authentication processing in response to a connection request from the wireless terminal WTA. The link control unit 132 can control the state of the link established with the wireless terminal WTA.

[0030] The beacon management unit 133 manages information transmitted as beacons by the access point AP. The beacon management unit 133 also periodically generates management frames including management information and inputs the generated management frames to the MAC frame processing unit 140. The management frames generated by the beacon management unit 133 are also called "beacon frames." The management information transmitted as beacons by the beacon management unit 133 includes, for example, information related to the setting of the rTWT function. In other words, the beacon management unit 133 can notify the wireless terminal device WTA of the rTWT start time TS and the rTWT duration TD by a beacon.

[0031] The rTWT setting management unit 134 manages the rTWT setting for each set up single or multiple wireless terminal devices (WTAs) and the transmission priority of low-latency traffic. The transmission priority is a parameter that is uniquely determined by the rTWT setting management unit 134 based on, for example, an SCS or a TID (Traffic IDentifer). The rTWT setting management unit 134 may refer to conditions such as traffic delay requirements and jitter notified from an upper layer when determining the transmission priority. For example, the rTWT setting management unit 134 determines a higher transmission priority the more strict the delay requirement, and determines a higher transmission priority the more jitter. The rTWT setting management unit 134 may also determine the transmission priority of the STA function it manages based on notifications from other access points (APs), notifications from the STA function, or a predetermined management number. Furthermore, when multiple wireless terminal devices WTA use the rTWT function, the rTWT setting management unit 134 can check whether there is competition between the transmission of low-latency traffic during the rTWT service period SP among the multiple wireless terminal devices WTA. Then, the rTWT setting management unit 134 can change the setting of the rTWT function of each wireless terminal device WTA based on the check result and the transmission priority of the low-latency traffic of each wireless terminal device WTA. Details of this operation will be described later.

[0032] The MAC frame processing unit 140 inputs a MAC frame input from the data processing unit 120 or the management unit 130 to the radio signal processing unit 150 corresponding to the link associated with the MAC frame. Furthermore, the MAC frame processing unit 140 inputs the MAC frame input from the radio signal processing unit 150 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. Furthermore, if the MAC frame is a management frame, the MAC frame processing unit 140 inputs the MAC frame to the management unit 130.

[0033] The radio signal processing unit 150 transmits and receives radio signals via an antenna. Specifically, when transmitting a radio signal, the radio signal processing unit 150 performs carrier sensing to check the channel status. If the channel is busy, the radio signal processing unit 150 continues carrier sensing. If the channel is idle, the radio signal processing unit 150 generates a radio frame by adding a preamble or the like to the MAC frame input from the MAC frame processing unit 140. The radio signal processing unit 150 then converts the generated radio frame into a radio signal (wireless medium). The radio signal processing unit 150 then radiates (transmits) the converted radio signal via an antenna. On the other hand, when receiving a radio signal, the radio signal processing unit 150 converts the radio signal received via the antenna into a radio frame. The radio signal processing unit 150 then extracts the MAC frame from the converted radio frame and inputs the extracted MAC frame to the MAC frame processing unit 140.

[0034] The radio signal processing unit 150 may also be referred to as an "STA function." The conversion process from radio frames to radio signals performed by the radio signal processing unit 150 includes, for example, any of convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform, OFDM (Orthogonal Frequency Division Multiplexing) modulation, and frequency conversion. The conversion process from radio signals to radio frames performed by the radio signal processing unit 150 includes, for example, any of frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and Viterbi decoding. The access point AP may include multiple radio signal processing units 150 each handling a different channel, or multiple radio signal processing units 150 handling different frequency bands.

[0035] (Functional configuration of wireless terminal device WTA) FIG. 6 is a block diagram showing an example of the functional configuration of the wireless terminal device WTA included in the communication system 1 according to the first embodiment. As shown in FIG. 6, the wireless terminal device WTA functions as a computer including, 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 application execution unit 200 is a functional block that executes processing corresponding to layer 7. The LLC processing unit 210 is a functional block that executes processing corresponding to the LLC sublayer of layer 2 and layers 3 to 6. The data processing unit 220, the management unit 230, and the MAC frame processing unit 240 are functional blocks that execute processing corresponding to the MAC sublayer of layer 2. The radio signal processing unit 250 is a functional block that executes processing corresponding to the MAC sublayer of layer 2 and layer 1.

[0036] The application execution unit 200 executes an application based on data input from the LLC processing unit 210. The application execution unit 200 also inputs data to the LLC processing unit 210. For example, the application execution unit 200 can display application information on the display 25. The application execution unit 200 can also operate based on operations on an input interface.

[0037] The LLC processing unit 210 generates an LLC packet by adding a DSAP header, an SSAP header, and the like to the data input 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 extracts data from the LLC packet input from the data processing unit 120. Then, the LLC processing unit 210 inputs the extracted data to the application execution unit 200.

[0038] 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 extracts an LLC packet from the MAC frame input from the MAC frame processing unit 240. The data processing unit 220 then inputs the extracted LLC packet to the LLC processing unit 210.

[0039] The management unit 230 manages the state of the link between the access point AP and the wireless terminal device WTA. MAC frames including management information related to the link, rTWT function, etc. are input and output between the management unit 230 and the MAC frame processing unit 240. The management unit 230 includes, for example, link management information 231, a link control unit 232, and a beacon processing unit 233.

[0040] The link management information 231 includes information about the link between the wireless terminal WTA and the wirelessly connected access point AP. The link management information 231 may also include information about rTWT function settings such as the rTWT start time TS and the rTWT duration TD. Based on the link management information 231, the wireless terminal WTA can recognize the rTWT service period SP assigned to it.

[0041] The link control unit 232 controls the establishment of a link between the access point AP and the wireless terminal WTA. For example, the link control unit 232 executes an association process and a subsequent authentication process when transmitting a connection request to the access point AP. The link control unit 232 can control the state of the link established with the access point AP.

[0042] The beacon processing unit 233 processes information included in a beacon received from the access point AP. Specifically, the beacon processing unit 233 extracts management information related to the rTWT function from the beacon frame input from the MAC frame processing unit 240. Then, the beacon processing unit 233 associates, for example, the rTWT start time TS and the rTWT duration TD from the extracted management information related to the rTWT function with the link to which the rTWT function is applied, and records them in the link management information 231. In other words, the beacon processing unit 233 extracts information on a period during which low-latency traffic is transmitted (rTWT service period SP) from the received beacon, and reflects this information in the link management information 231. The beacon processing unit 233 may notify the data processing unit 220 of the management information related to the rTWT function.

[0043] The MAC frame processing unit 240 inputs a MAC frame input from the data processing unit 220 or the management unit 230 to the radio signal processing unit 250 corresponding to the link associated with the MAC frame. Furthermore, the MAC frame processing unit 240 inputs the MAC frame input from the radio signal processing unit 250 to the data processing unit 220, the management unit 230, or the radio signal processing unit 250 depending on the type of MAC frame. Specifically, if the MAC frame is a data frame, the MAC frame processing unit 240 inputs the MAC frame to the data processing unit 220. If the MAC frame is a management frame, the MAC frame processing unit 240 inputs the MAC frame to the management unit 230. For example, if the MAC frame is a beacon frame, the MAC frame processing unit 240 inputs the beacon frame to the beacon processing unit 233. If the MAC frame is a trigger frame, the MAC frame processing unit 240 outputs corresponding data to the radio signal processing unit 250.

[0044] The radio signal processing unit 250 transmits and receives radio signals via an antenna. Specifically, when transmitting a radio signal, the radio signal processing unit 250 performs carrier sensing to check the channel status. If the channel is busy, the radio signal processing unit 250 continues carrier sensing. If the channel is idle, the radio signal processing unit 250 generates a radio frame by adding a preamble or the like to the MAC frame input from the MAC frame processing unit 240. The radio signal processing unit 250 then converts the generated radio frame into a radio signal (wireless medium). The radio signal processing unit 250 then radiates (transmits) the converted radio signal via an antenna. On the other hand, when receiving a radio signal, the radio signal processing unit 250 converts the radio signal received via the antenna into a radio frame. The radio signal processing unit 250 then extracts the MAC frame from the converted radio frame and inputs the extracted MAC frame to the MAC frame processing unit 240.

[0045] The radio signal processing unit 250 may also be referred to as an "STA function." The conversion process from radio frames to radio signals performed by the radio signal processing unit 250 includes, for example, any of convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform, OFDM (Orthogonal Frequency Division Multiplexing) modulation, and frequency conversion. The conversion process from radio signals to radio frames performed by the radio signal processing unit 250 includes, for example, any of frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and Viterbi decoding. The access point AP may include multiple radio signal processing units 250 each handling a different channel, or multiple radio signal processing units 250 handling different frequency bands.

[0046] (Configuring the channel access function of the access point AP) Fig. 7 is a block diagram showing an example of the configuration of a channel access function of the access point AP according to the first embodiment. As shown in Fig. 7, the wireless signal processing unit 150 of the access point AP includes, for example, a classification unit 151, queues 152A, 152B, 152C, and 152D, carrier sense execution units 153A, 153B, 153C, and 153D, and an internal collision management unit 154.

[0047] When the MAC frame input from MAC frame processing unit 140 is a data frame, classification unit 151 classifies the data frame into a plurality of access categories: VO (Voice), VI (Video), BE (Best Effort), and BK (Background) based on the traffic type (TID) included in the MAC header. Then, classification unit 151 inputs the data frame to a corresponding queue 152 among a plurality of queues 152A, 152B, 152C, and 152D. In this example, classification unit 151 inputs data frames corresponding to access categories VO, VI, BE, and BK to queues 152A, 152B, 152C, and 152D, respectively. Furthermore, when the MAC frame input from MAC frame processing unit 140 is a high-priority frame such as a trigger frame, classification unit 151 inputs the high-priority frame to internal collision management unit 154, for example, without passing through queue 152. Note that LL (Low Latency) may be provided as an access category.

[0048] Each of the plurality of queues 152A, 152B, 152C, and 152D buffers input data frames. In this example, the plurality of queues 152A, 152B, 152C, and 152D buffers data frames corresponding to the access categories VO, VI, BE, and BK, respectively.

[0049] Each of the carrier sense execution units 153A, 153B, 153C, and 153D is associated with a corresponding queue 152A, 152B, 152C, and 152D. Each of the carrier sense execution units 153A, 153B, 153C, and 153D executes carrier sense based on CSMA / CA in accordance with preset access parameters. 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." Each of the carrier sense execution units 153A, 153B, 153C, and 153D acquires the right to transmit a data frame and terminates carrier sense when it determines that the channel has been idle for a predetermined period of time. Each of the carrier sense execution units 153A, 153B, 153C, and 153D ceases acquiring the right to transmit and terminates carrier sense when it determines that the channel is busy. The carrier sense execution unit 153 that has acquired the transmission right extracts a data frame from the associated queue 152 and outputs the extracted data frame to the internal collision management unit 154 .

[0050] The internal collision management unit 154 prevents transmission collisions when multiple carrier sense execution units 153 simultaneously acquire the transmission right. Specifically, when multiple data frames are input simultaneously, the internal collision management unit 154 prioritizes and outputs data frames of higher priority access categories. The data frames output from the internal collision management unit 154 are converted into wireless frames and transmitted via an antenna.

[0051] When a high-priority frame such as a trigger frame is input, the radio signal processing unit 150 performs carrier sensing and then transmits a radio signal including the high-priority frame via the antenna. Because carrier sensing is performed on the high-priority frame without going through the queue 152, the high-priority frame can be processed with less delay than other traffic. When transmitting a high-priority frame, the radio signal processing unit 150 may temporarily suspend carrier sensing for other queues 152. Furthermore, the radio signal processing unit 150 may generate a trigger frame based on the rTWT start time TS notified by the management unit 130.

[0052] Access parameters used in carrier sensing include, for example, CW (Contention Window) min, CW max, AIFS (Arbitration Inter Frame Space), and TXOP (Transmission Opportunity) Limit. The contention window is a parameter used to determine the transmission waiting time for collision avoidance. CW min and CW max indicate the minimum and maximum values ​​of the contention window, respectively. AIFS (Arbitration Inter Frame Space) indicates a fixed transmission waiting time set for each access category for collision avoidance control with priority control function. TXOP corresponds to the channel occupancy time. TXOP Limit indicates the upper limit value of TXOP. The shorter the CW min and CW max, the easier it is for the queue 152 to obtain the transmission right. The smaller the AIFS, the higher the priority of the queue 152. The larger the value of TXOP Limit, the larger the amount of data transmitted with one transmission right. Access parameters may also be called EDCA (Enhanced Distributed Channel Access) parameters.

[0053] In communication system 1, the configuration related to the channel access function of wireless terminal apparatus WTA is equivalent to the configuration related to the channel access function of access point AP. In this specification, the case where the channel access function of access point AP is implemented in wireless signal processing unit 150 has been described, but the channel access function of access point AP may also be implemented in MAC frame processing unit 140. Similarly, the channel access function of wireless terminal apparatus WTA may also be implemented in wireless signal processing unit 250 or MAC frame processing unit 240.

[0054] <1-2> Operation <1-2-1> How to set up a link Fig. 8 is a flowchart showing an example of a link setup method in the communication system 1 according to the first embodiment. A link setup method using the rTWT function will be described below with reference to Fig. 8. The link setup is performed, for example, by transmitting and receiving a management frame between the management unit 130 of the access point AP and the management unit 230 of the wireless terminal device WTA.

[0055] First, the wireless terminal WTA transmits (broadcasts) a probe request to the access point AP (S1). The probe request is a signal for checking whether or not the access point AP is present in the vicinity of the wireless terminal WTA.

[0056] When the access point AP receives the probe request, it transmits a probe response to the wireless terminal device WTA (S2). The probe response is a signal used in response to the probe request from the wireless terminal device WTA, and includes information necessary for establishing a link.

[0057] When the wireless terminal device WTA receives the probe response, it transmits an association request to the access point AP (S3). The association request is a signal requesting the access point AP to establish a link and includes information for link connection. When the rTWT function is used, the association request includes, for example, information regarding the generation period of low-latency traffic.

[0058] Upon receiving the association request, the access point AP executes association processing (S4), in which the access point AP establishes a wireless connection (link) with the STA function of the wireless terminal WTA.

[0059] Once the link is established, the access point AP sets up the rTWT function (S5). In setting up the rTWT function, the management unit 130 sets the rTWT start time TS, the rTWT duration TD, and the rTWT period, for example, in accordance with the generation period of the low-latency traffic. The access point AP may obtain information on the data generation period set in the application that generates the low-latency traffic from the wireless terminal device WTA and use this information in setting up the rTWT function. Any means may be used as a method for the access point AP to obtain the generation period of the low-latency traffic, etc.

[0060] When the setup of the rTWT function is completed, the access point AP updates the link management information 131 based on the settings of the established link and the settings of the rTWT function (S6).

[0061] When the update of the link management information 131 is completed, the access point AP transmits a link establishment response to the wireless terminal WTA (S7). The link establishment response is a signal used in response to the association request from the wireless terminal WTA.

[0062] When the wireless terminal device WTA receives the link establishment response from the access point AP, it updates the link management information 231 based on the link settings and rTWT function settings included in the received link establishment response (S8). This updates the link management information in both the access point AP and the wireless terminal device WTA, completing the link setup. Thereafter, the access point AP and the wireless terminal device WTA can perform data communication using the rTWT function.

[0063] The rTWT function setting may be changed after the link is established. The change in the rTWT function setting after the link is established may be initiated by the access point AP or may be initiated by the wireless terminal WTA. The access point AP may notify the wireless terminal WTA of the rTWT function setting using a beacon. The link setup may also be performed based on a beacon periodically transmitted by the access point AP. In this case, the wireless terminal WTA performs the process of S3 based on receiving the beacon. That is, the processes of S1 and S2 may be omitted. The channel to be used by the wireless terminal WTA may be determined by the access point AP or may be determined by the wireless terminal WTA. When the access point AP determines the channel, the access point AP may notify the wireless terminal WTA of the channel to be used by the wireless terminal WTA using a trigger frame or a beacon.

[0064] (Beacon frame format) 9 is a schematic diagram showing an example of the format of a beacon frame transmitted by the access point AP included in the communication system 1 according to the first embodiment. As shown in FIG. 9, the beacon frame includes, for example, a plurality of combinations of AID (Assosiation IDentifer) information and rTWT settings associated with the AID (for example, an rTWT start time TS, an rTWT duration TD, and a transmission suppression period QI).

[0065] The AID is an identifier of the wireless terminal device WTA that has established a link. The beacon frame shown in FIG. 9 includes an rTWT setting of AID#1 and an rTWT setting of AID#2. The wireless terminal device WTA can refer to the AID included in the beacon frame to determine whether the information is management information intended for the wireless terminal device WTA. The beacon frame may include an identifier of a group that shares the rTWT function setting instead of the AID. In this case, the access point AP transmits a beacon that includes information that combines the identifier of a group of wireless terminal devices WTA that share the rTWT function setting and the rTWT setting associated with that group.

[0066] Upon receiving the beacon, the beacon processor 233 of each wireless terminal apparatus WTA acquires the rTWT start time TS, the rTWT duration TD, and the transmission suppression period QI, and notifies the wireless signal processor 250. As a result, the access point AP can cause wireless terminal apparatuses WTA that support the rTWT function, among multiple wirelessly connected wireless terminal apparatuses WTA, to perform operations based on the rTWT settings, and cause wireless terminal apparatuses WTA that do not support the rTWT function to voluntarily suppress transmission of uplink data within the rTWT service period SP. On the other hand, wireless terminal apparatuses WTA that support the rTWT function and are not assigned communication within the set rTWT service period SP (i.e., wireless terminal apparatuses WTA that are not members of the rTWT service period SP) can suppress voluntarily transmission within the set rTWT service period SP by receiving the beacon.

[0067] The information indicating the transmission suppression period QI included in the beacon frame may be omitted, for example, when the rTWT duration period TD and the transmission suppression period QI are the same length. In this case, the wireless terminal device WTA sets the transmission suppression period QI to a period based on the rTWT start time TS and the rTWT duration period TD.

[0068] <1-2-2> How to replace the frame An example of a frame exchange method in the communication system 1 according to the first embodiment will be described below. In this example, an access point AP establishes links with three wireless terminal devices WTA using the same channel and receives low-latency traffic using the rTWT function. In the communication system 1 according to the first embodiment, the access point AP manages the priority of low-latency traffic for each link that uses the rTWT function.

[0069] Fig. 10 is a table showing an example of link management information 131 of the access point AP according to the first embodiment. As shown in Fig. 10, the link management information 121 includes information on, for example, a "link ID," a "channel ID," an "rTWT function," an "rTWT period," an "rTWT start time," and a "transmission priority."

[0070] The "Link ID" item indicates the identifier of the link associated with the STA function of each of the access point AP and the wireless terminal device WTA. In this example, STA1, STA2, and STA3 are assigned as link IDs corresponding to the three wireless terminal devices WTA. The "Channel ID" item indicates the identifier of the channel used for each link. In this example, a common channel CH1 is assigned to each of STA1, STA2, and STA3. The "rTWT function" item indicates whether the rTWT function is enabled. In this example, the rTWT function of each of STA1, STA2, and STA3 is enabled (Figure 2: Enabled).

[0071] The "rTWT period" item indicates the setting of the rTWT period. In this example, rTWT periods F1, F2, and F3 are set for STA1, STA2, and STA3, respectively. F1 is a period shorter than F2 and longer than F3. The "rTWT start time" item indicates the setting of the rTWT start time TS. In this example, rTWT start times TS1, TS2, and TS3 are set for STA1, STA2, and STA3, respectively, and TS1, TS2, and TS3 are set to the same time.

[0072] The "Transmission Priority" item indicates the transmission priority of low-latency traffic transmitted during the rTWT service period SP. In this example, transmission priorities P1, P2, and P3 are set for STA1, STA2, and STA3, respectively. Transmission priority P1 is higher than transmission priority P2. Transmission priority P2 is higher than transmission priority P3. The higher the transmission priority, the shorter the latency required for low-latency traffic. The transmission priority is calculated by the rTWT configuration management unit 134 based on information such as the requested latency time.

[0073] (How to set rTWT service period SP) 11 is a flowchart showing an example of a method for setting the rTWT service period SP in the communication system 1 according to the first embodiment. Below, the flow of setting the rTWT service period SP in the communication system 1 according to the first embodiment will be described with reference to FIG.

[0074] For example, when an access point AP establishes (starts) links using the rTWT function with multiple wireless terminal devices WTA, it checks whether scheduled rTWT service periods SP conflict (S11). For example, the access point AP determines that multiple rTWT service periods SP conflict if the rTWT start times TS of multiple links match. The access point AP may also determine that rTWT service periods conflict based on whether the rTWT service periods SP of multiple links overlap. Furthermore, the access point AP may also determine that the rTWT service periods SP do not conflict if the rTWT service periods SP of multiple links partially overlap but it is estimated that the transmission periods of low-latency traffic do not overlap.

[0075] In the process of S11, if it is determined that the scheduled rTWT service periods SP are not in conflict (S11: NO), the access point AP ends the series of processes shown in FIG. 11 (END).

[0076] If it is determined in the process of S11 that the scheduled rTWT service periods SP are in conflict (S11: YES), the access point AP checks the transmission priorities of the multiple STAs (wireless terminal devices WTA) that are in conflict with each other for the rTWT service periods SP (S12). After completing the process of S12, the access point AP proceeds to the process of S13.

[0077] In the process of S13, the access point AP notifies each of the multiple STAs competing for the rTWT service period SP of communication parameters based on the confirmed transmission priority (S13). The notified communication parameters are, for example, parameters for determining a transmission standby period from the start of the rTWT service period SP to the start of frame transmission. The access point AP may use a beacon frame or a management frame to notify the communication parameters. The wireless terminal apparatus WTA updates the link management information 231 based on the notified communication parameters. Specifically, the wireless terminal apparatus WTA extracts, for example, EDCA parameters from the communication parameters notified by the access point AP, and updates the communication parameters to be applied to the rTWT service period SP. When the process of S13 is completed, the access point AP ends the series of processes shown in FIG. 11 (end).

[0078] The access point AP may start the series of processes shown in Fig. 11 based on a preset schedule, or may execute the series of processes when the rTWT setting of one of the multiple wireless terminal devices WTA with which a link is established is updated. The timing at which the access point AP notifies the wireless terminal device WTA of the communication parameters in the process of S13 may be the rTWT start time TS. In the process of S13, notification of the communication parameters to the wireless terminal device WTA with the highest transmission priority may be omitted. The communication parameters that the access point AP instructs the wireless terminal device WTA to change in the process of S13 may be EDCA parameters such as a contention window, or may be fixed values ​​such as AIFS. (Example of frame replacement method) 12 is a time chart showing a specific example of a frame exchange method using the rTWT function of the communication system 1 according to the first embodiment. FIG. 12 shows frame exchange operations performed using the rTWT function between the access point AP and three wireless terminal devices WTA (STA1, STA2, and STA3). SP1-1 and SP1-2 correspond to the rTWT service period SP1 assigned to STA1. The start timing of SP1 is based on the rTWT cycle F1 of STA1. SP2-1 and SP2-2 correspond to the rTWT service period SP2 assigned to STA2. The start timing of SP2 is based on the rTWT cycle F2 of STA2. SP3-1, SP3-2, SP3-3, and SP3-4 correspond to the rTWT service period SP3 assigned to STA3. The start timing of SP3 is based on the rTWT cycle F3 of STA3.

[0079] As shown in FIG. 12, in this example, the rTWT start times TS1, TS2, and TS3 of STA1, STA2, and STA3 are the same. Therefore, the rTWT service periods SP1-1, SP2-1, and SP3-1 compete (overlap). Transmission priorities P1, P2, and P3 are set for STA1, STA2, and STA3, respectively. Therefore, the access point AP performs frame exchange in the order of priority: STA1, STA2, and STA3. Specifically, for example, the access point AP sets a longer AIFS for STA2 than for STA1, and sets a longer AIFS for STA3 than for STA2. The access point AP then notifies the corresponding STA functions of these communication parameters. Note that other access parameters may be used as the communication parameters set based on the transmission priority.

[0080] As a result, in the competing rTWT service periods SP1-1, SP2-1, and SP3-1, frame exchange opportunities (transmission opportunities) are given to STA1, STA2, and STA3 in that order. That is, the timing at which STA1 transmits its low-latency traffic in the rTWT service period SP1-1 is earlier than the timing at which STA2 transmits its low-latency traffic in the rTWT service period SP2-1. Also, the timing at which STA2 transmits its low-latency traffic in the rTWT service period SP2-1 is earlier than the timing at which STA3 transmits its low-latency traffic in the rTWT service period SP3-1. When the rTWT service periods SP are not competing, processing related to the transmission of low-latency traffic can start at the rTWT start time TS of each rTWT service period SP.

[0081] <1-3> Effects of the first embodiment According to the communication system 1 of the first embodiment, the access point AP can control the plurality of wireless terminal devices WTA so as to satisfy the delay requirements of the low-latency traffic of each of the plurality of wireless terminal devices WTA. The effects of the first embodiment will be described in detail below.

[0082] In wireless communication systems, the rTWT function is considered as a function to secure transmission opportunities for low-latency traffic with priority. An access point (AP) using the rTWT function sets the rTWT cycle to synchronize with periodically occurring low-latency traffic. For example, the access point (AP) sets up the rTWT function for each periodically occurring traffic type and sets the rTWT cycle for each traffic type.

[0083] However, depending on the occurrence cycles of multiple low-latency traffic streams, several low-latency traffic streams may occur at the same time. That is, there may be a conflict between multiple wireless terminal devices (WTAs) (STA functions) in transmitting low-latency traffic streams. In this case, channel access contention occurs to acquire the right to transmit frames during the conflicting rTWT service period SP. As a result, the access point AP may not be able to guarantee that traffic streams with strict delay requirements are given priority for transmission.

[0084] Therefore, in the communication system 1 according to the first embodiment, a transmission priority is determined for each low-latency traffic. Then, low-latency traffic transmitted within the same transmission period due to contention in the rTWT service period SP is transmitted in order of stricter delay requirement based on the transmission priority. Specifically, the access point AP notifies the corresponding STA function of the communication parameters for the rTWT service period SP determined based on the transmission priority. Then, each STA function attempts channel access using the notified communication parameters during the conflicting rTWT service period SP.

[0085] As a result, even when multiple low-latency traffics compete with each other, the communication system 1 according to the first embodiment can transmit traffic with stricter delay requirements with priority, thereby satisfying the delay requirements of the traffic. Therefore, the access point AP of the communication system 1 according to the first embodiment can control the multiple wireless terminal devices WTA so that the delay requirements of the low-latency traffics of each of the multiple wireless terminal devices WTA are satisfied.

[0086] <2> Second embodiment The communication system 1a according to the second embodiment has a configuration similar to that of the communication system 1 according to the first embodiment. The communication system 1a according to the second embodiment changes the rTWT settings of the wireless terminal devices WTA that compete for the rTWT service period SP based on the transmission priority. Details of the communication system 1a according to the second embodiment will be described below.

[0087] <2-1> How to replace the frame An example of a frame exchange method in the communication system 1a according to the second embodiment will be described below. In this example, an access point AP establishes links with three wireless terminal devices WTA using the same channel and receives low-latency traffic using the rTWT function.

[0088] (How to set rTWT service period SP) 13 is a flowchart showing an example of a method for setting the rTWT service period SP in the communication system 1a according to the second embodiment. Hereinafter, the flow of setting the rTWT service period SP in the communication system 1a according to the second embodiment will be described with reference to FIG.

[0089] As in the first embodiment, when the access point AP of the second embodiment establishes (starts) a link using the rTWT function with multiple wireless terminal devices WTA, it checks whether the scheduled rTWT service periods SP are in conflict (S11).

[0090] In the process of S11, if it is determined that the scheduled rTWT service periods SP are not in conflict (S11: NO), the access point AP ends the series of processes shown in FIG. 11 (END).

[0091] If it is determined in the process of S11 that the scheduled rTWT service periods SP are in conflict (S11: YES), the access point AP checks the transmission priorities of the multiple STAs (wireless terminal devices WTA) that are in conflict over the rTWT service periods SP (S12), as in the first embodiment. After completing the process of S12, the access point AP proceeds to the process of S21.

[0092] In the process of S21, the access point AP notifies each of the multiple STAs competing for the rTWT service period SP of the rTWT setting based on the confirmed transmission priority (S21). The access point AP may use a beacon frame or a management frame to notify the rTWT setting. The wireless terminal apparatus WTA updates the link management information 231 based on the notified rTWT setting. Specifically, the wireless terminal apparatus WTA extracts the TWT setting, such as the rTWT start time TS, from the communication parameters notified by the access point AP and reflects it in the link management information 231. When the process of S21 is completed, the access point AP ends the series of processes shown in FIG. 13 (end).

[0093] 13 based on a preset schedule, or may be executed when the rTWT setting of one of the wireless terminal devices WTA with which a link is established is updated. The access point AP according to the second embodiment may omit notifying the wireless terminal device WTA with the highest transmission priority of the rTWT setting in the process of S13.

[0094] (Example of frame replacement method) FIG. 14 is a time chart showing a specific example of a frame exchange method using the rTWT function of the communication system 1a according to the second embodiment. FIG. 14 shows frame exchange operations performed using the rTWT function between the access point AP and three wireless terminal devices WTA (STA1, STA2, and STA3). SP1-1 and SP1-2 correspond to the rTWT service period SP1 assigned to STA1. SP2-1a and SP2-2a correspond to the rTWT service period SP2 assigned to STA2. SP3-1a, SP3-2a, and SP3-3a correspond to the rTWT service period SP3 assigned to STA3. Note that SP2i indicates the rTWT service period SP2 of STA2 when the rTWT setting has not been changed from the initial setting. SP3i indicates the rTWT service period SP3 of STA3 when the rTWT setting has not been changed from the initial setting.

[0095] 14, in this example, the rTWT start times TS1, TS2, and TS3 of STA1, STA2, and STA3 are initially set to the same value. Therefore, the rTWT service periods SP1-1, SP2-1, and SP3-1 are initially set to conflict (overlap). In this case, the access point AP according to the second embodiment changes the rTWT settings based on the transmission priorities of STA1, STA2, and STA3.

[0096] Specifically, for example, the access point AP changes the rTWT start time of STA2 from TS2 to TS2a, which is later than TS2, and changes the rTWT start time of STA3 from TS3 to TS3a, which is later than TS3. Meanwhile, the access point AP maintains the rTWT start time TS1 of STA1, which has the highest transmission priority. In other words, the access point AP according to the second embodiment does not change the start time of the rTWT service period SP1, which has the highest transmission priority, from the scheduled time. Then, the access point AP delays the start times of the rTWT service periods SP of rTWT service periods SP2 and SP3 as the transmission priority decreases.

[0097] As a result, in the rTWT service periods SP1-1, SP2-1a, and SP3-1a, contention between STA functions (wireless terminal devices WTA) during the rTWT service period SP is resolved. The timing at which STA1 transmits its low-latency traffic during the rTWT service period SP1-1 is earlier than the timing at which STA2 transmits its low-latency traffic during the rTWT service period SP2-1a. The timing at which STA2 transmits its low-latency traffic during the rTWT service period SP2-1a is earlier than the timing at which STA3 transmits its low-latency traffic during the rTWT service period SP3-1a.

[0098] In addition, the communication system 1a may have an overlapping portion of the rTWT service period SP of each wireless terminal device WTA after the rTWT setting is changed, as long as frame exchange related to low latency traffic can be performed at the rTWT start time.

[0099] <2-2> Effects of the second embodiment As described above, the communication system 1a according to the second embodiment changes the start time (rTWT start time TS) of the rTWT service period SP based on the transmission priority when it determines that multiple rTWT service periods SP are competing at the same time.

[0100] As a result, even when multiple low-latency traffics compete with each other, the communication system 1a according to the second embodiment can transmit traffic with stricter delay requirements with priority, and can satisfy the delay requirements of the traffic. Therefore, the access point AP of the communication system 1 according to the second embodiment can control multiple wireless terminal devices WTA so that the delay requirements of each of the multiple low-latency traffics of the multiple wireless terminal devices WTA are satisfied, as in the first embodiment.

[0101] <3> Third embodiment In the communication system 2 according to the third embodiment, an external control device executes part of the processing of the access point AP described in the first or second embodiment. Details of the communication system 2 according to the third embodiment will be described below.

[0102] <3-1> Configuration Fig. 15 is a block diagram showing an example of the configuration of a communication system 2 according to the third embodiment. As shown in Fig. 15, the communication system 2 includes, for example, access points AP1 and AP2, wireless terminal devices WTA1 and WTA2, and a control device CNT.

[0103] The configuration of each of the access points AP1 and AP2 is, for example, similar to the configuration of the access point AP described in embodiment 1. The configuration of each of the wireless terminal devices WTA1 and WTA2 is, for example, similar to the configuration of the wireless terminal device WTA described in embodiment 1. The number of wireless terminal devices WTA connected to each access point AP may be two or more.

[0104] The control device CNT is a device that controls a plurality of access points AP. The control device CNT is configured to be able to communicate with each of the access points AP1 and AP2 via the network NW. The hardware configuration of the control device CNT has, for example, a configuration in which the wireless communication module 14 is omitted from the configuration of the access point AP shown in FIG. 3. The number of access points AP connected to the control device CNT may be one or three or more. Unlike the above, the control device CNT may be configured to be able to connect to the network NW or the access points AP via the wireless communication module 14. The control device CNT may have a function as an access point AP and may be called an "access point."

[0105] The control device CNT also has functions similar to the rTWT setting management unit 134 described in the first embodiment. The control device CNT can manage the rTWT setting of each access point AP belonging to the control device CNT. The rTWT setting of each access point AP may be notified to the control device CNT spontaneously by the access point AP that has set up a link with the wireless terminal device WTA, or may be notified to the control device CNT from the access point AP in response to a request from the control device CNT.

[0106] <3-2> Operation 16 is a flowchart showing an example of a communication control method in the communication system 2 according to the third embodiment. The flow of the communication control method in the communication system 2 according to the third embodiment will be described below with reference to FIG.

[0107] For example, when rTWT settings are notified (started) from multiple access points AP, the control device CNT checks whether or not rTWT service periods SP scheduled on the same channel CH conflict in each access point AP (S31). For example, the control device CNT determines that multiple rTWT service periods SP conflict when the rTWT start times TS assigned to the same channel CH are the same among multiple access points AP. The control device CNT may also determine that rTWT service periods conflict based on the overlap of rTWT service periods SP assigned to the same channel CH among multiple access points AP. Furthermore, the control device CNT may also determine that rTWT service periods SP do not conflict when it is estimated that the rTWT service periods SP assigned to the same channel CH among multiple access points AP partially overlap but the transmission periods of low-latency traffic do not overlap.

[0108] In the process of S31, if it is determined that the scheduled rTWT service periods SP are not in conflict (S31: NO), the control device CNT ends the series of processes shown in FIG. 16 (END).

[0109] In the process of S31, if it is determined that the scheduled rTWT service periods SP are in conflict (S31: YES), the control device CNT checks the transmission priorities of multiple STAs (i.e., STAs using the rTWT function at each access point AP) that are in conflict for the rTWT service periods SP (S32). After completing the process of S32, the control device CNT proceeds to the process of S33.

[0110] In the process of S33, the control device CNT notifies each of the multiple access points AP competing for the rTWT service period SP of communication parameters based on the confirmed transmission priority (S33). The notified communication parameters are, for example, parameters for determining a transmission standby period from the start of the rTWT service period SP to the start of frame transmission. The access point AP updates the link management information 131 based on the notified communication parameters. Then, the access point AP notifies the corresponding wireless terminal device WTA of the communication parameters notified by the control device CNT. When the process of S33 is completed, the control device CNT ends the series of processes shown in FIG. 16 (END).

[0111] 16 based on a preset schedule, or may be executed when the rTWT setting of one of a plurality of access points AP using the rTWT function is updated. In the process of S33, notification of communication parameters to the access point AP with the highest transmission priority may be omitted. The communication parameter that the control device CNT instructs the access point AP to change in the process of S33 may be an EDCA parameter such as a contention window, or may be a fixed value such as AIFS.

[0112] <3-3> Effects of the third embodiment As described above, in the communication system 2 according to the third embodiment, the control device CNT determines whether or not the rTWT service periods SP of multiple access points AP conflict with each other. If the control device 2 determines that the rTWT service periods SP conflict with each other, it changes the communication parameters of at least one access point AP based on the transmission priority.

[0113] As a result, the communication system 2 according to the third embodiment can suppress transmission delays of low-latency traffic caused by contention between multiple access points AP for channels CH that use the rTWT function. Therefore, the control device CNT of the communication system 2 according to the third embodiment can control multiple access points AP so as to satisfy the delay requirements of the low-latency traffic of each of multiple wireless terminal devices WTA.

[0114] In the third embodiment, the control device CNT notifies the access point AP of a change in communication parameters, but the present invention is not limited to this. The control device CNT may notify the access point AP of a change in rTWT settings instead of communication parameters. Even in such a case, the control device CNT in the third embodiment can suppress the transmission delay of low-latency traffic.

[0115] <4> others In the above embodiment, the access point AP may establish a multilink with the wireless terminal device WTA using multiple channels. Each of the access point AP and the wireless terminal device WTA may include multiple radio signal processing units (STA functions) corresponding to the multiple channels. When the multilink is established, a multilink association request and a multilink association process are performed using one of the multiple STA functions, instead of the processes of S3 and S4 shown in FIG. 9 . Note that when establishing the multilink, authentication and association processes for the other links constituting the multilink may be performed using the single link that is first established with the access point AP. When using the multilink, the communication system 1 may dynamically determine which link will be used for frame exchange for each rTWT service period SP. In the multilink, one or more STA functions may be assigned to one traffic type. 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. Without being limited to this, traffic of similar types (priority / non-priority, etc.) may be collected in a specific link that constitutes a multilink.

[0116] In the communication system 1, the CPU 11 included in the access point AP and the CPU 21 included in the wireless terminal device WTA may each be other circuits. For example, the access point AP and the wireless terminal device WTA may each be equipped with an MPU (Micro Processing Unit) instead of a CPU. The processes described in the embodiments may each be realized by dedicated hardware. The processes of the access point 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. The set of the data processing unit 120, management unit 130, and MAC frame processing unit 140 included in the access point AP may be referred to as a "link management unit." Similarly, the set of the data processing unit 220, management unit 230, and MAC frame processing unit 240 included in the wireless terminal device WTA may be referred to as a "link management unit."

[0117] 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 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 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 access point AP and the wireless terminal device WTA.

[0118] 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]

[0119] 1,2...Communication systems AP...Access point 11...CPU 12...ROM 13...RAM 14...Wireless communication module 15...Wired communication module 110...LLC Processing Section 120...Data processing unit 130...Management Department 131...Link management information 132...Link control unit 133...Beacon Management Department 134...rTWT settings management section 140...MAC frame processing unit 150...Radio signal processing unit 151...Classification section 152...Queue 153...Career Sense Executive Department 154…Internal conflict management department WTA: Wireless Terminal Equipment 21...CPU 22...ROM 23...RAM 24...Wireless communication module 25…Display 26…Storage 200...Application execution unit 210...LLC Processing Section 220...Data processing unit 230...Management Department 231...Link management information 232...Link control unit 233...Beacon processing unit 240...MAC frame processing unit 250...Radio signal processing unit CNT…controller

Claims

1. a management unit that manages a first service period during which a first wireless terminal device is provided with a transmission opportunity for a first traffic in a first cycle, and a second service period during which a second wireless terminal device is provided with a transmission opportunity for a second traffic in a second cycle; The management department managing a first transmission priority based on a delay requirement of the first traffic and a second transmission priority based on a delay requirement of the second traffic; detecting a conflict between the first service period and the second service period and, when it is confirmed that the first transmission priority is higher than the second transmission priority, notifying the second wireless terminal device of a change in setting related to the second service period; Access point.

2. the setting includes a parameter for determining a transmission waiting period from the start of the second service period to the start of frame transmission; when the first service period and the second service period conflict with each other, the management unit notifies the second wireless terminal device of a setting such that a transmission standby period applied to the second wireless terminal device in the second service period is longer than a transmission standby period applied to the first wireless terminal device in the first service period; The access point of claim 1 .

3. the settings include parameters for determining a start time of the second service period; when the first service period and the second service period conflict with each other, the management unit notifies the second wireless terminal device of a setting such that a start time of the second service period is later than a start time of the first service period. The access point of claim 1 .

4. the management unit determines each of the first transmission priority and the second transmission priority based on a traffic priority and a traffic type; The access point of claim 1 .

5. the management unit determines each of the first transmission priority and the second transmission priority based on a delay requirement or jitter of traffic notified from an upper layer; The access point of claim 1 .

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