Access point and wireless terminal device

Abstract

An access point of an embodiment includes communication circuitry and a processor. The communication circuit is configured to transmit and receive a wireless signal using a plurality of subcarriers. The processor is configured so as to establish a link with the plurality of wireless terminal devices using the communication circuit, set a plurality of units (RUs) obtained by grouping a plurality of subcarriers, and allocate a use for each of the plurality of units (RUs) in accordance with quality necessary conditions received from the plurality of wireless terminal devices. The plurality of wireless terminal devices are notified of information of the allocated use by using a trigger frame indicating the transfer period of the uplink frame.

Description

TECHNICAL FIELD

[0001] Embodiments relate to an access point and a wireless terminal device. BACKGROUND

[0002] As a communication system that makes a wireless connection between an access point and a wireless terminal device, a wireless LAN (Local Area Network) is known. The wireless terminal device is able to access a network via the access point within a communication area by using the wireless LAN. In addition, as a method of transmitting and receiving a low-delay traffic that requires a low delay between the access point and the wireless terminal device, an R-TWT (restricted target wake time) function is known. The access point using the R-TWT function sets a service period with a period corresponding to a required delay of the low-delay traffic, and notifies the set service period to the wireless terminal device using a beacon signal. Also, the access point prioritizes transmission and reception of the low-delay traffic in the service period set periodically. Thereby, it is possible to reduce the delay and jitter of the low-delay traffic.

[0003] PRIOR ART DOCUMENTS

[0004] NON-PATENT LITERATURE

[0005] Non-Patent Literature 1: IEEE 802.11be D4.0, “35.3 Multi-link operation, 35.8 Restricted TWT (R-TWT)”, p489-p580, p611-p616, July 2023 SUMMARY

[0006] However, as the low-delay traffic, not only a low-delay traffic that occurs periodically, but also a low-delay traffic that occurs non-periodically can exist. In the communication system, it is also desired to be able to satisfy the required delay with respect to the low-delay traffic that occurs non-periodically. In addition, in the communication system, it is also desired to be able to satisfy a quality necessary condition with respect to a traffic having the quality necessary condition in addition to the non-periodic low-delay traffic.

[0007] The present application has been achieved in view of the above-described circumstances, and an object thereof is to provide an access point and a terminal that are able to satisfy a quality necessary condition of a traffic.

[0008] The access point in this implementation includes a communication circuit and a processor. The communication circuit is configured to transmit and receive wireless signals using multiple subcarriers. The processor is configured to use the communication circuit to establish links with multiple wireless terminal devices, define multiple units obtained by grouping the multiple subcarriers, assign a purpose to each of the multiple units according to the quality requirements received from the multiple wireless terminal devices, and notify the multiple wireless terminal devices of the assigned purpose information using a trigger frame during the transmission of a frame indicating the uplink direction.

[0009] According to the implementation method, it is possible to provide access points and wireless terminal devices that can meet the quality requirements of services. Attached Figure Description

[0010] Figure 1 This is a block diagram illustrating an example of the structure of a communication system according to an embodiment.

[0011] Figure 2 This is a schematic diagram illustrating an example of a RU allocated a 20MHz frequency band.

[0012] Figure 3 This is a schematic diagram illustrating an example of the format of a wireless frame used in the communication system involved in the implementation.

[0013] Figure 4 This is a schematic diagram illustrating an example of the format of a trigger frame used in the communication system involved in the implementation.

[0014] Figure 5 This is a block diagram illustrating an example of the hardware structure of the access point involved in the implementation.

[0015] Figure 6 This is a block diagram illustrating an example of the hardware structure of a wireless terminal device according to an embodiment.

[0016] Figure 7 This is a block diagram illustrating an example of the functional structure of an access point involved in an implementation.

[0017] Figure 8 This is a block diagram illustrating an example of the structure of the channel access function of the access point according to the implementation method.

[0018] Figure 9 This is a block diagram illustrating an example of the functional structure of a wireless terminal device according to an embodiment.

[0019] Figure 10 This is a block diagram illustrating an example of the structure of the channel access function of the wireless terminal device according to the embodiment.

[0020] Figure 11This is a timing diagram illustrating an example of a downlink data transfer method using OFDMA in a communication system according to an embodiment.

[0021] Figure 12 This is a timing diagram illustrating an example of an uplink data transfer method using OFDMA in a communication system according to an embodiment.

[0022] Figure 13 This is a schematic diagram illustrating an example of the structure during OFDMA frame forwarding in a communication system according to an embodiment.

[0023] Figure 14 This is a flowchart illustrating an example of a negotiation method for allocating RUs by purpose, performed by the quality management department of the access point, as per the implementation embodiment.

[0024] Figure 15 This is a flowchart illustrating an example of a communication quality management method performed by the quality management department of an access point according to an embodiment.

[0025] Figure 16 This is a flowchart illustrating an example of a method for allocating RUs by the resource control unit of an access point according to an embodiment.

[0026] Figure 17 This is a flowchart illustrating an example of a method for generating trigger frames by the frame processing unit of an access point according to an embodiment.

[0027] Figure 18 This is a flowchart illustrating an example of an OFDMA frame generation method performed by the frame processing unit of an access point according to an embodiment.

[0028] Figure 19 This is a flowchart illustrating an example of a method for transmitting OFDMA frames in the downlink direction by the transmission and reception unit of an access point according to an embodiment.

[0029] Figure 20 This is a flowchart illustrating an example of a method for transmitting aperiodic low-latency services in the downlink direction by the transmission and reception unit of an access point, according to an embodiment.

[0030] Figure 21 This is a flowchart illustrating an example of a negotiation method for the allocation of RUs by purpose, performed by the quality management department of a wireless terminal device, as described in the embodiment.

[0031] Figure 22 This is a flowchart illustrating an example of a communication quality management method performed by the quality management department of a wireless terminal device according to an embodiment.

[0032] Figure 23 This is a flowchart illustrating an example of a method for obtaining and updating RU allocation information performed by the resource control unit of a wireless terminal device according to an embodiment.

[0033] Figure 24 This is a flowchart illustrating an example of a downlink frame processing method performed by the frame processing unit of a wireless terminal device according to an embodiment.

[0034] Figure 25 This is a flowchart illustrating an example of a method for processing uplink frames by the frame processing unit of a wireless terminal device according to an embodiment.

[0035] Figure 26 This is a flowchart illustrating an example of a method for receiving downlink frames performed by the transmitting and receiving unit of a wireless terminal device according to an embodiment.

[0036] Figure 27 This is a flowchart illustrating an example of a method for transmitting OFDMA frames in the uplink direction by the transmitting and receiving unit of a wireless terminal device according to an embodiment.

[0037] Figure 28 This is a flowchart illustrating an example of a method for transmitting uplink aperiodic low-latency services by the transmitting and receiving unit of a wireless terminal device according to an embodiment. Detailed Implementation

[0038] Hereinafter, embodiments will be described with reference to the accompanying drawings. The embodiments illustrate apparatuses and methods for embodying the technical concept of the invention. The drawings are schematic or conceptual diagrams. In the following description, common reference numerals are added to constituent elements having the same function and structure. Furthermore, when distinguishing multiple constituent elements having the same function and structure, a hyphen followed by a number is added to the end of the reference numeral.

[0039] <1> structure

[0040] First, the structure of the communication system 1 involved in the implementation method will be explained.

[0041] <1-1> Structure of Communication System 1

[0042] Figure 1 This is a block diagram illustrating an example of the structure of the communication system 1 according to an embodiment. For example... Figure 1 As shown, the communication system 1 includes an access point (hereinafter also referred to as "AP") 10 and at least one wireless terminal device 20. Figure 1In one example shown, three wireless terminal devices 20-1, 20-2, and 20-3 are wirelessly connected to access point 10.

[0043] Access point 10 is a base station for a wireless LAN. Access point 10 is configured to establish links with multiple wireless terminal devices 20 and communicate wirelessly with each of the established links. Additionally, access point 10 is configured to connect to a network NW and communicate with a server (not shown) on the network NW. Access point 10 and the network NW can be connected wirelessly or via a wired connection.

[0044] Wireless terminal device 20 is a wireless terminal such as a smartphone or PC (Personal Computer). Wireless terminal device 20 is configured to communicate with a server on network NW via access point 10 with a wireless connection. Hereinafter, wireless terminal devices 20-1, 20-2, and 20-3 that have established a link with access point 10 will also be referred to as "STA#1", "STA#2", and "STA#3", respectively.

[0045] The wireless communication between access point 10 and wireless terminal device 20 follows, for example, the IEEE 802.11 standard. The IEEE 802.11 standard provides wireless communication functionality based on the OSI (Open Systems Interconnection) reference model. In the OSI reference model, wireless communication functionality is divided into seven layers (Layer 1: Physical Layer, Layer 2: Data Link Layer, Layer 3: Network Layer, Layer 4: Transport Layer, Layer 5: Session Layer, Layer 6: Presentation Layer, Layer 7: Application Layer). The Data Link Layer includes the LLC (Logical Link Control) sublayer and the MAC (Media Access Control) sublayer. The LLC sublayer appends DSAP (Destination Service Access Point) headers, SSAP (Source Service Access Point) headers, etc., to the data input from the upper-level application, forming LLC data packets. The MAC layer appends MAC headers to the LLC data packets, forming MAC frames. This specification focuses on the processing of the MAC sublayers of layers 1 and 2, omitting the processing of other layers.

[0046] Access point 10 and wireless terminal device 20 both support Orthogonal Frequency Division Multiple Access (OFDMA) as wireless communication methods. OFDMA combines Orthogonal Frequency Division Multiplexing (OFDM) and Time Division Multiple Access (TDMA). OFDM divides the channel bandwidth allocated for wireless communication into multiple subcarriers (tones). OFDM allocates subcarriers to adjacent frequencies with orthogonal phases and partial overlap of frequency bands, thus achieving narrow-band subcarriers. TDMA divides the carriers used in communication into periods and allocates STAs for each period. Furthermore, OFDMA, as a combination of OFDM and TDMA, allocates the right to use each subcarrier according to time and distributes it to different STAs. OFDMA can finely vary the subcarrier allocation based on the radio wave conditions of each STA, improving radio wave utilization efficiency. In OFDMA, subcarriers are allocated to multiple STAs in units called RUs (resource units), which group the subcarriers that make up a channel. Furthermore, in OFDMA, data can be transmitted in parallel according to RU units.

[0047] Figure 2 This is a schematic diagram illustrating an example of a RU allocated a 20MHz frequency band. Figure 2 Example (A) illustrates the case where a 20MHz band is allocated to nine 26-toneRUs (#1 to #9), each consisting of 26 subcarriers. In this case, for each STA, any one of the nine 26-toneRUs (#1 to #9) is allocated. Figure 2 Example (B) illustrates the case where four 52-tone RUs (#1 to #4) are allocated to a 20MHz frequency band, each consisting of 52 subcarriers. In this case, for each STA, any one of the four 52-tone RUs (#1 to #4) is allocated. Figure 2 Example (C) illustrates the case where two 106-tone RUs, #1 and #2, each consisting of 106 subcarriers, are allocated to a 20MHz band. In this case, for each STA, either one of the two 52-tone RUs, #1 and #2, is allocated. Furthermore, RUs can also be composed of other numbers of subcarriers. For example, an RU can also be composed of more than 106 subcarriers. Additionally, multiple types of RUs consisting of different numbers of subcarriers can be allocated to the channel band allocated for wireless communication. The maximum number of RUs varies depending on the channel bandwidth allocated for wireless communication.

[0048] (The format of a wireless frame)

[0049] Figure 3 This is a schematic diagram illustrating an example of the format of a wireless frame used in the communication system 1 according to the embodiment. For example... Figure 3 As shown, a radio frame includes a preamble and a MAC frame. The preamble is placed at the beginning of the radio frame and includes a bit sequence indicating the start position of the radio frame. The MAC frame includes, for example, a MAC header, a payload, and an FCS (Frame Check Sequence) field. The MAC header stores information such as the frame type and data length. The payload stores information corresponding to the frame type, including LLC data packets in the case of transmitting data (services). The FCS field stores error detection codes used for error detection in the MAC header and payload. Furthermore, in communication system 1, access point 10 can control the transmission of uplink data (services) using STAs by using trigger frames. The format of the trigger frame will be described below.

[0050] Figure 4 This is a schematic diagram illustrating an example of the format of the trigger frame used in the communication system 1 according to the embodiment. For example... Figure 4 As shown, the trigger frame includes multiple fields such as the frame control field, duration field, first address field (RA: Receiver Address), second address field (TA: Transmitter Address), common information field, user information list field, padding field, and FCS (Frame Check Sequence) field. In this example, the group of frame control field, duration field, and address field corresponds to the MAC header, while the group of common information field, user information list field, and padding field corresponds to the payload.

[0051] The frame control field stores various control information. For example, it includes information indicating the frame type of the radio frame. The duration field indicates the planned period for using the radio line. The first and second address fields represent the BSSID (Basic Service Set Identifier), source address, destination address, sender terminal address, and receiver terminal address. The common information field represents information shared among multiple STAs. The user information list field represents information assigned to each STA. Padding is the area used to adjust the data length of the radio frame.

[0052] Common information fields include, for example, the trigger type subfield, the UL (Uplink) bandwidth subfield, and the maximum frame length subfield. The trigger type subfield indicates the type of trigger frame. The UL bandwidth subfield indicates the channel bandwidth available for frame transmission. The maximum frame length subfield indicates the maximum length of a frame that can meet the latency requirements of aperiodic low-latency services, as described later.

[0053] The user information list fields include, for example, an AID (Terminal Identifier) ​​subfield and an RU allocation subfield. Based on the STA information specified through the AID subfield and the RU location indicated by the RU allocation subfield, the RU allocation for each STA can be determined. That is, the STA can identify the RU allocation for its station through the AID subfield. Furthermore, the STA can identify the configuration of the RU allocated to its station through the RU allocation subfield.

[0054] The RU allocation subfield includes information related to the RU's purpose, RU identifier, and access category for each RU. The RU purpose includes information such as whether it is dedicated to a category shown in the access category, whether it is shared in a category with a higher priority than the category shown in the access category, whether it can start transmission en route to an OFDMA frame, and whether it is dedicated to a specific wireless terminal device 20 (represented by AID). OFDMA frames are allocated to subcarriers based on the RU allocation, corresponding to MAC frames that are the objects of transmission / reception using OFDMA. The RU identifier indicates the RU to which the allocation is made. Access categories include, for example, aperiodic low latency, deterministic low latency, video, audio, and best-effort service. Furthermore, hereinafter, the access category is sometimes abbreviated and referred to as "AC".

[0055] <1-2> Hardware Structure of Communication System 1

[0056] The hardware structure of the communication system 1 according to the embodiments will be described below.

[0057] <1-2-1> Hardware Structure of Access Point 10

[0058] Figure 5 This is a block diagram illustrating an example of the hardware structure of the access point 10 according to the embodiment. For example... Figure 5 As shown, the access point 10 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.

[0059] CPU 11 is an integrated circuit capable of executing various programs and controlling the overall operation of access point 10. ROM 12 is, for example, a non-volatile semiconductor memory that stores programs, control data, etc., used to control access point 10. RAM 13 is, for example, a volatile semiconductor memory, used as the operating area of ​​CPU 11. Wireless communication module 14 is configured to transmit and receive wireless signals via an antenna and is a circuit used to transmit and receive data, etc., between wireless terminal device 20 and wireless terminal device 20. Wired communication module 15 is a circuit used to transmit and receive data, etc., via wired signals and is configured to connect to network NW.

[0060] Furthermore, access point 10 can also be other hardware structures. For example, access point 10 can also be wirelessly connected to a network (NW). In this case, wired communication module 15 can be omitted from access point 10. The antenna can be built into access point 10 or externally connected to access point 10. CPU 11 can also be referred to as a "processor". Wireless communication module 14 can also be referred to as a "communication circuit".

[0061] <1-2-2> Hardware Structure of Wireless Terminal Device 20

[0062] Figure 6 This is a block diagram illustrating an example of the hardware structure of the wireless terminal device 20 according to an embodiment. For example... Figure 6 As shown, the wireless terminal device 20 includes, for example, a CPU 21, a ROM 22, a RAM 23, a wireless communication module 24, a display 25, and a storage device 26.

[0063] CPU 21 is an integrated circuit capable of executing various programs and controlling the overall operation of the wireless terminal device 20. ROM 22 is, for example, a non-volatile semiconductor memory that stores programs and control data used to control the wireless terminal device 20. RAM 23 is, for example, a volatile semiconductor memory used as the operating area of ​​CPU 21. The wireless communication module 24 is configured to transmit and receive wireless signals via an antenna and is a circuit used to transmit and receive data with access point 10. Display 25 displays, for example, a GUI (Graphical User Interface) corresponding to the application software. Storage device 26 is a non-volatile storage device, for example, storing system software of the wireless terminal device 20.

[0064] Furthermore, the wireless terminal device 20 can also be other hardware structures. For example, if the wireless terminal device 20 is an IoT (Internet of Things) terminal, the display 25 can be omitted from the wireless terminal device 20. The display 25 can also function as an input interface for the wireless terminal device 20. The antenna can be built into the wireless terminal device 20 or externally connected to it. The CPU 21 can also be referred to as a "processor". The wireless communication module 24 can also be referred to as a "communication circuit".

[0065] <1-3> Functional Structure of Communication System 1

[0066] The functional structure of the communication system 1 according to the implementation method is described below.

[0067] <1-3-1> Functional Structure of Access Point 10

[0068] Figure 7 This is a block diagram illustrating an example of the functional structure of the access point 10 according to an embodiment. For example... Figure 7 As shown, access point 10 functions, for example, as a computer equipped with an LLC processing unit 110, a link management unit 120, a frame processing unit 130, and a transmit / receive unit 140. The LLC processing unit 110 performs Layer 2 LLC sublayer processing and Layers 3 through 7 processing. The link management unit 120, frame processing unit 130, and transmit / receive unit 140 perform Layer 2 MAC sublayer processing. The transmit / receive unit 140 also performs Layer 1 processing.

[0069] LLC processing unit 110 appends DSAP headers, SSAP headers, etc., to the data received from network NW to generate LLC data packets. Then, LLC processing unit 110 inputs the generated LLC data packets to frame processing unit 130. Furthermore, LLC processing unit 110 extracts data from the LLC data packets input from frame processing unit 130. Finally, LLC processing unit 110 sends the extracted data to network NW.

[0070] The link management unit 120 manages the status of the link between the access point 10 and the wireless terminal device 20. The link management unit 120 can perform association processing and authentication processing based on connection requests from the wireless terminal device 20. Between the link management unit 120 and the frame processing unit 130, MAC frames containing information related to the link, OFDMA, etc., are input and output. The link management unit 120 includes a quality management unit 121 and a resource control unit 122.

[0071] The Quality Management Unit 121 exchanges quality requirements, such as latency, throughput, and packet arrival rate, with the Wireless Terminal Device 20 for low-latency services that occur aperiodically (hereinafter referred to as "aperiodic low-latency services"). Furthermore, based on the quality requirements received from the Wireless Terminal Device 20, the Quality Management Unit 121 requests necessary purpose-based RUs from the Resource Control Unit 122. Purpose-based RUs are RUs allocated according to each purpose of the service. Purpose-based RUs can include dedicated RUs, high-priority RUs, etc. Dedicated RUs are RUs allocated for use as aperiodic low-latency services regardless of whether there is service activity. High-priority RUs are RUs allocated for predetermined high-priority services. High-priority services, for example, correspond to categories with a priority of access category VI or higher. Information such as Preferred_AC can be attached to the purpose-based RUs. Preferred_AC indicates the access category that is preferentially transmitted in the corresponding RU.

[0072] Resource control unit 122 determines the RU allocation for uplink / downlink OFDMA frames. Resource control unit 122 then notifies frame processing unit 130 of the determined RU allocation. Hereinafter, information related to RU allocation will also be referred to as "RU allocation information." RU allocation information may include information related to the allocation of RUs for specific purposes, if the quality management unit 121 requests RUs for a particular purpose.

[0073] The frame processing unit 130 generates a MAC frame by appending a MAC header to the LLC data packet input from the LLC processing unit 110 according to the RU allocation notified by the resource control unit 122. The frame processing unit 130 then outputs the generated MAC frame to the transmit / receive unit 140. The frame processing unit 130 can also output a trigger frame generation instruction to the transmit / receive unit 140 based on information received from the link management unit 120. Furthermore, the frame processing unit 130 outputs the MAC frame input from the transmit / receive unit 140 to the LLC processing unit 110, the quality management unit 121, and the resource control unit 122, etc., depending on the type of the MAC frame. The frame processing unit 130 can also extract LLC data packets from the MAC frame and output the extracted LLC data packets to the LLC processing unit 110, etc.

[0074] The transmit / receive unit 140 performs CSMA / CA-based carrier sensing for each link and transmits MAC frames using the link that has obtained the transmission right. When transmitting MAC frames, the transmit / receive unit 140 generates radio frames by appending preambles or the like to the MAC frames input from the frame processing unit 130. Furthermore, the transmit / receive unit 140 converts the generated radio frames into radio signals (radio media) and transmits them via the antenna. The transmit / receive unit 140 can allocate OFDMA frames to subcarriers according to RU allocation and transmit them. The transmit / receive unit 140 can transmit trigger frames for uplink OFDMA frames. Additionally, the transmit / receive unit 140 converts radio signals received via the antenna into radio frames. Furthermore, the transmit / receive unit 140 extracts MAC frames from the converted radio frames and outputs them to the frame processing unit 130.

[0075] Furthermore, the transmit / receive unit 140 can also be referred to as "STA function". The conversion processing from radio frames to radio signals performed by the transmit / receive unit 140 includes, for example, any one of convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform, OFDM (Orthogonal Frequency Division Multiplexing) modulation, and frequency conversion. The conversion processing from radio signals to radio frames performed by the transmit / receive unit 140 includes, for example, any one of frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and Viterbi decoding. The access point 10 may also have multiple transmit / receive units 140 that handle different channels.

[0076] (Channel access function of access point 10)

[0077] Figure 8 This is a block diagram illustrating an example of the structure of the channel access function of the access point 10 according to the embodiment. For example... Figure 8 As shown, the transmitting and receiving unit 140 includes, for example, a classification unit 141, queues 142A, 142B, 142C and 142D, carrier sensing execution units 143A, 143B, 143C and 143D, and an internal conflict management unit 144.

[0078] The classification unit 141 classifies the MAC frames input from the frame processing unit 130 into multiple access categories VO (Voice), VI (Video), BE (Best Effort), BK (Background), and RT (Real Time) based on the Traffic ID (TID) included in the MAC header. Furthermore, the classification unit 141 inputs the MAC frames corresponding to the access categories VO, VI, BE, and BK into queues 142A, 142B, 142C, and 142D, respectively. Queues 142A, 142B, 142C, and 142D buffer the MAC frames corresponding to the access categories VO, VI, BE, and BK, respectively. Queues 142A, 142B, 142C, and 142D are associated with carrier sensing execution units 143A, 143B, 143C, and 143D, respectively.

[0079] Carrier sense execution units 143A, 143B, 143C, and 143D perform carrier sense based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) according to preset access parameters. Access parameters are set for each access category. For example, the access parameters are set to prioritize the transmission of radio signals in the order of "VO", "VI", "BE", and "BK". Carrier sense execution units 143A, 143B, 143C, and 143D suspend the acquisition of transmission rights when the channel state is busy during carrier sense, and acquire the right to transmit MAC frames when the channel state is idle for a predetermined time. The carrier sense execution unit 143 that has acquired the right to transmit retrieves the MAC frame from the associated queue 142 and outputs the retrieved MAC frame to the internal collision management unit 144.

[0080] The internal conflict management unit 144 prevents transmission conflicts when multiple carrier sensing execution units 143 simultaneously obtain transmission rights. Specifically, when multiple MAC frames are input simultaneously, the internal conflict management unit 144 prioritizes outputting the MAC frame with the higher priority access range. The MAC frame output from the internal conflict management unit 144 is converted into a radio frame after being appended with a preamble and transmitted via the antenna.

[0081] Furthermore, when a MAC frame input from the frame processing unit 130 is classified as an access category RT, the classification unit 141, after performing carrier sensing, inputs the MAC frame to the internal conflict management unit 144 without passing through each queue 142. MAC frames classified as access category RT are, for example, trigger frames, aperiodic low-latency services, and other high-priority frames. Regarding high-priority frames, carrier sensing is performed without passing through each queue 142, and because they have priority over other service categories, they are processed with low latency compared to other services. When transmitting high-priority frames, the transmission / reception unit 140 can also temporarily suspend carrier sensing by each carrier sensing execution unit 143. When the transmission / reception unit 140 is allocated a dedicated RU, it can also use the dedicated RU to transmit access category RT services without performing carrier sensing. The transmission / reception unit 140 can also generate trigger frames based on information notified from the frame processing unit 130.

[0082] Access parameters used in carrier sensing at the transmit / receive unit 140 of access point 10 include, for example, CW (contention window) min, CWmax, AIFS (arbitration interframe space), and TXOP (transmission opportunity) Limit. The contention window is a parameter used to determine the transmission waiting time for collision avoidance. CWmin and CWmax represent the minimum and maximum values ​​of the contention window, respectively. AIFS (arbitration interframe space) represents a fixed transmission waiting time set for each access category to enable collision avoidance control with priority control. TXOP corresponds to the channel occupancy time. TXOPLimit represents the upper limit of TXOP. The shorter CWmin and CWmax are, the easier it is for queue 142 to obtain the right to transmit. The smaller the AIFS is, the higher the priority of queue 142 becomes. The larger the value of TXOPLimit is, the more data is transmitted in a single transmission right. Access parameters can also be called EDCA (Enhanced Distributed Channel Access) parameters.

[0083] Furthermore, access point 10 can also have other functional structures as long as it can perform the actions described later. For example, the channel access function of access point 10 can be installed in frame processing unit 130 instead of transmission / reception unit 140. The transmission priority can also be determined based on the required delay of aperiodic low-latency services, the service priority (SCS: stream classification service), and the service category. Both uplink and downlink forwarding services can be executed by obtaining transmission rights through access point 10. In this case, access point 10 uses OFDMA frames for downlink service transmission and trigger frames for uplink service transmission. Access point 10 can also use common access parameters for both uplink and downlink to obtain transmission rights, alternating between transmitting OFDMA frames and trigger frames.

[0084] <1-3-2> Functional Structure of Wireless Terminal Device 20

[0085] Figure 9 This is a block diagram illustrating an example of the functional structure of the wireless terminal device 20 according to an embodiment. For example... Figure 9 As shown, the wireless terminal device 20 functions, for example, as a computer comprising an application execution unit 200, an LLC processing unit 210, a link management unit 220, a frame processing unit 230, and a transmission / reception unit 240. The application execution unit 200 performs processing corresponding to Layer 7. The LLC processing unit 210 performs processing at Layer 2 (LLC sublayer) and Layers 3 through 7. The link management unit 220, frame processing unit 230, and transmission / reception unit 240 perform processing at Layer 2 (MAC sublayer). The transmission / reception unit 240 also performs Layer 1 processing.

[0086] The application execution unit 200 executes the application based on the data input from the LLC processing unit 210. Additionally, the application execution unit 200 inputs data to the LLC processing unit 210. For example, the application execution unit 200 can display application information on the display 25. Furthermore, the application execution unit 200 can operate according to the operation of the input interface.

[0087] LLC processing unit 210 appends DSAP headers, SSAP headers, etc., to the data received from the network NW to generate LLC data packets. Then, LLC processing unit 210 inputs the generated LLC data packets to frame processing unit 230. Furthermore, LLC processing unit 210 extracts data from the LLC data packets input from frame processing unit 230. Finally, LLC processing unit 210 sends the extracted data to application execution unit 200.

[0088] The link management unit 220 manages the status of the link between the access point 10 and the wireless terminal device 20. The link management unit 220 can send connection requests to the access point 10 and perform association and authentication processing. Between the link management unit 220 and the frame processing unit 230, MAC frames containing information related to the link, OFDMA, etc., are input and output. The link management unit 220 includes a quality management unit 221 and a resource control unit 222.

[0089] The Quality Management Unit 221 exchanges quality-related conditions with Access Point 10, including the required latency of aperiodic low-latency services. The Quality Management Unit 221 can measure the measured latency of aperiodic low-latency services and notify Access Point 10. The Resource Control Unit 222 obtains RU allocation information notified from Access Point 10. Based on the obtained RU allocation information, it notifies the Frame Processing Unit 230 of the RU allocation.

[0090] The frame processing unit 230, based on the RU allocation notified by the resource control unit 222, appends a MAC header to the LLC data packet input from the LLC processing unit 210, thereby generating a MAC frame. The frame processing unit 230 then outputs the generated MAC frame to the transmit / receive unit 240. Depending on the type of the MAC frame, the frame processing unit 230 outputs the MAC frame input from the transmit / receive unit 240 to the LLC processing unit 210, the quality management unit 221, and the resource control unit 222, etc. The frame processing unit 230 may also extract LLC data packets from the MAC frame and output the extracted LLC data packets to the LLC processing unit 210, etc.

[0091] The transceiver unit 240 performs CSMA / CA-based carrier sensing for each link and transmits MAC frames using the link that has obtained the transmission right. When transmitting a MAC frame, the transceiver unit 240 adds a preamble or similar code to the MAC frame input from the frame processing unit 230 to generate a radio frame. The transceiver unit 240 then converts the generated radio frame into a radio signal (radio medium) and transmits it via the antenna. The transceiver unit 240 can allocate OFDMA frames to subcarriers according to RU allocation and transmit them. Additionally, the transceiver unit 240 converts the radio signal received via the antenna into a radio frame. Furthermore, the transceiver unit 240 extracts the MAC frame from the converted radio frame and outputs it to the frame processing unit 230.

[0092] Furthermore, the transceiver unit 240 can also be referred to as the "STA function". The STA function of the access point 10 and the STA function of the wireless terminal device 20 form a link in pairs. The conversion processing from wireless frames to wireless signals performed by the transceiver unit 240 includes, for example, any one of convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform, OFDM modulation, and frequency conversion. The conversion processing from wireless signals to wireless frames performed by the transceiver unit 240 includes, for example, any one of frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and Viterbi decoding. The wireless terminal device 20 may also have multiple transceiver units 240 that handle different channels.

[0093] (Channel access function of wireless terminal device 20)

[0094] Figure 10 This is a block diagram illustrating an example of the structure of the channel access function of the wireless terminal device 20 according to an embodiment. For example... Figure 10 As shown, the transmitting and receiving unit 240 includes, for example, a classification unit 241, queues 242A, 242B, 242C and 242D, carrier sensing execution units 243A, 243B, 243C and 243D, and an internal conflict management unit 244.

[0095] The classification unit 241 classifies the MAC frames input from the frame processing unit 230 into multiple access categories VO, VI, BE, BK, and RT based on the service category included in the MAC header. Furthermore, the classification unit 241 inputs the MAC frames corresponding to the access categories VO, VI, BE, and BK into queues 242A, 242B, 242C, and 242D, respectively. Queues 242A, 242B, 242C, and 242D buffer the MAC frames corresponding to the access categories VO, VI, BE, and BK, respectively. Queues 242A, 242B, 242C, and 242D are associated with carrier sensing execution units 243A, 243B, 243C, and 243D, respectively.

[0096] Carrier sensing execution units 243A, 243B, 243C, and 243D, similar to the transmit / receive unit 140 of access point 10, perform carrier sensing based on CSMA / CA according to preset access parameters. When the channel state is busy during carrier sensing, carrier sensing execution units 243A, 243B, 243C, and 243D respectively suspend the acquisition of transmission rights, and acquire the right to transmit MAC frames when the channel is idle for a predetermined time. The carrier sensing execution unit 243 that has acquired the transmission rights retrieves a MAC frame from the associated queue 242 and outputs the retrieved MAC frame to the internal conflict management unit 244.

[0097] The internal conflict management unit 244 prevents transmission conflicts when multiple carrier sensing execution units 243 simultaneously obtain transmission rights. Specifically, when multiple MAC frames are input simultaneously, the internal conflict management unit 244 prioritizes outputting the MAC frame with the higher priority access range. The MAC frame output from the internal conflict management unit 244 is converted into a radio frame after being appended with a preamble and transmitted via the antenna.

[0098] Furthermore, when a MAC frame input from the frame processing unit 230 is classified as an access category RT, the classification unit 241, after performing carrier sensing, inputs the MAC frame to the internal conflict management unit 244 without passing through each queue 242. MAC frames classified as access category RT are, for example, aperiodic low-latency services. Regarding aperiodic low-latency services, carrier sensing is performed without passing through each queue 242, and since it has priority over other service categories, it is processed with lower latency compared to other services. When transmitting aperiodic low-latency services, the transmission / reception unit 240 can also temporarily suspend carrier sensing by each carrier sensing execution unit 243. When the transmission / reception unit 240 is allocated a dedicated RU, it can also utilize the dedicated RU to transmit access category RT services without performing carrier sensing.

[0099] As access parameters used in carrier sensing in the transceiver unit 240 of the wireless terminal device 20, CWmin, CWmax, AIFS, and TXOPLimit are used, for example, the same as those used in the transceiver unit 140 of the access point 10. The shorter CWmin and CWmax are, the easier it is for queue 242 to obtain the right to transmit. The smaller AIFS is, the higher the priority of queue 242 becomes. The larger the value of TXOPLimit is, the more data is transmitted in one transmission right.

[0100] Furthermore, the wireless terminal device 20 can also have other functional structures as long as it can perform the operations described later. For example, the channel access function of the wireless terminal device 20 may be installed in the frame processing unit 230 instead of the transmission / reception unit 240. The transmission priority can also be determined based on the required delay of the aperiodic low-latency service, the priority of the service, and the service category. When the wireless terminal device 20 transmits an uplink service based on a trigger frame sent by the access point 10, it uses the RU corresponding to the RU allocation information notified by the access point 10 to transmit the service. The wireless terminal device 20 uses a dedicated RU to transmit the uplink aperiodic low-latency service. The wireless terminal device 20 uses a high-priority RU to transmit the uplink high-priority service. In addition, when multiple wireless terminal devices 20 use a common dedicated RU, in order to avoid conflicts with the aperiodic low-latency services of other wireless terminal devices 20, the dedicated RU may be used to transmit the aperiodic low-latency service after performing CSMA / CA-based carrier sensing. Similarly, when multiple wireless terminal devices 20 share a common high-priority RU, in order to avoid conflicts with the high-priority services of other wireless terminal devices 20, the high-priority RU can be used to send high-priority services according to carrier sensing based on CSMA / CA, a pre-determined terminal priority, or a scheduling method performed by the access point 10. That is, when multiple STAs or multiple service flows share a dedicated RU and / or a high-priority RU, random access can also be used.

[0101] <2> action

[0102] Next, the operation of the communication system 1 according to the implementation method will be described.

[0103] <2-1> Overview of OFDMA

[0104] Hereinafter, as an overview of OFDMA in the communication system 1 according to the embodiment, the downlink communication process, the uplink communication process, and the OFDMA frame forwarding period set in these communications will be described in sequence.

[0105] (Data forwarding method in the downlink direction)

[0106] Figure 11 This is a timing diagram illustrating an example of a downlink data transfer method using OFDMA in a communication system 1 according to an embodiment. Figure 11 This example illustrates the scenario of forwarding downlink data (services) between access point 10 (AP) and three wireless terminal devices 20 (STA#1~#3). For example... Figure 11As shown, when downlink traffic occurs, the AP sends a MU-RTS (multi-user request to send) to each of STAs #1 to #3. The MU-RTS is a frame used by the AP to reserve channels between the AP and multiple STAs when the AP begins forwarding downlink traffic to multiple STAs. The MU-RTS may include, for example, RU allocation information.

[0107] Each STA that receives the MU-RTS, and is capable of receiving downlink traffic, sends a CTS (clear toss) to the AP. Upon receiving a CTS from each STA#1 to #3, the AP uses the corresponding RU (i.e., at least one subcarrier) to send the data #1 to #3 stored in the OFDMA frame to STA#1 to #3 respectively. Figure 11 In this context, the period used when an AP sends an OFDMA frame to each STA is referred to as the "OFDMA frame transfer period".

[0108] Furthermore, after sending OFDMA frames to STAs #1 to #3, the AP also sends a MU-BAR (multi-user block acknowledgment request) to each of STAs #1 to #3. The MU-BAR is a frame used by the AP to request responses from multiple STAs simultaneously. Upon receiving the MU-BAR, each STA sends a BA (block acknowledgment) to the AP based on the OFDMA frame reception result. The AP then identifies that data #1 to #3 were successfully transmitted based on the BAs received from each STA. Thus, communication system 1 terminates downlink data forwarding using OFDMA.

[0109] Furthermore, during the OFDMA frame forwarding process in the downlink direction, the start time and transmission time of data #1 to #3 can differ. The AP can also independently send RTS and BAR for each STA. The timing of the AP receiving CTS from each STA can also differ. The timing of the AP receiving BA from each STA can also differ. The RU used in the OFDMA frame transmission can be allocated either for each service or for each STA.

[0110] (Data transfer method in the uplink direction)

[0111] Figure 12 This is a timing diagram illustrating an example of an uplink data transfer method using OFDMA in the communication system 1 according to the embodiment. Figure 12This example illustrates the transmission of uplink data between access point 10 (AP) and three wireless terminal devices 20 (STA#1~#3). For example... Figure 12 As shown, when an uplink service occurs, the AP will send the trigger frame to each of STAs #1 to #3.

[0112] Upon receiving the trigger frame, each STA, based on the RU allocation information stored in the trigger frame, uses its corresponding RU (i.e., at least one subcarrier) to send data to the AP. In this example, STAs #1 to #3 respectively send the data #1 to #3 stored in the OFDMA frame to the AP. Figure 12 In this context, the period used in the transmission of OFDMA frames from each STA to the AP is referred to as the "OFDMA frame transfer period".

[0113] Furthermore, after receiving OFDMA frames from each of STAs #1 to #3, the AP sends an M-BA (multi-STA BA) to each of STAs #1 to #3. The M-BA is a type of BA used by the AP to notify multiple STAs of successful data reception. Each STA, based on the M-BA received from the AP, identifies that data transmission for each of STAs #1 to #3 was successful. Thus, communication system 1 terminates its uplink data forwarding using OFDMA.

[0114] Furthermore, during OFDMA frame forwarding in the uplink direction, the start time and transmission time of data #1 to #3 can differ. The AP can also independently send trigger frames and BAs for each STA. The timing for each STA to receive trigger frames from the AP can also differ. The timing for each STA to receive BAs from the AP can also differ. The RUs used in OFDMA frame transmission can be allocated either for each service or for each STA.

[0115] (Structure during OFDMA frame transfer)

[0116] Figure 13 This is a schematic diagram illustrating an example of the structure during OFDMA frame forwarding in the communication system 1 according to the embodiment. Figure 13 This example illustrates the case where, after a certain period of time (IFS: interframe space) has elapsed since the trigger frame was received from the wireless terminal device 20, the OFDMA frame transfer period for the purpose-specific RU begins. The horizontal axis represents the time axis. For example... Figure 13 As shown, the OFDMA frame transfer period has, for example, the following structure: multiple transfer periods TP are divided in the time axis direction by RUs according to their purpose, and IFS are inserted between adjacent transfer periods TP.

[0117] Each forwarding period's TP is set to a delay shorter than the required delay for aperiodic low-latency services. Each forwarding period's TP is used to forward frames corresponding to RU#1 to RU#4. In this example, the four RU#1 to RU#4 are set as purpose-based RUs. For RU#1, a dedicated RU (dedicated) corresponding to aperiodic low-latency services is allocated. For RU#2, a high-priority RU (high-priority) corresponding to high-priority services is allocated. For RU#3, an RU (Any) is allocated that does not restrict the STA function that can be used by this RU. For RU#4, an RU (STA1) corresponding to STA1 is allocated. In this case, the following information (1) to (4) is stored, for example, in the user information list field of the triggering frame.

[0118] (1) AID=AID1 (dedicated RU and can be sent en route) RU=RU1, AC=aperiodic low latency

[0119] (2) AID=AID2 (high priority: AC lower limit specified), RU=RU2, AC=AC_VI

[0120] (3) AID=AID0 (either is acceptable), RU=RU3, AC=AC_BE

[0121] (4) AID=STA1, RU=RU4, AC=AC_BE

[0122] In setting (1), RU1 is designated as a dedicated RU for non-periodic low-latency services. In setting (2), RU2 is designated as an RU capable of sending services with an access scope having a priority of AC_VI or higher. Furthermore, the settings corresponding to AID in (1) to (4) can also be other settings. Multiple STAs can also be assigned to AID. The scope shown in AC represents Preferred_AC. In this way, access point 10 can specify the purpose of the RU in the trigger frame that initiates the uplink OFDMA frame by combining AID, RU allocation, and Preferred_AC.

[0123] As described above, in this example, multiple subcarriers are grouped, and multiple RUs are configured, including dedicated RUs associated with low-latency services and high-priority RUs associated with high-priority services. Furthermore, during OFDMA frame forwarding, the segmented forwarding periods (TPs) are sequentially arranged while IFS are inserted. Additionally, the number of forwarding periods (TPs) included in the OFDMA frame forwarding period may vary depending on the requirements of aperiodic low-latency services. For each forwarding period (TP), either multiple dedicated RUs or multiple high-priority RUs can be allocated. The combination of purpose-based RUs allocated to each forwarding period (TP) can be appropriately changed according to the quality requirements from the wireless terminal device 20.

[0124] <2-2> Actions of Access Point 10

[0125] Below, pay attention to Figure 7 The functional structure of the access point 10 shown illustrates the detailed operation of the access point 10 according to the embodiment. Furthermore, the interaction between each functional structure of the access point 10 and the STA is appropriately performed via the frame processing unit 130, the transmission / reception unit 140, etc.

[0126] <2-2-1> Actions of Quality Management Department 121

[0127] First, let me explain the actions of the quality management department 121 at access point 10.

[0128] (Dedicated RU allocation method)

[0129] Figure 14 This is a flowchart illustrating an example of a negotiation method for allocating RUs by purpose, performed by the quality management unit 121 of access point 10 (AP) according to an implementation embodiment. For example, when a non-periodic low-latency, high-priority service occurs after a link is established between the AP and STA, the quality management unit 121 begins... Figure 14 The flowchart shown is for the process (start).

[0130] First, the quality management unit 121 obtains the necessary quality conditions from the STA (S101). The necessary quality conditions are generated by the quality management unit 221 of the wireless terminal device 20. The frame type used to transmit the necessary quality conditions is not particularly limited. Services corresponding to the necessary quality conditions include aperiodic low-latency services, periodic services, and image services. The necessary quality conditions for aperiodic low-latency services include information related to the latency required in the transmission of the aperiodic low-latency service. The necessary quality conditions for periodic services include information related to the period of the periodic service. The necessary quality conditions for image services include information related to the image quality of the image service.

[0131] Next, the quality management unit 121 receives a request for allocation of RUs according to their purpose (S102). The request for allocation of RUs according to their purpose is generated by the quality management unit 221 of the wireless terminal device 20. There is no particular limitation on the frame type used to forward the request for allocation of RUs according to their purpose.

[0132] Next, the Quality Management Unit 121 determines whether a RU can be allocated according to its purpose (S103). The Quality Management Unit 121 determines whether a dedicated RU can be allocated based on the quality requirements of non-periodic low-latency services, and whether the remaining number of configurable dedicated RUs is exceeded. The number of configurable dedicated RUs can be preset by the AP or changed according to the number of STAs connected to the AP and the allocation of RUs. The Quality Management Unit 121 determines whether the required RUs can be allocated in accordance with the quality requirements of periodic services. The Quality Management Unit 121 determines whether the required RUs can be allocated in accordance with the quality requirements of image services. Furthermore, the Quality Management Unit 121 can allocate RUs required for service transmission either by targeting a specific wireless terminal device 20, or by obtaining the current status of the buffer from the wireless terminal device 20 each time and allocating RUs based on the obtained status.

[0133] In the processing of S103, if it is determined that a RU can be allocated according to its purpose (S103: "Yes"), the Quality Management Unit 121 sends a positive response to the STA (S104). Furthermore, the Quality Management Unit 121 requests the Resource Control Unit 122 to allocate a RU according to its purpose (S105). When allocating a RU according to its purpose, the Quality Management Unit 121 may also set a high-priority RU. For example, if there are insufficient resources among the allocated RUs according to their purpose, the Quality Management Unit 121 sets a high-priority RU. Afterwards, to determine whether frame segmentation is necessary, the Quality Management Unit 121 delays the notification of non-periodic low-latency service requests to the Resource Control Unit 122 and the Frame Processing Unit 130 (S106). Afterwards, the Quality Management Unit 121 concludes the process. Figure 14 A series of processes (end).

[0134] In the processing of S103, if it is determined that a RU cannot be assigned according to its purpose (S103: "No"), the Quality Management Department 121 sends a negative response to the STA (S107). Then, the Quality Management Department 121 concludes the process. Figure 14 A series of processes (end).

[0135] (Methods for managing communication quality)

[0136] Figure 15 This is a flowchart illustrating an example of a communication quality management method performed by the quality management unit 121 of the access point 10 (AP) according to an embodiment. For example, the quality management unit 121 begins, after the transfer of aperiodic low-latency services utilizing a dedicated RU is completed. Figure 15 The flowchart shown is for the process (start).

[0137] First, the Quality Management Department 121 obtains the measured latency values ​​for non-periodic low-latency services from the STA (S111). The measured latency values ​​are calculated by the STA. There are no particular restrictions on the frame type used to transmit the measured latency values.

[0138] Next, the Quality Management Department 121 evaluates whether the "required delay > measured delay" (S112). A measured delay greater than the required delay indicates that the delay time when transferring non-periodic low-latency services does not meet the necessary conditions required by the STA.

[0139] In the processing of S112, if the "required delay > measured delay value" does not occur (S112: "No"), the Quality Management Department 121 requests the Resource Control Department to increase the allocation of a dedicated RU (S113). That is, based on communication quality, the Quality Management Department 121 requests the Resource Control Department 122 to increase the allocation of a dedicated RU. Furthermore, the Quality Management Department 121 terminates the process. Figure 15 A series of processes (end).

[0140] In the processing of S112, if the condition becomes "required delay > measured delay value" (S112: "Yes"), the Quality Management Department will conclude at step 121. Figure 15 A series of processes (end).

[0141] Furthermore, the Quality Management Unit 121 can execute the individual processes of S112 and S113 either each time a delay measurement value is obtained from the STA, or periodically. When multiple delay measurement values ​​are obtained, the Quality Management Unit 121 can also compare parameters based on the average, minimum, or maximum value of the multiple obtained delay measurement values, jitter, etc., and the required delay during the S112 process. Additionally, the Quality Management Unit 121 can determine whether it is necessary to allocate more dedicated RUs based on the use of high-priority RUs. This is because using high-priority RUs indicates that the originally allocated RUs for specific purposes compete with other wireless terminal devices 20.

[0142] <2-2-2> Operations of Resource Control Department 122

[0143] Next, the operation of the resource control unit 122 of access point 10 will be explained.

[0144] Figure 16 This is a flowchart illustrating an example of a method for allocating RUs by the resource control unit 122 of the access point 10 (AP) according to an embodiment. After the link between the AP and the STA is established, the resource control unit 122, for example, starts based on an RU allocation request from the STA. Figure 16 The flowchart shown is for the process (start).

[0145] First, the resource control unit 122 confirms whether a request for the allocation of RUs by purpose has been made (S121). The allocation request for RUs by purpose can also be generated by the quality management unit 121. There are no particular limitations on the frame type used to forward the RU allocation request.

[0146] In the processing of S121, if a request is made to allocate RUs according to their purpose (S121: "Yes"), the resource control unit 122 allocates RUs according to their purpose based on the request (S122). Then, the resource control unit 122 handles the allocation of remaining RUs (S123). Afterwards, the resource control unit 122 notifies the frame processing unit 130 of the allocated RU information (S124). Finally, the resource control unit 122 terminates the process. Figure 16 A series of processes (end).

[0147] In the processing of S121, if no RU allocation based on purpose is requested (S121: "Yes"), the resource control unit 122 handles all RU allocation services (S122). Then, the resource control unit 122 proceeds to the processing of S124, notifying the frame processing unit 130 of the allocated RU information. Afterwards, the resource control unit 122 terminates. Figure 16 A series of processes (end).

[0148] Furthermore, the resource control unit 122 can also increase the allocation of purpose-based RUs in the processing of S122 according to the request from the quality management unit 121 in the order of 26-tone, 52-tone, 106-tone, ... . In allocations other than purpose-based RUs, the resource control unit 122 can also perform channel estimation between the STA and other components, and prioritize the allocation of RUs suitable for each STA when suitable RUs for each STA are available. If there are services requiring latency in addition to aperiodic low-latency services, the resource control unit 122 can also prioritize the allocation of RUs for those services. In addition, the resource control unit 122 can also allocate RUs for each OFDMA frame based on the buffer accumulation status of downlink and uplink services.

[0149] <2-2-3> Operation of Frame Processing Unit 130

[0150] Next, the operation of the frame processing unit 130 of access point 10 will be explained.

[0151] (Situation of sending downlink services)

[0152] Figure 17 This is a flowchart illustrating an example of a method for generating trigger frames by the frame processing unit 130 of the access point 10 (AP) according to an embodiment. The frame processing unit 130 starts, for example, when a service occurs after a link is established between the AP and the STA.Figure 17 The flowchart shown is for the process (start).

[0153] First, the frame processing unit 130 generates a MAC frame for each service simultaneously transmitted via OFDMA (S131). In the processing of S131, the frame processing unit 130 can generate multiple MAC frames based on the number of services transmitted simultaneously. Furthermore, a MAC header is appended when generating the MAC frame.

[0154] Next, the frame processing unit 130 confirms whether the generated MAC address frame corresponds to an aperiodic low-latency service (S132). The processing of S132 is performed on each of the multiple MAC frames generated in the processing of S131.

[0155] In the processing of S132, if it is confirmed that the service corresponds to a non-periodic low-latency traffic (S132: "Yes"), the frame processing unit 130 outputs the generated MAC frame along with RU allocation information to the transmit / receive unit 140 (S133). The RU allocation information in the processing of S133 includes allocation information for RUs other than dedicated RUs. Then, the frame processing unit 130 ends. Figure 17 A series of processes (end).

[0156] In the processing of S132, if it is confirmed that the service does not correspond to an aperiodic low-latency service, i.e., the service being processed is not an aperiodic low-latency service (S132: "No"), the frame processing unit 130 outputs the generated MAC frame, RU allocation information, and requested delay to the transmit / receive unit 140 (S134). The RU allocation information in the processing of S134 includes the allocation information of dedicated RUs. Then, the frame processing unit 130 ends. Figure 17 A series of processes (end).

[0157] (Instructions for STA to send uplink traffic)

[0158] Figure 18 This is a flowchart illustrating an example of an OFDMA frame generation method performed by the frame processing unit 130 of the access point 10 (AP) according to an embodiment. The frame processing unit 130, for example, begins... Figure 18 The flowchart shown is for the process (start).

[0159] First, the frame processing unit 130 confirms whether a purpose-based RU has been allocated (S141). For example, the frame processing unit 130 confirms whether an RU for transferring non-periodic low-latency services between AP and STA has been allocated.

[0160] In the processing of S141, if it is confirmed that a purpose-based RU has been allocated (S141: "Yes"), the frame processing unit 130 generates purpose-based RU allocation information according to the notification from the resource control unit 122 and saves it to the RU allocation subfield (S142). Furthermore, the frame processing unit 130 calculates the maximum frame length based on the required delay and saves it to the maximum frame length subfield (S143). The maximum frame length information corresponds, for example, to the maximum value of the frame length that can meet the required delay of aperiodic low-latency services. Alternatively, the maximum frame length information may also correspond to a value smaller than the maximum value of the frame length that can meet the required delay of aperiodic low-latency services. Afterwards, the frame processing unit 130 adds a MAC header, etc., to generate a trigger frame and outputs it to the transmit / receive unit 140 (S144). Then, the frame processing unit 130 concludes. Figure 18 A series of processes (end).

[0161] In the process of S141, if it is confirmed that no RU has been allocated according to its purpose (S141: "No"), the frame processing unit 130 generates RU allocation information according to the notification from the resource control unit 122 and saves it to the RU allocation subfield (S146). The RU allocation information generated by the process of S146 does not include information related to RUs according to their purpose. Then, the frame processing unit 130 proceeds to the process of S144, attaches a MAC header, etc. to generate a trigger frame, and outputs it to the transmit / receive unit 140. After that, the frame processing unit 130 ends. Figure 18 A series of processes (end).

[0162] As described above, the frame processing unit 130 can notify the STA of the RU allocation in the uplink OFDMA by sending a trigger frame to the STA. In addition, the RU allocation information and maximum frame length information stored in the trigger frame can also be generated by the link management unit 120.

[0163] (The case of receiving uplink frames)

[0164] When a frame is received from the transmit / receive unit 140, the frame processing unit 130 performs MAC header processing, etc. Furthermore, the frame processing unit 130 outputs the information contained in the processed frame to the network NW via the LLC processing unit 110, etc. If the received frame is a data frame, the frame processing unit 130 outputs the received frame to the network NW. Additionally, if the received frame is a purpose-specific RU allocation request from a STA, or a communication quality report (e.g., measured delay value), the frame processing unit 130 outputs the received frame to the quality management unit 121. In this way, the frame processing unit 130 can select a suitable output destination to output the received frame based on the type of uplink frame.

[0165] <2-2-4> Operation of the transmitting and receiving unit 140

[0166] Next, the operation of the transmitting and receiving unit 140 of access point 10 will be explained.

[0167] (Method for transmitting OFDMA frames in the downlink direction)

[0168] Figure 19 This is a flowchart illustrating an example of a method for transmitting downlink OFDMA frames by the transmission and reception unit 140 of the access point 10 (AP) according to an embodiment. The transmission and reception unit 140, for example, begins to transmit a MAC frame corresponding to a downlink service when it is input. Figure 19 The flowchart shown is for the process (start).

[0169] First, the transmitting and receiving unit 140 matches the MAC frame input from the frame processing unit 130 with the subcarrier according to the RU allocation information (S151). The transmitting and receiving unit 140 can match the input MAC frame with the subcarrier according to the information notified by the frame processing unit 130, the link management unit 120, etc., or according to the information stored in the RU allocation subfield.

[0170] Next, the transmitting and receiving unit 140 calculates the transmission time required (S152). The transmission time required can be estimated based on the size of the MAC frame to be transmitted, the number of sub-channels used in the transmission of the MAC frame, etc.

[0171] Next, the transmitting and receiving unit 140 evaluates whether the "required delay > transmission time" (S153).

[0172] In the processing of S153, if the "required delay > transmission time" condition is not met (S153: "No"), the transmission receiving unit 140 segments the frame (S154). The period used to transmit the segmented frame is... Figure 13 The transfer period TP is shown. Furthermore, the transmit / receive unit 140 appends a preamble including RU allocation information to each segmented frame (S155). Then, using the allocated RUs, the transmit / receive unit 140 continuously transmits the segmented frames while setting an inter-frame wait period (IFS) (S156). Afterwards, the transmit / receive unit 140 terminates. Figure 19 A series of processes (end).

[0173] In the processing of S153, if the required delay is greater than the transmission time (S153: "Yes"), the transmit / receive unit 140 uses the allocated RU to transmit the frame (S157). Furthermore, when processing of S157 is performed, frame segmentation is unnecessary, and the required delay for aperiodic low-latency services can be met. Afterwards, the transmit / receive unit 140 terminates. Figure 19 A series of processes (end).

[0174] Furthermore, the "transmission" step in each of the processes in S155 and S156 includes the process of adding a preamble to the MAC frame to generate a radio frame, and radio signal processing. The acquisition of transmission rights in the transmission / reception unit 140 is based, for example, on CSMA / CA. The transmission / reception unit 140 is configured to delay the transmission of segmented frames until the reception of the uplink service is completed if uplink traffic is detected during the IFS (waiting period) of OFDMA frame transfer.

[0175] (Transmission method for non-periodic low-latency services in the downlink direction)

[0176] Figure 20 This is a flowchart illustrating an example of a method for transmitting downlink aperiodic low-latency services by the transmit / receive unit 140 of the access point 10 (AP) according to an embodiment. For example, when a MAC frame corresponding to a downlink aperiodic low-latency service is input, the transmit / receive unit 140 begins... Figure 20 The flowchart shown is for the process (start).

[0177] First, the transmitting and receiving unit 140 maps the input MAC frame to the subcarrier of the dedicated RU (S161). The transmitting and receiving unit 140 can map the input MAC frame to the subcarrier based on information notified by the frame processing unit 130, the link management unit 120, etc., or based on information stored in the RU allocation subfield.

[0178] Next, the transmitting / receiving unit 140 appends a preamble to the MAC frame (S162). Through the processing in S162, a radio frame is generated. Furthermore, the transmitting / receiving unit 140 confirms the communication status (S163). In the processing in S163, the transmitting / receiving unit 140, for example, confirms the communication status of each of the multiple RUs.

[0179] In the processing of S163, if it is confirmed that a downlink OFDMA frame is being transmitted, the transmit / receive unit 140 uses the allocated dedicated RU to transmit aperiodic low-latency services (S164). For example, if the transmit / receive unit 140 is transmitting downlink services using an RU other than a dedicated RU, it uses a dedicated RU in parallel with the transmission of that service to transmit the occurring low-latency service to any one of the multiple STAs. After that, the transmit / receive unit 140 ends. Figure 20 A series of processes (end).

[0180] In the S163 process, if it is confirmed that an uplink OFDMA frame is being received, the transmit / receive unit 140 waits until the reception of the OFDMA frame is completed or a waiting period is detected (S165). Furthermore, when the reception of the OFDMA frame is completed or a waiting period is detected, the transmit / receive unit 140 proceeds to the S164 process, using the allocated dedicated RU to transmit aperiodic low-latency services. Afterwards, the transmit / receive unit 140 terminates. Figure 20 A series of processes (end).

[0181] As described above, when the transmission and reception unit 140 receives an aperiodic low-latency service from the frame processing unit 130, it processes the service according to the transmission status. To shorten the latency of the aperiodic low-latency service, it is preferable to execute the processing in S164 quickly.

[0182] (Methods for receiving uplink traffic, etc.)

[0183] When the transceiver unit 140 receives a wireless signal via the antenna, it performs wireless signal processing. Furthermore, the transceiver unit 140 extracts a MAC frame from the wireless signal through wireless signal processing and outputs the extracted MAC frame to the frame processing unit 130. In this way, the transceiver unit 140 can receive uplink services, etc.

[0184] <2-3> Operation of Wireless Terminal Device 20

[0185] Below, pay attention to Figure 9 The functional structure of the wireless terminal device 20 shown will be explained, and the detailed operation of the wireless terminal device 20 according to the embodiment will be described. Furthermore, it is assumed that the interaction between each functional structure of the wireless terminal device 20 and the access point 10 is appropriately performed via the frame processing unit 230, the transmission and reception unit 240, etc.

[0186] <2-3-1> Actions of Quality Management Department 221

[0187] First, let me explain the operation of the quality management department 221 of the wireless terminal device 20.

[0188] (Dedicated RU allocation method)

[0189] Figure 21 This is a flowchart illustrating an example of a negotiation method for allocating RUs according to their intended use, performed by the quality management unit 221 of the wireless terminal device 20 (STA) as described in the embodiment. For example, after a link is established between the AP and the STA, the quality management unit 221 begins, when a low-latency service, such as an aperiodic low-latency service, is anticipated to occur. Figure 21 The flowchart shown is for the process (start).

[0190] First, the Quality Management Department 221 notifies the AP of the necessary quality conditions (S201). For example, the necessary quality conditions are forwarded from the upper layer along with services such as non-periodic low-latency services. The necessary quality conditions for non-periodic low-latency services include, for example, data rate and required latency. The necessary quality conditions for periodic low-latency services include, for example, data rate and service occurrence cycle. The necessary quality conditions for image services include, for example, data rate and required latency. Next, the Quality Management Department 221 sends a request for allocation of RUs according to their purpose to the AP (S202). Alternatively, the Quality Management Department 221 may send the necessary quality conditions and the request for allocation of RUs according to their purpose together with the AP. Then, the Quality Management Department 221 waits until it receives a response from the AP (S203).

[0191] Upon receiving a response from the AP, the Quality Management Department 221 identifies whether a RU (Respondent Unit) has been assigned according to its purpose (S204) based on the AP's response. For example, if a positive response is received, the Quality Management Department 221 identifies that a RU has been assigned according to its purpose. On the other hand, if a negative response is received, the Quality Management Department 221 identifies that a RU has not been assigned according to its purpose. Afterwards, the Quality Management Department 221 concludes the process. Figure 21 The process shown is complete.

[0192] Furthermore, if the wireless terminal device 20 confirms the allocation of a purpose-based RU during the processing in S204, it can utilize the purpose-based RU to transmit non-periodic low-latency services until the allocation of the purpose-based RU is released. The quality management unit 221 can also retry the processing in S201-S204 after a predetermined time following the receipt of a negative response. If no purpose-based RU is allocated, the quality management unit 221 can also notify the application that the required latency cannot be met.

[0193] (Methods for managing communication quality)

[0194] Figure 22 This is a flowchart illustrating an example of a communication quality management method performed by the quality management unit 221 of the wireless terminal device 20 (STA) according to an embodiment. For example, when an aperiodic low-latency service occurs after a link is established between the AP and the STA, the quality management unit 221 begins... Figure 22 The flowchart shown is for the process (start).

[0195] First, the Quality Management Department 221 waits until the non-periodic low-latency service is sent (S211).

[0196] After the non-periodic low-latency service is transmitted, the quality management department 221 measures the measured delay of the non-periodic low-latency service (S212). The measured delay corresponds, for example, to the time required from the occurrence of the non-periodic low-latency service (from input to buffer) to the completion of the transmission of the non-periodic low-latency service.

[0197] Furthermore, Quality Management Department 221 notifies AP of the measured delay value (S213). Afterwards, Quality Management Department 221 concludes... Figure 22 A series of processes (end).

[0198] Furthermore, the latency measurement value sent in the S213 process can also be the average of multiple latency measurement values, jitter during the transmission of non-periodic low-latency services, the maximum latency calculated from the latency measurement value and a predetermined percentage, etc. The S213 process can be executed either upon request from the AP or by notifying the AP if the latency measurement value exceeds the required latency. Quality Management Department 221 via Figure 22 A series of processes can determine whether resources with the required latency have been allocated.

[0199] <2-3-2> Operations of Resource Control Department 222

[0200] Next, the operation of the resource control unit 222 of the wireless terminal device 20 will be explained.

[0201] Figure 23 This is a flowchart illustrating an example of a method for obtaining and updating RU allocation information performed by the resource control unit 222 of the wireless terminal device 20 (STA) according to an embodiment. The resource control unit 222 begins, for example, upon receiving RU allocation information from the AP after the link between the AP and the STA is established. Figure 23 The flowchart shown is for the process (start).

[0202] First, the resource control unit 222 checks whether there is RU allocation information according to purpose in the received RU allocation information (S221).

[0203] In the processing of S221, if it is confirmed that there is RU allocation information according to purpose (S221: "Yes"), the resource control unit 222 confirms whether there is a difference between the RU allocation information and the managed information (S222).

[0204] In the processing of S222, if a discrepancy is confirmed between the managed RU allocation information and the actual allocation information (S222: "Yes"), the resource control unit 222 updates the managed RU allocation information (S223). Furthermore, the resource control unit 222 notifies the frame processing unit 230 of the updated RU allocation information (S224). Afterwards, the resource control unit 222 terminates the process. Figure 23A series of processes (end).

[0205] If the allocation information of RUs by purpose is not confirmed in the processing of S221 (S221: "No"), or if the allocation information of the managed RUs is confirmed to be identical in the processing of S222 (S222: "No"), the resource control unit 222 confirms whether there is allocation information of RUs for this station, that is, whether there is allocation information of RUs for this station related to services other than non-periodic low-latency services (S225).

[0206] If, during processing S225, the allocation information regarding the local RU is confirmed (S225: "Yes"), resource control unit 222 proceeds to processing S224, notifying frame processing unit 230 of the RU allocation information. Afterwards, resource control unit 222 terminates. Figure 23 A series of processes (end).

[0207] In the processing of S225, if it is confirmed that there is no allocation information for the RU of this site (S225: "No"), Resource Control Department 222 ends. Figure 23 A series of processes (end).

[0208] <2-3-3> Operation of Frame Processing Unit 230

[0209] Next, the operation of the frame processing unit 230 of the wireless terminal device 20 will be explained.

[0210] (The case of received frames)

[0211] Figure 24 This is a flowchart illustrating an example of a downlink frame processing method performed by the frame processing unit 230 of the wireless terminal device 20 (STA) according to an embodiment. For example, when the frame processing unit 230 receives a frame from the transmit / receive unit 140 after establishing a link between the AP and the STA, it begins... Figure 24 The flowchart shown is for the process (start).

[0212] First, the frame processing unit 230 performs MAC header processing, etc. (S231).

[0213] Next, the frame processing unit 230 confirms the frame type (S232). If data is received, the data contained in the processed frame is output to the upper layer (S233). If a response is received for a purpose-based RU allocation request from the AP, the frame processing unit 230 outputs the response content to the quality management unit 221 (S234). If a trigger frame is received, the frame processing unit 230 extracts the RU allocation information from the RU allocation subfield and notifies the resource control unit 222 (S235). Afterwards, the frame processing unit 230 terminates.Figure 24 A series of processes (end).

[0214] (Situation of sending uplink services)

[0215] Figure 25 This is a flowchart illustrating an example of an uplink frame processing method performed by the frame processing unit 230 of the wireless terminal device 20 (STA) according to an embodiment. For example, when uplink traffic occurs after a link is established between the AP and the STA, the frame processing unit 230 begins... Figure 25 The flowchart shown is for the process (start).

[0216] First, the frame processing unit 230 receives services from the upper layer (S241). The services in S241 can be aperiodic low-latency services or other services.

[0217] Next, the frame processing unit 230 adds a MAC header and other components to generate a MAC frame (S242). The MAC frame generated by the processing in S242 includes data corresponding to non-periodic low-latency services or data corresponding to other services.

[0218] Next, the frame processing unit 230 outputs the generated MAC frame along with the RU allocation information input from the resource control unit 222 to the transmit / receive unit 240 (S243). Depending on the RU allocation status between the AP and multiple STAs, this RU allocation information may or may not include RU allocation information based on purpose. Afterwards, the frame processing unit 230 concludes its operation. Figure 25 A series of processes (end).

[0219] <2-3-4> Operation of the transmitting and receiving unit 240

[0220] Next, the operation of the transmitting and receiving unit 240 of the wireless terminal device 20 will be explained.

[0221] (Method for receiving downlink frames)

[0222] Figure 26 This is a flowchart illustrating an example of a method for receiving downlink frames performed by the transmit / receive unit 240 of a wireless terminal device 20 (STA) according to an embodiment. The transmit / receive unit 240, for example, begins... Figure 26 The flowchart shown is for the process (start).

[0223] First, the transmitting / receiving unit 240 performs wireless signal processing (S251). Through the processing in S251, the transmitting / receiving unit 240 obtains wireless frames from the wireless signal.

[0224] Next, the transmitting / receiving unit 240 confirms whether an OFDMA frame has been received (S252). In the processing of S252, the transmitting / receiving unit 240, for example, confirms the frame type.

[0225] In the processing of S252, if it is confirmed that an OFDMA frame has been received (S252: "Yes"), the transmit / receive unit 240 extracts the RU allocation information of the preamble and outputs it to the resource control unit 222 (S253). Furthermore, if the transmit / receive unit 240 detects an RU corresponding to its own station from the RU allocation field, it performs reception processing for that RU. That is, the transmit / receive unit 240 extracts the MAC frame from the RU allocated to its own station and outputs it to the frame processing unit 230 (S254). Afterwards, the transmit / receive unit 240 terminates. Figure 26 A series of processes (end).

[0226] In the process of S252, if it is not confirmed that an OFDMA frame has been received, that is, if the received frame is a normal radio frame that is not an OFDMA frame (S252: "No"), the transmit / receive unit 240 proceeds to the process of S254, extracts the MAC frame, and outputs it to the frame processing unit 230. Afterwards, the transmit / receive unit 240 ends. Figure 26 A series of processes (end).

[0227] Furthermore, if the transmitting / receiving unit 240 confirms receipt of a trigger frame during processing in S252, it outputs the received trigger frame to the frame processing unit 230. Additionally, if the transmitting / receiving unit 240 confirms receipt of a response from the AP during processing in S252, it outputs the received response to the frame processing unit 230.

[0228] (Method for sending frames in the uplink direction)

[0229] Figure 27 This is a flowchart illustrating an example of a method for transmitting uplink OFDMA frames by the transmit / receive unit 240 of a wireless terminal device 20 (STA) according to an embodiment. The transmit / receive unit 240, for example, begins to transmit uplink OFDMA frames when a MAC frame corresponding to an uplink service is input. Figure 27 The flowchart shown is for the process (start).

[0230] First, the transmitting and receiving unit 240 matches the input MAC frame with the subcarrier according to the RU allocation information (S261). The transmitting and receiving unit 240 can match the input MAC frame with the subcarrier according to the information notified by the frame processing unit 230, the link management unit 220, etc., or according to the information stored in the RU allocation subfield.

[0231] Next, the transmitting and receiving unit 240 evaluates whether "maximum frame length > frame length" (S262).

[0232] In the processing of S262, if the maximum frame length is not greater than the frame length (S262: "No"), the transmitting and receiving unit 240 segments the frame (S263). The period used to transmit the segmented frame is the same as... Figure 13 The transfer period TP shown corresponds to this. Furthermore, the transmit / receive unit 240 uses the allocated RU to continuously transmit the segmented frames while setting the inter-frame wait period (IFS) (S264). Afterwards, the transmit / receive unit 240 terminates. Figure 27 A series of processes (end).

[0233] In the processing of S262, if the maximum frame length > frame length (S262: "Yes"), the transmit / receive unit 140 uses the allocated RU to transmit the frame (S265). Furthermore, when processing of S265 is performed, frame segmentation is unnecessary, and the latency requirements of aperiodic low-latency services can be met. Afterwards, the transmit / receive unit 240 terminates. Figure 27 A series of processes (end).

[0234] Furthermore, the "transmission" step in each of the processes in S264 and S265 includes the process of adding a preamble to the MAC frame to generate a radio frame, and radio signal processing. The acquisition of transmission rights in the transmission / reception unit 240 is based, for example, on CSMA / CA. The transmission / reception unit 240 is configured to delay the transmission of segmented frames until the reception of the downlink service is completed if downlink traffic is detected during the IFS (waiting period) of OFDMA frame transfer.

[0235] (Transmission method for non-periodic low-latency services in the uplink direction)

[0236] Figure 28 This is a flowchart illustrating an example of a method for transmitting an uplink aperiodic low-latency service by the transmit / receive unit 240 of a wireless terminal device 20 (STA) according to an embodiment. The transmit / receive unit 240, for example, begins to transmit an uplink aperiodic low-latency service when a MAC frame corresponding to the uplink aperiodic low-latency service is input. Figure 28 The flowchart shown is for the process (start).

[0237] First, the transmitting / receiving unit 240 appends a preamble and other parameters to the MAC frame (S271). Through processing in S271, a radio frame is generated.

[0238] Next, the transmitting / receiving unit 140 confirms the communication status (S272). In the process of S272, if it is confirmed that a downlink OFDMA frame is being received, the transmitting / receiving unit 240 waits until the reception of the OFDMA frame is completed or a waiting period is detected (S273). Furthermore, when the reception of the OFDMA frame is completed or a waiting period is detected, the transmitting / receiving unit 240 proceeds to the process of S274. If, in the process of S272, it is confirmed that an uplink OFDMA frame is being transmitted, the transmitting / receiving unit 240 proceeds to the process of S274.

[0239] In the processing of S274, the transmit / receive unit 240 confirms whether a dedicated RU has been allocated. If, in the processing of S274, it is confirmed that no dedicated RU has been allocated (S274: "No"), the transmit / receive unit 240 uses another RU or the next frame to transmit the non-periodic low-latency service (S275). This "other RU" corresponds, for example, to a high-priority RU. This "next frame" corresponds to the next transfer period (TP) or the next OFDMA frame transfer period. After the processing of S275 is completed, the transmit / receive unit 240 ends. Figure 28 A series of processes (end).

[0240] In the process of S274, if it is confirmed that a dedicated RU has been allocated (S274: "Yes"), the transmit / receive unit 240 confirms whether the dedicated RU is being used (S276). In the process of S276, if it is confirmed that the dedicated RU is being used (S276: "Yes"), the transmit / receive unit 240 proceeds to the process of S275.

[0241] In the processing of S276, if it is confirmed that a dedicated RU is not being used (S276: "No"), the transmit / receive unit 240 evaluates whether the transmission of the radio frame created in the processing of S271 can be completed within the current OFDMA frame transfer period or within the transfer period TP. Specifically, the transmit / receive unit 240 compares the remaining frame time in the RU with the required time for transmitting the data. If it is determined that transmission cannot be completed, the transmit / receive unit 240 waits until the next uplink OFDMA frame before transmitting. The transmit / receive unit 240 may also use the remaining time of the OFDMA frame transfer period to send a request for RU allocation in order to reliably transmit the radio frame in the next uplink OFDMA frame.

[0242] In the process of S277, if it is confirmed that transmission can be completed (S277: "Yes"), the transmit / receive unit 240 uses the allocated dedicated RU to transmit aperiodic low-latency services (S278). Afterwards, the transmit / receive unit 240 terminates. Figure 28 A series of processes (end).

[0243] In the processing of S277, if it is confirmed that transmission cannot be completed (S277: "No"), the transmit / receive unit 240 transmits the aperiodic low-latency service with the following frame (S279). At this time, the transmit / receive unit 240 can also notify the AP of the transmission status of the aperiodic low-latency service by sending a BSR (Buffer Status Report) to the AP. After that, the transmit / receive unit 240 ends. Figure 28 A series of processes (end).

[0244] As described above, when the transceiver unit 240 receives an aperiodic low-latency service from the frame processing unit 230, it processes the service according to the transmission status. To shorten the latency of the aperiodic low-latency service, it is preferable to execute each of the processes S275, S278, and S279 quickly. During the processing of S278, if a dedicated RU is shared with other wireless terminal devices 20, the transceiver unit 240 transmits if no signal is detected by CSMA / CA in that dedicated RU. On the other hand, if a signal is detected by carrier sensing, the transceiver unit 240 performs CSMA / CA again in a high-priority RU, and transmits if no signal is detected by carrier sensing.

[0245] <3> Effects of the implementation method

[0246] The communication system 1 described above, based on the implementation method, can meet the necessary quality requirements for services. The effects of the implementation method will be explained in detail below.

[0247] In OFDMA, for downlink data forwarding, the access point generates multiple RUs (Remote Roots) by grouping subcarriers and assigns them to multiple STAs. The access point then uses these RUs to transmit data in parallel to the multiple STAs. For uplink data forwarding, the access point assigns RUs to each STA and notifies them via a trigger frame. Each STA then uses its assigned RU to transmit data.

[0248] Furthermore, the communication system 1 according to the embodiment allocates RUs according to their purpose when assigning RUs to services or STAs. These purpose-based RUs include dedicated RUs allocated (reserved) for aperiodic low-latency services, regardless of whether there is a service. In communication system 1, when an aperiodic low-latency service occurs, the dedicated RU is used to quickly transmit the service in the same direction as the OFDMA frame's forwarding direction. Regarding services in the same direction as the OFDMA frame's forwarding direction, even when a dedicated RU is used to transmit based on the occurrence of the service, interference to other services can be suppressed. Therefore, the communication system 1 according to the embodiment can suppress delays and jitter of aperiodic low-latency services occurring in the same direction as the OFDMA frame's forwarding direction.

[0249] On the other hand, regarding services whose direction is opposite to the forwarding direction of the OFDMA frame, even assuming no dedicated RU is used, there is a possibility that they cannot be received correctly due to interference between adjacent RUs. In contrast, the communication system 1 according to the embodiment divides the RUs during the transmission of the OFDMA frame along the time axis and inserts an in-between period (IFS) between the divided and adjacent RUs. Furthermore, considering the existence of reverse services, if the OFDMA frame has a longer delay than the required delay of aperiodic low-latency services, the communication system 1 checks for the presence of services in the IFS. Then, during the IFS or after the OFDMA frame forwarding is completed, the communication system 1 uses a dedicated RU to transmit services whose direction is opposite to the forwarding direction of the OFDMA frame. Additionally, the communication system 1 is configured to delay the transmission of services using other RUs when starting to transmit reverse services using a dedicated RU. As a result, the communication system 1 can suppress the delay and jitter of aperiodic low-latency services even for services whose direction is opposite to the forwarding direction of the OFDMA frame.

[0250] As described above, the communication system 1 according to the embodiment can suppress latency and jitter to a low level not only for periodic services but also for aperiodic low-latency services. Therefore, the communication system 1 according to the embodiment can meet the latency requirements of low-latency services that occur aperiodically. Furthermore, the communication system 1 according to the embodiment can also set purpose-specific RUs for services other than aperiodic low-latency services. Thus, the communication system 1 according to the embodiment can improve the efficiency of communication using OFDMA and meet the necessary quality conditions for services.

[0251] <4> other

[0252] In the above embodiments, a case of using a dedicated RU to forward non-periodic low-latency services was illustrated, but it is not limited to this. A dedicated RU can also be used to forward periodically occurring low-latency services. Even when forwarding periodically occurring low-latency services, latency and jitter can be suppressed by utilizing a dedicated RU.

[0253] In the above embodiments, the flowcharts used in the description of the actions are merely examples. The actions described in the embodiments can be rearranged in order of processing, and additional processing can be added. The format of the wireless frames described in the embodiments is merely an example. The wireless frames used in communication system 1 can also be other formats as long as they can perform the actions described in the embodiments. For wireless communication between access point 10 and wireless terminal device 20, a wireless communication standard different from the IEEE 802.11 standard can also be used. "RU" can also be referred to as a "unit".

[0254] In communication system 1, the CPU 11 of access point 10 and the CPU 21 of wireless terminal device 20 can each be other circuits. For example, access point 10 and wireless terminal device 20 can each have an MPU (Micro Processing Unit) instead of a CPU. The various processes described in the embodiment can also be implemented by dedicated hardware. The processes of access point 10 and wireless terminal device 20 can be a mixture of software-executed processes and hardware-executed processes, or only one of them.

[0255] Access point 10 can also use multiple channels to establish multiple links with wireless terminal device 20. Access point 10 and wireless terminal device 20 can each include multiple transmit / receive units (STA functions) corresponding to the multiple channels. In a multi-link system, one or more STA functions can be assigned to a single service category. The association between services and STA functions is configured, for example, to make the traffic volume (data volume) equal across the multiple links constituting the multi-link system. Similar types of services (priority / non-priority, etc.) can also be grouped onto specific links constituting the multi-link system.

[0256] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be made during the implementation phase without departing from its essence. Additionally, the embodiments can be appropriately combined, resulting in combined effects. Moreover, various inventions are included in the above embodiments, and various inventions can be extracted by selecting combinations from the disclosed multiple constituent elements. For example, even if several constituent elements are deleted from all the constituent elements shown in the embodiments, the problem can be solved, and if the desired effect is obtained, the structure with the deleted constituent element can be extracted as an invention.

[0257] (Symbol Explanation)

[0258] 1: Communication system; 10: Access point; 20, 20-1, 20-2, 20-3: Wireless terminal device; 11, 21: CPU; 12, 22: ROM; 13, 23: RAM; 14, 24: Wireless communication module; 15: Wired communication module; 25: Display; 26: Storage device; 200: Application execution unit; 110, 210: LLC processing unit; 120, 220: Link management unit; 121, 221: Quality management unit; 122, 222: Resource Control Department; 130, 230: Frame Processing Department; 140, 240: Transmitting and Receiving Department; 141, 241: Classification Department; 142, 142A, 142B, 142C, 142D, 242, 242A, 242B, 242C, 242D: Queues; 143, 143A, 143B, 143C, 143D, 243, 243A, 243B, 243C, 243D: Carrier Sense Execution Department; 144, 244: Internal Conflict Management Department.

Claims

1. An access point, comprising: The communication circuit is configured to transmit and receive wireless signals using multiple subcarriers; and The processor is configured to use the communication circuit to establish a link with multiple wireless terminal devices, set multiple units obtained by grouping the multiple subcarriers, assign a purpose to each unit according to the quality requirements received from the multiple wireless terminal devices, and notify the multiple wireless terminal devices of the assigned purpose information using a trigger frame during the transmission of a frame indicating the uplink direction.

2. The access point according to claim 1, wherein, The plurality of units includes a first unit associated with low-latency services. When low-latency services occur, the processor confirms the communication status of the plurality of units. While a downlink frame is being transmitted, the first unit is used to transmit the low-latency service to any one of the plurality of wireless terminal devices. While receiving an uplink frame, during the waiting period of the forwarding period or after the forwarding period is completed, the first unit is used to transmit the low-latency service that has occurred to any one of the plurality of wireless terminal devices.

3. The access point according to claim 2, wherein, The plurality of units also includes a second unit associated with a high-priority service, which corresponds to an access category with higher priority than the first access category. When a high-priority service occurs, the processor uses the second unit to send the data to any one of the plurality of wireless terminal devices. The processor is configured to receive low-latency services from any of the plurality of wireless terminal devices via the second unit when the first unit is being used during the transmission.

4. The access point according to claim 1, wherein, The trigger frame is for each of the units and includes information related to the purpose of the unit, the identifier of the unit, and the access scope.

5. A wireless terminal device, comprising: The communication circuit is configured to transmit and receive wireless signals using multiple subcarriers; and The processor is configured to use the communication circuit to establish a link with the access point, notify the access point of the quality requirements of the service to be transmitted, and set multiple units according to their purpose, which are obtained by grouping the multiple subcarriers, based on the trigger frame during the forwarding of the frame indicating the uplink direction received from the access point.

6. The wireless terminal device according to claim 5, wherein, The plurality of units includes a first unit associated with low-latency services. When low-latency services occur, the processor confirms the communication status of the plurality of units. While the first frame in the uplink direction is being transmitted, the first unit is used to send the low-latency service that has occurred to the access point. While receiving the second frame in the downlink direction, during the waiting period for receiving the second frame, or after the reception of the second frame is completed, the first unit is used to send the low-latency service that has occurred to the access point.

7. The wireless terminal device according to claim 6, wherein, The plurality of units also includes a second unit associated with a high-priority service, which corresponds to an access category with higher priority than the first access category. When a high-priority service occurs, the processor uses the second unit to send the data to the access point. The processor is configured to transmit low-latency services via the second unit while the first unit is in use during the transmission period.

8. The wireless terminal device according to claim 5, wherein, When the processor detects a unit corresponding to its own station in the preamble of a frame received from the access point, it performs reception processing on the unit specified by the preamble among the plurality of units.

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