Access point and terminal device

Abstract

An access point according to an embodiment of the present invention is configured to transmit, between a terminal device and the access point, information by using a plurality of wireless links including a first wireless link and a second wireless link. The access point includes a management unit configured to set a service period for preferentially transmitting low-delay traffic to at least one of the plurality of wireless links. When a first service period is scheduled in the first wireless link, the management unit schedules, on the basis of the first service period, a common service period in each of the first wireless link and the second wireless link, and notifies the terminal device of schedule information including information on the common service period.

Description

Access point and terminal device

[0001] The embodiments relate to an access point and a terminal device.

[0002] Wireless LANs (local area networks) are known as information communication systems that wirelessly connect access points (APs) and terminal devices. Terminal devices can access a network via an access point using a wireless LAN. IEEE 802.11be mentions multi-link transmission, in which multiple links (transmission paths) with different frequency channels are established between a terminal device and an access point. In multi-link transmission, multiple APs (affiliated access points) equipped in the same housing, called access point multi-link devices (AP_MLDs), communicate in pairs with multiple STAs (affiliated STAs) equipped in the same housing, called non-AP_MLDs (non-access point multi-link devices). Furthermore, a multi-AP function that enables multiple access points to communicate in a coordinated and cooperative manner is being considered for the next generation of standards.

[0003] Furthermore, the R-TWT (restricted target wake time) function is known as a method for transmitting and receiving low-latency traffic between an access point and a terminal device. An access point using the R-TWT function sets a service period (R-TWT SP) at a period corresponding to the required latency of the low-latency traffic and notifies the terminal device of the set service period using a management frame or action frame such as a beacon. Then, when a terminal device (low-latency terminal) handling low-latency traffic detects the allocation of an R-TWT SP to itself through a received beacon or the like, it deterministically transmits the low-latency traffic to the access point. In a multilink, a TWT agreement can be established for all links constituting the multilink by a pair of any one affiliated AP and affiliated STA. An information and communication system using the R-TWT function can reduce the delay and jitter of low-latency traffic.

[0004] IEEE802.11be D4.0, “35.8 Restricted TWT (R-TWT)”, p611-p616, July 2023

[0005] However, in multi-link transmission or multi-AP function, the R-TWT function is independently configured for each link or transmission path to each access point. Furthermore, when transmitting traffic, the period during which low-latency traffic can obtain priority is only at the start of the R-TWT SP. Therefore, if scheduled low-latency traffic cannot be transmitted at the start of the R-TWT SP due to interference or the like, or if communication of other low-latency or non-low-latency traffic is concentrated on a link with high channel utilization, the communication of the low-latency traffic scheduled to be transmitted may be impeded. In such cases, the required delay of the low-latency traffic may not be met.

[0006] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide an access point and a terminal device that can meet the delay required for low-delay traffic.

[0007] In an embodiment, an access point is configured to transmit information to a terminal device using multiple wireless links including a first wireless link and a second wireless link. The access point includes a management unit configured to set a service period for preferentially transmitting low-latency traffic on at least one of the multiple wireless links. When a first service period is scheduled for the first wireless link, the management unit schedules a common service period for each of the first wireless link and the second wireless link based on the first service period, and notifies the terminal device of schedule information including information about the common service period.

[0008] According to the embodiment, it is possible to provide an access point and a terminal device that can meet the required delay for low-latency traffic.

[0009] FIG. 1 is a block diagram showing an example of the overall configuration of an information communication system according to the first embodiment. FIG. 2 is a block diagram showing an example of the hardware configuration of an access point included in the information communication system according to the first embodiment. FIG. 3 is a block diagram showing an example of the hardware configuration of a terminal device included in the information communication system according to the first embodiment. FIG. 4 is a block diagram showing an example of the functional configuration of an access point included in the information communication system according to the first embodiment. FIG. 5 is a block diagram showing an example of the functional configuration of an A-AP included in an access point included in the information communication system according to the first embodiment. FIG. 6 is a block diagram showing an example of a format of a beacon signal generated by a beacon control unit of an A-AP in an access point included in the information communication system according to the first embodiment. FIG. 7 is a block diagram showing an example of the functional configuration of a transceiver unit of an A-AP in an access point included in the information communication system according to the first embodiment. FIG. 8 is a block diagram showing an example of the functional configuration of a terminal device included in the information communication system according to the first embodiment. FIG. 9 is a block diagram showing an example of the functional configuration of an A-STA included in a terminal device included in the information communication system according to the first embodiment. FIG. 10 is a block diagram showing an example of the functional configuration of a transceiver unit of an A-STA in a terminal device included in the information communication system according to the first embodiment. FIG. 11 is a time chart showing an overview of the R-TWT function in the information communication system according to the first embodiment. FIG. 12 is a flowchart showing an example of a method for using the R-TWT function in the information communication system according to the first embodiment. FIG. 13 is a time chart showing a specific example of communication using the R-TWT function in the information communication system according to the first embodiment. FIG. 14 is a block diagram showing an example of the overall configuration of an information communication system according to a second embodiment. FIG. 15 is a block diagram showing an example of the functional configuration of a sharing access point provided in the information communication system according to the second embodiment. FIG. 16 is a table showing an example of information managed by a management unit of a sharing access point provided in the information communication system according to the second embodiment. FIG. 17 is a block diagram showing an example of the functional configuration of a shared access point provided in the information communication system according to the second embodiment.Fig. 18 is a flowchart showing an example of a method for setting up the R-TWT function in the information communication system according to the second embodiment. Fig. 19 is a flowchart showing an example of a method for using the R-TWT function in the information communication system according to the second embodiment. Fig. 20 is a time chart showing a specific example of communication using the R-TWT function in the information communication system according to the second embodiment.

[0010] Each embodiment will be described below with reference to the drawings. Each embodiment illustrates an apparatus or method for embodying the technical concept of the invention. The drawings are schematic or conceptual. Hereinafter, the same reference numerals are used to designate components having substantially the same functions and configurations. The numerals following the letters in a reference numeral are used to distinguish between elements that are referenced by the same reference numerals and have similar configurations. Similarly, the letters and "hyphen + numeral" following the numerals in a reference numeral are used to distinguish between elements that are referenced by the same reference numerals and have similar configurations. When it is not necessary to distinguish between elements indicated by reference numerals containing the same letters or numerals, these elements are referred to by reference numerals containing only letters or numerals. Hereinafter, "access point" will be abbreviated as "AP" where appropriate.

[0011] <1> First Embodiment In an information communication system 1 according to the first embodiment, an access point and a terminal device establish a multilink connection. Then, the R-TWT service period scheduled for each link is standardized based on the R-TWT service period for transmitting the highest priority low-latency traffic. Details of the information communication system 1 according to the first embodiment are described below.

[0012] <1-1> Configuration First, a description will be given of the configuration of the information communication system 1 according to the first embodiment. In the following description, an example will be given in which a multi-link connection using three links is established between an access point and a terminal device in the information communication system 1.

[0013] <1-1-1> Overall configuration of information communication system 1 Fig. 1 is a block diagram showing an example of the overall configuration of an information communication system 1 according to the first embodiment. As shown in Fig. 1, the information communication system 1 includes, for example, an access point 10 and a terminal device 20.

[0014] The access point 10 is a type of wireless LAN access point. The access point 10 is connected to the network NW by wire or wirelessly and configured to communicate by wire or wirelessly with a server (not shown) on the network NW. The access point 10 is also connected wirelessly to the terminal device 20 and configured to communicate wirelessly with the terminal device 20.

[0015] The terminal device 20 is a wireless terminal such as a smartphone or a PC (Personal Computer). The terminal device 20 is arranged so as to be included in the communication area of ​​the access point 10. The terminal device 20 is wirelessly connected to the access point 10 and configured to communicate wirelessly with the access point 10.

[0016] The wireless communication used in the information and communication system 1 complies with, for example, the IEEE 802.11 standard. The IEEE 802.11 standard has wireless communication functions based on the OSI (Open Systems Interconnection) reference model. In the OSI reference model, wireless communication functions are divided into seven layers (Layer 1: Physical Layer, Layer 2: Data Link Layer, Layer 3: Network Layer, Layer 4: Transport Layer, Layer 5: Session Layer, Layer 6: Presentation Layer, and Layer 7: Application Layer). The data link layer includes a Logical Link Control (LLC) sublayer and a Media Access Control (MAC) sublayer. Frequency bands used in the wireless communication of the information and communication system 1 include, for example, the 2.4 GHz band, the 5 GHz band, the 6 GHz band, the 45 GHz band, and the 60 GHz band. Multiple channels are assigned to each frequency band.

[0017] Furthermore, in the information communication system 1, each of the access point 10 and the terminal device 20 supports an R-TWT (restricted target wake time) function. The R-TWT function is a function that allocates a service period to the terminal device 20 during which traffic requiring low latency can be preferentially exchanged. In this specification, the service period set by the R-TWT function is referred to as an "R-TWT service period (R-TWT SP)," and traffic requiring low latency is referred to as "low latency traffic."

[0018] An access point 10 using the R-TWT function allocates an R-TWT SP to a link and gives a frame exchange opportunity preferentially to a terminal device 20. The frame exchange opportunity corresponds to an opportunity for traffic (data) to be transmitted by frame exchange. For example, the terminal device 20 transmits low-latency traffic to the access point 10 based on receiving a trigger frame from the access point 10 in the R-TWT SP. In this way, the R-TWT function can improve the latency of low-latency traffic by preferentially transmitting the low-latency traffic of the terminal device 20 in the R-TWT SP.

[0019] Furthermore, in the information communication system 1, each of the access point 10 and the terminal device 20 supports multi-link communication using multiple channels (links) as a communication method. Below, an overview of the configuration used in multi-link communication in each of the access point 10 and the terminal device 20 will be described with reference to FIG.

[0020] The access point 10 includes, for example, an access point multi-link device (AP_MLD) and multiple affiliated APs (A-APs). The AP_MLD is a multi-link device (MLD) that manages the link status and wireless communication of each of the multiple A-APs. The AP_MLD may also perform processing for establishing a multi-link between the access point 10 and the terminal device 20. Each A-AP corresponds to a wireless signal processing unit that can establish a wireless link with the terminal device 20. In this example, the access point 10 includes multiple A-APs, A-AP#1, A-AP#2, and A-AP#3.

[0021] The terminal device 20 includes, for example, a non-AP_MLD (non-access point multi-link device) and multiple affiliated stations (A-STAs). The non-AP_MLD is a multi-link device (MLD) that manages the link status and wireless communication of each of the multiple A-STAs. The non-AP_MLD may also perform processing for establishing a multi-link between the access point 10 and the terminal device 20. Each A-STA corresponds to a wireless signal processing unit that may establish a wireless link with the access point 10. In this example, the terminal device 20 includes A-STA#1, A-STA#2, and A-STA#3 as the multiple A-STAs.

[0022] In this example, A-APs #1 to #3 of the access point 10 have established links with A-STAs #1 to #3 of the terminal device 20, respectively. Hereinafter, the link between A-AP #1 and A-STA #1 will be referred to as "link #1." The link between A-AP #2 and A-STA #2 will be referred to as "link #2." The link between A-AP #3 and A-STA #3 will be referred to as "link #3." In a multi-link connection, different channels are assigned to A-APs #1 to #3. The same frequency band may be used for A-APs #1 to #3, or different frequency bands may be used. In a multi-link connection, different channels are assigned to A-STAs #1 to #3. The same frequency band may be used for A-STAs #1 to #3, or different frequency bands may be used.

[0023] When the R-TWT function is used in multi-link, the AP_MLD of the access point 10 can schedule the R-TWT SPs so that they are synchronized across multiple links. The AP_MLD then assigns the scheduled R-TWT SPs to each link and outputs low-latency data to the A-AP corresponding to the link to which the R-TWT SP is assigned. When setting a new R-TWT SP, the AP_MLD determines whether the R-TWT SP overlaps with other previously scheduled R-TWT SPs and decides whether to schedule it. Each A-AP broadcasts schedule information for the R-TWT SP set by the AP_MLD as a wireless signal and sets the R-TWT SP according to the schedule information. The A-AP also transmits data input from the AP_MLD as a wireless signal and outputs the received wireless signal to the AP_MLD.

[0024] When the R-TWT function is used in a multi-link, the non-AP_MLD of the terminal device 20 outputs low-latency data from a higher level to the A-STA corresponding to the link to which the R-TWT SP is assigned at the timing when the data is input from the higher level, in accordance with the schedule information broadcast from the access point 10. Each A-STA outputs the schedule information and data received as a wireless signal to the non-AP_MLD, and outputs the data input from the non-AP_MLD as a wireless signal.

[0025] The AP_MLD may synchronize the transmission time of each link. As a method for synchronizing the transmission time, a master clock held by the AP_MLD may be referenced, or time information notified from the network NW may be referenced. Similarly, the non-AP_MLD may synchronize the transmission time of each link. As a method for synchronizing the transmission time, a master clock held by the non-AP_MLD may be referenced, or time information notified from the AP-MLD of the access point 10 may be referenced. The functional configurations of the access point 10 and the terminal device 20 will be described in more detail later.

[0026] <1-1-2> Hardware Configuration of Information Communication System 1 The hardware configuration of the information communication system 1 according to the first embodiment will be described below.

[0027] <1-1-2-1> Hardware configuration of access point 10 Fig. 2 is a block diagram showing an example of the hardware configuration of the access point 10 included in the information communication system 1 according to the first embodiment. As shown in Fig. 2, 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.

[0028] The CPU 11 is an integrated circuit capable of executing various programs and controls the overall operation of the access point 10. The ROM 12 is, for example, a non-volatile semiconductor memory and stores programs and control data for controlling the access point 10. The RAM 13 is, for example, a volatile semiconductor memory and is used as a work area for the CPU 11. The wireless communication module 14 is configured to be able to send and receive wireless signals via an antenna and is a circuit used for sending and receiving data, etc. with the terminal device 20. The wired communication module 15 is a circuit used for sending and receiving data, etc. via wired signals and is configured to be connectable to the network NW.

[0029] The access point 10 may have other hardware configurations. For example, the access point 10 may be wirelessly connected to the network NW. In this case, the wired communication module 15 may be omitted from the access point 10. The antenna may be built into the access point 10 or may be externally connected. The CPU 11 may be called a "processor." The wireless communication module 14 may be called a "communication circuit."

[0030] <1-1-2-2> Hardware configuration of the terminal device 20 Fig. 3 is a block diagram showing an example of the hardware configuration of the terminal device 20 included in the information communication system 1 according to the first embodiment. As shown in Fig. 3, the 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 26.

[0031] The CPU 21 is an integrated circuit capable of executing various programs and controls the overall operation of the terminal device 20. The ROM 22 is, for example, a non-volatile semiconductor memory and stores programs and control data for controlling the terminal device 20. The RAM 23 is, for example, a volatile semiconductor memory and is used as a work area for the CPU 21. The wireless communication module 24 is configured to be able to send and receive wireless signals via an antenna and is a circuit used for sending and receiving data to and from the access point 10. The display 25 displays, for example, a graphical user interface (GUI) corresponding to application software. The storage 26 is a non-volatile storage device and stores, for example, system software for the terminal device 20.

[0032] The terminal device 20 may have other hardware configurations. For example, if the terminal device 20 is an IoT (Internet of Things) terminal or the like, the display 25 may be omitted from the terminal device 20. The display 25 may function as an input interface for the terminal device 20. The antenna may be built into the terminal device 20 or may be externally connected. The CPU 21 may be called a "processor." The wireless communication module 24 may be called a "communication circuit."

[0033] <1-1-3> Functional Configuration of Information Communication System 1 The functional configuration of the information communication system 1 according to the first embodiment will be described below.

[0034] <1-1-3-1> Functional configuration of the access point 10 Fig. 4 is a block diagram showing an example of the functional configuration of the access point 10 included in the information communication system 1 according to the first embodiment. As shown in Fig. 4, the AP_MLD of the access point 10 includes, for example, a schedule control unit 111 and a data distribution unit 112.

[0035] The schedule control unit 111 controls (manages) the schedule of the R-TWT SPs assigned to each link constituting the multilink. The schedule control unit 111 has a function of scheduling the R-TWT SPs for the highest priority low-latency data and assigning them to each link. The schedule control unit 111 then outputs schedule information including the determined schedule to each A-AP and the data distribution unit 112. The schedule control unit 111 can also calculate the longest R-TWT SP that does not include multiple R-TWT SPs and schedule it as a common R-TWT SP. In this specification, "not including multiple R-TWT SPs" corresponds to a period during which the R-TWT SP is performed on a single link in the R-TWT SP schedule at that time. The schedule control unit 111 has a function of synchronizing the internal time of each A-AP.

[0036] The data distribution unit 112 outputs the low-latency data (low-latency traffic) to the A-AP corresponding to the link to which the R-TWT SP is assigned, when the low-latency data is input from the upper layer. For example, based on the schedule information of the R-TWT SP notified from the schedule control unit 111, the data distribution unit 112 determines the A-AP to which the R-TWT SP is set at the time the data is input, and outputs the low-latency data to that A-AP.

[0037] Note that each link may have a time period already reserved by another R-TWT SP. For this reason, the schedule control unit 111 may request information regarding a period during which transmission is unavailable from each A-AP constituting the multilink, and may adjust (e.g., shorten) the timing of the R-TWT SP assigned to each link based on the response from each A-AP so as to prevent collisions. If a collision occurs, the schedule control unit 111 may not perform scheduling for that link. Possible periods during which transmission is unavailable include reservations by other periodic R-TWT SPs on each link, reservations by other BSSs (basic service sets) using the same channel, and reservations by NAVs (network allocation vectors).

[0038] (1: Functional Configuration of A-AP) Fig. 5 is a block diagram showing an example of the functional configuration of an A-AP included in the access point 10 included in the information communication system 1 according to the first embodiment. As shown in Fig. 5, each A-AP includes, for example, a beacon control unit 121, an R-TWT control unit 122, a frame processing unit 123, and a transceiver unit 124.

[0039] The beacon control unit 121 generates a beacon signal and outputs it to the frame processing unit 123. The beacon signal includes, for example, schedule information for the R-TWT SP. The beacon control unit 121 of each A-AP may broadcast the schedule of the R-TWT SP set for its own link (channel) and other links (channels). For example, the beacon control unit 121 may include, as the R-TWT SP schedule, the start time (TWT start time) and duration (TWT duration) of the common R-TWT SP, and the start time (TWT start time) and duration (TWT duration) of each individual R-TWT SP transmitted synchronously. When the beacon control unit 121 broadcasts the schedules of the R-TWT SPs of all links only on the primary link set in the multilink, it broadcasts only the schedule of the R-TWT SP corresponding to that link on the other links. If the beacon signal received from another access point 10 includes a setting such as R-TWT SP, the beacon control unit 121 notifies the schedule control unit 111 of the setting.

[0040] The R-TWT control unit 122 extracts the R-TWT SP corresponding to its own channel from the schedule information of the R-TWT SP input from the schedule control unit 111. Then, the R-TWT control unit 122 outputs a trigger frame to the frame processing unit 123 at the start time of the R-TWT SP assigned to its own channel. The R-TWT control unit 122 may include in the trigger frame the duration or end time of the R-TWT SP, and a set of the identifier of the target link of the next R-TWT SP, the TWT start time, and the TWT duration.

[0041] The frame processing unit 123 is a functional block that executes processing corresponding to the MAC sublayer of the second layer. When data or the like is input from the data distribution unit 112, the frame processing unit 123 adds a MAC header to generate a MAC frame and outputs the MAC frame to the transmission / reception unit 124. When a trigger frame is input from the R-TWT control unit 122, the frame processing unit 123 transfers the input trigger frame to the transmission / reception unit 124. The frame processing unit 123 may be configured to generate a beacon signal or a trigger frame based on information input from the beacon control unit 121 or the R-TWT control unit 122.

[0042] Furthermore, when a MAC frame is input from the transmitting / receiving unit 124, the frame processing unit 123 processes the MAC header and outputs the input frame to the data allocation unit 112 or the beacon control unit 121 depending on the frame type. For example, when a data frame is input from the transmitting / receiving unit 124, the frame processing unit 123 outputs the input frame to the data allocation unit 112. When a control frame including schedule information for the R-TWT function is input from the transmitting / receiving unit 124, the frame processing unit 123 outputs the input frame to the beacon control unit 121.

[0043] The transceiver 124 is a functional block that executes processing corresponding to the first layer. The transceiver 124 generates a wireless frame by adding a preamble or the like to the MAC frame input from the frame processing unit 123, and converts the generated wireless frame into a wireless signal. The transceiver 124 then transmits (radiates) the converted wireless signal via an antenna. The transceiver 124 also extracts a MAC frame from the wireless frame received by the antenna and outputs the extracted MAC frame to the frame processing unit 123.

[0044] (2: Configuration of Beacon Signal) Fig. 6 is a block diagram showing an example of the format of a beacon signal generated by the beacon control unit 121 of the A-AP in the access point 10 included in the information communication system 1 according to the first embodiment. As shown in Fig. 6, the beacon signal includes information on, for example, a target link, a common TWT start time CT, a common TWT duration CP, a TWT start time T1, a TWT duration P1, a TWT start time T2, and a TWT duration P2.

[0045] The target link indicates the identifier of the link to which the R-TWT SP is assigned. The link identifier is specified, for example, by the identifier of the A-STA. The target link information may include information about a single link or multiple links. The common TWT start time CT indicates the start time of the common R-TWT SP assigned to the associated target link. The common TWT duration CP indicates the duration of the common R-TWT SP assigned to the associated target link. The pair of the TWT start time T1 and the TWT duration P1, and the pair of the TWT start time T2 and the TWT duration P2, respectively, indicate the start time and duration of synchronously transmitting data using multiple links in the common R-TWT SP. At least one pair of the TWT start time and the TWT duration may be set for the common R-TWT SP.

[0046] The beacon control unit 121 may include in the beacon signal the start time (TWT start time) and duration (TWT duration) of the R-TWT SP to be copied from its own channel and set in another channel, based on the schedule information of the R-TWT SP input by the schedule control unit 111. The beacon control unit 121 may also use the beacon signal to broadcast the schedules of the R-TWT SPs of all links. In this case, the beacon control unit 121 may include in the beacon signal information on the target link, the TWT start time, and the TWT duration for each R-TWT SP.

[0047] The configuration of the beacon signal may be changed as appropriate depending on the configuration of the common R-TWT SP. For example, when no other R-TWT SPs are set within the common R-TWT SP (i.e., when only a common R-TWT SP is set), information about the other TWT SPs (e.g., the TWT start time T1, the TWT duration P1, the TWT start time T2, and the TWT duration P2) may be omitted from the beacon signal, trigger frame, or other action frame. When only a common R-TWT SP is set and the same data is to be transmitted, the beacon control unit 121 can uniquely specify the transmission timing by announcing the common TWT start time CT and the common TWT duration CP using a beacon signal.

[0048] (3: Functional Configuration of Transmitter / Receiver 124) Fig. 7 is a block diagram showing an example of the functional configuration of the transmitter / receiver 124 of the A-AP in the access point 10 included in the information communication system 1 according to the first embodiment. The functional configuration of the transmitter / receiver 124 corresponds to the channel access means (function) of the A-AP. As shown in Fig. 7, the transmitter / receiver 124 includes, for example, a classification unit 131, queues 132A, 132B, 132C, and 132D, carrier sense execution units 133A, 133B, 133C, and 133D, and an internal collision management unit 134.

[0049] The classification unit 131 classifies MAC frames input from the frame processing unit 123 into multiple access categories: Voice (VO), Video (VI), Best Effort (BE), Background (BK), and Real Time (RT) based on the traffic type (TID: Traffic Identifier) ​​included in the MAC header. The TID is a traffic indicator used to identify the traffic to which data belongs. MAC frames classified into the access category RT are high-priority frames such as trigger frames and low-latency traffic. The classification unit 131 then inputs MAC frames corresponding to the access categories VO, VI, BE, and BK into queues 132A, 132B, 132C, and 132D, respectively. The queues 132A, 132B, 132C, and 132D buffer MAC frames corresponding to the access categories VO, VI, BE, and BK, respectively. The queues 132A, 132B, 132C, and 132D are associated with the carrier sense execution units 133A, 133B, 133C, and 133D, respectively.

[0050] When data is input to the corresponding queue 132, each of the carrier sense execution units 133A, 133B, 133C, and 133D executes carrier sense based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) in accordance with preset access parameters. The access parameters are set for each access category. For example, the access parameters are set so that the transmission of wireless signals is prioritized in the order of "VO," "VI," "BE," and "BK." Each of the carrier sense execution units 133A, 133B, 133C, and 133D halts acquisition of the transmission right if the channel state during carrier sense is busy, and acquires the transmission right for a MAC frame if the channel state remains idle for a predetermined period of time. After acquiring the transmission right, the carrier sense execution unit 133 retrieves a MAC frame from the associated queue 132 and outputs the retrieved MAC frame to the internal collision management unit 134.

[0051] The internal collision management unit 134 prevents transmission collisions when multiple carrier sense execution units 133 simultaneously acquire the right to transmit. Specifically, when multiple MAC frames are input simultaneously, the internal collision management unit 134 prioritizes and outputs MAC frames of higher priority access categories. The MAC frames output from the internal collision management unit 134, i.e., MAC frames that have acquired access rights to a channel, are converted into wireless frames after a preamble is added to them and transmitted via an antenna.

[0052] Furthermore, when a MAC frame input from the frame processing unit 123 is classified as the access category RT, the classification unit 131 performs carrier sensing and then inputs the MAC frame to the internal collision management unit 134 without passing through each queue 132. In other words, high-priority frames, such as low-latency traffic classified as the access category RT, are processed with priority over other traffic types by performing carrier sensing without passing through each queue 132. Therefore, high-priority frames can be processed with less delay than other traffic types. When transmitting a high-priority frame, the transmission / reception unit 124 may temporarily suspend carrier sensing by each carrier sense execution unit 133. The transmission / reception unit 124 may generate a trigger frame based on information notified from the frame processing unit 123.

[0053] In the information communication system 1, a trigger frame or low latency traffic input from the R-TWT control unit 122 at the start timing of an R-TWT SP is treated preferentially as an access category RT. Parameters that allow transmission of the trigger frame or low latency data to be prioritized over access parameters of other access categories may be set for the trigger frame or low latency data. The trigger frame may share a channel access means with a high-priority access category and be transmitted by interrupting other data in the queue 132. Furthermore, when it is determined that the data is an R-TWT SP, i.e., when the trigger frame has been transmitted first, the low latency data may be transmitted without using the channel access means.

[0054] The access parameters used in carrier sensing in the transceiver 124 of the 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 wait time for collision avoidance. CWmin and CWmax indicate the minimum and maximum values ​​of the contention window, respectively. AIFS (arbitration interframe space) indicates a fixed transmission wait time set for each access category for collision avoidance control with a priority control function. TXOP corresponds to the channel occupancy time. TXOPLimit indicates the upper limit of TXOP. The shorter the CWmin and CWmax, the easier it is for the queue 132 to obtain a transmission right. The smaller the AIFS, the higher the priority of the queue 132. The larger the value of TXOPLimit, the greater the amount of data transmitted with one transmission right. The access parameters may be referred to as Enhanced Distributed Channel Access (EDCA) parameters.

[0055] Furthermore, the access point 10 may have other functional configurations as long as it is capable of performing the operations described below. For example, the channel access function of the access point 10 may be implemented in the frame processing unit 123 rather than in the transceiver unit 124. The transmission priority may be determined based on the required delay of the aperiodic low latency traffic, the priority of the traffic (SCS: stream classification service), and the traffic type.

[0056] <1-1-3-2> Functional configuration of the terminal device 20 Fig. 8 is a block diagram showing an example of the functional configuration of the terminal device 20 included in the information communication system 1 according to the first embodiment. As shown in Fig. 8, the Non-AP_MLD of the terminal device 20 includes, for example, a schedule control unit 211 and a data distribution unit 212.

[0057] The schedule control unit 211 controls (manages) the schedule of the R-TWT SP assigned to each link constituting the multilink. The schedule control unit 211 outputs schedule information of the R-TWT SP to the data distribution unit 212 based on the schedule information input from each A-STA and information on the next R-TWT SP. When schedule information is notified in each link constituting the multilink, the schedule control unit 211 updates the schedule of the R-TWT SP using the input schedule information. When schedule information is notified only in the primary link assigned to the multilink, the schedule control unit 211 updates the schedule of the R-TWT SP using the schedule information. When information on the next R-TWT SP is input from the A-STA corresponding to the link in which the R-TWT SP is set, the schedule control unit 211 updates the schedule information using the information. The schedule control unit 211 notifies the data distribution unit 212 of the updated schedule.

[0058] When low-latency data (low-latency traffic) is input from an upper layer, the data distribution unit 212 determines the A-STA to which the R-TWT SP is set based on the schedule information of the R-TWT SP notified from the schedule control unit 211, and outputs the low-latency data to the A-STA. In addition, the data distribution unit 212 outputs the data input from each A-STA to the upper layer.

[0059] (1: Functional Configuration of A-STA) Fig. 9 is a block diagram showing an example of the functional configuration of an A-STA included in the terminal device 20 included in the information communication system 1 according to the first embodiment. As shown in Fig. 9, each A-STA includes, for example, a beacon processing unit 221, a frame processing unit 222, and a transceiver unit 223.

[0060] The beacon processing unit 221 extracts schedule information from the beacon signal input from the frame processing unit 222 and outputs it to the schedule control unit 211. For example, the beacon processing unit 221 outputs information on the next R-TWT SP input from the frame processing unit 222 to the schedule control unit 211, or notifies (sets) the frame processing unit 222 of the R-TWT SP linked to the channel corresponding to the A-STA. The beacon processing unit 221 may notify (set) the frame processing unit 222 of the R-TWT SP corresponding to the A-STA based on an instruction from the schedule control unit 211.

[0061] The frame processing unit 222 is a functional block that executes processing corresponding to the MAC sublayer of the second layer. When data or the like is input from the data distribution unit 212, the frame processing unit 222 adds a MAC header to generate a MAC frame and outputs it to the transceiver unit 223. The frame processing unit 222 performs MAC header processing on the frame input from the transceiver unit 223, and if the frame that has undergone MAC header processing is a beacon signal, it outputs it to the beacon processing unit 221, and if it is data, it outputs it to the data distribution unit 212. When the frame input from the transceiver unit 223 is a trigger frame indicating the start of an R-TWT SP, the frame processing unit 222 sets the R-TWT SP based on the TWT duration and outputs information about the next R-TWT SP to the beacon processing unit 221. The frame processing unit 222 outputs data to the corresponding A-STA based on the TID and the like, based on the schedule of the R-TWT SP input by the schedule control unit 211.

[0062] The transceiver 223 is a functional block that executes processing corresponding to the first layer. The transceiver 223 generates a wireless frame by adding a preamble or the like to the MAC frame input from the frame processing unit 222, and converts the generated wireless frame into a wireless signal. The transceiver 223 then transmits (radiates) the converted wireless signal via an antenna. The transceiver 223 also extracts a MAC frame from the wireless frame received by the antenna and outputs the extracted MAC frame to the frame processing unit 222.

[0063] 10 is a block diagram showing an example of the functional configuration of the transceiver 223 of the A-STA in the terminal device 20 included in the information communication system 1 according to the first embodiment. As shown in FIG. 10, the transceiver 223 includes, for example, a classification unit 231, queues 232A, 232B, 232C, and 232D, carrier sense execution units 233A, 233B, 233C, and 233D, and an internal collision management unit 234.

[0064] The classification unit 231 classifies MAC frames input from the frame processing unit 222 into multiple access categories VO, VI, BE, BK, and LL (Low Latency) based on the traffic type included in the MAC header. MAC frames classified into access category LL are high-priority frames such as low-latency traffic. The classification unit 231 then inputs MAC frames corresponding to access categories VO, VI, BE, and BK into queues 232A, 232B, 232C, and 232D, respectively. The queues 232A, 232B, 232C, and 232D buffer MAC frames corresponding to access categories VO, VI, BE, and BK, respectively. The queues 232A, 232B, 232C, and 232D are associated with carrier sense execution units 233A, 233B, 233C, and 233D, respectively.

[0065] Each of the carrier sense execution units 233A, 233B, 233C, and 233D executes carrier sense based on CSMA / CA in accordance with preset access parameters when data is input to the corresponding queue 232. Each of the carrier sense execution units 233A, 233B, 233C, and 233D halts acquisition of the transmission right if the channel state during carrier sense is busy, and acquires the transmission right for the MAC frame if the channel state remains idle for a predetermined period of time. The carrier sense execution unit 233 that has acquired the transmission right extracts the MAC frame from the associated queue 232 and outputs the extracted MAC frame to the internal collision management unit 234.

[0066] The internal collision management unit 234 prevents transmission collisions when multiple carrier sense execution units 233 simultaneously acquire the right to transmit. Specifically, when multiple MAC frames are input simultaneously, the internal collision management unit 234 prioritizes and outputs MAC frames of higher priority access categories. The MAC frames output from the internal collision management unit 234, i.e., MAC frames that have acquired access rights to a channel, are converted into wireless frames after a preamble is added, and then transmitted via an antenna.

[0067] Furthermore, when a MAC frame input from the frame processing unit 222 is classified as access category LL, the classification unit 231 performs carrier sensing and then inputs the MAC frame to the internal collision management unit 234 without passing through each queue 232. In other words, high-priority frames, such as low-latency traffic, classified as access category LL are processed with priority over other traffic types by performing carrier sensing without passing through each queue 232. Therefore, high-priority frames can be processed with less delay than other traffic. The transceiver unit 223 may temporarily stop carrier sensing by each carrier sense execution unit 233 when transmitting a high-priority frame.

[0068] In the information communication system 1, low latency traffic input from the frame processing unit 222 is treated preferentially as an access category LL. Parameters that allow transmission of low latency traffic with higher priority than access parameters of other access categories may be set for the low latency traffic. The low latency traffic may share a channel access means with a high priority access category and be transmitted by interrupting other data in the queue 232. Furthermore, when the low latency traffic receives a trigger frame and is determined to be within the R-TWT SP, it may be transmitted without using the channel access means.

[0069] The access parameters used in carrier sensing in the transceiver 223 of the terminal device 20 include, for example, CWmin, CWmax, AIFS, and TXOPLimit. The shorter the CWmin and CWmax, the easier it is for the queue 232 to obtain a transmission right. The smaller the AIFS, the higher the priority of the queue 232. The larger the value of TXOPLimit, the larger the amount of data transmitted with one transmission right.

[0070] The terminal device 20 may have other functional configurations as long as it is capable of executing the operations described below. For example, the channel access function of the terminal device 20 may be implemented in the frame processing unit 222, rather than in the transceiver unit 223. The transmission priority may be determined based on the required delay of the low-latency traffic, the priority of the traffic (SCS: stream classification service), and the traffic type.

[0071] <1-2> Operation The operation of the information communication system 1 according to the first embodiment will be described below.

[0072] <1-2-1> Overview of R-TWT Function Fig. 11 is a time chart showing an overview of the R-TWT function in the information communication system 1 according to the first embodiment. Fig. 11 shows a processing sequence of the R-TWT function when a multi-link including three links #1 to #3 is established between the access point 10 and the terminal device 20. Below, an overview of the R-TWT function in the information communication system 1 according to the first embodiment will be described with reference to Fig. 11.

[0073] The access point 10 sets a fixed period (TWT period) when setting up the R-TWT function. The TWT period is preferably set to match the transmission period of low-latency traffic. One period (TWT interval) of the TWT period includes an R-TWT SP. The R-TWT SP is determined, for example, by a TWT start time and a TWT duration. The TWT duration indicates the length of the R-TWT SP starting from the TWT start time. The terminal device 20 can recognize a time based on the TWT start time and the TWT period as the TWT start time of the next R-TWT service period SP. The TWT interval also corresponds to the interval between the TWT start times of adjacent R-TWT service periods SP.

[0074] When the TWT cycle begins, each link simultaneously transmits (radiates) a beacon signal to announce the R-TWT SP. The beacon signal may include management information used in the R-TWT function, such as the TWT start time, TWT duration, TWT interval, and transmission suppression period. This management information used in the R-TWT function may be included not only in the beacon signal but also in the multilink probe response during multilink setup. Upon receiving the beacon signal, the terminal device 20 acquires the TWT start time, TWT duration, TWT interval, and the like, and notifies each A-STA of them. In this example, an R-TWT SP is set for link #3 based on the beacon signal. As a result, low-latency traffic frame exchange is preferentially performed on the link to which the R-TWT SP is assigned.

[0075] In addition, when setting up the R-TWT function, a transmission suppression period may be set to overlap with the R-TWT SP. The transmission suppression period corresponds to a period during which traffic transmission by other terminal devices that are not given priority frame exchange opportunities is suppressed or prohibited. The initial setting of the R-TWT function may be determined in various ways. For example, the initial setting of the R-TWT function may use traffic attributes, such as the traffic occurrence interval and data volume, notified by an application that generates low-latency traffic. In this case, the access point 10 notifies a server on the network NW of the traffic type to acquire the corresponding traffic attributes. The access point 10 then determines the initial setting of the R-TWT function based on the acquired traffic attributes.

[0076] <1-2-2> Method of Using the R-TWT Function Fig. 12 is a flowchart showing an example of a method of using the R-TWT function in the information communication system 1 according to the first embodiment. Hereinafter, with reference to Fig. 12, an example of a method of using the R-TWT function in the information communication system 1 according to the first embodiment will be described.

[0077] After establishing a multi-link with the terminal device 20 and scheduling at least one R-TWT SP, the AP_MLD of the access point 10 starts a series of processes shown in FIG. 12 (START).

[0078] First, the schedule control unit 111 of the AP_MLD of the access point 10 checks whether there is an R-TWT SP that does not include multiple R-TWT SPs in a single link among the scheduled R-TWT SPs (S11).

[0079] In the process of S11, if the schedule control unit 111 confirms that there is an R-TWT SP that does not include multiple R-TWT SPs in a single link among the scheduled R-TWT SPs, it proceeds to the process of S12 (S11: YES), and if it confirms that there is no R-TWT SP that does not include multiple R-TWT SPs, it proceeds to the process of S13 (S11: NO).

[0080] In the process of S12, the schedule control unit 111 sets the R-TWT SP with the maximum length as the common R-TWT SP. The schedule control unit 111 selects the R-TWT SP with the maximum length from the R-TWT SPs extracted in the process of S11. When the process of S12 is completed, the schedule control unit 111 proceeds to the process of S14.

[0081] In the process of S13, the schedule control unit 111 sets the period of the R-TWT SP that has the longest period that does not overlap with other R-TWT SPs as a common R-TWT SP. That is, the schedule control unit 111 truncates the common R-TWT SP that is set based on the period in which multiple R-TWT SPs are scheduled in parallel before the next R-TWT SP so that it does not overlap with other R-TWT SPs. In addition, the schedule control unit 111 may schedule the portion that overlaps with other R-TWT SPs as a separate R-TWT SP. When the process of S13 is completed, the schedule control unit 111 proceeds to the process of S14.

[0082] In the process of S14, the schedule control unit 111 notifies the terminal device 20 of schedule information including the common R-TWT SP. The schedule control unit 111 of the AP_MLD notifies the beacon control unit 121 of each A-AP of the schedule information. Then, the beacon control unit 121 of each A-AP generates a beacon signal including the received schedule, and transmits (radiates) a wireless signal via the frame processing unit 123 and the transmission / reception unit 124.

[0083] Upon completion of the process of S14, the schedule control unit 111 performs redundant transmission of high-priority low-latency traffic using the common R-TWT SP (S15). Specifically, the schedule control unit 111 notifies the data distribution unit 112 of schedule information including the common R-TWT SP. When transmitting upstream traffic, the data distribution unit 112 outputs a trigger frame instructing the transfer of low-latency traffic to each A-AP to which the common R-TWT SP is assigned, for example, based on the common TWT start time. When transmitting downstream traffic, the data distribution unit 112 outputs downstream traffic to each A-AP to which the common R-TWT SP is assigned, for example, based on the common TWT start time. In this way, in both the upstream and downstream directions, low-latency traffic can be distributed and transmitted to multiple links to which the common R-TWT SP is assigned. The number of links used for redundant transmission in the common R-TWT SP assigned to each link may be plural. When the process of S15 is completed, the AP_MLD ends the series of processes in FIG.

[0084] As described above, in the information communication system 1 according to the first embodiment, the AP_MLD of the access point 10 can schedule a common R-TWT SP to multiple links at the same timing, thereby redundantly transmitting low-latency traffic.

[0085] <1-2-3> Specific Example of Communication Using the R-TWT Function Fig. 13 is a time chart showing a specific example of communication using the R-TWT function in the information communication system 1 according to the first embodiment. Fig. 13 shows a processing sequence of the R-TWT function when a multi-link including three links #1 to #3 is established between the access point 10 and the terminal device 20. Below, a specific example of communication using the R-TWT function in the information communication system 1 according to the first embodiment will be described with reference to Fig. 13.

[0086] In this example, R-TWT SP1 to R-TWT SP3 are set as common R-TWT SPs on links #1 to #3, respectively, based on beacon signals containing schedule information for the R-TWT SPs. The length of the TWT duration of each of R-TWT SP1 to R-TWT SP3 corresponds to the common TWT duration CP. The common R-TWT SPs are scheduled so that they do not overlap with other R-TWT SPs.

[0087] Time t0 corresponds to the common TWT start time CT. In this example, at time t0, transmission of data D#1 corresponding to low-latency traffic (LL) begins on each of links #1 to #3. That is, data D#1 is redundantly transmitted using links #1 to #3. Furthermore, in the R-TWT SP1 of link #1, after data D#1 is transmitted, transmission of data D#2 corresponding to non-low-latency traffic (non-LL) begins. In this way, non-low-latency traffic can be transmitted in the R-TWT SP during periods other than the TWT start time when low-latency traffic is not being transmitted. In the R-TWT SP2 of link #2, after data D#1 is transmitted, data D#3 corresponding to low-latency traffic (LL) is transmitted. In the R-TWT SP3 of the link #3, after the data D#1 is transmitted, the data D#4 corresponding to the low latency traffic (LL) is transmitted.

[0088] Time t1 corresponds to the start time of the TWT included in the common R-TWT SP. In this example, at time t1, data D#2 is being transmitted in R-TWT SP1 of link #1, and therefore data D#5 corresponding to low latency traffic is being redundantly transmitted using R-TWT SP2 and R-TWT SP3 corresponding to links #2 and #3, respectively. After data D#5 is transmitted in R-TWT SP2, data D#6 corresponding to low latency traffic (LL) is transmitted. Time t2 corresponds to the end time of the common R-TWT SP.

[0089] As described above, when transmitting the same data through a common R-TWT SP, the information communication system 1 synchronizes the transmission timing of low-latency traffic across multiple links according to the traffic transmission status and the TWT start time set in the common R-TWT SP. Furthermore, when only a common R-TWT SP is set, the information communication system 1 uniquely synchronizes the transmission timing of low-latency traffic across multiple links according to the common TWT start time. When upstream low-latency traffic is transmitted through the common R-TWT SP, a trigger frame is used. In this manner, the information communication system 1 can redundantly transmit low-latency traffic (e.g., data D#1, D#5) using the common R-TWT SPs (R-TWT SP1 to R-TWT SP3) set for each of links #1 to #3. Note that, in this specification, "redundant transmission" refers to the transmission of the same data in parallel using multiple links (transmission paths). In the information communication system 1, when different data are transmitted in the common R-TWT SP, the transmission timing does not need to be synchronized.

[0090] <1-3> Effects of the First Embodiment According to the information communication system 1 according to the first embodiment, it is possible to satisfy the required delay for low-latency traffic. The effects of the first embodiment will be described in detail below.

[0091] When low-latency traffic is transmitted using one R-TWT SP, there is a risk that it will not be able to transmit at the start of the scheduled R-TWT SP due to interference, etc. Furthermore, if low-latency traffic is unable to transmit at the start of the R-TWT SP, the right to transmit may be taken away by non-low-latency traffic in that R-TWT SP, and the traffic may not be able to transmit as scheduled.

[0092] Therefore, in the information communication system 1 according to the first embodiment, the access point 10 schedules a common R-TWT SP, which is a common R-TWT SP that is a combination of the R-TWT SPs scheduled for each link, based on the R-TWT SP that transmits the highest priority low latency traffic.The access point 10 then uses the common R-TWT SP to redundantly transmit the highest priority low latency traffic.

[0093] As a result, even if some of the multiple links constituting a multi-link are affected by interference or the like, the information communication system 1 according to the first embodiment can transmit low-latency traffic via other links that are less affected by interference or the like. As a result, the information communication system 1 according to the first embodiment can more reliably transmit low-latency traffic, thereby reducing the delay and jitter of the traffic. Therefore, the information communication system 1 according to the first embodiment can provide an access point and a terminal device that can meet the required delay of low-latency traffic.

[0094] <2> Second Embodiment In an information communication system 1A according to a second embodiment, an access point and a terminal device establish a multi-AP connection. The information communication system 1A standardizes the R-TWT service periods scheduled for each transmission path based on the R-TWT service period for transmitting the highest priority low-latency traffic. Details of the information communication system 1A according to the second embodiment are described below.

[0095] <2-1> Configuration First, the configuration of the information communication system 1A according to the second embodiment will be described. In one form of the multi-AP function, multiple access points belonging to an access point connected to the network NW cooperate to perform data communication between the access point connected to the network NW and a terminal device. As an example of the cooperative operation between multiple access points belonging to an access point connected to the network NW, offloading is considered, in which data (traffic) exchanged between an access point connected to the network NW and a non-AP_MLD is distributed to multiple access points belonging to the access point connected to the network NW. In this specification, in the multi-AP function, an access point connected to the network NW is referred to as a "sharing access point," and multiple access points belonging to an access point connected to the network NW are referred to as "shared APs."

[0096] <2-1-1> Overall configuration of information communication system 1A Fig. 14 is a block diagram showing an example of the overall configuration of the information communication system 1A according to embodiment 2. As shown in Fig. 14, the information communication system 1A includes a sharing AP (sharing access point) 30, a plurality of shared APs (shared access points) 40, and a terminal device 20.

[0097] The sharing AP 30 is a type of wireless LAN access point. The sharing AP 30 is connected to the network NW by wire or wirelessly, and is configured to perform wired or wireless communication with a server (not shown) on the network NW. The sharing AP 30 is also connected to multiple shared APs 40 by wire or wirelessly, and is configured to perform wired or wireless communication with each of the multiple shared APs 40. The sharing AP 30 can establish a logical multi-AP connection with the non-AP_MLD of the terminal device 20.

[0098] The shared AP 40 is a type of wireless LAN access point. The shared AP 40 is configured to communicate with the sharing AP 30 via wired or wireless communication. The shared AP 40 is wirelessly connected to the A-STA of the terminal device 20 and configured to communicate wirelessly with the A-STA of the terminal device 20. The multiple shared APs 40 are installed at locations distant from each other and have different communication areas. The communication area of ​​each shared AP 40 may overlap with the communication area of ​​other shared APs 40. FIG. 14 illustrates an example in which a multi-AP connection is established using three shared APs 40-1, 40-2, and 40-3.

[0099] In the terminal device 20 of the second embodiment, A-STA #1 is wirelessly connected to the shared AP 40-1 (link #1), A-STA #2 is wirelessly connected to the shared AP 40-2 (link #2), and A-STA #3 is wirelessly connected to the shared AP 40-3 (link #3). The wireless connection between the A-STA and the shared AP 40 corresponds to the connection between a pair of A-APs and A-STAs in the first embodiment. Each A-STA can switch its connection to another shared AP 40 as the terminal device 20 moves. The non-AP_MLD of the second embodiment establishes a logical multi-AP connection with the shared AP 30 via multiple A-STAs and multiple shared APs 40, and can exchange data, etc.

[0100] In the information communication system 1A, when a multi-AP connection is established, information on a plurality of shared APs 40 under the sharing AP 30 and information on a plurality of A-STAs under the non-AP_MLD are mutually exchanged between the sharing AP 30 and the non-AP_MLD. This allows the information communication system 1A to collectively establish a comprehensive connection between the sharing AP 30 and the non-AP_MLD, targeting the plurality of shared APs 40 and the plurality of A-STAs.

[0101] <2-1-2> Hardware configuration of information communication system 1A In the information communication system 1A according to the second embodiment, the hardware configuration of the sharing AP 30 is similar to, for example, the access point 10 according to the first embodiment. When the shared AP 40 is wirelessly connected to the sharing AP 30, the hardware configuration is similar to the configuration of the access point 10 according to the first embodiment from which the wired communication module 15 is omitted. When the shared AP 40 is wiredly connected to the sharing AP 30, the hardware configuration is similar to the access point 10 according to the first embodiment. The hardware configuration of the terminal device 20 according to the second embodiment is similar to the terminal device 20 according to the first embodiment.

[0102] <2-1-3> Functional Configuration of Information Communication System 1A The functional configuration of the information communication system 1A according to the second embodiment will be described below. Note that the functional configuration of the terminal device 20 according to the second embodiment is the same as that according to the first embodiment, except that, for example, non-AP_MLD can manage and control multi-AP connections.

[0103] <2-1-3-1> Functional configuration of the sharing AP 30 Fig. 15 is a block diagram showing an example of the functional configuration of the sharing AP 30 included in the information communication system 1A according to the second embodiment. As shown in Fig. 15, the sharing AP 30 includes, for example, a data processing unit 311, a frame processing unit 312, multiple transmission / reception units 313, and a management unit 314.

[0104] The data processing unit 311 outputs data input from the network NW side via the LLC sublayer to the frame processing unit 312. The data processing unit 311 also outputs data input from the frame processing unit 312 to the network NW side via the LLC sublayer.

[0105] Frame processing unit 312 exchanges management information with management unit 314, and exchanges data with data processing unit 311. Frame processing unit 312 distributes the management information and data input from data processing unit 311 or management unit 314 to transmission / reception unit 313 connected to shared AP 40 connected to A-STA under the destination non-AP_MLD. When frame processing unit 312 is connected to terminal device 20 via multiple shared APs 40, it may distribute data to transmission / reception unit 313 according to TID.

[0106] The transceiver 313 is connected to the shared AP 40 via a wired or wireless connection. In this example, the multiple transceivers 313 include transceivers 313-1, 313-2, and 313-3 connected to the shared APs 40-1, 40-2, and 40-3, respectively. The transceiver 313 transmits data, etc. input by the frame processing unit 312, to the shared AP 40 connected to it. The transceiver 313 transmits data, etc. received from the shared AP 40 connected to it to the frame processing unit 312. The transceiver 313 can exchange management information with the frame processing unit 312. Note that an A-STA may be directly connected to the sharing AP 30. In this case, one transceiver 313 shown in FIG. 15 replaces the shared AP 40.

[0107] The management unit 314 is a multi-link device (MLD) that manages the link status and wireless communication of each of the multiple transmission / reception units 313. The management unit 314 may also perform processing to establish a multi-AP connection between the sharing AP 30 and the terminal device 20. The management unit 314 includes a terminal management unit 321, a multi-AP management unit 322, and a schedule control unit 323.

[0108] As a terminal management function, the terminal management unit 321 manages information about non-AP_MLD that has a multi-AP connection with the sharing AP 30. The information for managing the terminal device 20 from the terminal management unit 321 is notified to the frame processing unit 312, and is used when the frame processing unit 312 distributes data and the like to the transmission / reception unit 313.

[0109] The multi-AP management unit 322 manages information related to multi-AP connections in the information communication system 1 A. The information related to multi-AP connections is notified to each shared AP 40 via the frame processing unit 312 and the associated transceiver unit 313, and is used to notify the terminal device 20 of information about the other shared APs 40 that make up the multi-AP by beacon.

[0110] The schedule control unit 323 manages the schedule of the R-TWT SP used in the multi-AP connection. The schedule control unit 323 schedules the R-TWT SP for the highest priority low-latency data to each shared AP 40 and assigns it to the link configured by each shared AP 40.

[0111] Note that each link (transmission path) may have a time period already reserved by another R-TWT SP. Therefore, the schedule control unit 323 may request information regarding unavailable periods of transmission from each shared AP 40 constituting the multi-AP connection, and based on the responses from each shared AP 40, adjust (e.g., shorten) the timing of the R-TWT SP assigned to each link to prevent collisions. If a collision occurs, the schedule control unit 323 may not perform scheduling for that link. Possible unavailable periods of transmission may include other periodic R-TWT SPs on each link, reservations by other BSSs (basic service sets) using the same channel, and reservations by NAV. The determined schedule is output to each shared AP 40, the frame processing unit 312, and each transceiver unit 313. The management unit 314 may also synchronize the internal time of each shared AP 40.

[0112] FIG. 16 is a table showing an example of information managed by the management unit 314 of the sharing AP 30 included in the information communication system 1A according to the second embodiment. As shown in FIG. 16, the management unit 314 manages information (identifiers, etc.) related to the non-AP_MLD to which the sharing AP 30 is connected, as well as information about the shared APs 40 via which the multi-AP connection is established. In this example, non-AP_MLD #1 is recorded as the identifier of the non-AP_MLD. Information (identifiers, etc.) about the shared APs 40-1, 40-2, and 40-3 is recorded as information about the shared APs 40 via which the multi-AP connection is established. By referencing this information, the management unit 314 can determine through which shared AP 40 subordinate to the sharing AP 30 the sharing AP 30 is connected to the non-AP_MLD #1.

[0113] <2-1-3-2> Functional Configuration of the Shared AP 40 Fig. 17 is a block diagram showing an example of the functional configuration of the shared AP 40 included in the information communication system 1A according to the second embodiment. As shown in Fig. 17, the shared AP 40 includes a MAC frame processing unit 411, a transmission / reception unit 412, and a management unit 413.

[0114] The MAC frame processing unit 411 is a functional block that executes processing corresponding to the MAC sublayer of the second layer. When data or the like is input from the sharing AP 30, the MAC frame processing unit 411 adds a MAC header to generate a MAC frame and outputs the MAC frame to the transceiver unit 412. The MAC frame processing unit 411 processes the MAC header of the frame input from the transceiver unit 412. The MAC frame processing unit 411 can also generate a MAC frame from management information such as a beacon input from the management unit 413 and output the MAC frame to the transceiver unit 412 or the sharing AP 30.

[0115] Specifically, when a MAC frame is input from the transmitting / receiving unit 412, the MAC frame processing unit 411 processes the MAC header and outputs the input frame to the sharing AP 30 or the beacon control unit 421 depending on the frame type. For example, when a data frame is input from the transmitting / receiving unit 412, the MAC frame processing unit 411 outputs the input frame to the sharing AP 30. When a control frame (beacon signal) including schedule information for the R-TWT function is input from the transmitting / receiving unit 412, the MAC frame processing unit 411 outputs the input frame to the beacon control unit 421.

[0116] The transceiver 412 is a functional block that executes processing corresponding to the first layer. The transceiver 412 generates a wireless frame by adding a preamble or the like to the MAC frame input from the MAC frame processing unit 411, and converts the generated wireless frame into a wireless signal. The transceiver 412 then transmits (radiates) the converted wireless signal via an antenna. The transceiver 412 also extracts a MAC frame from the wireless frame received by the antenna and outputs the extracted MAC frame to the MAC frame processing unit 411.

[0117] The management unit 413 manages the link state and wireless communication of the transmission / reception unit 412. The management unit 413 may also perform processing for establishing a multi-AP connection between the sharing AP 30 and the terminal device 20. The management unit 413 includes, for example, a beacon control unit 421 and an R-TWT processing unit 422.

[0118] The beacon control unit 421 generates a beacon signal and outputs it to the MAC frame processing unit 411. For example, the beacon signal may include the start time (TWT start time) and duration (TWT duration) of the common R-TWT SP, and the start time (TWT start time) and duration (TWT duration) of individual R-TWT SPs to be transmitted synchronously, based on the schedule information of the R-TWT SP input from the schedule control unit 211 of the sharing AP 30, or may include the transmission start time of individual data to be transmitted synchronously. If the beacon signal received from another access point (sharing AP 30 or shared AP 40) includes settings such as an R-TWT SP, the beacon control unit 421 notifies the schedule control unit 211 of the sharing AP 30.

[0119] The R-TWT processing unit 422 extracts the R-TWT SP corresponding to its own channel from the schedule information of the R-TWT SP input from the schedule control unit 211 of the sharing AP 30, and outputs a trigger frame at the start time of the R-TWT SP to the MAC frame processing unit 411. The trigger frame may include the duration or end time of the R-TWT SP, as well as the identifier of the target link of the next R-TWT SP, the TWT start time, and the TWT duration.

[0120] <2-2> Operation Hereinafter, the operation of the information communication system 1A according to the second embodiment will be described.

[0121] <2-2-1> R-TWT Function Setup Method Fig. 18 is a flowchart showing an example of a method for setting up the R-TWT function in the information communication system 1A according to the second embodiment. Fig. 18 shows a setup sequence for the R-TWT function when a multi-AP connection using three transmission paths (shared APs 40-1, 40-2, and 40-3) is established between the sharing AP 30 and the terminal device 20. Hereinafter, an example of a method for setting up the R-TWT function in the information communication system 1A according to the second embodiment will be described with reference to Fig. 18.

[0122] First, the sharing AP 30 transmits TWT information to each shared AP 40 (S21). The TWT information includes information about links (transmission paths) that can use the TWT function. Then, each shared AP 40 broadcasts a beacon signal that includes the TWT information (S22). This beacon signal can be received by each of A-STAs #1 to #3 of the terminal device 20. When each A-STA #1 to #3 receives the beacon signal, it acquires the TWT information and transmits it to the non-AP_MLD.

[0123] The non-AP_MLD transmits a TWT request to the sharing AP 30 based on the received TWT information (S23). The TWT request includes the identifier of the non-AP_MLD and information about A-STAs (links) available for multi-AP connection. The sharing AP 30 determines the target for R-TWT SP setup based on the TWT request received via at least one shared AP 40. The sharing AP 30 then transmits an R-TWT response to the non-AP_MLD (S24). The R-TWT response is transmitted via all shared APs 40 that are targets for R-TWT SP setup. When the non-AP_MLD receives the R-TWT response, the setup of the R-TWT function (TWT agreement setup) is completed.

[0124] Thereafter, the sharing AP 30 transmits schedule information to the shared AP 40 (S25). The schedule information includes information about the R-TWT SP set by the TWT agreement setup. Then, each shared AP 40 broadcasts a beacon signal including the schedule information (S26). This beacon signal can be received by each of the A-STAs #1 to #3 of the terminal device 20. When each of the A-STAs #1 to #3 receives the beacon signal, it acquires the schedule information and transmits it to the non-AP_MLD. This completes the scheduling of the R-TWT SP.

[0125] <2-2-2> Method of Using the R-TWT Function Fig. 19 is a flowchart showing an example of a method of using the R-TWT function in the information communication system according to the second embodiment. Hereinafter, with reference to Fig. 19, an example of a method of using the R-TWT function in the information communication system according to the second embodiment will be described.

[0126] The management unit 314 of the sharing AP 30 establishes a multi-AP connection with the terminal device 20 using multiple shared APs 40, schedules at least one R-TWT SP, and then starts the series of processes shown in FIG. 19 (start).

[0127] First, the schedule control unit 323 of the management unit 314 checks whether there is an R-TWT SP that does not include multiple R-TWT SPs in a single transmission path (shared AP 40) among the scheduled R-TWT SPs (S31).

[0128] In the process of S31, if the schedule control unit 323 confirms that there is an R-TWT SP that does not include multiple R-TWT SPs in a single transmission path among the scheduled R-TWT SPs, it proceeds to the process of S32 (S31: YES), and if it confirms that there is no R-TWT SP that does not include multiple R-TWT SPs, it proceeds to the process of S33 (S11: NO).

[0129] In the process of S32, the schedule control unit 323 sets the maximum length R-TWT SP as the common R-TWT SP, as in the first embodiment. When the process of S32 is completed, the schedule control unit 323 proceeds to the process of S34.

[0130] In the process of S33, the schedule control unit 323 sets the period of the R-TWT SP that has the longest period that does not overlap with other R-TWT SPs as the common R-TWT SP, as in the first embodiment. When the process of S33 is completed, the schedule control unit 323 proceeds to the process of S34.

[0131] In the process of S34, the management unit 314 notifies the terminal device 20 of schedule information including the common R-TWT SP. Specifically, the schedule control unit 323 of the management unit 314 uses the frame processing unit 312 and the transceiver unit 313 of each transmission path to transmit the schedule information to each shared AP 40 belonging to the sharing AP 30. Then, the beacon control unit 421 of the management unit 413 of each shared AP 40 generates a beacon signal including the received schedule information, and transmits (radiates) the wireless signal via the MAC frame processing unit 411 and the transceiver unit 412.

[0132] Upon completion of the process of S34, the schedule control unit 323 of the management unit 314 of the sharing AP 30 performs redundant transmission of high-priority low-latency traffic using the common R-TWT SP (S35). Specifically, the schedule control unit 323 notifies the frame processing unit 312 of schedule information including the common R-TWT SP. When transmitting uplink traffic, the frame processing unit 312 outputs a trigger frame instructing the transfer of low-latency traffic to each of the transceiver units 313 to which the common R-TWT SP is assigned, for example, based on the common TWT start time. As a result, the trigger frame is transmitted to the A-STA of the terminal device 20 via the shared AP 40 associated with each transceiver unit 313 to which the common R-TWT SP is assigned. Then, each A-STA of the terminal device 20 transmits low-latency traffic to the sharing AP 30 based on the trigger frame. When transmitting downlink traffic, the frame processing unit 312 outputs the downlink traffic to each of the transceiver units 313 to which a common R-TWT SP is assigned, for example, based on the common TWT start time. As a result, the downlink traffic is transmitted to the A-STA of the terminal device 20 via the shared AP 40 associated with each transceiver unit 313 to which a common R-TWT SP is assigned. In this way, in both the uplink and downlink directions, low-latency traffic can be redundantly transmitted via each of the multiple transmission paths in the multi-AP connection. It is sufficient that there are multiple transmission paths (shared APs 40) used for redundant transmission in the common R-TWT SP assigned to each link. When the processing of S35 is completed, the management unit 314 of the sharing AP 30 terminates the series of processing shown in FIG. 19.

[0133] As described above, in the information communication system 1A according to the second embodiment, the management unit 314 of the sharing AP 30 can redundantly transmit low-latency traffic at the same timing using multiple links in the common R-TWT SP.

[0134] <2-2-3> Specific Example of Communication Using the R-TWT Function Figure 20 is a time chart showing a specific example of communication using the R-TWT function in the information communication system according to the second embodiment. Figure 20 shows the processing sequence of the R-TWT function when a multi-AP connection using three transmission paths (shared APs 40-1, 40-2, and 40-3) is established between the sharing AP 30 and the terminal device 20. Below, with reference to Figure 20, a specific example of communication using the R-TWT function in the information communication system 1A according to the second embodiment will be described.

[0135] In this example, R-TWT SP1 to R-TWT SP3 are set as common R-TWT SPs in three transmission paths (shared APs 40-1 to 40-3) based on beacon signals containing schedule information for the R-TWT SPs. The length of each TWT duration of R-TWT SP1 to R-TWT SP3 corresponds to the common TWT duration CP. The common R-TWT SP is scheduled so that other R-TWT SPs do not overlap.

[0136] Time t0 corresponds to the common TWT start time CT. In this example, at time t0, each of R-TWT SP1 to R-TWT SP3 starts transmitting data D#1 corresponding to low latency traffic (LL). That is, data D#1 is redundantly transmitted using shared APs 40-1 to 40-3. Furthermore, in R-TWT SP1, after transmitting data D#1, transmission of data D#2 corresponding to non-low latency traffic (non-LL) starts. In R-TWT SP2, after transmitting data D#1, data D#3 corresponding to low latency traffic (LL) is transmitted. In R-TWT SP3, after transmitting data D#1, data D#4 corresponding to low latency traffic (LL) is transmitted. Time t1 corresponds to the TWT start time included in the common R-TWT SP. In this example, at time t1, data D#2 is being transmitted in R-TWT SP1, and therefore data D#5 corresponding to low latency traffic is being redundantly transmitted using each of R-TWT SP2 and R-TWT SP3. In this example, after data D#5 is transmitted in R-TWT SP2, data D#6 corresponding to low latency traffic (LL) is transmitted. Time t2 corresponds to the end time of the common R-TWT SP.

[0137] As described above, when transmitting the same data through the common R-TWT SP, the information communication system 1A synchronizes the transmission timing of the low-latency traffic through multiple transmission paths according to the traffic transmission status and the TWT start time set in the common R-TWT SP. The information communication system 1A can redundantly transmit the low-latency traffic (data D#1) by using the common R-TWT SPs (R-TWT SP1 to R-TWT SP3) set in each of the shared APs 40-1 to 40-3.

[0138] <2-3> Effects of the Second Embodiment In the information communication system 1A according to the second embodiment, similarly to the first embodiment, the R-TWT SPs scheduled for each transmission path are scheduled to a common R-TWT SP based on the R-TWT SP that transmits the highest priority low-latency traffic. Then, the sharing AP 30 uses the common R-TWT SP to redundantly transmit the highest priority low-latency traffic.

[0139] As a result, the information communication system 1A according to the second embodiment, like the first embodiment, can transmit low-latency traffic over other transmission paths that are less affected by interference, even if some of the multiple transmission paths constituting the multi-AP connection are affected by interference, etc. As a result, the information communication system 1A according to the second embodiment can more reliably transmit low-latency traffic and reduce the delay and jitter of the traffic. Therefore, the information communication system 1A according to the second embodiment can provide an access point and a terminal device that can meet the required delay of low-latency traffic.

[0140] <3> Others The conversion process from radio frames to radio signals described in the above embodiments includes, for example, convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform, OFDM modulation, and frequency conversion. The conversion process from radio signals to radio frames described in the above embodiments includes, for example, frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and Viterbi decoding.

[0141] In the above-described embodiments, the CPU 11 of the access point 10, the CPU 21 of the terminal device 20, the CPU of the sharing AP 30, and the CPU of the shared AP 40 may each be other circuits. For example, the access point 10, the terminal device 20, the sharing AP 30, and the shared AP 40 may each include an MPU (micro processing unit) or the like instead of a CPU. Each of the processes described in each embodiment may be realized by dedicated hardware. The processes of the access point 10, the terminal device 20, the sharing AP 30, and the shared AP 40 may be a mixture of processes executed by software and processes executed by hardware, or may be only one of them.

[0142] In the above embodiments, the flowcharts used to explain the operations are merely examples. The order of the processes of the operations described in the embodiments may be changed as far as possible, and other processes may be added. For example, the multi-link and multi-AP connection setup methods and R-TWT communication methods described in the above embodiments are merely examples. A wireless communication standard other than the IEEE 802.11 standard may be used as the wireless communication standard.

[0143] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention.

[0144] DESCRIPTION OF SYMBOLS 1, 1A... Information communication system 10... Access point 20... Terminal device 30... Sharing access point 40-1, 40-2, 40-3... Shared access points 11, 21... CPU 12, 22... ROM 13, 23... RAM 14, 24... Wireless communication module 15... Wired communication module 25... Display 26... Storage 111, 211, 323... Schedule control unit 112, 212... Data distribution unit 121... Beacon control unit 122... R-TWT control unit 123, 222, 312... Frame processing unit 124, 223, 313-1, 313-2, 313-3, 412... Transmitting / receiving unit 131, 231... Classification unit 132A, 132B, 132C, 132D, 232A, 232B, 232C, 232D... queues 133A, 133B, 133C, 133D, 233A, 233B, 233C, 233D... carrier sense execution units 134, 234... internal collision management units 221... beacon processing units 311... data processing units 314, 413... management units 321... terminal management units 322... multi-AP management units 411... MAC frame processing units 421... beacon control units 422... R-TWT processing units

Claims

1. An access point configured to transmit information between a terminal device and the access point using a plurality of wireless links including a first wireless link and a second wireless link, the access point being configured to set a service period for preferentially transmitting low-latency traffic on at least one of the plurality of wireless links, and comprising a management unit that, when a first service period is scheduled on the first wireless link, schedules a common service period for each of the first wireless link and the second wireless link based on the first service period, and notifies the terminal device of schedule information including information regarding the common service period.

2. The access point according to claim 1, wherein, during the common service period, first data is transmitted at the same timing through each of the first wireless link and the second wireless link.

3. The access point according to claim 1, wherein when there is a second service period in a scheduled service period that does not include multiple service periods in a single link, the management unit sets the second service period with the maximum length to the common service period.

4. The access point according to claim 1, wherein, when there is no second service period that does not include multiple service periods in a single link among the scheduled service periods, the management unit sets the period of the service period that has the longest period that does not overlap with other service periods as the common service period.

5. The access point according to claim 1, wherein the management unit transmits a trigger frame instructing transmission of first data to the terminal device using each of the first wireless link and the second wireless link based on a start time of the common service period.

6. An access point as described in any one of claims 1 to 5, further comprising: a first wireless signal processing unit that establishes the first wireless link with the terminal device; and a second wireless signal processing unit that establishes the second wireless link with the terminal device, wherein the management unit outputs the schedule information to each of the first wireless signal processing unit and the second wireless signal processing unit, and causes the first wireless signal processing unit and the second wireless signal processing unit to transmit beacon signals including the schedule information using the first wireless link and the second wireless link, respectively.

7. An access point as described in any one of claims 1 to 5, further comprising: a first transceiver unit connected to a first access point that establishes the first wireless link with the terminal device; and a second transceiver unit connected to a second access point that establishes the second wireless link with the terminal device, wherein the management unit transmits the schedule information to the first access point and the second access point via the first transceiver unit and the second transceiver unit, respectively, and causes the first access point and the second access point to transmit beacon signals including the schedule information using the first wireless link and the second wireless link, respectively.

8. A terminal device comprising: a first wireless signal processing unit that establishes a first wireless link with an access point; a second wireless signal processing unit that establishes a second wireless link with the access point; a data distribution unit that distributes data to the first wireless signal processing unit and the second wireless signal processing unit; and a schedule control unit that schedules a common service period for each of the first wireless link and the second wireless link based on schedule information received from the access point, wherein the data distribution unit outputs first data corresponding to low-latency traffic received from an upper layer to each of the first wireless signal processing unit and the second wireless signal processing unit at the same timing during the common service period.

9. The terminal device according to claim 8, wherein each of the first radio signal processing unit and the second radio signal processing unit transmits the first data to the access point based on receiving a trigger frame at a time based on a start time of the common service period.