Access point, terminal device, and communication methods therefor

Abstract

An access point, which is a first access point, constitutes a communication system together with a second access point, a third access point, and a terminal device. The first access point is configured to transmit a timestamp related to a first timer corresponding to the first access point to a second access point and a third access point, receive a first offset between the first timer and a second timer corresponding to the second access point from the second access point, and receive a second offset between the first timer and a third timer corresponding to the third access point from the third access point. The first offset and the second offset are transmitted to the second access point and the third access point, respectively.

Description

TECHNICAL FIELD

[0001] Embodiments relate to an access point, a terminal device, and a communication method thereof. BACKGROUND

[0002] As a communication system that performs wireless connection between an access point (AP) and a terminal device, a multi-link transmission method using a wireless LAN (local area network) is known.

[0003] In the multi-link transmission method, data exchange between a multi-link device (AP-type MLD (multi-link device)) within an access point and a multi-link device (non-AP-type AP) within a terminal device is implemented through wireless links between a plurality of affiliated APs within the access point and a plurality of affiliated STAs within the terminal.

[0004] As coordination work between a plurality of affiliated APs in the multi-link transmission method, an R-TWT (restricted target wake time) technique and the like have been proposed.

[0005] PRIOR ART DOCUMENTS

[0006] NON-PATENT DOCUMENTS

[0007] Non-Patent Document 1: IEEE 802.11be D3.0, “35.3 Multi-link operation”, “35.8 Restricted TWT”, pp. 479-586, pp. 617-621, January 2023 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] From the viewpoint of improving the wireless communication environment, as a terminal device, it is desirable to establish a transmission method (multi-AP transmission method) that can simultaneously use wireless links between a plurality of affiliated APs possessed by a plurality of access points.

[0010] However, a plurality of access points operate based on different time information, respectively. Therefore, when coordination work between a plurality of access points is performed in the multi-AP transmission method, in order to maintain a good wireless communication environment, time synchronization between a plurality of access points and a terminal device can be required.

[0011] The present invention has been made in view of the above circumstances, and an object thereof is to provide a shared access point, a shared access point, a terminal device, and a communication method thereof that improve the wireless communication environment.

[0012] Technical solution for solving technical problems

[0013] The access point of the first aspect constitutes a communication system together with the second access point, the third access point, and the terminal device. The first access point is configured to transmit a time stamp related to a first timer corresponding to the first access point to the second access point and the third access point, receive a first offset between the first timer and a second timer corresponding to the second access point from the second access point, receive a second offset between the first timer and a third timer corresponding to the third access point from the third access point, and transmit the first offset and the second offset to the second access point and the third access point, respectively.

[0014] Effects of the invention

[0015] According to the embodiments, it is possible to provide a shared access point, a shared access point, a terminal device, and a communication method thereof that improve a wireless communication environment. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a block diagram showing a configuration of a communication system of the first embodiment.

[0017] Figure 2 is a block diagram showing an example of a hardware configuration of a shared AP of the first embodiment.

[0018] Figure 3 is a block diagram showing an example of a hardware configuration of a shared AP of the first embodiment.

[0019] Figure 4 is a block diagram showing an example of a hardware configuration of a terminal device of the first embodiment.

[0020] Figure 5 is a block diagram showing an example of a functional configuration of a shared AP of the first embodiment.

[0021] Figure 6 is a diagram showing an example of a data structure of multi-AP management information stored in a shared AP of the first embodiment.

[0022] Figure 7 is a diagram showing an example of a data structure of terminal management information stored in a shared AP of the first embodiment.

[0023] Figure 8 is a diagram showing an example of a data structure of time management information stored in a shared AP of the first embodiment.

[0024] Figure 9is a diagram showing an example of a beacon frame transmitted from the shared AP of the first embodiment with respect to time synchronization.

[0025] Figure 10 is a block diagram showing an example of a functional structure of the shared AP of the first embodiment.

[0026] Figure 11 is a diagram showing an example of a data structure of link management information stored in the shared AP of the first embodiment.

[0027] Figure 12 is a diagram showing an example of a beacon frame transmitted from the shared AP of the first embodiment with respect to time synchronization.

[0028] Figure 13 is a block diagram showing an example of a functional structure of the terminal device of the first embodiment.

[0029] Figure 14 is a diagram showing an example of a data structure of link management information stored in the terminal device of the first embodiment.

[0030] Figure 15 is a sequence diagram showing an example of time synchronization processing in the communication system of the first embodiment.

[0031] Figure 16 is a sequence diagram showing an example of R-TWT coordination processing in the communication system of the first embodiment.

[0032] Figure 17 is a block diagram showing an example of a functional structure of the shared AP of the second embodiment.

[0033] Figure 18 is a sequence diagram showing an example of reference timer generation processing in the communication system of the second embodiment.

[0034] Figure 19 is a block diagram showing an example of a functional structure of the shared AP of the first modified example.

[0035] Figure 20 is a block diagram showing a structure of the communication system of the second modified example.

[0036] Reference Signs

[0037] 1, 1C: communication system; 5: housing; 10: sharing AP; 20: shared AP; 30: terminal device; 40: network; 11, 21, 31: CPU; 12, 22, 32: ROM; 13, 23, 33: RAM; 14, 24, 34: wireless communication module; 15: wired communication module; 16, 25, 37: oscillator; 35: display; 36: storage; 100, 100A, 100B: reference timer generation section; 110, 310: data processing section; 120, 210, 320: management section; 130, 220, 330: frame processing section; 140, 150, 230, 240, 340, 350: wireless signal processing section; 300: application execution section; 360, 370: TSF timer management section; 121: multi-AP management information; 122: terminal management information; 123: time management information; 211, 321: link management information. DETAILED DESCRIPTION

[0038] Embodiments will be described below with reference to the accompanying drawings. In the following description, components having the same function and structure are attached with the same reference numerals.

[0039] 1. First Embodiment

[0040] 1.1 Structure

[0041] 1.1.1 Communication System

[0042] Figure 1 is a block diagram showing an example of the structure of the communication system of the first embodiment. As shown in Figure 1 , the communication system 1 is provided with a sharing AP (sharing access point) 10 as a first access point, shared APs (shared access points) 20-1 and 20-2 as second and third access points, a terminal device 30, and a network 40.

[0043] The sharing AP 10, the shared APs 20-1 and 20-2, and the terminal device 30 have wireless communication functions based on, for example, an OSI (open systems interconnection) reference model. In the OSI reference model, the 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 an LLC (logical link control) sublayer and a MAC (media access control) sublayer.

[0044] Specifically, the shared AP 10 is, for example, an access point of a wireless LAN. The shared AP 10 includes an AP-type MLD. The AP-type MLD is a multi-link device (MLD) within the shared AP 10, and is an entity configured to logically perform wireless connection with the terminal device 30. That is, the AP-type MLD can serve as a terminal in data exchange in wireless communication between the shared AP 10 and the terminal device 30. The AP-type MLD is configured to communicate with a server (not shown) on a network 40 via wire or wireless. The AP-type MLD is configured to communicate with each of the shared APs 20-1 and 20-2 via wire or wireless.

[0045] Each of the shared APs 20-1 and 20-2 is, for example, an access point of a wireless LAN. The shared APs 20-1 and 20-2 are different access points from each other, and are disposed at physically separate locations from each other. Therefore, the shared APs 20-1 and 20-2 can have different communicable areas from each other, respectively. The shared APs 20-1 and 20-2 include an affiliated AP 1 and an affiliated AP 2, respectively. Each of the affiliated APs 1 and 2 is an entity configured to physically perform wireless connection with the terminal device 30. That is, each of the affiliated APs 1 and 2 has a physical structure to exchange data using a wireless link with the terminal device 30. Each of the affiliated APs 1 and 2 belongs to the AP-type MLD. Here, the "affiliated AP belonging to the AP-type MLD" means that the affiliated AP can be used in data exchange between the AP-type MLD and the terminal device.

[0046] Further, the shared APs 20-1 and 20-2 have mutually identical structures. Hereinafter, when the shared APs 20-1 and 20-2 are not particularly distinguished, it is sometimes described as the shared AP 20. In addition, when the affiliated APs 1 and 2 are not particularly distinguished, it is sometimes described as the affiliated AP.

[0047] The terminal device 30 is, for example, a smartphone or a PC (personal computer), and is a portable wireless terminal device compliant with the IEEE 802.11 standard. The terminal device 30 includes a non-AP-type MLD, an affiliated STA 1, and an affiliated STA 2.

[0048] The non-AP-type MLD is a multi-link device within the terminal device 30, and is an entity configured to logically perform wireless connection with the shared AP 10. That is, the non-AP-type MLD can be a terminal in data exchange in wireless communication between the terminal device 30 and the shared AP 10. The non-AP-type MLD is connected to the affiliated STAs 1 and 2 via wire.

[0049] Each of the affiliated STAs 1 and 2 is an entity configured to perform wireless connection physically with the affiliated AP. That is, each of the affiliated STAs 1 and 2 has a physical structure to exchange data through a wireless link with the affiliated AP. Each of the affiliated STAs 1 and 2 belongs to a non-AP MLD. Here, by the phrase "the affiliated STA belongs to the non-AP MLD", it means that the affiliated STA can be used in data exchange between the non-AP MLD and the AP MLD.

[0050] Further, the affiliated STAs 1 and 2 have mutually equivalent structures. Hereinafter, when the affiliated STAs 1 and 2 are not particularly distinguished, it is sometimes described as the affiliated STA.

[0051] In the present embodiment, the AP MLD and the non-AP MLD are configured to perform data exchange through wireless links between a plurality of affiliated APs provided in mutually different access points and a plurality of affiliated STAs provided in the same terminal device 30. This data transmission method is also referred to as a multi-AP transmission method.

[0052] Figure 1 In the example of FIG. 10, the case is shown in which the AP MLD in the shared AP 10 and the non-AP MLD in the terminal device 30 use the wireless link between the affiliated AP 1 in the shared AP 20-1 and the affiliated STA 1 in the terminal device 30 and the wireless link between the affiliated AP 2 in the shared AP 20-2 and the affiliated STA 2 in the terminal device 30 to exchange data.

[0053] Hereinafter, for convenience of explanation, a case in which the shared AP 10 and the shared AP 20 are connected via wireless is described.

[0054] 1.1.2 Hardware structure

[0055] Next, the hardware structure of the shared AP, the shared AP, and the terminal device in the communication system of the first embodiment is described.

[0056] 1.1.2.1 Hardware structure of shared AP

[0057] Figure 2 is a block diagram showing an example of the hardware structure of the shared AP of the first embodiment. As shown in FIG. 11, the shared AP 10 includes a CPU 101, a ROM 102, a RAM 103, a host bus 104, a bridge 105, a CPU bus 106, an interface 107, a hard disk drive (HDD) 108, and a display 109. Figure 2As shown, the shared AP 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, a wired communication module 15, and an oscillator 16.

[0058] The CPU 11 is a processing circuit that controls the overall operation of the shared AP 10. The ROM 12 is, for example, a nonvolatile semiconductor memory. The ROM 12 stores programs and data for controlling the shared AP 10. The RAM 13 is, for example, a volatile semiconductor memory. The RAM 13 is used as a work area of the CPU 11. The wireless communication module 14 is a circuit for transceiving data through wireless signals. The wireless communication module 14 is connected to an antenna. The wired communication module 15 is a circuit for transceiving data through wired signals. The wired communication module 15 is connected to the network 40. The oscillator 16 is used as a clock for generating time information used within the shared AP 10. The time information is also referred to as a TSF (time synchronization function) timer. The TSF timer generated by the oscillator 16 is highly accurate to the extent that it can be used as a TSF timer (reference timer) that is used as a reference when the shared AP 10, the shared AP 20, and the terminal device 30 operate in synchronization with each other. In the first embodiment, the TSF timer generated by the oscillator 16 coincides with the reference timer.

[0059] 1.1.2.2 Hardware structure of shared AP

[0060] Figure 3 is a block diagram showing an example of the hardware structure of the shared AP of the first embodiment. As shown, the shared AP 20 includes, for example, a CPU 21, a ROM 22, a RAM 23, a wireless communication module 24, and an oscillator 25. Figure 3

[0061] ​The CPU 21 is a processing circuit that controls the overall operation of the shared AP 20. The ROM 22 is, for example, a nonvolatile semiconductor memory. The ROM 22 stores programs and data for controlling the shared AP 20. The RAM 23 is, for example, a volatile semiconductor memory. The RAM 23 is used as a work area of the CPU 21. The wireless communication module 24 is a circuit for transmitting and receiving data by wireless signals. The wireless communication module 24 is connected to an antenna. The oscillator 25 operates independently of the oscillators 16 and 25, and functions as a clock for generating a TSF timer used within the shared AP 20. The TSF timer generated by the oscillator 25 does not need to be as accurate as a reference timer. That is, the TSF timer generated by the oscillator 25 can be offset from the reference timer.

[0062] 1.1.2.3 Hardware structure of terminal device

[0063] Figure 4 is a block diagram showing an example of the hardware structure of the terminal device of the first embodiment. As shown in Figure 4 , the terminal device 30 is provided with, for example, a CPU 31, a ROM 32, a RAM 33, a wireless communication module 34, a display 35, a storage 36, and an oscillator 37.

[0064] The CPU 31 is a processing circuit that controls the overall operation of the terminal device 30. The ROM 32 is, for example, a nonvolatile semiconductor memory. The ROM 32 stores programs and data for controlling the terminal device 30. The RAM 33 is, for example, a volatile semiconductor memory. The RAM 33 is used as a work area of the CPU 31. The wireless communication module 34 is a circuit for transmitting and receiving data by wireless signals. The wireless communication module 34 is connected to an antenna. The display 35 is, for example, an LCD (liquid crystal display) or an EL (electro-luminescence) display. The display 35 displays a GUI (graphical user interface) or the like corresponding to application software. The storage 36 is a nonvolatile storage device. The storage 36 stores system software or the like of the terminal device 30. The oscillator 37 operates independently of the oscillators 16 and 25, and functions as a clock for generating a TSF timer used within the terminal device 30. The TSF timer generated by the oscillator 37 does not need to be as accurate as a reference timer. That is, the TSF timer generated by the oscillator 37 can be offset from the reference timer.

[0065] 1.1.3 Functional structure

[0066] Next, the functional structure of the shared AP, the shared AP, and the terminal device in the communication system of the first embodiment will be described.

[0067] 1.1.3.1 Functional configuration of shared AP

[0068] Figure 5 is a block diagram illustrating an example of the functional configuration of the shared AP of the first embodiment.

[0069] The shared AP 10 functions as a computer that has a reference timer generation section 100, a data processing section 110, a management section 120, a frame processing section 130, and wireless signal processing sections 140 and 150. The data processing section 110 is a functional block that performs processing corresponding to the LLC sublayer of the second layer and the third to seventh layers. The management section 120 and the frame processing section 130 are functional blocks that perform processing corresponding to the MAC sublayer of the second layer. The wireless signal processing sections 140 and 150 are functional blocks that perform processing corresponding to the first layer. The reference timer generation section 100, the data processing section 110, the management section 120, and the frame processing section 130 function as an AP-type MLD.

[0070] The reference timer generation section 100 generates a reference timer on the basis of the output of the oscillator 16. The reference timer generation section 100 outputs the generated reference timer to the management section 120.

[0071] The data processing section 110 outputs data input from the network 40 via the LLC layer to the frame processing section 130. In addition, the data processing section 110 outputs data input from the frame processing section 130 to the network 40 via the LLC layer.

[0072] The management section 120 controls logical wireless connections between the AP-type MLD and the non-AP-type MLD in the multi-AP transmission scheme. For example, the management section 120 performs multi-AP connection processing in response to an association request from the terminal device 30. The management section 120 also manages the deviation (offset) of the reference timer from the TSF timer applicable in each shared AP 20-1 and 20-2. The multi-AP management information 121, the terminal management information 122, and the time management information 123 are stored in the management section 120.

[0073] Figure 6 is a diagram illustrating an example of the data structure of the multi-AP management information stored in the shared AP of the first embodiment.

[0074] As shown in Figure 6 , the multi-AP management information 121 stores information on various entities on the access point side (i.e., the AP-type MLD, the affiliated AP 1, and the affiliated AP 2) used in the multi-AP transmission scheme. Specifically, the information on the various entities on the access point side used in the multi-AP transmission scheme includes, for example, an identifier, a frequency band, capability information, and operation parameters.

[0075] The identifier includes, for example, a MAC address of the corresponding entity.

[0076] The frequency band includes information indicating a frequency band used by the corresponding entity. As the frequency band, for example, a 2.4 GHz band, a 5 GHz band, a 6 GHz band, a 45 GHz band, and a 60 GHz band, and the like can be applied. A plurality of channels are included in each frequency band.

[0077] The capability information includes, for example, information indicating whether or not the corresponding entity supports the multi-AP transmission method.

[0078] The operating parameter includes, for example, CWmin, CWmax, AIFS (arbitration interframe space), and TXOP (transmission opportunity) Limit. CWmin and CWmax indicate a minimum value and a maximum value of a contention window, respectively. The contention window is a parameter for calculating backoff, that is, a transmission waiting time for collision avoidance. The AIFS is a fixed transmission waiting time set for each traffic access category. The traffic access category includes, for example, "VO (voice)", "VI (video)", "BE (best effort)", "BK (background)", and "LL (low latency)". The TXOPLimit indicates an upper limit value of a TXOP (transmission opportunity period) of a channel.

[0079] Further, the frequency band, the capability information, and the operating parameter related to the AP-type MLD can not be stored.

[0080] Figure 7 is a diagram illustrating an example of a data structure of the terminal management information stored in the shared AP of the first embodiment.

[0081] As shown in Figure 7 , the terminal management information 122 stores information on connection states of the terminal device 30 wirelessly connected to the shared AP 10 in the multi-AP transmission method. Specifically, for example, the terminal management information 122 stores a group of an identifier of a non-AP-type MLD, an identifier of the affiliated STA 1, and an identifier of the affiliated AP in wireless connection with the affiliated STA 1, and a group of an identifier of the affiliated STA 2 and an identifier of the affiliated AP in wireless connection with the affiliated STA 2. Here, the identifier includes a MAC address of the target entity.

[0082] In the case of the connection example shown in Figure 1 , the affiliated AP in wireless connection with the affiliated STA 1 and the affiliated AP in wireless connection with the affiliated STA 2 are the affiliated AP 1 and the affiliated AP 2, respectively.

[0083] Before initiating multi-AP connection, the management unit 120 uses the wireless signal processing units 140 and 150 to send MAC frames (beacon frames) containing information stored in the multi-AP management information 121 to the shared APs 20-1 and 20-2 belonging to the shared AP 10. Additionally, during association processing, the management unit 120 uses the wireless signal processing units 140 and 150 to send association notifications based on the multi-AP management information 121 and the terminal management information 122 to the shared APs 20-1 and 20-2 belonging to the shared AP 10.

[0084] Figure 8 This is a diagram illustrating an example of a data structure for storing time management information in a shared AP in the first embodiment.

[0085] like Figure 8 As shown, the time management information 123 stores information about the offset of the TSF timer applicable in shared APs 20-1 and 20-2 relative to the reference timer at a certain time (time stamp).

[0086] For example, when the TSF timer of shared AP 20-1 is offset by +X (>0) seconds relative to the base timer, the TSF timer of shared AP 20-1 is X seconds faster than the base timer. When the TSF timer of shared AP 20-2 is offset by -X (<0) seconds relative to the base timer, the TSF timer of shared AP 20-2 is X seconds slower than the base timer.

[0087] After the multi-AP connection begins, the management unit 120 uses the wireless signal processing units 140 and 150 to send beacon frames about time synchronization to the shared APs 20-1 and 20-2 belonging to the shared AP 10.

[0088] Figure 9 This is a diagram illustrating an example of a time-synchronization beacon frame sent from a shared AP in the first embodiment.

[0089] like Figure 9 As shown, the beacon frame for time synchronization sent from shared AP 10 contains information stored in time management information 123. Specifically, for example, the beacon frame contains the identifier of shared AP 10, the timestamp of the reference timer, the offset of the TSF timer of shared AP 20-1 relative to the reference timer, and the offset of the TSF timer of shared AP 20-2 relative to the reference timer. Here, the identifier of shared AP 10 can also be referred to as the identifier of AP-type MLD.

[0090] Refer again Figure 5 The functional structure of the shared AP 10 is explained.

[0091] When data is input from the data processing section 110 or the management section 120, the frame processing section 130 adds a MAC header to the input data to generate a MAC frame. Then, the frame processing section 130 distributes the MAC frame to any of the wireless signal processing sections 140 and 150. The frame processing section 130 can determine the distribution destination of the MAC frame in accordance with a TID (traffic identifier) associated with an access category.

[0092] In addition, when a MAC frame is input from the wireless signal processing sections 140 and 150, the frame processing section 130 extracts data from the MAC frame and outputs the extracted data to the data processing section 110 or the management section 120 in accordance with the kind of the MAC frame. Specifically, when the MAC frame is a data frame, the frame processing section 130 inputs the data to the data processing section 110. When the MAC frame is a management frame or a control frame, the frame processing section 130 inputs the data to the management section 120.

[0093] Each of the wireless signal processing sections 140 and 150 adds a preamble or the like to the MAC frame input from the frame processing section 130 to generate a wireless frame. Each of the wireless signal processing sections 140 and 150 transforms the generated wireless frame into a wireless signal. Then, each of the wireless signal processing sections 140 and 150 radiates (transmits) the transformed wireless signal via an antenna. As the transformation processing from the wireless frame to the wireless signal, for example, convolutional encoding processing, interleaving processing, subcarrier modulation processing, inverse fast Fourier transform processing, OFDM modulation processing, and frequency transformation processing are included. In addition, each of the wireless signal processing sections 140 and 150 transforms a wireless signal received via an antenna from the corresponding shared AP 20 into a wireless frame. As the transformation processing from the wireless signal to the wireless frame, for example, frequency transformation processing, OFDM demodulation processing, fast Fourier transform processing, subcarrier demodulation processing, deinterleaving processing, and Viterbi decoding processing are included. Each of the wireless signal processing sections 140 and 150 extracts a MAC frame from the transformed wireless frame. Then, each of the wireless signal processing sections 140 and 150 outputs the extracted MAC frame to the frame processing section 130.

[0094] Further, the wireless signal processing sections 140 and 150 are configured to use mutually different frequency bands or channels to transmit and receive wireless signals. For example, the wireless signal processing section 140 is used to individually transmit a wireless signal to the one wireless signal processing section of the shared AP 20-1. In addition, the wireless signal processing section 150 is used to individually transmit a wireless signal to the one wireless signal processing section of the shared AP 20-2. In addition, for example, the wireless signal processing sections 140 and 150 can also be used to transmit a wireless signal containing the same information to a plurality of shared APs.

[0095] 1.1.3.2 Functional Configuration of Shared AP

[0096] Figure 10 is a block diagram showing an example of a functional structure of the shared AP of the first embodiment.

[0097] The shared AP 20 functions as a computer having a management section 210, a frame processing section 220, and wireless signal processing sections 230 and 240. The management section 210 and the frame processing section 220 are functional blocks that perform processing corresponding to the MAC sublayer of the second layer. The wireless signal processing sections 230 and 240 are functional blocks that perform processing corresponding to the first layer. The management section 210, the frame processing section 220, and the wireless signal processing section 240 function as a dependent AP.

[0098] Before starting the multi-AP transmission scheme, the management section 210 generates a beacon frame containing information on the multi-AP transmission scheme. The beacon frame on the multi-AP transmission scheme contains the multi-AP management information 121 received from the shared AP 10. More specifically, the beacon frame on the multi-AP transmission scheme contains the identifier of the AP-type MLD and the identifiers, frequencies, and operating parameters of all the dependent APs belonging to the AP-type MLD and supporting the multi-AP transmission scheme. The management section 210 notifies the terminal device 30 of the generated beacon frame on the multi-AP transmission scheme via the wireless signal processing section 240.

[0099] In addition, the management section 210 manages the state of the physical wireless connection with the dependent STA in the multi-AP transmission scheme. Specifically, for example, the link management information 211 is stored in the management section 210. The multi-AP management information 121 transmitted from the shared AP 10 can also be stored in the management section 210.

[0100] Figure 11 is a diagram showing an example of the data structure of the link management information stored in the shared AP of the first embodiment.

[0101] As shown in Figure 11 , the link management information 211 stores information on the dependent STA that is physically wirelessly connected with the dependent AP within the shared AP 20 in the multi-AP transmission scheme. Specifically, the information on the dependent STA connected with the dependent AP within the shared AP 20 includes, for example, an identifier.

[0102] The identifier includes, for example, the MAC address of the dependent STA. In the case of the connection example shown in Figure 1 , the MAC address of the dependent STA 1 is contained in the link management information 211 within the shared AP 20-1. In addition, the MAC address of the dependent STA 2 is contained in the link management information 211 within the shared AP 20-2.

[0103] In addition, after the multi-AP connection is started, the management unit 210 manages the TSF timer applicable in the own station so that the offset from the reference timer converges within a threshold (for example, ±15 μs) and shares the offset with the shared AP 10. Then, the management unit 210 transmits a beacon frame for time synchronization with the terminal device 30 using the wireless signal processing unit 240. The management unit 210 can further store the time management information 123 transmitted from the shared AP 10.

[0104] Figure 12 is a diagram showing an example of a beacon frame for time synchronization transmitted from the shared AP of the first embodiment.

[0105] As shown in Figure 12 , the beacon frame for time synchronization transmitted from the shared AP 20 includes information on the TSF timer applicable in the own station. Specifically, for example, the beacon frame includes the identifier of the shared AP 10, the identifier of the shared AP 20 of the own station, the timestamp of the TSF timer of the shared AP 20 of the own station, and the offset of the TSF timer of the shared AP 20 of the other station. Here, the offset of the TSF timer of the shared AP 20 of the other station can be either the offset from the TSF timer of the shared AP 20 of the own station or the offset from the reference timer. When the offset of the TSF timer of the shared AP 20 of the other station is the offset from the reference timer, the beacon frame further includes the timestamp of the reference timer or the offset of the TSF timer of the shared AP 20 of the own station from the reference timer. In addition, the offset of the TSF timer of the shared AP 20 of the other station can not be included in the beacon frame but transmitted to the terminal device 30 in response to a request from the terminal device 30 side.

[0106] Referring again to Figure 10 , the functional structure of the shared AP 20 will be described.

[0107] When a MAC frame is input from the shared AP 10 via the wireless signal processing unit 230, the frame processing unit 220 extracts data from the MAC frame and performs processing corresponding to the kind of the MAC frame. Specifically, when the MAC frame is a data frame, the frame processing unit 220 re-assigns a MAC header to the data and inputs to the wireless signal processing unit 240. When the MAC frame is a management frame or a control frame, the data is input to the management unit 210. In addition, when a MAC frame is input from an affiliated STA wirelessly connected via the wireless signal processing unit 240, the frame processing unit 220 re-assigns a MAC header to the data extracted from the MAC frame and inputs to the wireless signal processing unit 230.

[0108] The wireless signal processing sections 230 and 240 attach a preamble or the like to the MAC frame input from the frame processing section 220 to generate a wireless frame. The wireless signal processing sections 230 and 240 transform the generated wireless frame into a wireless signal. Then, the wireless signal processing sections 230 and 240 radiate (transmit) the transformed wireless signal via an antenna to the shared AP 10 and the wirelessly connected affiliated STA, respectively. As the transformation processing from the wireless frame to the wireless signal, for example, convolutional encoding processing, interleaving processing, subcarrier modulation processing, inverse fast Fourier transform processing, OFDM (orthogonal frequency division multiplexing) modulation processing, and frequency transformation processing are included. In addition, the wireless signal processing section 230 transforms the wireless signal received via the antenna from the shared AP 10 into a wireless frame. The wireless signal processing section 240 transforms the wireless signal received via the antenna from the terminal device 30 into a wireless frame. As the transformation processing from the wireless signal to the wireless frame, for example, frequency transformation processing, OFDM demodulation processing, fast Fourier transform processing, subcarrier demodulation processing, deinterleaving processing, and Viterbi decoding processing are included. The wireless signal processing sections 230 and 240 extract the MAC frame from the transformed wireless frame. Then, the wireless signal processing sections 230 and 240 input the extracted MAC frame to the frame processing section 220.

[0109] 1.1.3.3 Functional structure of terminal device

[0110] Figure 13 is a block diagram showing an example of the functional structure of the terminal device of the first embodiment.

[0111] The terminal device 30 functions as a computer provided with an application execution section 300, a data processing section 310, a management section 320, a frame processing section 330, wireless signal processing sections 340 and 350, and TSF timer management sections 360 and 370. The application execution section 300 is a functional block that executes processing corresponding to the seventh layer. The data processing section 310 is a functional block that executes processing corresponding to the LLC sublayer of the second layer and the third to sixth layers. The management section 320 and the frame processing section 330 are functional blocks that execute processing corresponding to the MAC sublayer of the second layer. The wireless signal processing sections 340 and 350 and the TSF timer management sections 360 and 370 are functional blocks that execute processing corresponding to the first layer. The data processing section 310, the management section 320, and the frame processing section 330 function as a non-AP MLD. The wireless signal processing section 340 and the TSF timer management section 360 function as an affiliated STA 1. The wireless signal processing section 350 and the TSF timer management section 370 function as an affiliated STA 2.

[0112] The application execution section 300 executes an application based on data input from the data processing section 310. In addition, the application execution section 300 inputs data to the data processing section 310. For example, the application execution section 300 can display application information on the display 35. In addition, the application execution section 300 can operate based on an operation of the input interface.

[0113] The data processing section 310 outputs data input from the application execution section 300 via the LLC layer to the frame processing section 330. In addition, the data processing section 310 outputs data input from the frame processing section 330 to the application execution section 300 via the LLC layer.

[0114] The management section 320 controls a logical wireless connection between an AP type MLD and a non-AP type MLD in the multi-AP transmission method. For example, the management section 320 generates an association request based on a beacon frame on multi-AP connection from the sharing AP 20. The link management information 321 is stored in the management section 320. In addition, information included in the beacon frame on multi-AP connection from the sharing AP 20 in the multi-AP management information 121 is also stored in the management section 320.

[0115] Figure 14 is a diagram illustrating an example of a data structure of the link management information stored in the terminal device of the first embodiment. Figure 14 The data structure of the link management information 321 is illustrated in

[0116] As illustrated in Figure 14 , the link management information 321 stores information on the subordinate APs that are physically connected to the subordinate STA 1 and the subordinate STA 2 in the terminal device 30, respectively, in the multi-AP transmission method. Specifically, the information on the subordinate APs that are physically connected to the subordinate STA 1 and the subordinate STA 2, respectively, includes an identifier, for example.

[0117] The identifier includes the MAC address of the subordinate AP, for example. In the case of the connection example illustrated in Figure 1 , the MAC address of the subordinate AP 1 that is connected to the subordinate STA 1 and the MAC address of the subordinate AP 2 that is connected to the subordinate STA 2 are stored in the link management information 321.

[0118] Referring back to Figure 10 , the functional structure of the terminal device 30 will be described.

[0119] In the management section 320, information identical to the time management information 123 is stored based on the beacon frame from the shared AP 20 regarding time synchronization. Then, the management section 320 manages the deviation between the TSF timer of the shared AP 20 and the TSF timer applicable in the non-AP MLD, the respective affiliated STAs 1 and 2. Specifically, the management section 320 notifies the TSF timer management section 360 of information regarding the TSF timer of the shared AP 20-1 including the affiliated AP 1 as the wireless connection destination of the affiliated STA 1. The management section 320 notifies the TSF timer management section 370 of information regarding the TSF timer of the shared AP 20-2 including the affiliated AP 2 as the wireless connection destination of the affiliated STA 2. In addition, when the information regarding the reference timer is included in the beacon frame from the shared AP 20 regarding time synchronization, the management section 320 can also synchronize the TSF timer of the non-AP MLD with the reference timer.

[0120] When data is input from the data processing section 310, the frame processing section 330 attaches a MAC header to the input data to generate a MAC frame. Then, the frame processing section 330 distributes the MAC frame to any of the wireless signal processing sections 340 and 350. The frame processing section 330 can also decide the distribution destination of the MAC frame according to the TID.

[0121] In addition, when a MAC frame is input from the wireless signal processing sections 340 and 350, the frame processing section 330 extracts data from the MAC frame and outputs the extracted data to the data processing section 310 or the management section 320 according to the kind of the MAC frame. Specifically, when the MAC frame is a data frame, the frame processing section 330 inputs the data to the data processing section 310. When the MAC frame is a management frame or a control frame, the frame processing section 330 inputs the data to the management section 320.

[0122] The wireless signal processing sections 340 and 350 attach a preamble or the like to the MAC frame input from the frame processing section 330 to generate a wireless frame. The wireless signal processing sections 340 and 350 transform the generated wireless frame into a wireless signal. Then, the wireless signal processing sections 340 and 350 radiate (transmit) the transformed wireless signal via an antenna. As the transformation processing from the wireless frame to the wireless signal, convolutional encoding processing, interleaving processing, subcarrier modulation processing, inverse fast Fourier transform processing, OFDM modulation processing, and frequency transformation processing are included, for example. In addition, the wireless signal processing sections 340 and 350 transform the wireless signal received via the antenna from the corresponding shared AP 20 into a wireless frame. As the transformation processing from the wireless signal to the wireless frame, frequency transformation processing, OFDM demodulation processing, fast Fourier transform processing, subcarrier demodulation processing, deinterleaving processing, and Viterbi decoding processing are included, for example. The wireless signal processing sections 340 and 350 extract the MAC frame from the transformed wireless frame. Then, the wireless signal processing sections 340 and 350 input the extracted MAC frame to the frame processing section 330.

[0123] The TSF timer management sections 360 and 370 manage the TSF timer of the affiliated STA 1 and the TSF timer of the affiliated STA 2, respectively, on the basis of the information on the offset notified from the management section 320. Specifically, the TSF timer management section 360 synchronizes the TSF timer of the affiliated STA 1 with the TSF timer of the shared AP 20-1 notified from the management section 320. The TSF timer management section 370 synchronizes the TSF timer of the affiliated STA 2 with the TSF timer of the shared AP 20-1 notified from the management section 320.

[0124] As such, the terminal device 30 generates three TSF timers suitable for the non-AP MLD, the affiliated STA 1, and the affiliated STA 2, respectively, on the basis of the oscillator 37. Then, the terminal device 30 synchronizes the TSF timer of the non-AP MLD with the reference timer, synchronizes the TSF timer of the affiliated STA 1 with the TSF timer of the shared AP 20-1, and synchronizes the TSF timer of the affiliated STA 2 with the TSF timer of the shared AP 20-2.

[0125] 1.2 Operation

[0126] Next, the operation in the communication system of the first embodiment will be described.

[0127] 1.2.1 Time synchronization processing

[0128] Figure 15 is a sequence diagram illustrating an example of the time synchronization processing in the communication system of the first embodiment. Figure 15The diagram illustrates the information flow exchanged between shared AP 10 (AP-type MLD), shared AP20-1 (auxiliary AP 1), shared AP 20-2 (auxiliary AP 2), auxiliary STA 1, auxiliary STA 2, and non-AP-type MLD during time synchronization processing when multiple AP connections are established.

[0129] Shared AP 10 sends a beacon frame containing time management information 123 to each shared AP 20-1 and 20-2 (S10).

[0130] Based on the beacon frame regarding time synchronization received in S10, shared AP 20-1 performs synchronization processing with the reference timer (S11). Specifically, shared AP 20-1 compares the timestamp of the reference timer contained in the beacon frame received in S10 with its own TSF timer. If the offset between the timestamp of the reference timer and the TSF timer of shared AP 20-1 is greater than a threshold, shared AP 20-1 overwrites its own TSF timer with the timestamp of the reference timer. If the offset between the timestamp of the reference timer and the TSF timer of shared AP 20-1 is less than the threshold, shared AP 20-1 directly uses its own TSF timer.

[0131] After the synchronization process in S11, the shared AP 20-1 calculates the offset of the shared AP 20-1's TSF timer relative to the reference timer (S12).

[0132] Similarly, based on the beacon frame regarding time synchronization received in the processing of S10, shared AP 20-2 performs synchronization processing with the reference timer (S13). Specifically, shared AP 20-2 compares the timestamp of the reference timer contained in the beacon frame received in the processing of S10 with the shared AP 20-2's TSF timer. If the comparison result shows that the offset between the timestamp of the reference timer and the TSF timer of shared AP 20-2 is above a threshold, shared AP 20-2 overwrites its TSF timer with the reference timer. If the offset between the timestamp of the reference timer and the TSF timer of shared AP 20-2 is less than the threshold, shared AP 20-2 directly uses its own TSF timer.

[0133] After the synchronization process in S13, the shared AP 20-2 calculates the offset of the shared AP 20-2's TSF timer relative to the reference timer (S14).

[0134] After the process of S13 and the process of S14, each of the shared APs 20-1 and 20-2 notifies the calculated offset to the shared AP 10 (S15).

[0135] The shared AP 10 updates the offset stored in the time management information 123 based on the offset notified in the process of S15 (S16). The offset updated in the process of S16 is reflected in the beacon frame on time synchronization transmitted next time from the shared AP 10. In this way, the shared AP 10 periodically notifies the beacon frame on time synchronization and acquires the latest offset information, thereby managing the TSF timers of the affiliated shared APs 20.

[0136] Each of the shared APs 20-1 and 20-2 transmits the beacon frame on time synchronization to the non-AP MLD via the wirelessly connected affiliated STAs (S17).

[0137] The non-AP MLD performs the synchronization process with the reference timer based on the beacon frame on time synchronization received in the process of S17 (S18). Specifically, the non-AP MLD calculates the TSF timers of the shared APs 20-1 and 20-2 based on the timestamps and the offset of the shared APs 20 included in the beacon frame received in the process of S17. Then, the non-AP MLD overwrites the TSF timer of the non-AP MLD with the calculated TSF timers. Further, in a case where the reference timer can be calculated based on the timestamps and the offset of the shared APs 20 included in the beacon frame received in the process of S17, the non-AP MLD can also overwrite the TSF timer of the non-AP MLD with the reference timer.

[0138] The non-AP MLD notifies the TSF timers of the shared APs 20-1 and 20-2 calculated in the process of S18 to the corresponding affiliated STAs, respectively (S19).

[0139] The affiliated STA 1 performs the synchronization process with the TSF timer of the shared AP 20-1 in the wireless connection based on the TSF timer received in the process of S19 (S20). Specifically, the affiliated STA 1 overwrites the TSF timer of the affiliated STA 1 with the TSF timer of the shared AP 20-1.

[0140] Likewise, the affiliated STA 2 performs the synchronization process with the TSF timer of the shared AP 20-2 in the wireless connection based on the TSF timer received in the process of S19 (S21). Specifically, the affiliated STA 2 overwrites the TSF timer of the affiliated STA 2 with the TSF timer of the shared AP 20-2.

[0141] Through the above processes, the time synchronization process ends.

[0142] 1.2.2 R-TWT coordination processing

[0143] Figure 16 is a sequence diagram illustrating an example of R-TWT coordination processing in the communication system of the first embodiment. In Figure 16 , as an example, a series of processes until the communication processing of R-TWT SP (service period) based on the generation of periodic low-delay traffic between the shared AP 10 and the non-AP MLD is shown.

[0144] When it is predicted that low-delay traffic will be generated in the application execution unit 300 (start), the non-AP MLD transmits a bandwidth allocation request for the R-TWT SP to the shared AP 10 (S30).

[0145] When the bandwidth allocation request for the R-TWT SP is received, the shared AP 10 inquires to each shared AP 20-1 and 20-2 about whether or not the R-TWT SP can be set and whether or not the bandwidth for traffic transmission and reception can be allocated (S31).

[0146] Each shared AP 20-1 and 20-2 responds to the inquiry received in the process of S31, and answers the shared AP 10 about the determination result of whether or not the R-TWT SP can be set and whether or not the bandwidth for traffic transmission and reception can be allocated (S32).

[0147] The shared AP 10 decides the shared AP 20 to be set for the R-TWT SP based on the answer received in the process of S32, and transmits it to the non-AP MLD as a response to the bandwidth allocation request received in the process of S30 (S33). In the case where both of the shared APs 20-1 and 20-2 can support, high-reliability bandwidth allocation can be performed by aligned link processing in which communication is performed using multiple wireless links at the same time in the same R-TWT SP.

[0148] When the response to the bandwidth allocation request is received, the non-AP MLD decides the affiliated STAs to be used for low-delay traffic transmission and reception in the R-TWT SP, and notifies each of the affiliated STAs 1 and 2 (S34).

[0149] The shared AP 10 notifies each of the shared APs 20-1 and 20-2 of the information about the start of the R-TWT SP (S35). The information about the start of the R-TWT SP includes, for example, the start time of the R-TWT SP, the period, and the interval length. Here, the start time of the R-TWT SP notified from the shared AP 10 is notified using a reference timer.

[0150] Each of the sharing APs 20-1 and 20-2 transmits a beacon frame including the information on the start of the R-TWT SP received in the process of S35 to the non-AP MLD via the wirelessly connected affiliated STA (S36).

[0151] Here, the start timing of the R-TWT SP notified from each of the sharing APs 20-1 and 20-2 is informed using the TSF timer of the station so as to be synchronized with the start timing of the R-TWT SP notified using the reference timer. That is, when there is an offset between the reference timer and the TSF timer of the station, the start timing of the R-TWT SP of the TSF timer of the station is set to be offset from the start timing of the R-TWT SP of the reference timer by the offset. Specifically, when the reference timer is faster than the TSF timer of the sharing AP 20-1 by X seconds, the sharing AP 20-1 sets a timing that is X seconds later than the start timing of the R-TWT SP of the reference timer as the start timing of the R-TWT SP of the TSF of the sharing AP 20-1.

[0152] Further, when the alignment link process is executed, information indicating that a plurality of wireless links are allocated in the same R-TWT SP is included in the beacon frame transmitted in the process of S36.

[0153] When the R-TWT SP starts, the sharing AP 20 to which the bandwidth is allocated among the sharing APs 20-1 and 20-2 transmits a trigger frame to the corresponding affiliated STA (S37).

[0154] When low-delay traffic is generated in the application execution unit 300, the non-AP MLD outputs data to the corresponding affiliated STA (S38).

[0155] The affiliated STA that receives the data in the process of S38 transmits the data to the corresponding sharing AP 20 based on the information on the bandwidth allocation included in the trigger frame received in the process of S37 (S39).

[0156] The sharing AP 20 that receives the data in the process of S39 forwards the data to the sharing AP 10 (S40).

[0157] Such processes of S37 to S40 are repeatedly executed in a plurality of R-TWT SPs set at intervals of the interval length included in the information on the start of the R-TWT SP.

[0158] Through the above processes, the R-TWT coordination process ends.

[0159] 1.3 Effects of the First Embodiment

[0160] According to the first embodiment, the sharing AP 10 transmits the timestamp on the reference timer to the sharing APs 20-1 and 20-2. Each of the sharing APs 20-1 and 20-2 transmits the offset of the TSF timer of the own station from the reference timer to the sharing AP 10 on the basis of the timestamp on the reference timer. The sharing AP 10 shares the offsets received from the respective sharing APs 20-1 and 20-2 with the sharing APs 20-1 and 20-2. Thereby, the sharing AP 10, the respective sharing APs 20-1 and 20-2 can share the information on the time synchronization.

[0161] In addition, the terminal device 30 receives the beacon frame on the time synchronization from the sharing APs 20-1 and 20-2. Thereby, it is possible to synchronize the TSF timer of the non-AP MLD, the TSF timer of the affiliated STA 1, and the TSF timer of the affiliated STA 2 in the terminal device 30 with the reference timer, the TSF timer of the sharing AP 20-1, and the TSF timer of the sharing AP 20-2, respectively. Therefore, in the coordination processing of the R-TWT SP, it is possible to perform the time synchronization between the wireless links while synchronizing the affiliated STA 1 and the affiliated STA 2 with the sharing APs 20-1 and 20-2 connected wirelessly, respectively.

[0162] In addition, by the alignment link processing, the affiliated STA 1 and the affiliated STA 2 can transmit data in the same R-TWT SP via the wireless links with the sharing APs 20-1 and 20-2, respectively. Thereby, for example, it is possible to perform redundant communication of transmitting the same data with a plurality of wireless links in the same R-TWT SP. Therefore, it is possible to perform data communication with high reliability.

[0163] 2. Second Embodiment

[0164] Next, the second embodiment will be described. In the second embodiment, it differs from the first embodiment in that the TSF timer generated by the oscillator 16 is not directly used as the reference timer. Hereinafter, the structure and operation different from the first embodiment will be mainly described. The structure and operation common to the first embodiment will be omitted as appropriate.

[0165] 2.1 Sharing AP

[0166] Figure 17 is a block diagram showing an example of the functional structure of the sharing AP of the second embodiment. Figure 17 Corresponding to the sharing AP 10 of the first embodiment Figure 5 .

[0167] As shown in Figure 17 , the sharing AP 10A includes a reference timer generation section 100A in place of the reference timer generation section 100.

[0168] The reference timer generation section 100A generates the reference timer based on the TSF timer of each of the shared APs 20-1 and 20-2 in addition to the output of the oscillator 16. The reference timer generation section 100A outputs the generated reference timer to the management section 120.

[0169] Specifically, for example, the reference timer generation section 100A updates the reference timer with an average of the TSF timer generated according to the oscillator 16, the TSF timer of the shared AP 20-1, and the TSF timer of the shared AP 20-2. At the time of updating the reference timer, the TSF timer that deviates by more than a threshold value compared to the reference timer before the update can be excluded from the calculation of the average.

[0170] Further, in the second embodiment, the TSF timer generated by the oscillator 25 included in the shared AP 20 is highly accurate to the extent that it can be used as the reference timer.

[0171] 2.2 Reference timer generation processing

[0172] Figure 18 is a sequence diagram illustrating an example of the reference timer generation processing in the communication system of the second embodiment. Figure 18 The information exchange between the shared AP 10A and the shared APs 20 at the time of generating the reference timer in the shared AP 10A is illustrated in.

[0173] The shared AP 10A periodically requests information on the TSF timer to the shared APs 20-1 and 20-2 (S50).

[0174] In response to the request for the TSF timer, each of the shared APs 20-1 and 20-2 notifies the shared AP 10A of information on the TSF timer of the station (S51).

[0175] The shared AP 10A updates the reference timer based on the TSF timer of each of the shared APs 20-1 and 20-2 received in the processing of S51 and the TSF timer generated by the oscillator 16 (S52).

[0176] Through the above processing, the reference timer generation processing ends.

[0177] 2.3 Effects of the second embodiment

[0178] According to the second embodiment, the reference timer is generated as an average of the TSF timers of the plurality of access points. Thereby, even when accuracy of an arbitrary TSF timer among the TSF timers of the plurality of access points deteriorates, the reference timer can be generated without being affected by the deterioration. Therefore, as compared with a case where the reference timer is generated from a single TSF timer, the reference timer with higher stability can be generated.

[0179] 3. Modified examples and the like

[0180] In addition, various modifications can be applied to the above-described first and second embodiments.

[0181] 3.1 First modified example

[0182] In the above-described first and second embodiments, it is assumed that the oscillators 16 of the shared APs 10 and 10A are capable of generating TSF timers with high accuracy to the extent that can be used as a reference timer, but the present technology is not limited thereto. For example, the oscillators 16 of the shared APs 10 and 10A can also not be required to generate TSF timers with high accuracy to the extent that can be used as a reference timer. In this case, the shared APs 10 and 10A can acquire TSF timers from the outside of the communication system 1.

[0183] Figure 19 is a block diagram showing an example of a functional configuration of the shared AP of the first modified example. Figure 19 Corresponding to the first embodiment Figure 5 .

[0184] As Figure 19 indicated, the shared AP 10B includes a reference timer generation section 100B. The reference timer generation section 100B acquires a TSF timer with accuracy to the extent that can be used as a reference timer from the outside of the communication system 1 via the network 40.

[0185] Specifically, for example, the reference timer generation section 100B can acquire a TSF timer from a time server on the network 40. The time server can be implemented by an NTP (network time protocol) server. In this case, communication between the reference timer generation section 100B and the NTP server can be performed by NTP. In order to achieve higher accuracy of time synchronization, communication between the reference timer generation section 100B and the NTP server can be performed in accordance with the IEEE 802.1AS-2011 standard.

[0186] In addition, for example, the shared AP 10B can have a GPS (global positioning system) receiver. In this case, the reference timer generation section 100B can generate the TSF timer based on time information acquired from the GPS receiver.

[0187] According to the 1st modification, the shared AP 10B can generate the reference timer at the time of synchronizing the various devices within the communication system 1 even without the oscillator 16 capable of generating a high-precision TSF timer.

[0188] In addition, when performing the time synchronization processing in a wider-area communication system using a plurality of multi-AP connections based on a plurality of shared APs, the time synchronization between the plurality of shared APs can be easily performed.

[0189] 3.2 2nd Modification

[0190] In addition, in the above 1st and 2nd embodiments, the case where each of the AP-type MLD and the plurality of affiliated APs is disposed at a mutually separate location is described, but is not limited thereto.

[0191] Figure 20 is a block diagram showing an example of the structure of the communication system of the 2nd modification. Figure 20 Corresponding to the 1st embodiment Figure 1 .

[0192] As Figure 20 indicated, in the communication system 1C, at least one affiliated AP (affiliated AP 1) among the plurality of affiliated APs can be provided within the same housing 5 as the AP-type MLD. In this case, the communication between the AP-type MLD and the affiliated AP 1 can be performed by wire.

[0193] According to the above structure, the shared AP 10 having the AP-type MLD and the shared AP 20-1 having the affiliated AP 1 are provided within the same housing 5. Therefore, the TSF timer of the shared AP 10 and the TSF timer of the shared AP 20-1 can be the same.

[0194] According to the 2nd modification, the time synchronization of the entire communication system 1C can be performed by making the TSF timer of the affiliated AP 1 coincide with the reference timer while synchronizing the TSF of the affiliated AP 2 with the reference timer.

[0195] 3.3 Others

[0196] Further, between the shared AP 10, the shared AP 20, and the terminal device 30, the TSF timer and the offset can also adopt values obtained taking into account the propagation delay of wireless communication and the processing delay within the device.

[0197] In addition, the time synchronization processing, the R-TWT coordination control processing, and the reference timer generation processing in the shared AP 10, the shared AP 20, and the terminal device 30 can also be stored in advance as programs that enable a processor of a computer to execute. Furthermore, the storage medium can be saved in an external storage device such as a magnetic disk, an optical disk, a semiconductor memory, or the like, and distributed. Then, the processor of each of the shared AP 10, the shared AP 20, and the terminal device 30 reads the program stored in the storage medium of the external storage device and controls the operation in accordance with the read program, whereby the time synchronization processing, the R-TWT coordination control processing, and the reference timer generation processing can be executed.

[0198] Furthermore, the present application is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the scope of the gist thereof. In addition, the embodiments can be implemented in combination as appropriate, in which case the effects of the combination can be obtained. Furthermore, various inventions are included in the above-described embodiments, and various inventions can be extracted by combining a plurality of constituent elements disclosed therein in an appropriate manner. For example, in the case where even if a certain constituent element is deleted from all the constituent elements shown in the embodiments, the technical issue can be solved and the effects can be obtained, a structure of the constituent element deleted therefrom can also be extracted as an invention.

Claims

1. An access point, serving as the first access point in a communication system comprising a first access point, a second access point, a third access point, and a terminal device, wherein, The first access point is configured as follows: Send timestamps associated with the first timer corresponding to the first access point to the second access point and the third access point. Receive the first offset between the first timer and the second timer corresponding to the second access point from the second access point. Receive the second offset between the first timer and the third timer corresponding to the third access point from the third access point. The first offset and the second offset are sent to the second access point and the third access point, respectively.

2. The access point according to claim 1, wherein, The first access point is configured to receive data from the terminal device in response to a request from the terminal device, starting from a first moment based on the first timer, during a first time period, via a first wireless link between the second access point and the terminal device and a second wireless link between the third access point and the terminal device, respectively.

3. An access point, serving as the second access point in a communication system comprising a first access point, a second access point, a third access point, and a terminal device, wherein, The second access point is configured as follows: Receive information from the first access point indicating a first time period starting from a first moment based on a first timer corresponding to the first access point. Based on the first timer and the first offset of the second timer corresponding to the second access point, and the information, data is received from the terminal device via the first wireless link between the second access point and the terminal device during a second time period that coincides with the first time period, wherein the second time period is a period that begins from the second moment based on the second timer.

4. A terminal device in a communication system, the communication system comprising a first access point, a second access point, a third access point, and the terminal device, wherein, The terminal device is configured as follows: Receive information related to the second timer corresponding to the second access point and the third timer corresponding to the third access point. Communicating with the second access point via the first wireless link based on the second timer. The third access point is communicated via a second wireless link based on the third timer.

5. The terminal device according to claim 4, wherein, The terminal device is configured as follows: During a second time period starting from a second moment based on the second timer, data is transmitted to the first access point via the first wireless link with the second access point, wherein the second time period coincides with the first time period starting from a first moment based on the first timer corresponding to the first access point. During a third time period starting from a third moment based on the third timer, data is transmitted to the first access point via a second wireless link with the third access point, wherein the third time period is a time period consistent with the first time period.

6. A communication method using an access point, wherein the access point is the first access point in a communication system including a first access point, a second access point, a third access point, and a terminal device, the communication method comprising: Send timestamps associated with the first timer corresponding to the first access point to the second access point and the third access point. Receive the first offset between the first timer and the second timer corresponding to the second access point from the second access point. Receive from the third access point the second offset between the first timer and the third timer corresponding to the third access point, and The first offset and the second offset are sent to the second access point and the third access point, respectively.

7. A communication method using an access point, wherein the access point is a second access point in a communication system including a first access point, a second access point, a third access point, and a terminal device, the communication method comprising: Receive information from the first access point indicating a first time period starting from a first moment based on a first timer corresponding to the first access point. Based on the first timer and the first offset of the second timer corresponding to the second access point, and the information, data is received from the terminal device via the first wireless link between the second access point and the terminal device during a second time period that coincides with the first time period, wherein the second time period is a period that begins from the second moment based on the second timer.

8. A communication method performed by a terminal device, the terminal device being a terminal device in a communication system including a first access point, a second access point, a third access point, and the terminal device itself, the communication method comprising: Receive information related to the second timer corresponding to the second access point and the third timer corresponding to the third access point. Communicating with the second access point via the first wireless link based on the second timer, and The third access point is communicated via a second wireless link based on the third timer.

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