Access point and communication method

Abstract

An access point according to one embodiment of the present invention is a first access point in a communication system in which a first terminal device exchanges data by coordinating a first wireless link with the first access point and a second wireless link with a second access point. When changing a first channel to be used in the first wireless link, the first access point is configured to acquire first information on a second channel to be used in the second wireless link, and determine, on the basis of the first information, the presence or absence of a channel differing from the first channel and the second channel as a migration destination channel from the first channel.

Description

Access point and communication method

[0001] The embodiments relate to an access point and a communication method.

[0002] 2. Description of the Related Art A multi-link transmission method using a wireless local area network (LAN) is known as a communication system for wirelessly connecting an access point (AP) and a terminal device (non-AP STA).

[0003] In the multi-link transmission method, data exchange between a multi-link device (AP MLD) in an AP and a multi-link device (non-AP MLD) in a non-AP STA is realized by wireless links between a plurality of affiliated APs in the AP and a plurality of affiliated STAs in the non-AP STA.

[0004] IEEE802.11beTM D6.0, “35.3 Multi-link operation (MLO)”, p517-p614, May 2024

[0005] From the viewpoint of improving the wireless communication environment, it is desirable to establish a transmission method (multi-AP transmission method) that allows one non-AP STA to cooperatively use wireless links with multiple APs.

[0006] In the multi-AP transmission method, interference may occur between the channel used in the wireless link with one AP and the channel used in the wireless link with the other AP. Therefore, if one of multiple APs that have established the multi-AP transmission method with a certain non-AP STA arbitrarily changes the channel, there is a risk of interference occurring with the channel used by the other AP, which is undesirable.

[0007] 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 communication method that improve the wireless communication environment.

[0008] In one aspect, the access point is a first access point in a communication system in which a first terminal device exchanges data by coordinating a first wireless link with the first access point and a second wireless link with a second access point. When changing a first channel used in the first wireless link, the first access point acquires first information regarding a second channel used in the second wireless link, and determines, based on the first information, whether or not there is a channel different from the first channel and the second channel as a transition channel from the first channel.

[0009] According to the embodiment, it is possible to provide an access point and a communication method that improve the wireless communication environment.

[0010] FIG. 1 is a block diagram showing the configuration of a communication system according to an embodiment. FIG. 2 is a block diagram showing an example of the hardware configuration of a sharing AP according to an embodiment. FIG. 3 is a block diagram showing an example of the hardware configuration of a shared AP according to an embodiment. FIG. 4 is a block diagram showing an example of the hardware configuration of a non-AP STA according to an embodiment. FIG. 5 is a block diagram showing an example of the functional configuration of a sharing AP according to an embodiment. FIG. 6 is a diagram showing an example of the data structure of multi-AP management information stored in a sharing AP according to an embodiment. FIG. 7 is a diagram showing an example of the data structure of terminal management information stored in a sharing AP according to an embodiment. FIG. 8 is a block diagram showing an example of the functional configuration of a shared AP according to an embodiment. FIG. 9 is a diagram showing an example of the data structure of link management information stored in a shared AP according to an embodiment. FIG. 10 is a block diagram showing an example of the functional configuration of a non-AP STA according to an embodiment. FIG. 11 is a diagram showing an example of the data structure of link management information stored in a non-AP STA according to an embodiment. FIG. 12 is a flowchart showing an example of a channel change process in a shared AP according to an embodiment. FIG. 13 is a flowchart showing an example of a process for acquiring information on interference channels outside the host AP in a non-AP STA according to an embodiment. FIG. 14 is a diagram showing an example of a channel change process in a shared AP according to an embodiment. FIG. 15 is a flowchart showing an example of a channel change process in a shared AP according to a modified example.

[0011] Hereinafter, embodiments will be described with reference to the drawings. In the following description, components having the same functions and configurations will be given the same reference numerals.

[0012] 1. Embodiment 1.1 Configuration 1.1.1 Communication System FIG. 1 is a block diagram showing an example of the configuration of a communication system according to an embodiment.

[0013] As shown in FIG. 1, the communication system 1 includes a sharing access point (AP) 10, shared access points (APs) 20-1 and 20-2, non-AP STAs 30-1 and 30-2, and a network 40.

[0014] The sharing AP 10, the shared APs 20-1 and 20-2, and the non-AP STAs 30-1 and 30-2 have wireless communication functions based on, for example, 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.

[0015] Specifically, the sharing AP 10 is, for example, an access point of a wireless LAN. The sharing AP 10 includes an AP MLD. The AP MLD is a multi-link device (MLD) within the sharing AP 10, and is an entity configured to logically connect with each of the non-AP STAs 30-1 and 30-2 via wireless communication. In other words, the AP MLD can be the end point on the sharing AP 10 side in data exchange via wireless communication with the non-AP STAs 30-1 and 30-2. The AP MLD is configured to communicate with a server (not shown) on the network 40 via wired or wireless communication. The AP MLD is configured to communicate with each of the shared APs 20-1 and 20-2 via wired or wireless communication.

[0016] Each of the shared APs 20-1 and 20-2 is, for example, a wireless LAN access point. The shared APs 20-1 and 20-2 are different access points and are located at locations physically separated from each other. Therefore, the shared APs 20-1 and 20-2 may have different communication areas. Each of the shared APs 20-1 and 20-2 includes one or more affiliated APs. In the example of FIG. 1 , the shared AP 20-1 includes affiliated AP 1 and affiliated AP 2. The shared AP 20-2 includes affiliated AP 3 and affiliated AP 4.

[0017] Each of affiliated AP1 to affiliated AP4 is an entity configured to establish a physical wireless connection with non-AP STA30-1 or 30-2. That is, each of affiliated AP1 to affiliated AP4 has a physical configuration for exchanging data via a wireless link with non-AP STA30-1 or 30-2.

[0018] The shared APs 20-1 and 20-2 have the same configuration. In the following, when there is no need to distinguish between the shared APs 20-1 and 20-2, they may be referred to as the shared AP 20. Furthermore, when there is no need to distinguish between the affiliated APs 1 to 4, they may be referred to as the affiliated APs.

[0019] Each of the non-AP STAs 30-1 and 30-2 is, for example, a smartphone or a PC (personal computer), and is a terminal device that complies with the IEEE 802.11 standard. Each of the non-AP STAs 30-1 and 30-2 includes a non-AP MLD and one or more affiliated STAs. In the example of FIG. 1, the non-AP STA 30-1 includes a non-AP MLD 1, an affiliated STA 1, and an affiliated STA 2. The non-AP STA 30-2 includes a non-AP MLD 2, an affiliated STA 3, and an affiliated STA 4.

[0020] Non-AP MLD1 and non-AP MLD2 are multilink devices within non-AP STAs 30-1 and 30-2, respectively, and are entities configured to establish a logical wireless connection with the sharing AP 10. In other words, non-AP MLD1 and non-AP MLD2 can be the endpoints of non-AP STAs 30-1 and 30-2, respectively, in data exchange via wireless communication with the sharing AP 10. Non-AP MLD1 is connected via wires to affiliated STA1 and affiliated STA2. Non-AP MLD2 is connected via wires to affiliated STA3 and affiliated STA4.

[0021] Each of Affiliated STA1 to Affiliated STA4 is an entity configured to have a physical wireless connection with the Affiliated AP. That is, each of Affiliated STA1 to Affiliated STA4 has a physical configuration for exchanging data with the Affiliated AP via a wireless link. Each of Affiliated STA1 to Affiliated STA4 may belong to the Affiliated AP. Here, "an Affiliated STA belongs to the Affiliated AP" or "an Affiliated AP is the Affiliated STA's source of origin" means that the wireless link between the Affiliated AP and the Affiliated STA is used in data exchange between the AP MLD and a non-AP STA.

[0022] It should be noted that non-AP STA30-1 and 30-2 have the same configuration. Hereinafter, when there is no need to distinguish between non-AP STA30-1 and 30-2, they may be referred to as non-AP STA30. Furthermore, non-AP MLD1 and non-AP MLD2 have the same configuration. Hereinafter, when there is no need to distinguish between non-AP MLD1 and non-AP MLD2, they may be referred to as non-AP MLD. Furthermore, affiliated STA1 to affiliated STA4 have the same configuration. Hereinafter, when there is no need to distinguish between affiliated STA1 to affiliated STA4, they may be referred to as affiliated STA.

[0023] In this embodiment, the AP MLD and non-AP MLD are configured to exchange data via wireless links between multiple affiliated APs provided in different shared APs 20 and multiple affiliated STAs provided in the same non-AP STA 30. This type of data transmission method is also called a multi-AP transmission method.

[0024] 1 shows a case where the AP MLD and non-AP MLD 1 exchange data by a multi-AP transmission method using the wireless link between affiliated AP 1 and affiliated STA 1, and the wireless link between affiliated AP 3 and affiliated STA 2. Also shown is a case where the AP MLD and non-AP MLD 2 exchange data by a multi-AP transmission method using the wireless link between affiliated AP 2 and affiliated STA 3, and the wireless link between affiliated AP 4 and affiliated STA 4.

[0025] For convenience of explanation, the following description will be given of a case where the sharing AP 10 and the shared AP 20 are wirelessly connected.

[0026] 1.1.2 Hardware Configuration Next, the hardware configuration of the sharing AP, shared AP, and non-AP STA in the communication system according to the embodiment will be described.

[0027] 1.1.2.1 Hardware Configuration of Sharing AP Fig. 2 is a block diagram showing an example of the hardware configuration of a sharing AP according to an embodiment. As shown in Fig. 2, the sharing AP 10 includes, for example, a central processing unit (CPU) 11, a read only memory (ROM) 12, a random access memory (RAM) 13, a wireless communication module 14, and a wired communication module 15.

[0028] The CPU 11 is a processing circuit that controls the overall operation of the sharing AP 10. The ROM 12 is, for example, a non-volatile semiconductor memory. The ROM 12 stores programs and data for controlling the sharing AP 10. The RAM 13 is, for example, a volatile semiconductor memory. The RAM 13 is used as a work area for the CPU 11. The wireless communication module 14 is a circuit used to send and receive data via wireless signals. The wireless communication module 14 is connected to an antenna. The wired communication module 15 is a circuit used to send and receive data via wired signals. The wired communication module 15 is connected to a network 40.

[0029] 3 is a block diagram showing an example of the hardware configuration of a shared AP according to an embodiment. As shown in Fig. 3, the shared AP 20 includes, for example, a CPU 21, a ROM 22, a RAM 23, and a wireless communication module 24.

[0030] The CPU 21 is a processing circuit that controls the overall operation of the shared AP 20. The ROM 22 is, for example, a non-volatile 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 for the CPU 21. The wireless communication module 24 is a circuit used to send and receive data via wireless signals. The wireless communication module 24 is connected to an antenna.

[0031] 1.1.2.3 Hardware Configuration of Non-AP STA Fig. 4 is a block diagram showing an example of the hardware configuration of a non-AP STA according to an embodiment. As shown in Fig. 4, the non-AP STA 30 includes, for example, a CPU 31, a ROM 32, a RAM 33, a wireless communication module 34, a display 35, and a storage 36.

[0032] The CPU 31 is a processing circuit that controls the overall operation of the non-AP STA 30. The ROM 32 is, for example, a non-volatile semiconductor memory. The ROM 32 stores programs and data for controlling the non-AP STA 30. The RAM 33 is, for example, a volatile semiconductor memory. The RAM 33 is used as a work area for the CPU 31. The wireless communication module 34 is a circuit used for sending and receiving data via 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) corresponding to application software, etc. The storage 36 is a non-volatile storage device. The storage 36 stores system software, etc. for the non-AP STA 30.

[0033] 1.1.3 Functional Configuration Next, the functional configuration of the sharing AP, shared AP, and non-AP STA in the communication system according to the embodiment will be described.

[0034] 1.1.3.1 Functional Configuration of Sharing AP FIG. 5 is a block diagram showing an example of the functional configuration of a sharing AP according to this embodiment.

[0035] The sharing AP 10 functions as a computer including a data processing unit 110, a management unit 120, a frame processing unit 130, and radio signal processing units 140 and 150. The data processing unit 110 is a functional block that executes processing corresponding to the LLC sublayer of layer 2 and layers 3 to 7. The management unit 120 and frame processing unit 130 are functional blocks that execute processing corresponding to the MAC sublayer of layer 2. The radio signal processing units 140 and 150 are functional blocks that execute processing corresponding to layer 1. The data processing unit 110, the management unit 120, and the frame processing unit 130 function as an AP MLD.

[0036] The data processing unit 110 outputs data input from the network 40 via the LLC layer to the frame processing unit 130. The data processing unit 110 also outputs data input from the frame processing unit 130 to the network 40 via the LLC layer.

[0037] The management unit 120 controls the logical wireless connection between the AP MLD and the non-AP MLD in the multi-AP transmission method. For example, the management unit 120 executes multi-AP connection processing in response to an association request from the non-AP STA 30. The management unit 120 stores multi-AP management information 121 and terminal management information 122.

[0038] FIG. 6 is a diagram illustrating an example of a data structure of multi-AP management information stored in a sharing AP according to the embodiment.

[0039] 6, information about various AP-side entities (i.e., AP MLD and affiliated APs 1 to 4) used in the multi-AP transmission method is stored in the multi-AP management information 121. The information about various AP-side entities used in the multi-AP transmission method specifically includes, for example, identifiers, channels, capability information, and operation parameters.

[0040] The identifier may include, for example, the MAC address of the corresponding entity.

[0041] A channel includes information indicating one or more frequency bands used by the corresponding entity, such as the 2.4 GHz band, the 5 GHz band, the 6 GHz band, the 45 GHz band, and the 60 GHz band.

[0042] The capability information includes, for example, information indicating whether the corresponding entity supports the multi-AP transmission method.

[0043] The operational parameters include, for example, CWmin, CWmax, arbitration interframe space (AIFS), and transmission opportunity (TXOP) limit. CWmin and CWmax respectively indicate the minimum and maximum values ​​of the contention window. The contention window is a parameter used to calculate backoff, which is a transmission waiting time for collision avoidance. AIFS is a fixed transmission waiting time set for each access category of traffic. Traffic access categories include, for example, "VO (voice)", "VI (video)", "BE (best effort)", "BK (background)", and "LL (low latency)". TXOP limit indicates the upper limit of the channel occupation period TXOP.

[0044] Note that the channels, capability information, and operational parameters related to AP MLD do not necessarily need to be stored.

[0045] FIG. 7 is a diagram illustrating an example of a data structure of terminal management information stored in the sharing AP according to the embodiment.

[0046] 7, information relating to various entities on the non-AP STA side used in the multi-AP transmission method (i.e., non-AP MLD1 and non-AP MLD2, and affiliated STA1 to affiliated STA4) is stored in the terminal management information 122. Specifically, the information relating to various entities on the non-AP STA side used in the multi-AP transmission method includes, for example, an identifier and identification information of the affiliated AP to which the STA belongs.

[0047] The identifier may include, for example, the MAC address of the corresponding entity.

[0048] The identification information of the affiliated AP from which the affiliated STA belongs includes the MAC address of the affiliated AP to which the affiliated STA belongs. In the connection example shown in Figure 1, the "affiliated AP from which the affiliated AP belongs" field for affiliated STA1 stores the MAC address of affiliated AP1. The "affiliated AP from which the affiliated AP belongs" field for affiliated STA2 stores the MAC address of affiliated AP3. The "affiliated AP from which the affiliated AP belongs" field for affiliated STA3 stores the MAC address of affiliated AP2. The "affiliated AP from which the affiliated AP belongs" field for affiliated STA4 stores the MAC address of affiliated AP4.

[0049] Prior to the start of the multi-AP connection, the management unit 120 transmits a MAC frame (beacon frame) including information stored in the multi-AP management information 121 to the shared APs 20-1 and 20-2 using the wireless signal processing units 140 and 150. During the association process, the management unit 120 also transmits an association notification based on the multi-AP management information 121 and the terminal management information 122 to the shared APs 20-1 and 20-2 using the wireless signal processing units 140 and 150.

[0050] Referring again to FIG. 5, the functional configuration of the sharing AP 10 will be described.

[0051] When data is input from data processing unit 110 or management unit 120, frame processing unit 130 generates a MAC frame by adding a MAC header to the input data. Frame processing unit 130 then distributes the MAC frame to either radio signal processing unit 140 or 150. Frame processing unit 130 may determine the distribution destination of the MAC frame according to a traffic identifier (TID) associated with an access category.

[0052] Furthermore, when a MAC frame is input from radio signal processing units 140 and 150, frame processing unit 130 extracts data from the MAC frame and outputs the extracted data to data processing unit 110 or management unit 120 depending on the type of MAC frame. Specifically, when the MAC frame is a data frame, frame processing unit 130 inputs the data to data processing unit 110. When the MAC frame is a management frame or a control frame, frame processing unit 130 inputs the data to management unit 120.

[0053] Each of the radio signal processing units 140 and 150 generates a radio frame by adding a preamble or the like to the MAC frame input from the frame processing unit 130. Each of the radio signal processing units 140 and 150 converts the generated radio frame into a radio signal. Each of the radio signal processing units 140 and 150 then radiates (transmits) the converted radio signal via an antenna. The conversion process from the radio frame to the radio signal includes, for example, convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform, OFDM modulation, and frequency conversion. Each of the radio signal processing units 140 and 150 also converts the radio signal received from the corresponding shared AP 20 via the antenna into a radio frame. The conversion process from the radio signal to the radio frame includes, for example, frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and Viterbi decoding. Each of the radio signal processing units 140 and 150 extracts a MAC frame from the converted radio frame, and then outputs the extracted MAC frame to the frame processing unit 130.

[0054] The wireless signal processing units 140 and 150 are configured to transmit and receive wireless signals using different frequency bands or channels. For example, the wireless signal processing unit 140 is used to transmit wireless signals individually to one wireless signal processing unit of the shared AP 20-1. The wireless signal processing unit 150 is used to transmit wireless signals individually to one wireless signal processing unit of the shared AP 20-2. For example, the wireless signal processing units 140 and 150 may be used to transmit wireless signals containing the same information to multiple shared APs.

[0055] 1.1.3.2 Functional Configuration of Shared AP Fig. 8 is a block diagram showing an example of the functional configuration of a shared AP according to the embodiment. Fig. 8 shows a block diagram of a shared AP 20-1 as an example of the shared AP 20. Although not shown, the functional configuration of the shared AP 20-2 is equivalent to that of the shared AP 20-1.

[0056] The shared AP 20-1 functions as a computer including a management unit 210, a frame processing unit 220, and radio signal processing units 230, 240, and 250. The management unit 210 and the frame processing unit 220 are functional blocks that execute processing corresponding to the MAC sublayer of the second layer. The radio signal processing units 230, 240, and 250 are functional blocks that execute processing corresponding to the first layer. The radio signal processing unit 240 functions as an affiliated AP 1. The radio signal processing unit 250 functions as an affiliated AP 2.

[0057] The management unit 210 manages the state of physical wireless connections with affiliated STAs in the multi-AP transmission method. Specifically, for example, the management unit 210 stores link management information 211.

[0058] FIG. 9 is a diagram illustrating an example of a data structure of link management information stored in a shared AP according to the embodiment.

[0059] 9, information about affiliated APs used in a multi-AP connection within the local AP (i.e., shared AP 20-1) is stored in link management information 211. The information about the affiliated APs within the local AP specifically includes, for example, identification information of the affiliated STAs to which they belong and the channels.

[0060] The identification information of the affiliated STAs includes the MAC addresses of the affiliated STAs that belong to the corresponding affiliated APs. In the example shown in Figure 1, the "affiliated STAs" field for affiliated AP 1 stores the MAC address of affiliated STA 1. The "affiliated STAs" field for affiliated AP 2 stores the MAC address of affiliated STA 3.

[0061] A channel includes information indicating one or more frequency bands that the corresponding affiliated AP uses in the wireless link between the AP and the affiliated STA.

[0062] Referring again to FIG. 8, the functional configuration of the shared AP 20-1 will be described.

[0063] The management unit 210 manages the status of channels used within the local AP. For example, when a channel change is necessary for a certain wireless link due to dynamic frequency selection (DFS) or other reasons, the management unit 210 selects a destination channel. When selecting a destination channel, the management unit 210 collects information (interference channel information) about channels that are inappropriate as destination channels because they cause interference with other wireless links. This collection process includes a process for acquiring interference channel information within the local AP and a process for acquiring interference channel information outside the local AP.

[0064] The process of acquiring interference channel information within the local AP is a process of collecting interference channel information based on channels used within the local AP. In the process of acquiring interference channel information within the local AP, the management unit 210 acquires the interference channel information by referring to link management information 211 within the local AP.

[0065] The process of acquiring information on interference channels outside the local AP is a process of collecting interference channel information based on channels used by non-AP STAs 30, including affiliated STAs belonging to the local AP, in wireless links with shared APs 20 other than the local AP. In the process of acquiring information on interference channels outside the local AP, the management unit 210 queries non-AP STAs 30, including affiliated STAs belonging to the affiliated AP that uses the channel to be changed, for interference channel information.

[0066] The process of acquiring information on interference channels within the local AP and the process of acquiring information on interference channels outside the local AP will be described in detail later.

[0067] When a MAC frame is input from sharing AP 10 via wireless signal processing unit 230, frame processing unit 220 extracts data from the MAC frame and performs processing according to the type of MAC frame. Specifically, if the MAC frame is a data frame, frame processing unit 220 re-adds a MAC header to the data and inputs it to wireless signal processing unit 240 or 250. If the MAC frame is a management frame or control frame, frame processing unit 220 inputs the data to management unit 210. Furthermore, when a MAC frame is input from a wirelessly connected affiliated STA via wireless signal processing unit 240 or 250, frame processing unit 220 re-adds a MAC header to the data extracted from the MAC frame and inputs it to wireless signal processing unit 230.

[0068] The radio signal processing units 230, 240, and 250 generate radio frames by adding a preamble and the like to the MAC frame input from the frame processing unit 220. The radio signal processing units 230, 240, and 250 convert the generated radio frames into radio signals. The radio signal processing unit 230 transmits the converted radio signals to the sharing AP 10 via an antenna. Each of the radio signal processing units 240 and 250 transmits the converted radio signals to a corresponding affiliated STA via an antenna. The conversion process from a radio frame to a radio signal includes, for example, convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform, orthogonal frequency division multiplexing (OFDM) modulation, and frequency conversion. The radio signal processing unit 230 also converts radio signals received from the sharing AP 10 via an antenna into radio frames. Each of the radio signal processing units 240 and 250 converts radio signals received from a corresponding affiliated STA via an antenna into radio frames. The conversion process from radio signals to radio frames includes, for example, frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and Viterbi decoding. The radio signal processing units 230, 240, and 250 extract MAC frames from the converted radio frames. The radio signal processing units 230, 240, and 250 then input the extracted MAC frames to the frame processing unit 220.

[0069] 1.1.3.3 Functional Configuration of Non-AP STA Fig. 10 is a block diagram showing an example of the functional configuration of a non-AP STA according to an embodiment. Fig. 10 shows a block diagram of non-AP STA30-1 as an example of non-AP STA30. Although not shown, the functional configuration of non-AP STA30-2 is equivalent to that of non-AP STA30-1.

[0070] Non-AP STA30-1 functions as a computer including an application execution unit 300, a data processing unit 310, a management unit 320, a frame processing unit 330, and radio signal processing units 340 and 350. The application execution unit 300 is a functional block that executes processing corresponding to layer 7. The data processing unit 310 is a functional block that executes processing corresponding to the LLC sublayer of layer 2 and layers 3 to 6. The management unit 320 and frame processing unit 330 are functional blocks that execute processing corresponding to the MAC sublayer of layer 2. The radio signal processing units 340 and 350 are functional blocks that execute processing corresponding to layer 1. The data processing unit 310, the management unit 320, and the frame processing unit 330 function as a non-AP MLD1. The radio signal processing unit 340 functions as an affiliated STA1. The radio signal processing unit 350 functions as an affiliated STA2.

[0071] The application execution unit 300 executes an application based on data input from the data processing unit 310. The application execution unit 300 also inputs data to the data processing unit 310. For example, the application execution unit 300 can display application information on the display 35. The application execution unit 300 can also operate based on operations on an input interface.

[0072] The data processing unit 310 outputs data input from the application execution unit 300 via the LLC layer to the frame processing unit 330. The data processing unit 310 also outputs data input from the frame processing unit 330 to the application execution unit 300 via the LLC layer.

[0073] The management unit 320 controls the logical wireless connection between the AP MLD and the non-AP MLD 1 in the multi-AP transmission method. For example, the management unit 320 generates an association request based on a beacon frame related to the multi-AP connection. The management unit 320 also stores link management information 321.

[0074] FIG. 11 is a diagram showing an example of the data structure of link management information stored in a non-AP STA according to the embodiment.

[0075] 11, information about affiliated STAs used for multi-AP connection within the local non-AP STA (i.e., non-AP STA 30-1) is stored in link management information 321. The information about affiliated STAs within the local non-AP STA specifically includes, for example, identification information of the affiliated AP to which the STA belongs and the channel.

[0076] The identification information of the affiliated AP to which the corresponding affiliated STA belongs includes the MAC address of the affiliated AP to which the corresponding affiliated STA belongs. In the connection example shown in Figure 1, the "affiliated AP to which the affiliated AP belongs" field for affiliated STA1 stores the MAC address of affiliated AP1. The "affiliated AP to which the affiliated AP belongs" field for affiliated STA2 stores the MAC address of affiliated AP3.

[0077] A channel includes information indicating one or more frequency bands that a corresponding affiliated STA uses in a wireless link between the affiliated AP and the STA.

[0078] Referring again to FIG. 10, the functional configuration of the non-AP STA 30-1 will be described.

[0079] In the process of acquiring information on interference channels outside the local AP, when the management unit 320 receives an inquiry about interference channel information from the shared AP 20, the management unit 320 acquires information on channels used in wireless links with shared APs 20 other than the queried shared AP 20 by referring to link management information 321 in the local non-AP STA 30. The management unit 320 notifies the shared AP 20 that originated the inquiry of the acquisition result.

[0080] When data is input from data processing unit 310, frame processing unit 330 generates a MAC frame by adding a MAC header to the input data. Frame processing unit 330 then distributes the MAC frame to either radio signal processing unit 340 or 350. Frame processing unit 330 may determine the distribution destination of the MAC frame according to the TID.

[0081] Furthermore, when a MAC frame is input from radio signal processing units 340 and 350, frame processing unit 330 extracts data from the MAC frame and outputs the extracted data depending on the type of MAC frame to data processing unit 310 or management unit 320. Specifically, when the MAC frame is a data frame, frame processing unit 330 inputs the data to data processing unit 310. When the MAC frame is a management frame or a control frame, frame processing unit 330 inputs the data to management unit 320.

[0082] The radio signal processors 340 and 350 generate radio frames by adding preambles and the like to the MAC frames input from the frame processor 330. The radio signal processors 340 and 350 convert the generated radio frames into radio signals. The radio signal processors 340 and 350 then transmit the converted radio signals via antennas. The conversion process from radio frames to radio signals includes, for example, convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform, OFDM modulation, and frequency conversion. The radio signal processors 340 and 350 also convert radio signals received from the corresponding affiliated APs via the antennas into radio frames. The conversion process from radio signals to radio frames includes, for example, frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and Viterbi decoding. The radio signal processors 340 and 350 extract MAC frames from the converted radio frames. Then, the radio signal processing units 340 and 350 input the extracted MAC frames to the frame processing unit 330 .

[0083] 1.2 Operation Next, the operation of the communication system according to the embodiment will be described.

[0084] 1.2.1 Channel Change Processing Fig. 12 is a flowchart showing an example of a channel change processing in a shared AP according to an embodiment. The example in Fig. 12 shows the channel change processing executed by a shared AP 20 when a channel change is required for the shared AP 20 due to DFS or some other reason.

[0085] When it is determined that a channel change is necessary (start), the shared AP 20 identifies, in its own station A, an affiliated AP that is using the wireless link where the channel change will occur (S11).

[0086] The shared AP 20 executes an interference channel information acquisition process within the local AP for the affiliated AP identified in the process of S11 (S12). Specifically, the shared AP 20 refers to the link management information 211 to determine whether or not the channels used by the affiliated APs within the local AP include any channels (interference channels) that interfere with the destination channel of the channel to be changed (destination channel). The shared AP 20 then identifies the interference channels within the local AP.

[0087] The shared AP 20 executes a process for acquiring information on interference channels outside the own AP for the affiliated AP identified in the process of S11 (S13). Specifically, the shared AP 20 inquires of the non-AP STAs 30, including the affiliated STAs belonging to the affiliated AP identified in the process of S11, about the presence or absence of interference channels. Based on the response results from the non-AP STAs 30 to the inquiry, the shared AP 20 identifies interference channels outside the own AP. Details of the operation of the non-AP STAs 30 in the process for acquiring information on interference channels outside the own AP will be described later.

[0088] Based on the results of the processes in S12 and S13, the shared AP 20 determines whether or not there is a channel that does not cause interference among the candidates for the destination channel (S14).

[0089] If there is a channel where no interference occurs (S14; yes), the shared AP 20 changes the channel to be changed to the channel determined to be free of interference (S15). In this case, although a channel change occurs, the wireless link is maintained without being interrupted.

[0090] If there is no channel free from interference (S14; no), the shared AP 20 stops the wireless link currently using the channel to be changed (S16).

[0091] After the process of S15 or S16, the channel change process ends (END).

[0092] 1.2.2 Processing for Acquiring Information on Interference Channels Outside the Local AP Figure 13 is a flowchart showing an example of processing for acquiring information on interference channels outside the local AP in a non-AP STA according to an embodiment. The processing of S21 and S22 shown in Figure 13 corresponds to details of the processing of S13 in Figure 12. In the example of Figure 13, it is assumed that the non-AP STA 30 includes multiple affiliated STAs. It is also assumed that the multiple affiliated STAs belong to multiple affiliated APs that are different from each other (i.e., have a multi-AP connection).

[0093] When a non-AP STA30 receives an inquiry from one of its affiliated APs regarding the process of obtaining information on interference channels outside its own AP (start), the non-AP STA30 determines whether there are any affiliated APs to which it belongs other than the affiliated AP that sent the inquiry (S21).

[0094] If there is an affiliated AP to which the non-AP STA 30 belongs in addition to the affiliated AP that sent the query (S21; yes), the non-AP STA 30 refers to the link management information 321 and notifies the affiliated AP that sent the query of information regarding the channels being used in the wireless links with the affiliated AP to which the non-AP STA 30 belongs other than the affiliated AP that sent the query (S22).

[0095] If there is no affiliated AP other than the affiliated AP that sent the inquiry (S21; no), or after the processing of S22, the processing for obtaining information on interference channels outside the local AP ends (END).

[0096] 1.2.3 Specific Example Figure 14 is a diagram showing an example of a channel change process according to an embodiment. In the example of Figure 14, in the communication system 1 shown in Figure 1, channel f1 is used for the wireless link between affiliated AP1 and affiliated STA1. Channel f2 is used for the wireless link between affiliated AP2 and affiliated STA3. Channel f3 is used for the wireless link between affiliated AP3 and affiliated STA2. Channel f4 is used for the wireless link between affiliated AP4 and affiliated STA4. The example of Figure 14 assumes a case where it becomes necessary to change channel f1 for some reason.

[0097] In this case, the shared AP 20-1 refers to the link management information 211 in the process of obtaining interference channel information within the local AP. As a result, the shared AP 20-1 learns that the affiliated AP 2 uses channel f2 for the wireless link with the affiliated STA 3 to which it belongs. Therefore, as a result of the process of obtaining interference channel information within the local AP, the shared AP 20-1 learns that channel f2 is an interference channel and excludes it from candidates for the destination channel.

[0098] Furthermore, in the process of acquiring information on interference channels outside the local AP, shared AP 20-1 inquires of non-AP STA 30-1 about interference channel information. In response to the inquiry, non-AP STA 30-1 notifies shared AP 20-1 of link management information 321. As a result, shared AP 20-1 learns that affiliated STA 2 is using channel f3 for the wireless link with affiliated AP 3 in shared AP 20-2, to which it belongs. Therefore, as a result of the process of acquiring information on interference channels outside the local AP, shared AP 20-1 learns that channel f3 is an interference channel and excludes it from the candidates for the destination channel.

[0099] As a result, if there is a channel other than channels f2 and f3 (e.g., channel f4) as a candidate for the transition channel of channel f1, the shared AP 20-1 selects that channel. Also, if there is no channel other than channels f2 and f3 as a candidate for the transition channel of channel f1, the shared AP 20-1 stops the wireless link between the affiliated AP 1 and the affiliated STA 1.

[0100] 1.3 Effects of the Embodiment According to the embodiment, in the communication system 1, the non-AP STA 30-1 establishes a first wireless link with the affiliated AP 1 in the shared AP 20-1, establishes a second wireless link with the affiliated AP 3 in the shared AP 20-2, and performs a multi-AP connection in which these links cooperate to exchange data. When the shared AP 20-1 changes the channel f1 used in the first wireless link, it acquires information about the channel f3 used in the second wireless link. Based on the acquired information about the channel f3, the shared AP 20-1 determines whether or not there is a channel other than the channels f1 and f3 to use as a destination channel for transitioning from the channel f1. As a result, when the shared AP 20-1 needs to change the channel f1 to another channel, it can avoid interference caused by selecting a channel used in a wireless link outside the local AP as the destination channel.

[0101] Furthermore, if the shared AP 20-1 determines that there is a channel other than channels f1 and f3 as a destination channel, it changes the channel used in the first wireless link from channel f1 to the destination channel. On the other hand, if the shared AP 20-1 determines that there is no channel other than channels f1 and f3 as a destination channel, it stops the first wireless link. As a result, if the multi-AP connection can be maintained, it is possible to maintain the multi-AP connection while avoiding interference. Furthermore, if the multi-AP connection cannot be maintained, it is possible to limit the scope of the impact of the channel change process to within the local AP by stopping the wireless link of the local AP.

[0102] The shared AP 20-1 acquires information about channel f3 from the non-AP STA 30-1, not from the sharing AP 10. This allows the shared AP 20-1 to autonomously determine the channel to switch to, without relying on control from the sharing AP 10.

[0103] 2. Modifications, etc. Various modifications can be applied to the above-described embodiment.

[0104] In the above embodiment, a case has been described in which a wireless link that requires a channel change is stopped when there is no channel free from interference, but the present invention is not limited to this.

[0105] 15 is a flowchart illustrating an example of a channel change process in a shared AP according to a modification, which corresponds to FIG. 12 in the embodiment.

[0106] When it is determined that a channel change is necessary (start), the shared AP 20 identifies, in its own station A, an affiliated AP that is using the wireless link where the channel change will occur (S31).

[0107] The shared AP 20 executes an interference channel information acquisition process within the local AP for the affiliated AP identified in the process of S31 (S32), thereby identifying interference channels within the local AP.

[0108] The shared AP 20 executes an outside-home AP interference channel information acquisition process for the affiliated AP identified in the process of S31 (S33), thereby allowing the shared AP 20 to grasp interference channels outside the home AP.

[0109] Based on the results of the processes in S32 and S33, the shared AP 20 determines whether or not there is a channel that does not cause interference among the candidates for the destination channel (S34).

[0110] If there is a channel where no interference occurs (S34; yes), the shared AP 20 changes the channel to be changed to the channel determined to be free of interference (S35). In this case, although the channel is changed, the wireless link is maintained without being interrupted.

[0111] If there is no channel that does not cause interference (S34; no), the shared AP 20 changes the channel to be changed to one of the channels that is determined to cause interference (S36). In this case, the new channel is used inside or outside the home AP, causing interference. However, the wireless link is maintained without being interrupted.

[0112] The shared AP 20 stops other wireless links that use the destination channel changed in the process of S36 (S37).

[0113] In the case shown in FIG. 14 , the shared AP 20-1 selects, for example, channel f3. In this case, the wireless link between the affiliated AP 1 and the affiliated STA 1 and the wireless link between the affiliated AP 3 and the affiliated STA 2 both use channel f3, causing interference. Therefore, the shared AP 20-1 notifies the shared AP 20-2 that the wireless link between the affiliated AP 3 and the affiliated STA 2 will be terminated. In response to this notification, the shared AP 20-2 terminates the wireless link between the affiliated AP 3 and the affiliated STA 2. Note that if the shared AP 20-1 cannot communicate directly with the shared AP 20-2, this notification may be made, for example, via the sharing AP 10.

[0114] After the process of S35 or the process of S37, the channel change process ends (END).

[0115] According to the modified example, when the shared AP 20-1 determines that there is no channel other than the channels f1 and f3 as a transition channel, the shared AP 20-1 changes the channel used in the first wireless link to, for example, the channel f3 used in the second wireless link, and notifies the shared AP 20-2 of the termination of the second wireless link. This makes it possible to suppress interference without terminating the wireless link of the local AP.

[0116] In the above embodiment, the shared AP 20 acquires information about interference channels from the non-AP STA 30 in the process of acquiring information about interference channels outside the home AP. However, this is not limiting. For example, the shared AP 20 may acquire information about interference channels from the sharing AP 10. This operation also allows the shared AP 20 to identify interference channels outside the home AP.

[0117] In the above embodiment, the sharing AP 10 and the shared AP 20 have different functional configurations, but this is not limiting. For example, the sharing AP 10 may further have a configuration for functioning as the shared AP 20. The shared AP 20 may further have a configuration for functioning as the sharing AP 10.

[0118] The channel change process in the shared AP 20 and the non-AP STA 30 can also be stored as a program that can be executed by a processor, which is a computer. Alternatively, the program can be stored and distributed in a storage medium of an external storage device, such as a magnetic disk, optical disk, or semiconductor memory. The processors of the shared AP 20 and the non-AP STA 30 can then load the program stored in the storage medium of the external storage device and execute the channel change process by having their operations controlled by the loaded program.

[0119] 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.

[0120] 1...Communication system 10...Sharing AP 20...Shared AP 30...Non-AP STA 40...Network 11, 21, 31...CPU 12, 22, 32...ROM 13, 23, 33...RAM 14, 24, 34...Wireless communication module 15...Wired communication module 35...Display 36...Storage 110, 310...Data processing unit 120, 210, 320...Management unit 130, 220, 330...Frame processing unit 140, 150, 230, 240, 250, 340, 350...Wireless signal processing unit 300...Application execution unit 121...Multi-AP management information 122...Terminal management information 211, 321...Link management information

Claims

1. An access point serving as the first access point in a communication system in which a first terminal device exchanges data by coordinating a first wireless link with a first access point and a second wireless link with a second access point, wherein the first access point is configured to: when changing the first channel used in the first wireless link, acquire first information regarding the second channel used in the second wireless link; and determine, based on the first information, whether or not there is a channel different from the first channel and the second channel to transition to from the first channel.

2. The access point according to claim 1, wherein the first access point is configured to change the channel used in the first wireless link from the first channel to the destination channel when it is determined that the destination channel is a channel different from the first channel and the second channel.

3. The access point according to claim 1, wherein the first access point is configured to terminate the first wireless link when it is determined that there is no channel different from the first channel and the second channel as the transition channel.

4. The access point according to claim 1, wherein the first access point is configured to: change the channel used in the first wireless link from the first channel to the second channel when it is determined that there is no channel different from the first channel and the second channel as the transition channel; and notify the second access point of the termination of the second wireless link.

5. The access point according to claim 1, wherein the communication system further includes a second terminal device that exchanges data using a third wireless link with the first access point, and the first access point is configured to: when changing the first channel, further acquire second information regarding a third channel to be used in the third wireless link; and determine, based on the first information and the second information, whether there is a channel different from the first channel, the second channel, and the third channel as a channel to transition from the first channel.

6. The access point according to claim 1, wherein the first access point acquires the first information from the first terminal device.

7. The access point according to claim 1, wherein the communication system further includes a third access point that exchanges data with the first terminal device via the first wireless link and the second wireless link, and the first access point acquires the first information from the third access point.

8. A communication method by an access point as the first access point in a communication system in which a first terminal device exchanges data by coordinating a first wireless link with a first access point and a second wireless link with a second access point, the method comprising: when changing the first channel used in the first wireless link, acquiring first information regarding the second channel used in the second wireless link; and determining, based on the first information, whether there is a channel different from the first channel and the second channel as a channel to transition from the first channel.

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