Access point and wireless terminal device

Abstract

A wireless terminal device according to one embodiment of the present invention comprises a wireless communication unit and a connection control unit. The wireless communication unit is configured to transmit and receive a wireless signal. The connection control unit: receives, from an access point via the wireless communication unit, a beacon including operation information indicating whether or not the access point is operating as a primary access point which is a representative of one or more access points to which an arbitrarily-defined wireless terminal device belongs; and transmits, to the access point, an association request for establishing a wireless link in response to the operation information, which is included in the beacon, indicating that the access point is operating as the primary access point.

Description

Access point and wireless terminal device

[0001] The present invention relates to wireless communications.

[0002] The IEEE 802.11be standard, a next-generation wireless local area network (LAN) standard, is currently being developed. IEEE 802.11be is considering a multi-link operation that enables multiple wireless links to be established between an access point (AP) and a wireless terminal device, thereby achieving a high transmission rate.

[0003] In parallel with the formulation of IEEE802.11be, a next-generation wireless LAN standard, IEEE802.11bn, is being discussed. IEEE802.11bn considers a transmission operation in which multiple distributed access points cooperate to transmit data.

[0004] IEEE 802.11be / D6.0, "35.3 Multi-link operation (MLO)", pp.517-614, May 2024.

[0005] An object of the present invention is to provide a technique that can improve efficiency in wireless communication.

[0006] According to one aspect of the present invention, a wireless terminal device includes a wireless communication unit and a connection control unit. The wireless communication unit is configured to transmit and receive wireless signals. The connection control unit receives a beacon from an access point via the wireless communication unit, the beacon including operation information indicating whether the access point is operating as a primary access point that represents one or more access points to which a given wireless terminal device belongs. In response to the operation information included in the beacon indicating that the access point is operating as the primary access point, the connection control unit transmits an association request to the access point to establish a wireless link.

[0007] According to the present invention, a technique is provided that can improve efficiency in wireless communication.

[0008] FIG. 1 is a block diagram showing a communication system according to an embodiment. FIG. 2 is a diagram for explaining connection processing according to an embodiment. FIG. 3 is a block diagram showing the hardware configuration of an access point according to an embodiment. FIG. 4 is a block diagram showing the hardware configuration of a terminal according to an embodiment. FIG. 5 is a block diagram showing the functional configuration of an access point according to an embodiment. FIG. 6 is a diagram for explaining beacon transmission according to an embodiment. FIG. 7 is a block diagram showing the functional configuration of a terminal according to an embodiment. FIG. 8 is a flowchart showing connection processing according to an embodiment. FIG. 9 is a block diagram showing a communication system according to another embodiment. FIG. 10 is a block diagram showing the functional configuration of an access point according to another embodiment. FIG. 11 is a block diagram showing the functional configuration of an access point according to another embodiment. FIG. 12 is a block diagram showing the functional configuration of a terminal according to another embodiment. FIG. 13 is a diagram for explaining beacon transmission according to another embodiment. FIG. 14 is a diagram for explaining connection processing according to another embodiment.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments exemplify devices and methods for embodying the technical ideas of the invention, and are not intended to limit the scope of the invention. The drawings are schematic or conceptual. Hereinafter, components having similar functions or configurations may be assigned the same reference numerals. In order to distinguish between components having similar functions or configurations, a subscript may be added to the reference numeral. The subscript is added after a hyphen "-" is inserted.

[0010] The embodiments relate to a wireless network capable of transmitting data in a coordinated manner among multiple distributed access points (APs), which may be referred to as multi-AP coordination. The access points may also be referred to as base stations.

[0011] In the wireless network according to the embodiment, each terminal can be wirelessly connected to multiple access points simultaneously. In other words, each terminal can simultaneously belong to multiple access points. One of the access points wirelessly connected to the terminal operates as a primary access point (Primary AP; P-AP) for the terminal, and the remaining access points wirelessly connected to the terminal operate as secondary access points (Secondary AP; S-AP). The primary AP is a representative of one or more access points to which each terminal belongs.

[0012] For example, the primary AP may control wireless communication of a terminal in a wireless network. Specifically, an access point operating as a primary AP for a terminal may implement arrangements necessary for multi-AP coordination with respect to the terminal. The arrangements necessary for multi-AP coordination may include, for example, allocation of wireless resources, optimization of parameters of each access point such as transmit power, traffic identifier (TID)-to-link mapping, etc. The primary AP may also implement transmission opportunity (TXOP) sharing, setting of a network allocation vector (NAV), etc.

[0013] For example, the primary AP may periodically transmit (specifically, broadcast) a beacon including information about a plurality of items, and the secondary AP may periodically transmit (specifically, broadcast) a beacon including information about some of the plurality of items. The secondary AP plays a supporting role to the primary AP. The secondary AP may also be called a non-primary AP.

[0014] There is a concern that if an access point operates as a primary AP for some of the terminals that belong to it and as a secondary AP for the rest of the terminals that belong to it, this will not lead to efficient wireless resource allocation and / or frame transmission. By making the access point operate as a primary AP for all the terminals that belong to it, it is possible to improve the efficiency of wireless resource allocation and / or frame transmission.

[0015] In the following, an embodiment will be described using wireless communication based on the IEEE 802.11 standard as an example. The IEEE 802.11 standard defines Layer 1 and Layer 2, a media access control (MAC) sublayer, in the Open Systems Interconnection (OSI) model. In the OSI model, 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, for example, a logical link control (LLC) sublayer and a MAC sublayer. Note that a wireless communication standard other than the IEEE 802.11 standard may be used.

[0016] Fig. 1 schematically illustrates a communication system 40 according to one embodiment. As illustrated in Fig. 1, the communication system 40 includes a plurality of access points 10, one or more terminals 20, and a communication network 30. In the example illustrated in Fig. 1, two access points 10-1 and 10-2 are illustrated as the access points 10, and one terminal 20-1 is illustrated as the terminal 20. The access points 10-1 and 10-2 and the terminal 20-1 are included in a wireless network 45.

[0017] The access points 10 are access points for a wireless LAN. The access points 10 are located in different geographical locations such that their communication areas overlap each other. The access points 10 are configured to wirelessly communicate with terminals 20. The access points 10 are connected to a communication network 30, which may include the Internet. For example, the access points 10 are connected to a gateway (not shown), such as a router, by, for example, a LAN cable, and access the communication network 30 via the gateway.

[0018] The access points 10 are configured to communicate with each other to exchange information necessary for multi-AP coordination. In one example, the access point 10-1 may communicate with the access point 10-2 via the communication network 30. In another example, the access point 10-1 may communicate wirelessly with the access point 10-2.

[0019] The terminal 20 is configured to wirelessly communicate with the access point 10. The terminal 20 is wirelessly connected to one or more access points 10. In the example shown in FIG. 1 , the terminal 20-1 is wirelessly connected to the access points 10-1 and 10-2. Specifically, a wireless link is logically established between the access point 10-1 and the terminal 20-1, and data communication is possible between the access point 10-1 and the terminal 20-1 using the established wireless link. A wireless link is logically established between the access point 10-2 and the terminal 20-1, and data communication is possible between the access point 10-2 and the terminal 20-1 using the established wireless link. The terminal 20 communicates with a computer on the communication network 30 via the access point 10. The terminal 20 is a wireless terminal device having a wireless communication function. Examples of wireless terminal devices include, but are not limited to, a desktop personal computer (PC), a laptop PC, a tablet PC, and a smartphone.

[0020] In the example shown in FIG. 1 , the access point 10-2 operates as a primary AP for the terminal 20-1, and the access point 10-1 operates as a secondary AP for the terminal 20-1. The access point 10-2 functions as a representative of the access points 10-1 and 10-2 and controls wireless communication for the terminal 20-1. For example, the access point 10-2 implements the arrangements necessary for multi-AP coordination, such as wireless resource allocation, for the terminal 20-1, and the terminal 20-1 and the access point 10-1 communicate according to instructions from the access point 10-2. For example, the access point 10-2 performs TID-to-link mapping, which associates a TID with a wireless link. Assume that, through TID-to-link mapping, TID#1 is associated with the wireless link between the access point 10-1 and the terminal 20-1, and TID#2 is associated with the wireless link between the access point 10-2 and the terminal 20-1. In this case, a data frame containing data corresponding to TID#1 is transmitted using the wireless link between access point 10-1 and terminal 20-1, and a data frame containing data corresponding to TID#2 is transmitted using the wireless link between access point 10-2 and terminal 20-1.

[0021] Furthermore, the access point 10-2 announces that it is operating as a primary AP. Specifically, the access point 10-2 periodically broadcasts a beacon including operational information indicating that it is operating as a primary AP. The access point 10-1 announces that it is not operating as a primary AP or that it is operating as a secondary AP. Specifically, the access point 10-1 periodically broadcasts a beacon including operational information indicating that it is not operating as a primary AP or that it is operating as a secondary AP.

[0022] As shown in FIG. 2, assume that terminal 20-2 newly joins wireless network 45. For example, terminal 20-2 moves and arrives within the communication areas of access points 10-1 and 10-2. As a result, terminal 20-2 begins to receive beacons from access points 10-1 and 10-2. Based on the received beacons, terminal 20-2 recognizes the existence of access points 10-1 and 10-2. Based on the operation information included in the beacon received from access point 10-2, terminal 20-2 recognizes that access point 10-2 is operating as a primary AP, and based on the operation information included in the beacon received from access point 10-1, terminal 20-2 recognizes that access point 10-1 is not operating as a primary AP. In this case, terminal 20-2 first performs a connection procedure with access point 10-2. Specifically, terminal 20-2 transmits an association request to access point 10-2 to establish a wireless link between access point 10-2 and terminal 20-2. The association request is a management frame for establishing a wireless link and may include information indicating whether the access point 10-2 is requesting operation as a primary AP or a secondary AP. The association request sent by the terminal 20-2 to the access point 10-2 includes information requesting operation as a primary AP for the terminal 20-2. In response to receiving the association request from the terminal 20-2, the access point 10-2 decides to operate as a primary AP for the terminal 20-2 and sends an association response to the terminal 20-2. This establishes a wireless link between the terminal 20-2 and the access point 10-2, and the access point 10-2 begins operating as a primary AP for the terminal 20-2.

[0023] Next, the terminal 20-2 performs a connection procedure with the access point 10-1. Specifically, the terminal 20-2 transmits an association request to the access point 10-1, including information requesting that the terminal 20-2 operate as a secondary AP. In response to receiving the association request from the terminal 20-2, the access point 10-1 decides to operate as a secondary AP for the terminal 20-2 and transmits an association response to the terminal 20-2. As a result, a wireless link is established between the terminal 20-2 and the access point 10-1, and the access point 10-1 begins to operate as a secondary AP for the terminal 20-2.

[0024] In this embodiment, when a terminal 20 newly joining the wireless network 45 finds an access point 10 nearby that is already operating as a primary AP for other terminals 20, the terminal 20 transmits an association request to that access point 10 requesting that it operate as a primary AP for the terminal 20. Upon receiving the association request from the terminal 20, the access point 10 decides to operate as a primary AP for the terminal 20. In this way, the access point 10 that is already operating as a primary AP for other terminals 20 also operates as a primary AP for the terminal 20 newly joining the wireless network 45. This enables a situation in which the access point 10 operates as a primary AP for all of the terminals 20 that belong to it.

[0025] Fig. 3 shows an example of a hardware configuration of the access point 10. As shown in Fig. 3, the access point 10 includes a central processing unit (CPU) 11 as a processor, a read only memory (ROM) 12, a random access memory (RAM) 13, a wireless communication module 14, and a wired communication module 15.

[0026] The CPU 11 is an integrated circuit capable of executing various programs and controls the overall operation of the access point 10. The ROM 12 is a non-volatile semiconductor memory that stores programs and control data for controlling the access point 10. The RAM 13 is a volatile semiconductor memory that is used as a work area for the CPU 11. At least a portion of the processing described for the access point 10 can be implemented by the CPU 11 executing the programs stored in the ROM 12.

[0027] The wireless communication module 14 is a circuit configured to be able to transmit and receive wireless signals via an antenna, and is used for communication with the terminal 20. In another embodiment described below, the wireless communication module 14 includes multiple wireless communication interfaces that transmit and receive wireless signals on different frequency channels. The wired communication module 15 is a circuit used for transmitting and receiving data, etc., using electrical signals, and is used for communication with the communication network 30.

[0028] It should be noted that the hardware configuration shown in FIG. 3 is an example, and the access point 10 may have a hardware configuration different from that shown in FIG.

[0029] Fig. 4 shows an example of a hardware configuration of the terminal 20. As shown in Fig. 4, the terminal 20 includes a CPU 21 as a processor, a ROM 22, a RAM 23, a wireless communication module 24, a display 25, and a storage 26.

[0030] The CPU 21 is an integrated circuit capable of executing various programs and controls the overall operation of the terminal 20. The ROM 22 is a non-volatile semiconductor memory that stores programs and control data for controlling the terminal 20. The RAM 23 is, for example, a volatile semiconductor memory that is used as a work area for the CPU 21. At least a portion of the processing described for the terminal 20 can be implemented by the CPU 21 executing the programs stored in the ROM 22.

[0031] The wireless communication module 24 is a circuit configured to be able to transmit and receive wireless signals via an antenna, and is used for communication with the access point 10. The wireless communication module 24 has multiple (e.g., two) wireless communication interfaces that transmit and receive wireless signals on different frequency channels.

[0032] The display 25 displays, for example, a graphical user interface (GUI) provided by application software. The storage 26 is a non-volatile storage device, and stores, for example, system software, application software, data, etc. of the terminal 20.

[0033] It should be noted that the hardware configuration shown in FIG. 4 is an example, and the terminal 20 may have a hardware configuration different from that shown in FIG.

[0034] FIG. 5 schematically illustrates an example of the functional configuration of the access point 10. The access point 10 illustrated in FIG. 5 corresponds to, for example, one or both of the access points 10-1 and 10-2 illustrated in FIG. 1. As illustrated in FIG. 5, the access point 10 includes an upper layer processing unit 110, an LLC processing unit 120, a MAC processing unit 130, a wireless communication unit 140, and a management unit 150. The upper layer processing unit 110 and the LLC processing unit 120 may be realized, for example, by a combination of the CPU 11 and a wired communication module 15. The MAC processing unit 130, the wireless communication unit 140, and the management unit 150 may be realized, for example, by the wireless communication module 14 or by a combination of the CPU 11 and the wireless communication module 14.

[0035] Upper layer processing unit 110 communicates with communication network 30. Upper layer processing unit 110 receives data addressed to terminal 20 from communication network 30 and sends the received data to LLC processing unit 120. Furthermore, when upper layer processing unit 110 receives data from LLC processing unit 120, it transmits the received data to communication network 30.

[0036] The LLC processing unit 120 performs LLC layer processing. For example, the LLC processing unit 120 receives data from the upper layer processing unit 110 and generates LLC packets by adding a destination service access point (DSAP) header and a source service access point (SSAP) header to the received data. When the LLC processing unit 120 receives an LLC packet from the MAC processing unit 130, it extracts data from the received LLC packet and sends the extracted data to the upper layer processing unit 110.

[0037] The MAC processing unit 130 performs MAC layer processing. For example, the MAC processing unit 130 receives LLC packets from the LLC processing unit 120, adds a MAC header and the like to the received LLC packets to generate MAC frames (specifically, data frames), and sends the generated MAC frames to the wireless communication unit 140. When the MAC processing unit 130 receives a data frame from the wireless communication unit 140, it extracts LLC packets from the received data frame and sends the extracted LLC packets to the LLC processing unit 120. When the MAC processing unit 130 receives a management frame or control frame from the wireless communication unit 140, it sends the received management frame or control frame to the management unit 150. Examples of management frames include a beacon frame, an association request, an association response, a primary AP request, and a primary AP response.

[0038] The wireless communication unit 140 performs PHY layer processing. The wireless communication unit 140 is configured to transmit and receive wireless signals. For example, the wireless communication unit 140 receives a MAC frame from the MAC processing unit 130, adds a preamble or the like to the received MAC frame to generate a wireless frame, converts the wireless frame into a wireless signal by performing a predetermined modulation process, and emits the wireless signal via an antenna. The predetermined modulation process includes, for example, convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform (IFFT), orthogonal frequency division multiplexing (OFDM) modulation, and frequency conversion. The wireless communication unit 140 also receives a wireless signal from the terminal 20 via the antenna and performs a predetermined demodulation process on the received wireless signal to obtain a wireless frame. The predetermined demodulation process includes, for example, frequency conversion, OFDM demodulation, fast Fourier transform (FFT), subcarrier demodulation, deinterleaving, and Viterbi decoding. Then, the wireless communication unit 140 extracts a MAC frame (specifically, a data frame, a management frame, or a control frame) from the wireless frame, and sends the extracted MAC frame to the MAC processing unit 130 .

[0039] The management unit 150 manages the connection with the terminal 20. In the example shown in FIG.

[0040] The beacon transmitter 151 generates a beacon frame and periodically transmits (specifically, broadcasts) the beacon frame via the wireless communication unit 140. The beacon frame is a type of management frame and includes various information necessary for communication. The beacon frame includes information on multiple items, such as the SSID (service set identifier) ​​set in the access point 10, the transmission rate supported by the access point 10, and a timestamp for synchronization.

[0041] The beacon frame further includes operation information indicating whether or not the access point 10 is operating as a primary AP for any terminal 20. For example, the beacon frame includes a field for storing the operation information. For example, if the access point 10 is operating as a primary AP, the value "1" is stored in the field, and if the access point 10 is not operating as a primary AP, the value "0" is stored in the field. In a situation where multiple terminals 20 belong to the access point 10, if the access point 10 is operating as a primary AP for at least one of the terminals 20, the value "1" is stored in the field, and if the access point 10 is operating as a secondary AP for all of the terminals 20, the value "0" is stored in the field.

[0042] The connection control unit 152 performs a connection procedure. For example, the connection control unit 152 waits for an association request from the terminal 20. The association request is received by the wireless communication unit 140 and input to the connection control unit 152. Specifically, the wireless communication unit 140 receives a wireless signal including the association request via an antenna, converts the wireless signal into a wireless frame, extracts the association request from the wireless frame, and sends the extracted association request to the connection control unit 152 via the MAC processing unit 130. In response to receiving the association request from the terminal 20, the connection control unit 152 transmits an association response to the terminal 20.

[0043] As will be described later, when there is no access point operating as a primary AP in the vicinity, the terminal 20 transmits a primary AP request to search for an access point capable of operating as a primary AP. The connection control unit 152 receives the primary AP request via the wireless communication unit 140. In response to receiving the primary AP request from the terminal 20, the connection control unit 152 determines whether or not to operate as a primary AP for the terminal 20. If the connection control unit 152 determines to operate as a primary AP for the terminal 20, it transmits a primary AP response, which is a response to the primary AP request, to the terminal 20 via the wireless communication unit 140.

[0044] Furthermore, the connection control unit 152 manages information about the currently connected terminals 20. For example, the connection control unit 152 holds management information for each terminal 20, including information indicating whether or not the terminal 20 is operating as a primary AP. For a terminal 20 that is a target for operating as a primary AP, the management information further includes information necessary for multi-AP coordination, such as information about wireless links between the terminal and other access points. The information necessary for multi-AP coordination can be received from the terminal 20 or another access point to which the terminal 20 belongs.

[0045] 6 schematically illustrates an example of beacon transmission according to the embodiment. As illustrated in FIG. 6, an access point 10 operating as a primary AP may transmit a beacon at a first time interval TI1, and an access point 10 operating as a secondary AP may transmit a beacon at a second time interval TI2 that is longer than the first time interval TI1. In other words, the beacon transmission period of the access point 10 operating as a primary AP may be shorter than the beacon transmission period of the access point 10 operating as a secondary AP.

[0046] The access point 10 operating as the primary AP may transmit a beacon equivalent to the beacon transmitted by an access point operating alone, and the access point 10 operating as a secondary AP may transmit a beacon in which some information has been deleted from the beacon transmitted by the access point 10 operating as the primary AP. In other words, the access point 10 operating as the primary AP may transmit a beacon including information about multiple items, and the access point 10 operating as a secondary AP may transmit a beacon including information about some of the multiple items. For example, the beacon transmitted by the access point 10 operating as the primary AP may include information about a first item, information about a second item, and information about a third item, while the beacon transmitted by the access point 10 operating as the secondary AP may include information about the first item and information about the second item, but not information about the third item. Therefore, the frame length FL2 of the beacon transmitted by the access point 10 operating as the secondary AP may be shorter than the frame length FL1 of the beacon transmitted by the access point 10 operating as the primary AP. Here, a beacon transmitted by an access point 10 operating as a primary AP is sometimes called a basic beacon, and a beacon transmitted by an access point 10 operating as a secondary AP is sometimes called a limited beacon.

[0047] The access point 10 may operate as a primary AP for one or more terminals 20 and as a secondary AP for one or more other terminals 20. In this case, the access point 10 may transmit a basic beacon or a limited beacon.

[0048] FIG. 7 schematically illustrates an example of the functional configuration of the terminal 20. The terminal 20 illustrated in FIG. 7 corresponds to either one or both of the terminals 20-1 and 20-2 illustrated in FIGS. 1 and 2. As illustrated in FIG. 7, the terminal 20 includes an upper layer processing unit 210, an LLC processing unit 220, a MAC processing unit 230, multiple wireless communication units 240, and a management unit 250. In the example illustrated in FIG. 7, three wireless communication units 240-1, 240-2, and 240-3 are provided as the wireless communication units 240. The number of wireless communication units 240 may be two or four or more. The upper layer processing unit 210 and the LLC processing unit 220 may be implemented by, for example, the CPU 21. The MAC processing unit 230, the wireless communication unit 240, and the management unit 250 may be implemented by, for example, the wireless communication module 24 or a combination of the CPU 21 and the wireless communication module 24. The wireless communication units 240-1, 240-2, and 240-3 correspond to the three wireless communication interfaces included in the wireless communication module 24.

[0049] Upper layer processing unit 210 executes applications that exchange data with computers on communication network 30 shown in Fig. 1. Upper layer processing unit 210 sends data generated by the applications to LLC processing unit 220.

[0050] The LLC processing unit 220 performs LLC layer processing. For example, the LLC processing unit 220 receives data from the upper layer processing unit 210 and generates LLC packets by adding a DSAP header, an SSAP header, and the like to the received data. When the LLC processing unit 220 receives an LLC packet from the MAC processing unit 230, it extracts data from the received LLC packet and sends the extracted data to the upper layer processing unit 210.

[0051] The MAC processing unit 230 performs MAC layer processing. For example, the MAC processing unit 230 receives LLC packets from the LLC processing unit 220, adds a MAC header and the like to the received LLC packets to generate MAC frames (specifically, data frames), and selectively sends the generated MAC frames to one of the wireless communication units 240. Furthermore, when the MAC processing unit 230 receives a data frame from one of the wireless communication units 240, it extracts an LLC packet from the received data frame and sends the extracted LLC packet to the LLC processing unit 220. When the MAC processing unit 230 receives a management frame or control frame from one of the wireless communication units 240, it sends the received management frame or control frame to the management unit 250.

[0052] The wireless communication units 240 may use different frequency channels. Each wireless communication unit 240 performs PHY layer processing. Each wireless communication unit 240 is configured to transmit and receive wireless signals on its corresponding frequency channel. For example, the wireless communication unit 240 receives a MAC frame from the MAC processing unit 230, generates a wireless frame by adding a preamble or the like to the received MAC frame, converts the wireless frame into a wireless signal by performing a predetermined modulation process, and emits the wireless signal via an antenna. The wireless communication unit 240 also receives a wireless signal from the access point 10 via the antenna, performs a predetermined demodulation process on the received wireless signal, and obtains a wireless frame. The wireless communication unit 240 then extracts the MAC frame from the wireless frame and sends the extracted MAC frame to the MAC processing unit 230.

[0053] The management unit 250 manages the connection with the access point 10. In the example shown in FIG.

[0054] The connection control unit 251 performs a connection procedure. For example, the connection control unit 251 transmits an association request via one of the wireless communication units 240 and receives an association response, which is a response to the association request, via one of the wireless communication units 240. For example, when the wireless communication unit 240-1 receives a beacon from the access point 10, the connection control unit 251 transmits an association request to the access point 10 using the wireless communication unit 240-1. The wireless communication unit 240-1 receives the association request from the connection control unit 251 via the MAC processing unit 230, generates a wireless frame including the received association request, converts the generated wireless frame into a wireless signal, and emits the wireless signal from the antenna. Thereafter, the wireless communication unit 240-1 receives a wireless signal including the association response via the antenna, converts the wireless signal into a wireless frame, extracts the association response from the wireless frame, and sends the extracted association response to the connection control unit 251 via the MAC processing unit 230. In this way, a wireless link is established between the wireless communication unit 240-1 of the terminal 20 and the wireless communication unit 140 of the access point 10.

[0055] When there is no nearby access point operating as a primary AP, the connection control unit 251 transmits a primary AP request to search for an access point capable of operating as a primary AP via at least one of the wireless communication units 240. The connection control unit 251 receives a response to the primary AP request from the terminal 20 via one of the wireless communication units 240. In this case, the connection control unit 251 transmits an association request including information requesting operation as a primary AP to the terminal 20 via the wireless communication unit 240 that received the response.

[0056] Furthermore, the connection control unit 251 manages information related to the currently connected access point 10. For example, the connection control unit 251 holds management information for each wireless communication unit 240, including information indicating the status of the wireless link and information indicating whether the connected access point 10 is a primary AP or a secondary AP.

[0057] 8 is a schematic diagram illustrating an example of a connection process according to an embodiment. The process illustrated in FIG. 8 can be executed by a terminal 20 (specifically, its connection control unit 251) that attempts to join the wireless network 45, such as the terminal 20-2 illustrated in FIG. 2.

[0058] 8, the terminal 20 searches for beacons to find nearby access points 10. When the terminal 20 finds one or more access points 10, the flow proceeds to step S802. Here, it is assumed that the terminal 20 has found multiple access points 10.

[0059] In step S802, the terminal 20 determines whether or not there is an access point 10 operating as a primary AP in the vicinity. The terminal 20 determines whether or not each access point 10 is operating as a primary AP based on the operation information included in the beacon received from each access point 10.

[0060] If the terminal 20 determines that an access point 10 operating as a primary AP is nearby (step S802; Yes), the flow proceeds to step S803. In step S803, the terminal 20 performs a connection procedure with the access point 10 operating as a primary AP. For example, the terminal 20 transmits an association request to the access point 10, including information requesting that the terminal 20 operate as a primary AP. The access point 10 receives the association request from the terminal 20 and determines to operate as a primary AP for the terminal 20. The access point 10 transmits an association response to the terminal 20, including information indicating that the access point 10 operates as a primary AP for the terminal 20. The terminal 20 receives the association response from the access point 10. As a result, a wireless link is established between the terminal 20 and the access point 10, and the access point 10 operates as a primary AP for the terminal 20.

[0061] On the other hand, if the terminal 20 determines that there is no access point 10 operating as a primary AP in the vicinity (step S802; No), the flow proceeds to step S804. In step S804, the terminal 20 transmits a primary AP request to search for an access point that can operate as a primary AP.

[0062] In step S805, the terminal 20 performs a connection procedure with an access point capable of operating as a primary AP. For example, the terminal 20 performs the connection procedure with the access point 10 that has transmitted a primary AP response, which is a response to the primary AP request. If multiple access points 10 transmit primary AP responses, the terminal 20 performs the connection procedure with one of these access points 10. The terminal 20 transmits an association request to the access point 10, including information requesting that the terminal 20 operate as a primary AP. The access point 10 receives the association request from the terminal 20 and determines to operate as a primary AP for the terminal 20. The access point 10 transmits an association response to the terminal 20, including information indicating that the access point 10 operates as a primary AP for the terminal 20. The terminal 20 receives the association response from the access point 10. As a result, a wireless link is established between the terminal 20 and the access point 10, and the access point 10 operates as a primary AP for the terminal 20.

[0063] After the processing of step S803 or step S805 is completed, the flow proceeds to step S806. In step S806, the terminal 20 sequentially performs a connection procedure with the remaining access points 10. For example, the terminal 20 transmits an association request to the access point 10, including information requesting that the terminal 20 operate as a secondary AP. The access point 10 receives the association request from the terminal 20 and determines to operate as a secondary AP for the terminal 20. The access point 10 transmits an association response to the terminal 20, including information indicating that the access point 10 operates as a secondary AP for the terminal 20. The terminal 20 receives the association response from the access point 10. As a result, a wireless link is established between the terminal 20 and the access point 10, and the access point 10 operates as a secondary AP for the terminal 20. Information regarding the wireless link established between the terminal 20 and the access point 10 operating as a secondary AP is notified to the access point 10 operating as a primary AP by either the terminal 20 or the access point 10 operating as a secondary AP.

[0064] In this way, the terminal 20 performs a connection procedure with a plurality of surrounding access points 10 so that one of the surrounding access points 10 operates as a primary AP for the terminal 20, and the remaining access points 10 operate as secondary APs for the terminal 20.

[0065] As described above, in wireless network 45, access point 10 broadcasts a beacon including operation information indicating whether or not it is operating as a primary AP, and terminal 20 determines whether or not each access point 10 is operating as a primary AP based on the operation information included in the beacon received from each access point 10. In response to the operation information included in the beacon indicating that an access point is operating as a primary AP, terminal 20 transmits an association request to that access point including information requesting operation as the primary AP.

[0066] According to the above configuration, the access point 10 that is already operating as a primary AP for other terminals 20 also operates as a primary AP for the terminal 20. This makes it easier for the access point 10 to operate as a primary AP for all of the terminals 20 that belong to it. As a result, the efficiency of wireless communication, for example, the efficiency of wireless resource allocation and frame transmission, is improved.

[0067] In another embodiment, at least one of the access points included in the wireless network may support multi-link operation in addition to multi-AP coordination. A case in which each access point supports multi-link operation will be described with reference to Figures 9 to 14. In Figures 9 to 14, components similar to those shown in Figures 1, 5, and 6 are designated by similar reference numerals, and redundant descriptions will be omitted where appropriate.

[0068] Fig. 9 schematically illustrates a communication system 90 according to another embodiment. As illustrated in Fig. 9, the communication system 90 includes a plurality of access points 10, one or more terminals 20, and a communication network 30. In the example illustrated in Fig. 9, two access points 10-3 and 10-4 are illustrated as the access points 10, and two terminals 20-3 and 20-4 are illustrated as the terminals 20. The access points 10-3 and 10-4 and the terminals 20-3 and 20-4 are included in a wireless network 95.

[0069] 10, the access point 10-3 includes an upper layer processing unit 110, an LLC processing unit 120, a MAC processing unit 130, three wireless communication units 140 (specifically, wireless communication units 140-1, 140-2, and 140-3), and a management unit 150. The frequency channels used by the wireless communication units 140-1, 140-2, and 140-3 of the access point 10-3 are denoted as Ch1, Ch2, and Ch3.

[0070] As shown in FIG. 11 , the access point 10-4 includes an upper layer processing unit 110, an LLC processing unit 120, a MAC processing unit 130, two wireless communication units 140 (specifically, wireless communication units 140-1 and 140-2), and a management unit 150. The frequency channels used by the wireless communication units 140-1 and 140-2 of the access point 10-4 are denoted as Ch4 and Ch5. Frequency channel Ch4 may be different from frequency channels Ch1, Ch2, and Ch3, or may be the same as one of frequency channels Ch1, Ch2, and Ch3. Frequency channel Ch5 may be different from frequency channels Ch1, Ch2, and Ch3, or may be the same as one of frequency channels Ch1, Ch2, and Ch3.

[0071] 12, terminal 20-3 includes upper layer processing unit 210, LLC processing unit 220, MAC processing unit 230, four wireless communication units 240 (specifically, wireless communication units 240-1, 240-2, 240-3, and 240-4), and management unit 250. Terminal 20-4 includes upper layer processing unit 210, LLC processing unit 220, MAC processing unit 230, three wireless communication units 240 (specifically, wireless communication units 240-1, 240-2, and 240-3), and management unit 250, as shown in FIG.

[0072] 9 again, the access point 10-3 operates as a primary AP for the terminals 20-3 and 20-4, and the access point 10-4 operates as a secondary AP for the terminals 20-3 and 20-4. Two wireless links L1 and L2 are established between the access point 10-3 and the terminal 20-3, two wireless links L3 and L4 are established between the access point 10-3 and the terminal 20-4, two wireless links L5 and L6 are established between the access point 10-4 and the terminal 20-3, and one wireless link L7 is established between the access point 10-4 and the terminal 20-4. The wireless link L1 uses frequency channel Ch1, the wireless links L2 and L4 use frequency channel Ch2, the wireless link L3 uses frequency channel Ch3, the wireless links L5 and L7 use frequency channel Ch4, and the wireless link L6 uses frequency channel Ch5.

[0073] For each access point 10, one of the multiple links corresponding to each of the multiple wireless communication units 140 is set as a primary link (P-L), and the remaining links are set as secondary links (S-L). For example, as shown in FIG. 13, for access point 10-3, the link corresponding to wireless communication unit 140-1 is set as a primary link, and the links corresponding to wireless communication units 140-2 and 140-3 are set as secondary links. The secondary links play a supplementary role to the primary link. The link corresponding to wireless communication unit 140-1 of access point 10-3 includes wireless link L1, the links corresponding to wireless communication unit 140-2 of access point 10-3 include wireless links L2 and L4, and the link corresponding to wireless communication unit 140-3 of access point 10-3 includes wireless link L3. For access point 10-4, the link corresponding to wireless communication unit 140-1 is set as a primary link, and the link corresponding to wireless communication unit 140-2 is set as a secondary link. The links corresponding to the wireless communication unit 140-1 of the access point 10-4 include wireless links L5 and L7, and the link corresponding to the wireless communication unit 140-2 of the access point 10-4 includes wireless link L6. The setting of the primary link and the secondary link is performed by a connection control unit 152 included in the management unit 150 of each access point 10.

[0074] The primary link (specifically, the link set as the primary link) may be used for transmitting and receiving management frames and control frames such as beacons, as well as data frames. The secondary link (specifically, the link set as the secondary link) may be used for transmitting and receiving data frames.

[0075] The primary link of the access point 10-4 operating as the primary AP may transmit a basic beacon, and the primary link of the access point 10-3 operating as the secondary AP may transmit a limited beacon. The beacon transmission period on the primary link of the access point 10-4 operating as the primary AP may be shorter than the beacon transmission period on the primary link of the access point 10-3 operating as the secondary AP.

[0076] The access point 10 may operate as a primary AP for one or more terminals 20 and as a secondary AP for one or more other terminals 20. In this case, the access point 10 may transmit a basic beacon on the primary link, or may transmit a limited beacon on the primary link.

[0077] 14, assume that terminal 20-5 newly joins wireless network 95. For example, terminal 20-5 moves and arrives within the communication areas of access points 10-3 and 10-4. As described above, access point 10-3 operates as a primary AP for terminals 20-3 and 20-4, and access point 10-4 operates as a secondary AP for terminals 20-3 and 20-4. Access point 10-3 broadcasts a basic beacon on its primary link, and access point 10-4 broadcasts a limited beacon on its primary link.

[0078] The terminal 20-5 receives beacons from the access points 10-3 and 10-4. Based on the operation information included in the beacon received from the access point 10-3, the terminal 20-5 recognizes that the access point 10-3 is operating as a primary AP, and based on the operation information included in the beacon received from the access point 10-4, the terminal 20-5 recognizes that the access point 10-1 is not operating as a primary AP. In this case, the terminal 20-5 first performs a connection procedure with the access point 10-3 via the primary link. Specifically, the terminal 20-5 transmits an association request to the access point 10-3 to establish a wireless link. The association request includes information requesting the terminal 20-5 to operate as a primary AP. The association request may include capability information indicating whether or not multi-link operation is supported.

[0079] In response to receiving the association request from the terminal 20-5, the access point 10-3 decides to operate as a primary AP for the terminal 20-5 and transmits an association response to the terminal 20-5 via the primary link. As a result, one or more wireless links are established between the terminal 20-5 and the access point 10-3, and the access point 10-3 begins to operate as a primary AP for the terminal 20-5.

[0080] Next, the terminal 20-5 performs a connection procedure with the access point 10-4. Specifically, the terminal 20-5 transmits an association request to the access point 10-4 over the primary link, the association request including information requesting that the terminal 20-5 operate as a secondary AP. In response to receiving the association request from the terminal 20-5, the access point 10-4 decides to operate as a secondary AP for the terminal 20-5, and transmits an association response to the terminal 20-5 over the primary link. As a result, one or more wireless links are established between the terminal 20-5 and the access point 10-4, and the access point 10-4 begins to operate as a secondary AP for the terminal 20-5.

[0081] The embodiments described with reference to Figures 9 to 14 can improve the efficiency of wireless communication, such as the efficiency of radio resource allocation and / or the efficiency of frame transmission, similar to the embodiments described with reference to Figures 1 to 8.

[0082] 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 components from the disclosed components. For example, if the problem can be solved and the effects can be obtained even if some components are removed from all the components shown in the embodiments, the configuration from which these components are removed can be extracted as an invention.

[0083] DESCRIPTION OF SYMBOLS 10...Access point 11...CPU 12...ROM 13...RAM 14...Wireless communication module 15...Wired communication module 20...Terminal 21...CPU 22...ROM 23...RAM 24...Wireless communication module 25...Display 26...Storage 30...Communication network 40...Communication system 45...Wireless network 90...Communication system 95...Wireless network 110...Upper layer processing unit 120...LLC processing unit 130...MAC processing unit 140...Wireless communication unit 150...Management unit 151...Beacon transmission unit 152...Connection control unit 210...Upper layer processing unit 220...LLC processing unit 230...MAC processing unit 240...Wireless communication unit 250...Management unit 251...Connection control unit

Claims

1. A wireless terminal device comprising: a wireless communication unit configured to transmit and receive wireless signals; and a connection control unit that receives a beacon from an access point via the wireless communication unit, the beacon including operational information indicating whether the access point is operating as a primary access point that is a representative of one or more access points to which a given wireless terminal device belongs; and that transmits an association request to the access point to establish a wireless link in response to the operational information included in the beacon indicating that the access point is operating as the primary access point.

2. The wireless terminal device according to claim 1, wherein the association request includes information requesting the wireless terminal device to operate as the primary access point.

3. The wireless terminal device of claim 1, wherein, when there is no access point operating as the primary access point, the connection control unit transmits a primary access point request via the wireless communication unit to search for an access point that can operate as the primary access point, and transmits the association request to an access point that has transmitted a response to the primary access point request.

4. An access point comprising: a wireless communication unit configured to transmit and receive wireless signals; and a connection control unit that transmits, via the wireless communication unit, a beacon containing operation information indicating whether or not the access point is operating as a primary access point that represents one or more access points to which a given wireless terminal device belongs.

5. The access point according to claim 4, wherein the access point is operating as the primary access point for a first wireless terminal device, and the operational information indicates that the access point is operating as the primary access point.

6. The access point according to claim 5, wherein the connection control unit is configured to: receive, via the wireless communication unit, from a second wireless terminal device, an association request for establishing a wireless link, the association request including information requesting the access point to operate as the primary access point for the second wireless terminal device; determine, in response to receiving the association request, to operate as the primary access point for the second wireless terminal device; and transmit, via the wireless communication unit, to the second wireless terminal device, an association response including information indicating that the access point will operate as the primary access point for the second wireless terminal device.

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