Access point and control device

Abstract

This access point according to an embodiment comprises a communication circuit and a processor. The communication circuit is configured to transmit and receive wireless signals. The processor is configured to use the communication circuit to establish a multi-link with another access point and a terminal device, respectively, and switch at least one link from the link with the other access point to the link with the terminal device, or from the link with the terminal device to the link with the other access point, on the basis of a first wireless environment on the other access point side and a second wireless environment on the terminal device side.

Description

Access Points and Control Devices

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

[0002] A wireless local area network (LAN) is known as a communication system that wirelessly connects an access point (AP) and a terminal device. By using the wireless LAN, the terminal device can access a network via the access point.

[0003] IEEE 802.11be mentions multi-link transmission, in which multiple links (transmission paths) with different frequency channels are established between a terminal device and an access point. In multi-link transmission, multiple affiliated APs (A-APs) equipped in the same housing, called an access point multi-link device (AP_MLD), and multiple affiliated STAs (A-STAs) equipped in the same housing, called a non-AP_MLD (non-access point multi-link device), form pairs and communicate. The number of A-APs and A-STAs that a wireless device (access point or terminal device) can use corresponds to the number of wireless LAN interfaces installed in the wireless device. The AP_MLD can add and remove devices (links), and can fixedly configure a multi-link with as many affiliated APs as possible.

[0004] EVGENY KHOROV et al., "Current Status and Directions of IEEE 802.11be, the Future Wi-Fi 7", IEEE Access Journal, VOLUME 8, May 21, 2020

[0005] However, IEEE 802.11be does not specify the specific process required for AP_MLD to release a device (link). Furthermore, when a relay station supporting multi-link transmission is used in communication between an access point and a terminal device, the relay station does not specify criteria or switching procedures for determining whether to use its own wireless LAN interface resources for communication on the access point side or for communication on the terminal device side. For example, if an imbalance occurs between the traffic volume on the upstream side and the traffic volume on the downstream side of the relay station, the throughput of the entire communication system may decrease.

[0006] The present invention has been made in light of the above-mentioned circumstances, and its purpose is to provide an access point and a control device that can suppress a decrease in the throughput of the entire communication system when a relay station is used.

[0007] An access point according to an embodiment includes a communication circuit and a processor. The communication circuit is configured to transmit and receive wireless signals. The processor is configured to establish multiple links with other access points and terminal devices using the communication circuit, and to switch at least one link from a link with the other access point to a link with the terminal device or from a link with the terminal device to a link with the other access point based on a first wireless environment of the other access point and a second wireless environment of the terminal device.

[0008] According to the embodiment, it is possible to provide an access point and a control device that can suppress a decrease in the throughput of the entire communication system when a relay station is used.

[0009] FIG. 1 is a block diagram showing an example of the overall configuration of a communication system according to the first embodiment. FIG. 2 is a block diagram showing an example of the hardware configuration of an access point included in the communication system according to the first embodiment. FIG. 3 is a block diagram showing an example of the hardware configuration of a relay station included in the communication system according to the first embodiment. FIG. 4 is a block diagram showing an example of the hardware configuration of a terminal device included in the communication system according to the first embodiment. FIG. 5 is a block diagram showing an example of the functional configuration of an access point included in the communication system according to the first embodiment. FIG. 6 is a block diagram showing an example of the functional configuration of a relay station included in the communication system according to the first embodiment. FIG. 7 is a block diagram showing an example of the functional configuration of a terminal device included in the communication system according to the first embodiment. FIG. 8 is a schematic diagram for explaining the operation of the communication system according to the first embodiment. FIG. 9 is a flowchart showing an example of the operation of a relay station included in the communication system according to the first embodiment. FIG. 10 is a schematic diagram for explaining a first specific example of the operation of the communication system according to the first embodiment. FIG. 11 is a schematic diagram for explaining a second specific example of the operation of the communication system according to the first embodiment. FIG. 12 is a block diagram showing an example of the overall configuration of a communication system according to the second embodiment. FIG. 13 is a block diagram showing an example of the hardware configuration of a control device included in the communication system according to the second embodiment. FIG. 14 is a block diagram showing an example of the functional configuration of a control device included in the communication system according to the second embodiment. Fig. 15 is a flowchart showing an example of the operation of a control device included in a communication system according to the second embodiment. Fig. 16 is a schematic diagram for explaining the operation of the communication system according to the second embodiment. Fig. 17 is a block diagram showing an example of the overall configuration of a communication system according to a third embodiment.

[0010] Each embodiment will be described below with reference to the drawings. Each embodiment illustrates an apparatus or method for embodying the technical concept of the invention. The drawings are schematic or conceptual. Hereinafter, the same reference numerals are used to designate components having substantially the same functions and configurations. A letter or a "hyphen + number" following a reference numeral is used to distinguish between elements having similar configurations and referenced by the same reference numeral. Hereinafter, "access point" will be abbreviated to "AP" as appropriate. In this specification, a wireless LAN access point may also be referred to as a "base station." "Multi-link transmission" may also be referred to as "multi-link." In this specification, "non-AP_MLD" may also be referred to as "STA_MLD." In this specification, "wireless LAN interface" may also be referred to as "wireless communication interface."

[0011] <1> First Embodiment In a communication system 1 according to a first embodiment, a relay station is configured to switch the connection destination of some links constituting a multi-link between an access point and a terminal device based on the upstream wireless environment and the downstream wireless environment. Details of the communication system 1 according to the first embodiment are described below.

[0012] <1-1> Configuration First, the configuration of the communication system 1 according to the first embodiment will be described.

[0013] <1-1-1> Overall configuration of communication system 1 Fig. 1 is a block diagram showing an example of the overall configuration of a communication system 1 according to the first embodiment. As shown in Fig. 1, the communication system 1 according to the first embodiment includes, for example, an access point 10, a relay station 20, and a terminal device 30.

[0014] The access point 10 is a type of access point for a wireless LAN. The access point 10 is connected to a network NW. The access point 10 is configured to be able to communicate with a server (not shown) on the network NW via wired or wireless communication, and to be able to communicate with a terminal device 30 via a relay station 20. The access point 10 can establish a multi-link with the relay station 20. The access point 10 may also be called a "base station."

[0015] The relay station 20 is a type of access point for a wireless LAN. The relay station 20 is configured to be able to wirelessly communicate with both the access point 10 and the terminal device 30. The relay station 20 can establish multiple links with both the access point 10 and the terminal device 30. The relay station 20 may set the number of links used when transferring traffic between the access point 10 and the terminal device 30 symmetrically or asymmetrically on the upstream side (the access point 10 side) and the downstream side (the terminal device 30 side).

[0016] The terminal device 30 is a wireless terminal such as a smartphone or a PC (Personal Computer). The terminal device 30 is configured to be able to communicate with the access point 10 via the relay station 20. The terminal device 30 can establish a multi-link with the relay station 20. The communication system 1 may include a plurality of terminal devices 30. In this case, the plurality of terminal devices 30 are wirelessly connected to the relay station 20 and communicate with the access point 10 via the relay station 20. Furthermore, there may be a plurality of relay stations under the access point 10, or a terminal device 30 may be directly connected to the access point 10.

[0017] The wireless communication used in the communication system 1 complies with, for example, the IEEE 802.11 standard. The IEEE 802.11 standard has wireless communication functions based on the OSI (Open Systems Interconnection) reference model. In the OSI reference model, wireless communication functions are divided into seven layers (Layer 1: Physical Layer, Layer 2: Data Link Layer, Layer 3: Network Layer, Layer 4: Transport Layer, Layer 5: Session Layer, Layer 6: Presentation Layer, and Layer 7: Application Layer). The data link layer includes a Logical Link Control (LLC) sublayer and a Media Access Control (MAC) sublayer. Frequency bands used in the wireless communication of the communication system 1 include, for example, the 2.4 GHz band, the 5 GHz band, the 6 GHz band, the 45 GHz band, and the 60 GHz band. Multiple channels can be assigned to each frequency band.

[0018] <1-1-2> Hardware Configuration of Communication System 1 The hardware configuration of the communication system 1 according to the first embodiment will be described below.

[0019] 2 is a block diagram showing an example of a hardware configuration of the access point 10 included in the communication system 1 according to the first embodiment. As shown in FIG. 2, the access point 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.

[0020] The CPU 11 is a processor capable of executing various programs and controls the overall operation of the access point 10. The ROM 12 is, for example, a non-volatile semiconductor memory and stores programs and control data for controlling the access point 10. The RAM 13 is, for example, a volatile semiconductor memory and is used as a work area for the CPU 11. The wireless communication module 14 is a communication circuit configured to be able to send and receive wireless signals via an antenna. The wireless communication module 14 has multiple wireless LAN interfaces. The wired communication module 15 is a circuit used to send and receive data, etc. via wired signals and is configured to be connectable to the network NW.

[0021] The access point 10 may have other hardware configurations. For example, the access point 10 may be wirelessly connected to the network NW. In this case, the wired communication module 15 may be omitted from the access point 10. The antenna may be built into the access point 10 or may be externally connected.

[0022] 3 is a block diagram showing an example of a hardware configuration of the relay station 20 included in the communication system 1 according to the first embodiment. As shown in FIG. 3, the relay station 20 includes, for example, a CPU 21, a ROM 22, a RAM 23, and a wireless communication module 24.

[0023] The CPU 21 is a processor capable of executing various programs and controls the overall operation of the relay station 20. The ROM 22 is, for example, a non-volatile semiconductor memory and stores programs and control data for controlling the relay station 20. The RAM 23 is, for example, a volatile semiconductor memory and is used as a work area for the CPU 21. The wireless communication module 24 is configured to be able to send and receive wireless signals via an antenna. The wireless communication module 24 is a communication circuit used to send and receive data, etc. with the access point 10 and to send and receive data, etc. with the terminal device 30. The wireless communication module 24 has multiple wireless LAN interfaces.

[0024] It should be noted that the relay station 20 may have other hardware configurations. For example, the antenna may be built into the relay station 20 or may be externally connected.

[0025] 4 is a block diagram showing an example of the hardware configuration of the terminal device 30 included in the communication system 1 according to the first embodiment. As shown in FIG. 4, the terminal device 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.

[0026] The CPU 31 is a processor capable of executing various programs and controls the overall operation of the terminal device 30. The ROM 32 is, for example, a non-volatile semiconductor memory and stores programs and control data for controlling the terminal device 30. The RAM 33 is, for example, a volatile semiconductor memory and is used as a work area for the CPU 31. The wireless communication module 34 is a communication circuit configured to be able to send and receive wireless signals via an antenna. The wireless communication module 34 has multiple wireless LAN interfaces. The display 35 displays, for example, a GUI (Graphical User Interface) of application software. The storage 36 is a non-volatile storage device and stores system software and the like for the terminal device 30.

[0027] <1-1-3> Functional Configuration of Communication System 1 The functional configuration of the communication system 1 according to the first embodiment will be described below.

[0028] (1: Functional Configuration of Access Point 10) Fig. 5 is a block diagram showing an example of the functional configuration of the access point 10 included in the communication system 1 according to the first embodiment. As shown in Fig. 5, the access point 10 includes, for example, an LLC processing unit 110, a data processing unit 120, a management unit 130, a frame processing unit 140, and a transceiver unit 150. The LLC processing unit 110 is a functional block that executes processing corresponding to the LLC sublayer of layer 2 and layers 3 to 7. The data processing unit 120 and the frame processing unit 140 are functional blocks that execute processing corresponding to the MAC sublayer of layer 2. The transceiver unit 150 is a functional block that executes processing corresponding to layer 1.

[0029] The LLC processing unit 110 generates LLC packets by, for example, adding a DSAP (Destination Service Access Point) header or an SSAP (Destination Service Access Point) header to data received from the network NW. The LLC processing unit 110 then inputs the generated LLC packets to the data processing unit 120. The LLC processing unit 110 also extracts data from the LLC packets input from the data processing unit 120. The LLC processing unit 110 then transmits the extracted data to the network NW.

[0030] Data processing unit 120 generates a MAC frame by adding a MAC header to the LLC packet input from LLC processing unit 110. Data processing unit 120 then inputs the generated MAC frame to frame processing unit 140. Data processing unit 120 also extracts LLC packets from the MAC frame input from frame processing unit 140. Data processing unit 120 then inputs the extracted LLC packets to LLC processing unit 110. A MAC frame containing data is also called a "data frame."

[0031] The management unit 130 establishes a wireless connection (wireless link) with the terminal device 30 via the relay station 20, maps data types to links, etc. The management unit 130 also manages management information related to the associated relay station 20 and terminal device 30. The management information may include information related to the link status of each of the associated relay station 20 and terminal device 30, information related to user requirements, etc.

[0032] When a MAC frame is input from the data processing unit 120 or the management unit 130, the frame processing unit 140 outputs the input MAC frame to the transceiver unit 150. When a MAC frame is input from the transceiver unit 150, the frame processing unit 140 outputs the input frame to the data processing unit 120 or the management unit 130 depending on the frame type. For example, when a data frame is input from the transceiver unit 150, the frame processing unit 140 outputs the input frame to the data processing unit 120. When a management frame or control frame is input from the transceiver unit 150, the frame processing unit 140 outputs the input frame to the management unit 130.

[0033] The transceiver 150 transmits and receives data, management information, and the like to and from the relay station 20 belonging to the access point 10. The access point 10 may transmit and receive data, management information, and the like directly to the terminal device 30 without going through the relay station 20. The transceiver 150 is provided with, for example, one wireless signal processing unit for each of the multiple links constituting the multilink with the relay station 20. That is, the transceiver 150 includes multiple wireless signal processing units. Each wireless signal processing unit in the transceiver 150 uses one wireless LAN interface included in the wireless communication module 14 and is associated with one A-AP. Each wireless signal processing unit in the transceiver 150 generates a wireless frame by adding a preamble, etc., to the MAC frame input from the frame processing unit 140, and converts the generated wireless frame into a wireless signal. Then, each wireless signal processing unit in the transceiver 150 transmits (radiates) the converted wireless signal via an antenna to the wirelessly connected relay station 20. Furthermore, each radio signal processing unit of the transceiver unit 150 converts the radio signal received from the relay station 20 via the antenna into a radio frame. Then, each radio signal processing unit of the transceiver unit 150 extracts a MAC frame from the converted radio frame and outputs the extracted MAC frame to the frame processing unit 140.

[0034] (2: Functional Configuration of Relay Station 20) Fig. 6 is a block diagram showing an example of the functional configuration of the relay station 20 included in the communication system 1 according to the first embodiment. As shown in Fig. 6, the relay station 20 includes, for example, transceiver units 210-1 and 210-2, a management unit 220, frame processing units 230-1 and 230-2, and a data processing unit 240. The transceiver units 210-1 and 210-2 are functional blocks that execute processing corresponding to the first layer. The frame processing units 230-1 and 230-2 are functional blocks that execute processing corresponding to the MAC sublayer of the second layer.

[0035] The transceiver 210-1 transmits and receives data, management information, and the like to and from the access point 10 via wireless communication. The transceiver 210-2 transmits and receives data, management information, and the like to and from the terminal device 30 via wireless communication. The transceivers 210-1 and 210-2 are associated with the frame processors 230-1 and 230-2, respectively. The transceiver 210-2 may use multicast or broadcast when sending notifications to the terminal device 30. Each of the transceivers 210-1 and 210-2 uses at least one wireless signal processor (wireless LAN interface). When used, multiple wireless signal processors configured by the wireless communication module 24 are assigned to either the transceiver 210-1 or 210-2. In the relay station 20, the number of wireless signal processors assigned to the transceiver 210-1 and the number of wireless signal processors assigned to the transceiver 210-2 can be changed according to instructions from the management unit 220.

[0036] When configuring STA_MLD, one radio signal processing unit in the transceiver unit 210-1 is associated with one A-STA. The radio signal processing unit of the transceiver unit 210-1 generates a radio frame by adding a preamble or the like to a MAC frame (such as a data frame or a management frame) input from the frame processing unit 230-1. The radio signal processing unit of the transceiver unit 210-1 then converts the generated radio frame into a radio signal and transmits (radiates) the converted radio signal to the access point 10 via the antenna. The radio signal processing unit of the transceiver unit 210-1 also converts a radio signal received from the access point 10 via the antenna into a radio frame. The radio signal processing unit of the transceiver unit 210-1 then extracts a MAC frame from the converted radio frame and outputs the extracted MAC frame to the frame processing unit 230-1.

[0037] When configuring AP_MLD, one radio signal processing unit in the transceiver unit 210-1 is associated with one A-AP. The radio signal processing unit of the transceiver unit 210-2 generates a radio frame by adding a preamble or the like to a MAC frame (such as a data frame or a management frame) input from the frame processing unit 230-2. The radio signal processing unit of the transceiver unit 210-2 then converts the generated radio frame into a radio signal and transmits (radiates) the converted radio signal to the terminal device 30 via the antenna. The radio signal processing unit of the transceiver unit 210-2 also converts a radio signal received from the terminal device 30 via the antenna into a radio frame. The radio signal processing unit of the transceiver unit 210-2 extracts a MAC frame from the converted radio frame and outputs the extracted MAC frame to the frame processing unit 230-2.

[0038] The management unit 220 controls the establishment of a wireless connection (wireless link) between the access point 10 and the terminal device 30 via the relay station 20. The management unit 220 can establish a single link or multiple links with the access point 10 using the transmission / reception unit 210-1. The management unit 220 can establish a single link or multiple links with the terminal device 30 using the transmission / reception unit 210-2. The management unit 220 also manages the status of the wireless link with the access point 10 and the status of the wireless link with the terminal device 30. The management unit 220 can generate and distribute beacons necessary for the wireless connection based on notifications from the access point 10. Furthermore, the management unit 220 has a function for monitoring the amount of traffic on the upstream side and the amount of traffic on the downstream side. The management unit 220 can then switch links based on the amount of traffic on the upstream side and the amount of traffic on the downstream side. Details of this operation will be described later.

[0039] When a MAC frame is input from the data processing unit 240, the frame processing unit 230-1 outputs the input frame to the transceiver unit 210-1. When a MAC frame is input from the transceiver unit 210-1, the frame processing unit 230-1 outputs the input MAC frame to the management unit 220 or the data processing unit 240, depending on the frame type. For example, when a data frame is input from the transceiver unit 210-1, the frame processing unit 230-1 outputs the input frame to the data processing unit 240. When a management frame or control frame intended for the frame processing unit 230-1 is input from the transceiver unit 210-1, the frame processing unit 230-1 outputs the input frame to the management unit 220.

[0040] When a MAC frame is input from the data processing unit 240, the frame processing unit 230-2 outputs the input frame to the transceiver unit 210-2. When a MAC frame is input from the transceiver unit 210-2, the frame processing unit 230-2 outputs the input MAC frame to the management unit 220 or the data processing unit 240, depending on the frame type. For example, when a data frame is input from the transceiver unit 210-2, the frame processing unit 230-2 outputs the input frame to the data processing unit 240. When a management frame or control frame intended for the frame processing unit 230-2 is input from the transceiver unit 210-2, the frame processing unit 230-2 outputs the input frame to the management unit 220.

[0041] Data processing unit 240 outputs the MAC frame input from frame processing unit 230-1 to frame processing unit 230-2, and also outputs the MAC frame input from frame processing unit 230-2 to frame processing unit 230-1.

[0042] (3: Functional Configuration of Terminal Device 30) FIG. 7 is a block diagram showing an example of the functional configuration of the terminal device 30 included in the communication system 1 according to the first embodiment. As shown in FIG. 7 , the terminal device 30 includes, for example, an application execution unit 300, an LLC processing unit 310, a data processing unit 320, a management unit 330, a frame processing unit 340, and a transmission / reception unit 350. The application execution unit 300 is a functional block that executes processing corresponding to layer 7. The LLC processing unit 310 is a functional block that executes processing corresponding to the LLC sublayer of layer 2 and layers 3 to 6. The data processing unit 320 and the frame processing unit 340 are functional blocks that execute processing corresponding to the MAC sublayer of layer 2. The transmission / reception unit 350 is a functional block that executes processing corresponding to layer 1.

[0043] The application execution unit 300 executes an application based on data input from the LLC processing unit 310. The application execution unit 300 also outputs data to the LLC 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.

[0044] The LLC processing unit 310 generates LLC packets by adding DSAP headers, SSAP headers, etc. to data input from the application execution unit 300 (upper layer). The LLC processing unit 310 then outputs the generated LLC packets to the data processing unit 320. The LLC processing unit 310 also extracts data from the LLC packets input from the data processing unit 320. The LLC processing unit 310 then outputs the extracted data to the application execution unit 300 (upper layer).

[0045] The data processing unit 320 generates a MAC frame by adding a MAC header to the LLC packet input from the LLC processing unit 310. The data processing unit 320 then outputs the generated MAC frame to the frame processing unit 340. The data processing unit 320 also extracts an LLC packet from the MAC frame input from the frame processing unit 340. The data processing unit 320 then outputs the extracted LLC packet to the LLC processing unit 310.

[0046] The management unit 330 establishes a wireless connection (wireless link) with the access point 10 via the relay station 20, maps data types to links, sets up BlockAck, etc. The management unit 330 can establish a single link or multiple links with the relay station 20 using the transceiver unit 350. The management unit 330 also manages the status of the wireless link with the access point 10 via the relay station 20. The management unit 330 can acquire management information from, for example, a beacon received from the relay station 20.

[0047] When a MAC frame is input from the data processing unit 320 or the management unit 330, the frame processing unit 340 outputs the input MAC frame to the transceiver unit 350. When a MAC frame is input from the transceiver unit 350, the frame processing unit 340 outputs the input frame to the data processing unit 320 or the management unit 330 depending on the frame type. For example, when a data frame is input from the transceiver unit 150, the frame processing unit 340 outputs the input frame to the data processing unit 320. When a management frame or control frame is input from the transceiver unit 350, the frame processing unit 340 outputs the input frame to the management unit 330.

[0048] The transceiver 350 transmits and receives data, management information, and the like to and from the relay station 20 belonging to the access point 10. The terminal device 30 may transmit and receive data, management information, and the like directly to the access point 10 without going through the relay station 20. The transceiver 350 is provided with, for example, one radio signal processing unit for each of the multiple links constituting the multilink with the relay station 20. That is, the transceiver 350 includes multiple radio signal processing units. One radio signal processing unit in the transceiver 350 utilizes one wireless LAN interface included in the wireless communication module 34 and is associated with one A-STA when configuring an STA_MLD. Each radio signal processing unit in the transceiver 350 generates a radio frame by adding a preamble, etc., to the MAC frame input from the frame processing unit 340, and converts the generated radio frame into a radio signal. Then, each radio signal processing unit in the transceiver 350 transmits (radiates) the converted radio signal via an antenna to the wirelessly connected relay station 20. Furthermore, each radio signal processing unit of the transceiver unit 350 converts the radio signal received from the relay station 20 via the antenna into a radio frame. Then, each radio signal processing unit of the transceiver unit 350 extracts a MAC frame from the converted radio frame and outputs the extracted MAC frame to the frame processing unit 340.

[0049] <1-2> Operation Next, the operation of the communication system 1 according to the first embodiment will be described. The operation of the relay station 20 described below is executed under the control of the management unit 220. Below, a case will be described in which traffic volume is used as information on the wireless environment used to determine link switching.

[0050] 8 is a schematic diagram for explaining the operation of the communication system 1 according to the first embodiment. As shown in FIG. 8, in the following description, it is assumed that the access point 10 has wireless signal processing units WP11 to WP13, the relay station 20 has wireless signal processing units WP21 to WP24, and the terminal device 30 has wireless signal processing units WP31 to WP33. In this example, with the relay station 20 as the reference, traffic communicated between the access point 10 and the relay station 20 corresponds to upstream traffic, and traffic communicated between the relay station 20 and the terminal device 30 corresponds to downstream traffic.

[0051] Each of the radio signal processing units WP11 to WP13 of the access point 10 functions as an A-AP. That is, the radio signal processing units WP11 to WP13 of the access point 10 are used as AP_MLDs. Each of the radio signal processing units WP21 to WP24 of the relay station 20 functions as an A-STA or an A-AP. In this example, each of the radio signal processing units WP21 and WP22 functions as an A-STA, and each of the radio signal processing units WP23 and WP24 functions as an A-AP. That is, the radio signal processing units WP21 and WP22 of the relay station 20 are used as STA_MLDs, and the radio signal processing units WP23 to WP24 of the relay station 20 are used as AP_MLDs. Each of the radio signal processing units WP31 to WP33 of the terminal device 30 functions as an A-STA. That is, the radio signal processing units WP31 and WP33 of the terminal device 30 are used as STA_MLD.

[0052] The wireless signal processors WP11 and WP12 of the access point 10 establish links with the wireless signal processors WP21 and WP22 of the relay station 20, respectively. That is, a multilink of two pairs of A-AP and A-STA is established between the access point 10 and the relay station 20. The wireless signal processors WP23 and WP24 of the relay station 20 establish links with the wireless signal processors WP32 and WP33 of the terminal device 30, respectively. That is, a multilink of two pairs of A-AP and A-STA is established between the relay station 20 and the terminal device 230.

[0053] 9 is a flowchart showing an example of the operation of the relay station 20 included in the communication system 1 according to the first embodiment. When relaying a link between the access point 10 and the terminal device 30, the relay station 20 starts the series of processes shown in FIG. 9 periodically (start).

[0054] First, the relay station 20 monitors the upstream and downstream traffic volumes (step S11). In the process of step S11, the relay station 20 may record, for example, the communication volume with the access point 10 during a predetermined period as the upstream traffic volume, and the communication volume with the terminal device 30 during the predetermined period as the downstream traffic volume.

[0055] Next, the relay station 20 determines whether link switching is necessary (step S12). In the process of step S11, the relay station 20 compares the upstream traffic volume with the downstream traffic volume and determines whether link switching is necessary based on the comparison result. Specifically, the relay station 20 determines that link switching is not necessary when the magnitude of the difference between the upstream traffic volume and the downstream traffic volume is within a predetermined threshold, and determines that link switching is necessary when the magnitude of the difference exceeds the predetermined threshold. Note that, in the comparison between the upstream traffic volume and the downstream traffic volume, the threshold set when one traffic volume is larger than the other traffic volume may be different from the threshold set when the other traffic volume is larger.

[0056] If the relay station 20 determines in the process of step S12 that link switching is not necessary (step S13: NO), the relay station 20 ends the series of processes in FIG. 9 (END).

[0057] If the relay station 20 determines in the process of step S12 that link switching is necessary (step S13: YES), it executes link switching (step S14). For example, if the upstream traffic volume is greater than the downstream traffic volume in the process of step S12, the relay station 20 adds a downstream link in the process of step S14. On the other hand, if the downstream traffic volume is greater than the upstream traffic volume in the process of step S12, the relay station 20 adds an upstream link in the process of step S14. When the link switching is completed, the relay station 20 ends the series of processes in FIG. 9 (END).

[0058] Adding a downstream link corresponds to switching the function of the wireless signal processor WP that has been used as A-STA in the relay station 20 to A-AP. Specifically, the wireless signal processor WP to be switched to is released from its paired link with the A-AP of the access point 10, and a link is established with the A-STA of the terminal device 30. Adding an upstream link corresponds to switching the function of the wireless signal processor WP that has been used as A-AP in the relay station 20 to A-STA. Specifically, the wireless signal processor WP to be switched to is released from its paired link with the A-STA of the terminal device 30, and a link is established with the A-AP of the access point 10.

[0059] The number of links to be switched may be varied depending on the number of links constituting the multi-link and the magnitude of the difference between the upstream traffic volume and the downstream traffic volume. For example, the relay station 20 may be configured to switch one link when the difference between the upstream traffic volume and the downstream traffic volume exceeds a first threshold, and to switch two links when the difference exceeds a second threshold greater than the first threshold. Furthermore, the relay station 20 controls the link switching so that at least one link remains between the access point 10 and the terminal device 30 after the link switching. In other words, even if it is determined that link switching is necessary, the relay station 20 will cancel the link switching if the link switching would result in the loss of either the upstream or downstream link.

[0060] In the process of step S12, the relay station 20 takes into account the traffic that is turned back at the relay station 20. For example, if there is traffic turned back from the terminal device 30 at the relay station 20, no traffic occurs on the upstream side, and only traffic occurs on the downstream side. Therefore, the relay station 20 calculates the above-mentioned traffic volume value by taking the turned-back traffic into account. In addition, in the process of step S12, the relay station 20 also takes into account the case where multiple terminal devices 30 are connected. For example, the relay station 20 performs processing based on the traffic volumes of multiple terminal devices 30 on both the upstream and downstream sides. This allows the upstream traffic volume and the downstream traffic volume to be calculated more accurately.

[0061] 10 is a schematic diagram for explaining a first specific example of the operation of the communication system 1 according to the first embodiment. The first specific example corresponds to an example of a link switching method when, based on the status of the communication system 1 shown in FIG. 8, it is determined in the processing of step S13 that link switching is necessary and the traffic volume on the downstream side is greater than the traffic volume on the upstream side.

[0062] As shown in FIG. 10 , in this example, first, the link between the radio signal processor WP23 functioning as an A-AP in the relay station 20 and the radio signal processor WP23 of the terminal device 30 is released. Then, the radio signal processor WP23 is switched from an A-AP to an A-STA. Then, a link is added between the radio signal processor WP23 of the relay station 20 and the radio signal processor WP13 of the access point 10, and the radio signal processor WP23 functions as part of the STA_MLD of the relay station 20. In this way, in this example, the release of the link changes the multi-link between the relay station 20 and the terminal device 30 to a single link. Then, the addition of the link increases the number of links included in the multi-link between the relay station 20 and the access point 10 from two to three. As a result, the difference between the upstream traffic volume and the downstream traffic volume is reduced compared to before the link switching.

[0063] 11 is a schematic diagram for explaining a second specific example of the operation of the communication system 1 according to the first embodiment. The second specific example corresponds to an example of a link switching method when, based on the status of the communication system 1 shown in FIG. 8, it is determined in the processing of step S13 that link switching is necessary and the traffic volume on the upstream side is greater than the traffic volume on the downstream side.

[0064] As shown in FIG. 11 , in this example, first, the link between the wireless signal processor WP22 functioning as an A-STA in the relay station 20 and the wireless signal processor WP12 of the access point 10 is released. Then, the wireless signal processor WP22 is switched from A-STA to A-AP. Then, a link is added between the wireless signal processor WP22 of the relay station 20 and the wireless signal processor WP31 of the terminal device 30, and the wireless signal processor WP22 functions as part of the AP_MLD of the relay station 20. In this way, in this example, the release of the link changes the multi-link between the relay station 20 and the access point 10 to a single link. Then, the addition of the link increases the number of links included in the multi-link between the relay station 20 and the terminal device 30 from two to three. As a result, the difference between the upstream traffic volume and the downstream traffic volume is reduced compared to before the link switching.

[0065] <1-3> Effects of the First Embodiment Next, effects of the communication system 1 according to the first embodiment will be described.

[0066] In the communication system 1 according to the first embodiment, the amount of traffic that can be communicated between the access point 10 and the relay station 20 (upstream traffic amount) depends on the distance between the access point 10 and the relay station 20, the number of links that make up the multi-link, etc. Also, the amount of traffic that can be communicated between the terminal device 30 and the relay station 20 (downstream traffic amount) depends on the distance between the terminal device 30 and the relay station 20, the number of links that make up the multi-link, the number of terminal devices 30 connected to the relay station 20, etc. Therefore, if a bias occurs between the amount of traffic that can be processed upstream and the amount of traffic that can be processed downstream at the relay station 20, the smaller amount may become a bottleneck in throughput.

[0067] In contrast, in the communication system 1 according to the first embodiment, the relay station 20 switches links based on the results of a comparison between the upstream traffic volume and the downstream traffic volume. For example, the relay station 20 can increase the upstream traffic volume by disconnecting the downstream link and switching to the upstream link. Furthermore, the relay station 20 can increase the downstream traffic volume by disconnecting the upstream link and switching to the downstream link. This allows the relay station 20 to reduce the difference between the traffic volume that can be handled on the upstream side and the traffic volume that can be handled on the downstream side. Therefore, in the communication system 1 according to the first embodiment, the relay station 20 enables the upstream and downstream sides to have equal throughput, thereby preventing a decrease in the throughput of the entire communication system 1.

[0068] <2> Second Embodiment In a communication system 1A according to the second embodiment, a control device on the network NW is configured to determine switching of the upstream and downstream links at the relay station 20 described in the first embodiment. Details of the communication system 1A according to the second embodiment will be described below, focusing on differences from the first embodiment.

[0069] <2-1> Configuration First, the configuration of a communication system 1A according to the second embodiment will be described.

[0070] <2-1-1> Overall Configuration of Communication System 1A Fig. 12 is a block diagram showing an example of the overall configuration of a communication system 1A according to the second embodiment. As shown in Fig. 12, the communication system 1A according to the second embodiment includes, for example, an access point 10, a relay station 20, a terminal device 30, and a control device 40. The configurations of the access point 10, the relay station 20, and the terminal device 30 in the second embodiment are similar to those in the first embodiment, for example.

[0071] The control device 40 is an information processing device such as a server. The control device 40 is connected to a network NW. The control device 40 is configured to be able to communicate with the access point 10 via the network NW. The control device 40 is further configured to determine whether link switching is necessary at the relay station 20 based on the upstream and downstream traffic volumes at the relay station 20 connected to the access point 10, and to transmit an instruction regarding link switching at the relay station 20 to the access point 10. The control device 40 may also be called a "server."

[0072] In addition, in the communication system 1A of the second embodiment, the number of access points 10 connected to the control device 40, the number of relay stations 20 under the access points 10, and the number of terminal devices 30 under the relay stations 20 may each be multiple.

[0073] <2-1-2> Hardware configuration of the control device 40 Fig. 13 is a block diagram showing an example of the hardware configuration of the control device 40 included in the communication system 1A according to the second embodiment. As shown in Fig. 13, the control device 40 includes, for example, a CPU 41, a ROM 42, a RAM 43, a wired communication module 44, a display 45, and a storage 46.

[0074] The CPU 41 is a processor capable of executing various programs and controls the overall operation of the terminal device 30. The ROM 42 is, for example, a non-volatile semiconductor memory and stores programs and control data for controlling the terminal device 30. The RAM 33 is, for example, a volatile semiconductor memory and is used as a work area for the CPU 31. The wireless communication module 34 is a communication circuit configured to be able to send and receive wireless signals via an antenna. The display 35 displays, for example, a GUI (Graphical User Interface) of application software. The storage 36 is a non-volatile storage device and stores system software and the like for the terminal device 30.

[0075] The control device 40 may have other hardware configurations. For example, if the control device 40 is an IoT (Internet of Things) terminal or the like, the display 45 may be omitted from the control device 40. The control device 40 may be wirelessly connected to the network NW. In this case, the wired communication module 44 is replaced with a wireless communication module.

[0076] <2-1-3> Functional configuration of the control device 40 Fig. 14 is a block diagram showing an example of the functional configuration of the control device 40 included in the communication system 1A according to the second embodiment. As shown in Fig. 14, the control device 40 includes, for example, a transmitting / receiving unit 410, a frame processing unit 420, and a link management unit 430.

[0077] The transmitting / receiving unit 410 is configured to be able to transmit and receive data, control instructions, etc. to and from the access point 10 via the network NW. The transmitting / receiving unit 410 transmits data, etc. input from the frame processing unit 420 to the access point 10 via the network NW. The transmitting / receiving unit 410 also extracts frames from signals received via the network NW and inputs them to the frame processing unit 420.

[0078] The frame processing unit 420 extracts data and the like from the frame input from the transmitting / receiving unit 410 and inputs the extracted data to the link management unit 430. The frame processing unit 420 also inputs control instructions and the like input from the link management unit 430 to the transmitting / receiving unit 410.

[0079] The link management unit 430 inputs and outputs data and the like to and from the frame processing unit 420, and manages the status of links in the communication system 1A. The link management unit 430 can generate, for example, an instruction to transfer information regarding upstream and downstream traffic volume to the access point 10 or the relay station 20. The link management unit 430 can also determine link switching at the relay station 20 based on the information regarding upstream and downstream traffic volume collected from the access point 10 or the relay station 20. The link management unit 430 can then generate an instruction regarding link switching to the access point 10 or the relay station 20.

[0080] <2-2> Operation Next, a description will be given of the operation of the communication system 1A according to the second embodiment. The operation of the control device 40 described below is executed based on the control of the link management unit 430.

[0081] Fig. 15 is a flowchart showing an example of the operation of the control device 40 included in the communication system according to the second embodiment. When a link is established between the access point 10 and the terminal device 30 via the relay station 20, the control device 40 starts (starts) the series of processes shown in Fig. 15, for example, periodically.

[0082] First, the control device 40 collects information on upstream and downstream traffic volumes (step S21). In the process of step S21, the relay station 20 may transmit the information on upstream and downstream traffic volumes to the control device 40 based on an instruction received from the control device 40 via the access point 10. Furthermore, the relay station 20 may periodically transmit, for example, the upstream traffic volume for a predetermined period and the downstream traffic volume for the same predetermined period to the control device 40. Furthermore, the control device 40 may obtain the information on upstream traffic volume from the access point 10.

[0083] Next, the control device 40 determines whether or not link switching is necessary (step S22). In the process of step S21, the control device 40 determines whether or not link switching is necessary based on the result of comparing the upstream traffic volume with the downstream traffic volume, similar to the process of step S12 in the first embodiment.

[0084] If the control device 40 determines in the process of step S22 that link switching is not necessary (step S23: NO), it ends the series of processes in FIG. 15 (END).

[0085] If the control device 40 determines in step S22 that link switching is necessary (step S23: YES), it instructs the relay station 20 to switch the link (step S24). For example, if the upstream traffic volume is greater than the downstream traffic volume in step S22, the control device 40 instructs the relay station 20 via the access point 10 to add a downstream link in step S24. On the other hand, if the downstream traffic volume is greater than the upstream traffic volume in step S12, the relay station 20 instructs the relay station 20 via the access point 10 to add an upstream link in step S14. The control device 40 may also transmit a link switching instruction to the access point 10. In this case, the access point 10 is configured to transmit an instruction based on the instruction to the relay station 20. When the link switching is completed, the relay station 20 ends the series of processes shown in FIG. 15 (END).

[0086] FIG. 16 is a schematic diagram illustrating the operation of a communication system 1A according to the second embodiment. The configuration of the communication system 1A illustrated in FIG. 16 corresponds to the configuration of the communication system 1 illustrated in FIG. 8 with a control device 40 added. As illustrated in FIG. 16 , in step S21, the control device 40 collects information on upstream traffic volume and downstream traffic volume from the access point 10 and the relay station 20. If the control device 40 determines that link switching is necessary based on the collected information, it instructs the relay station 20 to switch the link in step S24. As a result, the relay station 20 switches the link as illustrated in FIG. 10 when the downstream traffic volume is greater than the upstream traffic volume, and switches the link as illustrated in FIG. 11 when the upstream traffic volume is greater than the downstream traffic volume.

[0087] <2-3> Effects of the Second Embodiment As described above, in the communication system 1A according to the second embodiment, the control device 40 instructs the relay station 20 to switch links based on the results of a comparison between the upstream traffic volume and the downstream traffic volume. This allows the relay station 20 to reduce the difference between the traffic volume that can be handled on the upstream side and the traffic volume that can be handled on the downstream side, similar to the first embodiment. Therefore, in the communication system 1A according to the second embodiment, the control device 40, like the first embodiment, enables equivalent throughput on the upstream side and the downstream side, and can suppress a decrease in the throughput of the entire communication system 1A.

[0088] <3> Third Embodiment In a communication system 1B according to a third embodiment, an access point 10 and a terminal device 30 are connected via a plurality of relay stations 20, and link switching is performed in the same manner as in the second embodiment. Details of the communication system 1B according to the third embodiment will be described below, focusing on differences from the second embodiment.

[0089] <3-1> Configuration Fig. 17 is a block diagram showing an example of the overall configuration of a communication system 1B according to the third embodiment. As shown in Fig. 17, the communication system 1B according to the third embodiment includes, for example, an access point 10, multiple relay stations 20-1 and 20-2, a terminal device 30, and a control device 40. The access point 10, the relay stations 20-1 and 20-2, and the terminal device 30 in the third embodiment each have a configuration similar to, for example, the second embodiment.

[0090] In the communication system 1B according to the third embodiment, each of the access point 10, the multiple relay stations 20-1 and 20-2, the terminal device 30, and the control device 40 further supports a multi-AP function. In one form of the multi-AP function, multiple relay stations 20 connected to the access point 10 cooperate to perform data communication between the access point 10 and the terminal device 30. As an example of the cooperative operation between the multiple relay stations 20, offloading, in which data (traffic) exchanged between the access point 10 and the terminal device 30 is distributed to the multiple relay stations 20, can be considered.

[0091] The access point 10 establishes a multi-AP connection with a terminal device 30 (non-AP_MLD). In the multi-AP connection, for example, A-STA1 of the terminal device 30 is connected to the access point 10 via a relay station 20-1, and A-STA2 of the terminal device 30 is connected to the access point 10 via a relay station 20-2. The link between the terminal device 30 and each relay station 20 may be a multi-link. Similarly, the link between the access point 10 and each relay station may be a multi-link. Each A-STA can switch its connection to another relay station 20 as the terminal device 30 moves.

[0092] In communication system 1B, when a multi-AP connection is established, information on a plurality of relay stations 20 under the access point 10 and information on a plurality of A-STAs under the terminal device 30 are mutually exchanged between access point 10 and terminal device 30. This allows communication system 1B to collectively establish a comprehensive connection between access point 10 and terminal device 30 targeting a plurality of relay stations 20 and a plurality of A-STAs.

[0093] <3-2> Operation In the communication system 1B according to the third embodiment, each relay station 20 can execute a process related to link switching based on the amount of traffic upstream and downstream, similar to the first embodiment. As a result, in the communication system 1B, link switching in the communication path via the relay station 20-1 and link switching in the communication path via the relay station 20-2 between the access point 10 and the terminal device 30 can be executed similar to the first embodiment.

[0094] In the communication system 1B according to the third embodiment, the control device 40 may be configured to be able to execute processing related to link switching based on the upstream and downstream traffic volumes for each relay station 20, as in the second embodiment. That is, the control device 40 collects information about the upstream and downstream traffic volumes for each relay station 20-1 and 20-2, and determines whether link switching is necessary for each relay station 20. The control device 40 then transmits a link switching instruction to the relay station 20 for which it has determined that link switching is necessary. In this way, the control device 40 can execute link switching for each relay station 20, as in the second embodiment.

[0095] <3-3> Advantages of the Third Embodiment As described above, the communication system 1B according to the third embodiment switches links based on the upstream and downstream traffic volumes for each relay station 20. As a result, the communication system 1B according to the third embodiment enables equivalent throughput on the upstream and downstream sides for each relay station 20, and can suppress a decrease in the throughput of the entire communication system 1B.

[0096] <4> Others In the above embodiment, a case has been described in which traffic volume is used as information on the upstream and downstream wireless environments, but this is not limiting. Information on the upstream and downstream wireless environments may also be information on the location of each wireless device included in the communication system 1 (distance between devices) or information on signal strength. The relay station 20 and the control device 40 can achieve the above-mentioned effects by comparing the upstream wireless environment with the downstream wireless environment and switching links to eliminate imbalances in traffic volume.

[0097] In the second and third embodiments, the control device 40 performs the process related to link switching on the upstream and downstream sides of the relay station 20. However, this is not limiting. The process related to link switching may be performed by the access point 10. In this case, the management unit 130 of the access point 10 may generate an instruction to the relay station 20 to switch the upstream and downstream links based on information collected from the relay station 20. Specifically, the access point 10 collects information on upstream and downstream traffic volumes from the relay station 20 under its control and determines whether link switching is necessary. The access point 10 then instructs the relay station 20 to switch the links based on the comparison of the upstream and downstream traffic volumes. The access point 10 can also perform the process related to link switching on the upstream and downstream sides of each relay station 20 when using the multi-AP function. Even in such a case, the access point 10 can achieve equivalent throughput on the upstream and downstream sides and suppress a decrease in the throughput of the entire communication system 1A or 1B, as in the first embodiment.

[0098] The conversion process from radio frames to radio signals described in the above embodiments includes, for example, convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform, OFDM modulation, and frequency conversion. The conversion process from radio signals to radio frames described in the above embodiments includes, for example, frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and Viterbi decoding. A wireless communication standard other than the IEEE 802.11 standard may be used as the wireless communication standard.

[0099] In the above embodiments, the CPU 11 of the access point 10, the CPU 21 of the relay station, the CPU 21 of the terminal device 30, and the CPU 41 of the control device 40 may each be other circuits. For example, instead of a CPU, an MPU (Micro Processing Unit) or the like may be provided. Each of the processes described in each embodiment may be realized by dedicated hardware. Each of the processes described in the above embodiments may be a mixture of processes executed by software and processes executed by hardware, or may be only one of them.

[0100] 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.

[0101] DESCRIPTION OF SYMBOLS 1, 1A, 1B...Communication system 10...Access point 20, 20-1, 20-2...Relay station 30...Terminal device 40...Control device 11, 21, 31, 41...CPU 12, 22, 32, 42...ROM 13, 23, 33, 43...RAM 14, 24, 34...Wireless communication module 15, 44...Wired communication module 35, 45...Display 36, 46...Storage 110, 310...LLC processing unit 120, 240, 320...Data processing unit 130, 220, 330...Management unit 140, 230-1, 230-2, 340, 420...Frame processing unit 150, 210-1, 210-2, 350, 410...Transmission / reception unit 300...Application execution unit 430...Link management unit WP11, WP12, WP13, WP21, WP22, WP23, WP24, WP31, WP32, WP33...wireless signal processing unit

Claims

1. An access point comprising: a communication circuit configured to transmit and receive wireless signals; and a processor configured to use the communication circuit to establish multiple links with each of another access point and a terminal device, and to switch at least one link from a link with the other access point to a link with the terminal device, or from a link with the terminal device to a link with the other access point, based on a first wireless environment on the other access point side and a second wireless environment on the terminal device side.

2. The access point according to claim 1, wherein the first wireless environment corresponds to the amount of traffic on the other access point side, and the second wireless environment corresponds to the amount of traffic on the terminal device side.

3. The access point of claim 2, wherein the processor is further configured to compare the traffic volume on the other access point side with the traffic volume on the terminal device side, and switch at least one link from a link with the other access point to a link with the terminal device when the traffic volume on the other access point side is greater than the traffic volume on the terminal device side by a first threshold or more, and to switch at least one link from a link with the terminal device to a link with the other access point when the traffic volume on the terminal device side is greater than the traffic volume on the other access point side by a second threshold or more.

4. The access point of claim 2, wherein the processor is further configured to switch at least one link from a link with the other access point to a link with the terminal device, or from a link with the terminal device to a link with the other access point, based on an instruction received from the other access point via the communication circuit, after transmitting information regarding traffic volume between the other access point and the other access point and information regarding traffic volume between the other access point and the terminal device using the communication circuit.

5. A control device configured to control an access point that establishes multiple links with each of other access points and terminal devices, comprising: a communication circuit configured to transmit and receive signals; and a processor configured to acquire, from the access point or the other access point, information regarding a first radio environment between the access point and the other access point and information regarding a second radio environment between the access point and the terminal device via the communication circuit, and to instruct the access point via the communication circuit to switch at least one link from a link with the other access point to a link with the terminal device, or from a link with the terminal device to a link with the other access point, based on the first radio environment and the second radio environment.

6. The control device according to claim 5, wherein the first wireless environment corresponds to the amount of traffic on the other access point side at the access point, and the second wireless environment corresponds to the amount of traffic on the terminal device side at the access point.

7. The control device according to claim 6, wherein the processor is further configured to compare the traffic volume on the other access point side with the traffic volume on the terminal device side, and instruct the access point via the communication circuit to switch at least one link from a link with the other access point to a link with the terminal device if the traffic volume on the other access point side is greater than the traffic volume on the terminal device side by a first threshold or more, and to switch at least one link from a link with the terminal device to a link with the other access point if the traffic volume on the terminal device side is greater than the traffic volume on the other access point side by a second threshold or more.

8. The control device according to claim 5, wherein the communication circuitry is configured to communicate with the other access points over a network, and the instruction is transmitted to the access point via the other access points.

Images