Base station and terminal

Abstract

To provide a base station and a terminal which improve communication stability in a multi-link.SOLUTION: In a radio system, a base station includes: a first radio signal processing part capable of transmitting and receiving a radio signal using a first channel; a second radio signal processing part capable of transmitting and receiving the radio signal using a second channel; and a link management part. The link management part establishes a multilink with a terminal using the first and second radio signal processing parts, and sets a primary link used as a main link in the multilink and a secondary link used as an auxiliary link. The link management part transmits a first radio frame requesting a change of the primary link to the terminal using the first radio signal processing part set to the primary link, and changes the primary link from the first radio signal processing part to the second radio signal processing part when receiving an acknowledgement from either the first radio signal processing part or the second radio signal processing part after the first radio frame is transmitted.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The embodiments relate to a base station and a terminal. [Background technology]

[0002] 2. Description of the Related Art A wireless LAN (Local Area Network) is known as a wireless system that wirelessly connects a base station and a terminal. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] IEEE Std 802.11-2016, “Figure 4-25 Establishing the IEEE 802.11 association” and “11.3 STA authentication and association”, 7 December 2016 Summary of the Invention [Problem to be solved by the invention]

[0004] The challenge is to improve communication stability during multi-link. [Means for solving the problem]

[0005] A base station according to an embodiment includes a first radio signal processing unit, a second radio signal processing unit, and a link management unit. The first radio signal processing unit is configured to be able to transmit and receive radio signals using a first channel. The second radio signal processing unit is configured to be able to transmit and receive radio signals using a second channel different from the first channel. The link management unit establishes a multilink with a terminal using the first radio signal processing unit and the second radio signal processing unit, and sets a primary link to be used as a main link and a secondary link to be used as an auxiliary link in the multilink. The link management unit uses the first radio signal processing unit set as the primary link to transmit a first radio frame to the terminal requesting a change of the primary link, and when either the first radio signal processing unit or the second radio signal processing unit receives an acknowledgment from the terminal after the first radio frame is transmitted, changes the primary link from the first radio signal processing unit to the second radio signal processing unit. [Effects of the Invention]

[0006] The base station according to the embodiment can improve communication stability during multi-link. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a conceptual diagram showing an example of the overall configuration of a wireless system according to the first embodiment. [Figure 2] FIG. 2 is a conceptual diagram showing a specific example of a format of a radio frame in the radio system according to the first embodiment. [Figure 3] FIG. 3 is a block diagram showing an example of the configuration of a base station included in the wireless system according to the first embodiment. [Figure 4] FIG. 4 is a block diagram showing an example of functions of a base station included in the wireless system according to the first embodiment. [Figure 5] FIG. 5 is a block diagram showing an example of the configuration of a terminal included in the wireless system according to the first embodiment. [Figure 6]FIG. 6 is a block diagram showing an example of functions of a terminal included in the wireless system according to the first embodiment. [Figure 7] FIG. 7 is a block diagram showing an example of detailed functions of a link management unit in the base station included in the wireless system according to the first embodiment. [Figure 8] FIG. 8 is a flowchart showing an example of multi-link processing in the wireless system according to the first embodiment. [Figure 9] FIG. 9 is a table showing an example of link management information in the wireless system according to the first embodiment. [Figure 10] FIG. 10 is a flowchart showing an example of a data transmission method in a multi-link state in the wireless system according to the first embodiment. [Figure 11] FIG. 11 is a flowchart showing an example of an execution condition for the primary change process in the wireless system according to the first embodiment. [Figure 12] FIG. 12 is a flowchart showing a specific example of the primary change process in the wireless system according to the first embodiment. [Figure 13] FIG. 13 is a table showing an example of changes in link management information due to the primary change process described with reference to FIG. [Figure 14] FIG. 14 is a conceptual diagram showing a specific example of a radio frame used in the primary change process of the wireless system according to the first embodiment. [Figure 15] FIG. 15 is a conceptual diagram showing a specific example of a radio frame used in the primary change process of the wireless system according to the first embodiment. [Figure 16] FIG. 16 is a flowchart showing a specific example of a method for using multilink power save in the wireless system according to the second embodiment. [Figure 17] FIG. 17 is a table showing an example of changes in link management information due to the use of the multi-link power save described in FIG. [Figure 18] FIG. 18 is a flowchart showing a specific example of the primary change process in the wireless system according to the second embodiment. [Figure 19] FIG. 19 is a table showing an example of changes in link management information due to the primary change process described with reference to FIG. [Figure 20] FIG. 20 is a conceptual diagram showing an example of frequency bands used for wireless communication in a wireless system according to the third embodiment. [Figure 21] FIG. 21 is a flowchart showing an example of an execution condition for a channel change process in the wireless system according to the third embodiment. [Figure 22] FIG. 22 is a flowchart showing a specific example of channel change processing in the wireless system according to the third embodiment. [Figure 23] FIG. 23 is a table showing an example of changes in link management information due to the channel change process described with reference to FIG. [Figure 24] FIG. 24 is a conceptual diagram showing a specific example of a radio frame used in the channel change process of the wireless system according to the third embodiment. [Figure 25] FIG. 25 is a flowchart showing a specific example of a channel change process in a wireless system according to a first modification of the third embodiment. [Figure 26] FIG. 26 is a flowchart showing a specific example of a channel change process in a wireless system according to a second modification of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Each embodiment will be described below with reference to the drawings. The embodiments illustrate devices and methods for embodying the technical ideas of each invention. The drawings are schematic or conceptual. The dimensions and proportions of each drawing are not necessarily the same as those in reality. The technical ideas of the present invention are not specified by the shape, structure, arrangement, etc. of the components. Furthermore, in the following description, the same reference numerals are used to designate components having substantially the same functions and configurations.

[0009] <1> First embodiment The wireless system 1 according to the first embodiment relates to a method for switching a primary link set in a multi-link. The wireless system 1 according to the first embodiment will be described below.

[0010] <1-1> Configuration of wireless system 1 <1-1-1> Overall configuration of wireless system 1 1 shows an example of the configuration of a wireless system 1 according to the first embodiment. As shown in FIG. 1, the wireless system 1 includes a base station 10, a terminal 20, and a server 30, for example.

[0011] The base station 10 is connected to a network NW and is used as an access point of a wireless LAN. For example, the base station 10 can wirelessly distribute data received from the network NW to the terminal 20. The base station 10 can also be connected to the terminal 20 using one type of band or multiple types of bands. In this specification, a wireless connection using multiple types of bands between the base station 10 and the terminal 20 is referred to as a "multi-link." The communication between the base station 10 and the terminal 20 is based on, for example, the IEEE 802.11 standard.

[0012] The terminal 20 is a wireless terminal such as a smartphone or a tablet PC. The terminal 20 can transmit and receive data to and from a server 30 on the network NW via a base station 10 wirelessly connected to the terminal 20. The terminal 20 may also be other electronic devices such as a desktop computer or a laptop computer. The terminal 20 may be any device that can at least communicate with the base station 10 and perform the operations described below.

[0013] The server 30 can store various information, for example, data of content intended for the terminal 20. The server 30 is connected to the network NW by wire, for example, and is configured to be able to communicate with the base station 10 via the network NW. It is sufficient for the server 30 to be able to communicate with at least the base station 10. In other words, communication between the base station 10 and the server 30 may be wired or wireless.

[0014] In the wireless system 1 according to the first embodiment, data communication between the base station 10 and the terminal 20 is based on the OSI (Open Systems Interconnection) reference model. In the OSI reference 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).

[0015] The data link layer includes, for example, an LLC (Logical Link Control) layer and a MAC (Media Access Control) layer. The LLC layer adds a DSAP (Destination Service Access Point) header and an SSAP (Source Service Access Point) header to data input from an upper application, for example, to form an LLC packet. The MAC layer adds a MAC header to an LLC packet, for example, to form a MAC frame.

[0016] Fig. 2 shows a specific example of the format of a wireless frame used in communication between the base station 10 and the terminal 20 in the wireless system 1 according to the first embodiment. As shown in Fig. 2, the wireless frame includes, for example, a Frame Control field, a Duration field, an Address1 field, an Address2 field, an Address3 field, a Sequence Control field, other control information fields, a Frame Body field, and an FCS (Frame Check Sequence) field.

[0017] The Frame Control field through other control information fields correspond to, for example, the MAC header included in the MAC frame. The Frame Body field corresponds to, for example, the MAC payload included in the MAC frame. The FCS field stores an error detection code for the MAC header and Frame Body field, and is used to determine whether or not there is an error in the wireless frame.

[0018] The Frame Control field indicates various control information, including, for example, a Type value, a Subtype value, a To DS (To Distribution System) value, and a From DS value. The Type value indicates the frame type of the wireless frame. For example, a Type value of "00" indicates that the wireless frame is a management frame. A Type value of "01" indicates that the wireless frame is a control frame. A Type value of "10" indicates that the wireless frame is a data frame.

[0019] The contents of the wireless frame change depending on the combination of the Type and Subtype values. For example, "00 / 1000 (Type value / Subtype value)" indicates that the wireless frame is a beacon signal. The meaning of the To DS and From DS values ​​varies depending on the combination. For example, "00 (To DS / From DS)" indicates that the data is between terminals within the same IBSS (Independent Basic Service Set). "10" indicates that the data frame is directed from outside to the DS (Distribution System). "01" indicates that the data frame is directed outside the DS. "11" is used when configuring a mesh network.

[0020] The Duration field indicates the planned period for using the wireless link. Multiple Address fields indicate the BSSID, source address, destination address, sender terminal address, receiver terminal address, etc. The Sequence Control field indicates the MAC frame sequence number and the fragment number for the fragment. Other control information fields include, for example, traffic type (TID) information. TID information may be inserted at other positions within the wireless frame. The Frame Body field contains information according to the type of frame. For example, the Frame Body field stores data if it corresponds to a data frame.

[0021] <1-1-2> Configuration of base station 10 3 shows an example of the configuration of a base station 10 included in the wireless system 1 according to the first embodiment. As shown in FIG. 3, the base station 10 includes, for example, a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, a wireless communication module 14, and a wired communication module 15.

[0022] The CPU 11 is a circuit capable of executing various programs and controls the overall operation of the base station 10. The ROM 12 is a non-volatile semiconductor memory and stores programs and control data for controlling the base station 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 circuit used to transmit and receive data via wireless signals and is connected to an antenna. The wireless communication module 14 also includes, for example, multiple communication modules each corresponding to a multiple frequency band. The wired communication module 15 is a circuit used to transmit and receive data via wired signals and is connected to the network NW.

[0023] Fig. 4 shows an example of the functional configuration of the base station 10 included in the wireless system 1 according to the first embodiment. As shown in Fig. 4, the base station 10 includes, for example, a data processing unit 110, a link management unit 120, and radio signal processing units 130, 140, and 150. The processing of the data processing unit 110, the link management unit 120, and the radio signal processing units 130, 140, and 150 is realized by, for example, a CPU 11 and a wireless communication module 14.

[0024] The data processing unit 110 can perform LLC layer processing and upper layer (layers 3 to 7) processing on input data. For example, the data processing unit 110 outputs data input from the server 30 via the network NW to the link management unit 120. The data processing unit 110 also transmits data input from the link management unit 120 to the server 30 via the network NW.

[0025] The link management unit 120 performs, for example, part of MAC layer processing on the input data. The link management unit 120 also manages links with the terminal 20 based on notifications from the radio signal processing units 130, 140, and 150. The link management unit 120 includes link management information 121. The link management information 121 is stored in, for example, the RAM 13, and includes information on the terminal 20 that is wirelessly connected to the base station 10. The link management unit 120 also includes an association processing unit 122 and an authentication processing unit 123. When the association processing unit 122 receives a connection request from the terminal 20 via any of the radio signal processing units 130, 140, and 150, the association processing unit 122 executes a protocol related to association. Following the connection request, the authentication processing unit 123 executes a protocol related to authentication.

[0026] Each of the radio signal processing units 130, 140, and 150 transmits and receives data between the base station 10 and the terminal 20 using radio communication. For example, each of the radio signal processing units 130, 140, and 150 adds a preamble, a PHY header, and the like to data input from the link management unit 120 to create a radio frame. Then, each of the radio signal processing units 130, 140, and 150 converts the radio frame into a radio signal and distributes the radio signal via the antenna of the base station 10. Also, each of the radio signal processing units 130, 140, and 150 converts a radio signal received via the antenna of the base station 10 into a radio frame. Then, each of the radio signal processing units 130, 140, and 150 outputs the data included in the radio frame to the link management unit 120.

[0027] In this way, each of the radio signal processing units 130, 140, and 150 can perform, for example, part of the MAC layer processing and layer 1 processing on input data or radio signals. For example, the radio signal processing unit 130 handles radio signals in the 2.4 GHz band. The radio signal processing unit 140 handles radio signals in the 5 GHz band. The radio signal processing unit 150 handles radio signals in the 6 GHz band. The radio signal processing units 130, 140, and 150 may or may not share an antenna of the base station 10.

[0028] <1-1-3> Configuration of terminal 20 Fig. 5 shows an example of the configuration of the terminal 20 included in the wireless system 1 according to the first embodiment. As shown in Fig. 5, the terminal 20 includes, for example, a CPU 21, a ROM 22, a RAM 23, a wireless communication module 24, a display 25, and a storage 26.

[0029] The CPU 21 is a circuit capable of executing various programs and controls the overall operation of the terminal 20. The ROM 22 is a non-volatile semiconductor memory and stores programs and control data for controlling the terminal 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 a circuit used to transmit and receive data via wireless signals and is connected to an antenna. The wireless communication module 24 also includes, for example, multiple communication modules corresponding to multiple frequency bands. The display 25 displays, for example, a GUI (Graphical User Interface) corresponding to application software. The display 25 may also function as an input interface for the terminal 20. The storage 26 is a non-volatile storage device and stores, for example, system software for the terminal 20. The terminal 20 does not necessarily have a display. For example, the display 25 may be omitted in an IoT terminal.

[0030] Fig. 6 shows an example of the functional configuration of the terminal 20 included in the wireless system 1 according to the first embodiment. As shown in Fig. 6, the terminal 20 includes, for example, a data processing unit 210, a link management unit 220, wireless signal processing units 230, 240, and 250, and an application execution unit 260. The processing of the data processing unit 210, the link management unit 220, and the wireless signal processing units 230, 240, and 250 is realized by, for example, the CPU 21 and the wireless communication module 24.

[0031] Data processing unit 210 can perform LLC layer processing and upper layer (layers 3 to 7) processing on input data. For example, data processing unit 210 outputs data input from application execution unit 260 to link management unit 220. Data processing unit 210 also outputs data input from link management unit 220 to application execution unit 260.

[0032] The link management unit 220 performs, for example, part of MAC layer processing on the input data. The link management unit 220 also manages links with the base station 10 based on notifications from the radio signal processing units 230, 240, and 250. The link management unit 220 includes link management information 221. The link management information 221 is stored in, for example, the RAM 23, and includes information on the base station 10 wirelessly connected to the terminal 20. The link management unit 220 also includes an association processing unit 222 and an authentication processing unit 223. When the association processing unit 222 receives a connection request from the base station 10 via any of the radio signal processing units 230, 240, and 250, the association processing unit 222 executes a protocol related to association. Following the connection request, the authentication processing unit 223 executes a protocol related to authentication.

[0033] Each of the radio signal processing units 230, 240, and 250 transmits and receives data between the base station 10 and the terminal 20 using radio communication. For example, each of the radio signal processing units 230, 240, and 250 adds a preamble, a PHY header, and the like to data input from the link management unit 220 to create a radio frame. Then, each of the radio signal processing units 230, 240, and 250 converts the radio frame into a radio signal and distributes the radio signal via the antenna of the terminal 20. Also, each of the radio signal processing units 230, 240, and 250 converts a radio signal received via the antenna of the terminal 20 into a radio frame. Then, each of the radio signal processing units 230, 240, and 250 outputs the data included in the radio frame to the link management unit 220.

[0034] In this way, each of the radio signal processing units 230, 240, and 250 can perform, for example, part of the MAC layer processing and layer 1 processing on input data or radio signals. For example, the radio signal processing unit 230 handles radio signals in the 2.4 GHz band. The radio signal processing unit 240 handles radio signals in the 5 GHz band. The radio signal processing unit 250 handles radio signals in the 6 GHz band. The radio signal processing units 230, 240, and 250 may or may not share an antenna of the terminal 20.

[0035] The application execution unit 260 executes an application that can use data input from the data processing unit 210. For example, the application execution unit 260 can display information about the application on the display 25. The application execution unit 260 can also operate based on operations on an input interface.

[0036] In the wireless system 1 according to the first embodiment described above, the wireless signal processing units 130, 140, and 150 of the base station 10 are configured to be connectable to the wireless signal processing units 230, 240, and 250 of the terminal 20, respectively. That is, the wireless signal processing units 130 and 230 can be wirelessly connected to each other using the 2.4 GHz band. The wireless signal processing units 140 and 240 can be wirelessly connected to each other using the 5 GHz band. The wireless signal processing units 150 and 250 can be wirelessly connected to each other using the 6 GHz band. In this specification, each wireless signal processing unit may be referred to as an "STA function." That is, the wireless system 1 according to the embodiment has multiple STA functions.

[0037] <1-1-4> Detailed configuration of the link management section 7 shows details of a channel access function in the link management unit 120 of the base station 10 included in the wireless system 1 according to the first embodiment. Note that the function of the link management unit 220 of the terminal 20 is similar to that of, for example, the link management unit 120 of the base station 10, and therefore a description thereof will be omitted. As shown in FIG. 7, the link management unit 120 includes, for example, a data categorization unit 124, transmission queues 125A, 125B, 125C, 125D, and 125E, CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) execution units 126A, 126B, 126C, 126D, and 126E, and a data collision management unit 127.

[0038] The data categorization unit 124 categorizes the data input from the data processing unit 110. Data categories are set, for example, as "LL (Low Latency)", "VO (Voice)", "VI (Video)", "BE (Best Effort)", and "BK (Background)". LL is applied to data that requires low latency. For this reason, it is preferable that LL data be processed with priority over any of VO, VI, BE, and BK data.

[0039] Then, the data categorization unit 124 inputs the categorized data to one of the transmission queues 125A, 125B, 125C, 125D, and 125E. Specifically, LL data is input to the transmission queue 125A. VO data is input to the transmission queue 125B. VI data is input to the transmission queue 125C. BE data is input to the transmission queue 125D. BK data is input to the transmission queue 125E. Then, the input data of each category is accumulated in one of the corresponding transmission queues 125A to E.

[0040] In CSMA / CA, each of CSMA / CA execution units 126A, 126B, 126C, 126D, and 126E confirms by carrier sense that no wireless signals are being transmitted by other terminals, etc., and waits for transmission for a time period specified by a preset access parameter. Then, CSMA / CA execution units 126A, 126B, 126C, 126D, and 126E extract data from transmission queues 125A, 125B, 125C, 125D, and 125E, respectively, and outputs the extracted data to at least one of wireless signal processing units 130, 140, and 150 via data collision management unit 127. Then, a wireless signal containing the data is transmitted by the wireless signal processing unit (STA function) that has acquired the transmission right through CSMA / CA.

[0041] The CSMA / CA execution unit 126A performs CSMA / CA on the LL data held in the transmission queue 125A. The CSMA / CA execution unit 126B performs CSMA / CA on the VO data held in the transmission queue 125B. The CSMA / CA execution unit 126C performs CSMA / CA on the VI data held in the transmission queue 125C. The CSMA / CA execution unit 126D performs CSMA / CA on the BE data held in the transmission queue 125D. The CSMA / CA execution unit 126E performs CSMA / CA on the BK data held in the transmission queue 125E.

[0042] The access parameters are assigned so that wireless signal transmission is prioritized in the following order: LL, VO, VI, BE, and BK. The access parameters include, for example, CWmin, CWmax, AIFS, and TXOPLimit. CWmin and CWmax respectively indicate the minimum and maximum values ​​of the contention window, which is the transmission waiting time for collision avoidance. AIFS (Arbitration Inter Frame Space) indicates a fixed transmission waiting time set for each access category for collision avoidance control with a priority control function. TXOPLimit indicates the upper limit of TXOP (Transmission Opportunity), which corresponds to the channel occupancy time. For example, the shorter the CWmin and CWmax, the easier it is for the transmission queue 125 to obtain the transmission right. The smaller the AIFS, the higher the priority of the transmission queue 125. The larger the value of TXOPLimit, the greater the amount of data transmitted with one transmission right.

[0043] The data collision management unit 127 prevents data collisions when multiple CSMA / CA execution units 126 acquire the transmission right using the same STA function. Specifically, the data collision management unit 127 adjusts the transmission timing of data in different categories that have been acquired by the same STA function, and transmits data from the highest priority category to the STA function. For example, the STA function that has acquired the transmission right using CSMA / CA in the LL transmission queue 125A may be the same as the STA function that has acquired the transmission right using CSMA / CA in one of the other transmission queues 125B to 125E. In this case, the data collision management unit 127 prioritizes transmitting the data stored in the transmission queue 125A to the STA function. Similarly, for other combinations of transmission queues 125, data is transmitted in the order based on the priority set for the category. This prevents collisions between data assigned for transmission to the same STA function.

[0044] In this embodiment, the link management unit implements the channel access function. However, each STA function may also implement the channel access function. When the link management unit implements the channel access function, each STA function detects the state (idle / busy) of the wireless channel of the corresponding link, and the link management unit determines whether data can be transmitted (e.g., which link to use for transmission). On the other hand, when each STA function implements the channel access function, each STA function independently performs carrier sensing and transmits data. In this case, channel access when multiple links are used simultaneously may be performed by sharing access parameters between the multiple STA functions, or by sharing access parameters through the link management unit. The base station 10 and the terminal 20 can simultaneously use multiple links by transmitting data based on access parameters common to the multiple STA functions.

[0045] <1-2> Operation of wireless system 1 An example of various operations related to the multilink of the wireless system 1 according to the first embodiment will be described below. In the following description, for simplicity, STA1 and STA2 of the base station 10 will also be referred to as the "access point AP." Transmission of wireless signals from STA1 and STA2 of the terminal 20 to the access point AP corresponds to transmission of wireless signals to STA1 and STA2 of the base station 10, respectively. When STA1 and STA2 are described individually, they indicate the STA function of the terminal 20.

[0046] <1-2-1> About Multilink Fig. 8 is a flowchart showing an example of multi-link processing in the wireless system 1 according to the first embodiment. As shown in Fig. 8, in the multi-link processing, for example, steps S10 to S16 are executed in order.

[0047] Specifically, first, in the process of step S10, the terminal 20 transmits a probe request to the base station 10. The probe request is a signal that confirms whether or not a base station 10 is present in the vicinity of the terminal 20. The Frame Control field of the probe request contains, for example, "00 / 0100 (Type value / Subtype value)." Upon receiving the probe request, the base station 10 executes the process of step S11.

[0048] In the process of step S11, the base station 10 transmits a probe response to the terminal 20. The probe response is a signal that the base station 10 uses to respond to a probe request from the terminal 20. The Frame Control field of the probe response contains, for example, "00 / 0101 (Type value / Subtype value)." Upon receiving the probe request, the terminal 20 executes the process of step S12.

[0049] In the process of step S12, the terminal 20 transmits a multilink association request to the base station 10 via at least one STA function. The multilink association request is a signal for requesting the base station 10 to establish a multilink. For example, the multilink association request is generated by the link management unit 220 of the terminal 20. The Frame Control field of the multilink association request contains, for example, "00 / xxxx (Type value / Subtype value (xxxx is a predetermined numerical value))". Upon receiving the multilink association request, the link management unit 120 of the base station 10 executes the process of step S13.

[0050] In the process of step S13, the link management unit 120 of the base station 10 executes a multi-link association process using one STA function. Specifically, the base station 10 first executes an association process of a first STA function with the terminal 20. Then, when a wireless connection (link) is established in the first STA function, the link management unit 120 of the base station 10 executes an association process of a second STA function using the first STA function with which the link is established. In other words, the STA function with which the link is established is used in the association process of the STA function with which the link is not established. When the association processes of at least two STA functions are completed, the base station 10 establishes a multi-link and executes the process of step S14.

[0051] Note that a multilink may be established when a link is established in the first STA function. For example, the base station 10 and the terminal 20 can simultaneously execute association for the multilink by notifying each other of their multilink capabilities, the links to be multilinked, and the operation parameters for each link prior to the association process. Specifically, when the first STA function starts association, the link management units 120 and 220 instruct the establishment of a multilink and specify the links to be multilinked. Then, the link management units 120 and 220 execute association for each link and manage these links as a multilink.

[0052] In the process of step S14, the link management unit 120 of the base station 10 updates the link management information 121. In this example, the process of step S14 is executed after two links are established, but the link management information 121 may be updated every time the link status is updated, or may be updated when a multi-link is established. Once a multi-link is established and the link management information is updated, the base station 10 executes the process of step S15.

[0053] In the process of step S15, the base station 10 transmits a multi-link establishment response to the terminal 20. The multi-link establishment response is a signal that the base station 10 uses to respond to a multi-link request from the terminal 20. The Frame Control field of the multi-link association request contains, for example, "00 / 0001 (Type value / Subtype value)". Based on the reception of the multi-link establishment response, the link management unit 220 of the terminal 20 recognizes that a multi-link with the base station 10 has been established. When the terminal 20 receives the multi-link establishment response, it executes the process of step S16.

[0054] In the processing of step S16, the link management unit 220 of the terminal 20 updates the link management information 221. That is, the terminal 20 records in the link management information 221 that a multilink has been established with the base station 10. This completes the multilink processing in the wireless system 1 according to the first embodiment, and data communication using the multilink becomes possible between the base station 10 and the terminal 20.

[0055] Fig. 9 shows an example of link management information 121 in the wireless system 1 according to the first embodiment. Note that the link management information 221 of the terminal 20 contains information similar to the link management information 121 of the base station 10, and therefore a description thereof will be omitted. As shown in Fig. 9, the link management information 121 contains information such as STA function, frequency band, link destination ID, presence or absence of multi-link, and TID.

[0056] In this example, "STA1" corresponds to the STA function using the 6 GHz frequency band, i.e., the radio signal processing unit 150 or 250. "STA2" corresponds to the STA function using the 5 GHz frequency band, i.e., the radio signal processing unit 140 or 240. "STA3" corresponds to the STA function using the 2.4 GHz frequency band, i.e., the radio signal processing unit 130 or 230.

[0057] The link destination ID corresponds to the identifier of the terminal 20 in the link management information 121, and corresponds to the identifier of the base station 10 in the link management information 221. In this example, a multi-link using STA1 and STA2 is established. When a multi-link is established, each of the link management units 120 and 220 transmits data input from an upper layer using the link of at least one STA function associated with the multi-link. In addition, STA1 is set as the primary link, and STA2 is set as the secondary link.

[0058] A primary link is a link used as the main link in a multi-link. A secondary link is a link used as an auxiliary link in a multi-link. The links constituting a multi-link are assigned as either a primary link or a secondary link. There may be two or more primary links and two or more secondary links. For each terminal 10 that has established a multi-link with a base station 10, the link sets constituting each multi-link may be different from each other, and the primary links may also be different from each other. By allowing different primary links, the optimal link between the base station 10 and each terminal 20 can be set as the primary link. This is expected to have the effect of improving the quality of wireless communication, etc.

[0059] Furthermore, the primary link is used not only for transmitting and receiving assigned data but also for transmitting and receiving control information related to the operation of the multilink. The primary link is set in advance, for example, when the multilink is established between the base station 10 and the terminal 20. The STA function used as the primary link may be set in priority according to the frequency band or according to the radio wave strength of the link. Furthermore, the setting of the primary link may be changed as appropriate after the multilink is established by a primary change process described later.

[0060] "TID" in link management information 121 indicates the association between STA functions and TID information. Each STA function transmits and receives data corresponding to the assigned TID information. For example, each of TID#1 to 3 corresponds to LL, VO, VI, BE, or BK. One STA function may be associated with one traffic, i.e., one TID information, or multiple STA functions may be associated with one traffic, i.e., one TID information. In this example, TID#1 is assigned to both STA1 and STA2. TID#2 is assigned to STA1. TID#3 is assigned to STA2.

[0061] A traffic flow corresponding to such an association between traffic and STA functions is set in advance when setting up a multilink between the base station 10 and the terminal 20. For example, the link management unit 220 of the terminal 20 determines the association between traffic and STA functions and requests the link management unit 120 of the base station 10. Then, the base station 10 responds to the request, thereby determining the association between traffic and STA functions.

[0062] Note that traffic is set to be evenly distributed among multiple links constituting a multi-link, for example. This is not limiting, and traffic of similar types (priority / non-priority, etc.) may be collected on one of the links constituting a multi-link. Furthermore, as an association between STA functions and traffic, for example, voice is associated with the 2.4 GHz frequency band, and video is associated with 5G. In this way, it is preferable to allocate frequencies used for transmission and reception according to the type of information handled and the data volume.

[0063] <1-2-2> Data transfer during multi-link Fig. 10 shows an example of a data transmission method in multi-link mode in the base station 10 included in the wireless system 1 according to the first embodiment. As shown in Fig. 10, when the base station 10 acquires data from an upper layer, it sequentially executes the processes of steps S20 to S22.

[0064] Specifically, in step S20, the link management unit 120 first acquires TID information corresponding to the data. In other words, the link management unit 120, for example, references the MAC header in the wireless frame acquired from the upper layer and checks whether the TID information included in the MAC header is LL, VO, VI, BE, or BK. This allows the link management unit 120 to check which TID the traffic flow of the data corresponds to.

[0065] Next, in the process of step S21, the link management unit 120 acquires the STA function corresponding to the confirmed TID information. At this time, the link management unit 120 confirms the association between the TID information and the STA function by referring to the link management information 121. Note that in the process of step S21, the number of STA functions acquired by the link management unit 120 may be one or more.

[0066] Next, in the process of step S22, the link management unit 120 outputs data to the acquired STA function. If one STA function is associated with the output data (traffic), the data is transmitted serially using the one STA function. On the other hand, if multiple STA functions are associated with the traffic, the data is transmitted in parallel using the multiple STA functions.

[0067] When one traffic stream is transmitted in parallel, data allocation and rearrangement are performed between the link management unit 120 of the base station 10 and the link management unit 220 of the terminal 20. Data allocation is performed by the link management unit on the transmitting side, and data rearrangement is performed by the link management unit on the receiving side. For example, the link management unit on the transmitting side adds a flag indicating multi-link and an identification number to the wireless frame. The link management unit on the receiving side rearranges the data based on the added flag and identification number.

[0068] Furthermore, in the wireless system 1 according to the first embodiment, when a plurality of pieces of data are received from an upper layer, the link management unit may aggregate the received plurality of pieces of data. Aggregation in multi-link may be used as an optional function that can be selected by the user.

[0069] <1-2-3> Primary change process First, an example of a condition for executing the primary change process will be described. Fig. 11 is a flowchart showing an example of a condition for executing the primary change process in the wireless system 1 according to the first embodiment. As shown in Fig. 11, first, the link management unit 120 monitors the interference status of OBSSs (Overlapping BSSs) in the primary link and the interference status of OBSSs in the secondary link (step S30).

[0070] Then, the link management unit 120 checks whether the interference of the OBSS in the primary link is greater than the interference of the OBSS in the secondary link (step S31). For example, the link management unit 120 checks whether the channel occupation time of the OBSS for the primary link is greater than the channel occupation time of the OBSS for the secondary link. Note that interference evaluation may use something other than the channel occupation time, as long as it uses at least a factor that makes the channel busy during periods other than the exchange of signals in the own BSS. For example, interference evaluation may use the magnitude of interference power, interference from other communication systems, the presence of noise power, etc.

[0071] If the OBSS interference in the primary link is greater than the OBSS interference in the secondary link (step S31, YES), the link management unit 120 executes a primary change process (step S32). When the primary change process is executed, the primary link is changed to another link used in the multi-link. In other words, the primary link is switched with one secondary link.

[0072] If the OBSS interference in the primary link is equal to or less than the OBSS interference in the secondary link (step S31, NO), or if the primary change process in step S32 is completed, the link management unit 120 ends the series of processes related to the execution of the primary change process. The link management unit 120 may periodically execute the processes of steps S30 to S32 described above.

[0073] The primary change process may be performed as needed based on the results of continuous monitoring of the OBSS interference status. The trigger for the primary change process is not limited to the OBSS interference status. The primary change process may also be performed based on the signal strength of each link. In this case, the link management unit 120 checks, for example, whether the signal strength of the primary link is weaker than that of the secondary link.

[0074] Next, a specific example of the primary change process will be described with reference to Fig. 12. Fig. 12 is a flowchart showing a specific example of the primary change process in the wireless system 1 according to the first embodiment. In the initial state of this example, the link state shown in Fig. 9 is set. STA1 and STA2 are set as the primary link and secondary link, respectively.

[0075] 9, when data of TID#2 is transmitted from the access point AP to the terminal 20, the STA1 of the terminal 20 receives the data (step S40). Then, the STA1 of the terminal 20 transmits a wireless signal ("ACK: Acknowledge") to the access point AP notifying that the data has been received (step S41).

[0076] 11 is satisfied, the link management unit 120 of the base station 10 transmits a radio signal requesting a change of the primary link to the terminal 20 using the primary link (STA1) (step S42). When the STA1 of the terminal 20 receives the radio signal, the link management unit 220 of the terminal 20 checks whether or not the primary link can be changed.

[0077] If the primary link can be changed, the link management unit 220 of the terminal 20 transmits a positive response ("OK") to the access point AP via STA1 or STA2 (step S43). If the primary link cannot be changed, the link management unit 220 of the terminal 20 may transmit a negative response ("NO") to the access point AP via STA1 or STA2.

[0078] After the process of step S43, the link management unit 120 of the base station 10 and the link management unit 220 of the terminal 20 each change the primary link from STA1 to STA2 (step S44). Specifically, STA1 is changed from the primary link to the secondary link, and STA2 is changed from the secondary link to the primary link.

[0079] After the change of the primary link is executed in step S44, when the data of TID#2 is transmitted from the access point AP to the terminal 20, the STA2 of the terminal 20 receives the data (step S45). Then, the STA2 of the terminal 20 transmits a wireless signal ("ACK") to the access point AP notifying that the data has been received (step S46).

[0080] Fig. 13 shows an example of changes in the link management information 121 due to the primary change process described in Fig. 12. As shown in Fig. 13, the primary / secondary settings and TID settings of the two links that make up the multilink are swapped by executing the primary change process.

[0081] Specifically, as a result of the primary link change process, STA1 is changed from a primary link to a secondary link, and the TIDs assigned to STA1 are changed from TID#1 and 2 to TID#1 and 3. On the other hand, STA2 is changed from a secondary link to a primary link, and the TIDs assigned to STA2 are changed from TID#1 and 3 to TID#1 and 2.

[0082] As described above, the primary link set in a multilink may be changed by a primary change process that is executed based on the satisfaction of predetermined conditions. Furthermore, the TID associated with the primary link may be changed along with the change of the primary link. The settings relating to the association between traffic and TID information may be maintained even when the primary link is changed. In other words, the primary change process only requires that the STA function that transmits and receives multilink control information be switched to the STA function newly set for the primary link.

[0083] 14 and 15 show specific examples of wireless frames used in the primary link change process of the wireless system 1 according to the first embodiment. Fig. 14 corresponds to a wireless frame transmitted when the access point AP requests the terminal 20 to change the primary link. Fig. 15 corresponds to a wireless frame returned by the terminal 20 to the access point AP in response to the request to change the primary link.

[0084] 14, the Frame Body of the wireless frame requesting a change of the primary link includes, for example, a terminal identifier AID (Association Identifier), a primary change request, and an identifier of the next primary link. Based on the "primary change request," the link management unit 220 of the terminal 20 corresponding to the AID references the "identifier of the next primary link" and determines whether or not the primary link can be changed.

[0085] When a change of the primary link is possible, the Frame Body of the wireless frame corresponding to the response to the primary change request, i.e., the acknowledgement, contains "Ready" as shown in Figure 15(a). "Ready" corresponds to a bit that notifies that a primary change is possible.

[0086] On the other hand, if a change of the primary link is not possible, the Frame Body of the wireless frame corresponding to the response to the primary change request, i.e., a negative response, includes "No" and "Reason" as shown in Figure 15(b). "No" corresponds to a bit notifying that a primary change is not possible. "Reason" corresponds to a bit notifying the reason why a primary change is not possible. Note that "Reason" may be omitted in the wireless frame corresponding to the response to the primary change request.

[0087] <1-3> Effects of the first embodiment According to the wireless system 1 according to the first embodiment described above, communication stability during multi-link can be improved. The effects of the wireless system 1 according to the embodiment will be described in detail below.

[0088] Base stations and terminals using wireless LANs may have multiple STA functions, each for a different band used, such as 2.4 GHz, 5 GHz, and 6 GHz. In such wireless systems, a wireless connection is established by selecting one of the multiple STA functions, and data communication is performed between the base station and the terminal. In this case, the unselected STA functions are left unused in the wireless system, even if a base station corresponding to the band of the selected STA function exists.

[0089] In contrast, the wireless system 1 according to the first embodiment utilizes multiple STA functions provided in each of the base station 10 and the terminal 20 to establish a multi-link between the base station 10 and the terminal 20. Data communication using the multi-link can use multiple bands in combination, and can fully utilize the functions provided in the wireless LAN device. As a result, the wireless system 1 according to the embodiment can achieve efficient communication and improve communication speed.

[0090] Furthermore, one possible method of operating a multi-link is to set a primary link that is used to transmit and receive information related to the control of the multi-link. By setting a primary link, the wireless system 1 can simplify communication between the link management unit 120 of the base station 10 and the link management unit 220 of the terminal 20.

[0091] On the other hand, in a multi-link, the communication stability may differ for each link that constitutes the multi-link. For example, the interference situation due to OBSS and the strength of radio waves may vary depending on the frequency band being used. Therefore, when a primary link is set in a multi-link, the communication quality of the primary link may be lower than that of the secondary link. Because the primary link is used to control the entire multi-link, it is preferable that the primary link have higher communication quality than the other links.

[0092] Therefore, the wireless system 1 according to the first embodiment switches between the primary link and the secondary link depending on the communication quality of each link used in the multilink. For example, the link management unit 120 of the base station 10 monitors the interference status of each link constituting the multilink. When the link management unit 120 detects that "OBSS interference in the primary link > OBSS interference in the secondary link," it switches between the primary link and the secondary link.

[0093] As described above, the primary link is appropriately changed based on predetermined conditions, thereby maintaining high communication quality of the primary link. As a result, the wireless system 1 according to the first embodiment can improve the stability of multi-link. In other words, the wireless system 1 according to the first embodiment can improve the communication quality between the base station 10 and the terminal 20 during multi-link.

[0094] <2> Second embodiment The wireless system 1 according to the second embodiment has the same configuration as that of the first embodiment. The wireless system 1 according to the second embodiment appropriately sets the secondary link to multi-link power save, and in the primary change process, switches the primary link and switches multi-link power save simultaneously. The following describes the differences between the wireless system 1 according to the second embodiment and the first embodiment.

[0095] <2-1> Operation of wireless system 1 <2-1-1> Multi-link power save In the wireless system 1 according to the second embodiment, multiple types of operation modes are provided for each STA function. Examples of operation modes of the STA function include an active mode, an intermittent operation mode, and a dormant operation mode. The active mode corresponds to a state in which the STA function of the terminal 20 maintains an awake state, thereby enabling wireless signals to be transmitted and received at any time. The intermittent operation mode corresponds to a state in which the STA function of the terminal 20 operates intermittently, by repeatedly switching between an awake state and a dormant state. The dormant operation mode corresponds to a state in which the STA function of the terminal 20 maintains a dormant state, thereby disabling wireless signals from being transmitted and received. The multiple STA functions constituting the multilink include at least one link in the active mode or the intermittent operation mode. The other links constituting the multilink can be set to any of the active mode, the intermittent operation mode, and the dormant operation mode.

[0096] The Awake state corresponds to a state in which radio signals can be transmitted and received. The Dose state corresponds to a state in which radio signals cannot be transmitted or received. In the Doze state, the power supply to the circuitry related to the STA function is appropriately cut off. Therefore, the power consumption of the STA function decreases in the order of active mode, intermittent operation mode, and dormant operation mode. Note that there may also be links that the base station 10 or the terminal 20 can use for communication but that are not included in the link set of the multilink between them (disabled links). In the following, for simplicity of explanation, a link in active mode or intermittent operation mode, i.e., a link that is capable of communication, will be referred to as an "STA function (link) in the Awake state." A link in dormant operation mode, i.e., a link in a power-saving state in which communication is not possible, will be referred to as an "STA function (link) in the Dose state."

[0097] In the multilink in the wireless system 1 according to the second embodiment, the STA function set in the primary link is set to, for example, either active mode or discontinuous operation mode. Meanwhile, the STA function set in the secondary link can be set to either active mode, intermittent operation mode, or dormant mode. For example, the terminal 20 can operate in a power-saving manner by setting the secondary link to dormant mode during multilink. Hereinafter, the multilink state in which the secondary link is set to dormant mode is referred to as "multilink power save." Note that when a multilink is established by multilink processing, the initial state of the secondary link may be set to any of active mode, intermittent operation mode, or dormant mode.

[0098] Fig. 16 shows an example of a method for using multilink power save in the wireless system 1 according to the second embodiment. In the initial state of this example, the link state shown in Fig. 9 is set. STA1 and STA2 are each set to active mode. As shown in Fig. 16, when STA1 and STA2 are each in active mode, both data of TID#2 and data of TID#3 can be transmitted and received.

[0099] When the link management unit 220 of the terminal 20 detects that the first condition is satisfied, it transmits a Doze transition notification signal to the access point AP using the primary link (STA1) (step S50). The first condition corresponds to, for example, no traffic accumulating on the secondary link (STA2). The Doze transition notification signal is a signal notifying of a transition to the Doze state, and corresponds to "disable" shown in the figure. The terminal 20 can learn information about the traffic by receiving a beacon signal from the base station 10 using at least one of STA1 and STA2.

[0100] When STA1 of the base station 10 receives the Doze transition notification signal, the link management unit 120 of the base station 10 checks whether or not it is possible to permit the secondary link to transition to the dormant mode. If it is possible to permit the secondary link to transition to the dormant mode, the link management unit 120 of the base station 10 transmits a positive response ("OK") to the terminal 20 via STA1 or STA2 (step S51). Note that if it is not possible to permit the secondary link to transition to the dormant mode, the link management unit 120 of the base station 10 may transmit a negative response ("NO") to the base station 10 via STA1 or STA2.

[0101] When the terminal 20 receives the positive response in step S51, the link management unit 220 of the terminal 20 changes the STA2 set as the secondary link to the dormant mode (step S52). As a result, the STA1 and STA2 of the terminal 20 enter the Awake state and the Doze state, respectively. At this time, the multilink is in a state where only data of TID#2 can be transmitted and received.

[0102] Thereafter, when the link management unit 220 of the terminal 20 detects that the second condition has been satisfied, it transmits an Awake transition request signal to the access point AP using the primary link (STA1) (step S53). The second condition corresponds to, for example, the accumulation of traffic on the secondary link (STA2). The Awake transition request signal is a signal requesting a transition to the Awake state, and corresponds to "enable" shown in the figure. The terminal 20 can learn information about the traffic by receiving a beacon signal from the base station 10 using STA1 in the active state.

[0103] When STA1 of the base station 10 receives the Awake transition request signal, the link management unit 120 of the base station 10 transmits an acknowledgment ("OK") to the terminal 20 via STA1 corresponding to the primary link (step S54). When the terminal 20 receives the acknowledgment in step S54, the link management unit 220 of the terminal 20 changes STA2, which is set as the secondary link, to active mode (step S55). This causes each of STA1 and STA2 of the terminal 20 to enter the Awake state. As a result, the multilink becomes capable of transmitting and receiving any data of, for example, TID#1 to 3.

[0104] Fig. 17 shows an example of changes in link management information 121 due to the use example of multilink power save described in Fig. 16. As shown in Fig. 17, multilink power save is applied by a Doze transition notification signal and an Awake transition request signal. Specifically, after multilink is established, the terminal 20 transmits a Doze transition notification signal to the base station 10, causing the secondary link in active mode to transition to dormant mode, and transmits an Awake transition request signal, causing the secondary link in dormant mode to transition to active mode.

[0105] As described above, in the wireless system 1 according to the second embodiment, the base station 10 and the terminal 20 can change the mode of the secondary link by transmitting an Awake transition request / Doze transition notification signal. The transmission of the Awake transition request signal is performed using the primary link or another active link. The transmission of the Doze transition notification signal is performed using the primary link or a link to be stopped (a link to be transitioned to a dormant mode).

[0106] The Awake transition request signal and the Doze transition notification signal may be transmitted from either the access point AP or the terminal 20. When the first and second conditions are based on traffic congestion (buffer state), the change of the operation mode is triggered, for example, by the traffic accumulated in the buffer exceeding a predetermined threshold. Also, an intermittent operation mode may be applied to the primary link. In this case, the primary link operates so as to be able to receive a beacon signal including at least multi-link control information.

[0107] <2-1-2> Primary change process Fig. 18 is a flowchart showing a specific example of a primary change process in the wireless system 1 according to the second embodiment. In the initial state of this example, the link state is set to the Doze state shown in Fig. 17. That is, STA1 and STA2 are set to the Awake state and the Doze state, respectively, and the multilink is set to a state in which only data of TID#2 can be transmitted and received.

[0108] 11 is satisfied, the link management unit 120 of the base station 10 transmits a radio signal requesting a change of the primary link to the terminal 20 using the primary link (STA1) in active mode (step S60). When the STA1 of the terminal 20 receives the radio signal, the link management unit 220 of the terminal 20 checks whether or not the primary link can be changed.

[0109] If the primary link can be changed, the link management unit 220 of the terminal 20 transmits a positive response ("OK") to the access point AP via STA1 or STA2 (step S61). If the primary link cannot be changed, the link management unit 220 of the terminal 20 may transmit a negative response ("NO") to the access point AP via STA1 or STA2, as in the first embodiment.

[0110] After the process of step S61, the link management unit 220 first changes the secondary link from the Doze state to the Awake state (step S62). At this time, the secondary link may be set to either the active mode or the intermittent operation mode.

[0111] Then, the access point AP transmits a beacon signal including countdown information indicating the timing to change the primary link to the terminal 20 (step S63). The illustrated "countdown #1 to n" corresponds to n counts of beacon signals that will be transmitted to the terminal 20 until the primary link is changed.

[0112] When the countdown by the multiple beacon signals is completed, the link management unit 120 of the base station 10 and the link management unit 220 of the terminal 20 each change the primary link from STA1 to STA2 (step S64). Specifically, STA1 is changed from the primary link to the secondary link, and STA2 is changed from the secondary link to the primary link. Furthermore, in the second embodiment, STA1, which has been changed to the secondary link in response to the change in primary link, is set to a Doze state in a dormant mode. As a result, the multilink becomes capable of transmitting and receiving data of TID#2 using STA2, and the power consumption of STA1 is suppressed.

[0113] Fig. 19 shows an example of changes in the link management information 121 due to the primary change process described in Fig. 18. As shown in Fig. 19, by executing the primary change process, the primary / secondary settings, TID settings, and operation mode settings of the two links that make up the multilink are swapped.

[0114] Specifically, the primary link change process causes STA1 to change from a primary link in active mode (Awake state) to a secondary link in dormant mode (Doze state). Meanwhile, STA2 changes from a secondary link in dormant mode (Doze state) to a primary link in active mode (Awake state). Note that the settings relating to the association between traffic and TID information may be changed or maintained when the primary link is changed. Other operations of the wireless system 1 according to the second embodiment are the same as those of the first embodiment.

[0115] <2-2> Effects of the second embodiment Because multiple STA functions are used, the power consumption of a multi-link is higher than that of a single-link in which only one STA function is used. Therefore, from the viewpoint of power saving, it is preferable to use a single link when there is no traffic congestion and to use a multi-link when there is traffic congestion. Furthermore, from the viewpoint of low latency, it is preferable to set a link that is used exclusively by LL traffic when LL traffic accumulates. In other words, it is preferable to temporarily set a link for LL and a link for traffic other than LL.

[0116] Therefore, the wireless system 1 according to the second embodiment performs data communication by switching between a single link and a multi-link after the multi-link is established. Specifically, after the multi-link is established, the link management unit 120 of the base station 10 and the link management unit 220 of the terminal 20 control the activation / deactivation of the secondary link. Here, "activating the link" corresponds to setting the active mode, and "deactivating the link" corresponds to setting the dormant mode.

[0117] For example, from the viewpoint of power saving, when there is no traffic congestion, only one link (primary link) of the multiple links constituting the multilink is set to active mode, and the other links (secondary links) are set to inactive mode. In this case, the multilink performs data communication in a state substantially similar to that of a single link. On the other hand, when traffic congestion occurs, high-speed data communication is performed using the multiple links constituting the multilink.

[0118] Also, from the viewpoint of low latency, when LL traffic is not accumulated, the multilink is used in a substantially single-link state by utilizing the idle mode. On the other hand, when LL traffic is accumulated, the multiple links constituting the multilink are used, and for example, one of the multiple links is assigned as a link dedicated to LL traffic.

[0119] As described above, the wireless system 1 according to the second embodiment can reduce power consumption by using the low-power-consumption sleep mode depending on the traffic state. Also, the wireless system 1 according to the second embodiment can protect the LL traffic by controlling link activation / deactivation depending on the presence or absence of LL traffic.

[0120] Furthermore, even when multi-link and the operation suspension mode are combined, the primary change process described in the first embodiment can be executed. On the other hand, when the base station 10 arbitrarily instructs the terminal 20 having a secondary link in the operation suspension mode to switch the primary link, there is a risk that the link state (primary / secondary) on the terminal 20 side will not be synchronized.

[0121] Therefore, in the wireless system 1 according to the second embodiment, the link management unit 120 of the base station 10 executes signaling to control link activation / deactivation with the terminal 20 before switching the primary link. This signaling corresponds to, for example, a countdown using a beacon signal. Furthermore, because the primary link is switched using the primary link before the switch, the link management unit 120 of the base station 10 and the link management unit 220 of the terminal 20 can execute the primary change process regardless of whether the idle mode is being used.

[0122] This allows the link management unit 220 of the terminal 20 to know the timing of switching the primary link based on the signaling. As a result, the wireless system 1 according to the second embodiment can reliably execute the primary change process when using the pause mode. Furthermore, the wireless system 1 according to the second embodiment applies the pause mode for the secondary link in addition to switching the primary link, thereby reducing power consumption when using multi-links.

[0123] Note that, when a plurality of terminals 20 are connected to the base station 10 and a certain terminal 20 has LL traffic, the signaling in the primary switching process described above may be executed to perform exclusive control of the link to the other terminals 20. In this case, the base station 10 can improve the communication quality of the terminal 20 having LL traffic by changing the link setting of the other terminal 20.

[0124] <3> Third embodiment The wireless system 1 according to the third embodiment has the same configuration as that of the first embodiment. After establishing a multi-link, the wireless system 1 according to the third embodiment appropriately changes channels within the same frequency band. The following describes the differences between the wireless system 1 according to the third embodiment and the first and second embodiments.

[0125] <3-1> Operation of wireless system 1 <3-1-1> About channels Fig. 20 shows an example of frequency bands used for wireless communication in the wireless system 1 according to the third embodiment. As shown in Fig. 20, for example, the 2.4 GHz band, the 5 GHz band, and the 6 GHz band are used in wireless communication. Each frequency band includes multiple channels. In this example, it is assumed that the 2.4 GHz band, the 5 GHz band, and the 6 GHz band each include at least three channels CH1, CH2, and CH3. Communication using each channel CH is realized by an associated STA function.

[0126] <3-1-2> Channel change process First, an example of a condition for executing the channel change process will be described. Fig. 21 is a flowchart showing an example of an execution condition for the channel change process in the wireless system 1 according to the third embodiment. As shown in Fig. 21, first, the link management unit 120 monitors the interference status of the OBSS for each channel in the frequency band of the secondary link (step S70).

[0127] Then, the link management unit 120 checks whether the OBSS interference in the channel in use is greater than the OBSS interference in other channels (step S71). For example, the link management unit 120 checks whether the channel occupation time of the OBSS for the channel in use is greater than the channel occupation time for other channels. Note that interference evaluation may use something other than the channel occupation time, as long as it uses at least a factor that makes the channel busy during periods other than the exchange of signals in the own BSS. For example, interference evaluation may use the magnitude of interference power, interference from other communication systems, the presence of noise power, etc.

[0128] If the OBSS interference in the channel in use is greater than the OBSS interference in other channels (step S71, YES), the link management unit 120 executes a channel change (step S72). When the channel change is executed, the channel used in the secondary link is changed to another channel in the same frequency band.

[0129] If the OBSS interference in the channel being used is equal to or less than the OBSS interference in other channels (step S71, NO), or if the channel change in step S72 is completed, the link management unit 120 ends the series of processes related to the channel change process. The link management unit 120 may periodically perform the processes of steps S70 to S72 described above.

[0130] The channel change process may be performed as appropriate based on the results of continuous monitoring of the OBSS interference situation. Furthermore, the trigger for performing the channel change process is not limited to the OBSS interference situation. The channel change process may also be performed based on the signal strength of each link. In this case, the link management unit 120 checks, for example, whether the signal strength of the channel currently in use is weaker than the signal strength of other channels in the same frequency band. Furthermore, instead of the base station 10 directly monitoring the interference situation, the terminal 20 may monitor the interference situation and transmit the monitoring results to the base station 10. In this case, the base station 10 performs the channel change process using the monitoring results.

[0131] Next, a specific example of the channel change process will be described with reference to Fig. 22. Fig. 22 is a flowchart showing a specific example of the channel change process in the wireless system 1 according to the third embodiment. In the initial state of this example, a multi-link is set up using channel CH1 of STA1 and channel CH2 of STA2 in the link state shown in Fig. 9.

[0132] In this state, when data of TID#3 is transmitted from the access point AP to the terminal 20, the STA2 of the terminal 20 receives the data (step S80). Then, the STA2 of the terminal 20 transmits a wireless signal ("ACK") to the access point AP to notify that the data has been received (step S81).

[0133] 21 is satisfied, the link management unit 120 of the base station 10 transmits a radio signal requesting a channel change to the terminal 20 using the primary link (step S82). When STA1 of the terminal 20 receives the radio signal, the link management unit 220 of the terminal 20 checks whether a channel change is possible.

[0134] If the channel can be changed, the link management unit 220 transmits a positive response ("OK") to the access point AP via STA1 or STA2 (step S83). If the channel cannot be changed, the link management unit 220 of the terminal 20 transmits a negative response ("NO") to the access point AP via STA1 or STA2.

[0135] After the process of step S83, the link management unit 120 of the base station 10 and the link management unit 220 of the terminal 20 each change the 5 GHz channel used as the secondary link, for example, from "CH2" to "CH3" (step S84).

[0136] After the channel change in step S84 is executed, when data of TID#3 is transmitted from the access point AP to the terminal 20, the STA2 of the terminal 20, which has been changed to the 5 GHz channel CH3, receives the data (step S85). Then, the STA2 of the terminal 20 transmits a wireless signal ("ACK") to the access point AP notifying that the data has been received (step S86).

[0137] Fig. 23 shows an example of a change in link management information 121 due to the channel change process described in Fig. 22. As shown in Fig. 23, the channel ID corresponding to the secondary link among the multiple links constituting the multilink is changed by executing the channel change process.

[0138] Specifically, the channel of STA2, which is set as a secondary link and uses the 5 GHz frequency band, is changed from "CH2" to "CH3" by the channel change process. Note that the setting related to the association between traffic and TID information may be changed or maintained when the channel is changed.

[0139] Fig. 24 shows a specific example of a wireless frame used in the channel change process of the wireless system 1 according to the third embodiment. Fig. 24 corresponds to a wireless frame transmitted when the access point AP requests the terminal 20 to change the channel of the secondary link.

[0140] As shown in Fig. 24, the Frame Body of the wireless frame requesting a channel change process includes, for example, a terminal identifier AID, a channel change request, an identifier of the target secondary link, and a next channel ID. The link management unit 220 of the terminal 20 corresponding to the AID references the "identifier of the target secondary link" and the "next channel ID" based on the "channel change request" and determines whether or not it is possible to change the channel of the secondary link. Then, in response to the channel change request, for example, a wireless frame similar to that shown in Fig. 15 described in the first embodiment is used. Other operations of the wireless system 1 according to the third embodiment are similar to those of the first embodiment.

[0141] <3-2> Effects of the third embodiment In the first embodiment, the primary link is switched depending on the communication quality of different frequency bands. However, the communication quality may differ even between channels in the same frequency band. For example, the communication quality of the secondary link may vary depending on the channel being used, even in the same frequency band, due to factors such as the interference situation caused by OBSS and the strength of radio waves. For this reason, in the wireless system 1, when the primary link is used as the main line for data communication in a multi-link configuration, it may be preferable to switch the channel of the secondary link used as the sub-line.

[0142] Therefore, the wireless system 1 according to the third embodiment switches the channel used for the secondary link depending on the communication quality of each channel used in the multilink. For example, the link management unit 120 of the base station 10 monitors the interference status of each channel in the frequency band of the secondary link (e.g., 2.4 / 5 / 6 GHz band). Then, when the link management unit 120 detects that, for example, "OBSS interference in the channel in use > OBSS interference in other channels," the channel of the secondary link is switched to the channel with the least interference in the same frequency band.

[0143] As described above, in the wireless system 1 according to the third embodiment, the channel used in the secondary link is appropriately changed based on a predetermined condition, thereby maintaining high communication quality of the secondary link. As a result, the wireless system 1 according to the third embodiment can improve communication quality of the multi-link.

[0144] Note that, as the predetermined condition for executing the channel change process, any parameter related to the communication quality of each link can be used. Also, although the third embodiment illustrates the case where the channel of the secondary link is changed, the channel of the primary link may also be changed by the channel change process.

[0145] Furthermore, when a plurality of terminals 20 are connected to the base station 10, the base station 10 may collectively execute the channel change process for the plurality of terminals 20. In this case, the link management unit 120 of the base station 10 changes the channel of the secondary link when, for example, it receives positive responses from all of the terminals 20 that are targets for changing the channel.

[0146] <3-3> Modification of the third embodiment The wireless system 1 described in the third embodiment is merely an example, and various modifications are possible. A first modified example and a second modified example of the third embodiment will be described below in order.

[0147] <3-3-1> First modified example of the third embodiment The first modified example of the third embodiment is a combination of the third embodiment and the signaling in the second embodiment. Fig. 25 is a flowchart showing a specific example of channel change processing in the first modified example of the third embodiment. The flowchart shown in Fig. 25 has a configuration in which step S90 is added between steps S83 and S84 of the flowchart shown in Fig. 22.

[0148] Specifically, the access point AP instructs the terminal 20 to change the channel (step S82), and the terminal 20 transmits an acknowledgement to the access point AP (step S83). Then, the access point AP transmits to the terminal 20 a beacon signal including countdown information indicating the timing to change the channel of the secondary link (step S90). The illustrated "countdown #1 to n" corresponds to n counts of beacon signals that will be transmitted to the terminal 20 until the channel of the secondary link is changed.

[0149] When the countdown using the multiple beacon signals is completed, the link management unit 120 of the base station 10 and the link management unit 220 of the terminal 20 each change the channel of the secondary link (STA2), for example, from CH2 to CH3 (step S84). The other configurations and operations of the wireless system 1 according to the second modification of the third embodiment are the same as those of the third embodiment.

[0150] As described above, in the wireless system 1 according to the first modification of the third embodiment, countdown information is transmitted before the channel is changed. In other words, the access point AP executes signaling with the terminal 20 before switching the channel of the secondary link. This allows the link management unit 220 of the terminal 20 to know the timing of switching the channel based on the signaling, and ensures that the channel is switched reliably.

[0151] Furthermore, the channel change using signaling in the first modification of the third embodiment may be performed for multiple terminals 20 connected to the access point AP. By using signaling such as that in the first modification of the third embodiment, the access point AP can synchronize and switch the channels of multiple terminals 20 in the BSS. Such an operation is effective, for example, when establishing exclusive control of links as described in the effect of the second embodiment.

[0152] <3-3-2> Second modified example of the third embodiment The second modified example of the third embodiment is a combination of the third embodiment and the multilink power save of the second embodiment. Fig. 26 is a flowchart showing a specific example of a channel change process in the second modified example of the third embodiment. In the initial state of this example, a multilink is set by the channel CH1 of STA1 and the channel CH2 of STA2 with respect to the link state shown in Fig. 9, and STA1 and STA2 are set to an Awake state (active mode or intermittent operation mode) and a Doze state (operation pause mode), respectively.

[0153] When the link management unit 120 of the base station 10 detects that the predetermined conditions described in Fig. 21 have been satisfied, it transmits a radio signal requesting a channel change to the terminal 20 using the primary link (STA1) in the Awake state (step S100), as shown in Fig. 26. When STA1 of the terminal 20 receives the radio signal, the link management unit 220 of the terminal 20 checks whether or not it is possible to change the channel of the secondary link.

[0154] If the channel of the secondary link can be changed, the link management unit 220 of the terminal 20 transmits a positive response ("OK") to the access point AP via STA1 (step S101). If the channel of the secondary link cannot be changed, the link management unit 220 of the terminal 20 may transmit a negative response ("NO") to the access point AP via STA1, as in the third embodiment.

[0155] After the processing of step S101, each of the link management unit 120 of the base station 10 and the link management unit 220 of the terminal 20 changes the channel of the secondary link from CH2 to CH3 while the secondary link maintains the Doze state in the operation suspension mode (step S102).

[0156] Thereafter, when the link management unit 220 of the terminal 20 detects that the predetermined conditions as described in the second embodiment are satisfied, it transmits an Awake transition request signal to the access point AP using the primary link (STA1) (step S103). When the STA1 of the base station 10 receives the Awake transition request signal, the link management unit 120 of the base station 10 transmits an acknowledgment ("OK") to the terminal 20 using the primary link (step S104).

[0157] When terminal 20 receives the positive response in step S104, link management unit 220 of terminal 20 changes STA2, which is set as the secondary link, to active mode (step S105). At this time, link management unit 220 controls STA2 based on the setting changed by the processing of step S102. That is, STA2 of terminal 20 wakes up in a state where it can communicate using 5 GHz channel CH3.

[0158] That is, after the channel change is executed in step S105, when data of TID#3 is transmitted from the access point AP to the terminal 20, the STA2 of the terminal 20, which has changed to the 5 GHz channel CH3, receives the data (step S106). Then, the STA2 of the terminal 20 transmits a wireless signal ("ACK") notifying that the data has been received to the access point AP (step S107). The other configurations and operations of the wireless system 1 according to the second modification of the third embodiment are the same as those of the third embodiment.

[0159] As described above, in the second modification of the third embodiment, the channel change process is executed when the secondary link is in the dormant mode. If the access point AP arbitrarily changes the channel when the secondary link is in the dormant mode, there is a risk that the woken-up STA function will not operate on an appropriate channel. On the other hand, the access point AP in the second modification of the third embodiment notifies the terminal 20, using the primary link, that the channel of the secondary link will be changed.

[0160] As a result, the wireless system 1 according to the second modification of the third embodiment can reliably execute the channel change process for the secondary link when using the dormant mode. Then, the STA function that wakes up from the dormant mode can communicate on an appropriate channel by having the link management unit 220 confirm the correspondence between the STA function and the channel.

[0161] <4> others In the above embodiment, the case where the access point AP transmits data to the terminal 20 has been exemplified, but the terminal 20 may transmit data to the access point AP during multi-link. When the multi-link state is changed, the link management units 120 and 220 update the link management information 121 and 221, respectively. The link management units 120 and 220 may update the association between traffic and STA functions in accordance with an increase or decrease in the number of links.

[0162] In the above embodiment, the case where the terminal 20 requests the base station 10 to establish a multi-link in the multi-link processing has been exemplified, but the present invention is not limited to this. For example, the base station 10 may request the terminal 20 to establish a multi-link based on the establishment of multiple links between the base station 10 and the terminal 20.

[0163] In the above embodiment, the primary link and the secondary link are each set to the active mode after the multi-link process, but this is not limiting. When the multi-link is established, it is sufficient that at least the primary link is set to the active mode, and the secondary link may be set to either the active mode or the dormant mode. The secondary link may be switched between the dormant mode and the active mode based on a predetermined condition.

[0164] In the above embodiment, a case where a multi-link is established using STA functions of different frequency bands has been exemplified, but this is not limiting. A multi-link may be established between the base station 10 and the terminal 20 using multiple channels CH included in the same frequency band. For example, multiple STA functions may configure a multi-link using different channels in the 5 GHz band. Even in such a case, the primary change process described in the first and second embodiments and the channel change process described in the third embodiment may be executed.

[0165] The configuration of the wireless system 1 according to the embodiment is merely an example, and other configurations are also possible. For example, although the base station 10 and the terminal 20 each have three STA functions (wireless signal processing units), the present invention is not limited to this. The base station 10 only needs to have at least two wireless signal processing units. Similarly, the terminal 20 only needs to have at least two wireless signal processing units. The number of channels that each STA function can process can be set appropriately depending on the frequency band used. Each of the wireless communication modules 14 and 24 may support wireless communication in multiple frequency bands using multiple communication modules, or may support wireless communication in multiple frequency bands using a single communication module.

[0166] Furthermore, the functional configurations of the base station 10 and the terminal 20 in the wireless system 1 according to the embodiment are merely examples. The functional configurations of the base station 10 and the terminal 20 may be named and grouped differently as long as they are capable of performing the operations described in each embodiment. For example, in the base station 10, the data processing unit 110 and the link management unit 120 may be collectively referred to as a data processing unit. Similarly, in the terminal 20, the data processing unit 210 and the link management unit 220 may be collectively referred to as a data processing unit.

[0167] Furthermore, in the wireless system 1 according to the embodiment, the CPU included in each of the base station 10 and the terminal 20 may be other circuits. For example, an MPU (Micro Processing Unit) or the like may be used instead of a CPU. Furthermore, each of the processes described in each embodiment may be realized by dedicated hardware. The wireless system 1 according to each embodiment may include a mixture of processes executed by software and processes executed by hardware, or may include only one of them.

[0168] In each embodiment, the flowcharts used to explain the operations are merely examples. The order of the operations explained in the embodiments may be changed as far as possible, and other processes may be added. Furthermore, the radio frame formats explained in the above embodiments are merely examples. The radio system 1 may use other radio frame formats as long as they are capable of executing the operations explained in each embodiment.

[0169] 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. [Explanation of symbols]

[0170] 1...Radio system 10...Base station 20...Terminal 30...Server 11,21...CPU 12,22…ROM 13,23…RAM 14,24...Wireless communication module 15...Wired communication module 25…Display 26…Storage 110, 210...Data processing unit 120,220...Link Management Department 121,221...Link management information 122,222… 123,223… 124...Data Categorization Department 125...Transmission queue 126...CSMA / CA execution unit 127...Data collision management unit 130, 140, 150, 230, 240, 250...Radio signal processing unit

Claims

1. a first radio signal processing unit configured to be able to transmit and receive radio signals using a first channel; a second radio signal processing unit configured to be able to transmit and receive radio signals using a second channel different from the first channel; a link management unit that establishes a multi-link with a terminal using the first radio signal processing unit and the second radio signal processing unit, and sets a primary link to be used as a main link in the multi-link, and a secondary link to be used as an auxiliary link; a base station, wherein the link management unit has a first mode in which radio signals are exchanged using only a primary link, and a second mode in which radio signals are exchanged using the primary link and a secondary link, and switches between the first mode and the second mode depending on the traffic status associated with the multi-link.

2. a first radio signal processing unit configured to be able to transmit and receive radio signals using a first channel; a second radio signal processing unit configured to be able to transmit and receive radio signals using a second channel different from the first channel; a link management unit that establishes a multi-link with a terminal using the first radio signal processing unit and the second radio signal processing unit, and sets a primary link to be used as a main link in the multi-link, and a secondary link to be used as an auxiliary link; The link management unit Using the first radio signal processing unit set for the primary link, transmit a first radio frame requesting a change of the primary link to the terminal; a base station that, after the first radio frame is transmitted, changes a primary link from the first radio signal processing unit to the second radio signal processing unit when either the first radio signal processing unit or the second radio signal processing unit receives an acknowledgment from the terminal.

3. The link management unit When the first radio signal processing unit and the second radio signal processing unit are set to a primary link and a secondary link, respectively, and the second radio signal processing unit is set to an operation hibernation mode, transmitting a second radio frame to the terminal using the first radio signal processing unit, the second radio frame requesting switching between the primary link and the secondary link; When either the first radio signal processing unit or the second radio signal processing unit receives the acknowledgment, the second radio signal processing unit is set to an active mode and a primary link, and the first radio signal processing unit is set to a dormant mode and a secondary link. The base station of claim 2.

4. before changing the primary link based on the acknowledgement, the link management unit uses at least one of the first radio signal processing unit and the second radio signal processing unit to transmit to the terminal a plurality of beacon signals notifying a countdown of the change of the primary link; The base station according to claim 2 or claim 3.

5. a first radio signal processing unit configured to be able to transmit and receive radio signals using a first channel; a second radio signal processing unit configured to be able to transmit and receive radio signals using a second channel different from the first channel; a link management unit that establishes a multi-link with a terminal using the first radio signal processing unit and the second radio signal processing unit, and sets a primary link that mainly uses the multi-link and a secondary link that uses the multi-link as an auxiliary link; The link management unit Using the first radio signal processing unit set to the primary link, transmit a first radio frame to the terminal requesting a change of the channel of the second radio signal processing unit; a base station that, when either the first radio signal processing unit or the second radio signal processing unit receives an acknowledgment from the terminal after the first radio frame is transmitted, changes the channel of the second radio signal processing unit from the second channel to a third channel different from each of the first channel and the second channel.

6. The link management unit When the first radio signal processing unit and the second radio signal processing unit are set to a primary link and a secondary link, respectively, and the second radio signal processing unit is set to an operation hibernation mode, transmitting a second radio frame to the terminal using the first radio signal processing unit, the second radio frame requesting a change of a channel of the secondary link; When either the first radio signal processing unit or the second radio signal processing unit receives the acknowledgment, the channel of the second radio signal processing unit is changed to the third channel while being maintained in a dormant mode; causing the second radio signal processor to communicate using the third channel after the change is applied and the second radio signal processor wakes up from the dormant mode to the active mode. The base station of claim 5.

7. the link management unit, before changing the channel of the second radio signal processing unit based on the acknowledgement, uses at least one of the first radio signal processing unit and the second radio signal processing unit to transmit a plurality of beacon signals notifying the terminal of a countdown of the channel change; The base station according to claim 5 or claim 6.

8. a first radio signal processing unit configured to be able to transmit and receive radio signals using a first channel; a second radio signal processing unit configured to be able to transmit and receive radio signals using a second channel different from the first channel; a link management unit that establishes a multi-link with a terminal using the first radio signal processing unit and the second radio signal processing unit, and sets a primary link to be used as a main link in the multi-link, and a secondary link to be used as an auxiliary link; The link management unit has a first mode in which wireless signals are exchanged using only a primary link, and a second mode in which wireless signals are exchanged using the primary link and a secondary link, and switches between the first mode and the second mode depending on the traffic status associated with the multi-link.

9. a first radio signal processing unit configured to be able to transmit and receive radio signals using a first channel; a second radio signal processing unit configured to be able to transmit and receive radio signals using a second channel different from the first channel; a link management unit that establishes a multi-link with a base station using the first radio signal processing unit and the second radio signal processing unit, and sets a primary link to be used as a main link in the multi-link, and a secondary link to be used as an auxiliary link; When the first radio signal processing unit set to the primary link receives a first radio frame from the base station requesting a change of the primary link, the link management unit notifies the base station whether or not the primary link can be changed using either the first radio signal processing unit or the second radio signal processing unit, and if the notification is a positive response, changes the primary link from the first radio signal processing unit to the second radio signal processing unit.

10. When the first radio signal processing unit and the second radio signal processing unit are set to a primary link and a secondary link, respectively, and the second radio signal processing unit is set to an operation suspension mode, if the first radio signal processing unit receives a second radio frame requesting switching between the primary link and the secondary link from the base station, the link management unit causes either the first radio signal processing unit or the second radio signal processing unit to transmit the acknowledgment, and then sets the second radio signal processing unit to an active mode and a primary link, and sets the first radio signal processing unit to a secondary link and an operation suspension mode. The terminal according to claim 9.

11. the link management unit changes the primary link from the first radio signal processing unit to the second radio signal processing unit based on the fact that at least one of the first radio signal processing unit and the second radio signal processing unit has received, from the base station, a plurality of beacon signals notifying a countdown of a change of the primary link, after the first radio signal processing unit and the second radio signal processing unit have transmitted the acknowledgment; The terminal according to claim 9 or 10.

12. a first radio signal processing unit configured to be able to transmit and receive radio signals using a first channel; a second radio signal processing unit configured to be able to transmit and receive radio signals using a second channel different from the first channel; a link management unit that establishes a multi-link with a base station using the first radio signal processing unit and the second radio signal processing unit, and sets a primary link to be used as a main link in the multi-link, and a secondary link to be used as an auxiliary link; When the first radio signal processing unit set to the primary link receives a first radio frame from the base station requesting a change of the channel of the second radio signal processing unit, the link management unit notifies the base station whether or not the channel can be changed using either the first radio signal processing unit or the second radio signal processing unit, and if the notification is a positive response, changes the channel of the second radio signal processing unit from the second channel to a third channel different from both the first channel and the second channel.

13. When the first radio signal processing unit and the second radio signal processing unit are set to a primary link and a secondary link, respectively, and the second radio signal processing unit is set to an operation suspension mode, if the first radio signal processing unit receives a second radio frame requesting a change of the channel of the secondary link from the base station, the link management unit transmits the acknowledgement using the first radio signal processing unit, changes the channel of the second radio signal processing unit to the third channel while maintaining the channel in a dormant mode, and causes the second radio signal processing unit to communicate using the third channel after the change is applied and the second radio signal processing unit wakes up from the dormant mode to an active mode. The terminal according to claim 12.

14. the link management unit changes the channel of the second radio signal processing unit from the second channel to the third channel based on the fact that at least one of the first radio signal processing unit and the second radio signal processing unit has received, from the base station, a plurality of beacon signals notifying a countdown of a channel change, after the first radio signal processing unit and the second radio signal processing unit have transmitted the acknowledgment; A terminal according to claim 12 or claim 13.

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