Base station and terminal

Abstract

To provide a base station and a terminal that improve the communication quality of multi-links in a wireless LAN.SOLUTION: In a wireless system, a base station includes a first wireless signal processing unit that uses a first channel, a second wireless signal processing unit that uses a different second channel, and a processing unit that sets an anchor link to be used for intermittent transmission of control information. The processing unit transmits a beacon frame including information on a link configured by the first wireless signal processing unit and information on a link configured by the second wireless signal processing unit to a terminal using the first wireless signal processing unit set to the anchor link, and does not transmit a beacon frame using the second wireless signal processing unit. When the anchor link setting is changed from the first wireless signal processing unit to the second wireless signal processing unit, the processing unit notifies the terminal of the change in the anchor link setting, and then transmits a beacon frame using the second wireless signal processing unit.SELECTED DRAWING: Figure 15

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 for wirelessly connecting a base station and terminals. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] IEEE Std 802.11-2016, “9.3.3.3 Beacon frame format” and “11.1 Synchronization”, 7 December 2016 Summary of the Invention [Problem to be solved by the invention]

[0004] The challenge is to improve the quality of multi-link communications. [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 an anchor link used for transmitting and receiving control information related to the operation of the multilink. The link management unit transmits a first radio frame requesting a change of the anchor link to the terminal using the first radio signal processing unit set to the anchor 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 anchor link from the first radio signal processing unit to the second radio signal processing unit. Effect of the Invention

[0006] The base station according to the embodiment can improve the communication quality of multi-links. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a conceptual diagram showing an example of an overall configuration of a wireless system according to an embodiment. [Diagram 2] FIG. 2 is a conceptual diagram showing an example of frequency bands used for wireless communication in the wireless system according to the embodiment. [Diagram 3] FIG. 3 is a conceptual diagram showing an example of a format of a radio frame in the wireless system according to the embodiment. [Figure 4] FIG. 4 is a block diagram showing an example of a configuration of a base station included in the wireless system according to the embodiment. [Diagram 5] FIG. 5 is a block diagram showing an example of functions of a base station included in the wireless system according to the embodiment. [Figure 6] FIG. 6 is a block diagram showing an example of a configuration of a terminal included in the wireless system according to the embodiment. [Figure 7] FIG. 7 is a block diagram showing an example of functions of a terminal included in the wireless system according to the embodiment. [Figure 8] FIG. 8 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 embodiment. [Figure 9] FIG. 9 is a table showing an example of link management information in the wireless system according to the embodiment. [Figure 10] FIG. 10 is a flowchart showing an example of multi-link processing in the wireless system according to the embodiment. [Figure 11] FIG. 11 is a conceptual diagram showing an example of a method for outputting a beacon signal in a base station included in a wireless system according to the embodiment. [Figure 12] FIG. 12 is a conceptual diagram showing an example of a beacon signal including multilink capability information in the wireless system according to the embodiment. [Figure 13] FIG. 13 is a flowchart showing an example of a data transmission method in multi-link mode in the wireless system according to the embodiment. [Figure 14] FIG. 14 is a flowchart showing an example of an execution condition for the anchor link change process in the wireless system according to the embodiment. [Figure 15] FIG. 15 is a flowchart showing a specific example of the anchor link change process in the wireless system according to the embodiment. [Figure 16] FIG. 16 is a conceptual diagram showing a specific example of a wireless frame used in the anchor link changing process of the wireless system according to the embodiment. [Figure 17] FIG. 17 is a conceptual diagram showing a specific example of a wireless frame used in the anchor link changing process of the wireless system according to the embodiment. [Figure 18] FIG. 18 is a conceptual diagram showing an example of a method for acquiring a communication quality measurement result by a base station included in the wireless system according to the embodiment. [Figure 19] FIG. 19 is a conceptual diagram showing an example of a method for acquiring a communication quality measurement result by a base station included in a wireless system according to an embodiment. [Figure 20] FIG. 20 is a flowchart showing an example of a method for acquiring a communication quality measurement result by a base station included in the wireless system according to the embodiment. [Figure 21] FIG. 21 is a conceptual diagram showing an example of a method of notifying a communication quality measurement result by a terminal included in a wireless system according to an embodiment. [Figure 22] FIG. 22 is a conceptual diagram showing an example of a method of notifying a communication quality measurement result by a terminal included in the wireless system according to the embodiment. [Diagram 23] FIG. 23 is a flowchart showing an example of a method for notifying a communication quality measurement result by a terminal included in the wireless system according to the embodiment. [Figure 24] FIG. 24 is a conceptual diagram illustrating an example of an overall configuration of a wireless system according to a modification of the embodiment. [Diagram 25] FIG. 25 is a table showing combinations of link sets of multilinks and anchor link settings used in a wireless system according to a modified embodiment. [Figure 26] FIG. 26 is a table illustrating an example of link management information in a wireless system according to a first modified example of the embodiment. [Figure 27] FIG. 27 is a flowchart showing a specific example of an anchor link change process in a wireless system according to a first modified example of the embodiment. [Figure 28] FIG. 28 is a table illustrating an example of link management information in a wireless system according to a second modification of the embodiment. [Figure 29] FIG. 29 is a flowchart illustrating a first example of multi-link processing in a wireless system according to a second modification of the embodiment. [Diagram 30] FIG. 30 is a flowchart illustrating a second example of the multilink process in the wireless system according to the second modification of the embodiment. [Diagram 31] FIG. 31 is a table illustrating an example of link management information in a wireless system according to a third modification of the embodiment. [Diagram 32]FIG. 32 is a conceptual diagram showing an example of a method for outputting a beacon signal in a base station included in a wireless system according to a third modification of the embodiment. [Diagram 33] FIG. 33 is a table illustrating an example of link management information in a wireless system according to a fourth modification of the embodiment. [Diagram 34] FIG. 34 is a flowchart illustrating an example of an anchor link change process in a wireless system according to the fourth modification of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A wireless system 1 according to an embodiment will be described below with reference to the drawings. The embodiment illustrates an apparatus and a method for embodying the technical idea of ​​the invention. The drawings are schematic or conceptual. The dimensions and ratios of each drawing are not necessarily the same as those in reality. The technical idea of ​​the present invention is not specified by the shape, structure, arrangement, etc. of the components. In the following description, the same reference numerals are used for components having substantially the same functions and configurations.

[0009] <1> Wireless System 1 Configuration <1-1> Overall configuration of wireless system 1 1 shows an example of a configuration of a wireless system 1 according to an embodiment. As shown in FIG. 1, the wireless system 1 includes a base station 10, a terminal 20, and a server 30, for example.

[0010] The base station 10 is connected to the 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 between the base station 10 and the terminal 20 using multiple types of bands is called a "multi-link." The communication between the base station 10 and the terminal 20 is based on, for example, the IEEE 802.11 standard.

[0011] 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 connected wirelessly. The terminal 20 may 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 execute the operations described below.

[0012] The server 30 can hold various information, for example, data of content targeted 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. Note that it is sufficient for the server 30 to be able to communicate with at least the base station 10. In other words, the communication between the base station 10 and the server 30 may be wired or wireless.

[0013] In the wireless system 1 according to the 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).

[0014] The data link layer includes, for example, an LLC (Logical Link Control) layer and a MAC (Media Access Control) layer. The LLC layer adds, for example, a DSAP (Destination Service Access Point) header and an SSAP (Source Service Access Point) header to data input from an upper application to form an LLC packet. The MAC layer adds, for example, a MAC header to an LLC packet to form a MAC frame.

[0015] (Frequency bands used for wireless communication) Fig. 2 shows an example of frequency bands used for wireless communication in the wireless system 1 according to the embodiment. As shown in Fig. 2, for example, the 2.4 GHz band, the 5 GHz band, and the 6 GHz band are used in the wireless communication. Each frequency band includes a plurality of channels. In this example, 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 the STA function described later.

[0016] The wireless system 1 may use a frequency band other than the 2.4 GHz band, the 5 GHz band, and the 6 GHz band for wireless communication. At least one channel CH may be set in each frequency band. For multilink, channels CH of the same frequency band may be used, or channels CH of different frequency bands may be used.

[0017] (Radio frame format) Fig. 3 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 embodiment. As shown in Fig. 3, fields included in the wireless frame include, 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. Some of these fields are included, and some are not, depending on the type of wireless frame.

[0018] 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.

[0019] The Frame Control field indicates various control information, and includes, 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.

[0020] The contents of a wireless frame change depending on the combination of 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 in the same IBSS (Independent Basic Service Set). "10" indicates that the data frame is directed to the DS (Distribution System) from outside. "01" indicates that the data frame is directed outside the DS. "11" is used when configuring a mesh network.

[0021] The Duration field indicates the planned period for using the wireless link. The multiple Address fields indicate the BSSID, source address, destination address, sender terminal address, receiver terminal address, etc. The Sequence Control field indicates the sequence number of the MAC frame and the fragment number for fragmentation. Other control information fields include, for example, traffic type (TID) information. The TID information may be inserted at other positions within the wireless frame. The Frame Body field includes information according to the type of frame. For example, the Frame Body field stores data when it corresponds to a data frame.

[0022] <1-2> Configuration of base station 10 Fig. 4 shows an example of the configuration of a base station 10 included in the wireless system 1 according to the embodiment. As shown in Fig. 4, the base station 10 includes, for example, a central processing unit (CPU) 11, a read only memory (ROM) 12, a random access memory (RAM) 13, a wireless communication module 14, and a wired communication module 15.

[0023] 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 holds 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 working area for the CPU 11. The wireless communication module 14 is a circuit used for transmitting and receiving data by wireless signals and is connected to an antenna. The wireless communication module 14 also includes, for example, a plurality of communication modules each corresponding to a plurality of frequency bands. The wired communication module 15 is a circuit used for transmitting and receiving data by wired signals and is connected to a network NW.

[0024] Fig. 5 shows an example of a functional configuration of the base station 10 included in the wireless system 1 according to the embodiment. As shown in Fig. 5, the base station 10 includes, for example, a data processing unit 100, a MAC frame processing unit 110, a management unit 120, and wireless signal processing units 130, 140, and 150. The processing of the data processing unit 100, the MAC frame processing unit 110, the management unit 120, and the wireless signal processing units 130, 140, and 150 is realized by, for example, a CPU 11 and a wireless communication module 14.

[0025] The data processing unit 100 can execute LLC layer processing and upper layer processing for the input data. For example, the data processing unit 100 outputs data input from the server 30 via the network NW to the MAC frame processing unit 110. In addition, the data processing unit 100 transmits data input from the MAC frame processing unit 110 to the server 30 via the network NW.

[0026] The MAC frame processing unit 110 executes, for example, a part of the MAC layer processing on the input data. For example, the MAC frame processing unit 110 generates a MAC frame from the data input from the data processing unit 100. The MAC frame generating unit 110 also restores data from the MAC frames input from each of the wireless signal processing units 130, 140, and 150. The process of generating a MAC frame from data and the process of restoring data from a MAC frame are based on, for example, the IEEE 802.11 standard.

[0027] The management unit 120 manages the link with the terminal 20 based on the notification received from the wireless signal processing units 130, 140, and 150 via the MAC frame processing unit 110. The 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 wirelessly connected to the base station 10. The management unit 120 also includes an association processing unit 122, an authentication processing unit 123, and a quality measurement unit 124. When the association processing unit 122 receives a connection request from the terminal 20 via any of the wireless signal processing units 130, 140, and 150, it executes a protocol related to association. Following the connection request, the authentication processing unit 123 executes a protocol related to authentication. The quality measurement unit 124 periodically measures and evaluates the communication quality of each channel. The quality measurement unit 124 also periodically requests the terminal 20 to measure and report the communication quality. Hereinafter, the set of the data processing unit 100, the MAC frame processing unit 110, and the management unit 120 will be referred to as a link management unit LM1 of the base station 10.

[0028] 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 creates a radio frame by adding a preamble, a PHY header, and the like to the data input from the MAC frame processing unit 110. 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 data (e.g., a MAC frame) included in the radio frame to the MAC frame processing unit 110.

[0029] In this way, each of the radio signal processing units 130, 140, and 150 may execute, for example, part of the MAC layer processing and the first layer processing on the input data or radio signal. 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.

[0030] <1-3> Configuration of terminal 20 Fig. 6 shows an example of the configuration of the terminal 20 included in the wireless system 1 according to the embodiment. As shown in Fig. 6, 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.

[0031] 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 holds programs and control data for controlling the terminal 20. The RAM 23 is, for example, a volatile semiconductor memory and is used as a working area for the CPU 21. The wireless communication module 24 is a circuit used for transmitting and receiving data by wireless signals and is connected to an antenna. The wireless communication module 24 also includes a plurality of communication modules corresponding to, for example, a plurality of frequency bands. The display 25 displays, for example, a GUI (Graphical User Interface) corresponding to application software. The display 25 may have a function as an input interface for the terminal 20. The storage 26 is a non-volatile storage device and holds, for example, system software of the terminal 20. The terminal 20 may not have a display. For example, the display 25 may be omitted in an IoT terminal.

[0032] Fig. 7 shows an example of a functional configuration of the terminal 20 included in the wireless system 1 according to the embodiment. As shown in Fig. 7, the terminal 20 includes, for example, a data processing unit 200, a MAC frame processing unit 210, a management unit 220, wireless signal processing units 230, 240, and 250, and an application execution unit 260. The processing of the data processing unit 200, the MAC frame processing unit 210, the management unit 220, and the wireless signal processing units 230, 240, and 250 is realized, for example, by the CPU 21 and the wireless communication module 24. The processing of the application execution unit 260 is realized, for example, by the CPU 21.

[0033] The data processing unit 200 can execute LLC layer processing and upper layer (layer 3 to layer 7) processing on the input data. For example, the data processing unit 200 outputs data input from the application execution unit 260 to the MAC frame processing unit 210. The data processing unit 200 also outputs data input from the MAC frame processing unit 210 to the application execution unit 260.

[0034] The MAC frame processing unit 210 executes, for example, a part of the MAC layer processing on the input data. For example, the MAC frame processing unit 210 generates a MAC frame from the data input from the data processing unit 200. The MAC frame processing unit 210 also restores data from the MAC frames input from each of the wireless signal processing units 230, 240, and 250. The process of generating a MAC frame from data and the process of restoring data from a MAC frame are based on, for example, the IEEE 802.11 standard.

[0035] The management unit 220 manages the link with the base station 10 based on notifications received from the wireless signal processing units 230, 240, and 250 via the MAC frame processing unit 210. The 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 management unit 220 also includes an association processing unit 222, an authentication processing unit 223, and a quality measurement unit 224. When the association processing unit 222 receives a connection response from the base station 10 via any of the wireless signal processing units 230, 240, and 250, it executes a protocol related to association. Following the connection response, the authentication processing unit 223 executes a protocol related to authentication. The quality measurement unit 224 periodically measures and evaluates the communication quality of each channel. Furthermore, in response to a request for measuring and notifying communication quality received from the base station 10, the quality measurement unit 224 measures communication quality using each STA function and notifies the base station 10 of the measurement result. In the following, the set of the data processing unit 200, the MAC frame processing unit 210, and the management unit 220 is referred to as a link management unit LM2 of the terminal 20.

[0036] 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 creates a radio frame by adding a preamble, a PHY header, and the like to the data input from the MAC frame processing unit 210. 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 data (e.g., a MAC frame) included in the radio frame to the MAC frame processing unit 210.

[0037] In this way, each of the radio signal processing units 230, 240, and 250 may execute, for example, part of the MAC layer processing and the first layer processing on the input data or radio signal. 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.

[0038] The application execution unit 260 executes an application capable of using 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. In addition, the application execution unit 260 can operate based on an operation of an input interface.

[0039] In the wireless system 1 according to the 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 a "STA function". That is, the wireless system 1 according to the embodiment has multiple STA functions.

[0040] <1-4> About the Link Management Unit LM1 Fig. 8 shows details of a channel access function in the link management unit LM1 of the base station 10 included in the wireless system 1 according to the embodiment. Note that the function of the link management unit LM2 of the terminal 20 is similar to that of the link management unit LM1 of the base station 10, for example, and therefore a description thereof will be omitted. As shown in Fig. 8, the link management unit LM1 includes, for example, a data categorization unit 125, transmission queues 126A, 126B, 126C, 126D, and 126E, CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) execution units 127A, 127B, 127C, 127D, and 127E, and a data collision management unit 128.

[0041] The data categorization unit 125 categorizes the data input from the data processing unit 100. For example, "LL (Low Latency)", "VO (Voice)", "VI (Video)", "BE (Best Effort)", and "BK (Background)" are set as data categories. LL is applied to data that requires low latency. For this reason, it is preferable that LL data is processed with priority over any of VO, VI, BE, and BK data.

[0042] Then, the data categorization unit 125 inputs the categorized data to one of the transmission queues 126A, 126B, 126C, 126D, and 126E. Specifically, LL data is input to the transmission queue 126A. VO data is input to the transmission queue 126B. VI data is input to the transmission queue 126C. BE data is input to the transmission queue 126D. BK data is input to the transmission queue 126E. The input data of each category is then stored in one of the corresponding transmission queues 126A to E.

[0043] Each of the CSMA / CA executing units 127A, 127B, 127C, 127D, and 127E waits for transmission for a time specified by a preset access parameter while confirming that no wireless signal is being transmitted by other terminals, etc., by carrier sense in CSMA / CA. Then, the CSMA / CA executing units 127A, 127B, 127C, 127D, and 127E extract data from the transmission queues 126A, 126B, 126C, 126D, and 126E, respectively, and outputs the extracted data to at least one of the wireless signal processing units 130, 140, and 150 via the data collision management unit 128. Then, the wireless signal including the data is transmitted by the wireless signal processing unit (STA function) that has acquired the transmission right by CSMA / CA.

[0044] The CSMA / CA execution unit 127A performs CSMA / CA on the LL data held in the transmission queue 126A. The CSMA / CA execution unit 127B performs CSMA / CA on the VO data held in the transmission queue 126B. The CSMA / CA execution unit 127C performs CSMA / CA on the VI data held in the transmission queue 126C. The CSMA / CA execution unit 127D performs CSMA / CA on the BE data held in the transmission queue 126D. The CSMA / CA execution unit 127E performs CSMA / CA on the BK data held in the transmission queue 126E.

[0045] The access parameters are assigned in the order of, for example, LL, VO, VI, BE, and BK so that the transmission of the wireless signal is prioritized. The access parameters include, for example, CWmin, CWmax, AIFS, and TXOPLimit. CWmin and CWmax indicate the minimum and maximum values ​​of a contention window, which is a transmission waiting time for collision avoidance, respectively. 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 an upper limit value of TXOP (Transmission Opportunity) corresponding to the channel occupancy time. For example, the shorter the CWmin and CWmax are, the easier it is for the transmission queue 126 to obtain the transmission right. The smaller the AIFS is, the higher the priority of the transmission queue 126 is. The larger the value of TXOPLimit is, the larger the amount of data transmitted with one transmission right is.

[0046] The data collision management unit 128 prevents data collision when a plurality of CSMA / CA execution units 127 acquire the transmission right by the same STA function. Specifically, the data collision management unit 128 adjusts the transmission timing of data that is in different categories and has acquired the transmission right by the same STA function, and transmits data of the category with the highest priority to the STA function. For example, a STA function that has acquired the transmission right by CSMA / CA of the LL transmission queue 126A may acquire the transmission right at the same time as a STA function that has acquired the transmission right by CSMA / CA of any of the other transmission queues 126B to 126E. In this case, the data collision management unit 128 transmits the data stored in the transmission queue 126A to the STA function with priority. In the same manner, in the combination of the other transmission queues 126, data is transmitted in the order based on the priority set in the category. This prevents collision between data that is assigned to the same STA function for transmission.

[0047] In the embodiment, the link management units LM1 and LM2 implement the channel access function, but each STA function may implement the channel access function. When the link management units LM1 and LM2 implement the channel access function, each STA function detects the state (idle / busy) of the wireless channel in the corresponding link, and the link management units LM1 and LM2 judge 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 may independently perform carrier sense and transmit data. In this case, channel access when multiple links are used simultaneously may be performed by commonizing access parameters through communication between the multiple STA functions, or may be performed by commonizing access parameters by the link management units LM1 and LM2. The base station 10 and the terminal 20 can use multiple links simultaneously by transmitting data based on access parameters common between the multiple STA functions.

[0048] <1-5> About link management information 121 Fig. 9 shows an example of link management information 121 in the wireless system 1 according to the embodiment. Note that the link management information 221 of the terminal 20 has 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 includes information on, for example, the STA function, frequency band, channel ID, link destination ID, multilink, and TID.

[0049] In this example, "STA1" corresponds to an STA function using the 6 GHz frequency band, i.e., the wireless signal processing unit 150 or 250. "STA2" corresponds to an STA function using the 5 GHz frequency band, i.e., the wireless signal processing unit 140 or 240. "STA3" corresponds to an STA function using the 2.4 GHz frequency band, i.e., the wireless signal processing unit 130 or 230. Hereinafter, STA1, STA2, and STA3 are also referred to as link #1, link #2, and link #3, respectively.

[0050] The channel ID corresponds to the identifier of the channel used in the set frequency band. 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 is established using STA1, STA2, and STA3. When a multi-link is established, each of the link management units LM1 and LM2 transmits data input from an upper layer using a link of at least one STA function associated with the multi-link.

[0051] The base station 10 sets one of the multiple STA functions as an anchor link. In this example, STA1 is set as the anchor link. The anchor link is set by a link management unit LM1 of the base station 10. The anchor link transmits and receives control information related to the operation of the multilink in addition to transmitting and receiving assigned data. Note that the combination of links constituting the multilink may be different between multiple terminals 20 each of which has established a multilink with the base station 10.

[0052] "TID" in link management information 121 indicates the association between a STA function and TID information. Each STA function transmits and receives data corresponding to the assigned TID information. For example, each of TID#1-4 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. In this example, TID#1 is assigned to both STA1 and STA2. TID#2 is assigned to STA1. TID#3 is assigned to STA2. TID#4 is assigned to STA3.

[0053] A traffic flow corresponding to such an association between traffic and STA functions is set in advance when a multilink is set up between the base station 10 and the terminal 20. For example, the link management unit LM2 of the terminal 20 determines the association between traffic and STA functions and requests the link management unit LM1 of the base station 10. Then, the base station 10 responds to the request, thereby determining the association between traffic and STA functions.

[0054] In addition, the traffic is set to be equal among the multiple links constituting the multilink, for example. Not limited to this, traffic of similar types (priority / non-priority, etc.) may be collected in one of the links constituting the multilink. In addition, as an association between the STA function and the 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 that the frequency used for transmission and reception is assigned according to the type of information to be handled and the data capacity.

[0055] <2> Operation of Radio System 1 An example of various operations related to the multilink of the wireless system 1 according to the embodiment will be described below. In the following description, for simplicity, the STA1, STA2, and STA3 of the base station 10 are also called the "access point AP." The transmission of wireless signals by the STA1, STA2, and STA3 of the terminal 20 to the access point AP corresponds to the transmission of wireless signals to the STA1, STA2, and STA3 of the base station 10, respectively. When STA1, STA2, and STA3 are described individually, they indicate the STA function of the terminal 20.

[0056] <2-1> Multi-link processing Fig. 10 shows an example of a flow of multi-link processing in the wireless system 1 according to the embodiment. As shown in Fig. 10, in the multi-link processing, for example, the processing of steps S10 to S16 is executed in order. The processing of steps S10 to S16 will be described below taking as an example a case where a multi-link is formed using the functions of three STAs.

[0057] In the process of step S10, the terminal 20 transmits a probe request to the base station 10. The probe request is a signal for confirming whether or not a base station 10 exists 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.

[0058] 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 response, the terminal 20 executes the process of step S12.

[0059] 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 LM2 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 LM1 of the base station 10 executes the process of step S13.

[0060] In the process of step S13, the link management unit LM1 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 the first STA function with the terminal 20. Then, when a wireless connection (link) is established in the first STA function, the link management unit LM1 of the base station 10 executes an association process of the second STA function and an association process of the third 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 for 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.

[0061] In the process of step S14, the link management unit LM1 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 state is updated, or may be updated when a multi-link is established. When a multi-link is established and the link management information is updated, the base station 10 executes the process of step S15.

[0062] 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 LM2 of the terminal 20 recognizes that a multi-link with the base station 10 has been established. Upon receiving the multi-link establishment response, the terminal 20 executes the process of step S16.

[0063] In the process of step S16, the link management unit LM2 of the terminal 20 updates the link management information 221. That is, the terminal 20 records in the link management information 221 that a multi-link with the base station 10 has been established. This completes the multi-link process in the wireless system 1 according to the embodiment, and data communication using the multi-link becomes possible between the base station 10 and the terminal 20.

[0064] In addition, the wireless system 1 according to the embodiment may establish a multi-link when establishing a link in the first STA function. In this case, the terminal 20 receives a beacon signal related to the multi-link from the base station 10 before the multi-link association request in step S12. This operation will be described below with reference to Figs. 11 and 12.

[0065] Fig. 11 shows an example of a method for outputting a beacon signal in the base station 10 included in the wireless system 1 according to the embodiment. In this example, link #1 of links #1 to #3 is set as an anchor link. As shown in Fig. 11, the base station 10 transmits a beacon signal intermittently using link #1 set as an anchor link. Meanwhile, transmission of beacon signals through links #2 and #3, which are not set as anchor links, is omitted. The beacon signal may be transmitted using a link that is not set as an anchor link, and it is sufficient that the beacon signal is transmitted using at least the anchor link.

[0066] Fig. 12 shows a specific example of a beacon signal including multilink capability information in the wireless system 1 according to the embodiment. As shown in Fig. 12, the beacon signal includes, for example, multilink capability information, operation information of link #1, operation information of link #2, and operation information of link #3. These pieces of information are generated by the link management unit LM1 of the base station 10.

[0067] The multilink capability information indicates whether the base station 10 is capable of multilink. For example, when the multilink capability information is "0", it indicates that multilink is not possible. When the multilink capability information is "1", it indicates that multilink is possible. The link operational information (operational parameters) indicates parameters for performing data transmission, etc. in links that can be used in multilink. For example, the operational information of link #1 indicates access parameters, etc. of EDCA (Enhanced Distributed Channel Access) for performing transmission control in the link.

[0068] When the terminal 20 receives the beacon signal described with reference to Fig. 12, it checks the multilink capability information and the operation information of each link to be the target of the multilink from the beacon signal. Then, the link management unit LM2 of the terminal 20 notifies the link management unit LM1 of the base station 10 of information such as the links to be the target of the multilink when making a multilink association request. This allows the link management unit LM1 of the base station 10 to collectively execute the association of the multiple links specified by the link management unit LM2 of the terminal 20, and establish a multilink with the terminal 20.

[0069] In addition, when the above-mentioned beacon signal is transmitted only through the anchor link, the beacon signal may not have a field indicating the anchor link. On the other hand, when the beacon signal is transmitted through the anchor link and other links, the beacon signal may have a field indicating the anchor link and a field indicating other links. In addition, the base station 10 may add information contained in the above-mentioned beacon signal to the probe response. In this case, the link management unit LM2 of the terminal 20 can transmit a multi-link association request specifying the link to be used to the base station 10 without receiving a beacon signal. In addition, the base station 10 and the terminal 20 may perform an authentication process when establishing a multi-link.

[0070] <2-2> Data transfer during multi-link Fig. 13 shows an example of a data transmission method in multi-link in the base station 10 included in the wireless system 1 according to the embodiment. As shown in Fig. 13, when the base station 10 acquires data from an upper layer, the base station 10 executes the processes of steps S20 to S22 in order. The processes of steps S20 to S22 are described below.

[0071] In the process of step S20, the link management unit LM1 acquires TID information corresponding to the data. In other words, the link management unit LM1 associates the data with the TID by referring to control information such as a header added to the data acquired from the upper layer.

[0072] In the process of step S21, the link management unit LM1 acquires the STA function corresponding to the confirmed TID information. At this time, the link management unit LM1 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 LM1 may be one or more.

[0073] In the process of step S22, the link management unit LM1 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.

[0074] When one traffic is transmitted in parallel, data allocation and rearrangement are performed between the link management unit LM1 of the base station 10 and the link management unit LM2 of the terminal 20. Data allocation is performed by the link management unit LM on the transmitting side, and data rearrangement is performed by the link management unit LM on the receiving side. For example, the link management unit LM on the transmitting side adds a flag indicating that the wireless frame is a multi-link and an identification number. The link management unit LM on the receiving side rearranges the data based on the added flag and identification number.

[0075] In addition, in the wireless system 1 according to the embodiment, when a plurality of data are received from a higher layer, the link management unit LM may execute aggregation by combining the received plurality of data. Aggregation in multi-link may be used as an optional function that can be selected by the user whether or not to execute it.

[0076] <2-3> About anchor link change processing The wireless system 1 according to the embodiment can change the anchor link based on a predetermined condition during multi-link. Hereinafter, the process in which the wireless system 1 changes the anchor link is referred to as an "anchor link change process."

[0077] (About the execution conditions of anchor link change processing) First, an example of an execution condition of the anchor link change process will be described. Fig. 14 is a flowchart showing an example of an execution condition of the anchor link change process in the wireless system 1 according to the embodiment. The link management unit LM1 of the base station 10 periodically executes the process shown in Fig. 14 during multi-link.

[0078] Specifically, the quality measurement unit 124 of the base station 10 acquires the communication quality measurement results of each link that establishes the multi-link from the quality measurement unit 224 of the terminal 20 (step S30).Then, the quality measurement unit 124 of the base station 10 evaluates the communication quality of each link based on the received communication quality measurement results (step S31).Then, the link management unit LM1 of the base station 10 checks whether the communication quality of the anchor link satisfies a predetermined condition (step S32).

[0079] If the communication quality of the anchor link satisfies a predetermined condition (step S32, YES), the link management unit LM1 of the base station 10 ends the process without changing the anchor link. On the other hand, if the communication quality of the anchor link does not satisfy the predetermined condition (step S32, NO), the link management unit LM1 of the base station 10 checks whether the communication quality of other links satisfies the predetermined condition (step S33).

[0080] If the communication quality of the other links does not satisfy the predetermined condition (step S33, NO), the link management unit LM1 of the base station 10 ends the process without changing the anchor link. On the other hand, if the communication quality of the other links satisfies the predetermined condition (step S33, YES), the link management unit LM1 of the base station 10 executes an anchor link change process (step S34). The link management unit LM1 of the base station 10 changes the anchor link to one of the other links through the anchor link change process, and completes the process.

[0081] Various parameters may be used as evaluation criteria for the communication quality of each link. Also, various methods may be used for measuring the communication quality. For example, the channel utilization rate, the success rate of receiving a beacon signal, and the interference situation of an overlapping BSS (OBSS) may be used as the predetermined conditions in steps S32 and S33. The predetermined conditions in step S32 and the predetermined conditions in step S33 may be the same or different.

[0082] When the channel utilization rate is used as the predetermined condition, the STA function of the terminal 20 measures the busy time rate of each channel by carrier sense (CCA (Clear Channel Assessment) of the IEEE802.11 standard). The busy time rate corresponds to the proportion of time during which the received power exceeds a certain threshold. The measurement result of the busy time rate of each channel is transmitted to the quality measurement unit 224. Then, the quality measurement unit 124 of the base station 10 requests the terminal 20 to measure and notify the communication quality, and acquires the busy time rate measured by the quality measurement unit 224 of the terminal 20. Then, the link management unit LM1 of the base station 10 executes an anchor link change process when the busy time rate of the channel of the anchor link exceeds a predetermined threshold. In the anchor link change process, for example, the channel with the smallest busy time rate among the multiple channels that establish the multilink is determined as the anchor link.

[0083] When the success rate of beacon signal reception is used as the predetermined condition, the base station 10 requests the terminal 20 to measure and notify the communication quality, and transmits beacon signals using multiple channels that have established a multi-link during a predetermined period. Then, the quality measurement unit 224 of the terminal 20 measures the number of beacon signals that have been successfully received during the predetermined period for each channel, and reports the measurement result to the base station 10. Then, the link management unit LM1 of the base station 10 executes an anchor link change process when the ratio between the number of transmitted beacon signals and the number of beacon signals that have been successfully received by the terminal 20 falls below a certain threshold. In the anchor link change process, for example, the channel that has received the most beacon signals among the multiple channels that have established a multi-link is determined as the anchor link. Note that when a beacon signal is transmitted only through the anchor link, a signal for measuring communication quality may be transmitted to another channel, or an existing signal whose transmission period and transmission number are known in advance may be used.

[0084] When the OBSS interference status is used as the predetermined condition, the quality measurement unit 124 of the base station 10 checks whether the OBSS interference in the anchor link is greater than the OBSS interference in other links. In other words, the quality measurement unit 124 checks whether the channel occupation time of the OBSS for the anchor link is greater than the channel occupation time of the OBSS for other links. Note that, in order to evaluate the interference, other factors than the channel occupation time may be used, as long as at least a factor that makes the channel busy during a period other than the signal exchange of the own BSS is used. For example, the magnitude of interference power, interference from other communication systems, the presence of noise power, etc. may be used in the evaluation of the interference.

[0085] In the above description, a case where one parameter is used as the predetermined condition is exemplified, but multiple parameters may be used as the predetermined condition. For example, the link management unit LM1 of the base station 10 may evaluate the communication quality of each link using both the channel usage rate and the beacon signal reception success rate. For example, when the beacon signal reception success rate falls below a predetermined threshold and the maximum value of the channel occupation time rate of the OBSS of the other links falls below a predetermined threshold, the link management unit LM1 of the base station 10 may execute an anchor link change process to change the anchor link to one of the other links.

[0086] (Specific examples of anchor link change processing) Next, a specific example of the anchor link change process will be described with reference to Fig. 15. Fig. 15 is a flowchart showing a specific example of the anchor link change process in the wireless system 1 according to the embodiment. The initial state of the multi-link in this example is set to the state shown in Fig. 9. "Anchor" indicates that it is set as an anchor link. "Normal" indicates that it is a link that is not set as an anchor link. In the following, a link that is not set as an anchor link will be called a "normal link".

[0087] As shown in Fig. 15, when link #1 is an anchor link, the access point AP transmits a beacon signal using link #1, and the terminal 20 receives the beacon signal using the STA function assigned to link #1. The link management unit LM1 of the base station 10 transmits a communication quality measurement instruction to the terminal 20 to periodically check the communication quality of the multilink. The communication quality measurement instruction is transmitted using, for example, the anchor link (link #1). Then, based on receiving the communication quality measurement instruction, the quality measurement unit 224 of the terminal 20 measures the communication quality of each link constituting the multilink, and transmits the communication quality measurement result to the access point AP.

[0088] When the access point AP receives the communication quality measurement result, in this example, the link management unit LM1 of the base station 10 confirms that (1) the quality of the anchor link does not satisfy a predetermined condition, (2) the quality of the other links satisfies a predetermined condition, and (3) the link quality is link #2>link #3. Then, the link management unit LM1 of the base station 10 transmits an anchor link change instruction to the terminal 20 using the anchor link (link #1).

[0089] When the terminal 20 receives the anchor link change instruction, if the link management unit LM2 of the terminal 20 can permit the change of the anchor link, it transmits a positive response ("OK") to the terminal 20 via the anchor link. On the other hand, if the link management unit LM2 of the terminal 20 cannot permit the change of the anchor link, it transmits a negative response ("NG") to the base station 10 via the anchor link (not shown). When the link management unit LM2 of the terminal 20 transmits the positive response to the access point AP, it changes the anchor link of the multilink to link #2 and changes link #1 to a normal link. When the access point AP receives the positive response to the anchor link change instruction from the terminal 20, it transmits a beacon signal using the changed anchor link (link #2).

[0090] The anchor link change process described above is merely an example. The link management unit LM1 of the base station 10 executes the anchor link change process based on the communication quality of each link constituting the multi-link, and sets a link having a higher communication quality than the current anchor link as the next anchor link. Furthermore, the link management unit LM1 of the base station 10 may change the anchor link to another link based on the communication quality of the anchor link falling below that of another link, regardless of the state of the communication quality of the anchor link. The "positive response" and "negative response" may be transmitted using a link other than the anchor link.

[0091] (About radio frames used in anchor link change processing) Fig. 16 and Fig. 17 show specific examples of wireless frames used in the anchor link change process of the wireless system 1 according to the embodiment. Fig. 16 corresponds to a wireless frame transmitted when the access point AP requests the terminal 20 to change the anchor link. Fig. 17 corresponds to a wireless frame returned by the terminal 20 to the access point AP in response to the request to change the anchor link.

[0092] 16, the Frame Body of the wireless frame requesting a change of the anchor link includes, for example, a terminal identifier AID (Association Identifier), an anchor link change request, and an identifier of the target link to which the anchor link is to be changed. The link management unit LM2 of the terminal 20 corresponding to the AID refers to the "identifier of the target link" based on the "anchor link change request" and determines whether or not the anchor link can be changed.

[0093] When the anchor link can be changed, the Frame Body of a wireless frame corresponding to a positive response to the anchor link change request contains "OK" as shown in FIG. 17(a). "OK" corresponds to a bit notifying that the anchor link can be changed. On the other hand, when the anchor link cannot be changed, the Frame Body of a wireless frame corresponding to a negative response to the anchor link change request contains "NO" and "Reason" as shown in FIG. 17(b). "NO" corresponds to a bit notifying that the anchor link cannot be changed. "Reason" corresponds to a bit notifying the reason why the anchor link cannot be changed. Note that "Reason" in a wireless frame corresponding to a response to an anchor link change request may be omitted.

[0094] <2-4> How to obtain communication quality Next, a method for acquiring communication quality measurement results in the wireless system 1 according to the first embodiment will be described. There are two possible types of operation for the base station 10 to acquire communication quality measurement results for each link constituting a multi-link: one is performed under the initiative of the base station 10, and the other is performed under the initiative of the terminal 20. These two types of operation may be performed periodically, or may be performed in an event-driven manner. Below, a method for acquiring communication quality measurement results will be described taking as an example a case where the multi-link is set to the state shown in FIG. 9.

[0095] (When executed under the initiative of the base station 10) Figures 18 and 19 show an example of a method for acquiring communication quality measurement results by a base station 10 included in a wireless system 1 according to an embodiment, and correspond to a case in which acquisition of communication quality measurement results is performed periodically under the initiative of the base station 10.

[0096] 18, the base station 10 uses link #1 (anchor link), link #2, and link #3 to transmit a measurement request for link #1, a measurement request for link #2, and a measurement request for link #3 to the terminal 20, respectively. Then, based on receiving each measurement request, the terminal 20 measures the communication quality of each link using each STA function and the quality measurement unit 224, and transmits the measurement results to the base station 10.

[0097] In this way, in this example, the base station 10 obtains communication quality measurement results by transmitting a measurement request for communication quality to the terminal 20 using each link constituting the multilink. This allows the base station 10 to receive the measurement results of link #1, link #2, and link #3 from the terminal 20 via link #1, link #2, and link #3, respectively.

[0098] 19, the base station 10 may transmit a measurement request for the communication quality of each link to the terminal 20 in a lump using only the anchor link, or may receive a communication quality measurement result for each link in a lump from the terminal 20. In this case, the base station 10 transmits a measurement request for each of the links #1, #2, and #3 to the terminal 20 using the anchor link (link #1). Then, the terminal 20 transmits the communication quality measurement results for each of the links #1, #2, and #3 to the base station 10 using the anchor link.

[0099] Fig. 20 shows an example of a method for acquiring communication quality by the base station 10 included in the wireless system 1 according to the embodiment, and corresponds to a case where acquisition of communication quality is performed in an event-driven manner under the initiative of the base station 10. The link management unit LM1 of the base station 10 sequentially executes the operations shown in Fig. 20 during multi-link.

[0100] Specifically, the quality measurement unit 124 of the base station 10 measures the communication quality of each link constituting the multi-link (step S40). Then, the link management unit LM1 of the base station 10 checks whether the communication quality of each link satisfies a predetermined condition (step S41). If the communication quality of each link satisfies the predetermined condition (step S41, YES), the link management unit LM1 of the base station 10 ends the operation. On the other hand, if the communication quality of each link does not satisfy the predetermined condition (step S41, NO), the base station 10 requests the terminal 20 to measure the communication quality (step S42).

[0101] In this way, the base station 10 may measure the quality of each channel used by the base station, and transmit a measurement request to the terminal 20 when a parameter for evaluating the communication quality satisfies a predetermined condition. As the parameter for evaluating the communication quality, various parameters can be used, for example, the channel utilization rate. In this case, the link management unit LM1 of the base station 10 transmits a measurement request to the terminal 20 based on, for example, the channel utilization rate of the anchor link falling below a predetermined threshold.

[0102] (When executed under the initiative of terminal 20) 21 and 22 show an example of a method of notifying communication quality by the terminal 20 included in the wireless system 1 according to the embodiment, and correspond to a case where notification of communication quality is periodically performed under the initiative of the terminal 20. In FIG.

[0103] 21, the terminal 20 uses the link #1 (anchor link), the link #2, and the link #3 to notify the base station 10 of the communication quality measurement results of the link #1, the communication quality of the link #2, and the communication quality of the link #3, respectively. Then, the base station 10 determines whether or not to execute the anchor link change process based on each of the received communication quality measurement results.

[0104] In this way, in this example, terminal 20 periodically measures the communication quality in each channel and voluntarily transmits the measurement results to base station 10 using each link constituting the multilink. This allows base station 10 to receive the measurement results of link #1, link #2, and link #3 from terminal 20 via link #1, link #2, and link #3, respectively.

[0105] 22, the terminal 20 may transmit the measurement results of the communication quality of each link together to the base station 10 using only the anchor link. In this case, the terminal 20 transmits the communication quality measurement results of each of the links #1, #2, and #3 to the base station 10 using the anchor link (link #1).

[0106] Fig. 23 shows an example of a method of notifying communication quality by the terminal 20 included in the wireless system 1 according to the embodiment, and corresponds to a case where the notification of communication quality is performed in an event-driven manner under the initiative of the terminal 20. The link management unit LM2 of the terminal 20 sequentially executes the operations shown in Fig. 23 during multi-link.

[0107] Specifically, the quality measurement unit 224 of the terminal 20 measures the communication quality of each link constituting the multi-link (step S50). Then, the link management unit LM2 of the terminal 20 checks whether the communication quality of each link satisfies a predetermined condition (step S51). If the communication quality of each link satisfies the predetermined condition (step S51, YES), the link management unit LM1 of the terminal 20 ends the operation. On the other hand, if the communication quality of each link does not satisfy the predetermined condition (step S51, NO), the terminal 20 notifies the base station 10 of the communication quality measurement result (step S52).

[0108] In this way, the terminal 20 may measure the communication quality of each channel constituting the multilink, and notify the base station 10 of the communication quality measurement result when the parameter for evaluating the communication quality satisfies a predetermined threshold. As the parameter for evaluating the communication quality, various parameters can be used, for example, the channel utilization rate. In this case, the link management unit LM2 of the terminal 20 notifies the base station 10 of the communication quality measurement result based on, for example, the channel utilization rate of the anchor link falling below a predetermined threshold.

[0109] <3> Effects of the embodiment According to the wireless system 1 according to the embodiment described above, it is possible to improve communication stability during multi-link. The effects of the wireless system 1 according to the embodiment will be described in detail below.

[0110] Base stations and terminals using wireless LAN may have multiple STA functions provided for each band used, such as 2.4 GHz, 5 GHz, and 6 GHz. In such a wireless system, 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. At this time, in the wireless system, the STA functions that are not selected are left unused even if there is a base station that supports the band of the STA function.

[0111] In contrast, the wireless system 1 according to the 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 by 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 realize efficient communication and improve the communication speed.

[0112] As a method of operating the multilink, it is possible to set an anchor link that is used for transmitting and receiving information related to the control of the multilink. By setting the anchor link, the wireless system 1 can simplify communication between the link management unit LM1 of the base station 10 and the link management unit LM2 of the terminal 20.

[0113] On the other hand, in a multi-link, the communication stability may differ for each link constituting the multi-link. For example, the interference situation due to OBSS and the strength of radio waves may change depending on the frequency band used. For this reason, when an anchor link is set in a multi-link, the communication quality of the anchor link may be lower than the communication quality of the other links. Since the anchor link is used to control the entire multi-link, it is preferable that the anchor link has a higher communication quality than the other links.

[0114] Therefore, the wireless system 1 according to the embodiment changes the setting of the anchor link according to the communication quality of each link used in the multilink. Specifically, the quality measurement unit 224 of the terminal 20 measures the communication quality of each link constituting the multilink and notifies the base station 10 of the measurement result. Then, the quality measurement unit 124 of the base station 10 periodically evaluates the communication quality of each link constituting the multilink based on the received communication quality measurement result.

[0115] Then, when the quality measurement unit 124 detects that, for example, "channel utilization rate of the anchor link>channel utilization rate of other links," the link management unit LM1 sets, as the anchor link, a link among the other links that has a lower channel utilization rate than the anchor link. When the setting of the anchor link is changed in this way, the channel utilization rate of the anchor link decreases, and the communication quality of the anchor link improves.

[0116] As described above, in the wireless system 1 according to the embodiment, the anchor link is appropriately changed based on a predetermined condition, so that the communication quality of the anchor link is maintained in a high state. As a result, the wireless system 1 according to the embodiment can suppress a decrease in the communication quality of the entire multi-link caused by the control information being transmitted through a link with low communication quality, and can improve the communication stability during multi-link. The role of the anchor link is not limited to the transmission and reception of information related to the control of the multi-link described above. The anchor link only needs to play a role different from that of other links in the multi-link. For example, the anchor link may be used to notify traffic information (information on data stored in an access point) in each link. The anchor link may be used to transmit traffic requiring low latency. When the anchor link communicates with a specific communication device, the weighting of the traffic volume between the anchor link and other links may be changed.

[0117] <4> Modifications of the embodiment In the embodiment, the case where the base station 10 establishes a multi-link with one terminal 20 has been exemplified, but the base station 10 may establish a multi-link with multiple terminals 20. Below, as a modification of the embodiment, a variation of the operation when the base station 10 and multiple terminals 20 establish a multi-link will be described.

[0118] Fig. 24 shows an example of the overall configuration of a wireless system 1 according to a modification of the embodiment. As shown in Fig. 24, in the modification of the embodiment, three terminals 20A, 20B, and 20C are connected to a base station 10. A multi-link is established between the base station 10 and each of the terminals 20A, 20B, and 20C. The number of terminals 20 that can be connected to the base station 10 can be set according to the performance of the base station 10. When a plurality of terminals 20 are connected to the base station 10, the base station 10 may use both a multi-link and a single link.

[0119] Fig. 25 shows combinations of link sets of a multilink and anchor link settings used in a wireless system 1 according to a modified embodiment. A "link set" corresponds to a set of multiple links constituting a multilink. When a multilink is established between a base station 10 and multiple terminals 20, the four types of combinations shown in Fig. 25 are possible combinations of link sets of a multilink and anchor link settings.

[0120] The first combination corresponds to a case where the link set of the multilink and the anchor link settings are common to all terminals 20. The second combination corresponds to a case where the link set of the multilink is allowed to differ among the multiple terminals 20, and the anchor link settings are common to all terminals 20. The third combination corresponds to a case where the link set of the multilink is common to all terminals 20, and the anchor link settings are allowed to differ among the multiple terminals 20. The fourth combination corresponds to a case where each terminal 20 is allowed to have different link sets of the multilink among the multiple terminals 20, and to have different anchor link settings among the multiple terminals 20.

[0121] In the following, the first to fourth combinations are referred to as first to fourth modified examples of the embodiment, respectively. In addition, in the following, in order to simplify the explanation, a case where two terminals 20A and 20B are connected to the base station 10 will be explained as an example.

[0122] <4-1> First modified example FIG. 26 shows an example of the link management information 121 in the wireless system 1 according to the first modification of the embodiment. As shown in FIG. 26, the link sets of the terminals 20A and 20B in the first modification are the same as the link sets shown in FIG. 9. That is, the link set of the terminal 20A and the link set of the terminal 20B have a common combination of frequency bands and channels of the multiple links constituting the multilink, and also have a common frequency band and channel used as the anchor link. In the following, the links related to the STA1, STA2, and STA3 of the terminal 20A are called "link #1", "link #2", and "link #3", respectively. The links related to the STA1, STA2, and STA3 of the terminal 20B are called "link #4", "link #5", and "link #6", respectively. In this specification, the case where the same TID is used for each terminal 20 is illustrated, but different TIDs may be used for each terminal 20. That is, the association between the traffic and the TID can be arbitrarily set for each terminal 20.

[0123] Fig. 27 shows a specific example of anchor link change processing in a wireless system according to a first modification of the embodiment. Note that in Fig. 27, link #3 of terminal 20A and link #6 of terminal 20B are omitted. As shown in Fig. 27, in the first modification, the base station 10 transmits a beacon signal including control information of a Basic Service Set (BSS) using only anchor links (e.g., link #1 of terminal 20A and link #4 of terminal 20B).

[0124] For example, when the execution conditions for the anchor link change process are satisfied in each of the terminals 20A and 20B, the link management unit LM1 of the base station 10 executes the anchor link change process for each of the terminals 20A and 20B in turn. Specifically, first, the link management unit LM1 of the base station 10 transmits an anchor link change instruction to the terminal 20A, and sets the anchor link to link #2 based on a positive response from the terminal 20A. Next, the link management unit LM1 of the base station 10 transmits an anchor link change instruction to the terminal 20B, and sets the anchor link to link #5 based on a positive response from the terminal 20B.

[0125] In this example, link #2 of terminal 20A and link #5 of terminal 20B are set to the same frequency band and channel. In this way, the link management unit LM1 of the base station 10 changes the anchor link by the anchor link change process for each terminal 20 so that the frequency band and channel of the anchor link are common to each terminal 20. When the anchor link change process for all terminals 20 with which the multi-link is established is completed, the base station 10 transmits a beacon signal using only the updated anchor link.

[0126] As described above, the wireless system 1 according to the first modification of the embodiment executes the anchor link change process for the multiple terminals 20 based on the communication quality of the anchor link. As a result, the wireless system 1 according to the first modification of the embodiment can improve the communication stability of the multi-link with each terminal 20, similar to the embodiment.

[0127] When multiple terminals 20 are connected to the base station 10, the link management unit LM1 of the base station 10 may use the average or maximum busy time rate acquired from each terminal 20 for evaluation. In this case, the link management unit LM1 of the base station 10 executes the anchor link change process, for example, based on the average busy time rate acquired from each terminal 20 exceeding a predetermined threshold. Also, the base station 10 may execute the anchor link change process in parallel for multiple terminals 20 with which the base station 10 has established a multi-link.

[0128] <4-2> Second modified example FIG. 28 shows an example of link management information 121 in a wireless system 1 according to a second modification of the embodiment. As shown in FIG. 28, in the second modification, the link set of the terminal 20A and the link set of the terminal 20B share the same frequency band and channel used as an anchor link, and the combinations of the multiple links constituting the multilink are different. Specifically, in the link set of the terminal 20A, STA2 is assigned to the 5 GHz channel CH2, and STA3 is assigned to the 2.4 GHz channel CH2. On the other hand, in the link set of the terminal 20B, STA2 is assigned to the 5 GHz channel CH3, and STA3 is assigned to the 2.4 GHz channel CH3. The other configurations of the link sets of the terminals 20A and 20B are similar to those of the link sets shown in FIG. 9.

[0129] In the wireless system 1 according to the first modified example of the embodiment, for example, the link management unit LM1 of the base station 10 fixes the frequency band and channel of the anchor link used in the multilink. This example will be described as a first example of the multilink processing in the second modified example of the embodiment with reference to Fig. 29. Fig. 29 shows the first example of the multilink processing in the wireless system 1 according to the second modified example of the embodiment, and corresponds to the operation before the multilink is established between the base station 10 and the terminal 20.

[0130] As shown in FIG. 29, the terminal 20 receives the setting of the anchor link from the base station 10 (step S60). Then, the link management unit LM2 of the terminal 20 checks whether or not the channel designated as the anchor link is available (step S61). If the channel designated as the anchor link is not available (step S61, NO), the link management unit LM2 of the terminal 20 gives up on establishing a multi-link with the base station 10. On the other hand, if the channel designated as the anchor link is available (step S61, YES), the link management unit LM2 of the terminal 20 requests the base station 10 to establish a multi-link (step S62). The process of step S62 corresponds to, for example, the process of step S12 in FIG. 10.

[0131] In this way, in the first example of multilink processing in the second modified embodiment, whether or not multilink can be used is determined depending on whether or not the specified frequency band and channel are available for use by terminal 20. This makes it possible for the first example of multilink processing in the second modified embodiment to guarantee a minimum quality of multilink.

[0132] On the other hand, the wireless system 1 according to the second modified embodiment may set the channel with the highest communication quality among the multiple terminals 20 as the first anchor link. This example will be described as a second example of multilink processing in the second modified embodiment with reference to Fig. 30. Fig. 30 shows the second example of multilink processing in the wireless system according to the second modified embodiment, and corresponds to the operation before multilink is established between the base station 10 and the multiple terminals 20.

[0133] As shown in FIG. 30, the base station 10 acquires communication qualities of the multiple terminals 20 (step S70). Then, the link management unit LM1 of the base station 10 checks whether the channels available for the multiple terminals 20 for the multilink have a predetermined communication quality (step S71). If the channels available for the multiple terminals 20 for the multilink do not have the predetermined communication quality (step S71, NO), the link management unit LM1 of the base station 10 sets, for example, a preset anchor link as the first anchor link. On the other hand, if the channels available for the multiple terminals 20 for the multilink have the predetermined communication quality (step S71, YES), the link management unit LM1 of the base station 10 sets the common channel as the anchor link (step S72).

[0134] Thus, in the second example of the multilink processing in the second modified example of the embodiment, the base station 10 sets an optimal anchor link between multiple terminals 20. As a result, the second example of the multilink processing in the second modified example of the embodiment can improve the communication quality of the multilink of each of the multiple terminals 20 in the BSS.

[0135] In both the first and second examples of the multilink processing in the second modified example of the embodiment described above, the settings of the links other than the anchor link may be different for each terminal 20. In other words, in the second modified example of the embodiment, the degree of freedom of the frequency bands and channels used in the multilink is higher than in the embodiment, so that an optimal link set can be configured for each terminal 20. As a result, the wireless system 1 according to the second modified example of the embodiment can improve the communication quality of the multilink for each terminal 20.

[0136] <4-3>Third modified example Fig. 31 shows an example of link management information 121 in a wireless system 1 according to a third modified example of the embodiment. As shown in Fig. 31, in the third modified example, a common link set is used between the link set of the terminal 20A and the link set of the terminal 20B, and the anchor link settings are different. Specifically, in the link set of the terminal 20A, the anchor link is assigned to the 6 GHz channel CH1. In the link set of the terminal 20B, the anchor link is assigned to the 5 GHz channel CH2. Other configurations of the link sets of the terminals 20A and 20B are similar to those of the link sets shown in Fig. 9.

[0137] Fig. 32 shows an example of a beacon signal output method in the base station 10 included in the wireless system 1 according to the third modification of the embodiment. As shown in Fig. 32, in the wireless system 1 according to the third modification of the embodiment, the base station 10 transmits a beacon signal using all STA functions used in the multilink. This allows each terminal 20 that has established a multilink with the base station 10 to receive the beacon signal even if the frequency band and channel of the anchor link are different for each terminal 20.

[0138] In the third modification of the embodiment, the base station 10 only needs to transmit a beacon signal using at least a frequency band and a channel set for the anchor link. The beacon signal may be transmitted using a link other than the anchor link, or may not be transmitted. For example, in the example shown in FIG. 32, the transmission of a beacon signal by the STA3 of the base station 10 may be omitted. The base station 10 in the third modification of the embodiment can reduce power consumption by omitting the transmission of a beacon signal using a STA function that is not used as an anchor link.

[0139] <4-4> Fourth modified example FIG. 33 shows an example of the link management information 121 in the wireless system 1 according to the fourth modification of the embodiment. As shown in FIG. 33, in the fourth modification, different link sets are used between the link set of the terminal 20A and the link set of the terminal 20B, and the anchor link is set differently. Specifically, in the link set of the terminal 20A, STA1 is assigned to the 6 GHz channel CH1, STA2 is assigned to the 5 GHz channel CH2, STA3 is assigned to the 2.4 GHz channel CH2, and the anchor link is set to STA1. In the link set of the terminal 20B, STA1 is assigned to the 6 GHz channel CH2, STA2 is assigned to the 5 GHz channel CH3, STA3 is assigned to the 2.4 GHz channel CH3, and the anchor link is set to STA1. Other configurations of the link sets of the terminals 20A and 20B are similar to the link sets shown in FIG. 9.

[0140] FIG. 34 shows an example of anchor link change processing in the wireless system 1 according to the fourth modified example of the embodiment. As shown in FIG. 34, the base station 10 measures the channel usage rate of each channel (step S80). Then, the link management unit LM1 of the base station 10 checks whether the channel usage rate of the anchor link is higher than the channel usage rate of the other links (step S81). If the channel usage rate of the anchor link is lower than the channel usage rate of the other links (step S81, NO), the link management unit LM1 of the base station 10 maintains the setting of the anchor link. On the other hand, if the channel usage rate of the anchor link is higher than the channel usage rate of the other links (step S81, YES), the link management unit LM1 of the base station 10 sets the other links as the anchor link (step S82).

[0141] As described above, the anchor link may be changed based on the measurement result of the communication quality of each link by the base station 10. In addition, in the wireless system 1 according to the fourth modification of the embodiment, for example, the anchor link is used as the main link for communication, and the other links are used as auxiliary links. In this case, the base station 10 uses, for example, a channel with a low channel utilization rate as the anchor link for normal data exchange. Then, when, for example, traffic increases, the base station 10 uses the other link as the auxiliary link, and uses the anchor link and the auxiliary link in combination. As a result, the wireless system 1 according to the fourth modification of the embodiment can improve the communication efficiency of multi-links.

[0142] <5> others In the above embodiment, each STA function may notify the corresponding link management unit LM when the link cannot be maintained due to the movement of the terminal 20 or the like. Furthermore, the link management unit LM2 of the terminal 20 may change the state of the multi-link with the link management unit LM1 of the base station 10 based on the notification from the STA function. Specifically, for example, the link management unit LM2 of the terminal 20 and the link management unit LM1 of the base station 10 may appropriately change the STA function used in the multi-link. When the state of the multi-link is changed, the link management units LM1 and LM2 update the link management information 121 and 221, respectively. Furthermore, the link management units LM1 and LM2 may update the association between the traffic and the STA function according to an increase or decrease in the number of links.

[0143] The configuration of the wireless system 1 according to the embodiment is merely an example, and other configurations may be used. For example, the base station 10 and the terminal 20 each have three STA functions (wireless signal processing units), but 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 may be appropriately set according to 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 one communication module.

[0144] Moreover, 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 given other names and groupings as long as they are capable of executing the operations described in each embodiment.

[0145] 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.

[0146] In each embodiment, the flowchart used to explain the operation is merely an example. The order of the operations explained in the embodiments may be changed as far as possible, and other processes may be added. Furthermore, the wireless frame format explained in the above embodiment is merely an example. The wireless system 1 may use other wireless frame formats as long as they are capable of executing the operations explained in each embodiment.

[0147] The present invention is not limited to the above-mentioned embodiment, and can be modified in various ways without departing from the gist of the present invention. The embodiments may be combined as appropriate, and in that case, the combined effect can be obtained. Furthermore, the above-mentioned embodiment includes various inventions, and various inventions can be extracted by combinations selected from the multiple components disclosed. For example, if the problem can be solved and the effect can be obtained even if some components are deleted from all the components shown in the embodiment, the configuration from which the components are deleted can be extracted as an invention. [Explanation of symbols]

[0148] 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 LM1, LM2...Link Management Department 100, 200...Data processing section 110, 210...MAC frame processing unit 120,220…Management Department 121,221...Link management information 122,222...Association processing unit 123,223...Authentication processing section 124,224...Quality measurement department 125…Data Categorization Department 126...Transmission queue 127…CSMA / CA execution unit 128...Data collision management unit 130, 140, 150, 230, 240, 250...Radio signal processing unit

Claims

1. A base station for communicating with a terminal, a first radio signal processing unit that establishes a first link with the terminal; a second radio signal processing unit that establishes a second link different from the first link with the terminal; a processing unit that establishes a multi-link using the first link and the second link with the terminal, and sets one of the first link and the second link as a predetermined link to be used for periodically transmitting a beacon frame including control information related to the multi-link; The processing unit includes: transmitting the beacon frame including information of the first link and information of the second link to the terminal using the first link set as the predetermined link, and not transmitting the beacon frame using the second link which is not set as the predetermined link; A base station that, when the setting of the specified link is changed from the first link to the second link, transmits the beacon frame using the second link that is set as the specified link after notifying the terminal that the setting of the specified link is to be changed.

2. A terminal that communicates with a base station, a first radio signal processing unit that establishes a first link with the base station; a second radio signal processing unit that establishes a second link with the base station, the second link being different from the first link; a processing unit that establishes a multi-link using the first link and the second link with the base station, and sets one of the first link and the second link as a predetermined link to be used for periodically receiving a beacon frame including control information related to the multi-link; The processing unit includes: receiving the beacon frame including information of the first link and information of the second link from the base station using the first link set as the predetermined link, and not receiving the beacon frame using the second link that is not set as the predetermined link; A terminal that, when the setting of the specified link is changed from the first link to the second link, receives the beacon frame using the second link after receiving a notification from the base station of a change in the setting of the specified link.

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