Wireless Devices

Abstract

In an embodiment, this radio device comprises: an acquisition unit that acquires an index assisting with the selection of a link for sending a high-priority frame from among links constituting a multilink between the radio device and other radio devices; and a report unit that transmits to the other radio devices information for selecting said link on the basis of the index.

Description

[Technical Field]

[0001] The present invention relates to wireless communications. [Background technology]

[0002] Wireless LAN (Local Area Network) is a well-known wireless system that connects a base station and a terminal wirelessly. The base station and terminal, which are the radio stations of the wireless LAN, perform carrier sensing based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance), and transmit data when they acquire the right to transmit.

[0003] The multi-link function being considered for IEEE802.11be, which is being developed as the successor standard to IEEE802.11ax, allows a terminal to establish multiple links with a base station. When multiple links are established, the wireless station performs carrier sensing based on CSMA / CA for each link and transmits data frames using the link that has acquired the transmission right. The multi-link function improves throughput and delay characteristics.

[0004] When data frames transmitted by a base station or a terminal include high-priority frames and low-priority frames, if a link with a lot of contention is selected as the link to transmit the high-priority frame, the delay of the high-priority frame is likely to increase. On the other hand, if a link through which a high-priority frame is already being transmitted is selected when a low-priority frame is to be transmitted, the transmission of the high-priority frame is likely to be affected. In this way, when data frames with different priorities are mixed, transmitting without selecting an appropriate link according to the priority of the transmission frame degrades the communication characteristics of multi-link communication. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] IEEE P802.11be / D1.2, “35.3.6 Link management”, September 2021. Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a technique for preventing deterioration of communication characteristics in multi-link communication. [Means for solving the problem]

[0007] A wireless device according to one aspect of the present invention selects a link for transmitting a high-priority frame from among a plurality of links constituting a multilink with another wireless device. Information for other wireless devices an acquisition unit that acquires from a determining unit that determines whether a transmission frame is a high-priority frame; and a selecting unit that, when the transmission frame is a high-priority frame, selects a link for transmitting the transmission frame based on information for link selection, and, when the transmission frame is not a high-priority frame, selects a link for transmitting the transmission frame without relying on information for link selection. It is equipped with: [Effects of the Invention]

[0008] According to the present invention, a technique for preventing degradation of communication characteristics in multi-link communication is provided. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a communication system according to an embodiment. [Figure 2] FIG. 2 is a conceptual diagram showing frequency bands used in wireless communication according to the embodiment. [Figure 3] FIG. 3 is a diagram showing link management information according to the embodiment. [Figure 4] FIG. 4 is a block diagram showing a hardware configuration of the base station according to the embodiment. [Figure 5] FIG. 5 is a block diagram showing a functional configuration of the base station according to the embodiment. [Figure 6] FIG. 6 is a diagram showing a channel access function of the link management unit according to the embodiment. [Figure 7] FIG. 7 is a block diagram showing a hardware configuration of a terminal according to the embodiment. [Figure 8] FIG. 8 is a block diagram illustrating a functional configuration of the terminal according to the embodiment. [Figure 9] FIG. 9 is a flowchart showing the multi-link setup process according to the embodiment. [Figure 10] FIG. 10 is a flow chart that schematically illustrates an example of multilink selection performed by a terminal. [Figure 11] FIG. 11 is a flow chart that schematically illustrates an example of multilink selection performed by a base station. [Figure 12] FIG. 12 is a diagram showing an example of how information about a high-priority frame is written in a beacon. [Figure 13] FIG. 13 is a flow chart that schematically illustrates a first variation of multi-link selection performed by a terminal. [Figure 14] FIG. 14 is a flow chart that schematically illustrates a first variation of multi-link selection performed by a base station. [Figure 15] FIG. 15 is a diagram illustrating an example of a frame format of a trigger frame. [Figure 16] FIG. 16 is a diagram illustrating an example of a table showing the relationship between delay time and rank. [Figure 17] FIG. 17 is a flow chart that schematically illustrates a second variation of multi-link selection performed by a terminal. [Figure 18] FIG. 18 is a flow chart that schematically illustrates a second variation of multi-link selection performed by a base station. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] 1 is a schematic diagram illustrating an example of the configuration of a communication system 50 including a wireless network 45 according to an embodiment. The terms "system" and "network" used herein may be used interchangeably. As shown in FIG. 1 , the communication system 50 includes a base station 10, a terminal 20, and a server 30. The base station 10 and the terminal 20 are included in the wireless network 45.

[0012] The base station 10 operates as an access point (AP) of a wireless LAN. The base station 10 can be wirelessly connected to one or more terminals. The number of terminals wirelessly connected to the base station 10 changes dynamically. In the example shown in FIG. 1 , the base station 10 is wirelessly connected to the terminal 20. The base station 10 establishes one or more links with the terminal 20 and wirelessly communicates with the terminal 20 using one or more links. In this specification, a wireless connection using multiple links between the base station and a terminal is referred to as a "multi-link." The base station 10 is connected to a communication network 40, which may include the Internet, for example, by wire.

[0013] The terminal 20 is a wireless terminal device equipped with a wireless communication function. Examples of the wireless terminal device include a smartphone, a mobile phone, a tablet PC (personal computer), a desktop PC, a laptop PC, and an IoT (Internet of Things) sensor / device. The terminal 20 exchanges data with a computer such as a server 30 on a communication network 40 via the base station 10.

[0014] The server 30 is connected to a communication network 40. For example, the server 30 may be a service provider that provides a service such as a network game, and exchanges data related to the service with the terminal 20 via the communication network 40.

[0015] In the wireless network 45, wireless communication between the base station 10 and the terminal 20 is based on the IEEE 802.11 standard. Although this specification describes wireless communication based on the IEEE 802.11 standard as an example, a wireless communication standard other than the IEEE 802.11 standard may also be used.

[0016] The IEEE 802.11 standard defines Layer 1 and Layer 2 (MAC) sublayer of the OSI (Open Systems Interconnection) model. In the OSI model, communication functions are divided into seven layers (Layer 1: Physical Layer, Layer 2: Data Link Layer, Layer 3: Network Layer, Layer 4: Transport Layer, Layer 5: Session Layer, Layer 6: Presentation Layer, and Layer 7: Application Layer). The data link layer includes, for example, an LLC (logical link control) layer and a MAC layer. The LLC layer forms LLC packets by adding, for example, a DSAP (destination service access point) header and an SSAP (source service access point) header to data input from a higher layer. The MAC layer generates MAC frames by adding, for example, a MAC header to LLC packets. The physical layer generates wireless frames by adding, for example, a preamble and a PHY (physical layer) header to MAC frames. Here, the description will be focused on the processing of the first layer and the MAC sublayer of the second layer defined by the IEEE 802.11 standard, and the description of the processing of other layers will be omitted.

[0017] FIG. 2 schematically shows frequency bands used in the wireless network 45. In the example shown in FIG. 2, three frequency bands, namely, the 6 GHz band, the 5 GHz band, and the 2.4 GHz band, are available for wireless communication between the base station 10 and the terminal 20. Each frequency band includes multiple channels. In this embodiment, a multi-link is formed using channels in different frequency bands. For example, three links using a channel in the 6 GHz band, a channel in the 5 GHz band, and a channel in the 2.4 GHz band may be established between the base station 10 and the terminal 20. In other embodiments, multiple channels included in the same frequency band may be used to form a multi-link.

[0018] 3 is a schematic diagram of a link management table serving as link management information held by the base station 10. The link management information is information for managing the status of each link. In the example shown in FIG. 3, the link management table includes information on STA functionality, multi-link information, link information, and TID (Traffic Identifier).

[0019] The STA function corresponds to a radio signal processing unit that processes radio signals. Figure 3 shows the STA functions when, for example, the base station 10 has two radio signal processing units. For example, STA1 represents a radio signal processing unit that uses a channel in the 6 GHz band, and STA2 represents a radio signal processing unit that uses a channel in the 5 GHz band. Note that when the base station 10 has three or more radio signal processing units, STA function information for each unit is recorded.

[0020] The multilink information includes information indicating whether a multilink is established between the base station 10 and the terminal, and information indicating which STA is used to establish the link if the multilink is established. In the example of FIG. 3, the multilink information for the STA function for which the multilink is established is marked with "○". The link information includes information indicating whether the link is used for data transmission. In the example of FIG. 3, the link used for data transmission is marked with "Yes". In other words, the multilink information shown in FIG. 3 indicates that a link is established for each of STA1 and STA2. The link information shown in FIG. 3 indicates that the links corresponding to STA1 and STA2 are used for data transmission. In other words, the links corresponding to STA1 and STA2 are in an active state.

[0021] A TID is an identifier indicating the type of traffic (data). Each STA function transmits and receives traffic of its assigned TID. Traffic is classified into multiple access categories. Data transmission priorities are set for each access category. In one example, traffic may be classified into four access categories: "VO (Voice)," "VI (Video)," "BE (Best Effort)," and "BK (Background)." In another example, traffic may be classified into five access categories: "VO," "VI," "BE," "BK," and "LL (Low Latency)." Traffic in the access category "LL" is latency-sensitive traffic, such as traffic generated by real-time applications such as network games. For example, traffic of TID#1 is classified into the access category "VO," and traffic of TID#2 is classified into the access category "VI." In the example shown in Figure 3, TID#1 is assigned to STA1, and TID#2 is assigned to STA2. Here, for example, when there are four access categories, the priority order is "VO", "VI", "BE", and "BK". On the other hand, when there are five access categories, the priority order is "LL", "VO", "VI", "BE", and "BK". Hereinafter, a radio frame used for data transmission with a relatively high priority is referred to as a high-priority frame. For example, when there are five access categories, a high-priority frame is a radio frame used for data transmission of the access category "LL".

[0022] Links corresponding to the STA function are associated with TIDs when a multilink between the base station 10 and a terminal is established. For example, in the TID-to-link mapping, each TID may be associated with all links. Alternatively, the association between TIDs and links may be set so that the traffic volume (data volume) is equalized among the multiple links constituting the multilink. Also, similar types of traffic may be associated with specific links. The frequency bands allocated for transmitting and receiving traffic are preferably selected according to the type and data volume of the traffic. For example, it is conceivable to associate voice (VO), which has a small data volume, with the 5 GHz band, and video (VI), which has a large data volume, with the 6 GHz band.

[0023] Here, when there are multiple terminals 20, the association between the TID and the link may be different for each terminal 20 that has established a multi-link with the base station 10. In this case, the base station 10 may have the link management table shown in Fig. 3 for each terminal, or may manage link information for each terminal using one link management table.

[0024] Fig. 4 schematically illustrates an example of the hardware configuration of the base station 10. As illustrated in Fig. 4, the base station 10 includes, for example, a CPU (Central Processing Unit) 101, a program memory 102, a RAM (Random Access Memory) 103, a wireless communication module 104, and a wired communication module 105.

[0025] The CPU 101 is an integrated circuit capable of executing various programs and controls the overall operation of the base station 10. The program memory 102 is a non-volatile semiconductor memory such as a ROM (read only memory) or a flash memory, and stores programs and control data for controlling the base station 10. The RAM 103 is, for example, a volatile semiconductor memory, and is used as a work area for the CPU 101. The wireless communication module 104 is a circuit used to send and receive data by wireless signals, and is connected to an antenna. The wireless communication module 104 includes multiple communication modules corresponding to multiple frequency bands, respectively. The wired communication module 105 is a circuit used to send and receive data by wired signals, and is connected to the communication network 40.

[0026] The hardware configuration shown in Fig. 4 is an example, and the base station 10 may have a hardware configuration different from that shown in Fig. 4. For example, when the base station 10 is wirelessly connected to the communication network 40, the wired communication module 105 may be omitted from the base station 10.

[0027] Fig. 5 shows a schematic example of the functional configuration of the base station 10. As shown in Fig. 5, the base station 10 includes an LLC processing unit 110, a link management unit 150, and radio signal processing units 160, 170, and 180. The LLC processing unit 110 can be realized by a combination of the CPU 101 and a wired communication module 105. The data processing unit 120, the MAC frame processing unit 130, the link management unit 150, and the radio signal processing units 160, 170, and 180 can be realized by the radio communication module 104 or a combination of the radio communication module 104 and the CPU 101.

[0028] The LLC processing unit 110 performs LLC layer processing and upper layer (layers 3 to 7) processing on input data. For example, the LLC processing unit 110 generates LLC packets by adding a DSAP header, an SSAP header, etc. to data received from a computer on the communication network 40 (for example, the server 30 shown in FIG. 1 ), and sends the LLC packets to the link management unit 150. The LLC processing unit 110 also receives LLC packets from the link management unit 150, extracts data from the LLC packets, and sends the data to a computer on the communication network 40.

[0029] The link management unit 150 performs MAC layer processing on the input data. Furthermore, the link management unit 150 manages links between the base station 10 and each terminal wirelessly connected to the base station 10. The link management unit 150 includes a data processing unit 120, a MAC frame processing unit 130, and a management unit 140.

[0030] The data processing unit 120 receives LLC packets from the LLC processing unit 110 and adds a MAC header to the LLC packets to generate MAC frames. The data processing unit 120 then sends the MAC frames to the MAC frame processing unit 130. The data processing unit 120 also receives MAC frames from the MAC frame processing unit 130 and extracts LLC packets from the MAC frames. The data processing unit 120 then sends the LLC packets to the LLC processing unit 110.

[0031] The MAC frame processing unit 130 receives a MAC frame, which is a data frame, from the data processing unit 120 and temporarily stores the MAC frame. The MAC frame processing unit 130 then performs carrier sensing to check the status of the channel corresponding to the link associated with the TID of the data included in the MAC frame. If the channel is busy, the MAC frame processing unit 130 continues carrier sensing. If the channel is idle, the MAC frame processing unit 130 transmits the MAC frame to the radio signal processing unit corresponding to the link associated with the TID of the data included in the MAC frame. The MAC frame processing unit 130 receives a MAC frame, which is a management frame or a control frame, from the management unit 140 and transmits the MAC frame to one of the radio signal processing units 160, 170, or 180.

[0032] Furthermore, the MAC frame processing unit 130 receives MAC frames from the radio signal processing units 160, 170, and 180, and sends the MAC frames to the data processing unit 120 or the management unit 140 depending on the type of MAC frame. For example, if the MAC frame is a data frame, the MAC frame processing unit 130 sends the MAC frame to the data processing unit 120. If the MAC frame is a management frame or a control frame, the MAC frame processing unit 130 sends the MAC frame to the management unit 140. Furthermore, the MAC frame processing unit 130 executes processing based on instructions from the management unit 140, and exchanges information with the management unit 140.

[0033] Management unit 140 manages links with terminals based on information included in management frames received from radio signal processing units 160, 170, and 180 via MAC frame processing unit 130. In one example, management unit 140 includes link management information 141, association processing unit 142, authentication processing unit 143, measurement unit 144, multi-link control unit 145, and notification unit 146.

[0034] The link management information 141 includes information about terminals wirelessly connected to the base station 10. The link management information 141 is stored in, for example, the RAM 103, and is referenced by the MAC frame processing unit 130. For example, the MAC frame processing unit 130 uses the link management information 141 to identify a link corresponding to the TID of data included in a MAC frame to be transmitted.

[0035] The association processing unit 142 executes a protocol related to association when it receives a connection request from a terminal via one of the wireless signal processing units 160, 170, and 180. The authentication processing unit 143 executes a protocol related to authentication that follows the association.

[0036] The measurement unit 144 measures at least one type of indicator that contributes to link selection, some of which may be statistics.

[0037] At least one type of indicator to be measured includes a high-priority frame ratio. The high-priority frame ratio is the percentage of high-priority frames in wireless frames transmitted through each link. The high-priority frame ratio is expressed, for example, as two values: high and low. For example, if the ratio of high-priority frames among wireless frames transmitted through a link in a certain period is equal to or greater than a threshold, a high value is set as the high-priority frame ratio. On the other hand, if the ratio of high-priority frames among wireless frames transmitted through a link in a certain period is less than the threshold, a low value is set as the high-priority frame ratio. The high-priority frame ratio for a certain link may be expressed as being higher or lower than the average high-priority frame ratio for all links. In this case, if the ratio of high-priority frames among wireless frames transmitted through a link in a certain period is equal to or greater than the average high-priority frame ratio for all links, a high value is set as the high-priority frame ratio for the corresponding link. On the other hand, if the ratio of high-priority frames among wireless frames transmitted through a link in a certain period is less than the average high-priority frame ratio for all links, a low value is set as the high-priority frame ratio for the corresponding link. Furthermore, if necessary, the high-priority frame ratio may be information about a link associated with a wireless frame that is determined to be a high-priority frame in category information of TSN (Time Sensitive Network) Over Wi-Fi.

[0038] Furthermore, at least one type of indicator to be measured may include an average delay time, which is the average value of the delay time of wireless frame transmission for each link. The delay time may be measured from times such as queuing time, contention waiting time, contention time, retransmission time, and transmission time. The queuing time is the time from when a MAC frame is input to the end of a transmission queue until it reaches the head of the transmission queue. The contention waiting time is a waiting time determined by AIFS for collision avoidance control between access categories. The contention time is a waiting time for collision avoidance in transmission between multiple access categories or between terminals. The retransmission time is an additional time when retransmission is necessary. The transmission time is the time from when a wireless frame is transmitted until an acknowledgment (ACK) is received from the base station. Furthermore, in addition to the average delay time, a maximum delay time or a minimum delay time may be measured as necessary. Furthermore, each link may be ranked according to the length of its delay time.

[0039] In addition, the at least one type of indicator to be measured may include any indicator that contributes to the selection of a link for transmitting a high-priority frame.

[0040] The multilink control unit 145 controls the use of multiple links constituting the multilink for each terminal. For example, the multilink control unit 145 selects a link to use for transmitting a radio frame according to an index measured by the measurement unit 144. The multilink control unit 145 also associates a TID with a link. The association of a TID with a link is performed, for example, when establishing a multilink between the base station 10 and the terminal 20.

[0041] The notification unit 146 notifies the terminal 20 of multilink control information for controlling the use of multiple links constituting the multilink. In one example, the multilink control information includes information on a high-priority frame or delay time for link selection. The multilink control information may be transmitted to the terminal 20 in a management frame (e.g., a beacon). In another example, the multilink control information may be transmitted to the terminal 20 in a trigger frame.

[0042] The radio signal processing unit 160 transmits and receives data between the base station 10 and the terminal 20 via wireless communication. Specifically, the radio signal processing unit 160 performs physical layer processing on input data or radio signals. For example, the radio signal processing unit 160 receives a MAC frame from the MAC frame processing unit 130 and generates a radio frame by adding a preamble, a PHY header, and the like to the MAC frame. The radio signal processing unit 160 then performs a predetermined modulation operation on the radio frame to convert the radio frame into a radio signal and emits the radio signal via an antenna. The predetermined modulation operation includes, for example, convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform (IFFT), orthogonal frequency division multiplexing (OFDM) modulation, and frequency conversion. The radio signal processing unit 160 also receives a radio signal from the terminal 20 via the antenna and performs a predetermined demodulation operation on the received radio signal to obtain a radio frame. The predetermined demodulation operation includes, for example, frequency conversion, OFDM demodulation, Fast Fourier Transform (FFT), subcarrier demodulation, deinterleaving, and Viterbi decoding. Then, the radio signal processing unit 160 extracts the MAC frame from the radio frame and sends the MAC frame to the MAC frame processing unit 130.

[0043] Radio signal processing units 170 and 180 perform the same processing as radio signal processing unit 160. Therefore, a description of radio signal processing units 170 and 180 will be omitted. In this example, radio signal processing units 160, 170, and 180 handle radio signals in the 6 GHz band, 5 GHz band, and 2.4 GHz band, respectively. Note that radio signal processing units 160, 170, and 180 may use a common antenna or individual antennas.

[0044] Fig. 6 shows an outline of the channel access function of the MAC frame processing unit 130. As shown in Fig. 6, the MAC frame processing unit 130 includes a classification unit 131, transmission queues 132A, 132B, 132C, 132D, and 132E, carrier sense execution units 133A, 133B, 133C, 133D, and 133E, and a collision management unit 134.

[0045] 6, the classification unit 131 classifies MAC frames received from the data processing unit 120 and inputs the frames to transmission queues 132A, 132B, 132C, 132D, and 132E. In the example shown in Fig. 6, the classification unit 131 classifies MAC frames into five access categories "LL," "VO," "VI," "BE," and "BK," and inputs MAC frames classified in the access category "LL" to transmission queue 132A, MAC frames classified in the access category "VO" to transmission queue 132B, MAC frames classified in the access category "VI" to transmission queue 132C, MAC frames classified in the access category "BE" to transmission queue 132D, and MAC frames classified in the access category "BK" to transmission queue 132E. The transmission queues 132A, 132B, 132C, 132D, and 132E buffer the input MAC frames. The transmission queues 132A, 132B, 132C, 132D, and 132E are realized by the RAM 103, for example.

[0046] The carrier sense execution units 133A, 133B, 133C, 133D, and 133E perform carrier sense based on CSMA / CA in accordance with access parameters preset for each. The access parameters are set for each access category so that wireless signal transmission is prioritized in the order of, for example, "LL," "VO," "VI," "BE," and "BK." The carrier sense execution units 133A, 133B, 133C, 133D, and 133E perform carrier sense on MAC frames stored in the transmission queues 132A, 132B, 132C, 132D, and 132E, respectively. For example, when the carrier sense execution unit 133A acquires a transmission right (when the channel is idle), it retrieves a MAC frame from the transmission queue 132A and outputs the MAC frame to the wireless signal processing unit corresponding to the link associated with the access category "LL" via the collision management unit 134.

[0047] The collision management unit 134 prevents transmission collisions when two or more of the carrier sense execution units 133A, 133B, 133C, 133D, and 133E acquire the transmission right for the same link. The collision management unit 134 prioritizes the transmission of high-priority frame data. Assume that the carrier sense execution unit 133A and any of the carrier sense execution units 133B, 133C, 133D, and 133E simultaneously acquire the transmission right for the link corresponding to the wireless signal processing unit 160. In this case, the collision management unit 134 prioritizes the transmission right acquired by the carrier sense execution unit 133A and outputs the MAC frame received from the carrier sense execution unit 133A to the wireless signal processing unit 160.

[0048] In the embodiment, an example is described in which the MAC frame processing unit 130 implements the channel access function, but the radio signal processing units 160, 170, and 180 may implement the channel access function.

[0049] 7 is a schematic diagram illustrating an example of the hardware configuration of the terminal 20. As illustrated in FIG. 7, the terminal 20 includes, for example, a CPU 201, a program memory 202, a RAM 203, a wireless communication module 204, a display 205, and a storage 206.

[0050] The CPU 201 is an integrated circuit capable of executing various programs and controls the overall operation of the terminal 20. The program memory 202 is a non-volatile semiconductor memory such as a ROM, and stores programs and control data for controlling the terminal 20. The storage 206 may be used as the program memory 202. The RAM 203 is, for example, a volatile semiconductor memory, and is used as a work area for the CPU 201. The wireless communication module 204 is a circuit used to transmit and receive data via wireless signals, and is configured to be connectable to an antenna. The wireless communication module 204 also includes, for example, multiple communication modules corresponding to multiple frequency bands. The display 205 displays information such as a GUI (Graphical User Interface) provided by application software. The display 205 may also function as an input interface for the terminal 20. For example, a touch panel may be provided on the display 205. The storage 206 is a non-volatile storage device, and stores data including, for example, system software of the terminal 20.

[0051] 7 is an example, and the terminal 20 may have a hardware configuration different from that shown in Fig. 7. For example, if the terminal 20 is an IoT device or the like, the display 205 may be omitted from the terminal 20.

[0052] Fig. 8 schematically illustrates an example of the functional configuration of the terminal 20. As illustrated in Fig. 8, the terminal 20 includes an LLC processing unit 210, a link management unit 250, radio signal processing units 260, 270, and 280, and an application execution unit 290. The LLC processing unit 210 and the application execution unit 290 may be implemented by a CPU 201. The link management unit 250 and the radio signal processing units 260, 270, and 280 may be implemented by a wireless communication module 204 or a combination of the wireless communication module 204 and the CPU 201.

[0053] The LLC processing unit 210 performs LLC layer and upper layer processing on input data. For example, the LLC processing unit 210 receives data from the application execution unit 290, adds a DSAP header, an SSAP header, etc. to the data to generate an LLC packet, and sends the LLC packet to the link management unit 250. The LLC processing unit 210 also receives an LLC packet from the link management unit 250, extracts data from the LLC packet, and sends the data to the application execution unit 290.

[0054] The link management unit 250 performs MAC layer processing on the input data. Furthermore, the link management unit 250 manages the link between the terminal 20 and the base station 10 that is wirelessly connected to the terminal 20. The link management unit 250 includes a data processing unit 220, a MAC frame processing unit 230, and a management unit 240.

[0055] The data processing unit 220 receives LLC packets from the LLC processing unit 210 and generates a MAC frame by adding a MAC header to the LLC packet. The data processing unit 220 then sends the MAC frame to the MAC frame processing unit 230. The data processing unit 220 also receives MAC frames from the MAC frame processing unit 230 and extracts LLC packets from the MAC frames. The data processing unit 220 then sends the LLC packets to the LLC processing unit 210.

[0056] The MAC frame processing unit 230 receives a MAC frame, which is a data frame, from the data processing unit 220 and temporarily stores the MAC frame. The MAC frame processing unit 230 then performs carrier sensing to check the status of the channel corresponding to the link associated with the TID of the data included in the MAC frame. If the channel is busy, the MAC frame processing unit 230 continues carrier sensing. If the channel is idle, the MAC frame processing unit 230 transmits the MAC frame to the radio signal processing unit corresponding to the link associated with the TID of the data included in the MAC frame. The channel access function of the MAC frame processing unit 230 is the same as the channel access function of the MAC frame processing unit 130 of the base station 10 described with reference to FIG. 6, so a description of the channel access function of the MAC frame processing unit 230 will be omitted.

[0057] The MAC frame processing unit 230 receives a MAC frame, which is a management frame or a control frame, from the management unit 240 , and sends the MAC frame to one of the radio signal processing units 260 , 270 , and 280 .

[0058] Furthermore, the MAC frame processing unit 230 receives MAC frames from the radio signal processing units 260, 270, and 280, and sends the MAC frames to the data processing unit 220 or the management unit 240 depending on the type of MAC frame. For example, if the MAC frame is a data frame, the MAC frame processing unit 230 sends the MAC frame to the data processing unit 220. If the MAC frame is a management frame or a control frame, the MAC frame processing unit 230 sends the MAC frame to the management unit 240. Furthermore, the MAC frame processing unit 230 executes processing based on instructions from the management unit 240, and exchanges information with the management unit 240.

[0059] Management unit 240 manages links with base station 10 based on multilink control information received from radio signal processing units 260, 270, and 280 via MAC frame processing unit 230. Management unit 240 includes link management information 241, association processing unit 242, authentication processing unit 243, multilink control information acquisition unit 244, and multilink control unit 245.

[0060] The link management information 241 includes information about the base station 10 wirelessly connected to the terminal 20. The link management information 241 may include information about the STA function, multilink, link, and TID. The link management information 241 may match information about the terminal 20 included in the link management information 141 of the base station 10. The terminal 20 may measure the delay for each link (STA function) and register the measured delay value in the link management information 241. The link management information 241 is stored in, for example, the RAM 203, and is referenced by the MAC frame processing unit 230. For example, the MAC frame processing unit 230 uses the link management information 241 to identify the link corresponding to the TID of the data included in the MAC frame to be transmitted.

[0061] The association processing unit 242 executes a protocol related to association, including transmission of a connection request to the base station 10. The authentication processing unit 243 executes a protocol related to authentication subsequent to association.

[0062] The multilink control information acquisition unit 244 acquires multilink control information from the base station 10 and sends the multilink control information to the multilink control unit 245. For example, the multilink control information acquisition unit 244 acquires the multilink control information from a beacon.

[0063] The multilink control unit 245 controls the use of multiple links constituting the multilink between the base station 10 and the terminal 20 based on the multilink control information. Furthermore, the multilink control unit 245 determines the association between a TID and a link. The association between a TID and a link is performed at a predetermined timing, such as when the multilink is established between the base station 10 and the terminal 20. For example, when the multilink is set up, the multilink control unit 245 determines the association between a TID and a link and requests the multilink control unit 145 of the base station 10 to apply the association. Then, when the terminal 20 receives an acknowledgment for the request from the base station 10, the association between the TID and the link is confirmed.

[0064] The management unit 240 may further include a measurement unit that performs the same processing as the measurement unit 144 of the base station 10. When the management unit 240 includes a measurement unit, the measurement results obtained by the measurement unit are notified to the base station 10 and are used by the base station 10 to perform multilink control.

[0065] The radio signal processing unit 260 transmits and receives data between the base station 10 and the terminal 20 via wireless communication. Specifically, the radio signal processing unit 260 performs physical layer processing on the input data or radio signal. For example, the radio signal processing unit 260 receives a MAC frame from the MAC frame processing unit 230 and generates a radio frame by adding a preamble, a PHY header, and the like to the MAC frame. The radio signal processing unit 260 then performs a predetermined modulation operation on the radio frame to convert the radio frame into a radio signal, and emits the radio signal via an antenna. The radio signal processing unit 260 also receives a radio signal from the base station 10 via the antenna and performs a predetermined demodulation operation on the received radio signal to obtain a radio frame. The radio signal processing unit 260 then extracts the MAC frame from the radio frame and sends the MAC frame to the MAC frame processing unit 230.

[0066] Radio signal processing units 270 and 280 perform the same processing as radio signal processing unit 260. Therefore, a description of radio signal processing units 270 and 280 will be omitted. In this example, radio signal processing units 260, 270 and 280 handle radio signals in the 6 GHz band, 5 GHz band and 2.4 GHz band, respectively. Note that radio signal processing units 260, 270 and 280 may use a common antenna or individual antennas.

[0067] The application execution unit 290 executes an application that uses data received from the LLC processing unit 210. The application execution unit 290 sends data to the LLC processing unit 210 or receives data from the LLC processing unit 210 according to the operation of the application. The application execution unit 290 can display information from the application on the display 205. The application execution unit 290 can also execute processing according to user operations on the input interface.

[0068] 9, an example of operations related to the setup of a multilink between the base station 10 and the terminal 20 will be described. The multilink setup is performed using a management frame.

[0069] In step S10, terminal 20 transmits (broadcasts) a probe request. The probe request is a signal that confirms whether or not a base station exists in the vicinity of terminal 20. Upon receiving the probe request from terminal 20, base station 10 executes the process of step S11.

[0070] In 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. When the terminal 20 receives the probe response from the base station 10, it executes the process of step S12. Here, the probe response includes information necessary for establishing a multilink.

[0071] In step S12, the terminal 20 transmits an association request to the base station 10 via one of the STA functions of the terminal 20. The association request includes a signal for requesting the base station 10 to establish a multi-link. For example, the association request is generated by the management unit 240 of the terminal 20. When the management unit 140 of the base station 10 receives the association request including the signal for requesting the establishment of a multi-link, it executes the process of step S13. Note that the association request may be a normal association request to which information for a multi-link connection has been added.

[0072] In step S13, the management unit 140 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 for the first STA function with the terminal 20. Then, when a link is established in the first STA function, the management unit 140 of the base station 10 executes an association process for the second STA function using the first STA function with which the link is established. In other words, the STA function with which the link is established is used for the association process for the STA function with which the link is not established. When the association processes for at least two STA functions are completed, the base station 10 recognizes that a multi-link with the terminal 20 has been established, and executes the process of step S14.

[0073] In step S14, the management unit 140 of the base station 10 updates the link management information 141.

[0074] In step S15, the base station 10 transmits a multi-link establishment response to the terminal 20. The multi-link establishment response is a signal used in response to a multi-link request. When the management unit 240 of the terminal 20 receives the multi-link establishment response from the base station 10, it recognizes that a multi-link has been established with the base station 10, and executes the process of step S16.

[0075] In step S 16 , the management unit 240 of the terminal 20 updates the link management information 241 .

[0076] The multilink setup is completed by updating the link management information in both the base station 10 and the terminal 20. After that, data communication using the multilink becomes possible between the base station 10 and the terminal 20.

[0077] 9, connection processing for establishing a multi-link is performed after a probe request from the terminal 20 and a probe response from the base station 10. Alternatively, the base station 10 may periodically transmit a beacon, and the terminal 20 that receives this beacon may transmit an association request for establishing a multi-link, thereby performing connection processing for establishing a multi-link.

[0078] Next, the operation of link selection during data transmission will be described. FIG. 10 is a flowchart that schematically illustrates an example of multi-link selection executed by terminal 20. The processing of the flowchart illustrated in FIG. 10 may be started at regular intervals after the multi-link setup illustrated in FIG. 9 is completed. In the following example, a link is selected from three links. The links are numbered "link 1," "link 2," and "link 3." For example, link 1 is a link established by a radio signal processing unit using a channel in the 6 GHz band, link 2 is a link established by a radio signal processing unit using a channel in the 5 GHz band, and link 3 is a link established by a radio signal processing unit using a channel in the 2.4 GHz band.

[0079] In step S1001, multilink control information acquisition unit 244 receives a beacon from one of radio signal processing units 260, 270, and 280 via MAC frame processing unit 230. Upon receiving the beacon, multilink control information acquisition unit 244 acquires multilink control information from the beacon. Multilink control information acquisition unit 244 sends the multilink control information to multilink control unit 245.

[0080] In step S1002, each element of the terminal 20 waits until a transmission queue is generated. When data to be transmitted to the base station 10 is generated by, for example, an application process in the terminal 20, it is determined that a transmission queue has been generated. In this case, the process proceeds to step S1003. Note that if no transmission queue is generated within a certain period of time, the process of FIG. 10 may end.

[0081] In step S1003, the MAC frame processing unit 230 receives a MAC frame as a wireless frame to be transmitted via the LLC processing unit 210 and the data processing unit 220. Meanwhile, the multilink control unit 245 determines whether the priority of the wireless frame to be transmitted is high, for example, based on the TID. For example, if the TID indicates "LL," the priority of the wireless frame to be transmitted is determined to be high. If it is determined in step S1003 that the priority of the wireless frame to be transmitted is high, the process proceeds to step S1004. If it is determined in step S1003 that the priority of the wireless frame to be transmitted is not high, the process proceeds to step S1005. Here, the determination of the priority level in step S1003 is not limited to being performed using the TID. For example, the determination of the priority level may be performed using a priority directly associated with the wireless frame to be transmitted.

[0082] In step S1004, the multilink control unit 245 selects a link associated with "X" as the link for transmitting the radio frame to be transmitted, based on the information on the high-priority frame in the multilink control information. Then, the processing in FIG. 10 ends. "X" indicates the link number determined by the base station 10. "X" is information included in the multilink control information. The method for determining "X" will be explained in detail later. Note that the multilink control information may include information on the magnitude relationship of the high-priority frame ratios instead of or in addition to X. In this case, the multilink control unit 245 may select a link using the magnitude relationship of the high-priority frame ratios. For example, the multilink control unit 245 may select the link with the smallest high-priority frame ratio.

[0083] In step S1005, the multilink control unit 245 selects a link based on a normal link selection scheme. Then, the process in Fig. 10 ends. For example, the multilink control unit 245 selects a link associated with the TID.

[0084] After selecting a link, the multilink control unit 245 notifies the MAC frame processing unit 230 of information about the selected link. The MAC frame processing unit 230 performs carrier sensing to check the status of the channel corresponding to the notified link, and when the channel is idle, sends a MAC frame to the radio signal processing unit corresponding to the notified link. This causes the radio signal to be transmitted.

[0085] Fig. 11 is a flowchart that schematically illustrates an example of multilink selection performed by the base station 10. The processing of the flowchart illustrated in Fig. 11 may be started at regular intervals after the multilink setup illustrated in Fig. 9 is completed.

[0086] In step S1101, the multilink control unit 145 initializes variables for link selection. The variables include, for example, n, a, b, c, d, e, f, g, h, i, x, and y. n is the count of the total number of occurrences of transmission queues. a is the count of the number of occurrences of transmission queues in link 1, d is the count of the number of occurrences of transmission queues in link 2, and g is the count of the number of occurrences of transmission queues in link 3. b is the count of the number of occurrences of high-priority transmission queues in link 1, e is the count of the number of occurrences of high-priority transmission queues in link 2, and h is the count of the number of occurrences of high-priority transmission queues in link 3. c is the value of b / a, i.e., the high-priority frame ratio for link 1. f is the value of e / d, i.e., the high-priority frame ratio for link 2. i is the value of h / g, i.e., the high-priority frame ratio for link 3. x is the minimum of c, f, and i, i.e., the minimum value of the high-priority frame ratio. y is the average value of c, f, and i, i.e., the average value of the high priority frame ratios of links 1, 2, and 3. In step S1101, multilink control unit 145 initializes n, a, b, c, d, e, f, g, h, i, x, and y to 0.

[0087] In step S1102, each element of the base station 10 waits until a transmission queue is generated. For example, when the beacon transmission interval arrives, it is determined that a transmission queue has been generated. Furthermore, when it becomes necessary to transmit a wireless frame such as a management frame or a trigger frame, it is determined that a transmission queue has been generated. Furthermore, when data to be transmitted from the server 30 to the terminal 20 is generated, it is determined that a transmission queue has been generated. When a transmission queue has been generated, the multilink control unit 145 selects a link based on, for example, the TID and link management information. The multilink control unit 145 then notifies the MAC frame processing unit 130 of information about the selected link. The MAC frame processing unit 130 performs carrier sensing to check the status of the channel corresponding to the notified link, and when the channel is idle, it transmits a MAC frame to the wireless signal processing unit corresponding to the notified link. This results in wireless signal transmission. When the wireless frame to be transmitted is a beacon, the beacon is transmitted from the base station 10 to the terminal 20. After completing the transmission of the wireless frame, the multilink control unit 145 increments n by 1. Thereafter, the process proceeds to step S1103. Note that if no transmission queue occurs within a certain period of time, the process of FIG. 11 may end. When the process of FIG. 11 is started again, the process may be performed from the initialization of variables in step S1101, or from waiting for the occurrence of a transmission queue in step S1102. Also, in step S1102, it may be determined that a transmission queue has occurred if a transmission queue has occurred in terminal 20, that is, if a wireless frame has been transmitted from terminal 20.

[0088] In step S1103, the multilink control unit 145 determines whether the number of the link through which the wireless frame is transmitted is link 1. The multilink control unit 145 identifies the number of the link used to transmit the wireless frame, for example, based on the TID and link management information. If it is determined in step S1103 that the number of the link through which the wireless frame is transmitted is link 1, the process proceeds to step S1104. If it is determined in step S1103 that the number of the link through which the wireless frame is transmitted is not link 1, the process proceeds to step S1107.

[0089] In step S1104, multi-link control unit 145 increments a by 1. Thereafter, the process proceeds to step S1105.

[0090] In step S1105, the multilink control unit 145 determines whether the priority of the radio frame to be transmitted is high, for example, based on the TID. For example, if the TID indicates "LL," the priority of the radio frame to be transmitted is determined to be high. If it is determined in step S1105 that the priority of the radio frame to be transmitted is high, the process proceeds to step S1106. If it is determined in step S1105 that the priority of the radio frame to be transmitted is not high, the process proceeds to step S1114. Here, the determination of the high or low priority in step S1005 is not limited to being performed using the TID. For example, the determination of the high or low priority may be performed using a priority directly associated with the radio frame to be transmitted.

[0091] In step S1106, multi-link control unit 145 increments b by 1. Thereafter, the process proceeds to step S1114.

[0092] In step S1107, multilink control unit 145 determines whether the number of the link through which the wireless frame is transmitted is link 2. If it is determined in step S1107 that the number of the link through which the wireless frame is transmitted is link 2, the process proceeds to step S1108. If it is determined in step S1107 that the number of the link through which the wireless frame is transmitted is not link 2, that is, is link 3, the process proceeds to step S1111.

[0093] In step S1108, multi-link control unit 145 increments d by 1. Thereafter, the process proceeds to step S1109.

[0094] In step S1109, the multilink control unit 145 determines whether the priority of the radio frame to be transmitted is high. The determination of the priority may be performed in the same manner as in step S1105. If it is determined in step S1109 that the priority of the radio frame to be transmitted is high, the process proceeds to step S1110. If it is determined in step S1109 that the priority of the radio frame to be transmitted is not high, the process proceeds to step S1114.

[0095] In step S1110, multi-link control unit 145 increments e by 1. Thereafter, the process proceeds to step S1114.

[0096] In step S1111, multi-link control unit 145 increments g by 1. Thereafter, the process proceeds to step S1112.

[0097] In step S1112, the multilink control unit 145 determines whether the priority of the radio frame to be transmitted is high. The determination of the priority may be performed in the same manner as in step S1105. If it is determined in step S1112 that the priority of the radio frame to be transmitted is high, the process proceeds to step S1113. If it is determined in step S1112 that the priority of the radio frame to be transmitted is not high, the process proceeds to step S1114.

[0098] In step S1113, multi-link control unit 145 increments h by 1. Thereafter, the process proceeds to step S1114.

[0099] In step S1114, multilink control unit 145 determines whether n has exceeded N. N is a threshold value for determining the range of the number of radio frames used in calculating the high-priority frame ratio, and is an integer equal to or greater than 2. If it is determined in step S1114 that n does not exceed N, the process returns to step S1102. If it is determined in step S1114 that n has exceeded N, the process proceeds to step S1115.

[0100] In step S1115, measurement unit 144 receives a, b, d, e, g, and h from multilink control unit 145 and calculates c, f, and i, respectively. Furthermore, measurement unit 144 calculates x and y based on the calculated c, f, and i. Then, measurement unit 144 returns x and y to multilink control unit 145. Here, the calculation of y may be omitted.

[0101] In step S1116, the multilink control unit 145 includes information on the link number X of the link whose high-priority frame rate is the minimum value x, or information on the magnitude relationship of the high-priority frame rate, i.e., the value of the high-priority frame rate for each link, in the multilink control information and writes this information in the beacon. Then, the processing of FIG. 11 ends. FIG. 12 is a diagram showing an example of how high-priority frame information is written in a beacon. In FIG. 12, both the link number with the smallest high-priority frame rate and the value of the high-priority frame rate for each link are written in the beacon. Alternatively, only one of the link number with the smallest high-priority frame rate and the value of the high-priority frame rate for each link may be written in the beacon. Furthermore, the magnitude relationship of the high-priority frame rate may be the magnitude relationship of the value of the high-priority frame rate for each link with respect to the average value. In this case, the average value of the high-priority frame rate is also written in the beacon shown in FIG. 12.

[0102] 11, n is incremented every time a transmission queue occurs. However, n does not necessarily have to be incremented every time a transmission queue occurs. For example, n may be incremented every five times a transmission queue occurs.

[0103] Furthermore, the notification unit 146 may notify the traffic characteristics for each link using a beacon. The traffic characteristics for each link indicate, for example, the priority of traffic transmitted for each link. Specifically, the traffic characteristics for each link are information such as link 1 being used for transmitting high-priority traffic such as "LL." Upon receiving such information on the traffic characteristics for each link, the multilink control unit 245 of the terminal 20 updates the association between the TID and the link.

[0104] As described above, according to the embodiment, when selecting a link for transmitting a high-priority frame, the terminal 20 checks the information about the high-priority frame notified by the base station 10. For example, the terminal 20 selects a link with the smallest high-priority frame ratio. A link with a small high-priority frame ratio is a link with a small share of competing high-priority traffic. By transmitting high-priority frames over such a link, the transmitted high-priority frames are less likely to be affected by other wireless frames. Furthermore, by transmitting high-priority frames over such a link, it is expected that delay time will be reduced.

[0105] [Variation 1] In the above-described embodiment, the information for link selection is notified from the base station 10 to the terminal 20 using a beacon. Alternatively or in addition to this, the information for link selection may be notified from the base station 10 to the terminal 20 using a trigger frame.

[0106] Fig. 13 is a flowchart schematically showing a first modification of multilink selection executed by the terminal 20. The processing of the flowchart shown in Fig. 13 may be started at regular intervals after the multilink setup shown in Fig. 9 is completed.

[0107] In step S1301, multilink control information acquisition unit 244 receives a trigger frame from one of radio signal processing units 260, 270, 280 via MAC frame processing unit 230. Upon receiving the trigger frame, multilink control information acquisition unit 244 acquires multilink control information from the trigger frame. Multilink control information acquisition unit 244 sends the multilink control information to multilink control unit 245.

[0108] In step S1302, each element of the terminal 20 waits until a transmission queue is generated. If a transmission queue is generated, the process proceeds to step S1303. Note that if no transmission queue is generated within a certain period of time, the process of FIG. 13 may end.

[0109] In step S1303, the MAC frame processing unit 230 receives a MAC frame as a wireless frame to be transmitted via the LLC processing unit 210 and the data processing unit 220. Meanwhile, the multilink control unit 245 determines whether the priority of the wireless frame to be transmitted is high, for example, based on the TID. If it is determined in step S1303 that the priority of the wireless frame to be transmitted is high, the process proceeds to step S1304. If it is determined in step S1303 that the priority of the wireless frame to be transmitted is not high, the process proceeds to step S1305. Here, the determination of whether the priority is high or low in step S1303 is not limited to being performed using the TID. For example, the determination of whether the priority is high or low may be performed using a priority directly associated with the wireless frame to be transmitted.

[0110] In step S1304, the multilink control unit 245 selects a link with "Rank 1" from the ranks notified by the multilink control information. Alternatively, the multilink control unit 245 selects the link with the highest rank among the ranks notified by the multilink control information. Thereafter, the processing in FIG. 13 ends. The rank is determined in the base station 10 based on the length of delay time for each link. For example, the rank is made up of four ranks, from Rank 1, which is the highest rank, to Rank 4, which is the lowest rank, and is information included in the multilink control information. A high rank is set for a link with a short delay time. The method of determining the rank will be explained in detail later.

[0111] In step S1305, the multilink control unit 245 selects a link based on a normal link selection scheme. Then, the processing in Fig. 13 ends. For example, the multilink control unit 245 selects a link associated with the TID.

[0112] After selecting a link, the multilink control unit 245 notifies the MAC frame processing unit 230 of information about the selected link. The MAC frame processing unit 230 performs carrier sensing to check the status of the channel corresponding to the notified link, and when the channel is idle, sends a MAC frame to the radio signal processing unit corresponding to the notified link. This causes the radio signal to be transmitted.

[0113] Fig. 14 is a flowchart schematically showing a first modification of multilink selection performed by the base station 10. The processing of the flowchart shown in Fig. 14 may be started at regular intervals after the multilink setup shown in Fig. 9 is completed.

[0114] In step S1401, the multilink control unit 145 initializes variables for link selection. The variables include, for example, n, n{1,2,3}, delay, alldelay{1,2,3}, and maxd{1,2,3}. n is the count of the total number of times transmission queues have occurred, as described above. n{1,2,3} is the count of the number of times transmission queues have occurred for link 1, link 2, and link 3. Hereinafter, as necessary, the count of the number of times transmission queues have occurred for link 1 is represented as n1, the count of the number of times transmission queues have occurred for link 2 is represented as n2, and the count of the number of times transmission queues have occurred for link 3 is represented as n3. delay is the delay time of wireless frame transmission. alldelay{1,2,3} is the sum of the delay times of wireless frame transmission for link 1, link 2, and link 3. Hereinafter, as necessary, the sum of the delay times for link 1 is represented as alldelay1, the sum of the delay times for link 2 is represented as alldelay2, and the sum of the delay times for link 3 is represented as alldelay3. maxd{1,2,3} is the maximum delay time for transmitting wireless frames on link 1, link 2, and link 3. Hereinafter, as necessary, the total value of the maximum delay times for link 1 will be expressed as maxd1, the maximum delay time for link 2 as maxd2, and the maximum delay time for link 3 as maxd3. In step S1401, the multilink control unit 145 initializes n, n{1,2,3}, delay, alldelay{1,2,3}, and maxd{1,2,3} to 0.

[0115] In step S1402, each element of the base station 10 waits until a transmission queue is generated. When a transmission queue is generated, the multilink control unit 145 selects a link based on, for example, the TID and link management information. Then, the multilink control unit 145 notifies the MAC frame processing unit 130 of information about the selected link. The MAC frame processing unit 130 performs carrier sensing to check the status of the channel corresponding to the notified link, and when the channel is idle, sends a MAC frame to the radio signal processing unit corresponding to the notified link. This results in transmission of a radio signal. After completion of the radio signal, the multilink control unit 145 increments n by 1. Then, the process proceeds to step S1403. For example, if the radio frame to be transmitted is a trigger frame, the trigger frame is transmitted from the base station 10 to the terminal 20. Note that the trigger frame may be transmitted at each start time of a TWT (Target Wake Time). Here, the trigger frame may be assigned the highest priority access category so that the trigger frame is transmitted at the start time of the TWT. Alternatively, the trigger frame may be transmitted by a priority transmission procedure different from EDCA (Enhanced Distributed Channel Access).

[0116] In step S1403, the measurement unit 144 measures the delay time (delay) of the wireless frame transmission in step S1402. For example, the delay time (delay) is measured as the time from when a transmission queue is generated until transmission is completed and an acknowledgement (ACK) is received.

[0117] In step S1404, the multilink control unit 145 determines whether the number of the link through which the wireless frame is transmitted is link 1. If it is determined in step S1404 that the number of the link through which the wireless frame is transmitted is link 1, the process proceeds to step S1405. If it is determined in step S1404 that the number of the link through which the wireless frame is transmitted is not link 1, the process proceeds to step S1408.

[0118] In step S1405, multi-link control unit 145 adds the delay measured in step S1403 to alldelay1. Multi-link control unit 145 also increments n1 by 1. After that, the process proceeds to step S1406.

[0119] In step S1406, multilink control unit 145 determines whether delay exceeds maxd1. If it is determined in step S1406 that delay exceeds maxd1, the process proceeds to step S1407. If it is determined in step S1406 that delay does not exceed maxd1, the process proceeds to step S1415.

[0120] In step S1407, multilink control unit 145 updates maxd1 to delay, after which the process proceeds to step S1415.

[0121] In step S1408, the multilink control unit 145 determines whether the number of the link through which the wireless frame is transmitted is link 2. If it is determined in step S1408 that the number of the link through which the wireless frame is transmitted is link 2, the process proceeds to step S1409. If it is determined in step S1408 that the number of the link through which the wireless frame is transmitted is not link 2, that is, is link 3, the process proceeds to step S1412.

[0122] In step S1409, multi-link control unit 145 adds the delay measured in step S1403 to alldelay2. Multi-link control unit 145 also increments n2 by 1. Thereafter, the process proceeds to step S1410.

[0123] In step S1410, multi-link control unit 145 determines whether delay exceeds maxd2. If it is determined in step S1410 that delay exceeds maxd2, the process proceeds to step S1411. If it is determined in step S1410 that delay does not exceed maxd2, the process proceeds to step S1415.

[0124] In step S1411, multilink control unit 145 updates maxd2 to delay, after which the process proceeds to step S1415.

[0125] In step S1412, multi-link control unit 145 adds the delay measured in step S1403 to alldelay3. Also, multi-link control unit 145 increments n3 by 1. Thereafter, the process proceeds to step S1413.

[0126] In step S1413, multilink control unit 145 determines whether delay exceeds maxd3. If it is determined in step S1413 that delay exceeds maxd3, the process proceeds to step S1414. If it is determined in step S1413 that delay does not exceed maxd3, the process proceeds to step S1415.

[0127] In step S1414, multilink control unit 145 updates maxd3 to delay, after which the process proceeds to step S1415.

[0128] In step S1415, multilink control unit 145 determines whether n has exceeded N. N is a threshold value for determining the range of the number of wireless frames used in calculating the average delay time for each link, and is an integer equal to or greater than 2. If it is determined in step S1415 that n does not exceed N, the process returns to step S1402. If it is determined in step S1415 that n has exceeded N, the process proceeds to step S1416.

[0129] In step S1416, the measurement unit 144 receives n{1,2,3} and alldelay{1,2,3} from the multilink control unit 145 and calculates α, β, and γ, respectively. α is the average delay time in link 1 and is calculated by α=alldelay1 / n1. β is the average delay time in link 2 and is calculated by β=alldelay2 / n2. γ is the average delay time in link 3 and is calculated by γ=alldelay3 / n3. The measurement unit 144 also calculates δ from α, β, and γ. δ is the minimum value of α, β, and γ, i.e., the minimum value of the average delay time. The measurement unit 144 also receives maxd{1,2,3} from the multilink control unit 145 and calculates ε. ε is the minimum value of maxd1, maxd2, and maxd3, i.e., the minimum value of the maximum delay time. Then, measurement unit 144 returns α, β, γ, δ, and ε to multi-link control unit 145. Note that only one of the calculations of α, β, and γ and the calculations of δ and ε may be performed.

[0130] In step S1417, the multilink control unit 145 writes information about the rank of the average delay time for each link, and / or information about the link number of the link whose average delay time is the smallest value δ, and information about the link number whose maximum delay time is the smallest value ε, into the trigger frame. Thereafter, the processing in FIG. 14 ends. FIG. 15 is a diagram showing an example of the frame format of a trigger frame. The delay time information for these links can be written in the Common Info field in the trigger frame. FIG. 16 is a diagram showing an example of a table showing the relationship between delay time and rank. In FIG. 16, a higher rank is set for shorter delay times. The multilink control unit 145 ranks each link by comparing the values ​​of α, β, and γ measured by the measurement unit 144 with the table shown in FIG. 16.

[0131] 14, n is incremented every time a transmission queue occurs. However, n does not necessarily have to be incremented every time a transmission queue occurs. For example, n may be incremented every five times a transmission queue occurs.

[0132] Furthermore, when a trigger frame is used, information on a high-priority frame may be notified instead of the delay time. Conversely, when a beacon is used, information on a delay time may be notified instead of the high-priority frame information.

[0133] As described above, according to the first modification, when selecting a link for transmitting a high-priority frame, the terminal 20 checks the delay time information notified by the base station 10. For example, the terminal 20 selects the link with the shortest delay time, i.e., the highest-ranked link. By selecting the highest-ranked link, the high-priority frame can be transmitted with as little delay time as possible. A low-delay link can also be considered a link with few competing frames or a link with a small share of high-priority traffic. By transmitting a high-priority frame over such a link, the transmitted high-priority frame is less likely to be affected by other wireless frames.

[0134] [Variation 2] In the above-described first modification, the trigger frame is transmitted at each start time of the TWT. That is, in the above-described first modification, the trigger frame is transmitted at regular intervals. However, the transmission interval of the trigger frame may be dynamically changed depending on, for example, the delay time.

[0135] Fig. 17 is a flowchart schematically showing a second modification of multilink selection executed by the terminal 20. The processing of the flowchart shown in Fig. 17 may be started at regular intervals after the multilink setup shown in Fig. 9 is completed.

[0136] In step S1701, the multilink control unit 245 counts the number of trigger frames that are not retransmitted and that are transmitted in the BSS (Basic Service Set) to which the terminal belongs, for each link.

[0137] In step S1702, each element of the terminal 20 waits until a transmission queue is generated. If a transmission queue is generated, the process proceeds to step S1703. Note that if no transmission queue is generated within a certain period of time, the process of FIG. 17 may end.

[0138] In step S1703, the MAC frame processing unit 230 receives a MAC frame as a wireless frame to be transmitted via the LLC processing unit 210 and the data processing unit 220. Meanwhile, the multilink control unit 245 determines whether the priority of the wireless frame to be transmitted is high, for example, based on the TID. If it is determined in step S1703 that the priority of the wireless frame to be transmitted is high, the process proceeds to step S1704. If it is determined in step S1703 that the priority of the wireless frame to be transmitted is not high, the process proceeds to step S1705. Here, the determination of the high or low priority in step S1703 is not limited to being performed using the TID. For example, the determination of the high or low priority may be performed using a priority directly associated with the wireless frame to be transmitted.

[0139] In step S1704, the multilink control unit 245 selects the link with the largest trigger frame count, after which the processing in FIG.

[0140] After selecting a link, the multilink control unit 245 notifies the MAC frame processing unit 230 of information about the selected link. The MAC frame processing unit 230 performs carrier sensing to check the status of the channel corresponding to the notified link, and when the channel is idle, sends a MAC frame to the radio signal processing unit corresponding to the notified link. This causes the radio signal to be transmitted.

[0141] Fig. 18 is a flowchart schematically showing a second modification of multilink selection performed by the base station 10. The processing of the flowchart shown in Fig. 18 may be started at regular intervals after the multilink setup shown in Fig. 9 is completed.

[0142] In step S1801, multilink control unit 145 initializes variables for link selection. The variables include, for example, n, n{1,2,3}, delay, alldelay{1,2,3}, and maxd{1,2,3}. These variables are the same as those described in FIG. 14.

[0143] In step S1802, each element of the base station 10 waits until a transmission queue is generated. When a transmission queue is generated, the multilink control unit 145 selects a link based on, for example, the TID and link management information. Then, the multilink control unit 145 notifies the MAC frame processing unit 130 of information about the selected link. The MAC frame processing unit 130 performs carrier sensing to check the status of the channel corresponding to the notified link, and when the channel is idle, sends a MAC frame to the radio signal processing unit corresponding to the notified link. This results in transmission of a radio signal. After completion of the radio signal, the multilink control unit 145 increments n by 1. Then, the process proceeds to step S1803. For example, if the radio frame to be transmitted is a trigger frame, the base station 10 transmits the trigger frame to the terminal 20. Note that the trigger frame may be transmitted at intervals described later. Here, as in the first modification, the trigger frame may be assigned the highest priority access category. Alternatively, the trigger frame may be transmitted using a prioritized transmission procedure different from EDCA. If no transmission queue occurs within a certain period of time, the process of FIG. 18 may be terminated.

[0144] In step S1803, the measurement unit 144 measures the delay time "delay" of the wireless frame transmission in step S1802.

[0145] In step S1804, the multilink control unit 145 determines whether the number of the link through which the wireless frame is transmitted is link 1. If it is determined in step S1804 that the number of the link through which the wireless frame is transmitted is link 1, the process proceeds to step S1805. If it is determined in step S1804 that the number of the link through which the wireless frame is transmitted is not link 1, the process proceeds to step S1808.

[0146] In step S1805, multi-link control unit 145 adds the delay measured in step S1803 to alldelay1. Multi-link control unit 145 also increments n1 by 1. After that, the process proceeds to step S1809.

[0147] In step S1806, multilink control unit 145 determines whether the number of the link through which the wireless frame is transmitted is link 2. If it is determined in step S1806 that the number of the link through which the wireless frame is transmitted is link 2, the process proceeds to step S1807. If it is determined in step S1806 that the number of the link through which the wireless frame is transmitted is not link 2, that is, is link 3, the process proceeds to step S1808.

[0148] In step S1807, multilink control unit 145 adds the delay measured in step S1803 to alldelay2. Multilink control unit 145 also increments n2 by 1. Thereafter, the process proceeds to step S1809.

[0149] In step S1808, multilink control unit 145 adds the delay measured in step S1803 to alldelay3. Multilink control unit 145 also increments n3 by 1. Thereafter, the process proceeds to step S1809.

[0150] In step S1809, multilink control unit 145 determines whether n has exceeded N. N is a threshold value for determining the range of the number of wireless frames used in calculating the average delay time for each link, and is an integer equal to or greater than 2. If it is determined in step S1809 that n does not exceed N, the process returns to step S1802. If it is determined in step S1809 that n has exceeded N, the process proceeds to step S1810.

[0151] In step S1810, the measurement unit 144 receives n{1,2,3} and alldelay{1,2,3} from the multilink control unit 145 and calculates α, β, and γ, respectively. Then, the measurement unit 144 returns α, β, and γ to the notification unit 146. α, β, and γ are the average delay times in the respective links described above.

[0152] In step S1811, the multilink control unit 145 rearranges the average delay times α, β, and γ in ascending order. Then, the multilink control unit 145 sets the transmission interval of the trigger frame to a smaller value in ascending order of the average delay time. For example, if the delay times are α, β, and γ in this order, the transmission intervals of the trigger frames are set to be shorter in the order of α, β, and γ. For example, the transmission interval of β may be set to a predetermined median value (e.g., the TWT interval), the transmission interval of α may be set to be shorter than the transmission interval of β by a certain time, and the transmission interval of γ may be set to be longer than the transmission interval of β by a certain time.

[0153] 18, n is incremented every time a transmission queue occurs. However, n does not necessarily have to be incremented every time a transmission queue occurs. For example, n may be incremented every five times a transmission queue occurs.

[0154] Furthermore, the method of shortening the transmission interval of the trigger frames is not limited to changing the set value of the transmission interval. For example, the transmission interval of the trigger frames can be shortened by transmitting dummy trigger frames in addition to transmitting normal trigger frames.

[0155] As described above, according to the second modification, the transmission interval of the trigger frame for each link is set according to the delay time for each link. In other words, the transmission interval of the trigger frame reflects the delay time information for each link. Therefore, the terminal 20 can grasp the magnitude of the delay time for each link simply by observing the transmission interval of the trigger frame. This allows the terminal 20 to select a link suitable for transmitting a high-priority frame.

[0156] Here, in Modification 2, the transmission interval of the trigger frame is set according to the delay time. Alternatively, the transmission interval of the trigger frame may be set according to the proportion of high-priority frames.

[0157] Furthermore, in the above-described embodiment and its variations, the wireless communication functions of the wireless stations (base station 10 and terminal 20) may be implemented by discrete components such as chips. For example, a chip may be embedded in a substrate of the wireless station when the wireless station is manufactured. The wireless device referred to here may refer to the wireless station or to a discrete component that realizes the wireless communication function of the wireless station.

[0158] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected components from the disclosed components. For example, if the problem can be solved and the effects can be obtained even if some components are removed from all the components shown in the embodiments, the configuration from which these components are removed can be extracted as an invention. [Explanation of symbols]

[0159] 10...Base station 20...Terminal 30...Server 40...Communication Network 45...Wireless network 50...Communication Systems 101...CPU 102...Program memory 103...RAM 104...Wireless communication module 105...Wired communication module 110...LLC Processing Section 120...Data processing unit 130...MAC frame processing unit 131...Classification section 132A, 132B, 132C, 132D, 132E...Transmission queue 133A, 133B, 133C, 133D, 133E...Carrier sense execution unit 134…Collision Management Department 140...Management Department 141...Link management information 142...Association processing unit 143...Authentication processing unit 144…Measurement part 145...Multi-link control unit 146…Notification Department 150...Link Management Department 160, 170, 180...Radio signal processing unit 201...CPU 202...Program memory 203...RAM 204...Wireless communication module 205...Display 206…Storage 210...LLC Processing Section 220...Data processing unit 230...MAC frame processing unit 240...Management Department 241...Link management information 242...Association processing unit 243...Authentication processing unit 244...Multi-link control information acquisition unit 245...Multi-link control unit 250...Link Management Department 260, 270, 280...Radio signal processing unit 290...Application execution unit

Claims

1. an acquisition unit that acquires, from another wireless device, information for selecting a link for transmitting a high-priority frame from among a plurality of links that constitute a multilink with the other wireless device; a determination unit that determines whether a transmission frame is a high-priority frame; a selection unit that, when a transmission frame is a high-priority frame, selects a link for transmitting the transmission frame based on information for link selection, and, when the transmission frame is not a high-priority frame, selects a link for transmitting the transmission frame without relying on information for link selection; A wireless device comprising:

2. the information for selecting a link includes information on a link having a minimum high-priority frame ratio, which indicates an occupancy rate of high-priority frames in radio frames transmitted through each link, or information on a link having a minimum delay time; 10. The wireless device of claim 1.

3. the information for selecting the link is included in a beacon; 3. The wireless device according to claim 1 or 2.

4. The information for selecting the link is included in a trigger frame.

4. A wireless device according to any one of claims 1 to 3.

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