Access point

Abstract

An access point according to one aspect of the present invention is provided with a management unit having scheduled therein a service period for a terminal device group including a terminal device, the service period being a period during which data communication can be carried out via the access point, so that the management unit skips data communication by the terminal device in service periods that occur after completion of a handover of the terminal device from another access point to the access point.

Description

Access Points

[0001] The present invention relates to wireless communications.

[0002] IEEE 802.11be is considering multi-link transmission, in which multiple wireless links (transmission paths) with different frequency channels are established between a terminal device and an access point. Furthermore, in the next generation of IEEE 802.11 standardization, a multi-access point (AP) function in which multiple access points cooperate and work together is being considered. With the multi-AP function, multiple shared APs connected to a shared AP cooperate to communicate data with a terminal device. A terminal device can change the shared AP to which it is connected by performing a handover.

[0003] Furthermore, in IEEE 802.11be, the R-TWT (restricted target wake time) function is also being considered as a method for transmitting and receiving low-latency traffic between an access point and a terminal device. An access point using the R-TWT function schedules an R-TWT service period for a terminal device that handles low-latency traffic, for example, in accordance with the required delay of the low-latency traffic. The terminal device can transmit low-latency traffic to the access point during the scheduled service period. An information communication system using the R-TWT function can reduce the delay and jitter of low-latency traffic.

[0004] IEEE P802.11be / D4.1, “35.8 Restricted TWT (R-TWT)”, p622-p627, September 2023. IEEE 802.11-23 / 0297r0, “R-TWT for Multi-AP”, April 2023.

[0005] Assume a situation in which the R-TWT service period is periodically set for each shared AP or sharing AP. In this case, there is a concern that a terminal device may repeatedly handover between shared APs in order to obtain multiple service periods. If a specific terminal device obtains multiple service periods, transmission opportunities for other terminal devices will decrease. As a result, the effectiveness of R-TWT will be reduced.

[0006] An object of the present invention is to provide a technique for preventing the effect of the R-TWT from being reduced.

[0007] An access point according to one embodiment of the present invention has a management unit that schedules a service period during which data communication can be performed for a group of terminal devices including the access point, and skips data communication by the terminal device during the service period that occurs after handover of the terminal device from another access point to the access point is completed.

[0008] According to the present invention, it is possible to provide a technique for preventing the effect of R-TWT from being reduced due to a terminal device that repeatedly performs handovers.

[0009] FIG. 1 is a block diagram illustrating an information communication system according to an embodiment. FIG. 2 is a diagram illustrating an overview of a wireless communication method according to an embodiment. FIG. 3 is a block diagram illustrating a hardware configuration of a sharing access point according to an embodiment. FIG. 4 is a block diagram illustrating a hardware configuration of a shared access point according to an embodiment. FIG. 5 is a block diagram illustrating a hardware configuration of a terminal device according to an embodiment. FIG. 6 is a block diagram illustrating a functional configuration of a sharing access point according to an embodiment. FIG. 7 is a block diagram illustrating a functional configuration of a shared access point according to an embodiment. FIG. 8 is a block diagram illustrating a functional configuration of a terminal device according to an embodiment. FIG. 9 is a diagram illustrating a method of imposing a penalty on a terminal device that has executed a handover according to an embodiment. FIG. 10 is a diagram illustrating a method of imposing a penalty on a terminal device that has executed a handover according to an embodiment. FIG. 11 is a diagram illustrating a method of imposing a penalty on a terminal device that has executed a handover according to an embodiment. FIG. 12 is a diagram illustrating a method of imposing a penalty on a terminal device that has executed a handover according to an embodiment. FIG. 13 is a diagram illustrating a problem that may occur in the related art.

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments exemplify devices and methods for embodying the technical ideas of the invention and are not intended to limit the scope of the invention. The drawings are schematic or conceptual. Hereinafter, components having similar functions or configurations are assigned the same reference numerals. To distinguish between components having similar functions or configurations, a subscript may be added to the reference numeral. The subscript is added after a hyphen (-). Hereinafter, "access point" may be abbreviated as "AP."

[0011] FIG. 1 schematically illustrates an information communication system 50 according to one embodiment. As illustrated in FIG. 1, the information communication system 50 includes a sharing access point (AP) 10, a shared AP (shared access point) 20, a terminal device 30, and a network 40. In the example illustrated in FIG. 1, two sharing APs 10-1 and 10-2 are provided as the sharing AP 10, and four shared APs 20-1, 20-2, 20-3, and 20-4 are provided as the shared AP 20. Although one terminal device 30 is illustrated, multiple terminal devices 30 may be included in the information communication system 50.

[0012] The sharing AP 10 is a type of access point of a wireless LAN (local area network). In this specification, a wireless LAN access point may be referred to as a base station. The sharing AP 10 is connected to a network 40, which may include the Internet, by wire or wirelessly, and communicates with a computer (e.g., a server) on the network 40. In this embodiment, the sharing AP 10 is connected to the network 40 by wire. The sharing APs 10-1 and 10-2 communicate with each other to share information. The sharing AP 10-1 may communicate with the sharing AP 10-2 via the network 40, or may communicate directly with the sharing AP 10-2. In this embodiment, the sharing APs 10-1 and 10-2 communicate with each other via the network 40.

[0013] Furthermore, the sharing AP 10 is connected by wire or wirelessly to a plurality of shared APs 20 that it manages, and communicates with these shared APs 20. In this embodiment, the sharing AP 10 is connected wirelessly to a plurality of shared APs 20. In the example shown in Fig. 1 , the sharing AP 10-1 is connected to shared APs 20-1 and 20-2, and the sharing AP 10-2 is connected to shared APs 20-3 and 20-4.

[0014] Each sharing AP 10 may be connected to three or more shared APs 20. Also, each sharing AP 10 may be connected to a different number of shared APs 20. For example, sharing AP 10-1 is connected to two shared APs 20, and sharing AP 10-2 is connected to three shared APs 20. Although the sharing AP 10 is shown separated from the shared APs 20, the sharing AP 10 and one of the shared APs 20 may exist in a single device. For example, sharing AP 10-1 includes shared AP 20-1.

[0015] The shared AP 20 is a type of wireless LAN access point. The shared AP 20 relays communication between the sharing AP 10 and the terminal device 30. The shared AP 20 is connected to the sharing AP 10 wirelessly or via a wired connection and communicates with the sharing AP 10. In this embodiment, the shared AP 20 is connected to the sharing AP 10 wirelessly. Furthermore, the shared AP 20 is connected to the terminal device 30 wirelessly and communicates with the terminal device 30. The shared APs 20 are located in different locations and have different communication areas. The communication area of ​​each shared AP 20 may partially overlap with the communication area of ​​another shared AP 20.

[0016] The sharing APs 10-1 and 10-2 and the shared APs 20-1 to 20-4 form an AP system that provides a multi-AP connection to the terminal device 30. The multi-AP connection indicates a connection in which a terminal device establishes multiple wireless links (transmission paths) with multiple APs (multiple shared APs 20 in this example).

[0017] The terminal device 30 is a terminal device with a wireless communication function, such as a smartphone, a personal computer (PC), etc. The terminal device 30 is carried by a user and moves with the user as shown by the arrow in FIG.

[0018] The terminal device 30 is configured to establish a multi-AP connection with a plurality of shared APs 20. The terminal device 30 includes a plurality of affiliated STAs 31 and a non-APMLD (non-access point multi-link device) 32. In the example shown in FIG. 1 , the affiliated STAs 31 include an affiliated STA 31-1 referred to as affiliated STA #1 and an affiliated STA 31-2 referred to as affiliated STA #2. Note that three or more affiliated STAs 31 may be provided.

[0019] Each affiliated STA 31 is configured to establish a wireless link with the shared AP 20 and exchange data with the shared AP 20 through the established wireless link. In the example shown in FIG. 1 , a wireless link is established between the affiliated STA 31-1 and the shared AP 20-2, and a wireless link is established between the affiliated STA 31-2 and the shared AP 20-3. These two wireless links use different frequency channels. The terminal device 30 may communicate with the sharing AP 10-1 via the shared AP 20-2 and may communicate with the sharing AP 10-2 via the shared AP 20-3 to transmit data to a computer on the network 40.

[0020] The non-AP MLD 32 performs data communication using the affiliated STAs 31. Furthermore, the non-AP MLD 32 manages the link status of each affiliated STA 31. The non-AP MLD 32 also performs various processes, including a process for establishing a multi-AP connection and a process for switching the connection destination of the affiliated STA 31, called handover. For example, the non-AP MLD 32 uses one of the affiliated STAs 31 to send an association request to the sharing AP 10 via the shared AP 20, requesting the establishment of a multi-AP connection. Here, a description of the procedure for establishing a multi-AP connection will be omitted.

[0021] The wireless communication used in the information and communication system 50 complies with, for example, the IEEE 802.11 standard. The IEEE 802.11 standard has wireless communication functions based on the OSI (open systems interconnection) reference model. In the OSI reference model, wireless communication functions are divided into seven layers (Layer 1: physical layer, Layer 2: data link layer, Layer 3: network layer, Layer 4: transport layer, Layer 5: session layer, Layer 6: presentation layer, and Layer 7: application layer). The data link layer includes a logical link control (LLC) sublayer and a media access control (MAC) sublayer. The wireless communication of the information and communication system 50 may use frequency bands such as the 2.4 GHz band, the 5 GHz band, the 6 GHz band, the 45 GHz band, and the 60 GHz band. Each frequency band includes multiple frequency channels.

[0022] In the information communication system 50, the sharing AP 10, the shared AP 20, and the terminal device 30 each support the R-TWT (restricted target wake time) function. The R-TWT function is a function that assigns a service period (SP) to wireless devices such as the terminal device 30, during which traffic (data) that requires low latency can be preferentially exchanged. Note that traffic that requires low latency is called "low latency traffic."

[0023] The R-TWT service period can be set for each sharing AP 10 or each shared AP 20. Each sharing AP 10 or each shared AP 20 assigns a service period. For example, the sharing AP 10 or the shared AP 20 assigns a service period in response to a request from the terminal device 30 and notifies the terminal device 30 of the service period assignment. The shared AP 20-2 assigns a service period to the terminal device 30, and the terminal device 30 can transmit low-latency traffic to the shared AP 20-2 or receive low-latency traffic from the shared AP 20-2 during the service period assigned to it. For example, the shared AP 20-2 transmits a trigger frame at the start of the service period to give the terminal device 30 a transmission opportunity, and the terminal device 30 transmits low-latency traffic in response to receiving the trigger frame from the shared AP 20-2. In this way, the R-TWT function can improve the latency of low-latency traffic by prioritizing communication of low-latency traffic during the service period.

[0024] A general method can be used to set up the R-TWT. For example, the sharing AP 10 transmits TWT information to each shared AP 20. The TWT information includes information about wireless links (transmission paths) that can use the TWT function. Each shared AP 20 then broadcasts a beacon signal that includes the TWT information. This beacon signal can be received by each affiliated STA 31 of the terminal device 30. The affiliated STA 31 that receives the beacon signal outputs the TWT information included in the beacon signal to the non-AP MLD 32.

[0025] The non-AP MLD 32 transmits a TWT request to the shared AP 20 based on the received TWT information. The TWT request includes the identifier of the non-AP MLD 32 and information about wireless links available for multi-AP connection. The sharing AP 10 schedules an R-TWT service period based on the TWT request received from the non-AP MLD 32. Then, the sharing AP 10 transmits an R-TWT response to the non-AP MLD 32 via the shared AP 20. When the non-AP MLD 32 receives the R-TWT response, the R-TWT setup (TWT agreement setup) is completed.

[0026] In the information communication system 50, the terminal device 30 performs a handover as it moves. For example, as the terminal device 30 moves to the right in FIG. 1 , the power of the wireless signal received by the affiliated STA 31-1 from the shared AP 20-2 decreases, and the power of the wireless signal received by the affiliated STA 31-2 from the shared AP 20-4 increases. In response to this, the non-AP MLD 32 switches the connection destination of the affiliated STA 31-1 from the shared AP 20-2 to the shared AP 20-4. Specifically, the non-AP MLD 32 transmits a handover request to the sharing AP 10 requesting a handover of the affiliated STA 31-1. For example, the non-AP MLD 32 uses the affiliated STA 31-1 to transmit the handover request to the sharing AP 10-1 via the shared AP 20-2. The handover request includes information identifying the affiliated STA 31 to be the target of handover, information identifying the shared AP 20 of the handover source, and information identifying the shared AP 20 of the handover destination. In response to receiving the handover request, the sharing AP 10-1 executes a handover procedure. A detailed description of the handover procedure will be omitted here. Meanwhile, the wireless link between the affiliated STA 31-2 and the shared AP 20-3 is maintained.

[0027] The shared AP 20-4, which is the handover destination, imposes a penalty on the terminal device 30 that performed the handover, as necessary. Specifically, the shared AP 20-4 skips data communication by the terminal device 30 for a service period that occurs after the handover is completed and is assigned to a group of terminal devices including the terminal device 30. Skipping data communication by the terminal device 30 for a service period may include not providing the terminal device 30 with an exclusive transmission opportunity during the service period. The group of terminal devices includes at least one terminal device.

[0028] An example of a method for imposing a penalty on a terminal device 30 that has performed a handover will be briefly described with reference to Fig. 2. In Fig. 2, a periodic service period SP1 assigned to a terminal device group including the terminal device 30 is shown. There may be service periods assigned to other terminal device groups. In the description with reference to Fig. 2, the service period SP1 refers to the service period assigned to the terminal device group including the terminal device 30.

[0029] As shown in Fig. 2, the shared AP 20-4 skips data communication by the terminal device 30 during a service period SP1 that occurs from the time when the handover of the affiliated STA 31-1 is completed until a predetermined time T has elapsed. In the example shown in Fig. 2, the first service period SP1 that occurs in the shared AP 20-4 after the handover of the affiliated STA 31-1 is completed starts before the predetermined time T has elapsed. Therefore, the terminal device 30 cannot acquire a transmission opportunity during this service period SP1. During the next service period SP1, the terminal device 30 can acquire a transmission opportunity.

[0030] A problem that may arise in the related technology will be described with reference to FIG. 13 . Assume a situation in which R-TWT service periods are set for two access points #1 and #2 as shown in FIG. 13 . In FIG. 13 , service periods SP1, SP2, and SP3 indicate service periods assigned to a first terminal device group, a second terminal device group, and a third terminal device group, respectively. In the related technology, a situation may arise in which a specific terminal device included in the first terminal device group drifts between access point #1 and access point #2 to obtain multiple transmission opportunities. If a terminal device obtains multiple transmission opportunities by drifting between access point #1 and access point #2, the transmission opportunities for other terminal devices will decrease. This reduces the effectiveness of R-TWT. Furthermore, as the number of terminal devices that repeatedly drift increases, the effectiveness of R-TWT will further decrease.

[0031] In the information communication system 50 according to this embodiment, the drift required to acquire a transmission opportunity can be reduced by imposing a penalty on a terminal device that has performed a handover, thereby preventing a decrease in the effectiveness of R-TWT.

[0032] As an exception, a penalty may be excluded from being imposed on a terminal device whose communication should be prioritized, such as a terminal device performing data communication of low-latency traffic or a terminal device performing data communication of traffic of a predetermined TID (traffic identifier), or a terminal device designated in advance. For example, the sharing AP 10 may designate terminal devices to be excluded from being subject to penalty imposition.

[0033] Fig. 3 schematically illustrates an example of the hardware configuration of the sharing AP 10. The sharing AP 10 illustrated in Fig. 3 corresponds to each of the sharing APs 10-1 and 10-2 illustrated in Fig. 1. As illustrated in Fig. 3, the sharing AP 10 includes 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.

[0034] The CPU 11 is an integrated circuit capable of executing various programs and controls the overall operation of the sharing AP 10. The ROM 12 is, for example, a non-volatile semiconductor memory that stores programs and control data for controlling the sharing AP 10. The RAM 13 is, for example, a volatile semiconductor memory that is used as a work area for the CPU 11. At least a portion of the processing described for the sharing AP 10 can be performed by the CPU 11 executing the programs stored in the ROM 12.

[0035] The wireless communication module 14 is a circuit configured to be able to send and receive wireless signals via an antenna, and is a circuit used to send and receive data and the like with the shared AP 20. When the sharing AP 10 shown in FIG. 3 is the sharing AP 10-1 shown in FIG. 1, the wireless communication module 14 is used to communicate with the shared APs 20-1 and 20-2. The wired communication module 15 is a circuit used to send and receive data and the like using electrical signals or optical signals, and is configured to be connectable to the network 40.

[0036] Note that the hardware configuration shown in Fig. 3 is an example, and the sharing AP 10 may have a hardware configuration different from that shown in Fig. 3. For example, the sharing AP 10 may be wirelessly connected to the network 40. In this case, the sharing AP 10 includes a wireless communication module instead of the wired communication module 15. The sharing AP 10 may also be wiredly connected to the shared AP 20. In this case, the sharing AP 10 includes a wired communication module instead of the wireless communication module 14. The CPU 11 is an example of a processor, and other types of processors may be used.

[0037] Fig. 4 shows an example of a hardware configuration of the shared AP 20. The shared AP 20 shown in Fig. 4 corresponds to each of the shared APs 20-1 to 20-4 shown in Fig. 4. As shown in Fig. 4, the shared AP 20 includes a CPU 21, a ROM 22, a RAM 23, a wireless communication module 24, and a wireless communication module 25.

[0038] The CPU 21 is an integrated circuit capable of executing various programs and controls the overall operation of the shared AP 20. The ROM 22 is, for example, a non-volatile semiconductor memory and stores programs and control data for controlling the shared AP 20. The RAM 23 is, for example, a volatile semiconductor memory and is used as a work area for the CPU 21. At least a portion of the processing described for the shared AP 20 can be performed by the CPU 21 executing the programs stored in the ROM 22.

[0039] The wireless communication module 24 is a circuit configured to be able to send and receive wireless signals via an antenna, and is used to send and receive data, etc., to and from a terminal device (for example, the terminal device 30 shown in FIG. 1 ). The wireless communication module 25 is a circuit configured to be able to send and receive wireless signals via an antenna, and is used to send and receive data, etc., to and from the sharing AP 10.

[0040] 4 is an example, and the shared AP 20 may have a hardware configuration different from that shown in Fig. 4. For example, the shared AP 20 may be connected to the sharing AP 10 by wire. In this case, the shared AP 20 includes a wired communication module instead of the wireless communication module 25. The CPU 21 is an example of a processor.

[0041] 5 is a schematic diagram illustrating an example of the hardware configuration of the terminal device 30. As illustrated in FIG. 5, the terminal device 30 includes a CPU 34, a ROM 35, a RAM 36, a wireless communication module 37, a display 38, and a storage 39.

[0042] The CPU 34 is an integrated circuit capable of executing various programs and controls the overall operation of the terminal device 30. The ROM 35 is, for example, a non-volatile semiconductor memory and stores programs and control data for controlling the terminal device 30. The RAM 36 is, for example, a volatile semiconductor memory and is used as a work area for the CPU 34. At least a portion of the processing described for the terminal device 30 can be implemented by the CPU 34 executing the programs stored in the ROM 35.

[0043] The wireless communication module 37 is a circuit configured to be able to send and receive wireless signals via an antenna, and is used to send and receive data between the terminal device 30 and the shared AP 20. The display 38 displays, for example, a GUI (Graphical User Interface) corresponding to application software. The storage 39 is a non-volatile storage device that stores, for example, system software for the terminal device 30.

[0044] Note that the hardware configuration shown in Fig. 5 is an example, and the terminal device 30 may have a hardware configuration different from that shown in Fig. 5. For example, if the terminal device 30 is an IoT (Internet of Things) device such as a sensor, the display 38 may be omitted from the terminal device 30. The display 38 may function as an input interface for the terminal device 30. The CPU 34 is an example of a processor.

[0045] Fig. 6 schematically shows an example of the functional configuration of the sharing AP 10. The sharing AP 10 shown in Fig. 6 corresponds to each of the sharing APs 10-1 and 10-2 shown in Fig. 1. As shown in Fig. 6, the sharing AP 10 includes a data processing unit 101, a management unit 102, a frame processing unit 103, and a transmission / reception unit 104. The management unit 102 includes a terminal management unit 1021. The data processing unit 101, the management unit 102, the frame processing unit 103, and the transmission / reception unit 104 can be realized by the wireless communication module 14 or a combination of the CPU 11 and the wireless communication module 14.

[0046] Data processing unit 101 outputs data input from network 40 via an LLC layer (not shown) to frame processing unit 103. Data processing unit 101 also outputs data input from frame processing unit 103 to network 40 via the LLC layer.

[0047] The frame processing unit 103 exchanges management information with the management unit 102 and exchanges data with the data processing unit 101. The management information includes information for managing the terminal device 30. For example, the management information includes information indicating the shared AP 20 to which each affiliated STA 31 of the terminal device 30 is connected. Furthermore, the frame processing unit 103 transmits and receives MAC frames to the shared AP 20 via the transceiver 104. For example, the frame processing unit 103 receives management information from the management unit 102, generates a MAC frame including the management information, and transmits the MAC frame to the shared AP 20 via the transceiver 104. The frame processing unit 103 receives data from the data processing unit 101, generates a MAC frame including the data, and transmits the MAC frame via the transceiver 104 to the shared AP 20 connected to the destination terminal device.

[0048] The frame processing unit 103 receives a MAC frame from the shared AP 20 via the transceiver unit 104, extracts terminal information or data from the MAC frame, and outputs the terminal information to the management unit 102 or the data to the data processing unit 101. The terminal information includes information about a terminal device connected to the shared AP 20, which is transmitted by the shared AP 20. For example, the terminal information includes a measurement value of the time that has elapsed since the handover of the terminal device was completed.

[0049] The transceiver 104 is wirelessly connected to each shared AP 20 and communicates with the shared AP 20. The communication between the transceiver 104 and the shared AP 20 is performed using a specific frequency channel.

[0050] The transceiver 104 receives a MAC frame from the frame processor 103 and transmits the MAC frame to the shared AP 20. Specifically, the transceiver 104 generates a wireless frame by adding a preamble, a PHY header, and the like to the MAC frame, converts the wireless frame into a wireless signal by performing a predetermined modulation process, and emits the wireless signal via an antenna. When simultaneously notifying multiple shared APs 20, the transceiver 104 may transmit a beacon signal or the like by, for example, multicast or broadcast.

[0051] Furthermore, the transmitting / receiving unit 104 receives a MAC frame from the shared AP 20 and outputs the MAC frame to the frame processing unit 103. Specifically, the transmitting / receiving unit 104 receives a wireless signal from the shared AP 20 via the antenna, performs a predetermined demodulation process on the wireless signal to obtain a wireless frame, extracts the MAC frame from the wireless frame, and outputs the MAC frame to the frame processing unit 103.

[0052] The management unit 102 executes a process for establishing a multi-AP connection with the terminal device 30. The management unit 102 further executes various processes including handling handover of the terminal device 30, scheduling of R-TWT service periods, and TID-link mapping for associating a TID with multiple wireless links that constitute the multi-AP connection.

[0053] The terminal management unit 1021 holds terminal information about terminal devices connected to each shared AP 20. The terminal information includes a history of handovers performed by the terminal devices and a measurement value of the time elapsed since the handover of the terminal device was completed. The terminal management unit 1021 exchanges terminal information with other sharing APs 10. Specifically, the terminal management unit 1021 transmits terminal information about terminal devices managed by the sharing AP 10 to the other sharing APs 10, and receives terminal information about terminal devices managed by the other sharing APs 10 from the other sharing APs 10. The management unit 102 can derive the number of times a terminal device has performed handovers within a certain period from the terminal information held by the terminal management unit 1021. The management unit 102 can derive the time elapsed since the handover of the terminal device was completed from the terminal information held by the terminal management unit 1021.

[0054] Fig. 7 schematically illustrates an example of the functional configuration of the shared AP 20. As illustrated in Fig. 7, the shared AP 20 includes a data processing unit 201, a management unit 202, a frame processing unit 203, a frame processing unit 204, a transceiver unit 205, and a transceiver unit 206. The management unit 202 includes a terminal management unit 2021. The data processing unit 201, the management unit 202, the frame processing unit 203, the frame processing unit 204, the transceiver unit 205, and the transceiver unit 206 can be realized by a combination of the CPU 21, the wireless communication module 24, and the wireless communication module 25.

[0055] The transceiver 206 is used for communication with the sharing AP 10. The transceiver 206 performs the same processing as the transceiver 104 of the sharing AP 10 shown in FIG. 6 , and therefore a detailed description of the transceiver 206 will be omitted. The transceiver 206 transmits the MAC frame input from the frame processing unit 204 to the sharing AP 10. The transceiver 206 also receives a wireless signal from the sharing AP 10, extracts the MAC frame from the wireless signal, and outputs the MAC frame to the frame processing unit 204.

[0056] The frame processing unit 204 outputs the MAC frame input from the data processing unit 201 to the transceiver unit 206. The frame processing unit 204 also processes the MAC frame input from the transceiver unit 206. For example, if the MAC frame is addressed to a terminal device, the frame processing unit 204 outputs the MAC frame to the data processing unit 201. If the MAC frame is addressed to the shared AP 20, the frame processing unit 204 extracts information (e.g., management information) from the MAC frame and outputs the information to the management unit 202.

[0057] The data processing unit 201 outputs the MAC frame input from the frame processing unit 203 to the frame processing unit 204. The data processing unit 201 also outputs the MAC frame input from the frame processing unit 204 to the frame processing unit 203.

[0058] The transceiver 205 is used for communication with terminal devices such as the terminal device 30. The frequency channel used by the transceiver 205 may be different from the frequency channel used by the transceiver 206. The transceiver 205 performs the same processing as the transceiver 104 of the sharing AP 10 shown in FIG. 6 , and therefore a detailed description of the transceiver 205 will be omitted. The transceiver 205 transmits the MAC frame input from the frame processing unit 203 to the terminal device. The transceiver 205 also receives a wireless signal from the terminal device, extracts the MAC frame from the wireless signal, and outputs the MAC frame to the frame processing unit 203.

[0059] The frame processing unit 203 outputs the MAC frame input from the data processing unit 201 to the transceiver unit 205. The frame processing unit 203 also processes the MAC frame input from the transceiver unit 205. For example, if the MAC frame is addressed to the sharing AP 10, the frame processing unit 203 outputs the MAC frame to the data processing unit 201. If the MAC frame is addressed to the shared AP 20, the frame processing unit 203 extracts information from the MAC frame and outputs the information to the management unit 202. The information may be, for example, information including a measurement value of the time elapsed since the handover was completed.

[0060] The management unit 202 generates a beacon required for multi-AP connection based on information received from the sharing AP 10 and transmits it via the frame processing unit 203 and the transceiver unit 205. Furthermore, the management unit 202 manages wireless connections with affiliated STAs of terminal devices based on information received from the sharing AP 10. The management unit 202 also performs processing to impose a penalty on a terminal device that has executed a handover, which will be described with reference to Figures 9 to 12.

[0061] The terminal management unit 2021 holds terminal information about terminal devices connected to the shared AP 20. For example, the terminal management unit 2021 includes a history of handovers performed by the terminal devices and a measurement value of the time elapsed since the handover of the terminal device was completed. When the handover destination of the terminal device is the shared AP 20, the terminal management unit 2021 measures the time elapsed since the handover of the terminal device was completed. The terminal management unit 2021 notifies the sharing AP 10 of the measurement value of the elapsed time via the frame processing unit 204 and the transceiver unit 206. The management unit 202 can derive the number of times the terminal device has executed handovers within a certain period from the terminal information held by the terminal management unit 2021. The management unit 202 can derive the time elapsed since the handover of the terminal device was completed from the terminal information held by the terminal management unit 2021.

[0062] Fig. 8 schematically illustrates an example of the functional configuration of the terminal device 30. As shown in Fig. 8, the terminal device 30 includes a frame generation unit 301, a frame processing unit 302, a transmission / reception unit 303, and a communication control unit 304. The frame generation unit 301, the frame processing unit 302, and the transmission / reception unit 303 are included in each of the affiliated STAs 31 illustrated in Fig. 1. The communication control unit 304 is included in the non-APMLD 32 illustrated in Fig. 1. The frame generation unit 301, the frame processing unit 302, the transmission / reception unit 303, and the communication control unit 304 can be realized by a wireless communication module 37 or a combination of the CPU 34 and the wireless communication module 37.

[0063] The frame generation unit 301 generates a MAC frame by adding a MAC header to the data input from the non-APMLD 32, and outputs the MAC frame to the transmission / reception unit 303. The MAC header includes a sequence number (SN) assigned to identify the data. The sequence number is output from the transmission buffer of the non-APMLD 32 together with the data.

[0064] The transmitting / receiving unit 303 is used for communication with the shared AP 20. The transmitting / receiving unit 303 performs the same processing as the transmitting / receiving unit 104 of the sharing AP 10 shown in FIG. 6 , and therefore a detailed description of the transmitting / receiving unit 303 will be omitted. The transmitting / receiving unit 303 transmits the MAC frame input from the frame generating unit 301 to the shared AP 20. The transmitting / receiving unit 303 also receives a wireless signal from the shared AP 20, extracts the MAC frame from the wireless signal, and outputs the MAC frame to the frame processing unit 302.

[0065] The frame processing unit 302 receives a MAC frame from the transceiver unit 303, determines whether the data contained in the MAC frame has been received correctly based on the frame check sequence, and if the data has been received correctly, outputs the data to the non-APMLD 32.

[0066] The communication control unit 304 executes processes related to wireless communication such as handover, etc. For example, the communication control unit 304 transmits low-latency traffic in response to receiving a trigger frame from the shared AP 20 that provides a transmission opportunity to the terminal device 30.

[0067] Measurement of the time elapsed since the completion of handover and counting of the number of handovers may be performed by any of the sharing AP 10, the shared AP 20, and the terminal device 30, as long as the measurement and counting can be shared between the sharing AP 10 and the shared AP 20. When the measurement and counting are performed by the terminal device 30, the terminal device 30 transmits information indicating the elapsed time and information indicating the number of handovers to the shared AP 20.

[0068] 9 is a schematic diagram illustrating an example of a method for imposing a penalty on a terminal device 30 that has performed a handover. Here, with reference to the information communication system 50 illustrated in FIG. 1, a situation will be described in which the non-AP MLD 32 of the terminal device 30 performs a handover of the affiliated STA 31-1 of the terminal device 30 from the shared AP 20-2 to the shared AP 20-4, as illustrated in FIG.

[0069] As shown in Figure 9, for each of the shared APs 20-2 and 20-4, R-TWT service periods SP1, SP2, and SP3 are scheduled for a first terminal device group, a second terminal device group, and a third terminal device group, each including a terminal device 30. Specifically, a series of service periods including a service period SP1, a service period SP2 following the service period SP1, and a service period SP3 following the service period SP2 occur periodically. The first terminal device group includes one or more terminal devices in addition to the terminal device 30. Note that, although the service periods are synchronized between the shared APs 20-2 and 20-4 in the example shown in Figure 9, they do not need to be synchronized.

[0070] During the service period SP1, the non-APMLD 32 performs data communication with the shared AP 20-2 through the affiliated STA 31-1. After that, the non-APMLD 32 executes handover for the affiliated STA 31-1, thereby switching the connection destination of the affiliated STA 31-1 from the shared AP 20-2 to the shared AP 20-4.

[0071] In the shared AP 20-4, a service period SP1 occurs before a predetermined time T has elapsed since the completion of the handover of the affiliated STA 31-1. In this case, the shared AP 20-4 skips data communication by the terminal device 30 (specifically, the affiliated STA 31-1) during this service period SP1 and allows data communication by other terminal devices included in the first terminal device group. For example, for this service period SP1, the shared AP 20-4 transmits a trigger frame at the start of the service period SP1 that gives a transmission opportunity to the other terminal devices included in the first terminal device group.

[0072] The next service period SP1 occurs after a predetermined time T has elapsed since the handover of affiliated STA 31-1 was completed. The shared AP 20-4 provides a transmission opportunity to terminal device 30 during this service period SP1. For example, at the start of service period SP1, shared AP 20-4 transmits a trigger frame that designates terminal device 30 as a terminal device capable of data communication during this service period SP1. In response to receiving the trigger frame from shared AP 20-4, non-AP MLD 32 uses affiliated STA 31-1 to transmit low-latency traffic to shared AP 20-4.

[0073] The predetermined time T may be a fixed value or may be variable. For example, as shown in FIG. 10, the shared AP 20-4 determines the predetermined time T according to the number of times the terminal device 30 (specifically, the affiliated STA 31-1) has executed handover during a certain period TI before the time when the handover of the affiliated STA 31-1 is initiated. The more times the affiliated STA 31-1 has executed handover during the certain period TI, the longer the predetermined time T becomes. For example, the predetermined time T is set to T when the number of handovers is 0 or 1. １ , and when the number of handovers is two, T ２ (Here, T ２ >T １ ), and when the number of handovers is three, T ３ (Here, T ３>T ２ )

[0074] Fig. 11 shows an outline of another example of a method for imposing a penalty on a terminal device 30 that has performed a handover. The situation shown in Fig. 11 is similar to that described with reference to Fig. 9. In the description of Fig. 11, the same matters as those described with reference to Fig. 9 will be omitted as appropriate.

[0075] 11, the shared AP 20-4 skips data communication by the terminal device 30 (specifically, the affiliated STA 31-1) during a predetermined number of service periods SP1 that occur after the point in time when the handover of the affiliated STA 31-1 is completed. In this example, the predetermined number of times is one, and the shared AP 20-4 skips data communication by the terminal device 30 during the first service period SP1 that occurs after the handover of the affiliated STA 31-1 is completed.

[0076] The shared AP 20-4 provides the affiliated STA 31-1 with a transmission opportunity for the second service period SP1 that occurs after the handover of the affiliated STA 31-1 is completed.

[0077] The predetermined number of times may be a fixed value or may be variable. For example, the shared AP 20-4 determines the predetermined number of times according to the number of times the terminal device 30 (specifically, the affiliated STA 31-1) has executed handover during a certain period of time TI before the time when the handover of the affiliated STA 31-1 is initiated. The greater the number of times the affiliated STA 31-1 has executed handover during the certain period of time TI, the greater the predetermined number of times. For example, the predetermined number of times is N when the number of handovers is 0 or 1. １ , and when the number of handovers is two, N ２ (Here, N ２ >N １ ), and if the number of handovers is three, N ３ (Here, N ３ >N ２ )

[0078] Fig. 12 schematically shows another example of a method for imposing a penalty on a terminal device 30 that has performed a handover. The situation shown in Fig. 12 is similar to that described with reference to Fig. 9. In the description of Fig. 12, the same matters as those described with reference to Fig. 9 will be omitted as appropriate.

[0079] In the example shown in FIG. 12 , the shared AP 20-4 prohibits handover of the affiliated STA 31-1 for a period of time from the time the handover of the affiliated STA 31-1 is completed until a predetermined time T has elapsed. During this period, the terminal device 30 cannot execute handover of the affiliated STA 31-1. For example, the terminal device 30 transmits a handover request to the sharing AP 10-2 requesting handover of the affiliated STA 31-1. In response to receiving the handover request from the terminal device 30, the sharing AP 10-2 transmits an association notification to the shared AP 20-4. The association notification may include the same information as that included in the handover request. Specifically, the association notification includes information indicating that the connection destination of the affiliated STA 31-1 will be switched from the shared AP 20-4 to another shared AP 20 (e.g., the shared AP 20-2). If the shared AP 20-4 receives the association notification before a predetermined time T has elapsed since the completion of the handover, the shared AP 20-4 rejects the handover. For example, the shared AP 20-4 does not return a response to the association notification, or returns a response indicating that the handover is rejected to the sharing AP 10-2. If the shared AP 20-4 receives the association notification after the predetermined time T has elapsed since the completion of the handover, the shared AP 20-4 accepts the handover. For example, the shared AP 20-4 returns a response indicating that it accepts the handover to the sharing AP 10-2, and disconnects the wireless link with the affiliated STA 31-1 at an appropriate time.

[0080] In this example, the terminal device 30 can perform data communication with the shared AP 20-4 during the first service period SP1 that occurs after the handover of the affiliated STA 31-1 is completed.

[0081] The predetermined time T may be a fixed value or may be variable. For example, the shared AP 20-4 determines the predetermined time T based on the number of times the terminal device 30 (specifically, the affiliated STA 31-1) has performed handover during a certain period TI before the time when the handover of the affiliated STA 31-1 was initiated. The greater the number of times the affiliated STA 31-1 has performed handover during the certain period TI, the longer the predetermined time T becomes.

[0082] In some of the examples described above, the entity that imposes a penalty on the terminal device that performed the handover is the shared AP 20. In other examples, the entity may be the sharing AP 10. For example, in the example described with reference to FIG. 12, when the sharing AP 10-2 receives a handover request from the terminal device 30, it determines whether to accept or reject the request depending on the time that has elapsed since the completion of the handover. If the sharing AP 10-2 determines to reject the request, it transmits a response rejecting the request to the terminal device 30 without transmitting an association notification to the shared APs 20-3 and 20-4. If the sharing AP 10-2 determines to accept the request, it transmits an association notification to the shared APs 20-3 and 20-4.

[0083] As described above, in this embodiment, in a situation where a service period during which data communication can be performed for the shared AP 20-4 is scheduled for a group of terminal devices including the terminal device 30, the management unit 202 of the shared AP 20-4 skips data communication by the terminal device during the service period that occurs after the completion of handover of the terminal device 30 from the shared AP 20-2 to the shared AP 20-4. In one example, the shared AP 20-4 skips data communication by the terminal device 30 during the service period that occurs (specifically, starts) from the completion of the handover until a predetermined time has elapsed. In another example, the shared AP 20-4 skips data communication by the terminal device 30 during a predetermined number of service periods that occur after the completion of the handover.

[0084] According to the above configuration, the terminal device 30 cannot acquire a transmission opportunity during the service period immediately after the handover is completed. Therefore, it is possible to prevent the terminal device 30 from performing drift in order to acquire a transmission opportunity. As a result, it is possible to prevent the effect of R-TWT from being reduced.

[0085] In yet another example, the shared AP 20-4 prohibits the terminal device 30 from handing over from the shared AP 20-4 to another shared AP 20 (e.g., the shared AP 20-2) until a predetermined time has elapsed since the completion of the handover. This configuration suppresses the execution of a handover by the terminal device 30. Therefore, it is possible to prevent or suppress the terminal device 30 from drifting to acquire a transmission opportunity. As a result, it is possible to prevent a decrease in the effectiveness of R-TWT.

[0086] In the above-described embodiment, a system configuration is adopted in which a sharing AP 10 controls or manages multiple shared APs 20, and each shared AP 20 relays communication between the sharing AP 10 and a terminal device 30, as shown in Fig. 1. The system configuration shown in Fig. 1 is an example, and other system configurations may be adopted. For example, a system may be configured in which multiple access points are provided, and each access point is connected to a network 40 and wirelessly connected to a terminal device 30.

[0087] In the above-described embodiment, the terminal device 30 includes a plurality of affiliated STAs 31. In other embodiments, the terminal device 30 may include a single affiliated STA 31.

[0088] 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.

[0089] DESCRIPTION OF SYMBOLS 10... Sharing access point 11, 21, 34... CPU 12, 22, 35... ROM 13, 23, 36... RAM 14, 24, 25, 37... Wireless communication module 15... Wired communication module 20... Shared access point 30... Terminal device 31... Affiliated STA 32... Non-AP MLD 38... Display 39... Storage 40... Network 50... Information communication system 101, 201... Data processing unit 102, 202... Management unit 103, 203, 204, 302... Frame processing unit 104, 205, 206, 303... Transmitting / receiving unit 301... Frame generation unit 304... Communication control unit 1021, 2021... Terminal management unit

Claims

1. An access point, comprising a management unit that skips data communication by the terminal device during a service period that occurs after a handover of the terminal device from another access point to the access point is completed, wherein the service period during which data communication can be performed for the access point is scheduled for a group of terminal devices including the terminal device.

2. The access point according to claim 1, wherein the management unit skips data communication by the terminal device during the service period that occurs until a predetermined time has elapsed from the time point.

3. The access point according to claim 2, wherein the management unit determines the predetermined time according to the number of handovers performed by the terminal device within a certain period.

4. The access point according to claim 1, wherein the management unit skips data communication by the terminal device during a predetermined number of service periods that occur after the time point.

5. The access point according to claim 4, wherein the management unit determines the predetermined number according to the number of handovers performed by the terminal device within a certain period.

6. The access point according to claim 1, wherein skipping data communication by the terminal device includes not giving a transmission opportunity to the terminal device.

7. The access point according to claim 1, wherein the management unit transmits a trigger signal that gives a transmission opportunity to other terminal devices included in the group of terminal devices at the start of the service period in order to skip data communication by the terminal device.

8. For each of a first access point and a second access point, a service period during which data communication can be performed is scheduled for a group of terminal devices including the terminal device, and a management unit that prohibits a handover of the terminal device from the second access point to the first access point until a predetermined time has elapsed from the time point when the handover of the terminal device from the first access point to the second access point is completed.

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