Communication device, terminal device, and communication method

Abstract

A communication device can a second communication device and can include a control unit configured to receive, from a first communication device, a second switching request signal for requesting switching a connection destination from the first communication device to the second communication device in response to a first switching request signal transmitted from a terminal device connected to the first communication device to the first communication device, and transmit, to the terminal device, a trigger signal for the terminal device to transmit data together with a switching response signal in response to switching from the first communication device to the second communication device based on the second switching request signal.

Description

COMMUNICATION DEVICE, TERMINAL DEVICE, AND COMMUNICATION METHOD

[0001] The present disclosure relates to a communication device, a terminal device, and a communication method.

[0002] In recent years, in various use cases such as homes, offices, and factories, environments in which a plurality of access points (hereinafter referred to as an AP) are installed and high-speed and highly reliable Wi-Fi (registered trademark) networks are constructed have been increasing.

[0003] In such environments in which a plurality of APs are installed, terminal devices (stations or station terminals, hereinafter referred to as STAs) can continue good communication, for example, by selecting APs with good communication quality and executing handover processing. Hereinafter, switching the APs that are connection destinations may be referred to as AP switching.

[0004] For example, as an example of handover processing, in IEEE 802.11be / Multi-Link Operation, a seamless Handover operation using a defined multi-link device (MLD) entity has been studied. Seamless handover enables an STA to continuously receive downlink (DL) data transmitted from an AP.

[0005] Guogang Huang, et al. "Thoughts on Seamless Roaming Under Non-collocated AP MLD Architecture", IEEE 802.11-23 / 0231r0, February 20, 2023Duncan Ho, et al. "Seamless Roaming details", IEEE 802.11-24 / 52r0, January 12, 2024Thomas Derham, et al. "Thoughts on functionality and security architecture for UHR seamless roaming", IEEE 802.11-24 / 0679r4, September 12, 2024Binita Gupta et al. "Seamless Roaming within a Mobility Domain-Follow Up", IEEE 802.11-24 / 0396r2, May 13, 2024Summary

[0006] However, in handover processing of the related art, in the uplink (UL) communication from the STA to the AP, an interruption period (hereinafter referred to as an UL communication interruption period) may occur. Therefore, for example, when low-delay traffic occurs during the UL communication interruption period, the STA has to transmit the low-delay traffic after the UL communication interruption period, and data continuity cannot be guaranteed in some cases.

[0007] Accordingly, the present disclosure proposes a communication device, a terminal device, and a communication method capable of guaranteeing data continuity.

[0008] The above problem or object is merely one of a plurality of problems or objects that can be solved or achieved by the plurality of embodiments disclosed in the present specification.

[0009] To solve the problem described above, a communication device according to one aspect of the present disclosure is a second communication device including a control unit or control circuitry configured to receive, from a first communication device, a second switching request signal for requesting switching a connection destination from the first communication device to the second communication device in response to a first switching request signal transmitted from a terminal device (which may be connected to the first communication device) to the first communication device, and transmit, to the terminal device, a trigger signal for the terminal device to transmit data together with a switching response signal in response to switching from the first communication device to the second communication device based on the second switching request signal.

[0010] Fig. 1 is a diagram illustrating an example of a communication system according to the present disclosure.Fig. 2 is a diagram illustrating an example of an AP switching process using Single Link.Fig. 3 is a diagram illustrating an example of an AP switching process using Dual Link.Fig. 4 is a block diagram illustrating a configuration example of an AP according to an embodiment of the present disclosure.Fig. 5 is a block diagram illustrating a configuration example of an STA according to an embodiment of the present disclosure.Fig. 6 is a diagram illustrating an example of an AP switching process using a trigger signal according to a first embodiment.Fig. 7 is a diagram illustrating an example of an AP switching process when a transmittable frame is used according to the first embodiment.Fig. 8 is a diagram illustrating an example of a frame configuration of a switching request signal according to the first embodiment.Fig. 9 is a diagram illustrating an example of an AP switching process using notification information according to the first embodiment.Fig. 10 is a diagram illustrating an example of an A-control field format according to the first embodiment.Fig. 11 is a diagram illustrating an example of a format when an element is used according to the first embodiment.Fig. 12 is a diagram illustrating an example of an AP switching process when an operation after AP switching is notified according to the first embodiment.Fig. 13 is a diagram illustrating an example of a frame configuration of a switching response signal according to the first embodiment.Fig. 14 is a flowchart illustrating an example of a flow of an STA-side switching process according to the first embodiment.Fig. 15 is a flowchart illustrating an example of a flow of an AP-side switching process according to the first embodiment.Fig. 16 is a diagram illustrating an example of an AP switching process according to a second embodiment.Fig. 17 is a flowchart illustrating an example of a flow of an STA-side switching process according to the second embodiment.Fig. 18 is a flowchart illustrating an example of a flow of an AP-side switching process on the according to the second embodiment.Fig. 19 is a diagram illustrating an example of an AP switching process according to a third embodiment.Fig. 20 is a flowchart illustrating an example of a flow of an STA-side switching process according to the third embodiment.Fig. 21 is a flowchart illustrating an example of a flow of an AP-side switching process according to the third embodiment.Fig. 22 is a diagram illustrating an example of an AP switching process according to a modification.Fig. 23 is a block diagram illustrating a hardware configuration example of a computer that executes the above-described series of processes by a program.Fig. 24 is a block diagram illustrating an overall configuration example of a smartphone to which the present technique is applied.Fig. 25 is a block diagram illustrating an example of an overall configuration of an in-vehicle device to which the present technique is applied.Fig. 26 is a block diagram illustrating an example of an overall configuration of radio to which the present technique is applied.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each of the following embodiments, the same portions are denoted by the same reference numerals, and repeated description thereof will be omitted.

[0012] In the present specification and the drawings, similar constituents of the embodiments may be distinguished by adding at least one of different alphabets and numbers after the same reference numeral. However, when it is not necessary to particularly distinguish similar constituents from each other, only the same reference numeral is assigned.

[0013] One or a plurality of embodiments (including examples, modifications, and application examples) to be described below can each be implemented independently. On the other hand, at least some of the plurality of embodiments to be described below may be appropriately combined with at least some of other embodiments. The plurality of embodiments may include novel features different from each other. Accordingly, the plurality of embodiments can contribute to solving different objects or problems, and thus it is possible to different effects.

[0014] The present disclosure will be described according to the following order of items. 1. Introduction 1-1. Background 1-2. Communication system 1-3. Overview of embodiment 2. Configuration example of communication system 2-1. Configuration example of AP 2-2. Configuration Example of STA 3. Processing example of communication System 3-1. First embodiment 3-1-1. Processing according to first embodiment 3-1-2. Limitation of transmissible Frames 3-1-3. Information exchange 3-1-4. Operation after end of AP switching 3-1-5. Flowchart illustrating procedure of STA-side switching process according to first embodiment 3-1-6. Flowchart illustrating procedure of AP-side switching process according to first embodiment 3-2. Second embodiment 3-2-1. Process according to second embodiment 3-2-2. Flowchart illustrating procedure of STA-side switching process according to second embodiment 3-2-3. Flowchart illustrating procedure of AP-side switching process according to second embodiment 3-3. Third embodiment 3-3-1. Process according to Third Embodiment 3-3-2. Flowchart illustrating procedure of STA-side switching process according to third embodiment 3-3-3. Flowchart illustrating procedure of AP-side switching process according to third embodiment 3-4. Modification according to embodiment 3-4-1. Other processes 4. Other embodiments 5. Effects of communication device according to present disclosure 6. Configuration example of computer 7. Application example

[0015] (1. Introduction) (1-1. Background) In recent years, cases where a plurality of APs are used to expand Wi-Fi coverage and implement stable communication have been increasing. In particular, in a case where wide communication coverage is required in an office environment, a school, a factory, or the like, a large-scale network may be constructed using a plurality of APs and a wireless LAN controller that manages the plurality of APs.

[0016] In such a case, the STA sometimes switches an AP that is a connection destination in order to avoid traffic concentration due to movement of the STA or an increase in the number of STAs connected to the AP. At that time, a discussion on seamless roaming for seamlessly executing AP switching and guaranteeing data continuity has been made in IEEE 802.11bn corresponding to Wi-Fi 8.

[0017] In IEEE 802.11be corresponding to Wi-Fi 7, a multi-link Operation (MLO) is adopted. The MLO is a wireless communication method using a plurality of links (frequency bands). A device compatible with the MLO is called a multi-link device (MLD). An MLD can coordinate multiple radio interfaces and establish multiple links.

[0018] An MLD divides a medium access control (MAC) sublayer into multiple (for example, two) functional groups. For example, the MLD divides the MAC sublayer into two function groups of upper-MAC (U-MAC) and lower-MAC (L-MAC).

[0019] The U-MAC is a common processing unit for all interfaces. For example, the U-MAC has a function of managing a network and a sequence number. The L-MAC is an independent processing unit for each interface. The L-MAC has, for example, a function of executing channel access that operates independently in each wireless interface. As described above, the MLD can implement low-delay, high reliable transmission, and high throughput by utilizing a plurality of links.

[0020] As a method capable of implementing seamless roaming, IEEE 802.11bn proposes a method of utilizing an architecture of a centralized system in which the U-MAC is shared by a plurality of APs. However, there is a concern about feasibility of an architecture in which the U-MAC and the L-MAC and lower layers are distributed in terms of locations from the viewpoint of complexity. In this method, the MLD has been discussed on the premise.

[0021] Additionally, in IEEE 802.11bn, a method of implementing seamless roaming by extension of Fast Transition (FT) has been discussed. The FT is a function that has already been defined in the standard of IEEE 802.11, and AP switching can be implemented in about 5 to 10 ms in a best case by simplifying an extensible authentication protocol (EAP) and 4-way-handshake. However, the FT may not be achieved in most cases, and a data loss occurs (see IEEE 802.11-23 / 2157r2, Nov. 27, 2023). In this method, the MLD has also been discussed on the premise.

[0022] In order to guarantee data continuity, it is necessary to share context information such as block ack information and capability information between an AP that is a connection destination after AP switching and an AP that is a connection source before AP switching. In an example of a contribution (IEEE 802.11-24 / 52r0, Jan. 12, 2024), an AP switching method of utilizing an MLD and sharing context information has been proposed.

[0023] (1-2. Communication system) Here, a communication system assumed in the present disclosure will be described with reference to Fig. 1. Fig. 1 is a diagram illustrating an example of a communication system according to the present disclosure. The communication system illustrated in Fig. 1 includes a plurality of APs 100 (in Fig. 1, a first AP 100A and a second AP 100B are illustrated), a plurality of STAs 200(in Fig. 1, first to third STAs 200A to 200C), and a controller 300. Some or all of the controller 300 may be implemented in or using circuitry.

[0024] In the example of Fig. 1, the first STA 200A is a head mounted display (HMD). In the example of Fig. 1, the second STA 200B is a smartphone. In the example of Fig. 1, the third STA 200C is an HMD.

[0025] The HMD is used, for example, to provide a virtual reality (VR) service. Therefore, the HMD is required to have low delay, high reliability, and high throughput for DL communication, and is required to have low delay and high reliability for UL communication.

[0026] In the example of Fig. 1, the first STA 200A is located within communication ranges of the first AP 100A and the second AP 100B. For example, it is assumed that the first STA 200A communicates with the second AP 100B. In this case, the first STA 200A switches the AP to be connected from the second AP 100B to the first AP 100A.

[0027] In the example of Fig. 1, the second STA 200B is located within the communication range of the first AP 100A and communicates with the first AP 100A. In the example of Fig. 1, the third STA 200C is located within the communication range of the second AP 100B and communicates with the second AP 100B.

[0028] The first STA 200A that switches the AP 100 is not limited to the HMD. The first STA 200A may be any device as long as low delay is required and may be, for example, an industrial internet of things (IoT) device or the like.

[0029] The example of Fig. 1 is an example in which the number of APs 100 is 2, but the number of APs 100 is not limited thereto. The number of APs 100 may be 3 or more. The number of STAs 200 is not limited to 3. The number of STAs 200 may be 2 or less or may be 4 or more. The controller 300 may be a part of the AP 100. That is, the AP 100 may have the function of the controller 300.

[0030] Backhaul communication for connecting the APs 100, and the APs 100 and the controller 300 may be wired communication or wireless communication. The AP 100 and the STA 200 are MLD. Note that, in the current standardization, an STA that desires to execute AP switching executes AP switching while maintaining State 4 (Authenticated / Associated / IEEE802.1X controlled port unblocked).

[0031] (1-3. Overview of embodiment) In the above communication system, the STA 200 switches the AP 100 in order to make connection with the AP 100 in a good channel state when the STA 200 moves or in order to execute traffic distribution when the number of STAs 200 connected to the AP 100 is large. For example, after disconnecting (disassociating) the connection with the first AP 100 (hereinafter, the source AP is referred to as a source AP) to which the STA 200 (hereinafter referred to as a roaming STA) to be subjected to AP switching has been connected, connection (association) with the second AP 100 (hereinafter, the target AP is referred to as a target AP) as a new connection destination is executed. In this way, the roaming STA executes AP switching. However, in this case, since there are many frames to be exchanged, a time until completion of AP switching becomes long, which results in occurrence of a data loss.

[0032] Hereinafter, a case where Single Link is utilized and a case where Dual Link is utilized will be described separately. Here, Single Link indicates, for example, a case where there is normally only one AP to which the roaming STA can be connected. Dual Link indicates, for example, a case where the roaming STA is temporarily connected to two APs. Hereinafter, the controller 300 may be referred to as a controller.

[0033] First, a case where Single Link is utilized will be described. In a method of utilizing Single Link, before link switching, the source AP transmits all DL traffic buffered in the source AP to the roaming STA before data path switching is executed. The source AP then disables the link with the roaming STA. Then, the roaming STA enables a link with a new target AP. Therefore, the traffic buffered in the target AP cannot be transmitted until the enabling of the link with the target AP is completed after the data path switching is executed. Accordingly, a delay time of the DL traffic increases. There is a period in which the UL traffic cannot be transmitted, and a transmission delay of the UL traffic also increases.

[0034] A specific example of the AP switching when Single Link is utilized will be described with reference to Fig. 2. Fig. 2 is a diagram illustrating an example of an AP switching process using Single Link. In Fig. 2, it is assumed that the STA 200 that requires low-delay transmission in UL traffic (an example of data) such as VR or an industrial IoT device executes the AP switching in an environment where there are a plurality of APs 100.

[0035] In the example of Fig. 2, the roaming STA determines execution of the AP switching at time t1. For example, in the case of STA initiated roaming, the roaming STA transmits a switching request signal (corresponding to a roaming request in Fig. 2) for requesting the source AP to switch the AP. In the example of Fig. 2, the roaming STA transmits a switching request signal to the source AP at time t3. The switching request signal is an example of a first switching request signal.

[0036] Then, when the source AP correctly receives the switching request signal from the roaming STA, the AP switching is started. In the example of Fig. 2, the source AP receives the switching request signal from the roaming STA. Subsequently, in a case where it is determined that the source AP correctly receives the switching request signal, AP switching is started. Subsequently, the source AP transmits a switching request signal to the Controller, and the Controller transmits Context information to the target AP. The switching request signal is an example of a second switching request signal. In the target AP, a link is added at time t2, but a link state is disabled until time t5.

[0037] Here, since there is a possibility of the UL traffic not being correctly transmitted to an upper layer during the AP switching, the UL communication is interrupted. When the UL is transmitted to the source AP during the UL communication interruption period, a context shared between the source AP and the target AP changes. Therefore, the UL communication is interrupted. In the example of Fig. 2, a period in which the UL communication is interrupted corresponds to UL suspension. Hereinafter, the period during which the UL is interrupted may be referred to as an UL communication interruption period.

[0038] Then, after preparation for the AP switching between the source AP and the target AP is completed (context transfer / data path switching), the source AP receives a switching response signal (corresponding to a roaming response in Fig. 2) in response to the switching of the AP 100 from the controller, and then transmits the switching response signal to the roaming STA. In the example of Fig. 2, the source AP transmits a switching response signal to the roaming STA at time t4. Accordingly, the roaming STA can resume the UL communication.

[0039] As described above, when low-delay traffic is generated in the roaming STA during the UL communication interruption period or before the UL communication interruption period and the low-delay traffic is held during the UL communication interruption period, the low-delay traffic cannot be transmitted until the end of AP switching. Therefore, there is a possibility of a delay requirement not being satisfiable and continuity of the data not being guaranteeable.

[0040] In the example of Fig. 2, the example in which the roaming STA transmits the switching request signal to the source AP has been described, but the roaming STA may transmit the switching request signal to the target AP. In the example of Fig. 2, the example in which the roaming STA transmits the switching request signal has been described, but there may be a case where the AP 100 (for example, the source AP, the target AP, or the like) is AP Initiated roaming in which the switching request signal is transmitted. In the example of Fig. 2, the source AP may transmit a response to the switching request signal to the roaming STA.

[0041] Next, a case where Dual Link is utilized will be described. In the method utilizing Dual Link, after Data Path Switching during AP switching, the roaming STA enables another link different from the source AP with the target AP. The source AP can transmit data buffered in the source AP before the data path switching. In addition, the target AP can transmit data to be newly buffered in the target AP after the data path switching. Accordingly, delay of the DL can be reduced. Thereafter, after transmitting all the traffic buffered in the source AP, the roaming STA disables the link with the source AP. Even when Dual Link is used, there is a period in which the UL traffic cannot be transmitted as in the case of the Single Link.

[0042] A specific example of the AP switching in a case where Dual Link is utilized will be described with reference to Fig. 3. Fig. 3 is a diagram illustrating an example of an AP switching process using Dual Link. In Fig. 3, it is assumed that the STA 200 that requires low-delay transmission for UL traffic executes the AP switching in an environment where there are a plurality of APs 100 and STAs 200.

[0043] In the example of Fig. 3, the STA 200 that requires low-delay transmission for UL traffic is a roaming STA. The STA 200 different from the roaming STA is another roaming STA. In the example of Fig. 3, it is assumed that the other Roaming STA has already executed the AP switching. In this case, the roaming STA executes the AP switching.

[0044] In the case of the STA initiated roaming, the roaming STA transmits a switch request signal for requesting the source AP to switch the AP. In the example of Fig. 3, the roaming STA transmits a switch request signal to the source AP at time t11. Subsequently, when the source AP correctly receives the switching request signal from the roaming STA, the AP switching starts. In the example of Fig. 3, the source AP receives the switching request signal from the roaming STA. Then, when it is determined that the source AP correctly receives the switching request signal, the AP switching starts. Subsequently, in the roaming STA, UL traffic is generated at time t12. Then, in the other roaming STA, the UL traffic is generated at time t13.

[0045] Subsequently, the source AP transmits a switching response signal to the other Roaming STA at time t14. Then, after the preparation of the AP switching between the source AP and the target AP is completed, the source AP transmits a switching response signal to the roaming STA in response to the switching of the AP. In the example of Fig. 3, the source AP transmits a switching response signal to the roaming STA at time t15.

[0046] In this case, since the other roaming STA resumes the UL communication at time t16, the roaming STA cannot transmit the UL communication. That is, the roaming STA cannot transmit the UL traffic generated at time t12 to the target AP. Therefore, the roaming STA cannot meet the delay requirement.

[0047] As described above, when the plurality of STAs 200 simultaneously start the AP switching, there is a possibility of channel contention occurring between the plurality of STAs 200 before and after the STA 200 that requires low-delay for the UL receives the switching response signal. In this case, a collision between the plurality of STAs 200 may occur, or an interruption to transmission may occur by another STA 200 that does not require low-delay. Accordingly, there is a possibility of the roaming STA not being able to transmit UL traffic with low delay. There is a possibility of continuity of data not being guaranteeable.

[0048] Thus, to solve an example of the above problem, the present disclosure proposes, for example, a communication device that transmits, to a roaming STA, a trigger signal for the roaming STA to transmit data together with a switching response signal in response to switching from a source AP to a target AP based on a switching request signal. Accordingly, the present disclosure can guarantee continuity of data.

[0049] (2. Configuration example of communication system) (2-1. Configuration example of AP) Fig. 4 is a block diagram illustrating a configuration example of the AP 100 (an example of a communication device) according to the embodiment of the present disclosure. The AP 100 includes a wireless communication unit 110, a backhaul communication unit 120, a storage unit 130, and a control unit 140. The storage unit 130 can be regarded as memory and the control unit 140 can be regarded as one or more controllers, circuitry, and / or control circuitry.

[0050] (Wireless communication unit 110) The wireless communication unit 110 is a communication unit that executes wireless communication with another wireless communication device (for example, the STA 200). The wireless communication unit 110 communicates with the STA 200 in conformity with, for example, a wireless local area network (LAN) standard such as Wi-Fi.

[0051] The wireless communication unit 110 includes a common media access control (MAC) processing unit 111, individual MAC processing units 112A and 112B, signal processing units 113A and 113B, radio frequency (RF) units 114A and 114B, RF switches 115A and 115B, antennas 118A_1, 118A_2, 118B_1, and 118B_2, and a communication control unit 116.

[0052] The configuration of the wireless communication unit 110 illustrated in Fig. 4 is exemplary, and the present disclosure is not limited thereto. The wireless communication unit 110 may include some or all of the common MAC processing unit 111, the individual MAC processing unit 112, the signal processing unit 113, the RF unit 114, the RF switch 115, the antenna 118, and the communication control unit 116.

[0053] Hereinafter, the individual MAC processing unit 112A, the signal processing unit 113A, the RF unit 114A, and the RF switch 115A are collectively referred to as a first processing unit 117A. The individual MAC processing unit 112B, the signal processing unit 113B, the RF unit 114B, and the RF switch 115B are collectively referred to as a second processing unit 117B. When the first processing unit 117A and the second processing unit 117B are not distinguished from each other, they are also simply referred to as the processing unit 117. The processing unit 117 may include some or all of the individual MAC processing unit 112, the signal processing unit 113, the RF unit 114, and the RF switch 115.

[0054] As described above, the AP 100 in Fig. 4 includes two processing units 117. That is, the AP 100 is an MLD that can be connected by two different links. Here, the number of links to which the AP 100 can be connected is 2, but the number of links to which the AP 100 can be connected may be 3 or more. In this case, the AP 100 includes the number of links to which the processing unit 117 can be connected.

[0055] Operations of the first processing unit 117A and the second processing unit 117B are the same. Therefore, here, the first processing unit 117A will be described, and the description of the second processing unit 117B will be omitted.

[0056] (Common MAC processing unit 111) The common MAC processor unit 111 executes a process on the data. For example, the common MAC processing unit 111 executes at least some of the MAC processes for media access control (MAC).

[0057] The common MAC processing unit 111 executes sequence management of data, and control information and management information received from the communication control unit 116 during transmission, and executes an encryption process or the like to generate a data unit. During reception, the common MAC processing unit 111 executes a decoding process, and then executes a retransmission request operation and a reordering process.

[0058] These processes are also collectively referred to as common data processing (Upper MAC (U-MAC) processing). Note that the controller 300 may execute at least part of the common data processing. When the controller 300 normally executes the common data processing, the common MAC processing unit 111 (a processing unit that executes common data processing) can be omitted.

[0059] (Individual MAC processing unit 112A) The individual MAC processing unit 112A executes at least some of the MAC processing for media access control. The individual MAC processing unit 112A executes a process other than a process executed by the common MAC processing unit 111 in the MAC processing.

[0060] The individual MAC processing unit 112A receives data (for example, a data unit) subjected to encryption and addition of a sequence number from the common MAC processing unit 111, and executes the following process (individual data processing to be described below) on the received data.

[0061] During transmission, the individual MAC processing unit 112A adds a MAC header and an error detection code to an encrypted packet to generate a MAC frame. The individual MAC processing unit 112A executes a plurality of MAC frame coupling process. The individual MAC processing unit 112A executes a decoupling process, error detection, and a retransmission request operation of the MAC header of the received MAC frame during reception. The individual MAC processing unit 112A executes a channel access operation based on carrier sensing.

[0062] These processes are also collectively referred to as individual data processing (lower MAC (L-MAC) process). Even when the controller 300 executes at least a part of the common data processing, the individual data processing is executed by the individual MAC processing unit 112A, that is, the AP 100.

[0063] As in Fig. 4, when the AP 100 is an MLD, that is, when the AP 100 is connected to a plurality of links, the common MAC processing unit 111 and the individual MAC processing unit 112A can be configured as different processing units.

[0064] (Signal processing unit 113A) The signal processing unit 113A executes a process in a physical layer (PHY). The signal processing unit 113A executes encoding, interleaving, modulation, and the like during transmission, and adds a physical header to generate a symbol stream.

[0065] During reception, the signal processing unit 113A analyzes the physical header and executes demodulation, deinterleaving, decoding, and the like on the symbol stream to generate a MAC frame. The signal processing unit 113A executes complex channel characteristic estimation and spatial separation processing as necessary.

[0066] (RF unit 114A) Although not illustrated, the RF unit 114A includes a transmission RF unit (Tx RF) and a reception RF unit (Rx RF). The transmission RF unit executes digital-to-analog signal conversion, filtering, up-conversion using a local oscillator (not illustrated), and phase control on the symbol stream to generate a transmission signal.

[0067] The reception RF unit executes down-conversion, filtering, and analog-digital signal conversion on the reception signal using a local oscillator (not illustrated) to generate a symbol stream.

[0068] (RF switch 115A) The RF switch 115A switches between transmission and reception. For example, the RF switch 115A switches the RF unit connected to the antennas 118A_1 and 118A_2 among the transmission and reception RF units.

[0069] In Fig. 4, the number of antennas 118A_1 and 118A_2 connected to the RF switch 115A is 2, but the number of antennas is not limited to 2. The number of antennas connected to the RF switch 115A may be 1 or 3 or more.

[0070] (Communication control unit 116) The communication control unit 116 controls an operation of each unit of the wireless communication unit 110 and information transmission between the units. The communication control unit 116 executes control to pass control information and management information of which the STA 200 is notified to the common MAC processing unit 111.

[0071] A function of executing the above-described common data processing (common MAC processor unit 111) is also referred to as an "AP MLD entity." Furthermore, (the individual MAC processing unit 112A, the signal processing unit 113A, and the RF unit 114A) from the function of executing individual data processing to the function of amplifying a signal is also referred to as an "AP Entity (APx)". The AP 100 may include a plurality of AP entities belonging to AP MLD entity.

[0072] For example, when the AP 100 functions as a roaming AP MLD entity, the AP 100 executes common data processing of another AP 100 in the AP MLD entity. That is, the AP MLD entity can function as a roaming AP MLD entity.

[0073] Here, the roaming AP MLD entity uniformly manages a connection relationship between the STA 200 and the AP 100 belonging to the roaming AP MLD entity. Therefore, the APs 100 (for example, the first AP 100A and the second AP 100B) belonging to the roaming AP MLD entity can omit the reconnection process / reauthentication process with the first STA 200A when the handover processing (an AP switching process) is executed.

[0074] In Fig. 4, the wireless communication unit 110 is mounted on the AP 100 as one integrated circuit (IC), but the configuration of the wireless communication unit 110 is not limited thereto. For example, the wireless communication unit 110 may include a plurality of ICs or individual components. For example, the RF unit 114A, the RF switch 115A, and the antennas 118A_1 and 118A_2 may be mounted on the AP 100 as an IC or an individual component different from other constituents of the wireless communication unit 110.

[0075] (Backhaul Communication Unit 120) The backhaul communication unit 120 is a communication unit that communicates with another AP 100, a router (not illustrated), and the controller 300. The backhaul communication unit 120 executes communication between a backhaul network and a fronthaul network (a network between the AP 100 and the STA 200).

[0076] The backhaul communication unit 120 can communicate with another AP 100, a router, or the controller 300 by wire using an optical fiber, an Ethernet (registered trademark) cable, or the like. Alternatively, the backhaul communication unit 120 may execute wireless communication with these devices.

[0077] The backhaul communication unit 120 decodes a packet acquired via a backhaul link and outputs the packet to the wireless communication unit 110 through the control unit 140. Here, the packet output to the wireless communication unit 110 may be a packet in which an IP Header is left as it is (access point mode) or may be a packet in which the IP Header is decoded and removed by the backhaul communication unit 120 (router mode). In the present embodiment, the AP 100 exchanges information with another AP 100 (communicates with another AP 100) via the backhaul communication unit 120.

[0078] The control link (a link between the controller 300 and another AP 100) may be formed using the wireless communication unit 110 or may be formed using the backhaul communication unit 120.

[0079] (Storage unit 130) The storage unit 130 is a storage device capable of reading and writing data, such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a flash memory, or a hard disk. The storage unit 130 holds information used by the control unit 140 and the wireless communication unit 110.

[0080] The storage unit 130 executes queuing of a signal from an upper layer, buffering of a received signal, and the like. The storage unit 130 holds data and the like when the signal processing unit 113A executes a combining process.

[0081] (Control unit 140) The control unit 140 is a controller that controls each unit of the AP 100. Instead, the control unit 140 may execute some of operations of the communication control unit 116. The communication control unit 116 and the control unit 140 may be configured as one block.

[0082] The control unit 140 may have any configuration included in the AP 100. The control unit 140 may be provided inside another device (for example, the controller 300) different from the AP 100.

[0083] The control unit 140 may be implemented by, for example, a processor such as a central processing unit (CPU) or a micro processing unit (MPU).

[0084] Specifically, the control unit 140 may be implemented by a processor executing various programs stored in a storage device inside the AP 100 using a random access memory (RAM) or the like as a work area.

[0085] The control unit 140 may be implemented by an integrated circuit such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The control unit 140 may be implemented by a graphics processing unit (GPU).

[0086] Any of the CPU, the MPU, the ASIC, the FPGA, and the GPU can be regarded as a controller. The control unit 140 may include a plurality of physically separated objects. For example, the control unit 140 may include a plurality of semiconductor chips.

[0087] (2-2. Configuration example of STA) Fig. 5 is a block diagram illustrating a configuration example of the STA 200 (an example of a terminal device) according to an embodiment of the present disclosure. The STA 200 includes a wireless communication unit 210, a storage unit 220, and a control unit 230. The storage unit 220 can be regarded as memory and the control unit 230 can be regarded as one or more controllers, circuitry, and / or control circuitry.

[0088] (Wireless communication unit 210) The wireless communication unit 210 is a communication unit that executes wireless communication with another wireless communication device (for example, the AP 100). The wireless communication unit 210 communicates with the AP 100 in conformity with, for example, a wireless local area network (LAN) standard such as Wi-Fi.

[0089] The wireless communication unit 210 includes a common MAC processing unit 211, individual MAC processing units 212A and 212B, signal processing units 213A and 213B, radio frequency (RF) units 214A and 214B, RF switches 215A and 215B, antennas 218A_1, 218A_2, 218B_1, and 218B_2, and a communication control unit 216.

[0090] The configuration of the wireless communication unit 210 illustrated in Fig. 5 is exemplary, and the present disclosure is not limited thereto. The wireless communication unit 210 may include some or all of the common MAC processing unit 211, the individual MAC processing unit 212, the signal processing unit 213, the RF unit 214, the RF switch 215, the antenna 218, and the communication control unit 216.

[0091] Hereinafter, the individual MAC processing unit 212A, the signal processing unit 213A, the RF unit 214A, and the RF switch 215A are collectively referred to as a first processing unit 217A. The individual MAC processing unit 212B, the signal processing unit 213B, the RF unit 214B, and the RF switch 215B are collectively referred to as a second processing unit 217B. When the first processing unit 217A and the second processing unit 217B are not distinguished from each other, they are also simply referred to as the processing unit 217. The processing unit 217 may include some or all of the individual MAC processing unit 212, the signal processing unit 213, the RF unit 214, and the RF switch 215.

[0092] As described above, the STA 200 in Fig. 5 includes two processing units 217. That is, the STA 200 is an MLD that can be connected by two different links.

[0093] Here, the number of links to which the STA 200 can be connected is 2, but the number of links to which the STA 200 can be connected may be 3 or more. In this case, the STA 200 includes the number of links to which the processing unit 217 can be connected.

[0094] Here, the operations of the first processing unit 217A and the second processing unit 217B are the same. Therefore, here, the first processing unit 217A will be described, and the description of the second processing unit 217B will be omitted.

[0095] (Common MAC processing unit 211) The common MAC processor unit 211 executes a process on the data. For example, the common MAC processing unit 211 executes at least some of the MAC processes for media access control (MAC).

[0096] The common MAC processing unit 211 executes common data processing (U-MAC processing) as in the common MAC processing unit 111 of the AP 100. The common MAC processing unit 211 executes, for example, data processing common to the first processing unit 217A and the second processing unit 217B.

[0097] (Individual MAC processing unit 212A) The individual MAC processing unit 212A executes at least some of the MAC processing for media access control. The individual MAC processing unit 212A executes a process other than the processing executed by the common MAC processing unit 211 in the MAC processing. The individual MAC processing unit 212A executes individual data processing (L-MAC processing) as in the individual MAC processing unit 112A of the AP 100.

[0098] As illustrated in Fig. 5, when the STA 200 is an MLD, that is, when the STA 200 is connected to a plurality of links, the common MAC processing unit 211 and the individual MAC processing unit 212A can be configured as separate processing units.

[0099] On the other hand, when the STAs 200 are connected to one link, the wireless communication unit 210 may include one processing unit (for example, a MAC processing unit) obtained by collecting the common MAC processing unit 211 and the individual MAC processing unit 212A.

[0100] (Signal processing unit 213A) The signal processing unit 213A executes a process in a physical layer (PHY). The signal processing unit 213A executes encoding, interleaving, modulation, and the like at the time of transmission, and adds a physical header to generate a symbol stream.

[0101] At the time of reception, the signal processing unit 213A analyzes the physical header and executes demodulation, deinterleaving, decoding, and the like on the symbol stream to generate a MAC frame. The signal processing unit 213A executes complex channel characteristic estimation and spatial separation processing as necessary.

[0102] (RF unit 214A) Although not illustrated, the RF unit 214A includes a transmission RF unit (Tx RF) and a reception RF unit (Rx RF). The transmission RF unit executes digital-to-analog signal conversion, filtering, up-conversion using a local oscillator (not illustrated), and phase control on the symbol stream to generate a transmission signal.

[0103] The reception RF unit executes down-conversion, filtering, and analog-digital signal conversion on the reception signal using a local oscillator (not illustrated) to generate a symbol stream.

[0104] (RF switch 215A) The RF switch 215A switches between transmission and reception. For example, the RF switch 215A switches the RF unit connected to the antennas 218 A_1 and 218 A_2 among the transmission RF unit and the reception RF unit.

[0105] In Fig. 5, the number of antennas 218A_1 and 218A_2 connected to the RF switch 215A is 2, but the number of antennas is not limited to 2. The number of antennas connected to the RF switch 215A may be 1 or 3 or more.

[0106] (Communication control unit 216) The communication control unit 216 controls an operation of each unit of the wireless communication unit 210 and information transmission between the units. The communication control unit 216 executes control to pass control information and management information of which the AP 100 is notified to the common MAC processing unit 211.

[0107] In Fig. 5, the wireless communication unit 210 is mounted on the STA 200 as one integrated circuit (IC), but the configuration of the wireless communication unit 210 is not limited thereto. For example, the wireless communication unit 210 may include a plurality of ICs or individual components. For example, the RF unit 214A, the RF switch 215A, and the antennas 218A_1 and 218A_2 may be mounted on the STA 200 as an IC or an individual component different from other constituents of the wireless communication unit 210.

[0108] (Storage unit 220) The storage unit 220 is a storage device capable of reading and writing data, such as a DRAM, an SRAM, a flash memory, or a hard disk. The storage unit 220 holds information used by the control unit 230 and the wireless communication unit 210.

[0109] (Control unit 230) The control unit 230 is a controller that controls each unit of the STA 200. Instead, the control unit 230 may execute some operations of the communication control unit 216. The communication control unit 216 and the control unit 230 may be configured as one block. The control unit 230 may have any configuration included in the STA 200.

[0110] The control unit 230 may be implemented by, for example, a processor such as a CPU or an MPU. Specifically, the control unit 230 may be implemented by a processor executing various programs stored in a storage device inside the STA 200 using a RAM or the like as a work area.

[0111] The control unit 230 may be implemented by an integrated circuit such as an ASIC or an FPGA. Furthermore, the control unit 230 may be implemented by a GPU.

[0112] Any of the CPU, the MPU, the ASIC, the FPGA, and the GPU can be regarded as a controller. The control unit 230 may include a plurality of physically separated objects. For example, the control unit 230 may include a plurality of semiconductor chips.

[0113] (3. Processing example of communication system) Next, an example of a process executed in the communication system according to the present embodiment will be described. Hereinafter, in the present embodiment, several embodiments in which the traffic buffered in the STA 200 that requires low-delay transmission for UL traffic is transmitted with low delay after the UL communication is resumed by the end of the AP switching will be described.

[0114] (3-1. First embodiment) (3-1-1. Process according to first embodiment) First, as a first embodiment, an example in which a trigger signal for transmitting data is transmitted to a roaming STA having UL traffic for which low-delay transmission is required together with a switching response signal will be described.

[0115] Fig. 6 is a diagram illustrating an example of an AP switching process using a trigger signal according to the first embodiment. In the example of Fig. 6, it is assumed that the target AP transmits a switching response signal to the roaming STA.

[0116] In the example of Fig. 6, the roaming STA determines execution of the AP switching at time t21. For example, in the case of STA initiated roaming, the roaming STA transmits a switch request signal for requesting the source AP to switch the AP. In the example of Fig. 6, the roaming STA transmits the switching request signal to the source AP at time t22. Then, when the source AP correctly receives the switching request signal from the roaming STA, the AP switching is started. In the example of Fig. 6, the source AP receives the switching request signal from the roaming STA. Subsequently, in a case where it is determined that the source AP correctly receives the switching request signal, AP switching is started.

[0117] Then, in the roaming STA, UL traffic is generated at time t23. Subsequently, the roaming STA transmits notification information to the target AP at time t24. The notification information will be described in detail in the following 3-1-3. Information exchange.

[0118] Then, at time t25, the target AP transmits the trigger signal to the roaming STA together with the switching response signal. In this way, the target AP triggers UL communication with the STA 200 having low-delay UL traffic at the same time as the transmission of a switching response signal.

[0119] Accordingly, the roaming STA can transmit the UL communication after time t26. In the example of Fig. 6, the roaming STA transmits UL traffic at time t27. In this way, the roaming STA can transmit the UL traffic for which low delay is required without the target AP ending the transmission opportunity (TXOP) immediately after transmitting the switching response signal. Since the UL traffic is transmitted from the roaming STA as a response to the switching response signal, the target AP can ascertain whether the switching response signal has been correctly transmitted.

[0120] In the example of Fig. 6, an example in which the roaming STA transmits the switching request signal to the source AP has been described, but the present disclosure is not limited thereto. For example, the roaming STA may transmit a switch request signal to the target AP.

[0121] In the first embodiment, a capability check indicating that the function described in the present disclosure is supported may be executed. The capability information may be notified of with, for example, a beacon frame including a capability element used for each version of each standard, a probe request frame, a probe response frame, or the like.

[0122] In the first embodiment, an example in which the target AP transmits the trigger signal to the roaming STA together with the switching response signal has been described, but the present disclosure is not limited thereto. For example, the target AP may transmit a switching response signal including a trigger signal to the roaming STA. The target AP may transmit the switching response signal and the trigger signal separately in the same TXOP using the TXOP.

[0123] Here, in execution of the operation according to the first embodiment, the following preliminary negotiation, notification operation, or the like is required. (1) A transmittable frame except for a QoS data frame is limited during a UL communication interruption period to enable the UL communication. (2) Information exchange is executed among the target AP, the source AP, and the roaming STA. (3) An operation after the end of AP switching is determined and notified of.

[0124] (3-1-2. Limitation of Transmissible Frame) (Method of limiting transmissible frame during UL communication interruption period to enable UL communication) In execution of an operation according to the first embodiment, it is necessary to notify the target AP of information regarding the operation when UL traffic for which low-delay transmission is required is generated in the roaming STA during the UL communication interruption period. With this notification, it is possible to execute an operation of executing the UL low-delay transmission after the end of the AP switching.

[0125] Thus, a transmittable frame and a notifiable information are negotiated in advance with the target AP during the UL communication interruption period to enable the UL communication. For example, NPL 2 describes that multi-link setup is executed before transmission of a switching request signal, and a newly added link is disabled. In IEEE 802.11be, a signal for an individual address in the disabled link including a control frame and a management frame cannot be transmitted. Therefore, it is preferable to transmit a minimum frame during the UL communication interruption period.

[0126] For example, a method using a multi-link setup frame or a method using a roaming request frame is considered as a method of limiting a frame that can be transmitted during the UL communication interruption period and setting a link state of the roaming STA during the UL communication interruption period.

[0127] Hereinafter, an example of a method of enabling UL communication by limiting a transmittable frame during the UL communication interruption period will be described. Fig. 7 is a diagram illustrating an example of an AP switching process when a transmittable frame according to the first embodiment is used. In the example of Fig. 7, it is assumed that the target AP transmits a switching response signal to the roaming STA.

[0128] In the example of Fig. 7, a link state in which a desired frame can be transmitted is defined in a region RC31. Multi-link setup is executed in a region RC32. In the example of Fig. 7, the roaming STA transmits a frame of the multi-link setup at time t31. In the target AP, a link is added at time t31, but the link state is disabled until time t36.

[0129] The roaming STA transmits a switching request signal to the source AP. In the example of Fig. 7, in the case of STA initiated roaming, the roaming STA transmits a switching request signal to the source AP at time t32.

[0130] Subsequently, when the source AP correctly receives the switching request signal from the roaming STA, the AP switching starts. In the example of Fig. 7, the source AP receives the switching request signal from the roaming STA. Then, when it is determined that the source AP correctly receives the switching request signal, the AP switching starts.

[0131] Subsequently, it is assumed that UL traffic is generated at time t33 in the roaming STA. Then, the roaming STA transmits the notification information to the target AP at time t34. Subsequently, the source AP transmits the switching response signal at time t35. The notification information will be described in detail in the following 3-1-3. Information exchange.

[0132] In addition to the negotiation of the frame that can be transmitted during the UL communication interruption period, the target AP may transmit a request signal for transmitting the switching response signal. A frame used to limit the transmittable frame during the UL communication interruption period to enable the UL communication may be another frame related to the AP switching transmitted before the switching request signal. For example, the other frames mentioned here are an FT request, an FT probe request, and the like. Although not illustrated in Fig. 7, a response signal may be transmitted to each signal such as the switching request signal.

[0133] (Encryption key) What needs to be considered when the UL traffic is transmitted during the UL communication interruption period is whether an encryption key is held between the roaming STA and the target AP. For example, the transmittable frame changes depending on whether there is the encryption key. The notifiable information may be changed depending on whether there is the encryption key.

[0134] Although there are some proposals made to apply Protection by encryption to a control frame and a MAC Header, communication that can be executed without encryption other than the control frame and the MAC Header will also be examined.

[0135] For example, in IEEE 802.11be, an example of a frame that can be transmitted during the UL communication interruption period according to a holding state of the encryption key will be described below. When the roaming STA does not hold an encryption key with the target AP, examples of the frame that can be transmitted include a control frame, a public action frame, and a QoS null frame. When the roaming STA holds an encryption key with the target AP, an encrypted (management) frame or the like can be given as an example of a transmittable frame.

[0136] As the encryption key, there is a PTK for transmitting a signal for an individual address between the target AP and the roaming STA, a roaming signal key dedicated for AP switching as described in NPL 3, or the like. NPL 3 proposes that a PTK is newly generated without being shared between the target AP and the source AP. NPL 4 proposes that PTK is shared between a target AP and a source AP.

[0137] (Frame format) Next, a format of a transmittable frame will be described with reference to Fig. 8. Fig. 8 is a diagram illustrating an example of a frame configuration of a switching request signal according to the first embodiment. The example of Fig. 8 is an example of a format in which a frame that can be transmitted with the switching request signal during the UL communication interruption period is set. Transmission of the switching request signal by the target AP is requested using Roaming Response From Target AP Request Flag.

[0138] The upper diagram of Fig. 8 is a diagram illustrating an example of a MAC frame format in IEEE 802.11. The lower diagram of Fig. 8 is a diagram illustrating a frame body of a MAC frame. In the example of Fig. 8, the frame body of the MAC frame includes Roaming Response From Target AP Request, PTK Request, Permitted Frame Type during UL Suspension Request, and Reserved. Roaming Response From Target AP Request has one bit. PTK Request has one bit. Permitted Frame type during UL Suspension Request has 3-bit. Reserved has four bits.

[0139] A request for a frame that can be transmitted during the UL communication interruption period is requested in a Permitted Frame Type during UL Suspension Request. Here, the type of frame is designated with information included in Permitted Frame type during UL Suspension Request. Table 1 below shows a correspondence relationship between information included in a Permitted Frame type during UL Suspension Request and a frame type.

[0140]

[0141] In Table 1, when Permitted Frame type during UL Suspension Request is "00", Subsequence Content is "Public Action". When Permitted Frame type during UL Suspension Request is "01", Subsequence Content is "QoS Null".

[0142] When Permitted Frame type during UL Suspension Request is "10", the Subsequence Content is "Protected Individually Addressed Management Frame". When Permitted Frame type during UL Suspension Request is "11", Subsequence Content is "Protected Signal by Roaming Signal Key". In this way, an appropriate type of frame can be designated according to information included in Permitted Frame type during UL Suspension Request.

[0143] When a PTK is newly generated during the UL communication interruption period or when the PTK is shared between the source AP and the target AP, a request for immediately notifying the roaming STA can also be requested using Flag.

[0144] In the example of Fig. 8, the transmittable frame has been described as a type of frame, but the present disclosure is not limited thereto. For example, any number of types of transmittable frames may be set. The frame requested in the holding state of the encryption key at the time of the switching request signal may change. Information that can be notified of during the UL communication interruption period may be limited according to the holding state of the encryption key.

[0145] By using the response signal to the switching response signal, the source AP or the target AP may transmit a response signal with reference to the request signal transmitted by the roaming STA illustrated in Fig. 8. A rule for a frame or information that can be transmitted between the source AP and the target AP may be determined in advance according to the holding state of the encryption key during the UL communication interruption period.

[0146] (3-1-3. Information exchange) (Information exchange among target AP, source AP, and roaming STA) In execution of an operation according to the first embodiment, it is necessary to notify the target AP of a state of the roaming STA during the UL communication interruption period. Here, as the notification information regarding the traffic to be notified of, the following information is conceivable. 1. Traffic amount 2. Notification in which low-delay traffic is buffered (buffer status) 3. TID / AC 4. Request for trigger signal to be transmitted with switching response signal 5. Priority transmission period setting request 6. Delay budget 7. DL suspension 8. Request for target AP to transmit switching response signal

[0147] Accordingly, in addition to the information of the traffic held by the roaming STA, a request for a low-delay transmission method for low-delay traffic after the UL communication interruption period, and other request information such as a request for the target AP to transmit a switching response signal can be notified of. Only the switching request signal, a frame permitted in advance by multi-link setup or the like, and the transmittable information can be transmitted during the UL communication interruption period. The number of bits that can be transmitted with a transmittable frame may change. Of the notification information, detailed information may be encrypted and transmitted.

[0148] Hereinafter, an example of a process executed by the communication system in information exchange among the target AP, the source AP, and the roaming STA will be described. Fig. 9 is a diagram illustrating an example of an AP switching process using notification information according to the first embodiment. In the example of Fig. 9, it is assumed that the source AP transmits a switching response signal to the roaming STA.

[0149] In the example of Fig. 9, information exchange during the UL communication interruption period is executed in a region RC41. For example, in the case of STA initiated roaming, the roaming STA transmits the switching request signal to the source AP. In the example of Fig. 9, the roaming STA transmits the switching request signal to the source AP at time t41.

[0150] Subsequently, when the source AP correctly receives the switching request signal from the roaming STA, the AP switching starts. In the example of Fig. 9, the source AP receives the switching request signal from the roaming STA. Then, when it is determined that the source AP correctly receives the switching request signal, the AP switching starts.

[0151] Subsequently, it is assumed that UL traffic is generated in the roaming STA at time t42. Then, the roaming STA transmits the notification information to the target AP at time t43. Subsequently, the target AP transmits the response signal indicating that the notification information has been received to the roaming STA at time t44. Then, the source AP transmits the switching response signal at time t45. In the example of Fig. 9, the UL communication interruption period is a period from time t41 to time t46.

[0152] (Format of frame in case of no encryption) Next, a frame format in the case of no encryption will be described with reference to Fig. 10. Fig. 10 is a diagram illustrating an example of an A-Control field format according to the first embodiment. The upper diagram of Fig. 10 is a diagram illustrating an example of a MAC frame format in IEEE 802.11. The middle diagram of Fig. 10 is a diagram illustrating the HT control field of the MAC frame. The HT Control field includes Control ID and Control Information. The lower diagram of Fig. 10 is a diagram illustrating Control Information.

[0153] In the example of Fig. 10, Control Information includes AC, Queue Size, Roaming Response from Target AP Request, Trigger Request When Roaming Response, Source AP Address, and Reserved. AC has two bits. Queue Size has eight bits. Roaming Response from Target AP Request has one bit. Trigger Request When Roaming Response has one bit. Source AP Address has twelve bits. Reserved has two bits.

[0154] The A-Control field is available when the first bit and the second bit of HT Control field of the MAC frame are both 1. The number of bits of Control Information in the A-Control field is twenty six bits. Control ID10-14 is reserved. Therefore, a new format can be defined in Control ID10-14. For example, in addition to traffic information such as AC and Queue Size, a transmission request signal of a trigger signal transmitted together with a switching response signal can be included in Control Information.

[0155] When it is desired to share information regarding the frame to be transmitted to the target AP also with the source AP via the Distribution System (DS) (Over-The-DS), the address of the source AP can be included in Control Information. In this case, it is necessary to shorten the number of bits in the AP address used in the FT request due to limitation on the number of bits.

[0156] When the public action frame is used, the frame body can be used. Therefore, various types of information such as Delay Budget can be utilized. In the example of Fig. 10, buffer information is included in the HT Control field, but the buffer information may be notified of utilizing the QoS Control field.

[0157] Information that can be transmitted when information is transmitted without encryption may be limited from the viewpoint of security. The source AP can transmit information to the target AP through the DS. In this case, not an address of the source AP but an address of the target AP is stored.

[0158] (Regarding frame format in case of encryption) Next, the format of the frame in the case of encryption will be described with reference to Fig. 11. Fig. 11 is a diagram illustrating an example of a format when an element according to the first embodiment is used.

[0159] The upper diagram of Fig. 11 is a diagram illustrating an example of an element format in IEEE 802.11. As illustrated in the upper diagram of Fig. 11, Information of Element is identified by a combination of Element ID and Element ID Extension. In the lower diagram of Fig. 11, Information of Element is illustrated.

[0160] In the example of Fig. 11, the information includes AC, Queue Size, Delay Bound, Source AP Address, Roaming Response From Target AP Request, Trigger Request When Roaming Response, and PTK Request. AC has two bits. Queue Size has eight bits. Delay Bound has twenty four bits. Source AP Address has forty eight bits. Roaming Response from Target AP Request has one bit. Trigger Request When Roaming Response has one bit. PTK Request has one bit.

[0161] For example, new Element ID can be assigned as information for identifying Information. In this way, a new format can be defined by defining the new Element ID. In the format when the element is used, for example, an encrypted Management frame is used, and security is higher than unencrypted communication. In the format in the case of using Element, for example, a frame body can be utilized, and thus the amount of information that can be transmitted is large.

[0162] In the example of Fig. 11, in the format when an element is used, in addition to the AC and size information of traffic in which the AC is buffered, the target AP is also notified of information regarding Delay Bound. Information is shared with the source AP through the DS. Therefore, the address of the source AP can be stored in the format when the element is used.

[0163] In the format when the element is used, the operation requests information after the UL communication interruption period and other information can also be notified of. In addition to a method of adding new Element ID used for (FT) Action Frame or the like, a dedicated Management frame to be transmitted during an operation within the UL communication interruption period may be defined. The number of bits may be reduced by compressing an amount of information regarding Delay Bound or Target AP as necessary. The source AP may transmit information to the target AP through the DS. In this case, not an address of the source AP but an address of the target AP is stored.

[0164] The format of the frame in the case of encryption or non-encryption is summarized in Table 2. Table 2 shows a correspondence relationship between a holding state of an encryption key and a frame example used during the UL communication interruption period.

[0165]

[0166] In Table 2, when the holding state of the encryption key is "No encryption key is held", a frame example is "Header (Control frame / QoS Null frame) / Public Action frame". When the holding state of the encryption key is "Encryption key is held", the frame example is "Management (Element / FT Action frame / Roaming frame)".

[0167] (3-1-4. Operation after end of AP switching) (Determination and notification of operation after end of AP switching) In execution of the operation according to the first embodiment, notification of the operation after the UL communication interruption period is executed together with the switching response signal based on the information transmitted by the roaming STA during the UL communication interruption period, the Context information, and the like.

[0168] Hereinafter, an example of a method of notifying of the operation after the end of AP switching will be described. Fig. 12 is a diagram illustrating an example of an AP switching process when an operation after AP switching according to the first embodiment is notified of. In the example of Fig. 12, an example in which a trigger signal is transmitted together with the switching response signal will be described. The notification of the operation after the end of AP switching includes information indicating transmission of the trigger signal.

[0169] In the example of Fig. 12, in the case of STA initiated roaming, the roaming STA transmits the switching request signal to the source AP. In the example of Fig. 12, the roaming STA transmits the switching request signal to the source AP at time t51. Subsequently, when the source AP correctly receives the switching request signal from the roaming STA, the AP switching starts. In the example of Fig. 12, the source AP receives the switching request signal from the roaming STA. Then, when it is determined that the source AP correctly receives the switching request signal, the AP switching starts. Subsequently, the target AP transmits the trigger signal to the roaming STA together with the switching response signal at time t52. In this case, the target AP also transmits a notification of the operation after the end of AP switching to the roaming STA.

[0170] When the trigger signal cannot be transmitted together with the switching response signal for some reason, the target AP transmits a notification indicating that the trigger signal cannot be transmitted to the roaming STA having the low-delay traffic. In this case, for example, the target AP transmits a notification of the operation according to the second embodiment to the roaming STA. For example, the notification of the operation after the end of the AP switching includes a notification of the operation according to the second embodiment. The second embodiment will be described in detail in 3-2. Second embodiment.

[0171] When the plurality of STAs 200 including a roaming STA having low-delay traffic are simultaneously executing AP switching, a notification of an operation according to the third embodiment described in detail in 3-3. Third embodiment below is transmitted to the roaming STA. For example, a notification of the operation after the end of the AP switching includes the notification of the operation according to the third embodiment.

[0172] As described above, the notification of the operation after the end of the AP switching is transmitted together with the switching response signal to the STA 200 that has a sufficient lifetime based on information from the roaming STA during the UL communication interruption period or the STA 200 that does not require low-delay transmission. Accordingly, operations of the plurality of STAs 200 other than the roaming STA having the low-delay traffic can be controlled. Therefore, it is possible to increase a possibility of a roaming STA having low-delay traffic being able to execute low-delay transmission.

[0173] (Frame format) Next, a format of a transmittable frame will be described with reference to Fig. 13. Fig. 13 is a diagram illustrating an example of a frame configuration of a switching response signal according to the first embodiment. In the example of Fig. 13, Action After Roaming Response indicates that a process (corresponding to Trigger in Table 3 described below) according to the first embodiment, a process (corresponding to Temporal SP in Table 3) according to the second embodiment, a process (corresponding to Channel Access Restriction in Table 3) according to the third embodiment, or a special operation is not executed. The second or third embodiment will be described in detail in 3-2. Second embodiment and 3-3. Third embodiment.

[0174] The upper diagram of Fig. 13 is a diagram illustrating an example of a MAC frame format in IEEE 802.11. The lower diagram of Fig. 13 is a diagram illustrating a frame body of a MAC frame. In the example of Fig. 13, a frame body of a MAC frame includes Action After Roaming Response and Subsequent Content (SP Information / Trigger Information...). Action After Roaming Response has two bits. Subsequent Content has any number of bits (corresponding to the X bits in Fig. 13).

[0175] Here, a type of operation is designated with information included in Action After Roaming Response. Table 3 below shows a correspondence relationship between information included in Action After Roaming Response and a type of operation.

[0176]

[0177] In Table 3, when Action After Roaming Response is "00", the Subsequence Content is "Trigger". When Action After Roaming Response is "01", Subsequence Content is "Temporal SP".

[0178] When Action After Roaming Response is "10", Subsequence Content is "Channel Access Restriction". When Action After Roaming Response is "11", Subsequent Content is "No Action". In this way, it is possible to designate an appropriate type of operation in accordance with the information included in the Action After Roaming Response.

[0179] Information necessary for each operation is included subsequently. For example, when Action After Roaming Response is "00", information necessary for an operation of "Trigger" is included subsequently. In the example of Fig. 13, a management frame including Frame Body has been assumed and described, but the present disclosure is not limited thereto. For example, Control Frame may be assumed.

[0180] (3-1-5. Flowchart illustrating procedure of STA-side switching process according to first embodiment) Next, a procedure of the switching process executed by the STA 200 according to the first embodiment will be described with reference to Fig. 14. Fig. 14 is a flowchart illustrating an example of a flow of a switching process on the STA 200 side according to the first embodiment.

[0181] First, the premise will be described. In the example of Fig. 14, a case where a roaming STA having low-delay traffic transmits a switching response signal from a target AP during execution of AP switching is assumed. In the example of Fig. 14, Dual Link is assumed.

[0182] A request for the target AP transmitting the switching response signal is made when the switching request signal is transmitted. It is assumed that negotiation based on the holding condition of the encryption key between the target AP and the source AP, and negotiation regarding a frame and information that may be transmitted is executed in advance. It is assumed that information is shared between the target AP and the source AP via the DS or wirelessly between the target AP and the source AP.

[0183] The switching process on the STA 200 side illustrated in Fig. 14 is repeatedly executed by the roaming STA at predetermined intervals, for example, while the roaming STA is connected to the source AP. The example of Fig. 14 will be described assuming that the STA 200 is a roaming STA.

[0184] As illustrated in Fig. 14, the STA 200 determines whether low-delay transmission of the UL traffic is necessary (step S101). For example, when the STA 200 determines that the low-delay transmission of the UL traffic is necessary (step S101; Yes), a switching request signal is transmitted (step S102).

[0185] Subsequently, the STA 200 receives a response signal to the switching request signal (step S103). Then, the STA 200 determines whether the low-delay traffic is held during the UL communication interruption period (step S104).

[0186] For example, when the STA 200 determines that the low-delay traffic is held during the UL communication interruption period (step S104; Yes), the notification information is transmitted (step S105). Subsequently, the STA 200 receives the trigger signal together with the switching response signal from the target AP (step S106).

[0187] Conversely, when the STA 200 determines that the low-delay traffic is not held during the UL communication interruption period (step S104; No), the switching response signal is received (step S108).

[0188] Conversely, when the STA 200 determines that the low-delay transmission of the UL traffic is not necessary (step S101; No), the switching request signal is transmitted (step S109). Subsequently, the STA 200 receives the response signal to the switching request signal (step S110).

[0189] Then, the STA 200 receives the switching response signal (step S111). Subsequently, the STA 200 starts UL communication with the target AP (step S107). Then, the STA 200 ends the process. The STA 200 may transmit the switching request signal to the target AP or the source AP.

[0190] As described above, when the low-delay traffic is generated, it is necessary to limit a transmittable frames except for a QoS Data frame during the UL communication interruption period and to enable the UL communication. Therefore, the STA 200 transmits the request signal for transmitting the switching response signal from the target AP, the information regarding the frame type that can be transmitted during the UL communication interruption period, and the request signal regarding the transmittable information together with the switching request signal. When the response signal to the switching request signal is returned, the transmittable frame except for the QoS data frame is limited during the UL communication interruption period, so that the UL communication can be executed. When traffic is generated during the UL communication interruption period, the STA 200 transmits the traffic information and the like to the target AP together with a negotiation request for an operation related to low-delay transmission after the UL communication interruption period. Conversely, when the low-delay traffic is not generated during the UL communication interruption period, the STA 200 is not required to transmit the notification information including the operation related to the low-delay transmission after the UL communication interruption period and a buffer state of the STA 200.

[0191] When low-delay transmission of the UL traffic is not necessary, the STA 200 transmits the switching request signal as usual. Then, a response signal to the switching request signal is received, and AP switching starts.

[0192] (3-1-6. Flowchart illustrating procedure of AP-side switching process according to first embodiment) Next, a procedure of a switching process executed by the AP 100 according to the first embodiment will be described with reference to Fig. 15. Fig. 15 is a flowchart illustrating an example of a flow of a switching process on the AP 100 side according to the first embodiment. The example of Fig. 15 will be described assuming that the AP 100 is a target AP.

[0193] As illustrated in Fig. 15, the AP 100 receives a transmission request signal for requesting transmission of a switching response signal from the STA 200 (step S201). For example, when the AP 100 has received the transmission request signal from the STA 200 (step S201; Yes), the switching request signal is received (step S202).

[0194] Subsequently, the AP 100 transmits the response signal to the switching request signal (step S203). Then, the AP 100 determines whether notification information has been received from the roaming STA during the UL communication interruption period (step S204). For example, when the AP 100 has received the notification information from the roaming STA during the UL communication interruption period (step S204; Yes), the trigger signal is transmitted together with the switching response signal (step S205). Subsequently, the AP 100 ends the process.

[0195] Conversely, when the AP 100 has not received the notification information from the roaming STA during the UL communication interruption period (step S204; No), the switching response signal is transmitted (step S208). Subsequently, the AP 100 ends the process.

[0196] Conversely, in a case where the AP 100 has not received the transmission request signal from the STA 200 (step S201; No), the switching request signal is received (step S206). Subsequently, the AP 100 transmits the response signal to the switching request signal (step S207). Then, the AP 100 transmits the switching response signal (step S208). Subsequently, the AP 100 ends the process.

[0197] As described above, in the flowchart illustrated in Fig. 15, classification occurs depending on whether there is the transmission request signal of the frame to the AP 100 in advance during the UL communication interruption period. When the request signal has not been received from the STA 200, the AP 100 receives the switching request signal. Then, the AP 100 returns the response signal to the switching request signal, and transmits the switching response signal for notifying that AP switching ends after end of the AP switching.

[0198] When there is a request to limit the transmittable frames except the QoS data frame during the UL communication interruption period to enable the UL communication, the AP 100 transmits a response to the request. Then, the AP 100 determines the operation during the UL communication interruption period. When notification information has not been received from the STA 200 during the UL communication interruption period, the AP 100 transmits the switching response signal as a signal indicating that there is no request from the STA 200. When the low-delay transmission request and the notification information including the traffic information are received from the STA 200 during the UL communication interruption period, the AP 100 determines the operation after the UL communication interruption period based on the notification information.

[0199] (3-2. Second embodiment) (3-2-1. Processing according to second embodiment) Next, in a second embodiment, an example in which a priority period is set for a roaming STA having UL traffic for which low-delay transmission is required will be described. In the first embodiment, the example in which a target AP transmits a trigger signal together with a switching response signal to the roaming STA when the low-delay traffic is generated in the roaming STA during the UL communication interruption period has been described, but there may be a case where a trigger signal cannot be transmitted.

[0200] For example, the above case includes a case where the source AP transmits a switching response signal, a case where allocation of resources is late, and a case where the number of STAs 200 making a request for AP switching is large. There is another roaming STA having low-delay traffic, and an amount of data varies for each STA 200, such that UL OFDMA cannot be used.

[0201] In this case, the target AP (or the source AP) sets a priority transmission period so that the roaming STA can have a low delay. Then, the target AP (or the source AP) transmits a notification of the priority transmission period to the roaming STA together with the switching response signal.

[0202] For example, as an operation example of the priority transmission period, when the target AP, the source AP, or the other AP acquires the TXOP within the priority transmission period, TXOP Sharing or a trigger signal is transmitted so that the roaming STA having low-delay traffic can transmit the TXOP.

[0203] Hereinafter, an example of a process executed by the communication system in information exchange among the target AP, the source AP, and the roaming STA will be described. Fig. 16 is a diagram illustrating an example of an AP switching process according to the second embodiment. In the example of Fig. 16, it is assumed that the target AP transmits a switching response signal to the roaming STA.

[0204] In the example of Fig. 16, the roaming STA determines execution of AP switching at time t61. For example, in the case of STA initiated roaming, the roaming STA transmits a switch request signal for requesting the source AP to switch the AP. In the example of Fig. 16, the roaming STA transmits the switching request signal to the source AP at time t62.

[0205] Subsequently, when the source AP correctly receives the switching request signal from the roaming STA, the AP switching starts. In the example of Fig. 16, the source AP receives the switching request signal from the roaming STA. Then, when it is determined that the source AP correctly receives the switching request signal, the AP switching starts. In the example of Fig. 16, the UL communication interruption period is a period from time t62 to time t66.

[0206] Then, in the roaming STA, UL traffic is generated at time t63. Subsequently, the roaming STA transmits the notification information to the target AP at time t64. Then, at time t65, the target AP transmits a notification of the priority transmission period to the roaming STA together with the switching response signal.

[0207] Here, it is assumed that information regarding the UL traffic is shared in advance between the source AP and the target AP. In this case, the source AP executes TXOP sharing at time t67 and transfers the TXOP to the target AP. Subsequently, the target AP transmits the trigger signal to the roaming STA together with the switching response signal at time t68. In this way, the target AP triggers the STA having low-delay UL traffic.

[0208] When only the source AP ascertains that the roaming STA holds the low-delay traffic, the present disclosure is not limited to execution of the TXOP sharing at time t67, and the source AP may transmit an indication to the target AP so that the roaming STA can execute the low-delay transmission. Accordingly, when the target AP acquires a channel right without TXOP sharing from the source AP, the target AP can trigger.

[0209] Accordingly, the roaming STA can transmit the UL communication after time t68. In the example of Fig. 16, the roaming STA transmits UL traffic at time t69. As described above, in addition to the low-delay transmission of the UL traffic, a trigger signal is transmitted simultaneously with other STAs 200 by shifting a timing at which the trigger signal is transmitted. Accordingly, the communication system can improve transmission efficiency.

[0210] For example, as an operation example of the priority transmission period, the transmission of another STA 200 ends at the SP start time as in the R-TWT SP, and channel access is not made with Quiet Element. In this case, it is necessary to notify the other STA 200 of the SP information in order to execute an operation such as R-TWT.

[0211] For example, as an operation example of the priority transmission period, the number of STAs 200 contending for the roaming STA having low-delay traffic is reduced by a combination with an operation according to a third embodiment described in detail in 3-3. Third embodiment below.

[0212] The priority transmission period is calculated utilizing a value of Delay Budget during the UL communication interruption period and information (service capability server (SCS) information or the like) obtained in Context information. The priority transmission period is calculated at each time.

[0213] In the second embodiment, a capability check indicating correspondence to a function described in the present disclosure may be executed. The capability information may be notified of with, for example, a beacon frame including an ultra high reliability (UHR) capability element, a probe request frame, a probe request response, or the like. In the second embodiment, as in the first embodiment, preliminary negotiation, a notification operation, or the like of (1) to (3) above are executed.

[0214] (3-2-2. Flowchart illustrating procedure of STA-side switching process according to second embodiment) Next, a procedure of a switching process executed by the STA 200 according to the second embodiment will be described with reference to Fig. 17. Fig. 17 is a flowchart illustrating an example of a flow of a switching process on the STA 200 side according to the second embodiment.

[0215] Since the premise in Fig. 17 according to the second embodiment is the same as the premise described in Fig. 14 according to the first embodiment, description thereof will be omitted. The switching process on the STA 200 side illustrated in Fig. 17 is repeatedly executed by the roaming STA at predetermined intervals, for example, while the roaming STA is connected to the source AP. The example of Fig. 17 will be described assuming that the STA 200 is a roaming STA.

[0216] As illustrated in Fig. 17, the STA 200 determines whether low-delay transmission of UL traffic is necessary (step S301). For example, when the STA 200 determines that the low-delay transmission of the UL traffic is necessary (step S301; Yes), a switching request signal is transmitted (step S302).

[0217] Subsequently, the STA 200 receives a response signal to the switching request signal (step S303). Then, the STA 200 determines whether traffic has been generated during the UL communication interruption period (step S304).

[0218] For example, when the STA 200 determines that traffic has been generated during the UL communication interruption period (step S304; Yes), the notification information is transmitted (step S305). Subsequently, the STA 200 receives the switching response signal from the target AP (step S306).

[0219] For example, the STA 200 receives the switching response signal and receives information regarding the priority transmission period included in the switching response signal. Then, the STA 200 receives a notification indicating that the trigger cannot be applied from the target AP (step S307).

[0220] Conversely, when the STA 200 determines that the traffic has not been generated during the UL communication interruption period (step S304; No), the switching response signal is received from the target AP (step S309).

[0221] Conversely, when the STA 200 determines that the low-delay transmission of the UL traffic is not necessary (step S301; No), the switching request signal is transmitted (step S310). Subsequently, the STA 200 receives the response signal to the switching request signal (step S311).

[0222] Then, the STA 200 receives the switching response signal (step S312). Subsequently, the STA 200 starts UL communication with the target AP (step S308). Then, the STA 200 ends the process. The STA 200 may transmit the switching request signal to the target AP or the source AP.

[0223] (3-2-3. Flowchart illustrating procedure of AP-side switching process according to second embodiment) Next, the procedure of the switching process executed by the AP 100 according to the second embodiment will be described with reference to Fig. 18. Fig. 18 is a flowchart illustrating an example of a flow of a switching process on the AP 100 side according to the second embodiment. The example of Fig. 18 will be described assuming that the AP 100 is a target AP.

[0224] As illustrated in Fig. 18, the AP 100 receives a transmission request signal from the STA 200 (step S401). For example, when the AP 100 has received the transmission request signal from the STA 200 (step S401; Yes), the switching request signal is received (step S402).

[0225] Subsequently, the AP 100 transmits the response signal to the switching request signal (step S403). Then, the AP 100 determines whether notification information has been received from the roaming STA during the UL communication interruption period (step S404).

[0226] For example, when the AP 100 has received the notification information from the roaming STA during the UL communication interruption period (step S404; Yes), the switching response signal is transmitted (step S405). Subsequently, the AP 100 transmits information regarding the priority transmission period (step S406). Then, the AP 100 preferentially executes UL communication with the roaming STA (step S407). Subsequently, the AP 100 ends the process.

[0227] Conversely, when the AP 100 has not received data from the roaming STA during the UL communication interruption period (step S404; No), the switching response signal is transmitted (step S410). Subsequently, the AP 100 ends the process.

[0228] Conversely, when the AP 100 has not received the transmission request signal from the STA 200 (step S401; No), the switching request signal is received (step S408). Subsequently, the AP 100 transmits the response signal to the switching request signal (step S409). Then, the AP 100 transmits the switching response signal (step S410). Subsequently, the AP 100 ends the process.

[0229] (3-3. Third embodiment) (3-3-1. Processing according to third embodiment) Next, as a third embodiment, an example in which channel access is not executed for a certain period on the STA 200 for which low-delay traffic is not required will be described. When the plurality of STAs 200 executes AP switching and the plurality of STAs 200 holds traffic, channel contention occurs between the STAs 200 of which the AP switching has ended.

[0230] In this case, an interruption of the UL communication occurs by the STA 200 that has a sufficient lifetime, the STA 200 that has the traffic not requiring the low-delay transmission, or the like. Accordingly, for example, of the STAs 200, there is a possibility of a roaming STA having low-delay traffic not being able to execute UL communication.

[0231] Accordingly, the UL channel access other than the STA 200 that requires the low-delay transmission is temporarily stopped. For example, it is assumed that the roaming STA having low-delay traffic cannot be triggered together with transmission of the switching response signal. In this case, when the switching response signal is transmitted utilizing the traffic information of the roaming STA notified of during the UL communication interruption period, the SCS information notified of by Context Transfer, or the like, the channel access other than the STA 200 immediately requiring the low-delay transmission is not executed for a certain period.

[0232] Fig. 19 is a diagram illustrating an example of an AP switching process according to the third embodiment. In the example of Fig. 19, it is assumed that the target AP transmits a switching response signal to the roaming STA. In the example of Fig. 19, it is assumed that the roaming STA that requires low-delay transmission for UL traffic executes AP switching in an environment where there are a plurality of APs 100 and STAs 200.

[0233] In the example of Fig. 19, the roaming STA is the STA 200 that requires low-delay transmission for UL traffic. The STA 200 different from the roaming STA is another roaming STA. In the example of Fig. 19, it is assumed that the other roaming STAs have already executed the AP switching. In this case, the roaming STA executes the AP switching.

[0234] In the example of Fig. 19, in the case of STA initiated roaming, the roaming STA transmits the switching request signal to the source AP. In the example of Fig. 19, the roaming STA transmits the switching request signal to the source AP at time t71. Then, when the source AP correctly receives the switching request signal from the roaming STA, the AP switching is started. In the example of Fig. 19, the source AP receives the switching request signal from the roaming STA. Subsequently, in a case where it is determined that the source AP correctly receives the switching request signal, AP switching is started.

[0235] Then, in the roaming STA, UL traffic is generated at time t72. Subsequently, in the other roaming STAs, the UL traffic is generated at time t73.

[0236] Subsequently, the target AP transmits the switching response signal to the other Roaming STAs at time t74. In this case, the target AP transmits information regarding an additional UL communication interruption period to the other Roaming STAs. In the example of Fig. 19, the UL communication interruption period is extended by the period of a region RC71. Accordingly, the other roaming STAs do not execute the channel access until the additional UL communication interruption period elapses. Then, the target AP transmits the switching response signal to the roaming STA at time t76.

[0237] In the example of Fig. 19, a status of UL or DL communication of the other roaming STAs is indicated by a bar B71 or B72. As indicated by the bar B71, in the UL communication of the other roaming STAs, a period until time t75 corresponds to the UL communication interruption period. The UL communication is not executed during a period corresponding to the region RC71. Then, after the period corresponding to the region RC71, the other roaming STAs execute UL communication with the target AP.

[0238] Furthermore, as illustrated in the bar B72, the other roaming STAs execute the DL communication with the source AP. After the UL communication interruption period, the other roaming STAs execute the DL communication with the source AP or the target AP. Then, the other roaming STAs execute the DL communication with the target AP from time t77.

[0239] In this way, the number of other STAs 200 contending channel access with the roaming STA having low-delay traffic can be reduced. Accordingly, the roaming STA can execute low-delay transmission. By transmitting the trigger signal to a plurality of STAs 200 including the STA 200 with limited channel access, it is possible to simultaneously transmit the UL traffic. Accordingly, the communication system can improve transmission efficiency.

[0240] In the third embodiment, unlike a case where the transmission of the switching response signal is delayed by simply extending the UL communication interruption period, a link between the roaming STA and the target AP can be validated by transmitting the switching response signal to the roaming STA. Accordingly, even when low-delay transmission is required for the DL, it is possible to take measures similarly.

[0241] In the second embodiment, a capability check indicating correspondence to a function described in the present disclosure may be executed. The capability information may be notified of with, for example, a beacon frame including an ultra high reliability (UHR) capability element, a probe request frame, a probe request response, or the like. In the second embodiment, as in the first embodiment, preliminary negotiation, a notification operation, or the like of (1) to (3) above are executed.

[0242] The AC that executes the channel access restriction may be limited. For example, traffic of a best effort or a background access category may be restricted not to be transmitted.

[0243] (3-3-2. Flowchart illustrating procedure of STA-side switching process according to third embodiment) Next, the procedure of the switching process executed by the STA 200 according to the third embodiment will be described with reference to Fig. 20. Fig. 20 is a flowchart illustrating an example of a flow of a switching process on the STA 200 side according to the third embodiment.

[0244] Since the premise in Fig. 20 according to the third embodiment is the same as the premise described in Fig. 14 according to the first embodiment, the description thereof will be omitted. In the third embodiment, it is assumed that channel contention occurs between a plurality of STAs 200.

[0245] The switching process on the STA 200 side illustrated in Fig. 20 is repeatedly executed by the STA 200 at predetermined intervals, for example, while the STA 200 is connected to the source AP. In the example of Fig. 20, description will be made on the assumption that the STA 200 is an STA 200 different from the roaming STA.

[0246] As illustrated in Fig. 20, the STA 200 determines whether low-delay transmission of the UL traffic is necessary (step S501). For example, when the STA 200 determines that the low-delay transmission of the UL traffic is necessary (step S501; Yes), the switching request signal is transmitted (step S502).

[0247] Subsequently, the STA 200 receives the response signal to the switching request signal (step S503). Then, the STA 200 determines whether traffic has been generated during the UL communication interruption period (step S504).

[0248] For example, when the STA 200 determines that traffic has been generated during the UL communication interruption period (step S504; Yes), the notification information is transmitted (step S505). Subsequently, the STA 200 receives the switching response signal from the target AP (step S506).

[0249] On the other hand, when the STA 200 determines that the traffic is generated during the UL communication interruption period (step S504; No), the switching response signal is received from the target AP (step S506).

[0250] Subsequently, the STA 200 determined that the low-delay transmission is not necessary by the target AP transmitting the switching response signal based on the notification information or the like receives information regarding the additional UL communication interruption period (step S507). Then, the STA 200 determines whether the channel access restriction has ended (step S508).

[0251] For example, when the STA 200 determines that the channel access restriction has not ended (step S508; No), waiting is executed until the channel access restriction ends. Conversely, when the STA 200 determines that the channel access restriction has ended (step S508; Yes), the UL communication with the target AP starts (step S509). Then, the STA 200 ends the process.

[0252] Conversely, when the STA 200 determines that the low-delay transmission of the UL traffic is not necessary (step S501; No), the switching request signal is transmitted (step S510). Subsequently, the STA 200 receives the response signal to the switching request signal (step S511).

[0253] Then, the STA 200 receives the switching response signal (step S512). Subsequently, the STA 200 determines whether information regarding the additional UL communication interruption period has been received (step S513). For example, when it is determined that the STA 200 has not received the information regarding the additional UL communication interruption period (step S513; No), the process ends.

[0254] Conversely, when the STA 200 determines that the information regarding the additional UL communication interruption period has been received (step S513; Yes), the STA 200 determines whether the channel access restriction has ended (step S514).

[0255] For example, when the STA 200 determines that the restriction of the channel access has not ended (step S514; No), waiting is executed until the channel access restriction ends. Conversely, when the STA 200 determines that the channel access restriction has ended (step S514; Yes), the process ends. The STA 200 may transmit the switching request signal to the target AP or the source AP.

[0256] As described above, when the AP switching occurs simultaneously in the plurality of STAs 200 and the trigger signal cannot be immediately transmitted, the channel access is restricted to another STA 200 different from the STA 200 required to execute the low-delay transmission of the UL traffic and other STAs 200 has a sufficient lifetime. In this case, the channel access of the other STAs 200 is restricted until the additional UL communication interruption period ends. The channel access of the other STAs 200 is restricted until a trigger signal can be transmitted.

[0257] (3-3-3. Flowchart illustrating procedure of AP-side switching process according to third embodiment) Next, a procedure of the switching process executed by the AP 100 according to the third embodiment will be described with reference to Fig. 21. Fig. 21 is a flowchart illustrating an example of a flow of a switching process on the AP 100 side according to the third embodiment. The example of Fig. 21 will be described assuming that the AP 100 is a target AP. Further, in the example of Fig. 21, description will be made on the assumption that the STA 200 is an STA 200 different from the roaming STA.

[0258] As illustrated in Fig. 21, the AP 100 receives the transmission request signal from the STA 200 (step S601). For example, when the AP 100 has received the transmission request signal from the STA 200 (step S601; Yes), the switching request signal is received (step S602).

[0259] Subsequently, the AP 100 transmits the response signal to the switching request signal (step S603). Then, the AP 100 determines whether notification information has been received from the STA 200 during the UL communication interruption period (step S604). For example, when the AP 100 receives the notification information from the STA 200 during the UL communication interruption period (step S604; Yes), the switching response signal is transmitted (step S605). Subsequently, the AP 100 transmits information regarding the additional UL communication interruption period (step S606).

[0260] Conversely, when the AP 100 has not received the UL communication from the STA 200 during the UL communication interruption period (step S604; No), the switching response signal is transmitted (step S609). Then, the AP 100 determines whether execute the channel access restriction (step S610).

[0261] For example, when the AP 100 determines not to execute the channel access restriction (step S610; No), the process ends. Conversely, when the AP 100 determines to execute the channel access restriction (step S610; Yes), information regarding the additional UL communication interruption period is transmitted (step S611). Subsequently, the AP 100 ends the process.

[0262] Conversely, when the AP 100 has not received the transmission request signal from the STA 200 (step S601; No), the switching request signal is received (step S607). Subsequently, the AP 100 transmits the response signal to the switching request signal (step S608). Then, the AP 100 transmits the switching response signal (step S609).

[0263] Subsequently, the AP 100 determines whether to execute the channel access restriction (step S610). For example, when the AP 100 determines not to execute the channel access restriction (step S610; No), the process ends. Conversely, when the AP 100 determines to execute the channel access restriction (step S610; Yes), information regarding the additional UL communication interruption period is transmitted (step S611). Subsequently, the AP 100 ends the process.

[0264] (3-4. Modification according to embodiment) The information processing according to the above-described first to third embodiments may be modified in various forms. Hereinafter, modifications of the first to third embodiments will be described.

[0265] (3-4-1. Other processes) In the first embodiment, the example in which the target AP transmits the trigger signal to the roaming STA together with the switching response signal when the low-delay traffic is generated in the roaming STA during the UL communication interruption period has been described, but the present disclosure is not limited thereto.

[0266] For example, the source AP may notify the target AP that all traffic of the roaming STA has been processed. For example, when Single Link is applied, a roaming STA can only activate a link with only one AP 100 at the same time. Therefore, the source AP is required to transmit data buffered in the source AP to the roaming STA before switching of a data path unless the data is forwarded to the target AP.

[0267] Here, it is also conceivable that the target AP executes UL communication and the source AP executes DL communication by switching the link. However, it takes time to switch the link. When communication starts in one link in the case of execution of communication in other link, the roaming STA cannot receive the traffic that cannot be received during switching of the link.

[0268] More specifically, when a roaming STA is transmitting UL traffic to a target AP and a source AP starts transmitting DL traffic to the roaming STA, the roaming STA cannot receive DL data.

[0269] The AP 100 side cannot identify that the roaming STA is switching a link. Therefore, when transmission starts during switching of the link, the roaming STA cannot receive data. For example, NPL 2 proposes a method of enabling a link with a target AP after processing traffic buffered in a source AP.

[0270] When the target AP transmits a switching response signal, it is necessary to notify that the source AP has processed all the traffic of the roaming STA in the case of Single Link. Accordingly, the source AP transmits a notification indicating that the traffic buffered for the target AP has been processed after all the traffic of the roaming STA has been processed to the target AP.

[0271] Hereinafter, an example in which the source AP notifies the target AP that all the traffic of the roaming STA has been processed will be described. Fig. 22 is a diagram illustrating an example of an AP switching process according to a modification. In the example of Fig. 22, it is assumed that the target AP transmits a switching response signal to the roaming STA.

[0272] In the example of Fig. 22, in the case of STA initiated roaming, the roaming STA transmits a switching request signal to the source AP. In the example of Fig. 22, the roaming STA transmits the switching request signal to the source AP at time t81.

[0273] Subsequently, when the source AP correctly receives the switching request signal from the roaming STA, the AP switching starts. In the example of Fig. 22, the source AP receives the switching request signal from the roaming STA. Then, when it is determined that the source AP correctly receives the switching request signal, the AP switching starts. In the example of Fig. 22, the UL communication interruption period is a period from time t81 to time t87.

[0274] Then, in the roaming STA, UL traffic is generated at time t82. Subsequently, the roaming STA transmits the notification information to the target AP at time t83. Then, the source AP transmits the data buffered at time t84 to the roaming STA.

[0275] Subsequently, the source AP transmits a notification indicating that the buffered traffic has been processed at time t85 to the target AP. The target AP transmits the switching response signal to the roaming STA at time t86. Accordingly, the communication system can improve transmission efficiency.

[0276] The notification indicating that the buffered traffic has been processed may be executed in a wired manner using the DS. The notification indicating that the buffered traffic has been processed may be executed wirelessly.

[0277] The Target AP may receive, from the source AP, information indicating a buffer state of the roaming STA and / or instruction information for instructing the roaming STA to execute low-delay transmission, together with a notification indicating that the traffic buffered in the source AP has been processed.

[0278] For example, when the notification indicating that the buffered traffic has been processed is transmitted, the source AP may transmit, to the target AP, a buffer state of the roaming STA or an indication such that the roaming STA can transmit the UL communication with a low-delay after AP switching.

[0279] Accordingly, even when only the source AP ascertains a traffic state of the roaming STA, the target AP can operate. For example, even when the target AP is prohibited from transmitting a signal during the UL communication interruption period, the source AP transmits the buffer state and the indication to the target AP, so that the target AP can operate.

[0280] (4. Other embodiments) The process according to each of the above-described embodiments may be executed in various different modes other than each of the above-described embodiments.

[0281] Of the processes described in the above embodiments, some or all of the processes described as being automatically executed can be manually executed, or some or all of the processes described as being manually executed can be automatically executed by a known method. Additionally, the processing procedure, specific name, and information including various types of data and parameters illustrated in the literature and the drawings can be arbitrarily changed unless otherwise mentioned. For example, the various types of information illustrated in each drawings are not limited to the illustrated information.

[0282] The constituents of the devices illustrated in the drawings are functionally conceptual, and are not necessarily physically configured as illustrated in the drawings. That is, a specific form of distribution and integration of the devices is not limited to the illustrated form, and some or all of the devices can be functionally or physically distributed and integrated in an arbitrary unit according to various loads, usage conditions, and the like.

[0283] The above-described embodiments and modifications can be appropriately combined within a range in which the processing content does not contradict each other.

[0284] The effects described in the present specification are merely exemplary and are not limited, and other effects may be obtained.

[0285] (5. Effects of communication device according to present disclosure) As described above, a communication device according to the present disclosure is a second communication device including a control unit that receives, from a first communication device (corresponding to a source AP in the embodiment), a second switching request signal for requesting switching a connection destination from the first communication device to a second communication device (corresponding to a target AP in the embodiment) in response to a first switching request signal transmitted from a terminal device (corresponding to a roaming STA in the embodiment) connected to the first communication device to the first communication device; and transmits, to the terminal device, a trigger signal for the terminal device to transmit data together with a switching response signal in response to switching from the first communication device to the second communication device based on the second switching request signal.

[0286] In this way, the communication device can immediately transmit data without interruption of another terminal device after receiving the switching response signal. Therefore, the communication device enables low-delay transmission of the UL traffic. For example, since the response signal by the UL data frame is returned to the switching response signal, the communication device is not required to transmit Ack indicating that the switching response signal is correctly transmitted.

[0287] The control unit receives a transmission request signal for requesting transmission of a switching response signal from the terminal device before receiving the second switching request signal.

[0288] Accordingly, the communication device can control an operation of the terminal device by receiving the transmission request signal from the terminal device.

[0289] The control unit receives the transmission request signal for requesting transmission of the switching response signal within the UL communication interruption period as the transmission request signal from the terminal device.

[0290] Accordingly, the communication device can have an operation determination right of the terminal device.

[0291] The control unit receives, from the terminal device, information varying depending on whether an encryption key between the second communication device and the terminal device is held.

[0292] Accordingly, the communication device can implement communication with high security.

[0293] The control unit receives notification information regarding data traffic from the terminal device during the UL communication interruption period.

[0294] Accordingly, the communication device can receive notification information necessary for determining the operation after transmitting the switching response signal.

[0295] The control unit transmits, to the terminal device, information regarding the operation after a UL communication interruption period together with the switching response signal.

[0296] Accordingly, the communication device can control an operation of the terminal device after the UL communication interruption period.

[0297] The control unit transmits, to the terminal device, information regarding a priority transmission period set as a period in which the terminal device is able to preferentially transmit data together with the switching response signal.

[0298] Accordingly, the communication device can easily obtain the UL transmission opportunity, so that low delay can be implemented. The communication device can transmit traffic simultaneously with other terminal devices by shifting a transmission timing at which the switching response signal is transmitted. Accordingly, the communication device can improve transmission efficiency.

[0299] The control unit transmits the switching response signal to another terminal device different from the terminal device.

[0300] Accordingly, the communication device can transmit a signal for controlling an operation of another terminal device by transmitting the switching response signal.

[0301] The control unit transmits the regarding the additional UL communication interruption period to the another terminal device.

[0302] Accordingly, the communication device can control the operation after the UL communication interruption period with respect to another terminal device.

[0303] The control unit receives, from the first communication device, a notification indicating that the traffic buffered by the first communication device is processed.

[0304] Accordingly, the communication device can transmit the switching response signal to the terminal device, for example, even during Single Link.

[0305] As described above, the terminal device according to the present disclosure includes a control unit that transmits a switching request signal for requesting switching a connection destination from the first communication device to the second communication device to the connected first communication device; and transmits data to the second communication device when the trigger signal for transmitting the data is received from the second communication device together with a switching response signal responding to switching from the first communication device to the second communication device.

[0306] In this way, when the terminal device has UL traffic for which low delay is required, the terminal device enables a request for executing low-delay transmission of the UL traffic after AP switching. The terminal device can start the UL communication by receiving the switching response signal from the second communication device.

[0307] The control unit transmits the transmission request signal for requesting transmission of the switching response signal to the second communication device before transmitting the switching request signal.

[0308] Accordingly, the terminal device can cause the communication device to control an operation of the terminal device.

[0309] The control unit transmits the transmission request signal for requesting transmission of the switching response signal within a UL communication interruption period as the transmission request signal to the second communication device.

[0310] Accordingly, the terminal device can transfer an operation determination right to the communication device.

[0311] Before the switching request signal is transmitted, the control unit transmits the transmission request signal to the second communication device using a multi-link setup frame or a roaming request frame.

[0312] Accordingly, the terminal device can appropriately transmit the transmission request signal to the communication device by using the multi-link setup frame or the roaming request frame.

[0313] The control unit transmits, to the second communication device, information varying depending on whether an encryption key between the second communication device and the terminal device is held.

[0314] Accordingly, the terminal device can implement communication in consideration of a security risk.

[0315] When data transmission occurs during the UL communication interruption period, the control unit transmits notification information regarding data traffic to the second communication device.

[0316] Accordingly, the terminal device can transmit the notification information necessary for determining the operation after the second communication device transmits the switching response signal.

[0317] The control unit receives the information regarding the operation after the UL communication interruption period from the second communication device together with the switching response signal.

[0318] Accordingly, the terminal device can ascertain the operation of the second communication device after the UL communication interruption period.

[0319] The control unit receives, from the second communication device, information regarding a priority transmission period set as a period in which the terminal device is able to preferentially transmit the data together with the switching response signal.

[0320] Accordingly, the terminal device can transmit traffic simultaneously with other terminal devices by shifting a timing at which the switching response signal is received.

[0321] (6. Configuration example of computer) The above-described series of processes can be executed by hardware or software. When the series of processes is executed by software, a program configuring the software is installed from a program recording medium to a computer embedded in dedicated hardware, a general-purpose personal computer, or the like.

[0322] Fig. 23 is a block diagram illustrating a configuration example of hardware of a computer that executes the above-described series of processes by a program.

[0323] A central processing unit (CPU) 801, a read only memory (ROM) 802, and a random access memory (RAM) 803 are mutually connected by a bus 804.

[0324] An input / output interface 805 is further connected to the bus 804. An input unit 806 configured with a keyboard, a mouse, or the like, and an output unit 807 configured with a display, a speaker, or the like are connected to the input / output interface 805. Information regarding the present technique, for example, information regarding handover (AP switching process) may be output or displayed from the output unit 807. From the input unit 806, input of information regarding the present technique, for example, information regarding handover (AP switching process), and confirmation or a response to the information output or displayed on the output unit 807 may be input. A storage unit 808 configured with a hard disk, a nonvolatile memory, or the like, a communication unit 809 configured with a network interface or the like, and a drive 810 that drives a removable medium 811 are connected to the input / output interface 805.

[0325] In the computer configured as described above, for example, the CPU 801 loads a program stored in the storage unit 808 into the RAM 803 via the input / output interface 805 and the bus 804 and executes the program to execute the above-described series of processes. For example, the CPU 801 may execute a processing program corresponding to the flowcharts of Figs. 14 to 15, 17, 18, 20, and 21 of the present technique.

[0326] The program executed by the CPU 801 is provided, for example, by being recorded in the removable medium 811 or via a wired or wireless transmission medium such as a local area network, the Internet, or digital broadcasting, and is installed in the storage unit 808.

[0327] The program executed by the computer may be a program in which processes are executed chronologically in the order described in the present specification, or may be a program in which processes are executed in parallel or at necessary timing such as a time at which a call is made.

[0328] (7. Application example) The present technique can be applied to various products. For example, the AP 100 (communication device) in Fig. 4, the STA 200 (terminal device) in Fig. 5, and the controller 300 may be implemented as a mobile terminal such as a smartphone, a tablet personal computer (PC), a notebook PC, a portable game terminal, a digital camera, a fixed terminal such as a television receiver, a projector, a printer, a digital scanner, a network storage, or an in-vehicle terminal such as a car navigation device or a drive recorder device. The AP 100 (communication device), the STA 200 (terminal device), and the controller 300 may be implemented as a machine to machine communication (M2M) terminal such as a smart meter, a vending machine, a remote monitoring device, or a point of sale (POS) terminal, or an internet of things (IoT) terminal. The AP 100 (communication device), the STA 200 (terminal device), and the controller 300 may be implemented as a terminal that requires low-delay and high reliability, such as an XR (extended reality / cross reality) device. Furthermore, the AP 100 (communication device), the STA 200 (terminal device), and the controller 300 may be wireless communication modules (for example, an integrated circuit module including one die) mounted on these terminals.

[0329] On the other hand, for example, the AP 100 (communication device), the STA 200 (terminal device), and the controller 300 may be implemented as an AP (wireless base station) of a wireless LAN that has a router function or does not have a router function. Furthermore, the AP 100 (communication device), the STA 200 (terminal device), and the controller 300 may be implemented as mobile wireless LAN routers. The AP 100 (communication device), the STA 200 (terminal device), and the controller 300 may be implemented as a base station of a cellular communication system and a femtocell. Further, the AP 100 (communication device), the STA 200 (terminal device), and the controller 300 may be wireless communication modules (for example, an integrated circuit module including one die) mounted on these devices.

[0330] (Configuration example of smartphone) Fig. 24 is a block diagram illustrating an overall configuration example of a smartphone 900 to which the present technique is applied. Fig. 24 illustrates a configuration example of the smartphone 900, but is not limited thereto, and may be a configuration example of various devices and functions described above.

[0331] The smartphone 900 includes a processor 901, a memory 902, a storage 903, an external connection interface 904, a camera 906, a sensor 907, a microphone 908, an input device 909, and a display device 910. In addition, the smartphone 900 includes a speaker 911, a wireless communication interface 913, an antenna switch 914, an antenna 915, a bus 917, a battery 918, and an auxiliary controller 919. The smartphone 900 may include all of the above units or may include some of the units.

[0332] The processor 901 may be, for example, a CPU or a system on chip (SoC), and controls functions of an application layer and other layers of the smartphone 900.

[0333] The memory 902 includes a RAM and a ROM, and stores programs and data executed by the processor 901.

[0334] The storage 903 includes a storage medium such as a semiconductor memory or a hard disk.

[0335] The external connection interface 904 is an interface for connecting an external device such as a memory card or a universal serial bus (USB) device to the smartphone 900.

[0336] The camera 906 includes, for example, an imaging element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), and generates a captured image.

[0337] The sensor 907 includes, for example, a sensor group such as a positioning sensor, a gyro sensor, a geomagnetic sensor, and an acceleration sensor.

[0338] The microphone 908 converts a voice input to the smartphone 900 into a voice signal.

[0339] The input device 909 includes, for example, a touch sensor that detects a touch on a screen of the display device 910, a keypad, a keyboard, a button, a switch, or the like, and receives an operation or information input from the user.

[0340] The display device 910 has a screen such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display, or a quantum dot (QD) display, and displays an output image of the smartphone 900.

[0341] The speaker 911 converts an audio signal output from the smartphone 900 into a voice.

[0342] The wireless communication interface 913 supports one or more of wireless LAN standards such as IEEE 802.11a, 11b, 11g, 11ac, 11ad, 11ax, 11ay, 11be, and 11bn, and their successor standards, and executes wireless communication.

[0343] The wireless communication interface 913 communicates with another device via an AP of a wireless LAN in an infrastructure mode. The wireless communication interface 913 directly communicates with another device in an ad hoc mode or a direct communication mode such as Wi-Fi Direct.

[0344] In Wi-Fi Direct, unlike the ad-hoc mode, one of two terminals operates as an AP, but communication is directly executed between terminals.

[0345] The wireless communication interface 913 typically includes a baseband processor, a radio frequency (RF) circuit, and a power amplifier. The wireless communication interface 913 may be a one-chip module in which a memory that stores a communication control program, a processor that executes the program, and related circuits are integrated.

[0346] In addition to a wireless LAN scheme, the wireless communication interface 913 may support other types of wireless communication schemes such as a short-range wireless communication scheme such as Bluetooth (registered trademark), a proximity wireless communication scheme such as NFC, or a 3GPP (registered trademark) cellular communication scheme such as 2G, 3G, 4G, 5G, and 6G. The wireless communication interface 913 may be a one-chip module supporting a plurality of wireless communication schemes or may be a combination of modules supporting some wireless communication schemes.

[0347] The antenna switch 914 switches a connection destination of the antenna 915 among a plurality of circuits (for example, a circuit for different wireless communication schemes, or a transmission system circuit and a reception system circuit) included in the wireless communication interface 913.

[0348] The antenna 915 has a single or a plurality of antenna elements (for example, a plurality of antenna elements included in a multiple input multiple output (MIMO) antenna or a plurality of antenna elements included in an array antenna), and is used for transmission and reception of wireless signals by the wireless communication interface 913.

[0349] The smartphone 900 is not limited to the example of Fig. 24, and may include a plurality of antennas (for example, an antenna for a wireless LAN, an antenna of a close proximity wireless communication scheme, an antenna of a cellular communication scheme, or the like). In that case, the antenna switch 914 may be omitted from the configuration of the smartphone 900.

[0350] The bus 917 connects the processor 901, the memory 902, the storage 903, the external connection interface 904, the camera 906, the sensor 907, the microphone 908, the input device 909, the display device 910, the speaker 911, the wireless communication interface 913, and the auxiliary controller 919 to each other.

[0351] The battery 918 supplies power to each block of the smartphone 900 illustrated in Fig. 24 via a power supply line partially indicated by a broken line in the drawing. The auxiliary controller 919 operates minimum necessary functions of the smartphone 900, for example, in a sleep mode. The battery 918 may be charged via the external connection interface 904. The battery 918 may have a function capable of reading information regarding a remaining amount of power, an accumulated energization time, or an accumulated supply power amount. The processor 901, the wireless communication interface 913, or the auxiliary controller 919 may control any function of the above-described embodiments based on the information read from the battery 918.

[0352] In the smartphone 900 illustrated in Fig. 24, for example, the communication control unit 116 in Fig. 4 or the communication control unit 216 in Fig. 5 may be implemented in the wireless communication interface 913. For example, the processing program corresponding to the flowcharts of Figs. 14, 15, 17, 18, 20, and 21 may be executed in the wireless communication interface 913. At least some of these functions may be implemented in the processor 901 or the auxiliary controller 919.

[0353] The smartphone 900 may operate as a wireless AP (software AP) when the processor 901 executes an AP function at an application level. The wireless communication interface 913 may have a wireless AP function. The processor 901 or the wireless communication interface 913 has a tethering function using a wireless LAN scheme and a cellular communication scheme, and may transmit payload data received by the cellular communication scheme by the wireless LAN scheme or may transmit payload data received by the wireless LAN scheme by the cellular communication scheme. The smartphone 900 may be enabled with a tethering function with a user input.

[0354] Further, the smartphone 900 may include a biometric authentication unit (fingerprint authentication, palm shape authentication, voice authentication, blood vessel authentication, face authentication, iris authentication, or retina authentication). At that time, the wireless communication interface 913 on which the communication control unit 116 in Fig. 4 or the communication control unit 216 in Fig. 5 is mounted is configured to receive power supply from the same battery 918 as at least one of the display device 910, the speaker 911, and the biometric authentication unit.

[0355] In the smartphone 900, information is displayed from at least one of the display device 910 and the speaker 911 based on communication with an external device by the wireless communication interface 913. At that time, information regarding the present technique, for example, information regarding handover (switching process of the AP 100) may be output as the information from at least one of the display device 910 and the speaker 911. The input device 909 may input confirmation or a response to information output from at least one of the display device 910 and the speaker 911.

[0356] (Configuration example of in-vehicle device) Fig. 25 is a block diagram illustrating an example of an overall configuration of an in-vehicle device 920 to which the present technique is applied. Although Fig. 25 is described as a configuration example of the in-vehicle device 920, the present disclosure is not limited thereto, and may be a configuration example of the above-described various devices and functions.

[0357] The in-vehicle device 920 is configured to include a processor 921, a memory 922, a global navigation satellite system (GNSS) module 924, a sensor 925, a data interface 926, a content player 927, and a storage medium interface 928. The in-vehicle device 920 is configured to include an input device 929, a display device 930, a speaker 931, a wireless communication interface 933, an antenna switch 934, an antenna 935, and a battery 938. The in-vehicle device 920 may have a configuration including all of the above units, or may have a configuration including a some of the units.

[0358] The processor 921 may be, for example, a CPU or an SoC and controls a navigation function and other functions of the in-vehicle device 920. The processor 921 can also control a drive system of a vehicle such as a brake, an accelerator, or a steering based on information obtained through communication based on the present technique.

[0359] The memory 922 includes a RAM and a ROM, and stores programs and data executed by the processor 921.

[0360] The GNSS module 924 measures a position (for example, latitude, longitude, and altitude) of the in-vehicle device 920 using a GNSS signal received from a GNSS satellite.

[0361] The sensor 925 includes, for example, a sensor group such as a gyro sensor, a geomagnetic sensor, a millimeter wave radar, a camera (imaging element such as CCD or CMOS), and an atmospheric pressure sensor.

[0362] For example, the data interface 926 is connected to an in-vehicle network 941 via a terminal (not illustrated) and acquires data generated on the vehicle side such as vehicle-side data.

[0363] The content player 927 reproduces content stored in a storage medium (for example, a CD or DVD) inserted into the storage medium interface 928 or content received via the wireless communication interface 933.

[0364] The input device 929 includes, for example, a touch sensor that detects a touch on the screen of the display device 930, a button, a switch, or the like and receives an operation or information input from the user. For example, the input device 929 may input confirmation or a response to information output from at least one of the display device 930 and the speaker 931.

[0365] The display device 930 has a screen such as an LCD, an OLED display, or a QD display, and displays an image of a navigation function or content to be reproduced or information regarding the present technique, for example, information regarding handover (AP switching process).

[0366] The speaker 931 outputs a navigation function, audio of content to be reproduced, or information regarding the present technique, for example, information regarding handover (AP switching process).

[0367] In the in-vehicle device 920, a navigation function and a function by the content player 927 are optional. The navigation function and the content player 927 may be removed from the configuration of the in-vehicle device 920.

[0368] The wireless communication interface 933 supports one or more of wireless LAN standards such as IEEE 802.11a, 11b, 11g, 11n, 11ac, 11ad, 11ax, 11ay, 11be, 11bn, and their successors, and executes wireless communication.

[0369] The wireless communication interface 933 communicates with another device via an AP of a wireless LAN in an infrastructure mode. The wireless communication interface 933 directly communicates with another device in an ad hoc mode or a direct communication mode such as Wi-Fi Direct.

[0370] In Wi-Fi Direct, unlike the ad-hoc mode, one of two terminals operates as an AP, but communication is directly executed between terminals.

[0371] The wireless communication interface 933 typically includes a baseband processor, an RF circuit, a power amplifier, and the like. The wireless communication interface 933 may be a one-chip module in which a memory that stores a communication control program, a processor that executes the program, and related circuits are integrated.

[0372] In addition to the wireless LAN scheme, the wireless communication interface 933 may support other types of wireless communication schemes such as a short-range wireless communication scheme such as Bluetooth, a proximity wireless communication scheme such as NFC, or a 3GPP cellular communication scheme such as 2G, 3G, 4G, 5G, and 6G. The wireless communication interface 933 may be a one-chip module supporting a plurality of wireless communication schemes or may be a combination of modules supporting some wireless communication schemes.

[0373] The antenna switch 934 switches a connection destination of the antenna 935 among a plurality of circuits (for example, a circuit for different wireless communication schemes, or a transmission system circuit and a reception system circuit) included in the wireless communication interface 933.

[0374] The antenna 935 has a single or a plurality of antenna elements (for example, a plurality of antenna elements included in a multiple input multiple output (MIMO) antenna or a plurality of antenna elements included in an array antenna), and is used for transmission and reception of wireless signals by the wireless communication interface 933.

[0375] The in-vehicle device 920 is not limited to the example of Fig. 25, and may include a plurality of antennas 935 (for example, an antenna for a wireless LAN, an antenna of a close proximity wireless communication scheme, an antenna of a cellular communication scheme, or the like.). In this case, the antenna switch 934 may be omitted from the configuration of the in-vehicle device 920.

[0376] The battery 938 supplies power to each block of the in-vehicle device 920 illustrated in Fig. 25 via a power supply line partially indicated by a broken line in the drawing. The battery 938 may store electric power supplied from the vehicle side. The in-vehicle device 920 may use power supplied from the vehicle side via a voltage regulator or a capacitor without mounting a battery.

[0377] In the in-vehicle device 920 illustrated in Fig. 25, for example, the communication control unit 116 in Fig. 4 or the communication control unit 216 in Fig. 5 may be implemented in the wireless communication interface 933. For example, the processing program corresponding to the flowcharts of Figs. 14 and 15, 17 and 18, and 20 and 21 may be executed in the wireless communication interface 933. At least some of these functions may be implemented in the processor 921.

[0378] The wireless communication interface 933 may operate as the AP 100 (communication device), the STA 200 (terminal device), or the controller 300 described above and may provide wireless connection to a terminal of a user in the vehicle. For example, the wireless communication interface 933 may connect the in-vehicle device 920 to another peripheral device, and the in-vehicle device 920 may use CarPlay (registered trademark) or Android Auto (registered trademark). The wireless communication interface 933 may connect the in-vehicle device 920 to another peripheral device by a short-range wireless communication scheme, an infrastructure mode, or a wireless LAN scheme by Wi-Fi Direct.

[0379] The in-vehicle device 920 may operate as a wireless AP (software AP) when the processor 921 executes an AP function at an application level. The wireless communication interface 933 may have a wireless AP function. The processor 921 or the wireless communication interface 933 has a tethering function using the wireless LAN scheme and the cellular communication scheme, and may transmit the payload data received by the cellular communication scheme by the wireless LAN scheme or may transmit the payload data received by the wireless LAN scheme by the cellular communication scheme. The in-vehicle device 920 may be enabled with the tethering function by the user's input.

[0380] The present technique may be implemented as an in-vehicle system (or vehicle) 940 including one or more blocks of the above-described in-vehicle device 920, the in-vehicle network 941, and the vehicle-side module 942. The vehicle-side module 942 may generate vehicle-side data such as vehicle speed information, engine speed information, information regarding a vehicle-side battery, or failure information and may output the generated data to the in-vehicle network 941, and the processor 921 or the wireless communication interface 933 may control any function of the above-described embodiments based on vehicle-side data acquired via the in-vehicle network 941.

[0381] (Configuration Example of Wireless AP) Fig. 26 is a block diagram illustrating an example of an overall configuration of a wireless AP 950 to which the present technique is applied. Fig. 26 illustrates a configuration example of the wireless AP 950, but the present disclosure is not limited thereto, and any of the configuration examples of various devices and functions described above may be applied.

[0382] The wireless AP 950 includes a controller 951, a memory 952, an input device 954, a display device 955, a network interface 957, a wireless communication interface 963, an antenna switch 964, and an antenna 965. The wireless AP 950 may include all of the above units, or may include some of the units.

[0383] The controller 951 may be, for example, a CPU or a digital signal processor (DSP), and operates various functions (for example, access restriction, routing, encryption, a firewall, log management, and the like) of an Internet protocol (IP) layer and higher layers of the wireless AP 950.

[0384] The memory 952 includes a RAM and a ROM, and stores a program executed by the controller 951 and various types of control information (for example, a terminal list, a routing table, an encryption key, a security setting, a log, and the like).

[0385] The input device 954 includes, for example, a button, a switch, and the like, and receives an operation from a user. For example, the input device 954 may input confirmation or a response to the information output from the display device 955. The input device 954 may receive an input of switching on / off a radio function and switching a router function / access point function by an operation from the user.

[0386] The display device 955 includes an LED lamp and displays an operation status of the wireless AP 950. The display device 955 may display information regarding the present technique, for example, information regarding handover (an AP switching process).

[0387] The network interface 957 is a wired communication interface for the wireless AP 950 for connection to the wired communication network 958. The network interface 957 may have a plurality of connection terminals. The network interface 957 may output, as a wired signal, payload data included in a wireless signal input from the wireless communication interface 963, may input, as a wired signal, payload data output as a wireless signal from the wireless communication interface 963, or may operate in parallel with or independently of an input and an output of a wireless signal by the wireless communication interface 963 to input and output a wired signal. The wired communication network 958 may be a LAN such as Ethernet (registered trademark), or may be a wide area network (WAN).

[0388] The wireless communication interface 963 supports one or more of wireless LAN standards, such as IEEE 802.11a, 11b, 11g, 11n, 11ac, 11ad, 11ax, 11ay, 11be, 11bn, and their successors, and provides wireless connectivity as an AP to nearby terminals. When the wireless AP 950 is mounted on a base station and a femtocell of a cellular communication scheme, the wireless communication interface 963 may support other types of wireless communication schemes such as a 3GPP cellular communication scheme such as 2G, 3G, 4G, 5G, and 6G in addition to the wireless LAN scheme. The wireless communication interface 963 may be a one-chip module supporting a plurality of wireless communication schemes, or may be a combination of modules supporting some wireless communication schemes.

[0389] The wireless communication interface 963 typically includes a baseband processor, an RF circuit, and a power amplifier.

[0390] The wireless communication interface 963 may be a one-chip module in which a memory that stores a communication control program, a processor that executes the program, and related circuits are integrated.

[0391] The antenna switch 964 switches a connection destination of the antenna 965 among a plurality of circuits (for example, a circuit for different wireless communication schemes, or a transmission system circuit and a reception system circuit) included in the wireless communication interface 963.

[0392] The antenna 965 has a single or a plurality of antenna elements (for example, a plurality of antenna elements included in a multiple input multiple output (MIMO) antenna or a plurality of antenna elements included in an array antenna), and is used for transmission and reception of wireless signals by the wireless communication interface 963.

[0393] In the wireless AP 950 illustrated in Fig. 26, for example, the communication control unit 116 in Fig. 4 or the communication control unit 216 in Fig. 5 may be implemented in the wireless communication interface 963. For example, the processing program corresponding to the flowcharts of Figs. 14 and 15, 17 and 18, and 20 and 21 may be executed in the wireless communication interface 963. At least some of these functions may be implemented in the controller 951.

[0394] In the above-described embodiment, examples for embodying the present technique have been given as examples, and the matters in the embodiments and aspects of the present disclosure specifying matters in the claims have a correspondence relationship. Similarly, the matters specifying aspects of the disclosure in the claims and the matters in the embodiments of the present technique denoted by the same names as the matters specifying aspects present disclosure have a correspondence relationship. However, the present technique is not limited to the embodiments and can be embodied by making various modifications to the embodiments without departing from the gist thereof.

[0395] Some or all of the communication device, the terminal device, and the controller described in the above-described embodiments may be implemented as or in, for example, circuitry such as a semiconductor chip (integrated circuit (IC)) having a wireless communication control function. Some or all of the communication device, the terminal device, and the controller may be implemented by one semiconductor chip on which a plurality of functions such as a system on chip (SoC) are mounted, or may be implemented by combining a plurality of semiconductor chips having a single function such as a processor. Further, a plurality of SoCs may be combined or may be implemented by combining a semiconductor chip of a single function and the SoC. Each unit may be implemented in or by circuitry such as a semiconductor chip such as a dedicated application specific integrated circuit (ASIC) for implementing each unit, or may be implemented by a combination of a general-purpose processor, software, firmware, and the like, or a semiconductor chip such as a field programmable gate array (FPGA).

[0396] The processing procedures described in the above-described embodiments may be regarded as a method having a series of these procedures, or may be regarded as a program for causing the computer to execute the series of these procedures or a recording medium storing the program.

[0397] As this recording medium, for example, a compact disc (CD), a mini disc (MD), a digital versatile disc (DVD), a memory card, a Blu-ray (registered trademark) disc, or the like can be used.

[0398] In the present specification, a system means a set of a plurality of constituents (devices, modules (components), etc.), and it does not matter whether all the constituents are in the same housing. Accordingly, a plurality of devices housed in separate casings and connected via a network and one device in which a plurality of modules is housed in one causing are both systems.

[0399] The effects described in the present specification are merely exemplary and are not limited, and other effects may be provided.

[0400] The embodiments of the present technique are not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present technique.

[0401] For example, the present technique can have a configuration of cloud computing in which one function is shared and processed in cooperation of a plurality of devices via a network.

[0402] Each step described in the above-described flowchart can be executed by one device or can be shared and executed by a plurality of devices.

[0403] Furthermore, when a plurality of processes is included in one step, the plurality of processes included in the one step can be executed by one device or can be shared and executed by a plurality of devices. Further, the functionality of the elements or units disclosed herein may be implemented in or using circuitry or processing circuitry which includes general purpose processors, special purpose processors, integrated circuits, ASICs (“Application Specific Integrated Circuits”), FPGAs (“Field-Programmable Gate Arrays”), conventional circuitry and / or combinations thereof which are programmed, using one or more programs stored in one or more memories, or otherwise configured to perform the disclosed functionality. Processors and controllers are considered processing circuitry or circuitry as they include transistors and other circuitry therein. In the disclosure, the circuitry, units, or means can be hardware that carry out or are programmed to perform the recited functionality. The hardware may be any hardware disclosed herein which is programmed or configured to carry out the recited functionality. Also, the memory (e.g., storage / memory units 130, 220, 808, 902, 903, 922, 952) can store a computer program which includes computer instructions. These computer instructions provide the logic and routines that enable the hardware (e.g., processing circuitry or circuitry) to perform the method disclosed herein. This computer program can be implemented in known formats as a computer-readable storage medium, a computer program product, a memory device, a record medium such as a CD-ROM or DVD, and / or the memory of a FPGA or ASIC.

[0404] The present technique can also have the following configurations. (1) A communication device that is a second communication device, comprising a control unit or control circuitry configured to receive, from a first communication device, a second switching request signal for requesting switching a connection destination from the first communication device to the second communication device in response to a first switching request signal transmitted from a terminal device (which may be connected to the first communication device) to the first communication device, and transmit, to the terminal device, a trigger signal for the terminal device to transmit data together with a switching response signal in response to switching from the first communication device to the second communication device based on the second switching request signal. (2) The communication device according to (1), wherein the control unit receives a transmission request signal for requesting transmission of the switching response signal from the terminal device before receiving the second switching request signal. (3) The communication device according to (2), wherein the control unit receives the transmission request signal for requesting transmission of the switching response signal within a UL communication interruption period as the transmission request signal from the terminal device. (4) The communication device according to (3), wherein the control unit receives the transmission request signal from the terminal device using a multi-link setup frame or a roaming request frame before receiving the second switching request signal. (5) The communication device according to (1), wherein the control unit receives, from the terminal device, information varying depending on whether an encryption key between the second communication device and the terminal device is held. (6) The communication device according to (1), wherein the control unit receives notification information regarding traffic of the data from the terminal device within a UL communication interruption period. (7) The communication device according to (1), wherein the control unit transmits, to the terminal device, information regarding an operation after a UL communication interruption period together with the switching response signal. (8) The communication device according to (1), wherein the control unit transmits, to the terminal device, information regarding a priority transmission period set as a period in which the terminal device is able to preferentially transmit the data together with the switching response signal. (9) The communication device according to (1), wherein the control unit transmits the switching response signal to another terminal device different from the terminal device. (10) The communication device according to (9), wherein the control unit transmits information regarding an additional UL communication interruption period to the another terminal device. (11) The communication device according to (1), wherein the control unit receives, from the first communication device, a notification indicating that traffic buffered by the first communication device is processed. (12) The communication device according to (11), wherein the control unit receives, from the first communication device, information indicating a buffer state of the terminal device, and / or instruction information for instructing the terminal device to execute low-delay transmission together with a notification indicating that the traffic buffered in the first communication device is processed. (13) A terminal device comprising a control unit configured to transmit, to a connected first communication device, a switching request signal for making a request for switching a connection destination from the first communication device to a second communication device, and transmit data to the second communication device when a trigger signal for transmitting data is received from the second communication device together with a switching response signal responding to switching from the first communication device to the second communication device. (14) The terminal device according to (13), wherein the control unit transmits a transmission request signal for requesting transmission of the switching response signal to the second communication device before transmitting the switching request signal. (15) The terminal device according to (14), wherein the control unit transmits the transmission request signal for requesting transmission of the switching response signal within a UL communication interruption period as the transmission request signal to the second communication device. (16) The terminal device according to (14), wherein the control unit transmits the transmission request signal to the second communication device using a multi-link setup frame or a roaming request frame before transmitting the switching request signal. (17) The terminal device according to (13), wherein the control unit transmits, to the second communication device, information varying depending on whether an encryption key between the second communication device and the terminal device is held. (18) The terminal device according to (13), wherein the control unit transmits notification information regarding traffic of the data to the second communication device when the transmission of the data occurs during a UL communication interruption period. (19) The terminal device according to (13), wherein the control unit receives information regarding an operation after the UL communication interruption period from the second communication device together with the switching response signal. (20) The terminal device according to (13), wherein the control unit receives, from the second communication device, information regarding a priority transmission period set as a period in which the terminal device is able to preferentially transmit the data together with the switching response signal. (21) A communication method executed by a second communication device, the method comprising: receiving, from a first communication device, a second switching request signal for requesting switching a connection destination from the first communication device to a second communication device in response to a first switching request signal transmitted from a terminal device connected to the first communication device to the first communication device; and transmitting, to the terminal device, a trigger signal for the terminal device to transmit data together with a switching response signal in response to switching from the first communication device to the second communication device based on the second switching request signal. (22) A communication method executed by a terminal device, the method comprising: transmitting, to a connected first communication device, a switching request signal for making a request for switching a connection destination from the first communication device to a second communication device; and transmitting data to the second communication device when a trigger signal for transmitting data is received from the second communication device together with a switching response signal responding to switching from the first communication device to the second communication device.

[0405] 100 AP 110 Wireless communication unit 111 Common MAC processing unit 112A, 112B Individual MAC processing unit 113A, 113B Signal processing unit 114A, 114B RF unit 115A, 115B RF switch 116 Communication control unit 117A, 117B Processing unit 118A_1, 118A_2, 118B_1, 118B_2 Antenna 120 Backhaul communication unit 130 Storage unit / memory 140 Control unit / control circuitry 200 STA 210 Wireless communication unit 211 Common MAC processing unit 212A, 212B Individual MAC processing unit 213A, 213B Signal processing unit 214A, 214B RF unit 215A, 215B RF switch 216 Communication control unit 217A, 217B Processing unit 218A_1, 218A_2, 218B_1, 218B_2 Antenna 220 Storage unit / memory 230 Control unit / control circuitry

Claims

1. A communication device that is a second communication device, comprising: 　　control circuitry configured to 　　　　receive, from a first communication device, according to a wireless local area network standard or scheme, a second switching request signal to request switching a connection destination from the first communication device to the second communication device in response to a first switching request signal transmitted from a terminal device to the first communication device, and 　　　　transmit, to the terminal device, according to the wireless local area network standard or scheme, a trigger signal for the terminal device to transmit data, together with a switching response signal, in response to switching the connection destination from the first communication device to the second communication device based on the second switching request signal from the first communication device.

2. The communication device according to claim 1, wherein 　　the control circuitry is configured to 　　receive a transmission request signal to request transmission of the switching response signal from the terminal device before receiving the second switching request signal.

3. The communication device according to claim 2, wherein 　　the control circuitry is configured to 　　receive the transmission request signal to request transmission of the switching response signal within a UL communication interruption period as the transmission request signal from the terminal device.

4. The communication device according to claim 1, wherein 　　the control circuitry is configured to 　　receive, from the terminal device, information varying depending on whether an encryption key between the second communication device and the terminal device is held.

5. The communication device according to claim 1, wherein 　　the control circuitry is configured to 　　receive notification information regarding traffic of the data from the terminal device within a UL communication interruption period.

6. The communication device according to claim 1, wherein 　　the control circuitry is configured to 　　transmit, to the terminal device, information regarding an operation after a UL communication interruption period, together with the switching response signal.

7. The communication device according to claim 1, wherein 　　the control circuitry is configured to 　　transmit, to the terminal device, information regarding a priority transmission period set as a period in which the terminal device is able to preferentially transmit the data, together with the switching response signal.

8. The communication device according to claim 1, wherein 　　the control circuitry is configured to 　　transmit the switching response signal to another terminal device different from the terminal device.

9. The communication device according to claim 8, wherein 　　the control circuitry is configured to 　　transmit information regarding an additional UL communication interruption period to the another terminal device.

10. The communication device according to claim 1, wherein 　　the control circuitry is configured to 　　receive, from the first communication device, a notification indicating that traffic buffered by the first communication device is processed.

11. The communication device according to claim 10, wherein 　　the control circuitry is configured to 　　receive, from the first communication device, information indicating a buffer state of the terminal device, and / or instruction information to instruct the terminal device to execute low-delay transmission, together with a notification indicating that the traffic buffered in the first communication device is processed.

12. A terminal device comprising: 　　control circuitry configured to 　　　　transmit, to a connected first communication device, according to a wireless local area network standard or scheme, a switching request signal to make a request to switch a connection destination from the first communication device to a second communication device, and 　　　　transmit, according to the wireless local area network standard or scheme, data to the second communication device under a condition where a trigger signal to transmit data is received from the second communication device, together with a switching response signal responding to switching the connection destination from the first communication device to the second communication device.

13. The terminal device according to claim 12, wherein 　　the control circuitry is configured to 　　transmit a transmission request signal to request transmission of the switching response signal to the second communication device before transmitting the switching request signal.

14. The terminal device according to claim 13, wherein 　　the control circuitry is configured to 　　transmit the transmission request signal to request transmission of the switching response signal within a UL communication interruption period as the transmission request signal to the second communication device.

15. The terminal device according to claim 12, wherein 　　the control circuitry is configured to 　　transmit, to the second communication device, information varying depending on whether an encryption key between the second communication device and the terminal device is held.

16. The terminal device according to claim 12, wherein 　　the control circuitry is configured to 　　transmit notification information regarding traffic of the data to the second communication device under a condition where the transmission of the data occurs during a UL communication interruption period.

17. The terminal device according to claim 12, wherein 　　the control circuitry is configured to 　　receive information regarding an operation after the UL communication interruption period from the second communication device, together with the switching response signal.

18. The terminal device according to claim 12, wherein 　　the control circuitry is configured to 　　receive, from the second communication device, information regarding a priority transmission period set as a period in which the terminal device is able to preferentially transmit the data together with the switching response signal.

19. A communication method executed by a second communication device, the method comprising: 　　receiving, from a first communication device, according to a wireless local area network standard or scheme, a second switching request signal to request switching a connection destination from the first communication device to a second communication device in response to a first switching request signal transmitted from a terminal device to the first communication device; and 　　transmitting, to the terminal device, according to the wireless local area network standard or scheme, a trigger signal for the terminal device to transmit data, together with a switching response signal in response to switching the connection destination from the first communication device to the second communication device based on the second switching request signal from the first communication device.

20. A communication method executed by a terminal device, the method comprising: 　　transmitting, to a connected first communication device, according to a wireless local area network standard or scheme, a switching request signal to make a request to switch a connection destination from the first communication device to a second communication device; and 　　transmitting, according to the wireless local area network standard or scheme, data to the second communication device under a condition where a trigger signal to transmit data is received from the second communication device, together with a switching response signal responding to switching from the first communication device to the second communication device.

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