Communication devices, terminal devices, and communication methods

Abstract

To propose communication devices, terminal devices, and communication methods that can ensure data continuity. [Solution] The communication device according to the present disclosure is a second communication device which receives a second switching request signal from the first communication device in response to a first switching request signal transmitted to the first communication device from a terminal device connected to the first communication device, and which requests that the connection destination be switched from the first communication device to the second communication device, and which includes a control unit that transmits to the terminal device 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, along with a trigger signal for the terminal device to transmit data.

Description

Technical Field

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

Background Art

[0002] In recent years, in various use cases such as homes, offices, and factories, environments where multiple access points (hereinafter sometimes referred to as APs) are installed and a high-speed and highly reliable Wi-Fi (registered trademark) network is constructed have been increasing.

[0003] In an environment where such multiple APs are installed, a terminal device (station or station terminal; hereinafter sometimes referred to as STA) can continue good communication, for example, by selecting an AP with good communication quality and performing handover processing. Hereinafter, switching the AP that is the connection destination may be referred to as AP switching.

[0004] For example, as an example of handover processing, in IEEE802.11be / Multi-Link Operation, the operation of Seamless Handover using a defined MLD (Multi-Link Device) Entity is being considered. With Seamless Handover, the STA can receive downlink (DL) data transmitted from the AP without interruption.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 2

[0006] However, in conventional handover processes, uplink (UL) communication from the STA to the AP is interrupted for a period of time (which may be referred to as the UL communication interruption period below). Therefore, for example, if low-latency traffic occurs during the UL communication interruption period, the STA has no choice but to transmit the low-latency traffic after the UL communication interruption period, and there are times when data continuity cannot be guaranteed.

[0007] Therefore, this disclosure proposes a communication device, a terminal device, and a communication method that can ensure data continuity.

[0008] It should be noted that the above-mentioned problems or objectives are merely one of several problems or objectives that can be solved or achieved by the multiple embodiments disclosed herein. [Means for solving the problem]

[0009] To solve the above problems, one form of communication device according to the present disclosure is a second communication device which receives from the first communication device a second switching request signal that requests switching the connection destination from the first communication device to the second communication device in response to a first switching request signal transmitted to the first communication device from a terminal device connected to the first communication device, and which transmits to the terminal device a trigger signal for the terminal device to transmit data, along with a switching response signal that responds to switching from the first communication device to the second communication device based on the second switching request signal. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows an example of a communication system related to this disclosure. [Figure 2] This figure shows an example of AP switching processing using Single Link. [Figure 3] This figure shows an example of AP switching processing using Dual Link. [Figure 4] This is a block diagram showing an example configuration of an AP according to the embodiment of this disclosure. [Figure 5] This is a block diagram showing an example configuration of STA according to the embodiment of this disclosure. [Figure 6] This figure shows an example of AP switching processing using a trigger signal according to the first embodiment. [Figure 7] This figure shows an example of AP switching processing when using a transmittable frame according to the first embodiment. [Figure 8] This figure shows an example of the frame configuration of a switching request signal according to the first embodiment. [Figure 9] This figure shows an example of AP switching processing using notification information according to the first embodiment. [Figure 10] This figure shows an example of the A-Control field format according to the first embodiment. [Figure 11] This figure shows an example of a format when using Element according to the first embodiment. [Figure 12]It is a diagram showing an example of an AP switching process when notifying the operation after AP switching according to the first embodiment. [Figure 13] It is a diagram showing an example of the frame configuration of a switching response signal according to the first embodiment. [Figure 14] It is a flowchart showing an example of the flow of the switching process on the STA side according to the first embodiment. [Figure 15] It is a flowchart showing an example of the flow of the switching process on the AP side according to the first embodiment. [Figure 16] It is a diagram showing an example of an AP switching process according to the second embodiment. [Figure 17] It is a flowchart showing an example of the flow of the switching process on the STA side according to the second embodiment. [Figure 18] It is a flowchart showing an example of the flow of the switching process on the AP side according to the second embodiment. [Figure 19] It is a diagram showing an example of an AP switching process according to the third embodiment. [Figure 20] It is a flowchart showing an example of the flow of the switching process on the STA side according to the third embodiment. [Figure 21] It is a flowchart showing an example of the flow of the switching process on the AP side according to the third embodiment. [Figure 22] It is a diagram showing an example of an AP switching process according to a modification. [Figure 23] It is a block diagram showing an example of the hardware configuration of a computer that executes the above-described series of processes by a program. [Figure 24] It is a block diagram showing a schematic configuration example of a smartphone to which the present technology is applied. [Figure 25] It is a block diagram showing an example of a schematic configuration of an in-vehicle device to which the present technology is applied. [Figure 26] It is a block diagram showing an example of a schematic configuration of a wireless device to which the present technology is applied.

Embodiments for Carrying Out the Invention

[0011] Embodiments of this disclosure will be described in detail below with reference to the drawings. In each of the following embodiments, the same parts will be denoted by the same reference numerals to avoid redundant descriptions.

[0012] Furthermore, in this specification and drawings, similar components of embodiments may be distinguished by adding at least one different alphabet and number after the same reference numeral. However, if there is no need to particularly distinguish each of the similar components, only the same reference numeral will be used.

[0013] The one or more embodiments (including examples, modifications, and applications) described below can each be implemented independently. On the other hand, at least some of the embodiments described below may be implemented in appropriate combination with at least some of the other embodiments. These embodiments may contain novel features that differ from each other. Therefore, these embodiments may contribute to solving different objectives or problems and may produce different effects.

[0014] This disclosure will be explained in the order of the items shown below. 1. Introduction 1-1.Background 1-2. Communication Systems 1-3. Overview of Embodiments 2. Example of a communication system configuration 2-1. Example of AP configuration 2-2. Example of STA configuration 3. Example of a communication system's processing 3-1. First Embodiment 3-1-1. Processing according to the first embodiment 3-1-2. Limitations on the number of frames that can be transmitted. 3-1-3. Information Exchange 3-1-4. Operation after AP switching is complete 3-1-5. Flowchart showing the procedure for the STA-side switching process according to the first embodiment. 3-1-6. Flowchart showing the procedure for the AP-side switching process according to the first embodiment. 3-2. Second Embodiment 3-2-1. Processing according to the second embodiment 3-2-2. Flowchart showing the procedure for switching on the STA side according to the second embodiment 3-2-3. Flowchart showing the procedure for the AP-side switching process according to the second embodiment. 3-3. Third Embodiment 3-3-1. Processing according to the third embodiment 3-3-2. Flowchart showing the procedure for switching on the STA side according to the third embodiment 3-3-3. Flowchart showing the procedure for the AP-side switching process according to the third embodiment 3-4. Modified Examples According to the Embodiment 3-4-1. Other processes 4. Other Embodiments 5. Effects of the communication device related to this disclosure 6. Example of a computer configuration 7. Application Examples

[0015] (1. Introduction) (1-1. Background) In recent years, the use of multiple access points (APs) has increased to expand Wi-Fi coverage and ensure stable communication. In particular, in office environments, on campuses, and in factories where wide communication coverage is required, large-scale networks are sometimes constructed using multiple APs and a wireless LAN controller to manage them.

[0016] In such cases, to avoid traffic congestion caused by the movement of STAs or an increase in the number of STAs connected to APs, STAs may switch the AP they are connected to. Discussions regarding Seamless Roaming, which ensures data continuity by performing AP switching seamlessly, are taking place in IEEE 802.11bn, which is equivalent to Wi-Fi 8.

[0017] Furthermore, IEEE 802.11be, which is equivalent to Wi-Fi 7, adopted Multi-Link Operation (MLO). MLO is a wireless communication method that uses multiple links (frequency bands). Devices that support MLO are called Multi-Link Devices (MLDs). MLDs can establish multiple links by coordinating multiple wireless interfaces.

[0018] MLD divides the Medium Access Control (MAC) sublayer into multiple (e.g., two) functional groups. For example, MLD divides the MAC sublayer into two functional groups: 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 functions for managing the network and sequence number. The L-MAC is an independent processing unit for each interface. For example, the L-MAC has the function of performing channel access that operates independently on each wireless interface. In this way, MLD can achieve low latency, high reliability transmission, and high throughput by utilizing multiple links.

[0020] Furthermore, as a method to achieve Seamless Roaming, IEEE 802.11bn proposes a method that utilizes a Centralized system architecture in which the U-MAC is shared among multiple access points (APs). However, the feasibility of an architecture that spatially distributes the U-MAC, L-MAC, and lower layers is a concern from the perspective of complexity. It should be noted that this method is discussed under the assumption of MLD (Multi-Level Distribution).

[0021] In addition, IEEE 802.11bn discusses a method to achieve Seamless Roaming through an extension of Fast Transition (FT). FT is a feature already present in the IEEE 802.11 standard, and by simplifying EAP (Extensible Authentication Protocol) and 4-way handshake, AP switching can be achieved in about 5-10 ms in the best case. However, this cannot be achieved in most cases, and data loss occurs (see IEEE 802.11-23 / 2157r2, Nov. 27, 2023). It should be noted that this method also assumes the use of MLD (Multi-Level Delay).

[0022] Furthermore, in order to ensure data continuity, context information such as Block Ack information and Capability information must be shared between the AP at the destination after AP switching and the AP at the source of the connection before AP switching. An example from a previous paper (IEEE 802.11-24 / 52r0, Jan.12, 2024) proposes AP switching methods that utilize MLD and share context information.

[0023] (1-2. Communication Systems) Here, we will explain the communication system envisioned in this disclosure using Figure 1. Figure 1 is a diagram showing an example of a communication system related to this disclosure. The communication system shown in Figure 1 includes a plurality of AP100s (in Figure 1, the first AP100A and the second AP100B), a plurality of STA200s (in Figure 1, the first to third STA200A to 200C), and a controller 300.

[0024] In the example in Figure 1, the first STA200A is a Head Mounted Display (HMD). Also in the example in Figure 1, the second STA200B is a smartphone. Also in the example in Figure 1, the third STA200C is an HMD.

[0025] HMDs are used, for example, to provide virtual reality (VR) services. Therefore, HMDs require low latency, high reliability, and high throughput in DL communication, as well as low latency and high reliability in UL communication.

[0026] In the example shown in Figure 1, the first STA200A is located within the communication range of the first AP100A and the second AP100B. For example, let's assume that the first STA200A is communicating with the second AP100B. In this case, the first STA200A switches the AP it connects to from the second AP100B to the first AP100A.

[0027] In the example shown in Figure 1, the second STA200B is located within the communication range of the first AP100A and communicates with the first AP100A. Also in the example shown in Figure 1, the third STA200C is located within the communication range of the second AP100B and communicates with the second AP100B.

[0028] Note that the first STA200A, which switches AP100, is not limited to HMDs. The first STA200A can be any device that requires low latency, such as an Industrial IoT (Internet of Things) device.

[0029] Furthermore, although Figure 1 shows an example where there are two AP100s, the number of AP100s is not limited to this. There may be three or more AP100s. Similarly, the number of STA200s is not limited to three. There may be two or fewer STA200s, or four or more. Moreover, the control device 300 may be part of the AP100. In other words, the AP100 may have the functions of the control device 300.

[0030] Furthermore, backhaul communication between AP100s, and between AP100s and the control unit 300, may be either wired or wireless. Also, AP100 and STA200 are MLDs. In current standardization, STAs that wish to perform AP switching are required to maintain State 4 (Authenticated / Associated / IEEE802.1X Controlled Port Unblocked) while performing AP switching.

[0031] (1-3. Overview of the Embodiment) In the above communication system, when an STA200 moves, it connects to an AP100 with a good channel condition, or when there are many STA200s connected to AP100, it switches AP100. For example, an STA200 that wants to perform an AP switch (hereinafter sometimes referred to as Roaming STA) disconnects (Disassociates) from the first AP100 (hereinafter sometimes referred to as Source AP) to which it was connected, and then connects (Associates) to the new destination, the second AP100 (hereinafter sometimes referred to as Target AP). In this way, the Roaming STA performs the AP switch. However, in this case, because there are many frames that need to be exchanged, the time until the AP switch is completed becomes long, and data loss occurs.

[0032] The following explanation will cover the cases using Single Link and Dual Link separately. Here, Single Link refers to the case where, for example, Roaming STA can only connect to one AP at any given time. Dual Link refers to the case where, for example, Roaming STA is temporarily connected to two APs. Note that the control device 300 may be referred to as "Controller" below.

[0033] First, let's explain the case where a Single Link is used. In the method using a Single Link, before the link switchover, the Source AP transmits all DL traffic buffered at the Source AP to the Roaming STA before Data Path Switching is performed. After that, the Source AP disables the link with the Roaming STA. Then, the Roaming STA enables the link with the new Target AP. Therefore, from the time Data Path Switching is performed until the link with the Target AP is enabled, traffic buffered at the Target AP cannot be transmitted. This increases the latency of DL traffic. Also, there is a period during which UL traffic cannot be transmitted, and the transmission latency of UL traffic also increases.

[0034] Figure 2 illustrates a specific example of AP switching when using Single Link. Figure 2 shows an example of AP switching processing using Single Link. In Figure 2, we assume an environment where multiple AP100s exist, and STA200, which requires low-latency transmission of UL traffic (an example of data) such as VR and Industrial IoT devices, performs AP switching.

[0035] In the example in Figure 2, the Roaming STA makes a decision to perform AP switching at time t1. For example, in the case of STA-initiated roaming, the Roaming STA sends a switching request signal (corresponding to the Roaming Request in Figure 2) to the Source AP requesting it to switch APs. In the example in Figure 2, the Roaming STA sends the switching request signal to the Source AP at time t3. Note that this 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, AP switching begins. In the example in Figure 2, the Source AP receives the switching request signal from the Roaming STA. Subsequently, if the Source AP determines that it has correctly received the switching request signal, AP switching begins. Next, the Source AP sends a switching request signal to the Controller, and the Controller sends Context information to the Target AP. Note that this switching request signal is an example of a second switching request signal. Also, at the Target AP, a Link is added at time t2, but the Link status remains Disabled until time t5.

[0037] During AP switching, UL traffic may not be properly transmitted to the upper layer, so UL communication is blocked. Also, if a UL is sent to the Source AP during the UL communication blockage period, the shared Context between the Source AP and Target AP changes, so UL communication is blocked. In the example in Figure 2, the period during which UL communication is blocked corresponds to UL Suspension. Note that below, the period during which UL is blocked may be referred to as the UL communication blockage period.

[0038] Then, after the Source AP has finished preparing for AP switching between the Source AP and the Target AP (Context Transfer / Data Path Switching), the Source AP receives a switching response signal (corresponding to the Roaming Response in Figure 2) from the Controller in response to switching AP100, and subsequently sends the switching response signal to the Roaming STA. In the example in Figure 2, the Source AP sends the switching response signal to the Roaming STA at time t4. This allows the Roaming STA to resume UL communication.

[0039] As described above, if low-latency traffic occurs in the Roaming STA during or before the UL communication outage period, and if this low-latency traffic is held during the UL communication outage period, such low-latency traffic cannot be transmitted until the AP switchover is complete. Therefore, delay requirements may not be met, and data continuity may not be guaranteed.

[0040] In the example in Figure 2, the Roaming STA sends a switching request signal to the Source AP, but the Roaming STA may also send the switching request signal to the Target AP. Also, in the example in Figure 2, the Roaming STA sends the switching request signal, but in AP-Initiated Roaming, AP100 (for example, the Source AP or Target AP) may send the switching request signal. Furthermore, in the example in Figure 2, the Source AP may send a response to the switching request signal to the Roaming STA.

[0041] Next, let's discuss the case where Dual Link is used. In the Dual Link method, after Data Path Switching during AP switching, the Roaming STA enables a separate link between itself and the Target AP, different from the Source AP. The Source AP can also send data that was buffered to the Source AP before Data Path Switching. The Target AP can also send data that will be newly buffered to the Target AP after Data Path Switching. This reduces DL latency. After all the buffered traffic to the Source AP has been transmitted, the Roaming STA disables the link with the Source AP. Even when using Dual Link, there is a period during which UL traffic cannot be transmitted, just as with Single Link.

[0042] Figure 3 illustrates a specific example of AP switching when using Dual Link. Figure 3 shows an example of AP switching processing using Dual Link. In Figure 3, we assume an environment where multiple AP100s and STA200s exist, and the STA200, which requires low-latency transmission of UL traffic, performs AP switching.

[0043] In the example in Figure 3, the STA200 that requires low-latency transmission for UL traffic is the Roaming STA. Another STA200, different from the Roaming STA, is the Other Roaming STA. In the example in Figure 3, it is assumed that the Other Roaming STA has already performed AP switching. In this case, the Roaming STA will perform AP switching.

[0044] In the case of STA-initiated roaming, the Roaming STA sends a switching request signal to the Source AP requesting it to switch APs. In the example in Figure 3, the Roaming STA sends the switching request signal to the Source AP at time t11. Subsequently, if the Source AP correctly receives the switching request signal from the Roaming STA, AP switching begins. In the example in Figure 3, the Source AP receives the switching request signal from the Roaming STA. If the Source AP determines that it has correctly received the switching request signal, AP switching begins. Subsequently, UL traffic is generated in the Roaming STA at time t12. Then, UL traffic is generated in the Other Roaming STA at time t13.

[0045] Next, at time t14, the Source AP sends a switching response signal to the Other Roaming STA. Then, after the Source AP and Target AP have finished preparing for AP switching, the Source AP sends a switching response signal to the Roaming STA in response to switching the AP. In the example in Figure 3, the Source AP sends the switching response signal to the Roaming STA at time t15.

[0046] In this case, the Other Roaming STA resumes UL communication at time t16, preventing the Roaming STA from transmitting UL communication. In other words, the Roaming STA cannot transmit the UL traffic that occurred at time t12 to the Target AP. Therefore, the Roaming STA cannot satisfy the delay request.

[0047] As described above, when multiple STA200s initiate AP switching simultaneously, channel contention may occur among the multiple STA200s before and after the STA200 that requires low latency for the UL receives the switching response signal. In this case, collisions may occur between multiple STA200s, or interrupts on transmission may occur due to other STA200s that do not require low latency. As a result, the Roaming STA may not be able to transmit UL traffic with low latency. Furthermore, data continuity may not be guaranteed.

[0048] Therefore, in response to one example of the above-mentioned problems, this disclosure proposes a communication device that, for example, transmits a switching response signal to the Roaming STA, along with a switching response signal that responds to switching from the Source AP to the Target AP based on a switching request signal, and a trigger signal for the Roaming STA to transmit data. This allows this disclosure to ensure data continuity.

[0049] (2. Example of a communication system configuration) (2-1. Example of AP configuration) Figure 4 is a block diagram showing an example configuration of AP100 (an example of a communication device) according to the present disclosure. AP100 comprises a wireless communication unit 110, a backhaul communication unit 120, a storage unit 130, and a control unit 140.

[0050] (Wireless communication section 110) The wireless communication unit 110 is a communication unit that performs wireless communication with other wireless communication devices (for example, STA200). The wireless communication unit 110 communicates with STA200 according to a wireless LAN (Local Area Network) standard, such as Wi-Fi.

[0051] The wireless communication unit 110 includes a common MAC (Media Access Control) processing unit 111, individual MAC processing units 112A and 112B, signal processing units 113A and 113B, RF (Radio Frequency) 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 shown in Figure 4 is an example and is not limited thereto. The wireless communication unit 110 may include all or some of the following: 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 will be collectively referred to as the first processing unit 117A. Similarly, the individual MAC processing unit 112B, the signal processing unit 113B, the RF unit 114B, and the RF switch 115B will be collectively referred to as the second processing unit 117B. Furthermore, when the first processing unit 117A and the second processing unit 117B are not distinguished, they will simply be referred to as processing unit 117. In addition, processing unit 117 may include all of the individual MAC processing unit 112, the signal processing unit 113, the RF unit 114, and the RF switch 115, or it may include some of them.

[0054] As shown above, the AP100 in Figure 4 has two processing units 117. In other words, the AP100 is an MLD that can be connected by two different links. Here, we have assumed that the AP100 can be connected to two links, but the AP100 may be able to be connected to three or more links. In this case, the AP100 will have as many processing units 117 as there are links it can be connected to.

[0055] Note that the operation of the first processing unit 117A and the second processing unit 117B are the same. Therefore, the first processing unit 117A will be explained here, and the explanation of the second processing unit 117B will be omitted.

[0056] (Common MAC Processing Unit 111) The common MAC processing unit 111 performs processing on the data. For example, the common MAC processing unit 111 performs at least part of the MAC processing for media access control (MAC).

[0057] The common MAC processing unit 111 performs sequence management of data and control and management information received from the communication control unit 116 during transmission, and generates data units by performing encryption processing, etc. Upon reception, the common MAC processing unit 111 performs decryption processing and then performs retransmission request operations and reorder processing.

[0058] This process is also collectively referred to as common data processing (Upper MAC (U-MAC) processing). Note that the control device 300 may execute at least a part of the common data processing. If the control device 300 always executes common data processing, the common MAC processing unit 111 (the processing unit that performs common data processing) may be omitted.

[0059] (Individual MAC processing unit 112A) The individual MAC processing unit 112A performs at least a portion of the MAC processing for media access control. The individual MAC processing unit 112A executes the MAC processing excluding the processing performed by the common MAC processing unit 111.

[0060] The individual MAC processing unit 112A receives encrypted data (e.g., data units) with sequence numbers added from the common MAC processing unit 111, and performs the following processing (individual data processing described later) on the received data.

[0061] The individual MAC processing unit 112A generates a MAC frame by adding a MAC header and error detection codes to an encrypted packet during transmission. The individual MAC processing unit 112A also performs concatenation of multiple MAC frames. Upon reception, the individual MAC processing unit 112A performs deconcatenation of the MAC header of the received MAC frame, error detection, and retransmission request operations. Furthermore, the individual MAC processing unit 112A performs channel access operations based on carrier sense.

[0062] These processes are collectively referred to as individual data processing (Lower MAC (L-MAC) processing). Even if the control device 300 performs at least a part of the common data processing, the individual data processing is performed by the individual MAC processing unit 112A, i.e., AP100.

[0063] Furthermore, as shown in Figure 4, if AP100 is an MLD, that is, if AP100 is connected to multiple links, the common MAC processing unit 111 and the individual MAC processing unit 112A can be configured as separate processing units.

[0064] (Signal processing unit 113A) The signal processing unit 113A performs processing at the physical layer (PHY). During transmission, the signal processing unit 113A performs encoding, interleaving, and modulation, adds a physical header, and generates a symbol stream.

[0065] The signal processing unit 113A analyzes the physical header upon reception, performs demodulation, deinterleaving, and decoding of the symbol stream, and generates a MAC frame. The signal processing unit 113A also performs complex channel characteristic estimation and spatial separation processing as needed.

[0066] (RF section 114A) The RF section 114A includes a transmitting RF section (Tx RF) and a receiving RF section (Rx RF), although these are not shown. The transmitting RF section generates a transmit signal by performing digital-to-analog signal conversion, filtering, upconversion using a local oscillator (not shown), and phase control on the symbol stream.

[0067] The receiving RF section performs down-conversion, filtering, and analog-to-digital signal conversion on the received signal using a local oscillator (not shown) to generate a symbol stream.

[0068] (RF switch 115A) The RF switch 115A switches between transmitting and receiving. For example, the RF switch 115A switches the RF section of the transmitting RF section and the RF section of the receiving RF section that is connected to antennas 118A_1 and 118A_2.

[0069] In Figure 4, there are two antennas, 118A_1 and 118A_2, connected to the RF switch 115A, but the number of antennas is not limited to two. The number of antennas connected to the RF switch 115A can be one or three or more.

[0070] (Communication control unit 116) The communication control unit 116 controls the operation of each part of the wireless communication unit 110 and the transmission of information between each part. The communication control unit 116 also controls the transfer of control information and management information to be notified to the STA200 to the common MAC processing unit 111.

[0071] The function that performs the common data processing described above (common MAC processing unit 111) will also be referred to as "AP MLD Entity". Furthermore, the functions that perform individual data processing, as well as the functions that amplify signals (individual MAC processing unit 112A, signal processing unit 113A, and RF unit 114A) will also be referred to as "AP Entity (APx)". AP100 may have multiple AP Entities belonging to the AP MLD Entity.

[0072] For example, if AP100 functions as a Roaming AP MLD Entity, AP100 will perform common data processing for other AP100s within the AP MLD Entity. In other words, an AP MLD Entity can function as a Roaming AP MLD Entity.

[0073] Here, the Roaming AP MLD Entity uniformly manages the connection relationships between the AP100 and STA200 to which it belongs. Therefore, when AP100s belonging to the Roaming AP MLD Entity (for example, AP100A and AP100B) perform a handover (AP switching), they can omit the reconnection / re-authentication process with STA200A.

[0074] Furthermore, although Figure 4 shows the wireless communication unit 110 as being implemented in AP100 as a single IC (Integrated Circuit), the configuration of the wireless communication unit 110 is not limited to this. For example, the wireless communication unit 110 may be composed of multiple ICs or individual components. For instance, the RF unit 114A, the RF switch 115A, and the antennas 118A_1 and 118A_2 may be implemented in AP100 as separate ICs or individual components from the other components of the wireless communication unit 110.

[0075] (Backhaul communication unit 120) The backhaul communication unit 120 is a communication unit that communicates with other AP100s, routers (not shown), and control devices 300. The backhaul communication unit 120 handles communication between the backhaul network and the fronthaul network (the network between AP100 and STA200).

[0076] The backhaul communication unit 120 can communicate with other AP100s, routers, and control devices 300 via wired connections using optical fiber or Ethernet® cables. Alternatively, the backhaul communication unit 120 may communicate wirelessly with these devices.

[0077] The backhaul communication unit 120 decodes packets acquired via the backhaul link and outputs them to the wireless communication unit 110 via the control unit 140. The packets output to the wireless communication unit 110 may be packets with the IP header intact (access point mode), or packets with the IP header decoded and removed by the backhaul communication unit 120 (router mode). In this embodiment, AP100 performs information exchange (communication with other AP100s) via the backhaul communication unit 120.

[0078] The control link (the link between the control device 300 and other AP100s) may be formed using the wireless communication unit 110 or using the backhaul communication unit 120.

[0079] (Storage unit 130) The memory unit 130 is a data read / write storage device such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), flash memory, or hard disk. The memory unit 130 holds information used by the control unit 140 and the wireless communication unit 110.

[0080] The memory unit 130 performs tasks such as queuing signals from higher layers and buffering received signals. The memory unit 130 also holds data for the signal processing unit 113A during synthesis processing.

[0081] (Control unit 140) The control unit 140 is a controller that controls various parts of the AP100. The control unit 140 may perform some of the operations of the communication control unit 116. The communication control unit 116 and the control unit 140 may be configured as a single block.

[0082] The control unit 140 may be configured in any way included in AP100. Alternatively, the control unit 140 may be located inside a different device (for example, a control device 300) from AP100.

[0083] The control unit 140 may be implemented by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit).

[0084] More specifically, the control unit 140 may be implemented by the processor executing various programs stored in the internal storage device of the AP100 using RAM (Random Access Memory) or the like as a working area.

[0085] The control unit 140 may be implemented by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). Alternatively, the control unit 140 may be implemented by a GPU (Graphics Processing Unit).

[0086] A CPU, MPU, ASIC, FPGA, and GPU can all be considered controllers. The control unit 140 may be composed of multiple physically separate objects. For example, the control unit 140 may be composed of multiple semiconductor chips.

[0087] (2-2. Example of STA configuration) Figure 5 is a block diagram showing an example configuration of STA200 (an example of a terminal device) according to the present disclosure. STA200 comprises a wireless communication unit 210, a storage unit 220, and a control unit 230.

[0088] (Radio communication section 210) The wireless communication unit 210 is a communication unit that performs wireless communication with other wireless communication devices (for example, AP100). The wireless communication unit 210 communicates with AP100 according to a wireless LAN (Local Area Network) 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, RF (Radio Frequency) 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 shown in Figure 5 is an example and is not limited thereto. The wireless communication unit 210 may include all or some of the following: 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 will be collectively referred to as the first processing unit 217A. Similarly, the individual MAC processing unit 212B, the signal processing unit 213B, the RF unit 214B, and the RF switch 215B will be collectively referred to as the second processing unit 217B. Furthermore, when the first processing unit 217A and the second processing unit 217B are not distinguished, they will simply be referred to as processing unit 217. In addition, processing unit 217 may include all or some of the individual MAC processing unit 212, the signal processing unit 213, the RF unit 214, and the RF switch 215.

[0092] Thus, the STA200 in Figure 5 is equipped with two processing units 217. In other words, the STA200 is an MLD that can be connected by two different links.

[0093] In this example, it is assumed that the STA200 can connect to two links, but the STA200 may connect to three or more links. In this case, the STA200 will have a number of links to which the processing unit 217 can be connected.

[0094] Here, the operation of the first processing unit 217A and the second processing unit 217B is the same. Therefore, the first processing unit 217A will be explained here, and the explanation of the second processing unit 217B will be omitted.

[0095] (Common MAC Processing Unit 211) The common MAC processing unit 211 performs processing on the data. For example, the common MAC processing unit 211 performs at least part of the MAC processing for media access control (MAC).

[0096] The common MAC processing unit 211 performs common data processing (U-MAC processing) similar to the common MAC processing unit 111 of AP100. For example, the common MAC processing unit 211 performs 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 performs at least a portion of the MAC processing for media access control. The individual MAC processing unit 212A executes the MAC processing excluding the processing performed by the common MAC processing unit 211. The individual MAC processing unit 212A performs individual data processing (L-MAC processing) in the same way as the individual MAC processing unit 112A of AP100.

[0098] Furthermore, as shown in Figure 5, if STA200 is an MLD, that is, if STA200 is connected to multiple 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 STA200 connects to a single link, the wireless communication unit 210 may be configured to include a single processing unit (e.g., a MAC processing unit) that combines the common MAC processing unit 211 and the individual MAC processing units 212A.

[0100] (Signal processing unit 213A) The signal processing unit 213A performs processing at the physical layer (PHY). During transmission, the signal processing unit 213A performs encoding, interleaving, and modulation, adds a physical header, and generates a symbol stream.

[0101] The signal processing unit 213A analyzes the physical header upon reception, performs demodulation, deinterleaving, and decoding of the symbol stream, and generates a MAC frame. The signal processing unit 213A also performs complex channel characteristic estimation and spatial separation processing as needed.

[0102] (RF section 214A) The RF section 214A includes a transmitting RF section (Tx RF) and a receiving RF section (Rx RF), although these are not shown. The transmitting RF section generates a transmit signal by performing digital-to-analog signal conversion, filtering, upconversion using a local oscillator (not shown), and phase control on the symbol stream.

[0103] The receiving RF section performs down-conversion, filtering, and analog-to-digital signal conversion on the received signal using a local oscillator (not shown) to generate a symbol stream.

[0104] (RF switch 215A) The RF switch 215A switches between transmitting and receiving. For example, the RF switch 215A switches the RF section of the transmitting RF section and the RF section of the receiving RF section that is connected to antennas 218A_1 and 218A_2.

[0105] In Figure 5, there are two antennas, 218A_1 and 218A_2, connected to the RF switch 215A, but the number of antennas is not limited to two. The number of antennas connected to the RF switch 215A can be one or three or more.

[0106] (Communication control unit 216) The communication control unit 216 controls the operation of each part of the wireless communication unit 210 and the transmission of information between each part. The communication control unit 216 also controls the transfer of control information and management information to be notified to the AP100 to the common MAC processing unit 211.

[0107] Furthermore, although Figure 5 shows the wireless communication unit 210 as being implemented in the STA200 as a single IC (Integrated Circuit), the configuration of the wireless communication unit 210 is not limited to this. For example, the wireless communication unit 210 may be composed of multiple ICs or individual components. For instance, the RF unit 214A, the RF switch 215A, and the antennas 218A_1 and 218A_2 may be implemented in the STA200 as separate ICs or individual components from the other components of the wireless communication unit 210.

[0108] (Storage unit 220) The memory unit 220 is a data read / write storage device such as DRAM, SRAM, flash memory, or hard disk. The memory 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 various parts of the STA200. The control unit 230 may perform some of the operations of the communication control unit 216. The communication control unit 216 and the control unit 230 may be configured as a single block. The control unit 230 may also be one of the configurations included in the STA200.

[0110] The control unit 230 may be implemented by a processor such as a CPU or MPU. More specifically, the control unit 230 may be implemented by the processor executing various programs stored in the internal storage device of the STA200 using RAM or the like as a working area.

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

[0112] A CPU, MPU, ASIC, FPGA, and GPU can all be considered controllers. The control unit 230 may be composed of multiple physically separate objects. For example, the control unit 230 may be composed of multiple semiconductor chips.

[0113] (3. Examples of communication system processing) Next, an example of processing performed in the communication system according to this embodiment will be described. Below, several embodiments of this embodiment will be described in which, after UL communication resumes due to AP switching completion, buffered traffic to the STA200, which is required to provide low-latency transmission for UL traffic, is transmitted with low latency.

[0114] (3-1. First Embodiment) (3-1-1. Processing according to the first embodiment) First, as a first embodiment, we will describe an example in which a trigger signal is sent to a Roaming STA having UL traffic requiring low-latency transmission, along with a switching response signal, for transmitting data.

[0115] Figure 6 shows an example of AP switching processing using a trigger signal according to the first embodiment. In the example in Figure 6, it is assumed that the Target AP sends a switching response signal to the Roaming STA.

[0116] In the example in Figure 6, the Roaming STA makes a decision to perform AP switching at time t21. For example, in the case of STA-initiated roaming, the Roaming STA sends a switching request signal to the Source AP requesting it to switch APs. In the example in Figure 6, the Roaming STA sends the switching request signal to the Source AP at time t22. Then, if the Source AP correctly receives the switching request signal from the Roaming STA, AP switching begins. In the example in Figure 6, the Source AP receives the switching request signal from the Roaming STA. Subsequently, if the Source AP determines that it has correctly received the switching request signal, AP switching begins.

[0117] Then, UL traffic occurs at Roaming STA at time t23. Subsequently, Roaming STA sends notification information to Target AP at time t24. This notification information will be described in detail in section 3-1-3. Information Exchange below.

[0118] Then, at time t25, the Target AP sends a trigger signal to the Roaming STA along with a switching response signal. In this way, the Target AP triggers UL communication to the STA200, which has low-latency UL traffic, at the same time as sending the switching response signal.

[0119] This allows the Roaming STA to transmit UL communication after time t26. In the example in Figure 6, the Roaming STA transmits UL traffic at time t27. In this way, the Roaming STA can transmit UL traffic requiring low latency without the Target AP terminating the Transmission Opportunity (TXOP) immediately after sending the switching response signal. Furthermore, since the UL traffic is transmitted from the Roaming STA as a response to the switching response signal, the Target AP can determine whether or not the switching response signal was transmitted correctly.

[0120] Note that while Figure 6 illustrates an example where the Roaming STA sends a switching request signal to the Source AP, the explanation is not limited to this. For example, the Roaming STA may also send a switching request signal to the Target AP.

[0121] Furthermore, in the first embodiment described above, a capability check may be performed to indicate that the system supports the functions described in this disclosure. Capability information may be notified, for example, by a Beacon frame containing a Capability element used for each version of the standard, a Probe Request frame, a Probe Response frame, etc.

[0122] Furthermore, although the first embodiment described above included an example in which the Target AP transmits a trigger signal along with a switching response signal to the Roaming STA, the system is not limited to this. For example, the Target AP may transmit a switching response signal including a trigger signal to the Roaming STA. Alternatively, the Target AP may use a TXOP to transmit the switching response signal and the trigger signal separately within the same TXOP.

[0123] In order to perform the operations according to the first embodiment described above, the following prior negotiations and notification actions are necessary: ​​(1) Restrict the transmittable frames, excluding QoS Data frames, during the UL communication blockage period, and enable UL communication. (2) Exchange information between the Target AP, Source AP, and Roaming STA. (3) Decide on and notify the actions to be taken after the AP switchover is completed.

[0124] (3-1-2. Limitations on the number of frames that can be transmitted) (Regarding a method to enable UL communication by limiting the frames that can be transmitted during the UL communication blockage period) In performing the operation according to the first embodiment described above, if UL traffic requiring low-latency transmission occurs at the Roaming STA during the UL communication interruption period, it is necessary to notify the Target AP of information regarding the operation. This notification enables the operation to perform low-latency UL transmission after the AP switchover is completed.

[0125] Therefore, during the UL communication blockage period, the Target AP is negotiated in advance regarding the frames that can be transmitted and the information that can be notified, thereby enabling UL communication. For example, Non-Patent Literature 2 describes that Multi-Link setup is performed before sending the switching request signal, and that the newly added link is disabled. In IEEE 802.11be, signals for individual addresses on disabled links, including control frames and management frames, cannot be transmitted. Therefore, it is desirable to transmit a minimum number of frames during the UL communication blockage period.

[0126] For example, methods for limiting the number of frames that can be transmitted during a UL communication interruption period, and for setting the link status of Roaming STA during a UL communication interruption period, include using a Multi-Link setup frame or a Roaming Request frame.

[0127] The following describes an example of a method for enabling UL communication by limiting the frames that can be transmitted during the UL communication interruption period. Figure 7 shows an example of AP switching processing when using the transmittable frames according to the first embodiment. In the example in Figure 7, it is assumed that the Target AP transmits a switching response signal to the Roaming STA.

[0128] In the example in Figure 7, the link state in region RC31 is defined so that the desired frame can be transmitted. In region RC32, a multi-link setup is performed. In the example in Figure 7, the roaming STA transmits a multi-link setup frame at time t31. Note that at the Target AP, a link is added at time t31, but the link state remains disabled until time t36.

[0129] Furthermore, the Roaming STA sends a switching request signal to the Source AP. In the example in Figure 7, in the case of STA-initiated roaming, the Roaming STA sends a switching request signal to the Source AP at time t32.

[0130] Next, the Source AP initiates AP switching when it correctly receives a switching request signal from the Roaming STA. In the example in Figure 7, the Source AP receives a switching request signal from the Roaming STA. Then, if the Source AP determines that it has correctly received the switching request signal, AP switching is initiated.

[0131] Next, Roaming STA will generate UL traffic at time t33. Then, Roaming STA will send notification information to Target AP at time t34. Subsequently, Source AP will send a switching response signal at time t35. This notification information will be described in detail in section 3-1-3. Information Exchange below.

[0132] In addition to negotiating the frames that can be transmitted during the UL communication blockage period, the Target AP may also send a request signal for a switching response signal. Furthermore, the frames used to restrict the frames that can be transmitted during the UL communication blockage period and enable UL communication may be other frames related to AP switching that are sent before the switching request signal. For example, these other frames include FT Requests and FT Probe Requests. Although not shown in Figure 7, response signals may also be sent for each signal, such as the switching request signal.

[0133] (Regarding encryption keys) Furthermore, when transmitting UL traffic during a UL communication blockage period, it is necessary to consider whether the Roaming STA and the Target AP possess encryption keys. For example, the types of frames that can be transmitted will change depending on whether or not an encryption key is present. Also, the information that can be advertised may change depending on whether or not an encryption key is present.

[0134] While some proposals have been made to apply encryption protection to certain control frames and MAC headers, we will also consider communication methods that can be performed without encryption, other than those involving control frames and MAC headers.

[0135] For example, IEEE 802.11be shows an example of a transmittable frame during a UL communication blockage period depending on the encryption key possession status. If the Roaming STA does not possess the encryption key for the Target AP, transmittable frames include Control frames, Public Action frames, and QoS Null frames. If the Roaming STA possesses the encryption key for the Target AP, transmittable frames include encrypted (Management) frames.

[0136] The encryption keys include PTKs for transmitting individual address signals between the Target AP and the Roaming STA, and Roaming Signal Keys specifically for AP switching, as described in Non-Patent Document 3. Non-Patent Document 3 proposes that the PTK is not shared between the Target AP and the Source AP, but is newly generated. Non-Patent Document 4 proposes that the PTK is shared between the Target AP and the Source AP.

[0137] (Regarding frame formatting) Next, the format of the transmittable frame will be explained using Figure 8. Figure 8 is a diagram showing an example of the frame configuration of a switching request signal according to the first embodiment. The example in Figure 8 is an example of a format for setting the frames that can be transmitted during the UL communication interruption period in the switching request signal. The Target AP is requested to send a switching request signal using the Roaming Response From Target AP Request Flag.

[0138] The upper part of Figure 8 shows an example of the MAC frame format in IEEE 802.11. The lower part of Figure 8 shows the Frame Body of the MAC frame. In the example in Figure 8, the Frame Body of the MAC frame includes Roaming Response From Target AP Request, PTK Request, Permitted Frame type during UL Suspension Request, Reserved, etc. Roaming Response From Target AP Request is 1 bit. PTK Request is 1 bit. Permitted Frame type during UL Suspension Request is 3 bits. Reserved is 4 bits.

[0139] Requests for frames that can be transmitted during a UL (Ultra Lift) communication interruption period are made using the "Permitted Frame Type during UL Suspension Request" form. The frame type is specified by the information included in this form. Table 1 below shows the correspondence between the information included in the "Permitted Frame Type during UL Suspension Request" and the frame type.

[0140] [Table 1]

[0141] Table 1 shows that when the Permitted Frame type during UL Suspension Request is "00", the Subsequent Content is "Public Action". Also, when the Permitted Frame type during UL Suspension Request is "01", the Subsequent Content is "QoS Null".

[0142] Furthermore, if the Permitted Frame type during UL Suspension Request is "10", the Subsequent Content is "Protected Individually Addressed Management Frame". If the Permitted Frame type during UL Suspension Request is "11", the Subsequent Content is "Protected Signal by Roaming Signal Key". In this way, the appropriate frame type can be specified depending on the information to be included in the Permitted Frame type during UL Suspension Request.

[0143] Furthermore, if a PTK is newly generated or shared between the Source AP and Target AP during the UL communication blockage period, a request to immediately notify the Roaming STA can also be made using the above Flag.

[0144] Note that while the example in Figure 8 describes only one type of transmittable frame, this is not limited to that. For example, there may be any number of transmittable frame types. Furthermore, the required frame may change depending on the cryptographic key holding status at the time of the switching request signal. In addition, the information that can be notified during the UL communication blockage period may be restricted depending on the cryptographic key holding status.

[0145] Furthermore, using the response signal to the switching response signal, the Source AP or Target AP may send a response signal by referring to the request signal sent by the Roaming STA shown in Figure 8. In addition, rules regarding the frames and information that can be sent between the Source AP and the Target AP depending on the state of cryptographic key possession during the UL communication blockage period may be predetermined.

[0146] (3-1-3. Information Exchange) (Information exchange between Target AP, Source AP, and Roaming STA) Furthermore, in order to perform the operation according to the first embodiment described above, it is necessary to notify the Target AP of the Roaming STA status during the UL communication blockage period. The notification information regarding the traffic to be notified may include the following: 1. Traffic volume 2. Notification that low-latency traffic is being buffered (Buffer Status) 3. TID / AC 4. Request for trigger signal to be transmitted along with the switching response signal. 5. Request to set priority transmission period 6. Delay Budget 7. DL Suspension 8. Target AP sends a switching response signal in response to a request.

[0147] This allows the Roaming STA to notify not only the traffic information it possesses, but also other request information, such as requests for low-latency transmission methods for low-latency traffic after the UL communication blockage period, and requests for the Target AP to send a switching response signal. Only switching request signals, frames pre-authorized by Multi-Link Setup, etc., and transmittable information can be transmitted during the UL communication blockage period. The number of transmittable bits in transmittable frames may change. Furthermore, detailed information among the above notification information may be transmitted encrypted.

[0148] The following describes an example of the processing performed by the communication system during information exchange between the Target AP, Source AP, and Roaming STA. Figure 9 is a diagram showing an example of AP switching processing using notification information according to the first embodiment. In the example in Figure 9, it is assumed that the Source AP sends a switching response signal to the Roaming STA.

[0149] In the example in Figure 9, information exchange takes place in region RC41 during the UL communication interruption period. For example, in the case of STA-initiated roaming, the Roaming STA sends a switching request signal to the Source AP. In the example in Figure 9, the Roaming STA sends the switching request signal to the Source AP at time t41.

[0150] Next, the Source AP initiates AP switching when it correctly receives a switching request signal from the Roaming STA. In the example in Figure 9, the Source AP receives a switching request signal from the Roaming STA. Then, if the Source AP determines that it has correctly received the switching request signal, AP switching is initiated.

[0151] Next, assume that UL traffic occurs at time t42 on the Roaming STA. Then, at time t43, the Roaming STA sends notification information to the Target AP. Subsequently, at time t44, the Target AP sends a response signal to the Roaming STA indicating that it has received the notification information. Then, at time t45, the Source AP sends a switching response signal. In the example in Figure 9, the UL communication interruption period is from time t41 to time t46.

[0152] (Regarding the frame format when encryption is not used) Next, the frame format without encryption will be explained using Figure 10. Figure 10 is a diagram showing an example of the A-Control field format according to the first embodiment. The upper part of Figure 10 shows an example of the MAC frame format in IEEE 802.11. The middle part of Figure 10 shows the HT Control field of the MAC frame. The HT Control field includes the Control ID and Control Information. The lower part of Figure 10 shows the Control Information.

[0153] In the example in Figure 10, the Control Information includes AC, Queue Size, Roaming Response from Target AP Request, Trigger Request When Roaming Response, Source AP Address, Reserved, etc. AC is 2 bits. Queue Size is 8 bits. Roaming Response from Target AP Request is 1 bit. Trigger Request When Roaming Response is 1 bit. Source AP Address is 12 bits. Reserved is 2 bits.

[0154] The A-Control field is available when both the first and second bits of the HT Control field in the MAC frame are 1. The Control Information in the A-Control field has 26 bits. Control IDs 10-14 are reserved. Therefore, a new format can be defined for Control IDs 10-14. For example, in addition to traffic information such as AC and queue size, it is possible to include a transmission request signal for the trigger signal, which is sent along with the switching response signal, in the Control Information.

[0155] Furthermore, if you want to share the frame information sent to the Target AP with the Source AP via the Distribution System (DS) (Over-The-DS), you can include the Source AP's address in the Control Information. However, in this case, due to bit limitations, the number of bits in the AP Address used in the FT Request must be reduced.

[0156] Furthermore, when using a Public Action frame, the Frame Body can be utilized, allowing for the use of various information such as the Delay Budget. Also, in the example in Figure 10, buffer information is included in the HT Control field, but buffer information may also be notified using the QoS Control field.

[0157] Furthermore, when transmitting information without encryption, the information that can be transmitted may be restricted for security reasons. Also, a Source AP can transmit information to a Target AP via a DS. In this case, the Target AP's address, not the Source AP's address, is stored.

[0158] (Regarding the frame format when encryption is enabled) Next, we will explain the frame format when encryption is enabled using Figure 11. Figure 11 is a diagram showing an example of the format when using the Element according to the first embodiment.

[0159] The upper part of Figure 11 shows an example of the Element format in IEEE 802.11. As shown in the upper part of Figure 11, the Element Information is identified by a combination of Element ID and Element ID Extension. The lower part of Figure 11 shows the Element Information.

[0160] In the example in Figure 11, the Information field includes AC, Queue Size, Delay Bound, Source AP Address, Roaming Response from Target AP Request, Trigger Request When Roaming Response, PTK Request, etc. AC is 2 bits. Queue Size is 8 bits. Delay Bound is 24 bits. Source AP Address is 48 bits. Roaming Response from Target AP Request is 1 bit. Trigger Request When Roaming Response is 1 bit. PTK Request is 1 bit.

[0161] For example, a new Element ID may be assigned to identify the Information element. By defining a new Element ID in this way, a new format can be defined. Furthermore, formats using Elements utilize, for example, encrypted Management frames, offering higher security compared to unencrypted communication. Additionally, formats using Elements allow for the use of Frame Bodies, enabling the transmission of a larger amount of information.

[0162] In the example shown in Figure 11, the format using Element notifies the Target AP of the AC, the size information of the traffic buffered by that AC, and the Delay Bound information. Furthermore, since information is shared with the Source AP via DS, the format using Element can also store the Source AP's address.

[0163] In the format using Elements, information regarding operation requests after the UL communication blockage period and other information can also be notified. In addition to adding a new Element ID to be used in the (FT) Action Frame, etc., a dedicated Management frame to be transmitted while operating within the UL communication blockage period may be defined. Furthermore, the number of bits may be reduced by using a Delay Bound or compressing the amount of information of the Target AP as needed. Note that the Source AP may also send information to the Target AP via DS. In this case, the address of the Target AP, not the address of the Source AP, is stored.

[0164] Table 2 summarizes the frame formats for the cases with and without encryption. Table 2 shows the correspondence between the status of encryption key possession and example frames used during the UL communication blockage period.

[0165] [Table 2]

[0166] Table 2 shows that when the encryption key ownership status is "Does not own an encryption key," the example frame is "Header (Control frame / QoS Null frame) / Public Action frame." When the encryption key ownership status is "Owns an encryption key," the example frame is "Management (Element / FT Action frame / Roaming frame)."

[0167] (3-1-4. Operation after AP switching is complete) (Decision and notification of actions after AP switching is complete) Furthermore, in performing the operation according to the first embodiment described above, the system notifies the user of the operation after the UL communication interruption period, along with a switching response signal, based on the information transmitted by the Roaming STA during the UL communication interruption period and context information, etc.

[0168] The following describes an example of a method for notifying the operation after AP switching is complete. Figure 12 is a diagram showing an example of AP switching processing when notifying the operation after AP switching according to the first embodiment. In the example in Figure 12, an example of sending a trigger signal together with the switching response signal is described. It is assumed that the notification of the operation after AP switching is complete includes information indicating the transmission of a trigger signal.

[0169] In the example in Figure 12, in the case of STA-initiated roaming, the Roaming STA sends a switching request signal to the Source AP. In the example in Figure 12, the Roaming STA sends 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, AP switching begins. In the example in Figure 12, the Source AP receives the switching request signal from the Roaming STA. Then, when the Source AP determines that it has correctly received the switching request signal, AP switching begins. Subsequently, at time t52, the Target AP sends a trigger signal along with a switching response signal to the Roaming STA. In this case, the Target AP also sends a notification of the operation after the AP switching is completed to the Roaming STA.

[0170] Furthermore, if for any reason the trigger signal cannot be transmitted along with the switching response signal, the Target AP sends a notification to the Roaming STA, which has low-latency traffic, that it is unable to transmit the trigger signal. In this case, the Target AP sends a notification of operation according to the second embodiment to the Roaming STA, for example. For example, the notification of operation after AP switching is completed includes the notification of operation according to the second embodiment. The second embodiment will be described in detail in 3-2. Second Embodiment.

[0171] Furthermore, if multiple STA200s, including a Roaming STA with low-latency traffic, are simultaneously performing AP switching, a notification of the operation according to the third embodiment, detailed in 3-3. Third Embodiment below, is sent to the Roaming STA. For example, the notification of operation after the completion of AP switching includes a notification of the operation according to the third embodiment.

[0172] In this way, during the UL communication interruption period, information from the Roaming STA allows for the transmission of switching response signals, along with notifications of operation after AP switching is complete, to STA200s with sufficient lifetime remaining and STA200s that do not require low-latency transmission. This allows for the control of the operation of multiple STA200s other than the Roaming STA that has low-latency traffic. Therefore, the likelihood of the Roaming STA with low-latency traffic being able to perform low-latency transmission can be increased.

[0173] (Regarding frame formatting) Next, the format of the transmittable frame will be explained using Figure 13. Figure 13 is a diagram showing an example of the frame configuration of the switching response signal according to the first embodiment. In the example in Figure 13, the Action After Roaming Response does not perform any processing according to the first embodiment (corresponding to Trigger in Table 3, which will be explained below), processing according to the second embodiment (corresponding to Temporal SP in Table 3), processing according to the third embodiment (corresponding to Channel Access Restriction in Table 3), or any special operation. The second and third embodiments will be described in detail in 3-2. Second Embodiment and 3-3. Third Embodiment, respectively.

[0174] The upper part of Figure 13 shows an example of the MAC frame format in IEEE 802.11. The lower part of Figure 13 shows the Frame Body of the MAC frame. In the example in Figure 13, the Frame Body of the MAC frame includes the Action After Roaming Response, Subsequent Content (SP Information / Trigger Information, etc.), etc. The Action After Roaming Response is 2 bits. The Subsequent Content can be any number of bits (corresponding to X bits in Figure 13).

[0175] Here, the type of action is specified by the information included in the Action After Roaming Response. Table 3 below shows the correspondence between the information included in the Action After Roaming Response and the type of action.

[0176] [Table 3]

[0177] Table 3 shows that when the Action After Roaming Response is "00", the Subsequent Content is "Trigger". Also, when the Action After Roaming Response is "01", the Subsequent Content is "Temporal SP".

[0178] Furthermore, if the Action After Roaming Response is "10", the Subsequent Content is "Channel Access Restriction". If the Action After Roaming Response is "11", the Subsequent Content is "No Action". In this way, the appropriate type of action can be specified depending on the information included in the Action After Roaming Response.

[0179] Furthermore, the information necessary for each action is included in the subsequent steps. For example, if the Action After Roaming Response is "00", the information necessary for the "Trigger" action is included in the subsequent steps. Note that although the example in Figure 13 assumes a Management Frame with a Frame Body, it is not limited to this. For example, it may be a Control Frame.

[0180] (3-1-5. Flowchart showing the procedure for the STA-side switching process according to the first embodiment) Next, the procedure for the switching process performed by the STA200 according to the first embodiment will be explained using Figure 14. Figure 14 is a flowchart showing an example of the switching process flow on the STA200 side according to the first embodiment.

[0181] First, let's explain the premise. In the example in Figure 14, we assume a case where a Roaming STA with low-latency traffic performs AP switching, and the Target AP sends a switching response signal. Also, in the example in Figure 14, we assume a Dual Link configuration.

[0182] Furthermore, the request for the Target AP to send a switching response signal is made at the time of sending the switching request signal. Also, negotiations between the Target AP and the Source AP regarding the conditions for holding cryptographic keys, and negotiations regarding frames and information that may be transmitted, are assumed to have taken place in advance. Additionally, information sharing between the Target AP and the Source AP is assumed to occur via DS or wireless.

[0183] The switching process on the STA200 side shown in Figure 14 is repeatedly executed by the Roaming STA at predetermined intervals, for example, while the Roaming STA is connected to the Source AP. In the example in Figure 14, it is assumed that the STA200 is the Roaming STA.

[0184] As shown in Figure 14, STA200 determines whether low-latency transmission of UL traffic is required (step S101). For example, if STA200 determines that low-latency transmission of UL traffic is required (step S101; Yes), it sends a switching request signal (step S102).

[0185] Next, STA200 receives a response signal to the switching request signal (step S103). Then, STA200 determines whether or not it has low-latency traffic during the UL communication interruption period (step S104).

[0186] For example, if STA200 determines that it is holding low-latency traffic during the UL communication interruption period (step S104; Yes), it sends notification information (step S105). Subsequently, STA200 receives a trigger signal along with a switching response signal from the Target AP (step S106).

[0187] On the other hand, if STA200 determines that it does not have low-latency traffic during the UL communication interruption period (step S104; No), it receives a switching response signal (step S108).

[0188] On the other hand, if STA200 determines that low-latency transmission of UL traffic is not required (step S101; No), it transmits a switching request signal (step S109). Subsequently, STA200 receives a response signal to the switching request signal (step S110).

[0189] Then, STA200 receives a switching response signal (step S111). Subsequently, STA200 starts UL communication with the Target AP (step S107). Then, STA200 terminates processing. Note that STA200 may send a switching request signal to either the Target AP or the Source AP.

[0190] Thus, when low-latency traffic occurs, it is necessary to restrict the transmittable frames, excluding QoS Data frames, during the UL communication blockage period to enable UL communication. For this reason, the STA200 sends a request signal to the Target AP to send a switching response signal, along with information about the frame types that can be transmitted during the UL communication blockage period and a request signal for transmittable information, along with the switching request signal. When a response signal is returned to the switching request signal, the transmittable frames, excluding QoS Data frames, are restricted during the UL communication blockage period, enabling UL communication. Furthermore, if traffic occurs during the UL communication blockage period, the STA200 sends traffic information, etc., along with a request to negotiate the operation regarding low-latency transmission after the UL communication blockage period to the Target AP. On the other hand, if no low-latency traffic occurs during the UL communication blockage period, the STA200 does not need to send notification information, including the operation regarding low-latency transmission after the UL communication blockage period and the buffer status of the STA200.

[0191] Furthermore, if low-latency transmission of UL traffic is not required, the STA200 will send a switching request signal as usual. Then, upon receiving a response signal to the switching request signal, AP switching will begin.

[0192] (3-1-6. Flowchart showing the procedure for the AP-side switching process according to the first embodiment) Next, the procedure for the switching process performed by AP100 according to the first embodiment will be explained using Figure 15. Figure 15 is a flowchart showing an example of the switching process flow on the AP100 side according to the first embodiment. In the example of Figure 15, AP100 is assumed to be the Target AP.

[0193] As shown in Figure 15, AP100 receives a transmission request signal from STA200 requesting the transmission of a switching response signal (step S201). For example, if AP100 receives a transmission request signal from STA200 (step S201; Yes), it receives a switching request signal (step S202).

[0194] Next, AP100 transmits a response signal to the switching request signal (step S203). Then, AP100 determines whether or not it received notification information from Roaming STA during the UL communication interruption period (step S204). For example, if AP100 receives notification information from Roaming STA during the UL communication interruption period (step S204; Yes), it transmits a trigger signal along with the switching response signal (step S205). Subsequently, AP100 terminates processing.

[0195] On the other hand, if AP100 has not received notification information from Roaming STA during the UL communication blockage period (step S204; No), it sends a switching response signal (step S208). Subsequently, AP100 terminates processing.

[0196] On the other hand, if AP100 has not received a transmission request signal from STA200 (step S201; No), it receives a switching request signal (step S206). Next, AP100 transmits a response signal to the switching request signal (step S207). Then, AP100 transmits a switching response signal (step S208). Subsequently, AP100 terminates its processing.

[0197] As shown in the flowchart in Figure 15, a distinction is made depending on whether or not a frame transmission request signal has been received by AP100 in advance during the UL communication interruption period. If AP100 has not received a request signal from STA200, AP100 receives a switching request signal. AP100 then returns a response signal to the switching request signal and sends a switching response signal to notify that the AP switching is complete after the AP switching is finished.

[0198] Furthermore, if there is a request to enable UL communication by restricting the transmittable frames, excluding QoS Data frames, during the UL communication blockage period, AP100 will send a response to such request. AP100 will then determine its operation during the UL communication blockage period. If AP100 has not received notification information from STA200 during the UL communication blockage period, AP100 will send a switching response signal, assuming there is no request from STA200. If AP100 receives a low-latency transmission request and notification information, including traffic information, from STA200 during the UL communication blockage period, AP100 will determine its operation after the UL communication blockage period based on the notification information.

[0199] (3-2. Second Embodiment) (3-2-1. Processing according to the second embodiment) Next, as a second embodiment, we will describe an example of setting a priority period for a Roaming STA with UL traffic requiring low-latency transmission. In the first embodiment described above, we described an example in which, when low-latency traffic occurs at the Roaming STA during the UL communication blockage period, the Target AP sends a trigger signal to the Roaming STA along with a switching response signal. However, there may be cases in which it is not possible to send a trigger signal.

[0200] For example, the above cases include situations where the Source AP sends a switching response signal, resource allocation is not completed in time, or there are many STA200s requesting AP switching. Additionally, there may be other Roaming STAs with low-latency traffic, and the data volume varies among STA200s, making UL OFDMA unavailable.

[0201] In such cases, the Target AP (or Source AP) sets a priority transmission period to allow the Roaming STA to operate with low latency. The Target AP (or Source AP) then sends a notification of the priority transmission period to the Roaming STA along with a switching response signal.

[0202] For example, as an example of operation during the priority transmission period, when a Target AP, Source AP, or Other AP acquires a TXOP during the priority transmission period, TXOP sharing or trigger signals are sent to enable Roaming STAs with low-latency traffic to transmit.

[0203] The following describes an example of the processing performed by the communication system during information exchange between the Target AP, Source AP, and Roaming STA. Figure 16 is a diagram showing an example of AP switching processing according to the second embodiment. In the example in Figure 16, it is assumed that the Target AP sends a switching response signal to the Roaming STA.

[0204] In the example in Figure 16, the Roaming STA makes a decision to perform AP switching at time t61. For example, in the case of STA-initiated roaming, the Roaming STA sends a switching request signal to the Source AP requesting it to switch APs. In the example in Figure 16, the Roaming STA sends the switching request signal to the Source AP at time t62.

[0205] Next, the Source AP initiates AP switching when it correctly receives a switching request signal from the Roaming STA. In the example in Figure 16, the Source AP receives a switching request signal from the Roaming STA. Then, if the Source AP determines that it has correctly received the switching request signal, AP switching is initiated. In the example in Figure 16, the UL communication interruption period is from time t62 to time t66.

[0206] Then, at time t63, UL traffic occurs at the Roaming STA. Subsequently, at time t64, the Roaming STA sends notification information to the Target AP. Then, at time t65, the Target AP sends a notification of the priority transmission period to the Roaming STA along with a switching response signal.

[0207] Here, we assume that UL traffic information is shared in advance between the Source AP and the Target AP. In this case, the Source AP performs TXOP Sharing at time t67 and transfers the TXOP to the Target AP. Subsequently, at time t68, the Target AP sends a trigger signal along with a switching response signal to the Roaming STA. In this way, the Target AP triggers STAs with low-latency UL traffic.

[0208] Furthermore, if only the Source AP is aware that the Roaming STA is holding low-latency traffic, the Source AP may send an indication to the Target AP to enable the Roaming STA to transmit at low latency, rather than having to perform TXOP sharing at time t67. This allows the Target AP to trigger the action even if it does not receive TXOP sharing from the Source AP, as long as it acquires channel rights.

[0209] This allows the Roaming STA to transmit UL communication after time t68. In the example in Figure 16, the Roaming STA transmits UL traffic at time t69. In this way, in addition to low-latency transmission of UL traffic, it is possible to transmit simultaneously with other STA200s by staggering the timing of the trigger signal transmission. This allows the communication system to improve transmission efficiency.

[0210] Furthermore, as an example of operation during a priority transmission period, like R-TWT SP, other STA200s can terminate transmission at the start of the SP and prevent channel access via Quiet Element. In this case, in order to perform an operation like R-TWT, it is necessary to notify other STA200s of the SP information.

[0211] Furthermore, as an example of operation during the priority transmission period, the number of STA200s competing for Roaming STAs with low-latency traffic can be reduced by combining it with the operation according to the third embodiment, which is detailed in 3-3. Third Embodiment below.

[0212] Furthermore, the priority transmission period is calculated using the Delay Budget value during the UL communication blockage period and information obtained from context information (such as SCS (Service Capability Server) information). The priority transmission period is calculated on a case-by-case basis.

[0213] In addition, in the second embodiment described above, a Capability check may be performed to indicate that the system supports the functions described in this disclosure. Capability information may be notified, for example, by a Beacon frame containing an Ultra High Reliability (UHR) Capability element, a Probe Request frame, or a Probe Request Response. Furthermore, in the second embodiment, the same pre-negotiation and notification actions described in (1) to (3) above are performed as in the first embodiment.

[0214] (3-2-2. Flowchart showing the procedure for switching on the STA side according to the second embodiment) Next, the procedure for the switching process performed by the STA200 according to the second embodiment will be explained using Figure 17. Figure 17 is a flowchart showing an example of the flow of the switching process on the STA200 side according to the second embodiment.

[0215] The assumptions in Figure 17 of the second embodiment are the same as those explained in Figure 14 of the first embodiment, so their explanation is omitted. Furthermore, the switching process on the STA200 side shown in Figure 17 is repeatedly executed by the Roaming STA at predetermined intervals, for example, while the Roaming STA is connected to the Source AP. Note that in the example of Figure 17, the STA200 is assumed to be the Roaming STA.

[0216] As shown in Figure 17, STA200 determines whether low-latency transmission of UL traffic is required (step S301). For example, if STA200 determines that low-latency transmission of UL traffic is required (step S301; Yes), it sends a switching request signal (step S302).

[0217] Next, STA200 receives a response signal to the switching request signal (step S303). Then, STA200 determines whether or not traffic occurred during the UL communication interruption period (step S304).

[0218] For example, if STA200 determines that traffic has occurred during the UL communication blockage period (step S304; Yes), it sends notification information (step S305). Subsequently, STA200 receives a switching response signal from the Target AP (step S306).

[0219] For example, STA200 receives a switching response signal and information regarding the priority transmission period included in the switching response signal. Then, STA200 receives a notification from the Target AP indicating that it cannot be triggered (step S307).

[0220] On the other hand, if STA200 determines that no traffic has occurred during the UL communication blockage period (step S304; No), it receives a switching response signal from the Target AP (step S309).

[0221] On the other hand, if STA200 determines that low-latency transmission of UL traffic is not required (step S301; No), it transmits a switching request signal (step S310). Subsequently, STA200 receives a response signal to the switching request signal (step S311).

[0222] Then, STA200 receives a switching response signal (step S312). Subsequently, STA200 starts UL communication with the Target AP (step S308). Then, STA200 terminates processing. Note that STA200 may send a switching request signal to either the Target AP or the Source AP.

[0223] (3-2-3. Flowchart showing the procedure for the AP-side switching process according to the second embodiment) Next, the procedure for the switching process performed by AP100 according to the second embodiment will be explained using Figure 18. Figure 18 is a flowchart showing an example of the switching process flow on the AP100 side according to the second embodiment. In the example of Figure 18, AP100 is assumed to be the Target AP.

[0224] As shown in Figure 18, AP100 receives a transmit request signal from STA200 (step S401). For example, if AP100 receives a transmit request signal from STA200 (step S401; Yes), it receives a switching request signal (step S402).

[0225] Next, AP100 transmits a response signal to the switching request signal (step S403). Then, AP100 determines whether or not it received notification information from Roaming STA during the UL communication interruption period (step S404).

[0226] For example, if AP100 receives a message from Roaming STA during the UL communication interruption period (step S404; Yes), it sends a switching response signal (step S405). Next, AP100 sends information regarding the priority transmission period (step S406). Then, AP100 prioritizes UL communication with Roaming STA (step S407). Finally, AP100 terminates its processing.

[0227] On the other hand, if AP100 has not received any data from Roaming STA during the UL communication blockage period (step S404; No), it sends a switching response signal (step S410). Subsequently, AP100 terminates its processing.

[0228] On the other hand, if AP100 has not received a transmission request signal from STA200 (step S401; No), it receives a switching request signal (step S408). Next, AP100 transmits a response signal to the switching request signal (step S409). Then, AP100 transmits a switching response signal (step S410). Subsequently, AP100 terminates its processing.

[0229] (3-3. Third Embodiment) (3-3-1. Processing according to the third embodiment) Next, as a third embodiment, we will describe an example in which channel access is not performed for a certain period of time for STA200s that do not require low-latency traffic. When multiple STA200s perform AP switching and multiple STA200s are holding traffic, channel contention occurs among the STA200s that have finished AP switching.

[0230] In this case, interruptions to UL communication may occur due to STA200s with ample lifetime or STA200s with traffic that does not require low-latency transmission. As a result, for example, a Roaming STA among the STA200s that has low-latency traffic may not be able to perform UL communication.

[0231] Therefore, channel access from ULs other than STA200, which require low-latency transmission, is temporarily suspended. For example, a Roaming STA with low-latency traffic cannot be triggered along with the transmission of the switching response signal. In this case, when transmitting the switching response signal, the Roaming STA traffic information notified during the UL communication blockage period, and SCS information notified by Context Transfer, are used to prevent channel access from STAs other than STA200, which require immediate low-latency transmission, for a certain period of time.

[0232] Figure 19 shows an example of AP switching processing according to the third embodiment. In the example in Figure 19, it is assumed that the Target AP sends a switching response signal to the Roaming STA. Furthermore, in the example in Figure 19, it is assumed that in an environment where multiple AP100s and STA200s exist, the Roaming STA, which requires low-latency transmission of UL traffic, performs AP switching.

[0233] In the example in Figure 19, the Roaming STA is STA200, which requires low-latency transmission for UL traffic. Another STA200, distinct from the Roaming STA, is the Other Roaming STA. In the example in Figure 19, it is assumed that the Other Roaming STA has already performed AP switching. In this case, the Roaming STA will perform AP switching.

[0234] In the example in Figure 19, in the case of STA-initiated roaming, the Roaming STA sends a switching request signal to the Source AP. In the example in Figure 19, the Roaming STA sends a 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, AP switching is initiated. In the example in Figure 19, the Source AP receives the switching request signal from the Roaming STA. Subsequently, when the Source AP determines that it has correctly received the switching request signal, AP switching is initiated.

[0235] Then, in Roaming STA, UL traffic occurs at time t72. Subsequently, in Other Roaming STA, UL traffic occurs at time t73.

[0236] Next, at time t74, the Target AP sends a switching response signal to the Other Roaming STA. In this case, the Target AP sends information about an additional UL communication blackout period to the Other Roaming STA. In the example in Figure 19, the UL communication blackout period is extended by the duration of region RC71. As a result, the Other Roaming STA does not access the channel until the additional UL communication blackout period has elapsed. Then, at time t76, the Target AP sends a switching response signal to the Roaming STA.

[0237] In the example in Figure 19, the status of UL or DL ​​communication for the Other Roaming STA is indicated by bars B71 or B72. As shown by bar B71, in the UL communication of the Other Roaming STA, the period up to time t75 corresponds to the UL communication interruption period. Also, UL communication is not performed during the period corresponding to area RC71. After the period corresponding to area RC71, the Other Roaming STA performs UL communication with the Target AP.

[0238] Furthermore, as shown in bar B72, Other Roaming STA performs DL communication with Source AP. After the UL communication blockage period, Other Roaming STA performs DL communication with either Source AP or Target AP. Then, from time t77, Other Roaming STA performs DL communication with Target AP.

[0239] In this way, the number of other STAs 200 competing with the Roaming STA having low-latency traffic for channel access can be reduced. As a result, the Roaming STA can perform low-latency transmission. Also, by transmitting a trigger signal to a plurality of STAs 200 including the STAs 200 with restricted channel access, UL traffic can be transmitted simultaneously. As a result, the communication system can improve the transmission efficiency.

[0240] Further, unlike the case of delaying the transmission of the switching response signal by simply extending the UL communication interruption period in the third embodiment, the link between the Roaming STA and the Target AP can be activated by transmitting the switching response signal to the Roaming STA. As a result, it becomes possible to similarly respond even when low-latency transmission is required for DL.

[0241] In addition, in the second embodiment, a Capability check indicating that it corresponds to the function shown in the present disclosure may be performed. The Capability information may be notified, for example, by a Beacon frame including a UHR (Ultra High Reliability) Capability element, a Probe Request frame, a Probe Request Response, or the like. Also, in the second embodiment, as in the first embodiment, the prior negotiation and notification operations (1) to (3) described above are performed.

[0242] Also, the AC that performs channel access restriction may be limited. For example, traffic in the best effort or background access category may be restricted from being transmitted.

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

[0244] 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, so the description will be omitted. Note that in the third embodiment, it is assumed that channel contention occurs among a plurality of STAs 200.

[0245] The switching process on the STA 200 side shown in FIG. 20 is repeatedly executed by the STA 200 at a predetermined period, for example, while the STA 200 is connected to the Source AP. In the example of FIG. 20, the STA 200 is described as being different from the Roaming STA.

[0246] As shown in FIG. 20, the STA 200 determines whether low-latency transmission of UL traffic is required (step S501). For example, when the STA 200 determines that low-latency transmission of UL traffic is required (step S501; Yes), it transmits a switching request signal (step S502).

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

[0248] For example, when the STA 200 determines that traffic has occurred during the UL communication interruption period (step S504; Yes), it transmits notification information (step S505). Subsequently, the STA 200 receives a switching response signal from the Target AP (step S​​​​

[0250] Next, the Target AP, which sends a switching response signal based on notification information, determines that low-latency transmission is not necessary, and the STA200 receives information regarding an additional UL communication blockage period (step S507). The STA200 then determines whether the channel access restriction has ended (step S508).

[0251] For example, if STA200 determines that the channel access restriction has not ended (step S508; No), it waits until the channel access restriction ends. On the other hand, if STA200 determines that the channel access restriction has ended (step S508; Yes), it starts UL communication with the Target AP (step S509). Then, STA200 terminates its processing.

[0252] On the other hand, if STA200 determines that low-latency transmission of UL traffic is not required (step S501; No), it transmits a switching request signal (step S510). Subsequently, STA200 receives a response signal to the switching request signal (step S511).

[0253] Then, STA200 receives a switching response signal (step S512). Subsequently, STA200 determines whether or not it has received information regarding an additional UL communication interruption period (step S513). For example, if STA200 determines that it has not received information regarding an additional UL communication interruption period (step S513; No), it terminates the process.

[0254] On the other hand, if STA200 determines that it has received information regarding an additional UL communication blocking period (step S513; Yes), it determines whether the channel access restriction has ended (step S514).

[0255] For example, if STA200 determines that the channel access restriction has not ended (step S514; No), it waits until the channel access restriction ends. On the other hand, if STA200 determines that the channel access restriction has ended (step S514; Yes), it terminates the process. Note that STA200 may send a switching request signal to either the Target AP or the Source AP.

[0256] In this manner, if AP switching occurs simultaneously on multiple STA200s and a trigger signal cannot be transmitted immediately, channel access is restricted to other STA200s that are different from the STA200 that needs to perform low-latency transmission of UL traffic and that have sufficient lifetime remaining. In this case, channel access to the other STA200s will be restricted until the additional UL communication blockage period ends. Furthermore, channel access to the other STA200s will be restricted until a trigger signal can be transmitted.

[0257] (3-3-3. Flowchart showing the procedure for the AP-side switching process according to the third embodiment) Next, the procedure for the switching process performed by AP100 according to the third embodiment will be explained using Figure 21. Figure 21 is a flowchart showing an example of the switching process flow on the AP100 side according to the third embodiment. In the example of Figure 21, AP100 is assumed to be the Target AP. Also, in the example of Figure 21, STA200 is assumed to be a different STA200 from the Roaming STA.

[0258] As shown in Figure 21, AP100 receives a transmit request signal from STA200 (step S601). For example, if AP100 receives a transmit request signal from STA200 (step S601; Yes), it receives a switching request signal (step S602).

[0259] Next, AP100 transmits a response signal to the switching request signal (step S603). Then, AP100 determines whether or not it has received notification information from STA200 during the UL communication blockage period (step S604). For example, if AP100 has received it from STA200 during the UL communication blockage period (step S604; Yes), it transmits a switching response signal (step S605). Next, AP100 transmits information regarding additional UL communication blockage periods (step S606).

[0260] On the other hand, if AP100 has not received anything from STA200 during the UL communication blockage period (step S604; No), it sends a switching response signal (step S609). Then, AP100 determines whether or not to implement channel access restrictions (step S610).

[0261] For example, if AP100 determines that it will not implement channel access restrictions (step S610; No), it terminates processing. On the other hand, if AP100 determines that it will implement channel access restrictions (step S610; Yes), it sends information regarding an additional UL communication blocking period (step S611). Subsequently, AP100 terminates processing.

[0262] On the other hand, if AP100 has not received a transmit request signal from STA200 (step S601; No), it receives a switching request signal (step S607). Subsequently, AP100 transmits a response signal to the switching request signal (step S608). Then, AP100 transmits a switching response signal (step S609).

[0263] Next, AP100 determines whether or not to implement channel access restrictions (step S610). For example, if AP100 determines that it will not implement channel access restrictions (step S610; No), it terminates the process. On the other hand, if AP100 determines that it will implement channel access restrictions (step S610; Yes), it transmits information regarding an additional UL communication blocking period (step S611). Subsequently, AP100 terminates the process.

[0264] (3-4. Variations according to the embodiment) The information processing according to the first to third embodiments described above may involve various variations. The variations of the first to third embodiments will be described below.

[0265] (3-4-1. Other processing) In the first embodiment above, an example was described where when low-latency traffic occurs in the Roaming STA during the UL communication interruption period, the Target AP transmits a trigger signal to the Roaming STA together with a switching response signal, but it is not limited to this.

[0266] For example, the Source AP may notify the Target AP that it has processed all the traffic of the Roaming STA. For example, when Single Link is applied, the Roaming STA can only activate a link with one AP100 at a time. Therefore, the Source AP needs to transmit the data buffered in the Source AP to the Roaming STA before Data Path Switching unless it is forwarded to the Target AP.

[0267] Here, it is also conceivable to switch the link so that the Target AP performs UL communication and the Source AP performs DL communication. However, it takes time to switch the link. Also, when communicating on the other link, when communication starts on the other link, the Roaming STA cannot receive the traffic that cannot be received when the link is switched.

[0268] More specifically, when the Roaming STA is transmitting UL traffic to the Target AP, if the Source AP starts transmitting DL traffic to the Roaming STA, the Roaming STA cannot receive the DL data.

[0269] Furthermore, AP100 cannot recognize that the Roaming STA is in the process of link switching. Therefore, if transmission is initiated during link switching, the Roaming STA will not be able to receive the data. For example, Non-Patent Document 2 proposes a method in which buffered traffic on the Source AP is processed before the link with the Target AP is activated.

[0270] When the Target AP sends a switching response signal, in the Single Link case described above, it is necessary to notify the Source AP that it has processed all of the Roaming STA's traffic. Therefore, after processing all of the Roaming STA's traffic, the Source AP sends a notification to the Target AP indicating that it has processed the buffered traffic.

[0271] The following describes an example in which the Source AP notifies the Target AP that it has processed all of the Roaming STA's traffic. Figure 22 shows an example of AP switching processing related to a modified example. In the example in Figure 22, it is assumed that the Target AP sends a switching response signal to the Roaming STA.

[0272] In the example in Figure 22, in the case of STA-initiated roaming, the Roaming STA sends a switching request signal to the Source AP. In the example in Figure 22, the Roaming STA sends the switching request signal to the Source AP at time t81.

[0273] Next, the Source AP initiates AP switching when it correctly receives a switching request signal from the Roaming STA. In the example in Figure 22, the Source AP receives a switching request signal from the Roaming STA. Then, if the Source AP determines that it has correctly received the switching request signal, AP switching is initiated. In the example in Figure 22, the UL communication interruption period is from time t81 to time t87.

[0274] Then, at time t82, UL traffic occurs at the Roaming STA. Subsequently, at time t83, the Roaming STA sends notification information to the Target AP. Then, at time t84, the Source AP sends buffered data to the Roaming STA.

[0275] Next, at time t85, the Source AP sends a notification to the Target AP indicating that it has processed the buffered traffic. Then, at time t86, the Target AP sends a switching response signal to the Roaming STA. This allows the communication system to improve transmission efficiency.

[0276] Furthermore, the notification indicating that buffered traffic has been processed may be transmitted via a wired connection using a DS. Alternatively, the notification indicating that buffered traffic has been processed may be transmitted wirelessly.

[0277] Furthermore, the Target AP may receive from the Source AP a notification indicating that it has processed the buffered traffic, along with information indicating the buffer status of the Roaming STA, and / or instruction information instructing the Roaming STA to perform low-latency transmission.

[0278] For example, when sending a notification indicating that buffered traffic has been processed, the Source AP may send the Roaming STA's buffer status and an indication to the Target AP that enables the Roaming STA to transmit UL communications with low latency after AP switching.

[0279] This allows the Target AP to operate even if only the Source AP is aware of the Roaming STA's traffic status. For example, even if the Target AP is disabled from transmitting signals during a UL communication blockage period, the Source AP can send buffer status and indications to the Target AP, allowing the Target AP to operate.

[0280] (4. Other Embodiments) The processes described in each embodiment above may be carried out in various other forms besides those described above.

[0281] Furthermore, among the processes described in each of the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically by known methods. In addition, the processing procedures, specific names, and information including various data and parameters shown in the above documents and drawings can be changed at will unless otherwise specified. For example, the various information shown in each figure is not limited to the information shown.

[0282] Furthermore, the components of each illustrated device are functionally conceptual and do not necessarily need to be physically configured as shown. In other words, the specific forms of distribution and integration of each device are not limited to those shown, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads and usage conditions.

[0283] Furthermore, the embodiments and modifications described above can be combined as appropriate, provided that the processing content is not inconsistent.

[0284] Furthermore, the effects described herein are merely illustrative and not limiting; other effects may also occur.

[0285] (5. Effects of the communication device related to this disclosure) As described above, the communication device according to the present disclosure is a second communication device that receives a second switching request signal from the first communication device (corresponding to a Target AP in the embodiment) in response to a first switching request signal transmitted to the first communication device from a terminal device (corresponding to a Roaming STA in the embodiment) connected to the first communication device, and that requests to switch the connection destination from the first communication device to the second communication device (corresponding to a Target AP in the embodiment), and that transmits to the terminal device 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, along with a trigger signal for the terminal device to transmit data.

[0286] In this way, the communication device can transmit data immediately after receiving the switching response signal without interruption from other terminal devices. This enables low-latency transmission of UL traffic. Furthermore, since the communication device receives a response signal in the form of an UL Data Frame in response to the switching response signal, it eliminates the need to send an Ack (acknowledgment) to indicate that the switching response signal was transmitted correctly.

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

[0288] This allows the communication device to control the operation of the terminal device by receiving a transmission request signal from the terminal device.

[0289] Furthermore, the control unit receives a transmission request signal from the terminal device, which requests that the switching response signal be transmitted within the UL communication interruption period.

[0290] This allows the communication device to have the right to determine the operation of the terminal device.

[0291] Furthermore, the control unit receives information from the terminal device that varies depending on whether or not it possesses the encryption key between the second communication device and the terminal device.

[0292] This allows communication devices to achieve highly secure communication.

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

[0294] This allows the communication device to receive notification information necessary for determining its actions after transmitting a switching response signal.

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

[0296] This allows the communication device to control the operation of the terminal device after the UL communication interruption period.

[0297] Furthermore, along with the switching response signal, the control unit transmits to the terminal device information regarding the priority transmission period, which is set as the period during which the terminal device can preferentially transmit data.

[0298] This allows communication devices to more easily obtain opportunities to transmit ULs, thereby achieving lower latency. Furthermore, by staggering the transmission timing of the switching response signal, communication devices can transmit traffic simultaneously with other terminal devices. This allows communication devices to improve transmission efficiency.

[0299] Furthermore, the control unit transmits a switching response signal to a terminal device other than the terminal device.

[0300] This allows the communication device to transmit signals to control the operation of other terminal devices by sending a switching response signal.

[0301] Furthermore, the control unit transmits information regarding additional UL communication blocking periods to other terminal devices.

[0302] This allows the communication device to control the operation of other terminal devices after the UL communication interruption period.

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

[0304] This allows the communication device to send a switching response signal to the terminal device, even when using a Single Link connection.

[0305] As described above, the terminal device relating to this disclosure includes a control unit that transmits a switching request signal to the connected first communication device requesting that the connection destination be switched from the first communication device to the second communication device, and transmits data to the second communication device when it receives a switching response signal from the second communication device in response to switching from the first communication device to the second communication device, along with a trigger signal for transmitting data.

[0306] Thus, when a terminal device has UL traffic requiring low latency, the terminal device can request low-latency transmission of the UL traffic after AP switching. Furthermore, the terminal device can initiate UL communication by receiving a switching response signal from the second communication device.

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

[0308] This allows the terminal device to have its operation controlled by the communication device.

[0309] Furthermore, the control unit sends a transmission request signal to the second communication device as a transmission request signal, requesting that the switching response signal be transmitted within the UL communication interruption period.

[0310] This allows the terminal device to transfer the right to make operational decisions to the communication device.

[0311] Furthermore, before transmitting the switching request signal, the control unit transmits a transmission request signal to the second communication device using a Multi-Link setup frame or a Roaming Request frame.

[0312] This allows the terminal device to suitably transmit a transmission request signal to the communication device using a Multi-Link setup frame or a Roaming Request frame.

[0313] Furthermore, the control unit transmits information to the second communication device that varies depending on whether or not it possesses the encryption key between the second communication device and the terminal device.

[0314] This allows terminal devices to achieve communication that takes security risks into consideration.

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

[0316] This allows the terminal device to transmit notification information necessary for determining its actions after the second communication device transmits a switching response signal.

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

[0318] This allows the terminal device to understand the operation of the second communication device after the UL communication interruption period.

[0319] Furthermore, the control unit receives from the second communication device, along with a switching response signal, information regarding the priority transmission period, which is set as a period during which the terminal device can preferentially transmit data.

[0320] This allows terminal devices to transmit traffic simultaneously with other terminal devices by staggering the timing of receiving the switching response signal.

[0321] (6. Example of a computer configuration) The series of processes described above can be executed by hardware or by software. When the series of processes are executed by software, the programs that make up the software are installed from a program storage medium onto a computer that is built into dedicated hardware, or a general-purpose personal computer.

[0322] Figure 23 is a block diagram showing an example of the hardware configuration of a computer that executes the series of processes described above by a program.

[0323] The CPU (Central Processing Unit) 801, ROM (Read Only Memory) 802, and RAM (Random Access Memory) 803 are interconnected by a bus 804.

[0324] An input / output interface 805 is further connected to the bus 804. An input unit 806, consisting of a keyboard, mouse, etc., and an output unit 807, consisting of a display, speaker, etc., are connected to the input / output interface 805. Information related to this technology, such as information related to handover (AP switching process), may be output or displayed from the output unit 807. Information related to this technology, such as information related to handover (AP switching process), may be input from the input unit 806, and confirmation or response to the information output or displayed to the output unit 807 may be input. In addition, a storage unit 808, consisting of a hard disk or non-volatile memory, a communication unit 809, consisting of a network interface, etc., and a drive 810 that drives removable media 811 are connected to the input / output interface 805.

[0325] In a computer configured as described above, the CPU 801 performs the aforementioned series of processes by loading a program stored in the memory unit 808 into the RAM 803 via the input / output interface 805 and the bus 804 and executing it. For example, the CPU 801 may execute a processing program corresponding to the flowcharts in Figures 14-15, 17-18, and 20-21 of this technology.

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

[0327] The programs executed by the computer may be programs that are processed chronologically in the order described herein, or they may be programs that are processed in parallel or at necessary times, such as when a call is made.

[0328] (7. Application Examples) This technology can be applied to a variety of products. For example, the AP100 (communication device) in Figure 4, the STA200 (terminal device) and the control device 300 in Figure 5 may be implemented as mobile terminals such as smartphones, tablet PCs (personal computers), notebook PCs, portable game consoles, or digital cameras; fixed terminals such as television receivers, projectors, printers, digital scanners, or network storage devices; or in-vehicle terminals such as car navigation systems and drive recorders. Furthermore, the AP100 (communication device), STA200 (terminal device) and the control device 300 may be implemented as M2M (Machine To Machine Communication) terminals or IoT (Internet of Things) terminals such as smart meters, vending machines, remote monitoring devices, or POS (Point of Sale) terminals. In addition, the AP100 (communication device), STA200 (terminal device) and the control device 300 may be implemented as terminals requiring low latency and high reliability, such as XR (Extended Reality / Cross Reality) devices. Furthermore, AP100 (communication device), STA200 (terminal device), and control device 300 may be wireless communication modules (for example, integrated circuit modules consisting of a single die) mounted on these terminals.

[0329] On the other hand, for example, AP100 (communication device), STA200 (terminal device), and control device 300 may be implemented as a wireless LAN AP (wireless base station) with or without router functionality. Alternatively, AP100 (communication device), STA200 (terminal device), and control device 300 may be implemented as a mobile wireless LAN router. Furthermore, AP100 (communication device), STA200 (terminal device), and control device 300 may be implemented as a cellular communication base station and femtocell. In addition, AP100 (communication device), STA200 (terminal device), and control device 300 may be wireless communication modules (for example, integrated circuit modules consisting of a single die) mounted on these devices.

[0330] (Example of smartphone configuration) Figure 24 is a block diagram showing a schematic configuration example of a smartphone 900 to which this technology is applied. Although Figure 24 is shown as an example of the configuration of a smartphone 900, it is not limited to this and may also be an example of the configuration of various devices and functions described above.

[0331] The smartphone 900 includes a processor 901, memory 902, 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. The smartphone 900 also 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 features, or some of them.

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

[0333] Memory 902 includes RAM and ROM and stores programs and data executed by processor 901.

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

[0335] External connection interface 904 is an interface for connecting external devices such as memory cards or USB (Universal Serial Bus) devices to the smartphone 900.

[0336] The camera 906 has an image sensor, such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor), and generates an image.

[0337] Sensor 907 includes, for example, a group of sensors such as a positioning sensor, a gyroscope, a geomagnetic sensor, and an accelerometer.

[0338] Microphone 908 converts the audio input to smartphone 900 into an audio signal.

[0339] The input device 909 includes, for example, a touch sensor that detects touches on the screen of the display device 910, a keypad, a keyboard, a button, or a switch, and accepts 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 the output image of the smartphone 900.

[0341] Speaker 911 converts the audio signal output from smartphone 900 into sound.

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

[0343] In infrastructure mode, the wireless communication interface 913 communicates with other devices via the wireless LAN access point (AP). In ad-hoc mode or direct communication modes such as Wi-Fi Direct, the wireless communication interface 913 communicates directly with other devices.

[0344] In Wi-Fi Direct, unlike ad-hoc mode, one of the two devices acts as the access point (AP), but communication takes place directly between those devices.

[0345] The wireless communication interface 913 typically includes a baseband processor, RF (Radio Frequency) circuitry, and a power amplifier. The wireless communication interface 913 may also be a single-chip module integrating memory for storing a communication control program, a processor for executing the program, and associated circuitry.

[0346] The wireless communication interface 913 may support other types of wireless communication methods in addition to the wireless LAN method, such as short-range wireless communication methods like Bluetooth®, proximity wireless communication methods like NFC, or 3GPP® cellular communication methods such as 2G, 3G, 4G, 5G, and 6G. The wireless communication interface 913 may be a single-chip module that supports multiple wireless communication methods, or it may be a combination of modules that support some of the wireless communication methods.

[0347] The antenna switch 914 switches the destination of the antenna 915 among multiple circuits included in the wireless communication interface 913 (for example, circuits for different wireless communication methods, or transmitting and receiving circuits).

[0348] Antenna 915 has one or more antenna elements (for example, multiple antenna elements that make up a MIMO (Multiple Input Multiple Output) antenna, or multiple antenna elements that make up an array antenna) and is used for transmitting and receiving radio signals via wireless communication interface 913.

[0349] Note that the smartphone 900 is not limited to the example in Figure 24 and may have multiple antennas (for example, an antenna for wireless LAN, an antenna for proximity wireless communication, and an antenna for cellular communication). In that case, the antenna switch 914 may be omitted from the configuration of the smartphone 900.

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

[0351] The battery 918 supplies power to each block of the smartphone 900 shown in Figure 24 via power supply lines partially shown by dashed lines in the figure. The auxiliary controller 919 operates the minimum necessary functions of the smartphone 900, for example, in sleep mode. The battery 918 may also be charged via the external connection interface 904. The battery 918 may also have a function that allows reading of information regarding the remaining power, cumulative power supply time, or cumulative power supply amount, and the processor 901, wireless communication interface 913, or auxiliary controller 919 may control any of the functions of the above embodiments based on the information read from the battery 918.

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

[0353] The smartphone 900 may also operate as a wireless AP (software AP) by having the processor 901 execute AP functions at the application level. Alternatively, the wireless communication interface 913 may have wireless AP functionality. Furthermore, the processor 901 or the wireless communication interface 913 may have a tethering function using both wireless LAN and cellular communication methods, and may transmit payload data received via cellular communication using the wireless LAN method, or transmit payload data received via wireless LAN using the cellular communication method. The smartphone 900 may also enable the tethering function through user input.

[0354] Furthermore, the smartphone 900 may be equipped with a biometric authentication unit (fingerprint authentication, palm print authentication, voice authentication, vascular authentication, facial authentication, iris authentication, retinal authentication). In this case, the wireless communication interface 913 on which the communication control unit 116 in Figure 4 and the communication control unit 216 in Figure 5 are implemented is configured to receive power from the same battery 918 as at least one of the display device 910, the speaker 911, and the biometric authentication unit.

[0355] Furthermore, 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 via the wireless communication interface 913. In this case, information related to this technology, such as information related to handover (AP100 switching process), may be output from at least one of the display device 910 and the speaker 911. In addition, the input device 909 may input confirmation or response to the information output from at least one of the display device 910 and the speaker 911.

[0356] (Example of in-vehicle device configuration) Figure 25 is a block diagram showing an example of the schematic configuration of an in-vehicle device 920 to which this technology is applied. Although Figure 25 is shown as an example of the configuration of the in-vehicle device 920, it is not limited to this, and may also be an example of the configuration of various devices and functions described above.

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

[0358] The processor 921 may be, for example, a CPU or a SoC, and controls the navigation and other functions of the in-vehicle device 920. The processor 921 can also control the vehicle's drivetrain, such as the brakes, accelerator, or steering, based on information obtained through communication based on this technology.

[0359] Memory 922 includes RAM and ROM and stores programs and data executed by processor 921.

[0360] The GNSS module 924 uses GNSS signals received from GNSS satellites to measure the position (e.g., latitude, longitude, and altitude) of the on-board device 920.

[0361] Sensor 925 includes, for example, a group of sensors such as a gyro sensor, a geomagnetic sensor, a millimeter-wave radar, a camera (image sensor such as a CCD or CMOS), and a barometric pressure sensor.

[0362] The data interface 926 is connected to the in-vehicle network 941, for example, via terminals (not shown), and acquires data generated on the vehicle side, such as vehicle-side data.

[0363] The content player 927 plays content stored on a storage medium (e.g., 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, button, or switch that detects touches on the screen of the display device 930, and accepts operations or information input from the user. For example, the input device 929 may also accept confirmation or 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, OLED, or QD display, and displays navigation functions or images of content being played, as well as information about this technology, such as information about handover (AP switching process).

[0366] Speaker 931 outputs navigation functions, audio of the content being played, or information related to this technology, such as information related to handover (AP switching process).

[0367] Note that in the in-vehicle device 920, the navigation function and the functions provided by the content player 927 are optional. The navigation function and the content player 927 may be omitted from the configuration of the in-vehicle device 920.

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

[0369] In infrastructure mode, the wireless communication interface 933 communicates with other devices via the wireless LAN access point (AP). In ad-hoc mode or direct communication modes such as Wi-Fi Direct, the wireless communication interface 933 communicates directly with other devices.

[0370] In Wi-Fi Direct, unlike ad-hoc mode, one of the two devices acts as the access point (AP), but communication takes place directly between those devices.

[0371] The wireless communication interface 933 typically includes a baseband processor, RF circuitry, and power amplifiers. The wireless communication interface 933 may also be a single-chip module integrating a memory for storing a communication control program, a processor for executing the program, or related circuitry.

[0372] The wireless communication interface 933 may support other types of wireless communication methods in addition to the wireless LAN method, such as short-range wireless communication methods like Bluetooth, proximity wireless communication methods like NFC, or 3GPP cellular communication methods such as 2G, 3G, 4G, 5G, and 6G. The wireless communication interface 933 may be a single-chip module that supports multiple wireless communication methods, or it may be a combination of modules that support some of the wireless communication methods.

[0373] The antenna switch 934 switches the destination of the antenna 935 among multiple circuits included in the wireless communication interface 933 (for example, circuits for different wireless communication methods, or transmitting and receiving circuits).

[0374] Antenna 935 has one or more antenna elements (for example, multiple antenna elements that make up a MIMO (Multiple Input Multiple Output) antenna, or multiple antenna elements that make up an array antenna) and is used for transmitting and receiving radio signals via wireless communication interface 933.

[0375] Note that the in-vehicle device 920 is not limited to the example in Figure 25, and may include multiple antennas 935 (for example, an antenna for wireless LAN, an antenna for proximity wireless communication, and an antenna for cellular communication). In that case, the antenna switch 934 may be omitted from the configuration of the in-vehicle device 920.

[0376] Battery 938 supplies power to each block of the on-board device 920 shown in Figure 25 via the power supply lines partially shown by dashed lines in the figure. Battery 938 may also store power supplied from the vehicle. Alternatively, the on-board device 920 may not have a battery and may utilize power supplied from the vehicle via a voltage regulator or capacitor.

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

[0378] Furthermore, the wireless communication interface 933 may operate as the AP100 (communication device), STA200 (terminal device), or control device 300 described above, providing wireless connectivity to terminals held by users in the vehicle. For example, the wireless communication interface 933 may connect the in-vehicle device 920 to other peripheral devices, and the in-vehicle device 920 may utilize CarPlay® or Android Auto®. The wireless communication interface 933 may also connect the in-vehicle device 920 to other peripheral devices using a short-range wireless communication method, infrastructure mode, or a Wi-Fi Direct wireless LAN method.

[0379] The in-vehicle device 920 may also operate as a wireless AP (software AP) by having the processor 921 execute AP functions at the application level. Alternatively, the wireless communication interface 933 may have wireless AP functionality. Furthermore, the processor 921 or the wireless communication interface 933 may have a tethering function using both wireless LAN and cellular communication methods, and may transmit payload data received via cellular communication using the wireless LAN method, or transmit payload data received via wireless LAN using the cellular communication method. The tethering function of the in-vehicle device 920 may be enabled by user input.

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

[0381] (Example of wireless AP configuration) Figure 26 is a block diagram showing an example of a schematic configuration of a wireless AP950 to which this technology is applied. Although Figure 26 is described as an example of the configuration of a wireless AP950, it is not limited to this, and may also be an example of the configuration of various devices and functions described above.

[0382] The wireless AP950 includes a controller 951, memory 952, input device 954, display device 955, network interface 957, wireless communication interface 963, antenna switch 964, and antenna 965. The wireless AP950 may include all of the above, or some of them.

[0383] The controller 951 may be, for example, a CPU or a DSP (Digital Signal Processor) and operates various functions of the wireless AP 950 at the IP (Internet Protocol) layer and higher layers (e.g., access restriction, routing, encryption, firewall, and log management).

[0384] Memory 952 includes RAM and ROM and stores programs executed by controller 951, as well as various control information (e.g., terminal list, routing table, encryption key, security settings, and logs).

[0385] The input device 954 includes, for example, buttons and switches, and accepts user input. For example, the input device 954 may accept confirmation or response to information output from the display device 955. The input device 954 may also accept user input such as switching the wireless function on / off, and switching between router function and access point function.

[0386] The display device 955 includes an LED lamp or the like and displays the operating status of the wireless AP 950. The display device 955 may also display information related to this technology, such as information related to handover (AP switching process).

[0387] The network interface 957 is a wired communication interface for the wireless AP 950 to connect to the wired communication network 958. The network interface 957 may have multiple connection terminals. The network interface 957 may output payload data included in the wireless signal input from the wireless communication interface 963 as a wired signal, or it may receive payload data output as a wireless signal from the wireless communication interface 963 as a wired signal, or it may input and output wired signals in parallel with or independently of the wireless communication interface 963's input and output of wireless signals. The wired communication network 958 may be a LAN such as Ethernet®, or a WAN (Wide Area Network).

[0388] The wireless communication interface 963 supports one or more 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. Furthermore, when the wireless AP 950 is mounted on a cellular communication base station and femtocell, the wireless communication interface 963 may support other types of wireless communication methods in addition to wireless LAN, such as 3GPP cellular communication methods including 2G, 3G, 4G, 5G, and 6G. The wireless communication interface 963 may be a single-chip module supporting multiple wireless communication methods, or a combination of modules supporting some of the wireless communication methods.

[0389] The wireless communication interface 963 typically includes a baseband processor, RF circuitry, and power amplifiers, among others.

[0390] The wireless communication interface 963 may be a single-chip module integrating a memory for storing a communication control program, a processor for executing the program, or related circuits.

[0391] The antenna switch 964 switches the destination of the antenna 965 among multiple circuits included in the wireless communication interface 963 (for example, circuits for different wireless communication methods, or transmitting and receiving circuits).

[0392] Antenna 965 has one or more antenna elements (for example, multiple antenna elements that make up a MIMO (Multiple Input Multiple Output) antenna, or multiple antenna elements that make up an array antenna) and is used for transmitting and receiving radio signals via wireless communication interface 963.

[0393] In the wireless AP950 shown in Figure 26, for example, the communication control unit 116 in Figure 4 and the communication control unit 216 in Figure 5 may be implemented in the wireless communication interface 963. For example, the processing programs corresponding to the flowcharts in Figures 14-15, 17-18, and 20-21 may be executed in the wireless communication interface 963. Furthermore, at least some of these functions may be implemented in the controller 951.

[0394] The above-described embodiments are merely examples of how to realize this technology, and there is a corresponding relationship between the matters in the embodiments and the inventive features in the claims. Similarly, there is a corresponding relationship between the inventive features in the claims and the matters in the embodiments of this technology that bear the same name. However, this technology is not limited to the embodiments and can be realized by making various modifications to the embodiments without departing from the gist of the technology.

[0395] Furthermore, some or all of the communication device, terminal device, and control device described in the above embodiments may be implemented as, for example, a semiconductor chip (IC (Integrated Circuit)) having wireless communication control functionality. Alternatively, they may be implemented as a single semiconductor chip equipped with multiple functions, such as an SoC (System on Chip), or as a combination of multiple semiconductor chips having a single function, such as a processor. Moreover, multiple SoCs may be combined, or a single-function semiconductor chip may be combined with an SoC. In addition, each part may be implemented as a dedicated semiconductor chip such as an ASIC (Application Specific Integrated Circuit), or as a combination of a general-purpose processor and software or firmware, or as a semiconductor chip such as an FPGA (Field Programmable Gate Array).

[0396] Furthermore, the processing procedure described in the above-described embodiment may be considered as a method comprising these steps, or as a program or recording medium that stores such a program for causing the computer to execute these steps.

[0397] For example, CDs (Compact Discs), MDs (MiniDiscs), DVDs (Digital Versatile Discs), memory cards, and Blu-ray Discs (Blu-ray® Discs) can be used as recording media.

[0398] In this specification, a system refers to a collection of multiple components (devices, modules (parts), etc.), regardless of whether all components are located in the same enclosure. Therefore, multiple devices housed in separate enclosures and connected via a network, and a single device containing multiple modules within a single enclosure, are both considered systems.

[0399] Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also occur.

[0400] The embodiments of this technology are not limited to those described above, and various modifications are possible without departing from the spirit of this technology.

[0401] For example, this technology can be configured as cloud computing, where a single function is shared and processed collaboratively by multiple devices via a network.

[0402] Furthermore, each step described in the flowchart above can be performed by a single device, or it can be divided and performed by multiple devices.

[0403] Furthermore, if a single step includes multiple processes, those processes can be executed by a single device or shared among multiple devices.

[0404] Furthermore, this technology can also be configured as follows. (1) The first communication device receives a second switching request signal from the first communication device, which is a response to a first switching request signal transmitted to the first communication device from a terminal device connected to the first communication device, and requests that the connection destination be switched from the first communication device to the second communication device. Based on the second switching request signal, the control unit transmits to the terminal device a trigger signal for the terminal device to transmit data, along with a switching response signal in response to switching from the first communication device to the second communication device. A communication device which is the second communication device comprising the above-mentioned equipment. (2) The control unit, Before receiving the second switching request signal, the terminal device receives a transmission request signal requesting the transmission of the switching response signal. The communication device described in (1) above. (3) The control unit, The transmission request signal received from the terminal device is a transmission request signal requesting that the switching response signal be transmitted within the UL communication interruption period. The communication device described in (2) above. (4) The control unit, Before receiving the second switching request signal, the transmission request signal is received from the terminal device using a Multi-Link setup frame or a Roaming Request frame. The communication device described in (3) above. (5) The control unit, Information is received from the terminal device that varies depending on whether or not it possesses an encryption key between the second communication device and the terminal device. The communication device described in (1) above. (6) The control unit, During the UL communication blockage period, notification information regarding the traffic of the aforementioned data is received from the terminal device. The communication device described in (1) above. (7) The control unit, Along with the switching response signal, information regarding the operation after the UL communication interruption period is transmitted to the terminal device. The communication device described in (1) above. (8) The control unit, Along with the switching response signal, the terminal device is provided with information regarding a priority transmission period, which is set as a period during which the terminal device can preferentially transmit the data. The communication device described in (1) above. (9) The control unit, The switching response signal is transmitted to another terminal device different from the aforementioned terminal device. The communication device described in (1) above. (10) The control unit, Information regarding additional UL communication blocking periods is transmitted to the other terminal devices. The communication device described in (9) above. (11) The control unit, The first communication device receives a notification from the first communication device indicating that it has processed the buffered traffic. The communication device described in (1) above. (12) The control unit, The first communication device receives a notification that it has processed the buffered traffic, along with information indicating the buffer status of the terminal device, and / or instruction information instructing the terminal device to perform low-latency transmission. The communication device described in (11) above. (13) A switching request signal is sent to the connected first communication device, requesting that it switch the connection destination from the first communication device to the second communication device. When a control unit receives a trigger signal from the second communication device for transmitting data, along with a switching response signal in response to switching from the first communication device to the second communication device, the control unit transmits the data to the second communication device. A terminal device equipped with the following features. (14) The control unit, Before transmitting the switching request signal, a transmission request signal requesting the transmission of the switching response signal is transmitted to the second communication device. The terminal device described in (13) above. (15) The control unit, The transmission request signal is transmitted to the second communication device, requesting that the switching response signal be transmitted within the UL communication interruption period. The terminal device described in (14) above. (16) The control unit, Before transmitting the switching request signal, the transmission request signal is transmitted to the second communication device using a Multi-Link setup frame or a Roaming Request frame. The terminal device described in (14) above. (17) The control unit, Information that varies depending on whether or not the second communication device possesses the encryption key between the second communication device and the terminal device is transmitted to the second communication device. The terminal device described in (13) above. (18) The control unit, If the transmission of the aforementioned data occurs within the UL communication blockage period, notification information regarding the traffic of the aforementioned data is transmitted to the second communication device. The terminal device described in (13) above. (19) The control unit, Along with the aforementioned switching response signal, information regarding the operation after the UL communication interruption period is received from the second communication device. The terminal device described in (13) above. (20) The control unit, Along with the switching response signal, the terminal device receives from the second communication device information regarding a priority transmission period, which is set as a period during which it can preferentially transmit the data. The terminal device described in (13) above. (twenty one) Receiving a second switching request signal from the first communication device in response to a first switching request signal transmitted to the first communication device from a terminal device connected to the first communication device, which requests that the connection destination be switched from the first communication device to the second communication device, Based on the second switching request signal, the terminal device transmits a trigger signal to transmit data to the terminal device, along with a switching response signal in response to switching from the first communication device to the second communication device. A communication method performed by the second communication device, including the following: (twenty two) To send a switching request signal to the connected first communication device requesting that it switch the connection destination from the first communication device to the second communication device, When a trigger signal for transmitting data is received from the second communication device along with a switching response signal in response to switching from the first communication device to the second communication device, the data is transmitted to the second communication device. A communication method performed by a terminal device, including [the specified method]. [Explanation of Symbols]

[0405] 100 AP 110 Wireless Communication Section 111 Common MAC Processing Unit 112A, 112B Individual MAC Processing Units 113A, 113B Signal Processing Unit 114A, 114B RF section 115A, 115B RF switches 116 Communication Control Unit 117A, 117B processing unit 118A_1, 118A_2, 118B_1, 118B_2 antennas 120 Backhaul Communications Unit 130 Storage section 140 Control Unit 200 STA 210 Wireless Communication Section 211 Common MAC Processing Unit 212A, 212B Individual MAC Processing Units 213A, 213B Signal Processing Unit 214A, 214B RF section 215A, 215B RF Switch 216 Communication Control Unit 217A, 217B Processing Unit 218A_1, 218A_2, 218B_1, 218B_2 antennas 220 Storage section 230 Control Unit

Claims

1. The first communication device receives a second switching request signal from the first communication device, which is a response to a first switching request signal transmitted to the first communication device from a terminal device connected to the first communication device, and requests that the connection destination be switched from the first communication device to the second communication device. Based on the second switching request signal, the control unit transmits to the terminal device a switching response signal in response to switching from the first communication device to the second communication device, along with a trigger signal for the terminal device to transmit data. A communication device which is the second communication device comprising the above-mentioned equipment.

2. The control unit, Before receiving the second switching request signal, the terminal device receives a transmission request signal requesting the transmission of the switching response signal. The communication device according to claim 1.

3. The control unit, The transmission request signal received from the terminal device is a transmission request signal requesting that the switching response signal be transmitted within the UL communication interruption period. The communication device according to claim 2.

4. The control unit, Information is received from the terminal device that varies depending on whether or not it possesses the encryption key between the second communication device and the terminal device. The communication device according to claim 1.

5. The control unit, During the UL communication blockage period, notification information regarding the traffic of the aforementioned data is received from the terminal device. The communication device according to claim 1.

6. The control unit, Along with the aforementioned switching response signal, information regarding the operation after the UL communication interruption period is transmitted to the terminal device. The communication device according to claim 1.

7. The control unit, Along with the switching response signal, the terminal device is provided with information regarding a priority transmission period, which is set as a period during which the terminal device can preferentially transmit the data. The communication device according to claim 1.

8. The control unit, The switching response signal is transmitted to another terminal device different from the aforementioned terminal device. The communication device according to claim 1.

9. The control unit, Information regarding additional UL communication blocking periods is transmitted to the other terminal devices. The communication device according to claim 8.

10. The control unit, The first communication device receives a notification from the first communication device indicating that it has processed the buffered traffic. The communication device according to claim 1.

11. The control unit, The first communication device receives a notification indicating that it has processed the buffered traffic, along with information indicating the buffer status of the terminal device, and / or instruction information instructing the terminal device to perform low-latency transmission. The communication device according to claim 10.

12. A switching request signal is sent to the connected first communication device, requesting that it switch the connection destination from the first communication device to the second communication device. When a control unit receives a trigger signal from the second communication device for transmitting data, along with a switching response signal indicating a switch from the first communication device to the second communication device, the control unit transmits the data to the second communication device. A terminal device equipped with the following features.

13. The control unit, Before transmitting the switching request signal, a transmission request signal requesting the transmission of the switching response signal is transmitted to the second communication device. The terminal device according to claim 12.

14. The control unit, The transmission request signal is transmitted to the second communication device, requesting that the switching response signal be transmitted within the UL communication interruption period. The terminal device according to claim 13.

15. The control unit, Information that varies depending on whether or not the second communication device possesses the encryption key between the second communication device and the terminal device is transmitted to the second communication device. The terminal device according to claim 12.

16. The control unit, If the transmission of the aforementioned data occurs during the UL communication blockage period, notification information regarding the traffic of the aforementioned data is transmitted to the second communication device. The terminal device according to claim 12.

17. The control unit, Along with the aforementioned switching response signal, information regarding the operation after the UL communication interruption period is received from the second communication device. The terminal device according to claim 12.

18. The control unit, Along with the switching response signal, the terminal device receives from the second communication device information regarding a priority transmission period, which is set as a period during which it can preferentially transmit the data. The terminal device according to claim 12.

19. Receiving a second switching request signal from the first communication device in response to a first switching request signal transmitted to the first communication device from a terminal device connected to the first communication device, which requests that the connection destination be switched from the first communication device to the second communication device, Based on the second switching request signal, a switching response signal is transmitted to the terminal device in response to switching from the first communication device to the second communication device, along with a trigger signal for the terminal device to transmit data. A communication method performed by the second communication device, including the following:

20. To send a switching request signal to the connected first communication device requesting that it switch the connection destination from the first communication device to the second communication device, When a trigger signal for transmitting data is received from the second communication device along with a switching response signal indicating a switch from the first communication device to the second communication device, the data is transmitted to the second communication device. A communication method performed by a terminal device, including [the specified method].

Images