Communication device and terminal device

Abstract

A communication device according to the present disclosure comprises a control unit. The control unit performs control to transmit first packet data to a terminal device. The control unit requests the first communication device to transmit second packet data to the terminal device. The control unit notifies the first communication device regarding at least one of first information relating to the second packet data and second information relating to transmission of the second packet data.

Description

Communication devices and terminal devices

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

[0002] In recent years, there has been an increase in environments in which multiple access points (hereinafter also referred to as APs) are installed in various use cases such as homes, offices, and factories, and high-speed, highly reliable Wi-Fi (registered trademark) networks are constructed.

[0003] In this way, in an environment where multiple APs are installed, a terminal device (station or station terminal, hereinafter also referred to as STA) that moves around the vicinity may need to frequently perform handover processing to change the AP to which it is connected.

[0004] If a handover is not accurately determined and a connection with an AP with weak link strength continues, or if the handover process takes a long time, there is a risk that a period during which the STA cannot transmit data will occur. The occurrence of a period during which data transmission is not possible can be a significant hindrance to services in applications that require low-latency and highly reliable data communication.

[0005] As a method for solving this problem, IEEE802.11be / Multi-Link Operation is considering the operation of seamless handover using a defined MLD (Multi-Link Device) Entity.

[0006] In this method, one or more APs on the same network are managed by an MLD entity installed in a control device, and the MLD entity enables the STAs connected to each AP to share a common encryption key.

[0007] This allows neighboring APs to transmit data to the same STA before handover occurs. This period during which multiple APs can transmit data to the STA is called a Transition Phase.

[0008] This transition phase allows the STA to switch the AP to which it is connected without interrupting data communication, even in a situation where the STA is moving around, i.e., even when a handover of the STA is necessary.

[0009] Special Publication No. 2022-546889

[0010] Duncan Ho, et al. "Seamless Roaming for UHR". IEEE 802.11-22 / 1910r0. Nov. 2022.

[0011] As described above, it is assumed that multiple APs transmit data to the same STA during the transition phase. However, it cannot be said that sufficient consideration has been given to how multiple APs transmit data to the same STA.

[0012] For example, there is room for further consideration in order to realize the Transition Phase, such as how to share data among multiple APs.

[0013] Therefore, the present disclosure proposes a mechanism for multiple APs to transmit data to the same STA.

[0014] It should be noted that the above problem or object is merely one of multiple problems or objects that can be solved or achieved by multiple embodiments disclosed in this specification.

[0015] A communication device according to the present disclosure includes a control unit. The control unit controls transmission of first packet data to a terminal device. The control unit requests a first communication device to transmit second packet data to the terminal device. The control unit notifies the first communication device of at least one of first information regarding the second packet data and second information regarding the transmission of the second packet data.

[0016] 1 is a diagram illustrating an example configuration of a communication system according to a proposed technique of the present disclosure. FIG. 1 is a diagram illustrating an overview of handover processing according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating an overview of handover processing according to an embodiment of the present disclosure. FIG. 3 is a diagram illustrating an example configuration of an AP (communication device) according to an embodiment of the present disclosure. FIG. 4 is a block diagram illustrating an example configuration of an STA (terminal device) according to an embodiment of the present disclosure. FIG. 5 is a block diagram illustrating an example configuration of a control device according to an embodiment of the present disclosure. FIG. 6 is a sequence diagram illustrating an example flow of first sharing processing according to an embodiment of the present disclosure. FIG. 7 is a sequence diagram illustrating an example flow of data transmission in a Transition Phase according to an embodiment of the present disclosure. FIG. 8 is a diagram illustrating an example configuration of a Coordination Request frame according to an embodiment of the present disclosure. FIG. 9 is a diagram illustrating an example configuration of a Coordination Response frame according to an embodiment of the present disclosure. FIG. 10 is a diagram illustrating an example of first sharing processing according to an embodiment of the present disclosure. FIG. 11 is a sequence diagram illustrating another example of the first sharing processing according to an embodiment of the present disclosure. FIG. 12 is a sequence diagram illustrating an example flow of second sharing processing according to an embodiment of the present disclosure. FIG. 13 is a sequence diagram illustrating another example flow of second sharing processing according to an embodiment of the present disclosure. FIG. 14 is a diagram illustrating an example configuration of a Coordination Request frame according to an embodiment of the present disclosure. FIG. 1 is a diagram showing an example of a second sharing process according to an embodiment of the present disclosure. FIG. 2 is a diagram showing another example of the second sharing process according to an embodiment of the present disclosure. FIG. 3 is a sequence diagram showing an example of the flow of a third sharing process according to an embodiment of the present disclosure. FIG. 4 is a diagram showing an example of the flow of a fourth sharing process according to an embodiment of the present disclosure. FIG. 5 is a diagram showing an example of a configuration of a Coordination Request frame according to an embodiment of the present disclosure. FIG. 6 is a diagram showing an example of a configuration of a Coordination Response frame according to an embodiment of the present disclosure. FIG. 7 is a diagram showing an example of a fourth sharing process according to an embodiment of the present disclosure. FIG. 8 is a diagram showing another example of the fourth sharing process according to an embodiment of the present disclosure.FIG. 1 is a sequence diagram showing an example of the flow of a fifth sharing process according to an embodiment of the present disclosure. FIG. 2 is a diagram showing an example of a configuration of a Coordination Request frame according to an embodiment of the present disclosure. FIG. 3 is a diagram showing another example of the fifth sharing process according to an embodiment of the present disclosure. FIG. 4 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. FIG. 5 is a block diagram showing an example of a schematic configuration of a smartphone to which the present technology is applied. FIG. 6 is a block diagram showing an example of a schematic configuration of an in-vehicle device to which the present technology is applied. FIG. 7 is a block diagram showing an example of a schematic configuration of a wireless AP to which the present technology is applied.

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0018] Furthermore, in this specification and drawings, similar components of the embodiments may be distinguished by adding at least one different alphabet and / or number after the same reference numeral. However, if there is no need to particularly distinguish between similar components, only the same reference numeral will be used. For example, multiple components having substantially the same functional configuration may be distinguished as necessary, such as a first AP 100A and a second AP 100B. Furthermore, if there is no need to particularly distinguish between the first AP 100A and the second AP 100B, they will simply be referred to as AP 100.

[0019] One or more embodiments (including examples, modifications, and application examples) described below can be implemented independently. However, at least a portion of the embodiments described below may be implemented in appropriate combination with at least a portion of another embodiment. These embodiments may include novel features that are different from one another. Therefore, these embodiments may contribute to solving different purposes or problems and may produce different effects.

[0020] <<1. Introduction>> <1-1. Example of Overall System Configuration> Fig. 1 is a diagram showing an example configuration of a communication system 10 according to the proposed technology of the present disclosure. The communication system 10 in Fig. 1 includes a first AP 100A, a second AP 100B, a STA 200, a control device 300, and a router 400.

[0021] (AP 100) The AP 100 is a device called an access point or a base station. The AP 100 communicates with the STA 200 in accordance with, for example, the Wi-Fi (registered trademark) standard. In the example of FIG. 1 , the AP 100 performs downlink (DL) communication with the STA 200, but the AP 100 may also perform uplink (UL) communication with the STA 200.

[0022] The AP 100 is also connected to an external network (not shown) (for example, the Internet) via a router 400 .

[0023] The connection between the multiple APs 100 and the router 400 is also referred to as a backhaul link, and communication through the backhaul link is also referred to as backhaul communication. The backhaul link is, for example, a wired link.

[0024] The connection between the AP 100 and the STA 200 is also referred to as a fronthaul link, and communication via the fronthaul link is also referred to as fronthaul communication. The fronthaul link is, for example, a wireless link.

[0025] (STA200) The STA200 is a communication device such as a smartphone, a tablet terminal, or a PC (Personal Computer). Alternatively, the STA200 may be a communication device such as an IoT (Internet of Things) device or an MTC (Machine Type Communications) device. The STA200 is a terminal device that connects to the AP100 and performs wireless communication.

[0026] The STA 200 may communicate with multiple APs 100. For example, the STA 200 connects to a first AP 100A and communicates with the first AP 100A. Furthermore, for example, if the communication quality with the first AP 100A deteriorates, the STA 200 performs handover to switch the connection destination to a second AP 100B with higher communication quality.

[0027] As a result, even if the quality of communication with the first AP 100A deteriorates, the STA 200 can continue data transmission by connecting to the second AP 100B.

[0028] The control device 300 manages information used for smooth handover by the STA 200. The control device 300 manages the first AP 100A and the second AP 100B. The control device 300 has, for example, the function of a Roaming AP MLD Entity.

[0029] For example, the control device 300 manages encryption keys and the like used by the STAs 200 connected to multiple APs 100. When the control device 300 functions as a Roaming AP MLD Entity, the control device 300 performs part of the MAC processing of the APs 100 under its control. For example, the control device 300 performs connection processing with the STAs 200 under its control that connect to the APs 100 and generates encryption keys.

[0030] The AP 100 connected to the control device 300 functioning as the Roaming AP MLD is also referred to as an “AP affiliated with the Roaming AP MLD.” The control device 300 functioning as the Roaming AP MLD can manage / control part of the processing of the MAC layer in the AP 100 that belongs to the Roaming AP MLD.

[0031] The AP 100 and the control device 300 are connected by a control link. The control link may be a wireless link or a wired link. In the example of FIG. 1, the control link is a wired link using the same wired cable as the backhaul link. Alternatively, the control link may use a wired cable different from that of the backhaul link.

[0032] The router 400 connects the AP 100 to an external network (not shown).

[0033] Although the communication system 10 has two APs 100 in this example, the number of APs 100 included in the communication system 10 is not limited to two and may be three or more. Furthermore, the number of APs 100 connected to the control device 300 is not limited to two and may be three or more.

[0034] The number of STAs 200 included in the communication system 10 is not limited to one, and may be two or more. One STA 200 may have multiple STA Entities.

[0035] The number of control devices 300 included in the communication system 10 is not limited to one, and may be two or more. Furthermore, when a plurality of control devices 300 are included in the communication system 10, the number of APs 100 belonging to each control device 300 may be different.

[0036] Furthermore, the number of routers 400 included in the communication system 10 is not limited to one, and may be two or more. When a plurality of routers 400 are included in the communication system 10, the number of APs 100 connected to each router 400 may be different. Furthermore, APs 100 connected to different routers 400 may belong to the same control device 300. In this case, the APs 100 belonging to the same control device 300 are connected to each other, for example, by a control link or the like.

[0037] Note that, although the control device 300 has been described here as having the function of a Roaming AP MLD Entity, devices having the function of a Roaming AP MLD Entity are not limited to the control device 300. For example, the AP 100 may have the function of a Roaming AP MLD Entity. One of the multiple APs 100 may have the function of a Roaming AP MLD Entity, or each of the multiple APs 100 may have the function of a Roaming AP MLD Entity.

[0038] When multiple APs 100 each have the function of a Roaming AP MLD Entity, which Roaming AP MLD Entity the AP 100 functions as, in other words, which AP 100 will comprehensively manage the subordinate STAs 200, may be determined by negotiation between the multiple APs 100. Alternatively, the AP 100 that will comprehensively manage the subordinate STAs 200 may be determined depending on whether or not predetermined conditions are met, such as the number of STAs 200 connected to the AP 100 and the performance of the AP 100.

[0039] The control device 300 may manage the first AP 100A and the second AP 100B at all times, or may manage the first AP 100A and the second AP 100B during a predetermined period, such as a transition phase. Here, the first AP 100A and the second AP 100B may transmit the same data to the STA 200 during the transition phase.

[0040] At the timing when this transition phase starts, the control device 300 may acquire information about the STA 200 from the AP 100 (for example, the first AP 100A) to which the STA 200 is connected, and manage the STA 200.

[0041] <1-2. Problem> In a conventional communication system, a connected AP (e.g., a first AP) transmits data to a STA. However, as the STA moves and gradually moves away from the first AP, the quality of the communication link between the first AP and the STA may gradually deteriorate.

[0042] When the link quality deteriorates, data transmission failures occur frequently, throughput decreases, and the quality of communication between the first AP and the STA deteriorates.

[0043] Therefore, when the communication quality deteriorates, the first AP or the STA starts a handover process. Specifically, the STA disconnects the existing connection and establishes a connection with a new AP (e.g., the second AP). That is, the STA executes a handover process to switch the connection destination from the first AP to the second AP.

[0044] In the handover process, the STA performs a disconnection process with the first AP and a connection process with the second AP, and therefore, in the handover process, the STA is required to exchange multiple frames with each of the first AP and the second AP.

[0045] By using Fast Transition standardized in IEEE802.11r, the STA can omit the re-authentication process with the second AP at the handover destination. However, even when using Fast Transition, the STA still needs to exchange multiple frames with the second AP.

[0046] As described above, the first AP or the STA determines whether to perform handover processing. If the handover decision is delayed, the STA will continue communication with the first AP with poor communication quality.

[0047] On the other hand, if the handover decision is made too early, the handover process may be performed frequently. For example, if the STA moves irregularly, the handover process may be performed frequently. This increases the number of frame exchanges between the STA and each of the first AP and the second AP. Furthermore, performing the handover process increases the time during which the STA's communication is interrupted.

[0048] As described above, conventional handover processing results in periods when communication is unavailable, making it unsuitable for environments that require high throughput, low latency, and highly reliable communication.

[0049] Therefore, Seamless Roaming processing has been studied as a method for solving the above-mentioned handover processing problems. In Seamless Roaming processing, in a transition phase, a first AP as a handover source and a second AP as a handover destination transmit data to the same STA.

[0050] In the Transition Phase, the STA performs a connection process with the second AP while communicating with the first AP and the second AP. The Transition Phase continues while the STA and the second AP perform the connection process, in other words, until a connection is established between the STA and the second AP.

[0051] In this way, by providing a transition phase before the STA performs handover processing from the first AP to the second AP, the STA does not need to perform handover processing frequently. Also, the STA can perform handover without interrupting data transmission, and can perform wireless communication while maintaining redundancy.

[0052] Furthermore, the Roaming AP MLD Entity uniformly manages the connection relationships between the APs and STAs to which it belongs, so that the APs (e.g., the first AP and the second AP) that belong to the Roaming AP MLD Entity can omit the reconnection / reauthentication process with the STA when performing handover processing.

[0053] This allows the STA to perform the handover process with fewer frame exchanges than in a conventional handover process that does not include a transition phase. For example, the STA may be able to perform the handover without recognizing that the connection destination has been switched from the first AP to the second AP.

[0054] In the Transition Phase, the first AP is required to process some of the data received from the router and transfer it to the second AP. This is because, in the Transition Phase, if the router transmits data to the STA via the first AP, the data may still be stored in the MAC Table. In other words, in the Transition Phase, there is no guarantee that the router has the function to transfer data to the STA to the first AP and the second AP.

[0055] It is assumed that data transferred from the first AP to the second AP is transmitted as IEEE802.11-compliant frames encapsulated in IP packets. This data (Copied Data) is transmitted from the MAC layer (data processing unit) of the first AP to the MAC layer (data processing unit) of the second AP.

[0056] On the other hand, in order for the second AP to generate a signal to actually transmit to the STA, it is considered that not only Copied Data but also some other information (e.g., a sequence number) is required. However, the types of this information and how to share it have not yet been fully considered. Thus, in the conventional technology, further consideration is required for the mechanism of handover using the transition phase.

[0057] <1-3. Overview of Proposed Technology> Therefore, in an embodiment of the present disclosure, the first AP 100A, to which the STA 200 is connected, requests the second AP 100B to transmit data to the STA 200 and notifies the second AP 100B of information to be used for transmitting the data to the STA 200.

[0058] For example, a first AP 100A (an example of a communication device) transmits first data (e.g., first packet data) to a STA 200 (an example of a terminal device). The first AP 100A requests a second AP 100B (an example of a first communication device) to transmit second data (e.g., second packet data) to the STA 200.

[0059] The first AP 100A notifies the second AP 100B of at least one of first information related to the second data and second information related to the transmission of the second data.

[0060] This allows the second AP 100B to generate second data using at least one of the first information and the second information in accordance with a request from the first AP 100A, and to transmit this second data to the STA 200.

[0061] An overview of handover processing according to an embodiment of the present disclosure will be described using Figures 2 to 5. Figures 2 to 5 are diagrams illustrating an overview of handover processing according to an embodiment of the present disclosure.

[0062] This handover process is executed after the process of transitioning to the Transition Phase is completed among the first AP 100A, the second AP 100B, and the control device 300. The process of transitioning to the Transition Phase is started in response to a request from the first AP 100A or the STA 200 that detects that a condition for transitioning to the Transition Phase, such as a deterioration in communication quality or a decrease in radio wave intensity, is met.

[0063] The criteria for determining whether to transition to the Transition Phase may be lower than the criteria for determining whether to execute a handover in the past. For example, the first AP 100A or the STA 200 determines to execute a handover process when the communication quality falls below a first threshold. On the other hand, the first AP 100A or the STA 200 determines to transition to the Transition Phase when the communication quality falls below a second threshold that is greater than the first threshold.

[0064] In this way, the first AP 100A or the STA 200 determines to transition to the Transition Phase earlier than the timing at which a conventional handover is determined to be performed, thereby enabling the STA 200 to perform a handover while maintaining higher communication quality.

[0065] As shown in FIG. 2, after transitioning to the Transition Phase, the first AP 100A receives data to be transmitted to the STA 200 from the router 400 via the backhaul link.

[0066] 3, the first AP 100A that has received the data exchanges a request / response with the second AP 100B via the backhaul link. For example, the first AP 100A transmits a request (request signal) to the second AP 100B, requesting that the STA 200 transmit data.

[0067] The second AP 100B transmits a response (a response signal) corresponding to the request to the first AP 100A. The response includes, for example, information indicating that data transmission to the STA 200 will be performed, or information indicating that data transmission to the STA 200 will not be performed.

[0068] For example, if the second AP 100B has difficulty storing or saving data addressed to the STA 200, for example, because the reception buffer is equal to or greater than a predetermined threshold, the second AP 100B rejects the transmission of this data.

[0069] The first AP 100A, whose data transmission has been refused, may, for example, wait for a predetermined period of time and then repeatedly request data transmission, or the first AP 100A may perform a conventional handover process.

[0070] For example, the first AP 100A notifies the STA 200 and the control device 300 to perform a conventional handover process. This notification may be sent to the second AP 100B.

[0071] Upon receiving this notification, the STA 200 executes a conventional handover process, for example, a process of disconnecting from the first AP 100A and a process of connecting to the second AP 100B.

[0072] On the other hand, when transmitting data to the STA 200, the second AP 100B acquires, from the first AP 100A, information to be used for transmitting data to the STA 200. This information includes, for example, information about the data and information about the transmission of the data.

[0073] The first AP 100A may transmit this information by including it in the above-mentioned request (request signal), or by including it in a separate signal.

[0074] Assume that a response indicating that data transmission to STA 200 is to be performed is received. In this case, as shown in FIG. 4 , the first AP 100A transmits data to STA 200 via the fronthaul link. The first AP 100A also partially processes the data addressed to STA 200 at the MAC (Media Access Control) layer and transmits the data to the second AP 100B via the backhaul link. Hereinafter, data partially processed at the MAC layer will also be referred to as "Copied Data." The second AP 100B transmits the Copied Data to STA 200.

[0075] When the handover of the STA 200 is completed and the STA 200 is connected to the second AP 100B, the transition phase ends. After that, communication is performed between the second AP 100B and the STA 200, as shown in FIG.

[0076] As described above, in the proposed technology, the first AP 100A requests the second AP 100B to transmit data to the STA 200, and notifies the second AP 100B of information to be used in transmitting this data.

[0077] This allows the second AP 100B to share with the first AP 100A information used for transmitting data to the STA 200, and to transmit data to the STA 200. Therefore, in the Transition Phase, multiple APs 100 can transmit data to the same STA 200.

[0078] Hereinafter, the data frame transmitted from the AP 100 to the STA 200 will be simply referred to as data (DATA) or packet data. Also, the error-detectable unit of data that constitutes the data frame will be referred to as packets (Packets).

[0079] Unless otherwise specified, when the first AP 100A transmits all packets that have been partially processed to the second AP 100B, all of these packets are collectively referred to as "Copied Data." When the first AP 100A transmits some of the packets that have been partially processed to the second AP 100B, these packets are collectively referred to as "Copied Packet(s)."

[0080] 6 is a block diagram showing a configuration example of an AP 100 (communication device) according to an embodiment of the present disclosure. The AP 100 includes a communication unit 110, a backhaul communication unit 120, a storage unit 130, and a control unit 140.

[0081] (Communication Unit 110) The communication unit 110 is a wireless communication unit that performs wireless communication with other wireless communication devices (e.g., the STA 200). The communication unit 110 performs communication with the STA 200 in accordance with a wireless LAN (Local Area Network) standard such as Wi-Fi (registered trademark).

[0082] The communication unit 110 includes a data processing unit 111 , a signal processing unit 112 , a wireless interface unit 113 , an amplifier unit 114 , a communication control unit 115 , and a communication storage unit 116 .

[0083] (Communication control unit 115) The communication control unit 115 controls the operation of each unit of the communication unit 110 and the transmission of information between each unit. The communication control unit 115 also controls the transfer of control information and management information to be notified to the STA 200 to the data processing unit 111.

[0084] (Communication storage unit 116) The communication storage unit 116 stores information used by the communication control unit 115. The communication storage unit 116 also stores data packets to be transmitted and received data packets. Here, a transmission buffer (not shown) that stores data packets to be transmitted is included in the communication storage unit 116.

[0085] (Data Processing Unit 111) The data processing unit 111 processes data. For example, the data processing unit 111 performs media access control (MAC) processing.

[0086] During transmission, the data processing unit 111 performs sequence management of the data stored in the communication storage unit 116 and the control information and management information received from the communication control unit 115, and performs encryption processing, etc. During reception, the data processing unit 111 performs decryption processing, and then performs a retransmission request operation and reorder processing.

[0087] This processing may be performed by the control device 300 in the Transition Phase. This processing may also be collectively referred to as common data processing (Upper MAC processing). Note that if the control device 300 always executes the common data processing, the data processing unit 111 may omit execution of this common data processing. In this case, the data processing unit 111 receives data that has been encrypted and has a sequence number added from the control device 300, and executes the following processing (individual data processing, described later) on the received data.

[0088] During transmission, the data processing unit 111 adds a MAC header and an error detection code to the encrypted packet to generate a data frame. The data processing unit 111 also performs a process of concatenating multiple data frames. During reception, the data processing unit 111 performs a process of deconcatenating the MAC header of the received data frame and performs error detection.

[0089] This processing is also performed in the transition phase by the AP 100. This processing is also collectively referred to as individual data processing (Lower MAC processing).

[0090] Here, the data processing unit 111 performs both common data processing and individual data processing, but the processing unit that performs common data processing and individual data processing is not limited to the data processing unit 111. For example, the communication unit 110 may have a processing unit that performs common data processing (common data processing unit) and a processing unit that performs individual data processing (individual data processing unit).

[0091] (Signal Processing Unit 112) The signal processing unit 112 executes processing at the physical layer (PHY). During transmission, the signal processing unit 112 performs encoding, interleaving, modulation, etc. on a data frame, adds a physical header, and generates a symbol stream.

[0092] Upon reception, the signal processing unit 112 analyzes the physical header, and performs demodulation, deinterleaving, decoding, etc. on the symbol stream to generate a data frame. The signal processing unit 112 also estimates complex channel characteristics and performs spatial separation processing as necessary.

[0093] (Radio Interface Unit 113) The radio interface unit 113 includes a transmitting radio interface unit and a receiving radio interface unit. The transmitting radio interface unit performs digital-to-analog signal conversion, filtering, up-conversion, and phase control on the symbol stream to generate a transmission signal.

[0094] The receiving radio interface performs down-conversion, filtering, and analog-to-digital signal conversion on the received signal to generate a symbol stream.

[0095] (Amplification unit 114) The amplification unit 114 has a transmission amplifier and a reception amplifier. The transmission amplifier amplifies the signal input from the wireless interface unit 113 and outputs the amplified signal to the antenna. The reception amplifier amplifies the signal input from the antenna and outputs the amplified signal to the wireless interface unit 113.

[0096] A part of the amplifier 114 may be a component outside the communication unit 110. For example, a part of the amplifier 114 may be included in an antenna. Also, a part of the amplifier 114 may be included in the wireless interface unit 113.

[0097] Although FIG. 6 illustrates the AP 100 having one set of the amplifier 114 and the antenna, that is, a SISO (Single Input Single Output) AP 100, the configuration of the AP 100 is not limited to the example of FIG.

[0098] For example, the AP 100 may have a configuration in which multiple sets of amplifiers 114 and antennas are provided, enabling MIMO (Multiple Input Multiple Output) transmission and reception processing. Alternatively, the AP 100 may have a configuration in which multiple sets of wireless interface units 113, signal processing units 112, and data processing units 111 are provided, enabling parallel communication over multiple links or multiple frequency channels.

[0099] The function that executes the above-mentioned common data processing (part of the data processing unit 111 (common data processing unit)) is also referred to as an "AP MLD Entity." Furthermore, the functions from executing individual data processing to amplifying signals (part of the data processing unit 111 (individual data processing unit), signal processing unit 112, wireless interface unit 113, and amplifier unit 114) are also referred to as an "AP Entity (APx)." The AP 100 may have multiple AP Entities that belong to an AP MLD Entity.

[0100] For example, when the AP 100 functions as a Roaming AP MLD Entity, the AP 100 performs common data processing in the AP MLD Entity for other APs 100. In other words, the AP MLD Entity can function as a Roaming AP MLD Entity.

[0101] 6, the communication unit 110 is implemented in the AP 100 as a single integrated circuit (IC), but the configuration of the communication unit 110 is not limited to this. For example, the communication unit 110 may be configured with multiple ICs. For example, the wireless interface unit 113 and the amplifier unit 114 may be implemented in the AP 100 as an IC separate from the other components of the communication unit 110.

[0102] (Control Unit 140) The control unit 140 is a controller that controls each unit of the AP 100. The control unit 140 may perform part of the operations of the communication control unit 115. The communication control unit 115 and the control unit 140 may be configured as a single block.

[0103] The control unit 140 may be realized by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit).

[0104] In particular, the control unit 140 may be realized by a processor executing various programs stored in a storage device inside the AP 100 using RAM (Random Access Memory) or the like as a working area.

[0105] The control unit 140 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The control unit 140 may also be realized by a GPU (Graphics Processing Unit).

[0106] A CPU, an MPU, an ASIC, an FPGA, and a GPU can all be considered controllers. Note that the control unit 140 may be composed of multiple physically separated objects. For example, the control unit 140 may be composed of multiple semiconductor chips.

[0107] (Storage Unit 130) The storage unit 130 is a data readable / writable storage device such as a dynamic random access memory (DRAM), a static random access memory (SRAM), a flash memory, or a hard disk.

[0108] The storage unit 130 holds information used by the control unit 140 and the communication unit 110. The storage unit 130 may perform part of the operations of the communication storage unit 116. Furthermore, the storage unit 130 and the communication storage unit 116 may be configured as a single block.

[0109] (Backhaul communication unit 120) The backhaul communication unit 120 is a communication unit that communicates with other APs 100 and the router 400. The backhaul communication unit 120 communicates with other APs 100 and the router 400 via wired communication, but may also communicate wirelessly with these devices.

[0110] The backhaul communication unit 120 decodes packets acquired via the backhaul link and outputs them to the communication unit 110 via the control unit 140. The packets output to the communication unit 110 may be packets with the IP header left intact (access point mode), or packets with the IP header decoded and removed by the backhaul communication unit 120 (router mode). In this embodiment, the AP 100 exchanges information with other APs 100 (communicates with other APs 100) via the backhaul communication unit 120.

[0111] The above-mentioned control link (the link between the control device 300 and another AP 100 ) may be formed using the communication unit 110 or may be formed using the backhaul communication unit 120 .

[0112] 7 is a block diagram showing an example of the configuration of a STA 200 (terminal device) according to an embodiment of the present disclosure. The STA 200 includes a communication unit 210, a storage unit 220, and a control unit 230.

[0113] (Communication Unit 210) The communication unit 210 is a wireless communication unit that performs wireless communication with other wireless communication devices (e.g., the AP 100). The communication unit 210 communicates with the AP 100 in accordance with a wireless LAN (Local Area Network) standard such as Wi-Fi (registered trademark).

[0114] The communication unit 210 includes a data processing unit 211 , a signal processing unit 212 , a wireless interface unit 213 , an amplifier unit 214 , a communication control unit 215 , and a communication storage unit 216 .

[0115] (Communication control unit 215) The communication control unit 215 controls the operation of each unit of the communication unit 210 and the transmission of information between each unit. The communication control unit 215 also controls the transfer of control information and management information to be notified to the AP 100 to the data processing unit 211.

[0116] (Communication Storage Unit 216) The communication storage unit 216 stores information used by the communication control unit 215. The communication storage unit 216 also stores data packets to be transmitted and received data packets.

[0117] (Data Processing Unit 211) The data processing unit 211 processes data. For example, the data processing unit 211 performs MAC processing for media access control.

[0118] During transmission, the data processing unit 211 performs sequence management of the data stored in the communication storage unit 216 and the control information and management information received from the communication control unit 215, and performs encryption processing, etc. During reception, the data processing unit 211 performs decryption processing, and then performs a retransmission request operation and reorder processing.

[0119] During transmission, the data processing unit 211 adds a MAC header and an error detection code to the encrypted packet to generate a data frame. The data processing unit 211 also performs a process of concatenating multiple data frames. During reception, the data processing unit 211 performs a process of deconcatenating the MAC header of the received data frame and performs error detection.

[0120] (Signal Processing Unit 212) During transmission, the signal processing unit 212 performs encoding, interleaving, modulation, etc. on the data frame, adds a physical header, and generates a symbol stream. During reception, the signal processing unit 212 analyzes the physical header, and performs demodulation, deinterleaving, decoding, etc. on the symbol stream to generate a data frame. The signal processing unit 212 also estimates complex channel characteristics and performs spatial separation processing as necessary.

[0121] (Radio Interface Unit 213) The radio interface unit 213 includes a transmitting radio interface unit and a receiving radio interface unit. The transmitting radio interface unit performs digital-to-analog signal conversion, filtering, up-conversion, and phase control on the symbol stream to generate a transmission signal.

[0122] The receiving radio interface performs down-conversion, filtering, and analog-to-digital signal conversion on the received signal to generate a symbol stream.

[0123] (Amplification unit 214) The amplification unit 214 has a transmission amplifier and a reception amplifier. The transmission amplifier amplifies the signal input from the wireless interface unit 213 and outputs the amplified signal to the antenna. The reception amplifier amplifies the signal input from the antenna and outputs the amplified signal to the wireless interface unit 213.

[0124] A part of the amplifier unit 214 may be a component outside the communication unit 210. For example, a part of the amplifier unit 214 may be included in an antenna. Also, a part of the amplifier unit 214 may be included in the wireless interface unit 213.

[0125] 7 shows STA 200 having one set of amplifier 214 and antenna, that is, STA 200 of SISO (Single Input Single Output), but the configuration of STA 200 is not limited to the example of FIG.

[0126] For example, STA 200 may have a configuration in which multiple sets of amplifiers 214 and antennas are provided, enabling MIMO (Multiple Input Multiple Output) transmission and reception processing. Alternatively, STA 200 may have a configuration in which multiple sets of radio interface units 213, signal processors 212, and data processors 211 are provided, enabling parallel communication over multiple links or multiple frequency channels.

[0127] 7, the communication unit 210 is implemented in the STA 200 as a single integrated circuit (IC), but the configuration of the communication unit 210 is not limited to this. For example, the communication unit 210 may be configured with multiple ICs. For example, the wireless interface unit 213 and the amplifier unit 214 may be implemented in the STA 200 as an IC separate from the other components of the communication unit 210.

[0128] (Control Unit 230) The control unit 230 is a controller that controls each unit of the STA 200. The control unit 230 may perform part of the operations of the communication control unit 215. The communication control unit 215 and the control unit 230 may be configured as a single block.

[0129] The control unit 230 may be realized by a processor such as a CPU or an MPU, for example. In detail, the control unit 230 may be realized by the processor executing various programs stored in a storage device inside the STA 200 using a RAM or the like as a working area.

[0130] The control unit 230 may be realized by an integrated circuit such as an ASIC or an FPGA. The control unit 230 may also be realized by a GPU.

[0131] A CPU, an MPU, an ASIC, an FPGA, and a GPU can all be considered to be controllers. Note that the control unit 230 may be composed of multiple physically separated objects. For example, the control unit 230 may be composed of multiple semiconductor chips.

[0132] (Storage Unit 220) The storage unit 220 is a data readable / writable storage device such as a DRAM, an SRAM, a flash memory, or a hard disk.

[0133] The storage unit 220 holds information used by the control unit 230 and the communication unit 210. The storage unit 220 may perform part of the operations of the communication storage unit 216. Furthermore, the storage unit 220 and the communication storage unit 216 may be configured as a single block.

[0134] 8 is a block diagram showing a configuration example of a control device 300 according to an embodiment of the present disclosure. The control device 300 includes a communication unit 310, a backhaul communication unit 320, a storage unit 330, and a control unit 340.

[0135] (Communication Unit 310) The communication unit 310 communicates with, for example, the AP 100. The communication unit 310 includes a data processing unit 311, a communication control unit 312, and a communication storage unit 313.

[0136] (Communication Control Unit 312) The communication control unit 312 controls / manages the subordinate AP 100 through the MAC layer. Here, the subordinate AP 100 refers to the AP 100 that is connected via a control link and is the target of control / management through the MAC layer.

[0137] For example, the communication control unit 312 collects information (Layer 2 information) about the STAs 200 connected to the subordinate APs 100. The communication control unit 312 notifies the collected information to APs 100 other than the AP 100 to which it is connected as necessary. This allows the APs 100 belonging to the same group (the same control device 300) to cooperate at the MAC layer.

[0138] In this embodiment, the communication control unit 312 manages at least information such as connection information (encryption keys, etc.) and sequence numbers of the subordinate STAs 200, but the information managed by the communication control unit 312 is not limited to this. For example, the communication control unit 312 may manage whether packet transmission in each STA 200 is successful or not.

[0139] (Communication Storage Unit 313) The communication storage unit 313 stores information used by the communication control unit 312.

[0140] (Data Processing Unit 311) The data processing unit 311 processes data. For example, the data processing unit 311 performs media access control (MAC) processing.

[0141] During transmission, the data processing unit 311 performs sequence management of the data stored in the communication storage unit 313 and the control information and management information received from the communication control unit 312, and performs encryption processing, etc. During reception, the data processing unit 311 performs decryption processing, and then performs a retransmission request operation and reorder processing.

[0142] The data processing unit 311 transmits the processed data to the AP 100. The data processing unit 311 also obtains the data to be processed from the AP 100. The data processing unit 311 communicates with the AP 100 via a backhaul communication unit 320, which will be described later.

[0143] (Control unit 340) The control unit 340 is a controller that controls each unit of the control device 300. The control unit 340 may perform part of the operations of the communication control unit 312. The communication control unit 312 and the control unit 340 may be configured as a single block.

[0144] The control unit 340 may be realized by a processor such as a CPU or an MPU, for example. In detail, the control unit 340 may be realized by the processor executing various programs stored in a storage device inside the control device 300 using a RAM or the like as a work area.

[0145] The control unit 340 may be realized by an integrated circuit such as an ASIC or an FPGA. The control unit 340 may also be realized by a GPU.

[0146] A CPU, an MPU, an ASIC, an FPGA, and a GPU can all be considered to be controllers. Note that the control unit 340 may be composed of multiple physically separated objects. For example, the control unit 340 may be composed of multiple semiconductor chips.

[0147] The control unit 340 controls and manages the APs 100 on the same network via the network layer and application layer. The control unit 340 collects, for example, information (information at Layer 3 or higher) on the STAs 200 connected to the APs 100 under its control. The control unit 340 also collects performance information such as data transmission throughput / delay, and load information on the APs 100 under its control.

[0148] The control unit 340 uses the collected information to optimize network information including the AP 100 to which the STA 200 is connected. The control unit 340 may also make a final decision on handover processing via the communication control unit 312. In other words, the control unit 340 may decide whether or not to execute handover of the STA 200.

[0149] Whether or not the STA 200 executes handover may be determined by the STA 200 itself, the AP 100 of the handover destination, or the AP 100 of the handover source.

[0150] (Storage Unit 330) The storage unit 330 is a data readable / writable storage device such as a DRAM, an SRAM, a flash memory, or a hard disk.

[0151] The storage unit 330 holds information used by the control unit 340 and the communication unit 310. The storage unit 330 may perform part of the operations of the communication storage unit 313. Furthermore, the storage unit 330 and the communication storage unit 313 may be configured as a single block.

[0152] (Backhaul communication unit 320) The backhaul communication unit 320 is a communication unit that communicates with the AP 100. The backhaul communication unit 320 communicates with the AP 100 via wired communication, but may also communicate with the AP 100 wirelessly.

[0153] Backhaul communication unit 320 decodes packets acquired via the backhaul link and outputs the packets to communication unit 310 via control unit 340. Here, the packets output to communication unit 310 may be packets with the IP header left intact (access point mode), or packets with the IP header decoded and removed by backhaul communication unit 320 (router mode).

[0154] The above-mentioned control link (the link between the control device 300 and the AP 100) may be formed using the communication unit 310. In this case, the communication unit 310 has, for example, a signal processing unit, a wireless interface unit, an amplifier unit, a wireless processing unit (not shown) such as an antenna, and performs wireless communication with the AP 100.

[0155] <<3. Examples of Sharing Process>> As described above, in the communication system 10 according to this embodiment, the STA 200 performs handover depending on the communication quality between the AP 100 and the STA 200. In the communication system 10, a sharing process for sharing data between the APs 100 is executed in the Transition Phase. Below, examples of first to fifth sharing processes performed in the communication system 10 will be described.

[0156] <3-1. First Sharing Process Example> (Flow of First Sharing Process) Fig. 9 is a sequence diagram showing an example of the flow of the first sharing process according to an embodiment of the present disclosure. Fig. 9 shows an example in which the STA 200 connected to the first AP 100A switches (hands over) its connection to the second AP 100B. Also, in Fig. 9, communication via a fronthaul link is indicated by a dashed line, and communication via a backhaul link is indicated by a dashed line.

[0157] As shown in Fig. 9, while the STA 200 is connected to the first AP 100A, data is transmitted between the first AP 100A and the STA 200. In the example of Fig. 9, the first AP 100A transmits data (DATA) to the STA 200 and receives a response signal (Block Ack (Acknowledge), hereinafter also simply referred to as BA) in response to the data from the STA 200.

[0158] Although FIG. 9 shows an example in which the first AP 100A transmits data to the STA 200, the STA 200 may transmit data to the first AP 100A.

[0159] When an index indicating communication quality, such as radio wave intensity or packet loss rate, satisfies a predetermined condition in communication with the STA 200, the first AP 100A notifies the control device 300 of the possibility of handover processing.

[0160] The predetermined condition may be when an index indicating communication quality has deteriorated to a certain threshold or below, when the deterioration of the index indicating communication quality has continued for a predetermined period, etc. In addition to these conditions, for example, when movement of the STA 200 is detected, the first AP 100A may notify the control device 300 of the possibility of handover processing.

[0161] Instead of the first AP 100A notifying the control device 300 of the possibility of handover processing, the STA 200 may notify the control device 300. In this case, the STA 200 notifies the control device 300 of the possibility of handover processing via the first AP 100A.

[0162] This notification of the possibility of handover processing may be a notification of a request signal requesting an operation for handover processing (e.g., transition to the Transition Phase), or may be a notification of information for determining whether to execute handover processing (or transition to the Transition Phase), such as an index of communication quality or movement of STA 200.

[0163] Upon receiving this notification, the control device 300 notifies the first AP 100A and the second AP 100B of a Transition Set Request frame (for example, an example of a request signal) at time t01.

[0164] The control device 300 uses this frame to notify the first AP 100A and the second AP 100B of at least one of the following information: AP information regarding the AP 100 that is requested to participate in the Transition Phase STA information regarding the STA 200 that may be subject to handover Connection information Phase information regarding the Transition Phase

[0165] The AP information includes information about APs 100 that may participate in the Transition Phase, such as the first AP 100A as the handover source and one or more APs 100 (e.g., the second AP 100B) that are candidate handover destinations. The AP information includes, for example, identifier information of the APs 100 that may participate in the Transition Phase.

[0166] The STA information includes information about the STA 200 that may be subject to handover. The STA information includes, for example, identifier information of the STA 200. The connection information includes information such as an encryption key.

[0167] The information about the transition phase includes, for example, information about the transition phase, such as the maximum duration of the transition phase.

[0168] The first AP 100A and the second AP 100B, which have received the Transition Set Request frame, notify the control device 300 of a Transition Set Response frame at time t02.

[0169] The Transition Set Response frame is a response frame to the Transition Set Request frame, and includes information (for example, a flag) indicating whether or not participation in the Transition Phase is permitted.

[0170] Here, it is assumed that both the first AP 100A and the second AP 100B participate in the Transition Phase, but the second AP 100B may refuse to participate in the Transition Phase.

[0171] For example, the second AP 100B may refuse to participate in the Transition Phase if it determines that it does not have enough capacity to transmit data to the STA 200 under the control of the first AP 100A. For example, if the second AP 100B has priority traffic, it determines that it does not have enough capacity to transmit data to the STA 200 under the control of the first AP 100A.

[0172] Alternatively, if the buffer of the second AP 100B is filled to a predetermined threshold or more with packets transmitted to the STA 200 under its control, the second AP 100B may determine that it does not have room to transmit data to the STA 200 under the control of the first AP 100A.

[0173] Although the Transition Set Request frame includes connection information such as an encryption key, the connection information may be notified to the AP 100 in a frame separate from the Transition Set Request frame. For example, the control device 300 may notify the AP 100 participating in the Transition Phase of the connection information.

[0174] The connection information includes confidential information such as an encryption key. Therefore, by the control device 300 notifying the AP 100 participating in the Transition Phase of the connection information, it is possible to make it difficult for the confidential information to leak to the outside. Note that the connection information may be encrypted before being notified to the AP 100.

[0175] Although the second AP 100B is assumed to be one candidate for the handover destination here, there may be two or more candidate for the handover destination. In this case, the control device 300 transmits a Transition Set Request frame to all candidate for the handover destination.

[0176] The control device 300 can determine the candidate handover destinations based on, for example, the location of the STA 200, the communication quality between the STA 200 and the AP 100, and the like.

[0177] Furthermore, if the second AP 100B, in other words, all APs 100 that are candidates for handover destination, refuse to participate in the Transition Phase, the control device 300 may be configured to send a Transition Set Request frame again after a predetermined period of time has elapsed.

[0178] Until the transition phase is set, the STA 200 maintains the connection with the first AP 100A, or the STA 200 may perform a conventional handover process.

[0179] When the Transition Set Response frame is notified to the control device 300, the Transition Phase is initiated. Note that in Fig. 9, the period during which the STA 200 is connected to the first AP 100A (hereinafter also referred to as the first connection period) ends before the Transition Set Request frame is notified to the AP 100, but the end of the first connection period is not limited to this. For example, the first connection period may continue until the Transition Phase is initiated.

[0180] Assume that the transition phase is started and the first AP 100A acquires data to be transmitted to the STA 200. In this case, the first AP 100A secures the transmission right and sets a period during which continuous transmission is possible (TXOP: Transmission Opportunity).

[0181] At time t03 included in the TXOP, the first AP 100A transmits data to the STA 200. In addition, the first AP 100A transmits a Coordination Request frame to the second AP 100B participating in the Transition Phase.

[0182] The Coordination Request frame includes request information related to the AP 100 (here, the second AP 100B) requesting transmission of Copied Data to the STA 200. The Coordination Request frame also includes shared information (an example of first information) related to data to be transmitted by the first AP 100A to the STA 200. The Coordination Request frame also includes transmission information (an example of second information) for transmitting data to be transmitted by the second AP 100B to the STA 200.

[0183] The shared information includes, for example, information for the first AP 100A and the second AP 100B to share data to be transmitted to the same STA 200. The transmission information includes, for example, information for the second AP 100B to generate a data frame of data to be transmitted to the STA 200.

[0184] In this way, the Coordination Request frame can also be said to be a notification frame that notifies the STA 200 of information for transmitting data to the STA 200 in the Transition Phase. The Coordination Request frame will be described in detail later.

[0185] Upon receiving the Coordination Request frame, the second AP 100B transmits a Coordination Response frame as a response signal to the first AP 100A at time t04. The Coordination Response frame includes information (a flag) indicating whether data transmission to the STA 200 is possible. The Coordination Response frame will be described in detail later.

[0186] Here, it is assumed that the second AP 100B transmits a Coordination Response frame including information indicating that data transmission to the STA 200 is possible to the first AP 100A.

[0187] On the other hand, if the second AP 100B determines that it does not have enough capacity to transmit data to the STA 200 under its control, it may reject the data transmission to the STA 200. For example, if the second AP 100B has priority traffic, it may determine that it does not have enough capacity to transmit data to the STA 200 under the control of the first AP 100A. Here, the STA 200 under the control of the second AP 100B is the STA 200 that is connected to the second AP 100B but not connected to the first AP 100A. The STA 200 under the control of the second AP 100B is different from the STA 200 (under the control of the first AP 100A) shown in FIG. 1, in other words, different from the STA 200 connected to the first AP 100A. The STA 200 under the control of the second AP 100B is the STA 200 not shown in FIG. 1.

[0188] Alternatively, if the buffer of the second AP 100B is filled to a predetermined threshold or more with packets transmitted to the STA 200 under its control, the second AP 100B may determine that it does not have room to transmit data to the STA 200 under the control of the first AP 100A.

[0189] It should be noted that although it has been assumed here that the timing at which the first AP 100A transmits data to the STA 200 and the timing at which it transmits a Coordination Request frame to the second AP 100B are the same, these timings may be different.

[0190] For example, in a fronthaul link, frame exchange such as RTS (Request to Send) / CTS (Clear to Send) may be performed prior to data transmission to the STA 200. In this case, the AP 100 may exchange a Coordination Request frame / Coordination Response frame during the period in which the RTS / CTS frame exchange is performed.

[0191] Alternatively, the exchange of the Coordination Request frame / Coordination Response frame may be performed after a certain period of time has elapsed since the first AP 100A transmitted data to the STA 200.

[0192] Also, although it has been described here that the Coordination Request frame / Coordination Response frame is transmitted via a backhaul link, the link over which these frames are transmitted is not limited to a backhaul link.

[0193] For example, these frames may be transmitted via a fronthaul link. In this case, the first AP 100A cannot simultaneously transmit these frames and data addressed to the STA 200. Therefore, these frame exchanges may be performed before the transmission of data addressed to the STA 200. For example, these frame exchanges may be performed so as to be completed by time t03.

[0194] 9, the first AP 100A and the second AP 100B directly exchange Coordination Request frames and Coordination Response frames. The Coordination Request frames and Coordination Response frames directly exchanged between the APs 100 may be acquired by the control device 300. The control device 300 may use these acquired frames to update information related to the STA 200 or determine context information.

[0195] Alternatively, the exchange of Coordination Request frames / Coordination Response frames between the APs 100 may be performed via the control device 300. For example, the first AP 100A and the second AP 100B may exchange Coordination Request frames / Coordination Response frames via the control device 300.

[0196] The first AP 100A, which has received the Coordination Response frame, generates Copied Data and transmits it to the second AP 100B via the backhaul link at time t05. The second AP 100B stores the received Copied Data in its own buffer as is.

[0197] Here, the copied data is data that has been subjected to some processing, such as encryption, up to the MAC layer by the first AP 100A, as described above. The copied data includes all packets included in the data that the first AP 100A transmits to the STA 200.

[0198] In the example of FIG. 9, the first AP 100A acquires the BA from the STA 200 at time t06 after transmitting the copied data to the second AP 100B.

[0199] Thereafter, when the second AP 100B acquires a transmission opportunity (TXOP), it generates a data frame using the stored Copied Data and transmission information (for example, Context information) included in the Coordination Request frame.

[0200] For example, the second AP 100B stores a sequence number and control information in the MAC header of the data frame based on the context information of the Coordination Request frame. Meanwhile, the second AP 100B determines information related to its own transmission status and stores the determined information in the MAC header of the data frame. Here, the information related to its own transmission status may include at least one of data transmission time and address information, for example.

[0201] In the example of FIG. 9, the second AP 100B transmits data (an example of second packet data) to the STA 200 at time t07, and subsequently receives a BA from the STA 200 at time t08.

[0202] The first AP 100A and the second AP 100B repeatedly perform the above-described operations while the Transition Phase continues. The duration of the Transition Phase is set by a Transition Set Request frame. For example, the duration of the Transition Phase is the maximum duration included in the Transition Set Request frame.

[0203] The first AP 100A repeatedly transmits data to the STA 200, exchanges Coordination Request frames / Coordination Response frames, and sends Copied Data until the Transition Phase ends.

[0204] The second AP 100B repeatedly exchanges Coordination Request frames / Coordination Response frames and transmits data to the STA 200 until the Transition Phase ends.

[0205] When the transition phase set by the control device 300 ends, a handover process is executed to switch the connection destination of the STA 200 from the first AP 100A to the second AP 100B.

[0206] Alternatively, if the communication quality between the first AP 100A and the STA 200 deteriorates, the handover process is executed even before the Transition Phase set by the control device 300 ends.

[0207] 9, as part of this handover process, the control device 300 transmits a Handover Request frame to the first AP 100A and the second AP 100B at time t09. In response, the first AP 100A and the second AP 100B transmit a Handover Response frame to the control device 300 at time t10.

[0208] After the exchange of the Handover Request frame / Handover Response frame, a connection switching process from the first AP 100A or the second AP 100B to the STA 200 is performed, thereby completing the handover process.

[0209] The second AP 100B can continue to use the information about the STA 200 acquired from the control device 300 from the transition phase. Therefore, the second AP 100B can perform the connection switching process with fewer frame exchanges.

[0210] When the handover process is completed, the STA 200 connects to the second AP 100B. During the period in which the STA 200 is connected to the second AP 100B (hereinafter also referred to as the second connection period), data is transmitted from the second AP 100B to the STA 200. Also, during the second connection period, the second AP 100B receives a BA, which is a response signal to the data transmission, from the STA 200.

[0211] Note that this Handover Request frame may be transmitted from any one of the first AP 100A, the second AP 100B, and the STA 200 instead of from the control device 300.

[0212] Furthermore, when it is clear that a handover process will be performed, such as when the maximum duration of the Transition Phase has elapsed, the exchange of the Handover Request frame / Handover Response frame may be omitted. In this case, for example, the first AP 100A or the second AP 100B performs the connection switching process without exchanging the Handover Request frame / Handover Response frame.

[0213] Although the description has been given here using an example in which there is one second AP 100B, there may be two or more second APs 100B. In this case, for example, the control device 300 selects one of the two or more second APs 100B as the AP 100 to be requested to participate in the Transition Phase.

[0214] The control device 300 may select the AP 100 to be requested to participate in the Transition Phase based on, for example, the communication quality between the STA 200 and the second AP 100B, the position of the STA 200, the direction and speed of movement of the STA 200, and the like.

[0215] If the selected AP 100 refuses to participate in the Transition Phase, the control device 300 may select an AP 100 to request participation in the Transition Phase from among the remaining second APs 100B.

[0216] Alternatively, for example, the control device 300 may request two or more second APs 100B to participate in the Transition Phase. That is, the control device 300 may request two or more second APs 100B to participate in the Transition Phase.

[0217] When two or more second APs 100B participate in the Transition Phase, the first AP 100A may request two or more second APs 100B to transmit data to the STA 200. In this case, the first AP 100A transmits a Coordination Request frame to two or more second APs 100B.

[0218] The first AP 100A may request data transmission from all of the second APs 100B participating in the Transition Phase, or may request data transmission from some of the second APs 100B.

[0219] Two or more second APs 100B that have received a data transmission request generate a data frame at the timing when they acquire a TXOP, and transmit the generated data frame to the STA 200. That is, the STA 200 receives the same data frame from two or more different second APs 100B.

[0220] Alternatively, if there are two or more second APs 100B participating in the Transition Phase, the first AP 100A may select one of the two or more second APs 100B and request data transmission to the STA 200. In this case, the first AP 100A transmits a Coordination Request frame to the selected second AP 100B.

[0221] In this way, when there are two or more second APs 100B participating in the Transition Phase, the control device 300 transmits a Handover Request frame to any one of the two or more second APs 100B. The second AP 100B to which the Handover Request frame is transmitted, i.e., the handover destination, is determined according to, for example, the result of data transmission in the Transition Phase.

[0222] For example, the control device 300 selects the second AP 100B as the handover destination depending on the communication quality (for example, radio wave intensity, packet loss rate, etc.) between the second AP 100B and the STA 200.

[0223] Next, a detailed example of data transmission in the Transition Phase will be described with reference to Fig. 10. Fig. 10 is a sequence diagram illustrating an example of the flow of data transmission in the Transition Phase according to an embodiment of the present disclosure. Note that a description of the same processes in Fig. 10 as those in Fig. 9 will be omitted.

[0224] In FIG. 10, the AP 100 transmits data (packet data) including four packets (packet #1 to packet #4).

[0225] For example, at time t03 of the TXOP of the first AP 100A, the first AP 100A transmits packet data including a header ("H" in FIG. 10) and four packets (packet #1 to packet #4) to the STA 200. Furthermore, at time t05, the first AP 100A transmits all copied packets (packet #1 to packet #4) to the second AP 100B.

[0226] Here, it is assumed that STA 200 receives the data transmitted at time t03, but fails to receive packets #2 and #4 at this time. In this case, STA 200 transmits a BA indicating that it failed to receive packets #2 and #4 to the first AP 100A at time t06.

[0227] At time t07 of the TXOP of the second AP 100B, the second AP 100B transmits packet data including a header ("H" in FIG. 10) and four packets (packet #1 to packet #4) to the STA 200.

[0228] As a result, even if the quality of communication between the STA 200 and the first AP 100A deteriorates and the STA 200 fails to receive data transmitted by the first AP 100A, the STA 200 can acquire data from the second AP 100B. In this way, the STA 200 can switch (handover) the AP 100 while further shortening the disconnection period of data communication.

[0229] (Frame Configuration Example) (Coordination Request Frame) Fig. 11 is a diagram illustrating a configuration example of a Coordination Request frame according to an embodiment of the present disclosure. Fig. 11 illustrates a Coordination Request frame based on the Action frame of IEEE 802.11.

[0230] However, the Coordination Request frame according to this embodiment is not limited to a frame configuration based on the Action frame of IEEE 802.11. The Coordination Request frame may have any configuration as long as it includes at least one of the following pieces of information:

[0231] Furthermore, although FIG. 11 illustrates an example in which the Coordination Request frame is transmitted as a MAC Frame, the Coordination Request frame may be transmitted in a format other than a MAC Frame, such as a TCP / IP Frame.

[0232] The Coordination Request frame shown in FIG. 11 includes "Frame Control", "Duration", "RA (Receiver Address)", "TA (Transmitter Address)", "Frame Body", and "FCS (Frame Check Sequence)".

[0233] The Frame Body includes "Category", "MAP Action", "Dialog Token", "Transition AP ID", "STA ID", "Copied DATA Info", "Context Info", and "Packets Flush flag".

[0234] In the "Category" of the Frame Body, information indicating the type of Action frame (Coordination Request frame) is stored. In this embodiment, it is assumed that information indicating a MAP (Multi-AP) Action frame is stored.

[0235] Information indicating the type of the MAP Action frame is stored in "MAP Action." For example, in the case of a Coordination Request, "0" is stored in "MAP Action."

[0236] "Dialog Token" stores information indicating a processing number. "Transition AP ID" stores identifier information for identifying the second AP 100B to which a data transmission request to the STA 200 is made, in other words, the destination of the Coordination Request frame. "Transition AP ID" may include identifier information for multiple second APs 100B.

[0237] "STA ID" stores identifier information for identifying the STA 200 to which data is to be transmitted. For example, "STA ID" stores the MAC address of the STA 200. Alternatively, if the second AP 100B has an address table, "STA ID" stores index information that specifies a MAC address in the address table.

[0238] "Copied DATA Info" stores information about the transmission of Copied DATA, including "Max Num. of Packets" and "Copied Data Share Timing."

[0239] "Max Num. of Packets" stores information indicating the maximum number of packets to be transmitted. Here, the number of packets included in the data transmitted by the first AP 100A to the STA 200 is stored in "Max Num. of Packets." In the second to fifth sharing processes described below, a number smaller than the number of packets included in the data transmitted by the first AP 100A to the STA 200 may be stored in "Max Num. of Packets."

[0240] Information about the timing of sharing the copied data is stored in "Copied Data Share Timing." The timing of sharing the copied data is, for example, the timing when the first AP 100A transmits the copied data (time t07 in FIG. 9).

[0241] The timing for sharing the Copied Data is, for example, immediately after the first AP 100A receives a Coordination Response frame or after a certain period has elapsed since the reception of the Coordination Response frame. The timing for sharing the Copied Data is immediately after the first AP 100A receives a BA from the STA 200 or after a certain period has elapsed since the reception of the BA.

[0242] The timing for sharing the Copied Data is, for example, immediately after the first AP 100A receives a Coordination Response frame or immediately after it receives a BA, whichever is later (or earlier).

[0243] Here, the BA received from the STA 200 is, for example, the BA received by the first AP 100A at time t06 in FIG.

[0244] The "Context Info" in the Frame Body contains information used to generate a data frame from Copied Data. Context Info includes the "Start SN (Sequence Number)", "SN Bitmap", "ACI", and "QoS (Quality of Service) / HT Control".

[0245] "Start SN" stores information indicating the first sequence number of the packets included in the data frame. "SN Bitmap" stores bitmap information indicating the sequence numbers of the packets included in the data frame.

[0246] "ACI" stores information about the access category. "QoS / HT Control" stores information about control information to be included in the MAC header.

[0247] For example, the shared information may be information stored in "Copied Data Info," and the transmission information may be information stored in "Context Info."

[0248] The "Packets Flush flag" in the Frame Body contains information indicating how the first AP 100A will handle the data (or packets contained in the data) after transmitting the Copied Data. For example, assume that "Y" (Yes) is stored in the "Packets Flush flag." In this case, after transmitting the Copied Data to the second AP 100B, the first AP 100A deletes the packets contained in the data from its own buffer, regardless of whether the data was successfully transmitted to the STA 200.

[0249] The additional information of the "Packets Flush flag" may include information indicating the timing (that is, retention period information) at which the first AP 100A erases the data (or packets included in the data).

[0250] (Coordination Response Frame) Fig. 12 is a diagram illustrating a configuration example of a Coordination Response frame according to an embodiment of the present disclosure. Fig. 12 illustrates a Coordination Response frame based on the Action frame of IEEE802.11.

[0251] However, the Coordination Response frame according to this embodiment is not limited to a frame configuration based on the Action frame of IEEE 802.11. The Coordination Response frame may have any configuration as long as it includes at least one of the following pieces of information:

[0252] Furthermore, although FIG. 12 illustrates an example in which the Coordination Response frame is transmitted as a MAC Frame, the Coordination Response frame may be transmitted in a format other than a MAC Frame, such as a TCP / IP Frame.

[0253] The Coordination Response frame shown in FIG. 12 includes "Frame Control", "Duration", "RA (Receiver Address)", "TA (Transmitter Address)", "Frame Body", and "FCS (Frame Check Sequence)".

[0254] The Frame Body includes "Category", "MAP Action", "Dialog Token" and "Transition flag".

[0255] In the "Category" of the Frame Body, information indicating the type of Action frame (Coordination Request frame) is stored. In this embodiment, it is assumed that information indicating a MAP (Multi-AP) Action frame is stored.

[0256] "MAP Action" stores information indicating the type of MAP Action frame. For example, in the case of a Coordination Response, "01" is stored in "MAP Action." "Dialog Token" stores information indicating a processing number.

[0257] The "Transition flag" stores flag information indicating whether the second AP 100B accepts (allows) the request (request for data transmission to the STA 200) from the first AP 100A.

[0258] The additional information of the "Transition flag" may include information indicating the reason why the second AP 100B does not accept the request from the first AP 100A. The reason for not accepting the request may include the free space in the buffer of the second AP 100B, the presence or absence of priority traffic, etc.

[0259] (Operation of the First AP 100A) Fig. 13 is a diagram illustrating an example of a first sharing process according to an embodiment of the present disclosure. The first sharing process illustrated in Fig. 13 is executed by the first AP 100A that has acquired the TXOP, for example, in the transition phase.

[0260] 13, the first AP 100A starts data transmission to the STA 200 via the fronthaul link (step S101). Next, the first AP 100A transmits a Coordination Request to the second AP 100B (step S102).

[0261] The first AP 100A determines whether or not it has received a Coordination Response with a Transition flag set to Y (Transition flag = Y) from the second AP 100B (step S103). For example, if the second AP 100B allows data transmission to the STA 200, it transmits a Coordination Response with a Transition flag set to Y to the first AP 100A.

[0262] If the first AP 100A does not receive a Coordination Response with a Transition flag of Y (step S103; No), the first AP 100A receives a Block Ack (BA) from the STA 200 (step S104). For example, if the second AP 100B does not allow data transmission to the STA 200, the second AP 100B transmits a Coordination Response with a Transition flag of N to the first AP 100A. In this case, the first AP 100A does not receive a Coordination Response with a Transition flag of Y.

[0263] The first AP 100A, which has received the Block Ack from the STA 200, deletes the successfully transmitted packet (step S105) and ends the process.

[0264] On the other hand, if a Coordination Response with a Transition flag of Y is obtained (Step S103; Yes), the first AP 100A transmits Copied Data to the second AP 100B via the backhaul link (Step S106).

[0265] Next, the first AP 100A receives a Block Ack (BA) from the STA 200 (step S107). The first AP 100A determines whether or not it is possible to erase all packets included in the data transmitted to the STA 200 (step S108). For example, the first AP 100A determines whether or not it is possible to erase all packets based on information stored in the Packets Flush flag of the Coordination Request.

[0266] If all packets can be erased (step S108; Yes), the first AP 100A erases all packets included in the data regardless of whether they can be transmitted (step S109), and ends the process. Here, "irrelevant to whether they can be transmitted" means that it is irrelevant to whether the STA 200 has successfully received the packets. In this case, the first AP 100A erases all packets transmitted to the STA 200 regardless of the contents of the Block Ack (BA).

[0267] If it is not possible to erase all packets (step S108; No), the first AP 100A erases the packets that have been successfully transmitted to the STA 200 in response to a Block Ack (BA) (step S110), and ends the process.

[0268] Although the Coordination Request / Response frame is assumed to be transmitted over a backhaul link here, the Coordination Request / Response frame may be transmitted over a fronthaul link as described above. When the Coordination Request / Response frame is transmitted over a fronthaul link, data transmission to STA 200 starts after the Coordination Request / Response frame exchange.

[0269] (Operation of the second AP 100B) Fig. 14 is a diagram illustrating another example of the first sharing process according to the embodiment of the present disclosure. The first sharing process illustrated in Fig. 14 is executed by the second AP 100B, for example, in the transition phase.

[0270] As shown in FIG. 14, the second AP 100B receives a Coordination Request from the first AP 100A (step S201).

[0271] Next, the second AP 100B determines whether data transmission to the corresponding STA 200 (STA 200 specified in the Coordination Request) is possible (step S202). For example, the second AP 100B determines whether data transmission to the STA 200 is possible depending on whether there is a margin for data transmission to the STA 200. The second AP 100B determines whether there is a margin for data transmission to the STA 200 depending on the free space in its own buffer, the presence or absence of priority traffic, etc.

[0272] If it is determined that data transmission to the STA 200 is not possible (step S202; No), the second AP 100B transmits a Coordination Response with a Transition flag set to N to the first AP 100A (step S203), and ends the process.

[0273] On the other hand, if it is determined that data transmission to the STA 200 is possible (step S202; Yes), the second AP 100B transmits a Coordination Response with a Transition flag set to Y to the first AP 100A (step S204).

[0274] Next, the second AP 100B acquires the copied data from the first AP 100A (step S205).

[0275] After that, the second AP 100B that has acquired the TXOP generates a data frame to be transmitted to the STA 200 based on the previously acquired Context information (step S206). The Contest information is transmitted, for example, included in Context Info of a Coordination Request.

[0276] After generating the data frame, the second AP 100B starts transmitting data to the STA 200 via the fronthaul link (step S207).

[0277] Although the Coordination Request / Response frame is transmitted over a backhaul link here, the Coordination Request / Response frame may be transmitted over a fronthaul link as described above.

[0278] Furthermore, as described above, when the second AP 100B transmits data to the STA 200 via the fronthaul link, the second AP 100B receives a BA in response from the STA 200. This BA includes information on whether or not the transmission of the packet included in the data was successful.

[0279] The second AP 100B may transmit this capability information to the first AP 100A. For example, if the second AP 100B is not able to erase all packets included in the data transmitted by the first AP 100A to the STA 200, the second AP 100B may transmit this capability information to the first AP 100A.

[0280] If it is not possible to erase all packets included in the data transmitted to the STA 200, the first AP 100A retains packets that were not successfully transmitted among the packets included in the data transmitted to the STA 200.

[0281] By the second AP 100B transmitting this success / failure information to the first AP 100A, the first AP 100A can know which packets included in the data transmitted to the STA 200 were successfully transmitted by the second AP 100B.

[0282] The first AP 100A deletes from its own buffer the packets that the second AP 100B has successfully transmitted. Note that, for example, the second AP 100B can check whether it is possible to erase all packets included in the data transmitted by the first AP 100A to the STA 200 by checking the Packets Flush flag in the Coordination Request.

[0283] As described above, in the first sharing process, Coordination Request / Response frames are exchanged between the first AP 100A and the second AP 100B. In this manner, pre-negotiation and information exchange for data transmission to the STA 200 are performed between the first AP 100A and the second AP 100B.

[0284] After determining whether or not the first AP 100A can participate in the transition operation (transition phase), the first AP 100A notifies the second AP 100B of a group of information required to generate a data frame to be transmitted.

[0285] This mechanism allows multiple APs 100 (first AP 100A and second AP 100B) to transmit data to the same STA 200 in the transition phase.

[0286] <3-2. Second Sharing Process Example> In the first sharing process described above, the first AP 100A copies all packets to be transmitted to the STA 200 and transmits them to the second AP 100B. In addition, the second AP 100B transmits all acquired Copied Packets to the STA 200.

[0287] On the other hand, improvement of communication efficiency is required in the communication system 10. Therefore, in the second sharing process, the second AP 100B transmits a part of all acquired Copied Packets to the STA 200, thereby improving communication efficiency.

[0288] (Flow of Second Sharing Process) Fig. 15 is a sequence diagram showing an example of the flow of the second sharing process according to an embodiment of the present disclosure. Fig. 15 shows an example of the flow of the second sharing process in the Transition Phase. Note that in Fig. 15, descriptions of the same processes as in Fig. 10 will be omitted.

[0289] In the example of FIG. 15, the first AP 100A, which has acquired BA from the STA 200 at time t06, transmits SN information (SN Info. in FIG. 15) to the second AP 100B at time t11.

[0290] The SN information includes, for example, BA information acquired at time t06 from the STA 200. Specifically, the SN information includes, for example, bitmap information indicating whether the packet transmitted from the first AP 100A to the STA 200 was successfully transmitted.

[0291] The first AP 100A transmits the SN information to the second AP 100B, thereby requesting the second AP 100B to retransmit the packet that the STA 200 failed to receive. In response to this retransmission request, the second AP 100B transmits the retransmitted packet to the STA 200.

[0292] For example, when the second AP 100B acquires the TXOP, it generates a data frame to be transmitted to the STA 200 based on the SN information, Copied Packets, and Context information previously acquired through the Coordination Request.

[0293] Specifically, the second AP 100B identifies packets to be retransmitted based on the SN information and the information stored in the Start SN / SN Bitmap in the Context information. The second AP 100B selects packets to be retransmitted from the Copied Packets and generates a data frame including the selected packets.

[0294] After generating the data frame, the second AP 100B transmits the generated data frame to the STA 200 at time t12. Thereafter, the second AP 100B obtains a BA from the STA 200 at time t13.

[0295] Here, a second sharing process in which the first AP 100A requests two or more second APs 100B to transmit data to the STA 200 will be described.

[0296] In this case, the second AP 100B may notify the other second AP 100B of whether or not the packet retransmission to the STA 200 was successful (e.g., SN information). For example, the second AP 100B notifies the other second AP 100B of the SN information.

[0297] The second AP 100B may transmit to the other second AP 100B via the first AP 100A the success or failure of packet retransmission to the STA 200. It is also assumed that the other second AP 100B has also acquired the SN information transmitted by the first AP 100A to the second AP 100B at time t11.

[0298] In this case, for example, the second AP 100B, which acquires the TXOP next and transmits data to the STA 200, generates a data frame using all the acquired SN information and transmits it to the STA 200.

[0299] Specifically, the second AP 100B identifies packets that the STA 200 has failed to receive from all the SN information, and generates and transmits a data frame including the identified packets.

[0300] For example, if the STA 200 has successfully received all packets, the second AP 100B may not transmit data to the STA 200.

[0301] This allows the communication system 10 to further improve communication efficiency.

[0302] 16 is a sequence diagram illustrating another example of the flow of the second sharing process according to an embodiment of the present disclosure. In FIG. 16, another example of the flow of the second sharing process in the Transition Phase is illustrated. In FIG. 16, the second AP 100B does not acquire SN information from the first AP 100A, but receives a BA transmitted by the STA 200 to the first AP 100A.

[0303] In the example of FIG. 16, at time t06, the BA transmitted by the STA 200 is acquired by both the first AP 100A and the second AP 100B.

[0304] When the second AP 100B acquires the TXOP, it generates a data frame to be transmitted to the STA 200 based on the context information previously acquired from the BA, Copied Packets, and Coordination Request transmitted by the STA 200.

[0305] Specifically, the second AP 100B identifies a packet to be retransmitted based on the BA transmitted by the STA 200 and the information stored in the Start SN / SN Bitmap in the Context information. The second AP 100B selects a packet to be retransmitted from the Copied Packets and generates a data frame including the selected packet.

[0306] After generating the data frame, the second AP 100B transmits the generated data frame to the STA 200 at time t14. Thereafter, the second AP 100B obtains a BA from the STA 200 at time t15.

[0307] In this way, by acquiring the BA addressed to the first AP 100A from the STA 200, the second AP 100B can identify the packet to be retransmitted earlier than by acquiring the SN information from the first AP 100A.

[0308] In order to acquire a BA addressed to the first AP 100A, the second AP 100B is required to be in a state in which it can reliably acquire a signal when the STA 200 transmits the BA. It is desirable for the second AP 100B to determine whether it can acquire a BA addressed to the first AP 100A by exchanging Coordination Request / Response frames.

[0309] Furthermore, the STA 200 is required to generate a BA for data transmitted by the first AP 100 A so that it can be received by the second AP 100 B. For example, it is desirable for the STA 200 to generate a BA that can be received by both the first AP 100 A and the second AP 100 B, such as by adding the second AP 100 B to the destination address of the BA.

[0310] (Frame Configuration Example) Here, a description will be given of the frame configuration of the Coordination Request / Response frame when the second AP 100B acquires a BA addressed to the first AP 100A. Note that the configuration of the Coordination Request / Response frame when the second AP 100B acquires SN information from the first AP 100A is the same as the frame configuration described in the first sharing process, and therefore description thereof will be omitted.

[0311] (Coordination Request frame) Fig. 17 is a diagram illustrating a configuration example of a Coordination Request frame according to an embodiment of the present disclosure. Note that, among the configurations of the Coordination Request frame in Fig. 17, the description of the configurations that are the same as those of the Coordination Request frame in Fig. 11 will be omitted.

[0312] The Coordination Request frame shown in Fig. 17 differs from the Coordination Request frame shown in Fig. 11 in that "Block Ack Info" is included in Copied Data Info. "Block Ack Info" stores BA information related to a BA (Block Ack) transmitted from STA 200. The BA information includes, for example, information related to the transmission timing at which STA 200 transmits the BA, information indicating the destination / destination addresses of the BA, etc.

[0313] (Coordination Response frame) Fig. 18 is a diagram illustrating a configuration example of a Coordination Response frame according to an embodiment of the present disclosure. Note that, among the configurations of the Coordination Response frame in Fig. 18, the description of the configuration that is the same as that of the Coordination Response frame in Fig. 12 will be omitted.

[0314] The Coordination Response frame shown in Fig. 18 differs from the Coordination Response frame shown in Fig. 12 in that a "Block Ack obtainable flag" is included in the Frame Body. The "Block Ack obtainable flag" stores flag information indicating whether the STA 200 can obtain the BA transmitted from the second AP 100B to the first AP 100A.

[0315] (Operation of the first AP 100A) Fig. 19 is a diagram illustrating an example of a second sharing process according to an embodiment of the present disclosure. The second sharing process illustrated in Fig. 19 is executed by the first AP 100A that has acquired a TXOP, for example, in the Transition Phase. Note that in the second sharing process illustrated in Fig. 19, the same processes as those in the first sharing process illustrated in Fig. 13 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0316] 19 , the first AP 100A, which has received a Block Ack from the STA 200 in step S107, determines whether the second AP 100B can receive this Block Ack (step S301). For example, the first AP 100A determines whether the second AP 100B can receive this Block Ack from flag information stored in the Block Ack obtainable flag of the Coordination Response frame.

[0317] If the second AP 100B can acquire this Block Ack (step S301; Yes), the first AP 100A proceeds to step S108. On the other hand, if the second AP 100B cannot acquire this Block Ack (step S301; No), the first AP 100A transmits the SN information to the second AP 100B (step S302).

[0318] (Operation of the second AP 100B) Fig. 20 is a diagram showing another example of the second sharing process according to the embodiment of the present disclosure. The second sharing process shown in Fig. 20 is executed by the second AP 100B, for example, in the Transition Phase. Note that in the second sharing process shown in Fig. 20, the same processes as those in the first sharing process shown in Fig. 14 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0319] As shown in FIG. 20, the second AP 100B, which has acquired the Copied Data in step S205, acquires the SN information from the first AP 100A or a Block Ack from the STA 200 (step S401).

[0320] For example, assume that the second AP 100B stores flag information indicating that a Block Ack can be acquired in the Block Ack obtainable flag of the Coordination Response frame and transmits it. In this case, the second AP 100B acquires the Block Ack addressed to the first AP 100A from the STA 200.

[0321] On the other hand, if the second AP 100B transmits a Coordination Response frame with flag information indicating that a Block Ack cannot be obtained stored in the Block Ack obtainable flag, the second AP 100B obtains the SN information from the first AP 100A.

[0322] Based on the acquired SN information or Block Ack, the second AP 100B deletes from its own buffer the Copied Packet(s) that have been successfully transmitted to the STA 200 (step S402). As a result, the second AP 100B identifies the packets to be transmitted (retransmitted) to the STA 200.

[0323] Next, the second AP 100B determines whether or not there is a packet to be transmitted to the STA 200 (step S403). If there is no packet to be transmitted to the STA 200 (step S403; No), the second AP 100B ends the process. On the other hand, if there is a packet to be transmitted to the STA 200 (step S403; Yes), the second AP 100B proceeds to step S206.

[0324] As described above, in the second sharing process, the second AP 100B retransmits packets to the STA 200 based on the BA addressed to the first AP 100A. The data retransmitted to the STA 200 includes at least one packet (e.g., a packet that failed to be transmitted) included in the data transmitted by the first AP 100A.

[0325] In this way, the second AP 100B can prevent redundant transmission of packets on the fronthaul link by retransmitting the packets that have failed to be transmitted to the STA 200. This can prevent a deterioration in transmission efficiency of the communication system 10.

[0326] <3-3. Third Example of Sharing Process> In the second sharing process described above, the first AP 100A copies all packets to be transmitted to the STA 200 and transmits them to the second AP 100B.

[0327] On the other hand, improvement in communication efficiency of the backhaul link is required in the communication system 10. Therefore, in the third sharing process, the first AP 100A copies some of the packets included in the data to be transmitted to the STA 200 and transmits the copied packets to the STA 200, thereby improving communication efficiency.

[0328] (Flow of third sharing process) Fig. 21 is a sequence diagram showing an example of the flow of the third sharing process according to an embodiment of the present disclosure. Fig. 21 shows an example of the flow of the third sharing process in the Transition Phase. Note that in Fig. 21, descriptions of the same processes as in Fig. 15 will be omitted.

[0329] In the third sharing process, the first AP 100A receives a BA from the STA 200 and then transmits Copied Packet(s) to the first AP 100A.

[0330] 21, at time t21, which is after time t06, the first AP 100A transmits a frame including SN information and Copied Packet(s) to the second AP 100B. The Copied Packet(s) include Copied Packets #2 and #4, which are packets #2 and #4 that the first AP 100A failed to transmit. This SN information is, for example, the same as the SN information of the second sharing process.

[0331] The first AP 100A generates SN information and copied packet(s) based on the BA acquired from the STA 200. The first AP 100A transmits the generated SN information and copied packet(s) to the second AP 100B.

[0332] When the second AP 100B acquires the TXOP, it generates a data frame to be transmitted to the STA 200 based on the acquired SN information, Copied Packet(s), and Context information acquired in advance in the Coordination Request.

[0333] After generating the data frame, the second AP 100B transmits the generated data frame to the STA 200 at time t22. Thereafter, the second AP 100B obtains a BA from the STA 200 at time t23.

[0334] Here, when the first AP 100A requests two or more second APs 100B to transmit data to the STA 200, the second AP 100B may notify the other second APs 100B of whether or not the packet retransmission to the STA 200 was successful (e.g., SN information).

[0335] At this time, the second AP 100B may notify the other second AP 100B of a copy of the packet that the transmission of the first AP 100A failed. If the other second AP 100B already has a copy of the packet that the transmission of the first AP 100A failed, the second AP 100B may omit notifying the other second AP 100B of the copy of the packet that the transmission of the first AP 100A failed.

[0336] The frame structure of the Coordination Request / Response frame in the third sharing process is the same as the frame structure described in the first sharing process, and therefore a description thereof will be omitted.

[0337] (Operation of the first AP 100A) Fig. 22 is a diagram illustrating an example of a third sharing process according to an embodiment of the present disclosure. The third sharing process illustrated in Fig. 22 is executed by the first AP 100A that has acquired a TXOP, for example, in the Transition Phase. Note that in the third sharing process illustrated in Fig. 22, the same processes as those in the first sharing process illustrated in Fig. 13 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0338] 22, the first AP 100A, which has received a Coordination Response with a Transition flag set to Y (step S103; Yes), then receives a Block Ack from the STA 200 in step S107. Thereafter, the first AP 100A determines whether or not there is a packet that has failed to be transmitted to the STA 200 (step S501).

[0339] If there are no packets whose transmission has failed (step S501; No), the first AP 100A proceeds to step S108. On the other hand, if there are packets whose transmission has failed (step S501; Yes), the first AP 100A transmits Copied Packet(s) to the second AP 100B via the backhaul link (step S502). This Copied Packet(s) includes a copy of the packet whose transmission has failed. The first AP 100A also transmits SN information to the second AP 100B along with the Copied Packet(s).

[0340] The operation of the second AP 100B in the third sharing process is the same as that in the first sharing process shown in FIG. 14, and therefore will not be described here.

[0341] As described above, in the third sharing process, the first AP 100A transmits a copy of the packet for which retransmission is requested to the second AP 100B. This allows the first AP 100A to prevent redundant transmission of the packet on the backhaul link.

[0342] Furthermore, the second AP 100B retransmits a packet that the first AP 100A failed to transmit to the STA 200. This allows the second AP 100B to prevent redundant transmission of packets on the fronthaul link.

[0343] This allows the communication system 10 to prevent a decrease in communication efficiency.

[0344] In the third sharing process, the first AP 100A transmits the copied data to the second AP 100B after acquiring the BA from the STA 200. Therefore, if it is desired to start transmitting data from the second AP 100B to the STA 200 sooner, it is desirable to perform the first sharing process or the second sharing process rather than the third sharing process.

[0345] On the other hand, in order to prevent a deterioration in the communication efficiency of the communication system 10 including the backhaul link, it is desirable to perform the third sharing process.

[0346] <3-4. Fourth Example of Sharing Process> In the first to third sharing processes described above, the second AP 100B acquires the copied data or copied packet(s) and then transmits the data to the STA 200 upon acquiring the TXOP.

[0347] In the fourth sharing process, the second AP 100B waits for a predetermined period (hereinafter also referred to as a waiting time) to acquire Copied Data or Copied Packet(s) regardless of whether or not the second AP 100B has acquired a TXOP. That is, in the fourth process, it is assumed that the approximate time (Pre-determined Copied Packets ReTx Time) at which the second AP 100B starts transmitting data to the STA 200 has been determined between the first AP 100A and the second AP 100B.

[0348] Even if the second AP 100B has already received the Copied Packet(s) and acquired a TXOP, it waits to retransmit data until the waiting time (or Pre-determined Copied Packets ReTx Time) has elapsed.

[0349] On the other hand, suppose that the second AP 100B has already acquired Copied Packet(s) and the waiting time (or Pre-determined Copied Packets ReTx Time) has elapsed without acquiring a TXOP. In this case, the second AP 100B acquires a TXOP after the waiting time has elapsed, and then retransmits data to the STA 200.

[0350] Furthermore, when the second AP 100B acquires the copied packet(s) from the first AP 100A after the waiting time has elapsed, the second AP 100B may or may not transmit the copied packet(s) to the STA 200.

[0351] For example, the second AP 100B may determine whether to transmit the acquired Copied Packet(s) after the waiting time has elapsed, taking into consideration the free space in its own buffer, etc.

[0352] The first AP 100A transmits the Copied Packet(s) requesting retransmission to the second AP 100B by the end of the waiting time. The first AP 100A may transmit the Copied Packet(s) requesting retransmission all at once or may transmit them in multiple batches.

[0353] The first AP 100A transmits the Copied Packet(s) to the second AP 100B, taking into consideration the length of the waiting time and the status of the backhaul link (for example, speed, congestion, tightness, etc.).

[0354] For example, if the waiting time is long (for example, longer than a predetermined threshold Th1), the first AP 100A, after acquiring the BA from the STA 200, transmits Copied Packet(s) according to the BA to the second AP 100B.

[0355] On the other hand, if the waiting time is short (for example, shorter than a predetermined threshold Th2), the first AP 100A, after receiving the Coordination Response, transmits Copied Data to the second AP 100B. Alternatively, after receiving the Coordination Response, the first AP 100A may transmit copies of packets that are likely to fail to be transmitted as Copied Packet(s) to the second AP 100B.

[0356] Alternatively, if the waiting time is within a predetermined range (for example, a predetermined threshold value Th2 or more and Th1 or less), the first AP 100A transmits the Copied Packet(s) to the second AP 100B in multiple batches.

[0357] The thresholds Th1 and Th2 here can be changed depending on the status of the backhaul link (for example, speed, congestion, tightness, etc.).

[0358] For example, after receiving the Coordination Response, the first AP 100A transmits some of the Copied Packets to the second AP 100B.

[0359] The number of packets to be transmitted here is preferably the number of Copied Packets that the first AP 100A cannot send from the time of BA acquisition until the waiting time. However, the number of packets to be transmitted here is not limited to this. In addition, the packets to be transmitted here may be determined taking into consideration the priority and loss rate of the packets.

[0360] Next, after obtaining the BA from the STA 200, the first AP 100A transmits to the second AP 100B the copied packets that it failed to transmit to the STA 200 and that it has not yet transmitted to the second AP 100B.

[0361] The first AP 100A has already transmitted some of the copied packets to the second AP 100B, so there is a possibility that the first AP 100A can reduce the number of copied packets to be transmitted to the second AP 100B.

[0362] For example, the first AP 100A transmits to the second AP 100B in advance copies of packets that are likely to fail to be transmitted to the STA 200 or packets with high priority. This increases the possibility that the first AP 100A can reduce the number of copied packets transmitted to the second AP 100B after acquiring the BA.

[0363] Here, examples of packets that are likely to fail in transmission to the STA 200 include packets with large sequence numbers (SN), in other words, packets transmitted after a data frame.

[0364] For example, when the STA 200 moves away from the first AP 100A, the distance between the STA 200 and the first AP 100A increases as time passes since the start of data transmission to the STA 200.

[0365] In this case, the longer the time passes after the start of data transmission to the STA 200, the more the communication quality between the STA 200 and the first AP 100A deteriorates, and packet transmission failure becomes more likely to occur.

[0366] For this reason, the first AP 100A transmits copies of packets that are likely to fail in transmission to the second AP 100B in advance, thereby increasing the possibility of reducing the number of copied packets transmitted to the second AP 100B after BA acquisition.

[0367] The waiting time may be a predetermined fixed time, or may be a time determined depending on the traffic conditions, communication quality, etc., exchanged in the communication system 10 .

[0368] Alternatively, the waiting time may be determined according to the quality (QoS) required for packets transmitted to STA 200. The waiting time may be determined according to the allowable delay time of packets transmitted to STA 200, the required transmission delay budget, etc.

[0369] In this way, in the fourth sharing process, the time to start retransmission to the STA 200 (in other words, the waiting time to wait for copied data) is determined in advance between the first AP 100A and the second AP 100B. The second AP 100B waits for the copied packet(s) until the waiting time has elapsed, and starts transmitting data to the STA 200 after the waiting time has elapsed.

[0370] This allows the communication system 10 to transmit data from the first AP 100A and the second AP 100B to the same STA 200 while reducing the number of copied packets transmitted over the backhaul link.

[0371] (Flow of Fourth Sharing Process) Fig. 23 is a sequence diagram showing an example of the flow of the fourth sharing process according to an embodiment of the present disclosure. Fig. 23 shows an example of the flow of the third sharing process in the Transition Phase. Note that in Fig. 23, descriptions of the same processes as in Fig. 21 will be omitted.

[0372] Here, the flow of the fourth sharing process will be described when the waiting time is within a predetermined range (for example, equal to or greater than the predetermined threshold Th2 and equal to or less than the predetermined threshold Th1).

[0373] The flow of the fourth sharing process when the waiting time is long (for example, longer than a predetermined threshold Th1) is the same as the third sharing process. Also, the flow of the fourth sharing process when the waiting time is short (for example, shorter than a predetermined threshold Th2) is the same as the second sharing process. Therefore, a description of the fourth sharing process when the waiting time is long / short will be omitted.

[0374] First, the first AP 100A and the second AP 100B exchange Coordination Request / Response frames at time t03 and time t04. At this time, the first AP 100A and the second AP 100B determine the standby time to be time t30.

[0375] The first AP 100A determines the timing of transmitting the Copied Packet(s) in accordance with the determined waiting time, etc. Here, it is assumed that the first AP 100A determines to transmit the Copied Packet(s) twice, once after receiving the Coordination Response and once after receiving the BA from the STA 200.

[0376] After acquiring the Coordination Response and determining the Copied Packet(s) to be transmitted, the first AP 100A transmits the determined Copied Packet(s) to the second AP 100B at time t31.

[0377] Next, when the first AP 100A acquires a BA from the STA 200 at time t06, the first AP 100A identifies packets that have failed to be transmitted to the STA 200 and have not yet been transmitted to the second AP 100B.

[0378] The first AP 100A transmits copies of the identified packets (several Copied Packets) together with the SN information to the second AP 100B at time t32.

[0379] The second AP 100B, which has acquired the SN information and some Copied Packet(s), does not transmit to the STA 200 even though it has acquired the TXOP, and waits until time t30, which is a standby time, has elapsed.

[0380] After time t30 has elapsed, the second AP 100B identifies a packet to be retransmitted based on the SN information and the information stored in the Start SN / SN Bitmap in the Contest information. The second AP 100B selects a packet to be retransmitted from the Copied Packet(s) and generates a data frame including the selected packet.

[0381] After generating the data frame, the second AP 100B transmits the generated data frame to the STA 200 at time t33 within the TXOP. Thereafter, the second AP 100B obtains a BA from the STA 200 at time t34.

[0382] (Frame Configuration Example) Here, a configuration example of a Coordination Request / Response frame in a case where the first AP 100A and the second AP 100B determine the standby time will be described.

[0383] (Coordination Request frame) Fig. 24 is a diagram illustrating a configuration example of a Coordination Request frame according to an embodiment of the present disclosure. Note that, among the configurations of the Coordination Request frame in Fig. 24, the description of the configurations that are the same as those of the Coordination Request frame in Fig. 11 will be omitted.

[0384] The Coordination Request frame shown in Fig. 24 differs from the Coordination Request frame shown in Fig. 11 in that "Expected Packets Wait Time" is included in Copied Data Info. "Expected Packets Wait Time" stores information regarding the waiting time requested (desired) by the first AP 100A.

[0385] This waiting time is, for example, an approximate time from when the first AP 100A transmits a Coordination Request frame until when the second AP 100B starts retransmitting data addressed to the STA 200. In other words, the start timing of the waiting time is the timing when the first AP 100A transmits a Coordination Request frame to the second AP 100B.

[0386] Hereinafter, the standby time requested by the first AP 100A will also be referred to as a standby request time.

[0387] (Coordination Response frame) Fig. 25 is a diagram illustrating a configuration example of a Coordination Response frame according to an embodiment of the present disclosure. Note that, among the configurations of the Coordination Response frame in Fig. 25, the description of the configuration that is the same as that of the Coordination Response frame in Fig. 12 will be omitted.

[0388] The Coordination Response frame shown in Fig. 18 differs from the Coordination Response frame shown in Fig. 12 in that the Frame Body includes "Packets Wait Time." "Packets Wait Time" stores information related to the waiting time specified by the second AP 100B.

[0389] By exchanging the Coordination Request / Response frames shown in FIGS. 24 and 25, the first AP 100A and the second AP 100B determine the standby time.

[0390] (Operation of the first AP 100A) Fig. 26 is a diagram illustrating an example of a fourth sharing process according to an embodiment of the present disclosure. The fourth sharing process illustrated in Fig. 26 is executed by the first AP 100A that has acquired a TXOP, for example, in the Transition Phase. Note that in the fourth sharing process illustrated in Fig. 26, the same processes as those in the first sharing process illustrated in Fig. 13 may be assigned the same reference numerals and descriptions thereof may be omitted.

[0391] 26, the first AP 100A, which has started data transmission to the STA 200 via the fronthaul link in step S101, determines an Expected Packets Wait Time (step S601). In step S102, the first AP 100A transmits a Coordination Request including the Expected Packets Wait Time to the second AP 100B.

[0392] When the first AP 100A receives a Coordination Response with the Transition flag set to Y (Step S103; Yes), the first AP 100A sets a Packets Wait Time (Step S602).

[0393] Next, the first AP 100A determines whether all packets can be transmitted over the backhaul link within the time (Packets Wait Time) after acquiring the BA (step S603). This BA is a response to the data transmitted by the first AP 100A and is acquired from the STA 200.

[0394] If all packets can be transmitted over the backhaul link by the time (Packets Wait Time) after BA acquisition (Step S603; Yes), the first AP 100A proceeds to Step S605.

[0395] On the other hand, if it is not possible to transmit all packets via the backhaul link within the above-mentioned time (Packets Wait Time) after obtaining the BA (step S603; No), the first AP 100A transmits some of the Copied Packet(s) to the second AP 100B via the backhaul link (step S604).

[0396] Thereafter, when the first AP 100A receives a Block Ack (BA) from the STA 200 (step S605), it determines whether the transmission unsuccessful packet has already been shared with the second AP 100B (step S606).

[0397] If the transmission unsuccessful packet has already been shared with the second AP 100B (step S606; Yes), the first AP 100A transmits the SN information to the second AP 100B (step S607) and ends the process.

[0398] The SN information transmitted here may be the same as the SN information transmitted by the first AP 100A in the second sharing process. Also, similar to the second sharing process, when the second AP 100B obtains a BA addressed to the first AP 100A, transmission of the SN information may be omitted.

[0399] If the transmission-failed packet has not already been shared with the second AP 100B (step S606; No), the first AP 100A transmits the SN information and some of the Copied Packet(s) to the second AP 100B (step S607), and ends the process.

[0400] That is, if there is a failed transmission packet that is not shared with the second AP 100B, the first AP 100A transmits a copy of the failed transmission packet and SN information that is not shared with the second AP 100B to the second AP 100B.

[0401] (Operation of the second AP 100B) Fig. 27 is a diagram showing another example of the fourth sharing process according to the embodiment of the present disclosure. The fourth sharing process shown in Fig. 27 is executed by the second AP 100B, for example, in the Transition Phase. Note that in the fourth sharing process shown in Fig. 27, the same processes as those in the first sharing process shown in Fig. 14 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0402] 27, the second AP 100B, which has determined in step S202 that it is possible to transmit data to the STA 200, determines a Packet Wait Time (step S701). In step S204, the second AP 100B transmits a Coordination Response including the Packets Wait Time to the first AP 100A.

[0403] The second AP 100B acquires the Copied Packet(s) via the backhaul link (step S702). At this time, the second AP 100B may acquire the Copied Packet(s) in multiple batches.

[0404] Next, the second AP 100B acquires a transmission opportunity (TXOP) after the Packets Wait Time has elapsed (step S703). The subsequent processing is the same as that in FIG.

[0405] As described above, in the fourth sharing process, the first AP 100A and the second AP 100B set a waiting time. The second AP 100B starts retransmission to the STA 200 after the waiting time has elapsed.

[0406] By setting the waiting time, the first AP 100A can know the approximate timing at which the second AP 100B will start retransmitting data. Furthermore, the first AP 100A shares packets with the second AP 100B at a timing according to the waiting time.

[0407] As a result, the communication system 10 can reduce the amount of transmission on the backhaul link while shortening the timing of data retransmission by the second AP 100B compared to the third sharing process.

[0408] <3-5. Fifth Sharing Process Example> In the above-described first to third sharing processes, the second AP 100B transmits data to the STA 200 using the TXOP it has acquired. On the other hand, by using a function called TXOP Sharing, the first AP 100A can share the TXOP it has acquired with the second AP 100B. In other words, the first AP 100A can allow the second AP 100B to transmit data within the TXOP it has acquired.

[0409] In the fifth sharing process, the first AP 100A uses this TXOP Sharing to give a transmission opportunity to the second AP 100B, and the second AP 100B transmits data to the STA 200 within the TXOP acquired by the first AP 100A.

[0410] Here, a case where TXOP Sharing is applied to the fourth sharing process will be described, but TXOP Sharing can also be applied to the first to third sharing processes in the same way.

[0411] (Flow of Fifth Sharing Process) Fig. 28 is a sequence diagram showing an example of the flow of the fifth sharing process according to an embodiment of the present disclosure. Fig. 28 shows an example of the flow of the fifth sharing process in the Transition Phase. Note that in Fig. 28, descriptions of the same processes as in Fig. 23 will be omitted.

[0412] 28 differs from the fourth sharing process in that the second AP 100B retransmits data using the TXOP of the first AP 100A. The first AP 100A transmits a Trigger frame for TXOP Sharing to the second AP 100B at time t41. By transmitting the Trigger frame, the first AP 100A permits the second AP 100B to use the TXOP it has acquired.

[0413] Upon receiving the trigger frame, the second AP 100B retransmits data. This data retransmission is the same as the fourth sharing process in Fig. 23 except that the TXOP acquired by the first AP 100A is used.

[0414] In this way, by transmitting the Trigger frame, the first AP 100A can instruct (request) the second AP 100B to retransmit data at a desired timing.

[0415] For example, the first AP 100A transmits a trigger frame near the standby time (e.g., time t30). In the example of Fig. 28, the first AP 100A transmits the trigger frame at time t41, which is before time t30. This allows the second AP 100B to retransmit data immediately after the standby time has elapsed.

[0416] (Frame Configuration Example) (Coordination Request Frame) Fig. 29 is a diagram illustrating a configuration example of a Coordination Request frame according to an embodiment of the present disclosure. Note that, among the configurations of the Coordination Request frame in Fig. 29, descriptions of the same configuration as the Coordination Request frame in Fig. 24 will be omitted.

[0417] The Coordination Request frame shown in Fig. 29 differs from the Coordination Request frame shown in Fig. 24 in that Copied Data Info includes a "TXOP Sharing Flag." The "TXOP Sharing Flag" stores flag information indicating whether TXOP Sharing is performed.

[0418] For example, TXOP sharing is not performed when the TXOP Sharing Flag is N. In this case, the second AP 100B acquires a TXOP by itself and retransmits data to the STA 200.

[0419] On the other hand, if the TXOP Sharing Flag is Y, TXOP Sharing is performed. In this case, the second AP 100B receives permission (Trigger frame) from the first AP 100A and retransmits data to the STA 200 using the TXOP acquired by the first AP 100A.

[0420] (Coordination Response frame) The configuration of the Coordination Response frame is the same as the configuration of the Coordination Response frame in Fig. 25. However, when the TXOP Sharing Flag of the Coordination Request frame is Y, the Expected Packets Wait Time of the Coordination Request frame may be stored as is in "Packets Wait Time". Alternatively, an arbitrary value (wildcard) may be stored in "Packets Wait Time".

[0421] Furthermore, when the TXOP Sharing Flag of the Coordination Request frame is set to Y, time information different from the Expected Packets Wait Time may be stored in the "Packets Wait Time."

[0422] (Operation of the first AP 100A) Fig. 30 is a diagram showing an example of a fifth sharing process according to an embodiment of the present disclosure. The fifth sharing process shown in Fig. 30 is executed by the first AP 100A that has acquired a TXOP, for example, in the Transition Phase. Note that in the fifth sharing process shown in Fig. 30, the same processes as those in the fourth sharing process shown in Fig. 26 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0423] As shown in FIG. 30, the first AP 100A, which has transmitted the SN information in step S607 or the SN information and some Copied Packet(s) in step S608, sends a TXOP Sharing Trigger to the second AP 100B (step S801) and terminates the processing.

[0424] (Operation of the second AP 100B) Fig. 31 is a diagram showing another example of the fifth sharing process according to the embodiment of the present disclosure. The fifth sharing process shown in Fig. 31 is executed by the second AP 100B, for example, in the Transition Phase. Note that in the fifth sharing process shown in Fig. 31, the same processes as those in the fourth sharing process shown in Fig. 27 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0425] In this case, the second AP 100B does not set a standby time because it retransmits using the TXOP acquired by the first AP 100A in response to an instruction (trigger) from the first AP 100A. Therefore, the process of Fig. 31 differs from the process of Fig. 27 in that it does not include steps S701 and S703.

[0426] 31, the second AP 100B, which has acquired the Copied Packet(s) in step S702, acquires a TXOP Sharing Trigger from the first AP 100A (step S901). Thereafter, the second AP 100B generates a transmission packet (step S206) and starts data transmission to the STA 200 using the TXOP acquired by the first AP 100A (step S207).

[0427] As described above, in the fifth sharing process, the first AP 100A uses the TXOP Sharing Trigger to instruct the second AP 100B when to retransmit data. This allows the first AP 100A to accurately determine the timing when the second AP 100B will retransmit data, making it possible to more efficiently determine the transmission of Copied Packet(s).

[0428] Although TXOP sharing is used here as a method for the first AP 100A and the second AP 100B to share the TXOP, the method for the first AP 100A and the second AP 100B to share the TXOP is not limited to this. The first AP 100A and the second AP 100B may share the TXOP using another cooperative method.

[0429] <<4. Other Embodiments>> The processing according to the above-described embodiment may be implemented in various different forms other than the above embodiment.

[0430] In the above embodiment, the second AP 100B retransmits data to the STA 200 once, but the number of times the second AP 100B retransmits data to the STA 200 is not limited to once. The second AP 100B may retransmit data to the STA 200 two or more times.

[0431] The second and subsequent retransmissions may be performed by the second AP 100B that performed the first retransmission, or by the first AP 100A. Alternatively, the second and subsequent retransmissions may be performed by a second AP 100B different from the second AP 100B that performed the first retransmission. This different second AP 100B is, for example, the second AP 100B participating in the Transition Phase.

[0432] When the second or subsequent retransmissions are performed by an AP 100 different from the second AP 100B that performed the first retransmission, the second AP 100B that performed the first retransmission notifies the AP 100 that will perform the second or subsequent retransmissions of information to be used for retransmission. For example, the second AP 100B notifies the AP 100 that will perform the second or subsequent retransmissions of SN information and a copy of the packet to be retransmitted.

[0433] In the above embodiment, the second AP 100B retransmits data to the STA 200. That is, the first AP 100A and the second AP 100B transmit the same data (or packet) to the same STA 200, but the present invention is not limited to this.

[0434] For example, the second AP 100B may transmit to the STA 200 packets different from the packets transmitted by the first AP 100A. For example, packets other than retransmissions may be included in part of the data transmitted by the second AP 100B to the STA 200. These packets other than retransmissions may be packets transmitted by the first AP 100A to the second AP 100B. In this case, the retransmission of data described above may be interpreted as transmission of data.

[0435] In the above embodiment, the second AP 100B retransmits the data transmitted by the first AP 100A, but the order of data transmission is not limited to this. For example, the first AP 100A (or another second AP 100B) may retransmit the data transmitted by the second AP 100B.

[0436] For example, if the first AP 100A has high priority traffic and cannot immediately transmit data addressed to the STA 200, the first AP 100A requests (requests) the second AP 100B to transmit the data before transmitting the data itself.

[0437] This allows the communication system 10 to further reduce delays in data transmission.

[0438] <<5. Example of Computer Configuration>> The above-described series of processes can be executed by hardware or software. When the series of processes is executed by software, the program constituting the software is installed from a program recording medium into a computer incorporated in dedicated hardware, a general-purpose personal computer, or the like.

[0439] FIG. 32 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.

[0440] A CPU (Central Processing Unit) 801 , a ROM (Read Only Memory) 802 , and a RAM (Random Access Memory) 803 are interconnected by a bus 804 .

[0441] An input / output interface 805 is further connected to the bus 804. An input unit 806 including a keyboard, a mouse, etc., and an output unit 807 including a display, a speaker, etc., are connected to the input / output interface 805. Information related to the present technology, for example, information related to handover, may be output or displayed from the output unit 807. Information related to the present technology, for example, information related to handover, may be input from the input unit 806, and confirmation or response to the information output or displayed on the output unit 807 may be input. In addition, a storage unit 808 including a hard disk or nonvolatile memory, a communication unit 809 including a network interface, etc., and a drive 810 that drives removable media 811 are connected to the input / output interface 805.

[0442] In the computer configured as above, the series of processes described above are performed by the CPU 801, for example, by loading a program stored in the storage unit 808 into the RAM 803 via the input / output interface 805 and the bus 804 and executing the program. For example, the CPU 801 may execute processing programs corresponding to the flowcharts of the present technology in Figures 13, 14, 19, 20, 22, 26, 27, 30, and 31.

[0443] The program executed by the CPU 801 is provided, for example, by being recorded on a removable medium 811 or via a wired or wireless transmission medium such as a local area network, the Internet, or digital broadcasting, and is installed in the storage unit 808.

[0444] The program executed by the computer may be a program that processes in chronological order according to the order described in this specification, or may be a program that processes in parallel or at the required timing, such as when called.

[0445] <Application Examples> The present technology can be applied to various products. For example, the AP 100 (communication device) in Fig. 6, the STA 200 (terminal device) in Fig. 7, and the control device 300 in Fig. 8 may be realized as a mobile terminal such as a smartphone, a tablet PC (personal computer), a notebook PC, a portable game terminal, or a digital camera, a fixed terminal such as a television receiver, a projector, a printer, a digital scanner, or a network storage, or an in-vehicle terminal such as a car navigation device or a drive recorder. Furthermore, the AP 100 (communication device), the STA 200 (terminal device), and the control device 300 may be realized as an M2M (machine-to-machine communication) terminal or an IoT (Internet of Things) terminal such as a smart meter, a vending machine, a remote monitoring device, or a POS (point-of-sale) terminal. The AP 100 (communication device), the STA 200 (terminal device), and the control device 300 may be realized as terminals that require low latency and high reliability, such as XR (Extended Reality / Cross Reality) devices. Furthermore, the AP 100 (communication device), the STA 200 (terminal device), and the control device 300 may be wireless communication modules (for example, integrated circuit modules configured on a single die) mounted on these terminals.

[0446] On the other hand, for example, the AP 100 (communication device), the STA 200 (terminal device), and the control device 300 may be realized as a wireless LAN AP (wireless base station) with or without router functionality. The AP 100 (communication device), the STA 200 (terminal device), and the control device 300 may also be realized as a mobile wireless LAN router. The AP 100 (communication device), the STA 200 (terminal device), and the control device 300 may also be realized as a cellular communication base station and a femtocell. Furthermore, the AP 100 (communication device), the STA 200 (terminal device), and the control device 300 may be wireless communication modules (e.g., integrated circuit modules configured on a single die) mounted on these devices.

[0447] <Configuration example of smartphone> Fig. 33 is a block diagram showing a schematic configuration example of a smartphone 900 to which the present technology is applied. Fig. 33 is described as a configuration example of the smartphone 900, but the present technology is not limited to this, and may be a configuration example of the various devices and functions described above.

[0448] The smartphone 900 includes a processor 901, a memory 902, a storage 903, an external connection interface 904, a camera 906, a sensor 907, a microphone 908, an input device 909, and a display device 910. 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 or some of the above.

[0449] 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.

[0450] The memory 902 includes RAM and ROM, and stores programs and data executed by the processor 901 .

[0451] The storage 903 includes a storage medium such as a semiconductor memory or a hard disk.

[0452] The external connection interface 904 is an interface for connecting an external device such as a memory card or a USB (Universal Serial Bus) device to the smartphone 900 .

[0453] The camera 906 has an imaging element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), and generates a captured image.

[0454] The sensor 907 includes a group of sensors such as a positioning sensor, a gyro sensor, a geomagnetic sensor, and an acceleration sensor.

[0455] The microphone 908 converts the sound input to the smartphone 900 into an audio signal.

[0456] The input device 909 includes, for example, a touch sensor that detects a touch on the screen of the display device 910, a keypad, a keyboard, a button, or a switch, and accepts operations or information input from the user.

[0457] The display device 910 has a screen such as a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, or a quantum dot (QD) display, and displays an output image of the smartphone 900.

[0458] The speaker 911 converts the audio signal output from the smartphone 900 into sound.

[0459] The wireless communication interface 913 supports one or more wireless LAN standards such as IEEE802.11a, 11b, 11g, 11ac, 11ad, 11ax, 11ay, 11be, 11bn, and successor standards thereof, and performs wireless communication.

[0460] The wireless communication interface 913 communicates with other devices via a wireless LAN AP in infrastructure mode, and directly with other devices in ad hoc mode or a direct communication mode such as Wi-Fi Direct.

[0461] Unlike ad hoc mode, in Wi-Fi Direct, one of the two terminals acts as an AP, but communication is carried out directly between the terminals.

[0462] The wireless communication interface 913 typically includes a baseband processor, an RF (Radio Frequency) circuit, a power amplifier, etc. The wireless communication interface 913 may be a one-chip module that integrates a memory that stores a communication control program, a processor that executes the program, and related circuits.

[0463] The wireless communication interface 913 may support other types of wireless communication methods, such as a short-range wireless communication method such as Bluetooth (registered trademark), a proximity wireless communication method such as NFC, or a 3GPP (registered trademark) cellular communication method such as 2G, 3G, 4G, 5G, and 6G, in addition to the wireless LAN method. The wireless communication interface 913 may be a one-chip module that supports multiple wireless communication methods, or may be a combination of modules that support some of the wireless communication methods.

[0464] The antenna switch 914 switches the connection destination of the antenna 915 between multiple circuits included in the wireless communication interface 913 (for example, circuits for different wireless communication methods, or transmission system circuits and reception system circuits).

[0465] The antenna 915 has a single or multiple antenna elements (e.g., multiple antenna elements constituting a MIMO (Multiple Input Multiple Output) antenna, or multiple antenna elements constituting an array antenna) and is used for transmitting and receiving radio signals via the wireless communication interface 913.

[0466] 33 , the smartphone 900 may include multiple antennas (for example, a wireless LAN antenna, a proximity wireless communication antenna, and a cellular communication antenna). In this case, the antenna switch 914 may be omitted from the configuration of the smartphone 900.

[0467] The 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.

[0468] The battery 918 supplies power to each block of the smartphone 900 shown in FIG. 33 via a power supply line partially indicated by a dashed line 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 amount of power, the cumulative power-on time, or the cumulative amount of power supply, and the processor 901, the wireless communication interface 913, or the auxiliary controller 919 may control any of the functions of the above-described embodiments based on the information read from the battery 918.

[0469] In the smartphone 900 shown in Fig. 33 , for example, the communication control unit 115 in Fig. 6 , the communication control unit 215 in Fig. 7 , and the communication control unit 312 in Fig. 8 may be implemented in the wireless communication interface 913. For example, processing programs corresponding to the flowcharts in Figs. 13 , 14 , 19 , 20 , 22 , 26 , 27 , 30 , and 31 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.

[0470] The smartphone 900 may operate as a wireless AP (software AP) by the processor 901 executing an AP function at the application level. The wireless communication interface 913 may have a wireless AP function. The processor 901 or the wireless communication interface 913 may have a tethering function that uses a wireless LAN system and a cellular communication system, and may transmit payload data received via the cellular communication system via the wireless LAN system, or may transmit payload data received via the wireless LAN system via the cellular communication system. The smartphone 900 may have a tethering function enabled by user input.

[0471] Furthermore, the smartphone 900 may be provided with a biometric authentication unit (fingerprint authentication, palm shape authentication, voice authentication, blood vessel authentication, face authentication, iris authentication, retina authentication). In this case, a wireless communication interface 913 on which the communication control unit 115 in Fig. 6, the communication control unit 215 in Fig. 7, and the communication control unit 312 in Fig. 8 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.

[0472] Furthermore, in the smartphone 900, information is displayed on 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. At this time, information related to the present technology, for example, information related to handover, may be output from at least one of the display device 910 and the speaker 911. Furthermore, the input device 909 may be configured to input a confirmation or response to the information output from at least one of the display device 910 and the speaker 911.

[0473] <Configuration example of in-vehicle device> Fig. 34 is a block diagram showing an example of a schematic configuration of an in-vehicle device 920 to which the present technology is applied. Fig. 34 is described as an example of the configuration of the in-vehicle device 920, but the configuration is not limited to this and may be an example of the configuration of the various devices and functions described above.

[0474] The in-vehicle device 920 is configured to include a processor 921, a memory 922, a GNSS (Global Navigation Satellite System) module 924, a sensor 925, a data interface 926, a content player 927, and a storage medium interface 928. The in-vehicle device 920 is also configured to include an input device 929, a display device 930, a speaker 931, a wireless communication interface 933, an antenna switch 934, an antenna 935, and a battery 938. The in-vehicle device 920 may be configured to include all or some of the above.

[0475] The processor 921 may be, for example, a CPU or an SoC, and controls the navigation function and other functions of the in-vehicle device 920. The processor 921 can also control the vehicle's driving system, such as the brake, accelerator, or steering, based on information obtained through communication based on the present technology.

[0476] The memory 922 includes RAM and ROM, and stores programs and data executed by the processor 921 .

[0477] The GNSS module 924 measures the position (e.g., latitude, longitude, and altitude) of the in-vehicle device 920 using GNSS signals received from GNSS satellites.

[0478] The sensor 925 includes a group of sensors such as a gyro sensor, a geomagnetic sensor, a millimeter wave radar, a camera (an imaging element such as a CCD or CMOS), and an air pressure sensor.

[0479] The data interface 926 is connected to an in-vehicle network 941 via a terminal (not shown), for example, and acquires data generated on the vehicle side, such as vehicle-side data.

[0480] The content player 927 plays content stored on a storage medium (for example, a CD or DVD) inserted into the storage medium interface 928 or content received via the wireless communication interface 933 .

[0481] The input device 929 includes, for example, a touch sensor, a button, or a switch that detects a touch on the screen of the display device 930, and accepts operations or information input from the user. For example, the input device 929 may be configured to input a confirmation or response to information output from at least one of the display device 930 and the speaker 931.

[0482] The display device 930 has a screen such as an LCD, OLED display, or QD display, and displays images of navigation functions or content being played, as well as information related to the present technology, such as information about handover.

[0483] The speaker 931 outputs navigation functions, audio of the content being played, or information related to the present technology, for example, information related to handover.

[0484] Note that the navigation function and the function of the content player 927 are optional in the in-vehicle device 920. The navigation function and the content player 927 may be removed from the configuration of the in-vehicle device 920.

[0485] The wireless communication interface 933 supports one or more wireless LAN standards such as IEEE802.11a, 11b, 11g, 11n, 11ac, 11ad, 11ax, 11ay, 11be, 11bn, and successor standards thereof, and performs wireless communication.

[0486] The wireless communication interface 933 communicates with other devices via a wireless LAN AP in infrastructure mode, and directly with other devices in ad hoc mode or a direct communication mode such as Wi-Fi Direct.

[0487] Unlike ad hoc mode, in Wi-Fi Direct, one of the two terminals acts as an AP, but communication is carried out directly between the terminals.

[0488] The wireless communication interface 933 typically includes a baseband processor, an RF circuit, a power amplifier, etc. The wireless communication interface 933 may be a one-chip module that integrates a memory that stores a communication control program, a processor that executes the program, or related circuits.

[0489] The wireless communication interface 933 may support other types of wireless communication methods in addition to the WLAN method, such as a short-range wireless communication method such as Bluetooth, a proximity wireless communication method such as NFC, or a 3GPP cellular communication method such as 2G, 3G, 4G, 5G, and 6G. The wireless communication interface 933 may be a one-chip module that supports multiple wireless communication methods, or may be a combination of modules that support some of the wireless communication methods.

[0490] The antenna switch 934 switches the connection destination of the antenna 935 between multiple circuits included in the wireless communication interface 933 (for example, circuits for different wireless communication methods, or transmission system circuits and reception system circuits).

[0491] The antenna 935 has a single or multiple antenna elements (e.g., multiple antenna elements constituting a MIMO (Multiple Input Multiple Output) antenna, or multiple antenna elements constituting an array antenna) and is used for transmitting and receiving radio signals via the wireless communication interface 933.

[0492] 34 , the in-vehicle device 920 may include multiple antennas (for example, an antenna for wireless LAN, an antenna for a close-proximity wireless communication system, and an antenna for a cellular communication system). In this case, the antenna switch 934 may be omitted from the configuration of the in-vehicle device 920.

[0493] The battery 938 supplies power to each block of the in-vehicle device 920 shown in Fig. 34 via a power supply line partially indicated by a dashed line in the figure. The battery 938 may also store power supplied from the vehicle side. Alternatively, the in-vehicle device 920 may not be equipped with a battery and may instead use power supplied from the vehicle side via a voltage regulator or a capacitor.

[0494] In the in-vehicle device 920 shown in Fig. 34 , for example, the communication control unit 115 in Fig. 6 , the communication control unit 215 in Fig. 7 , and the communication control unit 312 in Fig. 8 may be implemented in the wireless communication interface 933. For example, processing programs corresponding to the flowcharts in Figs. 13 , 14 , 19 , 20 , 22 , 26 , 27 , 30 , and 31 may be executed in the wireless communication interface 933. Furthermore, at least some of these functions may be implemented in the processor 921.

[0495] The wireless communication interface 933 may also operate as the AP 100 (communication device), the STA 200 (terminal device), and the control device 300 described above, and provide wireless connection to a terminal owned by a user 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 use CarPlay (registered trademark) or Android Auto (registered trademark). 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 wireless LAN method using Wi-Fi Direct.

[0496] The in-vehicle device 920 may operate as a wireless AP (software AP) by the processor 921 executing an AP function at the application level. The wireless communication interface 933 may have a wireless AP function. The processor 921 or the wireless communication interface 933 may have a tethering function that uses a wireless LAN system and a cellular communication system, and may transmit payload data received via the cellular communication system via the wireless LAN system, or may transmit payload data received via the wireless LAN system via the cellular communication system. The in-vehicle device 920 may have the tethering function enabled by user input.

[0497] Furthermore, the present technology may be realized 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 rotation speed information, information about the vehicle-side battery, or malfunction information, and output the generated data to the in-vehicle network 941, and the processor 921 or the wireless communication interface 933 may control any of the functions of the above-described embodiments based on the vehicle-side data acquired via the in-vehicle network 941.

[0498] <Configuration example of wireless AP> Fig. 35 is a block diagram showing an example of a schematic configuration of a wireless AP 950 to which the present technology is applied. Fig. 35 is described as an example of the configuration of the wireless AP 950, but is not limited to this and may be an example of the configuration of the various devices and functions described above.

[0499] The wireless AP 950 includes a controller 951, a memory 952, an input device 954, a display device 955, a network interface 957, a wireless communication interface 963, an antenna switch 964, and an antenna 965. The wireless AP 950 may include all or some of the above.

[0500] The controller 951 may be, for example, a CPU or a DSP (Digital Signal processor) and operates various functions of the IP (Internet Protocol) layer and higher layers of the wireless AP 950 (e.g., access restriction, routing, encryption, firewall, and log management).

[0501] The memory 952 includes RAM and ROM, and stores programs executed by the controller 951 and various control information (for example, a terminal list, a routing table, an encryption key, security settings, and logs).

[0502] The input device 954 includes, for example, buttons and switches, and receives operations from the user. For example, the input device 954 may be configured to input a confirmation or response to information output from the display device 955. Furthermore, the input device 954 may be configured to input, by user operation, switching the wireless function on / off and switching between the router function and the access point function.

[0503] The display device 955 includes an LED lamp or the like and displays the operation status of the wireless AP 950. The display device 955 may display information related to the present technology, for example, information related to handover.

[0504] The network interface 957 is a wired communication interface for connecting the wireless AP 950 to a wired communication network 958. The network interface 957 may have multiple connection terminals. The network interface 957 may output payload data included in a wireless signal input from the wireless communication interface 963 as a wired signal, or may receive payload data output as a wireless signal from the wireless communication interface 963 as a wired signal. The network interface 957 may input and output wired signals in parallel with or independently of the wireless communication interface 963 inputting and outputting wireless signals. The wired communication network 958 may be a LAN such as Ethernet (registered trademark) or a WAN (Wide Area Network).

[0505] 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 successor standards, and provides wireless connection to nearby terminals as an AP. When the wireless AP 950 is installed in a cellular communication base station or a femtocell, the wireless communication interface 963 may support other types of wireless communication systems, such as 3GPP cellular communication systems such as 2G, 3G, 4G, 5G, and 6G, in addition to the wireless LAN system. The wireless communication interface 963 may be a one-chip module that supports multiple wireless communication systems, or a combination of modules that support some of the wireless communication systems.

[0506] The wireless communication interface 963 typically includes a baseband processor, an RF circuit, a power amplifier, and the like.

[0507] The wireless communication interface 963 may be a one-chip module that integrates a memory that stores a communication control program, a processor that executes the program, or related circuits.

[0508] The antenna switch 964 switches the connection destination of the antenna 965 between multiple circuits included in the wireless communication interface 963 (for example, circuits for different wireless communication methods, or transmission system circuits and reception system circuits).

[0509] The antenna 965 has a single or multiple antenna elements (e.g., multiple antenna elements constituting a MIMO (Multiple Input Multiple Output) antenna, or multiple antenna elements constituting an array antenna) and is used for transmitting and receiving radio signals via the wireless communication interface 963.

[0510] In the wireless AP 950 shown in Fig. 35 , for example, the communication control unit 115 in Fig. 6 , the communication control unit 215 in Fig. 7 , and the communication control unit 312 in Fig. 8 may be implemented in the wireless communication interface 963. For example, processing programs corresponding to the flowcharts in Figs. 13, 14, 19, 20, 22, 26, 27, 30, and 31 may be executed in the wireless communication interface 963. Furthermore, at least some of these functions may be implemented in the controller 951.

[0511] The above-described embodiment shows an example for realizing the present technology, and the matters in the embodiment correspond to the matters specifying the invention in the claims. Similarly, the matters specifying the invention in the claims correspond to the matters in the embodiment of the present technology having the same title. However, the present technology is not limited to the embodiment, and can be realized by applying various modifications to the embodiment without departing from the gist of the present technology.

[0512] Furthermore, some or all of the communication devices, terminal devices, and control devices described in the above embodiments may be realized as, for example, semiconductor chips (ICs (Integrated Circuits)) having wireless communication control functions. They may also be realized as a single semiconductor chip equipped with multiple functions, such as a SoC (System on Chip), or as a combination of multiple semiconductor chips each having a single function, such as a processor. Furthermore, they may be realized by combining multiple SoCs, or by combining a semiconductor chip with a single function and a SoC. They may also be realized by semiconductor chips such as ASICs (Application Specific Integrated Circuits) dedicated to implementing each unit, or by a combination of a general-purpose processor with software or firmware, or by semiconductor chips such as FPGAs (Field Programmable Gate Arrays).

[0513] Furthermore, the processing procedures described in the above embodiments may be regarded as a method having a series of these procedures, or as a program for causing this computer to execute these procedures or a recording medium for storing the program.

[0514] Examples of the recording medium that can be used include a CD (Compact Disc), an MD (MiniDisc), a DVD (Digital Versatile Disc), a memory card, and a Blu-ray (registered trademark) Disc.

[0515] In this specification, a system refers to a collection of multiple components (devices, modules (components), etc.), regardless of whether all of the components are contained in the same housing. Therefore, multiple devices housed in separate housings and connected via a network, and a single device housed in a single housing with multiple modules, are both systems.

[0516] Furthermore, the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0517] The embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present technology.

[0518] For example, the present technology can be configured as a cloud computing system in which a single function is shared and processed collaboratively by a plurality of devices via a network.

[0519] Furthermore, each step described in the above flowchart can be executed by one device, or can be shared and executed by a plurality of devices.

[0520] Furthermore, when one step includes multiple processes, the multiple processes included in that one step can be executed by one device or can be shared and executed by multiple devices.

[0521] <<6. Conclusion>> Although the embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present disclosure. Furthermore, components of different embodiments and modifications may be combined as appropriate.

[0522] Furthermore, the effects of the embodiments described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0523] Note that the present technology may also be configured as follows. (1) A communication device including a control unit that controls transmission of first packet data to a terminal device, wherein the control unit requests a first communication device to transmit second packet data to the terminal device, and notifies the first communication device of at least one of first information regarding the second packet data and second information regarding the transmission of the second packet data. (2) The communication device according to (1), wherein the second packet data includes at least one of one or more first packets included in the first packet data. (3) The communication device according to (1) or (2), wherein the control unit notifies the first communication device of the request signal requesting transmission of the second packet data, including at least one of the first information and the second information. (4) The communication device according to any one of (1) to (3), wherein the first information includes information for sharing the second packet data with the first communication device. (5) The communication device according to any one of (1) to (4), wherein the first information includes information on the number of packets included in the second packet data and information on timing for notifying the first communication device of the second packet data. (6) The communication device according to any one of (1) to (5), wherein the second information includes information on generation of a data frame of the second packet data. (7) The communication device according to any one of (1) to (6), wherein the second information includes at least one of information on a sequence number of a second packet included in the second packet data, information on an access category of the second packet, and control information of the second packet. (8) The communication device according to any one of (1) to (7), wherein the control unit notifies the first communication device of all of one or more first packets included in the first packet data. (9) The communication device according to (8), wherein the first communication device transmits the second packet data including a failed packet, among the first packets, that the terminal device failed to receive, to the terminal device.(10) The communication device according to (8) or (9), wherein the control unit notifies the first communication device of information regarding a failed packet that the terminal device failed to receive from among the first packets. (11) The communication device according to (8) or (9), wherein the first communication device receives a response signal corresponding to the first packet data transmitted by the terminal device. (12) The communication device according to (8), wherein the first communication device transmits the second packet data including all of the first packets to the terminal device. (13) The communication device according to any one of (1) to (7), wherein the control unit notifies the first communication device of a failed packet that the terminal device failed to receive from among one or more first packets included in the first packet data. (14) The communication device according to any one of (1) to (8), wherein the control unit notifies the first communication device of information regarding a wait request time for requesting the first communication device to wait to receive a packet to be transmitted by being included in the second packet data. (15) The communication device according to (14), wherein the control unit determines, from one or more first packets included in the first packet data, the first packet to be notified to the first communication device before receiving a response signal to the first packet data from the terminal device, in accordance with the standby request time. (16) The communication device according to (14), wherein the control unit receives, from the first communication device, information regarding a standby time during which the first communication device waits to receive the packet. (17) The communication device according to (16), wherein the control unit determines, from one or more first packets included in the first packet data, the first packet to be notified to the first communication device before receiving a response signal to the first packet data from the terminal device, in accordance with the standby time. (18) The communication device according to any one of (14) to (17), wherein the control unit notifies the first communication device of a failed packet that the terminal device has failed to receive, among one or more first packets included in the first packet data, and that has not been notified to the first communication device before receiving a response signal to the first packet data.(19) The communication device according to any one of (1) to (18), wherein the control unit requests the first communication device to transmit the second packet data using a TXOP acquired by the control unit. (20) The communication device according to any one of (1) to (19), wherein the control unit receives from the first communication device a response including a status of transmission of the second packet data to the terminal device. (21) A communication device comprising: a control unit that acquires from the first communication device a request to transmit second packet data to a terminal device that receives the first packet data from the first communication device, and acquires from the first communication device at least one of first information regarding the second packet data and second information regarding the transmission of the second packet data. (22) The communication device according to (21), wherein the control unit starts transmitting the second packet data at a timing instructed by the first communication device during the period of the TXOP acquired by the first communication device. (23) A terminal device comprising: a control unit that performs control to receive first packet data from a first communication device, control to transmit a response signal corresponding to the first packet data to the first communication device and a second communication device different from the first communication device, and control to receive second packet data in response to the response signal from the second communication device. (24) The terminal device according to (23), wherein the control unit performs control to transmit the response signal to the second communication device in accordance with an instruction from the first communication device. (25) A communication system comprising a first communication device, a second communication device, and a terminal device, wherein the first communication device comprises a first control unit that controls transmission of first packet data to the terminal device, the first control unit requests the first communication device to transmit second packet data to the terminal device, and notifies the first communication device of at least one of first information regarding the second packet data and second information regarding the transmission of the second packet data, and the second communication device comprises a second control unit that transmits the second packet data to the terminal device in response to a request from the first communication device.(26) A communication method comprising: transmitting first packet data to a terminal device; requesting a first communication device to transmit second packet data to the terminal device; and notifying the first communication device of at least one of first information regarding the second packet data and second information regarding the transmission of the second packet data. (27) A communication method comprising: acquiring from the first communication device a request to transmit second packet data to a terminal device receiving the first packet data from the first communication device; and acquiring from the first communication device at least one of first information regarding the second packet data and second information regarding the transmission of the second packet data. (28) A communication method comprising: receiving first packet data from a first communication device; transmitting a response signal corresponding to the first packet data to the first communication device and a second communication device different from the first communication device; and receiving second packet data in response to the response signal from the second communication device. (29) A communication method in a communication system including a first communication device, a second communication device, and a terminal device, the communication method including: the first communication device transmitting first packet data to the terminal device; the first communication device requesting the first communication device to transmit second packet data to the terminal device; the first communication device notifying the first communication device of at least one of first information regarding the second packet data and second information regarding the transmission of the second packet data; and the second communication device transmitting the second packet data to the terminal device in response to the request from the first communication device.

[0524] 10 Communication system 100 AP 110, 210, 310, 809 Communication unit 111, 211, 311 Data processing unit 112, 212 Signal processing unit 113, 213 Wireless interface unit 114, 214 Amplification unit 115, 215, 312 Communication control unit 116, 216, 313 Communication storage unit 120, 320 Backhaul communication unit 130, 220, 330 Storage unit 140, 230, 340 Control unit 200 STA 300 Control device 400 Router

Claims

1. A communication device comprising a control unit that controls the transmission of first packet data to a terminal device, wherein the control unit requests a first communication device to transmit second packet data to the terminal device, and notifies the first communication device of at least one of first information regarding the second packet data and second information regarding the transmission of the second packet data.

2. The communication device according to claim 1, wherein the second packet data includes at least one of the one or more first packets included in the first packet data.

3. The communication device according to claim 1, wherein the control unit notifies the first communication device by including at least one of the first information and the second information in a request signal requesting the transmission of the second packet data.

4. The communication device according to claim 1, wherein the first information includes information for sharing the second packet data with the first communication device.

5. The communication device according to claim 1, wherein the first information includes information regarding the number of packets contained in the second packet data and information regarding the timing of notifying the first communication device of the second packet data.

6. The communication device according to claim 1, wherein the second information includes information relating to generation of a data frame of the second packet data.

7. The communication device of claim 1, wherein the second information includes at least one of information regarding a sequence number of a second packet included in the second packet data, information regarding an access category of the second packet, and control information of the second packet.

8. The communication device according to claim 1, wherein the control unit notifies the first communication device of all of the one or more first packets included in the first packet data.

9. The communication device according to claim 8, wherein the first communication device transmits the second packet data including a failed packet of the first packets that the terminal device failed to receive to the terminal device.

10. The communication device according to claim 8, wherein the first communication device receives a response signal corresponding to the first packet data transmitted by the terminal device.

11. The communication device according to claim 1, wherein the control unit notifies the first communication device of a failed packet that the terminal device failed to receive, out of one or more first packets included in the first packet data.

12. The communication device according to claim 1, wherein the control unit notifies the first communication device of information regarding a waiting request time for requesting the first communication device to wait in order to receive a packet to be included in the second packet data and transmitted.

13. The communication device according to claim 12, wherein the control unit determines, from among one or more first packets included in the first packet data, the first packet to be notified to the first communication device before receiving a response signal to the first packet data from the terminal device, in accordance with the waiting request time.

14. The communication device according to claim 12, wherein the control unit receives, from the first communication device, information regarding a waiting time for the first communication device to wait to receive the packet.

15. The communication device according to claim 14, wherein the control unit determines, according to the waiting time, which of the one or more first packets included in the first packet data to notify the first communication device of before receiving a response signal to the first packet data from the terminal device.

16. The communication device according to claim 12, wherein the control unit notifies the first communication device of a failed packet, among one or more first packets included in the first packet data, that the terminal device has failed to receive and that has not been notified to the first communication device before receiving a response signal to the first packet data.

17. The communication device according to claim 1, wherein the control unit requests the first communication device to transmit the second packet data using a TXOP acquired by the control unit.

18. The communication device according to claim 1, wherein the control unit receives a response from the first communication device that includes whether or not the second packet data can be transmitted to the terminal device.

19. A communications device comprising: a control unit that acquires, from a first communications device, a request to transmit second packet data to a terminal device that receives first packet data from the first communications device; and acquires, from the first communications device, at least one of first information regarding the second packet data and second information regarding the transmission of the second packet data.

20. A terminal device comprising: a control unit that performs control to receive first packet data from a first communication device; control to transmit a response signal corresponding to the first packet data to the first communication device and a second communication device different from the first communication device; and control to receive second packet data corresponding to the response signal from the second communication device.

Images