Controller device, base station, terminal device, communication method, and control method

Abstract

[Problem] To improve communication efficiency between a terminal device and a base station. [Solution] A controller device according to the present disclosure comprises: a communication unit that transmits, to a first base station among a plurality of base stations, request information for requesting measurement of a data transmission time with one or more second base stations among the plurality of base stations, and receives measurement information of the data transmission time as a response to the request information; and a control unit that determines a third base station from among the one or more second base stations on the basis of the measurement information of the data transmission time, and performs control such that the other of the first base station and the third base station receives second data from one of the first base station and the third base station and transmits the second data to the terminal device, the second data is the same as the first data transmitted from the one base station to the terminal device.

Description

Technical Field

[0001] This disclosure relates to controller devices, base stations, terminal devices, communication methods, and control methods. Background Technology

[0002] In recent years, numerous scenarios have emerged in various use cases such as homes, offices, and factories where multiple access points (APs) are deployed to create highly reliable, high-speed Wi-Fi networks. In such environments with multiple APs, STAs moving around the network must perform handover processes to change their target AP. If the handover is not properly executed, resulting in persistent connections to APs exhibiting low link strength or time spent on handover processing, data transmission may fail for a period of time. This can significantly negatively impact the quality of service (QoS) of applications requiring highly reliable, low-latency data communication.

[0003] A seamless handover operation using the MLD entity defined in IEEE 802.11be / Multi-Link Operation is being discussed as a method to address the aforementioned situation (refer to Non-Patent Document 1). In this operation, the MLD entity in the control device manages the corresponding AP in a network, enabling the corresponding AP to share the encryption key used by the STA. Then, when it is determined that a handover should be performed, a transition phase is executed. During the transition phase, before the handover is complete, the handover source AP sends the same data to the STA to surrounding APs (such as the handover destination AP), and not only the handover source AP but also the surrounding APs send data to the STA. This allows for the switching of the AP to which the STA is connected without interrupting data communication, even when the STA is moving around.

[0004] Currently, the number of APs that such an MLD entity can manage at one time is undetermined, and it is possible that an upper limit will be set on the number of APs allowed to be managed (the number of APs allowed to connect to the MLD entity). In this case, there is room for discussion regarding which APs the AP MLD entity should manage or how to determine the set of APs for seamless roaming. In particular, if the data transfer from the source AP to surrounding APs during the transition phase takes a long time, it will reduce communication efficiency, thus failing to achieve the expected effects provided by seamless handover.

[0005] Citation List

[0006] Patent documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2022-546889

[0008] Non-patent literature

[0009] Non-patent literature 1: IEEE 802.11-22 / 1910r0 Summary of the Invention

[0010] Technical issues

[0011] The purpose of this disclosure is to improve the efficiency of communication between terminal devices and base stations.

[0012] Solution to the problem

[0013] The controller device according to this disclosure includes: a communication unit that sends a request message to a first base station included in a plurality of base stations, the request message being for requesting measurement of a data transmission time period performed between the first base station and at least one second base station included in the plurality of base stations, and receives measurement information regarding the data transmission time period as a response to the request message; and a control unit that determines a third base station from the at least one second base station based on the measurement information regarding the data transmission time period, and performs control such that one of the first base station and the third base station receives second data from the other of the first base station and the third base station and transmits the second data to a terminal device, the second data being identical to the first data transmitted from the other of the first base station and the third base station to the terminal device.

[0014] According to this disclosure, the base station is one of a plurality of base stations, comprising: a communication unit that receives request information for requesting measurement of a data transmission time period performed between the base station and another base station included in the plurality of base stations, and receives data for measuring the data transmission time period from the other base station based on the request information, or sends data for measurement to the other base station based on the request information; and a control unit that measures the data transmission time period performed between the base station and the other base station based on the time of receiving the data for measurement, wherein the communication unit sends measurement information regarding the measurement of the data transmission time period as a response to the request information, and when the base station selects a base station to be paired with the other base station as the destination for the response transmission of the measurement information, the communication unit receives second data from the other base station and sends second data to a terminal device, the second data being the same as the first data sent from the other base station to the terminal device, or the communication unit sends fourth data to the other base station that is the same as the third data sent from the base station to the terminal device.

[0015] The terminal device according to this disclosure includes: a communication unit that receives first data from a first base station and receives second data from a second base station capable of receiving the same data as the first data from the first base station; and a control unit that determines whether the second data is the same as the first data, and when the second data is the same as the first data, measures a data transmission time period performed between the first base station and the second base station, the measurement being performed based on first information related to the first data and second information related to the second data, wherein the communication unit sends measurement information, which is information about the measurement of the data transmission time period, to at least one of the first base station and the second base station, or to a controller device controlling the first base station and the second base station. Attached Figure Description

[0016] Figure 1 An example of the overall configuration of a wireless communication system according to this disclosure is illustrated.

[0017] Figure 2 This is a block diagram of an example AP used as a base station according to this disclosure.

[0018] Figure 3 This is a block diagram of an example STA used as a terminal device according to this disclosure.

[0019] Figure 4 This is a block diagram of an example controller device according to the present disclosure.

[0020] Figure 5 The illustration shows an example of a handover process based on relevant technologies.

[0021] Figure 6 An example of seamless roaming processing is illustrated.

[0022] Figure 7 This is a diagram used to describe the problems that occur when performing seamless roaming.

[0023] Figure 8 This is a diagram illustrating a solution strategy for the problem of seamless roaming.

[0024] Figure 9 This is a diagram of the entire sequence in this disclosure.

[0025] Figure 10 It is a diagram of the sequence of measurement phases.

[0026] Figure 11 The illustration shows an example of the configuration of a DFDM request frame.

[0027] Figure 12 The illustration shows an example of test group configuration.

[0028] Figure 13 The illustration shows an example of the configuration of a DFDM response frame.

[0029] Figure 14 This is a diagram of the processing sequence for measuring packet transmission time periods during the transition phase in the data Tx phase.

[0030] Figure 15 The illustration shows an example of data grouping configuration.

[0031] Figure 16 This is a flowchart illustrating an example of an operation to measure a transmission time period, which is performed by the STA.

[0032] Figure 17 The illustration shows an example of a network in a home grid scenario.

[0033] Figure 18 The illustration shows an example of a network in which multiple APs perform a joint Tx.

[0034] Figure 19 This is a block diagram illustrating an example of the configuration of computer hardware that uses a program to perform a series of processes according to this embodiment.

[0035] Figure 20 This is a block diagram illustrating an example of a smartphone configuration for which this embodiment is applied.

[0036] Figure 21 This is a block diagram illustrating an example of a vehicle-mounted device to which this embodiment is applied.

[0037] Figure 22 This is a block diagram illustrating an example of a configuration of a wireless AP to which this embodiment is applied. Detailed Implementation

[0038] Embodiments of the present disclosure will now be described below with reference to the accompanying drawings. It should be noted that in the specification and drawings, structural elements including substantially the same function are denoted by the same reference numerals to appropriately omit their description. The illustrations in the drawings are simplified illustrations, and in addition to the illustrated structural elements, structural elements necessary for the implementation are appropriately provided. Furthermore, unless otherwise specified, when terms such as “first” and “second” are used in the specification or claims, these terms do not indicate any order or degree of importance, but are used to distinguish one structural element from another.

[0039] Figure 1An example of the overall configuration of a wireless communication system 1 according to this disclosure is illustrated. System 1 includes three access points (APs, base stations) 100_1, 100_2, and 100_3, a station (STA, terminal device) 200, a router 400, and a controller device 300 for controlling the respective APs. Router 400 is connected to a wide area network (WAN) (not shown). APs 100_1 to 100_3 are referred to as AP 100 unless otherwise distinguished.

[0040] The controller device 300 includes an AP multilink device (MLD) entity 310, which includes functions for performing a portion of the MAC processing performed by the AP, such as establishing a connection with a STA attached to the AP attached to the controller device 300, and generating encryption keys. An AP connected to the AP MLD entity 310 is referred to as an "AP belonging to the AP MLD". The AP MLD entity can also be simply referred to as the AP MLD.

[0041] Router 400 and each of APs 100_1 to 100_3 are connected to wired backhaul network 500. Packets 200 to be sent to STA 200 are sent from router 400 to APs connected to STA 200 via backhaul network 500, and thereafter, the packets are wirelessly transmitted from APs to STA 200. In this embodiment, backhaul network 500 is a wired network, but it can be a wireless network.

[0042] Through the control link (reference) Figure 1 (As shown by the dashed arrows), the controller device 300 or AP MLD entity 310 exchanges information with each of the APs 100_1 to 100_3 under the control of the controller device 300 or AP MLD entity 310. In this embodiment, the control link is a wireless link, but the control link can also be a wired link. A group of APs managed by the controller device 300 is referred to hereinafter as a controller group. In this example, the controller group is formed by APs 100_1 to 100_3. The controller device 300 can control and manage the APs included in a controller group through the network layer and application layer above the MAC layer. However, the controller device 300 is not allowed to manage or control the processing performed at or below the MAC layer.

[0043] Regarding the APs attached to AP MLD entity 310, AP MLD entity 310 can manage and control processing at the MAC layer and below. An upper limit can be set on the number of APs allowed to connect to AP MLD entity 310. In this embodiment, the upper limit is assumed to be two.

[0044] In this embodiment, firstly, it is assumed that each of AP 100_1 and 100_2 is connected to (belongs to) AP MLD entity 310, and AP 100_3 is not connected to (not belonging to) AP MLD entity 310.

[0045] A group of APs belonging to an AP MLD entity 310 is called an MLD group. In this example, the MLD group consists of AP100_1 and 100_2. Regarding the APs belonging to a group (MLD group) of AP MLD entity 310, AP MLD entity 310 can manage and control a portion of the processing in the MAC layer. Generally, an MLD group is a subset of a controller group.

[0046] STA 200 is connected to AP 100_1 to communicate with AP 100_1. When STA 200 moves in the direction of AP 100_2 or AP 100_3, in order to maintain communication during the movement of STA 200, it is necessary to hand over STA 200 to AP 100_2 or AP 100_3 (connection switch). The feature of this embodiment is that STA 200 can be seamlessly handed over without interrupting communication.

[0047] Note that this embodiment is not limited to Figure 1 The system configuration shown. For example, the number of AP MLD entities or the number of APs included in the controller device 300 may be greater than or equal to the values ​​exemplified in this embodiment. For example, in Figure 1 In the example shown, the number of AP MLD entities is one, but the number of AP MLD entities can be two or more. Additionally, the maximum number of APs belonging to an APMLD entity can be three or more.

[0048] Figure 2 This is a block diagram of an AP 100 used as a base station (wireless communication device) according to this embodiment. The AP 100 mainly includes a communication processing unit 110, a control unit 130, a storage unit 140, an antenna 150, and a backhaul communication unit 160.

[0049] The communication processing unit 110 performs processing for wireless communication with the STA 200, which is used as another wireless communication device (including a wireless communication unit) to establish a connection with. The communication processing unit 110 includes a communication control unit 111, a communication storage unit 112, and a wireless communication unit 125. The wireless communication unit 125 includes a data processing unit 121, a signal processing unit 122, a wireless interface unit 123, and an amplification unit 124. The communication unit of the base station according to this embodiment at least partially includes functions performed by at least one of the wireless communication unit 125 or the backhaul communication unit 160.

[0050] The communication control unit 111 controls the operations performed by the corresponding structural elements and the information transmission performed between the structural elements. In addition, the communication control unit 111 delivers control information and management information to be reported to another wireless communication device to the data processing unit 121.

[0051] The communication storage unit 112 stores information used by the communication control unit 111. Additionally, the communication storage unit 112 stores data to be transmitted (or data packets) and received data (or received data packets). A transmission buffer storing the data to be transmitted is included in the communication storage unit 112.

[0052] During transmission, the data processing unit 121 performs sequence management on the information to be transmitted. Examples of the information to be transmitted include data stored in the communication storage unit 112 and control and management information received from the communication control unit 111. After performing, for example, encryption processing on the information to be transmitted, the data processing unit 121 adds a Media Access Control (MAC) header and error detection code to the information to be transmitted and generates a frame. Additionally, the data processing unit 121 can perform processing that couples multiple frames. During reception, the data processing unit 121 performs decoupling processing on the MAC header of the received frame, performs analysis, and performs error detection. Furthermore, the data processing unit 121 performs reordering processing in response to a retransmission request. The frame type can be any of a data frame, a management frame, or a control frame.

[0053] During transmission, the signal processing unit 122 performs operations such as encoding, interleaving, and modulation on the frame, and adds a physical header to generate a symbol stream. During reception, the signal processing unit 122 analyzes the physical header and performs operations such as demodulation, deinterleaving, and decoding on the symbol stream to generate a frame. Additionally, the signal processing unit 122 performs estimation processing and spatial separation processing on the complex channel characteristics when necessary.

[0054] During transmission, the wireless interface unit 123 performs digital-to-analog signal conversion, filtering, up-conversion, and phase control on the symbol stream, and generates a transmission signal. During reception, the wireless interface unit 123 performs down-conversion, filtering, and analog-to-digital signal conversion on the received signal, and generates a symbol stream.

[0055] The amplifier 124 amplifies the signal input via the wireless interface 123 or the antenna 150. A portion of the amplifier 124 may be a structural element external to the communication unit. Alternatively, a portion of the amplifier 124 may be included within the wireless interface 123.

[0056] Note that an example of providing an amplification unit 124 and an antenna 150 has been described as a SISO configuration. However, a configuration using multiple sets of antennas 150 and amplification units 124 to perform MIMO transmission and reception processing can also be adopted. Furthermore, a configuration including multiple sets of radio interface units, signal processing units, and data processing units can be adopted, enabling parallel operation of multiple links or multiple frequency channels.

[0057] Note that the diagram assumes the communication processing unit 110 includes one IC. However, the IC configuration is not limited to this. For example, the wireless interface unit can be configured with different ICs.

[0058] Control unit 130 controls communication processing unit 110 and communication control unit 111. Furthermore, control unit 130 can perform a portion of the operations performed by communication control unit 111 on behalf of communication control unit 111. Additionally, communication control unit 111 and control unit 130 can be formed as a single block. According to this embodiment, the control unit at least partially includes functions performed by at least one of communication control unit 111 or control unit 130.

[0059] Storage unit 140 stores information used by control unit 130 and communication processing unit 110. Furthermore, storage unit 140 can perform a portion of the operations performed by communication storage unit 112, replacing communication storage unit 112. Storage unit 140 and communication storage unit 112 can be formed as a single block.

[0060] The backhaul communication unit 160 communicates with another AP, router 400, and controller device 300 or APMLD entity 310 via the backhaul network 500. For example, the backhaul communication unit 160 decrypts packets obtained from the backhaul network 500 and delivers the decrypted packets to the communication processing unit 110 via the control unit 130. Regarding the form of the packets delivered here, the packets may be in a state where the IP header remains unchanged (access point mode), or they may be in a state where the IP header has been decrypted and removed by the backhaul communication unit 160 (router mode). In this embodiment, communication with the controller device 300 is performed via the backhaul communication unit 160. However, communication with the controller device 300 may also be performed via the wireless communication unit 125.

[0061] In the above configuration of AP 100, when the backhaul communication unit 160 or the wireless communication unit 125 receives a request message from the controller device 300 controlling AP 100 requesting measurement of the data transmission time period performed with another AP, the control unit 130 or the communication control unit 111 performs control to measure the data transmission time period performed with the other AP based on the request message. Specifically, the control unit 130 or the communication control unit 111 performs control to receive data (such as frames or data packets) for measuring the data transmission time period from the other AP based on the request message, or to send the data for measurement to the other AP based on the request message.

[0062] When the backhaul communication unit 160 receives measurement data from another AP, the control unit 130 or the communication control unit 111 measures the data transmission time period performed with that other AP station based on the time the measurement data was received. When measuring the data transmission time period, a timestamp (transmission time information) included in the measurement data can be used. The control unit 130 or the communication control unit 111 performs control, causing the backhaul communication unit 160 to send measurement information regarding the measurement of the data transmission time period as a response to a request. The data transmission time period corresponds to the time period from when data is acquired from the data transmission source AP to when the data is received by the data transmission destination AP. Therefore, from the perspective of the data transmission destination AP, the time when the data is received by the data transmission destination AP is later than that of the data transmission source AP. Therefore, the data transmission time period is also referred to as the delay time.

[0063] When the controller device 300 at the destination of the measurement information response selects the AP of the control unit 130 or the communication control unit 111 as the AP to be used in combination with another AP (i.e., when the AP of the control unit 130 or the communication control unit 111 is classified into the same MLD group as another AP), the control unit 130 or the communication control unit 111 then performs control such that the backhaul communication unit 160 receives the same data from the other AP as the data sent from the other AP to the STA 200, and causes the received second data to be sent from the wireless communication unit 125 to the STA 200. Alternatively, the control unit 130 or the communication control unit 111 performs control such that the backhaul communication unit 160 sends the same data to the other AP as the data sent from the AP of the control unit 130 or the communication control unit 111 to the STA 200.

[0064] This control prevents communication interruptions performed by STA 200 when STA 200 is transferred from another AP to the AP of control unit 130 or communication control unit 111, or from the AP of control unit 130 or communication control unit 111 to that other AP.

[0065] Figure 3This is a block diagram of STA 200, which is used as a terminal device (wireless communication device) according to this embodiment. STA 200 mainly includes a communication processing unit 210, a control unit 230, a storage unit 240, and an antenna 250.

[0066] The communication processing unit 210 performs processing for wireless communication with the AP 100, which is used as a wireless communication device (including a wireless communication unit) to which the STA 200 is connected, or another STA. Additionally, the communication processing unit 210 can perform processing for wireless communication with the controller device 300. The communication processing unit 210 includes a communication control unit 211, a communication storage unit 212, and a wireless communication unit 225. The wireless communication unit 225 includes a data processing unit 221, a signal processing unit 222, a wireless interface unit 223, and an amplification unit 224. According to this embodiment, the communication unit of the STA 200 at least partially includes the functions performed by the wireless communication unit 225.

[0067] The communication control unit 211 controls the operations performed by the corresponding structural elements and the information transmission performed between the structural elements. In addition, the communication control unit 211 delivers control information and management information to be reported to another wireless communication device to the data processing unit 221.

[0068] The communication storage unit 212 stores information used by the communication control unit 211. Additionally, the communication storage unit 212 stores data to be transmitted (or data packets) and received data (or received data packets). A transmission buffer storing the data to be transmitted is included in the communication storage unit 212.

[0069] During transmission, the data processing unit 221 performs sequence management on the information to be transmitted. Examples of the information to be transmitted include data stored in the communication storage unit 212 and control and management information received from the communication control unit 211. After performing, for example, encryption processing on the information to be transmitted, the data processing unit 221 adds a Media Access Control (MAC) header and error detection code to the information to be transmitted and generates a frame. Additionally, the data processing unit 221 can perform processing that couples multiple frames. During reception, the data processing unit 221 performs decoupling processing on the MAC header of the received frame, performs analysis, and performs error detection. Furthermore, the data processing unit 221 performs reordering processing in response to a retransmission request. The frame type can be any of a data frame, a management frame, or a control frame.

[0070] During transmission, the signal processing unit 222 performs operations such as encoding, interleaving, and modulation on the frame, and adds a physical header to generate a symbol stream. During reception, the signal processing unit 222 analyzes the physical header and performs operations such as demodulation, deinterleaving, and decoding on the symbol stream to generate a frame. Additionally, the signal processing unit 222 performs estimation processing and spatial separation processing on the complex channel characteristics when necessary.

[0071] During transmission, the wireless interface unit 223 performs digital-to-analog signal conversion, filtering, up-conversion, and phase control on the symbol stream, and generates a transmission signal. During reception, the wireless interface unit 223 performs down-conversion, filtering, and analog-to-digital signal conversion on the received signal, and generates a symbol stream.

[0072] The amplifier 224 amplifies the signal input via the wireless interface 223 or the antenna 150. A portion of the amplifier 224 may be a structural element external to the communication unit. Alternatively, a portion of the amplifier 224 may be included within the wireless interface 223.

[0073] Note that an example of providing a combination of amplifier 224 and antenna 150 has been described as a SISO configuration. However, configurations using multiple combinations of antenna 150 and amplifier 224 to perform MIMO transmission and reception processing can also be employed. Furthermore, configurations including multiple combinations of wireless interface, signal processing, and data processing units can be used, enabling parallel operation of multiple links or multiple frequency channels.

[0074] Note that the diagram assumes the communication processing unit 210 includes one IC. However, the IC configuration is not limited to this. For example, the wireless interface unit can be configured with different ICs.

[0075] The control unit 230 controls the communication processing unit 211 and the communication control unit 211. Furthermore, the control unit 230 can perform a portion of the operations executed by the communication control unit 211 on behalf of the communication control unit 211. Additionally, the communication control unit 211 and the control unit 230 can be configured as a single module.

[0076] Storage unit 240 stores information used by control unit 230 and communication processing unit 210. Furthermore, storage unit 240 can perform a portion of the operations performed by communication storage unit 212 on behalf of communication storage unit 212. Storage unit 240 and communication storage unit 212 can be formed as a single block.

[0077] In the above configuration of STA 200, the communication control unit 211 or the control unit 230 can perform processing to measure the data transmission time period (delay time) performed between APs during the transition phase provided when STA 200 is handed over.

[0078] More specifically, during the transition phase, when the wireless communication unit 225 receives first data from a first AP (e.g., AP 100_1) and second data from a second AP (e.g., AP 100_2) that can receive the same data as the first data from the first AP, the communication control unit 211 or the control unit 230 determines whether the second data is the same as the first data (such as a frame or data packet). For example, it can be determined whether the second data is the same as the first data based on whether a first sequence number included in the first data matches a second sequence number included in the second data.

[0079] When the second data is the same as the first data, the communication control unit 211 or the control unit 230 measures the data transmission time period based on the first information about the first data and the second information about the second data. The data transmission time period is the time period from sending the first data to the second base station to the time when the first data is received by the second base station.

[0080] As an example, the first information may include the time of sending the first data, the second information may include the time of sending the second data, and the communication control unit 211 or the control unit 230 may measure the data transmission time period based on the difference between the time of sending the first data and the time of sending the second data.

[0081] Alternatively, the first information may include the reception time of receiving the first data, the second information may include the reception time of receiving the second data, and the communication control unit 211 or the control unit 230 may estimate the data transmission time period based on the difference between the reception time of receiving the first data and the reception time of receiving the second data.

[0082] The communication control unit 211 or the control unit 230 performs control, causing measurement information regarding the data transmission time period to be transmitted to the controller device 300 via the wireless communication unit 225 and at least one of the first AP or the second AP. Alternatively, the measurement information can be directly fed back to the controller device 300.

[0083] Figure 4 This is a block diagram of the controller device 300. The controller device 300 mainly includes a control unit 350 and a communication unit 360. The control unit 350 includes a network control unit 330 and a data processing control unit 320. The communication unit 360 is equipped with an antenna 340.

[0084] Network control unit 330 controls and manages APs in the same group (controller group) through the network layer and application layer. Figure 1The APs shown are 100_1 to 100_3. For example, the network control unit 330 collects information about STAs connected to the affiliated APs (information about Layer 3 and higher layers), performance information about the STAs (such as throughput and latency during data transmission), and load information about the APs; and optimizes network information about the STAs and the APs to which they are connected. The handover process according to this embodiment can also be performed by the network control unit 330.

[0085] The data processing control unit 320 controls and manages the APs (Application Processors) in the same group (MLD group) through the MAC layer. Figure 1 (APs 100_1 and 100_2 are shown in the diagram). For example, the data processing control unit 320 collects information about STAs connected to a certain affiliated AP (information about Layer 2) and transmits this information to another AP when necessary, enabling APs in the same group to cooperate with each other at the MAC layer. In this embodiment, the data processing control unit 320 can at least manage connection information (such as encryption keys) about STAs connected to the AP and information about sequence numbers. Note that this embodiment is not limited to this configuration, and the data processing control unit 320 can also manage, for example, whether packets were successfully sent to the STA. The data processing control unit 320 corresponds to the AP MLD entity described above.

[0086] The communication unit 360 transmits and receives signals via antenna 340 and wirelessly communicates with the target AP 100 via a control link. Note that communication between the controller device 300 and AP 100 can be wired. Alternatively, both wired and wireless communication can be performed. The communication unit 360 may be able to communicate directly with STA 200 (without via AP 100).

[0087] Figure 5 The illustration shows an example of a handover process based on relevant technologies.

[0088] First, AP 100_1 connects to STA (“AP 100_1 Association”) and performs data transmission between AP 100_1 and STA. In the diagram, AP 100_1 sends DATA#1 to STA, which is a packet obtained from the router, and STA sends an ACK. In this example, data transmission is performed by AP 100_1 using the downlink (DL), but data transmission can be performed by STA using the uplink (UL). However, as STA moves in the directions of AP 100_2 and 100_3 and approaches AP 100_2, the quality of the link (quality of communication) between AP 100_1 and STA gradually degrades. As a result, data transmission either fails continuously or is successfully performed, but with a low success rate and reduced throughput. In the example shown in the attached diagram, AP 100_1 fails to send DATA#2 two or more times consecutively (“×” in the diagram). AP 100_1 or STA initiates handover process 501, disconnecting AP 100_1 from STA, and AP 100_2 reconnects to STA (“AP 100_2 association”). After handover process 501, AP 100_2 sends DATA#2 to STA, and STA successfully receives DATA#2 and sends an ACK. Subsequently, similar operations are performed when STA moves further from AP 100_2 in the direction of AP 100_3. In other words, AP 100_2 or STA initiates handover process due to a deterioration in the link quality between AP 100_2 and STA. As a result, AP 100_2 and STA disconnect from each other, and AP 100_3 and STA reconnect to each other.

[0089] In the handover process 501, it is necessary to perform processes including disconnecting the STA from the AP it is connected to and establishing a connection between the STA and the AP to which the STA is newly connected (handed over). Therefore, it is necessary for the STA and AP to exchange multiple frames. When using the fast handover standardized by IEEE 802.11r, although the re-authentication process with the AP to which the STA is handing over can be omitted, multiple frames still need to be exchanged. In addition, when the determination of whether to perform the handover of the AP or STA is delayed, the period of communication failure between the AP and STA becomes longer, or the period of reduced throughput becomes longer. On the other hand, when the handover is quickly determined and when the STA moves irregularly, frame exchanges for the handover process are performed frequently, and the number of periods of communication interruption increases.

[0090] As mentioned above, when using handover processing according to related technologies, the periods of unsuccessful communication or reduced throughput become longer or occur more frequently. Therefore, handover processing according to related technologies is not suitable for environments requiring highly reliable, low-latency communication.

[0091] Figure 6 An example of the seamless roaming process proposed in Non-Patent Document 1 is illustrated.

[0092] First, AP 100_1 connects to STA (“AP 100_1 Association”) and performs data transmission (packet transmission) between AP 100_1 and STA. In the diagram, AP 100_1 sends DATA#1, which is a packet obtained from the router, and STA sends ack. When AP 100_1 detects that the link with STA is slightly weakened, AP 100_1, together with AP MLD entity 310, performs the transition to transition phase 511. This transition process is also handled by AP MLD entity 310 and another AP belonging to AP MLD entity 310 (…). Figure 6 AP 100_2 is shown in the example. AP 100_3 is not part of AP MLD entity 310.

[0093] After transitioning to transition phase 511, AP 100_1 sends DATA#2 and DATA#3 as packets to STA, and simultaneously sends (transmits) the same packets to AP 100_2 via the backhaul network (represented by shaded rectangles in the diagram). When AP 100_2 receives the packets via the backhaul network, AP 100_2 sends DATA#2 and DATA#3 to STA, just as in the case of AP 100_1. DATA#2 sent from AP 100_1 to STA is not successfully received, while DATA#2 sent from AP 100_2 to STA is successfully received. Additionally, DATA#3 sent by AP 100_1 is not successfully received by STA, while DATA#3 sent by AP 100_2 is successfully received by STA. When STA receives DATA#2 and DATA#3, STA sends the corresponding ACK to AP 100_2. As described above, both AP 100_1 and AP 100_2 repeatedly perform the operation of sending the same packets. This operation is then terminated when the handover process 512 for the STA is completed and the connection between AP 100_2 and the STA is established (“AP 100_2 Association”). After the handover process 512 is completed, packets obtained from the router are sent to AP 100_2, and packet (DATA#4) is sent from AP 100_2 to the STA. When the STA successfully receives the packet, the STA sends an ACK to AP 100_2.

[0094] Note that AP 100_3 is not subordinate to AP MLD entity 310. Therefore, in the process of transferring from AP 100_2 to AP 100_3, a transition phase is not performed; instead, a process based on... Figure 5The transfer of related technologies shown in the figure.

[0095] When a transition phase 511 is provided before the handover process 512 from AP 100_1 to AP 100_2, as described above, packet transmissions with increased redundancy can be performed, thus allowing data transmission to the STA to continue uninterrupted. Furthermore, AP 100_1 and AP 100_2 belong to the same AP MLD, and the AP MLD centrally manages their connection relationships with the STAs. Therefore, during the handover process, there is no need to perform reconnection with the STA or re-authentication with the STA. Therefore, compared with the execution of... Figure 5 Compared to the handover process of the related technologies shown, handover processing can be performed with far fewer frame exchanges. In some cases, there is a possibility that the STA will not even need to recognize the handover between APs.

[0096] Description Reference Figure 6 The issue of seamless roaming is described. As mentioned above, after transitioning to transition phase 511, AP100_1 must send (transmit) packets obtained from the router to AP100_2. This is because the MAC table in the router stores the fact that packets destined for STAs still need to be sent through AP100_1. When the router supports the transition phase and includes the ability to send packets directly to both AP100_1 and AP100_2, the transmission from AP100_1 to AP100_2 can be eliminated. However, there is no guarantee that existing routers include this functionality.

[0097] Regarding packets sent from AP 100_1 to AP 100_2, it is expected that frames supporting IEEE 802.11 will be encapsulated using IP packets and transmitted as IP packets. The packets are sent from the MAC layer (data processing unit) of AP 100_1 to the MAC layer (data processing unit) of AP 100_2. Normally, performing packet transmissions between APs connected via a backhaul network does not take much time. However, depending on factors such as network configuration, traffic load status, or AP system configuration, performing packet transmissions via the backhaul network can take a significant amount of time, thus creating the possibility that redundant operations may not be effectively performed during transition phases. This is described in detail below.

[0098] Figure 7 It is used to describe when... Figure 6The problem shown is caused by the increased time until packets are sent to AP 100_2 via the backhaul network during seamless roaming. Due to factors such as the state of traffic in the backhaul network, the time interval 513 between sending packets from AP 100_1 to the STA and sending the same packets from AP 100_2 to the STA becomes longer. In the example shown in the attached figure, the transmission of packets (DATA#2 and DATA#3) to AP 100_2, which was performed before the handover process 512, is not completed in time. As a result, the STA cannot successfully receive DATA#2 or DATA#3 before the handover is completed, just like... Figure 5 The same applies to the transfer and processing of related technologies. This results in the loss of the advantage of seamless roaming.

[0099] Figure 8 It is used to describe references Figure 7 A diagram illustrating the solution strategy for the problem of seamless roaming. Figure 8 The left image in the middle is based on the data obtained from... Figure 1 The configuration shown is obtained by omitting STA 200.

[0100] For reference Figure 1 The description sets an upper limit on the number of APs managed by AP MLD entity 310, and in this embodiment, this upper limit is two. When the number of APs belonging to a controller group is three or more, there are multiple combinations of two APs managed by AP MLD entity 310. How to determine the combination of APs managed by AP MLD entity 310, i.e., how to determine the MLD group, is crucial to preventing the aforementioned problems when using seamless roaming (see reference). Figure 7 This can be important. In this embodiment, the combination of APs managed by APMLD entity 310, i.e., the MLD group, is determined based on the time period of packet transmission performed through backhaul network 500. Note that in addition to the time period necessary for packet transmission performed through backhaul network 500, the MLD group can also be determined based on, for example, the mobility range of STAs or statistics about the mobility range of STAs, or the traffic load of APs or statistics about the traffic load of APs.

[0101] In this embodiment, specifically, as Figure 8As shown on the left, measurement 312 is performed to measure the packet transmission time period (data transmission time period) between APs 100_1 and 100_2 via the backhaul network 500. Similarly, measurement 323 is performed to measure the packet transmission time period between APs 100_2 and 100_3 via the backhaul network 500. Additionally, measurement 313 is performed to measure the packet transmission time period between APs 100_1 and 100_3 via the backhaul network 500. Note that measurement 313 is unnecessary when APs 100_1 and 100_3 are far apart and no handover occurs between them. The AP MLD entity 310 determines the MLD group obtained by combining the two APs to be managed based on the results of these measurements. In this example, the transmission time period between APs 100_1 and 100_2 is the longest, and the transmission time period between APs 100_2 and 100_3 is the shortest. In this case, AP MLD entity 310 generates an MLD group obtained by combining AP 100_2 and 100_3, such as Figure 8 As shown on the right side of the diagram. APs 100_2 and 100_3, which belong to this MLD group, are connected to AP MLD entity 310 via a link.

[0102] As a method for measuring the time period of packet transmission, there are (1) a method of pre-setting a dedicated phase for measurement, and (2) a method of referencing Figure 6 The method described is to perform measurements during a transition phase. In method (1), for example, the AP measures the packet transmission time period and reports the measurement results to the AP MLD entity 310. Based on the reported measurement results, the AP MLD entity 310 knows the transmission time period performed between the APs. In method (2), for example, the STA performs measurements and reports the measurement results directly or through the AP to the AP MLD, so that the AP MLD entity 310 knows the transmission time period performed between the APs.

[0103] As mentioned above, the optimal MLD group can be determined by considering the time period required for packet transmissions performed between APs. Therefore, the reference time can be reduced. Figure 7 The described situation occurs with the error: "Reference source not found!", and optimal operation for seamless roaming can be performed. Embodiments according to this disclosure are described in detail below.

[0104] Figure 9 This is a diagram of the entire sequence in this disclosure. This embodiment mainly includes the following five stages.

[0105] Network Setup Phase (S110): Controller device 300 performs initial network setup between APs 100_1 to 100_3 to form a controller group. Specifically, controller device 300 collects information about the status of each AP and information about the STAs attached to each AP. Controller device 300 manages the APs in the same group (controller group) at a layer above the MAC layer. At this time, the AP MLD entity 310 of controller device 300 does not need to be connected to the APs in the controller group, nor does it need to control and manage any part of the processing in the MAC layer. These processes are performed in the "MLD Group Setup Phase" described later.

[0106] Measurement Phase (S120): To determine the MLD group, the time interval for data transmission between APs is measured via the backhaul network 500. This will be described later. Figure 10 Let me describe it in detail.

[0107] MLD Group Setup Phase (S130): AP MLD entity 310 performs processes associated with the generation or update of MLD groups with each AP. Specifically, AP MLD entity 310 performs frame exchanges with each AP associated with adding or excluding APs attached to AP MLD entity 310, and sets multicast addresses to specify a group of APs in the same MLD group.

[0108] Association Phase (S140): The process of connecting AP MLD entity 310 and STA is performed. Specifically, AP MLD entity 310 and STA 200 exchange authentication frames and association frames to complete the connection process. Afterwards, a four-way handshake is performed to generate an encryption key. For STAs already directly connected to APs belonging to the MLD group (STAs that were directly connected to and communicated with the AP before the MLD group was generated), the STA is disconnected from the AP, and the process of connecting the STA and AP MLD entity 310 is re-executed. The STA can exchange frames with AP MLD entity 310 directly or via the AP. Additionally, AP MLD entity 310 shares an encryption key with APs in the same MLD group, which is used to send and receive data with the STA.

[0109] Data Tx Phase (S150): Data transmission is performed between the STA and the AP. When the association phase is performed through an AP, the AP with which the STA performs data transmission can be that specific AP. Alternatively, when the association phase is performed directly between the STA and the APMLD entity 310, the AP with which the STA performs data transmission can be any AP determined by any method, including APs with the highest received radio wave strength and APs specified by the AP MLD entity 310.

[0110] When handover processing is performed between APs belonging to the same MLD group during the data Tx phase, the following steps are performed: Figure 6 The transition phase shown is processed to perform data transmission with increased redundancy. Additionally, in this embodiment, the STA measures the time interval of packet transmissions performed between APs during the transition phase. This will be referred to later. Figure 14 Detailed description.

[0111] <Measurement Phase (S120)>

[0112] Figure 10 This is a sequence diagram of the measurement phase (S120).

[0113] First, the controller device 300 sends a Data Forwarding Delay Measurement (DFDM) request frame (S121) to all APs belonging to the controller group via the control link. This frame includes information specifying the AP (AP 100_1 in the figure) that will send subsequent test packets, and the APs (APs 100_2 and 100_3 in the figure) that will receive the test packets and measure the transmission time period. The test packets are packets containing data used to measure the data transmission time period performed between the APs. Refer to the description below. Figure 11 Describe the DFDM request frame in detail.

[0114] Next, AP 100_1 sends a test packet via backhaul network 500 (S122). The destination of the test packet can be a separate address, multicast address, or broadcast address of AP 100_2 / AP 100_3. Note that when using a separate address, the number of times the test packet is sent increases depending on the number of APs to which it is sent. Additionally, when using a multicast address, a preset address is required to specify a group of APs within the same network. Furthermore, when using a broadcast address, the packet is also sent to network equipment outside the controller group. This can lead to a significant increase in overall load. Note that the test packet can be sent not only once, but also repeatedly a necessary number of times or for a necessary period of time. Information indicating the method used to send the test packet is included in the DFDM request described above. Refer to the description below. Figure 12 Describe the test group in detail.

[0115] Finally, each of APs 100_2 and 100_3 sends a DFDM report frame to controller device 300 (S123_1, S123_2) via the control link. This frame includes information (measurement information) about the transmission time period measured by each of APs 100_2 and 100_3. Refer to the description below. Figure 13 Describe the DFDM report frame in detail.

[0116] [Example of DFDM request frame configuration]

[0117] Figure 11 The diagram illustrates an example of configuring a DFDM request frame. Here, based on the IEEE 802.11 measurement request frame / measurement request element, a DFDM request frame is defined by adding index information indicating "DFDM" in the "Measurement-Request-Mode" field. The "Measurement Request" field includes the following information. Note that the configuration of the DFDM request frame is not limited to... Figure 11 The configuration shown is sufficient, provided that the DFDM request frame includes at least a portion of the following information.

[0118] Transmitter ID: Identification information about the AP that sent the test packets. The identification information about the AP can be an AID (Association ID) or a MAC address, or it can be an ID assigned to each AP for measurement by the AP MLD entity 310 or the controller device 300.

[0119] Receiver ID: Identification information about the AP that received the test packets and measured the transmission time period. This AP identification information can be an AID (Association ID), a MAC address, or other identification information. Multiple receiver IDs can be set, or the receiver ID can be a multicast address.

[0120] First Packet ID: Packet identification information included in the first test packet sent. The packet identification information can be any number or symbol that can identify the packet.

[0121] Test packet count: The number of times test packets are transmitted. The test packet count can be blank or include "0" when the measurement duration described later includes values ​​other than zero. A blank or "0" means that no number of transmissions is specified.

[0122] Test packet interval: The time interval for transmitting test packets. The test packet interval can be blank or include "0". Blank or "0" means that no transmission time interval is specified.

[0123] Measurement Duration: The time period used for measurement. When the number of test groups mentioned above includes values ​​other than zero, the measurement duration can be blank or include "0". Blank or "0" means that no time period for measurement has been specified.

[0124] Test Packet Type: The type of test packet sent for measurement. Examples of test packet types include "No Payload", "Payload", and "Encrypted Payload".

[0125] Reporting conditions: Information instructing the AP on the conditions under which it sends a report. Below is an example of a condition.

[0126] *After completing the measurement based on the information included in the number of test groups or the measurement duration, AP voluntarily sends a report.

[0127] The AP waits for a report to be sent until the controller device 300 gives the AP an instruction to send a report.

[0128] Even before the measurement is completed, the AP sends a report at that time based on the measurement results acquired before the time to obtain a transmission opportunity.

[0129] [Example of test group configuration]

[0130] Figure 12 The diagram illustrates an example of test group configuration. Here, the diagram illustrates a configuration based on an IEEE 802.11 control frame. The test group includes the following information. Note that the example of test group configuration is not limited to this. Figure 12 The configuration shown is valid, and the test group may include at least some of the following information.

[0131] Group ID: Identifying information about the group (test group). The group ID is used to identify the target test group for measurement.

[0132] Timestamp: Time information about when the packet (test packet) was generated. This time information is used to determine when the packet was sent. The time period of packet transmission performed between APs is measured based on this time information. In this case, time synchronization needs to be established for the APs measuring the packet transmission period. Regarding the accuracy of synchronization, millisecond-level synchronization is sufficient, and high accuracy is not required.

[0133] Encryption flag: Information about whether the random data corresponding to the subsequent payload is encrypted.

[0134] Any encryption algorithm can be used, based on an encryption key shared within the controller group.

[0135] Encryption of the portion of the test packet corresponding to the payload allows for the measurement of a composite time period obtained by including a portion of the time period through MAC processing, which involves encryption at the source AP and decryption at the destination AP, during the packet transmission time from the source AP to the destination AP. Conversely, the payload does not necessarily need to be encrypted when precise information about the time periods for encryption and decryption is not required.

[0136] Random Data: Random data corresponding to the payload. Including a sequence of random values ​​in the payload allows for the measurement of transmission time periods approximating the normal transmission time of packets containing data such as actual audio, video, and text. When a rough transmission time period is sufficient, payload data is not required. Not providing payload data reduces the load on the backhaul network 500.

[0137] [Example of DFDM response frame configuration]

[0138] Figure 13 The diagram illustrates an example of DFDM response frame configuration. Here, based on the IEEE 802.11 measurement report frame / measurement report element, the DFDM response frame is defined by adding an index indicating "DFDM" in the "Measurement-Report-Mode" field. The "Measurement Report" field includes the following information. Note that the configuration of the DFDM response frame is not limited to... Figure 13 The configuration shown is acceptable, provided that the DFDM response frame includes at least a portion of the following information.

[0139] Transmitter ID: Identification information about the AP that has sent the test packet.

[0140] Measurement start time: Time information regarding when the measurement started. For example, the measurement start time could be the time when the DFDM request frame was received, or it could be a timestamp value included in the first received test packet.

[0141] Test Packet Count: The number of test packets received. When including a test packet count, the AP that has received test packets must count the number of times the test packets were received. The AP MLD entity can compare the test packet count value with the number of test packets indicated using the DFDM request frame, and if the test packet count value is less than the number of test packets, it can be determined that the success rate of packet reception between the corresponding APs is low, i.e., the level of communication quality is low.

[0142] Average latency (or data transmission time): The average duration (latency) of data transmission between APs. The data transmission time can be calculated using the difference between the timestamp value included in the received test packet and the time the test packet was received (i.e., the time period required to send the test packet). The AP receiving the test packet can calculate the average duration of data transmission between APs by dividing the sum of the transmission times of the received test packets by the aforementioned test packet count value. If the average duration of data transmission is large, it can be determined that the bandwidth load in the backhaul network 500 between the corresponding APs is high.

[0143] Worst-case latency: The worst-case time interval (latency) of data transmission between APs. In other words, the worst-case latency indicates the maximum value among the data transmission interval values ​​calculated for the corresponding test group.

[0144] In addition to the information mentioned above, it may also include information such as variance values, jitter values, or histograms for data transmission time periods.

[0145] <Sequence of Data Tx Phase (S150)>

[0146] Figure 14 This includes performing a transition phase in the data Tx phase (S150) (see reference). Figure 6 This is a diagram showing the sequence of processes for measuring packet transmission time periods during the transition phase. This sequence includes the process of requesting STA 200 to measure packet transmission time periods.

[0147] First, when AP 100_1 detects a decline in link quality (communication quality) while communicating with STA 200 (such as performing data transmission), AP 100_1 determines to request a transition to a transition phase and sends a transition request frame to AP MLD entity 310 (S151). For example, a decline in link quality can be detected when the packet error rate or the rate of change of the packet error rate is greater than a threshold, or when the signal strength or the rate of change of the signal strength is less than a threshold. This transition to the transition phase can be determined by the STA, and the STA can request the transition to the transition phase directly or through AP 100_1 to AP MLD entity 310. The transition request frame may include identification information (such as AID) about the STA 200 to be handed over and information about the determination criteria on which the handover process is based (such as the value of the packet error rate, or information indicating that the packet error rate is greater than a threshold).

[0148] Additionally, the transition request frame includes a DFDM request. The DFDM request may have the same characteristics as described above. Figure 11 The configuration is the same as the measurement request element shown. In this case, for example, setting fields that are not currently needed (such as the number of test groups and duration) to "0" or blank is sufficient. Alternatively, it can be defined with... Figure 11 The different frames and elements are shown below. In this case, it is sufficient for the elements to include only the fields containing the information currently needed.

[0149] Next, AP MLD entity 310 designates the AP belonging to the same MLD group as AP 100_1 (in this example, only AP 100_2) and sends a transition setup frame to AP 100_2. The transition setup frame includes identification information (such as AID) about the STA to be handed over, as well as information about the criteria used to determine the handover process. The information about the criteria can be the same as that included in the transition request frame. When AP 100_2 receives the transition setup frame, AP 100_2 begins sending data packets from AP 100_1 to STA 200 via the backhaul network 500. Note that the data packets sent from AP 100_1 here are different from the test packets described above and include the data that actually needs to be sent to STA 200.

[0150] At this time, each of APs 100_1 and 100_2 includes the DFDM request in the data packet sent to STA 200 (S153, S155). For example, the DFDM request is sent with the status in the "Control" field of the frame included in the data packet. Refer to the description below. Figure 15 An example describing the configuration of data grouping.

[0151] After receiving a data packet from each of APs 100_1 and 100_2, STA 200 sends a frame including a DFDM report and an ACK to one of APs 100_1 and 100_2, and sends an ACK to the other AP, where the DFDM report includes measurement information about the data transmission time period (delay time). In the example shown in the attached figure, STA 200 sends an ACK to AP 100_1 (S154) and sends a frame including a DFDM report and an ACK to AP 100_2 (S156). The DFDM report can be defined as a different frame from the ACK, and a frame including the DFDM report and an ACK can be sent separately. Note that when STA 200 successfully receives a data packet from only one of APs 100_1 and 100_2, STA 200 can send an ACK only to that one AP. When transmitting measurement information obtained through multiple measurements in a concentrated manner, a frame including a DFDM report and an ACK can be sent at any time when a data packet is successfully received. Alternatively, a frame including only the DFDM report can be sent at any time.

[0152] DFDM reports can have the same characteristics as the above. Figure 13 The measurement report element shown has the same configuration, or may have the same configuration as... Figure 13 The elements shown are configurations of elements defined independently. Refer to the descriptions below. Figure 16 Describe in detail the operations performed by the STA 200 after receiving the data packet.

[0153] Figure 15 The illustration shows an example of the configuration of a data packet, including a DFDM request, sent from the AP to the STA 200. Here, the "HT Control" field of a typical IEEE 802.11 frame includes the following information as a DFDM request. Note that the configuration of the data packet is not limited to... Figure 15 The configuration shown may include at least a portion of the following information as a DFDM request.

[0154] DFDM Request Flag: Indicates whether to request the STA to measure the packet transmission period during the transition phase. When the STA receives a data packet, it determines whether to measure the transmission period based on the flag information.

[0155] First Group SN: SN information regarding the sequence number (SN) of the group (data group) that is first added to the STA for which measurements are performed. Note that the group's sequence number is stored in the "Sequence Control" field.

[0156] Number of data packets: The number of times data packets are transmitted. When the measurement duration described later includes a value, the number of data (test) packets can be blank or include "0". Blank or "0" means that no number of transmissions is specified.

[0157] Data packet interval: The time interval for transmitting data packets. The data packet interval can be blank or include "0". A blank or "0" means that no transmission time interval is specified.

[0158] Measurement Duration: The time period used for the measurement. When the above data grouping number includes values, the measurement duration can be blank or include "0". Blank or "0" means that no time period is specified for the measurement.

[0159] Timestamp: Time information about when the packet (data packet) was generated. This time information is used to indicate when the data packet was sent from the AP (transmission time information).

[0160] Reporting conditions: Information instructing the STA to send a report based on the conditions. Below is an example of a condition.

[0161] *STA voluntarily sends a report after completing the measurement based on information included in the number of data groups or the measurement duration.

[0162] *STA waits to send a report until AP gives STA the instruction to send a report.

[0163] Even before the measurement is completed, the STA sends a report at that timing based on the measurement results obtained before the timing for obtaining the transmission opportunity.

[0164] Figure 16 This is a flowchart illustrating an example of an operation for measuring a transmission time period, performed by STA 200. When STA 200 receives a data packet from AP 100_1 or 100_2 (S201), STA 200 checks the sequence number (SN) included in the "Sequence Control" field of the received data packet (S202).

[0165] STA 200 determines whether the SN is within the range specified by the DFDM request included in the data packet (i.e., whether the SN exhibits a value larger than the value in the first packet SN) (S203). When the SN is within the range specified by the DFDM request, STA 200 checks whether a data packet with the same SN has been received (S204). Whether a data packet with the same SN has been received is determined by whether information with the same SN has been stored in the memory.

[0166] When a data packet with the same SN has not yet been received, STA 200 stores timestamp information associated with the SN in its internal memory, which is included in the DFDM request in the data packet (S205).

[0167] When a data packet with the same SN is received, STA 200 calculates the difference between the timestamp information associated with the SN in its memory and the timestamp information included in the DFDM request in the currently received data packet (S206). The calculated difference represents the data packet transmission time period (delay time) performed between AP 100_1 and AP 100_2. STA 200 sends a frame including a DFDM report containing the calculated difference (transmission time period) (S207).

[0168] When it is determined in step S203 that the SN is not within the range specified by the DFDM request, or after the processing in steps S205 or S207, STA 200 continues to execute the process of waiting for data packets. When a data packet is received (step S201), the above-described steps S202 and subsequent processing are executed.

[0169] exist Figure 16 In the process shown, a DFDM report is sent each time a difference is calculated in step S206. However, a DFDM report set can be used to send differences calculated for a time period specified by the measurement duration or a specific time period. Alternatively, a specified number of differences (transmission time period) can be sent using a DFDM report set each time a specified number of differences are calculated. The specified number can be the upper limit if there is an upper limit to the number of differences that can be stored in a DFDM report.

[0170] In the above embodiments, the maximum number of APs is two, and the AP pairs performing seamless roaming are the same as those managed by APMLD entity 310. However, when the maximum number is three or more, APs 100_1 to 100_3 can all be classified into the same MLD group, and AP pairs performing seamless roaming can be determined according to the above embodiments. For example, when the data transmission time period between APs 100_1 and 100_2 does not meet the criteria (e.g., the data transmission time period is greater than a threshold) and the data transmission time period between APs 100_2 and 100_3 meets the criteria (e.g., the data transmission time period is less than or equal to the threshold), only the pair of APs 100_2 and 100_3 can be determined as AP pairs performing seamless roaming.

[0171] As described above, according to this embodiment, the optimal AP pair (MLD group) for performing seamless roaming can be determined by comparing the data transmission time periods (latency times) performed between APs by AP MLD entities with an upper limit on the number of connections.

[0172] Additionally, by providing a measurement phase before operation begins and measuring the data transmission time periods performed between APs, fixed latency factors such as the impact of network configuration can be identified first, and highly effective MLD groups can be set up at the start of operation.

[0173] Furthermore, when the STA measures the time intervals of data transfer between APs during the transition phase and provides feedback on the measurement results, the impact of factors such as potentially large variations in network load during operation can also be considered, and MLD groups can be generated or updated. This allows for the setup of highly robust MLD groups.

[0174] Of the methods for setting up MLD groups before and after the operation begins, only one or both can be used. Using both methods simultaneously allows for optimal management by considering both fixed and variable transmission delays (delays during transmission).

[0175] (First application example)

[0176] Application examples related to the measurement of data transmission time periods (measurement of delay time) are described as modifications to the above embodiments.

[0177] Figure 17 The illustration shows an example of a network in a home mesh scenario. A home mesh scenario means providing multiple access points (APs) in a mesh arrangement within a home to broaden the wireless environment. Similar to the embodiment described above, this example assumes that STA 200 moves between three APs and performs handover processing. Note that this example adopts the same approach as according to the embodiment described above. Figure 1 The configuration shown is different from the previous one, except that AP 100_1' is directly connected to router 400, and a wireless backhaul network is created between AP 100_1' and each of APs 100_2 and 100_3. In this case, AP 100_1' includes an AP MLD entity and is connected to APs 100_2 and 100_3. Similar to the cases of APs 100_2 and 100_3, AP 100_1' also includes the usual AP functions (the functions of AP 100_1 in the above embodiment).

[0178] In this case, using the results of measuring the data transmission time period performed through the backhaul network, AP 100_1 determines two APs from AP 100_1 to 100_3 that form an MLD group (in the case where the upper limit of the number of APs that the AP MLD entity can manage is two), as in the case of the above embodiment.

[0179] Alternatively, the link quality in the wireless backhaul between APs 100_1 and 100_2, and between APs 100_1 and 100_3, can be measured separately to estimate the corresponding data transmission time periods (latency) instead of actually measuring the data transmission time periods performed between the APs. This allows the data transmission time periods to be measured using test packet transmissions for each omission in the data transmission between APs 100_1 and 100_2 and between APs 100_1 and 100_3.

[0180] Furthermore, when performing a handover from AP 100_2 to AP 100_3, during the transition phase, if AP 100_1 performs a single packet multicast transmission to both AP 100_2 and AP 100_3, the data transmission time from AP 100_2 to AP 100_3 (due to latency from the wireless backhaul network) can be essentially zero. Therefore, the measurement of the data transmission time from AP 100_2 to AP 100_3 can be omitted.

[0181] Depending on the network configuration, it is flexible to determine which APs (access points) to measure data transmission time periods (latency), or whether to actually send test packets, as described above. These can be defined by standards or determined by any of the APs.

[0182] (Second application example)

[0183] Figure 18The illustration shows an example configuration of a network where multiple APs perform a joint transmission function (Tx). APs 100_1 and 100_2 simultaneously send transmission signals generated from a single packet to STA 200 using a joint Tx (one of the multi-AP coordination methods). This allows for the expectation of improved throughput and reliability. In this case, it is necessary for APs 100_1 and 100_2 to share the data (packets) from which they generate transmission signals. Therefore, data is likely to be sent from one of APs 100_1 and 100_2 to the other, as in the embodiment described above. Thus, the above embodiment can be applied to the determination of the group performing coordinated transmissions, such as measuring the data transmission time period (delay time) performed between APs 100_1 and 100_2 during data transmission for joint Tx, performing joint Tx for APs with short data transmission time periods (e.g., less than or equal to a threshold), and not performing joint Tx for APs with long data transmission time periods (e.g., greater than a threshold).

[0184] <Example of computer configuration>

[0185] The above series of processes can be performed using hardware or software. When software is used to perform the series of processes, the program included in the software is installed from a program recording medium onto a computer, such as a computer integrated with dedicated hardware or a general-purpose personal computer.

[0186] Figure 19 This is a block diagram illustrating an example configuration of computer hardware that uses a program to perform the series of processes described above.

[0187] The central processing unit (CPU) 801, read-only memory (ROM) 802 and random access memory (RAM) 803 are connected to each other via bus 804.

[0188] Additionally, the input / output interface 805 is connected to the bus 804. An input section 806, including, for example, a keyboard and mouse, and an output section 807, including, for example, a display and speakers, are connected to the input / output interface 805. Furthermore, a storage section 808, including, for example, a hard disk and non-volatile memory, a communication section 809, including, for example, a network interface, and a driver 810 that drives the removable medium 811 are connected to the input / output interface 805.

[0189] In a computer with the above configuration, the above series of processes are performed by the CPU 801 via the input / output interface 805 and the bus 804, loading, for example, a program stored in the storage unit 808 into the RAM 803 and executing the program.

[0190] For example, the program executed by the CPU 801 is provided by recording in the removable medium 811, or by providing it via a wired or wireless transmission medium such as a local area network, the Internet or digital broadcasting, and the provided program is installed on the storage unit 808.

[0191] Note that a program executed by a computer can be a program that is processed sequentially in the order described herein, or it can be a program that is processed in parallel or at necessary time intervals, such as timed invocations.

[0192] <Application Example>

[0193] This technology can be applied to various products. For example, Figure 2 The base station (wireless communication device) 100 shown in the figure and Figure 3 The terminal devices (wireless communication devices) 200 shown can each be implemented as mobile terminals, such as smartphones, tablet PCs, laptops, portable gaming consoles, or digital cameras; fixed terminals, such as television receivers, printers, digital scanners, or network storage devices; or in-vehicle terminals, such as car navigation systems. Furthermore, the base station (wireless communication device) 100 and the terminal devices (wireless communication devices) 200 can each be implemented as machine-to-machine (M2M) communication terminals, such as smart meters, vending machines, remote monitoring devices, or point-of-sale (POS) terminals. Moreover, each of the base station (wireless communication device) 100 and the terminal devices (wireless communication devices) 200 can be a wireless communication module (such as an integrated circuit module formed using a die) included in a corresponding one of these terminals.

[0194] On the other hand, for example, the base station (wireless communication device) 100 and the terminal device (wireless communication device) 200 can each be implemented as a wireless LAN AP (wireless base station) with or without router functionality. Additionally, the base station (wireless communication device) 100 and the terminal device (wireless communication device) 200 can each be implemented as a mobile wireless LAN router. Furthermore, each of the base station (wireless communication device) 100 and the terminal device (wireless communication device) 200 can be a wireless communication module (such as an integrated circuit module formed using a die) included in the corresponding device.

[0195] <Example of Smart Phone Configuration>

[0196] Figure 20 This is a block diagram illustrating an example configuration of a smartphone to which this technology is applied.

[0197] The smartphone 900 includes a processor 901, a memory 902, a storage device 903, an external connection interface 904, a camera 906, a sensor 907, a microphone 908, an input device 909, and a display device 910. Furthermore, the smartphone 900 includes a speaker 911, a wireless communication interface 913, an antenna switch 914, an antenna 915, a bus 917, a battery 918, and an auxiliary controller 919.

[0198] The processor 901 can be, for example, a CPU or a system-on-a-chip (SoC), and limits the functionality of the application layer and other layers of the smartphone 900.

[0199] The memory 902 includes RAM and ROM, and stores programs and data executed by the processor 901 therein.

[0200] Storage device 903 includes storage media such as semiconductor memory or hard disk.

[0201] External connection interface 904 is an interface for connecting external devices such as memory cards or Universal Serial Bus (USB) devices to the smartphone 900.

[0202] The camera 906 includes, for example, a charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) imaging element and generates captured images.

[0203] Sensor 907 includes a group of sensors such as a positioning sensor, a gyroscope, a geomagnetic sensor, and an accelerometer.

[0204] Microphone 908 converts the sound input to smartphone 900 into an audio signal.

[0205] Input device 909 includes, for example, a touch sensor, keypad, keyboard, button, or switch that detects touches on the screen of display device 910, and receives operations performed by the user or information input by the user.

[0206] Display device 910 includes a screen such as a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display, and converts the audio signal output by smartphone 900 into sound.

[0207] The wireless communication interface 913 supports at least one of the wireless LAN standards, such as IEEE 802.11a, 11b, 11g, 11ac, 11ad, 11ax, 11ay and 11be, and performs wireless communication.

[0208] The wireless communication interface 913 communicates with other devices via a wireless LAN AP in infrastructure mode. Alternatively, the wireless communication interface 913 can communicate directly with other devices in ad hoc mode or a direct communication mode such as Wi-FiDirect.

[0209] Note that in Wi-FiDirect, one of the two terminals operates as an access point (AP), but the terminals communicate directly with each other, which is different from the self-organizing mode.

[0210] Typically, the wireless communication interface 913 includes, for example, a baseband processor, radio frequency (RF) circuitry, and a power amplifier. The wireless communication interface 913 can be a single-chip module that integrates a memory for storing communication control programs, a processor for executing programs, and related circuitry.

[0211] In addition to wireless LAN solutions, the wireless communication interface 913 can also support other types of wireless communication solutions, such as near-field communication solutions, short-range wireless communication solutions, and cellular communication solutions.

[0212] Antenna switch 914 switches the connection destination of antenna 915 among multiple circuits (such as circuits for different wireless communication schemes) included in wireless communication interface 913.

[0213] Antenna 915 includes at least one antenna element (such as multiple antenna elements included in a multiple-input multiple-output (MIMO) antenna) and is used to transmit and receive radio signals via wireless communication interface 913.

[0214] Note that smartphones 900 are not limited to Figure 20 The example shown can include multiple antennas (such as an antenna for wireless LAN and an antenna for short-range wireless communication schemes). In this case, the antenna switch 914 can be omitted from the configuration of the smartphone 900.

[0215] The processor 901, memory 902, storage device 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 are connected to each other via bus 917.

[0216] Battery 918 supplies power to the battery via the power supply line indicated by the dashed line in the diagram. Figure 20 Each block of the smartphone 900 shown is powered. The auxiliary controller 919 operates the minimum necessary functions of the smartphone 900 in, for example, sleep mode.

[0217] For example, in Figure 20In the smartphone 900 shown, Figure 2 The communication processing unit 110, communication control unit 111, and control unit 130 shown are... Figure 3 The communication processing unit 210, communication control unit 211, and control unit 230 shown can be implemented by the wireless communication interface 913. Furthermore, at least some of these functions can be implemented by the processor 901 or the auxiliary controller 919.

[0218] Note that when the processor 901 performs AP functions at the application layer, the smartphone 900 can operate as a wireless AP (software AP). Additionally, the wireless communication interface 913 can include wireless AP functionality.

[0219] Furthermore, the smartphone 900 may include a biometric authentication unit (fingerprint authentication, palm print authentication, voice authentication, vascular authentication, facial authentication, iris authentication, and retinal authentication). In this case, it is implemented through... Figure 2 The communication processing unit 110, communication control unit 111, and control unit 130 shown are... Figure 3 The wireless communication interface 913 of the communication processing unit 210, communication control unit 211 and control unit 230 shown is configured to receive power from at least one of the same batteries 918 as the display device 910, speaker 911 or biometric authentication unit.

[0220] Furthermore, in the smartphone 900, information is displayed using at least one of the display device 910 or the speaker 911 based on communication performed with an external device using the wireless communication interface 913. In this case, information related to this technology can be output as information from at least one of the display device 910 or the speaker 911.

[0221] <Example of vehicle-mounted device configuration>

[0222] Figure 21 This is a block diagram illustrating an example configuration of an on-board device 920 to which this technology is applied.

[0223] The vehicle-mounted device 920 includes a processor 921, a memory 922, a Global Navigation Satellite System (GNSS) module 924, a sensor 925, a data interface 926, a content player 927, and a storage medium interface 928. Additionally, the vehicle-mounted device 920 includes 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.

[0224] The processor 921 may be, for example, a CPU or a SoC, and controls the navigation and other functions of the in-vehicle device 920. Additionally, the processor 921 may also control the vehicle's drive system (such as brakes, accelerators, or steering mechanisms) based on information obtained through communication based on this technology.

[0225] The memory 922 includes RAM and ROM, and stores programs and data executed by the processor 921 therein.

[0226] The GNSS module 924 uses GNSS signals received from GNSS satellites to measure the location (e.g., latitude, longitude, and altitude) of the vehicle-mounted device 920.

[0227] Sensor 925 includes a group of sensors such as gyroscopes, geomagnetic sensors, and atmospheric pressure sensors.

[0228] Data interface 926 is connected to vehicle network 941, for example, via a terminal (not shown), and acquires data generated on the vehicle side (such as vehicle data).

[0229] Content player 927 plays back content stored in storage media (such as CD or DVD) stored in storage media interface 928.

[0230] Input device 929 includes, for example, a touch sensor, button, or switch that detects touch on the screen of display device 930, and receives operations performed by the user or information input by the user.

[0231] Display device 930 includes a screen such as an LCD or OLED display, and displays images on it for navigation functions or for content to be played back.

[0232] Speaker 931 outputs sound for navigation functions or for content to be played back.

[0233] It should be noted that the navigation function and content player 927 are optional features in the in-vehicle device 920. The navigation function and content player 927 can be excluded from the configuration of the in-vehicle device 920.

[0234] The wireless communication interface 933 supports at least one of the wireless LAN standards, such as IEEE 802.11a, 11b, 11g, 11n, 11ac, 11ad, 11ax, 11ay, and 11be, and performs wireless communication. The wireless communication interface 933 communicates with other devices via a wireless LAN AP in infrastructure mode. Additionally, the wireless communication interface 933 communicates directly with other devices in self-organizing mode or in a direct communication mode such as Wi-FiDirect.

[0235] Typically, the wireless communication interface 933 includes, for example, a baseband processor, RF circuitry, and a power amplifier. The wireless communication interface 933 can be a single-chip module that integrates a memory storing communication control programs, as well as a processor or related circuitry for executing those programs. In addition to wireless LAN solutions, the wireless communication interface 933 can also support other types of wireless communication solutions, such as near-field communication, short-range wireless communication, and cellular communication.

[0236] Antenna switch 934 switches the connection destination of antenna 935 among multiple circuits included in wireless communication interface 933.

[0237] Antenna 935 includes at least one antenna element and is used to transmit and receive radio signals via wireless communication interface 933.

[0238] It should be noted that the vehicle-mounted device 920 is not limited to Figure 21 The example in the text can include multiple antennas 935. In this case, the antenna switch 934 can be omitted from the configuration of the vehicle-mounted device 920.

[0239] Battery 938 is connected to the power supply line indicated by the dashed line in the diagram. Figure 21 In the vehicle-mounted device 920 shown, for example, Figure 2 The communication processing unit 110, communication control unit 111, and control unit 130 shown are... Figure 3 The communication processing unit 210, communication control unit 211, and control unit 230 shown can be implemented by the wireless communication interface 933. Furthermore, at least some of these functions can be implemented by the processor 921.

[0240] In addition, the wireless communication interface 933 can operate as each of the aforementioned base station (wireless communication device) 100 and terminal device (wireless communication device) 200, and provide wireless connection to the terminal of the user in the vehicle.

[0241] Furthermore, this technology can be implemented as an in-vehicle system (or vehicle) 940, which includes at least one block of the aforementioned in-vehicle device 920, an in-vehicle network 941, and a vehicle-side module 942. The vehicle-side module 942 generates vehicle-side data (such as vehicle speed, engine speed, or fault information) and outputs the generated data to the in-vehicle network 941.

[0242] <Example of wireless AP configuration>

[0243] Figure 22 This is a block diagram illustrating an example configuration of a wireless AP 950 to which this technology is applied.

[0244] 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.

[0245] The controller 951 can be, for example, a CPU or a digital signal processor (DSP), and operates various functions of the wireless AP 950 at the Internet Protocol (IP) layer and higher layers (such as access restriction, routing, encryption, firewall, and log management).

[0246] The memory 952 includes RAM and ROM, and stores programs executed by the controller 951 as well as various control information (such as terminal lists, routing tables, encryption keys, security settings, and logs).

[0247] Input device 954 includes, for example, buttons and switches, and receives operations performed by the user.

[0248] Display device 955 includes, for example, LED lights and displays the operating status of wireless AP 950 thereon.

[0249] Network interface 957 is a wired communication interface used to connect wireless AP 950 to wired communication network 958. Network interface 957 may include multiple connection terminals. Wired communication network 958 may be a LAN, such as Ethernet (registered trademark), or it may be a wide area network (WAN).

[0250] The wireless communication interface 963 supports at least one of the wireless LAN standards, such as IEEE 802.11a, 11b, 11g, 11n, 11ac, 11ad, 11ax, 11ay and 11be, and acts as an access point to provide wireless connectivity to nearby terminals.

[0251] Typically, the wireless communication interface 963 includes, for example, a baseband processor, RF circuitry, and a power amplifier.

[0252] The wireless communication interface 963 can be a single-chip module that integrates a memory for storing communication control programs and a processor or related circuitry for executing the programs.

[0253] Antenna switch 964 switches the connection destination of antenna 965 among multiple circuits included in wireless communication interface 963, and antenna 965 includes at least one antenna element and is used to transmit and receive radio signals through wireless communication interface 963.

[0254] For example, in Figure 22 In the wireless AP 950 shown, Figure 2 The communication processing unit 110, communication control unit 111, and control unit 130 shown are... Figure 3 The communication processing unit 210, communication control unit 211, and control unit 230 shown can also be implemented by the wireless communication interface 963. Furthermore, at least some of these functions can be implemented by the controller 951.

[0255] It should be noted that the above embodiments are examples for implementing this technology, and there is a correspondence between the matters in the embodiments and the matters specified in the claimed invention. Similarly, there is a correspondence between the claimed invention-specific matters and the matters in the embodiments of this technology when they are represented by the same name. However, this technology is not limited to the described embodiments and can be implemented by making various modifications to the embodiments without departing from the scope of this technology.

[0256] In addition, the processing described in the above embodiments can be considered as a method comprising a series of processes, or as a program for causing the computer to perform a series of processes, or a recording medium in which the program is stored.

[0257] For example, compact discs (CDs), mini discs (MDs), digital multifunction discs (DVDs), memory cards, or Blu-ray discs (registered trademarks) can be used as such recording media.

[0258] It is important to note that, as used herein, "system" refers to a collection of multiple components (such as devices and modules (parts)), and it is not important whether all components are housed in a single housing. Therefore, multiple devices housed in separate housings and interconnected via a network, as well as a single device housing multiple modules in a single housing, are both systems.

[0259] Furthermore, the effects described in this article are not limiting but merely illustrative, and may provide other effects.

[0260] The embodiments of this technology are not limited to the examples described above, and various modifications can be made to them without departing from the scope of this technology.

[0261] For example, this technology can have a cloud computing configuration, where a single function is shared to be processed collaboratively by multiple devices via a network.

[0262] Furthermore, the corresponding steps described using the above flowchart can be performed by a single device or can be performed by multiple devices in a shared manner.

[0263] Furthermore, when a single step includes multiple processes, the multiple processes included in the single step can be executed by a single device or can be shared and executed by multiple devices.

[0264] This embodiment may also have the following configurations.

[0265] [appendix]

[0266] (1) A controller device, comprising:

[0267] Ministry of Communications

[0268] A request message is sent to a first base station included in a plurality of base stations. The request message requests measurement of the time period of data transmission performed between the first base station and at least one second base station included in the plurality of base stations.

[0269] Receive measurement information related to the measurement of the data transmission period as a response to the requested information; and

[0270] Control Department

[0271] A third base station is determined from the at least one second base station based on measurement information related to the measurement of the data transmission time period, and

[0272] The execution control causes one of the first base station and the third base station to receive second data from the other of the first base station and the third base station and send the second data to the terminal device, the second data being the same as the first data sent from the other of the first base station and the third base station to the terminal device.

[0273] (2) The controller device according to (1), wherein

[0274] The measurement of the data transmission time period is performed by sending the data used for measurement from one of the first base station and the second base station to the other of the first base station and the second base station.

[0275] The request information includes first identification information for identifying a base station transmitting measurement data between a first base station and a second base station, and second identification information for identifying a base station receiving measurement data between a first base station and a second base station.

[0276] (3) The controller device according to (1) or (2), wherein

[0277] The measurement of the data transmission time period is performed by sending the data used for measurement from one of the first base station and the second base station to the other of the first base station and the second base station.

[0278] The request information includes at least one of the number of times the data used for measurement was sent or the measurement duration of the data transmission period.

[0279] (4) A controller device according to any one of (1) to (3), wherein

[0280] The measurement of the data transmission time period is performed by sending the data used for measurement from one of the first base station and the second base station to the other of the first base station and the second base station.

[0281] The request information includes instructions to encrypt the data used for measurement.

[0282] (5) A controller device according to any one of (1) to (4), wherein

[0283] The first base station and the third base station perform inter-base station coordination to simultaneously send the first data and the second data to the terminal device.

[0284] (6) A controller device according to any one of (1) to (5), wherein

[0285] The first base station and the third base station transmit first data and second data to the terminal device during at least a portion of the time period from when the terminal device is determined to be transferred from the first base station to the third base station until the transfer is completed.

[0286] (7) A base station that is one of a plurality of base stations, the base station comprising:

[0287] Ministry of Communications

[0288] Receive request information for requesting measurement of the time period of data transmission performed between the base station and another base station included in the plurality of base stations, and

[0289] Receive data for measuring the data transmission time period from the other base station based on the request information, or send data for measurement to the other base station based on the request information; and

[0290] The control unit measures the time interval for data transmission between the base station and the other base station based on the time it receives data for measurement.

[0291] The communications department sends measurement information related to the measurement of the data transmission period as a response to the request, and

[0292] When the base station is selected as the base station to be paired with the other base station by the destination of the response transmission of measurement information,

[0293] The communication unit receives second data from the other base station and sends the second data to the terminal device. The second data is the same as the first data sent from the other base station to the terminal device, or...

[0294] The communication unit sends fourth data to the other base station, which is the same as the third data sent from the base station to the terminal device.

[0295] (8) Based on the base station in (7), where

[0296] During at least a portion of the time period from when the terminal device is determined to be transferred from the other base station to the base station until the transfer is completed,

[0297] The communication unit sends the second data received from the other base station to the terminal device, or

[0298] The communication unit sends fourth data to the other base station, which is the same as the third data sent from the base station to the terminal device.

[0299] (9) Based on the base station of (7) or (8), where

[0300] Due to coordination between base stations, the communication unit simultaneously sends second data to the terminal device while sending first data from the other base station to the terminal device, or the communication unit simultaneously sends third data to the terminal device while sending fourth data from the other base station to the terminal device.

[0301] (10) A base station based on any one of (7) to (9), wherein

[0302] The data received by the communications department for measurement includes transmission time information, and

[0303] Based on the transmission time information included in the data used for measurement, the control unit measures the data transmission time period.

[0304] (11) A base station based on any one of (7) to (10), wherein

[0305] The communication unit receives request information from the controller device that controls the multiple base stations and sends measurement information to the controller device.

[0306] (12) A base station based on any one of (7) to (11), wherein

[0307] The communications department encrypts the data used for measurement and sends the encrypted data to the other base station.

[0308] (13) A base station based on any one of (7) to (12), wherein

[0309] The request information includes information used to instruct the communications department whether it serves to receive or transmit data for measurement, and

[0310] The communications department receives or transmits measurement data based on information used to indicate whether it is functioning.

[0311] (14) A base station based on any one of (7) to (13), wherein

[0312] The request information includes the number of times data for measurement was sent or the duration of the transmission.

[0313] The communications unit receives data for measurement a number of times included in the request information, or receives data for measurement for a duration included in the request information, and

[0314] Measurement information related to the measurement of the data transmission period includes at least one of the average or maximum values ​​of the measurements during the data transmission period.

[0315] (15) A base station based on any one of (7) to (14), wherein

[0316] The request information includes the number of times the data used for measurement was sent or the duration of the transmission, and

[0317] The communications department sends measurement data based on the number of times or duration included in the request information.

[0318] (16) A terminal device, comprising:

[0319] Ministry of Communications

[0320] Receive first data from the first base station, and

[0321] Receive second data from a second base station capable of receiving the same data as the first data from the first base station; and

[0322] Control Department

[0323] Determine whether the second data is the same as the first data, and

[0324] When the second data is identical to the first data, the measurement is performed on the data transmission time period between the first base station and the second base station. This measurement is based on first information related to the first data and second information related to the second data.

[0325] The communication unit sends measurement information to at least one of the first base station and the second base station, or to a controller device that controls the first base station and the second base station. The measurement information is related to the measurement of the data transmission time period.

[0326] (17) The terminal device according to (16), wherein

[0327] The first information includes the time when the first data was sent.

[0328] The second information includes the time of sending the second data, and

[0329] The control unit measures the data transmission time period based on the difference between the transmission time of the first data and the transmission time of the second data.

[0330] (18) The terminal device according to (16) or (17), wherein

[0331] The first information includes the reception time of the first data received by the communications department.

[0332] The second information includes the reception time of the second data received by the communications department, and

[0333] The control unit estimates the data transmission time period based on the difference between the reception time of the first data and the reception time of the second data.

[0334] (19) A terminal device according to any one of (16) to (18), wherein

[0335] Associate the first data with the sequence number.

[0336] The second data is associated with the sequence number, and

[0337] The control unit determines whether the second data is the same as the first data based on whether the serial number of the first data and the serial number of the second data are the same.

[0338] (20) According to the terminal device of (19), wherein

[0339] The range information related to the range of sequence numbers for the time period of data transmission to be measured is associated with at least one of the first data or the second data, and

[0340] The control unit determines whether the serial number of the first data and the serial number of the second data are the same based only on the serial number included in the range information.

[0341] (21) A control method, comprising:

[0342] Send a request message to a first base station included in a plurality of base stations, the request message being used to request measurement of the time period of data transmission performed between the first base station and at least one second base station included in the plurality of base stations;

[0343] Receive measurement information related to the measurement of the data transmission period as a response to the request information;

[0344] A third base station is determined from the at least one second base station based on measurement information related to the measurement of the data transmission time period; and

[0345] The execution control causes one of the first base station and the third base station to receive second data from the other of the first base station and the third base station and send the second data to the terminal device, the second data being the same as the first data sent from the other of the first base station and the third base station to the terminal device.

[0346] (22) A communication method performed by a base station as one of a plurality of base stations, the communication method comprising:

[0347] Receive request information for requesting measurement of the time period of data transmission performed between the base station and another base station included in the plurality of base stations;

[0348] Based on the request information, receive data for measuring the data transmission time period from the other base station, or send data for measurement to the other base station based on the request information;

[0349] The time period of data transmission performed between the base station and the other base station is measured based on the time when the data used for measurement is received;

[0350] Sending measurement information related to the measurement of the data transmission period as a response to the requested information; and

[0351] When the base station is selected as the base station to be paired with the other base station by the response transmission destination of the measurement information, the second data is received from the other base station and sent to the terminal device. The second data is the same as the first data sent from the other base station to the terminal device, or the fourth data is the same as the third data sent from the base station to the terminal device.

[0352] (23) A communication method, comprising:

[0353] Receive the first data from the first base station;

[0354] Receive second data from a second base station that is capable of receiving the same data as the first data from the first base station;

[0355] Determine whether the second data is the same as the first data;

[0356] When the second data is identical to the first data, the measurement is performed on the data transmission time period between the first base station and the second base station, the measurement being performed based on first information related to the first data and second information related to the second data; and

[0357] Measurement information is sent to at least one of the first base station and the second base station, or to a controller device that controls the first base station and the second base station. The measurement information is related to the measurement of the data transmission time period.

[0358] List of reference numerals

[0359] 1 Wireless Communication System

[0360] 100AP

[0361] 100 communication equipment

[0362] 100_1AP

[0363] 100_1'AP

[0364] 100_2AP

[0365] 100_3AP

[0366] 110 Communications Processing Department

[0367] 111 Communications Control Department

[0368] 112 Communication Storage Department

[0369] 121 Data Processing Department

[0370] 122 Signal Processing Department

[0371] 123 Wireless Interface Section

[0372] 124 Enlarged Section

[0373] 125 Wireless Communications Department

[0374] 130 Control Department

[0375] 140 Storage Department

[0376] 150 antenna

[0377] 160 Backhaul Communications Department

[0378] 200 communication devices

[0379] 210 Communications Processing Department

[0380] 211 Communications Control Department

[0381] 212 Communication Storage Department

[0382] 221 Data Processing Department

[0383] 222 Signal Processing Department

[0384] 223 Wireless Interface Section

[0385] 224 Enlarged section

[0386] 225 Wireless Communications Department

[0387] 230 Control Department

[0388] 240 Storage Department

[0389] 250 antenna

[0390] 300 Controller Unit

[0391] 310 MLD Entities

[0392] 310 Entities

[0393] 312 Measurement

[0394] 313 Measurement

[0395] 320 Data Processing and Control Department

[0396] 323 Measurement

[0397] 330 Network Control Department

[0398] 340 antenna

[0399] 350 Control Department

[0400] 360 Ministry of Communications

[0401] 400 router

[0402] 500 return network

[0403] 501 Transfer Processing

[0404] 511 Transition Phase

[0405] 512 Handover Processing

[0406] 513 time interval

[0407] 804 bus

[0408] 805 Input / Output Interface

[0409] 806 Input Section

[0410] 807 Output Section

[0411] 808 Storage Unit

[0412] 809 Ministry of Communications

[0413] 810 drive

[0414] 811 Removable Media

[0415] 900 Smart Phone

[0416] 901 processor

[0417] 902 Memory

[0418] 903 Storage device

[0419] 904 External Connection Interface

[0420] 906 camera

[0421] 907 sensor

[0422] 908 microphone

[0423] 909 Input Devices

[0424] 910 display device

[0425] 911 speaker

[0426] 913 Wireless Communication Interface

[0427] 914 Antenna Switch

[0428] 915 antenna

[0429] 917 bus

[0430] 918 battery

[0431] 919 Auxiliary Controller

[0432] 920 vehicle-mounted device

[0433] 921 processor

[0434] 922 memory

[0435] 924GNSS module

[0436] 925 sensor

[0437] 926 Data Interface

[0438] 927 Content Player

[0439] 928 Storage Media Interface

[0440] 929 Input Devices

[0441] 930 display device

[0442] 931 loudspeaker

[0443] 933 Wireless Communication Interface

[0444] 934 Antenna Switch

[0445] 935 antenna

[0446] 938 battery

[0447] 940 In-vehicle system (or vehicle)

[0448] 941 In-vehicle Network

[0449] 942 Vehicle-side module

[0450] 950 Wireless AP

[0451] 951 Controller

[0452] 952 memory

[0453] 954 Input Device

[0454] 955 display device

[0455] 957 Network Interface

[0456] 958 Wired Communication Network

[0457] 963 Wireless Communication Interface

[0458] 964 Antenna Switch

[0459] 965 antenna

Claims

1. A controller device, comprising: Communications Department: A request message is sent to a first base station included in a plurality of base stations. The request message requests measurement of the time period of data transmission performed between the first base station and at least one second base station included in the plurality of base stations. Receive measurement information related to the measurement of the data transmission period as a response to the requested information; and Control Department: A third base station is determined from the at least one second base station based on measurement information related to the measurement of the data transmission time period, and The execution control causes one of the first base station and the third base station to receive second data from the other of the first base station and the third base station and send the second data to the terminal device, the second data being the same as the first data sent from the other of the first base station and the third base station to the terminal device.

2. The controller device according to claim 1, wherein The measurement of the data transmission time period is performed by sending the data used for measurement from one of the first base station and the second base station to the other of the first base station and the second base station. The request information includes first identification information for identifying the base station that transmits measurement data among the first base station and the second base station, and second identification information for identifying the base station that receives measurement data among the first base station and the second base station.

3. The controller device according to claim 1, wherein... The measurement of the data transmission time period is performed by sending the data used for measurement from one of the first base station and the second base station to the other of the first base station and the second base station. The request information includes at least one of the number of times the data used for measurement was sent or the measurement duration of the data transmission period.

4. The controller device according to claim 1, wherein The measurement of the data transmission time period is performed by sending the data used for measurement from one of the first base station and the second base station to the other of the first base station and the second base station. The request information includes instructions to encrypt the data used for measurement.

5. The controller device according to claim 1, wherein... The first base station and the third base station perform inter-base station coordination to simultaneously send the first data and the second data to the terminal device.

6. The controller device according to claim 1, wherein The first base station and the third base station transmit first data and second data to the terminal device during at least a portion of the time period from when the terminal device is determined to be transferred from the first base station to the third base station until the transfer is completed.

7. A base station as one of a plurality of base stations, the base station comprising: Communications Department: Receive request information for requesting measurement of the time period of data transmission performed between the base station and another base station included in the plurality of base stations, and Based on the request information, receive data for measuring the data transmission time period from the other base station, or send data for measurement to the other base station based on the request information; as well as The control unit measures the data transmission time period performed between the base station and the other base station based on the time when the data for measurement is received. The communications department sends measurement information related to the measurement of the data transmission period as a response to the request, and When the base station is selected as the base station to be paired with the other base station by the destination of the response transmission of measurement information, The communication unit receives second data from the other base station and sends the second data to the terminal device. The second data is the same as the first data sent from the other base station to the terminal device, or... The communication unit sends fourth data to the other base station, which is the same as the third data sent from the base station to the terminal device.

8. The base station according to claim 7, wherein During at least a portion of the time period from when the terminal device is determined to be transferred from the other base station to the base station until the transfer is completed, The communication unit sends the second data received from the other base station to the terminal device, or The communication unit sends fourth data to the other base station, which is the same as the third data sent from the base station to the terminal device.

9. The base station according to claim 7, wherein Due to coordination between base stations, the communication unit simultaneously sends second data to the terminal device while sending first data from the other base station to the terminal device, or the communication unit simultaneously sends third data to the terminal device while sending fourth data from the other base station to the terminal device.

10. The base station according to claim 7, wherein The data received by the communications department for measurement includes transmission time information, and Based on the transmission time information included in the data used for measurement, the control unit measures the data transmission time period.

11. The base station according to claim 7, wherein The communication unit receives request information from the controller device that controls the multiple base stations and sends measurement information to the controller device.

12. The base station according to claim 7, wherein The communications department encrypts the data used for measurement and sends the encrypted data to the other base station.

13. The base station according to claim 7, wherein The request information includes information used to instruct the communications department whether it serves to receive or transmit data for measurement, and The communications department receives or transmits measurement data based on information used to indicate whether it is functioning.

14. The base station according to claim 7, wherein The request information includes the number of times data for measurement was sent or the duration of the transmission. The communications unit receives data for measurement a number of times included in the request information, or receives data for measurement for a duration included in the request information, and Measurement information related to the measurement of the data transmission period includes at least one of the average or maximum value of the measurement values ​​during the data transmission period.

15. The base station according to claim 7, wherein The request information includes the number of times the data used for measurement was sent or the duration of the transmission, and The communications department sends measurement data based on the number of times or duration included in the request information.

16. A terminal device, comprising: Communications Department: Receive first data from the first base station, and Receive second data from a second base station capable of receiving the same data as the first data from the first base station; and Control Department: Determine whether the second data is the same as the first data, and When the second data is identical to the first data, the measurement is performed on the data transmission time period between the first base station and the second base station. This measurement is based on first information related to the first data and second information related to the second data. The communication unit sends measurement information to at least one of the first base station and the second base station, or to a controller device that controls the first base station and the second base station. The measurement information is related to the measurement of the data transmission time period.

17. The terminal device according to claim 16, wherein The first information includes the time when the first data was sent. The second information includes the time of sending the second data, and The control unit measures the data transmission time period based on the difference between the transmission time of the first data and the transmission time of the second data.

18. The terminal device according to claim 16, wherein The first information includes the reception time of the first data received by the communications department. The second information includes the reception time of the second data received by the communications department, and The control unit estimates the data transmission time period based on the difference between the reception time of the first data and the reception time of the second data.

19. The terminal device according to claim 16, wherein The first data is associated with a sequence number. The second data is associated with a sequence number, and The control unit determines whether the second data is the same as the first data based on whether the serial number of the first data and the serial number of the second data are the same.

20. The terminal device according to claim 19, wherein The range information related to the range of sequence numbers for the time period of data transmission to be measured is associated with at least one of the first data or the second data, and The control unit determines whether the serial number of the first data and the serial number of the second data are the same based only on the serial number included in the range information.

21. A control method, comprising: Send a request message to a first base station included in a plurality of base stations, the request message being used to request measurement of the time period of data transmission performed between the first base station and at least one second base station included in the plurality of base stations; Receive measurement information related to the measurement of the data transmission period as a response to the request information; A third base station is determined from the at least one second base station based on measurement information related to the measurement of the data transmission time period; as well as The execution control causes one of the first base station and the third base station to receive second data from the other of the first base station and the third base station and send the second data to the terminal device, the second data being the same as the first data sent from the other of the first base station and the third base station to the terminal device.

22. A communication method performed by a base station as one of a plurality of base stations, the communication method comprising: Receive request information for requesting measurement of the time period of data transmission performed between the base station and another base station included in the plurality of base stations; Based on the request information, receive data for measuring the data transmission time period from the other base station, or send data for measurement to the other base station based on the request information; The time period of data transmission performed between the base station and the other base station is measured based on the time when the data used for measurement is received; Send measurement information related to the measurement of the data transmission period as a response to the request; as well as When the base station is selected as the base station to be paired with the other base station by the response transmission destination of the measurement information, the second data is received from the other base station and sent to the terminal device. The second data is the same as the first data sent from the other base station to the terminal device, or the fourth data is the same as the third data sent from the base station to the terminal device.

23. A communication method, comprising: Receive the first data from the first base station; Receive second data from a second base station that is capable of receiving the same data as the first data from the first base station; Determine whether the second data is the same as the first data; When the second data is the same as the first data, the measurement is performed on the data transmission time period between the first base station and the second base station. This measurement is performed based on the first information related to the first data and the second information related to the second data. as well as Measurement information is sent to at least one of the first base station and the second base station, or to a controller device that controls the first base station and the second base station. The measurement information is related to the measurement of the data transmission time period.

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