Wireless communication device, wireless communication terminal, and wireless communication method
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SONY GROUP CORP
- Filing Date
- 2026-01-15
- Publication Date
- 2026-08-06
Smart Images
Figure JP2026000976_06082026_PF_FP_ABST
Abstract
Description
Wireless Communication Device, Wireless Communication Terminal, and Wireless Communication Method
[0001] The present disclosure relates to a wireless communication device, a wireless communication terminal, and a wireless communication method, and particularly to a wireless communication device, a wireless communication terminal, and a wireless communication method that enable faster switching of connection destinations for wireless communication.
[0002] As a communication system for wirelessly connecting between a base station (AP) and a terminal (STA), there is a wireless LAN (Local Area Network). In use cases where multiple base stations are installed, such as in a home or a factory, it is required to provide low-latency and highly reliable wireless communication even when the terminal moves.
[0003] To achieve this, in the standardization of IEEE802.11bn, methods have been studied to make the switching of the terminal's connection destination smoother, such as a new entity or Mobility Domain that can collectively manage different base stations and sharing information related to connections between base stations (see, for example, Non-Patent Document 1).
[0004] Yelin Yoon, et al., “Seamless Roaming Data Transfer,” IEEE 802.11-24 / 1517r0, Nov.12, 2024.
[0005] However, in the current standard, there is no defined method for transferring data transmitted to the terminal between base stations when switching the connection destination base station, and there has been a demand for a proposal for the terminal to more quickly switch the connection destination base station for wireless communication.
[0006] The present disclosure has been made in view of such a situation and enables faster switching of the connection destination for wireless communication.
[0007] One aspect of the present disclosure is a wireless communication device comprising a control unit that performs control for transmitting data to a wireless communication terminal based on a data transmission method determined based on at least one of communication environment information exchanged with a wireless communication terminal and information regarding data transfer exchanged with a first wireless communication device, and control for communicating with the first wireless communication device.
[0008] A wireless communication terminal in one aspect of the present disclosure includes a control unit that performs control for receiving data transmitted from a first wireless communication device and control for receiving data transferred from the first wireless communication device, which is transmitted from a second wireless communication device different from the first wireless communication device, based on a data transmission method notified by the first wireless communication device, wherein the data transmission method is information regarding the transmission of the data, determined based on at least one of information regarding data transfer exchanged between the first wireless communication device and the second wireless communication device and information regarding the communication environment exchanged with the first wireless communication device.
[0009] Furthermore, the wireless communication device and wireless communication terminal described in this disclosure may be independent devices or internal blocks constituting a single device.
[0010] This figure shows an example of a Seamless Roaming architecture. This figure shows another example of a Seamless Roaming architecture. This figure shows another example of a Seamless Roaming architecture. This figure shows an example of a Seamless Roaming sequence in a prior art proposal. This figure shows an example of the configuration of a communication system in this disclosure. This block diagram shows an example of the configuration of a communication device compatible with AP MLD in this disclosure. This block diagram shows an example of the configuration of a communication device compatible with Non-AP MLD in this disclosure. This is a flowchart explaining the operation of the current AP. This is a flowchart explaining the operation of the target AP. This is a flowchart explaining the operation of the STA. This figure shows an example of a Seamless Roaming sequence in this disclosure. This figure shows an example of the format of a frame that notifies how to send data. This figure shows an example of the format when information indicating how to send data is stored in the PHY header. This figure shows an example of the format when information indicating how to send data is stored in the MAC header.
[0011] <Background> Multi-link operation (MLO) is being considered as a method to meet the high transmission speed requirements of 8K transmission and XR (Extended Reality). A link is a wireless transmission path that can transmit data between two communication devices. When performing MLO, each link is selected from multiple independent wireless transmission paths, for example, divided by frequency domain. For example, channels selected from multiple channels included in one of the frequency bands such as the 2.4GHz band, 5GHz band, 6GHz band, and 920MHz band are used for each link.
[0012] Devices compatible with MLO are called MLDs (Multi-link Devices). An MLD is a logical entity that contains one or more STAs (Stations) and has only one SAP (Service Access Point) to the upper layer. Hereafter, an MLD in which each contained STA is an AP (Access Point) will be referred to as an AP MLD, and an MLD in which each STA is a Non-AP STA will be referred to as a Non-AP MLD. To specify that each entity within an MLD is an internal entity of the MLD, it may be written as AP (AP affiliated with AP MLD) belonging to an AP MLD, or Non-AP STA (Non-AP STA affiliated with Non-AP MLD) belonging to a Non-AP MLD.
[0013] In use cases where multiple access points (APs) may be installed, such as in homes or factories, there is a need to provide low-latency, highly reliable communication even when terminals are moving. To achieve this, the IEEE 802.11bn standardization includes Multi-link Operation (MLO), which enables communication using multiple links. This allows for simultaneous communication with multiple APs, and Seamless Roaming, a technology that enables seamless switching between AP connections, is being considered.
[0014] In Seamless Roaming, the Multi-link device, newly defined in IEEE 802.11be for managing multiple APs within the same device, is being extended to define an entity for centrally managing APs in different devices. In this specification, this entity is called the Seamless Mobility Domain Management Entity (SMD-ME), but it is also called Single Mobility Domain MLD (SMD MLD) or Ultra Fast Transition MLD (UFT MLD). The functions of the SMD-ME can be executed on one or a different AP device. It is assumed that an SMD-ME exists for each SMD described below.
[0015] Figure 1 shows an example of a Seamless Roaming architecture. In Figure 1, each rectangular block is a logical entity, and each has a MAC address. However, the MAC addresses do not all need to be different; MAC addresses may overlap within the same device, for example, between STA1-1 and Non-AP MLD1. Furthermore, if an SMD-ME exists, a unique MAC address may be used, or a Roaming MAC address used only by terminals within the SMD may be set.
[0016] AP MLD1, AP1-1, and AP1-2 reside within the same communication device 11-1 (hereinafter, communication device 11-1 is also referred to as AP MLD1). Similarly, AP MLD2, AP2-1, and AP2-2 reside within the same communication device 11-2 (hereinafter, communication device 11-2 is also referred to as AP MLD2), and Non-AP MLD1, STA1-1, and STA1-2 reside within the same communication device 12 (hereinafter, communication device 12 is also referred to as Non-AP MLD1). In addition to the entities shown in the diagram, the above-mentioned SMD-ME may also exist. An SMD-ME may reside within at least one of AP MLD1 and AP MLD2, or it may reside in a separate device such as an external controller. Note that the existence of an SMD-ME is not mandatory; AP MLDs may cooperate to perform roaming operations, or an external controller may control roaming operations. An SMD-ME may be directly connected to an AP managed by each AP MLD, rather than to an AP MLD.
[0017] AP MLD1 and AP MLD2 may be included within the Seamless Mobility Domain shown by the dashed line in the diagram. Note that Seamless Mobility Domain is a name under discussion during standardization and may also be called USRD (Ultra Seamless Roaming Domain), etc. Also, multiple SMDs may be included within the Mobility Domain shown by the dashed line in the diagram. Within an SMD, each AP MLD may share a PTK (Pairwise Transient Key) or PMK (Pairwise Master Key), or both. However, if sharing the PTK is not possible for security reasons, the PTK or PMK may be regenerated with the destination AP MLD2 without being shared. Non-AP MLDs may establish association with SMD-ME through AP MLD1, which initiates the connection.
[0018] The AP MLDs to be connected to the SMD-ME may be known in advance, and new AP MLDs may be connected to the SMD-ME upon request from the STA. AP MLD1 and AP MLD2 are connected by a wired or wireless backhaul, and for example, AP1-1 and AP2-1 can communicate via the backhaul. The DS (Distribution System) 13 is a logical element that provides interconnection between APs, and is mainly wired Ethernet, but may also be a Wireless Distribution System (WDS) using a wireless medium. Note that the system configuration shown in Figure 1 is just an example, and each AP MLD and Non-AP MLD may consist only of APs or STAs that do not support MLO, rather than MLDs.
[0019] The SMD-ME may provide its functions within the Wireless LAN Controller (WLC), or each AP MLD may provide its own functions. Furthermore, each AP MLD may be connected to the DS via a MAC SAP, or each SMD-ME may have a single MAC SAP within the SMD and be connected to the DS. The former method is called separate MAC SAP, and the latter method is called single MAC SAP.
[0020] Figure 2 shows another example of the Seamless Roaming architecture when separate MAC SAP is adopted. In Figure 2, the Mobility Domain includes SMD1 and SMD2. SMD1 contains AP MLD1 and AP MLD2 and is connected to SMD-ME1. SMD2 contains AP MLD3 and AP MLD4 and is connected to SMD-ME2. As shown in Figure 2, AP MLD1 and AP MLD2 in SMD1 and AP MLD3 and AP MLD4 in SMD2 are connected to DS13. Figure 3 shows another example of the Seamless Roaming architecture when single MAC SAP is adopted. As shown in Figure 3, SMD-ME1 in SMD1 and SMD-ME2 in SMD2, which are included in the Mobility Domain, are connected to DS13.
[0021] <Prior Art and its Problems> Figure 4 is a diagram showing an example of a Seamless Roaming sequence in a prior art proposal such as Non-Patent Document 1 mentioned above. In Figure 4, corresponding to the configurations shown in Figures 1 to 3, the frame exchange between each communication device, AP MLD1 (AP1-1, AP1-2), AP MLD2 (AP2-1, AP2-2), and Non-AP MLD1 (STA1-1, STA1-2), is shown in chronological order. In this example, the AP that initiates the connection switch in Seamless Roaming (hereinafter referred to as the current AP) is AP MLD1, and the AP that receives the connection switch (hereinafter referred to as the target AP) is AP MLD2.
[0022] As shown in Figure 4, in AP MLD1 (current AP), AP MLD2 (target AP), and Non-AP MLD1 (STA), after Preparation (S1), a Roaming Request is sent from Non-AP MLD1 to AP MLD1 (S2), and dynamic context transfer, DS mapping change, and data transfer occur between AP MLD1 and AP MLD2. A Roaming Response is sent from AP MLD1 to Non-AP MLD1 (S3). The connection is then switched from AP MLD1 to AP MLD2, but Non-AP MLD1 may continue to wait for DL (Down Link) data from AP MLD1, potentially causing roaming to fail (S4, S5). Note that Roaming Request and Roaming Response are names under discussion in the standardization process, and other names may be used.
[0023] In other words, while the current Seamless Roaming standard stipulates that DL data can be transferred between APs, details such as what data is sent, from which AP, and how are not defined, which may lead to roaming failures. Furthermore, if the STA does not know how much DL data it expects to receive from the current AP, it may unnecessarily continue waiting for data from the current AP, potentially delaying the switchover to the target AP.
[0024] One solution for DL data transfer is to set a timer to receive DL data (Buffered DL), continue sending DL data until the timeout occurs, then stop sending and transfer the remaining data to the target AP. However, this method has the problem that until the STA receives the remaining data that has been transferred, the data received from the target AP will be incomplete, preventing the data from being immediately passed to the higher layer.
[0025] <System Configuration> Figure 5 shows an example of the configuration of a communication system in this disclosure. In Figure 5, the communication system is a wireless LAN (Local Area Network) system composed of AP MLDs and Non-AP MLDs. AP MLD1 is the current AP and is a communication device 11-1 that corresponds to a base station compatible with Multi-link Operation (MLO). AP MLD2 is the target AP and is a communication device 11-2 that corresponds to a base station compatible with MLO. Non-AP MLD1 is a communication device 12 that corresponds to a terminal compatible with MLO. Each Non-AP MLD is connected to an AP MLD. In Figure 5, the solid and dashed lines connecting AP MLD1 and Non-AP MLD1 indicate that they are connected by different links (Link1, Link2), respectively.
[0026] The two links used in the communication system shown in Figure 5 may be two channels selected from the same frequency band, or two channels selected from different frequency bands. Furthermore, the number of links used between the AP MLD and the Non-AP MLD is not limited to two; communication may use one, three, or more links. In the communication system shown in Figure 5, the number of AP MLDs that the Non-AP MLD can connect to is not limited to two; it may be one, three, or more. This also applies to systems consisting of two or more APs and one or more STAs, even if the MLDs are not MLO-compatible.
[0027] <Configuration of the communication device> Figure 6 is a block diagram showing an example configuration of a communication device 11, which is a wireless communication device corresponding to AP MLD in this disclosure.
[0028] In Figure 6, the communication device 11 consists of a communication unit 21, a control unit 22, a storage unit 23, a WAN (Wide Area Network) communication unit 24, and an antenna 25. The communication unit 21 includes a communication control unit 31, a communication storage unit 32, a data processing unit 40, a signal processing unit 43, a wireless interface unit 44, and an amplification unit 45. The data processing unit 40 can be configured to include a common data processing unit 41 and individual data processing units 42.
[0029] The communication control unit 31 controls the operation of each part and the transmission of information between each part. The communication control unit 31 also controls the transfer of control information and management information to be notified to other communication devices to each data processing unit 40. The communication storage unit 32 holds the information used by the communication control unit 31. The communication storage unit 32 also holds the data to be transmitted and the data that has been received.
[0030] When transmitting, the data processing unit 40 performs sequence management of the data held in the communication storage unit 32 and the control and management information received from the communication control unit, generates data units by performing encryption processing, performs channel access operations based on carrier sense, adds a MAC (Media Access Control) header and error detection codes to the data to be transmitted, and performs multiple data unit linking processing. When receiving, the data processing unit 40 performs MAC header unlinking processing of the received data unit, analysis and error detection, retransmission request operation, data unit decryption processing and reordering processing.
[0031] The data processing unit 40 may consist of individual data processing units 42 that perform operations necessary for communication in a single frequency band, and a common data processing unit 41 that is connected to multiple individual data processing units 42 and performs operations common to communication in multiple frequency bands. In this disclosure, the common data processing unit 41 is also referred to as AP MLD / Non-AP MLD. In particular, in an AP, the common data processing unit 41 may consist of two blocks: a block dedicated to this communication device (AP MLD) and a shared block (SMD-ME / SMD Upper MAC) that can communicate with other communication devices.
[0032] Furthermore, it is not necessary to have a common data processing unit 41; in this case, processing is performed in the common data processing unit of another communication device. Even if a common data processing unit 41 is present, it may be operated so that processing is performed in the common data processing unit of another communication device rather than in its own unit. In addition, the AP MLD / Non-AP MLD may consist not only of the common data processing unit 41, but also of the communication control unit 31 and a part of the communication storage unit 32.
[0033] The signal processing unit 43 includes a transmit signal processing unit and a receive signal processing unit. The transmit signal processing unit performs encoding, interleaving, and modulation of data units, adds a physical header, and generates a symbol stream. The receive signal processing unit analyzes the physical header, performs demodulation, deinterleaving, and decoding of the symbol stream, and generates data units. The signal processing unit 43 also performs complex channel characteristic estimation and spatial separation processing as needed. In this disclosure, the signal processing unit 43 is also referred to as the PHY unit.
[0034] The wireless interface unit 44 includes a transmitting wireless interface unit and a receiving wireless interface unit. The transmitting wireless interface unit performs digital-to-analog signal conversion, filtering, upconversion, and phase control on the symbol stream to generate a transmission signal. The receiving wireless interface unit performs downconversion, filtering, and analog-to-digital signal conversion on the received signal to generate a symbol stream.
[0035] The amplification unit 45 includes a transmitting amplification unit and a receiving amplification unit. The transmitting amplification unit amplifies the signal input from the transmitting radio interface unit. The receiving amplification unit amplifies the signal input from the antenna 25. Part of the amplification unit 45 may be an external component of the communication unit 21. Also, part of the amplification unit 45 may be incorporated into the radio interface unit 44. In this disclosure, the radio interface unit 44 and the amplification unit 45 together are referred to as the RF unit.
[0036] The control unit 22 controls the communication unit 21 and the communication control unit 31. The control unit 22 may also perform some of the operations of the communication control unit 31. The control unit 22 and the communication control unit 31 may be configured as a single block. The storage unit 23 holds information used by the control unit 22 and the communication unit 21. The storage unit 23 may also perform some of the operations of the communication storage unit 32. The storage unit 23 and the communication storage unit 32 may be configured as a single block.
[0037] The wireless interface unit 44, the amplification unit 45, and the antenna 25 may be considered as one set, and two or more sets may constitute components of the communication device 11. The data processing unit 40 and the signal processing unit 43 may be considered as one set, and two or more sets may be connected to one wireless interface unit 44. The WAN communication unit 24 decodes packets acquired from the backhaul link and passes them to the communication unit 21 via the control unit 22. The communication unit 21 may be implemented by one or more LSIs. Note that the configuration of the communication unit 21 is just an example and is not limited thereto. For example, the communication unit 21 may be composed of three or more blocks. Also, if it is composed of three or more blocks, some of the blocks may share the same antenna via a frequency division unit.
[0038] Figure 7 is a block diagram showing an example configuration of a communication device 12, which is a wireless communication terminal compatible with Non-AP MLD in this disclosure.
[0039] In Figure 7, the communication device 12 consists of a communication unit 51, a control unit 52, a storage unit 53, and an antenna 54. The communication unit 51 includes a communication control unit 61, a communication storage unit 62, a data processing unit 70, a signal processing unit 73, a wireless interface unit 74, and an amplification unit 75. The data processing unit 70 can be configured to include a common data processing unit 71 and individual data processing units 72.
[0040] The communication unit 51, control unit 52, storage unit 53, and antenna 54 in Figure 7 are configured similarly to the communication unit 21, control unit 22, storage unit 23, and antenna 25 in Figure 6, so their explanation is omitted here. The communication control unit 61, communication storage unit 62, data processing unit 70, signal processing unit 73, wireless interface unit 74, and amplification unit 75 in Figure 7 are configured similarly to the communication control unit 31, communication storage unit 32, data processing unit 40, signal processing unit 43, wireless interface unit 44, and amplification unit 45 in Figure 6. The common data processing unit 71 and individual data processing unit 72 in Figure 7 are configured similarly to the common data processing unit 41 and individual data processing unit 42 in Figure 6.
[0041] Furthermore, the communication device 11 in Figure 6 corresponds to the communication devices 11-1 to 11-4 in Figures 1 to 3, the AP MLD Entity 33 corresponds to AP MLD1 to AP MLD4, and AP34-1 to 34-n (n: natural number) corresponds to AP1-1, AP1-2, AP2-1, AP2-2, AP3-1, AP3-2, AP4-1, and AP4-2. Also, the communication device 12 in Figure 7 corresponds to the communication device 12 in Figures 1 to 3, the Non-AP MLD 63 corresponds to Non-AP MLD1, and STA64-1 to 64-m (m: natural number) corresponds to STA1-1 and STA1-2.
[0042] <Operation Flow> Figure 8 is a flowchart explaining the operation of the current AP. Each step in Figure 8 is executed by the control unit 22 controlling each part in the communication device 11 corresponding to the current AP.
[0043] In step S11, the current AP exchanges communication environment information. The communication environment information exchanged with other communication devices such as the target AP and STA includes, for example, the following: information regarding backhaul communication, information regarding Non-AP MLD, information regarding AP / AP MLD buffer size, BSS AC Access Delay element, and information regarding whether it supports the operation proposed in this disclosure.
[0044] Information regarding Non-AP MLD includes information such as the amount of buffered data, lifetime, traffic pattern, and information regarding simultaneous transmission and reception on multiple links. Information regarding simultaneous transmission and reception on multiple links includes information such as the number of frequency bands (single radio / multi radio), NSTR (Non-Simultaneous Transmit and Receive) capability, etc. The BSS AC Access Delay element includes information regarding the AC (Access Category) access delay of the BSS (Basic Service Set).
[0045] In step S12, the current AP receives a Roaming Request or a Preparation Request from the STA.
[0046] In step S13, the current AP determines whether to transfer the DL data (Buffered DL) buffered in itself to another AP based on information such as communication environment information and information regarding data transfer. The method of determination here is, for example, as follows. First, when capability information regarding data transfer is exchanged between APs, it can be determined to transfer data to another AP. At this time, as the capability information regarding data transfer between APs, information regarding the amount of data that can be transferred and time may be exchanged.
[0047] Second, it can be determined based on the transfer time of Dynamic context (e.g., SN (Sequence Number)) or the necessity of transmission as information regarding data transfer. That is, when receiving information from the STA indicating that the transfer of Dynamic context is unnecessary, or when it is expected that the transfer of Dynamic context will take a long time, it is determined not to perform data transfer from the current AP to the target AP. At this time, it may be determined to transmit all buffered data by itself, and when receiving information indicating that the transmission of Dynamic context is necessary, or when it is expected that the transfer time of Dynamic context is sufficiently short, it may be determined to transfer data from the current AP to the target AP.
[0048] Third, information regarding the data reception method may be received from the STA and determined based on the received information. Examples of the information received here include information regarding the size, time, and priority of data received from the current AP and the target AP, and information instructing not to receive data from the current AP. Note that the information may be included in the Preparation Request or Roaming Request, or may be notified in another frame or the like. In the current AP, the information notified in the Preparation Request, Roaming Request, another frame, or the like can be treated as communication environment information or information regarding data transfer.
[0049] Here, the current AP may predetermine candidate methods for transmitting DL and notify the AP and STA of these candidate methods and their identifiers, for example, in the Preparation Response. These candidate methods and their identification methods may be recognized by the AP and STA through a predetermined table. Examples of how candidate methods are described include identification using 1-bit information indicating whether or not data is transmitted from the current AP, or identification using a table relating to the size, time, and priority of data received from the current AP. For example, when using time for identification using the latter table, the subfield value may be identified based on a correspondence table such as 0 = 0us, 1 = 128us, 2 = 256us, and specifying 0us may indicate that no data is transmitted from the current AP.
[0050] If it is determined in step S13 to transfer data, the process proceeds to step S14. In step S14, the current AP sends data to the target AP. Here, based on the decision in step S13, data of a specific size and with a specific TID (Traffic Identifier) is sent to the target AP. On the other hand, if it is determined in step S13 not to transfer data, step S14 is skipped and the process proceeds to step S15.
[0051] In step S15, the current AP notifies the STA and target AP of information regarding the data transmission method. The information notified here includes, for example, information about DL data to be transmitted from itself or the target AP. Specifically, the information about DL data includes information such as priority (TID: Traffic Identifier), size, and SN (Sequence Number). The notification method can be, for example, by sending it in a frame such as a Preparation Response or Roaming Response, or by sending it in buffered DL data (header or frame body) before the Roaming Response.
[0052] As described above, in the communication device 11 configured as a current AP, the control unit 22 performs control to send data to the STA and control to communicate with the target AP, based on a data transmission method determined based on at least one of the communication environment information exchanged with the STA and the data transfer information exchanged with the target AP. Specifically, the control unit 22 performs control to determine the data transmission method based on at least one of the communication environment information and the data transfer information. Here, the communication environment information includes at least one of the following: information about the STA (Non-AP MLD), information about the data buffer temporarily held in the AP (e.g., buffer size), and information about the AP's backhaul communication. The data transfer information includes at least one of the following: information about the size and time of the transferable data exchanged between APs, information about the data's dynamic context, and information about the method of receiving the data received from the STA.
[0053] In this way, the current AP notifies other communication devices such as the target AP and STA of the data transmission method it has decided on. For example, the STA can then quickly start wireless communication with the target AP, the AP to which the connection is being switched, based on the notified data transmission method, without unnecessarily waiting for data from the current AP, the AP from which the connection was switched. Therefore, the STA can switch to the destination AP and perform wireless communication more quickly.
[0054] Furthermore, in the communication device 11 configured as the current AP, the control unit 22 can pre-determine candidate transmission methods, which are candidates for data transmission methods, and notify other communication devices such as the target AP and STA of the candidate transmission methods and identification information that identifies the data transmission method from the candidate transmission methods. This allows information regarding the data transmission method to be notified while suppressing the increase in the transmission time of non-data information during AP switching. Moreover, when there are constraints on information exchange between the current AP and the target AP, it is possible to suppress the increase in the time from the start to the completion of AP switching.
[0055] Figure 9 is a flowchart illustrating the operation of the target AP. Each step in Figure 9 is executed by the control unit 22 controlling each part of the communication device 11, which corresponds to the target AP.
[0056] In step S21, the target AP exchanges communication environment information. The communication environment information exchanged with other communication devices such as the current AP and STA includes, for example, the following: information about backhaul communication, information about non-AP MLDs, information about AP / AP MLD buffer amounts, BSS AC Access Delay element, and information about whether it supports the operation proposed in this disclosure. Information about non-AP MLDs includes information such as the amount of buffered data, lifetime, traffic pattern, and information about simultaneous transmission and reception on multiple links. Information about simultaneous transmission and reception on multiple links includes information such as the number of frequency bands and NSTR capability.
[0057] In step S22, the target AP receives information regarding the data transmission method notified by the current AP. The information received here is the same as the information notified in step S15 in Figure 8.
[0058] In step S23, the target AP determines the completion of DL data transmission from the current AP based on the data transmission method notified in step S22 or the notification from the STA. The methods for determining completion here are, for example, as follows: Firstly, the target AP can determine completion by having the current AP send a Buffered DL transmission completion notification indicating that the transmission of buffered DL data has been completed, and receiving this notification. Secondly, the target AP can determine completion by having the STA, which has completed receiving buffered DL data and completed switching to the link with the target AP, send a UL addressed to the target AP, or send information regarding the completion of the link switchover, and receiving this information. Thirdly, the target AP can determine completion by the expiration of the pre-configured Buffered DL transmission period from the current AP. The Buffered DL transmission period indicates the period during which the current AP transmits buffered DL data.
[0059] In step S23, if it is determined that the DL data from the current AP is not yet complete, step S23 is repeated. On the other hand, if it is determined that the DL data from the current AP is complete, the process proceeds to step S24. In step S24, the target AP starts communication with the STA and sends the DL data to the STA.
[0060] As described above, in the communication device 11 configured as a target AP, the control unit 22 performs control to send data to the STA and control to communicate with the current AP, based on a data transmission method determined based on at least one of the communication environment information exchanged with the STA and the data transfer information exchanged with the current AP. Specifically, the control unit 22 performs control to send the data transferred from the current AP to the STA based on the data transmission method received from the current AP. In addition, in the communication device 11 configured as a target AP, the control unit 22 may determine at least a part of the data transmission method based on the communication environment information and the data transfer information.
[0061] In addition, in the communication device 11 configured as a target AP, the control unit 22 may identify a data transmission method based on a transmission method candidate, which is a predetermined list of data transmission method candidates notified from the current AP, and identification information that identifies a data transmission method from the transmission method candidate.
[0062] Figure 10 is a flowchart illustrating the operation of the STA. Each step in Figure 10 is executed by the control unit 52 controlling each part in the communication device 12, which corresponds to the STA.
[0063] In step S31, the STA exchanges communication environment information. The communication environment information exchanged with other communication devices such as the current AP and target AP includes, for example, the following: information about Non-AP MLD, information about the buffer amount of AP / AP MLD, BSS AC Access Delay element, and information about whether it supports the operation proposed in this disclosure. Information about Non-AP MLD includes information such as the amount of buffered data, lifetime, traffic pattern, and information about simultaneous transmission and reception on multiple links. Information about simultaneous transmission and reception on multiple links includes information such as the number of frequency bands and NSTR capability. The STA may also transmit information about the data reception method described in the explanation of step S13 in Figure 8 above to the current AP.
[0064] In step S32, the STA receives information regarding the data transmission method notified by the current AP. The information received here is the same as the information notified in step S15 in Figure 8.
[0065] In step S33, the STA determines that the DL data from the current AP has expired. The methods for determining this expiration are, for example, as follows: Firstly, it can be determined by the completion of receiving the data size or time included in the data transmission method notified in step S32. Secondly, it can be determined by having the current AP send information regarding the expiration of the DL data and receiving it. Thirdly, it can be determined by not receiving buffered DL data from the current AP between the Roaming Request and the Roaming Response.
[0066] In step S33, if it is determined that the DL data from the current AP is not yet complete, step S33 is repeated and DL data is received from the current AP. On the other hand, if it is determined that the DL data from the current AP is complete, the process proceeds to step S34. In step S34, the STA starts communication with the target AP and receives DL data from the target AP.
[0067] As described above, in the communication device 12 configured as an STA, the control unit 52 performs control to receive data transmitted from the current AP and control to receive data transferred from the current AP and transmitted from the target AP based on the data transmission method notified by the current AP. Here, the data transmission method is information regarding data transmission, which is determined based on at least one of the data transfer information exchanged between APs and the communication environment information exchanged with the current AP.
[0068] In addition, in a communication device 12 configured as an STA, the control unit 52 may identify a data transmission method based on a transmission method candidate, which is a predetermined list of data transmission method candidates notified from the current AP, and identification information that identifies a data transmission method from the transmission method candidate.
[0069] <Example> Figure 11 is a diagram showing an example of a Seamless Roaming sequence in this disclosure. In Figure 11, the frame exchange between each communication device, AP MLD1 (AP1-1, AP1-2), AP MLD2 (AP2-1, AP2-2), and Non-AP MLD1 (STA1-1, STA1-2), is shown in chronological order, corresponding to the configurations shown in Figures 1 to 3 and Figure 5. In this example, AP MLD1 is the current AP and AP MLD2 is the target AP. Figure 11 shows an example for a single radio terminal that performs a preparation procedure as a preparatory step for roaming.
[0070] The current AP performs preparation and collects information such as the backhaul condition, the DL buffer size of the current AP / target AP, and whether the STA is multi-radio or single-radio (S41, S42). Subsequently, the current AP decides on the method of sending DL data after receiving a Roaming Request (data transmission method) based on the collected information. At this time, the current AP may decide not to send dynamic context after the Roaming Request and notify the STA of not performing data transfer between APs, based on a request from the STA. Alternatively, the current AP may decide on candidate methods for sending DL data and include these candidates in the Preparation Response for notification.
[0071] The STA notifies the Roaming Request of information regarding the desired data transmission method (S43). When the current AP transmits buffered DL data, it includes information regarding the amount of buffered DL to transmit in the header (S44). This information may be transmitted in the DL data transmitted after the Roaming Response (Buffered DL), rather than in the DL data transmitted between the Roaming Request and the Roaming Response (S45, S46). At this time, dynamic context transfer, DS mapping modification, and data transfer occur between AP MLD1 and AP MLD2.
[0072] When STA receives DL data (Buffered DL), after receiving a Roaming Response, it receives the DL data based on the notified information, and after reception is complete, it deletes the link with the current AP and enables the link with the target AP, switching the links (S47, S48). If STA does not receive DL data, upon receiving a Roaming Response, STA determines that the current AP has transferred all data to the target AP and promptly enables the link with the target AP. The current AP measures the backhaul delay between APs in advance by exchanging frames for measurement.
[0073] The target AP detects that the STA has completed link switching to it in one of the following ways: Firstly, it detects this by having the current AP send a Buffered DL transmission completion notification and receiving it. Secondly, it detects this by having the STA, which has completed receiving DL data (Buffered DL) and completed the switchover, send an UL (Up Link) or switchover completion notification and receiving it (S49). Thirdly, it determines this by the expiration of the pre-configured Buffered DL transmission period from the current AP.
[0074] <Format Example> Figure 12 shows an example of the format of a frame that notifies the data transmission method. This frame may include specific frames such as a Preparation Response or a Roaming Response.
[0075] As shown in Figure 12, the frame consists of the following fields: Element ID, Length, Element ID Extension, current AP Transmission info, and target AP Transmission info. Element ID specifies the identifier of this element. Length specifies the length of this element. Element ID Extension specifies the identifier of this element.
[0076] The `current AP Transmission info` specifies information about data transmission from the current AP. This includes information about the priority, size, and transmission time of the data transmitted from the current AP. The `target AP Transmission info` specifies information about data transmission from the target AP. This includes information about the priority, size, and transmission time of the data transmitted from the target AP. Note that if `current AP Transmission info` is included in a given frame, `target AP Transmission info` may not be included.
[0077] Note that the example shown in Figure 12 is just one example, and it may not be defined as an element as in the example in Figure 12, but may be written in the frame body, or it may be written in the PHY header, MAC header, etc.
[0078] Figure 13 shows an example of a format for storing information indicating how to send data in the PHY header.
[0079] As shown in Figure 13, the actual data, Data, has fields such as L-STF (Legacy Short Training Field), L-LTF (Legacy Long Training Field), L-SIG (Legacy Signal Field), RL-SIG (Repeated Legacy Signal Field), U-SIG (Universal Signal Field), EHT-SIG (Extremely High Throughput Signal Field), EHT-STF (Extremely High Throughput Short Training Field), and EHT-LTF (Extremely High Throughput Long Training Field) added to it. Note that PE (Packet Extension) is data packet extension.
[0080] When included in the PHY header, for example, at least one of the fields shown in Figure 12, current AP Transmission info and target AP Transmission info, will be included in the U-SIG, for example.
[0081] Figure 14 shows an example of the format when information indicating how to send data is stored in the MAC header.
[0082] In Figure 14, the Frame Body with the MAC header and FCS (Frame Check Sequence) attached is placed in the Data field in Figure 13. As shown in Figure 14, the MAC header includes Frame Control, Duration / ID, Address1-4, Sequence Control, QoS Control, and HT Control. When describing the MAC header, for example, by setting B0 and B1 of the HT Control field in the MAC header to 1, B2 and beyond can be treated as A-Control fields. Then, as new Control information within the A-Control field, at least one of the fields shown in Figure 12, current AP Transmission info and target AP Transmission info, is described.
[0083] <Application Example> Similarly, for UL (Up Link) from STA, when forwarding from the current AP to the target AP, information regarding the UL forwarding may be used to determine the amount of data to be forwarded to the target AP. Details of this technology are described in Japanese Patent Application No. 2024-195605. In addition, if information regarding UL traffic is received during the Roaming Request / Response period, the transmission method may be determined based on that information. Details of this technology are described in Japanese Patent Application No. 2024-196327.
[0084] <Variation> The series of processes described above can be executed by hardware or by software. When the series of processes are executed by software, the programs that make up the software are installed from a program storage medium onto a computer built into dedicated hardware, or a general-purpose PC (Personal Computer).
[0085] For example, in a computer that performs the above-described series of processes using a program, the CPU (Central Processing Unit) loads the program stored in a storage unit, such as a hard disk or non-volatile memory, into RAM (Random Access Memory) and executes it, thereby performing the above-described series of processes. The program executed by the computer may be a program that processes in chronological order according to the order described herein, or it may be a program that processes in parallel or at necessary times, such as when a call is made.
[0086] This disclosure is applicable to a variety of products. For example, the communication device 12 may be configured as a mobile terminal such as a smartphone, tablet PC, notebook PC, portable game terminal, or digital camera; a fixed terminal such as a television receiver, printer, digital scanner, or network storage; or an in-vehicle terminal such as a car navigation system. The communication device 12 may also be configured as an M2M (Machine To Machine Communication) terminal such as a smart meter, vending machine, remote monitoring device, or POS (Point Of Sale) terminal. Furthermore, the communication device 12 may be a wireless communication module (for example, an integrated circuit module consisting of a single die) mounted on these terminals.
[0087] Furthermore, the communication device 11 may be configured as a wireless LAN base station (AP) with or without router functionality. Alternatively, the communication device 11 may be configured as a mobile wireless LAN router. Furthermore, the communication device 11 may be a wireless communication module (for example, an integrated circuit module consisting of a single die) mounted on these devices.
[0088] The embodiments described herein are not limited to those described above, and various modifications are possible without departing from the spirit of this disclosure. Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also occur.
[0089] Furthermore, in this specification, the processes performed by a computer according to a program do not necessarily have to be performed chronologically in the order described in the flowchart. That is, the processes performed by a computer according to a program include processes that are executed in parallel or individually (for example, parallel processing or object-based processing). Also, the program may be processed by one computer (processor) or it may be processed in a distributed manner by multiple computers. Moreover, if a single step includes multiple processes, those processes included in that single step may be executed by one device or distributed among multiple devices.
[0090] Furthermore, this disclosure can take the following form.
[0091] (1) A wireless communication device comprising a control unit that performs control for transmitting data to a wireless communication terminal based on a data transmission method determined based on at least one of communication environment information exchanged with a wireless communication terminal and data transfer information exchanged with a first wireless communication device, and control for communicating with the first wireless communication device. (2) The wireless communication device according to (1), wherein the communication environment information includes at least one of information relating to the wireless communication terminal, information relating to a data buffer temporarily held in the wireless communication device, and information relating to backhaul communication of the wireless communication device. (3) The wireless communication device according to (1) or (2), wherein the data transfer information includes at least one of information relating to the size and time of transferable data exchanged between the first wireless communication device and the wireless communication device, information relating to the Dynamic Context of the data, and information relating to a method of receiving the data received from the wireless communication terminal. (4) The wireless communication device according to (3), wherein the Dynamic Context information is information relating to the transfer time or whether the Dynamic Context needs to be transmitted. (5) The control unit performs control to determine the data transmission method based on the communication environment information and the data transfer information, according to any one of (1) to (4). (6) The control unit determines in advance a candidate transmission method which is a candidate for the data transmission method, and notifies at least one of the first wireless communication device and the wireless communication terminal of the candidate transmission method and identification information which identifies the data transmission method from the candidate transmission method, according to (5). (7) The control unit performs control to transmit the data transferred from the first wireless communication device to the wireless communication terminal based on the data transmission method received from the first wireless communication device, according to any one of (1) to (4). (8) The control unit identifies the data transmission method based on the candidate transmission method received from the first wireless communication device and identification information which identifies the data transmission method from the candidate transmission method, according to (7).(9) A wireless communication device according to any one of (1) to (8), wherein the data transmission method includes at least one of the priority, size, and sequence number of the data. (10) A wireless communication device according to any one of (1) to (9), wherein the control unit determines that the transmission of the data from the first wireless communication device has been completed based on at least one of the data transmission method received from the first wireless communication device and a notification from the wireless communication terminal or the first wireless communication device. (11) A wireless communication device according to any one of (1) to (10), wherein the data transmission method is notified by being stored in a specific frame or in a PHY header or MAC header. (12) A wireless communication device according to any one of (1) to (11), wherein the wireless communication device or the first wireless communication device transmits the data to the wireless communication terminal via a plurality of wireless transmission paths. (13) A wireless communication method comprising the wireless communication device transmitting data to the wireless communication terminal based on a data transmission method determined based on at least one of communication environment information exchanged with the wireless communication terminal and information regarding data transfer exchanged with the first wireless communication device, and communicating with the first wireless communication device. (14) A wireless communication terminal comprising a control unit that performs control for receiving data transmitted from a first wireless communication device and control for receiving data transferred from the first wireless communication device and transmitted from a second wireless communication device different from the first wireless communication device, based on a data transmission method notified by the first wireless communication device, wherein the data transmission method is information for transmitting the data, determined based on at least one of information relating to data transfer exchanged between the first wireless communication device and the second wireless communication device and communication environment information exchanged with the first wireless communication device. (15) The wireless communication terminal according to (14), wherein the communication environment information includes at least one of information relating to the wireless communication terminal, information relating to a buffer of the data temporarily held by the first wireless communication device and the second wireless communication device, and information relating to backhaul communication between the first wireless communication device and the second wireless communication device.(16) The wireless communication terminal according to (14) or (15), wherein the information relating to the data transfer includes at least one of the following: information relating to the size and time of transferable data exchanged between the first wireless communication device and the second wireless communication device; information relating to the dynamic context of the data; and information relating to the method of receiving the data received from the wireless communication terminal. (17) The wireless communication terminal according to any one of (14) to (16), wherein the control unit identifies the data transmission method based on a transmission method candidate received from the first wireless communication device and identification information that identifies the data transmission method from the transmission method candidate. (18) The wireless communication terminal according to any one of (14) to (17), wherein the data transmission method includes at least one of the priority, size, and sequence number of the data. (19) The wireless communication terminal according to any one of (14) to (18), wherein the data transmission method is notified by being stored in a specific frame or in the PHY header or MAC header. (20) A wireless communication terminal according to any one of (14) to (19), wherein the control unit receives the data transmitted from the first wireless communication device or the second wireless communication device via a plurality of wireless transmission paths. (21) A wireless communication terminal comprising receiving data transmitted from a first wireless communication device and receiving data transferred from the first wireless communication device and transmitted from a second wireless communication device different from the first wireless communication device, based on a data transmission method notified by the first wireless communication device, wherein the data transmission method is a wireless communication method in which information relating to the transmission of the data is determined based on at least one of information relating to data transfer exchanged between the first wireless communication device and the second wireless communication device and information relating to communication environment exchanged with the first wireless communication device.
[0092] 11 Communication device, 12 Communication device, 13 DS, 21 Communication unit, 22 Control unit, 23 Storage unit, 24 WAN communication unit, 25 Antenna, 31 Communication control unit, 32 Communication storage unit, 40 Data processing unit, 41 Common data processing unit, 42 Individual data processing unit, 43 Signal processing unit, 44 Wireless interface processing unit, 45 Amplifier unit, 51 Communication unit, 52 Control unit, 53 Storage unit, 54 Antenna, 61 Communication control unit, 62 Communication storage unit, 70 Data processing unit, 71 Common data processing unit, 72 Individual data processing unit, 73 Signal processing unit, 74 Wireless interface processing unit, 75 Amplifier unit
Claims
1. A wireless communication device comprising a control unit that performs control for transmitting data to a wireless communication terminal based on a data transmission method determined based on at least one of communication environment information exchanged with a wireless communication terminal and data transfer information exchanged with a first wireless communication device, and control for communicating with the first wireless communication device.
2. The wireless communication device according to claim 1, wherein the communication environment information includes at least one of the following: information relating to the wireless communication terminal; information relating to the data buffer temporarily held in the wireless communication device; and information relating to the backhaul communication of the wireless communication device.
3. The wireless communication device according to claim 1, wherein the information relating to the data transfer includes at least one of the following: information relating to the size and time of transferable data exchanged between the first wireless communication device and the wireless communication device; information relating to the dynamic context of the data; and information relating to the method of receiving the data received from the wireless communication terminal.
4. The wireless communication device according to claim 3, wherein the information relating to the Dynamic Context is information relating to the transfer time or whether or not the Dynamic Context needs to be transmitted.
5. The wireless communication device according to claim 1, wherein the control unit performs control to determine the data transmission method based on the communication environment information and the data transfer information.
6. The wireless communication device according to claim 5, wherein the control unit predetermines a candidate transmission method which is a candidate for the data transmission method, and notifies at least one of the first wireless communication device and the wireless communication terminal of the candidate transmission method and identification information which identifies the data transmission method from the candidate transmission method.
7. The wireless communication device according to claim 1, wherein the control unit controls the transmission of the data transferred from the first wireless communication device to the wireless communication terminal based on the data transmission method received from the first wireless communication device.
8. The wireless communication device according to claim 7, wherein the control unit determines that the transmission of the data from the first wireless communication device has been completed based on at least one of the data transmission method received from the first wireless communication device and a notification from the wireless communication terminal or the first wireless communication device.
9. The wireless communication device according to claim 7, wherein the control unit identifies the data transmission method based on a candidate transmission method received from the first wireless communication device and identification information that identifies the data transmission method from the candidate transmission method.
10. The wireless communication device according to claim 1, wherein the data transmission method includes at least one of the priority, size, and sequence number of the data.
11. The wireless communication device according to claim 1, wherein the data transmission method is notified by storing the data in a specific frame, or in a PHY header or MAC header.
12. A wireless communication method comprising: a wireless communication device transmitting data to a wireless communication terminal based on a data transmission method determined based on at least one of communication environment information exchanged with a wireless communication terminal and information regarding data transfer exchanged with a first wireless communication device; and communicating with the first wireless communication device.
13. A wireless communication terminal comprising a control unit that performs control for receiving data transmitted from a first wireless communication device, and control for receiving data transferred from the first wireless communication device, which is transmitted from a second wireless communication device different from the first wireless communication device, based on a data transmission method notified by the first wireless communication device, wherein the data transmission method is information regarding the transmission of the data, which is determined based on at least one of information regarding data transfer exchanged between the first wireless communication device and the second wireless communication device and information regarding the communication environment exchanged with the first wireless communication device.
14. The wireless communication terminal according to claim 13, wherein the communication environment information includes at least one of the following: information relating to the wireless communication terminal; information relating to the data buffer temporarily held in the first wireless communication device and the second wireless communication device; and information relating to the backhaul communication of the first wireless communication device and the second wireless communication device.
15. The wireless communication terminal according to claim 13, wherein the information relating to the data transfer includes at least one of the following: information relating to the size and time of transferable data exchanged between the first wireless communication device and the second wireless communication device; information relating to the dynamic context of the data; and information relating to the method of receiving the data received from the wireless communication terminal.
16. The wireless communication terminal according to claim 13, wherein the control unit identifies the data transmission method based on a candidate transmission method received from the first wireless communication device and identification information that identifies the data transmission method from the candidate transmission method.
17. The wireless communication terminal according to claim 13, wherein the data transmission method includes at least one of the priority, size, and sequence number of the data.
18. The wireless communication terminal according to claim 13, wherein the data transmission method is notified by storing the data in a specific frame, or in the PHY header or MAC header.
19. The wireless communication terminal according to claim 13, wherein the control unit receives the data transmitted from the first wireless communication device or the second wireless communication device via a plurality of wireless transmission paths.
20. A wireless communication method comprising: a wireless communication terminal receiving data transmitted from a first wireless communication device; and receiving data transferred from the first wireless communication device, transmitted from a second wireless communication device different from the first wireless communication device, based on a data transmission method notified by the first wireless communication device, wherein the data transmission method is a wireless communication method in which information relating to the transmission of the data is determined based on at least one of information relating to data transfer exchanged between the first wireless communication device and the second wireless communication device and information relating to communication environment exchanged between the first wireless communication device and the second wireless communication device.