Wireless communication device

Abstract

To achieve efficient communication using a multi-link transmission technique.SOLUTION: A wireless communication device includes a plurality of sets of a wireless unit and a control unit, and a host control unit. Each control unit determines a reception status as to whether or not each wireless unit has normally received each data frame received from other wireless communication device. Each data frame can be received by any of the plurality of wireless units after communication is established and has a sequence control field and a frame body field. A number stored in the sequence control field is assigned to each data stored in the frame body field. Each control unit holds reception history information indicating a reception status of each data frame. A start number corresponding to the number stored in the sequence control field of each data frame is set in each reception history information. The host control unit performs control so that difference between start numbers set in each reception history information falls within first information.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a wireless communication device. [Background technology]

[0002] In recent years, a variety of technologies have been proposed to improve communication reliability. One of these is multi-link transmission technology. In multi-link transmission, multi-link devices, each equipped with multiple wireless functions in a single housing, cooperate with each other to establish multiple wireless links between a wireless base station multi-link device with multiple wireless functions that operates as an access point and a wireless terminal multi-link device with multiple wireless functions that operates as a station, and transmit data using these multiple wireless links. This multi-link transmission technology enables the same data to be transmitted in parallel using multiple wireless links, thereby improving communication reliability.

[0003] However, in multi-link transmission technology, data that has already been transmitted using one of multiple wireless links and for which a delivery confirmation that the transmission was successful has already been received may be transmitted separately using another wireless link, resulting in inefficient communication. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-142897 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a wireless communication device that can realize efficient communication using a multi-link transmission technique. [Means for solving the problem]

[0006] According to one embodiment, a wireless communication device includes a plurality of pairs of radio units and controllers, and a host controller. The wireless communication device establishes communication with another wireless communication device using the plurality of radio units. Each radio unit receives a plurality of data frames from the other wireless communication device. Each controller determines a reception status of each data frame, determining whether the data frame has been received correctly by the corresponding radio unit. Each data frame can be received by any of the plurality of radio units after the communication is established, and has a sequence control field and a frame body field. A number stored in the sequence control field is assigned to each piece of data stored in the frame body field. Each controller holds reception history information indicating the reception status of each data frame. A starting number corresponding to the number stored in the sequence control field of each data frame is set in each piece of reception history information. The host controller controls the start numbers set in each piece of reception history information so that the difference between the starting numbers set in each piece of reception history information is within first information. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of a schematic configuration of a wireless communication system including a wireless communication device according to an embodiment. [Figure 2] FIG. 2 is a diagram showing the frame format of a MAC frame. [Figure 3] FIG. 3 is a diagram illustrating an example of a schematic configuration of a wireless communication device according to the embodiment. [Figure 4] FIG. 4 is a flowchart showing a processing procedure executed by a wireless base station to establish a wireless connection with a wireless terminal in the Multi-Link mode. [Figure 5] FIG. 5 is a block diagram illustrating a schematic configuration example of a wireless communication system according to the embodiment. [Figure 6] FIG. 6 is a diagram showing the frame format of a beacon frame. [Figure 7]FIG. 7 is a diagram illustrating an example of a field configuration of a Multi-Link Element. [Figure 8] FIG. 8 is a diagram showing an example of setting values ​​set in each field constituting a Multi-Link Element. [Figure 9] FIG. 9 is a diagram illustrating an example of a field configuration of a Reduced Neighbor Report Element. [Figure 10] FIG. 10 is a diagram showing an example of setting values ​​set in each field constituting the Reduced Neighbor Report Element. [Figure 11] FIG. 11 is a diagram showing an example of setting values ​​set in each field constituting a Multi-Link Element included in an Association Request frame. [Figure 12] FIG. 12 is a flowchart showing a processing procedure up to the point where the multi-AP controller transfers transmission data addressed to the first wireless terminal to the first wireless base station and the second wireless base station. [Figure 13] FIG. 13 is a diagram showing an example of setting the TID, sequence number, and management number included in a transfer frame. [Figure 14] FIG. 14 is a diagram showing the frame format of an Ethernet frame. [Figure 15] FIG. 15 is a flowchart showing a processing procedure in which the first radio base station transmits transmission data to the first radio terminal. [Figure 16] FIG. 16 is a diagram showing an example of setting values ​​set in each field constituting a Multi-Link Element. [Figure 17] FIG. 17 is a diagram showing an example of setting values ​​set in each field constituting the Reduced Neighbor Report Element. [Figure 18] FIG. 18 is a diagram illustrating the frame format of an A-MPDU frame. [Figure 19] FIG. 19 is a diagram showing the frame format of a BA frame. [Figure 20] FIG. 20 is a diagram showing the frame format of a BAR frame. [Figure 21] FIG. 21 is a diagram for explaining a method for controlling the Block Ack Window. [Figure 22] FIG. 22 is a flowchart showing a processing procedure for updating the reception history of a wireless terminal. [Figure 23] FIG. 23 is a block diagram illustrating a schematic configuration example of a wireless communication system according to the embodiment. [Figure 24] FIG. 24 is a block diagram illustrating a schematic configuration example of a wireless terminal according to the embodiment. [Figure 25] FIG. 25 is a diagram for explaining control by SCC and RxRBC. [Figure 26] FIG. 26 is a flowchart showing the procedure for updating the BA window. [Figure 27] FIG. 27 is a flowchart showing another procedure for updating the BA window. [Figure 28] FIG. 28 is a diagram showing the frame format of the Action frame. [Figure 29] FIG. 29 is a diagram showing the frame format of the DELBA frame. [Figure 30] FIG. 30 is a diagram showing the frame format of the ADDBA Request frame. [Figure 31] FIG. 31 is a diagram showing the frame format of a BAR frame. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the drawings. The disclosure is merely an example, and the invention is not limited to the contents described in the following embodiments. Modifications that can be easily conceived by a person skilled in the art are naturally included in the scope of the disclosure. For clearer explanation, the size, shape, etc. of each part may be changed from the actual embodiment and shown schematically in the drawings. In multiple drawings, corresponding elements may be given the same reference numerals, and detailed description may be omitted.

[0009] [First embodiment] FIG. 1 is a diagram illustrating a schematic configuration example of a wireless communication system including a wireless communication device according to a first embodiment. The wireless communication system illustrated in FIG. 1 includes a first wireless base station AP MLD1 and a second wireless base station AP MLD2 operating as AP MLDs (Access Point Multi-Link Devices), a first wireless terminal STA MLD1 and a second wireless terminal STA MLD2 operating as non-AP MLDs (non-Access Point Multi-Link Devices), and a control device 20 connected by wire to the first wireless base station AP MLD1 and the second wireless base station AP MLD2 via a hub 10. Although details will be described later, the first wireless base station AP MLD1, the second wireless base station AP MLD2, the first wireless terminal STA MLD1, and the second wireless terminal STA MLD2 can all be realized by the same configuration, and these may all be referred to as wireless communication devices. In this specification, when there is no need to distinguish between the first wireless base station AP MLD1 and the second wireless base station AP MLD2, they may be simply referred to as the wireless base station AP MLD. Similarly, when there is no need to distinguish between the first wireless terminal STA MLD1 and the second wireless terminal STA MLD2, they may be simply referred to as wireless terminals STA MLD.

[0010] The first wireless base station AP MLD1 can communicate with both the first wireless terminal STA MLD1 and the second wireless terminal STA MLD2. The second wireless base station AP MLD2 can also communicate with both the first wireless terminal STA MLD1 and the second wireless terminal STA MLD2. In other words, both the first wireless terminal STA MLD1 and the second wireless terminal STA MLD2 belong to both the networks of the first wireless base station AP MLD1 and the second wireless base station AP MLD2, and can wirelessly communicate with the first wireless base station AP MLD1 and the second wireless base station AP MLD2 using a wireless local area network (wireless LAN) system.

[0011] 1 assumes that a first wireless terminal STA MLD1 and a second wireless terminal STA MLD2 configure an infrastructure mode network in which they perform wireless communication via a first wireless base station AP MLD1 or a second wireless base station AP MLD2. In an infrastructure mode network, the range in which a wireless signal from a wireless base station reaches the wireless terminal is called a BSS (Basic Service Set). In FIG. 1, the range in which a wireless signal from the first wireless base station AP MLD1 reaches the wireless terminal is denoted as BSS1, and the range in which a wireless signal from the second wireless base station AP MLD2 reaches the wireless terminal is denoted as BSS2.

[0012] Note that a wireless base station included in a wireless communication system does not necessarily have to be a wireless base station fixed at a certain location. For example, a wireless terminal that functions as a simple wireless base station by changing its operation mode may also operate as a wireless base station included in a wireless communication system. Here, it is assumed that a network in infrastructure mode is configured in which multiple wireless terminals included in the wireless communication system perform wireless communication via a wireless base station. However, this is not limited to this. The wireless communication system may also configure a network in ad hoc mode in which multiple wireless terminals perform wireless communication without using a wireless base station. In this case, any one of the multiple wireless terminals may operate as the owner in the ad hoc mode network. As described above, a wireless terminal can also function as a wireless base station, and a wireless base station and a wireless terminal can be realized with the same configuration. Therefore, as described above, both a wireless base station and a wireless terminal can be referred to as a wireless communication device.

[0013] 1, a first wireless base station AP MLD1 and a second wireless base station AP MLD2 are connected to a control device 20 by wired connection (for example, Ethernet (registered trademark)) via a hub 10. The control device 20 transfers frames to be transmitted to wireless terminals to the first wireless base station AP MLD1 and the second wireless base station AP MLD2.

[0014] First, the frame format used in the wireless communication system shown in FIG. 1 will be described below. Fig. 2 is a diagram showing the frame format of a MAC (Media Access Control) frame used in wireless communication systems conforming to the IEEE 802.11 standard (IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, IEEE 802.11ac, IEEE 802.11ax, IEEE 802.11be, and future 802.11 standards).

[0015] As shown in Figure 2, a MAC frame is composed of a MAC Header, a Frame Body field, and an FCS (Frame Check Sequence) field. Information necessary for reception processing in the MAC layer is set in the MAC Header. Information according to the type of frame (e.g., data from an upper layer) is set in the Frame Body field. An error detection code (CRC: Cyclic Redundancy Code) calculated to determine whether the MAC Header and Frame Body fields have been received correctly is set in the FCS field.

[0016] As shown in Fig. 2, the MAC Header includes a Frame Control field, a Duration / ID field, an Address1 field, an Address2 field, an Address3 field, a Sequence Control field, an Address4 field, and a QoS (Quality of Service) Control field. Note that the various fields included in the MAC Header are not limited to the above-mentioned fields, and for example, new fields may be added or some fields may be deleted.

[0017] In the Frame Control field, a value according to the type of frame is set. More specifically, the Frame Control field includes a Protocol Version field, a Type field, a Subtype field, a ToDS field, a FromDS field, a More Fragment field, a Retry field, a Protected Frame field, and a +HTC / Order field, as shown in FIG. 2.

[0018] In the Protocol Version field, information indicating the protocol version to be used is set. The Type field contains a bit string that indicates the type of MAC frame, and by referring to this Type field, it is possible to determine whether the MAC frame type is a control frame, management frame, or data frame. In the Subtype field, a bit string indicating the type of MAC frame within the frame type indicated by the Type field is set.

[0019] The ToDS field contains information about the receiving station, indicating whether the receiving station is a wireless base station or a wireless terminal. Specifically, a bit of 1 indicates that the receiving station is a wireless base station, and a bit of 0 indicates that the receiving station is a wireless terminal.

[0020] The FromDS field contains information about the transmitting station, indicating whether the transmitting station is a wireless base station or a wireless terminal. Specifically, a bit of 1 indicates that the transmitting station is a wireless base station, and a bit of 0 indicates that the transmitting station is a wireless terminal.

[0021] The More Fragment field is used when upper layer data is fragmented, and information indicating whether or not a fragment frame exists afterwards is set. Specifically, a bit of 1 indicates that a fragment frame exists afterwards, and a bit of 0 indicates that no fragment frame exists afterwards.

[0022] The Retry field contains information indicating whether the frame is a retransmitted frame or not. Specifically, if the bit is 1, it indicates that the frame is a retransmitted frame, and if it is 0, it indicates that the frame is not a retransmitted frame.

[0023] The Protected Frame field contains information indicating whether the frame is encrypted (protected). Specifically, a bit of 1 indicates that the frame is encrypted, and a bit of 0 indicates that the frame is not encrypted.

[0024] The +HTC / Order field indicates that when a non-QoS data frame is transmitted, the order of the frames must not be changed when relaying the frames, and when a QoS data frame is transmitted in an IEEE802.11n / ac / ax physical frame, the MAC Header includes an HT Control field (not shown). The HT Control field is included between the QoS Control field and the Frame Body field, and is used to notify some of the functions specified in IEEE802.11n / ac / ax.

[0025] The various fields included in the Frame Control field are not limited to the above-mentioned fields, and for example, new fields may be added or some fields may be deleted.

[0026] The Duration / ID field is 16 bits long, and if the most significant bit (MSB: More Significant Bit) is 0, the lower 15 bits indicate the transmission prohibition period (NAV: Network Allocation Vector), and if the most significant bit is 1, part of the lower 15 bits indicates the identification number assigned to the wireless terminal connected to the wireless base station.

[0027] The Address1 field contains the MAC address of the direct receiving station, and is used, for example, to determine whether the frame is addressed to the device itself.

[0028] The Address2 field is set to the MAC address of the direct transmitting station. In the Address3 field, the MAC address of the device that is the final destination is set in the uplink, and the MAC address of the device that is the source is set in the downlink. The Address4 field is set only when a wireless base station transmits a frame to another wireless base station, and the MAC address of the device that is the source of the frame is set in the Address4 field.

[0029] The Sequence Control field contains the sequence number of the frame to be transmitted and the fragment number if the data is fragmented. The QoS Control field is added when the frame type indicated by the Type field is a data frame and the type of MAC frame indicated by the Subtype field is a QoS data frame. The QoS Control field includes a TID (Traffic ID) field in which an identifier corresponding to the data traffic is set, an Ack policy field in which a delivery confirmation method is set, and the like. For example, the TID field is used to determine the data traffic type. The Ack policy field is used to determine which policy, NormalAck policy, BlockAck policy, or NoAck policy, the QoS data is transmitted according to.

[0030] Next, a schematic configuration example of a wireless communication device (wireless base station and wireless terminal) according to this embodiment will be described with reference to Fig. 3. As described above, the wireless communication device 300 is a device that complies with, for example, the IEEE 802.11 standard. As described above, the configuration of the wireless communication device 300 shown in Fig. 3 can be applied to both the wireless base station AP MLD and the wireless terminal STA MLD.

[0031] 3, wireless communication device 300 includes wireless link units 310 and 320, antennas 311 and 321, a controller unit 330, a processor unit 341, a memory unit 342, and a wired I / F (Interface) unit 343. Note that wireless link unit 310 and antenna 311 and wireless link unit 320 and antenna 321 have similar functions, and therefore, in the following, only wireless link unit 310 and antenna 311 will be described as representative examples of the wireless link units and antennas.

[0032] The antenna 311 receives analog radio signals transmitted in, for example, the 2.4 GHz band, the 5 GHz band, or the 6 GHz band. The signals received by the antenna 311 are input to the radio link unit 310. The radio link unit 310 includes a PHY (Physical) layer unit 312 and an LMAC (Lower MAC) layer unit 313.

[0033] Although detailed illustration is omitted in FIG. 3, the PHY layer 312 includes an antenna switch, a wireless receiving unit, a wireless transmitting unit, an oscillator, a demodulator, a modulator, and the like.

[0034] When a received signal from the antenna 311 is input to a wireless receiving unit included in the PHY layer unit 312, the received signal is frequency-converted (down-converted) to a signal of an appropriate frequency band (e.g., a baseband signal) using a signal of the same frequency as the carrier signal generated by the oscillator unit. The frequency-converted signal is then converted to a digital signal by an ADC (Analog to Digital Converter) and input to a demodulation unit. The demodulation unit performs reception processing on the input digital signal, including predetermined demodulation and decoding processing, in accordance with, for example, the IEEE 802.11 standard (IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, IEEE 802.11ac, IEEE 802.11ax, IEEE 802.11be, and future 802.11 standards), converts the digital signal into a MAC frame specified by the IEEE 802.11 standard, and transfers the MAC frame to the LMAC layer unit 313.

[0035] The demodulator performs OFDM symbol timing synchronization, FFT (Fast Fourier Transform) processing, deinterleaving, error correction coding, etc. on the digital signal converted by the ADC. The PHY header in the PHY frame (PPDU (PHY Protocol Data Unit)) demodulated by the demodulator contains information indicating the frame length, information indicating the transmission rate, bandwidth information, etc., and this information is extracted by the demodulator. The demodulator uses the extracted information for demodulation processing or transfers it to the LMAC layer unit 313.

[0036] In the reception process, the LMAC layer unit 313 performs de-aggregation processing, CRC check processing, MAC header analysis processing, etc. When an A-MPDU frame (described later) is received, the de-aggregation processing breaks the A-MPDU frame into one or more MAC frames (MPDUs (MAC Protocol Data Units)). The CRC check processing verifies that the CRC added to each MPDU is correct. If the verification result shows that the CRC is incorrect, the MPDU to which the CRC is added is discarded. The MAC header analysis processing verifies whether the address in the Address1 field in the MAC Header matches the MAC address of the device itself (for example, the MAC address set in the wireless link unit 310). If the verification result shows that the MAC addresses match and the CRC is correct, the MAC frame to be processed is transferred to the UMAC (Upper MAC) layer unit 331 included in the controller unit 330.

[0037] Furthermore, the LMAC layer unit 313 generates a response frame when the MAC frame transferred from the PHY layer unit 312 is a frame that requires a response. The response frame generated by the LMAC layer unit 313 is a frame that mainly requires an immediate response, and is returned SIFS (Short Interframe Spacing) after the end of the PPDU that includes the MAC frame that requests the response frame (for example, a QoS data frame, an A-MPDU frame that includes multiple QoS data frames, or a BAR (Block Ack Request) frame). In the reception process, the LMAC layer unit 313 also performs a process of retaining delivery confirmation information, which indicates that the MPDU has been correctly received, in bitmap format. This bitmap information is information that is used when returning a response frame as a BA (Block Ack) frame. The above is an overview of the reception process.

[0038] On the other hand, in transmission processing, the LMAC layer unit 313 generates MAC frames (for example, data frames and control frames such as BA (Block Ack), ACK (Acknowledge), and BAR (Block Ack Request)). The LMAC layer unit 313 uses a CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) method, which checks the usage status of a wireless channel, such as whether or not other wireless communication devices are transmitting wireless signals, before deciding whether or not to transmit a MAC frame. If the wireless channel is unused for a period specified by the IEEE 802.11 standard, the LMAC layer unit 313 determines that other wireless communication devices are not transmitting wireless signals, and transfers the MAC frame to the PHY layer unit 312 to start transmission. On the other hand, if the wireless channel is busy, the transmission is postponed until the wireless channel becomes unused (idle).

[0039] When a MAC frame is transferred from the LMAC layer 313 to the PHY layer 312, a modulation unit included in the PHY layer 312 performs transmission processing on the MAC frame, including predetermined modulation and coding processing that conforms to, for example, the IEEE 802.11 standard (IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, IEEE 802.11ac, IEEE 802.11ax, IEEE 802.11be, and future 802.11 standards).The MAC frame is then converted from a digital signal to an analog baseband signal by a DAC (Digital to Analog Converter), and the baseband signal is input to a wireless transmission unit. The radio transmitting unit frequency-converts (upconverts) the input baseband signal to a predetermined frequency band (e.g., 2.4 GHz, 5 GHz, or 6 GHz band frequencies) using a carrier signal generated by the oscillator unit, and transmits the frequency-converted signal as a radio signal from the antenna via the antenna switch.

[0040] In the transmission process, the LMAC layer unit 313 performs CRC calculation processing, aggregation processing, etc. The LMAC layer unit 313 calculates the CRC of a MAC frame transferred from the UMAC layer unit 331, details of which will be described later, and transfers an MPDU frame, in which the CRC calculation result is included in an FCS field added to the end of the MAC frame, to the PHY layer unit 312. The LMAC layer unit 313 also generates an A-MPDU frame by concatenating multiple MPDUs as necessary, for example to achieve high-speed throughput, and transfers this to the PHY layer unit 312. As described above, the LMAC layer unit 313 may also generate response frames such as Ack frames and BA frames and transfer these to the PHY layer unit 312. The above is an overview of the transmission process.

[0041] The controller unit 330 performs control necessary to operate the multiple wireless link units 310 and 320. For example, the controller unit 330 sets the frequency channel and frequency bandwidth for operating each of the wireless link units 310 and 320. The controller unit 330 includes a UMAC layer unit 331. In transmission processing, the UMAC layer unit 331 generates sequence numbers to be assigned to each MPDU and performs MPDU encryption processing. In reception processing, the UMAC layer unit 331 performs processes such as decrypting encrypted MPDUs and reordering MPDUs in the order of their sequence numbers.

[0042] The wired I / F unit 343 has a function of receiving data from other devices and transmitting data to other devices using, for example, Ethernet as a wired communication method. Other wired communication functions may be used, such as PCIe (Peripheral Component Interconnect-Express), USB (Universal Serial Bus), SDIO (Secure Digital Input / Output), SPI (Serial Peripheral Interface), and UART (Universal Asynchronous Receiver / Transmitter). Note that the wired I / F unit 343 may be omitted if there is no need for a wired connection with an external device of the wireless communication device.

[0043] The memory unit 342 is configured from a data storage device such as an SRAM (static random access memory) or a DRAM (dynamic random access memory), etc. The memory unit 342 is used to temporarily store transmitted and received data transferred between the wired I / F unit 343 and the controller unit 330, and to store data when the processor unit 341 performs processing.

[0044] The processor unit 341 is, for example, a CPU (Central Processing Unit) or an MPU (Micro Processor Unit), and has the function of executing predetermined instruction codes. The processor unit 341 also controls the wireless link units 310 and 320, the controller unit 330, the wired I / F unit 343, etc. The processor unit 341 also controls the transfer of transmitted and received data between the wired I / F unit 343 and the controller unit 330.

[0045] 3, the wireless communication device 300 has been described as having two wireless link units 310 and 320, but the configuration is not limited to this and the wireless communication device 300 may have three or more wireless link units. In this case, the wireless link units may communicate using different frequency channels or may communicate using the same frequency channel.

[0046] 3, the wireless link units 310 and 320 are respectively connected to one antenna 311 and 321, but the present invention is not limited to this, and multiple antennas may be connected to each of the wireless link units 310 and 320. When multiple antennas are connected, wireless communication may be performed using a MIMO (Multiple Input Multiple Output) method, which spatially multiplexes and transmits and receives different data streams.

[0047] 3 each have a MAC address. Different MAC addresses are set for LMAC layer units 313 and 323. On the other hand, UMAC layer unit 331 may be set with the same MAC address as one of LMAC layer units 313 and 323, or may be set with a MAC address different from both LMAC layer units 313 and 323.

[0048] Each unit included in wireless communication device 300 may be realized as an analog circuit or a digital circuit, or may be realized by software executed by a CPU (Central Processing Unit). Furthermore, wireless communication device 300 may be implemented in a single LSI (Large Scale Integration), or the controller unit 330, processor unit 341, memory unit 342, and wired I / F unit 343 may be implemented in a single LSI, and wireless link units 310 and 320 may be implemented in a separate LSI. Alternatively, only the wireless transmission unit, wireless reception unit, and antenna switch constituting PHY layer units 312 and 322 may be implemented in a separate IC (Integrated Circuit).

[0049] Next, referring to the flowchart of FIG. 4, the wireless base station AP MLD The processing steps to be executed for wireless connection in MLD and Multi-Link modes will be explained.

[0050] First, the wireless base station AP MLD periodically (for example, every 100 ms) transmits a beacon frame, which is one of management frames, as a broadcast frame (step S1). This broadcasts information such as communication capabilities supported by the wireless base station AP MLD to the wireless terminal STA MLD.

[0051] Next, the wireless base station AP MLD receives a connection request frame (for example, an Association Request frame) transmitted from the wireless terminal STA MLD (step S2).

[0052] Next, when permitting the connection of the wireless terminal STA MLD, the wireless base station AP MLD transmits a connection response frame (for example, an Association Response frame) including information indicating that the connection is permitted to the wireless terminal STA MLD (step S3).

[0053] Thereafter, the radio base station AP MLD sets a communication mode for communicating with the radio terminal STA MLD (for example, a mode for performing highly reliable communication by one radio base station AP MLD alone, a mode for performing highly reliable communication in cooperation with multiple radio base stations AP MLD, etc.) in accordance with the communication mode request included in the connection request frame transmitted from the radio terminal STA MLD (step S4), and then ends the series of processes here.

[0054] Fig. 5 is a block diagram showing a schematic configuration example of a wireless communication system according to this embodiment. As already described in conjunction with Fig. 1, the wireless communication system according to this embodiment includes a first wireless base station AP MLD1, a second wireless base station AP MLD2, a first wireless terminal STA MLD1, a second wireless terminal STA MLD2, and a control device 20. The first wireless base station AP MLD1 and the second wireless base station AP MLD2 are wired connected to the control device 20 via a hub 10. The control device 20 includes a multi-AP controller 21 that controls the operation of the control device 20.

[0055] The first wireless base station AP MLD1 operating as an AP MLD includes a first access point AP1-1, a second access point AP1-2, and a controller AP CT1 that controls the operation of the first wireless base station AP MLD1. The first access point AP1-1 and the second access point AP1-2 correspond to the wireless link units 310 and 320 of the wireless communication device 300 shown in Fig. 3. The controller AP CT1 corresponds to the controller unit 330 of the wireless communication device 300 shown in Fig. 3. Similarly, the second wireless base station AP MLD2 operating as an AP MLD includes a first access point AP2-1, a second access point AP2-2, and a controller AP CT1 that controls the operation of the second wireless base station AP MLD2. The first access point AP2-1 and the second access point AP2-2 correspond to the wireless link units 310 and 320 of the wireless communication device 300 shown in Fig. 3. The controller AP CT2 corresponds to the controller unit 330 of the wireless communication device 300 shown in Fig. 3.

[0056] A first wireless terminal STA MLD1 operating as a non-AP MLD includes a first station STA1-1, a second station STA1-2, and a controller STA CT1 that controls the operation of the first wireless terminal STA MLD1. The first station STA1-1 and the second station STA1-2 correspond to the wireless link units 310 and 320 of the wireless communication device 300 shown in FIG. 3. The controller STA CT1 corresponds to the controller unit 330 of the wireless communication device 300 shown in FIG. 3. Similarly, a second wireless terminal STA MLD2 operating as a non-AP MLD includes a first station STA2-1, a second station STA2-2, and a controller STA CT2 that controls the operation of the second wireless terminal STA MLD2. The first station STA2-1 and the second station STA2-2 correspond to the wireless link units 310 and 320 of the wireless communication device 300 shown in FIG. 3. The controller STA CT2 corresponds to the controller unit 330 of the wireless communication device 300 shown in FIG. 3.

[0057] In the following, a more specific situation is assumed. A first access point AP1-1 included in the first wireless base station AP MLD1 transmits a beacon frame to the wireless terminal STA MLD. The first wireless terminal STA MLD1 receives the beacon frame and This section describes a case where multi-link operation (which may also be referred to as multi-AP multi-link operation) is performed to connect to both the first radio base station AP MLD1 and a second radio base station AP MLD2 that can operate cooperatively with the first radio base station AP MLD1.

[0058] The first access point AP1-1 included in the first wireless base station AP MLD1 periodically transmits a beacon frame, which is one type of management frame, as a broadcast frame to the wireless terminal STA MLD.

[0059] Here, with reference to FIG. 6, a beacon frame broadcast from the first access point AP1-1 included in the first wireless base station AP MLD1 to the wireless terminal STA MLD will be described.

[0060] Fig. 6 is a diagram showing the frame format of a beacon frame. As shown in Fig. 6, the beacon frame is composed of a Frame Control field, a Duration / ID field, an Address1 field, an Address2 field, an Address3 field, a Sequence Control field, a Frame Body field, and an FCS field. Note that the roles of the fields other than the Frame Body field are the same as those of the MAC frame described with reference to Fig. 2, so detailed description thereof will be omitted here.

[0061] The Type field and Subtype field of the Frame Control field are assigned a bit pattern indicating that it is a beacon frame (for example, Type=2'b00, Subtype=4'b1000, etc.), and 0 is set in the Duration / ID field.

[0062] In the Address1 field, all ones (specifically, 48'hFFFF_FFFF) are set to indicate that the beacon frame has been transmitted as a broadcast frame. In the Address2 field, the MAC address of the transmitting station is set. Here, it is assumed that the first access point AP1-1 included in the first wireless base station AP MLD1 transmits the beacon frame, so the MAC address of the first access point AP1-1 is set in the Address2 field. Note that, if the second access point AP1-2 included in the first wireless base station AP MLD1 transmits the beacon frame, the MAC address of the second access point AP1-2 is set in the Address2 field. In the Address3 field, the BSSID is set. Here, it is assumed that the BSSID is the same as that of the first access point AP1-1 that transmitted the beacon frame, so the MAC address of the first access point AP1-1 is set in the Address3 field. In the Sequence Control field, a value is set that is incremented by one each time a beacon frame is transmitted.

[0063] In the Frame Body field, a plurality of pieces of information related to the first radio base station AP MLD1 are set, such as the time to transmit the beacon frame, the transmission cycle time of the beacon frame, PHY rate information supported by the first radio base station AP MLD1, etc. Information related to the multi-link operation of the first radio base station AP MLD1 (Multi-Link Element) and information related to the frequency channel (Reduced Neighbor Report Element) are added to this Frame Body field.

[0064] Fig. 7 is a diagram showing an example of the field configuration of a Multi-Link Element. As shown in Fig. 7, a Multi-Link Element is composed of an Element ID field, a Length field, an Element ID Extension field, a Type field, an MLD MAC Address field, and a Link Info field.

[0065] The Element ID field is set to the identifier of the Multi-Link Element. The Length field is set to information indicating the length from the Element ID Extension field to the Link Info field in octets. The Element ID Extension field is set to an identifier indicating that it is a Multi-Link Element. The Type field is set to information indicating the type of Multi-Link Element. MLD The MAC Address field is set with a MAC address of a configuration corresponding to the UMAC layer, and includes the MAC addresses of the first wireless base station AP MLD1, a wireless base station capable of operating in cooperation with the first wireless base station AP MLD1 (in this case, the second wireless base station AP MLD2), and a control device 20 that is wiredly connected to the first wireless base station AP MLD1.

[0066] In the Link Info field, information for identifying a configuration (wireless link section) corresponding to the LMAC layer section included in the first radio base station AP MLD1 and a radio base station capable of cooperating with the first radio base station AP MLD1 (in this case, the second radio base station AP MLD2) is set. More specifically, the Link Info field includes a Subelement ID field, a Length field, a Link ID field, and a Link MAC Address field.

[0067] The Subelement ID field contains the identifier of the subelement. The Length field contains the length from the Link ID field to the Link MAC Information indicating the length up to the Address field in octets is set. The Link ID field is set with an identifier to identify the configuration (wireless link part) equivalent to the LMAC layer part. The Link MAC Address is set with the MAC address of the configuration (wireless link part) equivalent to the LMAC layer part.

[0068] Fig. 8 is a diagram showing an example of setting values ​​set in each field constituting a Multi-Link Element. As shown in Fig. 8, the Element ID field is set to a value "255" indicating that an Element ID Extension field is added after it. The Length field is set to a value "44" when, for example, the Link Info field includes four Subelements. The Element ID Extension field is set to a value "100" as an example. The Type field is set to a value "0" indicating a Basic Type. The MLD MAC Address is set to the MAC address of the first radio base station AP MLD1. The Link Info field includes four Subelements as described above.

[0069] As shown in Figure 8, the Subelement ID included in the first Link Info field is set to the value "3" indicating that it is a Basic variant Multi-Link element, the Length field is set to the value "7" indicating the length from the Link ID field to the Link MAC Address, the Link ID field is set to the identifier "0" for identifying the first access point AP1-1 included in the first wireless base station AP MLD1, and the Link MAC Address field is set to the MAC address of the first access point AP1-1.

[0070] In addition, the Subelement ID included in the second Link Info field is set to the value "3" indicating that it is a Basic variant Multi-Link element, and the Length field is set to the value "7" indicating the length from the Link ID field to the Link MAC Address. The ID field is set with an identifier "1" for identifying the second access point AP1-2 included in the first wireless base station AP MLD1, and the Link MAC Address field is set with the MAC address of the second access point AP1-2.

[0071] Furthermore, the Subelement ID included in the third Link Info field is set to the value "4" indicating that it is a Multi-AP variant Multi-Link element, the Length field is set to the value "7" indicating the length from the Link ID field to the Link MAC Address, the Link ID field is set to the identifier "2" for identifying the first access point AP2-1 included in the second wireless base station AP MLD2, and the Link MAC Address field is set to the MAC address of the first access point AP2-1.

[0072] In addition, the Subelement ID included in the fourth Link Info field is set to the value "4" indicating that it is a Multi-AP variant Multi-Link element, the Length field is set to the value "7" indicating the length from the Link ID field to the Link MAC Address, the Link ID field is set to the identifier "3" for identifying the second access point AP2-2 included in the second wireless base station AP MLD2, and the Link MAC Address field is set to the MAC address of the second access point AP2-2.

[0073] Next, a field configuration example of the Reduced Neighbor Report Element will be described with reference to Fig. 9. The Reduced Neighbor Report Element includes information for associating frequency channel numbers used by each wireless link unit included in the first radio base station AP MLD1 and a radio base station capable of cooperating with the first radio base station AP MLD1 (in this case, the second radio base station AP MLD2).

[0074] As shown in Fig. 9, the Reduced Neighbor Report Element is composed of an Element ID field, a Length field, and a Neighbor AP Information field. The ID field contains the identifier of the Reduced Neighbor Report Element.

[0075] As shown in FIG. 9, the Neighbor AP Information field includes a TBTT Information Header, an Operating Class field, a Channel Number field, and a TBTT Information Set field.

[0076] In a wireless communication system that complies with the IEEE802.11 standard, the position of the center frequency on the frequency can be identified by the channel number. Channel numbers are assigned at 5 MHz intervals around the center frequency, and these values ​​are set in the Channel Number field. Information on the channel width that matches the usage regulations of each country or region is set in the Operating Class field. The Channel Number field and Operating Class field make it possible to identify at which frequency position and with which channel width a wireless base station (or an access point included in it) is operating.

[0077] As shown in Figure 9, the TBTT Information Set field can include a BSSID field for notifying the BSSID, which is the identifier of the BSS, and a Short-SSID field for confirming the SSID, which is the service identifier of the wireless communication system.

[0078] The TBTT Information Header contains information for identifying whether or not a subsequent field, such as a BSSID field or a Short-SSID field, is included. This allows the wireless terminal STA MLD receiving the beacon frame to recognize whether or not an MLD Parameters field, which will be described later, is added to the subsequent field.

[0079] An MLD Parameters field can be added to the TBTT Information Set field, as shown in Fig. 9. The MLD Parameters field includes an MLD ID field and a Link ID field, as shown in Fig. 9. An identifier capable of identifying the MLD (i.e., the configuration equivalent to the UMAC layer part) is set in the MLD ID field, and for example, the MAC address of the MLD of the wireless base station AP is set. An identifier capable of identifying the wireless link part (i.e., the configuration equivalent to the LMAC layer part) is set in the Link ID field, and for example, the same value as the Link ID field included in the Link Info field of the Multi-Link Element is set.

[0080] 10 is a diagram showing an example of setting values ​​set in the BSSID field, MLD ID field, and Link ID field as main parameters included in a Reduced Neighbor Report Element. Note that here, it is assumed that a Reduced Neighbor Report Element including four Neighbor AP Information fields is included in a beacon frame. Alternatively, four Reduced Neighbor Report Elements may be included.

[0081] For example, the BSSID field included in the first Neighbor AP Information field is set to the MAC address of the first access point AP1-1, the MLD ID field is set to the MAC address of the first wireless base station AP MLD1, and the Link ID field is set to the identifier "0" for identifying the first access point AP1-1 included in the first wireless base station AP MLD1.

[0082] In addition, the BSSID field included in the second Neighbor AP Information field is set to the MAC address of the second access point AP1-2, the MLD ID field is set to the MAC address of the first wireless base station AP MLD1, and the Link ID field is set to the identifier "1" for identifying the second access point AP1-2 included in the first wireless base station AP MLD1.

[0083] Furthermore, the BSSID field included in the third Neighbor AP Information field is set to the MAC address of the first access point AP2-1, the MLD ID field is set to the MAC address of the multi-AP controller 21, and the Link ID field is set to the identifier "2" for identifying the first access point AP2-1 included in the second wireless base station AP MLD2.

[0084] In addition, the BSSID field included in the fourth Neighbor AP Information field is set to the MAC address of the second access point AP2-2, the MLD ID field is set to the MAC address of the multi-AP controller 21, and the Link ID field is set to the identifier "3" for identifying the second access point AP2-2 included in the second wireless base station AP MLD2.

[0085] When the first wireless terminal STA MLD1 receives a beacon frame including the above-mentioned Multi-Link Element and the above-mentioned Reduced Neighbor Report Element, it recognizes, based on this information, that the first wireless base station AP MLD1 can perform Multi-Link operation by itself and that the first wireless base station AP MLD1 can perform Multi-Link operation (Multi-AP Multi-Link operation) in cooperation with the second wireless base station AP MLD2.

[0086] Here, as described above, it is assumed that the first wireless terminal STA MLD1 performs Multi-Link operation to connect to both the first wireless base station AP MLD1 and the second wireless base station AP MLD2. However, for example, if the first wireless terminal STA MLD1 selects to perform Multi-Link operation with only the first wireless base station AP MLD1, the first wireless terminal STA MLD1 transmits an Association Request frame to the first access point AP1-1 requesting, for example, that the first station STA1-1 be connected to the first access point AP1-1 and the second station STA1-2 be connected to the second access point AP1-2.

[0087] When the first wireless terminal STA MLD1 selects to perform Multi-Link operation to connect to both the first wireless base station AP MLD1 and the second wireless base station AP MLD2, the first wireless terminal STA MLD1 transmits an Association Request frame to the first access point AP1-1, requesting, for example, that the first station STA1-1 be connected to the first access point AP1-1 included in the first wireless base station AP MLD1 and that the second station STA1-2 be connected to the second access point AP2-2 included in the second wireless base station AP MLD2. More specifically, the controller STA CT1 included in the first wireless terminal STA MLD1 generates an Association Request frame with a Multi-Link Element included in the Frame Body. The generated Association Request frame is transmitted by the first station STA1-1 included in the first wireless terminal STA MLD1 to the first access point AP1-1 included in the first wireless base station AP MLD1.

[0088] Fig. 11 is a diagram showing an example of the setting values ​​set in each field constituting a Multi-Link Element included in an Association Request frame. As shown in Fig. 11, the Element ID field is set to the value "255", which indicates that an Element ID Extension field is added after it. The Length field is set to the value "26", which is the length from the Element ID Extension field to the Link Info field when, for example, the Link Info field contains two Subelements. The Element ID Extension field and Type field are each 1 octet, the MLD MAC Address is 6 octets, and the Link The Subelement ID field, Length field, and Link ID field in the Info field are each one octet long, and the Link MAC Address field is six octets long. The Element ID Extension field is set to a value of "100," for example. The Type field is set to a value of "0," indicating a Basic Type. The MLD MAC Address field is set to the MAC address of the multi-AP controller 21. The Link Info field contains two Subelements, as described above.

[0089] As shown in Figure 11, the Subelement ID included in the first Link Info field is set to the value "4" indicating that it is a Multi-AP variant Multi-Link element, the Length field is set to the value "7" indicating the length from the Link ID field to the Link MAC Address, the Link ID field is set to the identifier "0" for identifying the first access point AP1-1 included in the first wireless base station AP MLD1, and the Link MAC Address field is set to the MAC address of the first access point AP1-1.

[0090] The Subelement ID included in the second Link Info field is set to the value "4" indicating that it is a Multi-AP variant Multi-Link element, and the Length field is set to the value "7" indicating the length from the Link ID field to the Link MAC Address. The ID field is set with the identifier "3" for identifying the second access point AP2-2 included in the second wireless base station AP MLD2, and the Link MAC Address field is set with the MAC address of the second access point AP2-2.

[0091] When the first access point AP1-1 included in the first wireless base station AP MLD1 receives the above-mentioned Association Request frame, it transfers the Association Request frame to the multi-AP controller 21 included in the control device 20. As a result, the multi-AP controller 21 recognizes that the first wireless terminal STA MLD1 is requesting Multi-AP Multi-Link operation to connect to both the first wireless base station AP MLD1 and the second wireless base station AP MLD2.

[0092] If there is no problem in accommodating the first wireless terminal STA MLD1, the multi-AP controller 21 notifies the first wireless base station AP MLD1 that the connection is permitted. Upon receiving the notification that the connection is permitted from the multi-AP controller 21, the first wireless base station AP MLD1 generates an Association Response frame and sets information that the connection is permitted in the frame. The Association Response frame in which the information that the connection is permitted is set is transmitted from the first access point AP1-1 included in the first wireless base station AP MLD1 to the first station STA1-1 included in the first wireless terminal STA MLD1.

[0093] When transmission of the Association Response frame is completed, the multi-AP controller 21 instructs the first wireless base station AP MLD1 and the second wireless base station AP MLD2 to accommodate the first station STA1-1 and the second station STA1-2 included in the first wireless terminal STA MLD1. As a result, the multi-AP controller 21, the controller AP CT1, and the controller AP CT2 set a mode in which the first wireless base station AP MLD1 and the second wireless base station AP MLD2 cooperate to perform highly reliable communication with the first wireless terminal STA MLD1.

[0094] Here, a case has been described in which the first wireless terminal STA MLD1 transmits an Association Request frame to the first wireless base station AP MLD1 requesting that the first station STA1-1 be connected to the first access point AP1-1 included in the first wireless base station AP MLD1 and that the second station STA1-2 be connected to the second access point AP2-2 included in the second wireless base station AP MLD2, and the first wireless terminal STA MLD1 wirelessly connects to the first wireless base station AP MLD1 and the second wireless base station AP MLD2. However, in a similar procedure, the second wireless terminal STA MLD2 can transmit an Association Request frame to the first wireless base station AP MLD1 requesting that the first station STA2-1 be connected to the first access point AP1-1 included in the first wireless base station AP MLD1 and that the second station STA2-2 be connected to the second access point AP2-2 included in the second wireless base station AP MLD2. By transmitting a Request frame to the first radio base station AP MLD2, the second radio terminal STA MLD2 can establish a wireless connection with the first radio base station AP MLD1 and the second radio base station AP MLD2.

[0095] Next, a process procedure up to when the multi-AP controller 21 transfers transmission data addressed to the first wireless terminal STA MLD1 to the first wireless base station AP MLD1 and the second wireless base station AP MLD2 will be described with reference to the flowchart in Fig. 12. The series of processes shown in Fig. 12 is performed, for example, after the first wireless terminal STA MLD1 is wirelessly connected to both the first wireless base station AP MLD1 and the second wireless base station AP MLD2.

[0096] First, when data generated in the control device 20 or data transferred from outside the control device 20 is addressed to the first wireless terminal STA MLD1, the multi-AP controller 21 starts preparations for transferring the data (transmission data) to the first wireless base station AP MLD1 and the second wireless base station AP MLD2 (step S11). Note that the data transferred to the wireless base station AP MLD is, for example, an IP (Internet Protocol) packet, and includes UDP (User Datagram Protocol) data or TCP (Transmission Control Protocol) data.

[0097] Next, the multi-AP controller 21 generates a TID and a sequence number for the transmission data to be transferred to the first wireless base station AP MLD1 and the second wireless base station AP MLD2 (step S12). The TID is determined according to the type of transmission data to be transferred. Therefore, if the type of transmission data is the same, the TID value is also the same. On the other hand, the sequence number is incremented by 1 for each transmission data to be transferred. The number of bits of the sequence number is, for example, 12 bits, and the sequence number takes on a value between 0 and 4095. When the sequence number reaches 4095, it returns to 0 and is assigned to the next transmission data. Furthermore, a sequence number is assigned for each destination device and each TID. In other words, if either the destination device or the TID is different, a sequence number that is incremented separately from the sequence numbers for that destination device and that TID is assigned. Details will be described later, but when the wireless base station AP MLD generates a MAC frame based on transmission data transferred from the multi-AP controller 21, the TID and sequence number are set in the QoS Control field (the TID field contained in it) and the Sequence Control field in the MAC Header, respectively.

[0098] After the process of step S12, the multi-AP controller 21 generates a management number for managing the transmission data (MSDU (MAC Service Data Unit)) to be transferred to the first wireless base station AP MLD1 and the second wireless base station AP MLD2 (step S13). The MSDU includes, for example, an IP packet. The management number is a number that is incremented for each transmission data (MSDU) transferred to the radio base station AP MLD. When transmission data that has at least one value of the destination device, TID, and sequence number different from other transmission data is transferred to the radio base station AP MLD, the management number is incremented by 1.

[0099] The number of bits of the management number is, for example, 32 bits. However, the management number assigned to transmission data already transmitted from the wireless base station AP MLD to the destination device (wireless terminal STA MLD) has already fulfilled its role and is reused as the management number for new data. In other words, the management number only needs to be unique within a certain period of time, and the number of bits of the management number may be a number other than the above-mentioned 32 bits. For example, the number of bits of the management number may be determined depending on the number of wireless terminals managed by the multi-AP controller 21, the transfer rate of data transmitted within a certain period of time, etc.

[0100] After processing step S13, the multi-AP controller 21 generates an Ethernet frame (transfer frame, transfer packet) including the TID and sequence number generated in the processing of step S12, the management number generated in the processing of step S13, and the transmission data to be transferred (step S14).

[0101] Here, with reference to FIG. 13, an example of setting the TID, sequence number, and management number included in the forwarded frame generated by the processing of step S14 described above will be described. Here, for example, attention is paid to forwarded frames with forwarding order numbers "1" and "2". As shown in FIG. 13, a forwarded frame with forwarding order number "1" and destination device "first wireless terminal STA MLD1" contains TID "0", sequence number "0", and management number "1" which are associated with each other. Also, a forwarded frame with forwarding order number "2" and destination device "first wireless terminal STA MLD2" contains TID "0", sequence number "0", and management number "1" which are associated with each other. The transfer frame of "MLD1" contains a TID of "0", a sequence number of "1", and a management number of "1", which are associated with each other. Because the TIDs contained in these two transfer frames both indicate "0", it can be seen that the type of transmission data to be transferred contained in the two transfer frames is the same. On the other hand, because the sequence numbers contained in these two transfer frames each indicate different values, it can be seen that the transmission data to be transferred contained in the two transfer frames is different. As mentioned above, the management number is a value that is incremented by 1 if any one of the destination device, TID, and sequence number is different, so the management numbers contained in these two transfer frames indicate different values. Note that although the transfer frames with transfer order numbers "1" and "2" have been used as examples here, the same explanation can be given for the transfer frames with transfer order numbers "3" to "10".

[0102] Furthermore, the frame format of the transfer frame (Ethernet frame) generated by the processing of step S14 described above will be described with reference to Fig. 14. Fig. 14 is a diagram showing the frame format of an Ethernet frame. As shown in Fig. 14, an Ethernet frame is made up of a Destination Address field, a Source Address field, a Multi-AP Tag field, an Ethernet Type Number field, a Data field, and an FCS field.

[0103] The Destination Address field is set with the MAC address of the destination device. The Source Address field is set with the MAC address of the source device. The Multi-AP Tag field is set with accompanying information when transmission data is transferred from the multi-AP controller 21 to a controller AP CT included in the wireless base station AP MLD. The Ethernet Type Number field is set with an identifier of an upper layer protocol stored in the following Data field. The Data field stores transmission data such as an IP packet, for example. The FCS field is set with a CRC calculated based on the Destination Address field to the Data field.

[0104] As shown in Fig. 14, the Multi-AP Tag field includes a Tag ID field, a TID field, a MAC Sequence Number field, and a Multi-AP Management Number field. An identifier indicating that it is a Multi-AP Tag is set in the Tag ID field. The TID field has a length of, for example, 4 bits, and a TID is set therein. The MAC Sequence Number field has a length of, for example, 12 bits, and a sequence number is set therein. The Multi-AP Management Number field has a length of, for example, 32 bits, and a management number is set therein.

[0105] Returning to the description of Fig. 12, after the process of step S14, the wired I / F unit (not shown) included in the control device 20 transfers the Ethernet frame (forwarded frame) generated by the multi-AP controller 21 to the first wireless base station AP MLD1 and the second wireless base station AP MLD2 (step S15), thereby ending the series of processes here.

[0106] In this embodiment, the first radio base station AP MLD1 and the second radio base station AP Since it is assumed that the first wireless base station AP MLD1 and the second wireless base station AP MLD2 cooperate to perform highly reliable communication with the first wireless terminal STA MLD1, an Ethernet frame containing the same transmission data is transferred to the first wireless base station AP MLD1 and the second wireless base station AP MLD2. In this case, by setting a broadcast address in the Destination Address field constituting the Ethernet frame, the frame may be transferred in one go to both the first wireless base station AP MLD1 and the second wireless base station AP MLD2. Alternatively, the MAC address of the wired I / F unit of the first wireless base station AP MLD1 and the MAC address of the wired I / F unit of the second wireless base station AP MLD2 may be set in the Destination Address field constituting the Ethernet frame, and the frame may be transferred in two separate goes. Note that the Destination The Address field may contain a multicast address or a unicast address.

[0107] Next, a processing procedure in which the first wireless base station AP MLD1 transmits transmission data to the first wireless terminal STA MLD1 will be described with reference to the flowchart of FIG.

[0108] First, when the first wireless base station AP MLD1 receives (accepts) an Ethernet frame (transferred frame) transferred from the control device 20, it extracts the TID, sequence number, and management number from the Multi-AP Tag field constituting the Ethernet frame (step S21). The extracted TID, sequence number, and management number are temporarily stored in memory in association with the transmission data stored in the subsequent Data field constituting the received Ethernet frame.

[0109] Next, the controller AP CT1 of the first wireless base station AP MLD1 sets the TID and sequence number extracted by the processing of step S21 in the QoS Control field (the TID field included in the QoS Control field) and the Sequence Control field in the MAC Header, respectively, and sets the transmission data stored in the Data field in the Frame Body field, thereby generating a QoS data frame, which is a MAC frame (step S22).

[0110] In this embodiment, it is assumed that the first station STA1-1 is connected to the first access point AP1-1 included in the first wireless base station AP MLD1, and the second station STA1-2 is connected to the second access point AP2-2 included in the second wireless base station AP MLD2.Therefore, the Address1 field of the QoS data frame generated by the first wireless base station AP MLD1 is set to the MAC address of the first station STA1-1 included in the first wireless terminal STA MLD1, the Address2 field is set to the MAC address of the first access point AP1-1 included in the first wireless base station AP MLD1, and the Address3 field is set to the MAC address of the first access point AP1-1, just like the Address2 field. In addition, by processing similar to the processing of steps S21 and S22 described above, the Address1 field of the QoS data frame generated by the second wireless base station AP MLD2 is set to the MAC address of the second station STA1-2 included in the first wireless terminal STA MLD1, the Address2 field is set to the MAC address of the second access point AP2-2 included in the second wireless base station AP MLD2, and the Address3 field is set to the MAC address of the second access point AP2-2, just like the Address2 field.

[0111] After the processing of step S22, the first radio base station AP MLD1 checks whether or not it has received a notification from the cooperating second radio base station AP MLD2 that the transmission of the QoS data frame including the transmission data assigned with the same management number as the management number of the transmission data stored in the Data field of the QoS data frame generated by the processing of step S22 has been successful (step S23).

[0112] If, as a result of the processing of step S23, it is confirmed that a notification has been received indicating that the transmission of the QoS data frame containing the transmission data assigned the same management number has been successful (Yes in step S23), the controller AP CT1 of the first wireless base station AP MLD1 discards the QoS data frame generated by the processing of step S22 (step S24) and transmits a notification indicating that the QoS data frame has been discarded to at least the multi-AP controller 21 included in the control device 20 (step S25).

[0113] On the other hand, if it is confirmed as a result of the processing in step S23 that a notification has not been received indicating that the QoS data frame containing the transmission data with the same management number has been successfully transmitted (No in step S23), the first access point AP1-1 of the first wireless base station AP MLD1 transmits the QoS data frame containing the transmission data to the first station STA1-1 of the first wireless terminal STA MLD1 (step S26).

[0114] Thereafter, the first access point AP1-1 of the first wireless base station AP MLD1 checks whether a response frame (such as an Ack frame or a BA frame) has been received from the first station STA1-1 of the first wireless terminal STA MLD1 (step S27). If it is confirmed as a result of the processing in step S27 that a response frame has been received (Yes in step S27), the controller AP CT1 of the first wireless base station AP MLD1 generates a UDP packet including information indicating that the QoS data frame has been successfully transmitted and the management number of the transmission data stored in the QoS data frame. Thereafter, the controller AP CT1 generates an IP packet including the generated UDP packet, and transmits the Ethernet frame, in which an Ethernet header has been added to the IP packet, to at least one of the multi-AP controller 21 of the control device 20 and the second wireless base station AP MLD2 (step S28).

[0115] The destination MAC address in the Ethernet header is set to, for example, a broadcast address (e.g., ff.ff.ff.ff.ff.ff), and the source MAC address in the Ethernet header is set to, for example, the MAC address of the wired I / F unit in the first wireless base station AP MLD1. The source IP address in the IP header is set to, for example, the IP address of the first wireless base station AP MLD1, and the destination IP address in the IP header is set to, for example, a broadcast address (e.g., 255.255.255.255). The source port number in the UDP header is set to an appropriate number (e.g., 49155) that does not overlap with other communications, and the destination port number in the UDP header is set to a number (e.g., 20400) that has been negotiated in advance with the second wireless base station AP MLD2. The transmission result in the UDP data is indicated by a value of "0" indicating successful transmission, a value of "1" indicating unsuccessful transmission, or a value of "2" indicating discard. According to this, Ethernet frames and IP packets are transmitted as broadcast frames from the wired I / F unit in the first wireless base station AP MLD1, allowing them to be transmitted to both the multi-AP controller 21 and the second wireless base station AP MLD2. When the second wireless base station AP MLD2 receives the above-mentioned UDP packet, it checks the destination port number. If the destination port number is a pre-negotiated number, it recognizes the UDP packet as a notification of the transmission result and can extract the management number and transmission result from the data field in the UDP packet. As a result, if the transmission result is "success," it searches for whether a QoS data frame containing transmission data assigned the same management number as the extracted management number exists as a frame to be transmitted. If the QoS data frame exists as a frame to be transmitted, it can stop transmission of the frame and discard it.

[0116] On the other hand, as a result of the processing in step S27, if a certain time has passed and a response timeout occurs without being able to confirm that the response frame has been received (No in step S27), the first access point AP1-1 of the first wireless base station AP MLD1 checks whether the number of times the QoS data frame has been transmitted has reached the retransmission limit (step S29).If as a result of the processing in step S29 it is confirmed that the number of times the QoS data frame has been transmitted has not reached the retransmission limit (No in step S29), the processing in step S23 described above is executed again.

[0117] On the other hand, as a result of the process in step S29, if it is confirmed that the number of times the QoS data frame has been transmitted has reached the retransmission limit (Yes in step S29), the first wireless base station AP The first access point AP1-1 of MLD1 gives up on retransmitting the QoS data frame generated by the process of step S22, and discards the QoS data frame (step S30).

[0118] Thereafter, the controller AP CT1 of the first wireless base station AP MLD1 sends a notification to at least the multi-AP controller 21 of the control device 20 that the transmission of the transmission data stored in the QoS data frame has failed (step S31), and ends this series of processes.

[0119] According to the first embodiment described above, the wireless base station AP MLD can identify whether other wireless base stations AP MLDs that perform Multi-Link operation in cooperation with the wireless base station AP MLD have succeeded in transmitting the transmission data based on the management number assigned to the transmission data transferred from the control device 20. For example, when the wireless base station AP MLD is connected to a plurality of wireless terminals STA When the MLDs are wirelessly connected and the same frame is transmitted to one wireless terminal STA MLD via multiple wireless base stations AP MLD, the wireless base station AP MLD can identify whether the transmitted data is the same as data that has already been successfully transmitted from another wireless base station AP MLD, and can discard the transmitted data. This suppresses unnecessary frame transmissions while promoting new frame transmissions, thereby enabling efficient communication using multi-link transmission technology.

[0120] A modification of the first embodiment will be described below. [Modification of the first embodiment] Fig. 16 is a diagram showing an example of setting values ​​set in each field constituting a Multi-Link Element included in a beacon frame, and Fig. 17 is a diagram showing an example of setting values ​​set in each field constituting a Reduced Neighbor Report Element included in a beacon frame. Note that Fig. 16 and Fig. 17 show only the main parameters of each Element.

[0121] In this modification, a case will be described in which the same setting value for the number is included in all beacon frames. 16 and 17, for example, the setting value of No. "1" shown in Fig. 16 and 17, the value "0" indicating a Basic Type is set in the Type field, while the value "4" indicating a Multi-AP variant Multi-Link element is set in the Subelement ID field. In other words, the setting value of No. "1" corresponds to a setting example in which the first radio base station AP MLD1 can perform Multi-Link operation by itself, and the first radio base station AP MLD1 can also perform Multi-Link operation in cooperation with the second radio base station AP MLD2.

[0122] Here, a case will be described in which the first wireless terminal STA MLD1 receives a beacon frame including an Element with a setting value of No. "1" shown in FIGS. 16 and 17 from the first wireless base station AP MLD1. First, a case will be described in which the first wireless terminal STA MLD1 selects to perform Multi-Link operation with the first wireless base station AP MLD1 alone.

[0123] When the first wireless terminal STA MLD1 receives a beacon frame including an Element with a setting value of No. "1," it selects a wireless link in which the Type field is set to the value "0" indicating a Basic Type and the Subelement ID field is set to the value "3" indicating a Basic variant Multi-Link element. Here, for example, it is selected to connect the first station STA1-1 to the first access point AP1-1 included in the first wireless base station AP MLD1, and to connect the second station STA1-2 to the second access point AP1-2 included in the first wireless base station AP MLD1.

[0124] When connecting to the first access point AP1-1, the frequency channel used for wireless communication is set to the frequency channel used when the first station STA1-1 received a beacon frame from the first access point AP1-1. In other words, it is assumed here that the first station STA1-1 has already been set to a frequency channel that can communicate with the first access point AP1-1. On the other hand, when connecting to the second access point AP1-2, the channel number is extracted from the Channel Number field corresponding to the identifier "1" set in the Link ID field of the Reduced Neighbor Report element, and the frequency channel number "36" is set. This channel number is used to set the center frequency of the second station STA1-2 (its radio unit) to 5.18 GHz, and an attempt is made to connect to the second access point AP1-2. Note that the MAC address of the first wireless base station AP MLD1 set in the MLD MAC Address field in the Multi-Link Element set to "1" in FIG. 16 is selected as the UMAC layer.

[0125] Next, a case will be described in which the first wireless terminal STA MLD1 selects to perform a Multi-AP Multi-Link operation in which it is wirelessly connected to both the first wireless base station AP MLD1 and the second wireless base station AP MLD2.

[0126] When the first wireless terminal STA MLD1 receives a beacon frame including an Element with a setting value of No. "1", it first sets the value "0" in the Type field, indicating that it is a Basic Type, as one of the wireless links, and A wireless link having a value of "3" set in the ID field, which indicates that the wireless link is a Basic variant Multi-Link element, is selected. In this example, for example, the first station STA1-1 is selected to be connected to the first access point AP1-1 included in the first wireless base station AP MLD1.

[0127] Next, the first wireless terminal STA MLD1 selects another wireless link, a wireless link having a value "4" set in the Subelement ID field, which indicates that the wireless link is a Multi-AP variant Multi-Link element. Here, for example, the first wireless terminal STA MLD1 selects to connect the second station STA1-2 to the second access point AP2-2 included in the second wireless base station AP MLD2.

[0128] When connecting to the first access point AP1-1, the frequency channel used for wireless communication is set to the frequency channel used when the first station STA1-1 received the beacon frame from the first access point AP1-1, as described above. On the other hand, when connecting to the second access point AP2-2, the channel number is extracted from the Channel Number field corresponding to the identifier "3" set in the Link ID field of the Reduced Neighbor Report element, and the frequency channel number "44" is set. This channel number is used to set the center frequency of the second station STA1-2 (its radio unit) to 5.22 GHz, and an attempt is made to connect to the second access point AP2-2. Note that the MAC address of the multi-AP controller 21 set in the MLD ID field in the Reduced Neighbor Report element with the setting value "1" shown in FIG. 17 is selected as the UMAC layer.

[0129] 16 and 17, the value "4" is set in the Type field indicating that it is a MAP Type, and the value "4" is also set in the Subelement ID field indicating that it is a Multi-AP variant Multi-Link element. In other words, the setting value of No. "2" is set to "4" across the first wireless base station AP MLD1 and the second wireless base station AP MLD2. This corresponds to a setting example in which multi-link operation is possible. In this setting example, the UMAC layer unit includes a first wireless base station AP MLD1 and a second wireless base station AP Whichever access point included in MLD2 is selected, the multi-AP controller 21 is selected.

[0130] In the case of the setting example of No. "2", the first access point AP1-1 and the second access point AP1-2 included in the first wireless base station AP MLD1, or the second wireless base station AP The first wireless terminal STA cannot determine from the various ID information alone whether the first access point AP2-1 and the second access point AP2-2 included in the MLD2 are mounted in the same housing. MLD1 cannot be recognized.

[0131] In contrast to this, in the setting example of No. "3" shown in Fig. 16 and Fig. 17, the setting is made such that it is possible to distinguish whether the first access point AP1-1 and the second access point AP1-2 included in the first wireless base station AP MLD1, or the first access point AP2-1 and the second access point AP2-2 included in the second wireless base station AP MLD2, are implemented in the same housing. Specifically, the Reduced Neighbor Report The setting value of the MLD ID field of the element is the same for access points in the same wireless base station AP MLD. Also, a wireless base station AP MLD with a value of "0" in the MLD ID field indicates that it is the same wireless base station AP MLD (i.e., the first wireless base station AP MLD1) as the access point (here, the first access point AP1-1) set first in the Link Info field in the Multi-Link Element. The MLD ID fields of the first access point AP2-1 and the second access point AP2-2 included in the second wireless base station AP MLD2 are both set to "1". According to this, when the first wireless terminal STA MLD1 wants to connect to an access point AP included in a different wireless base station AP MLD, it can refer to the MLD ID field and select an access point AP of a different wireless base station AP MLD.

[0132] [Second embodiment] Next, a second embodiment will be described. In the second embodiment, an efficient communication resumption method will be described when communication of one of multiple wireless links established between a wireless base station AP MLD and a wireless terminal STA MLD is interrupted. Note that in this embodiment, it is assumed that the wireless base station AP MLD performs a multi-link operation with the wireless terminal STA MLD using a Block Ack mechanism.

[0133] As described above, if communication on one of multiple wireless links established between the wireless base station AP MLD and the wireless terminal STA MLD is interrupted for a while while communication continues on the other wireless links, a discrepancy occurs between the data transmitted on the interrupted wireless link and the data transmitted on the continued wireless link (the continued wireless link may transmit newer data). As a result, when communication resumes on the interrupted wireless link, the wireless terminal STA MLD may be unable to return an appropriate response frame even though it can receive data transmitted through the interrupted wireless link. This embodiment describes a method for detecting such a situation and transmitting a BAR frame to the wireless terminal STA MLD, thereby synchronizing the reception histories of the wireless terminal STA MLD on each wireless link and enabling the wireless terminal STA MLD to return an appropriate response frame.

[0134] A basic response method is to return an Ack frame to the source device (transmitting device) in response to the reception of a single data frame, informing the source device (transmitting device) that the data frame was successfully received. However, with this method, if multiple data frames are received, an Ack frame must be returned for each of the received data frames. This means that the time required to transmit the PHY header and the Ack frame when transmitting a data frame becomes overhead, and the throughput at the MAC layer saturates relative to the improvement in the PHY rate. To reduce the time required to transmit the PHY header when transmitting a data frame, there is A-MPDU (Aggregated MPDU), which concatenates multiple data frames into a single PHY frame (PSDU: PHY service data unit).

[0135] FIG. 18 is a diagram showing the frame format of an A-MPDU frame. As shown in FIG. 18, an A-MPDU frame is formed by concatenating N subframes (where N is a positive integer). Each subframe is composed of a delimiter field, which is boundary information for detecting subframe boundaries, and a MAC frame. The delimiter field is 4 bytes long and includes a length field indicating the length of the subsequent MAC frame, a CRC for detecting errors in the length field, and a delimiter signature field indicating that this field is a delimiter field. The frame format of the MAC frame following the delimiter field is the same as the frame format shown in FIG. 2, so a detailed description thereof will be omitted here. Note that the pad field following the MAC frame is a field added to make the length of the subframe a multiple of 4 bytes if the length of the subframe is not a multiple of 4 bytes, and is added in the range of 1 to 3 bytes. The data frame is an MPDU, and the frame body field that constitutes the MPDU contains an MSDU. The MSDU includes UDP packets, TCP packets, and the like that are transferred from layers higher than the MAC layer.

[0136] As shown in Figure 18, an A-MPDU frame is a frame in which multiple MAC frames are concatenated, so a BlockAck frame is used instead of an Ack frame as a response frame to the reception of an A-MPDU frame. A BA frame can notify delivery confirmation information for multiple data frames in a single MAC frame.

[0137] Fig. 19 is a diagram showing the frame format of a BA frame. As shown in Fig. 19, the BA frame is composed of a Frame Control field, a Duration field, an Address1 field, an Address2 field, a BA Control field, a BA Information field, and an FCS field. Note that the roles of the fields other than the BA Control field and the BA Information field are the same as those of the MAC frame explained in conjunction with Fig. 2, so detailed explanations thereof will be omitted here.

[0138] The Type field and Subtype field of the Frame Control field are assigned a bit pattern (for example, Type=2'b01, Subtype=4'b1001, etc.) indicating that the frame is a BA frame.

[0139] Information indicating the destination of the BA frame is set in the Address1 field. For example, when a first station STA1-1 included in a first wireless terminal STA MLD1 transmits a BA frame to a first access point AP1-1 included in a first wireless base station AP MLD1, the MAC address of the first access point AP1-1 is set in the Address1 field.

[0140] Information indicating the source of the BA frame is set in the Address2 field. For example, when a first station STA1-1 included in the first wireless terminal STA MLD1 transmits a BA frame to a first access point AP1-1 included in the first wireless base station AP MLD1, the MAC address of the first station STA1-1 is set in the Address2 field.

[0141] The BA Control field includes at least a Compressed Bitmap field and a TID_INFO field. Note that the Reserved field shown in Figure 19 indicates unused bits, and is set to 0. The unused bits in the Reserved field can be used for any purpose.

[0142] The Compressed Bitmap field is a 1-bit field, and indicates that the following Block Ack Bitmap field uses a field with a reduced length.

[0143] The TID_INFO field is a 4-bit field that indicates the TID of the data frame of the following acknowledgement information (Block Ack Bitmap information). The BA frame contains acknowledgement information for the data frame that has the same TID as the TID set in the TID_INFO field.

[0144] The BA Information field includes a Block Ack Starting Sequence Control field and a Block Ack Bitmap field, as shown in Figure 19. Furthermore, the Block Ack Starting Sequence Control field includes a Fragment Number field and a Starting Sequence Number (SSN) field.

[0145] The Fragment Number field contains information indicating the field length of the Block Ack Bitmap field and information indicating whether or not the Block Ack Bitmap field contains acknowledgement information for the fragmented data frame. The SSN field indicates the sequence number of the frame corresponding to the first bit of the following Block Ack Bitmap field.

[0146] The Block Ack Bitmap field is a field that indicates reception history information (i.e., information indicating whether the data frame was received normally or not) of data frames that were transmitted by a wireless base station (or an access point included in the data frame) and received by a wireless terminal (or a station included in the data frame) in a bitmap format with one bit per data frame. The basic length of the Block Ack Bitmap field is 8 bytes, but it is possible to select lengths of 32 bytes, 64 bytes, or 128 bytes in addition to 8 bytes by setting the value of the Fragment Number field.

[0147] If the fragmented data frame does not contain acknowledgement information, The first bit of the Ack Bitmap field indicates acknowledgement information for the data frame with the sequence number indicated by the SSN field. In the Block Ack Bitmap field, each shift of one bit from the top indicates acknowledgement information for a frame whose sequence number increases by one. In other words, the second bit from the top indicates acknowledgement information for a data frame with a sequence number indicated by (SSN+1). For example, if the value of the SSN field is 100, the Block Ack Bitmap field contains acknowledgement information for data frames with sequence numbers from 100 to 163.

[0148] 20 is a diagram showing the frame format of a BAR frame. As shown in FIG. 20, the BAR frame includes a Frame Control field, a Duration field, an Address 1 field, an Address 2 field, and a BAR It consists of a Control field, a BAR Information field, and an FCS field. The BAR is a frame that requests the destination wireless device to return a BA frame. It also serves to update the BA Window information (WinStart, etc.) held by that wireless device. Note that the roles of the fields other than the BAR Control field and the BAR Information field are the same as those of the MAC frame explained in conjunction with Figure 2, so a detailed explanation will be omitted here.

[0149] The Type field and Subtype field of the Frame Control field are assigned a bit pattern (for example, Type=2'b01, Subtype=4'b1000, etc.) that indicates a BAR frame.

[0150] The Address1 field is set with information indicating the destination of the BAR frame. For example, when a first access point AP1-1 included in a first wireless base station AP MLD1 transmits a BAR frame to a first station STA1-1 included in a first wireless terminal STA MLD1, the Address1 field is set with the MAC address of the first station STA1-1.

[0151] The Address2 field is set with information indicating the source of the BAR frame. For example, when a first access point AP1-1 included in the first wireless base station AP MLD1 transmits a BAR frame to a first station STA1-1 included in the first wireless terminal STA MLD1, the MAC address of the first access point AP1-1 is set in the Address2 field.

[0152] The BAR Control field includes at least a Compressed Bitmap field and a TID_INFO field. Note that the Reserved field shown in Figure 20 indicates unused bits, and is set to 0. The unused bits in the Reserved field can be used for any purpose.

[0153] The Compressed Bitmap field is a 1-bit long field, and indicates that a BA frame using a field with a shortened length of the Block Ack Bitmap field is requested from the destination device (for example, the first station STA1-1).

[0154] The TID_INFO field is a 4-bit field that indicates the TID of the BA frame's acknowledgement information (Block Ack Bitmap information). The first access point AP1-1 requests the first station STA1-1 to send a BA frame including acknowledgement information with the same TID value as the TID set in the TID_INFO field.

[0155] The BAR Information field consists of the Block Ack Starting Sequence Control field and the Block The Block Ack Starting Sequence Control field includes a Fragment Number field and a Starting Sequence Number (SSN) field.

[0156] The Fragment Number field is set to 0, and is treated as reserved in the BAR frame. The SSN field is set to the sequence number of the frame corresponding to the first bit of the Block Ack Bitmap field of the BA frame requested by the first access point AP1-1.

[0157] Next, a method for controlling the Block Ack (BA) window will be described with reference to Fig. 21. The BA window indicates the range of current acknowledgement information recorded by stations included in a wireless terminal. In other words, the range of the BA window corresponds to the range in which acknowledgement information is returned in the BA Bitmap field.

[0158] As described above, the sequence number of a data frame has a length of 12 bits, and integer values ​​ranging from 0 to 4095 are assigned to the data frame to be transmitted. Meanwhile, the length of the BA Bitmap field is shorter than the sequence number space (SN Space (Sequence Number Space)). Here, it is assumed that the length of the BA Bitmap field is 8 bytes (64 bits), which is the basic length. If the length of the BA Bitmap field is 64 bits, the size of the BA Window is also 64 bits. Here, the sequence number space refers to the range of values ​​that the sequence number included in the MAC frame, such as the data frame to be transmitted, can take. In this embodiment, the sequence number of the data frame is set in the Sequence Control field and has a length of 12 bits. The sequence number may have a length other than 12 bits; for example, if it is 13 bits, the sequence number space will have a wider range, from 0 to 8191. Furthermore, the sequence number may be set in another field within the MAC frame, or in a newly added field.

[0159] In the following description, the size of the BA window is represented as WinSize, the end number of the BA window is represented as WinEnd, and the start number of the BA window is represented as WinStart.

[0160] As shown in FIG. 21, when a data frame with sequence number SN1 is received by (a station included in) the wireless terminal STA MLD, WinEnd1 becomes the sequence number SN1. Also, WinStart1 is calculated by "SN1-(WinSize-1)". For example, if the sequence number SN1 is 163, WinEnd1 is 163, and if WinSize is 64 bits as mentioned above, WinStart1 becomes 100 (=163-(64-1)).

[0161] The BA window is controlled differently depending on which of Range1 to Range3 shown in FIG. 21 the sequence number SN2 of the data frame received after the data frame with sequence number SN1 falls within.

[0162] First, if the sequence number SN2 is included in Range1 (that is, WinStart1≦SN2≦WinEnd1), the wireless terminal STA MLD leaves BA Window1 as it is, sets the bit corresponding to the sequence number SN2 to 1, and returns a BA frame in which the bitmap of the range of BA Window1 is set in the BA Bitmap field to the wireless base station AP MLD. In this case, the value of the SSN field is set to WinStart1.

[0163] Next, the sequence number SN2 is included in Range2 (i.e., WinEnd1 <SN2<WinStart1+2 11), the wireless terminal STA MLD sets 1 to the bit corresponding to the sequence number SN2, sets the value of WinEnd to the sequence number SN2, and sets the value of WinStart to the value calculated by "SN2-(WinSize-1)", thereby shifting the BA Window. As a result, as shown in FIG. 21, the BA Window shifts from BA Window1 to BA Window2. Thereafter, the wireless terminal STA MLD returns a BA frame in which the bitmap of the range of BA Window2 is set in the BA Bitmap field to the wireless base station AP MLD. In this case, the value of the SSN field is set to WinStart2.

[0164] If the sequence number of the received data frame is within Range 1 or Range 2, the destination device (wireless terminal) recognizes the data frame as a new frame and recognizes that it needs to return a response frame containing delivery confirmation information for the data frame to the source device (wireless base station).

[0165] Also, sequence number SN2 is included in Range3 (i.e., WinStart1+2 11 If SN2≦WinStart1, the wireless terminal STA MLD maintains BA Window1 as it is and recognizes the data frame with sequence number SN2 set as an old frame. In this case, the destination device (wireless terminal) returns a BA frame to the source device (wireless base station), and the BA Bitmap field of the BA frame is set to a bitmap within BA Window1, and the SSN field is set to WinStart1.

[0166] If the sequence number of the received data frame is included in Range3, the destination device (wireless terminal) recognizes that the data frame is an old frame, and recognizes that it is not necessary to return a response frame including the acknowledgement information of the data frame, and returns a response frame that does not include the acknowledgement information. In this embodiment, the boundary between Range2 and Range3 is defined as WinStart1+2. 11 However, other values ​​may be used. For example, to widen the range of Range2, WinStart1+3000 may be used.

[0167] Here, a processing procedure for updating the reception history of the wireless terminal STA MLD will be described with reference to Fig. 22. Here, as shown in Fig. 23, a situation is assumed in which a first access point AP1-1 included in the first wireless base station AP MLD1 is wirelessly connected to a first station STA1-1 included in the first wireless terminal STA MLD1, and a second access point AP1-2 included in the first wireless base station AP MLD1 is wirelessly connected to a second station STA1-2 included in the first wireless terminal STA MLD1 (that is, the first wireless base station AP This assumes a situation where, in a situation where Multi-Link operation was being performed solely by MLD1, the wireless link between the first access point AP1-1 and the first station STA1-1 was interrupted for a while, while communication continued via the wireless link between the second access point AP1-2 and the second station STA1-2, or where communication continued via the wireless link between the second access point AP1-2 and the second station STA1-2 because the communication environment via the wireless link between the second access point AP1-2 and the second station STA1-2 was better than that via the wireless link between the first access point AP1-1 and the first station STA1-1 (for example, faster communication speed, less communication traffic from other wireless devices, etc.).

[0168] First, the first access point AP1-1 included in the first radio base station AP MLD1 checks the sequence number of a new data frame transferred from the controller AP CT1 (hereinafter referred to as SN_new) (step S41).

[0169] Subsequently, based on the latest sequence number among the sequence numbers of the data frames successfully transmitted to the first station STA1-1 immediately before the wireless link is blocked (hereinafter referred to as SN_old) and the above-mentioned SN_new, the first access point AP1-1 calculates the difference between these two sequence numbers (hereinafter referred to as SN_diff) (step S42). In the process of step S42, the calculation method of SN_diff is different when SN_new is greater than or equal to SN_old and when SN_new is less than SN_old.

[0170] Specifically, when SN_new is greater than or equal to SN_old, SN_diff is calculated as "SN_new - SN_old". On the other hand, when SN_new is less than SN_old, SN_diff is calculated as "4095 - SN_old + SN_new".

[0171] After the process of step S42, the first access point AP1-1 determines whether the SN_diff calculated by the process of step S42 is greater than or equal to a preset threshold value (hereinafter referred to as SN_th) (step S43). SN_th is set to, for example, 1900, but it may be set to other values. However, if SN_th is too small, the transmission frequency of the BAR frame will increase. Conversely, if SN_th is too large, the BAR frame may not be transmitted even when the BAR frame needs to be transmitted. Therefore, SN_th is preferably set to a value within the range greater than WinSize and less than approximately half of the sequence number space (that is, WinSize < SN_th ≤ SN Space / 2).

[0172] Before starting the BA mechanism with the first station STA1-1 included in the first wireless terminal STA MLD1, the first access point AP1-1 performs a negotiation sequence to exchange specified frames. Through this negotiation sequence, the first access point AP1-1 can determine WinSize, which is the size of the BA Window supported by the first station STA1-1, and can set the above-mentioned SN_th.

[0173] As a result of the process in step S43, if it is determined that SN_diff is less than SN_th (No in step S43), the first access point AP1-1 The new data frame transferred from CT1 is transmitted to the first station STA1-1 (step S44), and the process proceeds to step S47, which will be described later.

[0174] On the other hand, if it is determined as a result of the processing in step S43 that SN_diff is equal to or greater than SN_th (Yes in step S43), the first access point AP1-1 sets SN_new in the SSN field of the BAR frame (step S45). If there are multiple new data frames to be transmitted to the first station STA1-1, the smallest value among the sequence numbers of these multiple data frames is selected as SN_new. For example, if the sequence numbers of the data frames to be transmitted are 1000 to 1005, 1000 is selected as SN_new. The value set in the SSN field does not necessarily have to be SN_new, and may be any value that requests the first station STA1-1 to include delivery confirmation information for the data frame in a BA frame when it receives the data frame. However, although it is acceptable to set a value slightly smaller than SN_new (for example, a value smaller by WinSize), it is preferable to avoid setting a value larger than SN_new.

[0175] After the process of step S45, the first access point AP1-1 transmits a BAR frame in which SN_new is set in the SSN field to the first station STA1-1 (step S46). Next, the first access point AP1-1 determines whether SN_new is a newer number than SN_old (step S47). If it is determined in step S47 that SN_new is not a newer number than SN_old, that is, that SN_new is an older number (No in step S47), the first access point AP1-1 ends this series of processes. On the other hand, if it is determined as a result of the processing in step S47 that SN_new is a newer number than SN_old (Yes in step S47), the first access point AP1-1 assigns SN_new to SN_old (i.e., updates SN_old to SN_new) (step S48) and terminates this series of processes.

[0176] When the first station STA1-1 included in the first wireless terminal STA MLD1 receives a BAR frame transmitted from the first access point AP1-1, it updates WinStart, which is the start number of the BA Window, to the sequence number (i.e., SN_new) set in the SSN field of the BAR frame. This allows the range of the BA Window held by the first station STA1-1 to be updated according to the sequence number set in the SSN field of the BAR frame, so that when the first station STA1-1 subsequently receives a new data frame transmitted from the first access point AP1-1, it can return a BA frame including appropriate acknowledgement information to the first access point AP1-1.

[0177] According to the second embodiment described above, when communication on one of a plurality of wireless links established between the wireless base station AP MLD and the wireless terminal STA MLD is interrupted for a while (this includes not only a state in which communication is not possible at all, but also a case in which it takes a long time to start transmitting a frame due to a busy state, or a case in which the probability of receiving a response frame for a transmitted frame is lower than expected, etc.), while communication on the other wireless links continues, and the wireless link whose communication was interrupted thereafter recovers (this includes a case in which the busy state changes to an idle state, or a case in which the probability of receiving a response frame for a transmitted frame becomes higher than expected, etc.), the access point corresponding to the restored wireless link compares the sequence number SN_new of the new data frame with the sequence number SN_old of the data frame successfully transmitted immediately before the communication was interrupted, and if the difference SN_diff is equal to or greater than a threshold SN_th, transmits a BAR frame to update the range of the BA Window held by the corresponding station. Therefore, when the corresponding station receives a new data frame subsequently transmitted from the corresponding access point, it is able to return a BA frame containing appropriate delivery confirmation information to the access point, thereby efficiently resuming transmission of the new data frame.

[0178] A modification of the second embodiment will be described below. [First Modification of Second Embodiment] Each time the first station STA1-1 receives a new data frame from the first access point AP1-1, the first station STA1-1 may reset to 0 the frame reception history information of the MAC layer immediately before receiving the data frame or before determining whether the data frame was received successfully. Specifically, when the PHY layer transfers a PSDU frame including a data frame to the MAC layer, if the MAC layer receives (accepts) a reception request notification from the PHY layer, the MAC layer resets to 0 the frame reception history information that it has retained until immediately before receiving the PSDU frame, and then updates the information to reflect the reception status of the PSDU frame. Note that resetting the frame reception history information to 0 means that the history information is not retained (no temporary record) or that the status is the same as immediately after the BA mechanism is established. The frame reception history information may be reset when a data frame is received, but not when a BAR frame is received.

[0179] Furthermore, when the first station STA1-1 receives a new data frame transmitted from the first access point AP1-1 and has a sequence number whose difference from the sequence number set in the SSN field of the bitmap held by the first station STA1-1 is equal to or greater than the above-mentioned SN_th X times (where X is an integer equal to or greater than 0), the MAC layer unit may reset the held frame reception history information to 0 (for example, when the BA (It may be in the state immediately after the mechanism is established.)

[0180] Furthermore, if the difference between the sequence number of a new data frame transmitted from the first access point AP1-1 and the sequence number set in the SSN field of the bitmap held by the first station STA1-1 is equal to or greater than the above-mentioned SN_th, the first station STA1-1 inquires about the reception history status of another wireless link (for example, the second station STA1-2) included in the first wireless terminal STA MLD1 and checks the sequence number set in the SSN field of the bitmap held by the second station STA1-2. If the difference between the sequence number set in the SSN field of the bitmap held by the first station STA1-1 and the sequence number set in the SSN field of the bitmap held by the second station STA1-2 is equal to or greater than the above-mentioned SN_th, the first station STA1-1 updates the WinStart of the BA Window of the first station STA1-1 to the WinStart of the second station STA1-2.

[0181] [Second Modification of the Second Embodiment] The first access point AP1-1 may transmit a BAR frame when any of the following conditions is met. (Condition 1) The first access point AP1-1 compares the sequence number (hereinafter referred to as SN_new1) of the data frame to be transmitted that is stored in the transmission buffer implemented in the first access point AP1-1 with the latest sequence number (hereinafter referred to as SN_old1) of the data frame that was most recently successfully transmitted to the first station STA1-1, and if the difference between these sequence numbers exceeds the size of the BA window held by the first station STA1-1, the first access point AP1-1 transmits a BAR frame with SN_new1 set in the SSN field to the first station STA1-1.

[0182] (Condition 2) The first access point AP1-1 maintains a BA window update timer. If the first access point AP1-1 has successfully transmitted a data frame or a BAR frame to the first station STA1-1 (i.e., if the intended BA frame has been received), it sets the value of the BA window update timer to, for example, Y [sec] (e.g., 4 seconds) and begins counting down in usec units. If the first access point AP1-1 has successfully transmitted a data frame or a BAR frame to the first station STA1-1 during the countdown, the value of the BA window update timer is reset to Y [sec].

[0183] On the other hand, when the value of the BA Window update timer reaches 0, the first access point AP1-1 transmits to the first station STA1-1 a BAR frame in which the sequence number of the data frame that failed to be transmitted to the first station STA1-1 is set in the SSN field.

[0184] (Condition 3) When the first access point AP1-1 attempts to transmit a new data frame to the first station STA1-1 after Y [sec] or more has elapsed since the most recent successful transmission of a data frame or BAR frame to the first station STA1-1, it transmits a BAR frame to the first station STA1-1 with the sequence number of the new data frame to be transmitted set in the SSN field before transmitting the new data frame.

[0185] (Condition 4) When the first access point AP1-1 transmits a new data frame to the first station STA1-1 after Y [sec] or more has elapsed since the most recent successful transmission of a data frame or BAR frame to the first station STA1-1, and the number of retransmissions of the new data frame reaches M or more, the first access point AP1-1 transmits a BAR frame to the first station STA1-1 with the sequence number of the new data frame set in the SSN field.

[0186] (Condition 5) When the first access point AP1-1 transmits a data frame with a sequence number (hereinafter referred to as SN_new5) to the first station STA1-1 and receives a BA frame returned from the first station STA1-1, the first access point AP1-1 calculates the difference (hereinafter referred to as SN_diff5) between the sequence number (hereinafter referred to as SN_ba) set in the SSN field of the received BA frame and the above-mentioned SN_new5. Note that the method of calculating SN_diff5 differs depending on whether SN_new5 is equal to or greater than SN_ba or whether SN_new5 is less than SN_ba.

[0187] Specifically, if SN_new5 is equal to or greater than SN_ba, SN_diff5 is calculated as "SN_new5-SN_ba." On the other hand, if SN_new5 is less than SN_ba, SN_diff5 is calculated as "4095-SN_ba+SN_new5." If SN_diff5 is equal to or greater than the above-mentioned SN_th, the first access point AP1-1 transmits a BAR frame with SN_new5 set in the SSN field to the first station STA1-1. Note that although a BAR frame is used here, other frames may also be used. For example, an Action frame including at least a TID field and an SSN field may also be transmitted.

[0188] [Third embodiment] Next, a third embodiment will be described. In the second embodiment described above, a process in which (an access point included in) the wireless base station AP MLD transmits a BAR frame and updates the reception history on the wireless terminal STA MLD side has been mainly described, but in this embodiment, a process in which the wireless terminal STA MLD autonomously updates the reception history will be described.

[0189] 24 is a block diagram showing a schematic configuration example of a first wireless terminal STA MLD1 according to an embodiment. As described above, the first wireless terminal STA MLD1 includes a first station STA1-1, a second station STA1-2, and a controller STA CT1. The first station STA1-1 and the second station STA1-2 correspond to the wireless link units 310 and 320 of the wireless communication device 300, and the controller STA CT1 corresponds to the controller unit 330 of the wireless communication device 300.

[0190] The Scoreboard Context Control (hereinafter referred to as SCC) included in the first station STA1-1 and the Scoreboard Context Control included in the second station STA1-2 are both functional units included in the LMAC layer. The Receive Reordering Buffer Control (hereinafter referred to as RxRBC) included in the controller STA CT1 is a functional unit included in the UMAC layer.

[0191] The SCC stores acknowledgement information including the reception status (e.g., whether the MPDU was received successfully) of a MAC frame (e.g., MPDU) from a source device (e.g., the first access point AP1-1) received by a destination device (e.g., the first station STA1-1). The SCC also stores the source MAC address, TID, and sequence number of the frame when successful reception is confirmed.

[0192] The acknowledgement information records successful reception in a bitmap format. The acknowledgement information has multiple bit fields, each containing one bit per MPDU frame, and indicates successful reception of the MPDU frame corresponding to the bit field set to 1. The bitmap is, for example, 64 bits long. The first station STA1-1 returns a BA frame containing the bitmap, thereby notifying the first access point AP1-1 included in the first wireless base station AP MLD1 of the acknowledgement information. The BA frame has a field for setting a start sequence number (hereinafter referred to as SSN) indicated by the first bit in the bitmap. Each time the bitmap is shifted by one bit from the first bit, the sequence number increases by one from the start sequence number. In other words, the first bit in the bitmap is acknowledgement information for the MPDU frame with the sequence number indicated by SSN, and the next bit is acknowledgement information for the data frame with the sequence number indicated by SSN+1.

[0193] At least one bitmap information is stored for each pair of source MAC address and TID. There are two methods for storing bitmap information: Partial-State Operation and Full-State Operation. In Partial-State Operation, all bitmap information stored by the SCC is used, and when there is no other memory area to record bitmap information, if an MPDU frame containing a new source MAC address or TID is received, one of the one or more pieces of recorded bitmap information is reset to 0, and the reception information of the newly received MPDU frame is recorded. On the other hand, in Full-State Operation, In Operation, the bitmap information corresponding to Full-State is dedicated to one source MAC address and TID. Therefore, even if an MPDU frame containing a new source MAC address or TID is received, the bitmap information is not reset. In this embodiment, either retention method can be applied.

[0194] The RxRBC temporarily stores the received frames transferred from the first station STA1-1 and the second station STA1-2 in memory. When storing the received frames in memory (or after storing the received frames in memory), the RxRBC Reordering is performed to rearrange MAC frames in the order of their sequence numbers for each pair of source MAC address and TID included in the Header. The purpose of this is to rearrange the received frames in the order of their sequence numbers when RxRBC transfers the received frames to the next process in the MAC layer of the wireless communication system (for example, Replay detection process, which is one of the authentication processes) or to an outside of the MAC layer.

[0195] FIG. 25 is a diagram for explaining control by SCC and RxRBC. 25 includes QoS data frames (one of the MPDU frames) with sequence numbers 100 to 105. A-MPDU2 includes QoS data frames with sequence numbers 103, 106, and 107.

[0196] 25, it is assumed that the first access point AP1-1 transmits A-MPDU1 to the first station STA1-1, and the first station STA1-1 receives a QoS data frame with a sequence number other than 103. In this case, if the state of BA Bitmap1 (in other words, the start number and end number of the BA window) immediately before receiving A-MPDU1 is "WinStart_R=100" and "WinEnd_R=163," and if the size of BA Bitmap1, WinSize_R (in other words, the size of the BA window), is 64 and all bits are 0, then in the bitmap within BA Bitmap1 after receiving A-MPDU1, 1 is set to the bit positions of sequence numbers 100, 101, 102, 104, and 105 of the frame received by the SCC included in the first station STA1-1, and the other bits remain 0. At this time, frames with sequence numbers 100, 101, 102, 104, and 105 are transferred from SCC to RxRBC, so the data is stored in the receive buffer of RxRBC as shown in Buffer1. After that, RxRBC transfers the received frames with consecutive sequence numbers 100 to 102, starting from the smallest number, to the next process in the MAC layer. As a result, the receive buffer of RxRBC becomes Buffer2, WinStart_B becomes 103, and WinEnd_B becomes 166.

[0197] Next, assume that the first access point AP1-1 transmits A-MPDU2 to the first station STA1-1, and all QoS data frames are received by the first station STA1-1. In this case, in the bitmap in BA Bitmap2 after receiving A-MPDU2, 1 is set to the bit positions of sequence numbers 103, 106, and 107 of the frames received by the SCC included in the first station STA1-1. As a result, 1 is set to the bit positions of sequence numbers 100 to 107, and the rest are set to 0. At this time, the frames with sequence numbers 103, 106, and 107 are transferred from the SCC to RxRBC, and data is stored in the receive buffer of RxRBC as shown in Buffer3. Thereafter, as in the above case, RxRBC transfers the received frames with consecutive sequence numbers 103 to 107, starting from the smallest sequence number, to the next process in the MAC layer. Therefore, the receive buffer of RxRBC becomes empty like Buffer4, WinStart_B becomes 108, and WinEnd_B becomes 171.

[0198] FIG. 26 is a flowchart showing the procedure for updating the BA window executed by the SCC. First, the SCC receives a QoS data frame transmitted from the wireless base station AP MLD (step S51). Next, the SCC resets a parameter i (described later) to 0 (step S52). The SCC extracts a sequence number from the Sequence Control field of the QoS data frame received in the processing of step S51 (step S53).

[0199] The SCC checks whether the sequence number extracted in step S53 is included in any of Range1 to Range3 shown in FIG. 21 (step S54).

[0200] If it is determined as a result of the processing in step S54 that the extracted sequence number is included in Range 1 (Range 1 in step S54), the SCC determines that the sequence number is included in the range of the current BA Window and that updating WinStart_R and WinEnd_R is unnecessary, and executes the processing in step S59 described below.

[0201] If it is determined in step S54 that the extracted sequence number is included in Range2 (Range2 in step S54), the SCC determines that the sequence number is newer than the current WinEnd_R, updates WinEnd_R to the sequence number, updates WinStart_R to the value calculated by "WinEnd_R-(WinSize-1)", and updates the BA Window (step S55).Then, the SCC executes the process of step S59, which will be described later.

[0202] If it is determined in step S54 that the extracted sequence number is within Range 3 (Range 3 in step S54), the SCC determines that the sequence number is older than the current WinEnd_R, and then checks whether the parameter i is 1 or greater (step S56). The parameter i indicates the number of times that the sequence number was determined to be within Range 3 for one QoS data frame reception and the BA Window was updated.

[0203] As a result of the processing in step S56, if it is determined that the parameter i is less than 1, that is, that the BA Window has not been updated for one QoS data frame reception (No in step S56), the SCC updates WinStart_R to WinStart_B notified from RxRBC. Following the update of WinStart_R, the SCC also updates WinEnd_R to a value calculated by "WinStart_R + (WinSize - 1)" (step S57). Thereafter, the SCC updates the value of the parameter i to a value incremented by 1 (step S58), and executes the processing in step S54 again.

[0204] On the other hand, as a result of the processing in step S56, if it is determined that the parameter i is 1 or more, that is, the number of updates of the BA Window is 1 or more (Yes in step S56), the SCC transmits a BA frame including bitmap information of the range indicated by the BA Window to the first access point AP1-1 included in the first wireless base station AP MLD1 (step S59), and terminates this series of processing. Note that the parameter i indicates the number of times that WinStart_R held by the SCC is updated to WinStart_B held by the RxRBC for one reception of a QoS data frame. In the processing in step S56 of FIG. 26, if WinStart_R has been updated once, the second and subsequent updates of WinStart_R are not performed, and the processing proceeds to step S59. This is because it is assumed that WinStart_B updates do not occur frequently within a short period of time, and the value does not change even if WinStart_R is updated two or more times. On the other hand, if it is expected that WinStart_B will be updated multiple times between the time the first station STA1-1 receives the QoS data frame and the time it starts transmitting the corresponding BA frame, the threshold value may be set to a value of "2" or more instead of "1" in the processing of step S56.

[0205] According to the third embodiment described above, the wireless terminal STA MLD can autonomously update the start number and end number of the BA window based on the sequence number of the data frame transmitted from and received by the wireless base station AP MLD. In other words, the wireless terminal STA MLD can update the start number and end number of the BA window autonomously without receiving a BAR frame from the wireless base station AP MLD. Bitmap information can be updated, and for example, communication can be efficiently resumed on a wireless link where communication has been interrupted.

[0206] A modification of the third embodiment will be described below.

[0207] [First Modification of the Third Embodiment] FIG. 27 is a flowchart showing the procedure of the process of updating WinStart_R executed by RxRBC. First, the RxRBC recognizes the source MAC address (TA) and TID of the reception reordering buffer (Rx Reordering Buffer) managed for each source MAC address and TID (step S61).

[0208] Next, RxRBC searches for an SCC that manages a BA Bitmap that matches the source MAC address and TID recognized in the processing of step S61, and obtains WinStart_R and the identifier of the wireless link part that includes the SCC (i.e., the ID of the station STA (e.g., Link ID, MAC address, etc.)) from the SCC part obtained as the search result (step S62).

[0209] RxRBC sets the number of WinStart_Rs acquired in the process of step S62 to a parameter n (where n is an integer equal to or greater than 1), which is one of the internal parameters (step S63).

[0210] In the following description, it is assumed that the WinStart_R acquired in the processing of step S62 are WinStart_R1, WinStart_R2, ..., WinStart_Rn, and the IDs of the wireless link units corresponding to these WinStart_R are ID1, ID2, ..., IDn.

[0211] RxRBC extracts the latest value from the acquired WinStart_R1 to WinStart_Rn (step S64). In the following description, the extracted latest value will be referred to as WinStart_R_new. For example, if WinStart_R2 is the latest value, the above-mentioned WinStart_R_new becomes WinStart_R2. Note that the WinStart_R of the SSC included in the wireless link unit that recently transferred the received frame to RxRBC may be extracted as the latest value, or the WinStart_R with a value closest to WinStart_B held by RxRBC may be extracted as the latest value.

[0212] Next, RxRBC initializes a parameter k, which is one of the internal parameters, to 1 (step S65). RxRBC compares WinStart_Rk with WinStart_R_new and calculates the difference (hereinafter referred to as SN_diff_k) (step S66). Note that in the processing of step S66, the method of calculating SN_diff_k differs depending on whether WinStart_Rk is equal to or greater than WinStart_R_new or whether WinStart_Rk is less than WinStart_R_new.

[0213] Specifically, if WinStart_Rk is equal to or greater than WinStart_R_new, SN_diff_k is calculated as "(WinStart_Rk) - (WinStart_R_new)". On the other hand, if WinStart_Rk is less than WinStart_R_new, SN_diff_k is calculated as "4095 - (WinStart_R_new) + (WinStart_Rk)".

[0214] RxRBC determines whether SN_diff_k calculated in the process of step S66 is equal to or greater than a preset threshold value (hereinafter referred to as SN_th) (step S67). Note that, as a result of the process of step S67, if it is determined that SN_diff_k is less than SN_th (No in step S67), the process of step S70 described later is executed.

[0215] On the other hand, as a result of the process in step S67, if it is determined that SN_diff_k is equal to or greater than SN_th (Yes in step S67), the RxRBC updates WinStart_Rk to WinStart_R_new (step S68).

[0216] The RxRBC notifies the SCC of the wireless link unit corresponding to the identifier of IDk to set the WinStart_Rk updated in the process of step S68 to WinStart_R (step S69).

[0217] After that, RxRBC increments the parameter k by 1 (step S70), and determines whether the new parameter k calculated in the processing of step S70 is greater than the parameter n (step S71). As a result of the processing of step S71, if it is determined that the parameter k is equal to or less than the parameter n (No in step S71), the processing of step S66 is executed again for the new parameter k.

[0218] On the other hand, if the result of the processing in step S71 is that the parameter k is determined to be greater than the parameter n (Yes in step S71), RxRBC determines that processing has been performed for all WinStart_R obtained in the processing in step S62, and terminates this series of processing.

[0219] In the process of step S62 described above, the timing at which RxRBC acquires WinStart_R of each SSC is specified by an update timer (not shown) provided in the wireless terminal STA MLD, and may be specified, for example, every TBTT (Target Beacon Transmission Time) or every multiple of the Beacon Interval. The timing at which RxRBC acquires WinStart_R of each SSC may be every time a beacon frame is transmitted or received. The timing at which RxRBC acquires WinStart_R of each SSC may be every time RxRBC transfers a certain number of frames (for example, 128 frames) stored in the receive buffer to the next processing unit.

[0220] Furthermore, as shown in step S69 above, it is preferable that the timing for updating WinStart_R of the SCC included in the corresponding wireless link unit is at least after RxRBC acquires WinStart_R of each SCC and WisStart_R_new is updated. Furthermore, the timing for the SCC receiving the WinStart_R notification from RxRBC to actually update the value may be immediately after the notification, after transmitting any MAC frame, or immediately after the PHY layer issues a receive request signal to the LMAC layer requesting the reception of any demodulated frame. However, it is preferable to avoid the period during which the LMAC layer analyzes the received frame as the update timing.

[0221] Furthermore, in the process of step S64 described above, RxRBC extracts the latest value from among the acquired WinStart_R1 to WinStart_Rn, but the value extracted by RxRBC does not have to be the latest value. For example, the first access point AP1-1 included in the first wireless base station AP MLD1 may transmit a MAC frame having a sequence number matching "(WinStart_R)-1" (meaning a value that is 1 smaller than the value of WinStart_R) transmitted through another wireless link to a wireless link unit updated to the latest WinStart_R. In this case, the SCC included in the wireless link unit may recognize the sequence number as an old number. Therefore, the value extracted by RxRBC is not limited to the latest value. As another method for RxRBC to extract (select) one WinStart_R, for example, RxRBC may randomly select from among WinStart_R held by SCCs that have transferred frames within 200 ms (i.e., select from among SCCs that have updated WinStart_R recently, and avoid selecting WinStart_R of an SCC that has not been updated for a while). Alternatively, RxRBC may randomly select from among WinStart_R included in the range of WinStart_B ±WinSize_R.

[0222] In the above-described processing of steps S68 and S69, RxRBC updates WinStart_R of the SCC of the wireless link unit that needs to be updated, but for example, RxRBC may reset WinStart_R of the SCC of the corresponding wireless link unit to an initial state instead of updating WinStart_R of the SCC of the corresponding wireless link unit. Specifically, RxRBC may reset BA Bitmap information having the source MAC address and TID for which initialization was requested to 0 to a state in which delivery confirmation information is not recorded (to a no temporary record state), or may reset to a state at the time of ADDBA (at the time of negotiation in which ADDBA Request and ADDBA Response frames are exchanged before starting the BA mechanism).

[0223] Furthermore, although RxRBC has acquired WinStart_R for each SCC, other values ​​may be acquired that indicate the range of delivery confirmation information stored in the Scoreboard Context Control of the SCC, not limited to WinStart_R. For example, RxRBC may acquire WinEnd_R for each SCC and update WinEnd_R for the corresponding SCC.

[0224] The above-described update process and reset process of WinStart_R by SSC are necessary when wireless communication is performed using multiple links. On the other hand, in conventional wireless communication using a single link, the above-described update process and reset process of WinStart_R by SSC may be performed, but is not necessarily required. For this reason, when the wireless terminal STA MLD performs wireless communication using multiple links with the wireless base station AP MLD, the update process and reset process of WinStart_R by SSC may be performed, and when the wireless terminal STA MLD performs wireless communication with a wireless base station (access point included in the wireless terminal STA MLD) that does not support multi-link communication, the update process and reset process of WinStart_R by SSC may not be performed.

[0225] In the above, it is assumed that the wireless terminal STA MLD transmits a BA frame, but it can also be applied to the case where the wireless base station AP MLD replies with a BA frame in response to a QoS data frame from the wireless terminal STA MLD.

[0226] [Second Modification of the Third Embodiment] The following describes a method in which a first access point AP1-1 included in a first wireless base station AP MLD1 transmits a frame to a first station STA1-1 included in a first wireless terminal STA MLD1 to initialize the Scoreboard Context Control of the SCC of the first station STA1-1. Note that in this modification, the frame transmitted to initialize the Scoreboard Context Control of the SCC of the first station STA1-1 may be transmitted when conditions 1 to 5 shown in the second embodiment described above are met.

[0227] One example of a method for initializing the Scoreboard Context Control of the SCC of the first station STA1-1 is to use an Action frame.

[0228] 28 is a diagram showing the frame format of an Action frame. The Action frame is a frame that allows a source device to notify, instruct, request, report, etc. to a destination device by including various information fields in the Frame Body field. Here, a case will be described in which the Action frame is used to request initialization of the BA Bitmap.

[0229] To request initialization of the BA Bitmap, the Frame Body field includes a BA Bitmap Initialization element. Two types of BA Bitmap Initialization elements are described below.

[0230] In the format shown in Figure 28(a), the BA Bitmap Initialization element includes an Element ID field, a Length field, an Element ID Extension field, an Initialization Control field, and a Link Mapping Of TID n field (where n is a value between 0 and 7).

[0231] The Element ID field is set to "255", which indicates that the Element ID Extension is placed immediately after the Length field.

[0232] The Length field is from the Element ID Extension to the Link Indicates the length of the fields up to the Mapping Of TID n field in octets. For example, if all fields from Link Mapping Of TID 0 to Link Mapping Of TID 7 are included, the length is 16 octets, plus the lengths of the Element ID Extension field and Initialization Control field, so the Length field is set to "19".

[0233] In the Element ID Extension field, enter "BA Bitmap A value indicating the "Initialization element" is set, for example, "150".

[0234] The Initialization Control field has a length of 2 octets and is composed of 2 Direction bits, 6 Reserved bits, and 8 Link Mapping Present Inficator bits.

[0235] The Direction bit indicates the frame transmission direction, with 0 indicating the uplink direction (i.e., the direction in which the wireless terminal STA MLD transmits a frame to the wireless base station AP MLD) and 1 indicating the downlink direction (i.e., the direction in which the wireless base station AP MLD transmits a frame to the wireless terminal STA MLD). Note that 2 indicates Bidirectional, meaning that frames are transmitted in both the uplink and downlink directions.

[0236] Reserved bits are unused bits and are generally set to 0.

[0237] The Link Mapping Present Inficator bit is a bit for indicating whether or not a Link Mapping Of TID n field exists following it. A 1 set in bit position n of the Link Mapping Present Inficator bit means that a Link Mapping Of TID n field exists, and a 0 set in bit position n means that a Link Mapping Of TID n field does not exist. For example, If the Mapping Present Inficator bit is set to "8'b1000_0011", the Link Mapping Of TID is set to 1. 0, Link Mapping Of TID 1, Link Mapping Of This means that TID 7 exists, and Link Mapping Of TID 2 to Link Mapping Of TID 6 remain 0 and do not exist.

[0238] The Link Mapping Of TID n field indicates the radio links over which MAC frames of TID n are allowed to be transmitted. When bit position i of the TID n field is set to 1, it indicates that the frame of TID n is transmitted via the link to which the wireless link portion indicated by Link ID i is wirelessly connected. For example, when "16'h0000_0001" is set in the Link Mapping Of TID 0 field and 1 is set in the Direction bit, it means that the frame with TID "0" is transmitted from the first access point AP1-1 included in the first wireless base station AP MLD1 to the first station STA1-1 included in the first wireless terminal STA MLD1 using the wireless link portion with Link ID "0".

[0239] As described above, this Action frame is a frame that requests initialization of the BA Bitmap. For example, if "16'h0000_0001" is set in the Link Mapping Of TID 0 field and the Direction bit is set to 1, this indicates a request for initialization of the BA Bitmap information held by the SCC of the first station STA1-1, which recorded the delivery confirmation of the frame with TID "0" that was transmitted from the first access point AP1-1 to the first station STA1-1 using the wireless link portion with Link ID "0".

[0240] In an Action frame including the BA Bitmap Initialization element shown in Figure 28(a), the TID and Link ID for which initialization is requested do not have to be limited to one; by setting multiple bits to 1, it is also possible to request initialization of BA Bitmap information indicated by multiple TIDs and Link IDs.

[0241] On the other hand, in the format shown in FIG. 28(b), the BA Bitmap Initialization element includes an Element ID field, a Length field, an Element ID Extension field, an Initialization Control field, and a Link Info field.

[0242] The Initialization Control field consists of 2 Direction bits and 6 Reserved bits.

[0243] 28(a), the Direction bit indicates the frame transmission direction, with 0 indicating the uplink direction (i.e., the direction in which the wireless terminal STA MLD transmits a frame to the wireless base station AP MLD) and 1 indicating the downlink direction (i.e., the direction in which the wireless base station AP MLD transmits a frame to the wireless terminal STA MLD). Note that 2 indicates Bidirectional, meaning that frames are transmitted in both the uplink and downlink directions. Also, the reserved bit is an unused bit and is basically set to 0.

[0244] The Link Info field includes a Link ID subfield and a TID subfield. The Link ID of the BA Bitmap information to be initialized is set in the Link ID subfield. The TID subfield contains the Link ID of the BA Bitmap information to be initialized. The TID of the Bitmap information is set.

[0245] For example, setting the Direction bit to 1, the Link ID to 0, and the TID to 0 indicates a request to initialize the BA Bitmap information held by the SCC of the first station STA1-1, which recorded the delivery confirmation of the frame with TID "0" that was transmitted from the first access point AP1-1 to the first station STA1-1 using the wireless link portion with Link ID "0".

[0246] The format shown in Figure 28(b) allows for the initialization of BA Bitmap information indicated by a pair of TID and Link ID to be requested for one Action frame transmission, making it easier to set up than the format shown in Figure 28(a).

[0247] Another example of a method for initializing the Scoreboard Context Control of the SCC of the first station STA1-1 is to renegotiate the BA mechanism.

[0248] Normally, when starting a BA, the device that plans to send data (Originator) first sends an ADDBA Request frame to the destination device (Recipient), and then The recipient that received the ADDBA Request frame will send an ADDBA Response frame back to the originator if there is no problem in starting the BA mechanism. By exchanging the Request / Response frames, the negotiation of the BA mechanism is completed and data (or A-MPDU) transmission begins.

[0249] On the other hand, when it is desired to terminate the BA mechanism, the device requesting termination (originator or recipient) sends a DELBA frame to the other party. This terminates the BA mechanism. Note that the originator and recipient may each be a wireless base station or a wireless terminal.

[0250] The following describes the procedure for initializing the BA Bitmap of the first station STA1-1 by using this negotiation mechanism and having the first access point AP1-1 exchange ADDBA Request / Response frames with the first station STA1-1 again.

[0251] First, the first access point AP1-1 (here, Originator) transmits a DELBA frame to the first station STA1-1 (here, Recipient) to terminate the BA mechanism of a specific link (also referred to as "performing DELBA"). Meanwhile, the BA mechanism continues in links other than the first station STA1-1 (e.g., the second station STA1-2) in the first wireless terminal STA MLD1.

[0252] After transmitting the DELBA frame, the first access point AP1-1 transmits an ADDBA Request frame to the first station STA1-1, receives an ADDBA Response frame from the first station STA1-1, and re-establishes the BA mechanism. An example of the frame formats of the DELBA frame and ADDBA Request frame used in this case will be described below.

[0253] 29 is a diagram showing the frame format of a DELBA frame. Two types of DELBA frames will be described below.

[0254] In the format shown in Figure 29(a), the Frame Body field includes a Category field, a Block Ack Action field, a DELBA Parameter Set field, and a Reason Code field. Note that the Frame Body field may also include fields other than these.

[0255] In the Category field, a value is set that means that this frame is a Block Ack-related frame, for example, 3 is set.

[0256] The Block Ack Action field is set to the type of frame action used in Block Ack negotiation, and is set to 2, for example, indicating DELBA.

[0257] The DELBA Parameter Set field contains information about which BA negotiation DELBA is used for. The DELBA Parameter Set field contains a Link ID subfield, an Intiator subfield, and a TID subfield. The Reserved subfield is an unused area and is set to 0.

[0258] The Link ID subfield is set with the ID of the Link to be DELBAd, and for example, when the first access point AP1-1 DELBAs the first station STA1-1, the Link ID is set to "0." Note that, although it is assumed here that the target of DELBAd is the first station STA1-1, if the target of DELBAd is, for example, the second station STA1-2, the Link ID is set to "1."

[0259] The Initiator subfield indicates whether the device sending the DELBA frame is the Originator or the Recipient. If it is set to 1, it means that the Originator is sending the DELBA frame, and if it is set to 0, it means that the Recipient is sending the DELBA frame.

[0260] The TID subfield is set to the TID of the data frame to be DELBAd. For example, if the first access point AP1-1 has performed ADDBA (established the BA mechanism) with TID "0" for the first station STA1-1 and then DELBAs (terminates the BA mechanism) for that TID, the TID subfield is set to 0.

[0261] The Reason Code field is set with a value indicating the reason for DELBA. In this case, DELBA is performed to initialize the BA Bitmap, so for example, 100, which means "BA_Bitmap_Initilization", is set. Note that this value can be any other value, and can be any value up to 65535 that does not overlap with values ​​already in use.

[0262] 29(a) to the first station STA1-1, and the frame is received by the first station STA1-1, the first station STA1-1 can recognize which BA negotiation to terminate from the Link ID and TID, and can recognize that the BA negotiation is not to be terminated completely but to initialize the Socreboard Context Control information of a specific link because the Reason Code is "BA_Bitmap_Initilization." Therefore, the RxRBC of the first wireless terminal STA MLD1 can prevent the information in the Receive Reordering Buffer from being discarded even when it receives this DELBA frame.

[0263] If the Reason Code is a value indicating "END_BA", the first station STA1-1 recognizes that the BA negotiation is to be completely terminated, and either discards the information in the Receive Reordering Buffer, or transfers all frames remaining in the Reordering Buffer to the upper layer and terminates the BA negotiation.

[0264] On the other hand, in the format shown in FIG. 29(b), the Frame Body field further includes a BA Bitmap Initialization element field in addition to the various fields described above.

[0265] In the case of the format shown in Figure 29(b), the DELBA Parameter Set field is an unused field and is set to 0 because the BA Bitmap Initialization element field exists. This is because the ID and TID are included in the BA Bitmap Initialization element field. For this reason, the DELBA Parameter Set field itself may be omitted, but it is necessary to add information to determine whether or not the DELBA Parameter Set field is present. Considering this complexity, it is preferable to leave the DELBA Parameter Set field as an unused field and add the BA Bitmap Initialization element field after the Reason Code.

[0266] The BA Bitmap Initialization element field is the same as the BA Bitmap Initialization element field included in the Action frame shown in FIG. 28, and is the same as the BA Bitmap Initialization element field included in the Action frame shown in FIG. 28(a). Initilizaton element field and BA shown in Figure 28(b) Either the Bitmap Initialization element field or the

[0267] The first access point AP1-1 transmits a DELBA frame in the frame format shown in FIG. 29(b) to the first station STA1-1, and when the frame is received by the first station STA1-1, the first station STA1-1 sets the Link It is possible to recognize which BA negotiation to terminate from the ID and TID. Also, when the BA Bitmap Initialization element field shown in Figure 28(a) is applied, it is possible to include multiple Link ID and TID information, and it is possible to terminate BA negotiation for multiple Link ID and TID pairs with one DELBA frame.

[0268] Furthermore, since the Reason Code is "BA_Bitmap_Initilization", it is possible to recognize that the BA negotiation is not to be completely terminated but that the Socreboard Context Control information of a specific link is to be initialized. Therefore, even if the first wireless terminal STA MLD1 receives this DELBA frame, the RxRBC of the first wireless terminal STA MLD1 can avoid discarding the information in the Receive Reordering Buffer.

[0269] 30 is a diagram showing the frame format of an ADDBA Request frame. As shown in Fig. 30, the Frame Body field of the ADDBA Request frame includes a Category field, a Block Ack Action field, a Dialog Token field, a Block Ack Parameter Set field, a Block Ack Timeout Value field, a Block Ack Starting Sequence Control field, and a BA Bitmap Initialization element field. Note that the Frame Body field may also include fields other than these.

[0270] In the Category field, a value is set that means that this frame is a Block Ack-related frame, for example, 3 is set.

[0271] The Block Ack Action field is set to the type of action of the frame used in the Block Ack negotiation, and is set to, for example, 0, which indicates an ADDBA Request.

[0272] The Dialog Token field is used to associate an ADDBA Request frame with an ADDBA Response frame, which is the response to the ADDBA Request frame. The device that sends the ADDBA Request frame (here, the first access point AP1-1) sets a value other than 0 in this field. On the other hand, the device that sends the ADDBA Response frame (here, the first station STA1-1) includes in the ADDBA Response frame a value that is the same as the value in the Dialog Token field included in the ADDBA Request frame.

[0273] The Block Ack Parameter Set field contains information about the supported functions in the BA mechanism. Although not shown in detail in Figure 30, the Block Ack Parameter Set field contains the A-MSDU (Aggregated MSDU (MAC Service Data Unit)) Supported subfield, Block Ack Policy subfield, TID subfield, Buffer Contains the Size subfield.

[0274] The A-MSDU Supported subfield contains information indicating whether A-MSDU is supported. The Block Ack Policy subfield contains information indicating support for the HT-immediate block ack mode (a BA frame is returned in SIFS after receiving an A-MPDU). The TID subfield contains the TID for which ADDBA is requested. The Buffer Size subfield contains the size value of the receive buffer to be used. Based on this value, the recipient (in this case, the first station STA1-1) determines the memory size for storing MPDUs in the RxRBC Reordering Buffer and the memory size of the BA Bitmap, which holds the SCC data reception history. If the buffer size indicated in the ADDBA Request frame is larger than the memory capacity supported by the first station STA1-1, the first station STA1-1 can return the buffer size it supports in the ADDBA Response frame.

[0275] The Block Ack Timeout Value field sets the timeout period for terminating the BA mechanism. If this time period elapses without any frame exchange using the BA mechanism after the BA mechanism is established, the BA mechanism is terminated.

[0276] The Block Ack Starting Sequence Control field includes a Starting Sequence Number subfield and a Fragment Number subfield. The Fragment Number subfield is set to 0. The Starting Sequence Number subfield is set to the sequence number of the data frame that will be sent after ADDBA is re-established.

[0277] The BA Bitmap Initialization element field is the same as the BA Bitmap Initialization element field included in the Action frame shown in FIG. 22, and is the same as the BA Bitmap Initialization element field included in the Action frame shown in FIG. 28(a). Initilizaton element field and BA shown in Figure 28(b) Either the Bitmap Initialization element field or the

[0278] If the length of the Frame Body field in the ADDBA Request frame is greater than 9 bytes, the recipient (here, the first station STA1-1) that receives the frame can recognize that additional fields are included, and the values ​​of the Element ID field and Element ID Extension field determine that the additional fields are included in the BA Bitmap Initialization It can be recognized as an element field.

[0279] If the BA Bitmap Initialization element field is included, the TID in the Block Ack Parameter Set field is an unused field and is set to 0.

[0280] The first access point AP1-1 sends an ADDBA frame in the frame format shown in FIG. By transmitting a Request frame to the first station STA1-1 and receiving the frame, the first station STA1-1 can determine which BA negotiation to reestablish with the first access point AP1-1 (which can be recognized from the Address2 field) from the Link ID and TID in the BA Bitmap Initialization element field. Also, if the BA Bitmap Initialization element field is included, it is requested that the reception history in the SCC of the first station STA1-1 be initialized, and it can be determined that there is no need to initialize the Reordering Buffer in the RxRBC.

[0281] This makes it possible to initialize only the reception history held by the SCC of the first station STA1-1, while wireless links that do not require initialization (for example, the second station STA1-2) can continue wireless communication.

[0282] Another example of a method for initializing the Scoreboard Context Control of the SCC of the first station STA1-1 is for the Originator (here, the first access point AP1-1) to transmit a BAR frame.

[0283] This method initializes the BA Bitmap of the first station STA1-1 by setting the sequence number of a data frame that the first access point AP1-1 is going to transmit in the SSN field of the BAR.

[0284] When the first access point AP1-1 transmits a new data frame and does not receive a BA frame from the first station STA1-1, or receives a BA frame but it is not the BA frame intended by the first access point AP1-1 (for example, when the first access point AP1-1 checks the BA Bitmap information in the BA frame, it does not contain BA Bitmap information that includes delivery confirmation information for the data frame transmitted by the first access point AP1-1), the first access point AP1-1 retransmits the data frame. However, if the first access point AP1-1 retransmits the data frame M times (where M is an integer greater than or equal to 0) and the transmission is not successful, it gives up on transmitting the data frame.

[0285] Thereafter, the first access point AP1-1 transmits another new data frame. For this data frame, if the first access point AP1-1 does not receive a BA frame from the first station STA1-1, or if it receives one but it is not the BA frame intended by the first access point AP1-1, the first access point AP1-1 retransmits the data frame. However, if the transmission is unsuccessful after M retransmissions, the first access point AP1-1 gives up on transmitting the data frame. After repeating this operation N times (where N is an integer greater than or equal to 0), the first access point AP1-1 transmits a BAR frame in which the sequence number of the data frame to be transmitted to the first station STA1-1 is set in the SSN field.

[0286] On the other hand, in the above method using the existing BAR frame, the operation rules when the first station STA1-1 receives a BAR frame are limited to the rules of the current IEEE 802.11 standard. For example, if the SSN value of the BAR frame falls within Range 3 shown in Figure 20, the BA Bitmap in the first station STA1-1 will not be initialized.

[0287] The following describes a BAR frame that can solve this problem. This BAR frame has an additional field required to initialize the BA Bitmap.

[0288] 31 is a diagram showing the frame format of a BAR frame. Two types of BAR frames will be explained below. Note that only the main fields will be explained below. As shown in FIG. 31(a), the BAR Control field of the BAR frame includes a BA Bitmap Initialization bit. The Address1 field is set with the MAC address of the recipient (here, the first station STA1-1) whose BA Bitmap is to be reset.

[0289] The BA Bitmap Initialization bit can be set to 1 to initialize the BA This allows the first station STA1-1 to recognize that it is being requested to initialize the BA Bitmap. Furthermore, by setting the BA Bitmap Initialization bit to 1, the first station STA1-1 can initialize the BA Bitmap regardless of the position of the SSN value in Range1 to Range3 in the received BAR frame. Also, by setting the BA Bitmap Initialization bit to 1, the BA Bitmap can be initialized regardless of the position of the SSN value in Range1 to Range3 in the received BAR frame. According to this, even if the RxRBC of the first station STA1-1 receives this BAR frame, it will not discard or update the information in the Receive Reordering Buffer held by the RxRBC.

[0290] The TID_INFO field is set with the TID that requests initialization of the BA Bitmap.

[0291] The Starting Sequence Number subfield is set to the sequence number of the data frame that the first access point AP1-1 plans to transmit to the first station STA1-1, while the Fragment Number subfield is set to 0.

[0292] According to the BAR frame shown in FIG. 31(a), the first station STA1-1 The Bitmap Initialization bit allows the first access point AP1-1 to recognize that it is requesting the initialization of the BA Bitmap. 31(a) , BA Bitmap initialization is requested in the first station STA1-1 regardless of the position of Range1 to Range3 in the SSN value in the received BAR frame. Furthermore, the BAR frame shown in FIG. 31(a) can initialize only the BA Bitmap information of a specific wireless link (the first station STA1-1 in this case). Therefore, the BA Bitmap information of other wireless links (e.g., the second station STA1-2) that are not specified as the destination of the BAR frame is not initialized. Furthermore, the RxRBC of the first wireless terminal STA MLD1 does not discard the information in the Receiving Reordering Buffer upon receiving the BAR frame, so wireless communication using other wireless links can be continued.

[0293] The BAR frame shown in Figure 31(a) can be easily configured with only a few changes from the existing BAR frame. Furthermore, if the BA Bitmap Initialization bit is set to 0, it can function as an existing BAR frame.

[0294] On the other hand, in the format shown in Figure 31(b), the BAR Information field includes an Initialization Control field and a Link Mapping Of TID n field (where n is a value between 0 and 7). The Initialization Control field includes a Link Mapping Present Indicator subfield, while the Direction subfield is treated as reserved. This is because a BAR frame is a frame transmitted by the Originator, and the frame transmission direction does not necessarily need to be set in other fields.

[0295] The BA Bitmap Initialization bit is the same as in FIG. 31(a). When the BA Bitmap Initialization bit is 1, the BAR Information field contains an Initialization Control field and Link Mapping Of TID 0 to Link On the other hand, if the BA Bitmap Initialization bit is 0, then Block It can indicate that an Ack Starting Sequence Control field is included and can function as an existing BAR frame.

[0296] The Link Mapping Present Indicator subfield functions in the same way as the Link Mapping Present Indicator of the BA Bitmap Initialization element included in the Action frame shown in FIG. 28(a).

[0297] The Link Mapping Of TID 0 to Link Mapping Of TID 7 fields function in the same way as the Link Mapping Of TID 0 to Link Mapping Of TID 7 of the BA Bitmap Initialization element shown in FIG. 28(a).

[0298] 31(b), it is possible to request the initialization of multiple BA Bitmap information. Furthermore, since the RxRBC of the first wireless terminal STA MLD1 does not discard the information in the Receiving Reordering Buffer upon receiving the BAR frame, it is possible to continue wireless communication using other wireless links for which initialization is not required.

[0299] According to at least one of the embodiments described above, it is possible to provide a wireless communication device 300 (wireless base station AP MLD and wireless terminal STA MLD) and a wireless communication system that can realize efficient communication using multi-link transmission technology.

[0300] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0301] AP MLD1...first wireless base station, AP MLD2...second wireless base station, STA MLD1...first wireless terminal, STA MLD2...second wireless terminal, 10...hub, 20...controller, 300...wireless communication device, 310, 320...wireless link section, 311, 321...antenna, 312, 322...PHY layer section, 313, 323...LMAC layer section, 330...controller section, 331...UMAC layer section, 341...processor section, 342...memory section, 343...wired I / F section.

Claims

1. a plurality of sets of radio units and control units; A host control unit; Equipped with establishing communication with another wireless communication device using the plurality of wireless units; each of the wireless units receives a plurality of data frames from the other wireless communication device; each of the control units determines a reception status of each of the data frames received by each of the radio units, to determine whether or not each of the data frames has been received normally; each of the data frames can be received by any of the plurality of radio units after the communication is established, and has a sequence control field and a frame body field; The number stored in the sequence control field is assigned to each piece of data stored in the frame body field, Each of the control units is Reception history information indicating the reception status of each of the data frames is held, and a start number corresponding to the number stored in the sequence control field of each of the data frames is set in each of the reception history information; The upper control unit Controlling the difference between the start numbers set in each of the pieces of reception history information so that the difference falls within the first information. Wireless communication device.

2. The upper control unit Control is performed to advance the later start number of the first start number and the second start number set in the first reception history information and the second reception history information in each of the control units, respectively. The wireless communication device of claim 1 .

3. The first information is １１ That is, 3. The wireless communication device according to claim 1.

4. The number stored in the sequence control field of each data frame is used for a reordering process that is executed in the upper control unit and that rearranges the data stored in the frame body field of each data frame in numerical order. The wireless communication device of claim 1 .

5. Multiple radio and control unit combinations Equipped with establishing communication with another wireless communication device using the plurality of wireless units; each of the wireless units transmits a plurality of data frames to the other wireless communication device; Each of the control units transfers each of the data frames to each of the radio units; each of the data frames can be transmitted by any of the plurality of radio units after the communication is established, and has a sequence control field and a frame body field; The number stored in the sequence control field is assigned to each piece of data stored in the frame body field, Each of the control units is retaining first information; if a difference between a first number stored in a sequence control field of a first data frame to be transmitted and a second number stored in a sequence control field of a second data frame that has already been successfully transmitted exceeds the first information, before transmitting the first data frame to be transmitted, a control frame is generated in which the first number corresponding to the first data frame is stored in a sequence control field, and the control frame is transmitted via each of the radio units. Wireless communication device.

6. When there are a plurality of data frames to be transmitted, the data frame having the smallest number stored in the sequence control field is designated as the first data frame. The wireless communication device according to claim 5 .

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