Communication device and method for communication

Abstract

To provide a communication device for sending common response signals including data acquisition success-failure information for plural links.SOLUTION: A communication device that performs wireless communication using a plurality of links includes: a common storage unit of a cache type that stores success-failure of acquisition of packets received on the plurality of links; a common data processing unit for performing common data processing on the packets received on each link; and a control unit for controlling transmission of a response signal to the received packets. The control unit generates a common response signal including the success-failure information of acquisition received on the plurality of links, based on the acquisition success-failure information held by the common storage unit.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed in this specification (hereinafter referred to as "the present disclosure") relates to a communication device and a communication method that perform multi-link operation. [Background technology]

[0002] In order to cope with the recent increase in data traffic, there is a demand for an expansion of data capacity and an improvement of peak throughput in wireless LANs (Local Area Networks). As one solution, Multi-Link Operation (MLO) (see, for example, Patent Document 1), which enables communication by simultaneously using multiple frequency bands, has attracted attention and is expected to be standardized in IEEE802.11be, the next-generation standard of IEEE802.11.

[0003] Furthermore, automatic repeat-request (ARQ) technology is known to achieve high reliability in data communications. Specifically, a data receiver returns a response signal containing information on whether the data was successfully received, and the data sender retransmits the data based on the information extracted from the response signal. Typically, when a communication terminal attempts to send a response signal over a link, it is assumed that the response signal is generated in the media access control (MAC) block corresponding to the link within the communication terminal. This response signal contains only information on whether the data received over the link was successfully received (in other words, it does not contain information on whether the data received over other links was successfully received). Under this assumption, for example, if a data sender fails to receive a response signal over a link, even if the data receiver successfully received the data, the data sender will determine that the data was not received correctly and retransmit the data that the data receiver already received, resulting in waste.

[0004] Therefore, a method called Common Block Ack has been proposed as an ARQ method for MLO (see, for example, Non-Patent Document 1). In this method, the data receiver transmits to the data sender a Common Block Ack, which is a response signal including information on whether data received on the same link was successfully acquired, as well as information on whether data received on other links was successfully acquired. Therefore, even if the data sender fails to receive a response signal on one link, as long as the data sender successfully receives a response signal on another link, it can obtain information on whether data transmitted on the link on which the response signal was unsuccessful can be acquired, thereby preventing unnecessary retransmissions.

[0005] In MLO, a sender may distribute the same traffic data across multiple links. According to the Common Block Ack method, a receiver transmits a response signal that summarizes the acquisition success or failure information for the data of one Block Ack Session. Therefore, even if the sender fails to receive individual response signals containing the individual acquisition success or failure information for each link, it can prevent unnecessary retransmission as long as it successfully receives a common response signal summarizing the acquisition success or failure information for the entire Block Ack Session. Note that the Block Ack Session referred to here is a combination of a sender (sender address) and traffic (Traffic Identifier: TID). In this specification, the combination of a sender and a TID is also referred to as "sender information."

[0006] Generally, a data receiver uses a memory called a "scoreboard" to store information on whether data was successfully acquired. In Non-Patent Document 1, a Common Scoreboard is used to store information on whether data received on each link was successfully acquired in order to generate a Common Block Ack. However, the proposal in Non-Patent Document 1 assumes that the Common Scoreboard manages the information on whether data was successfully acquired in a "full-state" manner, in which a fixed memory area is allocated for each Block Ack Session (i.e., for each combination of sender and traffic identifier (TID)). This requires the implementation of expensive memory with a large storage capacity, which raises concerns about the difficulty of implementation.

[0007] On the other hand, the mainstream method of storing information on whether data was successfully acquired for each link is to use a "partial-state" scoreboard. A partial-state scoreboard is a small-capacity cache-type memory that temporarily stores the information on whether data was successfully acquired for at most one Block Ack Session. In other words, a partial-state scoreboard does not allocate a fixed memory area for each Block Ack Session like a full-state scoreboard, and instead the information is overwritten when another Block Ack Session starts on the corresponding link.

[0008] If the Common Scoreboard mentioned above were managed as a partial-state instead of a full-state type, the storage capacity could be reduced and implementation difficulty could be eased. However, the partial-state type only guarantees storage of the acquisition success / failure information for one Block Ack Session at most. Therefore, unless the update timing and conditions are specified, the Common Scoreboard may be overwritten with information from another session, which could lead to problems such as the inability to generate a Common Block Ack. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2017-28746 [Non-patent literature]

[0010] [Non-Patent Document 1] IEEE802.11 Public Contribution (20 / 0055r0, Multi-link Block Ack Architecture) Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present disclosure is to provide a communication device and a communication method for transmitting a common response signal including information on whether data acquisition was successful for a plurality of links. [Means for solving the problem]

[0012] The present disclosure has been made in consideration of the above-described problems, and a first aspect thereof provides a communication device that performs wireless communication using a plurality of links, a common data processing unit having a cache-type common storage unit that stores whether packets received via a plurality of links have been successfully acquired and that performs common data processing on packets received via each link; a control unit that controls transmission of a response signal in response to a received packet; Equipped with the control unit generates a common response signal including the acquisition success / failure information received through the plurality of links based on the acquisition success / failure information stored in the common storage unit. It is a communication device.

[0013] The communication device according to the first aspect has an individual memory unit that stores information on whether or not a packet received on an individual link has been successfully acquired, and further includes an individual data processing unit that performs individual data processing on the packets received on the individual links.

[0014] The control unit performs an update process for the common storage unit based on acquisition success / failure information for the same sender information stored in the common storage unit and the individual storage units. That is, when the individual storage units store acquisition success / failure information for the same sender information as that stored in the common storage unit, the control unit performs an update process for the common storage unit based on the acquisition success / failure information for the same sender information stored in the individual storage units.

[0015] Alternatively, the control unit performs an update process for the individual storage unit based on acquisition success / failure information relating to the same sender information stored in the common storage unit and the individual storage unit.

[0016] A second aspect of the present disclosure is a communication method for performing wireless communication using a plurality of links, comprising: a common data processing step of performing common data processing on packets received through each link using a cache-type common storage unit that stores whether packets received through a plurality of links have been successfully acquired; a control step of controlling transmission of a response signal in response to the received packet; and In the control step, a common response signal including the acquisition success / failure information received through the plurality of links is generated based on the acquisition success / failure information stored in the common storage unit. It is a method of communication.

[0017] Furthermore, a third aspect of the present disclosure is a communication unit that performs wireless communication using a plurality of links; a control unit that controls wireless communication operations in the communication unit; Equipped with the control unit notifies whether or not a common response signal including acquisition success information regarding reception of the data signals on the plurality of links is requested when transmitting the data signals on the plurality of links; It is a communication device.

[0018] A fourth aspect of the present disclosure is a communication method for performing wireless communication using a plurality of links, comprising: a step of notifying whether or not a common response signal including acquisition success information regarding reception of the data signals on the plurality of links is required, and transmitting the data signals; receiving a response signal; It is a communication method having the above. [Effects of the Invention]

[0019] According to the present disclosure, it is possible to provide a communication device and a communication method that transmit a common response signal using a cache-type common storage unit that stores information on whether packets received via multiple links were successfully acquired.

[0020] It should be noted that the effects described in this specification are merely examples, and the effects brought about by the present disclosure are not limited to these. Furthermore, the present disclosure may also bring about additional effects in addition to the effects described above.

[0021] Further objects, features, and advantages of the present disclosure will become apparent from the following detailed description based on the embodiments and accompanying drawings. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a communication system. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of the communication device 200. [Figure 3] FIG. 3 is a diagram showing an example of the functional configuration of an MLD. [Figure 4] FIG. 4 is a diagram showing an example of the operation of the multi-link operation. [Figure 5] FIG. 5 is a diagram showing another example of the multi-link operation. [Figure 6] FIG. 6 is a diagram showing an example of a communication sequence in a communication system that supports MLO. [Figure 7] FIG. 7 is a diagram showing an example of the configuration of the ADDBA Capabilities field. [Figure 8]FIG. 8 is a flowchart showing a processing procedure for a STA to transmit data in the Data Transmission phase. [Figure 9] FIG. 9 is a flowchart showing a processing procedure (first embodiment) executed by the AP in the Data Transmission phase. [Figure 10] FIG. 10 is a diagram showing an example of an internal sequence when the AP receives a data signal. [Figure 11] FIG. 11 is a diagram showing another example of an internal sequence when the AP receives a data signal. [Figure 12] FIG. 12 is a flowchart showing a processing procedure (first embodiment) for an AP to transmit a Block Ack. [Figure 13] FIG. 13 is a diagram showing an example of an internal sequence when the AP transmits a Block Ack. [Figure 14] FIG. 14 is a diagram showing another example of the internal sequence when the AP transmits a Block Ack. [Figure 15] FIG. 15 is a diagram showing an example of the configuration of a Block Ack Request frame. [Figure 16] FIG. 16 is a flowchart showing a processing procedure when a sender transmits a BAR frame. [Figure 17] FIG. 17 is a flowchart showing the processing procedure when the receiver receives a BAR frame. [Figure 18] FIG. 18 is a diagram showing an example of an internal sequence when a receiver receives a BAR frame. [Figure 19] FIG. 19 is a diagram showing an example of a communication sequence of multi-link operation (first embodiment). [Figure 20] FIG. 20 is a diagram showing the status of each scoreboard in the AP when the communication sequence shown in FIG. 19 is performed. [Figure 21] FIG. 21 is a diagram showing another example of a communication sequence (first embodiment) of multi-link operation. [Figure 22] FIG. 22 is a diagram showing the status of each scoreboard in the AP when the communication sequence shown in FIG. 21 is performed. [Figure 23] FIG. 23 is a diagram showing yet another example of a communication sequence (first embodiment) of multi-link operation. [Figure 24] FIG. 24 is a diagram showing the status of each scoreboard in the AP when the communication sequence shown in FIG. 23 is performed. [Figure 25] FIG. 25 is a flowchart showing a processing procedure (second embodiment) executed by the AP in the Data Transmission phase. [Figure 26] FIG. 26 is a diagram showing an example of an internal sequence when the AP receives a data signal in the data transmission phase. [Figure 27] FIG. 27 is a diagram showing another example of the internal sequence when the AP receives a data signal in the data transmission phase. [Figure 28] FIG. 28 is a flowchart showing a processing procedure (second embodiment) for an AP to transmit a Block Ack. [Figure 29] FIG. 29 is a diagram showing yet another example of a communication sequence (second embodiment) of multi-link operation. [Figure 30] FIG. 30 is a diagram showing the status of each scoreboard in the AP when the communication sequence shown in FIG. 29 is performed. DETAILED DESCRIPTION OF THE INVENTION

[0023] The technology according to the present disclosure will be described below in the following order with reference to the drawings. A. System Configuration B. Equipment configuration C. MLD functional configuration example D. Common Block Ack E. First Example E-1. Overall sequence E-2. Block Ack Setup Phase E-3. Data Transmission Phase E-4. Block Ack Request Phase E-5. Example of operation F. Second Example G.Effect

[0024] A. System Configuration 1 shows a schematic diagram of an example of a communication system that supports MLO to which the present disclosure is applied. The illustrated communication system is composed of one base station or access point (AP) and two slave stations STA (STAtion) 1 and STA2 that connect to the AP. While only two STAs are shown in FIG. 1 to simplify the drawing, it is also possible for three or more STAs to be connected to one AP.

[0025] Two links, Link 1 and Link 2, are available for data communication between the AP and STA1 and STA2. The AP, STA1, and STA2 are all communication devices that support MLO. A communication device that supports MLO is also referred to below as an MLD (Multi Link Device).

[0026] In this specification, a "link" refers to a wireless transmission path over which data can be transmitted between two communication devices. Each link is selected from a plurality of mutually independent wireless transmission paths (channels) divided, for example, in the frequency domain. The two links used in the communication system shown in FIG. 1 each use a channel selected from a plurality of channels included in one of frequency bands, such as the 2.4 GHz band, the 5 GHz band, the 6 GHz band, or the 920 MHz band. The two links used in the communication system shown in FIG. 1 may be two channels selected from the same frequency band or two channels selected from different frequency bands. Furthermore, the frequency band including the channel selected by at least one of the two links used in the communication system shown in FIG. 1 may be an unlicensed frequency band whose use is permitted by database access such as a Spectrum Access System (SAS).

[0027] B. Equipment configuration 2 shows an example of the internal configuration of communication device 200. Communication device 200 is a communication device that supports MLO, and is assumed to operate as an AP, STA1, or STA2 in the communication system shown in FIG. 1. Communication device 200 is mainly composed of a communication unit 210, a control unit 220, a storage unit 230, and an antenna 240. Furthermore, communication unit 210 includes a communication control unit 211, a communication storage unit 212, a data processing unit consisting of a common data processing unit 213 and an individual data processing unit 214, a signal processing unit 215, a wireless interface (IF) unit 216, and an amplifier 217.

[0028] An individual data processing unit 214, a signal processing unit 215, a wireless interface (IF) unit 216, an amplifier unit 217, and an antenna 240 are provided for each link. The communication device 200 is assumed to perform MLO using two links, Link1 and Link2. For example, the individual data processing unit 214-1, the signal processing unit 215-1, the wireless interface unit 216-1, the amplifier unit 217-1, and the antenna 240-1 are considered as one individual communication set for transmission and reception processing in Link1, and the individual data processing unit 214-2, the signal processing unit 215-2, the wireless interface unit 216-2, the amplifier unit 217-2, and the antenna 240-2 are considered as another individual communication set for transmission and reception processing in Link2.

[0029] The communication control unit 211 controls the operation of each unit in the communication unit 210 and the transmission of information between each unit. The communication control unit 211 also controls the transfer of control information and management information to be notified to other communication devices to the data processing units (common data processing unit 213, individual data processing unit 214-1, and individual data processing unit 214-2).

[0030] The communication storage unit 212 stores information used by the communication control unit 211. The communication storage unit 212 also stores data transmitted by the communication device 200 and data received by the communication device 200.

[0031] The data processing unit is made up of a common data processing unit 213 and an individual data processing unit 214. The individual data processing unit 214 is made up of an individual data processing unit 214-1 and an individual data processing unit 214-2 for each link.

[0032] During transmission, the common data processing unit 213 performs sequence management of the data stored in the communication storage unit 212 and the control information and management information received from the communication control unit 211, performs encryption processing and the like to generate data units, and allocates them to the individual data processing units 214-1 and 214-2. During reception, the common data processing unit 213 performs decryption processing and reordering processing of the data units.

[0033] In the present disclosure, when the Common Block Ack method is applied, the common data processing unit 213 uses a partial-state or cache type Common Scoreboard to perform data processing for transmitting a Common Block Ack that summarizes information on whether data acquisition was successful for each Block Ack Session, i.e., for each sender information, but details will be described later.

[0034] During transmission, the individual data processing units 214-1 and 214-2 perform channel access operations based on carrier sense on the corresponding link, add MAC headers and error detection codes to the data to be transmitted, and perform concatenation of multiple data units. During reception, the individual data processing units 214-1 and 214-2 perform MAC header deconcatenation processing, analysis and error detection, and retransmission request operations for the received data units.

[0035] The operations of the common data processing unit 213 and the individual data processing units 214-1 and 214-2 are not limited to those described above, and one may perform the operation of the other, for example.

[0036] During transmission, signal processing units 215-1 and 215-1-2 perform encoding, interleaving, modulation, etc. on data units, add physical headers, and generate symbol streams. During reception, signal processing units 215-1 and 215-2 analyze the physical headers and perform demodulation, deinterleaving, decoding, etc. on the symbol streams to generate data units. Furthermore, signal processing units 215-1 and 215-2 estimate complex channel characteristics and perform spatial separation processing as necessary.

[0037] During transmission, the radio interface units 216-1 and 216-2 perform digital-to-analog signal conversion, filtering, up-conversion, and phase control on the symbol stream to generate a transmission signal, and during reception, the radio interface units 216-1 and 216-2 perform down-conversion, filtering, and analog-to-digital signal conversion on the received signal to generate a symbol stream.

[0038] Amplification units 217-1 and 217-2 amplify signals input from wireless interface units 216-1 and 216-2 or antennas 240-1 and 240-2. Part of amplification units 217-1 and 217-2 may be components outside communication unit 210. Furthermore, part of amplification units 217-1 and 217-2 may be included in wireless interface units 216-1 and 216-2.

[0039] The control unit 220 controls the communication unit 210 and the communication control unit 211. The control unit 220 may also perform some of the operations of the communication control unit 211. The communication control unit 211 and the control unit 220 may also be configured as a single block.

[0040] The storage unit 230 holds information used by the communication unit 210 and the control unit 220. The storage unit 230 may also perform part of the operations of the communication storage unit 212. The storage unit 230 and the communication storage unit 212 may also be configured as a single block.

[0041] The individual data processing unit 214-1, signal processing unit 215-1, wireless interface unit 216-1, amplifier unit 217-1, and antenna 240-1 constitute one individual communication set, and perform wireless communication via Link 1. The individual data processing unit 214-2, signal processing unit 215-2, wireless interface unit 216-2, amplifier unit 217-2, and antenna 240-2 constitute another individual communication set, and perform wireless communication via Link 2. While only two individual communication sets are depicted in FIG. 2, the communication device 200 may be configured with three or more sets of individual communication sets, each of which performs wireless communication via its respective link. The memory unit 230 or the communication memory unit 212 may be included in each individual communication set.

[0042] A link is a wireless transmission path that allows data transmission between two communication devices, and each link is selected from, for example, a plurality of mutually independent wireless transmission paths (channels) divided in the frequency domain. The links used by each of the individual communication sets may be two channels selected from the same frequency band, or two channels selected from different frequency bands. Furthermore, the individual data processing unit 214 and the signal processing unit 215 may be configured as one pair, and two or more pairs may be connected to one common wireless interface unit 216.

[0043] The wireless interface unit 216, the amplifier unit 217, and the antenna 240 may be grouped together, and two or more groups may be components of the communication device 200.

[0044] The communication unit 210 can also be configured by one or more LSIs (Large Scale Integration).

[0045] The common data processing unit 213 is also referred to as an Upper MAC or a Higher MAC, and the individual data processing unit 214 is also referred to as a Lower MAC. The set of the individual data processing unit 214 and the signal processing unit 215 is also referred to as an AP entity or a Non-AP entity. Alternatively, the set of the individual data processing unit 214 and the signal processing unit 215 is also referred to as a MAC entity, without distinguishing between AP and Non-AP. The communication control unit 211 is also referred to as an MLD management entity.

[0046] C. MLD functional configuration example 3 shows an example of the functional configuration of a communication device that supports MLO, i.e., an MLD. For simplicity, only the functional blocks relevant to this disclosure when receiving data are shown. In FIG. 3, the Link1 MAC Entity and Link2 MAC Entity are functional blocks within the individual data processing units 214-1 and 214-2, respectively, and the MLD Entity is a functional block within the common data processing unit 213.

[0047] A MAC address is assigned to each of the Link1 MAC Entity, Link2 MAC Entity, and MLD Entity. The MAC addresses assigned to the MAC Entities of the respective links are used as the sending and receiving addresses for communications via Link1 and Link2. It is also assumed that the MAC address assigned to the MLD Entity will be used when establishing authentication or a Block Ack Session.

[0048] The Link1 MAC Entity and Link2 MAC Entity each include a MAC Protocol Data Unit (A-MPDU) De-aggregation block, a MAC Header+Cyclic Redundancy Code (CRC) Validation block, and a Link Scoreboard block as functional blocks that perform MAC layer reception processing on the corresponding link.

[0049] The A-MPDU De-aggregation block performs processing to divide a data signal that has been transmitted by aggregating multiple packets (data units) into individual packets.

[0050] The MAC Header + CRC Validation block reads the MAC header of each packet divided by the A-MPDU De-aggregation block and checks the CRC of the entire packet. This block recognizes the destination of the received packet and the type of the received packet (whether it is a data signal or a control signal) from the information in the MAC header. This block also checks the CRC to determine whether the received packet was correctly acquired. If this block determines that the received packet was correctly acquired, it passes the information obtained from the payload of that packet to the upper layer. On the other hand, if this block determines that the received packet was not correctly acquired, it discards the received packet at this point and does not pass the information to the upper layer.

[0051] The Link Scoreboard block stores the information on whether each packet was successfully acquired, as determined by the MPDU Header + CRC Validation block, in order to generate a Block Ack on the corresponding link. The Link Scoreboard is a partial-state scoreboard that temporarily stores the information on whether each packet was successfully acquired for at most one Block Ack Session. Details of the Link Scoreboard will be provided later.

[0052] The MLD Entity has the Block Ack Buffering and Recording block and the Common Scoreboard block, which are functional blocks that perform processing common to all links. MLD uses the Common Scoreboard to process data for sending a Common Block Ack, which summarizes the success or failure of data acquisition for each Block Ack Session, i.e., for each sender.

[0053] The Common Scoreboard block stores the success or failure of each packet acquisition, as determined by the MAC Header + CRC Validation block for each link, in order to generate a Common Block Ack. The Common Scoreboard is a partial-state scoreboard that temporarily stores the acquisition success or failure information for at most one Block Ack Session. Details of the Common Scoreboard will be provided later.

[0054] The Block Ack Buffering and Recording block temporarily stores packets received through MAC layer receive processing by each Link MAC Entity and performs reordering based on the sequence number assigned to each packet. Packets received through each Link Mac Entity are passed to the upper layer in order of their sequence numbers. If a packet cannot be received along the way, the Block Ack Buffering and Recording block temporarily stores packets with the same sequence number as that packet without passing them on to the upper layer. When a packet that could not be received is retransmitted and successfully received, or when the data sender notifies the layer that the packet will not be retransmitted via a Block Ack Request or other message, the Buffering and Recording block passes the temporarily stored packet to the upper layer.

[0055] In this embodiment, the Link Scoreboard provided in each Link MAC Entity and the Common Scoreboard provided in the MLD Entity are both managed in a partial-state format. IEEE 802.11-2016 describes the management of a partial-state scoreboard as follows, and this embodiment also basically follows the same description.

[0056] (1) The receiver MUST maintain a temporary block acknowledgment record. (2) The temporary record contains bitmap information associated with the sequence number, WindowStart R (the lowest sequence number value in the bitmap), WindowEnd R (Maximum sequence number value in the bitmap), Originator (data sender) address, TID (Traffic Identifier), Window Size R (Maximum transmission window size, a value determined during the Block Ack Session described later) is stored. (3) During partial-state operation, the receiver maintains its current record as long as it receives at least some data from the same originator. (4) When data is received from a different originator or a different TID (i.e., different sender information), the existing temporary record may be discarded, e.g., by overwriting, if resources are required to store a temporary record for the new originator and TID (i.e., new sender information).

[0057] D. Common Block Ack FIG. 4 shows an example of a communication sequence in which STA1 transmits data using Link1 and Link2 and the AP transmits a Common Block Ack in the communication system shown in FIG. 1, as an example of multi-link operation.

[0058] The horizontal axis in Figure 4 is the time axis, and shows the communication operations over time on each link between the AP and STA1. Each square block drawn with a solid line represents a transmitted frame at the corresponding communication device, link, and time, while each vertical solid arrow represents a frame transmitted to a destination, and each dotted square block represents a received frame. For simplicity, all packets transmitted from STA1 in Figure 4 have the same TID.

[0059] When STA1 acquires the right to transmit on Link 1, it transmits a data signal (A-MPDU) that aggregates packets with sequence numbers #1 to #32. When the AP receives this data signal, it transmits a Block Ack (BA) containing information on whether or not the packets with sequence numbers #1 to #32 were successfully acquired to STA1 on Link 1. Note that the information on whether or not the packets were successfully acquired is represented by information in bitmap format, and is therefore also referred to as "bitmap information" below.

[0060] Furthermore, when STA1 acquires the right to transmit on Link2, it transmits a data signal that aggregates packets with sequence numbers #33 to #64. After STA1 finishes transmitting the data signal on Link2, the AP generates a Block Ack. At this time, the AP holds not only the bitmap information for packets with sequence numbers #33 to #64 received on Link2, but also the bitmap information for packets with sequence numbers #1 to #32 received on Link1, so it generates a Common Block Ack that includes the bitmap information for sequence numbers #1 to #64 and transmits it to STA1 on Link2.

[0061] By having the AP send a Common Block Ack in this way, even if STA1 fails to correctly receive the Block Ack that the AP previously sent on Link 1, as long as it receives the Common Block Ack that the AP sent on Link 2, it can obtain bitmap information for all packets sent on each link and perform retransmission control to prevent unnecessary data retransmission.

[0062] In the example communication sequence shown in Figure 4, it is assumed that the Block Ack sent by the AP on Link 1 notifies only the bitmap information of the packets (#1 to #32) received on Link 1. However, if the AP can obtain some of the bitmap information of the packets (#33 to #64) received on Link 2 when generating the Block Ack, it may also generate and send a Common Block Ack on Link 1.

[0063] Figure 5 shows another example of a communication sequence for multi-link operation performed in the communication system shown in Figure 1. In the example of the communication sequence shown in Figure 5, STA1 transmits data using Link1 and Link2, and STA2 transmits data to the AP using Link1.

[0064] The horizontal axis in Figure 5 is the time axis, and shows the communication operations over time on each link between the AP, STA1, and STA2. Each square block drawn with a solid line represents a transmitted frame at the corresponding communication device, link, and time, while each vertical solid arrow represents a frame transmitted to a destination, and each dotted square block represents a received frame. For simplicity, the TIDs of packets transmitted from STA1 and STA2 in Figure 5 are all assumed to be the same.

[0065] When STA1 acquires the transmission right for Link1, it transmits a data signal that aggregates packets with sequence numbers #1 to #32. When the AP receives this data signal, it transmits a Block Ack containing bitmap information for packets with sequence numbers #1 to #32 to STA1 via Link1. The AP also stores the bitmap information for packets with sequence numbers #1 to #32 in the Common Scoreboard in preparation for generating a Common Block Ack.

[0066] Furthermore, when STA1 acquires the transmission right on Link2, it transmits a data signal that aggregates packets with sequence numbers #33 to #64. Here, before STA1 finishes transmitting data on Link2, STA2 acquires the transmission right on Link1 and transmits a data signal. When the AP receives a data signal from STA2, bitmap information corresponding to the data received from STA2 is held in the Common Scoreboard in the AP and the Link Scoreboard of Link1. In this case, the bitmap information corresponding to the packet received from STA1 that was held in the Common Scoreboard is likely to be deleted by overwriting, etc., because the originator (or sender information) is different. When STA1 finishes transmitting a data signal on Link2, the AP does not hold bitmap information corresponding to the packet received from STA1 on Link1 in any scoreboard, and therefore cannot send a Common Block Ack to STA1.

[0067] In this way, when managing the Common Scoreboard in a partial-state format, in the above situation, the AP, which receives data signals from multiple terminals over multiple links, has limited opportunities to send Common Block Acks. The same problem also occurs on the STA side when receiving data signals associated with multiple TIDs.

[0068] Therefore, the present disclosure provides appropriate conditions and methods for updating the Common Scoreboard in a communication system that supports MLO when the Common Scoreboard is managed in a partial-state format. According to the present disclosure, a communication device (e.g., the AP in FIG. 1) that receives data signals from multiple terminals via multiple links can increase the opportunities to send Common Block Acks, thereby improving the reliability of ARQ.

[0069] E. First Example In this section, a first embodiment of a communication system to which the present disclosure is applied will be described.

[0070] E-1. Overall sequence An example of a communication sequence performed in a communication system to which the present disclosure is applied is shown in Fig. 6. In Fig. 6, the communication system is assumed to be an MLO-compatible communication system in which one AP and one STA are connected using Link 1 and Link 2.

[0071] First, in the association phase (SEQ601), an association procedure is performed between the AP and the STA, and the STA joins the AP's BSS (Basic Service Set). In the IEEE802.11 standard, the association procedure is performed by the STA sending an association request to the AP, and the AP sending an association response to the STA to notify it of its association identifier (AID).

[0072] Next, in the MLO setup phase (SEQ602), Link1 and Link2 are set up for communication between the AP and STA. In the present disclosure, during this phase, the MAC addresses of the Link1 MAC Entity, Link2 MAC Entity, and MLD Entity are notified between the AP and STA, and these are managed as a single sender (originator). Note that the MLO setup phase may be included in the association phase.

[0073] Next, in the Block Ack setup phase (SEQ603), ADD Block Acknowledgement (ADDBA) Request and Response frames are exchanged between the AP and the STA to establish a Block Ack Session. The information exchanged between the AP and the STA includes Block Ack Policy, TID, Buffer Size, etc., and the aforementioned Window Size R is determined by the exchanged buffer size.

[0074] This embodiment is characterized in that the ADDBA Request frame and the ADDBA Response frame contain Common Scoreboard Capability. STAs exchange Common Scoreboard Capability, which indicates whether they can manage the Common Scoreboard, with the AP during the Block Ack setup phase. STAs can determine whether the AP can generate a Common Block Ack and set the Ack Policy correctly, for example, in the header of a data packet. Details of Common Scoreboard Capability will be described later.

[0075] Next, in the Data Transmission phase (SEQ604), the STA transmits data using Link 1 and Link 2, and the AP transmits Block Acks on Link 1 and Link 2. The STA that is transmitting the data includes an Ack Policy in the header of the packet, indicating whether it requests a Common Block Ack or a Normal Ack; details of this point will be given later. The method for updating the Common Scoreboard in this phase and the generation of a Common Block Ack will also be described later.

[0076] Next, in the Block Ack Request phase (SEQ605), the STA transmits a Block Ack Request (BAR) frame to the AP on any link (link X). In response, the AP transmits a Block Ack frame on the same link (link X). Not only when the STA wants to obtain a Block Ack, but also when the Scoreboard and Window Start R The BAR frame is also used to initialize the Common Scoreboard. How the Common Scoreboard is updated during the Block Ack Request phase will be described later.

[0077] E-2. Block Ack Setup Phase As described with reference to FIG. 6, in the Block Ack setup phase, ADDBA (ADD Block Acknowledgement) Request frames and Response frames are exchanged between the AP and the STA to establish a Block Ack Session.

[0078] Fig. 7 shows an example of the configuration of the ADDBA Capabilities field notified in the ADDBA Request frame and the ADDBA Response frame. In the example shown in Fig. 7, a part (1 bit in the illustrated example) of the 5-bit reserved area (Reserved bit) of the ADDBA Capabilities field is used to notify the Common Scoreboard Capability.

[0079] Based on the information in this Common Scoreboard Capability field, the data sender (originator) can determine whether the receiver can manage bitmap information using the Common Scoreboard and whether it can generate a Common Block Ack. Therefore, the data sender (originator) can correctly set the Ack Policy in the header of the data packet, for example.

[0080] It should be noted that the information on the Common Scoreboard Capability does not need to be included in the ADDBA Capabilities field, and may be notified in either the ADDBA Request frame or the ADDBA Response frame.

[0081] E-3. Data Transmission Phase As described with reference to FIG. 6, in the Data Transmission phase, the STA transmits data using Link1 and Link2, and the AP transmits Block Ack on Link1 and Link2.

[0082] FIG. 8 shows in the form of a flowchart the processing procedure for a STA to transmit data in the Data Transmission phase.

[0083] When a STA acquires a transmission opportunity (TXOP) by ending backoff on a link (e.g., Link1) (step S801), it determines whether to request a Common Block Ack from the AP, which is the receiving side (step S802).

[0084] When requesting a Common Block Ack from the AP (Yes in step S802), the STA sets the Ack Policy in the MAC Header / QoS Control field attached to the beginning of the packet to "Common BA" (i.e., an acknowledgment including information on whether data acquisition was successful on multiple links) and starts transmitting a data signal (step S803). Since the STA exchanges capability information (Common Scoreboard Capability) indicating whether it can manage the Common Scoreboard with the AP in the Block Ack setup phase (see Figures 6 and 7), the STA can determine whether the AP can generate a Common Block Ack and set the Ack Policy correctly in, for example, the header of the data packet.

[0085] On the other hand, if the STA does not request a Common Block Ack from the AP (No in step S802), the STA sets the Ack Policy in the MAC Header / QoS Control field attached to the beginning of the packet to something other than "Common BA" (for example, "Normal Ack") and begins transmitting the data signal (step S804).

[0086] Note that there are no particular limitations on how the STA determines whether to request a Common Block Ack in step S802. For example, the STA may request a Common Block Ack only when transmitting data that requires low latency or high reliability, or may be configured to always have a Common Block Ack sent.

[0087] FIG. 9 shows in the form of a flowchart the processing procedure when the AP receives data in the Data Transmission phase.

[0088] The AP receives a data signal on a certain link (for example, Link1), and updates the Link Scoreboard of the Link MAC entity corresponding to that link based on the information on whether data acquisition was successful or not, in a conventional manner (step S901).

[0089] Next, the AP checks whether to send a Common Block Ack (step S902). Specifically, if the AP has completed Block Ack setup including a Common Block Ack with the STA that is the data sender (originator), the AP checks whether the Ack Policy in the MAC Header / QoS Control field of the received packet is "Common BA." Since the STA exchanges capability information (Common Scoreboard Capability) indicating whether it can manage the Common Scoreboard with the AP during the Block Ack setup phase (see FIGS. 6 and 7), the AP can determine whether it can generate a Common Block Ack and set the Ack Policy correctly in, for example, the header of the data packet.

[0090] If Block Ack setup has not been completed with the data sender, or if the Ack Policy in the MAC Header / QoS Control field of the received packet is not "Common BA" (No in step S902), the AP terminates this process without updating the Common Scoreboard.

[0091] On the other hand, if the Block Ack setup is completed with the data sender and the Ack Policy in the MAC Header / QoS Control field of the received packet is "Common BA" (Yes in step S902), the AP determines whether to update the Common Scoreboard.

[0092] To determine whether to update the Common Scoreboard, the AP first checks whether the Common Scoreboard and the Link Scoreboard of the link that received the data manage the same sender information, i.e., bitmaps for the same sender and the same TID (step S903).

[0093] If the Common Scoreboard and the Link Scoreboard of the link that received the data (e.g., Link1) manage bitmaps for the same sender and the same TID (Yes in step S903), the AP updates the bitmap information in the Common Scoreboard based on the bitmap information in the Link1 Scoreboard of Link1 that received the data (or the SN information that updated the bitmap) (step S905), and terminates this processing. As a result, as long as data continues to be received from the same sender with the same TID as that managed in the Common Scoreboard, the Common Scoreboard will successively update the acquisition success / failure information for the same Block Ack Session based on the acquisition success / failure information in the scoreboard of the link that received the data.

[0094] Furthermore, if the Common Scoreboard and the Link Scoreboard of the link (e.g., Link1) through which data was received do not manage bitmaps with the same sender and the same TID (No in step S903), the AP further checks whether the Link Scoreboard of a link other than the Common Scoreboard and the link through which data was received (e.g., Link2) manages bitmaps with the same sender and the same TID as the Link Scoreboard of the link (e.g., Link1) through which data was received (step S904).

[0095] If the Link Scoreboard of another link manages the same sender information, i.e., bitmap information of the same sender and the same TID, as the Link Scoreboard of the link that received the data (Yes in step S904), the AP creates and stores new sender information, i.e., bitmap information of the new sender and TID, in the Common Scoreboard based on the bitmap information in the Link Scoreboard of the link that received the data and the other link (step S906), and terminates this processing.As a result, when data is received in which at least one of the sender or TID is different from that managed in the Common Scoreboard (i.e., when the sender information is switched), the acquisition success or failure information of the new Block Ack Session is updated in the Common Scoreboard based on the acquisition success or failure information managed by the scoreboard for each link.

[0096] Furthermore, if the Link Scoreboard of another link does not manage the same sender information, i.e., a bitmap of the same sender and the same TID, as the Link Scoreboard of the link that received the data (No in step S904), the AP terminates this process without updating the Common Scoreboard.

[0097] In this embodiment, it is assumed that the Link Scoreboard and Common Scoreboard are updated when CRC checks are performed on packets aggregated over all used links, but the timing for updating each scoreboard is not limited to this. For example, the Link Scoreboard may be updated when CRC checks are completed on all packets aggregated over each link. The Common Scoreboard may also be updated at internally determined intervals, or when reception of all data signals is completed.

[0098] In this embodiment, it is assumed that the AP acquires the MAC addresses of the subordinate STAs in the MLO setup phase, and stores and manages the MAC addresses of the Link MAC entities and MLD entities for each sender (originator). Therefore, when the AP receives data on each link, it can check the sender address and determine whether the senders of each link are the same STA.

[0099] Fig. 10 shows an example of an internal sequence when an AP receives a data signal in the Data Transmission phase. Fig. 10 shows an example of an internal sequence when an AP updates the bitmap information of the Common Scoreboard based on the bitmap information of the Link1 MAC Scoreboard, which corresponds to step S905 in the flowchart shown in Fig. 9. As described above, an AP is a communication device that supports MLO, i.e., an MLD, and, as shown in Fig. 3, includes a Link1 MAC Entity and a Link2 MAC Entity that perform individual data processing for each link, and an MLD Entity that performs data processing common to all links. In addition, scoreboards that store information on whether data acquisition was successful within the AP include the Link1 Scoreboard and Link2 Scoreboard owned by the Link1 MAC Entity and Link2 MAC Entity, and the Common Scoreboard owned by the MLD Entity.

[0100] When the Link1 MAC Entity updates the Link1 Scoreboard (Scoreboard Update) in response to receiving data on Link1, it notifies the MLD Entity of the Scoreboard Update Info, which includes the Originator Address, TID, and Updated SN.

[0101] Based on the information acquired from the Link1 MAC Entity, the MLD Entity determines whether the Common Scoreboard also manages bitmap information of the same sender information (i.e., the same Originator Address and TID) (Common Scoreboard Update Decision 1). This determination process corresponds to step S903 in the flowchart shown in Fig. 9. Here, it is assumed that Block Ack setup has been completed with the STA that is the data sender (originator), and that the Ack Policy in the MAC Header / QoS Control field of the received packet specifies "Common BA".

[0102] If the MLD Entity determines that the Common Scoreboard also manages the same Originator Address and TID bitmap information as the Link1 Scoreboard, it updates the Common Scoreboard (Common Scoreboard Update).

[0103] The MLD Entity shall update the Common Scoreboard according to the following procedure. R , WindowEnd R , WindowSize R , respectively. Rc , WindowEnd Rc , WindowSize Rc Also, if SN Space is expanded, 11 Larger numbers may be used.

[0104] (1) WindowStart Rc ≦SN≦WindowEnd Rc If so, set "1" to the field corresponding to the SN in the Common Scoreboard bitmap information. (2)WindowEnd Rc <SN≦WindowStart Rc +2 11 If so, perform the following process: (2-1)WindowEnd Rc Set SN-1 to 0. (2-2)WindowStart Rc =SN-WindowSize Rc Set to +1. (2-3)WindowEnd Rc Set to =SN. (2-4) Set "1" in the bitmap information of the Common Scoreboard corresponding to the SN.

[0105] In this embodiment, the Common Scoreboard is a Partial State type, and has only the capacity to store the bitmap information for one Block Ack Session. After going around once, it returns to the beginning and is overwritten. Rc ≦SN≦WindowEnd Rc This condition indicates that the corresponding SN fits within the current window size of the Common Scoreboard. In this case, the information on whether or not the packet of this SN was successfully acquired is set in the corresponding bit position of the bitmap of the Common Scoreboard. Rc <SN≦WindowStart Rc +2 11 This condition indicates that the end of the window size of the Common Scoreboard has been reached, and in this case, the bitmap returns to the beginning and sets information on whether or not the packet of this SN was successfully acquired.

[0106] Fig. 11 shows another example of an internal sequence when the AP receives a data signal in the Data Transmission phase. Fig. 11 shows an example of an internal sequence when the AP updates the bitmap information of the Common Scoreboard based on the bitmap information of the Link1 MAC Scoreboard and the bitmap information of the Link2 Scoreboard, which corresponds to step S906 in the flowchart shown in Fig. 9.

[0107] When the Link1 MAC Entity updates the Link1 Scoreboard (Scoreboard Update) in response to receiving data on Link1, it notifies the MLD Entity of the Scoreboard Update Info, which includes the Originator Address, TID, and Updated SN.

[0108] Based on the information acquired from the Link1 MAC Entity, the MLD Entity determines whether the Common Scoreboard also manages bitmap information for the same Originator Address and TID (Common Scoreboard Update Decision 1). This determination process corresponds to step S903 in the flowchart shown in Fig. 9. Here, it is assumed that Block Ack setup has been completed with the STA that is the data sender (originator), and that the Ack Policy in the MAC Header / QoS Control field of the received packet specifies "Common BA".

[0109] Then, when the MLD Entity confirms that the Common Scoreboard and Link1 Scoreboard do not manage bitmap information for the same Originator Address and TID, it sends a Scoreboard Originator Info Request to the Link2 MAC Entity. In response to this request from the MLD Entity, the Link2 MAC Entity sends a Scoreboard Originator Info Response including the Originator Address and TID. Note that if the MLD Entity regularly obtains Originator Address and TID information from the Link2 Scoreboard, it does not need to send a Scoreboard Originator Info Request to the Link2 MAC Entity.

[0110] Based on the information acquired from the Link2 MAC Entity, the MLD Entity determines whether to update the Common Scoreboard based on whether the Common Scoreboard manages the same sender information as the Link1 Scoreboard and the Link2 Scoreboard, i.e., the same Originator Address and TID bitmap information (Common Scoreboard Update Decision 2). This determination process corresponds to step S904 in the flowchart shown in FIG. 9.

[0111] If the Link1 Scoreboard and Link2 Scoreboard manage the same sender information, i.e., bitmap information for the same Originator Address and TID, the MLD Entity decides to create bitmap information for a new sender, i.e., a new Originator Address and TID, based on the bitmap information of both, and to update the Common Scoreboard. To do this, the MLD Entity sends a Scoreboard Request to the Link1 MAC Entity and Link2 MAC Entity.

[0112] In response to a Scoreboard Request from the MLD Entity, the Link1 MAC Entity and the Link2 MAC Entity each transmit Scoreboard Info containing bitmap information, WindowStart, WindowEnd, Originator Address, and TID.

[0113] Then, the MLD Entity updates the Common Scoreboard (Common Scoreboard Update) according to the following procedure based on the Scoreboard Info collected from the Link1 MAC Entity and the Link2 MAC Entity. R , WindowEnd R , WindowSize R , respectively. Rx , WindowEnd Rx , WindowSize Rx It is written as follows.

[0114] (1) WindowEnd Rc =max(WindowEND R1 ,WindowEND R2) In other words, the Common Scoreboard is updated to match the Link1 Scoreboard or Link2 Scoreboard, whichever has the larger final value of the sequence number stored. (2)WindowStart Rc =WindowEnd Rc -WindowSize Rc Set to +1. (3) First is WindowStart Rc , and the last one is WindowEnd Rc WindowSize such that Rc Generate a bitmap of the size (initially enter all 0s). (4)WindowStart R From WindowEnd Rc For each SN in the Common Scoreboard, if either the Link1 bitmap information or the Link2 bitmap information is "1", then "1" is set in the bitmap information of the Common Scoreboard where the corresponding SN is indicated. In other words, for an SN where at least one of the Link1 Scoreboard and Link2 Scoreboard indicates that a packet was successfully acquired, the Common Scoreboard bitmap information is also set to "1", indicating that acquisition was successful.

[0115] Also, if the sum of the window sizes of the Link Scoreboards for each link is larger than the window size of the Common Scoreboard, some bitmap information may be lost by the procedure described above when updating the Common Scoreboard. In this case, the MLD Entity may instruct links whose bitmap information could not be stored in the Common Scoreboard not to send a Common Block Ack, but to send a normal Block Ack based on the Link Scoreboard information for each link.

[0116] Furthermore, after updating the bitmap information for the Common Scoreboard, the Link Scoreboard for each link may be updated to match its own bitmap information. Specifically, for an SN where the Common Scoreboard is set to "1" and the Link Scoreboard is set to "0", the Link Scoreboard may be controlled to set "1" to the corresponding location, while leaving the WindowStart and WindowEnd of each link unchanged.

[0117] FIG. 12 shows, in the form of a flowchart, the processing procedure for the AP to send a Block Ack.

[0118] After completing reception of a data signal on a link (e.g., Link1) (step S1201), the AP checks whether the Common Scoreboard manages a bitmap with the same sender and TID as the sender of the data signal (step S1202).

[0119] If the Common Scoreboard manages a bitmap with the same sender and TID as the sender of the data signal (Yes in step S1202), the AP generates a Common Block Ack based on the information in the Common Scoreboard and sends it to the sender STA (step S1203), thereby terminating this process.

[0120] On the other hand, if the Common Scoreboard does not manage a bitmap with the same sender and TID as the sender of the data signal (No in step S1202), the AP generates a conventional Block Ack based on the information in the Link Scoreboard of the link (e.g., Link 1) that received the data signal, sends it to the sender STA (step S1204), and terminates this process.

[0121] Fig. 13 shows an example of an internal sequence when an AP transmits a Block Ack. Fig. 13 shows an example of an internal sequence when an AP transmits a Common Block Ack based on bitmap information in the Common Scoreboard, which corresponds to step S1203 in the flowchart shown in Fig. 12. An MLO-compatible AP has a Link1 MAC Entity and a Link2 MAC Entity that perform individual data processing for each link, and an MLD Entity that performs data processing common to all links. In addition, the scoreboards that store information on whether data acquisition was successful within the AP include the Link1 Scoreboard and Link2 Scoreboard held by the Link1 MAC Entity and Link2 MAC Entity, and the Common Scoreboard held by the MLD Entity.

[0122] After completing reception of the data signal on Link 1 (Data Rx End), the Link 1 MAC Entity notifies the MLD Entity of Common Block Ack Request Info, which includes the Originator Address and TID.

[0123] Based on the Common Block Ack Request Info information obtained from the Link1 MAC Entity, the MLD Entity confirms that the bitmap information of the same Originator and TID as the sender of the data received on Link1 is managed in the Common Scoreboard, and then updates the Common Scoreboard information (at least the bitmap information, WindowStart Rc , WindowEnd Rc ) to the Link1 MAC Entity.

[0124] The Link1 MAC Entity generates a Common Block Ack based on the information in the acquired Common Block Ack Response Info (Generate Block Ack) and transmits it to the sender STA (Start Block Ack Tx).

[0125] Fig. 14 shows another example of the internal sequence when the AP transmits a Block Ack. Fig. 14 shows an example of the internal sequence when the AP transmits a Block Ack in the conventional manner based on the bitmap information of the Link Scoreboard, which corresponds to step S1204 in the flowchart shown in Fig. 12.

[0126] After completing reception of the data signal on Link 1 (Data Rx End), the Link 1 MAC Entity notifies the MLD Entity of Common Block Ack Request Info, which includes the Originator Address and TID.

[0127] Based on the information in the Common Block Ack Request Info obtained from the Link1 MAC Entity, the MLD Entity confirms that the Common Scoreboard does not manage bitmap information with the same Originator and TID as the sender of the data received on Link1, and then notifies the Link1 MAC Entity of Common Block Ack Response Info that does not include Common Scoreboard information.

[0128] The Link1 MAC Entity generates a Block Ack in the conventional manner based on the information in its own Link1 Scoreboard (Generate Block Ack) and transmits it to the sender STA (Start Block Ack Tx).

[0129] E-4. Block Ack Request Phase In the Block Ack Request phase, a STA sends a Block Ack Request (BAR) frame to an AP on any link (link X). In response, the AP sends a Block Ack frame on the same link (link X). The Scoreboard and Window Start are used between the AP and the STA, not only when the STA wants to obtain a Block Ack. R The BAR frame is also used when initializing the

[0130] Fig. 15 shows an example of the structure of a Block Ack Request (BAR) frame. As explained with reference to Fig. 6, a BAR frame is transmitted from a sender (STA) to a receiver (AP) to request the transmission of a Block Ack.

[0131] The structure of the BAR frame is defined in IEEE802.11, so a detailed description will be omitted here. This embodiment is characterized in that the BAR Control field contains a Common Scoreboard Update subfield. Specifically, one bit of the Reserved field in the BAR Control field is assigned to the Common Scoreboard Update subfield.

[0132] When a sender sends a BAR frame over either link, if the sender requests the bitmap information of the receiver's Common Scoreboard, the sender sets "1" in this Common Scoreboard Update subfield and sends the BAR frame. Note that if the sender only wants to update the receiver's Common Scoreboard, the sender may send a BA frame with the RA (Receiver Address) of the BAR frame set to the MAC address assigned to the receiver's MLD entity.

[0133] 16 is a flowchart showing the processing steps when a sender transmits a BAR frame. Here, the sender is assumed to be a STA that has transmitted a data frame to an AP.

[0134] When a STA transmits a BAR on a certain link (for example, Link1) (step S1601), the STA determines whether to request updating of the Common Scoreboard simultaneously with the Link Scoreboard (step S1602).

[0135] If a request to update the Common Scoreboard is made (Yes in step S1602), the STA sets "1" in the Common Block Ack Update subfield of the BAR frame and transmits the BAR frame (step S1603).

[0136] On the other hand, if the STA does not request an update of the Common Scoreboard (No in step S1602), the STA sets "0" in the Common Block Ack Update subfield of the BAR frame and transmits the BAR frame (step S1604).

[0137] 17 is a flowchart showing the processing procedure when a receiver receives a BAR frame. Here, the receiver is assumed to be an AP that has received a data frame from a STA.

[0138] When the AP receives a BAR frame on a certain link (for example, Link1) (step S1701), it updates the Link Scoreboard corresponding to the link on which the BAR frame was received (step S1702).

[0139] Next, the AP checks whether "1" is set in the Common Scoreboard Update subfield of the BAR frame received in step S1701 (step S1703).

[0140] If "1" is set in the Common Scoreboard Update subfield (Yes in step S1703), the AP updates the Common Scoreboard (step S1704) and then sends a Block Ack (step S1705). The Common Scoreboard update process is performed according to the same processing procedure as that used when receiving data, for example, as shown in FIG. 9.

[0141] On the other hand, if "0" is set in the Common Scoreboard Update subfield (No in step S1703), the AP transmits a Block Ack without updating the Common Scoreboard (step S1705).

[0142] Fig. 18 shows an example of an internal sequence when a receiver receives a BAR frame. Fig. 18 corresponds to a case where Common Scoreboard Update=1 is set in the determination step of step S1703 in the flowchart shown in Fig. 17, and the Common Scoreboard is updated in step S1704. Here, it is assumed that the receiver AP receives a BAR frame on Link 1, and then transmits a Block Ack from Link 1. The AP is a communication device that supports MLO, i.e., an MLD, and, as shown in Fig. 3, includes a Link 1 MAC Entity and a Link 2 MAC Entity that perform individual data processing for each link, and an MLD Entity that performs data processing common to all links.

[0143] When the Link1 MAC Entity finishes the reception process of the BAR frame (BAR Rx End), it updates its own Link1 Scoreboard (Scoreboard Update).

[0144] Next, when the Link1 MAC Entity confirms that the Common Scoreboard Update subfield of the BAR frame is set to "1", it sends a Common Scoreboard Update Request including the Originator Address, TID, and Start Sequence Number (SSN) to the MLD Entity.

[0145] The MLD entity updates the Common Scoreboard based on the information included in the Common Scoreboard Update Request from the Link1 MAC entity (Common Scoreboard Update).The MLD entity then sends a Common Block Ack Response frame containing the Common Scoreboard information (bitmap information, WindowStart, WindowSize, Originator Address, and TID) to the Link1 MAC entity.

[0146] The Link1 MAC Entity generates a Block Ack based on the information contained in the Common Block Ack Response from the AP (Generate Block Ack) and starts transmitting the Block Ack (Start Block Ack Tx).

[0147] Here, the following rules apply to updating the scoreboard following a Block Ack Request, for both the Link1 Scoreboard and the Common Scoreboard.

[0148] <In the case of BAR for the same sender and the same TID> (1) WindowStart R ≦SSN≦WindowEnd R in the case of (1-1)WindowStart R Set to =SSN (1-2)WindowEnd R +1 to WindowStart R +WindowSize R Set bitmap to "0" to -1 (1-3)WindowEnd R =WindowStart R +WindowSize R Set to -1 (2)WindowEnd R <SN≦WindowStart R +2 11 in the case of (2-1)WindowStart R Set to =SSN (2-2)WindowEnd R =WindowStart R +WindowSize R Set to -1 (2-3)WindowStart R From WindowEnd RC Set the bitmap to "0" (3)WindowStart Rc +2 11 <SN≦WindowStart Rc If so, don't update

[0149] <BAR for a different sender or a different TID> (1) WindowStart R Set to =SSN (2)WindowEnd R +1 to WindowStart R +WindowSize R Set bitmap to "0" to -1 (3) First WindowStart R But the last one is WindowEnd R WindowSize such that R Create a bitmap of size .

[0150] E-5. Example of operation The first embodiment realizes generation of a Common Block Ack based on a Partial-state Common Scoreboard in a communication system that supports MLO. In this section, an example of operation in the first embodiment will be described.

[0151] Fig. 19 shows an example of a communication sequence of multi-link operation performed in the communication system shown in Fig. 1. In the example of the communication sequence shown in Fig. 19, STA1 and STA2 both transmit data to the AP using Link1 and Link2.

[0152] 19, the horizontal axis is the time axis, and indicates communication operations over time on each link of the AP, STA1, and STA2. Square blocks drawn with solid lines indicate transmitted frames at the corresponding communication device, link, and time, vertical solid arrows indicate frame transmission to the destination, and square blocks drawn with dotted lines indicate received frames.

[0153] 20 shows the bitmap information of the Link1 MAC Entity and Common Scoreboard of each link in the AP at each time (T1 to T8) when the communication sequence shown in FIG. 19 is executed. The Link1 MAC Entity and Common Scoreboard of each link are partial-state cache memories that can temporarily store information on whether packets for one Block Ack Session have been successfully acquired. The left end of the bitmap information for each scoreboard shows the WindowStart R The information that matches the SN indicated by is stored, and the WindowEnd R The information stored matches the SN indicated by the bitmap information. Each bit position of each bitmap information indicates whether the packet with the corresponding SN was successfully acquired by using 0 or 1. The SN of a packet that has not yet been received is represented as "0". The SN of a packet that has already been acquired is represented as "X", and X stores either 0 or 1 depending on whether the packet acquisition was successful or not.

[0154] 20, it is assumed that WindowSize=64, and that both STA1 and STA2 transmit packets with SNs of #1 to #32 on Link1, and transmit data with SNs of #33 to #64 on Link2 (i.e., it is assumed that STA1 and STA2 transmit packets equal to the window size by allocating them to Link1 and Link2, respectively). However, the present disclosure is not limited to the above assumption, and for example, Link1 and Link2 may contain different numbers of packets, or a number of packets less than the WindowSize may be transmitted.

[0155] Also, normally, even if the sender (Originator Address) is the same, if the TID is different, it is different sender information and is managed on the scoreboard as a separate Block Ack Session. In Figures 19 and 20, for simplicity of explanation, it is assumed that each sender (STA1, STA2) sends only data with the same TID, and each is managed on the scoreboard as a single Block Ack Session.

[0156] The communication sequence shown in FIG. 19 will be described below with reference to the status of each scoreboard shown in FIG.

[0157] When STA1 acquires the transmission right for Link1 at time T1, it starts transmitting a data signal that aggregates packets with SNs #1 to #32, and completes transmitting this aggregated data signal at time T3. Between times T1 and T3, the Link1 Scoreboard stores bitmap information regarding whether or not packets with SNs #1 to #32 transmitted from STA1 were successfully acquired, and this information is updated sequentially.

[0158] Furthermore, when STA1 acquires the transmission right for Link2 at time T2, it starts transmitting a data signal that aggregates packets with SNs #33 to #64 with the same TID as Link1, and completes transmission of this aggregated data signal at time T5. Between times T2 and T5, the Link2 Scoreboard stores bitmap information regarding whether or not packets with SNs #33 to #64 transmitted from STA1 were successfully acquired, and this information is updated sequentially.

[0159] Meanwhile, STA2 acquires the transmission right for Link1 at time T4. That is, at time T4, the transmitter of Link1 changes from STA1 to STA2. STA2 starts transmitting a data signal that aggregates packets with SN #1 to #32, and completes transmission of this aggregated data signal at time T7. After time T4, the Link1 Scoreboard stores bitmap information regarding whether or not packets with SN #1 to #32 transmitted from STA2 were successfully acquired, and this information is updated sequentially.

[0160] Also, STA2 acquires the transmission right for Link2 at time T6. That is, at time T6, the transmitter for Link2 changes from STA1 to STA2. STA2 starts transmitting a data signal on Link2 that aggregates packets with SNs #33 to #64 with the same TID as Link1, and completes transmission of this aggregated data signal at time T8. After time T6, the Link2 Scoreboard stores bitmap information regarding whether or not packets with SNs #33 to #64 transmitted from STA2 were successfully acquired, and this information is updated sequentially.

[0161] The AP's MLD Entity updates the Common Scoreboard according to the update rules explained above.

[0162] Therefore, the AP receives data signals from STA1 via both Link1 and Link2, and at time T2 when both the Link1 Scoreboard and the Link2 Scoreboard are managing bitmap information for STA1 with the same sender and the same TID, the Common Scoreboard is updated and bitmap information regarding whether or not the packet from STA1 was successfully acquired is stored.

[0163] Then, even after time T4 when the sender of Link1 changes from STA1 to STA2, Link2 Scoreboard stores bitmap information regarding whether or not packets from STA1 were successfully acquired, and so between times T2 and T5, Common Scoreboard continues to update bitmap information regarding whether or not packets from STA1 were successfully acquired. As a result, at time T5 when STA1 finishes transmitting data on Link2, Common Scoreboard stores bitmap information regarding whether or not packets with SN#1 to #64 transmitted from STA1 on Link1 and Link2 were successfully acquired (i.e., information regarding whether or not the sender and TID that completed transmission were successfully acquired). Therefore, the AP can transmit a Common Block Ack to STA1 on Link2 in accordance with the Block Ack transmission procedure shown in FIG. 12.

[0164] Meanwhile, at time T6, the AP receives data signals from STA2 via both Link1 and Link2, and both Link1 Scoreboard and Link2 Scoreboard now manage bitmap information for STA2, which has the same sender and the same TID. Therefore, the Common Scoreboard switches to storing bitmap information regarding whether packets from STA2 were successfully acquired. Between times T6 and T8, the Common Scoreboard continues to update bitmap information regarding whether packets from STA2 were successfully acquired. At this time, depending on the memory capacity of the Common Scoreboard, the bitmap information regarding STA1 that had been stored up until then may be deleted. (Assuming, as in this embodiment, that the Common Scoreboard is a partial-state cache memory large enough to store information regarding whether packets for one Block Ack Session were successfully acquired, the bitmap information regarding STA1 is deleted by overwriting.)

[0165] Thereafter, at time T8 when STA2 finishes transmitting data on Link 2, the Common Scoreboard stores bitmap information regarding whether or not STA2 has successfully acquired packets with SN#1 to #64 transmitted on Link 1 and Link 2 (i.e., information regarding whether or not the sender and TID that completed transmission were successfully acquired). Therefore, the AP can transmit a Common Block Ack to STA2 on Link 2 according to the Block Ack transmission procedure shown in FIG. 12.

[0166] Fig. 21 shows another example of a communication sequence for multi-link operation performed in the communication system shown in Fig. 1. Fig. 22 shows the status of each scoreboard in the AP at each time when the communication sequence shown in Fig. 21 is performed.

[0167] When STA1 acquires the transmission right for Link1 at time T1, it starts transmitting a data signal that aggregates packets with SNs #1 to #32, and completes transmitting this aggregated data signal at time T5. Between times T1 and T5, the Link1 Scoreboard stores bitmap information regarding whether or not packets with SNs #1 to #32 transmitted from STA1 were successfully acquired, and this information is updated sequentially.

[0168] Furthermore, when STA1 acquires the transmission right for Link2 at time T2, it starts transmitting a data signal that aggregates packets with SNs #33 to #64 with the same TID as Link1, and completes transmission of this aggregated data signal at time T3. Between times T2 and T3, the Link2 Scoreboard stores bitmap information regarding whether or not packets with SNs #33 to #64 transmitted from STA1 were successfully acquired, and this information is updated sequentially.

[0169] Meanwhile, STA2 acquires the transmission right for Link2 at time T4. That is, at time T4, the transmitter of Link2 changes from STA1 to STA2. STA2 starts transmitting a data signal that aggregates packets with SN #1 to #32, and completes transmitting this aggregated data signal at time T6. After time T4, the Link2 Scoreboard stores bitmap information regarding whether or not packets with SN #1 to #32 transmitted from STA2 were successfully acquired, and this information is updated sequentially.

[0170] Also, STA2 acquires the transmission right for Link1 at time T7. That is, at time T7, the transmitter of Link1 changes from STA1 to STA2. STA2 starts transmitting a data signal that aggregates packets with SNs #33 to #64 with the same TID as Link2, and completes transmission of this aggregated data signal at time T8. After time T7, the Link1 Scoreboard stores bitmap information regarding whether or not packets with SNs #33 to #64 transmitted from STA2 were successfully acquired, and this information is updated sequentially.

[0171] The AP's MLD Entity updates the Common Scoreboard according to the update rules explained above.

[0172] Therefore, the AP receives data signals from STA1 via both Link1 and Link2, and at time T2 when both the Link1 Scoreboard and the Link2 Scoreboard are managing bitmap information for STA1 with the same sender and the same TID, the Common Scoreboard is updated and bitmap information regarding whether or not the packet from STA1 was successfully acquired is stored.

[0173] Then, even at time T4 when the sender of Link2 changes from STA1 to STA2, both the Common Scoreboard and the Link1 Scoreboard store information on whether or not packets from STA1 were successfully acquired, so between times T2 and T5, the Common Scoreboard continues to update bitmap information on whether or not packets from STA1 were successfully acquired. As a result, at time T5 when STA1's data transmission on Link1 ends, the Common Scoreboard stores bitmap information on whether or not packets with SN#1 to #64 transmitted from STA1 on Link1 and Link2 were successfully acquired (i.e., information on whether or not the sender and TID that completed transmission were successfully acquired). Therefore, the AP can send a Common Block Ack to STA1 on Link1 in accordance with the Block Ack transmission procedure shown in FIG. 12.

[0174] Meanwhile, at time T7, the AP receives a data signal from STA2 via Link1, and both the Link1 Scoreboard and the Link2 Scoreboard begin managing bitmap information for STA2, which has the same sender and the same TID. Therefore, the Common Scoreboard switches to storing bitmap information regarding whether packets from STA2 were successfully acquired. Between times T7 and T8, the Common Scoreboard continues to update bitmap information regarding whether packets from STA2 were successfully acquired. At this time, depending on the memory capacity of the Common Scoreboard, the bitmap information regarding STA1 that had been stored up until then may be deleted. Assuming that the Common Scoreboard is a partial-state cache memory large enough to store information regarding whether packets for one Block Ack Session were successfully acquired, the bitmap information regarding STA1 is deleted by overwriting.

[0175] Thereafter, at time T8 when STA2 finishes transmitting data on Link 2, the Common Scoreboard stores bitmap information regarding whether or not STA2 has successfully acquired packets with SN#1 to #64 transmitted on Link 1 and Link 2 (i.e., information regarding whether or not the sender and TID that completed transmission were successfully acquired). Therefore, the AP can transmit a Common Block Ack to STA2 on Link 2 according to the Block Ack transmission procedure shown in FIG. 12.

[0176] 21, STA1 starts data transmission on Link1 first, and then starts data transmission of the same TID on Link2. However, even if data transmission ends on Link2 before data transmission on Link1, i.e., even if the data transmission start time and data transmission end time are reversed between the links, the AP can generate and transmit a Common Block Ack to STA1 by updating the Common Scoreboard in accordance with the update rule of the present disclosure. Furthermore, although the transmission times of data of the same TID on Link1 and Link2 do not overlap for STA2, the AP can generate and transmit a Common Block Ack to STA2 by updating the Common Scoreboard in accordance with the update rule of the present disclosure.

[0177] Fig. 23 shows yet another example of a communication sequence for multi-link operation performed in the communication system shown in Fig. 1. Fig. 24 shows the status of each scoreboard in the AP at each time when the communication sequence shown in Fig. 23 is performed.

[0178] When STA1 acquires the transmission right for Link1 at time T1, it starts transmitting a data signal that aggregates packets with SNs #1 to #32, and completes transmitting this aggregated data signal at time T3. Between times T1 and T3, the Link1 Scoreboard stores bitmap information regarding whether or not packets with SNs #1 to #32 transmitted from STA1 were successfully acquired, and this information is updated sequentially.

[0179] On the other hand, when STA2 acquires the transmission right for Link2 at time T2, it starts transmitting a data signal that aggregates packets with SNs #1 to #32, and completes transmitting this aggregated data signal at time T4. Between times T2 and T4, the Link2 Scoreboard stores bitmap information regarding whether or not packets with SNs #1 to #32 transmitted from STA2 were successfully acquired, and this information is updated sequentially.

[0180] Also, STA2 acquires the transmission right for Link1 at time T5. That is, at time T5, the transmitter of Link1 changes from STA1 to STA2. STA2 starts transmitting a data signal that aggregates packets with SNs #33 to #64 with the same TID as Link2, and completes transmission of this aggregated data signal at time T7. After time T5, the Link1 Scoreboard stores bitmap information regarding whether or not packets with SNs #33 to #64 transmitted from STA2 were successfully acquired, and this information is updated sequentially.

[0181] Meanwhile, STA1 acquires the transmission right for Link2 at time T6. That is, at time T6, the transmitter of Link2 changes from STA2 to STA1. STA1 starts transmitting a data signal that aggregates packets with SNs #33 to #64 with the same TID as Link1, and completes transmission of this aggregated data signal at time T8. After time T6, the Link2 Scoreboard stores bitmap information regarding whether or not packets with SNs #33 to #64 transmitted from STA1 were successfully acquired, and this information is updated sequentially.

[0182] The MLD entity of the AP updates the Common Scoreboard according to the update rules explained above. Therefore, at time T5, when both the Link1 Scoreboard and the Link2 Scoreboard in the AP start managing bitmap information for STA2 with the same sender and the same TID, the Common Scoreboard is updated to store bitmap information regarding whether packets from STA2 were successfully acquired.

[0183] Then, even at time T6 when the sender of Link2 changes from STA2 to STA1, the information stored in the Common Scoreboard is bitmap information regarding whether packets from STA2 were successfully acquired. Therefore, at time T7 when data transmission from STA2 on Link1 ends, the Common Scoreboard stores bitmap information regarding whether packets with SN#1 to #64 transmitted from STA2 on Link1 and Link2 were successfully acquired (i.e., information regarding whether the sender that completed transmission and the TID were successfully acquired). Therefore, the AP can send a Common Block Ack to STA2 on Link1 in accordance with the Block Ack transmission procedure shown in FIG. 12.

[0184] Meanwhile, at time T6, the AP begins receiving a data signal from STA1 via Link1. The Link1 Scoreboard manages bitmap information for STA1, while the Link2 Scoreboard manages bitmap information for STA2. Since the senders are not the same, the Common Scoreboard is not updated. Therefore, at time T8 when STA1's data transmission via Link1 ends, the Common Scoreboard still stores bitmap information regarding whether or not STA2 successfully acquired packets with SN#1 to #64 transmitted from STA2 via Link1 and Link2 (i.e., information regarding whether or not acquisition was successful for a sender or a different TID from the one at the time transmission was completed). Therefore, the AP cannot generate a Common Block Ack according to the Block Ack transmission procedure shown in FIG. 12, and instead transmits a normal Block Ack to STA1 via Link2.

[0185] 23 and 24, both STA1 and STA2 transmit data to the AP using Link1 and Link2, but STA1 starts transmitting data first, while STA2 finishes transmitting data first. In other words, the data transmission start time and data transmission end time are reversed between STA1 and STA2. In such a case, the information on whether or not STA1, which finishes its data transmission later, was able to obtain the entire Block Ack Session successfully is not stored in the Common Scoreboard, and the AP is unable to generate and transmit a Common Block Ack to STA1.

[0186] F. Second Example In the first embodiment, a method for generating a Common Block Ack based on a Partial-state Common Scoreboard has been described. However, as described with reference to Figures 23 and 24, there are cases where a Common Block Ack cannot be generated and transmitted to some senders (STAs). In the example shown in Figures 23 and 24, both STA1 and STA2 transmit data to the AP using Link1 and Link2, but the data transmission start time and data transmission end time are reversed between STA1 and STA2, so the AP cannot generate and transmit a Common Block Ack to STA1, which ends its data transmission later.

[0187] Even in a partial-state Common Scoreboard, it is possible to simultaneously store bitmap information for multiple senders or multiple TIDs depending on the memory installed. Therefore, as a second embodiment, a method for updating the scoreboard of each link based on the bitmap information of the Common Scoreboard under the condition that the partial-state Common Scoreboard can simultaneously store bitmap information for multiple senders or multiple TIDs will be described below.

[0188] FIG. 25 is a flowchart showing the processing steps for the AP to receive data in the Data Transmission phase.

[0189] The AP receives a data signal on a certain link (for example, Link1), and updates the Link Scoreboard of the Link MAC entity corresponding to that link based on the information on whether data acquisition was successful or not, in a conventional manner (step S2501).

[0190] Next, the AP checks whether to send a Common Block Ack (step S2502). Specifically, if the AP has completed a Block Ack setup including a Common Block Ack with the STA that is the data sender (originator), the AP checks whether the Ack Policy in the MAC Header / QoS Control field of the received packet is "Common BA."

[0191] If Block Ack setup has not been completed with the data sender, or if the Ack Policy in the MAC Header / QoS Control field of the received packet is not "Common BA" (No in step S2502), the AP terminates this process without updating the Common Scoreboard.

[0192] On the other hand, if the Block Ack setup is completed with the data sender and the Ack Policy in the MAC Header / QoS Control field of the received packet is "Common BA" (Yes in step S2502), the AP determines whether to update the scoreboard.

[0193] To determine whether to update the scoreboard, the AP first checks whether the Common Scoreboard and the Link Scoreboard of the link that received the data manage bitmaps for the same sender and the same TID (step S2503).

[0194] If the Common Scoreboard and the Link Scoreboard of the link that received the data (e.g., Link1) manage bitmaps for the same sender and the same TID (Yes in step S2503), the AP updates the bitmap information in the Link Scoreboard of the link that received the data based on the bitmap information in the Common Scoreboard (step S2505), and terminates this process. As a result, the Link Scoreboard of the link that received the data (e.g., Link1) is sequentially updated with information on whether or not data received with the same sender and TID was successfully acquired.

[0195] Furthermore, if the Common Scoreboard and the Link Scoreboard of the link that received the data (e.g., Link 1) do not manage bitmaps for the same sender and the same TID (No in step S2503), the AP further checks whether there is sufficient storage capacity in the Common Scoreboard (step S2504).

[0196] If the Common Scoreboard does not have sufficient storage capacity (No in step S2504), the AP ends this process without updating the Common Scoreboard.

[0197] On the other hand, if there is sufficient storage capacity in the Common Scoreboard (Yes in step S2505), the AP updates the Common Scoreboard based on the bitmap information in the Link1 Scoreboard (step S2506). As a result, as long as there is sufficient storage capacity, the Common Scoreboard is updated with information on whether or not data received from a new sender or TID was successfully acquired.

[0198] Fig. 26 shows an example of an internal sequence when an AP receives a data signal in the Data Transmission phase. Fig. 26 shows an example of an internal sequence when updating the bitmap information of the Common Scoreboard based on the bitmap information of the Link1 MAC Scoreboard, which corresponds to step S2505 in the flowchart shown in Fig. 25. The AP is a communication device that supports MLO, i.e., an MLD, and, as shown in Fig. 3, is equipped with a Link1 MAC Entity and a Link2 MAC Entity that perform individual data processing for each link, and an MLD Entity that performs data processing common to all links. In addition, scoreboards that store information on whether data acquisition was successful within the AP include the Link1 Scoreboard and Link2 Scoreboard owned by the Link1 MAC Entity and Link2 MAC Entity, and the Common Scoreboard owned by the MLD Entity.

[0199] When the Link1 MAC Entity updates the Link1 Scoreboard (Scoreboard Update) in response to receiving data on Link1, it notifies the MLD Entity of the Scoreboard Update Info, which includes the Originator Address, TID, and Updated SN.

[0200] Based on the information acquired from the Link1 MAC Entity, the MLD Entity determines whether the Common Scoreboard also manages bitmap information of the same sender information (i.e., the same Originator Address and TID) (Common Scoreboard Update Decision). This determination process corresponds to step S2503 in the flowchart shown in Fig. 25. Here, it is assumed that Block Ack setup has been completed with the STA that is the data sender (originator), and that the Ack Policy in the MAC Header / QoS Control field of the received packet specifies "Common BA".

[0201] Then, when the MLD Entity confirms that the Common Scoreboard manages the same bitmap information of the Originator Address and TID as the Link1 Scoreboard, it decides to update the Link1 Scoreboard. In this case, the MLD Entity sends Scoreboard Info, which includes the bitmap information, WindowStart, WindowSize, Originator Address, and TID, to the Link1 MAC Entity.

[0202] The Link1 MAC Entity updates the Link1 Scoreboard based on the Common Scoreboard information obtained from the MLD Entity (Scoreboard Update). The Link1 MAC Entity updates the Link1 Scoreboard according to the following procedure.

[0203] (1) WindowEnd RL1 =max(WindowEnd RL1 ,WindowEnd Rc) In other words, the Link1 Scoreboard is updated to match the Link1 Scoreboard or the Link2 Scoreboard, whichever has the larger final value of the sequence number stored. (2)WindowStart RL1 =WindowEnd RL1 -WindowSize RL1 Set to +1. (3)WindowStart Rc From WindowEnd Rc In each SN in the table, "1" is set in the Link1 Scoreboard indicated by the SN whose bitmap information of the Common Scoreboard is "1".

[0204] Fig. 27 shows another example of the internal sequence when the AP receives a data signal in the Data Transmission phase. Fig. 27 shows an example of the internal sequence when updating the bitmap information of the Link1 Scoreboard based on the bitmap information of the Common MAC Scoreboard, which corresponds to step S2506 in the flowchart shown in Fig. 25.

[0205] When the Link1 MAC Entity updates the Link1 Scoreboard (Scoreboard Update) in response to receiving data on Link1, it notifies the MLD Entity of the Scoreboard Update Info, which includes the Originator Address, TID, and Updated SN.

[0206] Based on the information obtained from the Link1 MAC Entity, the MLD Entity determines whether the Common Scoreboard also manages bitmap information for the same sender information (i.e., the same Originator Address and TID) (Common Scoreboard Update Decision).

[0207] Then, when the MLD Entity confirms that the Common Scoreboard and the Link1 Scoreboard do not manage bitmap information for the same Originator Address and TID and that the Common Scoreboard has sufficient storage capacity, it decides to update the Common Scoreboard. In this case, the MLD Entity sends a Scoreboard Request to the Link1 MAC Entity.

[0208] In response to a Scoreboard Request from the MLD Entity, the Link1 MAC Entity transmits Scoreboard Info containing bitmap information, WindowStart, WindowEnd, Originator Address, and TID.

[0209] Then, the MLD entity updates the common scoreboard (common scoreboard update) according to the following procedure based on the scoreboard information collected from the Link1 MAC entity and the Link2 MAC entity.

[0210] (1) WindowEnd Rc Set to =SN. (2)WindowStart Rc =WindowEnd Rc -WindowSize Rc Set to +1. (3) First is WindowStart Rc , and the last one is WindowEnd Rc WindowSize such that Rc Generate a bitmap of size (initially enter all 0s). (4) Set "1" in the location indicated by SN in the bitmap information of the Common Scoreboard.

[0211] FIG. 28 shows, in the form of a flowchart, the processing procedure for the AP to send a Block Ack.

[0212] When the AP completes receiving a data signal on a link (e.g., Link 1) (step S2801), it generates a Block Ack based on the Link Scoreboard information of the link (e.g., Link 1) that received the data signal, and sends it to the sender STA (step S2802), thereby completing this process.

[0213] According to the processing procedure shown in Fig. 28, the Link Scoreboard of the link that received the data is updated successively with information on whether packets from the same sender and the same TID were successfully acquired. Therefore, in step S2802 above, the AP can generate and send a Common Block Ack.

[0214] Figure 29 shows an example of a communication sequence of multi-link operation performed in the communication system shown in Figure 1. In the example of the communication sequence shown in Figure 29, TA1 and STA2 both transmit data to the AP using Link1 and Link2, as in Figure 23, but the data transmission start time and data transmission end time are reversed between STA1 and STA2.

[0215] 29 is the time axis, and indicates communication operations over time on each link of the AP, STA1, and STA2. Square blocks drawn with solid lines indicate transmitted frames at the corresponding communication device, link, and time, vertical solid arrows indicate frame transmission to the destination, and square blocks drawn with dotted lines indicate received frames.

[0216] 30 shows bitmap information for each time of the Link1 MAC Entity and Common Scoreboard for each link in the AP when the communication sequence shown in FIG. 29 is executed. At the left end of each bitmap information, R , WindowEnd on the right RThe bitmap stores information that matches the SN indicated by the bitmap. Each bit position in the bitmap represents whether the packet with the corresponding SN was successfully acquired, using 0 or 1. The SN of a packet that has not yet been received is represented as "0". The SN of a packet that has already been acquired is represented as "X", and X stores either 0 or 1 depending on whether the packet was successfully acquired or not.

[0217] Normally, the TID value is also involved in managing the scoreboard, but here, for simplicity of explanation, it is assumed that only data with the same TID is transmitted. Also, here, it is assumed that WindowSize=64, and that packets with SNs #1 to #32 are transmitted on Link1 for both STA1 and STA2, and data with SNs #33 to #64 are transmitted on Link2. However, the present disclosure is not limited to the above assumption, and for example, Link1 and Link2 may contain different numbers of packets, or a number of packets less than the WindowSize may be transmitted.

[0218] The communication sequence shown in FIG. 29 will be described below with reference to the status of each scoreboard shown in FIG.

[0219] When STA1 acquires the transmission right for Link1 at time T1, it starts transmitting a data signal that aggregates packets with SNs #1 to #32, and completes transmitting this aggregated data signal at time T3. Between times T1 and T3, the Link1 Scoreboard stores bitmap information regarding whether or not packets with SNs #1 to #32 transmitted from STA1 were successfully acquired, and this information is updated sequentially.

[0220] Between times T1 and T3, the Common Scoreboard has sufficient memory capacity, so bitmap information regarding whether packets with SN#1 to #32 transmitted from STA1 on Link1 were successfully acquired is also stored in the Common Scoreboard and updated sequentially.

[0221] On the other hand, when STA2 acquires the transmission right for Link2 at time T2, it starts transmitting a data signal that aggregates packets with SNs #1 to #32, and completes transmitting this aggregated data signal at time T4. Between times T2 and T4, the Link2 Scoreboard stores bitmap information regarding whether or not packets with SNs #1 to #32 transmitted from STA2 were successfully acquired, and this information is updated sequentially.

[0222] Between times T2 and T4, the Common Scoreboard manages bitmap information for STA1, a different sender from the Link2 Scoreboard. However, because there is sufficient memory capacity, the Common Scoreboard also stores bitmap information regarding whether packets with SN#1 to #32 sent from STA2 via Link2 were successfully acquired, and this information is updated sequentially.

[0223] Also, STA2 acquires the transmission right for Link1 at time T5. That is, at time T5, the transmitter of Link1 changes from STA1 to STA2. STA2 starts transmitting a data signal that aggregates packets with SNs #33 to #64 with the same TID as Link2, and completes transmission of this aggregated data signal at time T7. After time T5, the Link1 Scoreboard stores bitmap information regarding whether or not packets with SNs #33 to #64 transmitted from STA2 were successfully acquired, and this information is updated sequentially.

[0224] Between times T5 and T7, the Common Scoreboard manages the bitmap information of STA2, which is the same sender as the Link1 Scoreboard, and the bitmap information of the Link1 Scoreboard is updated based on the Common Scoreboard. Therefore, at time T7 when data transmission from STA2 on Link1 ends, the Link1 Scoreboard stores bitmap information regarding whether or not STA2 successfully acquired packets with SN#1 to #64 transmitted from STA2 on Link1 and Link2 (i.e., information on whether or not STA2 successfully acquired the sender and TID that completed transmission). Therefore, the AP can transmit a Common Block Ack to STA2 on Link1 based on the bitmap information stored in the Link1 Scoreboard, following the Block Ack transmission procedure shown in FIG. 28.

[0225] Also, STA1 acquires the transmission right for Link2 at time T6. That is, at time T6, the transmitter of Link2 changes from STA2 to STA1. STA1 starts transmitting a data signal that aggregates packets with SNs #33 to #64 with the same TID as Link1, and completes transmission of this aggregated data signal at time T8. After time T6, the Link1 Scoreboard stores bitmap information regarding whether or not packets with SNs #33 to #64 transmitted from STA1 were successfully acquired, and this information is updated sequentially.

[0226] At this point, the Common Scoreboard manages the bitmap information of STA1, which is the same sender as the Link2 Scoreboard, and therefore the bitmap information of the Link2 Scoreboard is updated based on the Common Scoreboard. As a result, at time T8 when data transmission on Link1 from STA2 ends, the Link2 Scoreboard stores bitmap information regarding whether or not packets with SN#1 to #64 transmitted from STA1 on Link1 and Link2 were successfully acquired (i.e., information on whether or not the sender that completed transmission and the TID were successfully acquired). Therefore, the AP can transmit a Common Block Ack to STA1 on Link2 based on the bitmap information stored in the Link2 Scoreboard, following the Block Ack transmission procedure shown in FIG. 28.

[0227] G.Effect In this section, the effects obtained by the present disclosure will be summarized.

[0228] (1) An MLO-compatible communication device to which the present disclosure is applied is equipped with a Link Scoreboard that manages information on whether or not received packets were successfully acquired for each link, and a Common Scoreboard that manages information on whether or not received packets were successfully acquired for multiple links. The Common Scoreboard is managed using a cache system, but it can transmit Common Block Acks containing information on whether or not received packets were successfully acquired for multiple links with high reliability, and the Common Scoreboard can be implemented using inexpensive memory.

[0229] (2) A communication device to which the present disclosure is applied exchanges Capability information indicating whether it is possible to manage information on whether or not a packet received from multiple links is successfully acquired using the Common Scoreboard with other communication devices. Therefore, a data sender can determine whether or not a Common Block Ack can be generated on the receiving side and set an Ack Policy correctly.

[0230] (3) According to the present disclosure, the data sender sends a Block Ack Request with additional information indicating whether to update the Common Scoreboard. Therefore, the receiving side can update the Common Scoreboard at the same time as updating the Link Scoreboard.

[0231] (4) An MLO-compatible communication device to which the present disclosure is applied updates the Link Scoreboard based on information in the Common Scoreboard, and is therefore able to generate and transmit Common Block Acks even in situations where multiple data senders alternately transmit data using multiple links. [Industrial Applicability]

[0232] Although the present disclosure has been described in detail above with reference to specific embodiments, it is obvious that those skilled in the art can make modifications or substitutions to the embodiments without departing from the spirit and scope of the present disclosure.

[0233] For example, by applying the present disclosure to a wireless LAN system conforming to the IEEE802.11 standard, it is possible to achieve the same effect by applying the present disclosure to a wireless system that performs multi-link communication conforming to other communication standards.

[0234] In short, the present disclosure has been described in the form of examples, and the contents of the specification should not be interpreted as limiting. To determine the gist of the present disclosure, the claims should be taken into consideration.

[0235] The present disclosure may also be configured as follows.

[0236] (1) A communication device that performs wireless communication using multiple links, a common data processing unit having a cache-type common storage unit that stores whether packets received via a plurality of links have been successfully acquired and that performs common data processing on packets received via each link; a control unit that controls transmission of a response signal in response to a received packet; Equipped with the control unit generates a common response signal including the acquisition success / failure information received through the plurality of links based on the acquisition success / failure information stored in the common storage unit. Communication equipment.

[0237] (2) An individual storage unit is provided for storing information on whether or not packets received through each link have been successfully acquired, and an individual data processing unit is further provided for performing individual data processing on packets received through each link. The communication device according to (1) above.

[0238] (3) The control unit performs an update process on the common storage unit based on acquisition success / failure information related to the same sender information stored in the common storage unit and the individual storage unit. The communication device according to (2) above.

[0239] (4) When the individual storage unit stores acquisition success / failure information related to the same sender information as the common storage unit, the control unit performs an update process on the common storage unit based on the acquisition success / failure information related to the same sender information stored in the individual storage unit. The communication device according to (3) above.

[0240] (5) When the individual storage unit does not store acquisition success / failure information regarding the same sender information as the common storage unit, but each individual storage unit of a plurality of links stores acquisition success / failure information regarding the same sender information, the control unit performs an update process of the common storage unit based on the acquisition success / failure information regarding the same sender information stored in each individual storage unit of the plurality of links. A communication device according to either (3) or (4) above.

[0241] (6) the control unit performs an update process on the common storage unit in accordance with the larger final value of the sequence number stored in each individual storage unit of the plurality of links; The communication device according to (5) above.

[0242] (7) The control unit sets a value indicating successful acquisition in the acquisition success / non-success information of the common storage unit for a sequence number that is indicated as having been successfully acquired in at least one of the individual storage units of the plurality of links. A communication device according to either (5) or (6) above.

[0243] (8) The control unit controls the exchange of information regarding whether the common storage unit can be managed with the sender of the packet. A communication device according to any one of (1) to (7) above.

[0244] (9) The control unit attempts to update the common storage unit when it has been confirmed with the sender that the common storage unit is manageable and the header of the received data signal requests transmission of the common response signal. The communication device according to (8) above.

[0245] (10) The control unit determines whether to generate the common signal based on sender information managed by the common storage unit. A communication device according to any one of (1) to (9) above.

[0246] (11) When the common storage unit stores acquisition success / failure information relating to the same sender information as the packet whose reception has been completed, the control unit generates the common response signal based on the acquisition success / failure information stored in the common storage unit, but when the common storage unit does not store acquisition success / failure information relating to the same sender information as the packet whose reception has been completed, the control unit generates the individual response signal based on acquisition success / failure information stored in the individual storage unit of the link that received the packet. The communication device according to (10) above.

[0247] (12) The control unit determines whether to update the common storage unit based on information included in a response request signal received from a sender. A communication device according to any one of (1) to (11) above.

[0248] (13) The control unit performs an update process on the individual storage unit based on acquisition success / failure information related to the same sender information stored in the common storage unit and the individual storage unit. The communication device according to (2) above.

[0249] (14) A communication method for wireless communication using a plurality of links, a common data processing step of performing common data processing on packets received through each link using a cache-type common storage unit that stores whether packets received through a plurality of links have been successfully acquired; a control step of controlling transmission of a response signal in response to the received packet; and In the control step, a common response signal including the acquisition success / failure information received through the plurality of links is generated based on the acquisition success / failure information stored in the common storage unit. Communication method.

[0250] (15) a communication unit that performs wireless communication using a plurality of links; a control unit that controls wireless communication operations in the communication unit; Equipped with the control unit notifies whether or not a common response signal including acquisition success information regarding reception of the data signals on the plurality of links is requested when transmitting the data signals on the plurality of links; Communication equipment.

[0251] (16) The control unit controls to transmit a response request signal requesting transmission of the common response signal. The communication device according to (15) above.

[0252] (17) The control unit controls to transmit the response request signal in order to initialize a common storage unit that stores acquisition success / failure information regarding reception of data signals on the plurality of links. The communication device according to (16) above.

[0253] (18) A communication method for wireless communication using a plurality of links, a step of notifying whether or not a common response signal including acquisition success information regarding reception of the data signals on the plurality of links is required, and transmitting the data signals; receiving a response signal; A communication method comprising: [Explanation of symbols]

[0254] 200... communication device, 210... communication unit, 211... communication control unit 212...communication storage unit, 213...common data processing unit 214... individual data processing unit, 215... signal processing unit 216...wireless interface unit, 217...amplifier unit, 220...control unit 230...storage unit, 240...antenna

Claims

[Claim 1] A communication device that performs wireless communication using a plurality of links, a cache-type common storage unit that stores whether packets received via the plurality of links have been successfully acquired; an individual storage unit that stores information on whether or not a packet received through each link has been successfully acquired; a control unit that controls transmission of a response signal in response to a received packet; Equipped with The control unit performing an update process on the common storage unit based on acquisition success / failure information related to the same sender information stored in the common storage unit and the individual storage unit; generating a common response signal including the acquisition success / failure information received through the plurality of links based on the acquisition success / failure information stored in the common storage unit; The same sender information is a combination of a sender address and a traffic identifier. Communication equipment.

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