Communication device, control method, and program

Abstract

To prevent transmission and reception from being performed in parallel in a communication device.SOLUTION: A communication device performs communications in conformity with IEEE 802.11 standard series together with the other device by use of a plurality of radio links. When a predetermined frame serving as a group address frame is transmitted via a first radio link included in the plurality of radio links, the communication device performs a control such that any frame addressed to the communication device does not come thereto via a second radio link included in the plurality of radio links and different from the first radio link.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a communication control technique that takes into account communication devices with operational constraints. [Background technology]

[0002] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard is known as a communication standard for wireless local area networks (WLANs). The IEEE 802.11 standard is a series of standards including the IEEE 802.11a / b / g / n / ac / ax standards. Patent Document 1 describes that the IEEE 802.11ax standard performs communication using Orthogonal Frequency Division Multiple Access (OFDMA). Wireless communication using OFDMA can achieve high peak throughput and ensure sufficient communication speed even in congested situations.

[0003] To further improve throughput, the IEEE 802.11be standard is currently being developed as a new standard in the IEEE 802.11 series. The IEEE 802.11be standard considers multi-link communication, in which an access point (AP) establishes multiple wireless links with a station (STA) over one or more frequency bands. In multi-link communication, for example, an AP establishes a connection with a STA over multiple frequency channels in at least one of the 2.4 GHz, 5 GHz, and 6 GHz frequency bands, and communicates in parallel over each frequency channel. Due to hardware limitations, some APs or STAs may be capable of multi-link communication but may be unable to receive over a given link while transmitting over another link. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-050133 Summary of the Invention [Problem to be solved by the invention]

[0005] An AP performing multi-link communication must periodically transmit beacons on each link. However, if an AP is a device that cannot receive data on one link while transmitting data on another link, the AP cannot transmit beacons on the other link while receiving data on the other link. In addition to beacons, an AP may need to transmit group address frames that transmit information collectively to multiple devices, but such frames may not be transmitted for the same reason. Even if the timing at which an AP transmits a beacon on a given link is predetermined, the timing of the beacon transmission may be delayed depending on the degree of congestion on that link. In such cases, the AP still operates under the constraint that it cannot receive data on the other link while transmitting data on the given link.

[0006] The present invention provides a communication control technique for preventing transmission and reception from occurring in parallel in a communication device. [Means for solving the problem]

[0007] A communication device according to one embodiment of the present invention comprises a communication means for communicating with a counterpart device in accordance with the IEEE 802.11 standard series using a plurality of wireless links, and a control means for controlling the communication means so that, when a predetermined frame which is a group address frame is transmitted on a first wireless link among the plurality of wireless links, a frame addressed to the communication device does not arrive on a second wireless link among the plurality of wireless links which is different from the first wireless link. [Effects of the Invention]

[0008] According to the present invention, it is possible to prevent transmission and reception from being performed in parallel in a communication device. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Figure 2] FIG. 2 illustrates an example of a hardware configuration of a communication device. [Figure 3] FIG. 2 illustrates an example of a functional configuration of a communication device. [Figure 4] FIG. 10 is a diagram illustrating an example of a flow of processing executed by an access point. [Figure 5] FIG. 1 is a diagram illustrating an example of a communication flow in a wireless communication system. [Figure 6] FIG. 10 is a diagram illustrating an example of a flow of processing executed by an access point. [Figure 7] FIG. 1 is a diagram illustrating an example of a communication flow in a wireless communication system. [Figure 8] FIG. 10 is a diagram illustrating an example of a flow of processing executed by an access point. [Figure 9] FIG. 1 is a diagram illustrating an example of a communication flow in a wireless communication system. [Figure 10] FIG. 1 is a diagram illustrating an example of a communication flow in a wireless communication system. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0011] (Configuration of wireless communication system) FIG. 1 shows an example of the configuration of a wireless communication system according to this embodiment. The wireless communication system includes a plurality of communication devices, which communicate by transmitting and receiving wireless signals to and from each other. In one example of the wireless communication system, an access point (AP102) forms a network 101, and a station (STA103) participates in the network 101. The STA103 participates in the network 101 and can communicate with the AP102. FIG. 1 also shows a situation in which there is a STA106 that is not participating in the network 101. The STA106 cannot communicate with the AP102, but is affected by interference from signals from the AP102, and is located in a position where its transmitted signals interfere with the communication of the AP102.

[0012] Here, the AP 102 and the STA 103 are each configured to be able to perform wireless communication compliant with the IEEE (Institute of Electrical and Electronics Engineers) 802.11be (EHT) standard. The AP 102 and the STA 103 may also support legacy standards that predate the IEEE 802.11be standard. For example, the AP 102 and the STA 103 may be configured to support at least one of the IEEE 802.11a / b / g / n / ac / ax standards. The AP 102 and the STA 103 may also support other communication standards, such as Bluetooth (registered trademark), NFC, UWB, ZigBee, and MBOA, in addition to the IEEE 802.11 standard series. NFC, UWB, and MBOA are acronyms for Near Field Communication, Ultra Wide Band, and Multi-Band OFDM Alliance, respectively. UWB includes wireless USB, wireless 1394, WiNET, and the like. The AP 102 and the STA 103 may also support a communication standard for wired communication, such as a wired LAN. The AP 102 may be, for example, a wireless LAN router or a personal computer (PC), but is not limited to these. The AP 102 may also be an information processing device, such as a wireless chip, capable of performing wireless communication in accordance with the IEEE 802.11be standard. The STA 103 may be, for example, a camera, a tablet, a smartphone, a PC, a mobile phone, a video camera, a headset, but is not limited to these. The STA 103 may also be an information processing device, such as a wireless chip, capable of performing wireless communication in accordance with the IEEE 802.11be standard.

[0013] The AP 102 and the STA 103 can communicate in frequency bands of, for example, 2.4 GHz, 5 GHz, and 6 GHz. Note that these frequency bands are merely examples, and the AP 102 and the STA 103 may be able to use other frequency bands, such as the 60 GHz band. The AP 102 and the STA 103 can also communicate using a bandwidth of 20 MHz, 40 MHz, 80 MHz, 160 MHz, or 320 MHz. Note that this is merely an example, and the AP 102 and the STA 103 may be configured to be able to communicate using a different bandwidth, such as 240 MHz or 4 MHz.

[0014] The AP 102 and the STAs 103 can perform multi-user (MU) communication in which signals from multiple users are multiplexed by performing OFDMA (Orthogonal Frequency Division Multiple Access) communication in accordance with the IEEE 802.11be standard. In OFDMA communication, the available frequency band is divided into resource units (RUs), and non-overlapping frequency resources are assigned to each STA on an RU basis. Note that subcarriers in an RU are configured to be orthogonal to subcarriers in other RUs. This allows the AP 102 to communicate with multiple STAs in parallel within a specified bandwidth.

[0015] The AP 102 and the STA 103 are also capable of establishing multiple wireless links via multiple frequency channels, and are configured to perform multi-link communication, communicating via one or more wireless links. Hereinafter, a wireless link is simply referred to as a "link." The IEEE 802.11 standard series defines the bandwidth of each frequency channel as 20 MHz. The "frequency channel" here refers to a frequency channel defined in the IEEE 802.11 standard series. The IEEE 802.11 standard series defines multiple frequency channels in each of the 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz frequency bands. The IEEE 802.11 standard series also allows for a 40 MHz bandwidth to be used in one frequency channel by bonding two adjacent frequency channels. Similarly, four frequency channels can be bonded to use an 80 MHz bandwidth, and eight frequency channels can be bonded to use a 160 MHz bandwidth. It is also possible to use a 320 MHz bandwidth by bonding 16 frequency channels together, or by using two 160 MHz bandwidths, for example.

[0016] In this embodiment, as an example, the AP 102 communicates with the STA 103 by establishing a link 104 via a first frequency channel in the 2.4 GHz band and a link 105 via a second frequency channel in the 6 GHz band. The AP 102 and the STA 103 may perform multi-link communication, maintaining the link 104 via the first frequency channel and the second link 105 via the second frequency channel in parallel. This allows the AP 102 and the STA 103 to improve communication throughput by using links via multiple frequency channels. In this embodiment, the link 104 is established on channel 6 in the 2.4 GHz band with a 20 MHz bandwidth, and the link number of this link 104 is set to "1." Furthermore, the link 105 is established on channel 113 in the 6 GHz band with a 320 MHz bandwidth, and the link number of this link 105 is set to "2."

[0017] Note that multilink communication may use links established in different frequency bands, or at least some of the multiple links may be established in a common frequency band. For example, multilink communication may be performed between the AP 102 and the STA 103 by establishing one link each in the 2.4 GHz band, the 5 GHz band, and the 6 GHz band. Alternatively, separate links may be established between the AP 102 and the STA 103 on channels 1 and 6 in the 2.4 GHz band, and multilink communication may be performed using these links. Alternatively, two or more links may be established between the AP 102 and the STA 103 in the 2.4 GHz band, and one or more links may be established in the 5 GHz band or the 6 GHz band, and multilink communication may be performed using these links. In other words, multilink communication establishes links using two or more of multiple frequency channels defined in multiple frequency bands, but the frequency channels of the two or more links may be any as long as they do not overlap with each other. By establishing multiple links on different frequency channels, AP102 and STA103 can continue communication on other frequency bands even when one frequency band is congested, thereby preventing a decrease in throughput and communication delays.

[0018] When performing multi-link communication, the AP 102 and the STA 103 divide a single piece of data and transmit it to a partner device via multiple links. The AP 102 and the STA 103 may also be capable of MIMO (Multiple-Input Multiple-Output) communication on each link. In this case, the AP 102 and the STA 103 have multiple antennas, and the transmitting device transmits multiple data streams in parallel from the multiple transmitting antennas on the same frequency channel. The receiving device receives multiple signals in parallel from the multiple transmitting antennas using multiple receiving antennas, and separates and decodes the multiple data streams from the signals. In this way, the AP 102 and the STA 103 can transmit and receive more data using common time and frequency resources through MIMO communication. When performing multi-link communication, the AP 102 and the STA 103 may also perform MIMO communication on only some of the links.

[0019] 1 shows a system configuration including one AP 102, one STA 103 connected to the AP 102, and one STA 106 that is not connected to the AP 102, but the number and arrangement of the APs and STAs are not limited to these. For example, one or more STAs may be added that connect to the AP 102. In this case, the frequency band of the link established with this STA, the number of links, and the bandwidth may be set arbitrarily.

[0020] The STA 106 may be any device that operates on a specific link established between the AP 102 and the STA 103 without considering other links. For example, although the STA 106 is not described as participating in the network 101, it may also participate in the network 101. In this case, the STA 106 may not comply with IEEE 802.11be but may comply only with IEEE 802.11b. In this case, the STA 106 may establish a link with the AP 102 on channel 6 in the 2.4 GHz band. The STA 106 may also be a wireless communication device that does not comply with the IEEE 802.11 standard series or a noise source that generates radio noise other than a communication device, such as a microwave oven. The STA 106 may also be a communication device that supports multi-link communication and may be configured to establish and communicate with the AP 102 via multiple links. In either case, the STA 106 may ignore operation on a specific link and communicate on other links.

[0021] (Device configuration) 2 is a diagram illustrating an example of the hardware configuration of the AP 102 according to this embodiment. The AP 102 includes, for example, a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207. The STA 103 may also have a similar configuration.

[0022] The storage unit 201 is configured to include one or more memories such as ROM and RAM, and stores various information such as computer programs for performing various operations described below and communication parameters for wireless communication. ROM is an acronym for Read Only Memory, and RAM is an acronym for Random Access Memory. The storage unit 201 may include storage media such as a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a non-volatile memory card, a DVD, etc., in addition to or instead of memories such as ROM and RAM. The storage unit 201 may also include multiple memories.

[0023] The control unit 202 is configured with one or more processors, such as a CPU or an MPU, and controls the entire AP 102 by executing a computer program stored in the storage unit 201, for example. Note that CPU is an acronym for Central Processing Unit, and MPU is an acronym for Micro Processing Unit. The control unit 202 may be configured to perform processes for generating data and signals (radio frames) to be transmitted in communication with other communication devices (e.g., the STA 103) in addition to the overall control of the AP 102. Note that the control unit 202 may be configured to perform processes such as the overall control of the AP 102 in cooperation with a computer program stored in the storage unit 201 and an OS (Operating System). The control unit 202 may also include multiple processors, such as a multi-core processor, and perform processes such as the overall control of the AP 102 using the multiple processors. The control unit 202 may also be configured with an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or the like.

[0024] Furthermore, the control unit 202 controls the functional unit 203 to execute predetermined processes such as capturing images, printing, and projection. The functional unit 203 is hardware that causes the AP 102 to execute predetermined processes. For example, if the AP 102 is a camera, the functional unit 203 is an imaging unit that performs imaging processing. For example, if the AP 102 is a printer, the functional unit 203 is a printing unit that performs printing processing. For example, if the AP 102 is a projector, the functional unit 203 is a projection unit that performs projection processing. The data processed by the functional unit 203 may be data stored in the storage unit 201, or may be data communicated with another communication device (e.g., STA 103) via the communication unit 206, which will be described later.

[0025] The input unit 204 receives various operations from the user. The output unit 205 outputs various types of information to the user. Here, the output by the output unit 205 includes, for example, at least one of a display on a screen, an audio output from a speaker, and a vibration output. Note that both the input unit 204 and the output unit 205 may be implemented by a single module, such as a touch panel. Furthermore, the input unit 204 and the output unit 205 may each be built into the AP 102, or may be configured as an external device connected to a communication device.

[0026] The communication unit 206 controls wireless communication compliant with the IEEE 802.11 series of standards and IP communication. In this embodiment, the communication unit 206 is configured to control wireless communication compliant with the IEEE 802.11be standard in particular. The communication unit 206 controls the antenna 207 to transmit and receive signals for wireless communication generated by the control unit 202, for example. If the AP 102 supports standards such as the NFC standard and Bluetooth, the communication unit 206 can also control wireless communication compliant with these standards. If the AP 102 is configured to be able to perform wireless communication compliant with multiple communication standards, separate communication units 206 and antennas 207 corresponding to each communication standard may be provided. The AP 102 communicates data such as image data, document data, and video data with a communication partner device (e.g., the STA 103) via the communication unit 206. The antenna 207 may be provided separately from the communication unit 206, or may be configured as a single module together with the communication unit 206.

[0027] Antenna 207 is an antenna capable of communication in the sub-GHz band, 2.4 GHz band, 5 GHz band, and 6 GHz band. Note that AP 102 may have a multi-band antenna as antenna 207, or may have multiple antennas corresponding to each frequency band. If AP 102 has multiple antennas 207, it may have one communication unit 206 for the multiple antennas, or multiple communication units 206 corresponding to each of the multiple antennas 207. Note that antenna 207 may be a single antenna or an antenna array. That is, antenna 207 may have multiple antenna elements and be configured to be able to perform multi-antenna communication such as MIMO.

[0028] 3 shows an example of the functional configuration of the AP 102. The STA 103 may also have a similar functional configuration. The functional units shown in FIG. 3 include a wireless LAN control unit 301, a frame generation unit 302, a transmission time control unit 303, a beacon control unit 304, a UI control unit 305, and a memory control unit 306.

[0029] The wireless LAN control unit 301 executes control for transmitting and receiving wireless signals to and from other wireless LAN communication devices. The wireless LAN control unit 301 executes wireless LAN communication control based on frames generated by the frame generation unit 302 in accordance with procedures defined in the IEEE 802.11 standard series. Note that the AP 102 may have two or more wireless LAN control units 301, for example, for each frequency band or each link.

[0030] Frame generation unit 302 generates a wireless control frame to be transmitted to another device under the control of wireless LAN control unit 301. The content of the wireless control frame generated by frame generation unit 302 may be restricted based on the setting information stored in storage unit 201. Furthermore, the content of the wireless control frame generated by frame generation unit 302 may be changed based on user settings received via UI control unit 305. The generated wireless control frame is transmitted to the other device via communication unit 206 under the control of wireless LAN control unit 301.

[0031] The transmission time control unit 303 outputs an instruction as to when to transmit the frame, in accordance with the time interval acquired from the beacon control unit 304. The wireless LAN control unit 301 controls the communication unit 206 to transmit the frame generated by the frame generation unit 302, in accordance with the instruction from the transmission time control unit 303.

[0032] The beacon control unit 304 outputs instructions regarding the timing of transmitting a beacon and information to be included in the beacon to the frame generation unit 302 and the transmission time control unit 303. When the AP 102 starts operating as an AP, the beacon control unit 304 outputs setting information for the time interval for periodically transmitting a beacon to the transmission time control unit 303. The transmission time control unit 303 can output an instruction to transmit a beacon to the wireless LAN control unit 301 at the time interval based on the setting information. Furthermore, when the transmission time control unit 303 outputs an instruction to transmit a beacon, the beacon control unit 304 outputs an instruction regarding information to be included in the beacon to the frame generation unit 302. Based on this instruction, the frame generation unit 302 acquires information from the memory unit 201 via the memory control unit 306 and generates a beacon based on the acquired information.

[0033] The UI control unit 305 controls the input unit 204 to accept operations on the AP 102 by a user (not shown), and controls the output unit 205 to present information such as image display and audio output to the user. The memory control unit 306 executes control processes such as storing data in the memory unit 201 and reading out data stored in the memory unit 201.

[0034] (Communication flow) Next, an example of the flow of communication when AP 102 communicates with one or more STAs such as STA 103 will be described. Note that, although the following description will be given assuming that the other device in communication with AP 102 is STA 103, AP 102 can communicate in parallel with multiple STAs including STA 103.

[0035] In this embodiment, the description focuses on a situation in which AP 102 transmits a group address frame over link 104 and link 105 established with STA 103. A group address frame is a frame that is mainly used when transmitting simultaneously to multiple STAs. In a group address frame, an address with a Group Bit of 1 is set in the MAC Address included in the Destination Address (DA) or A1 field. For example, a beacon is a frame that is transmitted by broadcast, and in this case the Group Bit is set to 1. Therefore, a beacon is a group address frame. A multicast address is also a group address frame because the Group Bit is similarly set to 1.

[0036] In this embodiment, as described above, while the AP 102 is transmitting a signal on either link 104 or link 105, it cannot receive a signal on the other link. Meanwhile, it is assumed that the AP 102 needs to transmit a beacon on each frequency channel (each link). Therefore, the following processes prevent signals addressed to the AP 102 from being transmitted from surrounding STAs or other APs on the frequency channel of another link while the AP 102 is transmitting a beacon (group address frame) on one link. An example of such a process flow will be described below. Note that a beacon is just one example, and similar processes can be performed when transmitting any group address frame. The following processes can also be applied to cases where a predetermined signal, the transmission timing of which is determined in advance, such as at a predetermined interval, is to be transmitted. That is, the following processes can be applied when any predetermined frame (which may be a unicast frame) with a predetermined transmission timing is present on any link.

[0037] Note that, although the following describes an example in which the AP 102 attempts to transmit a beacon (group address frame) on all established links, the present invention is not limited to this. That is, the AP 102 may perform the following process on two or more links that are part of the multiple established links. For example, such process may be performed when it is necessary to transmit a group address frame such as a beacon only on some of the links, and such transmission is not necessary on other frames. In this case, for example, while the AP 102 is transmitting frames on some of the links, it may ignore frames arriving on the other links.

[0038] In addition, although an example of transmitting a beacon will be described below, the following discussion can be applied to the transmission of any group address frame or a multicast frame addressed to a multicast address. For example, the beacon in the following description may be replaced with a FILS Discovery frame or an Unsolicited Probe Response frame. Note that a FILS Discovery frame is a frame that is transmitted at intervals of 20 TU between beacons. Here, TU is an acronym for Time Unit, and 1 TU is 1024 microseconds. The beacon in the following description may be replaced with other management frames, such as a Probe Response frame or an Action frame.

[0039] (Processing example 1) In this processing example, it is assumed that AP 102 attempts to transmit beacons in parallel at the same timing (at times when at least a part of the transmission periods overlap) on both link 104 and link 105. It is to be noted that AP 102 does not necessarily have to transmit beacons simultaneously on link 104 and link 105, and it is assumed that AP 102 is allowed to transmit beacons on link 104 and link 105 at different timings.

[0040] 4 shows an example of the flow of processing executed by AP 102 in the first processing example. The processing in FIG. 4 is started, for example, when AP 102 starts operating as an AP. Note that the processing in FIG. 4 can be realized, for example, by the control unit 202 of AP 102 executing a program stored in the storage unit 201 of AP 102. However, this is not limiting, and for example, some or all of the processing in FIG. 4 may be realized by dedicated hardware. Furthermore, the processing in FIG. 4 is one example, and unless otherwise specified, the order of each processing may be changed, some of the processing may be omitted, or the processing may be replaced with other similar processing.

[0041] In this process, the AP 102 first waits until the timing at which a beacon should be transmitted (hereinafter referred to as the beacon transmission time) (S401). This beacon transmission time can be determined based on, for example, a setting value of the transmission interval stored in the storage unit 201. When the beacon transmission time arrives (YES in S401), the AP 102 executes beacon transmission processing on all of the multiple established links (S402). Note that the beacon transmission time may be a predetermined timing prior to the timing at which the beacon should actually be transmitted (Target Beacon Transmission Time, TBTT). The AP 102 may then start preparing to transmit the beacon at the predetermined timing and execute processing so that it can start transmitting the beacon at the TBTT. The AP 102 then attempts to transmit the beacon on all of the links at the timing at which the beacon should be transmitted while observing the link status. The AP 102 then determines whether any of the multiple established links is in a state where a beacon cannot be transmitted due to, for example, channel congestion (S403). For example, if STA 106 is transmitting data to another AP on the same frequency channel as link 104 or link 105 and the TBTT arrives during the data transmission period, AP 102 determines that it cannot transmit a beacon on the link of that frequency channel. In this situation, AP 102 will transmit the beacon at a different timing.

[0042] If the AP 102 is unable to transmit a beacon on any link and determines that the beacon timing has shifted (YES in S403), it also transmits a signal on another link during the beacon transmission period on the link with the shifted transmission timing. In this processing example, the AP 102 first determines whether there is an additional group address frame to be transmitted following the beacon transmission (S404). If the additional group address frame can be transmitted on a second link different from the first link with the shifted transmission timing, the AP 102 transmits the additional group address frame on the second link during the beacon transmission period on the first link. In this case, it is possible that the beacon transmission on the first link is completed during the transmission of the additional group address frame on the second link, and then another AP or a surrounding STA may transmit a frame addressed to the AP 102. Therefore, in such a case, the AP 102 may prevent the transmission of a signal addressed to the AP 102 on the first link, even during the transmission of a group address frame on the second link.

[0043] If the AP 102 determines that an additional group address frame exists (YES in S404), it determines whether the group address frame should be transmitted on all links (S405). If the AP 102 determines that the additional group address frame should be transmitted on all links (YES in S405), it performs an adjustment process to ensure that the transmission of the frame is completed simultaneously (or approximately simultaneously) on all links (S406). This adjustment process can be performed, for example, by additionally transmitting another frame, such as an empty frame, or by adding padding bits to the end of the data of a frame whose frame length is short and whose transmission is completed quickly. Furthermore, in the adjustment process, the AP 102 may also perform a process to transmit an additional group address frame scheduled to be transmitted in the next beacon on other links in accordance with the transmission period of the additional group address frame to be transmitted on a specific link. Furthermore, in the adjustment process, the AP 102 may also transmit a duplicate frame of the additional group address frame on other links in accordance with the transmission period of the additional group address frame to be transmitted on a specific link.

[0044] Furthermore, the AP 102 may reserve a transmission opportunity (TXOP) on another link while transmitting a beacon or an additional group address frame on a given link. By reserving a TXOP, the AP 102 can prevent other STAs from transmitting frames. The AP 102 can reserve a TXOP, for example, by sending a Clear-To-Send (CTS)-to-self on another link. The CTS-to-self is a CTS sent to the sender itself. Upon receiving the CTS-to-self, STAs around the AP 102 and other APs cannot transmit frames during the period specified in the CTS-to-self. This prevents other devices from transmitting data to the AP 102 while the AP 102 is transmitting an additional group address frame when the AP 102 cannot transmit and receive data in parallel.

[0045] On the other hand, if it is determined in S405 that the AP 102 will not transmit the additional group address frame on all links (NO in S405), the AP 102 performs processing to align the transmission end times on all links (S407). For example, the AP 102 may transmit a frame similar to the additional group address frame or an empty group address frame on a link other than the link on which the additional group address frame is scheduled to be transmitted. Furthermore, the AP 102 may transmit a CTS-to-self on a link on which the AP 102 does not plan to transmit the additional group address frame to secure a TXOP, as described in relation to S406. Furthermore, the AP 102 may transmit a unicast frame with its own MAC address or source MAC address set as the destination on another link. Furthermore, the AP 102 may execute the processing of S407 by transmitting a control frame, an action frame, or a data frame, including a management frame, a trigger frame, or an Ack frame related to the connection. At this time, by specifying a value in the Duration field in the transmitted frame, the TXOP can be secured for the specified period. However, this is just an example, and the TXOP may be reserved using a field or subfield different from the Duration field. Note that the AP 102 may reserve the TXOP in advance using an RTS frame or a CTS-to-self frame, for example, before transmitting a beacon, rather than when transmitting an additional group address frame.

[0046] Furthermore, if the AP 102 determines in S404 that there is no additional group address frame (NO in S404), when transmitting a beacon on a link with a shifted beacon transmission timing, the AP 102 also transmits a frame on another link (S408). Note that the AP 102 does not need to transmit a frame if the other link on which the beacon is not transmitted is in a NAV (Network Allocation Vector) period. Here, for example, a unicast frame to be transmitted to a connected STA, a group address frame, an RTS (Request-To-Send) frame, a FILS Discovery frame, or the like may be transmitted. Alternatively, empty data may be transmitted, or a unicast frame whose destination is set to the MAC address or source MAC address of the AP 102 itself on that link may be transmitted.

[0047] If the AP 102 determines that the beacon timing is not off on each link (NO in S403), it determines whether to transmit an additional group address frame (S409). If the AP 102 determines not to transmit an additional group address frame (NO in S409), it transmits beacons with the same transmission period on each link (S413) and ends the process. On the other hand, if the AP 102 determines to transmit an additional group address frame (YES in S409), it determines whether to transmit the additional group address frame on all links (S410). If the AP 102 determines to transmit the additional group address frame on all links (YES in S410), it transmits the additional group address frame with the same transmission period on each link (S412). On the other hand, if the AP 102 determines to transmit the additional group address frame on only some links (NO in S410), it reserves TXOPs on the links on which it will not transmit the group address frame (S411). This allows the AP 102 to prevent signals addressed to the AP 102 from being transmitted from other devices on one link while additional group address frames are being transmitted on another link.

[0048] An example of the communication flow when AP 102 operates based on the process of Figure 4 is shown in Figure 5. Here, it is assumed that AP 102 transmits an additional group address frame following a beacon on both link 104 and link 105. Here, it is assumed that the timing of the beacon transmission on link 105 has shifted due to channel congestion.

[0049] In one example, it is assumed that a beacon should be transmitted at timing 531 after AP 102 receives a frame from STA 103 during period 511. At this time, it is assumed that AP 102 was able to transmit beacon 512 as scheduled on link 104. Meanwhile, it is assumed that link 105 is in NAV period 521, for example, because STA 106 is transmitting a data frame to another AP. At timing 532 after the NAV period ends, AP 102 is able to transmit beacon 522 on link 105 as well. At this time, after transmitting beacon 512 on link 104, AP 102 transmits additional group address frame 513, and is now transmitting frames in parallel on links 104 and 105. Then, after transmitting beacon 522 on link 105, AP 102 transmits additional group address frame 523.

[0050] Here, the transmission end timings of group address frame 513 of link 104 and group address frame 523 of link 105 are different. Therefore, AP 102 reserves TXOP 514 in link 104, for example, by one of the methods described above, in accordance with end timing 533 of group address frame 523 of link 105, which has the later transmission end timing. This allows AP 102 to reserve transmission rights for all links, preventing a situation in which AP 102 has to transmit frames on one link while receiving frames on another link.

[0051] In this process example, the AP 102 can transmit data to a specific STA during the time when the TXOP is reserved. This allows the AP 102 to efficiently use frequency resources while preventing simultaneous transmission and reception. Furthermore, the AP 102 can select an available link to transmit a beacon even if some links are unavailable for reasons unrelated to wireless communication, such as interference from a microwave oven.

[0052] Note that, when the timing of a beacon is shifted, as in link 105 of FIG. 5, the opportunity to transmit the next beacon after the shifted beacon is transmitted can be determined based on the timing and period at which the beacon should originally be transmitted. For example, assume that the beacon transmission period is 100 TU, and a beacon is first transmitted at 0 TU, and then the timing is shifted and the beacon is transmitted at 110 TU. In this case, the transmission timing of the next beacon can be determined to be 200 TU, based on the original transmission timing of 100 TU. Note that this is just one example, and the beacon transmission timing can be determined based on other criteria. For example, in the above example, based on the shifted timing, it can be determined that the next beacon will be transmitted at 210 TU.

[0053] (Processing example 2) In this processing example, it is assumed that AP 102 attempts to transmit beacons in parallel at the same timing (at times when at least a part of the transmission periods overlap) on both link 104 and link 105. Note that in this processing example, AP 102 does not necessarily have to transmit beacons simultaneously on link 104 and link 105, and is permitted to transmit beacons on link 104 and link 105 at different timings.

[0054] 6 shows an example of the flow of processing executed by AP 102 in the second processing example. The processing in FIG. 6 is started, for example, when AP 102 starts operating as an AP. Note that the processing in FIG. 6 can be realized, for example, by the control unit 202 of AP 102 executing a program stored in the storage unit 201 of AP 102. However, this is not limiting, and for example, some or all of the processing in FIG. 6 may be realized by dedicated hardware. Furthermore, the processing in FIG. 6 is one example, and unless otherwise specified, the order of each processing may be changed, some of the processing may be omitted, or the processing may be replaced with other similar processing.

[0055] In this process, the AP 102 first waits until it is time to transmit a beacon (S601). When it is time to transmit a beacon (YES in S601), it confirms that each link is not busy (S602, S603). The AP 102 determines that a link is busy when another wireless communication device is transmitting data on a frequency channel used by the link or when a TXOP is secured and the link is in the NAV state. When the AP 102 determines that all links are not busy (NO in S602, NO in S603), it transmits beacons on all of those links (S604). In one example, the AP 102 may measure the elapsed time from the time when it should transmit a beacon, and if any link remains busy until the elapsed time reaches a predetermined timeout time, it may terminate this process without transmitting a beacon.

[0056] After transmitting the beacon, the AP 102 determines whether to transmit an additional group address frame (S605). If the AP 102 does not transmit the additional group address frame (NO in S605), the AP 102 aligns the beacon transmission periods and transmits the frames (S609), and ends the process. On the other hand, if the AP 102 transmits the additional group address frame (YES in S605), the AP 102 determines whether to transmit the additional group address frame on all links (S606). If the AP 102 transmits the additional group address frame on all links (YES in S606), the AP 102 aligns the transmission periods and transmits the additional group address frame on all links (S608). Note that, as described above, adding padding bits or transmitting another frame may be performed to align the transmission periods. Furthermore, when transmitting a beacon on each link, the AP 102 may reserve a TXOP common to other links, taking into account the transmission period of the additional group address frame. On the other hand, if the AP 102 transmits an additional group address frame following the beacon only on a certain link (NO in S606), it reserves a TXOP on the link on which the group address frame is not transmitted (S607). This TXOP can be reserved for a period until the transmission of the group address frame on the other links is completed. The AP 102 can reserve a TXOP in the same manner as in the above-described process example 1.

[0057] FIG. 7 shows an example of the communication flow when the AP 102 operates based on the processing of FIG. 6. Note that this example describes a case where an additional group address frame is transmitted on all links immediately after the transmission of a beacon. In the example of FIG. 7, at beacon transmission timing 731, the TXOP 711 by the STA 103 has ended on link 104, and the link is not busy. On the other hand, the NAV period 721 is set on link 105, for example, because the frequency channel is being used for communication by another STA 106, and the link is busy. Therefore, the AP 102 cannot transmit beacons on both links 104 and 105 simultaneously, and therefore waits without transmitting beacons on either link. Thereafter, the AP 102 transmits beacons 712 and 722 on both links 104 and 105 at timing 732 when the link 105 is no longer busy and both links 104 and 105 are not busy. Thereafter, AP 102 transmits an additional group address frame 713 on link 104, and further transmits an additional group address frame 723 on link 105. At this time, AP 102 executes control to align the transmission periods of these frames, and matches the transmission end timing 733 of the group address frames on link 104 and link 105. Note that these additional group address frames are not necessary, but even when only beacons are transmitted, control is performed so that the transmission end timings of the beacons match.

[0058] As a result, AP 102 transmits frames on all links, preventing a situation in which AP 102 transmits frames on one link while receiving frames on another link. This processing example can also handle the case in which a beacon transmission timing arrives while AP 102 is receiving data from another STA on link 105. In other words, AP 102 can prevent the simultaneous reception of a frame on link 105 and the transmission of a beacon on link 104 by performing processing similar to that described above.

[0059] Note that the above-described processing example is merely an example, and processing different from the above-described processing may be performed. For example, in the above-described processing example, the beacon transmission timing of link 104 is changed based on the NAV period of link 105, but this is not limited to this. For example, AP 102 may set link 104 as the primary link and link 105 as the sub-link, and execute the control of shifting the beacon transmission timing as described above only when the beacon transmission timing is shifted on the primary link. That is, if the beacon transmission timing arrives during the NAV period of link 104, AP 102 shifts the timing of beacon transmission on both links 104 and 105. On the other hand, if the beacon transmission timing arrives during the NAV period of link 105, AP 102 shifts only the beacon transmission timing on link 105, but does not shift the beacon transmission timing on link 104. That is, AP 102 may operate by prioritizing the primary link.

[0060] In addition to the above processing, the AP 102 may, for example, require connection to the primary link and allow only communication devices capable of multilink communication to connect to sublinks. This allows the AP 102 to operate as a multilink communication AP while taking into consideration the operation of communication devices operating on the link 104 that do not support multilink communication. In this case, the AP 102 does not need to transmit a beacon on the link 105 if the beacon transmission timing is not possible due to, for example, the NAV period at the beacon transmission timing. This is because each STA connected to the AP 102 can maintain synchronization with the AP 102 even when receiving a beacon only on the link 104. However, because there are operations that must be performed for each link, such as an operation to return from power saving mode or an operation to correct time fluctuations, the AP 102 transmits a beacon on each link at a timing when transmission is possible.

[0061] (Processing example 3) In this processing example, the AP 102 attempts to transmit a beacon at different timings (at timings where the transmission periods do not overlap) on the links 104 and 105. Note that the AP 102 does not necessarily have to transmit a beacon so that the transmission periods on the links 104 and 105 do not overlap, and it is assumed that at least a partial overlap of the beacon transmission periods on the links 104 and 105 is permitted.

[0062] Fig. 8 shows an example of the flow of processing executed by AP 102 in the third processing example. The processing of Fig. 4 is started, for example, when AP 102 starts operating as an AP. Note that the processing of Fig. 4 can be realized, for example, by the control unit 202 of AP 102 executing a program stored in the storage unit 201 of AP 102. However, this is not limited to this, and for example, some or all of the processing of Fig. 4 may be realized by dedicated hardware. Furthermore, the processing of Fig. 8 is one example, and unless otherwise specified, the order of each processing may be changed, some of the processing may be omitted, or the processing may be replaced with other similar processing.

[0063] In this process, the AP 102 first waits until the beacon transmission time (S801). Then, before transmitting a beacon, the AP 102 checks the status of other links other than the link through which the beacon is being transmitted. Note that the order of the steps for checking other links in the following description is merely an example, and the order of these steps may be reversed. For example, the AP 102 first determines whether a frame is also being transmitted on another link (S802). If the AP 102 is also transmitting a frame on another link (YES in S802), the AP 102 transmits a beacon or an additional group address frame by matching the transmission time with that of the other link (S810). Note that various frames may be transmitted on the other link, such as management frames including beacon frames, unicast data frames, and control frames including trigger frames. Furthermore, group address frames addressed to a multicast address or broadcast address, action frames, and the like may also be transmitted on the other link.

[0064] When the AP 102 determines that a frame is not being transmitted on the other link as a result of checking the status of the other link (NO in S802), it then determines whether or not the NAV period is in effect on the other link (S803). When the AP 102 determines that the NAV period is not in effect on the other link (NO in S803), it reserves a TXOP until the end of the beacon transmission period (and the transmission period of an additional group address frame, if any, associated with the beacon) (S809). By reserving the transmission right on the other link in this manner, the AP 102 can prevent a signal from being received on the other link during the beacon transmission period (and the transmission period of an additional group address frame). The method for reserving a TXOP has been described above, and the description will not be repeated here, and the same applies hereinafter.

[0065] When the AP 102 determines that the NAV period is in progress on the other link (YES in S803) as the state of the other link, it subsequently determines whether the AP 102 is receiving a frame (S804). If the AP 102 is receiving a frame on the other link (YES in S804), it cannot transmit a frame during that reception. Therefore, in this case, the AP 102 waits until a timing at which it can transmit a frame before transmitting a beacon (S808). Note that the AP 102 reserves a TXOP for the other link during the period during which it is transmitting a beacon. Note that in this case, the AP 102 has been receiving a frame on the other link until just before, and therefore may need to transmit a reception acknowledgment response (Ack frame or Block Ack frame) for that frame. Therefore, the AP 102 can reserve a TXOP for transmitting the reception acknowledgment response. Note that an Ack frame or Block Ack frame is a type of control frame.

[0066] In a situation where a frame is not being received during the NAV period of another link (NO in S804), it is assumed that, for example, STA 106 is transmitting or receiving a data frame to or from another AP. In this situation, it is assumed that AP 102 is not receiving data during the NAV period. In this case, if the transmission of a beacon is completed during the NAV period, AP 102 can transmit only the beacon without receiving data addressed to itself via the other link. Therefore, AP 102 determines whether the NAV period of the other link will expire during the transmission period of the beacon (and, if there is an additional group address frame associated with the beacon, the transmission period of that frame) (S805). Then, if the NAV period of the other link will not expire during the transmission period of the beacon, etc. (NO in S805), AP 102 transmits the beacon, etc. as is (S807). On the other hand, if the NAV period of another link expires during the transmission period of a beacon or the like (YES in S805), the AP 102 reserves a TXOP in the other link so that no signal addressed to the AP 102 is transmitted during that transmission period (S806). Note that the AP 102 starts transmitting a beacon in the beacon transmission time in one link. The AP 102 may also transmit any frame during the TXOP period reserved in S806.

[0067] In this way, when the AP 102 transmits beacons independently on each link, it is possible to prevent a frame addressed to the AP 102 from arriving on another link while the AP 102 is transmitting a beacon or the like on one link.

[0068] FIG. 9 shows an example of a communication flow when the AP 102 operates based on the processing of FIG. 8. FIG. 9 shows an example of a communication flow when the NAV period expires during the transmission of a beacon and an additional group address frame accompanying the beacon. In the example of FIG. 9, at beacon transmission timing 931, the TXOP 911 by the STA 103 ends in the link 104. Meanwhile, the NAV period 921 is set in the link 105 because, for example, the frequency channel is used for communication by another STA 106. Meanwhile, if the beacon transmission starts in the link 104 at transmission timing 931, the transmission of a series of frames is completed at timing 933. In this case, since the NAV period 921 expires before timing 933, the AP 102 reserves the TXOP 922 in the link 105 during the period from timing 932 to timing 933, when the transmission right can be reserved. Note that the AP 102 may transmit any frame in the TXOP 922. In this way, the AP 102 can prevent frames addressed to the AP 102 from arriving on the link 105 during the period in which the beacon 912 and the additional group address frame 913 are being transmitted on the link 104 .

[0069] 10 shows another example of the flow of communication when the AP 102 operates based on the processing of FIG. 8. FIG. 10 shows an example in which the AP 102 is receiving a data frame from the STA 103 on the link 105 at the time of transmitting a beacon on the link 104. That is, in the example of FIG. 10, at the beacon transmission timing 1031, the TXOP 1011 by the STA 103 on the link 104 has ended, but the TXOP 1021 by the STA 103 on the link 105 continues, and the AP 102 is receiving a frame. Therefore, the AP 102 waits without transmitting a beacon until the TXOP 1021 by the STA 103 on the link 105 has ended. Note that while FIG. 10 shows a case in which the STA 103 operates in multi-link, the STA 103 may be a communication device that does not support multi-link communication. Then, at timing 1032 when the AP 102 has finished receiving the frame from the STA 103 and is able to secure the transmission right on the link 105, the AP 102 starts transmitting the beacon 1012 and the additional group address frame 1013 on the link 104. At this time, the AP 102 secures a TXOP 1022 on the link 105 so that frames addressed to the AP 102 do not arrive. The TXOP 1022 is set as a period until the transmission of the beacon 1012 and the additional group address frame 1013 (and any further frames to be transmitted, if any) on the link 104 is completed. That is, in the example of FIG. 10 , the TXOP 1022 is secured on the link 105 until timing 1033 when the transmission of the additional group address frame 1013 on the link 104 is completed. Note that in the example of FIG. 10 , the AP 102 has just received a frame during the period of the TXOP 1021 from the STA 103, and therefore, can transmit an acknowledgment of receipt of the frame in the TXOP 1022. In this way, the AP 102 can prevent frames addressed to the AP 102 from arriving on the link 105 during the period in which the beacon 1012 and the additional group address frame 1013 are being transmitted on the link 104 .

[0070] In this processing example, even in an environment where interference not due to communication from a microwave oven or the like exists on one link, the AP 102 can perform communication (e.g., transmit a beacon) on another link. Furthermore, if the AP 102 is receiving data on a link that does not transmit a beacon, the AP 102 can prevent simultaneous transmission and reception by suspending the transmission. By varying the timing of beacon transmission for each link, as in this processing example, the flexibility of communication on each link can be improved. On the other hand, by aligning the timing of beacon transmission, as in the above-described processing examples 1 and 2, processing such as securing a TXOP on one link while transmitting a beacon on the other link is not required, thereby reducing overhead. The above-described processing examples can be used in combination. For example, processing example 1 or processing example 3 can be used when there is interference not due to communication from a NAV period or a microwave oven, while processing example 2 can be used when a frame is being received on a link on which a beacon is not transmitted. This makes it possible to effectively utilize the advantages of each of the above-described processing examples while preventing parallel transmission and reception in the AP 102.

[0071] In the above-described embodiment, the AP 102 and the STA 103 are assumed to access channels using EDCA (Enhanced Distributed Channel Access). However, this is not limiting. For example, the AP 102 may allow only trigger frame-based UL (uplink) communications from connected STAs. In this case, the AP 102 assigns channels so that, when a beacon is transmitted on one link, UL communications are not performed on another link. This prevents frames addressed to the AP 102 from arriving from the STA during the beacon transmission period.

[0072] In the above-described embodiment, the AP 102 has been described as preventing data addressed to the AP 102 from being generated on a link where beacons are not transmitted by, for example, acquiring a transmission right. Alternatively, or in addition, the AP 102 may operate to reduce the probability of data addressed to the AP 102 being generated. For example, the AP 102 may receive an RTS frame requesting data transmission from a STA connected to the AP 102. In this case, the AP 102 identifies the TXOP duration that the STA, which is the source of the RTS, is attempting to secure from the value indicated in the Duration field of the RTS and determines whether the duration overlaps with a beacon transmission period on another link. If the TXOP duration that the STA is attempting to secure overlaps at least partially with a beacon transmission period on another link, the AP 102 may reject the RTS by not transmitting a CTS, which is a response to the received RTS. This reduces the probability that the STA will not be able to secure a TXOP and will transmit a frame addressed to the AP 102 during the AP 102's beacon transmission period.

[0073] <<Other embodiments>> The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0074] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0075] 102: Access point, 103: Station, 202: Control unit, 206: Communication unit, 301: Wireless LAN control unit, 303: Transmission time control unit, 304: Beacon control unit

Claims

1. A communication device, a communication means for performing communication with a partner device using a plurality of wireless links in accordance with the IEEE 802.11 standard series; a control means for controlling the communication means so that, when a predetermined frame that is a group address frame is transmitted through a first wireless link among the plurality of wireless links, a frame addressed to the communication device does not arrive through a second wireless link among the plurality of wireless links that is different from the first wireless link; A communication device having:

2. 2. The communication device according to claim 1, wherein the control means controls the communication means so as to reserve a transmission right on the second wireless link during a period in which the predetermined frame is transmitted on the first wireless link.

3. 3. The communication device according to claim 2, wherein the control means controls the communication means so as to secure the transmission right by transmitting a frame on the second wireless link during a period in which the specified frame is transmitted on the first wireless link.

4. 4. The communication device according to claim 3, wherein the frame transmitted to reserve the transmission right on the second wireless link includes an empty frame.

5. 4. The communication device according to claim 3, wherein the frame transmitted to reserve the transmission right on the second wireless link includes a group address frame.

6. 6. The communication device according to claim 3, wherein the frame transmitted to secure the transmission right on the second wireless link includes padding bits based on the length of the period during which the specified frame is transmitted on the first wireless link.

7. The communication device according to any one of claims 2 to 6, characterized in that the control means controls the communication means to transmit either a CTS (Clear-To-Send) or RTS (Request-To-Send) frame on the second wireless link during a period in which the specified frame is transmitted on the first wireless link so as to secure the transmission right before the period begins.

8. 8. The communication device according to claim 3, wherein the control means controls the communication means to set the value of a Duration field in a frame transmitted to secure the transmission right to a period corresponding to the period during which the specified frame is transmitted on the first wireless link and transmit the frame on the second wireless link.

9. 9. The communication device according to claim 2, wherein the control means controls the communication means to secure the transmission right in the second wireless link during a period in which the specified frame is transmitted in the first wireless link, based on a deviation of the timing of transmitting the specified frame in the first wireless link from a predetermined transmission timing.

10. 10. The communication device according to claim 9, wherein the control means controls the communication means to shift the timing of transmitting the specified frame on the first wireless link so that, when a frame addressed to the communication device is received on the second wireless link at the predetermined transmission timing of the specified frame, the specified frame is transmitted on the first wireless link after reception of the frame is completed.

11. The communication device according to claim 9 or 10, characterized in that, if the control means cannot secure the transmission right in the second wireless link at the predetermined transmission timing of the specified frame and a frame addressed to the communication device is not received, the control means controls the communication means to transmit the specified frame at the predetermined transmission timing in the first wireless link.

12. The communication device according to claim 11, characterized in that, if it becomes possible to secure the transmission right in the second wireless link while transmitting the specified frame at the predetermined transmission timing in the first wireless link, it controls the communication means so as to secure the transmission right in the second wireless link from the time the transmission right becomes possible to the time transmission of the specified frame is completed.

13. the communication means is configured to transmit a first predetermined frame, which is a group address frame, over the first wireless link and to transmit a second predetermined frame, which is a group address frame, over the second wireless link; 2. The communication device according to claim 1, wherein the control means controls the communication means to transmit the second predetermined frame on the second wireless link during a period for transmitting the first predetermined frame on the first wireless link after the timing of transmitting the first predetermined frame on the first wireless link has shifted from a predetermined transmission timing.

14. 14. The communication device according to claim 13, wherein the control means controls the timing at which the transmission of the first predetermined frame and the second predetermined frame starts to coincide with the timing at which the transmission ends.

15. 15. The communication device according to claim 14, wherein when the timing of the end of transmission based on the frame length of the first predetermined frame in the first wireless link and the frame length of the second predetermined frame in the second wireless link differ, the control means includes padding bits in the frame whose transmission ends first, and performs control so that the timing of the end of transmission coincides.

16. 15. The communication device according to claim 14, wherein, when the timing of the end of transmission based on the frame length of the first predetermined frame in the first wireless link and the frame length of the second predetermined frame in the second wireless link differ, the control means controls the communication means to transmit another frame in the wireless link in which transmission ends first so that the timing of the end of transmission coincides.

17. 17. The communication device according to claim 1, wherein the predetermined frame includes a beacon.

18. 18. The communication device according to claim 1, wherein the communication device is an access point.

19. A control method executed by a communication device that communicates with a partner device using multiple wireless links in accordance with the IEEE 802.11 standard series, comprising: A control method comprising: when a predetermined frame, which is a group address frame, is transmitted on a first wireless link among the plurality of wireless links, controlling so that a frame addressed to the communication device does not arrive on a second wireless link among the plurality of wireless links that is different from the first wireless link.

20. A program for causing a computer to function as each of the means included in the communication device according to any one of claims 1 to 18.

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