COMMUNICATION DEVICE, CONTROL METHOD FOR COMMUNICATION DEVICE, AND PROGRAM

Abstract

To provide a technology for transmission / reception control when a shift occurs in the reception timing of frames that are periodically transmitted in multilink communication.SOLUTION: A communication device that conforms to the IEEE802.11 series standards and can perform multi-link communication with other communication devices using a plurality of links with different frequency channels receives a first frame on a first link from among the plurality of links from the other communication device, obtains information on reception timing of the first frame transmitted from the other communication device in the communication device at predetermined intervals on the basis of the first frame, and transmits a second frame through a second link among the plurality of links. The communication device does not transmit the second frame during a period including the reception timing, and transmits the second frame on the second link in response to the reception of the first frame.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to wireless communication technology. [Background technology]

[0002] With the increase in the amount of data being communicated in recent years, the development of communication technologies such as wireless LANs (Local Area Networks) is progressing. The IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard series is known as a major communication standard for wireless LANs. The IEEE 802.11 standard series includes standards such as IEEE 802.11a / b / g / n / ac / ax. For example, IEEE 802.11ax standardizes a technology that uses OFDMA (Orthogonal Frequency Division Multiple Access) to achieve a high peak throughput of up to 9.6 gigabits per second (Gbps) as well as improve communication speeds under congested conditions (Patent Document 1).

[0003] A task group called IEEE802.11be was launched as a successor standard aiming to further improve throughput, frequency efficiency, and communication latency. IEEE802.11be considers multi-link communication, in which one AP (access point) and one STA (station) establish multiple links in frequency bands such as the 2.4GHz band and communicate simultaneously. In addition, due to hardware restrictions on wireless communication devices, APs and STAs are being considered that are configured so that one link cannot receive while another link is transmitting in multi-link communication. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-50133 A Summary of the Invention [Problem to be solved by the invention]

[0005] An STA that cannot receive on one link while transmitting on another link needs to periodically receive Beacon frames (hereinafter, sometimes referred to as Beacons) on each link. However, while such an STA is transmitting some data on the link, it cannot receive a group address frame including a Beacon on the other link. Even if such an STA knows the timing to receive a Beacon on the link, the timing may differ depending on the congestion of the link. Even in such a case, the STA needs to operate in such a way that it cannot transmit on the other link while transmitting on the link.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a technique for controlling transmission and reception when a deviation occurs in the reception timing of a frame that is periodically transmitted in multi-link communication. [Means for solving the problem]

[0007] As one means for achieving the above object, a communication device of the present invention has the following configuration: That is, the communication device is compliant with the IEEE802.11 series standard and is capable of performing multi-link communication with another communication device using a plurality of links having different frequency channels, and receives a signal from the other communication device on a first link of the plurality of links. Compliant with the IEEE802.11 series standards a receiving means for receiving a first frame; an acquiring means for acquiring information on a receiving timing of the first frame transmitted from the other communication device at a predetermined interval in the communication device based on the first frame; Compliant with the IEEE802.11 series standardsand a transmitting means for transmitting a second frame, wherein the transmitting means does not transmit the second frame during a first period from the reception timing to start of reception of the first frame and during a second period during which the first frame is being received. Effect of the Invention

[0008] According to the present invention, a technique for controlling transmission and reception when a deviation occurs in the reception timing of a frame that is periodically transmitted in multi-link communication is provided. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Diagram 2] FIG. 2 illustrates an example of a hardware configuration of a communication device. [Diagram 3] FIG. 2 illustrates an example of a functional configuration of a communication device. [Figure 4] 4 is a flowchart of a process executed by a STA according to the first embodiment. [Diagram 5] 4 is a sequence diagram illustrating an example of processing by an AP and an STA according to the first embodiment. FIG. [Figure 6] FIG. 11 is a sequence diagram illustrating another example of processing by the AP and the STA according to the first embodiment. [Figure 7] 11 is a flowchart of a process executed by a STA according to the second embodiment. [Figure 8] FIG. 11 is a sequence diagram illustrating an example of processing by an AP and an STA according to the second embodiment. [Figure 9] FIG. 11 is a sequence diagram illustrating another example of processing by the AP and the STA according to the second embodiment. [Figure 10] FIG. 11 is a sequence diagram illustrating another example of processing by the AP and the STA according to the second embodiment. [Figure 11] FIG. 11 is a sequence diagram showing an example of processing by an AP and a STA according to a third embodiment. [Figure 12] FIG. 13 is a sequence diagram showing another example of processing by the AP and the STA according to the third embodiment. [Figure 13]An example of the configuration of a TIM element is shown below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0011] (Configuration of wireless communication system) 1 shows an example of the configuration of a wireless communication system according to this embodiment. This system includes communication devices 101, 102, and 105. Communication device 102 (hereinafter, STA102) is a STA (station / terminal device) that plays a role in participating in a wireless network 100. Communication device 101 (hereinafter, AP101) is an AP (access point) that plays a role in constructing the wireless network 100. AP101 can communicate with STA102. Communication device 105 (hereinafter, STA105) is a STA that does not participate in the wireless network 100. STA105 cannot communicate with AP101, but is within a distance where their radio waves interfere with each other.

[0012] Each of the AP 101 and the STA 102 can perform wireless communication conforming to the IEEE802.11be (EHT (Extreme / Extremely High Throughput)) standard. The AP 101 and the STA 102 can communicate at frequencies such as the 2.4 Hz band, the 5 GHz band, the 6 GHz band, and the 60 GHz band. The frequency bands used by each communication device are not limited to these, and may use different frequency bands such as the 60 GHz band. The AP 101 and the STA 102 can communicate using bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz, and 320 MHz. The bandwidths used by each communication device are not limited to these, and may use different bandwidths such as 240 MHz and 4 MHz.

[0013] The AP 101 can realize multi-user (MU) communication by multiplexing the signals of multiple users by performing OFDMA communication compliant with the IEEE802.11be standard. In OFDMA communication, a part of the divided frequency band (Resource Unit (RU)) is assigned to each STA so that they do not overlap, and the carrier waves for each STA are orthogonal. Therefore, the AP can communicate with multiple STAs in parallel within a specified bandwidth.

[0014] Although the AP 101 and the STA 102 are described as being compatible with the IEEE 802.11be standard, they may also be compatible with a legacy standard that is a standard that precedes the IEEE 802.11be standard. Specifically, the AP 101 and the STA 102 may be compatible with at least one of the IEEE 802.11a / b / g / n / ac / ax standards. In addition to the IEEE 802.11 series standards, they may also be compatible with other communication standards such as Bluetooth (registered trademark), Near Field Communication (NFC), Ultra Wide Band (UWB), ZigBee, and Multi Band OFMA Alliance (MBOA). UWB includes wireless USB, wireless 1394, WiNET, and the like. They may also be compatible with a communication standard for wired communication such as wired LAN.

[0015] Specific examples of the AP 101 include, but are not limited to, a wireless LAN router and a personal computer (PC). The AP 101 may also be an information processing device such as a wireless chip capable of performing wireless communication conforming to the IEEE802.11be standard. Specific examples of the STA 102 include, but are not limited to, a camera, a tablet, a smartphone, a PC, a mobile phone, a video camera, a headset, etc. The STA 102 may also be an information processing device such as a wireless chip capable of performing wireless communication conforming to the IEEE802.11be standard.

[0016] The AP 101 and the STA 102 perform multi-link communication by establishing links via multiple frequency channels. In the IEEE 802.11 series standard, the bandwidth of each frequency channel is defined as 20 MHz. Here, the frequency channel is a frequency channel defined in the IEEE 802.11 series standard, and in the standard, multiple frequency channels are defined in each of the 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz frequency bands. Note that a bandwidth of 40 MHz or more may be used in one frequency channel by bonding with adjacent frequency channels.

[0017] For example, AP 101 can establish link 103 via a first frequency channel in the 2.4 GHz band with STA 102 and communicate with it. In parallel with this, STA 102 can establish link 104 via a second frequency channel in the 5 GHz band with AP 101 and communicate with it. In this case, STA 102 executes multi-link communication to maintain link 104 in parallel with link 103. In this way, AP 101 can improve the throughput in communication with STA 102 by establishing multiple links (multi-links) using multiple frequency channels with STA 102.

[0018] In multi-link communication, multiple links of different frequency bands may be established. For example, the AP 101 and the STA 102 may establish another link in the 5 GHz band in addition to the link 103 in the 2.4 GHz band and the link 104 in the 6 GHz band. Alternatively, links may be established via multiple different channels included in the same frequency band. For example, the AP 101 and the STA 102 may establish a link of 6ch in the 2.4 GHz band as the link 103, and in addition to this, a link of 1ch in the 2.4 GHz band as the link 104.

[0019] Also, links with the same frequency band and links with different frequency bands may be mixed. For example, in addition to link 103 with 6ch in the 2.4GHz band, AP101 and STA102 may establish link 104 with 1ch in the 2.4GHz band and another link with 149ch in the 5GHz band. By establishing multiple connections with STA102 with different frequencies, even if one band is congested, AP101 can establish communication with STA102 with the other band, thereby preventing a decrease in throughput and communication delays in communication with STA102.

[0020] In this embodiment, as an example, the link 103 is a 20 MHz connection on ch6 in the 2.4 GHz band, and the link number is set to 1. The link 104 is a 320 MHz connection on ch113 in the 6 GHz band, and the link number is set to 2.

[0021] Although the wireless network 100 in Fig. 1 is composed of one AP and one STA, the number and arrangement of the APs and STAs are not limited to this. For example, one STA may be added to the wireless network in Fig. 1. In this case, the frequency band of each link to be established, the number of links, and the frequency width are not important.

[0022] In this embodiment, the STA105 may be a communication device that operates on one of the multiple links established between the AP101 and the STA102 without considering the other links. For example, in the above description, the STA105 is an STA that does not participate in the wireless network 100, but may participate in the wireless network 100. In this case, the STA105 may not be compliant with IEEE802.11be, and may be an STA that is compliant only with IEEE802.11b. In addition, in this case, the STA105 may be a device that establishes a link with the AP101 on 6ch in the 2.4GHz band. Alternatively, the STA105 may be a noise source that generates radio noise unrelated to the wireless network, such as a microwave oven. Alternatively, the STA105 may be a communication device that supports multi-link communication and establishes multiple links with the AP101. In this case, the STA105 may be a communication device that ignores the operation on one link and communicates on the other link.

[0023] When performing multi-link communication, one piece of data may be divided between the AP 101 and the STA 102 and transmitted to the other device via multiple links. The AP 101 and the STA 102 may also be configured to perform MIMO (Multiple-Input and Multiple-Output) communication. In this case, the AP 101 and the STA 102 have multiple antennas, and one transmits different signals from each antenna using the same frequency channel. The receiving side simultaneously receives all signals arriving from multiple streams using multiple antennas, and separates and decodes the signals of each stream. In this way, by performing MIMO communication, the AP 101 and the STA 102 can communicate more data in the same time compared to when not performing MIMO communication. When performing multi-link communication, the AP 101 and the STA 102 may also perform MIMO communication on some links.

[0024] (STA and AP configuration) 2 shows an example of the hardware configuration of the STA 102 in this embodiment. As an example of the hardware configuration, the STA 102 has 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 AP 101 can also have a hardware configuration similar to that of the STA 102.

[0025] The storage unit 201 is configured with one or more memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and stores various information such as computer programs for performing various operations described below and communication parameters for wireless communication. Note that, in addition to memories such as ROM and RAM, storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs may be used as the storage unit 201. Furthermore, the storage unit 201 may include multiple memories.

[0026] The control unit 202 is configured with one or more processors such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and controls the entire STA 102 by executing a computer program stored in the storage unit 201. The control unit 202 may control the entire STA 102 in cooperation with the computer program stored in the storage unit 201 and an OS (operating system). The control unit 202 also generates data and signals (radio frames) to be transmitted in communication with other communication devices. The control unit 202 may also include multiple processors such as multi-core processors, and the entire STA 102 may be controlled by the multiple processors.

[0027] Furthermore, the control unit 202 controls the function unit 203 to execute predetermined processes such as wireless communication, imaging, printing, projection, etc. The function unit 203 is hardware that enables the STA 102 to execute predetermined functions.

[0028] The input unit 204 receives various operations from the user. The output unit 205 outputs various types of information to the user via a monitor screen or a speaker. Here, the output by the output unit 205 may be a display on a monitor screen, a voice output by a speaker, a vibration output, or the like. Note that both the input unit 204 and the output unit 205 may be realized by a single module, such as a touch panel. Also, the input unit 204 and the output unit 205 may be integrated with the STA 102, or may be separate from it.

[0029] The communication unit 206 controls wireless communication conforming to the IEEE802.11be standard. The communication unit 206 may also control wireless communication conforming to other IEEE802.11 series standards in addition to the IEEE802.11be standard, and control wired communication such as a wired LAN. The communication unit 206 controls the antenna 207 to transmit and receive signals generated by the control unit 202 for wireless communication.

[0030] If the STA 102 supports the NFC standard, Bluetooth standard, etc. in addition to the IEEE802.11be standard, the STA 102 may control wireless communication in accordance with these communication standards. If the STA 102 can perform wireless communication in accordance with a plurality of communication standards, the STA 102 may have a communication unit 206 and an antenna 207 that support each of the communication standards. The STA 102 communicates data such as image data, document data, and video data via the communication unit 206. The antenna 207 may be configured as a separate unit from the communication unit 206, or may be configured together with the communication unit 206 as a single module.

[0031] Antenna 207 is an antenna capable of communication in frequency bands such as 2.4 GHz band, 5 GHz band, and 6 GHz band. Although one antenna 207 is shown in FIG. 2, multiple antennas may be used. Alternatively, STA 102 may have a different antenna for each frequency band. Also, as described above, when STA 102 has multiple antennas, it may have a communication unit 206 corresponding to each antenna.

[0032] 3 shows an example of the functional configuration of the STA 102 in this embodiment. The STA 102 has, as an example of the functional configuration, a wireless LAN control unit 301, a frame generation unit 302, a transmission control unit 303, a beacon reception control unit 304, and a UI (User Interface) control unit 305. The AP 101 can also have a functional configuration similar to that of the STA 102.

[0033] The wireless LAN control unit 301 may be configured to include a program for controlling transmission and reception of wireless signals between other wireless LAN devices. The wireless LAN control unit 301 transmits and receives frames generated by the frame generation unit 302 via the communication unit 206 and the antenna 207 in accordance with the IEEE802.11 standard series, and executes wireless LAN communication control. The number of wireless LAN control units is not limited to one, and may be two, or three or more.

[0034] Frame generation unit 302 generates a wireless frame to be transmitted by wireless LAN control unit 301. The contents of the frame generated by frame generation unit 302 may be restricted by settings stored in storage unit 201 (FIG. 2), or may be changed by user settings from UI control unit 305. Information on the generated frame is sent to wireless LAN control unit 301, and transmitted to the communication partner via communication unit 206 and antenna 207.

[0035] The transmission control unit 303 performs transmission control for various frames transmitted from the STA 102. For example, the transmission control unit 303 measures (counts) and determines the timing for transmitting a frame on each link, and notifies the result to the wireless LAN control unit 301. The wireless LAN control unit 301 transmits the frame based on this.

[0036] The Beacon reception control unit 304 manages the timing of receiving a Beacon frame (hereinafter sometimes referred to as a Beacon) and analyzes the received Beacon. For example, the Beacon reception control unit 304 obtains information on the timing of receiving the next Beacon based on the received Beacon information, and transmits the information to the wireless LAN control unit 301 and the transmission control unit 303. The timing of receiving a Beacon (Beacon reception timing) can be obtained from a value indicating the interval of the Beacon transmission time, such as TBTT (Target Beacon Transmission Time), included in the Beacon.

[0037] The UI control unit 305 generates a control signal based on a user's operation (user setting) on ​​the input unit 204, and transmits it to each component. The UI control unit 305 also controls various outputs to the output unit 205.

[0038] In the following embodiments, a situation is assumed in which STA 102 receives a group addressed frame in the communication system shown in Fig. 1. A group addressed frame can be a frame that includes an address with a Group Bit of 1 in the MAC Address field included in the Destination Address (DA) field or A1 field. For example, a broadcast frame including a beacon is a type of group addressed frame because its Group Bit is 1. In addition, a multicast frame addressed to a multicast address also has its Group Bit set to 1, and is therefore a group addressed frame.

[0039] Next, the processing of the STA 102 according to this embodiment will be described using several examples. In this embodiment, the AP 101 periodically transmits a Beacon including a TIM (Traffic Indication Message). c Information on the timing of receiving a beacon at a predetermined interval can be obtained from the value indicating the interval of the beacon transmission time included in on. When there is data for the STA 102, the AP 101 can notify the STA 102 of the presence of data (group address frame) using a beacon by using a TIM (TIM element), and can transmit the data after the notification. The TIM that can notify the presence of data is called a DTIM (Delivery Traffic Indication Message).

[0040] Example 1 In this embodiment, a situation is assumed in which the STA 102 is unable to receive a Beacon at the scheduled timing when receiving the Beacon via the link 104. In this case, in this embodiment, the STA 102 is configured not to transmit frames via the links 103 and 104 until it receives the Beacon and the subsequent group address frame (different from the Beacon).

[0041] In this embodiment, the beacon may be any frame as long as it is a group address frame. For example, the beacon may be a multicast frame addressed to a multicast address. The beacon may be a FILS Discovery frame or an Unsolicited Probe Response frame transmitted between beacons at intervals of 20 TU (Time Unit). The beacon may be a Probe Response frame or an Action frame, which are other management frames. Or, the beacon may be a Trigger frame transmitted periodically. In this embodiment, a situation is considered in which the beacon is received only by the link 104, but the same applies to a situation in which the beacon is received by the link 103. The same applies to a situation in which the beacon is received simultaneously by the link 103 and the link 104. The same applies to a situation in which the beacon is received simultaneously by the link 103 and the link 104, but one of them is not able to receive the beacon.

[0042] Fig. 4 is a flowchart showing the processing of STA 102 when STA 102 receives a Beacon from AP 101 via link 104 in this embodiment. The flowchart shown in Fig. 4 can be realized by the control unit 202 of STA 102 executing a control program stored in the storage unit 201, and performing calculations and processing of information and control of each piece of hardware. The processing shown in this flowchart can be started at the same time that STA 102 establishes a connection with AP 101 via multi-links (links 103 and 104 in this embodiment).

[0043] When the STA102 is connected to the AP101, the Beacon reception control unit 304 of the STA102 judges whether the Beacon reception timing is approaching on any link, i.e., whether it is a predetermined time before the Beacon reception timing (S401). The predetermined time is 10 μsec in this embodiment, but this is just an example, and it may be 5 μsec or 20 μsec. As described above, whether it is the Beacon reception timing or not can be known from the value indicating the interval of the Beacon transmission time included in the Beacon received from the AP101. In this embodiment, the Beacon reception timing is every 100 msec (i.e., Beacon interval = 100 msec), but it can be set to any interval such as every 150 msec.

[0044] If the Beacon reception timing is approaching on any link (Yes in S401), the process proceeds to S402. Hereinafter, the link on which the Beacon reception timing is approaching is referred to as the target link. In S402, under the control of the transmission control unit 303 of the STA102, the wireless LAN control unit 301 causes the STA102 to refrain from data upload (UL) before the Beacon reception period on the target link. That is, the STA102 does not perform data upload / data transmission during the period including the Beacon reception timing. This means that if data upload is in progress, data upload is temporarily suspended on all links. Here, the links on which upload is suspended are all links that are a combination of links that cannot transmit and receive simultaneously. Therefore, for example, if the AP101 and the STA102 have established a third link (not shown) on which they can transmit and receive simultaneously, data upload does not need to be suspended on the third link.

[0045] Next, the Beacon reception control unit 304 of the STA102 waits for the reception of a Beacon on the target link (S403). If the Beacon is not received on the target link at the Beacon reception timing (No in S403), the transmission control unit 303 of the STA102 checks whether a predetermined scheduled time (the time from the original Beacon reception timing to the timing to stop waiting for frame reception) has passed (S404). In this embodiment, the scheduled time is 10 msec. If the scheduled time has not passed (No in S404), the process returns to S402, and if the scheduled time has passed (Yes in S404), the process proceeds to S408. If the Beacon is received on the target link (Yes in S403), the Beacon reception control unit 304 of the STA102 checks whether there is an additional group address frame (whether a group address frame is transmitted following the Beacon) (S405). For this purpose, the STA102 checks the TIM element included in the Beacon. Moreover, the STA 102 can check whether data addressed to itself has accumulated by checking the TIM element.

[0046] FIG. 13 shows an example of the configuration of a TIM element 1300. This element is defined in accordance with the IEEE 802.11 standard. An Element ID field 1301 contains a value of 5, which indicates that the element being used is a TIM element. A Length field 1302 indicates the length of the element. A DTIM Count field 1303 indicates whether the beacon containing this element is a DTIM (Delivery Traffic Indication Map) Beacon (a beacon containing DTIM). When this value is 0, this indicates that the beacon containing this element is a DTIM Beacon, and there is a possibility that a frame (data) for an STA is included after this. If this value is a value other than 0, it is not a DTIM Beacon, and the STA 102 can determine that there are no frames for an STA or group address frames following the beacon.

[0047] The Bitmap Control field 1305 indicates whether or not there is a frame with AID0 (Association Identifier) ​​in its Bit0. If Bit0 is 1, it indicates that some kind of group address frame is additionally prepared after the Beacon. it The map field 1306 indicates whether frames for each STA are queued. Each bit in this field is associated with an AID assigned to the STA by the AP at the time of connection. The STA 102 can determine whether frames addressed to itself are queued in the data transmission queue of the AP by checking whether the bit associated with the AID is 1.

[0048] The Beacon reception control unit 304 of the STA102 checks the TIM element included in the Beacon, and if it is confirmed that a group address frame is transmitted following the Beacon (Yes in S405), the process proceeds to S406, and if it is not confirmed (No in S405), the process proceeds to S408. In S406, the wireless LAN control unit 301 continues to refrain from uploading data (continues interruption) under the control of the transmission control unit 303 of the STA102. The transmission control unit 303 of the STA102 refrains from uploading data until the additional group address frame is received (S407). The determination of whether the additional group address frame is received may be based on the fact that a certain time, for example, a Distributed Coordination Function Interframe Space (DIFS) time, has elapsed since the STA102 received the group address frame on the target link (the link that received the group address frame). Alternatively, it may be triggered by the transmission of an Ack frame or a Block Ack frame after the group address frame is received.

[0049] If the wireless LAN control unit 301 of the STA102 receives a group address frame following the Beacon on the target link (Yes in S407), or if it fails to receive these but a certain time has passed (Yes in S404), the process proceeds to S408. In S408, the transmission control unit 303 of the STA102 checks whether or not a transmission frame has accumulated in its own transmission queue (S408). If the transmission control unit 303 of the STA102 checks that no transmission data has accumulated in the transmission queue (No in S408), it ends the process. If it checks that transmission data has accumulated in the transmission queue (Yes in S408), it proceeds to S409. In S409, the transmission control unit 303 of the STA102 waits for the AIFS (Arbitration Interframe Space) period from the last frame reception, and then sets a back-off counter for the waiting time until starting communication. The value of the AIFS differs depending on the priority of the data to be transmitted. If this is high-priority voice (VO) or video (VI) data, the AIFS is short. Conversely, in the case of low-priority background (BK) data, the AIFS is set long. The waiting period here may be a DIFS. The counter value of the backoff counter may be set to any value.

[0050] After setting the back-off counter, the transmission control unit 303 of the STA102 checks whether or not another communication device is transmitting a frame via any of the links that cannot transmit and receive simultaneously (S410). If it is checked that another communication device is not transmitting a frame via any of the links (No in S410), the transmission control unit 303 of the STA102 decrements the back-off counter by 1 (S416). The transmission control unit 303 of the STA102 repeats this process until the back-off counter becomes 0 (S417). When the back-off counter becomes 0 (Yes in S417), the wireless LAN control unit 301 of the STA102 starts (resumes) data transmission (S418).

[0051] When it is confirmed that another communication device is transmitting a frame on any of the links (Yes in S410), the transmission control unit 303 of the STA102 confirms whether the link on which the other communication device is transmitting is the link on which the STA102 is scheduled to transmit the frame (S411). If the link on which the other communication device is transmitting is the link on which the STA102 is scheduled to transmit the frame (Yes in S411), the transmission control unit 303 of the STA102 waits for transmission during a NAV (Network Allocation Vector) period included in the frame. After the NAV period ends, the transmission control unit 303 of the STA102 waits again for an AIFS period (S414). The waiting period here may be a DIFS period. If the STA102 confirms further frame transmission by the other communication device during this period, it waits again in the same manner. When the AIFS period ends, the transmission control unit 303 of the STA102 resumes processing of the back-off counter (S415), and the processing returns to S410 again.

[0052] In S411, if the link on which another communication device is transmitting is not the link on which the frame is scheduled to be transmitted (No in S411), the transmission control unit 303 of STA102 checks whether the frame transmitted by the other communication device is addressed to STA102 (addressed to itself) (S412). If the transmitted frame is addressed to STA102 (Yes in S412), STA102 needs to receive that frame, and cannot transmit frames on other links while receiving the frame. Therefore, STA102 needs to wait to transmit frames on all links that are combinations that cannot simultaneously transmit and receive frames until frame reception is complete (S413). When frame reception is complete, the process returns to S410 again.

[0053] The transmission control unit 303 of the STA102 may continue processing the back-off counter on the link to which the frame is to be transmitted even while waiting in S413. In this case, the STA102 continues the counter processing, but waits to transmit the frame until the frame reception on the other link is completed even if the count becomes 0. Then, when the frame reception on the other link is completed, if another communication device is not transmitting a frame on the link to which the frame is to be transmitted (the link on standby for transmission), the wireless LAN control unit 301 of the STA102 transmits the frame. However, since the frame transmission occurs at the same time as the frame reception on the other link is completed, the possibility of radio collision with the other communication device on the link to which the frame is to be transmitted increases. Therefore, if there is a frame addressed to the STA102 even on the other link, it is preferable to temporarily stop the back-off counter on all links on standby for transmission among all links in a combination that cannot be simultaneously transmitted and received. If the STA102 is not receiving a frame on the other link (No in S412), the transmission control unit 303 of the STA102 advances the back-off counter (S416). The processing from S417 onwards is as described above.

[0054] 4, it is assumed that STA 102 is planning to transmit a frame via one link, but if STA 102 is trying to transmit a frame via multiple links at the same time, the process may be divided for each link. For example, when STA 102 is preparing to transmit via links 103 and 104, if it confirms that another communication device is transmitting a frame via link 104, the process for link 103 may proceed to S412, and the process for link 104 may proceed to S414.

[0055] Next, a series of processing flows of the AP 101 and the STA 102 according to this embodiment will be explained using Figures 5 and 6. Figure 5 is a sequence diagram showing an example of processing of the AP 101 and the STA 102 according to this embodiment, and Figure 4 will also be referred to in the following explanation. Figure 5 shows a case where an additional group address frame is received following a Beacon on a certain link in a multi-link (link 103 and link 104), but the timing of receiving the Beacon is shifted due to channel congestion. Link 103 and link 104 are a combination of links that cannot transmit and receive simultaneously.

[0056] STA102 is transmitting (uploading) data on link 103 in accordance with its own TXOP (Transmission Opportunity: time during which continuous transmission is possible) 511. Meanwhile, on link 104, for example, STA105 (see FIG. 1) is transmitting a data frame to an AP other than AP 101, and NAV period 521 is set. STA102 is scheduled to receive a Beacon on link 104 at the original Beacon reception timing 531. When STA102 approaches Beacon reception timing 531 (Yes in S401), it refrains from (temporarily suspends) uploading data (S402).

[0057] Note that, if the STA 102 knows the length of the NAV period 521 of the link 104 and that the NAV period 521 does not overlap with the Beacon reception timing on the link 103, the STA 102 may continue transmitting data (TXOP 511) until the end of the NAV period 521. In FIG. 5, the STA 102 may continue transmitting data until before the Beacon reception timing 533 after the end of the NAV period 521. However, if there is a large difference between the end of the NAV period 521 and the Beacon reception timing, the STA 102 may consider transmitting data based on the end of the NAV period 521. If the end of the NAV period 521 is earlier than the Beacon reception timing, the STA 102 stops transmitting data before the Beacon reception timing.

[0058] In this embodiment, a case is considered in which the setting of NAV period 521 is valid for STA 102 but invalid for AP 101 depending on the radio wave environment. Therefore, in this embodiment, regardless of the NAV period, STA 102 uses Beacon reception timing 531 as a guide for interrupting data transmission. As a result, even if the period during which a Beacon can be received from AP 101 overlaps with the NAV period considered by STA 102, STA 102 can receive a Beacon on link 104.

[0059] Timing 532 indicates the timing (corresponding to the scheduled time in S404) at which to stop waiting for frame reception when a Beacon is not received at the original Beacon reception timing 531 (No in S403). In Fig. 5, STA102 receives Beacon522 from AP101 on link 104 at timing 533 after NAV period 521 ends before timing 532. STA102 checks the TIM element (see TIM element 1300 in Fig. 13) included in Beacon522 and confirms that a group address frame is transmitted following the Beacon (Yes in S405). Therefore, after receiving Beacon522, STA102 continues to receive additional group address frame 523 (S407).

[0060] When reception of the Beacon and the additional group address frame is completed at timing 534 (Yes in S407), STA 102 resumes data transmission in accordance with TXOP 512 (S408, S409, S410, S416, S417, S418). After receiving the additional group address frame, STA 102 may return an Ack frame on link 104, in which case data transmission will resume on link 103 after the Ack frame.

[0061] Fig. 6 is a sequence diagram showing another example of processing by AP 101 and STA 102 according to this embodiment, and Fig. 4 will also be referred to in the following description. Fig. 6 shows a case where a Beacon is received on a certain link in a multi-link (link 103 and link 104), but the timing of receiving the Beacon is shifted due to channel congestion. In the example of Fig. 6, no additional group address frame is transmitted following the Beacon. Link 103 and link 104 are a combination of links that cannot transmit and receive at the same time.

[0062] 5, STA102 is transmitting (uploading) data on link 103 in accordance with its own TXOP 611. Meanwhile, on link 104, for example, STA105 (see FIG. 1) is transmitting a data frame to an AP other than AP 101, and a NAV period 621 is set. STA102 is scheduled to receive a Beacon on link 104 at the original Beacon reception timing 631. When the Beacon reception timing 631 approaches (Yes in S401), STA102 temporarily suspends the data upload (S402).

[0063] If the STA 102 knows the length of the NAV period 621 of the link 104 and that the NAV period 621 does not overlap with the timing of receiving a Beacon on the link 103, the STA 102 may continue transmitting data (TXOP 611) until the end of the NAV period 621. The consideration of this point is as described above.

[0064] Timing 632 indicates the timing at which the STA102 stops waiting for frame reception when it does not receive a Beacon at the original Beacon reception timing 631 (No in S403) (timings 531 to 632 correspond to the scheduled time in S404). In FIG. 6, the STA102 receives a Beacon 622 from the AP 101 on the link 104 at timing 633 after the NAV period 621 ends before timing 632. The STA102 checks the TIM element (see TIM element 1300 in FIG. 13) included in the Beacon 622 and confirms that a group address frame is not transmitted following the Beacon (No in S405). Therefore, at the time of timing 634, the STA102 completes reception on the link 104. The STA102 then resumes data transmission according to the TXOP 612 (S408, S409, S410, S416, S417, S418). In this embodiment, the timing 632 does not need to be determined.

[0065] As described with reference to FIGS. 4 to 6, according to the first embodiment, even if the timing of receiving a Beacon from the AP 101 shifts, the STA 102 can continue transmitting data without simultaneously transmitting and receiving.

[0066] When the timing of a beacon transmission is shifted, the AP 101 sets the timing of the next beacon transmission to a period from the original timing of the beacon transmission. For example, consider a case where the beacon transmission interval (period) is 100TU, and the AP 101 first transmits a beacon at 0TU, and then transmits a beacon at 103TU. In this case, the AP 101 may set the timing of the next beacon transmission to be closer to 200TU. This is just one example, and the beacon transmission period may be set by a different method. The AP 101 may also set the next beacon to be transmitted to be closer to 203TU.

[0067] Also, the AP 101 may operate to align the Beacon transmission timings on the links 103 and 104. Accordingly, the Beacon reception timings on the links 103 and 104 may overlap in the STA 102. In this case, the STA 102 waits for transmission until the reception of the Beacon and the subsequent group address frame (if any) is completed on both the links 103 and 104. The STA 102 resumes frame transmission when the reception of the Beacon and the group address frame is completed on both links or when the STA 102 does not receive the Beacon by the time it stops waiting for reception. By aligning the timings at which the AP 101 transmits the Beacon, the STA 102 can reduce the period during which it waits for transmission of the data frame. As a result, the throughput of the STA 102 can be improved by aligning the Beacon transmission timings on the multi-links by the AP 101.

[0068] 5 and 6 (TXOP 511, 611), the STA 102 may receive an Ack frame or a Block Ack frame, which is a receipt confirmation, from the AP 101. When receiving these frames, the STA 102 may estimate the time to receive these frames with a margin and suspend the transmission. This allows the STA 102 to receive feedback on the transmission data at the timing of suspension, and allows the data to be quickly resent.

[0069] Example 2 In this embodiment, the STA 102 is c The following describes a case where an attempt to receive a beacon is not made on the target link when the on reception period has elapsed. In this embodiment, it is assumed that a beacon is received on link 104. The same applies to a situation where a beacon is received on link 103. The same applies to a situation where a beacon is received simultaneously on links 103 and 104. The same applies to a situation where an attempt is made to receive a beacon at the same time, but one of them fails to receive it. The contents that have already been explained in the previous embodiment will not be explained in this embodiment.

[0070] FIG. 7 is a flowchart showing the process of the STA 102 when the STA 102 receives a Beacon from the AP 101 on the link 104 in this embodiment. 7 The flowchart shown in the figure can be realized by the control unit 202 of the STA 102 executing a control program stored in the storage unit 201, and performing calculations and processing of information and control of each piece of hardware. The process shown in the flowchart can be started at the same time that the STA 102 establishes a connection with the AP 101 via a multi-link (link 103 and link 104 in this embodiment).

[0071] When the STA 102 is connected to the AP 101, the Beacon reception control unit 304 of the STA 102 determines whether the Beacon reception timing is approaching on any link, i.e., whether it is a predetermined time before the Beacon reception timing (S701). The predetermined time is 10 μsec in this embodiment, but this is just an example and may be 5 μsec or 20 μsec. In this embodiment, the Beacon reception timing is every 100 msec (i.e., Beacon interval = 100 msec), but it can be set to any interval such as every 150 msec.

[0072] If the timing of receiving a Beacon is approaching on any link (Yes in S701), the process proceeds to S702. Hereinafter, the link on which the timing of receiving a Beacon is approaching is referred to as the target link. In S702, the transmission control unit 303 of the STA102 causes the STA102 to refrain from data upload (UL) before the period of receiving a Beacon on the target link. That is, the STA102 does not perform data upload / data transmission during the period including the timing of receiving a Beacon. This means that if data upload is in progress, data upload is temporarily suspended on all links. Here, the links on which upload is suspended are all links that are a combination of links that cannot transmit and receive simultaneously. Therefore, for example, if a third link (not shown) that can transmit and receive simultaneously is established between the AP101 and the STA102, data upload does not need to be suspended on the third link.

[0073] Next, the Beacon reception control unit 304 of the STA102 waits for a certain period of time to receive a Beacon on the target link (S703). That is, the STA102 waits for a certain period of time from the original Beacon reception timing until the certain period of time has elapsed (hereinafter referred to as a first reception waiting period). In this embodiment, the first reception waiting period is 100 μsec, but this is an example and other time periods may be used. When the first reception waiting period has elapsed (Yes in S703), the transmission control unit 303 of the STA102 checks whether transmission data has accumulated in the transmission queue (S704). If transmission data has not accumulated (No in S704), the STA102 ends the process. If transmission data has accumulated (Yes in S704), the Beacon reception control unit 304 of the STA102 checks whether a Beacon has been received during the first reception waiting period (S705).

[0074] If a Beacon cannot be received during the first reception waiting period (No in S705), the wireless LAN control unit 301 of the STA 102 stops attempting to receive data on the target link (S709). In other words, the STA 102 gives up receiving data. If a Beacon is received during the first reception waiting period (Yes in S705), the process proceeds to S706, where the Beacon reception control unit 304 checks whether a group address frame is transmitted following the Beacon. This checking process is the same as S405 in FIG. 4.

[0075] If it is confirmed that a group address frame is transmitted following the Beacon (Yes in S706), the process proceeds to S707, and if not (No in S706), the process proceeds to S710. In S707, the wireless LAN control unit 301 of the STA102 confirms whether or not an additional group address frame following the Beacon has been received. The wireless LAN control unit 301 waits for the reception of the additional group address frame for a predetermined period after receiving the Beacon (S708). In this embodiment, the period (hereinafter referred to as the second reception waiting period) is 100 μsec, but this is an example and other time periods may be used. If the group address frame cannot be received even after the second reception waiting period has elapsed (Yes in S708), the STA102 stops attempting to receive data on the target link (S709), and the process proceeds to S710. Also, if the group address frame can be received during the second reception waiting period (Yes in S707), the process proceeds to S710. In S710, the transmission control unit 303 of the STA 102 sets a back-off counter in the link for transmission (S710), similarly to S409 in Fig. 4. The processes from S711 to S719 are similar to the processes from S410 to S418 in Fig. 4, and therefore will not be described.

[0076] The confirmation of whether or not the group address frame has been received in S707 may be confirmation by STA 102 of whether or not there is a frame addressed to itself. Also, if it is known that the group address frame has already been received on a link other than the target link (the link on which the Beacon is to be received), for example, link 103, STA 102 may determine that it will not receive a group address frame following the Beacon, and proceed to the process of S710.

[0077] Next, a series of processing flows of the AP 101 and the STA 102 according to this embodiment will be described with reference to Figs. 8 to 10. Fig. 8 is a sequence diagram showing an example of processing of the AP 101 and the STA 102 according to this embodiment, and Fig. 7 will also be referred to in the following description. Fig. 8 shows a case where a Beacon is received on a certain link in a multi-link (link 103 and link 104), but the timing of receiving the Beacon is shifted due to channel congestion. Furthermore, Fig. 8 shows a case where an additional group address frame was scheduled to be received following the Beacon, but the frame could not be received within a specified period. Link 103 and link 104 are a combination of links that cannot transmit and receive simultaneously.

[0078] 5 described in the first embodiment, STA102 transmits (uploads) data on link 103 in accordance with its own TXOP 811. Meanwhile, on link 104, for example, STA105 (see FIG. 1) is transmitting a data frame to an AP other than AP 101, and a NAV period 821 is set. STA102 is scheduled to receive a Beacon on link 104 at the original Beacon reception timing 831. When the Beacon reception timing 831 approaches (Yes in S701), STA102 temporarily suspends the data upload (S702).

[0079] If the STA 102 knows the length of the NAV period 821 of the link 104 and knows that the NAV period 821 does not overlap with the timing of receiving a Beacon on the link 103, the STA 102 may continue transmitting data (TXOP 811) until the end of the NAV period 821. Considerations regarding this point are as described in the first embodiment.

[0080] If the STA 102 knows the length of the NAV period 821 of the link 104 and knows that the NAV period 821 does not overlap with the period during which a Beacon is received on the link 103, the STA 102 may continue transmitting data (TXOP 811) until the end of the NAV period 621. The consideration of this point has been described above.

[0081] Timing 832 indicates the timing at which, when a Beacon is received, the STA102 stops waiting to receive a group address frame following the Beacon (the period from timing 833 to timing 832 corresponds to the second reception waiting period in S708 of FIG. 7). In FIG. 8, at timing 833 after the previous NAV period 821 ends due to timing 832, the STA102 receives a Beacon 822 from the AP 101 on the link 104. The AP 101 transmits an additional group address frame 823 following the Beacon 822. However, since the second reception waiting period has elapsed between the transmission of the Beacon 822 and the additional group address frame 823, the STA102 receives the Beacon 822 on the link 104 but does not receive a frame during period 824 after timing 832 (Not Received). Instead, the STA102 resumes data transmission on the link 103 in accordance with the TXOP 812 (No in S707, Yes in S708). 、 The AP 101 completes the transmission of the additional group address frame 823 at timing 834. However, the STA 102 ignores the reception of this group address frame and transmits a data frame on the link 103.

[0082] Fig. 9 is a sequence diagram showing another example of processing by the AP 101 and the STA 102 according to this embodiment, and Fig. 7 will also be referred to in the following description. Fig. 9 shows a case where a Beacon is received on a certain link in a multi-link (link 103 and link 104), but the timing of receiving the Beacon is shifted due to channel congestion. In the example of Fig. 9, no additional group address frame is transmitted following the Beacon. Link 103 and link 104 are a combination of links that cannot transmit and receive at the same time.

[0083] 8, STA102 is transmitting (uploading) data on link 103 in accordance with its own TXOP 911. Meanwhile, on link 104, for example, STA105 (see FIG. 1) is transmitting a data frame to an AP other than AP 101, and a NAV period 921 is set. STA102 is scheduled to receive a Beacon on link 104 at the original Beacon reception timing 931. When STA102 approaches the Beacon reception timing 931 (Yes in S701), it temporarily suspends the data upload (S702).

[0084] If the STA 102 knows the length of the NAV period 921 of the link 104 and knows that the NAV period 921 does not overlap with the timing of receiving a Beacon on the link 103, the STA 102 may continue transmitting data (TXOP 911) until the end of the NAV period 921. Considerations regarding this point are as described in the first embodiment.

[0085] Timing 932 indicates the timing to stop waiting for reception of a Beacon (the period from the original Beacon reception timing 931 to timing 932 corresponds to the first reception waiting period of S703 in FIG. 7). In FIG. 9, STA102 receives Beacon922 from AP101 on link 104 at timing 933, which is before timing 932. Since no additional group address frames follow Beacon922, STA102 completes reception on link 104 at timing 934. Therefore, STA102 then resumes data transmission according to TXOP912 (No in S706, S710, S711, S717, S718, S719).

[0086] Fig. 10 is a sequence diagram showing another example of processing by AP 101 and STA 102 according to this embodiment, and Fig. 7 will also be referred to in the following description. Fig. 10 shows a case where a beacon is received on a certain link in a multi-link (link 103 and link 104), but the timing of receiving the beacon is shifted due to channel congestion. Fig. 10 also shows a case where a beacon was scheduled to be received, but the beacon could not be received within a specified period. Link 103 and link 104 are a combination of links that cannot transmit and receive at the same time.

[0087] 8, STA102 is transmitting (uploading) data on link 103 in accordance with its own TXOP 1011. Meanwhile, on link 104, for example, STA105 (see FIG. 1) is transmitting a data frame to an AP other than AP 101, and a NAV period 1021 is set. STA102 is scheduled to receive a Beacon on link 104 at the original Beacon reception timing 1031. When the Beacon reception timing 1031 approaches (Yes in S701), STA102 temporarily suspends the data upload (S702).

[0088] If the STA 102 knows the length of the NAV period 1021 of the link 104 and knows that the NAV period 1021 does not overlap with the timing of receiving a Beacon on the link 103, the STA 102 may continue transmitting data (TXOP 1011) until the end of the NAV period 1021. Considerations regarding this point are as described in the first embodiment.

[0089] Timing 1032 indicates the timing to stop waiting for reception of a Beacon (the period from the original Beacon reception timing 1031 to timing 1032 corresponds to the first reception waiting period of S703 in FIG. 7). Regardless of whether a Beacon is received, the STA 102 resumes data transmission according to TXOP 1012 when timing 1032 has passed (the first reception waiting period has elapsed) (No in S705, S709, S710, S711, S717, S718, S719). In FIG. 10, Beacon 1022 is transmitted from AP 101 at timing 1033, later than the time of timing 1032. Beacon transmission ends at timing 1034. However, since the STA 102 is currently transmitting data on the link 103, it cannot receive the Beacon 1022 on the link 104 during the period 1024 (Not Received) corresponding to the TXOP.

[0090] 7 to 10, according to the second embodiment, even if the timing of receiving a Beacon from the AP 101 is shifted, the STA 102 prioritizes data transmission over receiving a Beacon. This allows the STA 102 to transmit a data frame to the AP 101 as quickly as possible even if congestion differs depending on the link, and as a result, communication delay caused by the STA 102 can be reduced.

[0091] Example 3 In the first and second embodiments, the AP 101 transmits a Beacon and the STA 102 receives it. However, the frame to be transmitted may be any group address frame that is periodically transmitted. For example, the frame may be a Trigger frame defined by TWT (Target Wake Time), a technology for power saving that conforms to the IEEE802.11 series of standards. In this embodiment, the operation will be described using TWT as an example.

[0092] Fig. 11 is a sequence diagram showing an example of processing by the AP 101 and the STA 102 according to this embodiment. Fig. 11 shows an example of a case where the Trigger frame is transmitted from the AP 101 during a reception waiting period, although the reception of the Trigger frame deviates from the timing / period in which it should be received (hereinafter also referred to as the Trigger reception timing). That is, this is similar to the processing example described in relation to Figs. 5 to 6. The Trigger reception timing can be acquired by the STA 102 based on predetermined information.

[0093] STA102 is transmitting (uploading) data on link 103 in accordance with its own TXOP 1111. Meanwhile, on link 104, for example, STA105 (see FIG. 1) is transmitting a data frame to an AP other than AP 101, and a NAV period 1121 is set. STA102 is scheduled to receive a Trigger frame on link 104 at the original Trigger reception timing 1131. As the Trigger reception timing 1131 approaches, STA102 temporarily suspends data uploading.

[0094] If the STA 102 knows the length of the NAV period 1121 of the link 104 and knows that the NAV period 1121 does not overlap with the timing of receiving a Trigger on the link 103, the STA 102 may continue transmitting data (TXOP 1111) until the end of the NAV period 1121. Considerations regarding this point are as described in the first embodiment.

[0095] Timing 1132 indicates the timing to stop waiting for reception of the Trigger frame and the subsequent frames. STA102 receives the Trigger frame 1122 on the link 104 at timing 1133. In response, STA102 returns a PS Poll (Power Save Poll) frame or a U-APSD (Unscheduled Automatic Power-Save Delivery) frame 1123 on the link 104. The AP 101 sees the returns from each STA and transmits a DL MU PPDU (Downlink Multi-user Physical layer Protocol Data Unit) frame 1124. This frame is addressed to multiple STAs including STA102. After receiving the DL MU PPDU frame 1124, STA102 returns a Block Ack frame 1125. STA102 resumes data transmission (TXOP 1112) at timing 1134 when the return of the Block Ack frame 1125 ends. If there is retransmission of data from the AP 101, the STA 102 waits until the retransmission is completed before resuming data transmission.

[0096] Fig. 12 is a sequence diagram showing another example of processing by the AP 101 and the STA 102 according to this embodiment. Fig. 12 shows an example in which the reception of a Trigger frame deviates from the Trigger timing and the reception waiting period has elapsed. In other words, this is similar to the processing example described in relation to Figs. 8 to 10.

[0097] STA102 is transmitting (uploading) data on link 103 in accordance with its own TXOP 1211. Meanwhile, on link 104, for example, STA105 (see FIG. 1) is transmitting a data frame to an AP other than AP 101, and a NAV period 1221 is set. STA102 is scheduled to receive a Trigger frame on link 104 at the original Trigger reception timing 1231. As the Trigger reception timing 1231 approaches, STA102 temporarily suspends data uploading.

[0098] If the STA 102 knows the length of the NAV period 1221 of the link 104 and knows that the NAV period 1221 does not overlap with the timing of receiving a Trigger on the link 103, the STA 102 may continue transmitting data (TXOP 1211) until the end of the NAV period 1221. Considerations regarding this point are as described in the first embodiment.

[0099] Timing 1232 indicates the timing to stop waiting for receipt of a trigger frame. Regardless of whether or not a trigger frame is received, STA 102 resumes data transmission (TXOP 1212) when timing 1232 has passed. In FIG. 12, a trigger frame 1222 is transmitted from AP 101 at timing 1233, which is later than timing 1232. The trigger frame and the subsequent data transmission and reception procedure end at timing 1234. However, since STA 102 is transmitting data via link 103, it is unable to receive a trigger frame via link 104 during period 1223 (Not Received).

[0100] In the above-described embodiment, the AP 101 and the STA 102 are assumed to access channels by EDCA (Enhanced Distributed Channel Access). However, the means for solving the problem are not limited to this. For example, the AP 101 may allow only Trigger frame-based UL communication from the connected STA. In this case, the channel is assigned so that there is no UL data when a Beacon is received on another link. This makes it possible for the STA to avoid overlapping the Beacon reception period and frame transmission.

[0101] In the second embodiment, if the STA 102 fails to receive a Beacon multiple times, it may transmit a message to that effect to the AP 101 and establish a link at a different frequency. This allows the link to be established in an uncongested environment, reduces delays in receiving the Beacon, and is expected to improve throughput by transmitting and receiving data over the link.

[0102] In this way, according to the embodiment described above, in a multi-link system, an STA configured to be unable to receive on one link while transmitting on another link controls the transmission operation even if the timing of an incoming group address frame such as a beacon is shifted, thereby making it possible to continue communication without wasting frequency resources.

[0103] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0104] The invention is not limited to the above-described embodiments, and various modifications and variations are possible 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]

[0105] 100 network, 101 communication device (AP), 102 communication device (STA), 103 link, 104 link, 105 communication device (STA)

Claims

1. A communication device that complies with the IEEE 802.11 series standard and is capable of performing multi-link communication with another communication device using multiple links having different frequency channels, a receiving means for receiving a first frame conforming to the IEEE 802.11 series standard from the other communication device via a first link of the plurality of links; an acquisition means for acquiring information on reception timing of the first frame at a predetermined interval in the communication device, the first frame being transmitted from the other communication device, based on the first frame; a transmitting means for transmitting a second frame conforming to the IEEE 802.11 series standard via a second link among the plurality of links, a second period during which the first frame is received, and a second period during which the first frame is received, the second period being a first period from the reception timing to the start of reception of the first frame, the second period being a second period during which the first frame is received, the second period being a first period from the reception timing to the start of reception of the first frame, and the second period being a second period during which the first frame is received, the second period being a

2. 2. The communication device according to claim 1, wherein the transmitting means temporarily suspends the transmission of the second frame during the first period after starting the transmission of the second frame on the second link, and resumes the transmission of the second frame on the second link in response to the reception of the first frame by the receiving means.

3. a determination means for determining, when the first frame is received by the receiving means in a state in which the transmission of the second frame is temporarily suspended by the transmitting means during the first period and the second period, whether or not a third frame that conforms to the IEEE 802.11 series standard and is different from the first frame is present, based on the first frame; 3. The communication device according to claim 2, characterized in that, when the determination means determines that the third frame is present, the transmission means resumes transmission of the second frame in response to the reception of the first frame and the third frame by the receiving means.

4. 4. The communication device according to claim 3, wherein the first frame and the third frame are group address frames.

5. A communication device that complies with the IEEE 802.11 series standard and is capable of performing multi-link communication with another communication device using multiple links having different frequency channels, a receiving means for receiving a first frame conforming to the IEEE 802.11 series standard from the other communication device via a first link of the plurality of links; an acquisition means for acquiring information on reception timing of the first frame at a predetermined interval in the communication device, the first frame being transmitted from the other communication device, based on the first frame; a transmitting means for transmitting a second frame conforming to the IEEE 802.11 series standard via a second link among the plurality of links, The transmitting means is not transmitting the second frame during a first period including the reception timing; a second frame transmitted over the second link after the first period has elapsed if the first period has elapsed without the first frame being received by the receiving means.

6. The transmitting means is after starting transmission of the second frame on the second link, suspending transmission of the second frame during the first period; 6. The communication device according to claim 5, wherein, if the first period has elapsed without the first frame being received by the receiving means, transmission of the second frame is resumed after the first period has elapsed.

7. a determination means for determining, when the first frame is received by the receiving means in a state in which the transmission of the second frame by the transmitting means is temporarily suspended during the first period, whether or not a third frame that conforms to the IEEE 802.11 series standard and is different from the first frame is present, based on the first frame; 7. The communication device according to claim 6, characterized in that when the determination means determines that the third frame is present and a second period has elapsed from the timing when the first frame was received without the third frame being received by the receiving means, the transmitting means resumes transmitting the second frame after the second period has elapsed.

8. 8. The communication device according to claim 7, wherein the first frame and the third frame are group address frames.

9. The communication device according to any one of claims 1 to 8, characterized in that the transmitting means is capable of transmitting the second frame via the second link during a NAV (Network Allocation Vector) period set for the communication device and the other communication device via the first link.

10. 10. The communication device according to claim 1, wherein the first frame is a Beacon frame in which a Group Bit in a MAC Address field is set to 1.

11. 10. The communication device according to claim 1, wherein the first frame is a Trigger frame in which a Group Bit in a MAC Address field is set to 1.

12. A communication device that complies with the IEEE 802.11 series standard and is capable of performing multi-link communication with another communication device using multiple links having different frequency channels, a receiving means for receiving a first frame conforming to the IEEE 802.11 series standard from the other communication device via a first link of the plurality of links; an acquisition means for acquiring information on reception timing of the first frame at a predetermined interval in the communication device, the first frame being transmitted from the other communication device, based on the first frame; a transmitting means for transmitting a second frame conforming to the IEEE 802.11 series standard via a second link among the plurality of links, a second period during which the first frame is received, the second period being a period during which the first frame is received, when the first frame is received after a first period has elapsed from the reception timing, the second period being a period during which the first frame is received ...

13. 13. The communication device according to claim 12, wherein the transmitting means temporarily suspends the transmission of the second frame during the first period after starting the transmission of the second frame on the second link, and resumes the transmission of the second frame on the second link in response to the reception of the first frame by the receiving means.

14. a determination means for determining, when the first frame is received by the receiving means in a state in which the transmission of the second frame is temporarily suspended by the transmitting means during the first period and the second period, whether or not a third frame that conforms to the IEEE 802.11 series standard and is different from the first frame is present, based on the first frame; 14. The communication device according to claim 13, characterized in that, when the determination means determines that the third frame is present, the transmission means resumes transmission of the second frame in response to the reception of the first frame and the third frame by the reception means.

15. 15. The communication device according to claim 12, wherein the first period is a period from the reception timing to the next reception timing until the first frame is received.

16. A method for controlling a communication device that is compliant with the IEEE 802.11 series standard and capable of performing multi-link communication with another communication device using a plurality of links having different frequency channels, comprising the steps of: a receiving step of receiving a first frame conforming to the IEEE 802.11 series standard from the other communication device via a first link of the plurality of links; an acquisition step of acquiring information on reception timing of the first frame at a predetermined interval in the communication device, the first frame being transmitted from the other communication device, based on the first frame; a transmitting step of transmitting a second frame conforming to the IEEE 802.11 series standard via a second link of the plurality of links; A control method characterized in that, in the transmitting step, the second frame is not transmitted during a first period from the reception timing to start of reception of the first frame and during a second period during which the first frame is being received.

17. A method for controlling a communication device that is compliant with the IEEE 802.11 series standard and capable of performing multi-link communication with another communication device using a plurality of links having different frequency channels, comprising the steps of: a receiving step of receiving a first frame conforming to the IEEE 802.11 series standard from the other communication device via a first link of the plurality of links; an acquisition step of acquiring information on reception timing of the first frame at a predetermined interval in the communication device, the first frame being transmitted from the other communication device, based on the first frame; a transmitting step of transmitting a second frame conforming to the IEEE 802.11 series standard via a second link among the plurality of links, In the transmitting step, not transmitting the second frame during a first period including the reception timing; a second frame being transmitted over the second link after the first period has elapsed if the first frame has not been received and the first period has elapsed.

18. A method for controlling a communication device that is compliant with the IEEE 802.11 series standard and capable of performing multi-link communication with another communication device using a plurality of links having different frequency channels, comprising the steps of: a receiving step of receiving a first frame from the other communication device via a first link conforming to the IEEE 802.11 series standard among the plurality of links; an acquisition step of acquiring information on reception timing of the first frame at a predetermined interval in the communication device, the first frame being transmitted from the other communication device, based on the first frame; a transmitting step of transmitting a second frame conforming to the IEEE 802.11 series standard via a second link among the plurality of links, A control method characterized in that, in the transmitting step, when the first frame is received after a first period has elapsed from the reception timing, the second frame is not transmitted during a second period during which the first frame is received.

19. A program for causing a computer to execute the method for controlling a communication device according to any one of claims 16 to 18.

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