Communication device, method for controlling communication device, and program for the same

Abstract

To provide a communication device, a method for controlling a communication device, and a program that, when there is an exchange of a plurality of start frames with a communication device of the other party before the start of enhanced multi-link multi-radio (EMLMR) operations, properly control operations in the EMLMR link.SOLUTION: In a radio communication system, a method comprises: detection means that detects, in a period from reception of a first start frame for starting a frame exchange sequence through a first EMLMR link from another communication device until transmission of a response frame thereto, reception of a second start frame for starting a frame exchange sequence through a second EMLMR link different from the first EMLMR link; and control means that, when the detection means detects the reception of the second start frame in the period, controls to continue the frame exchange sequence through the first EMLMR link or the second EMLMR link.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a communication device that performs wireless communication, a control method for the communication device, and a program therefor. [Background technology]

[0002] With the recent increase in the amount of data being communicated, development of communication technologies such as wireless local area networks (LANs) 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, the latest standard, IEEE 802.11ax, uses orthogonal frequency division multiple access (OFDMA) to standardize technology that not only achieves a high peak throughput of up to 9.6 gigabits per second (Gbps) but also improves communication speeds under congested conditions (see Patent Document 1). OFDMA stands for Orthogonal Frequency Division Multiple Access.

[0003] A task group called IEEE802.11be was established as a successor standard aiming to further improve throughput, frequency utilization efficiency, and communication latency.

[0004] IEEE802.11be is considering multi-link communication, in which one AP and one STA (Station) establish multiple links using frequency bands such as 2.4GHz, 5GHz, and 6GHz, and communicate simultaneously. In multi-link communication, the AP is called an AP MLD (Access point multi-link device), and the STA is called a non-AP MLD (non-Access point multi-link device).

[0005] In addition, IEEE 802.11be is considering Enhanced multi-link multi-radio (EMLMR) operation in multi-link communication. A non-AP MLD operating in EMLMR mode performs an initial frame exchange with the number of spatial streams according to the per-link spatial stream capability of the EMLMR link, and then operates as follows until the end of the frame exchange sequence on the link where the initial frame exchange took place: It receives a physical layer convergence protocol data unit (PPDU) with the number of spatial streams up to the value indicated in the EMLMR SUPPORTED MCS AND NSS SET subfield of the Common Info field of the Basic variant Multi-Link element, and transmits a PPDU with the number of spatial streams indicated in the EMLMR SUPPORTED MCS AND NSS SET subfield. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-50133 Summary of the Invention [Problem to be solved by the invention]

[0007] After the start of the initial frame exchange on a specific EMLMR link, that is, between the reception of the initiation frame for starting the frame exchange sequence and the start of transmission of the response frame, the operation when another initiation frame is received on another EMLMR link is not taken into consideration. Therefore, if multiple initiation frames are exchanged with the other communication device during that time, it is necessary to properly control the operation in EMLMR mode.

[0008] The present invention aims to appropriately control operation in EMLMR mode when multiple start frames are exchanged with the other communication device during that time. [Means for solving the problem]

[0009] The communication device of the present invention is a communication device that operates as a Multi-Link Device compliant with the IEEE 802.11 series standard, and is characterized by comprising: a detection means that detects that a second initiation frame for initiating a frame exchange sequence on a second EMLMR link different from the first EMLMR link is received from the other communication device during a period from when the communication device receives a first initiation frame for initiating a frame exchange sequence on a first EMLMR (Enhanced multi-link multi-radio) link to when the communication device transmits a response frame to the first initiation frame; and a control means that, when the detection means detects that the second initiation frame has been received during the period, controls to continue the frame exchange sequence on the first EMLMR link or the second EMLMR link. [Effects of the Invention]

[0010] According to the present invention, when a plurality of start frames are exchanged with a communication device that is a counterpart before the start of EMLMR operation, it is possible to appropriately control operation in EMLMR mode. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a network configuration according to the present invention. [Figure 2] FIG. 2 is a diagram illustrating a hardware configuration of a communication device according to the present invention. [Figure 3] FIG. 2 is a diagram illustrating a functional configuration of a communication device according to the present invention. [Figure 4] FIG. 1 is a diagram illustrating an overview of Multi-Link communication. [Figure 5]10A is a diagram showing a Basic variant Multi-Link element included in an Association Request frame, and FIG. 10B is a diagram showing an EMLMR Capabilities subfield included in a Common Info field of the Basic variant Multi-Link element. [Figure 6] 10 is a flowchart of a process performed to start a frame exchange sequence on an EMLMR link in the present invention. [Figure 7] 10 is a flowchart of a process performed to start a frame exchange sequence on an EMLMR link in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the configurations shown in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

[0013] (Wireless communication system configuration) 1 shows the configuration of a network searched by a communication device 101 (hereinafter referred to as Non-AP MLD 101) according to this embodiment. A communication device 102 (hereinafter referred to as AP MLD 102) is an access point (AP) that serves to construct a wireless network 100. The AP MLD 102 can communicate with the Non-AP MLD 101. This embodiment is applied to the Non-AP MLD 101 and the AP MLD 102.

[0014] Each of the non-AP MLD 101 and the AP MLD 102 can perform wireless communication compliant with the IEEE 802.11be (EHT) standard. IEEE stands for Institute of Electrical and Electronics Engineers. The non-AP MLD 101 and the AP MLD 102 can communicate in the 2.4 GHz, 5 GHz, and 6 GHz frequency bands. The frequency bands used by each communication device are not limited to these, and different frequency bands, such as the 60 GHz band, may be used. The non-AP MLD 101 and the AP MLD 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 different bandwidths, such as 240 MHz and 4 MHz, may be used.

[0015] The Non-AP MLD 101 and AP MLD 102 perform OFDMA communications compliant with the IEEE802.11be standard, enabling multi-user (MU) communications by multiplexing signals from multiple users. OFDMA stands for Orthogonal Frequency Division Multiple Access. In OFDMA communications, portions of the divided frequency band (RU, Resource Unit) are assigned to each STA without overlapping, and the carrier waves of each STA are orthogonal. This allows the AP to communicate with multiple STAs in parallel within a specified bandwidth.

[0016] Generally, the range of radio waves varies depending on the frequency; the lower the frequency, the greater the diffraction and the longer the reach, while the higher the frequency, the less diffraction and the shorter the reach. Even if there is an obstacle along the way, low-frequency radio waves can go around the obstacle and reach their destination, but high-frequency radio waves have a high degree of directivity and are difficult to go around, so they may not reach their destination. On the other hand, the 2.4 GHz frequency is often used by other devices, and microwave ovens are known to emit radio waves in the same frequency band. As such, even when radio waves are emitted by the same device, the strength of the radio waves that reach the destination and the signal-to-noise (SN) ratio can vary depending on the frequency band and the location and environment in which they are placed.

[0017] Although the non-AP MLD 101 and the AP MLD 102 are described as being compatible with the IEEE 802.11be standard, they may also be compatible with legacy standards that predate the IEEE 802.11be standard. Specifically, the non-AP MLD 101 and the AP MLD 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), NFC, UWB, ZigBee, and MBOA. UWB stands for Ultra Wide Band, and MBOA stands for Multi Band OFDM Alliance. NFC stands for Near Field Communication. UWB includes wireless USB, wireless 1394, WiNET, and the like. They may also be compatible with wired communication standards such as wired LAN. Specific examples of the AP MLD 102 include, but are not limited to, a wireless LAN router and a personal computer (PC).

[0018] The AP MLD 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. Specific examples of the non-AP MLD 101 include, but are not limited to, a camera, a tablet, a smartphone, a PC, a mobile phone, a video camera, and a headset. The non-AP MLD 101 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. Each communication device can communicate using bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz, and 320 MHz.

[0019] The non-AP MLD 101 and AP MLD 102 also perform multi-link communication, establishing links and communicating via multiple frequency channels. In the IEEE 802.11 series of standards, the bandwidth of each frequency channel is defined as 20 MHz except for the 60 GHz band, which is defined as 2.16 GHz. Here, a frequency channel refers to a frequency channel defined in the IEEE 802.11 series of standards, and the IEEE 802.11 series of standards defines multiple frequency channels for each of the 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz frequency bands. Note that a single frequency channel may utilize a bandwidth of 40 MHz or more by bonding adjacent frequency channels.

[0020] For example, the AP MLD 102 is capable of establishing a link and communicating with the non-AP MLD 101 via a first frequency channel in the 2.4 GHz band. In parallel with this, the non-AP MLD 101 is capable of establishing a link and communicating with the AP MLD 102 via a second frequency channel in the 5 GHz band. In this case, the non-AP MLD 101 performs multi-link communication, maintaining a second link via the second frequency channel in parallel with the link via the first frequency channel. In this way, the AP MLD 102 can improve the throughput of communication with the non-AP MLD 101 by establishing links with the non-AP MLD 101 via multiple frequency channels.

[0021] In multi-link communication, multiple links using different frequency bands may be established between communication devices. For example, the non-AP MLD 101 may be able to establish links in the 2.4 GHz, 5 GHz, and 6 GHz bands. Alternatively, links may be established via multiple different channels within the same frequency band. For example, a link on channel 6 in the 2.4 GHz band may be established as the first link, and a link on channel 1 in the 2.4 GHz band may be established as the second link. Links using the same frequency band and links using different frequency bands may be mixed. For example, the non-AP MLD 101 may be able to establish a first link on channel 6 in the 2.4 GHz band, as well as a link on channel 1 in the 2.4 GHz band and a link on channel 149 in the 5 GHz band. By establishing multiple connections using different frequencies between the non-AP MLD 101 and the AP, even if one band is congested, communication with the non-AP MLD 101 can be established in another band. This prevents degradation of throughput and communication delays in communication with the non-AP MLD 101.

[0022] Although the wireless network in Figure 1 has one AP MLD and one non-AP MLD, the number and placement of AP MLDs and non-AP MLDs are not limited to this. For example, one non-AP MLD may be added to the wireless network in Figure 1. In this case, the frequency band of each link to be established, the number of links, and the frequency width are not important.

[0023] When performing multi-link communication, the AP MLD 102 and the non-AP MLD 101 transmit and receive data to and from the other device via multiple links. Data may be transmitted and received via one of the links that make up the multi-link.

[0024] Furthermore, the AP MLD 102 and the non-AP MLD 101 may be capable of performing MIMO (Multiple-Input and Multiple-Output) communication. In this case, the AP MLD 102 and the non-AP MLD 101 each have multiple antennas, and each antenna transmits a different signal 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 from each stream. By performing MIMO communication in this way, the AP MLD 102 and the non-AP MLD 101 can communicate more data in the same amount of time than if they did not perform MIMO communication. Furthermore, when performing multi-link communication, the AP MLD 102 and the non-AP MLD 101 may perform MIMO communication on some of the links.

[0025] (Configuration of AP MLD and Non-AP MLD) 2 shows an example of the hardware configuration of the non-AP MLD 101 in this embodiment. The non-AP MLD 101 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. Note that there may be multiple antennas.

[0026] The storage unit 201 is configured with 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 stands for Read Only Memory, and RAM stands for Random Access Memory. In addition to memories such as ROM and RAM, the storage unit 201 may also use 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. Furthermore, the storage unit 201 may include multiple memories.

[0027] The control unit 202 is configured with one or more processors such as a CPU or MPU, and controls the entire Non-AP MLD 101 by executing a computer program stored in the storage unit 201. The control unit 202 may also control the entire Non-AP MLD 101 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 (wireless frames) to be transmitted in communications with other communication devices. The CPU stands for Central Processing Unit, and the MPU stands for Micro Processing Unit. The control unit 202 may also be equipped with multiple processors such as multi-core processors, and the entire Non-AP MLD 101 may be controlled by the multiple processors.

[0028] Furthermore, the control unit 202 controls the function unit 203 to perform predetermined processes such as wireless communication, image capture, printing, projection, etc. The function unit 203 is hardware that enables the non-AP MLD 101 to perform predetermined processes.

[0029] 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 from the output unit 205 may be a display on a monitor screen, an audio output from a speaker, a vibration output, or the like. Note that both the input unit 204 and the output unit 205 may be implemented in a single module, such as a touch panel. Furthermore, the input unit 204 and the output unit 205 may be integrated with the Non-AP MLD 101, or may be separate units.

[0030] The communication unit 206 controls wireless communication conforming to the IEEE 802.11be standard. The communication unit 206 may also control wireless communication conforming to other IEEE 802.11 series standards in addition to the IEEE 802.11be standard, and may 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.

[0031] If the non-AP MLD 101 supports the NFC standard, Bluetooth standard, or the like in addition to the IEEE802.11be standard, it may control wireless communications in accordance with these communication standards. Furthermore, if the non-AP MLD 101 can perform wireless communications in accordance with multiple communication standards, it may be configured to have separate communication units and antennas compatible with each communication standard. The non-AP MLD 101 communicates data such as image data, document data, and video data with the non-AP MLD 101 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.

[0032] Antenna 207 is an antenna capable of communication in the 2.4 GHz band, 5 GHz band, and 6 GHz band. In this embodiment, non-AP MLD 101 has one antenna, but it may have three antennas. Alternatively, it may have a different antenna for each frequency band. Furthermore, if non-AP MLD 101 has multiple antennas, it may have a communication unit 206 corresponding to each antenna.

[0033] The AP MLD 102 has the same hardware configuration as the non-AP MLD 101 .

[0034] 3 is a block diagram showing the functional configuration of the non-AP MLD 101 in this embodiment. The AP MLD 102 has a similar configuration. Here, the non-AP MLD 101 is assumed to include a wireless LAN control unit 301. The number of wireless LAN control units is not limited to one, and may be two, or three or more. The non-AP MLD 101 further includes a frame processing unit 302, an EMLMR management unit 303, a UI control unit 304, a storage unit 305, and a wireless antenna 306.

[0035] The wireless LAN control unit 301 includes an antenna and circuitry for transmitting and receiving wireless signals to and from other wireless LAN devices, as well as a program for controlling them. The wireless LAN control unit 301 controls wireless LAN communications based on frames generated by the frame processing unit 302 in accordance with the IEEE 802.11 standard series.

[0036] The frame processing unit 302 processes wireless control frames transmitted and received by the wireless LAN control unit 301. The contents of the wireless control generated and analyzed by the frame processing unit 302 may be restricted by settings stored in the storage unit 305. They may also be changed by user settings from the UI control unit 304. The information on the generated frame is sent to the wireless LAN control unit 301 and transmitted to the communication partner. The information on the frame received by the wireless LAN control unit 301 is passed to the frame processing unit 302 and analyzed.

[0037] The EMLMR management unit 303 performs management control to determine which links are EMLMR links, including the establishment of EMLMR links and the deletion of EMLMR links. Establishing an EMLMR link refers to the state in which an EMLMR link is specified when or after Multi-Link is established. Deleting an EMLMR link refers to canceling the state of a link specified as an EMLMR link.

[0038] The UI control unit 304 is configured to include hardware related to a user interface, such as a touch panel or buttons, for accepting operations by a user (not shown) of the Non-AP MLD 101 on the Non-AP MLD 101, and a program for controlling these. The UI control unit 304 also has a function for presenting information, such as displaying images or outputting audio, to the user.

[0039] The storage unit 305 is a storage device that can be configured with a ROM, a RAM, etc., that stores programs and data that the Non-AP MLD 101 runs on.

[0040] Figure 4 shows the configurations of AP MLD and Non-AP MLD for Multi-Link communication.

[0041] A communication device that operates in Multi-Link is called an MLD (Multi-Link Device), and one MLD has multiple STAs and APs (Access Points) associated with each Link. An MLD with AP functionality is called an AP MLD, and an MLD without AP functionality is called a Non-AP MLD.

[0042] 4, AP1 401 and STA1 404 establish Link1 407 over a first frequency channel. Similarly, AP2 402 and STA2 405 establish Link2 408 over a second frequency channel, and AP3 403 and STA3 406 establish Link3 409 over a third frequency channel.

[0043] Here, AP MLD and non-AP MLD establish connections via frequency channels in the sub-GHz band, 2.4 GHz band, 3.6 GHz band, 4.9 and 5 GHz bands, 60 GHz band, and 6 GHz band. AP MLD and non-AP MLD maintain a second link connection via a second frequency channel in parallel with a first link connection via a first frequency channel. Furthermore, instead of establishing connections via different frequency bands, multiple connections via different frequency channels in the same frequency band may be established.

[0044] Link1, Link2, and Link3 are each assigned a number of spatial streams according to the per-link spatial stream capability. Assuming six antennas are present, each link uses two antennas. In other words, the spatial stream capability of each link is "2." As described below, if Link1, Link2, and / or Link3 are EMLMR links, the spatial stream capability of Link1 during EMLMR operation is "4" or "6," while that of Link2 and / or Link3 is "0." As a result, Link1 can transmit and receive multiple pieces of data, or multiple different pieces of data, at the same time and frequency using multiple antennas to avoid spatial interference. The number of spatial streams is determined by the EHT Capabilities element or EHT Operation element included in the frame declaring that no-AP MLD supports EHT. Specifically, it is determined based on the value of the Supported EHT-MCS and NSS Set field or the Basic EHT-MCS and NSS Set field included in the EHT Capabilities element or the EHT Operation element.

[0045] Figure 5(a) shows the Basic variant Multi-Link element in an Association Request frame. Figure 5(b) shows the EMLMR Capabilities subfield included in the Common Info field of the Basic variant Multi-Link element. A value of "0" in the EMLMR Support field indicates non-support of EMLMR, while a value of "1" indicates support of EMLMR. When Multi-Link communication is established, all links establish EMLMR links. The Basic variant Multi-Link element is described as being included in the Association Request frame when establishing Multi-Link, but it may also be included in probe request frames, probe response frames, association response frames, Beacon frames, etc.

[0046] An EMLMR link is established by transmitting, receiving, or exchanging a frame containing an EMLMR Support subfield with a value of 1 on each link that constitutes Multi-Link. At this time, an EMLMR link may be established on only some of the links that constitute Multi-Link by transmitting, receiving, or exchanging a frame containing an EMLMR Support subfield with a value of 1 on one link, thereby establishing an EMLMR link on only those links. Alternatively, an EMLMR link may be established on multiple links, including other links, by transmitting, receiving, or exchanging a frame containing an EMLMR Support subfield with a value of 1 on one link. In this case, an EMLMR link may be established on all of the links that constitute Multi-Link, or on only some of the links. To specify the link on which an EMLMR link is to be established, information for identifying the link on which the EMLMR link is to be established may be included in a frame containing an EMLMR Support subfield with a value of 1, thereby specifying the link on which the EMLMR link is to be established. Information that can be used to identify the link includes the link identifier (ID), the basic service set identifier (BSSID) corresponding to the link, the traffic identifier (TID), etc.

[0047] The EMLMR Supported MCS and NSS Set subfield indicates the maximum number of spatial streams for transmitting and receiving PPDUs during EMLMR operation. When a specific link operates in EMLMR mode, the number of spatial streams assigned to links other than the link operating in EMLMR is reduced, allowing the specific link to transmit and receive PPDUs with an increased number of spatial streams.

[0048] Although the establishment of an EMLMR link is instructed when Multi-Link is established, the establishment of an EMLMR link can also be specified in the Action frame sent after Multi-Link is established. In this case, a frame called an EML (Enhanced Multi-Link) Operating Mode Notification frame can be prepared to instruct the establishment of an EMLMR link. For example, in the case of Non-AP MLD, when a frame containing an EMLMR Support subfield with a value of 1 is received and an EML Operating Mode Notification frame containing an EMLMR Mode subfield with a value of 1 is sent, the link that sent and received those frames establishes an EMLMR link. Alternatively, some or all of the other links that make up the Multi-link can establish an EMLMR link. Also, in the case of AP MLD, when a frame containing an EMLMR Support subfield with a value of 1 is sent and an EML Operating Mode Notification frame containing an EMLMR Mode subfield with a value of 1 is received, the link that sent and received those frames establishes an EMLMR link. Alternatively, some or all of the other links that make up the Multi-link can establish an EMLMR link. In this case, the link to be established may be specified by including information for identifying the link to be established in the EML Operating Mode Notification frame. The information for identifying the link may include a link identifier (ID), a basic service set identifier (BSSID) corresponding to the link, a traffic identifier (TID), etc.

[0049] Although it has been explained that non-AP MLD is the one that establishes the EMLMR link, the establishment of the EMLMR link can also be instructed by AP MLD. Note that the EML Operating Mode Notification frame is an Action frame that non-AP MLD sends to operate in EMLMR mode, and it must be sent if an EMLMR link is not established when Multi-Link communication is established, or if the EMLMR link is established but then deleted, in order to operate in EMLMR mode.

[0050] Next, the behavior of the AP MLD 102 when operating in EMLMR mode and exchanging frames after establishing an EMLMR link will be described using Figures 6 and 7. The main body of the following behavior is the behavior of the frame processing unit 302 or the EMLMR control unit 303, but the behavior of the communication device is the behavior of the AP MLD 102. Therefore, the main body of the behavior hereafter will be the control unit 202 of the communication device. Note that this behavior may also be performed by a non-AP MLD 101.

[0051] First, the operation when transmitting a start frame will be explained using Figure 6. Because the frame exchange sequence begins when the start frame is transmitted, the present invention expresses that an EMLMR link operating as EMLMR continues the frame exchange sequence. In S0, the control unit 202 determines that there is data to be transmitted to the communication device that is the communication partner. The data to be transmitted may be data requested to be transmitted from any communication device to the communication device that is the communication partner, or data generated by the function unit 203.

[0052] In S1, the control unit 202 determines whether multiple EMLMR links have been established. For example, if not only Link1 but also Link2 have been established, the determination is Yes, and if only Link1 has been established, the determination is No. A possible method for checking whether multiple EMLMR links have been established is to determine whether each of the multiple links has transmitted and received a frame including an EMLMR Support subfield with a value of 1. Another possible method is to determine whether each of the multiple links has transmitted a frame including an EMLMR Support subfield with a value of 1 and received an EML Operating Mode Notification frame including an EMLMR Mode subfield with a value of 1. Alternatively, whether multiple EMLMR links have been established may be checked by performing the above determination on any of the links constituting the multi-link, rather than on each of the multiple links.

[0053] In this case, frames including an EMLMR Support subfield with a value of 1 and information for identifying the link on which the EMLMR link is to be established may be exchanged, and if there are multiple links for which the information for identifying the link matches in the frames transmitted by both parties, it may be determined that multiple EMLMR links have been established. Here, in the case of non-AP MLD, an EML Operating Mode Notification frame including information for identifying the link on which the EMLMR link is to be established may be transmitted instead of a frame including an EMLMR Support subfield and information for identifying the link on which the EMLMR link is to be established. In the case of AP MLD, an EML Operating Mode Notification frame including information for identifying the link on which the EMLMR link is to be established may be received instead of a frame including an EMLMR Support subfield and information for identifying the link on which the EMLMR link is to be established.

[0054] If the determination in S1 is No, the process proceeds to S8. In S8, the control unit 202 transmits a start frame via the EMLMR link. The start frame of the EMLMR link is the frame that is transmitted first in the frame exchange sequence defined in Annex G of the IEEE 802.11 standard. For example, there is an RTS (Request To Send) frame or an MU-RTS Trigger frame. This start frame is an instruction to start frame exchange on the EMLMR link after the EMLMR link is established.

[0055] In S9, the control unit 202 determines whether a response frame has been received. A response frame of an EMLMR link is a frame transmitted as a response from a communication device that has received an initiation frame in a frame exchange sequence defined in Annex G of the IEEE 802.11 standard. For example, a CTS (Clear To Send) frame is one example.

[0056] In S10, the control unit 202 starts a frame exchange sequence with the maximum number of spatial streams indicated in the EMLMR SUPPORTED MCS AND NSS SET subfield of the Common Info field of the Basic variant Multi-Link element transmitted by the non-AP MLD before the start of this flow. As a result, one EMLMR link operates as an EMLMR. In S17, it is determined whether the frame exchange sequence has ended, and the process ends if the determination is Yes. The explanation up to this point is based on the assumption of normal EMLMR operation.

[0057] Next, we will explain the behavior when S1 returns Yes, i.e., when multiple EMLMR links are established. In S2, it is determined whether the conditions for transmitting a start frame over multiple EMLMR links are met based on predicted communication performance. A possible method for predicting communication performance is to estimate the congestion level of the channel corresponding to each link, i.e., the number of non-AP MLDs connected to the AP MLD. Another possible method is to measure the received signal strength and / or signal-to-noise power ratio of each link to predict the communication performance of each link. For example, if the channel of one of Link1 and Link2 is significantly more congested than the other link or the received signal strength is low, both links cannot be operated well, so the system transitions to S8 to enable EMLMR operation for either Link1 or Link2. However, if the channels of Link1 and Link2 are equally congested or sufficiently clear, or the received signal strength is low or sufficiently high, EMLMR operation is unlikely to improve communication performance, so the system transitions to S3 to transmit and receive data using the number of spatial streams according to the spatial stream capabilities of each link.

[0058] In S3, the control unit 202 transmits a start frame on multiple EMLMR links. However, the number of spatial streams specified here is the number of spatial streams according to the spatial stream capability of each link. That is, the number is determined by the EHT Capabilities element or EHT Operation element included in the frame that declares that non-AP MLD supports EHT. Other links that do not establish an EMLMR link are not links on which frame exchange sequences are performed.

[0059] In S4, the control unit 202 determines whether a response frame has been received on at least one EMLMR link. If a response frame has not been received within a specific period, it determines that a frame exchange sequence will not be executed on the EMLMR link and ends the process. On the other hand, if a response frame has been received, the process transitions to S5. In S5, the control unit 202 determines whether a response frame has been received on multiple EMLMR links. If the determination in S5 is No, the process transitions to S10. If the determination in S5 is Yes, the process transitions to S6. In S6, the control unit 202 executes frame exchange on the EMLMR link on which the response frame has been received, with the number of spatial streams according to the spatial stream capability for each link. In S7, it determines whether the frame exchange sequence has ended, and ends the process if the determination is Yes.

[0060] Next, the operation when receiving a start frame will be explained using FIG. 7. Steps numbered in FIG. 7 that overlap with those numbered in FIG. 6 have already been explained in FIG. 6, and therefore will not be explained again. In S11, this flow is executed after the control unit 202 receives a start frame on an EMLMR link. In S12, the control unit 202 detects whether or not another start frame has been received on an EMLMR link other than the selected EMLMR link during the period from when it starts receiving the start frame to when it starts transmitting a response frame. If the answer is No in S12, the process proceeds to S18. In S18, the control unit 202 transmits a response frame in response to the received start frame. The rest of the process is as explained in FIG. 6.

[0061] If the answer in S12 is Yes, the process proceeds to S13. In S13, it is determined whether the conditions for transmitting a response frame over multiple EMLMR links are met based on the predicted communication performance. As with S2, the communication performance can be predicted based on the congestion level of the channel corresponding to each link, i.e., the number of non-AP MLDs connected to the AP MLD. Another possible method is to measure the received signal strength and / or signal-to-noise power ratio of each link to predict the communication performance of each link.

[0062] If the result of S13 is No, the process proceeds to S16. In S16, the control unit 202 selects one EMLMR link from among the EMLMR links that have transmitted or received the start frame, based on a predetermined criterion. The EMLMR operation is performed on the selected EMLMR link. The method of determining based on a predetermined criterion is as follows: There are roughly three methods of determination: (1) selection based on information for identifying the link (such as a link ID), (2) selection based on the order in which the EMLMR links were established, and (3) selection based on at least one of the communication performance (such as the congestion level of the channel corresponding to the link (the number of STAs connected to the AP)).

[0063] When selecting based on information for identifying the link (such as a link ID), the Link ID subfield of the Multi-Link element shown in Figure 5(a) is referenced and determined. A Link ID is an ID assigned to each link when a Multi-Link is established. When IDs are assigned in the order in which the link IDs are established, the link with the lowest link ID number among multiple EMLMR links is selected as the single EMLMR link. Alternatively, the link with the highest link ID number may be selected as the single EMLMR link.

[0064] When selecting based on the order in which the EMLMR links are established, more specifically, the selection is based on at least one of the following orders: - The order in which frames containing the EMLMR Support subfield with a value of 1 were sent The order in which a frame containing an EMLMR Support subfield with a value of 1 is received The sequence in which frames containing an EMLMR Support subfield with a value of 1 were sent and received The order in which EML Operating Mode Notification frames containing an EMLMR Mode subfield with a value of 1 were sent (for non-AP MLD) The order in which an EML Operating Mode Notification frame containing an EMLMR Mode subfield with a value of 1 is received (in the case of AP MLD) The order in which a frame containing an EMLMR Support subfield with a value of 1 is received and an EML Operating Mode Notification frame containing an EMLMR Mode subfield with a value of 1 is sent (in the case of non-AP MLD) - The order in which a frame containing an EMLMR Support subfield with a value of 1 is sent and an EML Operating Mode Notification frame containing an EMLMR Mode subfield with a value of 1 is received (in the case of AP MLD) If the frame contains information for identifying a link for establishing an EMLMR link, the EMLMR link identified by the information may be selected based on the order in which the information is sent or received.The EMLMR link identified by the information may also be selected based on the order in which the transmitted information for identifying a link for establishing an EMLMR link matches the received information.

[0065] According to this order, an order value is assigned to each EMLMR link starting from 1. In other words, the EMLMR link with a link order of 1 is the EMLMR link selected based on a predetermined criterion. For example, when selecting an EMLMR link in the order in which frames containing an EMLMR Support subfield with a value of 1 are received, if it is assumed that the AP MLD receives a frame containing an EMLMR Support subfield with a value of 1 on Link 1 and then on Link 2, Link 1 is assigned an order value of 1, and therefore Link 1 is selected. Note that, as will be described in other embodiments, when selecting multiple EMLMR links, they are selected in ascending order up to a predetermined value at which an EMLMR link can be established.

[0066] When selecting based on communication performance, the congestion level of the channel corresponding to each EMLMR link is measured, and the EMLMR link with the lowest congestion level is selected. Measurement methods include determining the number of STAs connected to the AP, and calculating the channel occupancy rate for each Multi-Link link.

[0067] If the determination in S13 is Yes, the process proceeds to S14. In S14, the control unit 202 transmits response frames over the multiple EMLMR links over which the start frame was received, and the process proceeds to S15. In S15, the control unit 202 executes frame exchange in the EMLMR links over which the response frame was transmitted, with the number of spatial streams according to the spatial stream capability for each link. In S7, it is determined whether the frame exchange sequence has ended, and the process ends if the determination is Yes.

[0068] In the first embodiment, a method for appropriately controlling operation in EMLMR mode when multiple start frames are exchanged with the other communication device before EMLMR operation starts has been described. A specific method for appropriately controlling is a control method for performing frame exchange over one EMLMR link or multiple EMLMR links, depending on whether the frame exchange sequence is to be exchanged over multiple EMLMR links. The frame exchange sequence continues over the selected EMLMR link, and if there is an EMLMR link that has not been selected, the frame exchange sequence over that EMLMR link is temporarily stopped.

[0069] [Other Examples] In the first embodiment, in S5 of Fig. 6, it is determined whether a response frame was received on multiple EMLMR links, and depending on the result, the process proceeds to either step S6 or S10. However, S5 may be skipped. In this case, it is determined in S4 whether a response frame was received on at least one EMLMR link, and if the result is Yes, the process proceeds to step S6.

[0070] Although the first embodiment discloses a method for selecting one EMLMR link, multiple EMLMR links may be operated in EMLMR mode. For example, assume that four links, Link1 to Link4, are formed between a communication device and a counterpart communication device. When Link1 and Link2 are operated as EMLMR links, a method may be used in which the spatial stream of Link3 is assigned to Link1 and the spatial stream of Link4 is assigned to Link2. As a result, the number of spatial streams of Link1 and Link2 increases, and conversely, the number of spatial streams of Link3 and Link4 decreases. Since such a case is conceivable, if multiple EMLMR links exist that increase the number of spatial streams, multiple EMLMR links may be selected according to a predetermined criterion in S8 of FIG. 6 and S16 of FIG. 7. Then, in S9 of Fig. 6, it is determined whether a response frame has been received on each selected EMLMR link, and in S10, the EMLMR operation is performed on each EMLMR link that has received the response frame. Also, in S18 of Fig. 7, a response frame is transmitted on each selected EMLMR link, and in S10, the EMLMR operation is performed on each EMLMR link that has transmitted the response frame.

[0071] In Example 1, when selecting based on the order in which the EMLMR links were established, the selection was made from the lowest order, but the selection may also be made from the highest order, or the middle order may be selected first.

[0072] Although the first embodiment has been described as a Basic variant Multi-Link element, it may be a Basic Multi-Link element, and the EMLMR Supported MCS And NSS Set subfield may be an EMLMR Rx NSS subfield and an EMLMR Tx NSS subfield. In this case, the EMLMR Rx NSS subfield indicates the maximum number of spatial streams for reception, and the EMLMR Tx NSS subfield indicates the maximum number of spatial streams for transmission.

[0073] It is also possible to provide a system or device with a recording medium on which program code for software that realizes the above-described functions is recorded, and have the computer (CPU, MPU) of the system or device read and execute the program code stored on the recording medium. In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiments, and the recording medium on which the program code is stored constitutes the above-described device.

[0074] Examples of storage media that can be used to supply the program code include flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, ROMs, and DVDs.

[0075] In addition, the above-mentioned functions may be realized not only by the computer executing the read program code, but also by the operating system (OS) running on the computer performing some or all of the actual processing based on the instructions of the program code. OS is an abbreviation for Operating System.

[0076] Furthermore, the program code read from the storage medium is written into a memory provided on a function expansion board inserted into the computer or a function expansion unit connected to the computer. Then, based on the instructions of the program code, a CPU provided in the function expansion board or function expansion unit may perform some or all of the actual processing to realize the above-mentioned functions.

[0077] 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. [Explanation of symbols]

[0078] 201 Storage section 202 Control section 203 Functional Department 204 Input section 205 Output section 206 Communications Department

Claims

1. A communication device that operates as a multi-link device conforming to the IEEE 802.11 series standard, a detection means for detecting that a second initiation frame for starting a frame exchange sequence on a second EMLMR (Enhanced multi-link multi-radio) link different from the first EMLMR link has been received from the other communication device during a period from when the other communication device receives a first initiation frame for starting a frame exchange sequence on a first EMLMR link to when the other communication device transmits a response frame to the first initiation frame; and control means for controlling the first EMLMR link or the second EMLMR link to continue a frame exchange sequence when the detection means detects that the second start frame has been received during the period.

2. The communication device according to claim 1, characterized in that the control means controls the frame exchange sequence to continue in the first EMLMR link or the second EMLMR link based on a link ID assigned to each link in the multi-link communication.

3. The communication device according to claim 1, characterized in that the control means controls to continue the frame exchange sequence in the first EMLMR link or the second EMLMR link based on the order in which each link in the multi-link communication establishes an EMLMR link.

4. The communication device according to claim 1, characterized in that the control means controls to continue the frame exchange sequence in the first EMLMR link or the second EMLMR link based on the communication performance of each link in the multi-link communication.

5. 5. The communication device according to claim 1, wherein when the control means controls to continue the frame exchange sequence in the first EMLMR link, the control means controls to continue the frame exchange sequence with a number of spatial streams whose maximum value is a value defined in an EMLMR SUPPORTED MCS AND NSS SET subfield of the own device or the other communication device operating as a non-AP MLD.

6. The communication device according to any one of claims 1 to 5, characterized in that, when the control means controls to start a frame exchange sequence in the second EMLMR link, the control means controls to continue the frame exchange sequence with a number of spatial streams whose maximum value is a value defined in an EMLMR SUPPORTED MCS AND NSS SET subfield of the own device or the other communication device operating as a non-AP MLD.

7. 7. The communication device according to claim 1, wherein the control means deletes the EMLMR link that has undergone the frame exchange sequence when the frame exchange sequence is completed.

8. A communication device that operates as a multi-link device conforming to the IEEE 802.11 series standard, a detection means for detecting that a second initiation frame for starting a frame exchange sequence on a second EMLMR (Enhanced multi-link multi-radio) link different from the first EMLMR link has been received from the other communication device during a period from when the other communication device receives a first initiation frame for starting a frame exchange sequence on a first EMLMR link to when the other communication device transmits a response frame to the first initiation frame; and control means for controlling, when the detection means detects that the second start frame has been received during the period, to execute a frame exchange sequence with the number of spatial streams for each link assigned to each of the first EMLMR link and the second EMLMR link.

9. A control method for a communication device that operates as a multi-link device conforming to the IEEE 802.11 series standard, comprising: a detection step of detecting that a second initiation frame for initiating a frame exchange sequence on a second EMLMR (Enhanced multi-link multi-radio) link different from the first EMLMR link has been received from the other communication device during a period from when the other communication device receives a first initiation frame for initiating a frame exchange sequence on a first EMLMR link to when the other communication device transmits a response frame to the first initiation frame; and a control step of controlling to continue a frame exchange sequence on the first EMLMR link or the second EMLMR link when the detection step detects that the second start frame has been received during the period.

10. A control method for a communication device that operates as a multi-link device conforming to the IEEE 802.11 series standard, comprising: a detection step of detecting that a second initiation frame for initiating a frame exchange sequence on a second EMLMR (Enhanced multi-link multi-radio) link different from the first EMLMR link has been received from the other communication device during a period from when the other communication device receives a first initiation frame for initiating a frame exchange sequence on a first EMLMR link to when the other communication device transmits a response frame to the first initiation frame; a control step of controlling to execute a frame exchange sequence with the number of spatial streams for each link assigned to each of the first EMLMR link and the second EMLMR link when the detection step detects that the second start frame has been received during the period.

11. A program for causing a computer to function as each of the means of the communication device according to any one of claims 1 to 8.

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