Communication device and control method for same

Abstract

This communication device operates as a sharing AP in a multi-AP coordination configuration, and comprises: a transmission means that transmits a sounding signal in the multi-AP coordination configuration; a reception means that receives a response signal which includes a reception result from each of a plurality of STAs that have received the sounding signal; and a determination means that, on the basis of the reception results, determines transmission power control and beamforming propriety for an AP that constructs a BSS to which each of the plurality of STAs belongs.

Description

Communication device and control method thereof

[0001] The present invention relates to communication control in cooperative operation of a plurality of access points.

[0002] In recent years, development of communication technologies such as wireless local area networks (LANs) has progressed. The IEEE 802.11 series of standards is known as the main communication standard for wireless LANs. The IEEE 802.11 series of standards includes standards such as IEEE 802.11a / b / g / n / ac / ax / be. In addition, the IEEE 802.11bn Task Group (TG) is currently working on a successor standard.

[0003] The IEEE 802.11be standard (hereinafter referred to as the 11be standard) newly defines a multi-AP cooperative configuration in which multiple access points (APs) operate cooperatively in order to improve throughput. The IEEE 802.11bn standard (hereinafter referred to as the 11bn standard) is studying ways to improve communication reliability in a multi-AP cooperative configuration. To efficiently operate a cooperative configuration, a sounding procedure is typically performed between the access point (AP) and the station (STA). However, the current 11be standard does not define a sounding procedure in a multi-AP cooperative configuration.

[0004] Patent Literature 1 proposes a technique in which multiple APs transmit null data packets (NDPs) as "sounding packets," and STAs that receive the sounding packets transmit feedback packets containing channel conditions (CQIs, etc.) to the APs. It also proposes that the APs utilize the received feedback information to realize cooperative beamforming and cooperative MIMO.

[0005] Special Publication No. 2020-515112

[0006] The IEEE 802.11 series standard defines a spatial reuse (SR) function that uses spatial isolation to communicate over the same frequency and channel in order to improve frequency utilization efficiency. However, the sounding procedure in a multi-AP cooperative configuration is not defined, making it difficult to effectively utilize the SR function.

[0007] The present invention has been made in view of such problems, and provides a technique for effectively using the SR function in a multi-AP cooperative configuration.

[0008] In order to solve the above-mentioned problems, a communication device according to the present invention has the following configuration: That is, the communication device conforms to the IEEE 802.11 series standard and operates as a sharing AP in a multi-AP cooperative configuration in which it operates in cooperation with other access points (APs), and includes: a transmitting means for transmitting a sounding signal in the multi-AP cooperative configuration, a receiving means for receiving a response signal including a reception result from each of a plurality of stations (STAs) that have received the sounding signal, and a determining means for determining whether to perform transmit power control and beamforming in an AP that forms a basic service set (BSS) to which each of the plurality of STAs belongs, based on the reception result.

[0009] In addition, a communication device that complies with the IEEE 802.11 series standards and operates as a shared AP in a multi-AP cooperative configuration that operates in cooperation with other access points (APs) comprises: a transmitting means that transmits a sounding signal based on a first instruction from a sharing AP in the multi-AP cooperative configuration; and a receiving means that receives a second instruction regarding transmit power control and whether beamforming is possible in the communication device from the sharing AP that has received a response signal including a reception result from each of a plurality of stations (STAs) that have received the sounding signal.

[0010] According to the present invention, a technique for effectively using the SR function in a multi-AP cooperative configuration can be provided. Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar components are designated by the same reference numerals.

[0011] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments of the present invention, and are used together with the description to explain the principles of the present invention.

[0023] Figure 1 is a diagram showing the overall configuration of a system in a first embodiment. Figure 2 is a diagram showing the hardware configuration of an AP device and an STA device. Figure 3 is a diagram showing the functional configuration of an AP device. Figure 4 is a diagram explaining the operational concept of cooperative SR. Figure 5 is a diagram showing a timing chart of sounding in cooperative SR. Figure 6 is a flowchart showing the operation when an AP starts communication. Figure 7 is a flowchart showing the operation of an AP (in the case of a shared AP). Figure 8 is a flowchart showing the operation of an AP (in the case of a sharing AP). Figure 9 is a diagram showing an example format of a trigger frame.

[0012] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0013] (First Embodiment) As a first embodiment of a wireless communication device according to the present invention, an access point device based on the IEEE 802.11 series standard will be described below as an example. Note that IEEE is an abbreviation for Institute of Electrical and Electronics Engineers.

[0014] 1 is a diagram showing the overall configuration of a system in the first embodiment. For ease of explanation, only a portion including two access points (AP) 102 and 105 is shown.

[0015] The APs 102 and 105 are communicatively connected via a backhaul 100. The backhaul is a communication path for interconnecting a basic service set (BSS) established by the AP with other networks when the AP establishes a distributed system (DS). The backhaul 100 is implemented by wired communications such as Ethernet (registered trademark) or telephone lines, or wireless communications such as Long Term Evolution (LTE) or WiMAX (Worldwide Interoperability for Microwave Access). Furthermore, the backhaul 100 may be a wireless LAN compliant with the IEEE 802.11 series standards. In this case, the wireless channel used between the APs 102 and 105 and the stations (STAs) may be the same or different.

[0016] BSS 101 is a BSS established by AP 102, and its coverage area is exemplarily indicated by a two-dot chain circle. BSS 104 is a BSS established by AP 105, and its coverage area is exemplarily indicated by a dashed circle.

[0017] AP 102 is an access point having a multi-AP cooperative configuration function. Here, the multi-AP cooperative configuration function is a function that cooperates with other APs to realize faster or more stable communication and improved frequency utilization efficiency for connected STAs than when using a single AP. These methods include JTX (Joint Transmission) using D-MIMO (Distributed Multiple Input Multiple Output), null steering, cooperative OFDMA, fractional cooperative OFDMA, and cooperative SR (Coordinated Spatial Reuse). Similarly, AP 105 is an access point having a multi-AP cooperative configuration function. Note that when the multi-AP cooperative configuration function is not being executed, AP 102 manages only BSS 101, and AP 105 manages only BSS 104.

[0018] STAs 103 and 106 are wireless LAN terminals. These STAs are capable of data communication with multiple APs. Here, data communication includes at least communication used in sounding processing. The sounding processing includes receiving an "NDP announcement," an "NDP," and a "Beamforming Report Poll (BFRP)," and transmitting "Compressed Beamforming / CQI" that includes a CQI report field.

[0019] The AP 102, AP 105, STA 103, and STA 105 are configured to be capable of transmitting and receiving wireless frames compliant with the 11bn standard, which is the successor to the 11be standard. The 11bn standard's main features are highly reliable communication, low latency communication, and improved throughput during congestion. The 11bn standard also aims to reduce power consumption in the AP. FIG. 2 is a diagram showing a hardware configuration that can be applied to both the AP and the STA. An example of the hardware configuration includes 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.

[0020] The storage unit 201 is configured with memories such as ROM and RAM, and stores various information such as 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 also be used as the storage unit 201. Furthermore, the storage unit 201 may be configured with multiple memories of the same or different types.

[0021] The control unit 202 is configured with, for example, a processor such as a CPU or MPU, an ASIC (application-specific integrated circuit), a DSP (digital signal processor), an FPGA (field programmable gate array), etc. Here, CPU is an acronym for central processing unit, and MPU is an acronym for microprocessing unit. The control unit 202 controls each part of the device by executing a program stored in the storage unit 201. Note that the control unit 202 may be configured to control each part of the device in cooperation with the program stored in the storage unit 201 and an OS (operating system). The control unit 202 may also be configured with multiple processors, such as homogeneous / heterogeneous multi-core processors.

[0022] The functional unit 203 executes functions as an AP (or STA). A configuration may be adopted in which some or all of the functions of the functional unit 203 are realized by the control unit 202. The functional unit 203 may also be configured to include hardware for executing predetermined processes such as imaging, printing, and projection.

[0023] The input unit 204 receives various operations from the user. The output unit 205 outputs various types of information to the user. Here, the output by the output unit 205 includes at least one of display on a screen, audio output by a speaker, vibration output, etc. Note that both the input unit 204 and the output unit 205 may be implemented by a single module, such as a touch panel.

[0024] The communication unit 206, which is a wireless communication unit, controls wireless communication conforming to the 11bn standard, wireless communication conforming to Wi-Fi (registered trademark), and IP (Internet Protocol) communication. Furthermore, the communication unit 206 controls the antenna 207 to transmit and receive wireless signals for wireless communication. The antenna 207 is configured to be capable of beamforming transmission under the control of the communication unit 206. While only one antenna is shown in FIG. 11 for simplification, a configuration having multiple antennas (e.g., a number of antennas corresponding to the number of streams) may also be used. Furthermore, a configuration capable of using multiple frequency bands (e.g., 2.4 GHz band, 5 GHz band, 6 GHz band) may also be used.

[0025] 3 is a diagram showing the functional configuration of the AP device (APs 102 and 105). The AP device includes a wireless LAN control unit 301, a UI control unit 302, a storage unit 303, a configuration selection unit 304, a single AP configuration control unit 305, a multi-AP configuration control unit 306, a beamforming control unit 307, a schedule control unit 308, and an antenna 309.

[0026] The wireless LAN control unit 301 includes circuits for transmitting and receiving wireless signals to and from other wireless LAN devices (e.g., other APs or STAs) and programs for controlling these circuits. The wireless LAN control unit 301 generates frames and transmits and receives frames in accordance with the IEEE 802.11 series standards, and executes wireless LAN communication control.

[0027] The UI control unit 302 is configured to include hardware related to a user interface (UI), such as a touch panel or buttons, for accepting operations on the AP device by a user (not shown) of the AP device, and a program for controlling these. The UI control unit 302 also has a function for presenting information to the user via functions such as image display and audio output.

[0028] The storage unit 303 includes storage devices such as a read-only memory (ROM) and a random access memory (RAM) that store programs executed by the AP device and various data.

[0029] The configuration selection unit 304 is a functional unit that selects a communication configuration (single-AP configuration or multi-AP cooperative configuration) depending on the presence of surrounding APs, the capabilities of the surrounding APs, and the connection status between the surrounding APs and STAs. The single-AP configuration control unit 305 is a control unit that allows each AP device to communicate with STAs independently when the multi-AP cooperative configuration is not in operation. The multi-AP configuration control unit 306 is a control unit that controls the configuration of cooperative SR when the multi-AP cooperative configuration is used.

[0030] The beam forming control unit 307 is a control unit that controls beam forming and null steering in the antenna 309. The schedule control unit 308 is a control unit that schedules the operation of the multi-AP cooperative configuration.

[0031] <Device Operation> Figure 4 is a diagram explaining the operational concept of cooperative SR in a multi-AP cooperative configuration. Cooperative SR is a configuration in which adjacent BSSs communicate with each other using the same channel in the same frequency band, thereby improving frequency utilization efficiency. However, using the same channel in the same frequency band can result in a decrease in communication quality due to interference. For example, Figure 4 illustrates a situation in which interference is avoided by narrowing the communication area of ​​BSS 104 relative to BSS 101, and this control is achieved by controlling the transmission power of each AP. In this case, AP 102 operates as a sharing AP that manages the cooperative function. Meanwhile, AP 105 operates as a shared AP that operates under the control of AP 102, which is the sharing AP.

[0032] AP 102 cooperates with AP 105 to transmit sounding signals to STA 103 and STA 106. STA 103 and STA 106 derive channel quality indicators (CQIs) indicating channel conditions from the received sounding signals and report them to AP 102 and AP 105. The CQIs at this time are signal-to-noise ratios (SNRs).

[0033] AP 102, which is a sharing AP, controls the transmission power of AP 102 and AP 105 based on the reported CQI. In the example of FIG. 4, the path loss between AP 102 and STA 103 is large due to factors such as the distance between them, and a low SNR is fed back from STA 103. In this case, AP 102 cannot reduce its transmission power. On the other hand, the path loss between AP 105 and STA 106 is small due to factors such as the close distance between them, and a high SNR is fed back from STA 106. In this case, AP 105 can determine that communication is possible even if it reduces its transmission power. AP 102 and AP 105 control their transmission power so that their respective transmission powers do not interfere with STAs outside their respective BSSs.

[0034] 5 is a timing chart of sounding in cooperative SR. First, AP 102, which is a sharing AP, transmits a sounding trigger frame (TF) 501 to AP 105, which is a shared AP. Then, AP 102 transmits an NDP announcement frame 502 to STA 103, and AP 105 transmits an NDP announcement frame 503 to STA 106.

[0035] Thereafter, AP 102 transmits sounding NDP 504, and AP 105 transmits sounding NDP 505. The sounding NDP is transmitted at the maximum transmission power that the AP can transmit. STA 103 and STA 106 calculate the SNR based on the received sounding NDP. Note that the "maximum transmission power" is a transmission power preset for each AP and is within the transmission power limits imposed by law.

[0036] Note that the SNR calculation for thermal noise and environmental noise does not provide information used for transmission power control in cooperative SR. Therefore, the SNR calculation at each STA must be performed assuming that another BSS communicating on the same channel in the same frequency band exists nearby.

[0037] Therefore, STA 103 calculates the SNR based on the received power of the sounding NDP transmitted from AP 105. STA 106 also calculates the SNR based on the received power of the sounding NDP transmitted from AP 102. Note that sounding NDPs 504 and 505 are transmitted at different times, and STA 103 and STA 106 distinguish between in-BSS and out-of-BSS sounding NDPs, and calculate the SNR, which is the ratio of the received power intensities of the two NDPs, using the following formula (1): SNR = in-BSS sounding received power / out-BSS sounding received power (1)

[0038] The return (report) of the sounding result from each STA is triggered by the reception of a BFRP (Beamforming Report Poll) trigger frame (TF) 506 transmitted from AP 102, which is the sharing AP. After receiving BFRP_TF 506, STA 103 transmits a compressed beamforming / CQI frame 507 as a response signal to AP 102. After receiving BFRP_TF 506, STA 106 transmits a compressed beamforming / CQI frame 508 to AP 105. A beamforming-compatible AP can obtain information necessary for beamforming from the compressed beamforming / CQI frame including information on the reception result.

[0039] AP 102, which is a sharing AP, sets its own (AP 102) transmission power and the transmission power of AP 105 based on the SNR information reported by STAs 103 and 106. For example, if the SNR exceeds a predetermined threshold, it is determined that communication is possible with lowered transmission power, and control is performed to lower the transmission power. On the other hand, if the SNR is below the threshold, lowering the transmission power would further reduce the SNR, so transmission power control is not performed.

[0040] Table 1 shows an example of transmit power control based on the reported SNR. Here, the SNR threshold is set to 15 dB. Note that 15 dB is merely an example, and the threshold varies depending on the conditions under which cooperative SR is used. For example, for high-speed, high-capacity communications, it is necessary to set the SNR threshold higher.

[0041]

[0042] The operation for the four cases in Table 1 will be further explained.

[0043] Case 1: The SNRs of both STA 103 and STA 106 are above the threshold, and the environment is such that there are no problems with cooperative SR communication. In this case, it is determined that no transmission power control is performed and each AP transmits at its maximum transmission power.

[0044] Case 2: The SNR of STA 103 is below the threshold, and the SNR of STA 106 is above the threshold. In this case, STA 103 cannot reduce the received power, so AP 102 decides to transmit at maximum transmit power. On the other hand, STA 106 determines that it is possible to reduce the received power, so AP 105 decides to communicate by reducing the transmit power.

[0045] Case 3: The SNR of STA 103 exceeds the threshold, and the SNR of STA 106 falls below the threshold. In this case, STA 103 determines that it is possible to reduce the received power, and AP 102 determines to communicate by reducing the transmitted power. On the other hand, STA 106 cannot reduce the received power, so AP 105 determines to transmit at the maximum transmitted power.

[0046] Case 4: The SNR of both STA 103 and STA 106 is below the threshold, and neither AP 102 nor AP 105 can reduce the transmission power. Therefore, it is determined that AP 102 and AP 105 transmit at the maximum transmission power.

[0047] The power control amount is set based on the difference between the SNR threshold and the SNR value. Specifically, the power control amount is controlled to decrease the maximum transmission power. Power control amount = SNR measurement value - SNR threshold (2)

[0048] In the above equation (2), when the power control amount is negative, communication is performed at maximum transmission power, and when the power control amount is positive, the transmission power is reduced by that amount.

[0049] However, the above-described control is an operation that does not take beamforming into consideration, and additional control is required for APs that perform beamforming transmission. That is, sounding transmission is performed without beamforming, and therefore, performing beamforming on transmission power control based on the sounding results may result in a decrease in SNR. For example, interference power outside the BSS increases, resulting in a decrease in SNR for STAs in other BSSs. While this problem can be avoided by performing sounding with a beamformed signal, SNR measurement is required after beamforming, which increases overhead before communication begins. As a result, the increased overhead has the adverse effect of reducing communication capacity.

[0050] Considering the objective of cooperative SR, which is to improve frequency utilization efficiency, it can be considered that avoiding interference with other BSSs should be prioritized over improving the received signal power and SNR obtained by beamforming transmission. Therefore, in this embodiment, whether or not to perform beamforming transmission is determined depending on the status of transmission power control from sounding.

[0051] Table 2 shows an example of setting whether or not beamforming transmission is possible in the four cases shown in Table 1 above.

[0052]

[0053] Case 1: The SNRs of both STA103 and STA106 exceed the threshold, and it can be determined that there is little interference between BSSs. Because the SNRs are obtained at both, there is no need to further improve the SNRs by beamforming transmission. Performing beamforming transmission would only increase the possibility of interference. Therefore, both AP102 and AP105 decide not to perform beamforming transmission ("No").

[0054] Case 2: The SNR of STA103 is below the threshold, and the SNR of STA106 is above the threshold. In this case, as described above, AP105 is controlled to reduce its transmission power. In an environment (BSS104) where communication can be performed with reduced transmission power, beamforming is not required. On the other hand, reducing the transmission power of AP105 reduces the interference power with STA103 (in BSS101), improving the SNR of STA103. The advantage of AP102 performing beamforming transmission is that the SNR of STA103 improves. Therefore, AP102 determines that beamforming transmission may be performed ("OK"), and AP105 determines not to perform beamforming transmission.

[0055] Case 3: The SNR of STA 103 exceeds the threshold, and the SNR of STA 106 is below the threshold. In this case, as described above, AP 102 is controlled to reduce its transmission power. In an environment (BSS 101) where communication is possible with reduced transmission power, beamforming is not required. On the other hand, reducing the transmission power of AP 102 reduces the interference power with STA 106 (in BSS 104), improving the SNR of STA 106. The advantage of AP 105 performing beamforming transmission is that the SNR of STA 106 improves. Therefore, AP 102 decides not to perform beamforming transmission, and AP 105 decides that beamforming transmission may be performed.

[0056] Case 4: The SNR of both STA 103 and STA 106 is below the threshold. As described above, AP 102 and AP 105 do not control the transmission power. However, there is an advantage in that the SNR of each STA is improved by each AP performing beamforming transmission. Therefore, it is determined that both AP 102 and AP 105 may perform beamforming transmission.

[0057] Note that even if beamforming is determined to be "possible" in Table 2, beamforming is not performed during sounding, and therefore beamforming transmission may result in a decrease in SNR due to interference. Therefore, the final decision on whether to use beamforming transmission is made by AP 102 and AP 105, respectively.

[0058] As described above, compressed beamforming / CQI frames 507 and 508 are transmitted from STA 103 and STA 106 to AP 102 and AP 105, respectively. This enables AP 102 and AP 105 to estimate the arrival waves (directions of radio wave arrival) of STA 103 and STA 106 from these signals. The APs make a decision on beamforming transmission based on the results of this arrival wave estimation.

[0059] In Case 2 of Table 2, the AP 102 has determined that beamforming transmission is "possible," but there is a possibility that the SNR of the STA 106 will decrease due to the beamforming transmission. To avoid this, the result of the arrival wave estimation is used. That is, the AP 102 performs beamforming transmission to the STA 103, and at this time, the result of the arrival wave estimation of the STA 106 is referenced. If the result of the arrival wave estimation of the STA 103 and the STA 106 confirms that the STA 103 and the STA 106 are located in approximately the same direction (as seen from the AP 102), the beamforming transmission is stopped and transmission is performed using a single antenna. This makes it impossible to achieve an improvement in the SNR of the STA 103, but has the advantage of not causing a decrease in the SNR of the STA 106.

[0060] In Case 3 of Table 2, the AP 105 determines that beamforming transmission is "possible," but there is a possibility that the SNR of the STA 103 will decrease due to the beamforming transmission. To avoid this, the result of the arrival wave estimation is used. That is, the AP 105 performs beamforming transmission to the STA 106, but at this time, the result of the arrival wave estimation of the STA 103 is referenced. If the result of the arrival wave estimation of the STA 106 and the STA 103 confirms that the STA 106 and the STA 103 are located in approximately the same direction (as seen from the AP 105), the beamforming transmission is stopped and transmission is performed using a single antenna. This makes it impossible to achieve an improvement in the SNR of the STA 106, but has the advantage of not causing a decrease in the SNR of the STA 103.

[0061] In Case 4 of Table 2, similar to Cases 2 and 3, AP 102 and AP 105 determine whether to perform beamforming transmission or transmission using a single antenna based on the arrival wave estimation results of STA 103 and STA 106.

[0062] 6 is a flowchart showing the operation when the AP 102 starts communication. Here, processing starts when data to be transmitted to the STA 103 occurs in the AP 102.

[0063] In S601, the AP 102 determines whether to communicate (transmit) data to the STA 103 in a multi-AP cooperative configuration or a single-AP configuration. This determination may be made using a conventional determination method. If the communication is to be performed in a multi-AP cooperative configuration, the process proceeds to S602. On the other hand, if the communication is to be performed in a single-AP configuration, the communication is started in a single-AP configuration. If the communication is to be performed in a single-AP configuration, the above-mentioned transmission power control and beamforming feasibility determination are not necessary, and therefore detailed description thereof will be omitted.

[0064] In S602, the AP 102 starts communication in a multi-AP cooperative configuration. In S603, the AP 102 determines whether or not it (the AP 102) operates as a sharing AP. If it operates as a sharing AP, the process proceeds to S604. If it does not operate as a sharing AP (i.e., if it operates as a shared AP), the process proceeds to S800 (FIG. 8 described below).

[0065] In S604, the AP 102 transmits a sounding TF (first instruction) to the shared AP 105. Then, the process proceeds to S700 (FIG. 7, which will be described later).

[0066] FIG. 7 is a flowchart showing the operation of the AP 102, which is a sharing AP.

[0067] In S701, the AP 102 transmits an NDP announcement frame to a STA (STA 103) within its own BSS (BSS 101). In S702, the AP 102 transmits a sounding NDP. As described above, the sounding NDP is transmitted at maximum transmission power. In S703, the AP 102 transmits a BFRP_TF.

[0068] In S704, AP 102 receives compressed beamforming / CQI frames from the STAs (STA 103 and STA 106 in this example) that have received the sounding NDP and BFRP_TF. In S705, AP 102 determines whether to perform transmission power control for the sharing AP (AP 102 in this example) and the shared AP (AP 105 in this example) based on the CQI information reported from each STA. Details are as described with reference to Table 1.

[0069] In S706, the AP 102 determines whether or not beamforming transmission is possible based on the determination result in S705. Details are as described with reference to Table 2. If it is determined that beamforming transmission is "prohibited," the process proceeds to S711. On the other hand, if it is determined that beamforming transmission is "possible," the process proceeds to S707.

[0070] In S707, the AP 102 estimates the arrival wave (direction of radio wave arrival) of each STA based on the compressed beamforming / CQI frame received in S704. In S708, the AP 102 determines whether to transmit using beamforming (S709) or a single antenna (S710). That is, as described above, if it determines that the STA 103 in its own BSS (within the BSS 101) and the STA 106 outside the own BSS are not located in approximately the same direction, it transmits using beamforming. In S711, the AP 102 transmits a multi-AP cooperative communication (M-AP) trigger frame (TF) (second instruction) to start communication. The M-AP_TF includes control information for the shared AP (transmission power control / beamforming availability).

[0071] FIG. 8 is a flowchart showing the operation of the AP 105, which is a shared AP.

[0072] In S801, the AP 105 receives a sounding TF (first instruction) from a sharing AP (e.g., AP 102). In S802, the AP 105 waits for the time for the sounding process by the sharing AP. In S803, the AP 105 transmits an NDP announcement frame to a STA (STA 106) in its own BSS (BSS 104). In S804, the AP 105 transmits a sounding NDP. As described above, the sounding NDP is transmitted at maximum transmission power. In S805, the AP 105 receives a BFRP_TF from the sharing AP.

[0073] In S806, the AP 105 receives compressed beamforming / CQI frames from the STAs (here, STA 103 and STA 106) that have received the sounding NDP and BFRP_TF.

[0074] In S807, the AP 105 receives a multi-AP cooperative communication (M-AP) trigger frame (TF) (second instruction). As described above, the M-AP_TF includes control information (transmission power control / beamforming availability). In S808, the AP 105 sets the transmission power based on the power control information acquired in S807. In S809, the AP 105 determines whether beamforming is available based on the beamforming availability information acquired in S807. If it is determined that beamforming transmission is "unavailable," the process proceeds to S813. On the other hand, if it is determined that beamforming transmission is "available," the process proceeds to S810.

[0075] In S810, the AP 105 estimates the arrival wave (radio wave arrival direction) of each STA based on the compressed beamforming / CQI frame received in S704.

[0076] In S811, the AP 105 determines whether to transmit using beamforming (S812) or a single antenna (S813). That is, as described above, if it determines that the STA 106 in its own BSS (within the BSS 104) and the STA 103 outside the own BSS are not located in substantially the same direction, the AP 105 transmits using beamforming. In S814, the AP 105 starts communication in a multi-AP cooperative configuration.

[0077] <Frame Format Example> Figure 9 shows an example of the format of each trigger frame. The sounding trigger frame format in the current 11be standard is not designed for a multi-AP cooperative configuration. However, the same format of the sounding trigger frame can be used in a multi-AP cooperative configuration. However, by specifying a value for subfield 903 (Trigger Type) in field 901 that is different from the currently specified values ​​1 to 7, a new trigger type (multi-AP cooperative configuration) is indicated. Therefore, the value of "subfield value" is specified as one of the values ​​8 to 15, which are currently "Reserved."

[0078] Furthermore, the M-AP_TF frame 509 is not specified in the current 11be standard. Therefore, as described above, the M-AP_TF frame 509 is defined by specifying one of the values ​​8 to 15, which are currently "Reserved," as the value of subfield 903 (Trigger Type). It is also advisable to specify the addresses of the APs that make up the multi-AP by using the bit positions (e.g., 2047 to 4094) that are currently "Reserved" in the value of subfield 904 (AID12) in field 902.

[0079] As described above, according to the first embodiment, when communication is performed in a multi-AP cooperative configuration, the sharing AP determines whether or not to control the transmission power of each AP and whether or not to perform beamforming. Furthermore, when it is determined that beamforming is "enabled," each AP estimates the direction of each STA, and if it determines that the STAs are not located in approximately the same direction, it performs transmission using beamforming.

[0080] The above control makes it possible to avoid interference in cooperative SR communication and improve frequency utilization efficiency. In particular, it makes it possible to perform effective sounding without beamforming, thereby suppressing the increase in overhead due to beamforming.

[0081] The present invention can also be realized by a process in which a program that realizes one or more 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., an ASIC) that realizes one or more functions.

[0082] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention.

[0083] This application claims priority based on Japanese Patent Application No. 2024-059632, filed April 2, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A communication device that complies with the IEEE 802.11 series standard and operates as a sharing AP in a multi-AP cooperative configuration that operates in cooperation with other access points (APs), comprising: a transmitting means for transmitting a sounding signal in the multi-AP cooperative configuration; a receiving means for receiving a response signal including a reception result from each of a plurality of stations (STAs) that have received the sounding signal; and a determining means for determining whether to control transmission power and enable beamforming in the AP that forms the basic service set (BSS) to which each of the plurality of STAs belongs, based on the reception result.

2. The communication device according to claim 1, wherein the sounding signal is a null data packet (NDP) signal, and the reception result includes a channel quality indicator (CQI) determined based on the sounding signal received by each STA.

3. The communication device according to claim 2, characterized in that the CQI is a ratio of the received power intensity of a sounding signal transmitted by an AP that constitutes the BSS to which each STA belongs to, to a sounding signal transmitted by an AP that constitutes another BSS.

4. The communication device according to any one of claims 1 to 3, wherein the determining means determines not to perform beamforming on an AP for which it has determined to reduce transmission power.

5. A communication device as described in any one of claims 1 to 4, further comprising an estimation means for estimating the direction of the STA that transmitted the response signal, wherein the communication device performs beamforming transmission when the determination means determines that beamforming may be performed on the communication device and there is no STA outside the own BSS in approximately the same direction as the STA within the own BSS.

6. A communication device that complies with the IEEE 802.11 series standard and operates as a shared AP in a multi-AP cooperative configuration that operates in cooperation with other access points (APs), characterized in that it comprises: a transmitting means for transmitting a sounding signal based on a first instruction from a sharing AP in the multi-AP cooperative configuration; and a receiving means for receiving a second instruction regarding transmit power control and beamforming availability in the communication device from the sharing AP that has received a response signal including a reception result from each of a plurality of stations (STAs) that have received the sounding signal.

7. The communication device described in claim 6, further comprising an estimation means for receiving the response signal and estimating the direction of the STA that transmitted the response signal, wherein the communication device performs beamforming transmission when the second instruction indicates that the communication device may perform beamforming and there is no STA outside the own BSS in approximately the same direction as the STA within the own BSS.

8. A control method for a communication device that complies with the IEEE 802.11 series standards and operates as a sharing AP in a multi-AP cooperative configuration that operates in cooperation with other access points (APs), comprising: a transmitting step of transmitting a sounding signal in the multi-AP cooperative configuration; a receiving step of receiving a response signal including a reception result from each of a plurality of stations (STAs) that have received the sounding signal; and a determining step of determining whether to control transmission power and enable beamforming in the AP that forms the basic service set (BSS) to which each of the plurality of STAs belongs, based on the reception result.

9. A control method for a communication device that complies with the IEEE 802.11 series standard and operates as a shared AP in a multi-AP cooperative configuration that operates in cooperation with other access points (APs), comprising: a transmitting step of transmitting a sounding signal based on a first instruction from a sharing AP in the multi-AP cooperative configuration; and a receiving step of receiving, from the sharing AP that has received a response signal including a reception result from each of a plurality of stations (STAs) that have received the sounding signal, a second instruction regarding transmission power control and whether beamforming is possible in the communication device.

10. A program for causing a computer having a wireless communication unit to execute the control method according to claim 8 or 9.

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