Communication device, control method, and computer-readable storage medium

Abstract

The present invention relates to a communication device, a control method, and a computer-readable storage medium. A communication device that performs wireless communication with a partner device. The communication device makes a determination of whether or not to perform cooperative communication based on information about a distance between the other communication device and the partner device, the cooperative communication being an operation to reduce an influence of interference between communication between the communication device and the partner device and communication with the other communication device, and controls communication based on a result of the determination.

Description

TECHNICAL FIELD

[0001] The present application relates to a communication device, a control method, and a computer-readable storage medium, and more particularly, to a communication control technology in a wireless communication system capable of using cooperative communication. BACKGROUND

[0002] Recently, an increase in the amount of communication data has driven the development of communication technologies such as wireless LANs (Local Area Networks). The main communication standard for wireless LANs is the IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard series. The IEEE 802.11 standard series includes standards such as IEEE 802.11a / b / g / n / ac / ax. For example, the IEEE 802.11ac and IEEE 802.11ax standards standardize advanced communication technologies using MIMO (Multiple Input Multiple Output).

[0003] Currently, in order to achieve higher communication performance, a working group has been established to develop the IEEE 802.11be standard as a successor standard to IEEE 802.11ax. In the IEEE 802.11be standard, a multi-AP cooperative configuration in which multiple access points (APs) cooperate has been studied as a system throughput improvement technology.

[0004] Bibliographic List

[0005] Patent Literature

[0006] Patent Literature 1: US-2018-0263045 SUMMARY

[0007] Technical Problem

[0008] Patent Literature 1 describes a scheme in which multiple APs or stations (STAs) communicate while reducing interference between devices using MIMO cooperative beamforming in a wireless LAN conforming to the IEEE 802.11 standard. According to this scheme, for example, in order to reduce interference with a communication partner STA of a first AP, a second AP can control signals transmitted from multiple antennas of the second AP so that antenna gain in the direction of the STA takes a very small value such as 0. This can prevent signals transmitted from the second AP from reaching the STA with sufficient power, and prevent signals transmitted from the STA from being received by the second AP with sufficient power. This antenna control is called null steering. Null steering can be used to suppress interference with a specific device. However, the use of null steering in a situation where interference is easily received can impair the obtainable performance such as communication speed.

[0009] Solution to the Problem

[0010] The present application provides a technology that performs appropriate control according to a situation in a system capable of using cooperative communication.

[0011] According to an aspect of the present application, there is provided a communication apparatus that communicates with a partner apparatus using a radio frame compliant with IEEE 802.11 standards, the communication apparatus including: a determination unit configured to make a determination of whether to perform cooperative communication based on information about a distance between other communication apparatuses and the partner apparatus, the cooperative communication being an operation to reduce an influence of interference between communication between the communication apparatus and the partner apparatus and communication with the other communication apparatuses; and a control unit configured to control communication based on a result of the determination.

[0012] Advantages of the Invention

[0013] According to the present application, in a system capable of using cooperative communication, appropriate control can be performed according to a situation.

[0014] Other features and advantages of the present application will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the present application. It is to be expressly understood, however, that the drawings are provided for the purpose of illustration only and are not intended to limit the spirit or scope of the application. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0016] [ Figure 1 ] Figure 1 is a diagram showing an example of a system configuration;

[0017] [ Figure 2 ] Figure 2 is a block diagram showing an example of an arrangement of a communication apparatus;

[0018] [ Figure 3 ] Figure 3 is a block diagram showing an example of a functional arrangement of a communication apparatus;

[0019] [ Figure 4 ] Figure 4 is a flowchart showing an example of a processing sequence performed by a communication apparatus; and

[0020] [ Figure 5 ] Figure 5 is a diagram showing an example of a processing sequence performed in a system. DETAILED DESCRIPTION

[0021] Hereinafter, the embodiments will be described in detail with reference to the drawings. Note that the following embodiments are not intended to limit the scope of the claimed invention. Various features are described in the embodiments, but the invention is not limited to the invention requiring all of these features, and a plurality of such features can be appropriately combined. Also, in the drawings, the same reference numerals are assigned to the same or similar configurations, and redundant descriptions thereof are omitted.

[0022] (System configuration)

[0023] Figure 1 An example of a configuration of a wireless communication system according to the embodiments is shown. The wireless communication system includes an AP 102, an AP 105, a STA 103, and a STA 106 in a wireless LAN conforming to the IEEE 802.11 standard series (for example, IEEE 802.11a / b / g / n / ac / ax / be standards), for example. Note that the AP stands for an access point in a wireless LAN, and the STA stands for a station in a wireless LAN. Although two APs and two STAs are illustrated for convenience of description, three or more communication devices or only one communication device can of course exist.

[0024] The AP 102 and the AP 105 can communicate with each other via, for example, a backhaul 100. Note that the backhaul 100 can be formed by a wired communication line such as an Ethernet cable or a telephone line. The backhaul 100 can be formed by a wireless communication line such as LTE (Long Term Evolution) or WiMAX (Worldwide Interoperability for Microwave Access). In the absence of or in addition to the separately configured backhaul 100, the AP 102 and the AP 105 can communicate with each other by wireless communication conforming to the IEEE 802.11 standard series. In this case, the radio channel used between the AP 102 and the AP 105 can be the same as or different from the radio channel used in communication between the AP 102 or the AP 105 and the STA 103 or the STA 106.

[0025] ​The AP 102 constructs and manages the first network 101, and can communicate with STAs participating in the first network 101 (or other APs). The AP 105 constructs and manages the second network 104, and can communicate with STAs participating in the second network 104. The AP 102 and the AP 105 have a multi-AP cooperation function. Note that the multi-AP cooperation function is a function of communicating with connected stations in cooperation with other APs. For example, the AP 102 communicates with the STA 103 and the STA 106 in cooperation with the AP 105. This can improve communication speed and communication stability compared to a case where the AP 102 communicates with these STAs alone. Note that communication stability is evaluated in terms of an index or a combination thereof, such as whether a signal-to-noise ratio (SNR) reaches a predetermined level, whether an interference power level is lower than a predetermined level, and whether a delay or jitter is smaller than a predetermined value. In the following description, the multi-AP cooperation function will sometimes be referred to as a cooperative communication function.

[0026] The cooperative communication function includes, for example, a communication function based on a null-steering scheme. In the null-steering scheme, for example, when the AP 102 communicates with the STA 103 and the AP 105 communicates with the STA 106 in parallel, the AP 102 reduces the antenna gain in the direction of the STA 106 to be sufficiently low (for example, 0) by antenna control. The AP 105 reduces the antenna gain in the direction of the STA 103 to be sufficiently low (for example, 0) by antenna control. In the following description, sufficiently reducing the antenna gain in a predetermined direction will sometimes be referred to as forming a null in the predetermined direction. Note that a method of cooperatively using the null-steering scheme in the AP 102 and the AP 105 is sometimes referred to as cooperative null-steering. This method can also be referred to as cooperative beamforming (BF) because beamforming is performed to properly set the null point of a beam emitted from each AP. Furthermore, this method is also referred to as cooperative BF and nulling. Note that antenna control for null-steering is performed by changing the phase (and in some cases, the amplitude) of a radio signal transmitted from a plurality of antennas of an AP. The specific method is well known, and thus a detailed description thereof will be omitted. This method can prevent mutual interference between communication between the AP 102 and the STA 103 and communication between the AP 105 and the STA 106. Note that the cooperative communication function can include a function of controlling a radio signal transmitted from the antennas of the AP 102 and the AP 105 to improve the reception quality of the radio signal at the STA 103 and the STA 106 and provide high-speed wireless communication. In the present embodiment, null-steering is used as the cooperative communication function, and other cooperative communication functions are not used.

[0027] The STAs 103 and 106 are configured to, for example, establish connections with the AP 102 and the AP 105 and perform wireless communication. Note that these STAs can connect to the AP 102 and establish connections with the AP 105 in parallel, and these STAs communicate with these APs in parallel when these APs communicate in cooperation.

[0028] When the method of reducing the influence of interference is used as a cooperative communication function, the communication performance such as throughput sometimes decreases. For example, when the AP uses null steering, the antenna gain in the direction of the communication partner STA can decrease as a result of forming a null for interference suppression. In an embodiment, the communication performance of the entire system is improved by preventing the AP from unnecessarily using null steering. An example of an arrangement of an apparatus that performs such processing and an example of a processing sequence will be explained below.

[0029] (Apparatus arrangement)

[0030] Figure 2 An example of a hardware arrangement of a communication apparatus (AP and STA) is shown. The communication apparatus 101 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 as an example of a hardware arrangement.

[0031] The storage unit 201 is formed of either or both of a ROM (Read Only Memory) and a RAM (Random Access Memory), and stores various information such as programs (to be described later) for performing various operations and communication parameters for wireless communication. In addition to a memory such as a ROM or a RAM, a storage medium such as a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, or a DVD can be used as the storage unit 201.

[0032] The control unit 202 is formed of one or more processors such as a CPU and an MPU, an ASIC (Application-Specific Integrated Circuit), a DSP (Digital Signal Processor), and an FPGA (Field-Programmable Gate Array). The CPU is an abbreviation for Central Processing Unit, and the MPU is an abbreviation for Micro Processing Unit. The control unit 202 controls the entire apparatus by executing the programs stored in the storage unit 201. Note that the control unit 202 can control the entire apparatus in cooperation with an OS (Operating System) through the programs stored in the storage unit 201.

[0033] The control unit 202 controls the functional unit 203 to execute predetermined processing such as an AP function, a STA function, imaging, printing, or projection. The functional unit 203 is hardware for executing predetermined processing by the apparatus. For example, when the communication apparatus is an AP, the functional unit 203 is configured to execute an AP function including a cooperative communication function. When the communication apparatus is a STA, the functional unit 203 establishes a connection with an AP and performs communication. For example, when the communication apparatus is a camera, the functional unit 203 is an imaging unit and performs imaging processing. For example, when the communication apparatus is a printer, the functional unit 203 is a printing unit and performs printing processing. For example, when the communication apparatus is a projector, the functional unit 203 is a projection unit and performs projection processing. Data to be processed by the functional unit 203 can be data stored in the storage unit 201 or data transmitted with other APs or STAs via the communication unit 206 (to be described later).

[0034] The input unit 204 accepts various operations from a user. The output unit 205 performs various outputs to the user. The output by the output unit 205 includes at least one of display on a screen, audio output from a speaker, vibration output, and the like. Note that both the input unit 204 and the output unit 205 can be implemented by one module such as a touch panel.

[0035] The communication unit 206 performs control of wireless communication conforming to the IEEE 802.11 standard series and control of IP communication. The communication unit 206 is a so-called radio chip and can include one or more processors and memories. In an embodiment, the communication unit 206 can at least perform processing conforming to the IEEE 802.11be standard. The communication unit 206 controls the antenna 207 to transmit / receive a radio signal for wireless communication. The communication apparatus performs communication of content such as image data, document data, and video data with other communication apparatuses via the communication unit 206. The antenna 207 can transmit / receive in at least one of, for example, a sub-GHz band, a 2.4-GHz band, a 5-GHz band, and a 6-GHz band. Note that the frequency bands (and their combinations) to which the antenna 207 is compatible are not particularly limited. The antenna 207 can be one antenna or a set of two or more antennas for performing MIMO (Multiple Input and Multiple Output) transmission / reception. For example, in order to cope with MIMO communication using 16 spatial streams in the IEEE 802.11be standard, the antenna 207 can be configured to include 16 antenna elements.

[0036] Figure 3An example of the functional arrangement of the AP (AP 102 and AP 105) is shown. The AP includes, for example, a wireless LAN control unit 301, a UI control unit 302, a storage unit 303, a scheme selection unit 304, a single-AP control unit 305, and a null steering control unit 306. Note that these functional units are implemented by the control unit 202 of the AP executing a program stored in the storage unit 201 and including instructions defining the operation of each functional unit, as follows. Note that part or all of the following functional units can be implemented by dedicated hardware.

[0037] The wireless LAN control unit 301 is configured to include, for example, a circuit for transmitting / receiving radio signals to / from other devices (for example, other APs or STAs) conforming to the IEEE 802.11 standard series and a program for controlling the circuit. The wireless LAN control unit 301 performs communication control to generate and transmit frames, for example, in accordance with the procedures defined in the IEEE 802.11 standard series, or to receive radio frames from other devices and extract information. The UI control unit 302 is configured to include, for example, hardware units related to a user interface (UI), such as a touch panel or buttons for accepting operations of the AP by a user (not shown) of the AP, and a program for controlling these units. Note that the UI control unit 302 also has a function for presenting information to the user, such as display of images and the like or audio output. The storage unit 303 is configured to include a function of holding programs to be executed by the AP and various data.

[0038] The scheme selection unit 304 selects whether to use the cooperative communication function based on whether there is a neighboring AP, the capability of the neighboring AP, the connection state between the neighboring AP and the STA, a value corresponding to the distance between the neighboring AP and the communication partner device of the AP, and the like. For example, the scheme selection unit 304 determines which of the null-steering scheme serving as the cooperative communication function and the single-AP scheme serving as the non-cooperative communication function to use. Note that the scheme selection method will be described later. When the scheme selection unit 304 selects the single-AP scheme, the single-AP control unit 305 performs communication control to connect to the STA alone without using the cooperative communication function, that is, without cooperating with other APs. For example, the single-AP control unit 305 can control a plurality of antennas of the AP to sufficiently increase the antenna gain in the direction of the communication partner STA without considering interference. This can improve the communication performance when not performing cooperative communication. When the scheme selection unit 304 selects the null-steering scheme, the null-steering control unit 306 performs communication in cooperation with other APs by performing control to reduce interference. For example, in a situation where the communication partner STA of the other AP can be interfered, the null-steering control unit 306 controls the antenna to form a null in the direction of the STA and performs cooperative communication control to communicate in parallel with the communication of the other AP. For example, when the communication of the other AP can interfere with the communication partner STA of the AP, the null-steering control unit 306 performs cooperative communication control to cause the other AP to perform null-steering.

[0039] Since the STA is a communication device used as a general station in a wireless LAN conforming to the IEEE 802.11 standard series, the description of the function of the STA will be omitted.

[0040] (Process Sequence)

[0041] An example of a process sequence determined by the AP (AP 102 and AP 105) to use which of the single-AP scheme and the null-steering scheme will be described with reference to Figure 4

[0042] ​In the process, first, the AP searches for neighboring APs (step S401). For example, the AP searches for neighboring APs by receiving a beacon transmitted from other APs through a wireless function or receiving a signal broadcast / multicast from other APs via a wired line. Note that, in order to notify other neighboring APs of the existence of the AP, the AP can transmit a beacon in a wireless manner or via a wired broadcast / multicast signal. Alternatively, the AP can specify the existence of other specific APs in the vicinity of the AP by transmitting a query frame to the specific APs and receiving a response to the frame. In an embodiment, the AP 102 and the AP 105 recognize each other as neighboring APs.

[0043] If the AP detects a neighboring AP (YES in step S401), it determines whether the neighboring AP has a cooperative communication function (step S402). This determination can be made based on capability information included in a response signal to a beacon or a query signal received wirelessly by the AP from the neighboring AP or a signal received via a wire and indicating whether the cooperative communication function is supported. This determination can also be made based on other information such as version information of a standard supported by the neighboring AP. If the AP determines that there is no neighboring AP having a cooperative communication function (NO in step S401 or NO in step S402), it selects a single-AP scheme in which the AP communicates with a communication partner STA individually without cooperative communication control with other APs as the scheme to be used (step S405).

[0044] If the AP determines that there is a neighboring AP having a cooperative communication function (YES in step S402), it determines whether the distance between the communication partner STA of the AP and the neighboring AP having a cooperative communication function is far enough (step S403). If the AP determines that the distance between the communication partner STA and the neighboring AP is not far enough (NO in step S403), it selects the null steering scheme as the scheme to be used (step S404). If the AP determines that the distance between the communication partner STA and the neighboring AP is far enough (YES in step S403), it selects the single-AP scheme as the scheme to be used (step S405). More specifically, in the case where the distance between the communication partner STA and the neighboring AP is far enough, the influence of interference is satisfactorily suppressed by radio range attenuation even if the interference of the neighboring AP to the communication partner STA is not taken into account when a radio signal is transmitted. In this case, the AP does not have to cooperate with the neighboring AP, and selects the single-AP scheme. In contrast, when the communication partner STA is close to the neighboring AP to a certain extent, the influence of interference cannot be ignored. In order to reduce the influence of interference, the null steering scheme is selected. In this case, the AP causes the other AP to perform null steering to reduce the interference to the communication partner device of the AP. Alternatively, even the AP itself can perform null steering based on a request from the other AP, the distance to the communication partner device of the other AP, and the like.

[0045] For example, whether the distance between the communication partner STA and the neighboring AP is far is determined based on, for example, an RSSI (Received Signal Strength Indicator) obtained when the communication partner STA receives a beacon from the neighboring AP. For example, the STA measures the reception strength of the beacon of the neighboring AP, and notifies the AP of the RSSI value. When the notified RSSI is equal to or higher than a predetermined value, the AP can determine that the distance between the communication partner STA and the neighboring AP is close enough. When the notified RSSI is lower than the predetermined value, the AP can determine that the distance between the communication partner STA and the neighboring AP is far enough.

[0046] Further, the AP can determine whether to perform cooperative communication including null steering based on various information about a distance between the communication partner device of the AP and other APs. For example, assuming that the communication partner STA exists in the vicinity of the neighboring AP, the AP determines whether the distance between the communication partner STA and the neighboring AP is far based on whether the distance between the AP and the neighboring AP is far. More specifically, when the distance between the AP and the neighboring AP is far, the AP estimates that the distance between the communication partner STA and the neighboring AP is likely to be far. When the distance between the AP and the neighboring AP is near, the AP can estimate that the distance between the communication partner STA and the neighboring AP is likely to be near. Thus, the AP measures a reception strength of a beacon transmitted from the neighboring AP. When the reception strength is lower than a predetermined value, the AP determines that the distance between the AP and the neighboring AP is far, and thus the distance between the communication partner STA and the neighboring AP is also far. When the reception strength of the beacon from the neighboring AP is equal to or higher than the predetermined value, the AP determines that the distance between the AP and the neighboring AP is near, and thus the distance between the communication partner STA and the neighboring AP is also near.

[0047] When the communication partner STA communicates with the neighboring AP, the AP can use channel state information (CSI) about communication between the communication partner STA and the neighboring AP to perform the above-described determination. For example, when an SNR value included in the CSI is less than a predetermined value, the AP estimates that the distance between the communication partner STA and the neighboring AP is likely to be far. When the SNR value included in the CSI is equal to or greater than the predetermined value, the AP estimates that the distance between the communication partner STA and the neighboring AP is likely to be near. In this case, the AP can acquire the CSI information from the neighboring AP or the communication partner STA and make the determination. The CSI information can be acquired by transmitting a request signal from the AP to at least one of the neighboring AP or the communication partner STA. The signal received when the AP detects the neighboring AP in step S401 can include the CSI information between the neighboring AP and the communication (connected) STA.

[0048] When both the communication partner STA and the neighboring AP have a positioning function such as a GPS (Global Positioning Satellite), the AP can determine whether the distance between the communication partner STA and the neighboring AP is far based on the positioning result. In this case, for example, the AP can make the determination by acquiring a plurality of positioning result information from the communication partner STA and the neighboring AP. For example, when the neighboring AP is communicating (connected) with the communication partner STA, the AP can acquire not only the information of the positioning result of the neighboring AP but also the information of the positioning result of the communication partner STA. Note that whether the distance between the communication partner STA and the neighboring AP is equal to or greater than a predetermined value can be determined in step S403. The predetermined value can be determined based on, for example, a frequency band used. That is, assuming that a range attenuation differs depending on the frequency used, the predetermined value serving as a determination criterion can be appropriately determined depending on the frequency band used.

[0049] Note that the determination in step S403 can be made based on information obtained by, for example, combining various kinds of information on distance as described above.

[0050] Next, an example of a processing sequence performed in a wireless communication system according to an embodiment will be described with reference to Figure 5 An example of a processing sequence performed in a wireless communication system according to an embodiment will be described with reference to

[0051] First, the AP 102 confirms channel states between the AP 102 and the STAs 103 and 106 (S501 and S503), and the AP 105 also confirms channel states between the AP 105 and the STAs 103 and 106 (S502 and S504). For example, the AP 102 and the AP 105 transmit null data packets (NDPs) that do not include data, and the STAs 103 and 106 measure channel states from the NDPs from the APs. The STAs 103 and 106 feed back CSI to the APs serving as the NDP transmission sources based on the measurement results. Then, the AP 102 and the AP 105 exchange and share the CSI acquired respectively (S505). Through the information exchange, the AP 102 and the AP 105 can also perform downlink multi-user (DL MU) operation from each AP to multiple STAs in parallel. In the CSI acquisition, channel states when signals are transmitted from the STAs to the APs can also be confirmed. This information can be used when uplink multi-user (UL MU) operation from multiple STAs to the APs is performed. Here, the AP 102 and the AP 105 select a null-steering scheme. Note that the processing in S501 to S505 is performed, for example, periodically.

[0052] After that, the AP 102 transmits a null-steering trigger frame (TF) to the AP 105. The TF is used to specify timing of the next transmission operation. Which of the AP 102 and the AP 105 transmits the TF can be determined through negotiation, and the negotiation can be performed when the CSI is shared in S505, for example.

[0053] The AP 102 and the AP 105 transmit data frames after a SIFS (Short InterFrame Space) time after the TF transmission / reception timing or after other predetermined time. At this time, the AP 102 transmits a data frame to the STA 103 while performing null steering to direct nulls in the direction of the STA 106 (S507). The AP 105 transmits a data frame to the STA 106 while performing null steering to direct nulls in the direction of the STA 103 (S508). Thus, the communication between the AP 102 and the STA 103 and the communication between the AP 105 and the STA 106 are performed in parallel without interfering with each other. When the SNR in the CSI between the AP 102 and the STA 106 is sufficiently low and the SNR in the CSI between the AP 105 and the STA 103 is high, only the AP 105 can perform null steering. Similarly, when the SNR in the CSI between the AP 102 and the STA 106 is sufficiently high and the SNR in the CSI between the AP 105 and the STA 103 is low, only the AP 102 can perform null steering. That is, in these cases where the SNR between the AP and the STA that does not serve as a communication partner is sufficiently low and the interference is considered to be small even without performing null steering, the AP can not use null steering. In an environment where the interference is satisfactorily suppressed, not using null steering can suppress the reduction in throughput caused by using null steering.

[0054] Note that the AP 102 can transmit a TF to the STA 106 (S509) and transmit a data frame to the STA 106 while performing null steering to direct nulls in the direction of the STA 103 (S510). Further, the AP 105 can transmit a data frame to the STA 103 while performing null steering to direct nulls in the direction of the STA 106 (S511).

[0055] According to the null steering scheme, it is possible to perform communication while suppressing interference. However, when the distance between the AP and the communication partner STA of the other AP is far, the power of interference between the other AP and the STA is predicted to be low enough. Therefore, in embodiments, when the distance between the AP on the interference side and the STA on the interfered side is far, the AP performs communication with the STA without cooperating with the other neighboring AP. In other words, when the AP does not need to cause the neighboring AP to perform interference suppression control in cooperation with the neighboring AP, it communicates with the STA alone without cooperative communication. In an environment where interference hardly occurs, it is not attempted to reduce interference that can lower communication efficiency, and communication efficiency can be improved. When the distance between the AP on the interference side and the STA on the interfered side is close, the AP causes the other neighboring AP to perform interference suppression control in cooperation with the neighboring AP, allows communication efficiency to be lowered, and performs communication while reducing interference. According to embodiments, it is possible to perform efficient communication while taking into account the distance between communication devices.

[0056] In embodiments, the AP determines whether to perform cooperative communication that causes the other AP to perform null steering based on the distance between the other AP and the STA that serves as a communication partner device of the AP. From the perspective of the other AP, the AP can determine whether to perform cooperative communication with the other AP in the form of null steering by the AP based on the distance between the AP and the STA that serves as a communication partner device of the other AP. Note that the AP can determine whether to perform null steering by the AP based on the distance between the AP and the STA that serves as a communication partner device of the other AP. When the first AP causes the second AP to perform null steering, the first AP can transmit an instruction to the second AP when sharing the channel state in, for example, S505. Similarly, when the second AP causes the first AP to perform null steering, the second AP can transmit an instruction to the first AP when sharing the channel state in, for example, S505. Null steering is performed only when necessary, and communication efficiency can be improved. For example, the AP that transmits the TF can indicate to the AP that receives the TF that null steering is used in the TF, and the AP that transmits the TF can determine whether to use null steering in the AP itself. In other words, when performing cooperative communication with the other AP, the AP can perform communication on the AP itself without receiving an instruction from the other AP while causing the other AP to perform predetermined processing (for example, null steering).

[0057] Although the AP conforming to the IEEE 802.11 standard series cooperates with other APs to transmit a signal in the above-described example, the present application is not limited to this. For example, when a plurality of STAs transmit a signal in parallel, the AP can perform reception control cooperatively with other APs as in the above-described processing. For example, when the distance between the communication partner STA of the AP and other APs is short, the other APs can perform reception antenna control to direct nulls toward the direction of the STA. In this case, for example, the AP causes the communication partner STA of the other APs and the communication partner STA of the AP to transmit a signal in parallel, and performs cooperative operation at this time so that the other APs perform reception antenna control. Further, when cooperative communication is performed between STAs, the control as described above can be performed. Further, when a plurality of communication apparatuses respectively communicate with a communication partner apparatus, regardless of a wireless LAN, each communication apparatus can determine whether to perform cooperative communication with other communication apparatuses based on the distance between the communication partner apparatus of the communication apparatus and other communication apparatuses. Thus, when the influence of interference between communication between the communication apparatus and the communication partner apparatus and communication with other communication apparatuses is small enough and cooperative control is not needed, a decrease in communication efficiency due to unnecessary cooperative control can be prevented.

[0058] Although transmission antenna control is used in the above-described embodiment, the present application is not limited to this. For example, the AP can prevent interference between communication of the AP and communication of other APs by performing predetermined encoding (e.g., dirty paper coding (DPC) or the like). For example, the AP can specify the type of data transmitted from other APs, predict a waveform in advance, and transmit a signal obtained by subtracting a waveform component from a signal to be transmitted from the AP, and the communication partner apparatus receives a signal transmitted from other APs through the waveform. The communication partner apparatus can receive a waveform in which a signal that should be transmitted from the AP is reproduced by adding an interference waveform from other APs to a waveform received from the AP. According to this method, the AP acquires information of data to be transmitted and a channel estimation value between the communication partner STA of the AP and other APs in advance, and performs cooperative operation to adjust the transmission timing of a signal, thereby suppressing the influence of interference. In an environment in which the distance between the communication partner STA of the AP and other APs is long, the error of the predicted channel estimation value or the like is large. If the above-described method is used in such an environment, the communication performance decreases. To prevent this, whether to perform cooperative communication of operation to reduce the influence of interference can be determined based on information about the distance between the communication partner of the AP and other APs. In an environment in which the influence of interference is not strong enough and an interference waveform is buried in noise, the subtraction of an interference waveform including a relatively large error in advance can be prevented. As a result, a decrease in communication performance can be prevented.

[0059] The present application can be implemented by supplying a program realizing one or more functions of the above-described embodiments to a system or an apparatus via a network or a storage medium and causing one or more processors in a computer of the system or the apparatus to read out and execute the program. The present application can also be implemented by a circuit (e.g., ASIC) for realizing one or more functions.

[0060] The present application is not limited to the above-described embodiments, and various changes and modifications can be made within the spirit and scope of the present application. Therefore, the following claims are made in order to inform the public of the scope of the present application.

Claims

1. A communication apparatus that is a first access point, which communicates with a partner apparatus that is a non-access point station using radio frames conforming to IEEE 802.11 standards, comprising: a determination unit configured to make a determination whether to perform cooperative communication based on information about a distance between the partner apparatus and another communication apparatus that is a second access point, the cooperative communication being an operation to reduce an influence of interference between communication between the communication apparatus and the partner apparatus that is the non-access point station and communication with the another communication apparatus that is the second access point; and a control unit configured to, in a case where a role of the communication apparatus as a transmitter of a trigger frame is determined by negotiation between the communication apparatus and the another communication apparatus that is the second access point and the determination unit determines that the communication apparatus performs the cooperative communication, transmit the trigger frame to the another communication apparatus that is the second access point to trigger performance of the cooperative communication.

2. The communication apparatus according to claim 1, wherein The information about the distance includes information of a signal reception strength between the partner apparatus and the another communication apparatus.

3. The communication apparatus according to claim 1, wherein The information about the distance includes information of a signal reception strength between the communication apparatus and the another communication apparatus.

4. The communication apparatus according to claim 1, wherein The information about the distance includes channel state information between the partner apparatus and the another communication apparatus.

5. The communication apparatus according to claim 1, wherein The information about the distance includes information of a positioning result of each of the partner apparatus and the another communication apparatus.

6. The communication apparatus according to claim 1, wherein In a case where it is determined to perform the cooperative communication, the control unit performs control to cause the another communication apparatus to perform null-steering manipulation for reducing interference with the partner apparatus.

7. The communication apparatus according to claim 6, wherein In a case where it is determined to perform the cooperative communication, the control unit performs control to perform null-steering manipulation for reducing interference with the partner apparatus of the another communication apparatus.

8. The communication apparatus according to any of claims 1 to 7, wherein, The communication apparatus and the another communication apparatus are access points.

9. A control method performed by a communication apparatus that is a first access point, which communicates with a partner apparatus that is a non-access point station using radio frames conforming to IEEE 802.11 standards, the control method comprising: making a determination whether to perform cooperative communication based on information about a distance between the partner apparatus that is the non-access point station and another communication apparatus that is a second access point, the cooperative communication being an operation to reduce an influence of interference between communication between the communication apparatus that is the first access point and the partner apparatus that is the non-access point station and communication with the another communication apparatus that is the second access point; and in a case where a role of the communication apparatus as a transmitter of a trigger frame is determined by negotiation between the communication apparatus and the another communication apparatus that is the second access point and it is determined that the communication apparatus performs the cooperative communication, controlling communication to transmit the trigger frame to the another communication apparatus that is the second access point to trigger performance of the cooperative communication.

10. A computer-readable storage medium storing a program for causing a computer to function as the communication apparatus defined in any one of claims 1 to 8.

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