Communication apparatus, method of controlling communication apparatus, and computer readable storage medium

Abstract

The invention relates to a communication apparatus, a method of controlling the communication apparatus, and a computer readable storage medium. A communication apparatus operating as a first access point communicating with a first station apparatus in a first network managed by the communication apparatus includes a transmission unit configured to transmit a first null packet (NDP) to a second station apparatus in a second network managed by a second access point, the second station device transmitting first information on a channel state based on the first NDP; and a control unit configured to perform a null manipulation to the second station device in the second network based on the information transmitted by the second station device.

Description

[0001] This application is a divisional application of the invention patent application filed on November 24, 2020, with application number 202080078394.6 (international application number PCT / JP2020 / 043567) and entitled "Communication Apparatus, Control Method and Computer-Readable Storage Medium". Technical Field

[0002] This invention relates to communication devices, control methods, and computer-readable storage media, and more particularly, to communication control techniques in wireless communication systems capable of using cooperative communication. Background Technology

[0003] The recent increase in communication data volume 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 the use of MIMO (Multiple-Input Multiple-Output) advanced communication technology.

[0004] Currently, to achieve higher communication performance, a working group has been established to develop the IEEE 802.11be standard as a successor to IEEE 802.11ax. The IEEE 802.11be standard has already studied multi-AP cooperative communication as a technique to improve system throughput.

[0005] Reference List

[0006] Patent documents

[0007] Patent Document 1: US-2018-0263045 Summary of the Invention

[0008] Technical issues

[0009] Patent Document 1 describes a scheme in which multiple access points (APs) or stations (STAs) communicate in a wireless LAN compliant with the IEEE 802.11 standard using MIMO cooperative beamforming to reduce interference between devices. According to this scheme, for example, to reduce interference to the communication partner STA of a first AP, a second AP can control the signals transmitted from multiple antennas of the second AP so that the antenna gain in the direction of the STA is taken to a very small value, such as 0. This prevents signals transmitted from the second AP from reaching the STA with sufficient power, and prevents 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 to specific devices. However, using null steering in interference-prone environments may impair available performance such as communication speed.

[0010] Solution to the problem

[0011] This invention provides a technique for performing appropriate control as needed in a system capable of using cooperative communication.

[0012] According to one aspect of the present invention, a communication apparatus is provided for communicating with a partner device using radio frames conforming to the IEEE 802.11 standard. The communication apparatus includes: a determining unit configured to determine whether to perform cooperative communication based on information about the distance between other communication devices and the partner device, the cooperative communication being an operation to reduce interference between the communication device and the partner device and between the communication devices and other communication devices; and a control unit configured to control the communication based on the determining result.

[0013] Beneficial effects of the invention

[0014] According to the present invention, in a system capable of using cooperative communication, appropriate control can be performed as needed.

[0015] Other features and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings. Note that throughout the drawings, the same reference numerals denote the same or similar parts. Attached Figure Description

[0016] The accompanying drawings, which are included in and form part of this specification, illustrate embodiments of the invention and, together with this description, serve to explain the principles of the invention.

[0017] [ Figure 1 ] Figure 1 This is a diagram illustrating an example of system construction;

[0018] [ Figure 2 ] Figure 2This is a block diagram illustrating an example of the arrangement of a communication device;

[0019] [ Figure 3 ] Figure 3 This is a block diagram illustrating an example of the functional arrangement of a communication device;

[0020] [ Figure 4 ] Figure 4 This is a flowchart illustrating an example of a processing sequence performed by a communication device; and

[0021] [ Figure 5 ] Figure 5 This is a diagram illustrating an example of a processing sequence executed in the system. Detailed Implementation

[0022] In the following description, embodiments will be illustrated in detail with reference to the accompanying drawings. Please note that the following embodiments are not intended to limit the scope of the claimed invention. Several features are described in the embodiments, but the invention is not limited to requiring all of these features, and multiple such features can be suitably combined. Furthermore, in the drawings, the same reference numerals are given the same or similar constructions, and their redundant descriptions are omitted.

[0023] (System Structure)

[0024] Figure 1 An example of the construction of a wireless communication system according to an embodiment is shown. The wireless communication system includes, for example, AP 102, AP 105, STA 103, and STA 106 in a wireless LAN conforming to the IEEE 802.11 standard family (e.g., IEEE 802.11a / b / g / n / ac / ax / be standards). Note that AP represents an access point in the wireless LAN, and STA represents a station in the wireless LAN. Although two APs and two STAs are illustrated for ease of description, it is of course possible to have three or more communication devices or only one communication device.

[0025] AP 102 and AP 105 can communicate with each other via, for example, backhaul 100. Note that backhaul 100 can be established via, for example, Ethernet. The backhaul 100 can be formed by a wired communication line, such as a telephone line. The backhaul 100 can also be formed by a wireless communication line such as LTE (Long Term Evolution) or WiMAX (Worldwide Interoperability for Microwave Access). In the absence of a separately constructed backhaul 100, or in addition to a separately constructed backhaul 100, AP 102 and AP 105 can communicate with each other via wireless communication conforming to the IEEE 802.11 standard family. In this case, the radio channel used between AP 102 and AP 105 can be the same as or different from the radio channel used in communication between AP 102 or AP 105 and STA 103 or STA 106.

[0026] AP 102 constructs and manages the first network 101 and can communicate with STAs (or other APs) participating in the first network 101. AP 105 constructs and manages the second network 104 and can communicate with STAs participating in the second network 104. AP 102 and AP 105 have multi-AP cooperation capabilities. Note that multi-AP cooperation capability is the capability to communicate with connected stations that cooperate with other APs. For example, AP 102 cooperates with AP 105 to communicate with STAs 103 and 106. This can improve communication speed and communication stability compared to AP 102 communicating with these STAs alone. Note that communication stability is evaluated based on indicators or combinations thereof, such as whether the signal-to-noise ratio (SNR) reaches a predetermined level, whether the interference power level is below a predetermined level, and whether the delay or jitter is less than a predetermined value. In the following description, the multi-AP cooperation capability will sometimes be referred to as the cooperative communication capability.

[0027] Cooperative communication functions include, for example, communication functions based on nulling manipulation schemes. In a nulling manipulation scheme, for example, when AP 102 communicates with STA 103 and AP 105 communicates with STA 106 in parallel, AP 102 reduces the antenna gain in the direction of STA 106 to a sufficiently low level (e.g., 0) via antenna control. AP 105 reduces the antenna gain in the direction of STA 103 to a sufficiently low level (e.g., 0) via 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 the method of cooperatively using a nulling manipulation scheme in AP 102 and AP 105 is sometimes referred to as cooperative nulling manipulation. This method can also be referred to as cooperative beamforming (BF) because beamforming is performed to correctly set the null points of the beams transmitted from each AP. Furthermore, this method is also referred to as cooperative BF and nulling. Note that antenna control for nulling manipulation is performed by changing the phase (and in some cases, the amplitude) of the radio signals transmitted from multiple antennas of the AP. The specific method is well known, and therefore a detailed description thereof will be omitted. This method prevents mutual interference between communications between AP 102 and STA 103, and between AP 105 and STA 106. Note that the cooperative communication function may include controlling the radio signals transmitted from the antennas of AP 102 and AP 105 to improve the reception quality of radio signals at STA 103 and STA 106 and provide high-speed wireless communication. In this embodiment, null manipulation is used as the cooperative communication function, and other cooperative communication functions are not used.

[0028] STA103 and STA106 are configured, for example, to establish connections with AP 102 and AP 105 and to conduct wireless communication. Note that these STAs can connect to AP 102 and establish connections with AP 105 in parallel, and these STAs communicate in parallel with these APs when these APs are cooperating in communication.

[0029] When methods for reducing interference are used as cooperative communication functions, communication performance, such as throughput, can sometimes degrade. For example, when an AP uses null manipulation, the antenna gain in the direction of the communication partner STA may decrease as a result of forming nulls for interference suppression. In this embodiment, the overall system communication performance is improved by preventing the AP from unnecessarily using null manipulation. An example of the arrangement of apparatus for performing such processing and an example of the processing sequence will be explained below.

[0030] (Installation)

[0031] Figure 2An example of the hardware arrangement of a communication device (AP and STA) is shown. The communication device 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 the hardware arrangement.

[0032] Storage unit 201 is formed from either ROM (Read-Only Memory) or RAM (Random Access Memory) and stores various information, such as programs for performing various operations (described later) and communication parameters for wireless communication. In addition to memories such as ROM or RAM, storage media such as floppy disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, or DVDs can be used as storage unit 201.

[0033] The control unit 202 is formed by one or more processors such as a CPU and MPU, an ASIC (Application-Specific Integrated Circuit), a DSP (Digital Signal Processor), and a FPGA (Field-Programmable Gate Array). CPU is an abbreviation for Central Processing Unit, and MPU is an abbreviation for Microprocessor Unit. The control unit 202 controls the entire device by executing programs stored in the storage unit 201. Note that the control unit 202 can control the entire device through cooperation between the programs stored in the storage unit 201 and the OS (Operating System).

[0034] Control unit 202 controls functional unit 203 to perform predetermined processes such as AP functions, STA functions, imaging, printing, or projection. Functional unit 203 is hardware for performing predetermined processes by the device. For example, when the communication device is an AP, functional unit 203 is configured to perform AP functions including cooperative communication. When the communication device is a STA, functional unit 203 establishes a connection with the AP and communicates. For example, when the communication device is a camera, functional unit 203 is an imaging unit and performs imaging processing. For example, when the communication device is a printer, functional unit 203 is a printing unit and performs printing processing. For example, when the communication device is a projector, functional unit 203 is a projection unit and performs projection processing. The data to be processed by functional unit 203 may be data stored in storage unit 201 or data transmitted to other APs or STAs via communication unit 206 (described later).

[0035] Input unit 204 receives various operations from the user. Output unit 205 provides various outputs to the user. Outputs from output unit 205 include at least one of the following: on-screen display, audio output from a speaker, vibration output, etc. Note that both input unit 204 and output unit 205 can be implemented using a single module such as a touchpad.

[0036] Communication unit 206 controls wireless communications conforming to the IEEE 802.11 standard family and controls IP communications. Communication unit 206 is a so-called radio chip and may include one or more processors and memories. In embodiments, communication unit 206 can at least perform processing conforming to the IEEE 802.11be standard. Communication unit 206 controls antenna 207 to transmit / receive radio signals for wireless communication. Communication devices communicate with other communication devices via communication unit 206, transmitting content such as image data, document data, and video data. Antenna 207 can transmit / receive in at least one of, for example, sub-GHz bands, 2.4GHz bands, 5GHz bands, and 6GHz bands. Note that there are no particular limitations on the frequency bands (and combinations thereof) compatible with antenna 207. Antenna 207 can be a single antenna or a collection of two or more antennas for MIMO (Multiple-Input Multiple-Output) transmission / reception. For example, to accommodate MIMO communication using 16 spatial streams in the IEEE 802.11be standard, antenna 207 can be configured to include 16 antenna elements.

[0037] Figure 3 An example of the functional layout of an 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 zero-trap manipulation control unit 306. Note that these functional units are implemented by the AP's control unit 202 executing a program stored in the storage unit 201, which includes instructions defining the operation of each functional unit. Note that some or all of the following functional units can be implemented by dedicated hardware.

[0038] The wireless LAN control unit 301 is configured to include, for example, circuitry for transmitting / receiving radio signals to / from other devices (e.g., other APs or STAs) conforming to the IEEE 802.11 standard family, and a program for controlling that circuitry. The wireless LAN control unit 301 performs communication control, such as generating and transmitting frames according to procedures defined in the IEEE 802.11 standard family, or receiving radio frames from other devices and extracting 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 on the AP by a user (not shown), and a program for controlling these units. Note that the UI control unit 302 also has functions for presenting information to the user, such as displaying images or audio output. The storage unit 303 is configured to include functions for storing programs to be executed by the AP and various data.

[0039] The scheme selection unit 304 selects whether to use cooperative communication functionality based on factors such as the existence of neighboring APs, the capabilities of neighboring APs, the connection status between neighboring APs and STAs, and values ​​corresponding to the distance between neighboring APs and their communication partner devices. For example, the scheme selection unit 304 determines whether to use a null manipulation scheme that functions as cooperative communication or a single AP scheme that functions as non-cooperative communication. 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 independently without using cooperative communication functionality, i.e., without cooperating with other APs. For example, the single AP control unit 305 can control multiple antennas of the AP to maximize antenna gain in the direction of the communication partner STA, regardless of interference. This can improve communication performance when cooperative communication is not performed. When the scheme selection unit 304 selects the null manipulation scheme, the null manipulation control unit 306 performs control to reduce interference and cooperate with other APs in communication. For example, in situations where the communication partner STA of other APs may be interfered with, the null manipulation 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 other APs. For example, when the communication of other APs may interfere with the communication partner STA of this AP, the null manipulation control unit 306 performs cooperative communication control to cause other APs to perform null manipulation.

[0040] 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 STA's functions will be omitted.

[0041] (Processing sequence)

[0042] Reference Figure 4 This describes an example of the processing sequence by which the APs (AP 102 and AP 105) determine whether to use the single AP scheme or the zero-trap manipulation scheme. This processing is implemented, for example, by the execution of a program stored in the storage unit 201 by the AP's control unit 202. Note that the AP can perform the selection process at power-on or during network construction at any time during network operation.

[0043] In the process, firstly, the AP searches for neighboring APs (step S401). For example, the AP searches for neighboring APs by receiving beacons sent from other APs wirelessly or by receiving signal broadcasts / multicasts from other APs via wired lines. Note that in order to notify other neighboring APs of its presence, the AP may wirelessly send beacons or broadcast / multicast signals via wired lines. Optionally, the AP may specify the presence of other specific APs near it by sending a query frame to a specific AP and receiving a response to that frame. In this embodiment, AP 102 and AP 105 will identify each other as neighboring APs.

[0044] If the AP detects a neighboring AP ("Yes" in step S401), it determines whether the neighboring AP has cooperative communication capabilities (step S402). This determination can be based on capability information including response signals to beacon or query signals received wirelessly by the AP from the neighboring AP or signals received via wired means, indicating whether cooperative communication capabilities are supported. Alternatively, this determination can be based on other information such as version information of standards supported by the neighboring AP. If the AP determines that no neighboring AP has cooperative communication capabilities ("No" in step S401 or "No" in step S402), it selects the single AP scheme as the scheme to use, in which the AP communicates only with its communication partner STA without cooperative communication control with other APs (step S405).

[0045] If the AP determines that there is a neighboring AP with cooperative communication capabilities ("Yes" in step S402), it determines whether the distance between the AP's communication partner STA and the neighboring AP with cooperative communication capabilities is sufficient (step S403). If the AP determines that the distance between the communication partner STA and the neighboring AP is not sufficient ("No" in step S403), it selects a null manipulation 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 sufficient ("Yes" in step S403), it selects a single AP scheme as the scheme to be used (step S405). More specifically, when the distance between the communication partner STA and the neighboring AP is sufficient, even without considering the interference of the neighboring AP to the communication partner STA when transmitting radio signals, the effect of interference is satisfactorily suppressed by radio range attenuation. In this case, the AP does not need to cooperate with the neighboring AP and selects the single AP scheme. Conversely, when the communication partner STA is close to the neighboring AP to a certain extent, the effect of interference cannot be ignored. In order to reduce the effect of interference, a null manipulation scheme is selected. In this case, the AP causes other APs to perform null manipulation to reduce interference to the AP's communication partner devices. Alternatively, even the AP itself can perform zero-trap manipulation based on requests from other APs, distance to other APs' communication partner devices, etc.

[0046] For example, the distance between a communication partner STA and its neighboring AP is determined based on, for instance, the RSSI (Received Signal Strength Indicator) obtained when the communication partner STA receives a beacon from the neighboring AP. For example, the STA measures the received signal strength of the beacon from 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 sufficiently close. When the notified RSSI is lower than a predetermined value, the AP can determine that the distance between the communication partner STA and the neighboring AP is sufficiently far.

[0047] Furthermore, the AP can determine whether to conduct cooperative communication, including null manipulation, based on various information regarding the distances between its communication partner devices and other APs. For example, assuming the communication partner STA is near a neighboring AP, the AP determines whether the distance between the communication partner STA and the neighboring AP is far based on whether the AP is far from the neighboring AP. 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 far. When the distance between the AP and the neighboring AP is close, the AP can estimate that the distance between the communication partner STA and the neighboring AP is likely close. Therefore, the AP measures the received strength of beacons sent from neighboring APs. When the received strength is below a predetermined value, the AP determines that the distance between the AP and the neighboring AP is far, and therefore the distance between the communication partner STA and the neighboring AP is also far. When the received strength of beacons from the neighboring AP is equal to or higher than a predetermined value, the AP determines that the distance between the AP and the neighboring AP is close, and therefore the distance between the communication partner STA and the neighboring AP is also close.

[0048] When a communication partner STA communicates with a neighboring AP, the AP can use Channel State Information (CSI) regarding the communication between the communication partner STA and the neighboring AP to make the aforementioned determination. For example, when the 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 short. In this case, the AP can obtain CSI information from either the neighboring AP or the communication partner STA and make the determination. CSI information can be obtained by sending a request signal from the AP to at least one of the neighboring AP or the communication partner STA. The signal received by the AP when it detects a neighboring AP in step S401 may include CSI information between the neighboring AP and the communication (connection) STA.

[0049] When both the communication partner STA and the neighboring AP have positioning capabilities such as 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 results. In this case, for example, the AP can make this determination by obtaining multiple positioning result information from the communication partner STA and the neighboring AP. For example, when the neighboring AP is communicating (connecting) with the communication partner STA, the AP can obtain not only the positioning result information of the neighboring AP, but also the positioning result information of the communication partner STA. Note that in step S403, it can be determined whether the distance between the communication partner STA and the neighboring AP is equal to or greater than a predetermined value. The predetermined value can be determined based on, for example, the frequency band used. That is, assuming that range attenuation varies depending on the frequency used, the predetermined value serving as the determination criterion can be appropriately determined according to the frequency band used.

[0050] Please note that the determination in step S403 can be based on information obtained, for example, by combining various pieces of information about distance as described above.

[0051] Next, we will refer to Figure 5 An example of a processing sequence performed in a wireless communication system according to an embodiment is described. In the following example, AP 102 and AP 105 are connected to / communicate with STA 103 and STA 106 respectively, and each AP obtains the CSI between the AP and the corresponding STA and determines the scheme to be used based on the CSI.

[0052] First, AP 102 confirms the channel state between AP 102 and STAs 103 and 106 (S501 and S503), and AP 105 also confirms the channel state between AP 105 and STAs 103 and 106 (S502 and S504). For example, AP 102 and AP 105 send null data packets (NDPs) without data, and STAs 103 and 106 measure the channel state based on the NDPs from the APs. STAs 103 and 106 feed back the Channel State Indicator (CSI) to the APs acting as the NDP transmission sources based on the measurement results. Then, AP 102 and AP 105 exchange and share their respective acquired CSIs (S505). Through information exchange, AP 102 and AP 105 can also perform downlink multi-user (DL MU) operations from each AP to multiple STAs in parallel. The channel state when a signal is transmitted from a STA to an AP can also be confirmed during CSI acquisition. This information can be used when performing uplink multi-user (UL MU) operations from multiple STAs to an AP. Here, AP 102 and AP 105 select the zero-trap manipulation scheme. Note that the processing in S501 to S505 is performed, for example, periodically.

[0053] Afterwards, AP 102 sends a zero-trap manipulation trigger frame (TF) to AP 105. The TF specifies the timing of the next transmission operation. Which of AP 102 and AP 105 will send the TF can be determined through negotiation, and this negotiation can occur, for example, when sharing CSI in an S505 system.

[0054] AP 102 and AP 105 transmit data frames after the TF transmit / receive timing, either at the SIFS (Short Interframe Space) time or after another predetermined time. At this time, AP 102 transmits a data frame to STA 103 while simultaneously performing null manipulation to direct the null towards STA 106 (S507). AP 105 transmits a data frame to STA 106 while simultaneously performing null manipulation to direct the null towards STA 103 (S508). Therefore, communication between AP 102 and STA 103, and between AP 105 and STA 106, occurs in parallel without mutual interference. Only AP 105 can perform null manipulation when the SNR in the CSI between AP 102 and STA 106 is sufficiently low and the SNR in the CSI between AP 105 and STA 103 is high. Similarly, when the SNR in the CSI between AP 102 and STA 106 is sufficiently high and the SNR in the CSI between AP 105 and STA 103 is low, only AP 102 can perform null manipulation. That is, in cases where the SNR between the AP and STAs that are not communication partners is sufficiently low and the interference is considered minimal even without null manipulation, the AP may not use null manipulation. In environments where interference is satisfactorily suppressed, not using null manipulation can suppress the throughput reduction caused by using null manipulation.

[0055] Please note that AP 102 can send TF to STA 106 (S509), and simultaneously send data frames to STA 106 (S510) while performing null manipulation to direct the null towards STA 103. Furthermore, AP 105 can send data frames to STA 103 (S511) while performing null manipulation to direct the null towards STA 106.

[0056] According to the zero-trap manipulation scheme, communication can be performed while suppressing interference. However, when the distance between the AP and the communication partners STA of other APs is large, the power of interference between other APs and STAs is predicted to be sufficiently low. Therefore, in the embodiment, when the distance between the interfering AP and the interfered STA is large, the AP communicates with the STA without cooperating with other adjacent APs. In other words, when the AP does not need to cooperate with adjacent APs to perform interference suppression control, it communicates with the STA alone without cooperative communication. In an environment where little interference occurs, there is no attempt to reduce interference that may reduce communication efficiency, and communication efficiency can be improved. When the distance between the interfering AP and the interfered STA is small, the AP enables other adjacent APs to cooperate with each other to perform interference suppression control, allowing for reduced communication efficiency, and communication is performed while reducing interference. According to the embodiment, effective communication can be performed while taking into account the distance between communication devices.

[0057] In this embodiment, the AP determines whether to perform cooperative communication that causes the other AP to perform null manipulation based on the distance between the other AP and the STA, which acts as a communication partner device. From the perspective of the other APs, the AP can determine whether to perform cooperative communication with the other AP in the form of AP null manipulation based on the distance between the AP and the STA, which acts as a communication partner device. Note that the AP can determine whether to perform null manipulation based on the distance between the AP and the STA, which acts as a communication partner device. When the first AP causes the second AP to perform null manipulation, the first AP can send an instruction to the second AP when sharing the channel state, for example, in S505. Similarly, when the second AP causes the first AP to perform null manipulation, the second AP can send an instruction to the first AP when sharing the channel state, for example, in S505. Null manipulation is only performed when necessary and can improve communication efficiency. For example, the AP sending the TF can instruct the AP receiving the TF to use null manipulation in the TF, and the AP sending the TF can determine for itself whether to use null manipulation within the AP itself. In other words, when communicating in cooperation with other APs, an AP can communicate with itself without receiving instructions from other APs while causing other APs to perform predetermined processes (e.g., zero trap manipulation).

[0058] Although the AP conforming to the IEEE 802.11 standard series in the above example cooperates with other APs to transmit signals, the present invention is not limited thereto. For example, when multiple STAs transmit signals in parallel, the AP can cooperate with other APs to perform receive control as described above. For example, when the distance between an AP's communication partner STA and other APs is close, the other APs can perform receive antenna control to direct nulls toward the STA. In this case, for example, the AP enables the other AP's communication partner STA and its own communication partner STA to transmit signals in parallel, and performs cooperative operation at this time, thereby enabling the other APs to perform receive antenna control. Furthermore, when cooperative communication occurs between STAs, the control described above can be performed. In addition, when multiple communication devices communicate with communication partner devices separately, regardless of the wireless LAN, each communication device can determine whether to perform cooperative communication with other communication devices based on the distance between its communication partner device and other communication devices. Therefore, when the interference between communication devices and communication partner devices, as well as between communication devices and other communication devices, is sufficiently small and cooperative control is not required, the reduction in communication efficiency due to unnecessary performance of cooperative control can be prevented.

[0059] Although transmit antenna control was used in the above embodiments, the present invention is not limited thereto. For example, the AP can prevent interference between its communications and those of other APs by performing predetermined coding (e.g., dirty paper coding (DPC) or similar coding). For example, the AP can specify the type of data to be transmitted from other APs, predict the waveform in advance, and transmit a signal obtained by subtracting the waveform component from the signal to be transmitted from the AP. The communication partner device receives the signal transmitted from the other AP through the waveform. The communication partner device can receive the waveform in which the signal to be transmitted from the AP is reproduced by adding the waveform received from the AP to the interference wave from the other AP. According to this method, the AP obtains information about the data to be transmitted in advance, as well as the channel estimate between the AP's communication partner STA and other APs, and performs cooperative operation to adjust the signal transmission timing, thereby suppressing the effects of interference. In environments where the distance between the AP's communication partner STA and other APs is large, the error in predicting the channel estimate, etc., is large. If the above method is used in such environments, the communication performance degrades. To prevent this, cooperative communication can be performed based on information about the distance between the AP's communication partner and other APs to reduce the effects of interference. In environments where the interference is not strong enough and the interference waveform is buried by noise, it is possible to prevent the interference waveform containing relatively large errors from being subtracted in advance. As a result, it is possible to prevent the degradation of communication performance.

[0060] This invention can be implemented by supplying a program that performs one or more functions of the above embodiments to a system or device via a network or storage medium, and having one or more processors in the computer of the system or device read and execute the program. This invention can also be implemented by circuitry (e.g., an ASIC) for performing one or more functions.

[0061] This invention is not limited to the embodiments described above, and various changes and modifications can be made within the spirit and scope of this invention. Therefore, the following claims are made to inform the public of the scope of this invention.

Claims

1. A communication device that operates as a first access point for communicating with a first station device in a first network managed by the communication device, the communication device comprising: A transmitting unit is configured to transmit a first empty data packet (NDP) to a second station device in a second network managed by a second access point, wherein the second station device transmits first information about the channel state based on the first NDP; and The control unit is configured to perform zero-trap manipulation of the second station device in the second network based on the information sent by the second station device.

2. The communication device according to claim 1, wherein, The transmitting unit transmits a second NDP to the first station device in the network managed by the communication device, wherein the first station device transmits second information about the channel state based on the second NDP; and The control unit performs zero-trap manipulation in cooperation with the second access point based on the first information and the second information.

3. The communication device according to claim 2, wherein, If the transmission of the first NDP and the second NDP occurs within a specific time period, the transmission of the first NDP shall be performed before the transmission of the second NDP.

4. The communication device according to claim 2, wherein, The first NDP and the second NDP are sent periodically.

5. The communication device according to claim 1, wherein, The communication device conforms to the IEEE 802.11 standard series.

6. The communication device according to claim 1, wherein, The first NDP conforms to the IEEE 802.11 standard series.

7. A communication device that operates as a station device in a second network managed by a second access point, the communication device comprising: A receiving unit is configured to receive a first empty data packet (NDP) from a first access point managing a first network; as well as The transmitting unit is configured to transmit first information about the channel state based on the first NDP.

8. The communication device according to claim 7, wherein, The first access point and the second access point perform cooperative zero-dip beamforming based on the first information sent by the communication device.

9. The communication device according to claim 7, wherein, The communication device conforms to the IEEE 802.11 standard series.

10. The communication device according to claim 7, wherein the first NDP conforms to the IEEE 802.11 standard series.

11. A method for controlling a communication device, the communication device operating as a first access point communicating with a first station device in a first network managed by the communication device, the method comprising: Sending a first empty data packet (NDP) to a second station device in a second network managed by a second access point, wherein the second station device sends first information about the channel state based on the first NDP; and Based on the information sent by the second station device, a zero-trap operation is performed on the second station device in the second network.

12. A method for controlling a communication device, the communication device operating as a station device in a second network managed by a second access point, the method comprising: Receive the first empty data packet (NDP) from the first access point managing the first network; as well as Based on the first NDP, first information about the channel state is transmitted.

13. A computer-readable storage medium storing a program that, when executed, causes a communication device to: Send a first empty data packet (NDP) to a second station device in a second network managed by a second access point, wherein, The second station device transmits first information about the channel state based on the first NDP; as well as Based on the information sent by the second station device, a zero-trap operation is performed on the second station device in the second network.

14. A computer-readable storage medium storing a program that, when executed, causes a communication device to: Receive the first empty data packet (NDP) from the first access point managing the first network; and Based on the first NDP, first information about the channel state is transmitted.

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