Wireless base station and wireless terminal

Abstract

The present invention accurately estimates interference to another terminal for cooperative transmission by a plurality of wireless base stations.　This wireless base station comprises a wireless control unit and a communication unit. At the time of cooperative transmission with a cooperative wireless base station, the wireless control unit generates a reference signal for estimating interference given to a wireless terminal connected to another wireless base station, and determines a cooperative transmission-related setting in accordance with the interference estimation result based on the reference signal. The communication unit transmits the reference signal to the another wireless base station or a wireless terminal, and notifies the cooperative wireless base station of the cooperative transmission-related setting.

Description

[Technical field]

[0001] The present technology relates to a radio base station and a radio terminal, and more particularly to a radio base station and a radio terminal in a radio system including a plurality of radio base stations that perform cooperative transmission. [Background technology]

[0002] In wireless LAN, within one basic service set (BSS), an access point (AP or BS) and a terminal (STA or UE) autonomously acquire the right to transmit within the BSS and communicate. When a transmitting terminal is equipped with multiple antennas, transmission using multiple antennas simultaneously (BF: beamforming) allows transmission with high gain to the desired destination terminal, improving the system throughput within the BSS. In general, the gain obtained by beamforming is proportional to the number of antennas used simultaneously. By extending this beamforming, system throughput can be improved by transmission using multiple APs (hereinafter referred to as multi-AP) in cooperation with each other.

[0003] There are several methods for multi-AP, including CJT (Coherent Joint Transmission), which transmits as a virtual single AP with antennas that are the sum of the APs' antennas, and NCJT (Non-Coherent Joint Transmission), which forms a beam for each AP independently and transmits to a common receiving terminal. These are broadly classified as cooperative transmission (JT: Joint Transmission) from multi-AP to a common destination terminal. There is also coordinated nulling, which forms a null for each AP independently to communicate with different terminals without interfering with each other's communication terminals. All of these methods can achieve higher system throughput in an environment with multiple APs than when multiple APs do not cooperate with each other.

[0004] In NCJT and CJT, there is a problem that interference to terminals of other BSSs that are correlated with the propagation path of the desired destination terminal from the perspective of the transmitting terminal also increases, making it impossible to improve the system throughput including other BSSs that are not cooperating. In particular, since CJT provides gains equal to the number of antennas of multiple APs, the increase in the amount of interference to other BSSs becomes more significant. Therefore, in order to maximize the system throughput in transmission by multi-AP, it is necessary to select an appropriate cooperation method according to the propagation path. For example, a technology has been proposed that estimates potential interference in a communication system including multiple wireless devices and stops or modifies transmission (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2019-528636 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned conventional technology, when estimating potential interference, a known beamforming training protocol is used, and it is difficult to reflect information about the propagation path. Therefore, there is a problem that it is difficult to accurately estimate interference due to cooperative transmission.

[0007] This technology was developed in light of these circumstances, and its purpose is to accurately estimate interference caused by cooperative transmission. [Means for solving the problem]

[0008] The present technology has been made to solve the above-mentioned problems, and a first aspect thereof is a radio base station including a radio control unit that generates a reference signal for estimating interference caused to a radio terminal connected to another radio base station when performing cooperative transmission with a cooperative radio base station and determines settings related to the cooperative transmission according to an estimation result of the interference based on the reference signal, and a communication unit that transmits the reference signal to the other radio base station or the radio terminal and notifies the cooperative radio base station of the settings related to the cooperative transmission. This provides an effect of determining a cooperative scheme according to the estimation result of interference and notifying the cooperative radio base station of the cooperative scheme.

[0009] In addition, in the first aspect, the radio control unit may inquire of the other radio base station whether or not measurement for the interference estimation is possible prior to transmitting the reference signal, thereby providing an effect of confirming with the other radio base station whether or not measurement for interference estimation is possible before performing the measurement.

[0010] In addition, in this first aspect, the radio control unit may generate information related to precoding of the reference signal, and the communication unit may transmit the information related to precoding of the reference signal to the cooperative radio base station. This provides an effect of transmitting information related to precoding to the cooperative radio base station.

[0011] In addition, in this first aspect, the information related to the precoding may include information related to a frequency using the reference signal, information related to a codebook predetermined between the cooperative radio base station and the reference signal, and information related to a weighting coefficient to be calculated on the reference signal.

[0012] In addition, in this first aspect, the information on the preceding may include information on a time offset for the cooperative radio base station at the time of transmitting the reference signal. In this case, the information on the preceding may include at least one of information indicating the presence or absence of the time offset and information indicating the time offset.

[0013] Also, in this first aspect, the radio control unit may generate information indicating that the measurement for the interference estimation will be performed prior to transmission of the reference signal, and the communication unit may transmit the information indicating that the measurement for the interference estimation will be performed to the other radio base station. This provides an effect of notifying that the measurement for interference estimation will be performed prior to transmission of the reference signal. In this case, the information indicating that the measurement for interference estimation will be performed may include information regarding a time to transmit the reference signal, a period during which the measurement will be performed, and a frequency at which the measurement will be performed.

[0014] In addition, in this first aspect, the radio control unit may determine a cooperative parameter including at least one of a cooperative transmission scheme, a precoding, a coding scheme, and a transmission power in the cooperative transmission based on an estimation result of the interference from the other radio base station. In this case, the cooperative parameter is determined based on a predetermined criterion.

[0015] In addition, in this first aspect, the reference signal may include information for estimating a propagation path between the radio base station and a radio terminal connected to the radio base station, and the communication unit may transmit the reference signal to the radio terminal connected to the radio base station, thereby providing an effect of estimating the propagation path in parallel with the interference estimation.

[0016] In this first aspect, the cooperative transmission setting notified by the communication unit may include information on the number of the cooperative radio base stations. The cooperative transmission setting notified by the communication unit may further include at least one of information on a cooperative transmission method in the cooperative transmission, information on a transmitting antenna used in the cooperative radio base station, information on the wireless terminal that is a destination in the cooperative transmission, and information on precoding of the wireless terminal that is a destination in the cooperative transmission. The information on precoding of the wireless terminal that is a destination in the cooperative transmission may include information on the number of the wireless terminals that are the destination, information for identifying the wireless terminal that is the destination, and information on a frequency, an encoding method, a transmission power, and a stream used in the cooperative transmission.

[0017] A second aspect of the present technology is a radio base station including: a radio control unit that acquires, from a radio terminal, information on interference to a radio terminal due to cooperative transmission, estimated using a reference signal supplied from any one of a plurality of radio base stations performing cooperative transmission, and generates overall interference information based on the acquired information on the interference, and a communication unit that transmits the overall interference information to any one of the plurality of radio base stations performing cooperative transmission. This provides an effect of generating overall interference information based on individual interference information acquired from the radio terminal, and transmitting the overall interference information to any one of the plurality of radio base stations performing cooperative transmission.

[0018] In the second aspect, the communication unit may request the plurality of radio base stations performing the cooperative transmission to transmit reference signals for estimating interference caused to the radio terminal by the cooperative transmission, thereby providing an effect of performing interference estimation in response to a request from a party other than a party of the cooperative transmission.

[0019] A third aspect of the present technology is a wireless terminal including a wireless control unit that estimates interference caused by cooperative transmission using a reference signal supplied from any one of a plurality of wireless base stations that perform cooperative transmission, and a communication unit that transmits information related to the estimated interference to another wireless base station, thereby providing an effect of estimating interference that the wireless terminal itself receives due to cooperative transmission and transmitting the information to the wireless base station as individual interference information. [Brief description of the drawings]

[0020] [Figure 1] 1 is a diagram illustrating an example of a configuration of a wireless network system according to an embodiment of the present technology. [Diagram 2] 1 is a diagram illustrating an example of a configuration of a wireless communication device 300 according to an embodiment of the present technology. [Diagram 3] 4 is a sequence diagram showing an example of operation of the wireless network system according to the first embodiment of the present technology. FIG. [Figure 4] 11 is a diagram showing an example of a frame configuration of a JT interference scan notification 811 in the first embodiment of the present technology. FIG. [Diagram 5] 11 is a diagram showing an example of a frame structure of a JT interference scan response 812 in the first embodiment of the present technology. FIG. [Figure 6] 11 is a diagram showing an example of a frame configuration of JT scan sector information 813 in the first embodiment of the present technology. FIG. [Figure 7] 11 is a diagram showing an example of a frame configuration of a JT interference scan trigger 815 in the first embodiment of the present technology. FIG. [Figure 8] 11 is a diagram showing an example of the structure of a data unit notified by a JT interference scan 818 in the first embodiment of the present technology. FIG. [Figure 9] 11 is a diagram showing an example of a frame structure of a JT interference report 823 in the first embodiment of the present technology. FIG. [Figure 10] 11 is a diagram showing an example of a frame structure of JT interference feedback 824 in the first embodiment of the present technology. FIG. [Figure 11]11 is a diagram illustrating an example of a frame configuration of a cooperative transmission setting notification 827 according to the first embodiment of the present technology. FIG. [Figure 12] 5 is a flowchart showing an example of a processing procedure of a weight determination process according to the first embodiment of the present technology. [Figure 13] 4 is a flowchart showing an example of a process procedure of cooperative transmission setting determination process according to the first embodiment of the present technology. [Figure 14] FIG. 11 is a sequence diagram showing an example of operation of a wireless network system according to a second embodiment of the present technology. [Figure 15] 13 is a diagram showing an example of a frame configuration of a JT interference scan trigger 831 in the second embodiment of the present technology. FIG. [Figure 16] FIG. 11 is a diagram illustrating an example of a frame configuration of a channel feedback 834 according to the second embodiment of the present technology. [Figure 17] 13 is a flowchart showing an example of a processing procedure of a weight determination process according to the second embodiment of the present technology. [Figure 18] FIG. 13 is a sequence diagram showing an example of operation of a wireless network system according to a third embodiment of the present technology. [Figure 19] FIG. 13 is a diagram showing an example of a frame structure of a JT interference scan request 841 in the third embodiment of the present technology. [Figure 20] A figure showing an example of a frame configuration of a JT interference scan notification 842 in the third embodiment of the present technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, modes for carrying out the present technology (hereinafter, referred to as embodiments) will be described. The description will be made in the following order. 1. First embodiment (example of estimating interference due to cooperative transmission based on reference signal) 2. Second embodiment (example of performing channel estimation in parallel with interference estimation) 3. Third embodiment (example of interference estimation triggered by a request from a party other than the party in cooperative transmission)

[0022] <1. First embodiment> [Wireless network system] FIG. 1 is a diagram showing an example of a configuration of a wireless network system according to an embodiment of the present technology.

[0023] Here, cooperative transmission is assumed in which a master access point (master AP or sharing AP) 101 and a slave access point (slave AP or shared AP) 102 cooperate to perform simultaneous transmission to a wireless terminal (STA) 108 or 109. It is also possible to communicate with the wireless terminals 108 and 109 simultaneously. The master access point 101 and the slave access point 102 performing cooperative transmission are collectively referred to as a multi-AP. The master AP and the slave AP are not fixedly determined by the AP, but may be dynamically determined within the multi-AP. For example, at a certain time t1, AP1 may be the master AP and AP2 may be the slave AP, and at a different time t2, AP1 may be the slave AP and AP2 may be the master AP.

[0024] In a basic service set A (BSS-A), a multi-AP and wireless terminals 108 and 109 are connected. Area 10 is the radio wave coverage area when the multi-AP performs non-JT transmission. Area 11 is the radio wave coverage area when the multi-AP performs JT transmission.

[0025] Basic service set B (BSS-B) is a BSS that has an overlapping area when viewed from BSS-A, that is, an overlapped BSS (OBSS). In BSS-B, an OBSS access point (OBSS-AP) 203 and an OBSS terminal (OBSS-STA) 209 are connected. An area 20 is the range of radio waves from the OBSS access point 203.

[0026] It is assumed that the OBSS access point 203 and the multi-AP are in a mutually transmissible relationship. Also, the radio wave coverage of BSS-A and BSS-B is shown for the same frequency channel.

[0027] Although an example in which the OBSS access point 203 exists within the radio wave coverage of the multi-AP of the BSS-A in non-JT transmission has been shown here, it does not necessarily have to be within the radio wave coverage of the non-JT transmission. For example, any AP of the BSS-A (master AP 101 or slave AP 102) and the OBSS access point 203 may be connected by wire, and may be within the radio wave coverage of different frequency channels.

[0028] [Device configuration] 2 is a diagram showing a configuration example of a wireless communication device 300 according to an embodiment of the present technology. The wireless communication device 300 includes a master AP 101, a slave AP 102, an OBSS-AP 203, wireless terminals 108 and 109, and an OBSS terminal 209. In addition, for example, the wireless communication device 300 may be a wireless communication module or an integrated circuit mounted on these APs and terminals.

[0029] The wireless communication device 300 includes a communication unit 310, a control unit 321, a power supply unit 322, and an antenna 319. There may be multiple communication units 310.

[0030] The communication unit 310 includes a radio control unit 311, a data processing unit 312, a modulation / demodulation unit 313, a signal processing unit 314, a channel estimation unit 315, a radio interface unit 316, and an amplifier unit 317. The radio interface unit 316, the amplifier unit 317, and the antenna 319 form a set, and one or more sets may be components. The function of the amplifier unit 317 may be included in the radio interface unit 316. The communication unit 310 is realized by, for example, an LSI (Large Scale Integration).

[0031] During transmission when data is input from an upper layer, the data processing unit 312 generates packets for wireless transmission from the data, performs processing such as adding a header for media access control (MAC) and adding an error detection code, and supplies the processed data to the modem unit 313. On the other hand, during reception when there is input from the modem unit 313, it performs analysis of the MAC header, detection of packet errors, reordering processing, and provides the processed data to its own protocol upper layer.

[0032] The wireless control unit 311 transfers information between the various units. It also sets parameters for the modem unit 313 and the signal processing unit 314, schedules packets in the data processing unit 312, and sets parameters and controls transmission power for the modem unit 313, the signal processing unit 314, the wireless interface unit 316, and the amplifier unit 317.

[0033] During transmission, the modem unit 313 performs encoding, interleaving, and modulation on input data from the data processing unit 312 based on the encoding method and modulation method set by the radio control unit 311, generates a data symbol stream, and supplies it to the signal processing unit 314. During reception, the modem unit 313 performs processing on the input from the signal processing unit 314 that is the reverse of that during transmission, and supplies the data to the data processing unit 312 or the radio control unit 311.

[0034] During transmission, the signal processing unit 314 performs signal processing for spatial separation on the input from the modulation / demodulation unit 313 as necessary, and supplies the obtained one or more transmission symbol streams to each of the wireless interface units 316. Note that, without spatial separation, an arbitrary delay amount may be applied to each antenna 319 for transmission (hereinafter, cyclic shift delay (CSD)). During reception, the signal processing unit 314 performs signal processing on the reception symbol streams input from each of the wireless interface units 316, and performs spatial decomposition of the streams as necessary, and supplies the streams to the modulation / demodulation unit 313.

[0035] The channel estimation unit 315 calculates complex channel gain information of the propagation path from the preamble portion and the training signal portion of the input signal from each of the wireless interface units 316. The calculated complex channel gain information is used for demodulation processing in the modem unit 313 and spatial processing in the signal processing unit 314 via the wireless control unit 311.

[0036] During transmission, the wireless interface unit 316 converts the input from the signal processing unit 314 into an analog signal, performs filtering, up-conversion to a carrier frequency, and phase control, and sends the signal to the antenna 319 or the amplifier unit 317. During reception, the wireless interface unit 316 performs the reverse processing on the input from the antenna 319 or the amplifier unit 317, and supplies data to the signal processing unit 314 and the channel estimation unit 315.

[0037] During transmission, the amplifier unit 317 amplifies an analog signal input from the wireless interface unit 316 to a predetermined power and sends it to the antenna 319. During reception, the amplifier unit 317 amplifies a signal input from the antenna 319 to a predetermined power and outputs it to the wireless interface unit 316. At least one of the functions of the amplifier unit 317 during transmission and reception may be entirely or partially included in the wireless interface unit 316. Furthermore, at least one of the functions of the amplifier unit 317 during transmission and reception may be entirely or partially a component external to the communication unit 310.

[0038] The control unit 321 controls the wireless control unit 311 and the power supply unit 322. Furthermore, the control unit 321 may carry out at least a part of the operation of the wireless control unit 311 in place of the wireless control unit 311.

[0039] The power supply unit 322 is constituted by a battery power source or a fixed power source, and supplies power to each unit of the wireless communication device 300 .

[0040] Of these components, radio control unit 311 and control unit 321 control each unit to perform the following operations.

[0041] [Operation] FIG. 3 is a sequence diagram showing an example of operation of the wireless network system in the first embodiment of the present technology.

[0042] Here, assume that the first BSS is made up of access points (master AP 101 and slave AP 102) and wireless terminal 109. Also assume that the second BSS is made up of access point OBSS-AP 203 and OBSS terminal 209 (hereinafter, OBSS: Overlapped BSS).

[0043] [JT Interference Scan Notification] First, the master AP 101 sends a notification (JT interference scan announcement) 811 to the OBSS-AP 203, in which the multi-AP requests the OBSS terminal 209 to respond as to whether interference measurement can be performed. At this time, the notification may include information indicating the start time and execution period of the interference measurement. In addition, the subject of sending the JT interference scan notification to the OBSS-AP 203 may be at least one of the master AP 101 and the slave AP 102.

[0044] This JT interference scan notification 811 may be executed after it is determined that multiple APs will perform cooperative transmission 828. However, it is not necessary to execute this JT interference scan notification 811 every time cooperative transmission is performed. This is because, although the amount of interference to the OBSS is estimated in the subsequent JT interference feedback 824, when the time fluctuation of the propagation path is relatively long compared to the period of cooperative transmission, information highly correlated with the information on the amount of interference acquired in the immediately preceding JT interference feedback 824 is obtained, and therefore there is little effect on characteristics even if past information is reused.

[0045] For example, if the multi-AP holds the interference estimation results from the JT interference feedback 824 performed in the past and is within a period in which the propagation path can be considered constant, it may be possible to start from deciding on a cooperation method (826) without executing the JT interference scan notification 811.

[0046] Similarly, outside the period in which the propagation path can be regarded as constant, and if the multi-AP recognizes the existence of the OBSS, the JT interference scan notification 811 may be executed. The JT interference scan notification 811 is an example of the wireless control unit described in the claims.

[0047] [JT Interference Scan Response] The OBSS-AP 203, which has received the response request as to whether interference measurement can be performed, notifies the master AP 101 of whether interference measurement can be performed (JT interference scan response) 812. At this time, the notification may also include the start time and execution period of interference measurement that the OBSS-AP 203 can tolerate. The OBSS-AP 203 may also notify at least one of the master AP 101 and the slave AP 102.

[0048] There are cases where only the slave AP 102 receives a response from the OBSS-AP 203 due to the fact that only the slave AP 102 is specified as the destination of the response notification from the OBSS-AP 203, or the communication quality between the OBSS-AP 203 and the master AP 101 is low. In this case, the slave AP 102 may transfer the response information received from the OBSS-AP 203 to the master AP 101.

[0049] The master AP 101, which has received a response from the OBSS-AP 203 as to whether or not the measurement can be performed, determines whether or not to perform interference measurement with the OBSS based on the received information.

[0050] In addition, when notifying only that the information notified by the JT interference scan notification 811 performed from the multi-AP is executable, an Ack frame or block Ack frame specified in IEEE 802.11 may be sent.

[0051] [JT scan sector information] When the master AP 101 determines to perform interference measurement, the master AP 101 notifies the slave AP 102 of information for performing interference measurement (JT scan sector information) 813. This information includes, but is not limited to, the start time and execution period of the interference measurement, and information indicating a weighting coefficient and a cyclic shift delay value (hereinafter, referred to as precoding) to be multiplied by the antenna used during the interference measurement.

[0052] Furthermore, when the master AP 101 determines to perform interference measurement, it may notify the slave AP 102 of information indicating the start time and execution period of interference measurement for the OBSS-AP 203. The JT scan sector information 813 is an example of a communication unit described in the claims.

[0053] The slave AP 102 that has received the information for performing interference measurement from the master AP 101 notifies the master AP 101 of the reception of the information (Ack) 814. The Ack 814 may be notified as a block Ack defined in IEEE802.11, as necessary.

[0054] The slave AP 102 may notify the master AP 101 of information indicating the requested start time together with the Ack 814. In this case, when the master AP 101, which has received the start time request from the slave AP 102, changes the start time, it may notify the JT scan sector information 813 again.

[0055] [JT Interference Scan Trigger] When the master AP 101 receives Ack 814 from the slave AP 102 and determines that it is near the start time of interference measurement, it executes information notification (JT interference scan trigger) 815 indicating that interference measurement will be performed to the OBSS-AP 203. At this time, information indicating the start time and execution period of the interference measurement may be included, but is not limited to this. Note that the JT interference scan trigger 815 is an example of a communication unit described in the claims.

[0056] In addition, if the master AP 101 determines that the JT interference scan trigger 815 is unlikely to be correctly received by the OBSS-AP 203, for example when the communication quality between the master AP 101 and the OBSS-AP 203 is low, the notification may be sent from both the master AP 101 and the slave AP 102 or only from the slave AP 102.

[0057] The start time of interference measurement is the time indicated by the JT scan sector information 813, but may be determined by the master AP 101 based on information notified from the slave AP 102 together with the Ack 814.

[0058] [OBSS-JT interference scan notification] The OBSS-AP 203, which has received information indicating that interference measurement will be performed from at least one of the master AP 101 and the slave AP 102, issues an information notification (OBSS-JT interference scan announcement) 816 indicating that interference measurement will be performed from multiple APs to the OBSS terminal 209. The information notified by this OBSS-JT interference scan announcement 816 may be information indicating the start time and execution period of the interference measurement, but is not limited to this.

[0059] [JT Interference Scan] A JT interference scan trigger 815 is executed to indicate to the OBSS-AP 203 that interference measurement is to be performed, and the multi-AP, which has determined that it is time to start interference measurement, notifies the OBSS terminal 209 of information including a reference signal for interference measurement (JT interference scan) 818. At this time, the reference signal is transmitted by pre-coding determined between the multi-APs. The pre-coding may be determined based on a DFT (Discrete Fourier Transformation) matrix or information notified in advance by the master AP 101 to the slave AP 102. Furthermore, multiple pre-codings may be applied in a time-division manner. The JT interference scan 818 is an example of a communication unit described in the claims.

[0060] The OBSS terminal 209 that receives the reference signal for interference measurement from the multiple APs estimates the amount of interference for each observed precoding (821). The amount of interference for a precoding is calculated as the received power, but may be calculated by other methods.

[0061] In addition, the multi-AP may execute a trigger 817 that notifies the execution of a JT interference scan 818 immediately before executing the JT interference scan 818.

[0062] [JT Interference Report Trigger, JT Interference Report] After the transmission of the reference signal for interference measurement from the multi-AP to the OBSS terminal 209 is completed, the OBSS terminal 209 issues an information notification (JT interference report) 823 indicating the estimated amount of interference observed to the OBSS-AP 203. At this time, the information notification may be executed after an estimated amount of interference transmission request (JT interference report trigger) 822 is issued from the OBSS-AP 203. The JT interference report 823 is an example of a communication unit or a wireless control unit as described in the claims.

[0063] When there are multiple OBSS terminals 209, JT interference report 823 may be executed by an Orthogonal Frequency Domain Multiple Access (OFDMA) method. In this case, JT interference report trigger 822 may include information indicating the frequency that each OBSS terminal 209 uses in OFDMA.

[0064] [JT interference feedback] The OBSS-AP 203, which has been notified of the information indicating the estimated amount of interference observed from all desired OBSS terminals 209, executes notification (JT interference feedback) 824 of information indicating the results of these estimated amounts of interference to the multi-AP. Note that, although this example shows a case where notification is given to the master AP 101, notification may also be given to at least one of the master AP 101 and the slave AP 102. Note that the JT interference feedback 824 is an example of an estimation result or communication unit of interference from other wireless base stations as described in the claims.

[0065] The multi-AP that has received information indicating the result of the estimated interference amount from the OBSS-AP 203 notifies the OBSS-AP 203 of Ack 825. The Ack 825 may be notified as a block Ack defined in IEEE 802.11 as necessary. Also, while this example shows a case where the master AP 101 notifies the OBSS-AP 203, at least one of the master AP 101 and the slave AP 102 may notify the Ack 825.

[0066] [Cooperative transmission setting decision] The master AP 101, which has received the information indicating the result of the estimated interference amount from the OBSS-AP 203, determines 826 settings related to cooperative transmission with the slave AP 102 based on the notified information. The settings related to the cooperative method include at least one of a cooperative transmission method with the slave AP 102, precoding in cooperative transmission with the slave AP 102, and scheduling including transmission power and MCS (Modulation and Coding Scheme) in cooperative transmission with the slave AP 102.

[0067] [Cooperative transmission setting notification] The master AP 101, which has determined 826 the cooperative transmission settings, issues a notification (cooperative transmission setting notification: JT Scheme Announcement) 827 of information indicating the cooperative transmission settings of the slave AP 102 to the slave AP 102. The cooperative transmission setting notification 827 is an example of a communication unit described in the claims.

[0068] The slave AP 102 that has received the cooperative transmission setting notification 827 from the master AP 101 may notify the master AP 101 of an Ack. This Ack may be notified as a block Ack defined in IEEE 802.11 as necessary.

[0069] When the settings for the coordinated transmission are completed by the coordinated transmission setting notification 827, the master AP 101 and the slave AP 102 perform coordinated transmission 828 based on the settings. At this time, the OBSS-AP 203 can transmit data 829 to the OBSS terminal 209 independently of the coordinated transmission by the multi-AP.

[0070] [Frame composition] The configuration of each frame etc. described in the above sequence diagram will be described in detail below.

[0071] [JT Interference Scan Notification] FIG. 4 is a diagram showing an example of a frame configuration of a JT interference scan notification 811 in the first embodiment of the present technology.

[0072] This JT interference scan notification 811 is used by the multi-AP to notify the OBSS-AP 203 that is the target of interference measurement of the start time and execution period when the multi-AP executes a JT interference scan 818, and to request a response of the request values ​​related to these from the OBSS-AP 203. This frame is composed of, but is not limited to, a "frame control" and a "JT interference scan notification element" as shown below.

[0073] "Frame Control" includes information indicating that this frame is a frame to be notified as a JT interference scan notification 811. However, it does not have to be included only in "Frame Control", and may be configured to indicate that this frame is a JT interference scan notification 811 by combining with other information in this frame. For example, it may be configured so that it can be interpreted in combination with the value of any field in the "JT interference scan notification element".

[0074] The "JT Interference Scan Announcement element" includes at least one of the following fields: "Element ID", "Frequency band", "Number of multi-APs", "Scan start time", and "Scan execution period".

[0075] "Element ID" includes information indicating that this element is a JT interference scan notification element and information indicating the bit length of this element. Note that "Element ID" shown hereafter includes information indicating the same information as this "Element ID". However, if it is determined that an element must always exist, "Element ID" may be omitted.

[0076] "Frequency Band" (BW: Band Width) includes information indicating the requested value of the frequency band for which the multi-AP will perform the JT interference scan 818. "Multi AP Number" includes information indicating the number of access points that will perform the JT interference scan 818. "Scan Start Time" includes information indicating the start time of the JT interference scan 818 requested by the multi-AP. "Scan Duration" includes information indicating the execution duration of the JT interference scan 818 requested by the multi-AP.

[0077] [JT Interference Scan Response] FIG. 5 is a diagram showing an example of a frame configuration of a JT interference scan response 812 in the first embodiment of the present technology.

[0078] This JT interference scan response 812 is used by the OBSS-AP 203, which has received a JT interference scan notification 811 from the multi-AP, to notify information related to the execution of the JT interference scan 818, such as whether or not to perform a JT interference scan 818, the start time, and the execution period, based on the notified information. This frame is composed of, but is not limited to, a "frame control" and a "JT interference scan response element", as shown below.

[0079] The "frame control" includes information indicating that this frame is a frame to be notified as a JT interference scan response 812. However, it does not have to be included only in the "frame control", and may be configured to indicate that this frame is a JT interference scan response 812 by combining with other information in this frame. For example, it may be configured so that it can be interpreted in combination with the value of any field in the "JT interference scan response element".

[0080] The "JT Interference Scan Response element" includes at least one of the following fields: "Element ID", "Frequency band", "Number of terminals", "Scan permission", "Scan start time", and "Scan execution period".

[0081] "Frequency Band" (BW) includes information indicating a frequency band requested by OBSS-AP203 for the frequency band used by multi-AP in JT interference scan 818. "Number of Terminals" (STA Number) includes information indicating the number of wireless terminals connected to OBSS-AP203 in the OBSS. "Scan Grant" includes information indicating a request to multi-AP as to whether or not OBSS-AP203 can execute JT interference scan 818. "Scan Start Time" includes information indicating a start time requested by OBSS-AP203 for JT interference scan 818 performed by multi-AP. "Scan Duration" includes information indicating the execution duration of JT interference scan 818 requested by OBSS-AP203 for JT interference scan 818 performed by multi-AP.

[0082] The multi-AP that receives the JT interference scan response 812 may determine whether or not to perform the JT interference scan 818 based on the information indicated by the "number of terminals." Also, if the "scan permission" includes information indicating a denial of execution of the JT interference scan 818 for the multi-AP, the "scan start time" and "scan execution period" do not need to exist.

[0083] [JT scan sector information] FIG. 6 is a diagram showing an example of a frame configuration of JT scan sector information 813 in the first embodiment of the present technology.

[0084] This JT scan sector information 813 is used for the master AP 101 to notify the slave AP 102 of information required to perform a JT interference scan 818. As shown below, this frame is composed of, but not limited to, a "frame control", a "JT interference scan control element", and a "JT interference scan information element". Note that the "JT interference scan control element" and the "JT interference scan information element" may be defined together as one element without being separated.

[0085] The "frame control" includes information indicating that this frame is a frame to be notified as JT scan sector information 813. However, it does not have to be included only in the "frame control", and may be configured to indicate that this frame is JT scan sector information 813 by combining with other information in this frame. For example, it may be configured so that it can be interpreted in combination with the value of any field in the "JT interference scan control element".

[0086] The "JT Interference Scan Control element" includes, but is not limited to, information for estimating in advance the length of each field in the following "JT Interference Scan Information Element". In addition to the "Element ID", this element includes at least one of the following fields: "Frequency Band", "Scan Sector Information", and "Time Synchronization".

[0087] "Frequency Band" (BW) includes information indicating the frequency band in which the JT interference scan 818 is performed. "Scan Sector Information" includes information indicating the number, type, and format of each "Sector ID" field in the subsequent "JT Interference Scan Information Element." "Time Synchronization" includes information regarding the transmission timing between the master AP 101 and the slave AP 102 when the JT interference scan 818 is performed in multi-AP. Note that "Time Synchronization" is an example of information regarding the time offset described in the claims.

[0088] The "scan sector information" includes at least one of the subfields "sector number", "slave AP antenna mask", "codebook information", "slave AP index", and "quantization granularity".

[0089] The "Sector Number" includes information indicating the number of precodings used in the JT interference scan 818. The "Slave AP Ant Mask" includes information indicating the antenna of the slave AP 102 used in the JT interference scan 818. The "Codebook Information" includes information indicating whether or not to use a precoding candidate that is determined in advance between the master AP 101 and the slave AP 102 for use in the JT interference scan 818. The "Slave AP Nr Index" includes information specifying the range of precoding candidates to be applied by each slave AP 102. The "Quantization Granularity" includes information indicating how many bits of information each numerical value constituting the precoding is represented by.

[0090] A number of types of precoding are notified, and information indicating each type is stored in the "sector ID" field in the following "JT interference scan information element". For example, when precoding candidates are predefined between the master AP 101 and the slave AP 102 as DFT matrices, information indicating the row number of the precoding to be used by the slave AP 102 among the precoding candidates is stored in the "slave AP index". On the other hand, when precoding candidates are not predefined between the master AP 101 and the slave AP 102, it is necessary to notify the precoding matrix, and the "quantization granularity" is used to understand the precoding matrix from the information stored in the "sector ID" field.

[0091] Additionally, "Time Sync" includes at least one of the subfields "Flag" and "Time".

[0092] The "Flag" includes information indicating whether, when the multi-AP performs the JT interference scan 818, the transmission timing is shifted between the master AP 101 and the slave AP 102. When the "Flag" includes information indicating that the JT interference scan 818 is performed with shifted transmission timing, the "Time" includes information indicating the value of the shifted transmission timing.

[0093] The "flag" and "time" may be implemented as follows. That is, for example, when "flag" is set to "1", it indicates that the transmission timing is shifted between the master AP 101 and the slave AP 102, and the transmission timing may be read according to the information indicated by "time". Also, for example, when "time" is set to "0", it may indicate that the master AP 101 and the slave AP 102 transmit simultaneously without shifting the timing. The "flag" is an example of information indicating the presence or absence of a time offset as described in the claims. Also, the "time" is an example of information indicating a time offset as described in the claims.

[0094] The "JT Interference Scan Information element" includes, but is not limited to, detailed information of the precoding used in the JT interference scan 818 that is not included in the "JT interference scan control element". In addition to the "Element ID", this element includes a "Sector ID" field.

[0095] "Sector ID" includes information indicating a precoding matrix. There are a total of Nscan fields in this "Sector ID" field, and Nscan is determined based on the value of the "Sector Number" subfield in the "JT interference scan control element". The information indicated by this "Sector ID" is used in the JT interference scan 818 when generating TRN, which is a sequence for estimating the amount of interference in multi-AP, and is information indicating Q, which will be described later. Note that "Slave AP index", "quantization granularity" and "Sector ID" are examples of weighting coefficients described in the claims.

[0096] [JT Interference Scan Trigger] FIG. 7 is a diagram showing an example of a frame configuration of a JT interference scan trigger 815 in the first embodiment of the present technology.

[0097] This JT interference scan trigger 815 is used when the multi-AP notifies the OBSS-AP 203 of information indicating the timing for performing a JT interference scan 818. This frame is composed of, but is not limited to, a "frame control" and "JT interference scan information" as shown below.

[0098] The "frame control" includes information indicating that this frame is a frame to be notified as the JT interference scan trigger 815. However, it does not have to be included only in the "frame control", and may be configured to indicate that this frame is the JT interference scan trigger 815 by combining with other information in this frame. For example, it may be configured so that it can be interpreted in combination with the value of any field in the "JT interference scan information".

[0099] "JT Interference Scan Information" includes, but is not limited to, information indicating the timing of performing a JT interference scan 818. This field includes, but is not limited to, the subfields "frequency band", "scan start time", and "scan execution period".

[0100] "Frequency Band" (BW) includes information indicating the frequency channel on which the multi-AP performs the JT interference scan 818. "Scan Start Time" includes information regarding the time on which the multi-AP performs the JT interference scan 818. "Scan Duration" includes information indicating the period on which the multi-AP performs the JT interference scan 818. Note that the "Scan Start Time" is an example of information regarding the time on which the reference signal is transmitted as described in the claims. Also, the "Scan Duration" is an example of information regarding the period on which the measurement as described in the claims is performed. Also, the "Frequency Band" is an example of information regarding the frequency on which the measurement as described in the claims is performed.

[0101] [JT Interference Scan] FIG. 8 is a diagram showing an example of the structure of a data unit notified by a JT interference scan 818 in the first embodiment of the present technology.

[0102] This data unit is transmitted from the multi-AP to the OBSS terminal 209 in order to estimate the amount of interference. This data unit is composed of, but is not limited to, the fields "Legacy", "EHT-SIG", "EHT-STF", "EHT-LTF", and "TRN#1" through "TRN#N".

[0103] "Legacy" is used to estimate propagation path information required for time synchronization, frequency synchronization, and demodulating the subsequent frames when receiving this data unit. It may be a sequence that is known in advance between the transmitting and receiving terminals. It may also be used for purposes other than these.

[0104] The "EHT-SIG" includes information indicating the number of subsequent "TRN#1" to "TRN#N" fields, and information about each "TRN" field. Note that the components of the "EHT-SIG" are not limited to these. The "EHT-SIG" includes at least one of the fields of "TRN length", "TRN number", "precoding number", and "subcarrier allocation".

[0105] "TRN Length" includes information regarding the total number of bits of the following "TRN#1" to "TRN#N". "TRN Number" includes information regarding the subfield length of the "IEF (Interference Estimation Field)" in each "TRN" field. "Precoding Number" includes information regarding the precoding used in the following "TRN". "Subcarrier Allocation" includes information required to separate multiple precodings when they are multiplexed in the "IEF" in the following "TRN" field. Note that "Precoding Number" may include information indicating the number of precodings used in the following "IEF". Also, "Subcarrier Allocation" may include information indicating the subcarriers allocated to each precoding.

[0106] "EHT-STF" and "EHT-LTF" are used together with "Legacy" to perform time synchronization and frequency synchronization. As with "Legacy", they may be known sequences between transmitting and receiving terminals in advance, and their usage is not limited to these purposes.

[0107] "TRN#1" to "TRN#N" are training sequences used to estimate the amount of interference for any preceding in the OBSS terminal 209. Each "TRN" field includes an "IEF" which is a known sequence for estimating the amount of interference in the OBSS terminal 209, but the components are not limited to this.

[0108] The "IEF" (Interference Estimation Field) includes a sequence for estimating the amount of interference for any preceding in the OBSS terminal 209. The "IEF" in "TRN#L" may be a known sequence shown below.

number

[0109] Here, m is a number representing the access points that make up the multi-AP. L is the ordinal number of "TRN". TRN#L (m) (k, q) represents a baseband transmission signal at discrete time q from the kth antenna transmitting the Lth "TRN" field to the mth access point.

[0110] However, Q c(L,i) (rm) indicates the c(L,i)th column and the row indicated by rm for a matrix indicated by Q below. A column vector q1 of Q is referred to as a precoding vector. Q=[q1 q2 … q NDFT-1 ]

[0111] Furthermore, c(L,i) is the column number of the precoding vector multiplexed in the "IEF" of "TRN#L". rm is a group of row numbers of the precoding vector assigned to the mth access point among the access points constituting the multi-AP. numel(rm) is the number of elements of rm. K is a normalization coefficient. Np(L) is the number of precoding vectors simultaneously applied in the "IEF" in the Lth "TRN" subfield. Nf(i) is the number of subcarriers to which the c(L,i) precoding vector is applied. ki(j) is the jth subcarrier to which the c(L,i) precoding vector is applied. NDFT is the number of points of the IDFT (Inverse Discrete Fourier Transformation) used in the OFDM modulation method. q represents discrete time.

[0112] The following are specific examples of Q, but the present invention is not limited to these. For example, when all of the access points constituting a multi-AP transmit "TRN" simultaneously in cooperation with each other, Q may be a DFT (Discrete Fourier Transformation) matrix or a Hadamard matrix as shown below, but is not limited to these.

number

[0113] In addition, Q may be a matrix determined based on channel estimation information previously obtained by the multi-AP, instead of a matrix determined regardless of the channel estimation information as described above. For example, if a candidate for a precoding vector to be used between the multi-AP is known in advance, the candidate may be used.

[0114] Furthermore, Q may be expressed so that precoding can be performed in a time-division manner between the master AP 101 and the slave AP 102. Specifically, the following matrix may be applied.

number

[0115] N in the above formula MultiAP Q represents the number of access points that make up the multi-AP. i represents a set of precoding vectors that are applied only to the i-th access point that configures the multi-AP. i is N i The precoding vector in the above formula (1) is Q m The value may be the line number of the i may be determined based on a DFT matrix or a Hadamard matrix.

[0116] Equation (2) shows an example in which precoding is performed in cooperation with multiple APs, and equation (3) shows an example in which precoding is performed in a time-division manner for each access point that makes up the multi-AP, but a Q that combines both may also be defined.

[0117] [JT Interference Report] FIG. 9 is a diagram showing an example of a frame structure of a JT interference report 823 in the first embodiment of the present technology.

[0118] This JT interference report 823 is used by the OBSS terminal 209 that received the JT interference scan 818 from the multi-AP to notify the OBSS access point 203 of the estimated amount of interference. This frame is composed of, but is not limited to, a "frame control", a "JT interference report control element" and a "JT interference report element".

[0119] The "frame control" includes information indicating that this frame is a frame to be notified as a JT interference report 823. However, it does not have to be included only in the "frame control", and may be configured to indicate that this frame is a JT interference report 823 when combined with other information in this frame. For example, it may be configured so that it can be interpreted in combination with the value of any field in the "JT interference report control element".

[0120] The "JT Interference Report Control element" includes, but is not limited to, information for estimating in advance the length of each field in the following "JT Interference Report element". In addition to the "element ID", this element includes at least one of the following information: "frequency band", "number of observed precodings", and "receive antenna mask".

[0121] "Frequency Band" (BW) includes information indicating the frequency band of the estimated interference amount. "Observed Precoding Number" includes information indicating the number of precoding vectors for which interference was estimated. "Receive Antenna Mask" (RX Antenna Mask) includes information regarding the receive antenna of the OBSS terminal 209 used when interference was estimated. Note that "Observed Precoding Number" may include information indicating the number of "Sector Information" in the subsequent "JT Interference Report Element".

[0122] The "JT Interference Report element" in combination with the "JT Interference Report Control element" indicates, but is not limited to, the amount of interference estimated by the JT interference scan 818. In addition to the "Element ID", this element includes the following "Sector Information".

[0123] "Sector Info. #1" through "Sector Info. #M" include information about each observed precoding vector. Each "Sector Info. #i" includes a "Precoding ID #i" and an "Interference Level #i" subfield. "Precoding ID" includes information indicating the observed precoding vector. "Interference Level" includes information indicating the amount of interference of the observed precoding vector. "Interference Level" may include, for example, information indicating the SNR (Signal-to-Noise Ratio) in the observed frequency band or the received signal strength.

[0124] [JT interference feedback] FIG. 10 is a diagram showing an example of a frame structure of the JT interference feedback 824 in the first embodiment of the present technology.

[0125] This JT interference feedback 824 is used by the OBSS-AP 203 that has received the JT interference report 823 from the OBSS terminal 209 to notify information regarding the amount of interference estimated in all OBSS terminals 209. As shown below, this frame is made up of, but is not limited to, a "frame control", a "JT interference scan control element" and a "JT interference feedback element".

[0126] The "frame control" includes information indicating that the present frame is a frame to be notified as JT interference feedback 824. However, it does not have to be included only in the "frame control", and may be configured to indicate that the present frame is JT interference feedback 824 by combining with other information in the present frame. For example, it may be configured so that it can be interpreted in combination with the value of any field in the "JT interference scan control element".

[0127] The "JT Interference Scan Control element" includes, but is not limited to, information for estimating in advance the length of each field in the following "JT Interference Feedback element". In addition to the "element ID", this element includes at least one field for "frequency band" and "number of precoding".

[0128] The "frequency band" (BW) includes information indicating a frequency band of the estimated interference amount notified in the subsequent "JT interference feedback element". The "precoding number" includes the number of precoding vectors of the estimated interference amount notified in the subsequent "JT interference feedback element". The "precoding number" may include information indicating the number of "sector information" fields in the subsequent "JT interference feedback element".

[0129] The "JT Interference Feedback element" in combination with the "JT Interference Scan Control element" indicates, but is not limited to, the amount of interference estimated at all OBSS terminals 209 to which a JT interference report 823 has been transmitted. This element includes "sector information" in addition to the "element ID".

[0130] "Sector Info. #1" through "Sector Info. #M" include information indicating the estimated amount of interference in all OBSS terminals 209 from which the OBSS-AP 203 has received a JT interference report 823 for any of the precoding vectors used in the JT interference scan 818. Each "Sector Info. #i" field includes a "Precoding ID #i", an "Interference level #i" and a "Number of interfering terminals #i", but the components of the "Sector Info. #i" field are not limited to these.

[0131] "Precoding ID" includes information indicating the precoding vector referred to in "Sector Information". "Interference Level" includes information indicating the amount of interference estimated by the OBSS terminal 209 for the target precoding vector. "Interfered STA Num" includes information indicating the number of OBSS terminals 209 whose estimated amount of interference for the target precoding vector exceeds a certain threshold.

[0132] For example, in "sector information #k", "precoding ID #k" includes information indicating the k-th column precoding vector of the precoding matrix used in the JT interference scan 818. Also, "interference level #k" includes information indicating the total value of received power that exceeds a certain threshold among received powers observed in the k-th column precoding vector at the OBSS terminal 209. "Number of interfering terminals #k" includes information indicating the number of OBSS terminals 209 whose received powers observed in the k-th column precoding vector exceed a certain threshold.

[0133] [Cooperative transmission setting notification] FIG. 11 is a diagram showing an example of a frame configuration of the cooperative transmission setting notification 827 in the first embodiment of the present technology.

[0134] This cooperative transmission setting notification 827 is used by the master AP 101, which has received the JT interference feedback 824 from the OBSS-AP 203, to notify the slave AP 102 of the result after determining one or more of the cooperative method in multi-AP, the weighting factor in the cooperative method, the MCS (Modulation and Coding Scheme), and the transmission power based on the received notification information. Note that the information to be notified is not limited to these. This frame is composed of "frame control", "multi-AP control", "cooperative transmission element", and "null steering element", but it is not necessary that all of them are included. For example, this frame may be configured so that either the "cooperative transmission element" or the "null steering element" exists exclusively.

[0135] "Frame control" includes information indicating that this frame is a frame notified as a cooperative transmission setting notification 827. However, it does not have to be included only in "frame control", and may be configured to indicate that this frame is a cooperative transmission setting notification 827 by combining with other information in this frame. For example, it may be configured so that it can be interpreted in combination with the value of any field in "multi-AP control".

[0136] "Multi AP Control" is used to notify the slave AP 102 of the cooperative method in multi AP. Note that the notification content of this field is not limited to this. This field includes a subfield of "Multi AP method", but the components are not limited to this. Note that "Multi AP Control" is an example of information regarding the number of cooperative wireless base stations described in the claims.

[0137] The "Multi AP Scheme" includes information indicating a multi-AP cooperation scheme. The "Multi AP Scheme" may include information indicating, for example, whether or not to implement either Joint Transmission or Coordinated Nulling.

[0138] The "Joint Transmission element" is used to notify the necessary parameters when performing joint transmission among multiple APs. In addition to the "element ID", this element includes one or more of the following fields: "cooperation method", "slave AP transmission antenna mask", "terminal information", and "weight", but the components are not limited to these.

[0139] "JT Scheme" includes information indicating the cooperative scheme used in cooperative transmission. "Slave AP Tx Antenna Mask" includes information indicating the transmitting antenna used by the slave AP 102 when cooperative transmission is performed. "STA Info" includes information regarding the destination terminal to which data is transmitted by cooperative transmission when cooperative transmission is performed. "Weight" includes information regarding the weighting coefficient and transmission power used in multi-AP when cooperative transmission is performed.

[0140] In addition, the "weight" may include information indicating a weighting factor indicated in any of the formats of Compressed Feedback, Non Compressed Feedback, and CSI Feedback defined in IEEE802.11, as well as information indicating parameters that can be used to calculate these as weighting factors.

[0141] In addition, the "terminal information" may include one or more subfields of "number of terminals" and information corresponding to each terminal. The information corresponding to each terminal may include, but is not limited to, one or more of "terminal ID", "SS number", "subcarrier frequency band", "transmission power", and "MCS".

[0142] The "number of terminals" (STA Num) includes information indicating the number of terminals to which the cooperative transmission is to be performed. Therefore, the following information is a number (N STA ) are included.

[0143] "Terminal ID #1" (AID #1) through "Terminal ID #N STA " (AID #N STA ) includes information indicating each destination terminal. STA " (SS Number #N STA) includes information indicating the number of the stream to be assigned to each destination terminal. STA " (BW #N STA ) includes information indicating the frequency band to be assigned to each destination terminal. STA " (Tx Power #N STA ) includes information indicating the transmission power to be allocated to each destination terminal. STA " "MCS #N STA ) includes information indicating the MCS to be assigned to each destination terminal. Note that for a terminal to which multiple streams are assigned, "MCS" may include information indicating the MCS of each stream.

[0144] The fields and subfields of the "cooperative transmission element" may include the following information:

[0145] For example, the "cooperative method" may include information indicating whether CJT (Coherent Joint Transmission) or NCJT (Non-Coherent Joint Transmission) is to be executed. Also, the "number of terminals" may include the number of subfields (N STA In addition, when the information indicating that the "cooperative method" executes the CJT is included, the "transmission power" does not have to be present.

[0146] Furthermore, for the k-th terminal that is the destination of the cooperative transmission, "Terminal ID #k" may include a value determined by the MAC address. Furthermore, "SS number #k" may include information that can be used in combination with the "weight" field to determine a weighting coefficient. Furthermore, "Subcarrier frequency band #k" may include information indicating the subcarriers to be allocated in the cooperative transmission. Furthermore, "Transmission power #k" may include information indicating the average value of the transmission power to be allocated to each subcarrier.

[0147] The "Null-Steering element" is used to notify the necessary parameters when performing null-steering in multi-AP. This null-steering is a communication method that forms a null for undesired communication terminals. In addition to the "element ID", this element includes at least one or more fields of "slave AP transmission antenna mask" and "weight", but the components are not limited to these.

[0148] The "Weight" includes information indicating a vector that forms a null when null steering is performed. The "Slave AP TX Antenna Mask" includes information indicating the transmission antenna of the slave AP 102 when applying the vector indicated by the "Weight".

[0149] As a specific example, when a vector P indicated by "weight" is expressed as a matrix p as shown in the following equation, a precoding vector w implemented as null steering in the slave AP 102 may be calculated as follows:

number

[0150] In the above formula, H is the estimated propagation path information between the desired destination terminal (hereinafter, STA#3) of the slave AP 102 and the slave AP 102. N 2 represents the noise power that can be observed at STA♯3. H represents the complex conjugate transpose of matrix A. Also, "max. eigenvector{A}" represents the eigenvector with the largest eigenvalue among the eigenvectors of matrix A.

[0151] [Processing Procedure] FIG. 12 is a flowchart showing an example of a processing procedure of the weight determination processing according to the first embodiment of the present technology.

[0152] Here, the master AP 101, which has received a JT interference scan response 812 from the OBSS-AP 203 and determined to perform a JT interference scan 818, determines the weight to be notified to the slave AP 102 in the JT scan sector information 813. The weight determined here corresponds to the precoding used in the JT interference scan 818.

[0153] The master AP 101 , which has decided to perform the JT interference scan 818 , starts calculating the precoding matrix to be used in the JT interference scan 818 .

[0154] First, it is determined whether to calculate the precoding (weight) of the JT interference scan based on the stored CSI information (propagation path information: Channel State Information) (step S913). That is, CSI information between a terminal that can be a destination in the cooperative transmission 828 and multi-AP is obtained, and it is determined whether to calculate a precoding matrix based on this CSI information.

[0155] It is assumed that the JT interference scan 818 can be performed using a precoding matrix (hereinafter referred to as known precoding or codebook) that is determined in advance among multiple APs, regardless of CSI information. Therefore, whether or not to use known precoding in the JT interference scan 818 may be determined based on the execution time of the JT interference scan 818. For example, when it is determined that the number of precoding vectors to the terminal that is the destination in the cooperative transmission 828 is smaller than the number of known precoding vectors, it may be determined to use a precoding vector calculated based on the CSI information without using known precoding.

[0156] When it is determined that known preceding is to be used in the JT interference scan 818 (step S913: No), the master AP 101 stores information indicating that known preceding is to be used in the JT interference scan 818 in the "codebook information" in the JT scan sector information 813 (step S916). Then, information indicating the preceding to be used in the JT interference scan 818 among the known preceding is stored in the "sector ID".

[0157] On the other hand, when it is determined that the JT interference scan 818 is to be performed by the precoding calculated using the CSI information (step S913: Yes), the master AP 101 first calculates the precoding to be applied in the JT interference scan 818 based on the CSI information (step S914).Then, the master AP 101 stores information indicating that the JT interference scan 818 is to be performed using the calculated precoding in the "codebook information" in the JT scan sector information 813 (step S915).

[0158] As a specific example, the following Q may be applied as precoding, but the present invention is not limited to this.

number

[0159] FIG. 13 is a flowchart showing an example of a process procedure of the cooperative transmission setting determination process according to the first embodiment of the present technology.

[0160] Here, the master AP 101 that receives the JT interference feedback 824 from the OBSS-AP 203 determines one of the multi-AP cooperative method, MCS, and transmission power in cooperative transmission 828 .

[0161] The master AP 101 that has received the JT interference feedback 824 determines a cooperative transmission setting based on the notified information on the estimated amount of interference in the OBSS terminal 209 (step S921).

[0162] First, whether or not to implement CJT is determined depending on whether the amount of interference to OBSS terminal 209 exceeds a threshold if CJT is to be implemented (step S922). Specifically, the amount of interference of OBSS terminal 209 is estimated for CJT weights determined as described below. The CJT weights are calculated based on CSI information between multi-AP and OBSS terminal 209, and may be obtained using SVD (Singular Vector Decomposition), MMSE (Minimize Maximum Square Error), water filling theorem, or the like. Note that the weights are represented by complex numbers, and the norm of the weights represents the transmission power.

[0163] If it is decided to implement CJT (step S922: No), the MCS is calculated for the CJT weight (step S928), and the CJT weight and MCS are notified to the slave AP 102 in a cooperative transmission setting notification 827 (step S929).

[0164] On the other hand, if it is decided not to implement CJT (step S922: Yes), it is determined whether or not to implement NCJT (step S923). Specifically, as described below, the weight of NCJT is determined, and the amount of interference from OBSS terminal 209 corresponding to it is estimated. If it is decided to implement NCJT (step S923: No), the MCS is calculated for the NCJT weight (step S926), and the NCJT weight and MCS are notified to slave AP 102 in cooperative transmission setting notification 827 (step S927).

[0165] If it is determined that NCJT is not to be performed (step S923: Yes), it is determined that cooperative transmission 828 is to be performed by Non-Joint Transmission (Non-JT). Note that even in the case of Non-JT, the method of Non-JT is determined, including whether or not to perform Coordinated Nulling.

[0166] Whether or not coordinated nulling can be implemented is determined by comparing the number of receiving antennas of all destination terminals used in cooperative transmission 828 with the total number of transmitting antennas of the multi-AP. If the total number of transmitting antennas of the multi-AP is greater, coordinated nulling is implemented; otherwise, precoding calculated by ZF (Zero Forcing), MMSE (Minimize Maximum Square Error), etc. may be used.

[0167] If it is decided to implement Non-JT (step S923: Yes), the MCS is calculated for the weight of Non-JT (step S924), and the weight and MCS of Non-JT are notified to the slave AP 102 in a cooperative transmission setting notification 827 (step S925).

[0168] As a specific example of judging whether the above-mentioned CJT or NCJT can be performed, the following can be used. Here, for the precoding vectors performed in the JT interference scan 818, the total amount of interference of the OBSS terminal 209 with respect to the k-th precoding vector precoded in cooperation between multiple APs is calculated as I CJT (k) In addition, the total amount of interference from the OBSS terminal 209 with respect to the l-th precoding vector of the m-th access point, which is precoded in a time-division manner for each access point constituting the multi-AP without coordination between the multi-APs, is expressed as I NCJT (m,l) The threshold is expressed as I Thr , I Thr '. Note that I CJT (k) , I NCJT(m,l) Both of these are information indicated by the “sector information” field in the JT interference feedback 824 from the OBSS-AP 203 .

[0169] As the implementation criteria for CJT, it may be decided to implement CJT when the following is satisfied.

number

[0170] Here, W CJT represents the precoding matrix when CJT is implemented. Also, diag[] represents a diagonal matrix with each element being a diagonal component. Also, N T is the maximum value of k reported in the JT interference scan 818.

[0171] As another example, it may be determined that the CJT is performed when the following formula is satisfied, instead of the above formula:

number

[0172] As the implementation criteria for NCJT, it may be decided to implement NCJT when the following are met:

number

[0173] Here, W NCJT (m) represents the precoding matrix of the mth access point constituting the multi-AP when NCJT is performed. T (m) is the maximum value of l at the mth access point reported in the JT interference scan 818.

[0174] As another example, it may be determined that NCJT is performed when the following formula is satisfied, instead of the above formula:

number

[0175] In this way, according to the first embodiment of the present technology, by transmitting a reference signal (TRN) during the JT interference scan 818, the OBSS terminal 209 can estimate interference due to cooperative transmission.

[0176] <2. Second embodiment> In the above-described first embodiment, it is assumed that CSI information is obtained, but in this second embodiment, it is assumed that CSI information of the wireless terminal 109 is estimated during JT interference scan 818. Note that the configurations of the wireless network system and the wireless communication device are similar to those of the above-described first embodiment, and therefore detailed description thereof will be omitted.

[0177] [Operation] FIG. 14 is a sequence diagram showing an example of operation of the wireless network system in the second embodiment of the present technology.

[0178] The operation of the second embodiment is basically the same as that of the first embodiment described above, except for the following points.

[0179] [JT Interference Scan Trigger] When the master AP 101 receives an Ack 814 from the slave AP 102 and determines that it is near the start time of interference measurement, it also transmits to the wireless terminal 109 when executing a JT interference scan trigger indicating to the OBSS-AP 203 to perform interference measurement. The frame notified by this JT interference scan trigger 831 is the same as that in the above-mentioned first embodiment, but the wireless terminal 109 that has received this JT interference scan trigger 831 is set so that it can estimate propagation path information at the time when the JT interference scan 832 is notified. The time when the JT interference scan 832 is notified is determined by information included in the "scan start time" in the JT interference scan trigger 831.

[0180] [JT Interference Scan] A JT interference scan trigger 831 is executed, indicating to the OBSS-AP 203 that interference measurement should be performed, and the multi-AP determines that the time to start interference measurement has arrived.In this second embodiment, the multi-AP notifies the wireless terminal 109 of a JT interference scan 832, in addition to the OBSS terminal 209 in the first embodiment described above.

[0181] The wireless terminal 109 that receives the reference signal from the multi-AP by the JT interference scan 832 estimates propagation path (channel) information (833). Also, unlike the OBSS terminal 209, the propagation path information may be estimated for each precoding, or the propagation path information may be estimated based on "EHT-LTF", which is a reference signal portion to which no precoding is applied.

[0182] [Channel Feedback] The wireless terminal 109 that has been notified of the JT interference scan 832 from the multi-AP notifies the multi-AP of the estimated propagation path information by channel feedback 834. The timing of this channel feedback 834 may be determined based on the reception of the JT interference scan trigger 831, or may be performed when it is determined that the JT interference scan 832 has ended.

[0183] [Frame composition] The configuration of each frame added in the second embodiment will be described in detail below.

[0184] [JT Interference Scan Trigger] FIG. 15 is a diagram showing an example of a frame configuration of a JT interference scan trigger 831 according to the second embodiment of the present technology.

[0185] The frame of the JT interference scan trigger 831 in the second embodiment is basically the same as the JT interference scan trigger 815 in the first embodiment described above. However, unlike the first embodiment, when the JT interference scan trigger 831 estimates the amount of interference of the OBSS terminal 209 and simultaneously estimates the channel of the wireless terminal 109, the value indicated by the "frame control" may be different from the case where only the amount of interference of the OBSS terminal 209 is estimated. This is because, when the frame notified by the JT interference scan trigger 831 does not include information for the wireless terminal 109 to decide whether or not to perform channel estimation, it is necessary to notify the wireless terminal 109 by the immediately preceding JT interference scan trigger 831 that channel estimation will be performed in the subsequent JT interference scan 832. Note that the frame may be configured so that the wireless terminal 109 can understand that channel estimation will be performed in the subsequent JT interference scan 832 by combining the "frame control" with other information in this frame.

[0186] Furthermore, compared to the first embodiment described above, the "JT interference scan information" has been added with "Feedback execution time" (Feedback Timing). This "Feedback execution time" includes information indicating the time to execute channel feedback 834 to wireless terminal 109. This "Feedback execution time" may include information indicating that execution will be performed after a certain time has elapsed after the "JT interference scan information" has ended, or information indicating that execution will be performed after a trigger 817 has been notified from multi-AP.

[0187] [Channel Feedback] FIG. 16 is a diagram showing an example of a frame configuration of the channel feedback 834 in the second embodiment of the present technology.

[0188] This channel feedback 834 frame is used when the wireless terminal 109 notifies the multi-AP of the propagation path information estimated by the JT interference scan 832. This frame is composed of a "frame control", a "channel feedback control element" and a "channel feedback information element", but the components are not limited to these. Also, each element does not necessarily have to be defined independently, and may be defined as one element together with other components.

[0189] "Frame Control" includes information indicating that the present frame is a frame to be notified as channel feedback 834. However, it does not have to be included only in "Frame Control", and may be configured to indicate that the present frame is a frame to be notified as channel feedback 834 by combining with other information in the present frame. For example, it may be configured so that it can be interpreted in combination with the value of any field in the "Channel Feedback Control Element".

[0190] The "Channel Feedback Control element" includes, but is not limited to, information for estimating in advance the length of each field in the following "Channel Feedback Information Element". In addition to the "Element ID", this element includes at least one of the following information: "Frequency Band" and "Feedback Control".

[0191] "Frequency Band" (BW) includes information indicating the frequency band of the estimated propagation path information. "Feedback Control" includes information indicating the format of the propagation path information included in the following "Channel Feedback Information Element". This "Feedback Control" includes at least one of the subfields "Number of Measurements", "Terminal Antenna Mask", and "Quantization Granularity".

[0192] The "Measurement Number" includes information indicating that the estimated propagation path information includes propagation path information estimated when multi-APs transmit in cooperation, or propagation path information estimated for each access point that constitutes the multi-AP, or both. The "Terminal Antenna Mask" includes information indicating the receiving antenna of the wireless terminal 109 used to estimate the propagation path information. The "Quantization Granularity" includes information indicating how many bits of information each numerical value that constitutes the preceding is represented by.

[0193] Based on the information stored in the "number of measurements," the multi-AP that received the channel feedback 834 may determine whether "CJT channel measurement" or "NCJT channel measurement," or both, are present in the subsequent "channel feedback information element." In addition, when it is indicated that estimated propagation path information is included for each access point that constitutes the multi-AP, information indicating the estimated access point may also be included.

[0194] The "Channel Feedback Information element" in combination with the "Channel Feedback Control element" indicates propagation path information estimated by the JT interference scan 832. Note that the information included in the "Channel Feedback Information element" is not limited to this. In addition to the "Element ID", this element includes at least one of the following information: "CJT channel measurement" and "NCJT channel measurement".

[0195] The "CJT Channel Measurement" includes propagation path estimation information for a reference signal transmitted in cooperation between multi-APs that have performed a JT interference scan 832, and may include, for example, propagation path estimation information for a JT interference scan 832 performed according to Equation 2. The "NCJT Channel Measurement" includes propagation path estimation information for a reference signal transmitted by a multi-AP that has performed a JT interference scan 832 for each access point constituting the multi-AP, and may include, for example, propagation path estimation information for a JT interference scan 832 performed according to Equation 3. The "NCJT Channel Measurement" includes propagation path estimation information for "CSI AP Set #1" to "CSI AP Set #N SET " subfield.

[0196] “CSI AP Set #1” to “CSI AP Set #N” SET " includes propagation path estimation information for any combination of access points constituting a multi-AP and information indicating the combination. Information indicating the combination of access points may not be included. For example, if it is indicated in the "Channel Feedback Information Element" that each "CSI AP Set" includes propagation path estimation information for each access point constituting a multi-AP, information indicating the combination of access points may not be included.

[0197] [Processing Procedure] FIG. 17 is a flowchart showing an example of a processing procedure of a weight determination process according to the second embodiment of the present technology.

[0198] The master AP 101 that has decided to perform the JT interference scan 832 starts calculating the precoding to be used in the JT interference scan 832 .

[0199] Here, it is determined whether valid channel estimation information between the wireless terminal 109 that can be the destination in the cooperative transmission and the multi-AP is held. Specifically, it is determined whether the channel estimation information is not held, or whether the held channel estimation information was acquired a certain time ago or more ago (step S911).

[0200] If it is determined that valid propagation path estimation information is not held (step S911: No), it is determined whether or not to estimate propagation path information (sounding) for the wireless terminal 109 in the JT interference scan 832 (step S912).

[0201] If sounding is to be performed (step S912: Yes), the slave AP 102 is notified by the JT scan sector information 813 that the JT interference scan 832 will be performed using known precoding (step S916).

[0202] On the other hand, if it is determined that sounding is not to be performed in the JT interference scan 832 (step S912: No), it is determined whether to perform the JT interference scan 832 using known precoding (step S913). The subsequent operations are the same as those in the first embodiment described above.

[0203] In this way, according to the second embodiment of the present technology, by transmitting the JT interference scan 832 to the wireless terminal 109 as well, channel estimation can be performed in the wireless terminal 109 in parallel with interference estimation in the OBSS terminal 209.

[0204] <3. Third embodiment> In the above-mentioned first embodiment, it is assumed that the JT interference scan 818 is performed in response to the JT interference scan notification 811 from the multi-AP, but in this third embodiment, it is assumed that the OBSS-AP 203 notifies the multi-AP first. Note that the configurations of the wireless network system and the wireless communication device are the same as those in the above-mentioned first embodiment, so detailed explanations are omitted.

[0205] [Operation] FIG. 18 is a sequence diagram showing an example of operation of the wireless network system in the third embodiment of the present technology.

[0206] The operation of the third embodiment is basically the same as that of the first embodiment described above, except for the following points.

[0207] [JT Interference Scan Request] First, the OBSS-AP 203 issues a JT interference scan request 841 to the multi-AP, requesting the execution of a JT interference scan 818. At this time, the OBSS-AP 203 may notify the request by including information indicating the start time and execution period of the interference measurement requested by the OBSS-AP 203. This JT interference scan request 841 is notified to at least one of the master AP 101 and the slave AP 102 among the multi-APs. The JT interference scan request 841 is an example of a communication unit described in the claims.

[0208] When the JT interference scan request 841 is notified only to the slave AP 102, the slave AP 102 may notify the master AP 101 of information indicating that the JT interference scan request 841 has been notified from the OBSS-AP 203. Also, information that the slave AP 102 and the master AP 101 exchange roles with each other may be notified, and the roles of the slave AP 102 and the master AP 101 may be exchanged.

[0209] For example, if OBSS-AP 203 recognizes the presence of multi-AP and determines that the transmission quality to OBSS terminal 209 is poor, or if OBSS-AP 203 recognizes the presence of multi-AP and the received power of the signal transmitted by the multi-AP is higher than a threshold, OBSS-AP 203 may operate to execute a JT interference scan request 841.

[0210] [JT Interference Scan Notification] When a JT interference scan request 841 is issued from the OBSS-AP 203, the multi-AP issues a JT interference scan notification 842 regarding the start time and execution period for executing interference measurement to the OBSS-AP 203. Note that the information to be notified is not limited to this.

[0211] In this example, the master AP 101 is shown performing the JT interference scan notification 842 to the OBSS-AP 203, but this may also be performed by the slave AP 102 or multi-AP (both the master AP 101 and the slave AP 102) rather than the master AP 101.

[0212] [Frame composition] The configuration of each frame added in the third embodiment will be described in detail below.

[0213] [JT Interference Scan Request] FIG. 19 is a diagram showing an example of a frame configuration of a JT interference scan request 841 in the third embodiment of the present technology.

[0214] This JT interference scan request 841 frame is a frame for the OBSS-AP 203 to request the multi-AP to notify the OBSS-AP 203 of a request to perform interference measurement and a request for the start time and execution period of the interference measurement from the multi-AP to the OBSS-AP 203. This frame is made up of a "frame control" and a "JT interference scan request element", but the components are not limited to these.

[0215] The "frame control" includes information indicating that this frame is a frame notified as a JT interference scan request 841. However, it does not have to be included only in the "frame control", and may be configured to indicate that this frame is a JT interference scan request 841 by combining with other information in this frame. For example, it may be configured so that it can be interpreted in combination with the value of any field in the "JT interference scan request element".

[0216] The "JT Interference Scan Request element" includes information about the start time and execution time of interference measurement requested by the OBSS-AP 203 to the multi-AP. In addition to the "element ID", this element includes at least one of the following fields: "frequency band", "number of terminals", "scan request", "scan start time", and "scan execution period".

[0217] "Frequency Band" (BW) includes information indicating the bandwidth required when the OBSS-AP 203 performs interference measurement on multi-AP. "Number of Terminals" (STA Number) includes information regarding the number of OBSS-APs 203. "Scan Request" includes information indicating that it is a JT interference scan request 841. "Scan Start Time" includes information regarding the start time of execution of the JT interference scan 818 requested by the OBSS-AP 203 to multi-AP. "Scan Duration" includes information regarding the execution duration of the JT interference scan 818 requested by the OBSS-AP 203 to multi-AP.

[0218] [JT Interference Scan Notification] FIG. 20 is a diagram showing an example of a frame configuration of a JT interference scan notification 842 in the third embodiment of the present technology.

[0219] This JT interference scan notification 842 frame is used when a multi-AP to which a JT interference scan request 841 has been issued from the OBSS-AP 203 notifies information related to the JT interference scan 818, such as the start time and execution period of the JT interference scan 818 to be performed later, based on the information notified to the OBSS-AP 203. This frame is made up of a "frame control" and a "JT interference scan notification element", but the components are not limited to these.

[0220] The "frame control" includes information indicating that this frame is a frame to be notified as a JT interference scan notification 842. However, it does not have to be included only in the "frame control", and may be configured to indicate that this frame is a JT interference scan notification 842 by combining with other information in this frame. For example, it may be configured so that it can be interpreted in combination with the value of any field in the "JT interference scan notification element".

[0221] The "JT Interference Scan Announcement element" includes information about the start time and execution time of interference measurement requested by the OBSS-AP 203 to the multi-AP. In addition to the "element ID", this element includes at least one or more fields of "frequency band", "scan start time" and "scan execution period", but the components are not limited to these.

[0222] The "Frequency Band" (BW) includes information indicating the bandwidth when the multi-AP performs interference measurement with the OBSS-AP 203. The "Scan Start Time" includes information regarding the time when the multi-AP starts to perform the JT interference scan 818. The "Scan Duration" includes information regarding the duration when the multi-AP performs the JT interference scan 818.

[0223] In this way, according to the third embodiment of the present technology, the JT interference scan 818 can be performed in response to the JT interference scan request 841 from the OBSS-AP 203 .

[0224] The above-mentioned embodiment shows an example for realizing the present technology, and the matters in the embodiment and the matters specified in the claims correspond to each other. Similarly, the matters specified in the claims and the matters in the embodiment of the present technology having the same name correspond to each other. However, the present technology is not limited to the embodiment, and can be realized by applying various modifications to the embodiment within the scope of the gist of the technology.

[0225] The processing procedures described in the above embodiments may be regarded as a method having a series of these procedures, or as a program for causing a computer to execute the series of procedures or a recording medium for storing the program. For example, a CD (Compact Disc), an MD (MiniDisc), a DVD (Digital Versatile Disc), a memory card, a Blu-ray (registered trademark) Disc, etc. may be used as this recording medium.

[0226] It should be noted that the effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0227] The present technology can also be configured as follows. (1) A radio control unit that generates and transmits a reference signal for estimating interference caused to a radio terminal connected to another radio base station when performing cooperative transmission with a cooperative radio base station, and determines settings for the cooperative transmission according to an estimation result of the interference based on the reference signal; a communication unit that transmits the reference signal to the other radio base station or the radio terminal and notifies the cooperative radio base station of a setting related to the cooperative transmission; A wireless base station comprising: (2) The radio control unit inquires of the other radio base station whether or not measurement for the interference estimation is possible prior to transmitting the reference signal. The wireless base station according to (1). (3) the radio control unit generates information regarding precoding of the reference signal; The communication unit transmits information regarding precoding of the reference signal to the cooperative radio base station. The wireless base station according to (1) or (2). (4) The information regarding the precoding includes information regarding a frequency using the reference signal. The wireless base station according to (3). (5) The information regarding the precoding includes information regarding a codebook predetermined between the cooperative radio base station and the cooperative radio base station. The wireless base station according to (3) or (4). (6) The information regarding the preceding includes information regarding a weighting factor to be calculated for the reference signal. The wireless base station according to any one of (3) to (5). (7) The information regarding the precoding includes information regarding a time offset for the cooperative radio base station at the time of transmitting the reference signal. The radio base station according to any one of (3) to (6). (8) The information about the preceding includes at least one of information indicating the presence or absence of the time offset and information indicating the time offset. The wireless base station according to (7). (9) The radio control unit generates information indicating that a measurement for the interference estimation is performed prior to transmission of the reference signal; The communication unit transmits information indicating that the measurement for the interference estimation is to be performed to the other radio base station. The wireless base station according to any one of (1) to (8). (10) The information indicating that the measurement for the interference estimation is to be performed includes information regarding a time to transmit the reference signal, a period during which the measurement is performed, and a frequency at which the measurement is performed. The wireless base station according to (9). (11) The radio control unit determines cooperative parameters including at least one of a cooperative transmission scheme, a precoding scheme, a coding scheme, and a transmission power in the cooperative transmission based on the estimation result of the interference from the other radio base station. The wireless base station according to any one of (1) to (10). (12) The collaboration parameters are determined based on a predetermined criterion. The wireless base station according to (11). (13) The reference signal includes information for estimating a propagation path between the radio base station and a radio terminal connected to the radio base station, The communication unit transmits the reference signal to the wireless terminal connected to the wireless base station. The wireless base station according to any one of (1) to (12). (14) The cooperative transmission setting notified by the cooperative transmission setting notification unit includes information regarding the number of the cooperative radio base stations. The wireless base station according to any one of (1) to (13). (15) The cooperative transmission setting notified by the communication unit further includes at least one of information on a cooperative transmission method in the cooperative transmission, information on a transmitting antenna used in the cooperative radio base station, information on the wireless terminal that is a destination in the cooperative transmission, and information on precoding of the wireless terminal that is a destination in the cooperative transmission. The radio base station according to (14). (16) The information regarding the precoding of the wireless terminal serving as a destination in the cooperative transmission includes information regarding the number of the wireless terminals serving as the destination, information for identifying the wireless terminal serving as the destination, and information regarding a frequency, an encoding method, a transmission power, and a stream used in the cooperative transmission. The wireless base station according to (15). (17) A radio control unit that acquires, from a radio terminal, information regarding an interference caused by the cooperative transmission to the radio terminal, the interference being estimated using a reference signal provided from any one of a plurality of radio base stations that perform cooperative transmission, and generates overall interference information based on the acquired information regarding the interference; a communication unit that transmits the entire interference information to any one of the plurality of radio base stations that perform the cooperative transmission; A wireless base station comprising: (18) The communication unit requests the plurality of radio base stations performing the cooperative transmission to transmit a reference signal for estimating interference caused by the cooperative transmission to the radio terminal. The wireless base station according to (17). (19) A radio control unit that estimates interference caused by cooperative transmission using a reference signal provided from any one of a plurality of radio base stations that perform cooperative transmission; a communication unit that transmits information about the estimated interference to another radio base station; A wireless terminal comprising: [Explanation of symbols]

[0228] 101 Master Access Point 102 Slave Access Point 108~109 Wireless terminal 203 OBSS Access Points 209 OBSS terminal 300 Wireless communication device 310 Communications Department 311 Radio control unit 312 Data Processing Unit 313 Modulation and demodulation section 314 Signal Processing Unit 315 Channel Estimation Unit 316 Wireless Interface Unit 317 Amplifier section 319 Antenna 321 Control Unit 322 Power supply section 811 JT Interference Scan Notification 812 JT interference scan response 813 JT Scan Sector Information 815 JT Interference Scan Trigger 816 OBSS-JT Interference Scan Notification 817 Trigger 818 JT Interference Scan 821 Interference Amount Estimation 822 JT Interference Report Trigger 823 JT Interference Report 824 JT Interference Feedback 826 Cooperative Transmission Setting Decision 827 Cooperative Transmission Setting Notification 828 Cooperative Transmission 831 JT Interference Scan Trigger 832 JT Interference Scan 834 Channel Feedback 841 JT Interference Scan Request 842 JT Interference Scan Notification

Claims

1. a radio control unit that controls a communication unit to transmit a reference signal for estimating interference caused to a predetermined number of radio terminals connected to another radio base station when performing cooperative transmission with a cooperative radio base station to the other radio base station or the radio terminal, determines a setting related to the cooperative transmission according to a result of estimating the interference based on the reference signal, and controls the communication unit to notify the cooperative radio base station of the setting related to the cooperative transmission, the other radio base station acquires information regarding the interference from each of the radio terminals, and generates and transmits interference information indicating estimated amounts of interference for all of the predetermined number of radio terminals based on the acquired information regarding the interference; The wireless control unit controls the communication unit to receive the interference information as the estimation result. Radio control device.

2. The radio control unit inquires of the other radio base station whether or not measurement for estimating the interference is possible prior to transmitting the reference signal. The wireless control device according to claim 1.

3. The radio control unit generates information regarding precoding of the reference signal; The communication unit transmits information regarding precoding of the reference signal to the cooperative radio base station. The wireless control device according to claim 1.

4. The information regarding the precoding includes information regarding a frequency using the reference signal. The wireless control device according to claim 3.

5. The information regarding the precoding includes information regarding a codebook predetermined between the cooperative radio base station and the cooperative radio base station. The wireless control device according to claim 3.

6. The information regarding the precoding includes information regarding a weighting factor to be calculated on the reference signal. The wireless control device according to claim 3.

7. The information regarding the precoding includes information regarding a time offset for the cooperative radio base station at the time of transmitting the reference signal. The wireless control device according to claim 3.

8. The information about the precoding includes at least one of information indicating the presence or absence of the time offset and information indicating the time offset. The wireless control device according to claim 7.

9. The radio control unit generates information indicating that a measurement for estimating the interference is performed prior to transmission of the reference signal; The communication unit transmits information indicating that a measurement for estimating the interference is to be performed to the other radio base station. The wireless control device according to claim 1.

10. The information indicating that the measurement for estimating the interference is to be performed includes information regarding a time to transmit the reference signal, a period during which the measurement is performed, and a frequency at which the measurement is performed. The wireless control device according to claim 9.

11. The radio control unit determines cooperative parameters including at least one of a cooperative transmission scheme, a precoding scheme, a coding scheme, and a transmission power in the cooperative transmission based on the estimation result of the interference from the other radio base station. The wireless control device according to claim 1.

12. The collaboration parameters are determined based on a predetermined criterion. The wireless control device according to claim 11.

13. the reference signal includes information for estimating a propagation path between at least one of the radio base station and the cooperative radio base station and a radio terminal connected to the at least one of the radio base station and the cooperative radio base station; The communication unit transmits the reference signal to the wireless terminal connected to the wireless base station. The wireless control device according to claim 1.

14. The setting regarding the cooperative transmission notified by the communication unit includes information regarding the number of the cooperative radio base stations. The wireless control device according to claim 1.

15. The setting regarding the cooperative transmission notified by the communication unit further includes at least one of information regarding a cooperative transmission method in the cooperative transmission, information regarding a transmitting antenna used in the cooperative radio base station, information regarding the wireless terminal that is a destination in the cooperative transmission, and information regarding precoding of the wireless terminal that is a destination in the cooperative transmission. The wireless control device according to claim 14.

16. The information regarding the precoding of the wireless terminal that is the destination in the cooperative transmission includes information regarding the number of the wireless terminals that are the destination, information for identifying the wireless terminal that is the destination, and information regarding a frequency, an encoding method, a transmission power, and a stream that are used in the cooperative transmission.

16. The wireless control device according to claim 15.

17. The present invention controls a communication unit to obtain, from each of a plurality of wireless terminals, information regarding interference to a predetermined number of wireless terminals due to cooperative transmission, estimated using a reference signal supplied from any one of a plurality of wireless base stations performing cooperative transmission, generate interference information indicating estimated amounts of interference for all of the predetermined number of wireless terminals based on the obtained information regarding interference, and transmit the interference information to any one of the plurality of wireless base stations performing cooperative transmission. A wireless control device comprising:

18. The communication unit requests the plurality of radio base stations performing the cooperative transmission to transmit a reference signal for estimating interference caused by the cooperative transmission to the radio terminal.

18. The wireless control device of claim 17.

19. a predetermined number of wireless terminals that estimate interference caused by cooperative transmission using a reference signal supplied from any one of a plurality of wireless base stations that perform cooperative transmission, and transmit information about the estimated interference to another wireless base station; Wireless base station and A communication system comprising: The wireless base station acquires information about the interference from each of the wireless terminals, generates interference information indicating estimated interference amounts of all of the predetermined number of wireless terminals based on the acquired information about the interference, and transmits the interference information to any one of the multiple wireless base stations that perform the cooperative transmission. Communication systems.

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