Wireless communication device, wireless communication method, and wireless communication system

Abstract

To enable reduction of data transmission delay.SOLUTION: A wireless communication device transmits a first data frame including a first data signal to a wireless terminal, and controls transmission of suppression request signals requesting other wireless communication devices to suppress interference with the wireless terminal before transmitting the first data frame. The present technology can be applied to, for example, a wireless communication system including two wireless communication devices operating as AP1 and AP2, respectively, and four wireless communication terminals operating as STA1 to STA4, respectively.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present technology relates to a wireless communication device and a wireless communication terminal, and more particularly to a wireless communication device and a wireless communication terminal that are capable of reducing data transmission delays. [Background technology]

[0002] In recent years, various use cases using wireless communications have been considered, such as real-time mobile gaming using technologies such as VR (Virtual Reality) and AR (Augmented Reality), process management in factories, robot operation, drone control, etc. To realize these use cases, "low-latency transmission technology" that transmits important information such as control information within a certain delay time is considered important.

[0003] Among low-latency transmission technologies in an environment with multiple wireless LAN base stations (hereinafter referred to as APs), a technology called Coordinate Beamforming (CBF) is being studied as a method for using frequency resources most efficiently. CBF is a technology in which, while an AP is transmitting data to a wireless LAN device (hereinafter referred to as STA) under its control in the same cell, other APs cooperate to reduce the interference power they cause to the STA. CBF enables multiple APs to simultaneously transmit using the same frequency resource, while the STA receives the transmitted signal and acquires the transmitted data.

[0004] A commonly known method for reducing interference is to use MIMO (Multiple Input Multiple Output) technology to spatially generate NULL for wireless LAN (Local Area Network) devices that are not under the control of the device itself (see Patent Document 1). Generally, generating NULL spatially means reducing interference to zero spatially.

[0005] For example, from the perspective of an AP that holds data packets that require low-latency transmission technology (hereinafter referred to as RTA (Real Time Application) packets), it is desirable for other APs to always suppress interference with the STAs to which it transmits RTA packets. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2010 / 125635 Summary of the Invention [Problem to be solved by the invention]

[0007] However, for other APs, suppressing interference with STAs that are not under their control means sacrificing their own communication quality. For example, when using MIMO to generate NULLs, some of the AP's own transmit antennas must be used to generate NULLs for STAs that are not under its control, which reduces the number of transmit antennas that can be used for its own communication and leads to a decrease in data rate.

[0008] Therefore, it is desirable for an AP that performs interference suppression to limit interference suppression to STAs that are not under its control to situations where it is truly necessary.

[0009] The present technology has been made in view of such circumstances, and is intended to reduce data transmission delays. [Means for solving the problem]

[0010] A wireless communication device according to a first aspect of the present technology includes a wireless communication unit that transmits a first data frame including a first data signal to a wireless terminal, and a communication control unit that controls, before transmitting the first data frame, the transmission of a suppression request signal that requests other wireless communication devices to suppress interference with the wireless terminal.

[0011] A wireless communication device according to a second aspect of the present technology includes a wireless communication unit that receives a suppression request signal requesting interference suppression for a first wireless terminal, the suppression request signal being transmitted from another wireless communication device that transmits a first data frame including a first data signal to the first wireless terminal before transmitting the first data frame, and a communication control unit that determines whether to perform the interference suppression based on the suppression request signal.

[0012] A wireless communication terminal according to a third aspect of the present technology includes a wireless communication unit that transmits a data frame including a data signal to a first wireless communication device, and a communication control unit that controls the transmission of a suppression request signal that requests interference suppression from a second wireless communication device before transmitting the data frame.

[0013] A wireless communication device according to a fourth aspect of the present technology includes: a wireless communication unit that receives an interference request signal requesting interference suppression from a first wireless communication terminal that transmits a first data frame including a first data signal; and a communication control unit that, when transmitting a second data frame different from the first data frame to a second wireless communication terminal, determines, based on the interference request signal, whether or not the first wireless communication terminal will perform the interference suppression on another wireless communication device that transmits the first data frame.

[0014] A wireless communication terminal according to a fifth aspect of the present technology includes a communication unit that receives, from a wireless communication device, a cooperative information sharing signal that shares a request for interference suppression with another wireless communication terminal that transmits a first data frame including a first data signal, and a communication control unit that, when transmitting a second data frame different from the first data frame to the wireless communication device, determines, based on the cooperative information sharing signal, whether or not the other wireless communication terminal will perform the interference suppression with the other wireless communication device that transmits the first data frame.

[0015] In a first aspect of the present technology, a first data frame including a first data signal is transmitted to a wireless terminal, and before the transmission of the first data frame, transmission of a suppression request signal requesting another wireless communication device to suppress interference with the wireless terminal is controlled.

[0016] In a second aspect of the present technology, a suppression request signal is received from another wireless communication device that transmits a first data frame including a first data signal to a first wireless terminal before transmitting the first data frame, the suppression request signal requesting interference suppression for the first wireless terminal, and whether or not to perform the interference suppression is determined based on the suppression request signal.

[0017] In a third aspect of the present technology, a data frame including a data signal is transmitted to a first wireless communication device, and before the transmission of the data frame, transmission of a suppression request signal requesting interference suppression from a second wireless communication device is controlled.

[0018] In a fourth aspect of the present technology, an interference request signal requesting interference suppression is received from a first wireless communication terminal that transmits a first data frame including a first data signal, and when transmitting a second data frame different from the first data frame to a second wireless communication terminal, it is determined based on the interference request signal whether the first wireless communication terminal will perform the interference suppression on another wireless communication device that transmits the first data frame.

[0019] In a fifth aspect of the present technology, a cooperative information sharing signal is received from a wireless communication device, the cooperative information sharing signal sharing a request for interference suppression to another wireless communication terminal that transmits a first data frame including a first data signal. Then, when a second data frame different from the first data frame is transmitted to the wireless communication device, it is determined based on the cooperative information sharing signal whether the other wireless communication terminal will perform the interference suppression to the other wireless communication device that transmits the first data frame. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a diagram illustrating a configuration example of a wireless communication system according to the present technology. [Figure 2] FIG. 3 is a diagram illustrating a sequence for explaining the overall processing of the wireless communication system according to the first embodiment. [Figure 3] FIG. 10 is a diagram illustrating an example of the configuration of a Coordination Request Frame. [Figure 4] FIG. 10 is a diagram illustrating an example of the configuration of a Coordination Response Frame. [Figure 5] FIG. 10 is a diagram illustrating an example of the configuration of a preamble included in a data frame. [Figure 6] FIG. 10 is a diagram illustrating an example of the configuration of a Coordination End Frame. [Figure 7] FIG. 2 is a diagram illustrating a first example of a data sequence in a Data Tx Phase according to the first embodiment. [Figure 8] FIG. 10 is a diagram illustrating a second example of a data sequence in the Data Tx Phase in the first embodiment. [Figure 9] FIG. 10 is a diagram illustrating a third example of a data sequence in the Data Tx Phase in the first embodiment. [Figure 10] FIG. 10 is a diagram illustrating a fourth example of a data sequence in the Data Tx Phase in the first embodiment. [Figure 11] FIG. 10 is a diagram illustrating a fifth example of a data sequence in the Data Tx Phase in the first embodiment. [Figure 12] FIG. 1 is a block diagram illustrating an example of the configuration of a wireless communication device. [Figure 13] 10 is a flowchart illustrating processing of the AP 1 according to the first embodiment. [Figure 14] 10 is a flowchart illustrating processing of the AP2 in the first embodiment. [Figure 15] FIG. 10 is a diagram illustrating a sequence for explaining the overall processing of the wireless communication system according to the second embodiment. [Figure 16] FIG. 10 is a diagram illustrating a first example of a data sequence in a Data Tx Phase according to the second embodiment. [Figure 17] FIG. 10 is a diagram illustrating a second example of a data sequence in the Data Tx Phase in the second embodiment. [Figure 18] FIG. 11 is a diagram illustrating a third example of a data sequence in the Data Tx Phase in the second embodiment. [Figure 19] FIG. 11 is a diagram illustrating a fourth example of a data sequence in the Data Tx Phase in the second embodiment. [Figure 20] 10 is a flowchart illustrating processing of AP2 in a second embodiment. [Figure 21] 10 is a flowchart illustrating processing of the AP 1 according to the second embodiment. [Figure 22] FIG. 11 is a diagram illustrating a sequence for explaining the overall processing of the wireless communication system according to the third embodiment. [Figure 23] FIG. 10 is a diagram illustrating an example of the configuration of a Coordination Info Sharing Frame. [Figure 24] FIG. 1 is a block diagram illustrating an example of the configuration of a computer. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present technology will be described in the following order. 1. System Configuration 2. First embodiment (example in which AP1 acquires transmission right first) 3. Second embodiment (example in which AP2 acquires transmission right first) 4. Third embodiment (example of transmission from STA to AP) 5.Other

[0022] <1. System configuration> <Configuration example of wireless communication system> FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system according to an embodiment of the present technology.

[0023] In Figure 1, solid arrows indicate that devices are connected to each other, and dashed arrows indicate that power is exchanged between devices. AP (Access Point) represents a base station for a wireless LAN (Local Area Network). STA (Station) represents a wireless communication terminal.

[0024] 1 is configured by AP1 and AP2 being connected by wired communication or wireless communication. Wireless communication device 11-1 and wireless communication device 11-2 are devices that operate as AP1 and AP2, respectively. In addition, the wireless communication system is configured by STA1 and STA2 being connected to AP1 by wireless communication, and STA3 and STA4 being connected to AP2 by wireless communication. Wireless communication terminals 12-1 to 12-4 are devices that operate as STA1 to STA4, respectively.

[0025] STA1 and STA2, which are connected to AP1 via wireless communication, belong to the same cell (BSS) as AP1 and are referred to as STAs under AP1. STA3 and STA4, which are connected to AP2 via wireless communication, belong to the same cell (BSS) as AP1 and are referred to as STAs under AP2.

[0026] Since STA2 and STA3 are close to the AP other than the one they are connected to, it is expected that they will receive stronger received power from the AP other than the one they are connected to than STA1 and STA4, which are farther away from the AP other than the one they are connected to.

[0027] The system configuration in question is not limited to the example shown in Figure 1, and any configuration is possible as long as there are multiple APs with established connections and STAs are connected to each AP as surrounding terminals.

[0028] This technology is characterized in that when RTA (Real Time Application) packets are transmitted among multiple APs, the AP controls the transmission of suppression request signals, which are signals that request other APs to suppress interference with the STA to which the RTA packets are transmitted.

[0029] RTA packets are data packets that require at least one of low delay and high reliability.

[0030] Hereinafter, an example will be described in which AP1 requests AP2 to cooperate to suppress interference, on the assumption that AP1 transmits an RTA packet to STA2.

[0031] In this specification, the smallest unit of data transmitted by an AP is called a "packet," and data formed by connecting multiple packets and adding a MAC header and preamble is called a "data frame." The transmission of a data frame is called "data transmission." The names are not limited to these.

[0032] In addition, in this specification, interference suppression is referred to as "generating a NULL," which does not only refer to making spatial interference zero, but also refers to operations that reduce interference power by lowering the transmission power value or applying beamforming (hereinafter referred to as beam control).

[0033] <2. First embodiment (example in which AP1 acquires transmission right first)> First, as a first embodiment, an example in which AP1 acquires the transmission right first will be described.

[0034] <Example of overall processing sequence> FIG. 2 is a diagram showing a sequence for explaining the overall processing of the wireless communication system in the first embodiment.

[0035] 2 is performed by AP1, AP2, and STAs, which represent STA1 to STA4.

[0036] Processing in a wireless communication system is divided into five phases: Multi-AP Group Set Phase, Sounding Phase, Coordination Set Phase, Data Tx Phase, and Coordination End Phase. Note that in Figure 2, "Coordination" is abbreviated to "Coord." as appropriate. This also applies to the following figures.

[0037] Steps S1 and S2 are the Multi-AP Group Set Phase in which information is exchanged between APs. In step S1, AP1 performs Multi-AP Group Set with AP2. In step S2, AP2 performs Multi-AP Group Set with AP1.

[0038] In the Multi-AP Group Set Phase, AP1 and AP2 perform Multi-AP Group Set with each other, exchanging information such as whether the APs are capable of cooperating, the number of transmitting antennas, capability information indicating the capabilities of the cooperation method, information on the maximum number of STAs that can simultaneously generate NULL, and the identifiers of the subordinate STAs (AID: Association ID).

[0039] Steps S3 to S6 are the Sounding Phase, in which information is exchanged between the AP and the STAs. In step S3, AP1 transmits to the STAs an NDP (NULL DATA PACKET) Frame, which is a reference signal of a known pattern, an NDP-A (Announcement) Frame, which is a signal announcing the NDP, and the like. In step S4, the STAs that have received the NDP Frame or NDP-A Frame transmit a Feedback Frame, which is a feedback signal, to AP1. In step S5, AP2 transmits the NDP-A Frame, NDP Frame, and the like to the STAs. In step S6, the STAs transmit a Feedback Frame to AP2.

[0040] That is, in the sounding phase, AP1 and AP2 transmit NDP-A and NDP frames, receive feedback frames from STAs that receive the NDP-A and NDP frames, and exchange information between the AP and STAs. This allows channel information between the AP and STAs to be estimated, and obtains transmission weight information that the AP should apply.

[0041] In the sounding phase, the frames used in IEEE802.11ax (NDP-A, ANP, BFRP (Beam Forming Report Protocol) Trigger, Feedback) and their sequences are basically assumed. The BFRP Trigger Frame is a trigger signal for announcing beam control. However, the difference between this technology and IEEE802.11ax is that AP1 and AP2 also receive feedback from STAs belonging to other cells and obtain information on interference power.

[0042] Steps S7 and S8 are the Coordination Set Phase, in which AP1 and AP2 perform coordinated operations, that is, perform setup when starting interference suppression with STAs in other cells.

[0043] For example, when a certain STA (STA2 in the case of FIG. 2) starts an application that requires an RTA packet, in step S7, AP1 transmits a Coordination Request Frame, which is a suppression request signal requesting interference suppression to STA2, to AP2. Having received the Coordination Request Frame, AP2 determines whether to start interference suppression to STA2 based on the information in the frame, and in step S8, based on the result of that determination, returns a Coordination Response Frame, which is a response signal to the Coordination Request Frame, to AP1.

[0044] Steps S9 to S11 are the Data Tx Phase, in which AP1 and AP2 transmit data to the STAs under their control.

[0045] For example, in step S9, AP1 performs data transmission to STA2. In step S10, AP2 performs data transmission to STA3. In step S11, STA2 transmits an Ack to AP1, and STA3 transmits an Ack to AP2.

[0046] Although details will be described later, one Data Tx Phase is assumed to operate within the period during which one transmission right, a TXOP (Transmit Opportunity), is assigned (hereinafter referred to as within a TXOP). Data Transmission may be performed multiple times within the same TXOP.

[0047] Steps S12 and S13 are the Coordination End Phase. In the Coordination End Phase, a coordination operation between AP1 and AP2, that is, a process to terminate interference suppression to STAs of other cells, is performed.

[0048] That is, in step S12, AP1 transmits a Coordination End Frame, which is a signal to terminate interference suppression, to AP2. In step S13, AP2 transmits an Ack to AP1. Note that the transmission of Ack is optional.

[0049] As the timing for AP1 to transmit the Coordination End Frame, for example, the case where the application that STA2 requires the RTA packet ends, or the case where AP1 completes the transmission of all RTA packets can be considered.

[0050] Note that the above five Phases are an example, and the configuration example is not limited to this. For example, the Coordination Set Phase may be included in the Data Tx Phase (that is, performed every time TXOP is acquired), or may be included in the Sounding Phase.

[0051] The Coordination End Phase may be included in the Data Tx Phase. In this case, the Coordination End Phase is performed immediately before the end of TXOP. The Data Tx Phase may be performed multiple times between the Coordination Setup Phase and the Coordination End Phase.

[0052] <Configuration Example of Coordination Request Frame> FIG. 3 is a diagram showing a configuration example of the Coordination Request Frame.

[0053] The Coordination Request Frame consists of a MAC header, a Frame Body, and a Frame Check Sequence (FCS). Note that hatching in Figure 3 indicates fields that contain information that is characteristic of this technology. This also applies to the following figures.

[0054] The MAC header is made up of the following fields: Frame Control, Duration, Address 1 to Address 3, Sequence Control, and HT Control.

[0055] The Frame Body consists of the following fields: Category, Multi-AP Action, Dialog Token, and Coordination Request Element.

[0056] In the Category field, a value is set that indicates that this frame is an Action Frame for Multi-AP.

[0057] The Multi-AP Action field is set to a value indicating that this frame is a Coordination Request Frame.

[0058] In the Dialog Token field, when multiple Action requests occur simultaneously, the same value is stored in this Request and the response signal to this Request in order to identify which is the response signal to this Request.

[0059] The Coordination Request Element field contains information about the STA for which interference is to be suppressed. Note that this Element may contain information about only one STA or information about multiple STAs. Furthermore, multiple Coordination Request Elements may be included in this Frame.

[0060] The Coordination Request Element field consists of the following fields: Element ID, Length, Coordination Duration, Coordination STA ID, Allowable Interference Level, Precoded Preamble Flag, and RTA Packet Info.

[0061] The Element ID field contains identification information indicating that this frame is a Coordination Request Frame.

[0062] The Length field contains information about the length of this frame.

[0063] The Coordination Duration field contains information about the time for which interference suppression is requested from other APs (for example, period information or start / end times (timing)). In other words, the time for which interference suppression is requested from other APs is also the time related to the transmission of RTA data. A value such as "0" may be set in this field, so that no specific time does not need to be set. The limit value of this Duration may also be specified in the standard.

[0064] The Coordination STA ID field is set with identification information (for example, AID) of the STA that is the target of interference suppression. The identification information uses the identifier exchanged in the Multi-AP Group Set Phase.

[0065] The Allowable Interference Level field contains information about the allowable interference power, which is the interference power that can be tolerated by the STA indicated by the Coordination STA ID field. The allowable interference power information is expressed as a binary integer in dBm units. AP2 determines whether to implement interference suppression and the method based on the value of this field.

[0066] In the Precoded Preamble Flag field, if AP2 performs interference suppression on STAs of other cells by beam control using MIMO (Multi Input Multi Output), flag information indicating whether to request the start of beam control from the Preamble, which is the beginning of the frame, is set. If it is required to start beam control from the Preamble, "1" is set. If the Preamble may be radiated omnidirectionally and beam control may be performed after the Preamble, "0" is set.

[0067] In the RTA Packet Info field, information about the RTA packet that AP1 wants to transmit (for example, Interval, Length, MCS (Modulation Coding Scheme), etc.) is set. This field may be omitted depending on the situation.

[0068] Note that in FIG. 3, the Coordination Request Frame is configured as part of the Action Frame defined in IEEE802.11, but the frame configuration example is not limited to the example in FIG. 3. For example, it may be configured as part of a Management Frame or a Control Frame including a Coordination Request Element or a field equivalent to the information specified by this Element.

[0069] <Configuration Example of Coordination Response Frame> FIG. 4 is a diagram showing a configuration example of the Coordination Response Frame.

[0070] The Coordination Response Frame is composed of a MAC header, a Frame Body, and an FCS.

[0071] The Frame Body consists of the following fields: Category, Multi-AP Action, Dialog Token, Coordination Response Element, and Coordination Request Element.

[0072] In the Category field, a value is set that indicates that this frame is an Action Frame for Multi-AP.

[0073] The Multi-AP Action field is set to a value indicating that this frame is a Coordination Response Frame.

[0074] The Dialog Token field is set to the same value as the Dialog Token in the Coordination Request Frame that is responded to with this frame.

[0075] The Coordination Response Element field contains information indicating a response to the received Coordination Request Frame.

[0076] The Coordination Response Element field includes the following fields: Element ID, Length, Result flag, and Reason Code.

[0077] The Element ID field contains identification information indicating that this frame is a Coordination Response Frame.

[0078] The Length field contains information about the length of this frame.

[0079] The Result flag field is set to "1" if the request for interference suppression is accepted, and to "0" if the request is rejected.

[0080] If the Result flag field is set to "0", a value indicating the reason for rejecting the request is set in the Reason Code field. The table linking the value set in the field with the reason is standardized by IEEE802.11. Also, if the Result flag field is set to "1", this field is set to "0 (Successful)".

[0081] If a Coordination Request Element in a Coordination Request Frame requests interference suppression for multiple STAs, the Frame may contain multiple Coordination Response Elements. Alternatively, the same Element may contain as many Reason Flags / Reason Codes as the number of requested STAs.

[0082] If AP2 also has a STA requesting interference suppression, AP2 may add the above-mentioned Coordination Request Element to this frame and transmit it. In this case, AP1 must return a response signal including a Coordination Response Element to AP2.

[0083] In Fig. 4, the Coordination Response Frame is configured as part of the Action Frame defined in IEEE802.11, but the frame configuration example is not limited to the example in Fig. 4. For example, it may be configured as part of a Management Frame or Control Frame that includes a field equivalent to the Coordination Response Element or the information specified in this Element.

[0084] <Example of preamble configuration included in data frame> FIG. 5 is a diagram illustrating an example of the configuration of a preamble included in a data frame transmitted by AP1 / AP2.

[0085] The preamble included in the data frame consists of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG-A, EHT-STF, and EHT-LTF fields.

[0086] 5, the fields of EHT-SIG-A include at least the following fields: Receiver STA ID, RTA Info, Nulling Flag, and Coordination Request Info. Note that this information is not limited to EHT-SIG-A, and may be included anywhere in the preamble. Alternatively, equivalent information may be included in the Control field in the MAC header.

[0087] The Receiver STA ID field is set with the identification information of the destination STA. The identifier exchanged in the Multi-AP Group Set Phase is used as the identification information.

[0088] Information about the RTA packet is set in the RTA Info field. RTA Info includes subfields such as a flag (RTA flag) indicating whether or not an RTA packet is included in the data transmission of AP1, the time to start transmitting the RTA packet (RTA Tx Start Time), the transmission duration of the RTA packet (RTA Tx Duration), and an Ack Policy related to the RTA packet.

[0089] Note that these Start time and Duration are information related to the transmission time of the RTA packet. The information related to the transmission time of the RTA packet is not limited to Start time and Duration, and for example, the time at which the transmission of the RTA packet ends (RTA Tx End Time) may be set, or instead of time information, the number of the packet that is the RTA packet among the packets to be aggregated (concatenated) may be specified.

[0090] Also, if the Ack Policy of the RTA packet is uniquely defined by a standard, the Ack Policy subfield does not need to be notified.

[0091] The Nulling Flag field contains a flag indicating whether the AP transmitting this data is generating Nulls for STAs in other cells. If the Nulling Flag is "1", this means that the AP transmits data to STAs requested by other APs in the Coordination Set Phase with Nulls generated.

[0092] In the Coordination Request Info, some of the information included in the Coordination Request Frame described above with reference to FIG. 3 (for example, Precoded Preamble Flag, Allowable Interference Level, etc.) is set.

[0093] Normally, the Coordination Request Info is set to the same value as that notified in the Coordination Request Frame, so the Coordination Request Info does not need to be included in the Preamble. However, for example, if pre-negotiation such as the Coordination Request Frame is not performed, or if the information notified in the Coordination Request Frame changes frequently, the same information may be notified in the Preamble.

[0094] <Configuration Example of Coordination End Frame> FIG. 6 is a diagram showing a configuration example of Coordination End Frame.

[0095] Coordination End Frame is composed of a MAC header, a Frame Body, and an FCS.

[0096] The Frame Body is composed of each field of Category, Multi-AP Action, and Dialog Token.

[0097] A value indicating that this frame is an Action Frame for Multi-AP is set in the Category field.

[0098] A value indicating that this frame is a Coordination End Frame is set in the Multi-AP Action field.

[0099] The same value as the Dialog Token of the Coordination Request Frame processed in this frame is set in the Dialog Token field.

[0100] Note that in FIG. 6, although the Coordination End Frame is configured as part of the Action Frame defined in IEEE802.11, the configuration example of the frame is not limited to the example in FIG. 6.

[0101] <The First Example of Data Sequence> FIG. 7 is a diagram showing the first example of the data sequence in the Data Tx Phase in the first embodiment.

[0102] FIG. 7 shows an example in which AP1 transmits a data signal including an RTA packet to STA2, and AP2 generates a Null for STA2 and transmits a data signal to STA3.

[0103] 7, Rx represents the reception of a data frame transmitted from another AP or STA. This also applies to the following figures.

[0104] AP1 acquires a TXOP by Back Off or the like, and starts transmitting a data frame including a data signal of an RTA packet to STA2 at time t1.

[0105] After receiving the preamble from the data frame transmitted from AP1, AP2 acquires information about AP1 from the received preamble at time t2. The information about AP1 includes the fact that AP1 is transmitting data to STA2 for which AP1 requested interference suppression in the Coordination Set Phase, that the data signal contains RTA packet data, and the transmission start time and transmission period of the RTA packet. That is, Fig. 7 shows an example in which a precoded preamble is not requested for AP2. As described above, the precoded preamble indicates interference suppression from the preamble.

[0106] At time t3, when a time of SIFS (Short Interframe Space)+BO (Back Off) has elapsed since time t2, AP2 starts transmitting data to STA3 based on the acquired information about AP1. At time t4, after completing transmission of the preamble of the data frame, AP2 uses, for example, transmission power control to generate null for STA2, and starts transmitting data after the preamble to STA3.

[0107] At time t5, AP1 and AP2 finish transmitting data.

[0108] At time t6, STA2 transmits Ack, which is a data response confirmation signal, to AP1, and STA3 transmits Ack to AP2.

[0109] To avoid Ack collisions, AP2 must set its data transmission period to coincide with the end time (timing) of AP1's data transmission. The end time of AP1's data transmission can be confirmed from the duration information included in the preamble or MAC header. If there is insufficient data to transmit, AP2 must align its data transmission end time with AP1's by setting padding bits, for example.

[0110] <Second example of data sequence> FIG. 8 is a diagram showing a second example of a data sequence in the Data Tx Phase in the first embodiment.

[0111] FIG. 8 shows an example in which AP1 also generates Null for STA3, just as AP2 in FIG. 7 generates Null for STA2.

[0112] For example, whether AP1 generates Null is determined by whether a Coordination Request Element is included in the Coordination Response Frame transmitted from AP2 during the Coordination Set Phase. In this case, AP1 sets the Nulling Flag field in the Preamble / EHT-SIG-A to "1" and transmits data.

[0113] AP1 acquires the TXOP, and at time t11, AP1 starts transmitting a data frame including a data signal of an RTA packet to STA2. At time t12 after completing transmission of the preamble of the data frame, AP1 generates a null for STA3 and starts transmitting data after the preamble to STA2.

[0114] After receiving the preamble transmitted from AP1, AP2 acquires information about AP1 from the received preamble at time t12.

[0115] At time t13, when SIFS+BO has elapsed since time t12, AP2 starts transmitting data to STA3 based on the acquired information about AP1. At time t14, after completing transmission of the preamble of the data frame, AP2 generates a null for STA2 and starts transmitting data after the preamble to STA3.

[0116] At time t15, AP1 and AP2 finish data transmission.

[0117] At time t16, STA2 transmits an Ack to AP1, and STA3 transmits an Ack to AP2.

[0118] <Third example of data sequence> FIG. 9 is a diagram illustrating a third example of a data sequence in the Data Tx Phase in the first embodiment.

[0119] In Figure 9, an example is shown in which AP1 transmits a data signal that does not include an RTA packet and a data signal that includes an RTA packet, and AP2 generates a null for STA2 by beam control from the data transmission after the preamble.

[0120] AP1 acquires the TXOP and starts transmitting a data frame to STA2 at time t21. At time t22, after completing transmission of the preamble, AP1 starts transmitting data after the preamble of the data frame to STA2. At time t22, AP1 starts transmitting data that does not include an RTA packet, and at time t25 starts transmitting data that includes an RTA packet.

[0121] After receiving the preamble from the data frame transmitted from AP1, AP2 acquires information about AP1 from the received preamble at time t22.

[0122] 9, AP2 radiates preambles in all directions, so there is a risk that only the preamble transmitted by AP2 will act as a strong interfering signal to STA2, causing a collision. Therefore, AP2 checks the timing (time t25) of the RTA packet transmission from the RTA Info field of the Preamble / EHT-SIG-A transmitted from AP1.

[0123] If AP2 determines that AP1 is not transmitting an RTA packet while transmitting its own preamble, AP2 transmits a preamble in all directions at time t23, which is SIFS+BO after time t22. At time t24, AP2 uses beam control to generate nulls for STA2 from the data transmission after the preamble.

[0124] As a result, at time t25 when data transmission including an RTA packet starts, beam control is performed to generate null for STA2.

[0125] At time t26, AP1 and AP2 finish data transmission.

[0126] At time t27, STA2 transmits an Ack to AP1, and STA3 transmits an Ack to AP2.

[0127] <Fourth example of data sequence> FIG. 10 is a diagram illustrating a fourth example of a data sequence in the Data Tx Phase in the first embodiment.

[0128] 10 shows an example in which AP2 uses a method (precoded preamble) in which AP2 generates null from a preamble for STA2. In this case, unlike in FIGS. 7 to 9, AP2 can suppress interference from the preamble to STA2.

[0129] However, on the other hand, applying beam control from the preamble raises the concern that hidden terminals that cannot detect signals from AP2 may occur.

[0130] Therefore, when AP1 acquires a TXOP and requests a Precoded Preamble from AP2, it transmits a Multi-User (MU)-RTS (Request To Send) request signal at time t31. The MU-RTS is a transmission priority request signal that requests transmission priority.

[0131] AP2 receives the request from AP1 and at time t32 transmits MU-RTS to at least AP1 and STA1 to STA4. At time t33, AP1, STA2, and STA3 return CTS (Clear To Send) to AP2.

[0132] Since the MU-RTS and CTS are transmitted in all directions, it is possible to have surrounding terminals set a NAV (Network Allocation Vector, transmission prohibition period) to control transmission suppression until the end of data transmission. This makes it possible to avoid an increase in hidden terminals due to the precoded preamble.

[0133] At time t34, AP1 starts transmitting a data frame including a data signal of an RTA packet to STA 2. At time t35 after completing transmission of the preamble of the data frame, AP1 starts transmitting data after the preamble to STA 2.

[0134] At time t36, when a time of SIFS+BO has elapsed since time t35, AP2 performs control so as to generate nulls for STA2 by beam control from the transmission of the preamble.

[0135] At time t37, AP1 and AP2 finish data transmission.

[0136] At time t38, STA2 transmits an Ack to AP1, and STA3 transmits an Ack to AP2.

[0137] When AP1 acquires the TXOP, it cannot know the STA to which AP2 wants to transmit, so it requests AP2 to transmit an MU-RTS. However, if AP1 were able to obtain information about AP2's transmission destination in advance, AP1 could transmit the MU-RTS directly.

[0138] <Fifth example of data sequence> FIG. 11 is a diagram illustrating a fifth example of a data sequence in the Data Tx Phase in the first embodiment.

[0139] FIG. 11 shows an example in which AP1 does not receive Ack from STA2 by setting the Ack Policy in the RTA Info field of Preamble / EHT-SIG-A to "No Ack."

[0140] For example, AP1 acquires the TXOP, and at time t41, AP1 starts transmitting a data frame including a data signal of an RTA packet to STA2.

[0141] After receiving the preamble from the data frame transmitted from AP1, AP2 acquires information about AP1 from the received preamble at time t42.

[0142] At time t43, when SIFS+BO has elapsed since time t42, AP2 starts transmitting data to STA3 based on the acquired information about AP1. At time t44, after completing transmission of the preamble of the data frame, AP2 generates a null for STA2 and starts transmitting data after the preamble to STA3.

[0143] At time t45, AP1 ends data transmission.

[0144] At time t46, AP2 finishes data transmission. At time t47, STA3 transmits an Ack to AP2.

[0145] That is, when AP1 transmits an RTA packet to STA1, that is, a packet that is meaningless unless it is transmitted within a certain delay time, it is conceivable that there will be no time to retransmit if the data transmission fails.

[0146] In such a case, for example, AP1 will not receive an Ack from STA2, and will delete the RTA packet from the transmission buffer upon completion of data transmission, preventing retransmission. This eliminates the need for AP2 to consider Ack collisions, and therefore eliminates the need for the operation of synchronizing the end times of data transmission as described above in FIG. 7.

[0147] Therefore, for example, as described above, AP2 can continue its own data transmission even after AP1 has finished transmitting data.

[0148] <Configuration example of wireless communication device> FIG. 12 is a block diagram showing an example of the configuration of a wireless communication device.

[0149] A wireless communication device 11 shown in FIG. 12 is a device that operates as an AP.

[0150] The wireless communication device 11 is made up of a wireless processing unit 21, wireless communication units 22-1 and 22-2, and an AP-to-AP communication unit .

[0151] The wireless processing unit 21 controls communication with the AP and communication with the STA.

[0152] The wireless processing unit 21 is made up of a wireless I / F (interface) unit 31, a data processing unit 32, a communication control unit 33, and a storage unit .

[0153] The wireless I / F unit 31 performs analog conversion on the transmission signal generated by the data processing unit 32, converting the transmission signal from a digital signal to an analog signal. The wireless I / F unit 31 also performs digital conversion on the reception signals acquired by the wireless communication units 22-1 and 22-2, converting the reception signals from an analog signal to a digital signal.

[0154] The data processing unit 32 generates a transmission signal based on the transmission data and control information received from the communication control unit 33 , and outputs the generated transmission signal to the wireless I / F unit 31 .

[0155] The data processing unit 32 demodulates the received signal converted by the wireless I / F unit 31 and extracts the received data and control information. The data processing unit 32 outputs the extracted control information to the communication control unit 33, and outputs the extracted received data to a higher layer (not shown).

[0156] Furthermore, the data processing unit 32 receives control information and data supplied from the AP-to-AP communication unit 23 and outputs them to the communication control unit 33 .

[0157] The communication control unit 33 is configured with a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The communication control unit 33 executes programs stored in the ROM or the like to control the overall operation of the wireless communication device 11. The communication control unit 33 generates control information to be notified to other APs or STAs, and performs processing to transfer the information to the data processing unit 32.

[0158] For example, when operating as AP1, the communication control unit 33 determines whether or not a Precoded Preamble has been requested from AP2 after acquiring the TXOP, and based on the determination result, controls to either transmit the above-mentioned MU-RTS request signal or start data transmission including RTA data.

[0159] For example, when the communication control unit 33 operates as AP2, it transmits an MU-RTS based on the result of determining whether the received signal is an MU-RTS request signal or a data signal, or generates a Null as necessary and controls the waiting or start of data transmission.

[0160] The wireless communication units 22-1 and 22-2 are equipped with antennas, and perform wireless communication with STAs based on communication resources set by the communication control unit 33. The wireless communication units 22-1 and 22-2 are referred to as the wireless communication unit 22 unless there is a particular need to distinguish between them. Note that the number of wireless communication units 22 is not limited to two, and the wireless communication unit 22 is equipped with multiple (n>1) wireless communication units 22-1 to 22-n.

[0161] The wireless communication unit 22 performs RF processing on the wireless signal supplied from the antenna to generate a received signal, and outputs the received signal to the wireless I / F unit 31.

[0162] The wireless communication unit 22 generates a wireless signal by performing RF processing on the transmission signal supplied from the wireless I / F unit 31. The wireless communication unit 22 outputs the generated wireless signal to an antenna.

[0163] The electromagnetic waves received by the antenna are output as radio signals to the wireless communication unit 22. The antenna also emits the radio signals generated by the wireless communication unit 22 as electromagnetic waves.

[0164] The AP-to-AP communication unit 23 performs notification processing or acquisition processing of control information and data necessary for cooperation between APs. The AP-to-AP communication unit 23 includes at least either a wired cable outlet or an antenna, and communication between APs may be wired or wireless. When communication between APs is wireless, the wireless communication unit 22 may be configured to perform the function of the AP-to-AP communication unit 23. Furthermore, communication processing is performed via the wireless communication unit 22 for control information that needs to be transmitted to both the AP and the STA.

[0165] 12 shows an example in which the wireless processing unit 21 is configured as a single IC, the IC configuration of the present technology is not limited to this. For example, the wireless I / F unit 31 may be mounted as a separate IC.

[0166] Furthermore, since the configuration of the wireless communication terminal 12 in FIG. 1 is the configuration of the wireless communication device 11 in FIG. 12 minus the AP-to-AP communication unit 23, hereafter the configuration of the wireless communication device 11 in FIG. 12 will also be used as the configuration of the wireless communication terminal 12.

[0167] <Processing of AP1 in the First Embodiment> FIG. 13 is a flowchart illustrating the processing of the wireless communication device 11-1 operating as the AP1 in the first embodiment.

[0168] In step S31, the communication control unit 33 of the wireless communication device 11-1 acquires a TXOP by, for example, Back Off.

[0169] In step S32, the communication control unit 33 determines whether or not a precoded preamble, i.e., interference suppression from a preamble, has been requested from the AP 2. If it is determined in step S32 that a precoded preamble has been requested from the AP 2, the process proceeds to step S33 (FIG. 10).

[0170] In step S33, the wireless communication unit 22 transmits an MU-RTS request signal to the AP2, requesting an MU-RTS.

[0171] In response to this, AP2 sends MU-RTS.

[0172] In step S34, the wireless communication unit 22 receives the MU-RTS transmitted from the AP2, and then transmits a CTS to the AP2.

[0173] If it is determined in step S32 that a precoded preamble has not been requested from AP2, steps S33 and S34 are skipped and the process proceeds to step S35 (FIGS. 7 to 9, and FIG. 11).

[0174] In step S35, the wireless communication unit 22 starts transmitting data to the STA2.

[0175] <Processing of AP2 in the First Embodiment> FIG. 14 is a flowchart illustrating the processing of the wireless communication device 11-2 operating as the AP2 in the first embodiment.

[0176] In step S51, the wireless communication unit 22 of the wireless communication device 11-2 receives a signal transmitted from the AP1.

[0177] In step S52, communication control unit 33 determines whether or not the signal received by wireless communication unit 22 is an MU-RTS request signal. If it is determined in step S52 that the signal received by wireless communication unit 22 is an MU-RTS request signal, the process proceeds to step S53.

[0178] In step S53, wireless communication unit 22 transmits the MU-RTS. As described above with reference to Figure 10, the destinations to which the MU-RTS is transmitted include at least AP1, the destination of AP1 (STA2), and the destination of AP2 (STA3). Note that information about the destination of AP1 is included in the MU-RTS request signal.

[0179] For example, if the signal received by the wireless communication unit 22 is a data signal and it is determined in step S52 that the signal received by the wireless communication unit 22 is not an MU-RTS request signal, the process proceeds to step S54.

[0180] In step S54, the communication control unit 33 checks the SIG-A of the preamble in the received signal.

[0181] In step S55, the communication control unit 33 determines whether or not to generate a Null for the STA2 that is the destination of the AP1, based on the SIG-A of the checked preamble.

[0182] The condition for generating a Null is that at least the Receiver STA ID must be the same as the STA ID (Coordination STA ID) specified by AP1 in the Coordination Request Frame. This may also be determined in conjunction with other conditions. For example, if it can be calculated that even if AP2 transmits to the destination STA3 at maximum transmission power, the interference power to STA2 will not exceed the Allowable Interference level, AP2 does not need to generate a Null for STA2. Furthermore, if the RTA flag in the RTA Info of the preamble is "0", AP2 does not need to generate a Null for STA2.

[0183] If it is determined in step S55 that Null is to be generated in STA2, the process proceeds to step S56.

[0184] In step S56, the communication control unit 33 determines whether or not a preamble collision can be avoided while the AP1 is transmitting the RTA packet.

[0185] In step S56, it is determined that preamble collision can be avoided if any of the following (1) to (3) is true:

[0186] (1) When the Precoded Preamble field of the Preamble / EHT-SIG-A in the previously acquired Coordination Request Element (or the currently received data signal) is “0” (i.e., no interference suppression request is made from the preamble) (Figure 10). (2) If the RTA field of the Preamble / EHT-SIG-A of the currently received data frame indicates that the Preamble to be sent by itself does not overlap with the RTA packet sent by AP1 (Figure 9). (3) Interference suppression using only transmission power control (Figure 7)

[0187] If it is determined in step S56 that a preamble collision can be avoided, the process proceeds to step S57.

[0188] In step S57, the communication control unit 33 generates a Null for STA2, and the wireless communication unit 22 causes STA3 to start data transmission.

[0189] If it is determined in step S56 that a preamble collision cannot be avoided, the process proceeds to step S58. In step S58, the communication control unit 33 sets the NAV and waits for data transmission until the data transmission of AP1 is completed.

[0190] If it is determined in step S54 that Null is not to be generated in STA2, the process proceeds to step S59.

[0191] In step S59, the wireless communication unit 22 starts transmitting data to the STA3.

[0192] After steps S53 and S57 to S59, the process of FIG. 14 ends.

[0193] 3. Second embodiment (example in which AP2 acquires transmission right first) Next, as a second embodiment, an example in which AP2 acquires the transmission right first will be described.

[0194] <Example of overall processing sequence> FIG. 15 is a sequence diagram illustrating the overall processing of the wireless communication system according to the second embodiment.

[0195] The processing of the wireless communication system shown in FIG. 15 is divided into five phases, namely, a Multi-AP Group Set Phase, a Sounding Phase, a Coordination Set Phase, a Data Tx Phase, and a Coordination End Phase, similar to FIG.

[0196] Steps S101 and S102 are the Multi-AP Group Set Phase, similar to steps S1 and S2 in Fig. 2. Steps S103 to S106 are the Sounding Phase, similar to steps S3 to S6 in Fig. 2. Steps S107 and S108 are the Coordination Set Phase, similar to steps S7 and S8 in Fig. 2.

[0197] Steps S109 to S111 are Data Tx Phases, but the order of data transmission differs from steps S9 to S11 in Fig. 2. Steps S112 and S113 are Coordination End Phases similar to steps S12 and S13 in Fig. 2.

[0198] That is, steps S101 to S108, S112 and S113 in FIG. 15 perform the same processing as steps S1 to S8, S12 and S13 in FIG. 2, and therefore the description thereof will be omitted.

[0199] 2, in step S109, AP2 performs data transmission to STA3. In step S110, AP1 performs data transmission to STA2. In step S111, STA3 transmits an Ack to AP2, and STA2 transmits an Ack to AP1.

[0200] <First example of data sequence> FIG. 16 is a diagram illustrating a first example of a data sequence in the Data Tx Phase in the second embodiment.

[0201] FIG. 16 shows an example in which AP2 generates Null for STA2 and transmits a data signal to STA3, and AP1 transmits a data signal including an RTA packet to STA2 without generating Null.

[0202] In FIG. 16, the parts corresponding to those in FIG. 7 are repeated, so the description thereof will be omitted as appropriate.

[0203] AP2 acquires the TXOP and starts transmitting a data frame to STA3 at time t101. At time t102 after completing transmission of the preamble of the data frame, AP2 generates a null for STA2 and starts transmitting data after the preamble to STA3.

[0204] After receiving the preamble transmitted from AP2, at time t102, AP1 acquires information about AP2 from the received preamble, which is similar to the information about AP1 in the case of Fig. 7. At time t103, when a time of SIFS+BO has elapsed since time t102, AP1 starts transmitting data including RTA data to STA2 based on the acquired information about AP2. At time t104, after completing transmission of the preamble, AP1 starts transmitting data after the preamble to STA3, which is part of the data signal.

[0205] At time t105, AP1 and AP2 finish data transmission.

[0206] At time t106, STA2 transmits an Ack to AP1, and STA3 transmits an Ack to AP2.

[0207] <Second example of data sequence> FIG. 17 is a diagram illustrating a second example of a data sequence in the Data Tx Phase in the second embodiment.

[0208] 17, similarly to FIG. 8, an example is shown in which AP2 generates Null for STA2, and AP1 generates Null for STA3.

[0209] In FIG. 17, the parts corresponding to those in FIG. 8 are repeated, so the description thereof will be omitted as appropriate.

[0210] AP2 acquires the TXOP and starts transmitting a data frame to STA3 at time t111. At time t102 after completing transmission of the preamble of the data frame, AP2 generates a null for STA2 and starts transmitting data after the preamble to STA3.

[0211] After receiving the preamble transmitted from AP2, AP1 acquires information about AP2 from the received preamble at time t112. At time t113, which is SIFS+BO after time t112, AP1 starts transmitting data including RTA data to STA2 based on the acquired information about AP2. At time t114, after completing transmission of the preamble in the data signal, AP1 generates Null for STA3 and starts transmitting data after the preamble to STA2.

[0212] At time t115, AP1 and AP2 finish data transmission.

[0213] At time t116, STA2 transmits an Ack to AP1, and STA3 transmits an Ack to AP2.

[0214] <Third example of data sequence> FIG. 18 is a diagram illustrating a third example of a data sequence in the Data Tx Phase in the second embodiment.

[0215] 18 shows an example in which AP1 uses a method (precoded preamble) to generate nulls for STA3 by beam control. In this case, unlike in FIGS. 16 and 17, AP1 can suppress interference from preambles to STA3.

[0216] However, on the other hand, applying beam control from the preamble raises the concern that hidden terminals that cannot detect signals from AP1 may occur.

[0217] Therefore, when AP2 acquires a TXOP and requests a precoded preamble from AP1, it transmits an MU-RTS to AP1 and STA1 to STA4 at time t131.

[0218] In FIG. 18, the parts corresponding to those in FIG. 10 are repeated, so the description thereof will be omitted as appropriate.

[0219] At time t132, AP1, STA2, and STA3 return CTS to AP2.

[0220] At time t133, AP2 starts transmitting a data frame to STA3. At time t134 after completing transmission of the preamble of the data frame, AP2 generates a null for STA2 and starts transmitting data after the preamble to STA3.

[0221] After receiving the preamble transmitted from AP2, AP1 acquires information about AP2 from the received preamble at time t134. At time t135, when SIFS+BO has elapsed since time t134, AP1 generates a null for STA3 based on the acquired information about AP2, and starts transmitting data including RTA data to STA2.

[0222] At time t136, AP1 and AP2 finish data transmission.

[0223] At time t137, STA2 transmits an Ack to AP1, and STA3 transmits an Ack to AP2.

[0224] <Fourth example of data sequence> FIG. 19 is a diagram illustrating a fourth example of a data sequence in the Data Tx Phase in the second embodiment.

[0225] 19, similarly to FIG. 11, an example is shown in which AP1 does not receive an Ack from STA2 by, for example, setting the Ack Policy in the RTA Info field of Preamble / EHT-SIG-A to "No Ack."

[0226] In FIG. 19, the parts corresponding to those in FIG. 11 are repeated, so the description thereof will be omitted as appropriate.

[0227] For example, AP2 acquires a TXOP, and at time t141, AP2 starts transmitting a data frame to STA3. At time t142 after completing transmission of the preamble of the data frame, AP2 generates a null for STA2, and starts transmitting data after the preamble to STA3.

[0228] After receiving the preamble signal transmitted from AP2, at time t142 AP1 acquires information about AP2 from the received preamble.

[0229] At time t143, when a time period of SIFS+BO has elapsed since time t142, AP1 starts transmitting data including an RTA packet to STA2 based on the acquired information about AP2.

[0230] At time t144, AP1 ends data transmission.

[0231] At time t145, AP2 finishes transmitting data. At time t146, STA3 transmits an Ack to AP2.

[0232] That is, when AP1 transmits an RTA packet to STA1, that is, a packet that is meaningless unless it is transmitted within a certain delay time, it is conceivable that there will be no time to retransmit if the data transmission fails.

[0233] In such a case, for example, AP1 will not receive an Ack from STA2, and will erase the RTA packet from the transmission buffer upon completion of data transmission, preventing retransmission. In other words, AP2 does not need to consider Ack collisions, and therefore does not need to synchronize the end times of data transmission, as in the case of Figure 11.

[0234] Therefore, for example, as described above, AP2 can continue its own data transmission even after AP1 has finished transmitting data.

[0235] <Processing of AP2 in the second embodiment> FIG. 20 is a flowchart illustrating the processing of the wireless communication device 11-2 operating as the AP2 in the second embodiment.

[0236] In step S131, the communication control unit 33 of the wireless communication device 11-2 acquires a TXOP by, for example, Back Off.

[0237] In step S132, the communication control unit 33 determines whether or not a precoded preamble has been requested from the AP 1. If it is determined in step S32 that a precoded preamble has been requested from the AP 1, the process proceeds to step S133 (FIG. 18).

[0238] In step S133, the wireless communication unit 22 transmits the MU-RTS to at least AP1, STA2, and STA3.

[0239] In response to this, the AP 1 transmits a CTS. After the wireless communication unit 22 receives the CTS transmitted from the AP 1, the process proceeds to step S134.

[0240] If it is determined in step S132 that a precoded preamble has not been requested from AP1, the process of step S133 is skipped and the process proceeds to step S134.

[0241] In step S134, the wireless communication unit 22 starts transmitting data to STA3.

[0242] <Processing of AP1 in the second embodiment> FIG. 21 is a flowchart illustrating the processing of the wireless communication device 11-1 operating as the AP1 in the second embodiment.

[0243] In step S151, the wireless communication unit 22 of the wireless communication device 11-2 receives a signal transmitted from the AP1.

[0244] In step S152, the communication control unit 33 determines whether or not the signal received by the wireless communication unit 22 is an MU-RTS. If it is determined in step S152 that the signal received by the wireless communication unit 22 is an MU-RTS, the process proceeds to step S153.

[0245] In step S153, the wireless communication unit 22 transmits a CTS to AP2 after a SIFS.

[0246] For example, if the signal received by the wireless communication unit 22 is a data signal and it is determined in step S152 that the signal received by the wireless communication unit 22 is not an MU-RTS, the process proceeds to step S154.

[0247] In step S154, the communication control unit 33 checks the SIG-A of the preamble in the received signal.

[0248] In step S155, the communication control unit 33 determines whether or not the Nulling flag in the SIG-A of the checked preamble is 1. If it is determined in step S155 that the Nulling flag is 1, the process proceeds to step S156.

[0249] In step S156, the communication control unit 33 determines whether generation of Null has been requested by AP 2 and whether a collision cannot be avoided. If it is determined in step S156 that generation of Null has not been requested by AP 2 or that a collision can be avoided, the process proceeds to step S157.

[0250] In step S157, the wireless communication unit 22 causes the STA2 to start data transmission.

[0251] Also, if it is determined in step S155 that the Nulling flag is 0, or if it is determined in step S156 that AP2 has requested the generation of Null and a collision cannot be avoided, the process proceeds to step S158.

[0252] In step S158, the wireless communication unit 22 waits for data transmission to STA2.

[0253] Although the first and second embodiments have been described with reference to the case where an AP transmits data to a STA, the present technology can also be applied to the case where a STA transmits data to an AP.

[0254] 4. Third Embodiment (Example of Transmission from STA to AP) Next, as a third embodiment, a case where a STA transmits an RTA packet and a STA in another cell generates a NULL will be described.

[0255] <Example of overall processing sequence> FIG. 22 is a diagram showing a sequence for explaining the overall processing of the wireless communication system in the third embodiment.

[0256] The processing of the wireless communication system shown in FIG. 22 is divided into five phases, namely, a Multi-AP Group Set Phase, a Sounding Phase, a Coordination Set Phase, a Data Tx Phase, and a Coordination End Phase, similar to FIG. 2.

[0257] Steps S201 and S202 in Fig. 22 are the Multi-AP Group Set Phase, similar to steps S1 and S2 in Fig. 2. Steps S203 to S206 are the Sounding Phase, similar to steps S3 to S6 in Fig. 2. Steps S201 to S206 in Fig. 22 perform the same processing as steps S1 to S6 in Fig. 2, and therefore description thereof will be omitted.

[0258] That is, steps S207 to S209 are the Coordination Set Phase. In the Coordination Set Phase, a coordinated operation between AP1 and AP2, that is, a setup for starting interference suppression to STAs or APs in other cells, is performed.

[0259] For example, in step S207, a STA (STA2 in the case of FIG. 22) that wants to start transmitting an RTA packet transmits a Coordination Request Frame to an AP of another cell (AP2 in the case of FIG. 22). In step S208, AP2 transmits a Coordination Response Frame, and STA2 receives the Coordination Response Frame to determine whether or not the other cell is capable of cooperation.

[0260] In the Coordination Set Phase, a STA may request coordination from multiple APs, or may request coordination from one AP that is most likely to be affected by interference. Furthermore, as indicated by the dashed arrow, this frame exchange may be performed via an AP connected to the same cell (AP1 in FIG. 22).

[0261] If AP2 accepts the request for coordination from STA2, in step S209, AP2 transmits a Coordination Info Sharing Frame, which is a coordination information sharing signal for sharing coordination information, to its subordinate STAs (STA3 and STA4 in FIG. 22). The Coordination Info Sharing Frame is transmitted to request STA2 to share the necessary information or to suppress transmission in order to generate a Null when the subordinate STA starts data transmission.

[0262] In the Coordination Set Phase of FIG. 22, an example has been described in which the other party that sends an RTA packet and generates a NULL generates a NULL for STA2 and transmits an RTA packet, but it may also generate a NULL for AP1 and transmit an RTA packet.

[0263] Steps S210 to S212 are the Data Tx Phase. In the Data Tx Phase, in the case of Fig. 22, STA2 transmits data to AP1 of the cell to which it belongs.

[0264] For example, in step S210, STA2 performs data transmission to AP1. In step S211, STA3 performs data transmission to AP2. At this time, for example, STA3 performs interference suppression with STA2 (or AP1). In step S212, AP1 transmits an Ack to STA2. Although not shown, AP2 transmits an Ack to STA2.

[0265] Steps S213 to S215 are the Coordination End Phase. In the Coordination End Phase, the AP1 and AP2 perform a process of ending the cooperative operation, that is, ending interference suppression with STAs or APs in other cells.

[0266] That is, in step S213, when STA2 finishes transmitting the RTA packet, it transmits a Coordination End Frame to AP2 in the same way as in the Coordination Set Phase to end the cooperation operation. That is, as shown by the dashed arrow, this frame exchange may be carried out via the destination AP (AP1 in FIG. 22) of the same cell.

[0267] In step S214, AP2 transmits an Ack to STA2. Note that the transmission of Ack is optional. Also, in step S215, AP2 transmits a Coordination End Frame to the subordinate STAs to end the cooperation operation.

[0268] In step S211 of FIG. 22, an example where STA3 performs Data Transmission to AP2 has been described. However, for example, AP2 may perform Data Transmission to STA3. At this time, for example, AP2 performs interference suppression on STA2 (or AP1).

[0269] <Configuration Example of Coordination Info Sharing Frame> FIG. 23 is a diagram showing a configuration example of the Coordination Info Sharing Frame.

[0270] The Coordination Info Sharing Frame is composed of a MAC Header, a Frame Body, and an FCS.

[0271] The Frame Body is composed of fields such as Category, Multi-AP Action, Dialog Token, and Coordination Info Element.

[0272] A value indicating that this frame is an Action Frame for Multi-AP is set in the Category field.

[0273] The Multi-AP Action field is set to a value indicating that this frame is a Coordination Info Sharing Frame.

[0274] The Dialog Token field is set to the same value as the Dialog Token of the Coordination Request Frame whose processing is terminated in this frame.

[0275] The Coordination Info Element field contains information that is shared when the AP requests the subordinate STAs to cooperate.

[0276] The Coordination Info Element field includes the fields of Element ID, Length, Coordination Request Element, and User Info #1 to User Info #N.

[0277] The Element ID field contains identification information that indicates that this frame is a Coordination Info Sharing Frame.

[0278] The Length field contains information about the length of this frame.

[0279] The Coordination Request Element field contains information about the party for whom the NULL is to be generated.

[0280] Each of the fields User Info #1 to User Info #N includes Allowable Tx Power and Nulling Tx Weight Info.

[0281] Allowable Tx Power is information indicating the allowable transmission power for each subordinate STA.

[0282] Nulling Tx Weight Info is transmission weight information required for beam control.

[0283] The transmission weight information required for the above-mentioned beam control must be obtained by channel estimation between STAs in different cells in the sounding phase, and the AP must obtain the feedback information.

[0284] Furthermore, the present invention is not limited to the example of FIG. 23, and transmission suppression of the STA may be implemented by providing another field or by setting a specific value in the Allowable Tx Power field.

[0285] The STA that receives this frame acquires TXOP and starts data transmission by setting the transmission power below the notified allowable transmission power value or by performing transmission wait processing and starting data transmission. If the AP notifies the STA to suppress transmission, the corresponding STA sets NAV and waits for transmission.

[0286] In Fig. 23, the Coordination Info Sharing Frame is shown as part of the Action Frame defined in IEEE 802.11, but the configuration of the frame is not limited to the example in Fig. 23. For example, it may be configured as a Management Frame or Control Frame that includes a field equivalent to the Coordination Info Element or the information specified in this Element.

[0287] <5.Other> In this embodiment, the waiting time for the subsequent AP has been described as SIFS+BO, but this is because it is assumed that the waiting time will be randomized by BO so that data transmission collisions will not occur even if there are three or more APs.

[0288] If there are only two APs, or if the AP that transmits first can specify the AP that can transmit next using an MU-RTS Trigger / MU-RTS Frame in the preamble of the data signal, the AP that will transmit next does not need a BO and can wait for only an SIFS before starting data transmission.

[0289] <Effects of this technology> As described above, in the first present technology, AP1 (wireless communication device) transmits a first data frame including a first data signal to STA2 (wireless terminal). Then, before transmitting the first data frame, transmission of a suppression request signal requesting AP2 (another wireless communication device) to suppress interference with STA2 is controlled.

[0290] This makes it possible for AP1 to reduce the transmission delay of data that requires at least one of low delay and high reliability.

[0291] In the second aspect of the present technology, an AP2 (wireless communication device) receives a suppression request signal, which requests interference suppression for the first wireless terminal, transmitted from an AP1 (another wireless communication device) that transmits a first data frame including a first data signal to an STA2 (first wireless terminal) before the transmission of the first data frame. Then, based on the suppression request signal, it is determined whether to perform interference suppression.

[0292] As a result, AP2 can minimize the degradation of transmission quality that accompanies a reduction in transmission power and a reduction in antenna flexibility.

[0293] In the third aspect of the present technology, a data frame including a data signal is transmitted from STA2 (wireless communication terminal) to AP1 (first wireless communication device). Then, before transmitting the data frame, transmission of a suppression request signal requesting interference suppression from AP2 (second wireless communication device) is controlled.

[0294] In the fourth present technology, AP2 (wireless communication device) receives an interference request signal requesting interference suppression from STA2 (first wireless communication terminal) that transmits a first data frame including a first data signal, and when transmitting a second data frame different from the first data frame to a second wireless communication terminal, it determines based on the interference request signal whether or not STA2 will suppress interference with AP1 (another wireless communication device) that transmits the first data frame.

[0295] In a fifth aspect of the present technology, a STA3 (wireless communication terminal) receives from an AP2 (wireless communication device) a cooperative information sharing signal that shares a request for interference suppression with an STA2 (another wireless communication terminal) that transmits a first data frame including a first data signal. Then, when transmitting a second data frame different from the first data frame to the AP2, the STA2 determines, based on the cooperative information sharing signal, whether to suppress interference with the AP1 (another wireless communication device) that transmits the first data frame.

[0296] As a result, even when STA2 transmits data, it is possible to reduce the data transmission delay.

[0297] <Example of computer configuration> The above-described series of processes can be executed by hardware or software. When the series of processes is executed by software, the program constituting the software is installed from a program recording medium into a computer incorporated in dedicated hardware or a general-purpose personal computer.

[0298] FIG. 24 is a block diagram showing an example of the hardware configuration of a computer that executes the above-described series of processes using a program.

[0299] A CPU (Central Processing Unit) 301 , a ROM (Read Only Memory) 302 , and a RAM (Random Access Memory) 303 are interconnected by a bus 304 .

[0300] An input / output interface 305 is also connected to the bus 304. An input unit 306 including a keyboard, a mouse, etc., and an output unit 307 including a display, a speaker, etc. are connected to the input / output interface 305. In addition, a storage unit 308 including a hard disk, a nonvolatile memory, etc., a communication unit 309 including a network interface, etc., and a drive 310 that drives removable media 311 are also connected to the input / output interface 305.

[0301] In the computer configured as above, the CPU 301 loads a program stored in the storage unit 308 into the RAM 303 via the input / output interface 305 and the bus 304 and executes the program, thereby performing the series of processes described above.

[0302] The program executed by the CPU 301 is installed in the storage unit 308 by being recorded on a removable medium 311, or provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital broadcasting.

[0303] The program executed by the computer may be a program that processes in chronological order according to the order described in this specification, or may be a program that processes in parallel or at the required timing, such as when called.

[0304] In this specification, a system refers to a collection of multiple components (devices, modules (components), etc.), regardless of whether all the components are contained in the same housing. Therefore, multiple devices housed in separate housings and connected via a network, and a single device housed in a single housing with multiple modules, are both systems.

[0305] Furthermore, the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0306] The embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present technology.

[0307] For example, this technology can be configured as cloud computing, in which a single function is shared and processed collaboratively by multiple devices via a network.

[0308] Furthermore, each step described in the above flowchart can be executed by one device, or can be shared and executed by multiple devices.

[0309] Furthermore, when one step includes multiple processes, the multiple processes included in that one step can be executed by one device or can be shared and executed by multiple devices.

[0310] <Configuration combination example> The present technology can also be configured as follows. (1) a wireless communication unit that transmits a first data frame including a first data signal to a wireless terminal; a communication control unit that controls transmission of a suppression request signal that requests other wireless communication devices to suppress interference with the wireless terminal before transmitting the first data frame; A wireless communication device comprising: (2) The wireless communication device described in (1), wherein the communication control unit includes, in the suppression request signal, identification information of the wireless terminal, information regarding the transmission time of the first data signal, or information indicating the allowable interference power of the wireless terminal. (3) The communication control unit includes, in the suppression request signal, information indicating whether or not to perform the interference suppression from a head of a data frame transmitted by the other wireless communication device. The wireless communication device according to (1) or (2). (4) the wireless communication unit receives a response signal in response to the suppression request signal; The communication control unit determines, based on information of the response signal, whether to perform the interference suppression on a second data signal, which is different from the first data signal, to a destination, by the other wireless communication device, when transmitting the first data frame. The wireless communication device according to any one of (1) to (3). (5) The wireless communication device according to any one of (1) to (4), wherein the communication control unit includes, in the first data frame, information regarding identification information of the wireless terminal, the presence or absence of the first data signal, and the transmission time of the first data signal. (6) The communication control unit controls transmission of a transmission request signal to request transmission of a priority request signal requesting transmission priority to the other wireless communication device before transmitting the first data frame. The wireless communication device according to any one of (1) to (5). (7) The communication control unit determines whether to start transmission of the first data frame based on information included in a second data frame that is transmitted from the other wireless communication terminal and is different from the first data frame. The wireless communication device according to any one of (1) to (6). (8) When the communication control unit completes transmission of the first data frame, the communication control unit controls transmission of a notification signal notifying the other wireless communication device of the end of the interference suppression. The wireless communication device according to any one of (1) to (7). (9) The first data signal is data that requires at least one of low delay and high reliability. The wireless communication device according to any one of (1) to (8). (10) A wireless communication device transmitting a first data frame including a first data signal to the wireless terminal; Before transmitting the first data frame, control is made to transmit a suppression request signal that requests other wireless communication devices to suppress interference with the wireless terminal. Wireless communication method. (11) a wireless communication unit that receives a suppression request signal that requests interference suppression for a first wireless terminal, the suppression request signal being transmitted from another wireless communication device that transmits a first data frame including a first data signal to the first wireless terminal before the first data frame is transmitted; a communication control unit that determines whether to perform the interference suppression based on the suppression request signal; A wireless communication device comprising: (12) The communication control unit controls transmission of a response signal including information on whether or not the interference can be suppressed and a reason for the whether or not the interference can be suppressed, as a response to the suppression request signal. The wireless communication device according to (11). (13) The communication control unit generates, as a response to the suppression request signal, a response signal including information requesting the other wireless communication device to suppress the interference with a second wireless terminal that is a transmission destination of the communication control unit. The wireless communication device according to (11) or (12). (14) The communication control unit subsequently determines whether to start transmitting a second data frame different from the first data frame to a second wireless terminal that is a transmission destination of the first data frame, and whether to perform the interference suppression on the first wireless terminal, based on identification information of the first wireless terminal included in the first data frame, whether or not the first data signal is present, and information related to a transmission time of the first data signal. The wireless communication device according to (11). (15) The communication control unit determines whether to perform the interference suppression on the first wireless terminal designated by the suppression request signal when starting transmission of a second data frame different from the first data frame to a second wireless terminal that is a transmission destination of the communication control unit. The wireless communication device according to (11). (16) The first data signal is data that requires at least one of low delay and high reliability. The wireless communication device according to any one of (11) to (15). (17) A wireless communication device receiving a suppression request signal requesting interference suppression for a first wireless terminal, the suppression request signal being transmitted from another wireless communication device that transmits a first data frame including a first data signal to the first wireless terminal before the first data frame is transmitted; Determine whether to perform the interference suppression based on the suppression request signal. Wireless communication method. (18) a wireless communication unit that transmits a data frame including a data signal to the first wireless communication device; a communication control unit that controls transmission of a suppression request signal that requests interference suppression to a second wireless communication device before transmitting the data frame; A wireless communication terminal comprising: (19) Wireless communication terminal Transmitting a data frame including a data signal to a first wireless communication device; Controlling transmission of a suppression request signal that requests interference suppression from the second wireless communication device before transmitting the data frame. Wireless communication method. (20) a wireless communication unit that receives an interference request signal requesting interference suppression from a first wireless communication terminal that transmits a first data frame including a first data signal; a communication control unit that determines, when transmitting a second data frame different from the first data frame to a second wireless communication terminal, whether or not to perform the interference suppression on another wireless communication device to which the first wireless communication terminal transmits the first data frame, based on the interference request signal; A wireless communication device comprising: (twenty one) A wireless communication device receiving an interference request signal requesting interference suppression from a first wireless communication terminal transmitting a first data frame including a first data signal; When transmitting a second data frame different from the first data frame to a second wireless communication terminal, the first wireless communication terminal determines, based on the interference request signal, whether or not to perform the interference suppression on another wireless communication device that transmits the first data frame. Wireless communication method. (twenty two) a communication unit that receives, from the wireless communication device, a cooperative information sharing signal that shares a request for interference suppression to another wireless communication terminal that transmits a first data frame including a first data signal; a communication control unit that determines, based on the cooperative information sharing signal, whether or not the other wireless communication terminal performs the interference suppression on the other wireless communication device that transmits the first data frame when transmitting a second data frame different from the first data frame to the wireless communication device; A wireless communication terminal comprising: (twenty three) The wireless communication terminal receiving, from the wireless communication device, a cooperative information sharing signal that shares a request for interference suppression with another wireless communication terminal that transmits a first data frame including a first data signal; When transmitting a second data frame different from the first data frame to the wireless communication device, the other wireless communication terminal determines, based on the cooperative information sharing signal, whether or not to perform the interference suppression on the other wireless communication device that transmits the first data frame. Wireless communication method. [Explanation of symbols]

[0311] 11-1, 11-2, 11 wireless communication device, 12-1 to 12-4, 12 wireless communication terminal, 21 wireless processing unit, 22-1, 22-2, 22 wireless communication unit, 23 AP-to-AP communication unit, 31 wireless I / F unit, 32 data processing unit, 33 communication control unit, 34 storage unit

Claims

1. a wireless communication unit that transmits a first data frame including a first data signal to a wireless terminal; a communication control unit that controls transmission of a suppression request signal that requests other wireless communication devices to suppress interference with the wireless terminal before transmitting the first data frame; A wireless communication device comprising:

2. The communication control unit includes, in the suppression request signal, identification information of the wireless terminal, information related to a transmission time of the first data signal, or information indicating an allowable interference power of the wireless terminal. The wireless communication device of claim 1 .

3. The communication control unit includes, in the suppression request signal, information indicating whether or not to perform the interference suppression from the beginning of a data frame transmitted by the other wireless communication device. The wireless communication device of claim 1 .

4. the wireless communication unit receives a response signal in response to the suppression request signal; The communication control unit determines, based on information of the response signal, whether to perform the interference suppression on a second data signal, which is different from the first data signal, to a destination, by the other wireless communication device, when transmitting the first data frame. The wireless communication device of claim 1 .

5. The communication control unit includes, in the first data frame, information regarding identification information of the wireless terminal, whether or not the first data signal is present, and information regarding a transmission time of the first data signal. The wireless communication device of claim 1 .

6. The communication control unit controls transmission of a transmission request signal to request the other wireless communication device to transmit a priority request signal requesting transmission priority before transmitting the first data frame. The wireless communication device of claim 1 .

7. The communication control unit determines whether to start transmission of the first data frame based on information included in a second data frame that is transmitted from the other wireless communication terminal and is different from the first data frame. The wireless communication device of claim 1 .

8. When the communication control unit completes transmission of the first data frame, the communication control unit controls transmission of a notification signal notifying the other wireless communication device of the end of the interference suppression. The wireless communication device of claim 1 .

9. The first data signal is data that requires at least one of low delay and high reliability. The wireless communication device of claim 1 .

10. a wireless communication unit that receives a suppression request signal that requests interference suppression for a first wireless terminal, the suppression request signal being transmitted from another wireless communication device that transmits a first data frame including a first data signal to the first wireless terminal before the first data frame is transmitted; a communication control unit that determines whether to perform the interference suppression based on the suppression request signal; A wireless communication device comprising:

11. The communication control unit controls transmission of a response signal including information on whether or not the interference can be suppressed and a reason for the whether or not the interference can be suppressed, as a response to the suppression request signal. The wireless communication device of claim 10.

12. The communication control unit controls transmission of a response signal including information requesting the other wireless communication device to suppress the interference with a second wireless terminal that is a transmission destination of the communication control unit, as a response to the suppression request signal. The wireless communication device of claim 10.

13. The communication control unit subsequently determines whether to start transmission of a second data frame different from the first data frame to a second wireless terminal that is a transmission destination of the first data frame, and whether to perform the interference suppression on the first wireless terminal, based on identification information of the first wireless terminal included in the first data frame, whether or not the first data signal is present, and information related to a transmission time of the first data signal. The wireless communication device of claim 10.

14. The communication control unit determines whether to perform the interference suppression on the first wireless terminal designated by the suppression request signal when starting transmission of a second data frame different from the first data frame to a second wireless terminal that is a transmission destination of the communication control unit. The wireless communication device of claim 10.

15. The first data signal is data that requires at least one of low delay and high reliability. The wireless communication device of claim 10.

16. a wireless communication unit that transmits a data frame including a data signal to the first wireless communication device; a communication control unit that controls transmission of a suppression request signal that requests interference suppression to the second wireless communication device before transmitting the data frame; A wireless communication terminal comprising:

17. a wireless communication unit that receives an interference request signal requesting interference suppression from a first wireless communication terminal that transmits a first data frame including a first data signal; a communication control unit that determines, when transmitting a second data frame different from the first data frame to a second wireless communication terminal, whether or not to perform the interference suppression on another wireless communication device to which the first wireless communication terminal transmits the first data frame, based on the interference request signal; A wireless communication device comprising:

18. a communication unit that receives, from the wireless communication device, a cooperative information sharing signal that shares a request for interference suppression to another wireless communication terminal that transmits a first data frame including a first data signal; a communication control unit that determines, based on the cooperative information sharing signal, whether or not the other wireless communication terminal performs the interference suppression on the other wireless communication device that transmits the first data frame when transmitting a second data frame different from the first data frame to the wireless communication device; A wireless communication terminal comprising:

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