Communication Equipment

Abstract

To provide a communication device that can more efficiently avoid a hidden node problem.SOLUTION: A communication device comprises: a communication unit configured to transmit, to another communication device, a data signal including a transmission request of a busy signal which is a signal, in which no information is described, indicating that a channel is in use in a case of satisfying a predetermined condition; a determination unit configured to determine whether the other communication device which has received the data signal transmitted by the communication unit transmits the busy signal; and a control unit configured to control a process of transmitting the data signal to the other communication device in accordance with a result of the determination by the determination unit. The control unit transmits the busy signal after the transmission of the data signal has been completed, and controls the communication unit to stop the transmission of the busy signal when ACK is not received within a predetermined time from a start of the busy signal transmission.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a communication device. [Background technology]

[0002] In a wireless communication system, when multiple communication terminals are located in positions where they cannot detect each other, a hidden terminal problem occurs in which frames transmitted by each communication terminal collide. In the IEEE 802.11 standard for half-duplex communication, the hidden terminal problem is solved by having communication terminals exchange RTS (Request to Send) / CTS (Clear to Send) frames. However, in the RTS / CTS frame exchange, the time it takes for communication terminals to exchange frames is an overhead. In addition, the RTS / CTS frame exchange cannot reduce the influence of hidden terminals in other communication systems that cannot know the contents of the CTS frame. Therefore, as a technology for making wireless communication more efficient, technology related to full duplex communication, which can transmit and receive simultaneously, is being developed.

[0003] For example, Patent Document 1 discloses a method in which a full-duplex communication-compatible terminal transmits a busy signal to reduce the influence of hidden terminals. The busy signal has duration information calculated from information described in the data signal being received. The hidden terminal that receives the busy signal sets a transmission inhibition period based on the duration information. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 9,560,674 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method of Patent Document 1 is effective only for terminals that can decode the duration information, and cannot fully avoid the influence of hidden terminals in other communication systems that cannot decode the duration information. In addition, a full-duplex terminal transmits a busy signal when it detects a data signal, which may greatly reduce the transmission opportunities of hidden terminals.

[0006] Therefore, the present disclosure has been made in consideration of the above, and provides a new and improved communication device that can more efficiently avoid the hidden terminal problem. [Means for solving the problem]

[0007] According to the present disclosure, there is provided a communication device comprising: a communication unit that transmits to another communication device a data signal including a request to send a busy signal, which is a signal without information indicating that a channel is in use when a specified condition is met; a determination unit that determines whether the other communication device that received the data signal transmitted by the communication unit is transmitting the busy signal; and a control unit that controls the process of transmitting the data signal to the other communication device depending on the determination result of the determination unit, wherein the control unit transmits the busy signal after transmission of the data signal is completed, and controls the communication unit to stop transmitting the busy signal if no ACK is received within a specified time from the start of transmission of the busy signal. Effect of the Invention

[0008] As described above, according to the present disclosure, it is possible to more efficiently avoid the hidden terminal problem.

[0009] It should be noted that the above effects are not necessarily limiting, and any of the effects shown in this specification, or other effects that can be understood from this specification, may be achieved in addition to or instead of the above effects. [Brief description of the drawings]

[0010] [Figure 1]FIG. 1 is a diagram illustrating a configuration of a communication system according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a diagram illustrating a configuration of a communication system of a comparative example. [Diagram 3] FIG. 11 is a sequence diagram showing an example of an operation of a communication system of a comparative example. [Figure 4] FIG. 2 is a block diagram illustrating an example of a functional configuration of a communication device according to the embodiment. [Diagram 5] 4 is a block diagram showing an example of a functional configuration of a control unit according to the embodiment. FIG. [Figure 6] FIG. 2 is a diagram showing an example of a format of a data frame according to the embodiment. [Figure 7] FIG. 11 is a sequence diagram showing an example of the operation of the communication system according to the embodiment. [Figure 8] 13 is a flowchart illustrating an example of the operation of a receiving communication device according to the embodiment. [Figure 9] 13 is a flowchart illustrating an example of the operation of a transmitting communication device according to the embodiment. [Figure 10] FIG. 1 is a block diagram showing an example of a schematic configuration of a smartphone. [Figure 11] FIG. 1 is a block diagram showing an example of a schematic configuration of a car navigation device. [Figure 12] FIG. 2 is a block diagram showing an example of a schematic configuration of a wireless access point. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are denoted by the same reference numerals, and redundant description will be omitted.

[0012] The explanation will be given in the following order. 1. Overview of the communication system 2. Embodiments of the present disclosure 2-1. Functionality Overview 2-2. Example of functional configuration 2-3. Information communicated 2-4. Example of operation 3. Application Examples 4. Summary

[0013] <1. Overview of the communication system> [1-1. Communication system configuration] First, a configuration of a communication system according to an embodiment of the present disclosure will be described with reference to Fig. 1. As shown in Fig. 1, the communication system according to the present disclosure is a wireless LAN system (for example, a wireless LAN system conforming to IEEE802.11). The wireless LAN system is composed of, for example, an access point (AP) 100, which is a base station of a communication device, and a station (STA) 200, which is a child device. In addition, in the vicinity of the above-mentioned communication system, there is another system composed of an evolved node (eNB) 300, which is a base station of a communication device, and a user equipment (UE) 400, which is a child device. In Fig. 1, STA200A and STA200B exist as child devices of AP100.

[0014] The AP100 is a communication device that functions as a base station in a wireless LAN system. For example, the AP100 is connected to an external network to provide the STA200 with communication between the external network. For example, the AP100 is connected to the Internet to provide communication between the STA200 and devices on the Internet or devices connected via the Internet. The communication method, type, shape, etc. of the AP100 are not particularly limited. In addition, a range in which the AP100 can detect other communication devices is a detection range 102.

[0015] The STA200 is a communication device that functions as a child device in a wireless LAN system and communicates with the AP100. For example, the STA200 may be any device such as a display having a display function, a memory having a storage function, a keyboard and a mouse having an input function, a speaker having a sound output function, a smartphone having a function of executing advanced calculation processing, etc. The communication method, type, shape, etc. of the STA200 are not particularly limited.

[0016] The eNB300 is a communication device that functions as a base station in another system, and the UE400 is a communication device that functions as a child device in the other system. The communication method, type, shape, and the like of the eNB300 and the UE400 are not particularly limited. For example, the other system is LAA (Licensed-Assisted Access), which is a wireless communication system using a license-free frequency band established by 3GPP (3rd Generation Partnership Project), and the eNB300 and the UE400 may communicate using a communication method conforming to the LAA. In addition, the range in which the eNB300 can detect other communication devices is 302.

[0017] Basically, each communication device can only detect communication performed in another system by power. More specifically, the AP100 and the STA200 constituting the wireless LAN system can only detect communication performed by the eNB300 and the UE400 constituting the other system by power. The same can be said about the eNB300 and the UE400 constituting the other system.

[0018] [1-2. Hidden terminal problem] As shown in Fig. 2, assume that there is a communication system consisting of AP100, STA20A with a detection range of 22A, and STA20B with a detection range of 22B. In Fig. 2, STA20A and STA20B cannot detect each other, so a hidden terminal problem occurs in which frames transmitted from STA20A and STA20B to AP10 collide.

[0019] As shown in FIG. 3, communication terminals exchange RTS / CTS frames with each other as a measure against the hidden terminal problem. Specifically, before transmitting data to the AP 10, the STA 20A transmits an RTS frame 24 to the AP 10 (at time T 1 The AP 10 that receives the RTS frame 24 transmits a CTS frame 26 as a response to the other communication terminal (at time T 2 STA20A, which received the CST frame, transmits the Tx 28 (time T 3 -T 4 ). Time T 2 Now, STA20B also receives the CTS frame 26, and STA20B knows from the information in the CTS frame 26 that another communication device is occupying the channel, and sets a NAV (Network Allocation Vector). NAV is a period during which transmission is prohibited, and a communication device for which a NAV is set will suspend communication for the period of the NAV.

[0020] In addition, the hidden terminal problem may occur not only between communication terminals in the same system, but also between communication terminals in different systems. Specifically, a case where the hidden terminal problem occurs in an embodiment of the present disclosure will be described. For example, in FIG. 1, it is assumed that the STA200A of the wireless LAN system and the eNB300 of another system are in a hidden terminal relationship. That is, it is assumed that the STA200A cannot detect a signal transmitted from the eNB300, and the eNB300 cannot detect a signal transmitted from the STA200. Under this situation, a case where the STA200A transmits a signal to the AP100 is considered.

[0021] If eNB300 could recognize the CTS frame, STA200A would transmit an RTS frame to AP100 before communicating a signal by STA200A, and when AP100 receives the RTS frame and transmits a CTS frame, eNB300 would be able to appropriately wait to transmit a signal while STA200A is transmitting a signal by receiving the CTS frame.

[0022] However, since the eNB300 cannot recognize the CTS (and RTS) frame, it can only detect the power in the wireless LAN system communication. Therefore, the eNB300 may transmit a signal while the STA200A is transmitting a signal, and interference may occur between the signals, causing the AP100 to fail to receive the signal from the STA200A.

[0023] 2. Embodiments of the Present Disclosure [2-1. Functionality Overview] In an embodiment of the present disclosure, when a communication device receives data from another communication device, the communication device determines whether the data signal is addressed to itself and whether it includes a request to transmit a busy signal, and controls the process of transmitting a busy signal based on the determination result. Here, the busy signal is a signal for notifying other communication devices that the channel is in use. Specifically, when the AP100 transmits data addressed to the STA200A, the STA200A and STA200B detect the data signal. At this time, the eNB300 of the other system cannot detect the data signal.

[0024] When starting a communication connection, the AP 100, the STA 200A, and the STA 200B may write in the capability field that they are capable of performing an operation related to the transmission of a busy signal, and transmit and receive the capability field to each other. By receiving the capability field, each communication device can know that the sender of the capability field is capable of performing an operation related to a busy signal.

[0025] The STA200A and STA200B determine whether the received data signal is addressed to them. If the data signal is addressed to them, the STA200A and STA200B check whether the data signal includes a request to transmit a busy signal. If the data signal includes a request to transmit a busy signal, the STA200A and STA200B transmit a busy signal and start receiving the data signal. At this time, the eNB300 of the other system can detect the power of the busy signal transmitted by either the STA200A or the STA200B.

[0026] The functional overview of the communication device according to the embodiment of the present disclosure has been described above. Next, an example of the functional configuration of the communication device according to the embodiment of the present disclosure will be described.

[0027] [2-2. Example of functional configuration] Hereinafter, a functional configuration example of a communication device according to the present embodiment will be described with reference to Fig. 4. Fig. 4 is a block diagram showing a functional configuration example of a communication device. Note that a communication device compatible with full-duplex communication is used as the communication device according to the embodiment of the present disclosure. Full-duplex communication is a communication method in which data can be transmitted and received simultaneously from both sides. For example, a communication device compatible with full-duplex communication can transmit a busy signal to another communication device while receiving data from the other communication device.

[0028] In the following, the communication device refers to both or either of the AP100 and the STA200. Since each may have the same functional configuration, the functional configuration of the AP100 will be described below, and the functional configuration of the STA200 will be omitted. This is merely an example, and the AP100 and the STA200 may each have different functional configurations. For example, the AP100 may have a separate function for controlling multiple STA200.

[0029] As shown in FIG. 4, the AP 100 includes a communication unit 110, a data processing unit 130, a control unit 140, and a power supply unit 150.

[0030] (1) Communications Department 110 The communication unit 110 functions as a transmitter and a receiver, and has a function of transmitting and receiving an RTS frame, a CTS frame, and a data frame to and from another communication device. The communication unit 110 according to the embodiment of the present disclosure includes an antenna 111, an amplifier unit 112, a wireless interface unit 114, a signal processing unit 116, a channel estimation unit 118, and a modulation / demodulation unit 120. When the amplifier unit 112 and the wireless interface unit 114 are considered as one set, two or more sets may be provided (the figure shows an example in which two or more sets are provided). Also, the function of the amplifier unit 112 may be included in the wireless interface unit 114.

[0031] (Antenna 111) The antenna 111 has a single or multiple antenna elements, and has a function of outputting a received signal from another communication device to an amplifier unit 112, and a function of transmitting a transmission signal input from the amplifier unit 112 to another communication device.

[0032] (Amplifier section 112) The amplifier unit 112 performs a signal amplification process. More specifically, during reception, the amplifier unit 112 amplifies a received signal input from the antenna 111 to a predetermined power and outputs the signal to the wireless interface unit 114 described below. During transmission, the amplifier unit 112 amplifies a transmission signal input from the wireless interface unit 114 to a predetermined power and sends the transmission signal to the antenna 111. These functions may be realized by the wireless interface unit 114.

[0033] (Wireless interface unit 114) During reception, the radio interface unit 114 obtains a baseband signal by down-converting the received analog signal provided from the amplifier unit 112, and performs various processes such as filtering and conversion to a digital signal on the baseband signal to generate a received symbol stream, which is output to the signal processor 116 described below. During transmission, the radio interface unit 114 converts the input from the signal processor 116 to an analog signal, filters it, and up-converts it to a carrier frequency band, and sends it to the amplifier unit 112.

[0034] (Signal processing unit 116) During reception, signal processing unit 116 performs spatial processing on the received symbol streams provided from radio interface unit 114 to obtain an independent data symbol stream for each received symbol stream, and provides the obtained data symbol stream to modulation / demodulation unit 120, which will be described later. During transmission, signal processing unit 116 performs spatial processing on the data symbol streams input from modulation / demodulation unit 120, and provides the obtained one or more transmission symbol streams to each radio interface unit 114.

[0035] (Channel Estimation Unit 118) The channel estimation unit 118 calculates complex channel gain information of the propagation path from the preamble portion and the training signal portion of the received signal provided from each radio interface unit 114. The calculated complex channel gain information is used for demodulation processing in the modulation / demodulation unit 120 and spatial processing in the signal processing unit 116.

[0036] (Modem unit 120) During reception, the modem unit 120 obtains received data by demodulating, deinterleaving, and decoding the data symbol stream provided from the signal processing unit 116, and provides the received data to the data processing unit 130. During transmission, the modem unit 120 generates a data symbol stream by encoding, interleaving, and modulating the frames provided from the data processing unit 130 based on the coding and modulation scheme set by the control unit 140, which will be described later, and provides the stream to the signal processing unit 116.

[0037] (2) Data processing unit 130 During reception, the data processing unit 130 has a function of performing processing such as analyzing a MAC header for media access control (MAC) and detecting errors in a frame on the received data provided from the modem unit 120. During transmission, the data processing unit 130 generates a packet (data) for transmission, performs processing such as adding a MAC header and an error detection code to the packet to generate a frame for transmission, and provides the frame to the modem unit 120. Furthermore, the data processing unit 130 provides the control unit 140 with information from the received data that is necessary for the determination processing and transmission control processing in the control unit 140.

[0038] (3) Control unit 140 The control unit 140 has a function of controlling each of the above configurations, and performs processes such as information transfer between each of the above components, parameter setting, processing scheduling, etc. For example, the control unit 140 performs parameter setting in the modulation / demodulation unit 120 and the signal processing unit 116, and packet scheduling in the data processing unit 130. Also, for example, the control unit 140 performs parameter setting in the wireless interface unit 114 and the amplifier unit 112, and transmission power control.

[0039] In addition, in the embodiment of the present disclosure, the control unit 140 has a function of performing a determination process for controlling transmission and reception of data signals and busy signals, and controlling transmission and reception processes of each signal based on the determination results of the determination process.

[0040] In order to realize the above-mentioned functions, the control unit 140 according to the embodiment of the present disclosure includes a determination unit 142 and a signal transmission control unit 144, as shown in FIG.

[0041] (Judgment unit 142) The determination unit 142 has a function of performing a determination process for controlling transmission and reception of data signals and busy signals. The process of the determination unit 142 differs depending on whether the communication device is a data signal receiver or a data signal transmitter. The following describes the process for both the receiver and transmitter. The following describes the communication device receiving the data signal as STA200A, and the communication device transmitting the data signal as AP100.

[0042] When the communication device is the receiver of the data signal When detecting a data signal, the determination unit 242 of the STA 200A determines whether or not the STA 200A is to receive the data signal. For example, the determination unit 242 checks whether or not the data signal is addressed to itself based on information included in the data signal. If the data signal is addressed to itself, the determination unit 242 determines that the STA 200A is to receive the data signal, and provides the determination result to the signal transmission control unit 244. If the data signal is not addressed to itself, the determination unit 242 determines that the STA 200A is not to receive the data signal, and provides the determination result to the signal transmission control unit 244. Note that the determination unit 242 may perform destination determination by exchanging RTS / CTS frames before detecting the data signal.

[0043] Furthermore, the determination unit 242 performs a process of determining whether or not the STA 200 is in a position where signal transmission from the STA 200A may affect signal transmission from the AP 100. For example, the determination unit 242 checks whether or not the STA 200A detects a busy signal within a predetermined time (first time) after detecting a data signal.

[0044] Here, the predetermined time (first time) is, for example, a SIFS time. A SIFS (Short Inter Frame Space) time is the shortest waiting time in a frame transmission interval. Note that the predetermined time (first time) is not limited to a SIFS time, and may be set to any time.

[0045] When the busy signal is not detected, the determination unit 242 determines that the STA200A is located in a position where the signal transmission of the STA200A is unlikely to affect the signal transmission of the AP100, and provides the determination result to the signal transmission control unit 244. When the busy signal is detected, the determination unit 242 further determines whether the received power of the busy signal is equal to or less than a predetermined threshold. Here, the predetermined threshold is, for example, OBSS_PD defined by IEEE802.11ax. When the received power is equal to or less than OBSS_PD, the determination unit 242 determines that the STA200A is located in a position where the signal transmission of the STA200A is unlikely to affect the signal transmission of the AP100, and provides the determination result to the signal transmission control unit 244. When the received power is not equal to or less than OBSS_PD, the determination unit 242 determines that the STA200A is located in a position where the signal transmission of the STA200A is likely to affect the signal transmission of the AP100, and provides the determination result to the signal transmission control unit 244.

[0046] Furthermore, when the STA200A receives a data signal, the determination unit 242 performs a process of determining whether or not the STA200A transmits a busy signal. For example, when the STA200A detects a data signal, the determination unit 242 checks whether or not the data signal includes a request to transmit a busy signal. If the data signal includes a request to transmit a busy signal, the determination unit 242 determines that the STA200A transmits a busy signal, and provides the determination result to the signal transmission control unit 244. If the data signal does not include a request to transmit a busy signal, the determination unit 242 determines that the STA200A does not transmit a busy signal, and provides the determination result to the signal transmission control unit 244.

[0047] Furthermore, the determination unit 242 performs a determination process regarding operations after the STA200A starts receiving a data signal. For example, the determination unit 242 checks whether the STA200A has normally completed receiving the data signal. If the STA200A has normally completed receiving the data signal, the determination unit 242 determines that the STA200A will transmit an ACK to the AP100, and provides the determination result to the signal transmission control unit 244. Here, an ACK (Acknowledge) is a response for notifying the transmitting side that the data reception has been normally completed. Furthermore, if the STA200A has not normally completed receiving the data signal, the determination unit 242 determines that the STA200A will stop transmitting a busy signal, and provides the determination result to the signal transmission control unit 244.

[0048] When the communication device is the one sending the data signal The determination unit 142 of the AP 100 performs a process of determining whether or not a data signal to be transmitted needs protection by a busy signal. For example, when the data signal satisfies any one of a plurality of predetermined conditions, the determination unit 142 determines that the data signal does not need protection by a busy signal, and provides the determination result to the signal transmission control unit 144. Also, when the data signal does not satisfy any of a plurality of predetermined conditions, the determination unit 142 determines that the data signal needs protection by a busy signal, and provides the determination result to the signal transmission control unit 144.

[0049] Here, a description will be given of a plurality of predetermined conditions for determining whether or not a data signal needs to be protected by a busy signal. The plurality of predetermined conditions includes conditions 1 to 8.

[0050] Condition 1 is that the bit rate of the data signal is equal to or less than a first threshold. For example, the first threshold is the bit rate when the modulation scheme in the Modulation and Coding Scheme (MCS) is 16QAM and the coding rate is 3 / 4. Condition 2 is that the frame length of the data signal is equal to or less than a second threshold. The second threshold is, for example, 1 ms. Condition 3 is that the priority of the access category of the data signal is equal to or less than a third threshold. The third threshold is, for example, the priority when the access category is AC_BE.

[0051] Condition 4 is that the data signal is not a Fine Time Measurement (FTM) frame. Condition 5 is that the data signal is not a Null Data Packet (NDP). Condition 6 is that the data signal is not a management frame. Condition 7 is that the data signal is not an RTS / CTS frame. Condition 8 is that the data signal is not an SR PPDU (Spatial Reuse PPDU).

[0052] Furthermore, for example, when the probability that the STA 200A fails to receive the data signal is low, the determination unit 142 may determine that the data signal does not need protection by a busy signal and provide the determination result to the signal transmission control unit 144. Furthermore, for example, when the AP 100 transmits a data signal with low priority, the determination unit 142 may determine that the data signal does not need protection by a busy signal and provide the determination result to the signal transmission control unit 144.

[0053] Furthermore, the determination unit 142 performs a process of determining whether or not the STA 200A is receiving a data signal normally. For example, when the data signal is data that requires protection by a busy signal, the determination unit 142 checks whether or not the STA 200A is transmitting a busy signal. For example, when the AP 100 detects a busy signal until a predetermined time (second time) has elapsed since the AP 100 transmitted a data signal, and even after a predetermined time (third time) has elapsed, the determination unit 142 determines that the STA 200A is receiving the data signal normally, and provides the determination result to the signal transmission control unit 144. Here, the predetermined time (second time and third time) is, for example, a SIFS time. Note that the predetermined time (second time and third time) is not limited to the SIFS time, and may be set to any time. Furthermore, when the AP 100 does not detect a busy signal until the SIFS time has elapsed, and even after the SIFS time has elapsed, the determination unit 142 determines that the STA 200A is not receiving the data signal normally, and provides the determination result to the signal transmission control unit 144.

[0054] Furthermore, the determination unit 142 performs a process of determining whether or not the STA 200A has normally completed reception of the data signal. For example, the determination unit 142 checks whether or not an ACK has been received from the STA 200A after the AP 100A has completed transmission of the data signal and started transmission of a busy signal. If the AP 100 receives an ACK before the SIFS time has elapsed, the determination unit 142 determines that the STA 200A has normally completed reception of the data signal, and provides the determination result to the signal transmission control unit 144. If the AP 100 does not receive an ACK before the SIFS time has elapsed, the determination unit 142 determines that the STA 200A has not normally completed reception of the data signal, and provides the determination result to the signal transmission control unit 144.

[0055] (Signal transmission control unit 144) The signal transmission control unit 144 has a function of controlling data communication. Specifically, the signal transmission control unit 144 controls processing related to transmission and reception of data signals and busy signals, etc., based on the determination result acquired from the determination unit 142. The processing of the signal transmission control unit 144 differs depending on whether the communication device is a data signal receiving side or a data signal transmitting side. The processing for both the receiving side and the transmitting side will be described below. Also, the following description will be given assuming that the communication device receiving the data signal is STA200A, and the communication device transmitting the data signal is AP100.

[0056] When the communication device is the receiver of the data signal When the signal transmission control unit 244 of the STA 200A obtains a determination result from the determination unit 242 that the STA 200A will receive a data signal, the signal transmission control unit 244 puts the STA 200A in a state in which it can receive a data signal. When the signal transmission control unit 244 obtains a determination result from the determination unit 242 that the STA 200A will not receive a data signal, the signal transmission control unit 244 puts the STA 200A in a busy state without allowing it to receive a data signal.

[0057] Also, the signal transmission control unit 244 has acquired a determination result that the STA200A is in a position where the signal transmission of the STA200A is unlikely to affect the signal transmission of the AP100. In this case, the signal transmission control unit 244 puts the STA200A in a state where the signal transmission is possible (hereinafter also referred to as an idle state). Also, the signal transmission control unit 244 has acquired a determination result that the STA200A is in a position where the signal transmission of the STA200A is likely to affect the signal transmission of the AP100. In this case, the signal transmission control unit 244 keeps the STA200A in a busy state.

[0058] Furthermore, when the signal transmission control unit 244 obtains a determination result from the determination unit 242 that the STA200A will transmit a busy signal, the signal transmission control unit 244 causes the STA200A to transmit a busy signal and also to receive a data signal. Furthermore, when the signal transmission control unit 244 obtains a determination result from the determination unit 242 that the STA200A will not transmit a busy signal, the signal transmission control unit 244 causes the STA200A to receive a data signal without transmitting a busy signal.

[0059] Furthermore, when the signal transmission control unit 244 obtains a determination result from the determination unit 242 that the STA 200A will transmit an ACK to the AP 100, the signal transmission control unit 244 causes the STA 200A to transmit an ACK. Furthermore, when the signal transmission control unit 244 obtains a determination result from the determination unit 242 that the STA 200A will stop transmitting a busy signal, the signal transmission control unit 244 causes the STA 200A to stop transmitting the busy signal.

[0060] For example, when the STA200A is in the above-mentioned idle state, the STA200A is able to transmit data. However, when the STA200A actually transmits a signal, it is desired to avoid affecting the signal transmission of the AP100. For example, it is desired to avoid affecting the process of the AP100 receiving an ACK. Therefore, a restriction may be set on the process performed when the communication device is in the idle state. For example, a restriction on the idle state may be set based on the transmission time of the data signal, the transmission power information of the busy signal, and the transmission time information of the busy signal, which are written in the data signal received from the AP100.

[0061] Specifically, based on the above information, the time when AP100 is expected to receive ACK may be calculated, and the time that STA200A can continue the idle state may be limited according to that time, and the length of the signal that can be transmitted in the idle state may be set. Settings related to the idle state may be made so that data transmission, etc. is not performed at the timing when ACK is received. In addition, the transmission power of the signal to be transmitted in the idle state may be set based on the transmission power information of the busy signal and the reception power of the busy signal.

[0062] When the communication device is the one sending the data signal When the signal transmission control unit 144 of the AP 100 obtains a determination result from the determination unit 142 that the data signal does not need to be protected by a busy signal, the signal transmission control unit 144 causes the AP 100 to transmit a data signal without describing a request to transmit a busy signal. Also, when the signal transmission control unit 144 obtains a determination result from the determination unit 142 that the data signal needs to be protected by a busy signal, the signal transmission control unit 144 causes the AP 100 to transmit a data signal describing a request to transmit a busy signal.

[0063] When the signal transmission control unit 144 obtains a determination result from the determination unit 142 that the STA 200A is receiving the data signal normally, the signal transmission control unit 144 causes the AP 100 to continue transmitting the data signal. When the signal transmission control unit 144 obtains a determination result from the determination unit 142 that the STA 200A is not receiving the data signal normally, the signal transmission control unit 144 causes the AP 100 to stop transmitting the data signal.

[0064] Furthermore, when the signal transmission control unit 144 obtains a determination result from the determination unit 142 that the STA 200A has normally received the data signal, the signal transmission control unit 144 stops transmitting a busy signal to the AP 100. Furthermore, when the signal transmission control unit 144 obtains a determination result from the determination unit 142 that the STA 200A has not normally received the data signal, the signal transmission control unit 144 stops transmitting a busy signal to the AP 100.

[0065] (5) Power supply section 150 The power supply unit 150 is configured from a battery power source or a fixed power source, and has the function of supplying power to the communication device.

[0066] [2-3. Information communicated] Next, an example of information communicated by the AP 100 and the STA 200 will be described.

[0067] In the embodiment of the present disclosure, the information communicated between communication devices includes a data frame, a busy signal, and an ACK. Each piece of information will be specifically described below.

[0068] [2-3-1. Data frame] An example of a data frame format will be described with reference to FIG. 6. In the embodiment of the present disclosure, for example, the data frame has a "Phy Header" and "Data (MAC)". Note that the frame format is merely an example. Each format of the data frame will be described below.

[0069] (1)Phys Header The Phy Header has information defined according to the wireless LAN standard. In the embodiment of the present disclosure, for example, the Phy Header has fields such as "L-STF", "L-LTF", "L-SIG", "RL-SIG", "HE-SIG-A", "HE-STF", and "HE-LTF". Note that the format of the Phy Header is merely an example. Each field constituting the Phy Header will be described below.

[0070] The L-STF (Legacy-Short Training Field) is a field that performs synchronization processing for signal reception and is mainly used to detect wireless packet signals and timing. The L-LTF (Legacy-Long Training Field) is a field that performs synchronization processing for signal reception and is mainly used to correct errors in the carrier frequency and detect reference amplitudes. The L-SIG (Legacy-Signal Field) is a field in which information such as the length of the data contained in the data section of the frame, the transmission speed of the data section, and the modulation method is written. The RL-SIG (Repeated Legacy-Signal Field) repeatedly checks the information written in the L-SIG.

[0071] The HE-SIG-A (HE-Signal-A Field) has information about the transmission of a busy signal. For example, the HE-SIG-A further has fields such as "Busy signal request", "Busy signal transmit power", and "Busy signal duration". Note that the format of the fields is merely an example. Each field constituting the HE-SIG-A will be described below.

[0072] The Busy signal request field has information about a request to transmit a busy signal. The Busy signal transmit power field has information about the transmit power of the busy signal. The Busy signal duration field has information about the transmit time of the busy signal.

[0073] The HE-Short Training Field (HE-STF) is an STF that can be decoded by 802.11ax devices. The HE-Long Training Field (HE-LTF) is an LTF that can be decoded by 802.11ax devices.

[0074] (2) Data (MAC) Data (MAC) is a field in which data is stored.

[0075] In the embodiment of the present disclosure, the information regarding the transmission of the busy signal is stored in the HE-SIG-A field, but the location where it is stored is not particularly limited and may be stored in any location. For example, the information regarding the transmission of the busy signal may be stored in a newly extended header area after the Phy Header and before the Data, or may be stored in an existing field for storing other information. Also, for example, the information regarding the transmission of the busy signal may be stored at the beginning and end of the HE-SIG-A field, not in the middle. Also, for example, the fields storing the information regarding the transmission of the busy signal may be arranged in any order and may not be arranged consecutively.

[0076] Furthermore, when a busy signal is not transmitted, the data frame does not need to have a field for storing information regarding the transmission of a busy signal. For example, the data frame may indicate that a field is not required because a busy signal is not transmitted by setting the bits of all fields that store busy signals to 0. Note that when a busy signal is transmitted, the data frame only needs to set the bit of at least one field that stores a busy signal to 1.

[0077] [2-3-2. Busy signal] The busy signal is intended to protect the reception process of a data signal in a communication device. When a communication device receives a data signal or the like, it can notify the other communication device that the channel is in use by transmitting a busy signal to the other communication device. The other communication device that detects the busy signal can know that the channel is in use and does not transmit data or the like while it detects the busy signal. For example, when the STA200A receives a data signal from the AP100, it can protect the reception process of the data signal by transmitting a busy signal at the same time as the reception process. Also, for example, the AP100 can protect the reception process of the ACK transmitted from the STA200A by transmitting a busy signal after completing the transmission of the data signal to the STA200A.

[0078] When a communication device transmits a busy signal to another communication device, the communication device may transmit a frame having a transmission prohibition period (NAV: Network Allocation Vector) as the busy signal. Other communication devices in the same system can read the information written in the frame and set the NAV. However, communication devices in other communication systems cannot read the information written in the frame and therefore cannot set the NAV. Furthermore, communication devices in other communication systems can only detect the busy signal transmitted as a frame for an instant and therefore cannot set the NAV by detecting the received power of the busy signal.

[0079] Therefore, in order to allow communication devices in other communication systems to detect the busy signal, the communication device does not include any information in the frame and continues to transmit the busy signal for the period during which it is desired to prohibit communication devices in the other communication systems from transmitting. The communication devices in the other communication systems can continue to detect the reception power of the busy signal and can set the period during which the reception power is being detected as the NAV.

[0080] The timing of transmitting the busy signal when the AP 100 receives an ACK is not limited to immediately after transmitting the data signal, and may be any timing. For example, if it is determined that the time when the ACK is transmitted from the STA 200A is within a predetermined time (e.g., SIFS time) after the AP 100 transmits the busy signal, the AP 100 may transmit the busy signal after completing the data transmission.

[0081] Also, the AP100 may start transmitting a busy signal from the timing of receiving an ACK from the STA200A. At that time, the AP100 may perform destination determination based on information described in the ACK. However, if the AP100 receives an ACK within a time when the ACK transmission is expected, the AP100 can assume that the ACK was transmitted to the AP100, and therefore may not perform destination determination based on information described in the ACK. In that case, the AP100 may perform destination determination based on the reception power detected when the ACK is received. For example, the AP100 may determine that the ACK is addressed to itself when the reception power of the ACK is greater than a predetermined threshold. Here, the predetermined threshold is, for example, the reception power when the AP100 detects the preamble part of the IEEE802.11 standard.

[0082] If the AP 100 starts sending a busy signal without determining the destination based on the information written in the ACK, and if it finds out during transmission that the ACK is not addressed to itself, the AP 100 stops sending the busy signal.The AP 100 also stops sending the busy signal if it finds out that the ACK was not received normally.

[0083] The busy signal may also include a preamble portion of the IEEE802.11 standard communication system. The busy signal may also include information regarding the time when the AP 100 transmits a data signal, so that the IEEE802.11 standard communication device can set a NAV (transmission inhibition period). The busy signal may also include BSS identification information, so that the IEEE802.11 standard communication device can make a decision to terminate reception of the data signal.

[0084] Furthermore, the STA 200A sets the transmission time of the busy signal based on information regarding the transmission of the busy signal described in the data signal transmitted by the AP 100. The STA 200A may transmit the busy signal continuously within the set transmission time, or may transmit the busy signal intermittently according to the reception status of the data signal.

[0085] [2-3-3.ACK] When the STA200A has normally completed reception of the data signal from the AP100, the STA200A transmits an ACK to the AP100. The timing at which the STA200A transmits the ACK is not particularly limited, and the ACK may be transmitted at any timing. For example, the STA200A may transmit an ACK each time reception of data is completed in subframe units, even if the STA200A is in the middle of receiving a data signal from the AP100.

[0086] Furthermore, when transmitting an ACK, the STA 200A may transmit information indicating the reception status of the data signal, such as a signal to interference plus noise power ratio (SINR).

[0087] An example of information communicated by the AP 100 and the STA 200 according to an embodiment of the present disclosure has been described above with reference to Fig. 6. Next, an example of the operation of the communication system according to an embodiment of the present disclosure will be described.

[0088] [2-4. Example of operation] An operation example of the communication system according to an embodiment of the present disclosure will be described below. Hereinafter, an operation example of the communication system will be described with reference to FIGS.

[0089] (1) Example of communication system operation An example of the operation of the entire communication system according to an embodiment of the present disclosure will be described with reference to Fig. 7. Fig. 7 is a sequence diagram showing an example of the operation of the communication system.

[0090] The sequence diagram in Fig. 7 shows an example of the operation of AP100, STA200A, STA200B, and eNB300 when AP100 transmits data to STA200A. Note that the horizontal axis in Fig. 7 indicates time, and the vertical arrows between communication devices indicate that a signal has been transmitted to the communication device in the arrow direction.

[0091] First, the AP100 is X 30 to the STA 200A (time T 11The STA 200A that received the data signal from the AP 100 confirms that the data signal is addressed to itself and that it contains a request to transmit a busy signal, so it transmits a busy signal 32 and starts receiving the data signal (at time T 12 ) STA200B also receives a data signal from AP100, but since it confirms that the data signal is not addressed to itself, it transitions to a busy state (at time T 11 ).

[0092] The AP 100, which has received the busy signal 32 from the STA 200A, determines that the STA 200A is receiving the data signal normally and continues transmitting the data signal (time T 12 In addition, the eNB 300 detects the power of the busy signal 32 transmitted by the STA 200A and therefore transitions to a busy state (at time T 12 STA 200B does not detect the busy signal 32 even after the SIFS time has elapsed, so it transitions from the busy state to the idle state (at time T 13 ).

[0093] When the AP 100 completes the transmission of the data signal, it transmits a busy signal 36 and waits to receive an ACK 34 from the STA 200A (time T 14 STA 200B detects the busy signal 36 from AP 100 and transitions from the idle state to the busy state (at time T 14 ).

[0094] Since the STA 200A has successfully received the data signal from the AP 100, it transmits an ACK 34 to the AP 100 (at time T 15 At this time, the eNB 300 continues to be in a busy state because it has detected the power of the ACK 34 transmitted by the STA 200A (time T 15 After completing reception of the ACK 34 from the STA 200A, the AP 100 stops transmitting the busy signal 36 (at time T 16 ).

[0095] (2) Example of operation of the data receiving communication device Next, a specific determination process and operation in the data receiving communication device will be described with reference to Fig. 8. In the following, it is assumed that the receiving communication device is the SAT 200A and the transmitting communication device is the AP 100, for example.

[0096] First, when the STA 200A detects a data signal from the AP 100 (step S1000), it checks whether the data signal is addressed to itself (step S1002). If the data signal is addressed to itself (step S1002 / YES), the STA 200A checks whether the data signal includes a busy signal transmission request (step S1004). If the data signal includes a busy signal transmission request (step S1004 / YES), the STA 200A transmits a busy signal (step S1008) and starts receiving the data signal (step S1010). If the data signal does not include a busy signal transmission request (step S1004 / NO), the STA 200A starts receiving the data signal without transmitting a busy signal (step S1010).

[0097] If the STA 200A has received the data signal normally (step S1012 / YES), it transmits an ACK to the AP 100 (step S1016) and ends the process. If the STA 200A has not received the data signal normally (step S1012 / NO), it stops transmitting the busy signal (step S1020) and ends the process.

[0098] Also, if the data signal is not addressed to itself (step S1002 / NO), the STA200A does not receive the data signal and transitions to a busy state (step S1022). After that, if the STA200A detects a busy signal from another communication device until a first time has elapsed since the detection of the data signal (step S1024 / YES) and the reception power of the busy signal is not equal to or less than a predetermined threshold (step S1028 / NO), the STA200A continues the busy state. Note that, if the STA200A does not detect a busy signal from another communication device until a first time has elapsed since the detection of the data signal (step S1024 / NO), the STA200A transitions from the busy state to an idle state (step S1032). Also, if the reception power of the detected busy signal is equal to or less than a predetermined threshold (step S1028 / YES), the STA200A transitions from the busy state to an idle state (step S1032).

[0099] (3) Example of operation of data sending communication device Next, a specific determination process and operation in a data transmitting communication device will be described with reference to Fig. 9. In the following, for example, it is assumed that the transmitting communication device is AP100 and the receiving communication device is STA200A, as in the description of Fig. 8. First, AP100 transmits a data signal to STA200A (step S1100). If the data signal does not require protection by a busy signal (step S1104 / NO), AP100 completes the transmission of the data signal (step S1116).

[0100] If the data signal requires protection by a busy signal (step S1104 / YES), the AP 100 checks whether or not a busy signal is detected before the second time has elapsed (step S1108). If a busy signal is detected (step S1108 / YES), the AP 100 checks whether or not a busy signal is detected after the third time has elapsed (step S1112). If a busy signal is detected (step S1112 / YES), the AP 100 completes the transmission of the data signal (step S1116).

[0101] If the AP 100 does not detect a busy signal until the second time has elapsed since the transmission of the data signal (step S1108 / NO), the AP 100 determines that the STA 200A has not received the data signal normally, and stops the transmission of the data signal (step S1124). Similarly, if the AP 100 detects a busy signal before the second time has elapsed but does not detect a busy signal after the third time has elapsed (step S1112 / NO), the AP 100 also stops the transmission of the data signal (step S1124).

[0102] After completing the transmission of the data signal, the AP 100 transmits a busy signal to receive an ACK (step S1128). If an ACK is received (step S1132 / YES), the AP 100 determines that the STA 200A has normally received the data signal, and ends the process. If an ACK is not received (step S1132 / NO) but a predetermined time has not elapsed (step S1140 / NO), the AP 100 checks for reception of an ACK until the predetermined time has elapsed. If the predetermined time has elapsed (step S1140 / YES), the AP 100 determines that the STA 200A has not normally received the data signal, and stops transmitting the busy signal (step S1144).

[0103] An embodiment of the present disclosure has been described above with reference to Figures 1 to 9. Next, application examples of the technology according to an embodiment of the present disclosure will be described.

[0104] <3. Application Examples> The technology according to the present disclosure can be applied to various products. For example, the STA200 may be realized as a mobile terminal such as a smartphone, a tablet PC (Personal Computer), a notebook PC, a portable game terminal, or a digital camera, a fixed terminal such as a television receiver, a printer, a digital scanner, or a network storage, or an in-vehicle terminal such as a car navigation device. The STA200 may also be realized as a terminal (also called a Machine Type Communication (MTC) terminal) that performs M2M (Machine To Machine) communication, such as a smart meter, a vending machine, a remote monitoring device, or a Point Of Sale (POS) terminal. Furthermore, the STA200 may be a wireless communication module (for example, an integrated circuit module configured on one die) mounted on these terminals.

[0105] On the other hand, for example, the AP 100 may be realized as a wireless LAN access point (also called a wireless base station) with or without a router function. The AP 100 may also be realized as a mobile wireless LAN router. Furthermore, the AP 100 may be a wireless communication module (for example, an integrated circuit module configured on a single die) mounted on these devices.

[0106] [3-1. First application example] 10 is a block diagram showing an example of a schematic configuration of a smartphone 900 to which the technology according to the present disclosure can be applied. The smartphone 900 includes a processor 901, a memory 902, a storage 903, an external connection interface 904, a camera 906, a sensor 907, a microphone 908, an input device 909, a display device 910, a speaker 911, a wireless communication interface 913, an antenna switch 914, an antenna 915, a bus 917, a battery 918, and an auxiliary controller 919.

[0107] The processor 901 may be, for example, a central processing unit (CPU) or a system on chip (SoC), and controls the functions of the application layer and other layers of the smartphone 900. The memory 902 includes a random access memory (RAM) and a read only memory (ROM), and stores programs and data executed by the processor 901. The storage 903 may include a storage medium such as a semiconductor memory or a hard disk. The external connection interface 904 is an interface for connecting an external device such as a memory card or a universal serial bus (USB) device to the smartphone 900.

[0108] The camera 906 has an imaging element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) and generates a captured image. The sensor 907 may include a group of sensors such as a positioning sensor, a gyro sensor, a geomagnetic sensor, and an acceleration sensor. The microphone 908 converts a voice input to the smartphone 900 into an audio signal. The input device 909 includes, for example, a touch sensor that detects a touch on the screen of the display device 910, a keypad, a keyboard, a button, or a switch, and accepts an operation or information input from a user. The display device 910 has a screen such as a liquid crystal display (LCD) or an organic light emitting diode (OLED) display, and displays an output image of the smartphone 900. The speaker 911 converts an audio signal output from the smartphone 900 into audio.

[0109] The wireless communication interface 913 supports one or more of wireless LAN standards such as IEEE802.11a, 11b, 11g, 11n, 11ac, and 11ad, and performs wireless communication. In infrastructure mode, the wireless communication interface 913 can communicate with other devices via a wireless LAN access point. In ad-hoc mode or a direct communication mode such as Wi-Fi Direct (registered trademark), the wireless communication interface 913 can directly communicate with other devices. Note that in Wi-Fi Direct, unlike the ad-hoc mode, one of two terminals operates as an access point, but communication is performed directly between the terminals. The wireless communication interface 913 can typically include a baseband processor, an RF (Radio Frequency) circuit, a power amplifier, and the like. The wireless communication interface 913 may be a one-chip module that integrates a memory that stores a communication control program, a processor that executes the program, and related circuits. In addition to the wireless LAN system, the wireless communication interface 913 may support other types of wireless communication systems such as a short-distance wireless communication system, a close-proximity wireless communication system, or a cellular communication system. The antenna switch 914 switches the connection destination of the antenna 915 between multiple circuits (e.g., circuits for different wireless communication methods) included in the wireless communication interface 913. The antenna 915 has a single or multiple antenna elements (e.g., multiple antenna elements constituting a MIMO antenna) and is used for transmitting and receiving wireless signals by the wireless communication interface 913.

[0110] 10, the smartphone 900 may include multiple antennas (for example, an antenna for a wireless LAN and an antenna for a close-proximity wireless communication system, etc.). In that case, the antenna switch 914 may be omitted from the configuration of the smartphone 900.

[0111] The bus 917 connects the processor 901, the memory 902, the storage 903, the external connection interface 904, the camera 906, the sensor 907, the microphone 908, the input device 909, the display device 910, the speaker 911, the wireless communication interface 913, and the auxiliary controller 919 to one another. The battery 918 supplies power to each block of the smartphone 900 shown in Fig. 10 via a power supply line partially indicated by a dashed line in the figure. The auxiliary controller 919 operates the minimum necessary functions of the smartphone 900, for example, in a sleep mode.

[0112] The smartphone 900 may operate as a wireless access point (software AP) by the processor 901 executing an access point function at an application level. The wireless communication interface 913 may have a wireless access point function.

[0113] [3-2. Second application example] 11 is a block diagram showing an example of a schematic configuration of a car navigation device 920 to which the technology according to the present disclosure can be applied. The car navigation device 920 includes a processor 921, a memory 922, a GPS (Global Positioning System) module 924, a sensor 925, a data interface 926, a content player 927, a storage medium interface 928, an input device 929, a display device 930, a speaker 931, a wireless communication interface 933, an antenna switch 934, an antenna 935, and a battery 938.

[0114] The processor 921 may be, for example, a CPU or an SoC, and controls the navigation function and other functions of the car navigation device 920. The memory 922 includes a RAM and a ROM, and stores programs executed by the processor 921 and data.

[0115] The GPS module 924 measures the position (e.g., latitude, longitude, and altitude) of the car navigation device 920 using GPS signals received from GPS satellites. The sensor 925 may include a group of sensors such as a gyro sensor, a geomagnetic sensor, and an air pressure sensor. The data interface 926 is connected to the in-vehicle network 941 via a terminal (not shown), for example, and acquires data generated on the vehicle side, such as vehicle speed data.

[0116] The content player 927 plays content stored on a storage medium (e.g., a CD or DVD) inserted into the storage medium interface 928. The input device 929 includes, for example, a touch sensor, a button, or a switch that detects a touch on the screen of the display device 930, and accepts operations or information input from the user. The display device 930 has a screen such as an LCD or OLED display, and displays images of the navigation function or the content to be played. The speaker 931 outputs the sound of the navigation function or the content to be played.

[0117] The wireless communication interface 933 supports one or more of wireless LAN standards such as IEEE802.11a, 11b, 11g, 11n, 11ac, and 11ad, and performs wireless communication. In infrastructure mode, the wireless communication interface 933 may communicate with other devices via a wireless LAN access point. In ad-hoc mode or a direct communication mode such as Wi-Fi Direct, the wireless communication interface 933 may directly communicate with other devices. The wireless communication interface 933 may typically include a baseband processor, an RF circuit, a power amplifier, and the like. The wireless communication interface 933 may be a one-chip module that integrates a memory that stores a communication control program, a processor that executes the program, and related circuits. In addition to the wireless LAN system, the wireless communication interface 933 may support other types of wireless communication systems such as a short-distance wireless communication system, a close-proximity wireless communication system, or a cellular communication system. The antenna switch 934 switches the connection destination of the antenna 935 among multiple circuits included in the wireless communication interface 933. The antenna 935 may have a single or multiple antenna elements and is used for transmitting and receiving radio signals via the wireless communication interface 933 .

[0118] 11, the car navigation device 920 may include a plurality of antennas. In that case, the antenna switch 934 may be omitted from the configuration of the car navigation device 920.

[0119] The battery 938 supplies power to each block of the car navigation device 920 shown in Fig. 11 via a power supply line partially indicated by a dashed line in the figure. The battery 938 also stores power supplied from the vehicle side.

[0120] Furthermore, the wireless communication interface 933 may operate as the AP 100 described above and provide wireless connection to a terminal owned by a user in a vehicle.

[0121] Furthermore, the technology according to the present disclosure may be realized as an in-vehicle system (or vehicle) 940 including one or more blocks of the above-mentioned car navigation device 920, an in-vehicle network 941, and a vehicle-side module 942. The vehicle-side module 942 generates vehicle-side data such as vehicle speed, engine RPM, or failure information, and outputs the generated data to the in-vehicle network 941.

[0122] [3-3.Third application example] 12 is a block diagram showing an example of a schematic configuration of a wireless access point 950 to which the technology of the present disclosure can be applied. The wireless access point 950 includes a controller 951, a memory 952, an input device 954, a display device 955, a network interface 957, a wireless communication interface 963, an antenna switch 964, and an antenna 965.

[0123] The controller 951 may be, for example, a CPU or a DSP (Digital Signal Processor), and operates various functions (e.g., access restriction, routing, encryption, firewall, log management, etc.) of the IP (Internet Protocol) layer and higher layers of the wireless access point 950. The memory 952 includes a RAM and a ROM, and stores programs executed by the controller 951 and various control data (e.g., a terminal list, a routing table, an encryption key, security settings, logs, etc.).

[0124] The input device 954 includes, for example, a button or a switch, and receives operations from a user. The display device 955 includes, for example, an LED lamp, and displays the operation status of the wireless access point 950.

[0125] The network interface 957 is a wired communication interface for connecting the wireless access point 950 to a wired communication network 958. The network interface 957 may have a plurality of connection terminals. The wired communication network 958 may be a LAN such as Ethernet (registered trademark) or may be a Wide Area Network (WAN).

[0126] The wireless communication interface 963 supports one or more of wireless LAN standards such as IEEE802.11a, 11b, 11g, 11n, 11ac, and 11ad, and provides wireless connection to nearby terminals as an access point. The wireless communication interface 963 may typically include a baseband processor, an RF circuit, a power amplifier, and the like. The wireless communication interface 963 may be a one-chip module that integrates a memory that stores a communication control program, a processor that executes the program, and related circuits. The antenna switch 964 switches the connection destination of the antenna 965 among multiple circuits included in the wireless communication interface 963. The antenna 965 has a single or multiple antenna elements and is used for transmitting and receiving wireless signals by the wireless communication interface 963.

[0127] <4. Summary> As described above, the communication device according to the present disclosure can more efficiently avoid the hidden terminal problem. As a result, it is possible to provide a new and improved communication device and communication system that can more efficiently avoid the hidden terminal problem.

[0128] Although the preferred embodiment of the present disclosure has been described in detail above with reference to the attached drawings, the technical scope of the present disclosure is not limited to such examples. It is clear that a person having ordinary knowledge in the technical field of the present disclosure can conceive of various modified or amended examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure.

[0129] Furthermore, the series of processes performed by each device described in this specification may be realized using any of software, hardware, and a combination of software and hardware. The programs constituting the software are stored in advance, for example, in a recording medium (non-transitory medium) provided inside or outside each device. Then, each program is loaded into a RAM when executed by a computer, and executed by a processor such as a CPU.

[0130] In addition, the processes described in this specification using flowcharts and sequence diagrams do not necessarily have to be performed in the order shown in the drawings. Some processing steps may be performed in parallel. In addition, additional processing steps may be employed, and some processing steps may be omitted.

[0131] In addition, the effects described in this specification are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to a person skilled in the art from the description of this specification, in addition to or in place of the above effects.

[0132] Note that the following configurations also fall within the technical scope of the present disclosure. (1) a communication unit that transmits, to another communication device, a data signal including a transmission request for a busy signal, which is a signal containing no information and indicates that the channel is in use when a predetermined condition is satisfied; a determination unit that determines whether the other communication device that has received the data signal transmitted by the communication unit is transmitting the busy signal; a control unit that controls a process of transmitting the data signal to the other communication device in accordance with a determination result of the determination unit; Equipped with The control unit is After completing the transmission of the data signal, transmit the busy signal; controlling the communication unit to stop transmitting the busy signal if no ACK is received within a predetermined time from the start of transmission of the busy signal; Communications equipment. (2) the determination unit determines that the other communication device is normally receiving the data signal when the communication unit receives the busy signal; The communication device according to (1), wherein the control unit causes the communication unit to continue transmitting the data signal. (3) the determination unit determines that the other communication device has not normally received the data signal when the communication unit has not received the busy signal until a second time has elapsed since the communication unit started transmitting the data signal; The communication device according to any one of (1) and (2), wherein the control unit causes the communication unit to stop transmitting the data signal. (4) the determination unit determines that the other communication device has not normally received the data signal when the communication unit has not received the busy signal after a third time has elapsed since the communication unit started transmitting the data signal; The communication device according to any one of (1) to (3), wherein the control unit causes the communication unit to stop transmitting the data signal. (5) The communication device according to any one of (1) to (4), wherein the control unit transmits the busy signal after completing transmission of the data signal. (6) The communication device according to any one of (1) to (5), wherein the control unit controls the communication unit to transmit the data signal that does not include a request to transmit the busy signal when the data signal satisfies a predetermined condition. (7) The communication device according to any one of (1) to (6), wherein the communication device is a terminal that supports full-duplex communication. [Explanation of symbols]

[0133] 100 AP 110 Communications Department 111 Antenna 112 Amplifier section 114 Wireless Interface Unit 116 Signal Processing Section 118 Channel Estimation Unit 120 Modulation and demodulation section 130 Data Processing Unit 140 Control section 142 Judgment section 144 Signal transmission control section 150 Power supply section 200 STA

Claims

1. a communication unit that transmits, to another communication device, a data signal including a transmission request for a busy signal, which is a signal containing no information and indicates that the channel is in use when a predetermined condition is satisfied; a determination unit that determines whether the other communication device that has received the data signal transmitted by the communication unit is transmitting the busy signal; a control unit that controls a process of transmitting the data signal to the other communication device in accordance with a determination result of the determination unit; Equipped with The control unit is After completing the transmission of the data signal, transmit the busy signal; controlling the communication unit to stop transmitting the busy signal when an ACK is not received within a predetermined time from the start of transmission of the busy signal; Communications equipment.

2. the determination unit determines that the other communication device is normally receiving the data signal when the communication unit receives the busy signal; The communication device according to claim 1 , wherein the control unit causes the communication unit to continue transmitting the data signal.

3. the determination unit determines that the other communication device has not normally received the data signal when the communication unit has not received the busy signal until a second time has elapsed since the communication unit started transmitting the data signal; The communication device according to claim 1 , wherein the control unit causes the communication unit to stop transmitting the data signal.

4. the determination unit determines that the other communication device has not normally received the data signal when the communication unit has not received the busy signal after a third time has elapsed since the communication unit started transmitting the data signal, The communication device according to claim 1 , wherein the control unit causes the communication unit to stop transmitting the data signal.

5. The communication device according to claim 1 , wherein the control unit transmits the busy signal after completing transmission of the data signal.

6. The communication device according to claim 1 , wherein the control unit controls the communication unit to transmit the data signal that does not include a transmission request for the busy signal when the data signal satisfies a predetermined condition.

7. The communication device according to claim 1 , wherein the communication device is a terminal capable of full-duplex communication.

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