Access point and terminal device

Abstract

A terminal device according to the embodiments includes a communication circuit and a processor. The communication circuit is configured to transmit and receive wireless signals. The processor is configured to establish a wireless link with an access point using the communication circuit and, during periods allocated to Peer-to-Peer (P2P) communication by a pair of terminal devices that have established a wireless link with the access point, to prohibit transmission of wireless signals for a first period of time when inside a communication area of one terminal device of the pair of terminal devices but to not prohibit transmission when outside the communication area of the one terminal device.

Description

Access point and terminal device

[0001] The embodiments relate to an access point and a terminal device.

[0002] A wireless local area network (LAN) is known as a communication system that wirelessly connects an access point and a terminal device. By using a wireless LAN, the terminal device can access a network via the access point.

[0003] In a wireless LAN, an access point may support a Peer-to-Peer (P2P) communication method. In P2P communication, a terminal device can communicate directly with another terminal device without going through an access point. In order to improve communication stability between paired terminal devices that are the target of P2P communication, it is preferable that, during a period in which P2P communication is being performed, other terminal devices that are not the target of P2P communication be prohibited from sending or receiving data frames, etc.

[0004] IEEE P802.11beTM Draft4.1, “35.2.1 TXOP, 35.2.1.2 Triggered TXOP sharing procedure”, p491-p495, September 2023

[0005] However, during a period in which P2P communication is being performed, terminal devices that are not the target of P2P communication may not be affected by the P2P communication. If such terminal devices are in a standby state during a period in which P2P communication is being performed, this may cause a decrease in communication efficiency.

[0006] The present invention has been made in light of the above circumstances, and its purpose is to provide an access point and a terminal device that can improve the communication efficiency of a terminal device in P2P communication without being affected by the paired terminal device that is the target of the P2P communication.

[0007] In an embodiment, a terminal device includes a communication circuit and a processor. The communication circuit is configured to transmit and receive wireless signals. The processor is configured to establish a wireless link with an access point using the communication circuit. The processor is further configured to prohibit transmission of wireless signals for a first time period when the terminal device is within a communication area of ​​one of the paired terminal devices and not prohibit transmission when the terminal device is outside the communication area of ​​the other terminal device during a time period allocated for peer-to-peer (P2P) communication between the paired terminal devices that have established the wireless link with the access point.

[0008] According to the embodiment, it is possible to provide an access point and a terminal device that can improve the communication efficiency of a terminal device in P2P communication without being affected by a pair of terminal devices that are the target of P2P communication.

[0009] FIG. 1 is a block diagram showing an example of the overall configuration of a communication system according to an embodiment. FIG. 2 is a block diagram showing an example of the hardware configuration of an access point included in the communication system according to an embodiment. FIG. 3 is a block diagram showing an example of the functional configuration of an access point included in the communication system according to an embodiment. FIG. 4 is a block diagram showing an example of the hardware configuration of a terminal device included in the communication system according to an embodiment. FIG. 5 is a block diagram showing an example of the functional configuration of a terminal device included in the communication system according to an embodiment. FIG. 6 is a flowchart showing an example of the operation of an access point included in the communication system according to an embodiment. FIG. 7 is a block diagram showing an example of the format of a P2P communication start frame used in the communication system according to an embodiment. FIG. 8 is a flowchart showing an example of the operation of a terminal device included in the communication system according to an embodiment. FIG. 9 is a schematic diagram for explaining a specific example of P2P communication in the communication system according to an embodiment. FIG. 10 is a timing chart showing an example of a sequence of P2P communication in the communication system according to an embodiment.

[0010] A communication system according to an embodiment will be described below with reference to the drawings. The embodiments illustrate devices and methods for embodying the technical ideas of the invention. The drawings are schematic or conceptual. In this specification, the same reference numerals are assigned to components having substantially the same functions and configurations. Numbers following letters constituting a reference numeral are used to distinguish between elements that are referred to by reference numerals containing the same letters and that have similar configurations. When there is no need to distinguish between elements indicated by reference numerals containing the same letters, these elements are referred to by reference numerals containing only letters.

[0011] <1> Configuration First, the configuration of a communication system 1 according to the embodiment will be described.

[0012] <1-1> Overall Configuration of Communication System 1 Fig. 1 is a block diagram showing an example of the overall configuration of a communication system 1 according to an embodiment. As shown in Fig. 1, the communication system 1 includes, for example, an access point AP and multiple terminal devices STA. In this example, two terminal devices STA1 and STA2 are wirelessly connected to the access point AP.

[0013] An access point AP is a base station of a wireless LAN. The access point AP is configured to establish links with multiple terminal devices (STAs) and to be able to communicate wirelessly with each of the terminal devices STAs with which the link is established. The access point AP is also connected to a network NW and is configured to be able to communicate with a server (not shown) on the network NW. The access point AP and the network NW may be connected wirelessly or by wire. Furthermore, the access point AP supports peer-to-peer (P2P) communication between paired terminal devices STAs included in the multiple terminal devices STAs belonging to the access point AP.

[0014] The terminal device STA is a wireless terminal such as a smartphone or a PC (Personal Computer). The terminal device STA is configured to be able to communicate with a server (not shown) on a network NW via a wirelessly connected access point AP. When P2P communication is performed, a pair of terminal devices STA is set by the access point AP. In P2P communication, one of the pair of terminal devices STA can communicate directly with the other terminal device STA. For example, a terminal device STA1 can communicate with a terminal device STA2 based on an instruction from the access point AP without going through the access point AP.

[0015] In the embodiment, when the access point AP causes a paired terminal apparatus STA to perform P2P communication, the access point AP secures a communication period for P2P communication (hereinafter referred to as a "P2P communication period"). A P2P communication method that secures a P2P communication period in this manner is called, for example, Triggered TXOP sharing. A frame for starting Triggered TXOP sharing is, for example, a trigger frame such as MU-RTS_TXS_TF. During the P2P communication period, the paired terminal apparatus STA is suppressed from being affected by other terminal apparatuses STA, and can directly transmit and receive data frames and the like without going through the access point AP.

[0016] The wireless communication between the access point AP and the terminal device STA complies with, for example, the IEEE 802.11 standard. The IEEE 802.11 standard has a wireless communication function based on the OSI (Open Systems Interconnection) reference model. In the OSI reference model, the wireless communication function is divided into seven layers (Layer 1: Physical Layer, Layer 2: Data Link Layer, Layer 3: Network Layer, Layer 4: Transport Layer, Layer 5: Session Layer, Layer 6: Presentation Layer, and Layer 7: Application Layer). The data link layer includes a Logical Link Control (LLC) sublayer and a Media Access Control (MAC) sublayer. The LLC sublayer forms LLC packets by adding a Destination Service Access Point (DSAP) header, a Source Service Access Point (SSAP) header, etc. to data input from an upper application. The MAC layer forms MAC frames by adding a MAC header to the LLC packets. In this specification, the processing for the MAC sublayer of the first and second layers will be mainly described, and the processing for other layers will not be described.

[0017] <1-2> Configuration of Access Point AP The configuration of the access point AP will be described below.

[0018] 2 is a block diagram showing an example of the hardware configuration of the access point AP included in the communication system 1 according to the embodiment. As shown in FIG. 2, the access point AP includes, for example, a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, a wireless communication module 14, and a wired communication module 15.

[0019] The CPU 11 is an integrated circuit capable of executing various programs and controls the overall operation of the access point AP. The ROM 12 is, for example, a non-volatile semiconductor memory that stores programs and control data for controlling the access point AP. The RAM 13 is, for example, a volatile semiconductor memory that is used as a work area for the CPU 11. The wireless communication module 14 is configured to be able to send and receive wireless signals via an antenna and is a communication circuit used to send and receive data, etc., with the terminal device STA. The wired communication module 15 is a communication circuit used to send and receive data, etc., via wired signals and is configured to be connectable to the network NW.

[0020] The access point AP may have other hardware configurations. For example, the access point AP may be wirelessly connected to the network NW. In this case, the wired communication module 15 may be omitted from the access point AP. The antenna may be built into the access point AP or may be externally connected.

[0021] <1-2-2> Functional Configuration of Access Point AP Fig. 3 is a block diagram showing an example of the functional configuration of an access point AP included in the communication system 1 according to the embodiment. As shown in Fig. 3, the access point AP includes, for example, an LLC processing unit 110, a link management unit 120, a frame processing unit 130, and a transceiver unit 140. The LLC processing unit 110 performs processing of the LLC sublayer of layer 2 and layers 3 to 7. The link management unit 120, the frame processing unit 130, and the transceiver unit 140 perform processing of the MAC sublayer of layer 2. The transceiver unit 140 also performs processing of layer 1.

[0022] The LLC processing unit 110 generates LLC packets by adding DSAP headers, SSAP headers, etc. to data received from the network NW. The LLC processing unit 110 then inputs the generated LLC packets to the frame processing unit 130. The LLC processing unit 110 also extracts data from the LLC packets input from the frame processing unit 130. The LLC processing unit 110 then transmits the extracted data to the network NW.

[0023] The link management unit 120 manages the status of links between the access point AP and multiple terminal devices STA. The link management unit 120 can perform association processing and authentication processing in response to a connection request from a terminal device STA. The link management unit 120 also manages information related to P2P communication. MAC frames including information related to links and information related to P2P communication can be input and output between the link management unit 120 and the frame processing unit 130.

[0024] Frame processing unit 130 generates a MAC frame by adding a MAC header to the LLC packet input from LLC processing unit 110. Frame processing unit 130 then outputs the generated MAC frame to transceiver unit 140. Furthermore, frame processing unit 130 outputs the MAC frame input from transceiver unit 140 to either LLC processing unit 110 or link management unit 120, depending on the type of MAC frame. Frame processing unit 130 may also output an LLC packet extracted from the MAC frame to LLC processing unit 110, etc.

[0025] The transceiver 140 is configured to transmit and receive wireless signals using an enhanced distributed channel access (EDCA) mechanism. Specifically, the transceiver 140 performs carrier sense based on carrier sense multiple access with collision avoidance (CSMA / CA) according to preset access parameters. In carrier sense, acquisition of a transmission right is suspended when the channel state is busy, and the transmission right for a MAC frame is acquired when the channel state remains idle for a predetermined period of time. When transmitting a MAC frame, the transceiver 140 generates a wireless frame by adding a preamble or the like to the MAC frame input from the frame processing unit 130. The transceiver 140 then converts the generated wireless frame into a wireless signal (wireless medium) and radiates (transmits) it via an antenna. The transceiver 140 may also transmit a trigger frame for upstream traffic communication. The transceiver 140 also converts a wireless signal received via the antenna into a wireless frame. Then, the transmitting / receiving unit 140 extracts the MAC frame from the converted wireless frame and outputs it to the frame processing unit 130 .

[0026] In the communication system 1, access parameters are set for each access category. Examples of access categories include "VO (Voice)," "VI (Video)," "BE (Best Effort)," and "BK (Background)." Examples of access parameters used in carrier sensing include CW (contention window) min, CWmax, AIFS (arbitration interframe space), and TXOP (transmission opportunity) limit. The contention window is a parameter used to determine the transmission waiting time for collision avoidance. CWmin and CWmax correspond to the minimum and maximum values ​​of the contention window, respectively. AIFS (arbitration interframe space) corresponds to a fixed transmission waiting time set for each access category for collision avoidance control with a priority control function. TXOP corresponds to the channel occupation time. TXOPLimit corresponds to the upper limit of TXOP. The shorter the CWmin and CWmax are, the easier it is for each link to obtain the transmission right. The smaller the AIFS is, the higher the priority of each link is. The larger the value of TXOPLimit is, the larger the amount of data transmitted with one transmission right is. The access parameters are set, for example, so that the transmission of radio signals is prioritized in the order of "VO", "VI", "BE", and "BK". The access parameters may also be called EDCA parameters.

[0027] <1-3> Configuration of the Station STA The configuration of the station STA will be described below.

[0028] <1-3-1> Hardware Configuration of Terminal Device STA Fig. 4 is a block diagram showing an example of the hardware configuration of terminal device STA included in communication system 1 according to an embodiment. As shown in Fig. 4, terminal device STA includes, for example, a CPU 21, a ROM 22, a RAM 23, a wireless communication module 24, a display 25, and a storage 26.

[0029] The CPU 21 is an integrated circuit capable of executing various programs and controls the overall operation of the terminal device STA. The ROM 22 is, for example, a non-volatile semiconductor memory and stores programs and control data for controlling the terminal device STA. The RAM 23 is, for example, a volatile semiconductor memory and is used as a work area for the CPU 21. The wireless communication module 24 is configured to be able to send and receive wireless signals via an antenna and is a communication circuit used to send and receive data to and from the access point AP. The display 25 displays, for example, a graphical user interface (GUI) corresponding to application software. The storage 26 is a non-volatile storage device and stores, for example, system software for the terminal device STA.

[0030] The terminal apparatus STA may have other hardware configurations. For example, if the terminal apparatus STA is an IoT (Internet of Things) terminal or the like, the display 25 may be omitted from the terminal apparatus STA. The display 25 may have a function as an input interface for the terminal apparatus STA. The antenna may be built into the terminal apparatus STA or may be externally connected.

[0031] <1-3-2> Functional Configuration of the Terminal Device STA FIG. 5 is a block diagram showing an example of the functional configuration of the terminal device STA included in the communication system 1 according to the embodiment. As shown in FIG. 5, the terminal device STA includes, for example, an application execution unit 200, an LLC processing unit 210, a link management unit 220, a frame processing unit 230, and a transceiver unit 240. The application execution unit 200 performs processing corresponding to layer 7. The LLC processing unit 210 performs processing for the LLC sublayer of layer 2 and layers 3 to 7. The link management unit 220, frame processing unit 230, and transceiver unit 240 perform processing for the MAC sublayer of layer 2. The transceiver unit 240 also performs processing for layer 1.

[0032] The application execution unit 200 executes an application based on data input from the LLC processing unit 210. The application execution unit 200 also inputs data to the LLC processing unit 210. For example, the application execution unit 200 can display application information on the display 25. The application execution unit 200 can also operate based on operations on an input interface.

[0033] The LLC processing unit 210 generates LLC packets by adding DSAP headers, SSAP headers, etc. to data received from the network NW. The LLC processing unit 210 then inputs the generated LLC packets to the frame processing unit 230. The LLC processing unit 210 also extracts data from the LLC packets input from the frame processing unit 230. The LLC processing unit 210 then transmits the extracted data to the application execution unit 200.

[0034] The link management unit 220 manages the status of the link with the access point AP, etc. The link management unit 220 can send a connection request to the access point AP and execute association processing and authentication processing. The link management unit 220 also manages information related to P2P communication. The information related to P2P communication includes, for example, information related to the paired terminal device STA that is the target of the P2P communication, and information related to the start time and duration of the period allocated to the P2P communication. MAC frames including information related to the link, etc. and information related to the P2P communication can be input and output between the link management unit 220 and the frame processing unit 230.

[0035] Frame processing unit 230 generates a MAC frame by adding a MAC header to the LLC packet input from LLC processing unit 210. Frame processing unit 230 then outputs the generated MAC frame to transceiver unit 240. Furthermore, frame processing unit 230 outputs the MAC frame input from transceiver unit 240 to either LLC processing unit 210 or link management unit 220, depending on the type of MAC frame. Frame processing unit 230 may output an LLC packet extracted from the MAC frame to LLC processing unit 210 or the like.

[0036] The transceiver 240 is configured to be able to transmit and receive wireless signals using the EDCA mechanism. Specifically, the transceiver 240 performs carrier sense based on CSMA / CA in accordance with preset access parameters. When transmitting a MAC frame, the transceiver 240 generates a wireless frame by adding a preamble or the like to the MAC frame input from the frame processor 230. The transceiver 240 then converts the generated wireless frame into a wireless signal (wireless medium) and radiates (transmits) it via an antenna. The transceiver 240 also converts a wireless signal received via the antenna into a wireless frame. The transceiver 240 then extracts the MAC frame from the converted wireless frame and outputs it to the frame processor 230.

[0037] <2> Operation Next, the operation of the communication system 1 according to the embodiment will be described.

[0038] 6 is a flowchart showing an example of the operation of the access point AP included in the communication system 1 according to the embodiment. For example, when the access point AP receives a P2P communication request from a terminal device STA, the access point AP starts the series of operations shown in FIG. 6 (start).

[0039] First, the access point AP schedules P2P communication based on a P2P communication request (step S11). At this time, the access point AP sets a pair of terminal devices STA that will execute the P2P communication, and the start time and duration of a period to be allocated for the P2P communication (P2P communication period).

[0040] Next, the access point AP generates a P2P communication start frame based on the P2P communication schedule (step S12). The P2P communication start frame includes information on the paired terminal apparatus STA that is the target of the P2P communication, and information on the start time and duration of the P2P communication period. The P2P communication start frame is, for example, a trigger frame such as MU-RTS_TXS_TF. The P2P communication start frame may include information on the terminal apparatus STA that is to be prohibited from transmitting during the P2P communication period, and information on the start time and duration of the transmission prohibition for that terminal apparatus STA.

[0041] Next, the access point AP transmits a P2P communication initiation frame (step S13). The transmitted P2P communication initiation frame can be received by each terminal apparatus STA within the communication area of ​​the access point AP. That is, the P2P communication initiation frame is also transmitted to terminal apparatuses STA that are not P2P communication targets. Terminal apparatuses STA that are not P2P communication targets set a transmission prohibition period for themselves, for example, based on P2P communication period information acquired from the P2P communication initiation frame.

[0042] Next, the access point AP receives a response frame from, for example, the terminal apparatus STA that is the data sender of the pair of terminal apparatuses STA with which the P2P communication is to be performed (step S14). This response frame indicates that the pair of terminal apparatuses STA with which the P2P communication is to be performed is capable of performing P2P communication.

[0043] Next, the access point AP waits for the P2P communication period to elapse (step S15). During the P2P communication period, the access point AP may communicate data with a terminal apparatus STA that is not a target of P2P communication and that has voluntarily released the transmission prohibition. Such a terminal apparatus STA is located within the communication area of ​​the access point AP but outside the communication area of ​​the target terminal apparatus STA of P2P communication. The sequence in which the terminal apparatus STA voluntarily releases the transmission prohibition will be described later. After that, when the P2P communication period ends, the access point AP ends the series of processes shown in FIG. 6 (END).

[0044] 7 is a block diagram showing an example of the format of a P2P communication initiation frame used in the communication system 1 according to the embodiment. As shown in Fig. 7, the P2P communication initiation frame includes, for example, a frame control field, a duration field, address fields (RA and TA), a common information field, a user information list field, a padding field, and an FCS (Frame check sequence) field.

[0045] The frame control field stores various control information. The frame control field contains, for example, information indicating the frame type of the wireless frame. The duration field contains information indicating the planned period for using the wireless line. The address field contains information indicating the BSSID (Basic service set identifier), source address, destination address, sender terminal address, receiver terminal address, etc. The common information field contains information such as the trigger frame type. The user information list field contains information related to P2P communication. The padding is an area for adjusting the data length of the wireless frame. The FCS field stores an error detection code for the MAC header and frame body field pair, and is used to determine whether or not there is an error in the data frame.

[0046] The user information list field includes, for example, an association identifier (AID), a resource unit allocation (RU allocation), and an allocation duration. The AID includes information indicating an identifier of a terminal device STA associated with P2P communication. The RU allocation includes information regarding resources allocated to the associated AID. The allocation duration includes information related to the P2P communication duration. For example, based on the content of the user information list field, the terminal device STA can determine whether it is a device that transmits data frames in P2P communication, a device that receives data frames, or a device that is not a target of P2P communication. Furthermore, the terminal device STA can set the P2P communication duration based on the content of the user information list field.

[0047] Furthermore, when a terminal apparatus STA is not a target of P2P communication, the terminal apparatus STA may set itself to transmission prohibition during the P2P communication period, for example, based on the contents of the user information list field. The transmission prohibition may be set by setting the allocation of communication resources (frequency, transmission timing, period, etc.) to the terminal apparatus STA to zero. The transmission prohibition may also be set by the access point AP transmitting a transmission prohibition frame to the terminal apparatus STA to be prohibited from transmission. The period during which the terminal apparatus STA is prohibited from transmission is also called a NAV (Network Allocation Vector).

[0048] In the communication system 1 according to the embodiment, the NAV is set to overlap the entire P2P communication period, for example. This is not limiting, and the NAV set for a terminal device STA that is not a target of P2P communication during the P2P communication period may be set to be shorter than the entire P2P communication period. Furthermore, the NAV set for a terminal device STA that is not a target of P2P communication during the P2P communication period may be set to be longer than the entire P2P communication period, for example, to cover the time required for retransmission processing estimated in the event of P2P communication failure for some reason. In other words, the time for which the NAV is set may be equal to or longer than the length of the P2P communication period. When the NAV is set to the same length as the P2P communication period when P2P communication is performed, information indicating the start time and duration of the NAV may be omitted from the P2P communication start frame. The NAV may also be set based on channel occupation time information stored in the RTS / CTS packet.

[0049] 8 is a flowchart showing an example of the operation of the terminal apparatus STA included in the communication system 1 according to the embodiment. For example, when the terminal apparatus STA receives a P2P communication start frame, the terminal apparatus STA starts the series of operations shown in FIG. 8 (start).

[0050] First, the terminal apparatus STA checks whether it is a terminal apparatus STA that is a target of P2P communication (step S21). The terminal apparatus STA can check whether it is a target of P2P communication by, for example, referring to the user information list in the P2P communication start frame.

[0051] In the process of step S21, if the terminal apparatus STA has confirmed that it is the terminal apparatus STA with which P2P communication is to be performed (step S21: YES), the terminal apparatus STA proceeds to the process of step S22. In this case, the terminal apparatus STA is located within the communication area of ​​the access point AP and within the communication area of ​​the other terminal apparatus STA with which P2P communication is to be performed.

[0052] In the process of step S21, if it is confirmed that the terminal apparatus STA is not the terminal apparatus STA with which P2P communication is to be performed (step S21: NO), the terminal apparatus STA proceeds to the process of step S25. In this case, the terminal apparatus STA is located within the communication area of ​​the access point AP and within the communication area of ​​the terminal apparatus STA with which P2P communication is to be performed, or within the communication area of ​​the access point AP and outside the communication area of ​​the terminal apparatus STA with which P2P communication is to be performed.

[0053] (Operation of the terminal apparatus STA that is the target of P2P communication) In the process of step S22, the terminal apparatus STA checks whether it is the terminal apparatus STA that is the data sender. The terminal apparatus STA can check whether it is the terminal apparatus STA that is the target of P2P communication and the sender by, for example, referring to the user information list in the P2P communication start frame.

[0054] In the process of step S22, if the terminal apparatus STA has confirmed that it is the terminal apparatus STA that is sending data (step S22: YES), the terminal apparatus STA proceeds to the process of step S23. In the process of step S22, if the terminal apparatus STA has confirmed that it is not the terminal apparatus STA that is sending data (step S22: NO), the terminal apparatus STA proceeds to the process of step S24.

[0055] In the process of step S23, the terminal apparatus STA transmits a response frame to the P2P communication start frame to the access point AP. The response frame is, for example, a CTS (Clear To Send) frame. After the process of step S23 is completed, the terminal apparatus STA proceeds to the process of step S24.

[0056] In the process of step S24, the terminal apparatus STA executes P2P communication. Specifically, the terminal apparatus STA that transmits the data specified by the P2P communication initiation frame and the terminal apparatus STA that receives the data transmit and receive the data directly without going through the access point AP. When the P2P communication period ends, the terminal apparatus STA ends the series of processes in FIG. 8 (end).

[0057] (Operation of terminal apparatus STA not targeted for P2P communication) In the process of step S25, the terminal apparatus STA sets a transmission prohibition period based on the P2P communication period specified by the P2P communication initiation frame. The transmission prohibition period may be specified directly by the P2P communication initiation frame, or may be set based on information about the P2P communication period. When the process of step S25 ends, the terminal apparatus STA proceeds to the process of step S26.

[0058] In the processing of step S26, the terminal apparatus STA checks whether it has received the response frame of step S23 (e.g., CTS in response to MU-RTS_TXF_TF). That is, in the processing of step S26, the terminal apparatus STA checks whether it is located within the communication area of ​​the terminal apparatus STA with which it is P2P communication, or whether it is located outside the communication area of ​​the terminal apparatus STA with which it is P2P communication. In the processing of step S26, the terminal apparatus STA may determine that it has not received the response frame of step S23 based on the elapse of a predetermined time since it received the P2P communication start frame. Specifically, for example, if it does not detect a channel busy after SIFS (Short Inter Frame Space) since it received MU-RTS_TXF_TF, the terminal apparatus STA may determine that it has not received the response frame of step S23. In addition, in the processing of step S26, the terminal apparatus STA may determine that it has not received the response frame of step S23 based on the fact that it was not able to receive the response frame of step S23 normally. Specifically, for example, if the terminal device STA detects a channel busy state SIFS after receiving MU-RTS_TXF_TF but is unable to recognize it as a CTS, the terminal device STA determines that it has not received the response frame of step S23.

[0059] In the process of step S26, when it is confirmed that the response frame of step S23 has been received (step S26: YES), the terminal apparatus STA prohibits transmission during the transmission prohibition period specified by the P2P communication start frame. That is, the terminal apparatus STA prohibits transmission and reception of data with the access point AP during the transmission prohibition period. When the P2P communication period ends, the terminal apparatus STA ends the series of processes of FIG. 8 (END).

[0060] If it is confirmed in the process of step S26 that the response frame of step S23 has not been received (step S26: NO), the terminal apparatus STA cancels the setting of the transmission prohibition period, i.e., cancels the transmission prohibition (step S27). This allows the terminal apparatus STA to transmit and receive data with the access point AP during the transmission prohibition period specified by the P2P communication start frame. As a result, the terminal apparatus STA can communicate with the access point AP during the P2P communication period depending on the traffic (step S28). For example, the terminal apparatus STA that voluntarily canceled the transmission prohibition communicates with the access point AP using the EDCA mechanism during the P2P communication period. When the P2P communication period ends, the terminal apparatus STA ends the series of processes shown in FIG. 8 (END).

[0061] In the process of step S28, the terminal apparatus STA may transmit a communication request to the access point AP. The access point AP may recognize that the transmission prohibition of the terminal apparatus STA has been lifted based on the communication request. The timing of transmitting the communication request may be when it is confirmed that the response frame of step S23 has not been received, or when communication with the access point AP becomes necessary. When the access point AP recognizes that the transmission prohibition of the terminal apparatus STA has been lifted, the communication method between the access point AP and the terminal apparatus STA is not particularly limited. For example, when there is upstream traffic, the access point AP may transmit a trigger frame to the terminal apparatus STA requesting the transmission of upstream traffic based on the fact that the transmission prohibition of the terminal apparatus STA has been lifted.

[0062] Furthermore, a terminal apparatus STA that is not a target of P2P communication may set its NAV for the P2P communication period based on the reception of the response frame of step S23. In this case, the terminal apparatus STA that is not a target of P2P communication does not set its NAV based on the P2P communication start frame. In other words, a terminal apparatus STA that is not a target of P2P communication sets transmission prohibition during the P2P communication period when it receives the response frame of step S23, and maintains a state in which it can communicate with the access point AP when it does not receive the response frame of step S23.

[0063] <2-3> Specific Examples of P2P Communication Next, a specific example of P2P communication in the communication system 1 according to the embodiment will be described.

[0064] 9 is a schematic diagram for explaining a specific example of P2P communication in the communication system 1 according to the embodiment. As shown in FIG. 9, in this example, four terminal devices STA1, STA2, STA3, and STA4 are wirelessly connected to an access point AP. Each of the four terminal devices STA1 to STA4 is located within a communication area CA_AP of the access point AP. Terminal device STA1 is located within a communication area CA_STA2 of terminal device STA2. Terminal device STA2 is located within the communication area CA_STA1 of terminal device STA1. Terminal device STA3 is located within the communication area CA_STA1 of terminal device STA1. Terminal device STA4 is located outside both the communication area CA_STA1 of terminal device STA1 and the communication area CA_STA2 of terminal device STA2.

[0065] 10 is a timing chart showing an example of a P2P communication sequence in the communication system according to the embodiment, in which a pair of terminal devices STA1 and STA2 execute P2P communication in the arrangement of the access point AP and four terminal devices STA1 to STA4 shown in FIG.

[0066] As shown in Fig. 10, when starting P2P communication, the access point AP may first transmit a CTS-to-Self frame. The CTS-to-Self frame is a CTS transmitted to the access point AP as the destination and is used for access control. By transmitting the CTS-to-Self frame, the access point AP can prohibit transmission by all terminal devices STA within its communication area CA_AP for a certain period of time.

[0067] Next, the access point AP transmits MU-RTS_TXS_TF. MU-RTS_TXS_TF is received by all terminal devices STA1 to STA4 within the communication area CA_AP. In this example, the terminal devices STA that are targets of P2P communication are STA1 and STA2, and the terminal devices STA that are not targets of P2P communication are STA3 and STA4. Therefore, based on receiving MU-RTS_TXS_TF, each of the terminal devices STA1 and STA2 sets a P2P communication period. Meanwhile, based on receiving MU-RTS_TXS_TF, each of the terminal devices STA3 and STA4 sets a transmission prohibition period (NAV) to match the P2P communication period.

[0068] Then, of the pair of terminal devices STA that are the target of P2P communication, the transmitting terminal device STA1 transmits a response frame (CTS) to MU-RTS_TXS_TF. This prevents terminal devices STA that are not the target of P2P communication from interrupting frame transmission during the assigned P2P communication period (TXOP period). In this example, this CTS is received by the access point AP and the terminal devices STA2 and STA3 within the communication area CA_STA1 of the terminal device STA1, but is not received by the terminal device STA4 outside the communication area CA_STA1. Therefore, the terminal device STA3 sets a NAV for the P2P communication period in response to receiving the CTS. On the other hand, the terminal device STA4 cannot receive the CTS normally, so it cancels (resets) the NAV setting for the P2P communication period. Note that if the NAV is set by the CTS-to-Self frame, the terminal device STA4 cancels this NAV setting.

[0069] Thereafter, during the P2P communication period, terminal device STA1 transmits a data frame to terminal device STA2 without going through the access point AP. During the P2P communication period, terminal device STA2 transmits a BlockAck (BA) to terminal device STA1 without going through the access point AP in response to successfully receiving the data frame from terminal device STA1. Terminal device STA3 waits because its NAV is set during the P2P communication period. During the P2P communication period, terminal device STA4 transmits a data frame to the access point AP, for example, because its NAV is canceled. In response to receiving the data frame from terminal device STA4, the access point AP transmits a BlockAck to terminal device STA4.

[0070] As described above, during the P2P communication period, the length of the NAV set in the terminal device STA3 is longer than the length of the NAV set in the terminal device STA4. The length of the NAV set in the terminal device STA3 is equal to the length of the P2P communication period. In FIG. 10, the length of the NAV set in the terminal device STA4 is determined based on the fact that a CTS in response to MU-RTS_TXS_TF was not received from the terminal device STA1. When the P2P communication period ends, the access point AP and each terminal device STA perform the following process.

[0071] <3> Effects of the embodiment In the communication system 1 according to the embodiment, the access point AP is configured to allocate a period (P2P communication period) for P2P communication by a pair of terminal devices STA, and during the P2P communication period, prohibit transmission and reception of data when the other terminal device STA is within the communication area of ​​one of the pair of terminal devices STA, and accept transmission and reception of data when the other terminal device STA is outside the communication area of ​​the one terminal device STA. The terminal device STA is configured to prohibit transmission of wireless signals for a first time period when it is within the communication area of ​​the one terminal device, and not prohibit transmission when it is outside the communication area of ​​the one terminal device, during the P2P communication period.

[0072] As a result, the access point AP according to the embodiment can improve communication stability in P2P communication by using the P2P communication initiation frame to secure a communication period for P2P communication. Also, the terminal device STA according to the embodiment can transmit and receive frames during the P2P communication period by canceling the transmission prohibition based on the fact that a confirmation frame for the P2P communication initiation frame has not been received. As a result, the communication system 1 according to the embodiment can improve the communication efficiency of the terminal device STA in P2P communication, which is not affected by the paired terminal device that is the target of the P2P communication.

[0073] <4> Others The conversion process from radio frames to radio signals described in the embodiments includes, for example, any of convolutional coding, interleaving, subcarrier modulation, inverse fast Fourier transform, OFDM (Orthogonal Frequency Division Multiplexing) modulation, and frequency conversion. The conversion process from radio signals to radio frames described in the embodiments includes, for example, any of frequency conversion, OFDM demodulation, fast Fourier transform, subcarrier demodulation, deinterleaving, and Viterbi decoding.

[0074] In the embodiments, the CPU 11 of the access point AP and the CPU 21 of the terminal device STA may each be other circuits. For example, the access point AP and the terminal device STA may each include an MPU (Micro Processing Unit) or the like instead of a CPU. The processes described in the embodiments may be realized by dedicated hardware. The processes of the access point AP and the terminal device STA may be a mixture of processes executed by software and processes executed by hardware, or may be only one of them.

[0075] The functional configurations of the access point AP and the station STA according to the embodiment may be other functional configurations as long as they are capable of performing the above-described operations. For example, the channel access function of the access point AP may be implemented in the frame processing unit 130 instead of the transceiver unit 140. Similarly, the channel access function of the station STA may be implemented in the frame processing unit 230 instead of the transceiver unit 240.

[0076] In the embodiments, the flowcharts used to explain the operations are merely examples. Other processes may be added to each operation described in the embodiments. In this specification, a "data frame" corresponds to a radio frame containing data. A wireless communication standard other than the IEEE 802.11 standard may be used as the wireless communication standard.

[0077] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention.

[0078] REFERENCE SIGNS LIST 1... communication system AP... access point STA... terminal device 11, 21... CPU 12, 22... ROM 13, 23... RAM 14, 24... wireless communication module 15... wired communication module 25... display 26... storage 110, 210... LLC processing unit 120, 220... link management unit 130, 230... frame processing unit 140, 240... transmission / reception unit 200... application execution unit

Claims

1. A terminal device comprising: a communication circuit configured to transmit and receive wireless signals; and a processor configured to establish a wireless link with an access point using the communication circuit, and to prohibit transmission of wireless signals for a first period of time when within the communication area of one of the pair of terminal devices during a period assigned to Peer-to-Peer (P2P) communication by the pair of terminal devices that have established the wireless link with the access point, and not to prohibit transmission when outside the communication area of the one terminal device.

2. The terminal device according to claim 1, wherein the processor is further configured to start prohibiting transmission of wireless signals during the period based on receiving a first wireless frame instructing start of the P2P communication from the access point.

3. The terminal device according to claim 2, wherein the processor is further configured to release the transmission prohibition based on not being able to receive a second wireless frame from the one terminal device.

4. The terminal device according to claim 3, wherein the second wireless frame is a response frame to the first wireless frame.

5. The terminal device according to any one of claims 1 to 4, wherein the first period of time is equal to or longer than the length of the period.

6. An access point comprising: a communication circuit configured to transmit and receive wireless signals; and a processor configured to establish wireless links with a first terminal device, a second terminal device, and a third terminal device using the communication circuit, assign a period for Peer-to-Peer (P2P) communication by the first terminal device and the second terminal device, and prohibit data transmission and reception when the third terminal device is within the communication area of one of the first terminal device and the second terminal device during the period, and accept data transmission and reception when outside the communication area of the one terminal device.

7. The access point according to claim 6, wherein the processor is further configured to confirm that the third terminal device is outside the communication area of the one terminal device based on receiving a first wireless frame from the third terminal device during the period.

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