Terminal device and access point

Abstract

A terminal device according to an embodiment comprises: a communication circuit that transmits / receives a wireless signal; and a management unit that controls, by using the communication circuit, transmission of a first frame including an information element indicating the presence of low-latency data, to an access point, within a transmission opportunity (TXOP) period of the access point that has secured a TXOP.

Description

Terminal devices and access points

[0001] The embodiments relate to terminal devices and access points.

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

[0003] In use cases such as XR (Extended Reality), communication between access points and terminal devices is performed in a P2P (peer-to-peer) manner. Since communication at Layer 3 or higher (TCP (Transmission Control Protocol) / TCP Ack, etc.) is bidirectional, existing RTS (Request To Send) / CTS (Clear To Send) procedures only secure a TXOP (transmission opportunity) in the direction of sending RTS / CTS frames, respectively. Therefore, when performing bidirectional communication, channel access rights must be secured using the CSMA / CA (carrier sense multiple access with collision avoidance) procedure at the timing of switching DL / UL (Down Link / Up Link). This can contribute to increased latency due to interruptions from other terminals. For example, in IEEE 802.11bn, to solve this problem, the specification of a control frame for switching UL / DL within the secured TXOP is being discussed. Furthermore, in IEEE 802.11TGbn, a mechanism is being discussed that enables communication without creating a break between UL / DL using a single TXOP by transmitting the control frame.

[0004] IEEE Std 802.11-2020, “10.3.2.4 Setting and resetting the NAV”, pp. 1647- 1649, February 26, 2021.Dibakar Das et al., “TXOP sharing extensions for XR use-cases,” IEEE 802.11-23 / 1387, August 2023

[0005] In the above mechanism, the TXOP holder (e.g., AP) that secures the TXOP by CSMA / CA performs communication. After finishing transmitting the data held by the AP itself, the communication direction is switched by a control frame. Therefore, if a terminal device that cannot obtain the transmission right and cannot set the TXOP holds low-latency (LL) data, the transmission deadline of the low-latency data may be reached during the frame transmission period of the AP. Therefore, even if the AP secures the TXOP by the above mechanism, if the transmission deadline of the low-latency data is reached before the TXOP is transferred from the AP to the terminal device, there is a problem that the requirement conditions regarding the delay cannot be satisfied.

[0006] Therefore, the present invention has been made paying attention to the above circumstances, and an object thereof is to provide a terminal device and an access point that enable transmission of low-latency data within the transmission deadline of the low-latency data even if the communication partner of the TXOP holder has the low-latency data.

[0007] The terminal device according to the embodiment includes a communication circuit configured to transmit and receive wireless signals, and a management unit configured to control, using the communication circuit, to transmit a first frame including an information element indicating that the terminal device has low-latency data to the access point within the TXOP period of the access point that has secured the TXOP.

[0008] The terminal device of this embodiment is configured to include a communication circuit configured to send and receive wireless signals, and a management unit that uses the communication circuit to receive an RTS frame from an access point having a TXOP, and, in response to the reception of the RTS frame, transmits a CTS-to-Self frame addressed to itself if it has low-latency data, and controls the transmission of a data frame containing low-latency data.

[0009] The access point of the embodiment is configured to include a communication circuit configured to send and receive wireless signals, and a management unit that uses the communication circuit to receive a CTS frame from a destination device in response to the transmission of an RTS frame within the TXOP period, and when it receives a first frame containing an information element indicating that the destination device has low-latency data, it transmits a control frame for transferring the TXOP.

[0010] According to the embodiment, it is possible to provide a terminal device and access point that enable the transmission of low-latency data within the low-latency data transmission deadline, even if the communication partner of the TXOP holder has low-latency data.

[0011] Figure 1 is a block diagram showing an example of the overall configuration of a communication system according to the first embodiment. Figure 2 is a block diagram showing an example of the hardware configuration of an access point included in the communication system according to the first embodiment. Figure 3 is a block diagram showing an example of the hardware configuration of a terminal device included in the communication system according to the first embodiment. Figure 4 is a block diagram showing an example of the functional configuration of an access point included in the communication system according to the first embodiment. Figure 5 is a block diagram showing an example of the functional configuration of a terminal device included in the communication system according to the first embodiment. Figure 6 is a sequence diagram showing an example of communication processing by the communication system according to the first embodiment. Figure 7 is a sequence diagram showing an example of communication processing by a communication system according to a modification of the first embodiment. Figure 8 is a sequence diagram showing an example of communication processing by the communication system according to the second embodiment.

[0012] Each embodiment is described below with reference to the drawings. Each embodiment illustrates an apparatus or method for realizing the technical idea of ​​the invention. The drawings are schematic or conceptual. Hereinafter, components having substantially the same function and configuration are denoted by the same reference numeral. The numbers following the letters that constitute the reference numerals are used to distinguish 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 or numbers, these elements are referred to by reference numerals containing only letters or numbers.

[0013] Furthermore, in the following, "access point" will be abbreviated as "AP" as appropriate. "Terminal device" will be abbreviated as "STA (Station)" as appropriate. In this embodiment, a wireless LAN access point may also be called a "base station".

[0014] [First Embodiment] In the communication system according to the first embodiment, the STA recognizes the presence of low-latency data through an information element that notifies the presence or absence of low-latency traffic, which is a response to a frame inquiring about the presence or absence of low-latency traffic received by the AP, and thereby transfers the TXOP to the STA. This configures the terminal device to transmit low-latency data. Details of the communication system according to the first embodiment will be described below.

[0015] (Configuration) First, the configuration of the communication system according to the first embodiment will be described. Figure 1 is a block diagram showing an example of the overall configuration of the communication system 1 according to the first embodiment. As shown in Figure 1, the communication system 1 according to the first embodiment includes an access point 10 and a terminal device 20.

[0016] Access point 10 is a type of wireless LAN access point. Access point 10 is connected to a network NW. Access point 10 is configured to communicate via wired or wireless connection with a server (not shown) on the network NW. Access point 10 can establish a link with terminal device 20.

[0017] The terminal device 20 is an STA, such as a smartphone, PC (Personal Computer), or tablet device. The terminal device 20 is configured to communicate wirelessly with the access point 10. Multiple terminal devices 20 may be wirelessly connected to the access point 10.

[0018] The wireless communication used in communication system 1 conforms to the IEEE 802.11 standard, for example. The IEEE 802.11 standard has wireless communication functionality based on the OSI (Open Systems Interconnection) reference model. In the OSI reference model, wireless communication functionality 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, Layer 7: Application Layer). The data link layer includes the LLC (Logical Link Control) sublayer and the MAC (Media Access Control) sublayer. The frequency bands used in communication system 1 may include, for example, the 2.4 GHz band, 5 GHz band, 6 GHz band, 45 GHz band, and 60 GHz band. Multiple channels may be allocated to each frequency band.

[0019] Next, the hardware configuration of the access point 10 provided in the communication system 1 according to the first embodiment will be described. Figure 2 is a block diagram showing an example of the hardware configuration of the access point 10 provided in the communication system 1 according to the first embodiment. As shown in Figure 2, the access point 10 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.

[0020] The CPU 11 is a processor capable of executing various programs and controls the overall operation of the access point 10. The ROM 12 is, for example, a non-volatile semiconductor memory that stores programs and control data for controlling the access point 10. The RAM 13 is, for example, a volatile semiconductor memory and is used as a workspace for the CPU 11. The wireless communication module 14 is a communication circuit configured to send and receive wireless signals via an antenna. The wireless communication module 14 has multiple wireless LAN interfaces. The wired communication module 15 is a circuit used for sending and receiving data via wired signals and is configured to be connectable to a network NW.

[0021] Next, the hardware configuration of the terminal device 20 included in the communication system 1 according to the first embodiment will be described. Figure 3 is a block diagram showing an example of the hardware configuration of the terminal device 20 included in the communication system 1 according to the first embodiment. As shown in Figure 3, the terminal device 20 includes, for example, a CPU 21, ROM 22, RAM 23, wireless communication module 24, display 25, and storage 26.

[0022] The CPU 21 is a processor capable of executing various programs and controls the overall operation of the terminal device 20. The ROM 22 is, for example, a non-volatile semiconductor memory and stores programs and control data for controlling the terminal device 20. The RAM 23 is, for example, a volatile semiconductor memory and is used as a workspace for the CPU 21. The wireless communication module 24 is a communication circuit configured to send and receive wireless signals via an antenna. The wireless communication module 24 has multiple wireless LAN interfaces. The display 25 displays, for example, the GUI (Graphical User Interface) of application software. The storage 26 is a non-volatile storage device that stores system software for the terminal device 20.

[0023] Next, the functional configuration of the access point 10 provided in the communication system 1 according to the first embodiment will be described. Figure 4 is a block diagram showing an example of the functional configuration of the access point 10 provided in the communication system 1 according to the first embodiment. As shown in Figure 4, the access point 10 includes, for example, a management unit 110, an upper layer processing unit 120, a frame processing unit 130, and a wireless signal processing unit 140. The management unit 110 and the frame processing unit 120 are functional blocks that execute processing corresponding to the MAC sublayer of the second layer. The upper layer processing unit 120 is a functional block that executes processing corresponding to the LLC sublayer of the second layer and layers 3 through 7. The wireless signal processing unit 140 is a functional block that executes processing corresponding to the first layer.

[0024] The management unit 110 manages management information related to the terminal devices 20 belonging to the access point 10. This management information may include information about the link status of the terminal devices 20 and information about user requirements. The management unit 110 also performs processes to establish a wireless connection (wireless link) with the terminal devices 20. Furthermore, the management unit 110 controls the overall operation of the access point 10.

[0025] The upper layer processing unit 120 outputs data input from the network 30 via the LLC layer to the frame processing unit 120. The data processing unit 110 also outputs data input from the frame processing unit 120 to the network 30 via the LLC layer.

[0026] When data is input from the management unit 110 or the upper layer processing unit 120, the frame processing unit 130 adds a MAC header to the input data to generate a MAC frame. The frame processing unit 130 then outputs the MAC frame to the wireless signal processing unit 140. Furthermore, when a MAC frame is input from the wireless signal processing unit 140, the frame processing unit 130 extracts data from the MAC frame and outputs the extracted data according to the type of MAC frame to the management unit 110 or the upper layer processing unit 120. Specifically, if the MAC frame is a data frame, the frame processing unit 130 inputs the data to the upper layer processing unit 120. If the MAC frame is a management frame or a control frame, the frame processing unit 120 inputs the data to the management unit 110.

[0027] Furthermore, the frame processing unit 130 generates a frame to query the terminal device 20 for the presence or absence of low-latency traffic. Here, any frame such as a BSRP (Buffer Status Report Poll) can be used as the frame to query for the presence or absence of low-latency traffic.

[0028] The wireless signal processing unit 140 transmits and receives data, management information, etc., to and from terminal devices 20 belonging to the access point 10. For example, the wireless signal processing unit 140 transmits frames input by the frame processing unit 130 as wireless signals to the outside via the antenna. The wireless signal processing unit 140 also sends wireless signals received by the antenna to the frame processing unit 130. When notifying multiple terminal devices 20 simultaneously, the wireless signal processing unit 140 may transmit beacon signals, etc., via multicast or broadcast.

[0029] Next, the functional configuration of the terminal device 20 included in the communication system 1 according to the first embodiment will be described. Figure 5 is a block diagram showing an example of the functional configuration of the terminal device 20 included in the communication system 1 according to the first embodiment. As shown in Figure 5, the terminal device 20 includes, for example, a management unit 210, a higher layer processing unit 220, a frame processing unit 230, and a wireless signal processing unit 240.

[0030] The management unit 210 manages information related to communication between the terminal and the access point 10. For example, the management unit 210 manages status information indicating the status of the wireless link with the access point 10. The management unit 210 and the frame processing unit 220 are functional blocks that execute processing corresponding to the MAC sublayer of the second layer. The upper layer processing unit 220 is a functional block that executes processing corresponding to the LLC sublayer of the second layer and layers 3 through 7. The wireless signal processing unit 240 is a functional block that executes processing corresponding to layer 1.

[0031] The management unit 210 controls the operation of the entire terminal device 20. For example, the management unit 210 controls the terminal device 20 to send a frame containing an information element indicating that it has low-latency data to the access point. Here, any information element such as BSR can be used as the information element. Furthermore, if a TXOP is present in the terminal device 20, the management unit 210 determines whether to return the TXOP to the access point 10.

[0032] The upper layer processing unit 220 outputs data input from the upper layer via the LLC layer to the frame processing unit 220. The data processing unit 210 executes an application based on the data input from the frame processing unit 220. For example, the upper layer processing unit 220 can display application information on the display 25. Furthermore, the upper layer processing unit 220 can operate based on the operation of the input interface.

[0033] When data is input from the management unit 210 or the upper layer processing unit 220, the frame processing unit 230 adds a MAC header to the input data to generate a MAC frame. The frame processing unit 230 then outputs the MAC frame to the wireless signal processing unit 240. Furthermore, when a MAC frame is input from the wireless signal processing unit 240, the frame processing unit 230 extracts data from the MAC frame and outputs the extracted data according to the type of MAC frame to the management unit 210 or the upper layer processing unit 220. Specifically, if the MAC frame is a data frame, the frame processing unit 230 inputs the data to the upper layer processing unit 220. If the MAC frame is a management frame or a control frame, the frame processing unit 220 inputs the data to the management unit 210.

[0034] The frame processing unit 230 receives a wireless signal from the wireless signal processing unit 240 and extracts frames and data from the wireless signal. When the frame processing unit 230 receives data from a higher-level application, it generates a frame containing the data and sends it to the wireless signal processing unit 240.

[0035] The wireless signal processing unit 240 transmits and receives data, management information, etc., to and from the access point 10. For example, the wireless signal processing unit 240 transmits frames input from the frame processing unit 230 as wireless signals via the antenna. The wireless signal processing unit 250 also sends wireless signals received by the antenna to the frame processing unit 230. In addition, as with the access point 10, the wireless signal processing units 250 may transmit beacon signals, etc., via multicast or broadcast.

[0036] (Operation) Next, the operation of the communication system 1 according to the first embodiment will be described.

[0037] Figure 6 is a sequence diagram showing an example of communication processing by the communication system 1 according to the first embodiment. In the example in Figure 6, the TXOP holder that has secured the TXOP is the access point 10, and the communication partner of the access point 10 is the terminal device 20.

[0038] In step ST101, access point 10 sends an RTS frame to terminal device 20 inquiring whether access point 10 may transmit data during the TXOP period. Under the control of management unit 110, frame processing unit 130 generates an RTS frame, and wireless signal processing unit 140 transmits the RTS frame to terminal device 20. Here, the RTS may include the TXOP period. Therefore, terminal device 20 recognizes the TXOP period by receiving the RTS. Access point 10 may notify terminal device 20 of the TXOP period before access point 10 secures the TXOP. That is, terminal device 20 may recognize the TXOP period before the processing in step ST101 is performed.

[0039] In step ST102, the terminal device 20 that received the RTS sends a CTS frame to the access point 10 indicating that it is OK to transmit data. Under the control of the management unit 210, the frame processing unit 230 generates a CTS frame, and the wireless signal processing unit 240 transmits the CTS frame to the access point 10.

[0040] In step ST103, the access point 10 transmits a BSRP to the terminal device 20. The frame processing unit 130 of the access point 10, upon receiving the CTS frame, generates a BSRP, which is a type of trigger frame, under the control of the management unit 110, to query the terminal device 20 for low-latency data. The wireless signal processing unit 140 then transmits the BSRP to the terminal device 2. In the first embodiment, the access point 10 describes an example in which a BSRP is used as a frame to query for the presence or absence of low-latency traffic. However, it is also possible to use a frame that defines a new frame, which is a frame already defined in IEEE 802.11, with an information element added that includes a query for whether or not there is low-latency data.

[0041] In step ST104, the terminal device 20 transmits a BSR (Buffer Status Report) to the access point 10. Upon receiving the BSRP, the management unit 210 of the terminal device 20 determines whether there is low-latency data. Under the control of the management unit 210, the frame processing unit 230 of the terminal device 20 generates a frame containing a BSR that includes the determination result (i.e., an information element indicating the presence or absence of low-latency data). The wireless signal processing unit 240 then transmits the frame to the access point 10. In the first embodiment, an example is described in which the terminal device 20 uses a BSR as an information element to notify the presence or absence of low-latency traffic. However, it is also possible to use a BSR described in the A-control field of any frame, or to define a new frame or information element.

[0042] In step ST105, the access point 10 transmits a control frame (also referred to as a control frame). If the BSR contains information elements for which the terminal device 20 has low-latency data, the frame processing unit 130 of the access point 10 generates a control frame (indicated as Ctrl in Figure 6) to transfer the TXOP secured by the access point 10 to the terminal device 20, under the control of the management unit 110. Then, the wireless signal processing unit 140 transmits the generated control frame to the terminal device 20.

[0043] If the BSR contains information elements for which the terminal device 20 does not have low-latency data, the process skips steps ST105 to ST108 and proceeds to step ST109.

[0044] In step ST106, the terminal device 20 transmits low-latency data. The terminal device 20 detects that the TXOP has been transferred to the terminal device 20 by receiving a control frame. Then, under the control of the management unit 210, the frame processing unit 230 of the terminal device 20 generates a data frame including low-latency data. Note that the frame processing unit 230 may generate a data frame after receiving the BSRP in step ST103. Then, the radio signal processing unit 240 transmits the generated data frame to the access point 10. By processing as described above, the terminal device 20 can transmit the low-latency data to the access point 10 within the low-latency data transmission deadline.

[0045] In step ST107, the access point 10 transmits an Ack. The frame processing unit 130 of the access point 10 that has normally received the low-latency data generates an Ack indicating that the low-latency data has been normally received under the control of the management unit 110. Then, the radio signal processing unit 140 transmits the BA to the terminal device 20. Note that a BA (Block Ack) may be used.

[0046] In step ST108, the terminal device 20 transmits a control frame. The management unit 210 of the terminal device 20 that has received the BA determines whether the remaining TXOP period is more than a predetermined period. If it is determined that there is a remainder, under the control of the management unit 210, the frame processing unit 230 of the terminal device 20 generates a control frame for returning the TXOP to the access point 10. Then, the radio signal processing unit 240 transmits the control frame to the access point 10. Note that if it is determined that the TXOP period is less than a predetermined period, the processing may skip steps ST108 to ST110.

[0047] In step ST109, the access point 10 transmits data. The frame processing unit 130 of the access point 10 to which the TXOP has been returned generates a data frame including the data to be transmitted to the terminal device 20 under the control of the management unit 110. Then, the radio signal processing unit 140 transmits the data frame to the terminal device 20.

[0048] In step ST110, the terminal device 20 transmits an Ack. The frame processing unit 230 of the terminal device 20 that has normally received the data included in the data frame generates an Ack indicating that the data has been normally received under the control of the management unit 210. Then, the wireless signal processing unit 240 transmits the Ack to the access point 10.

[0049] (Operational Effects of the First Embodiment) As described above, in the communication system 1 according to the first embodiment, the terminal device 20 that has responded to the BSRP transmitted by the access point 10 transmits a frame including an information element indicating whether the terminal device 20 has low-latency data. When the terminal device 20 has low-latency data, the access point 10 transfers the TXOP to the terminal device 20 by transmitting a control frame. As a result, the low-latency data can be transmitted to the access point 10 within the low-latency data transmission deadline.

[0050] [Modification Example of the First Embodiment] In the first embodiment, an example in which the terminal device 20 transmits a frame including a BSR after receiving the BSRP has been described. In a modification example of the first embodiment, an example in which the terminal device 20 transmits a frame including a BSR immediately or after a certain period has elapsed after transmitting a CTS will be described.

[0051] FIG. 7 is a sequence diagram showing an example of communication processing by the communication system 1 according to the modification example of the first embodiment. Steps ST201 to ST202 may be the same as steps ST101 to ST102 described with reference to FIG. 6, and thus the overlapping description here is omitted.

[0052] In step ST203, the terminal device 20 transmits a frame containing the BSR to the access point 10. After transmitting the CTS frame, the management unit 210 of the terminal device 20 determines whether there is low-latency data. Then, under the control of the management unit 210, the frame processing unit 230 of the terminal device 20 generates a frame containing the BSR that includes the determination result (i.e., an information element indicating the presence or absence of low-latency data). Then, the wireless signal processing unit 240 transmits the frame to the access point 10. The wireless signal processing unit 240 may transmit the frame immediately after transmitting the CTS, or it may transmit it after a predetermined period has elapsed. In other words, a predetermined period for transmitting the BSR is set so that the low-latency data is transmitted by the low-latency data transmission deadline.

[0053] Alternatively, the BSR may be included in the CTS frame transmitted in step ST202. In this case, upon receiving the RTS frame, the management unit 210 determines whether there is low-latency data. Then, under the control of the management unit 210, the frame processing unit 230 generates a CTS frame that includes the BSR containing the determination result. The processing in step ST203 may then be skipped.

[0054] Steps ST204 to ST209 may be the same process as steps ST105 to ST110, which were explained with reference to Figure 6, so a redundant explanation will be omitted here.

[0055] [Second Embodiment] In the communication system according to the second embodiment, the terminal device secures a TXOP based on the RTS response received from the AP, and is configured to transmit low-latency data. The differences from the first embodiment will be mainly described below.

[0056] (Configuration) The configuration of the communication system 1 according to the second embodiment may be the same as that of the communication system 1 according to the first embodiment. Therefore, redundant explanations are omitted here.

[0057] (Operation) Next, the operation of the communication system 1 according to the second embodiment will be described.

[0058] Figure 8 is a sequence diagram showing an example of communication processing by the communication system 1 according to the second embodiment. In the example in Figure 8, the TXOP holder that has secured the TXOP is the access point 10, and the communication partner of the access point 10 is the terminal device 20.

[0059] In step ST301, access point 10 sends an RTS to terminal device 20 asking whether access point 10 may transmit data during the TXOP period. Here, the RTS may include the TXOP period. Access point 10 may also notify terminal device 20 of the TXOP period before access point 10 secures the TXOP. Then, access point 10 waits for this frame for the set period during which it accepts CTS frames.

[0060] In step ST302, if terminal device 20 has low-latency data to transmit immediately, it transmits a CTS-to-Self frame to itself. The management unit 210 of terminal device 20, which has received the RTS, determines whether there is low-latency data. If it determines that there is low-latency data, the frame processing unit 230 generates a CTS-to-Self frame under the control of the management unit 210. The wireless signal processing unit 240 then transmits the CTS-to-Self to itself. The CTS-to-Self frame is a CTS that is transmitted with itself as the destination. In other words, instead of transmitting a CTS to the access point 10, terminal device 20, which has received the RTS, transmits a CTS-to-Self frame. This allows terminal device 20 to secure the TXOP reserved by access point 10.

[0061] Furthermore, if it is determined that there is no low-latency data, the frame processing unit 230 may, under the control of the management unit 210, generate a normal CTS frame, and the wireless signal processing unit 240 may, of course, transmit the CTS frame to the access point 10.

[0062] In step ST303, the terminal device 20 transmits low-latency data. Under the control of the management unit 210, the frame processing unit 230 of the terminal device 20 generates a data frame containing the low-latency data. The wireless signal processing unit 240 then transmits the generated data frame to the access point 10. By processing as described above, the terminal device 20 can transmit the low-latency data to the access point 10 within the low-latency data transmission deadline.

[0063] In step ST304, the access point 10 transmits an Ack. The frame processing unit 130 of the access point 10, which has successfully received the low-latency data, generates an Ack indicating that it has successfully received the low-latency data, under the control of the management unit 110. The wireless signal processing unit 140 then transmits the Ack to the terminal device 20.

[0064] In step ST305, the terminal device 20 transmits a control frame. Under the control of the management unit 210, the frame processing unit 230 of the terminal device 20 generates a control frame to return the TXOP to the access point 10. The wireless signal processing unit 240 then transmits the control frame to the access point 10. As in the first embodiment, the management unit 210 of the terminal device 20 that receives the BA may, of course, determine whether the TXOP period remains longer than a predetermined period, and if it determines that it remains longer than a predetermined period, transmit the control frame to the access point 10.

[0065] In step ST306, the access point 10 transmits data. The frame processing unit 130 of the access point 10, upon receiving the TXOP, generates a data frame containing the data to be transmitted to the terminal device 20 under the control of the management unit 110. The wireless signal processing unit 140 then transmits the data frame to the terminal device 20.

[0066] In step ST307, the terminal device 20 transmits an Ack. The frame processing unit 230 of the terminal device 20, having successfully received the data contained in the data frame, generates an Ack indicating that the data has been successfully received. The wireless signal processing unit 240 then transmits this Ack to the access point 10.

[0067] (Effects of the second embodiment) In the communication system 1 according to the second embodiment, if the terminal device 20 that has received the RTS has low-latency data, it transmits a CTS-to-Self frame instead of transmitting a CTS frame to the access point 10. This allows the terminal device 20 to secure a TXOP and transmit the low-latency data to the access point 10 within the low-latency data transmission deadline.

[0068] [Other Embodiments] In the first and second embodiments, an example was described in which the TXOP holder is an access point 10 and the communication partner of the access point 10 is a terminal device 20, but the embodiment is not limited to this. For example, the TXOP holder may be a terminal device 20 and the communication partner may be an access point 10, or both the TXOP holder and the communication partner may be terminal devices 20. For example, when both the TXOP holder and the communication partner are terminal devices 20, the terminal device 20 connected to the access point 10 performs the communication processing described above.

[0069] In the above embodiments, the CPU 11 of the access point 10 and the CPU 21 of the terminal device 20 may each be other circuits (or processors). For example, the access point 10 and the terminal device 20 may each be equipped with an MPU (Micro Processing Unit) instead of a CPU. Each of the processes described in each embodiment may be implemented by dedicated hardware. The processes of the access point 10 and the terminal device 20 may be a mixture of processes executed by software and processes executed by hardware, or they may consist of only one or the other. The flowcharts or sequence diagrams used to describe the operation in the above embodiments are merely examples. The order of the operations described in the embodiments may be changed to the extent possible, and other processes may be added. A wireless communication standard other than the IEEE 802.11 standard may be used as the wireless communication standard.

[0070] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways during implementation without departing from its essence. Furthermore, each embodiment may be combined as appropriate, and in that case, the combined effects can be obtained. Moreover, the above embodiments include various inventions, and various inventions can be extracted by selecting combinations from the multiple constituent elements disclosed. For example, if the problem can be solved and effects can be obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, then the configuration with these deleted constituent elements can be extracted as an invention.

[0071] 1...Communication system 10...Access point 20...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...Management unit 120,220...Upper layer processing unit 130,230...Frame processing unit 140,240...Wireless signal processing unit

Claims

1. A terminal device comprising: a communication circuit configured to transmit and receive wireless signals; and a management unit that uses the communication circuit to control the transmission of a first frame containing an information element indicating that it has low-latency data to an access point within the TXOP period of an access point that has secured a TXOP (transmission opportunity).

2. The terminal device according to claim 1, wherein the management unit further controls the transmission of the first frame after receiving a second frame which includes an inquiry about whether it has low-latency data.

3. The terminal device according to claim 1, wherein the management unit further controls the device to transmit the first frame after transmitting a CTS frame in response to the reception of an RTS frame.

4. The terminal device according to claim 2 or 3, wherein the management unit, after receiving a control frame indicating the transfer of the TXOP, further controls the transmission of a data frame containing the low-latency data.

5. The terminal device according to claim 4, wherein the management unit, after transmitting the data frame, determines whether the remaining period of the TXOP is longer than a predetermined threshold, and if it determines that it is longer than the predetermined threshold, it further controls the unit to transmit a control frame for returning the TXOP.

6. A terminal device comprising: a communication circuit configured to transmit and receive wireless signals; and a management unit that uses the communication circuit to receive an RTS frame from an access point having a TXOP (transmission opportunity), and, in response to the reception of the RTS frame, controls the transmission of a CTS-to-Self frame addressed to itself if it contains low-latency data, and to transmit a data frame containing the low-latency data.

7. The terminal device according to claim 6, wherein the management unit, after transmitting the data frame, determines whether the remaining period of the TXOP is longer than a predetermined threshold, and if it determines that it is longer than the predetermined threshold, it further controls the device to transmit a control frame for returning the TXOP.

8. An access point comprising: a communication circuit configured to transmit and receive wireless signals; and a management unit that uses the communication circuit to control the transmission opportunity (TXOP) to receive a CTS frame from a destination device in response to the transmission of an RTS frame within a TXOP period, and to transmit a control frame for transferring the TXOP when it receives a first frame containing an information element indicating that the destination device has low-latency data.

9. The access point according to claim 8, wherein the management unit further controls the transmission of a second frame including an inquiry to determine whether the destination device has low-latency data.

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