Station device, access point device, control method, and program

Abstract

To provide a mechanism for sharing transmission opportunities acquired by a station device with other communication devices.SOLUTION: A station device capable of connecting to an access point device transmits a MU-RTS TXS Trigger frame to share a transmission opportunity with other communication devices when the station device itself has acquired a transmission opportunity.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a station device, an access point device, a control method, and a program for performing wireless communication. [Background technology]

[0002] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard is known as a communication standard for wireless local area networks (WLANs). The IEEE 802.11be standard and its successor, the IEEE 802.11bn standard, aim to reduce communication latency and improve channel utilization efficiency.

[0003] As a candidate technology, for example, Patent Document 1 discusses a function for sharing a transmission opportunity acquired by an access point device with a station device. This function may also be called a Triggered TXOP Sharing function. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-145264 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when communication is performed between an access point device and a station device, for example, when the station device secures a transmission opportunity to transmit data to the access point device, there are cases where the station device secures a long period of transmission opportunity just in case. In such a situation where the station device secures a transmission opportunity, in order for the station device to receive data from the opposite device, such as an access point device, it is necessary to release the secured transmission opportunity with a CF-End frame or the like. At this time, if the desired access point device does not win channel access, there is a problem that the transmission of data to be transmitted by the access point device to the station device is delayed. Also, even in a case where the access point device wins channel access, there is a problem that the communication overhead related to the procedure for releasing the transmission opportunity and the procedure for channel access using CSMA / CA is large. Also, as mentioned above, a mechanism for sharing the transmission opportunity acquired by the AP with the STA connected to the AP has already been technically examined. However, a specific mechanism for sharing the transmission opportunity acquired by the STA with other communication devices has not been technically examined, and there is a problem that the transmission opportunity acquired by the station cannot be shared with other communication devices.

[0006] The present invention has been made in consideration of at least one of the above problems, and has an object to provide a mechanism for a station device to share a transmission opportunity acquired by the station device with another communication device. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a station device as one aspect of the present invention is a station device connectable to an access point device, and is characterized in that when the station device has acquired a transmission opportunity, it has a transmission control means for transmitting an MU-RTS TXS Trigger frame that shares the transmission opportunity with other communication devices. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a mechanism for a station device to share a transmission opportunity acquired by the station device with another communication device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 illustrates a configuration of a network system. [Diagram 2] FIG. 2 is a diagram illustrating a hardware configuration of a communication device. [Diagram 3] FIG. 1 is a schematic diagram illustrating an example of a TXOP Sharing procedure. [Figure 4] 13 is a schematic diagram illustrating an example of a frame format of an MU-RTS TXS Trigger frame. [Diagram 5] This is a table for explaining the values ​​stored in the fields and the meanings indicated by the values. [Figure 6] 11 is a flowchart showing an example of communication control in a STA. [Figure 7] 13 is a flowchart illustrating an example of communication control in an AP. [Figure 8] FIG. 1 is a schematic diagram for explaining a specific example in which a Shared TXOP is used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0011] <First embodiment> An example of the configuration of a network system according to this embodiment is shown in Fig. 1. The network system according to this embodiment includes one access point device (hereinafter, also simply referred to as AP, AP STA, or access point) and two station devices (hereinafter, also simply referred to as STA, Non-AP STA, or stations).

[0012] The AP 101 and the STAs 102 and 103 are configured to be capable of communicating wireless frames conforming to the IEEE802.11bn standard, which is the successor to the IEEE802.11be standard and has a target maximum transmission speed of 46.08 Gbps.

[0013] IEEE is an abbreviation for the Institute of Electrical and Electronics Engineers. The main features of IEEE802.11bn, the successor standard to IEEE802.11be, are highly reliable communication, low latency communication, and improved throughput during congestion. Wireless frames communicated under this successor standard are also called UHR (Ultra High Reliability) PPDU. PPDU is an abbreviation for Physical Layer Protocol Data Unit.

[0014] The name UHR is a name given for convenience in consideration of the goals and features of the successor standard, and may be a different name when the standard is completed. Similarly, the name IEEE802.11bn may be a different name when the standard is completed. However, it should be noted that this specification and the appended claims are essentially applicable to all successor standards that are successors to the 802.11be standard.

[0015] The AP101 and the STAs 102 and 103 can also be configured to support wireless communication based on other communication standards such as Bluetooth (registered trademark), NFC, and Bluetooth (registered trademark) LE (Low Energy). NFC stands for Near Field Communication. The AP101 and the STAs 102 and 103 can also be configured to support wired communication using an Ethernet cable or wired communication using optical fiber. The AP101 and the STAs 102 and 103 can also be configured to support cellular wireless communication such as 5G and LTE (Long Term Evolution). Specific examples of the AP101 include, but are not limited to, a wireless LAN router and a personal computer (PC). The AP101 and the STAs 102 and 103 may also be information processing devices such as wireless chips that support the transmission and reception of UHR PPDUs. In this case, the AP101 and the STAs 102 and 103 can be configured to execute various controls using hardware circuits inside the wireless chip. The AP101 and the STAs 102 and 103 can also be configured to execute various processes by cooperation between a processor, memory, and hardware circuits such as an ASIP inside the wireless chip. ASIP stands for Application-specific instruction set processor.

[0016] Specific examples of the STA 102 include, but are not limited to, cameras, tablets, smartphones, PCs, mobile phones, video cameras, smart glasses, and wearable devices such as HMDs (head-mounted displays).

[0017] Returning to the explanation of Fig. 1, the AP 101 is an access point that supports a multi-band function that provides a network using a plurality of different frequency channels. In this embodiment, it is assumed that the AP 101 is a dual-band access point that provides, as an example, the 2.4 GHz band network 100 and a 5 GHz band network (not shown).

[0018] Furthermore, the AP 101 and the STA 102 of this embodiment can establish multiple communication links between the devices and perform Multi-Link communication for communication. Hereinafter, the communication link is also simply called a link. The AP 101 that performs Multi-Link communication is also called an AP Multi-Link Device (AP MLD) 101, and the STA 102 that performs Multi-Link communication is also called a non-AP MLD 102.

[0019] For example, the AP 101 can establish a link in the 2.4 GHz band with the STA 102 in the network 100 and communicate with them. In parallel with this, the AP 101 and the STA 102 can establish a link in the 5 GHz band, for example, and communicate with them. In this case, the STA 102 executes Multi-Link communication, which communicates via multiple links.

[0020] 1 shows a network system in which STA102 and STA103 are connected to one AP101 as an example, but the number of STAs constituting the network system may be greater than that shown in the figure. In addition, the AP101 and STA102-103 are described as supporting UHR PPDU communication (transmission and reception), but in addition to this, they can also be configured to support PPDU communication of a legacy standard that is a standard prior to the IEEE802.11bn standard. Specifically, the AP101 and STA102 can also be configured to support PPDU transmission and reception of the IEEE802.11a / b / g / n / ac / ax / be standard, etc.

[0021] Moreover, the frequency bands used by the AP 101 and the STAs 102 to 103 that can connect to an AP such as the AP 101 are not limited to the 2.4 GHz band and the 5 GHz band described above. For example, different frequency bands such as the 6 GHz band, the Sub 1 GHz band, and the millimeter wave band may be used. Furthermore, the AP 101 and the STAs 102 can communicate using bandwidths such as 20 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 540 MHz, and 640 MHz. The bandwidths used by each communication device are not limited to these.

[0022] In the IEEE802.11 series of standards, a frequency channel using a bandwidth of 20 MHz is specified as the minimum channel in the 2.4 GHz, 5 GHz, and 6 GHz frequency bands. This standard also defines multiple available channels in each of the 2.4 GHz, 5 GHz, and 6 GHz frequency bands. This standard also allows a channel to be used in combination with other adjacent channels.

[0023] The STAs such as the AP 101 and the STAs 102 to 103 perform carrier sense before transmitting data to determine whether transmission is possible. For example, the communication device measures the strength of a signal received on a channel that the device intends to use for transmission (received signal strength), and when the received signal strength exceeds a predetermined threshold, determines that a signal exists on the channel. The communication device also determines a transmission period during which a signal is transmitted based on information such as a Duration field included in the signal received on the channel. For example, the communication device stores the period indicated by the Duration field included in the received signal as a NAV (Network Allocation Vector) in the device. The communication device may handle the stored NAV as a period during which the device does not transmit. The operation of the communication device to set a period during which the device does not transmit based on information such as the Duration field of the received signal is also called setting a NAV. When the communication device determines that a signal exists on the channel by carrier sense, or when the period of the set NAV has not expired, the communication device may determine that transmission is not possible. In this case, the state of the channel may be called a busy state. On the other hand, a state in which no signal is detected on a channel in carrier sense and no NAV is set may be called an idle state. When a channel is in an idle state, the communication device may determine that transmission is possible. For example, when the AP 101 or the STAs 102 to 103 determine that transmission is possible as a result of performing carrier sense on a channel for a predetermined period of time, they may transmit, for example, a 160 MHz wide PPDU.

[0024] In addition, the AP 101 supports a Triggered TXOP Sharing function that shares the transmission opportunity secured by the AP 101 with STAs such as STA 102 and STA 103 connected to the AP 101. The AP 101 appropriately grasps the type and amount of data stored in the transmission buffers of the subordinate STAs based on BSR (Buffer Status Report) frames, etc. Based on the type and amount of data stored in the transmission buffers of the subordinate STAs, the AP 101 can share the transmission opportunity secured by the AP 101 with any one of the subordinate STAs. At this time, the AP 101 can start sharing the transmission opportunity by transmitting a MU-RTS TXS Trigger frame defined in the IEEE802.11be standard. TXS is an abbreviation for Triggered TXOP Sharing.

[0025] However, when communication is performed between an access point device and a station device, when the station device secures a transmission opportunity to transmit data to the access point device, there are cases where the station device secures a long period of transmission opportunity just to be safe. This transmission opportunity is secured by the RTS-CTS exchange procedure. RTS stands for Request To Send, and CTS stands for Request To Send. In a situation where the station device has secured a transmission opportunity in this way, in order for the station device to receive data from the opposite device, such as an access point device, it is necessary to release the secured transmission opportunity with a CF-End frame or the like. When the transmission opportunity is released, peripheral devices including the desired access point device compete for channel access. If the desired access point device does not win at this time, the transmission of data that the access point device should transmit to the station device will be delayed. Even if the access point device wins channel access, communication overhead may occur due to the procedure for releasing the transmission opportunity and the procedure for channel access using CSMA / CA. CSMA / CA stands for Carrier Sense Multiple Access with Collision Avoidance.

[0026] In view of this, this embodiment provides a mechanism for sharing a transmission opportunity acquired by a STA with other communication devices. More specifically, the communication rules are changed so that the MU-RTS TXS Trigger frame, which was previously only permitted to be transmitted by an AP, is permitted to be transmitted from the STA as necessary. In addition, in accordance with this change, the MU-RTS TXS Trigger frame is extended so that it can store information required for sharing a transmission opportunity from a STA and information for improving the convenience. By using the extended frame, it becomes possible for the STA to share the transmission opportunity acquired by the STA with other communication devices. The specific mechanism will be described below. The MU-RTS TXS Trigger frame is also simply called TXS TF, etc.

[0027] <Hardware configuration of communication device> 2 shows an example of a hardware configuration of a communication device (AP 101, STAs 102 to 103). The communication device includes a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207 as an example of the hardware configuration.

[0028] The storage unit 201 is configured with both or either one of a ROM and a RAM, and stores various information such as programs for performing various operations described below and communication parameters for wireless communication. RAM stands for Random Access Memory, and ROM stands for Read Only Memory. Note that, as the storage unit 201, in addition to memories such as ROM and RAM, storage media such as non-volatile storage devices such as hard disks and SSDs (Solid State Drives) may be used.

[0029] The control unit 202 is configured with, for example, a processor such as a CPU or MPU, an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), etc. Here, CPU stands for Central Processing Unit, and MPU stands for Micro Processing Unit. The control unit 202 executes the programs stored in the storage unit 201 and controls the entire device by operating hardware circuits such as the ASIC. The control unit 202 may control the entire device in cooperation with the programs stored in the storage unit 201 and an OS (Operating System).

[0030] The control unit 202 also controls the functional unit 203 to perform predetermined processing such as imaging, printing, and projection. The functional unit 203 is hardware for the device to perform predetermined processing. For example, when the communication device is a camera such as a digital still camera or a smartphone having a camera, the functional unit 203 is an imaging unit that performs imaging processing of surrounding images via a camera unit (not shown) of the communication device. For example, when the communication device is a printer, the functional unit 203 is a printing unit that performs printing processing on a sheet such as paper based on print data obtained from the outside via wireless communication. For example, when the communication device is a projector or smart glasses, the functional unit 203 is a projection unit that performs projection processing of image data and video data obtained from the outside via wireless communication. In the case of smart glasses, the projection surface is the retina of an end user. In the case of an HMD, the functional unit may be a display unit such as a micro OLED (Organic Light Emitting Diode). In this case, the display unit constituting the HMD performs display processing of image data and video data obtained from the outside via wireless communication.

[0031] The data processed by the function unit 203 may be data stored in the storage unit 201, or may be data communicated with other APs or STAs via the communication unit 206 described later. Furthermore, a communication device such as the AP 101 can provide a network storage function such as a network attached storage (NAS). The function is provided to other communication devices as a Web service such as a network storage service. For example, a communication device such as a STA connects to a network storage service provided by the AP 101 using a protocol such as SMB, FTP, or WebDAV. Then, the communication device such as the STA uploads files to the storage service and downloads files in the storage. The uploading and downloading data communication is also realized by communicating UHR PPDU between devices.

[0032] The input unit 204 receives various operations from the user. The output unit 205 performs various outputs to the user. Here, the output by the output unit 205 includes, for example, at least one of display on a screen, audio output by a speaker, and vibration output. Note that both the input unit 204 and the output unit 205 may be realized by one module, such as a touch panel. The output unit 205 functions as a display unit that presents information to the user. The input unit also functions as a receiving unit that receives user operations.

[0033] The communication unit 206 controls wireless communication conforming to the IEEE802.11 series standards and IP communication. In this embodiment, the communication unit 206 can execute transmission control for transmitting and reception control for receiving UHR PPDU, which is a wireless frame of the 802.11bn standard, and PPDU corresponding to the previous standard, in cooperation with the antenna 207. The antenna 207 is an antenna capable of transmitting and receiving signals in at least one of the frequency bands of the sub-GHz band, the 2.4 GHz band, the 5 GHz band, the 6 GHz band, and the millimeter wave band, for example. Note that, in this embodiment, a communication device having two antennas is illustrated as an example, but is not limited thereto. The number of antennas may be three or more.

[0034] When the communication device is compatible with the above-mentioned NFC standard, Bluetooth standard, wired communication standard, or the like, the communication unit 206 may be configured to control wireless communication or wired communication that complies with these communication standards.

[0035] <Sharing transmission opportunities> Next, an example of a process of sharing a transmission opportunity in this embodiment will be described with reference to Fig. 3. Fig. 3 is a schematic diagram showing an example of a process in which a STA in this embodiment shares a transmission opportunity with another communication device.

[0036] First, STA102 transmits an RTS frame 301 to AP101. STA102 stores a period corresponding to the transmission opportunity that STA102 wishes to acquire in the Duration field of the RTS frame. AP101 receives the RTS frame 301 and transmits a CTS frame 302 to STA102. AP101 stores a period corresponding to the transmission opportunity acquired by STA102 in the Duration field of the CTS frame. When the exchange of the RTS frame and the CTS frame is successful, STA102 occupies a channel corresponding to the network 100 and is ready to transmit data. Period 303 indicates the transmission opportunity acquired by STA102. The transmission opportunity is also called a TXOP. TXOP is an abbreviation for Transmission Opportunity.

[0037] The STA 102 that has acquired the TXOP transmits an uplink data frame 304 to the AP 101. This data frame is a data frame in the UHR PPDU format.

[0038] Next, the STA 102 judges whether or not to share the transmission opportunity with other communication devices such as the AP 101. The STA 102 can judge whether or not to share the transmission opportunity with other communication devices based on the tendency of past communication results, etc. Note that FIG. 3 illustrates, as an example, a case where it is judged to share the transmission opportunity with the AP 101.

[0039] The STA102 that has determined to share a transmission opportunity with the AP101 transmits an MU-RTS TXS Trigger frame304 for sharing a transmission opportunity with the AP101. The details of the frame304 will be described with reference to Figs. 4 and 5. The AP101 that has received the frame304 transmits a CTS frame 305a in response to the frame304. Next, the AP101 determines data to be transmitted during the period 306 of the TXOP shared using the frame304 based on the type of TXOP Sharing Mode indicated in the frame304 and the transmission data stored in the buffer. Hereinafter, the TXOP shared using the frame304 is also referred to as a Shared TXOP. Fig. 3 illustrates, as an example, a case in which downlink data addressed to the STA102 is determined as data to be transmitted.

[0040] The AP 101 transmits a downlink data frame 305b to the STA 102 during the Shared TXOP period. If there is no data to be transmitted during the Shared TXOP period, the AP 101 transmits a frame 307 including information indicating that the TXOP is to be returned to the STA 102. The frame 307 is a frame including a CAS Control field, and is a frame in which the RDG / More PPDU subfield included in the CAS Control field is set to 0. This CAS Control field is included in the HE Variant HT Control field.

[0041] The frames 305b and 307 may be included in the same UHR PPDU. The frame 307 may be a QoS Null frame.

[0042] The STA 102 that has received the frame 307 judges whether there is data to be transmitted during the remaining TXOP period 308. If it judges that there is data to be transmitted, it transmits the data frame to the outside. In FIG. 3, an example is illustrated in which an uplink data frame 309 to the AP 101 is transmitted.

[0043] Next, a specific format of the MU-RTS TXS Trigger frame 304 that is generated and transmitted by a STA such as the STA 102 for sharing a transmission opportunity with other communication devices will be described with reference to Figs.

[0044] Figures 4(A) to (C) show the specific format of the MU-RTS TXS Trigger frame, and Figures 5(A) to (B) are tables for explaining the values ​​that can be stored in the subfields of the MU-RTS TXS Trigger frame and their meanings.

[0045] The Frame Control Field includes a Type subfield and a Subtype subfield that indicate the frame type. The STA indicates that the frame is a trigger frame by setting the Type subfield to "01", which indicates a Control frame, and the Subtype subfield to "0010", which indicates a Trigger. The Duration field, RA field, and TA field conform to the contents of the MAC header of the Trigger frame, which is a control frame defined in the IEEE802.11ax standard. MAC is an abbreviation for Medium Access Control.

[0046] RA stands for Receiver Address, and the MAC address of the destination device is stored in the RA field. TA stands for Transmitter Address, and the MAC address of the source device is stored in the TA field. Note that the RA field of the trigger frame is assumed to store a broadcast address.

[0047] The Common Info field is a field that stores information common to the trigger frames, and includes each subfield shown in FIG. 5(B). The User Info List field stores one Special User Info field (not shown) and one User Info field shown in FIG. 5(C). The Special User Info field stores shared information that could not fit in the Common Info field. The User Info field stores information that identifies the other party with which the TXOP is shared, information that indicates the period, information for identifying the bandwidth to be shared, and the like. The Padding field stores padding data, and the FCS field stores information used in the Frame Check Sequence (FCS) that checks whether a frame is damaged during transmission.

[0048] Next, the Common Info field will be described with reference to FIG. 5(B). FIG. 5(B) illustrates an example in which the EHT Variant Common Info field is used. The Trigger Type subfield stores "3", which indicates that the type is MU-RTS (Multi-User RTS). The More TF subfield stores "0". The CS Required subfield stores "1" or "0". When the STA102 transmits a TXS TF in a congested environment, it stores "1" in the CS Required subfield. Storing "1" in the CS Required subfield means that carrier sensing is required at the other end sharing the transmission opportunity. Storing "0" means that carrier sensing is not required at the other end. The UL BW subfield is a subfield that indicates the bandwidth of the PPDU that transmits the MU-RTS type trigger frame. The bandwidth of the PPDU is indicated by combining the value of this subfield with the value of the UL Bandwidth Extension in the Special User Info field.

[0049] The GI And HE / EHT-LTF Type / Triggered TXOP Sharing Mode field stores the type of Triggered TXOP Sharing mode. Next, the Special User Info Field Flag subfield stores "0". Storing "0" means that the Special User Info field is provided.

[0050] Other subfields, UL Length, LDPC Extra Symbol Segment, Number of HE / EHT-LTF Symbols, AP Tx Power, Pre-FEC Padding Factor, PE Disambiguity, UL Spatial Reuse, and HE / EHT P160, are fields that store information used in trigger frames of other trigger types. In the case of TXS TF, which is an MU-RTS type, these fields are treated as reserved values. In addition, the Reserved subfield and EHT Reserved subfield are also treated as reserved values.

[0051] Next, the format of the User Info field will be described with reference to FIG. 5(C). FIG. 5(C) illustrates an example in which the EHT Varinat User Info field is used. The AID12 subfield stores information that identifies the other party with which the TXOP is shared. When sharing a TXOP with an AP such as AP101, since the AP is not assigned an AID, a specific value that indicates that the TXOP is addressed to the AP is set. Details will be described later. The RU Allocation subfield is a subfield that indicates whether the CTS frame, which is a response to the TXS TF, should be transmitted on the primary 20 MHz channel, the primary 40 MHz channel, the primary 80 MHz channel, the primary 160 MHz channel, or the 320 MHz channel. The Allocation Duration subfield is a subfield that stores the duration of the transmission opportunity shared with other communication devices, that is, the Shared TXOP. The PS160 subfield stores "1" when it indicates the 320 MHz channel. Otherwise, it stores "0". The Reserved subfield is treated as a reserved value.

[0052] Next, the meaning of the value stored in the Triggered TXOP Sharing Mode subfield will be described with reference to FIG. 6(A). Storing "0" means that it is a simple MU-RTS that does not execute the procedure for sharing TXOP. Storing "1" means that only MPDU addressed to the AP or the source device of the MU-RTS can be transmitted. More specifically, when the AP shares the TXOP with the STA, only data transmission to the AP is permitted in the Shared TXOP. On the other hand, when the STA shares the TXOP with the AP or other communication device as in this embodiment, only data transmission to the STA that transmitted the TXS TF is permitted in the Shared TXOP. MPDU is an abbreviation of MAC Protocol Data Unit, and means a so-called MAC frame. The MPDU to be transmitted may be an aggregated A-MPDU (Aggregation-MAC Protocol Data Unit).

[0053] Storing "2" means that the destination of the data transmission in the Shared TXOP is not limited. It is allowed to send the data to the AP, to the STA that sent the TXS TF, or to other STAs.

[0054] Storing "3" means that only MPDUs addressed to the STA that sent the TXS TF and MPDUs stored in the SA field by the STA that sent the TXS TF are permitted to be transmitted. In other words, it means that only data transmission related to the STA that sent the TXS TF is permitted in the Shared TXOP.

[0055] A communication device such as AP 101 that has received a TXOP from STA 102 identifies the type of transmission data that is permitted for the Sharing Mode indicated by the TXS TF, and then determines the data to be transmitted in the Shared TXOP, taking into consideration the identified type of transmission data that is permitted and the priority of the data stored in the buffer.

[0056] Furthermore, the meaning of the values ​​stored in the AID12 subfield of the User Info field will be explained using FIG. 6(B). Storing 0 or 2045 indicates that it is a RA-RU (Random Access-Resource Unit). RA-RU is used for uplink random access procedure. Storing 2046 indicates that it is an unallocated RU (Resource Unit). These values ​​are used when using trigger frames of other trigger types, and are not used in TXS TF. 4095 indicates the start of the Padding field, and is not used in the User Info field. The Padding field mentioned above is composed of all bits 1. When expressed in binary, 4095 is equivalent to 12 consecutive bits of 1 stored. A receiving terminal that recognizes that 12 consecutive bits of 1 are stored can recognize that it has completed reception of the User Info field and has reached the interpretation phase of the Padding field.

[0057] On the other hand, a value of 1-2007 means that the User Info field is addressed to a STA whose AID (Association Identifier) ​​is equal to this value. The AID is identification information that is assigned when a STA connects to an AP to identify the STA. AID is assigned a value that does not overlap with other STAs within the same network so that the destination STA can be uniquely identified. In other words, storing any value of 1-2007 in the AID12 subfield means providing information that identifies the destination STA that shares the TXOP.

[0058] In this embodiment, 2008 is used as an example of a specific value for identifying the AP described above. Storing 2008 in the AID12 subfield means that the User Info is addressed to an AP corresponding to the BSS Color value included in the PHY preamble of the UHR PPDU including the TXS TF. First, BSS Coloring will be described. BSS Coloring is a mechanism for identifying which network a frame is addressed to in an environment where access points are densely arranged by giving an identifier called a color code to a frame of the physical layer. An AP such as AP101 sets a BSS Color different from that of neighboring APs to itself, and shares the BSS Color with its subordinate STAs. When transmitting a frame, the AP or STA includes a BSS Color corresponding to the network to which it belongs in the U-SIG of the PHY preamble. U-SIG is an abbreviation for Universal Signal Field. The AP or STA compares the BSS Color of the network it manages with the value of the BSS Color field of the PHY preamble. Then, the AP or STA can distinguish whether the frame is addressed to the network to which it belongs or to another network in the vicinity based on whether the comparison results match. This mechanism was established primarily to realize OBSS_PD-based spatial reuse.

[0059] If an AP or STA determines through the above comparison that the PPDU is addressed to the network to which it belongs, it interprets the MAC frame included in the data section of the PPDU. Therefore, when a PPDU containing a TXS TF, which is a MAC frame, is received, the TXS TF is interpreted. If the interpretation result shows that 2008 is stored in the AID12 subfield of the TXS TF, it can be identified as a TXS TF for sharing a TXOP with an AP belonging to the same network. If the AP or STA is an AP of the same network, it can determine that the TXOP has been shared and use it for data transmission as appropriate. On the other hand, if the AP or STA is a STA that belongs to the same network, or if it does not belong to the same network, it can set the NAV.

[0060] <Communication Control> Next, communication control for sharing a TXOP according to the present embodiment will be described with reference to the flowcharts of Fig. 6 and Fig. 7 and the schematic diagram of Fig. 8. Fig. 8 is a schematic diagram for explaining a specific example in which a shared TXOP is used.

[0061] Each process shown in the flowchart of FIG. 6 is executed by a processor of the control unit 202 of an STA represented by STA102, STA103, etc., executing a computer program stored in the storage unit 201. Note that some processes such as transmission and modulation are realized by the processor of the control unit 202, various processors, ASIC, DSP, FPGA, antenna, and ASIC, DSP, FPGA, etc. constituting the communication unit 206 in cooperation with each other. Note that this is not limited to this, and it is of course possible to configure the control unit such as an ASIC or processor inside the communication unit 206 to cooperate with the antenna to execute each process shown in the flowchart. Also, each process shown in the flowchart of FIG. 7 is executed by a processor of the control unit 202 of the AP101, executing a computer program stored in the storage unit 201. Note that some processes such as transmission and modulation are realized by the processor of the control unit 202, various processors, ASIC, DSP, FPGA, antenna, and ASIC, DSP, FPGA, etc. constituting the communication unit 206 in cooperation with each other. It should be noted that the present invention is not limited to this, and it is of course possible to configure the communication unit 206 so that a control unit such as an ASIC or processor in the communication unit 206 cooperates with the antenna to execute each process shown in the flowchart.

[0062] 6 and 7 are flowcharts showing an excerpt of control relating to sharing of TXOPs, which is closely related to this embodiment.

[0063] In S601, the control unit 202 of an STA, such as STA102 or STA103, determines whether there is data to transmit. Specifically, the control unit 202 determines whether the transmission data (MAC frames such as data frames) has been stored in the transmission buffer, and if it is determined that the data has been stored in the transmission buffer, the process proceeds to S602. On the other hand, if it is determined that the transmission data has not been stored in the transmission buffer, the control unit 202 waits for the transmission data to be stored.

[0064] Next, in S602, the control unit 202 performs a process of securing a TXOP in cooperation with each unit such as the communication unit 206 and the antenna 207. Specifically, the RTS-CTS exchange procedure described in FIG. 3 is executed to secure a TXOP.

[0065] Next, in S603, the control unit 202 cooperates with each unit to transmit a UHR PPDU including transmission data to another communication device such as the AP 101. Next, in S604, the control unit 202 determines whether or not to share a transmission opportunity with another communication device such as the AP. If it is determined that a transmission opportunity is to be shared with another communication device such as the AP, the process proceeds to S608. On the other hand, if it is not determined that a transmission opportunity is to be shared with another communication device such as the AP, the process proceeds to S605. Specifically, the control unit 202 can determine whether or not to share a transmission opportunity with another communication device such as the AP based on the tendency of past communication results, etc.

[0066] In S605, the control unit 202 judges whether or not there is other data to be communicated. Specifically, when transmission data is stored in the transmission buffer, it is judged that there is other data to be communicated. When it is judged that there is other data to be communicated, the process proceeds to S612, and when it is not judged that there is other data to be communicated (i.e., there is no data to be transmitted), the process proceeds to S607.

[0067] In S607, the control unit 202 cooperates with each unit to transmit a PPDU including a CF-End frame, and the process proceeds to S601. The process of transmitting the frame means releasing the remaining TXOP.

[0068] Next, the control when it is determined that the TXOP is to be shared with another communication device will be described. In S608, the control unit 202 generates an MU-RTS TXS Trigger frame for sharing the TXOP with another communication device. Next, the control unit 202 cooperates with each unit to transmit the generated MU-RTS TXS Trigger frame. At this time, the control unit 202 determines the value of the TXOP Sharing Mode to be included in the TXS TF based on the trend of past communication results, etc. For example, when it is estimated that there is data to be received from the AP based on the trend of past communication results, etc., the TXOP Sharing Mode is set to "1". Also, when it is estimated that the data to be transmitted to the AP is the data destined for another communication device (e.g., STA103) etc. and should be transmitted to another communication device such as STA102 as soon as possible, the TXOP Sharing Mode is set to "2" or "3". Note that when the other party to share the TXOP is the AP, the control unit 202 stores 2008 in the AID12 subfield of the MU-RTS TXS Trigger frame.

[0069] Next, in S609, the control unit 202 cooperates with each unit to control reception of frames addressed to itself. When a frame addressed to itself is received, the control unit 202 appropriately interprets the data frame and control frame contained in the received frame, performs control based on the interpretation result, and transfers the data obtained as a result of the interpretation to a higher layer (not shown) such as an IP layer.

[0070] In S610, the control unit 202 judges whether the frame contains information indicating Return for returning the TXOP. Specifically, when a frame in which the RDG / More PPDU subfield included in the CAS Control field is set to 0 or a QoS Null frame is received, it judges that the frame contains information indicating Return. If it judges that the frame contains information indicating Return, the process proceeds to S612, and if it does not judge that the frame contains information indicating Return, the process proceeds to S611. In S611, it judges whether the Shared TXOP shared with other communication devices by the frame of S608 has expired. If it judges that the Shared TXOP has expired, the process proceeds to S612, and if it judges that the Shared TXOP has not expired, the process proceeds to control of S609, where reception control and monitoring control of the return of the TXOP are performed.

[0071] In S612, the control unit 202 judges whether the TXOP secured in S602 will expire. If it is judged that the TXOP will expire, the process proceeds to S613. On the other hand, if it is judged that the TXOP will not expire (i.e., if it is judged that the secured TXOP still remains), the process proceeds to S603.

[0072] In S613, it is determined whether or not to turn off the power. If it is determined that the power should be turned off, shutdown control is performed and the series of controls is terminated. On the other hand, if it is determined that the power should not be turned off, the process proceeds to S601.

[0073] Through the series of processes described above, an STA device such as STA102 can share a TXOP with other communication devices such as AP101, and prompt desired other communication devices to send data to itself or to perform other data transfer processes.

[0074] Next, the control in another communication device that receives a shared TXOP will be described with reference to Fig. 7. In this embodiment, the case where the AP 101 receives a shared TXOP from the STA 102 will be described as an example.

[0075] In S701, the control unit 202 of the AP101 cooperates with each unit such as the communication unit 206 and the antenna 207 to determine whether data addressed to the AP101 has been received from a STA such as STA102. If it determines that data addressed to itself has been received from a STA such as STA102, the process proceeds to S702. If it determines that data addressed to itself has not been received from a STA such as STA102, the process proceeds to S700, and control is performed to wait for reception. At this time, the STA of the opposite device may transmit a frame after securing a TXOP in advance by exchanging RTS-CTS in advance. In addition, the opposite device may transmit a frame and secure a TXOP at the same time. In this case, a frame is transmitted in which a TXOP corresponding to the transmission time of the frame (or the exchange time including an immediate ACK) is stored in the TXOP field of the U-SIG of the PHY preamble or the Duration field of the MAC frame. In this case, the time for transmitting the frame (or the exchange time including an immediate ACK) is equal to the TXOP. The control unit 202 temporarily stores the TXOP secured by the opposite device.

[0076] In S702, the control unit 202 cooperates with each unit to control reception of frames addressed to itself. When a frame addressed to itself is received, the control unit 202 appropriately interprets the data frame and control frame contained in the received frame, performs control based on the interpretation result, and transfers the data obtained as a result of the interpretation to a higher layer (not shown) such as an IP layer.

[0077] In S703, the control unit 202 judges whether the TXOP reserved by the STA, which is the opposite device, has expired. If it is judged that the TXOP reserved by the STA has expired, the series of reception processes is terminated. On the other hand, if it is judged that the TXOP reserved by the STA has not expired, the process returns to S701 and waits for further data to be received.

[0078] In S704, the control unit 202 cooperates with each unit to determine whether or not an MU-RTS TXS Trigger frame addressed to the AP 101 has been received from a STA such as the STA 102. If it is determined that an MU-RTS TXS Trigger frame addressed to the AP 101 has been received, the process proceeds to S705. If it is determined that an MU-RTS TXS Trigger frame addressed to the AP 101 has not been received, the process proceeds to S701. Specifically, it determines whether or not a MAC frame included in the data portion of a PPDU identified as having the same BSS Color is an MU-RTS type trigger frame. It then determines whether or not 1 to 3 is specified in the GI and HE / EHT-LTF Type / Triggered TXOP Sharing Mode field of the trigger frame. If it is an MU-RTS type trigger frame and 1 to 3 is specified in the Sharing Mode field, it determines that an MU-RTS TXS Trigger frame addressed to itself has been received. In this case, it further determines that an MU-RTS- TXS Trigger frame addressed to itself has been received if 2008 is specified in the AID12 subfield of the frame. If not, it is determined that the MU-RTS TXS Trigger frame addressed to itself has not been received. Although not shown due to space limitations, when other control frames are received, the control unit 202 performs appropriate control corresponding to the received other control frames.

[0079] In S705, the control unit 202 cooperates with each unit to control the transmission of the CTS frame to a channel specified based on the value specified in the RU Allocation subfield and the bandwidth in which the PPDU of the TXS TF is transmitted. Next, the control unit 202 determines and transmits transmission data based on the Triggered TXOP Sharing Mode indicated by the TXS TF and the priority of the data buffered in the transmission buffer.

[0080] In S706, the control unit 202 judges whether there is other data to be transmitted. If it is judged that there is other data to be transmitted, the process proceeds to S708, and if it is judged that there is no other data to be transmitted, the process proceeds to S707.

[0081] In S707, the control unit 202 cooperates with each unit to transmit a frame including information indicating Return for returning a TXOP. Specifically, the control unit 202 may transmit a frame in which 0 is set in the RDG / More PPDU subfield included in the CAS Control field, or a QoS Null frame.

[0082] In S708, the control unit 202 judges whether the shared TXOP expires. If it is judged that the shared TXOP expires, the process proceeds to S701. If it is judged that the shared TXOP does not expire (i.e., if the shared TXOP available for data transmission still remains), the process proceeds to S705.

[0083] The above-described processing enables the AP 101 to transmit data using Shared TXOP.

[0084] Here is a note on control when Shared TXOP is successful. There is an agreement that IEEE802.11be non-AP EHT STAs will use less favorable parameters in contention access if transmission is successful during the Shared TXOP period. Specifically, STAs that successfully transmit during the Shared TXOP period must use less favorable parameters indicated by the MU EDCA parameters for a certain period of time indicated by the MU EDCA Timer. EDCA is an abbreviation for Enhanced distributed channel access, and MU EDCA is an abbreviation for Multi-User EDCA.

[0085] On the other hand, even if data transmission is successful in the Shared TXOP shared by the TXS TF, the AP 101 of this embodiment controls not to change the EDCA parameters to unfavorable parameters corresponding to the MU EDCA parameters. This control is performed in consideration of the fact that putting a disadvantage on the contention access of the communication device that has the role of managing the network as an AP, may lead to a decrease in the efficiency of the entire network.

[0086] Finally, a specific example of using Shared TXOP will be described with reference to Fig. 8. For example, consider a case where an external server, STA102 such as HMD, and STA103 such as nearby HMD cooperate to build an interactive application system or game system. In particular, STA102 is performing live distribution within the game system, and tends to secure TXOP as much as possible.

[0087] In this case, it is basically expected that data traffic from STA102 to the outside will be large. However, in addition to that, STA102 may want to transmit small amounts of data or information to nearby STA103, or an external server may want to provide small amounts of data or information to STA102. In consideration of these, STA102 realizes data communication for this use case by appropriately sharing TXOP with AP101. For example, STA102 uses the TXOP it has secured to transmit data addressed to STA103 to AP101. Next, STA102, which estimates that the data should be transferred to STA103 urgently, transmits a TXS TF with "2" or "3" stored in the TXOP Sharing Mode. AP101, which has received the TXS TF, transfers the data addressed to STA103 received from STA102 during the Shared TXOP period to STA103. In addition, AP101 transmits data addressed to STA102 received from an external server or the like during the Shared TXOP period.

[0088] The estimation process of whether to share a TXOP may be realized by the application and the communication layer below the IP layer in cooperation with each other, or may be estimated only by the communication layer below the IP layer based on the information such as the transmission priority specified by the application. In addition, the estimation may utilize the past communication records described above.

[0089] <Modification> In the above embodiment, a case is exemplified where a specific value of 2008 is specified in the AID12 subfield in the TXS TF to indicate that the message is addressed to an AP. However, the specific value is not limited to this. Any value that is not included in the range of 0 to 2007 and does not fall under any of 2045, 2046, and 4095, i.e., any value currently reserved, may be defined as a specific value indicating that the message is addressed to an AP. For example, 2047, 4094, etc. may be defined as a specific value.

[0090] Also, it can be combined with values ​​of other fields to indicate that it is addressed to an AP. For example, one of the Reserved subfields of the Common Info field is diverted to a field to identify whether it is a trigger frame issued by an AP or a trigger frame issued by a STA. If the diverted field indicates that it is a trigger frame issued by a STA and the AID12 subfield indicates "0", it can be configured to be considered as a TXS TF addressed to an AP. As another modified example, if the diverted field indicates that it is a trigger frame issued by a STA and the AID12 subfield indicates "2045", it can be configured to be considered as a TXS TF addressed to an AP. Note that if the diverted field indicates that it is a trigger frame issued by an AP, "0" or "2045" can be configured to be considered as RA-RU as before.

[0091] In the above embodiment, it is assumed that the Common Info field and the User Info field are EHT Variant fields, but this is not limiting. The UHR Variant Common Info field and the UHR Variant User Info field may be used.

[0092] In the above embodiment, the case where the other communication device sharing the TXOP is an AP is described as an example, but the present invention is not limited to this. For example, the present invention can also be used for sharing the TXOP when the STA and another STA establish a direct link and communicate with each other. For example, when the STA102 establishes a direct link with the STA103, the STA102 that has acquired the TXOP can transmit the above-mentioned TXS TF to the STA103 to share the TXOP.

[0093] Also, the STA102 may be a device that operates as a client of Wi-Fi Direct (registered trademark), and another communication device may be a communication device that operates as a group owner of the Wi-Fi Direct to which the STA102 is connected. In this case, the STA102 can transmit a TXS TF to another communication device that is a group owner of Wi-Fi Direct, and share a TXOP with the group owner. In this case, since the group owner is an entity that operates like an AP, the AID12 subfield may be set to a value indicating the above-mentioned AP destination. As described above, the above-mentioned mechanism can also be provided for sharing transmission opportunities in P2P (Peer-to-Peer) communication such as a direct link or Wi-Fi Direct.

[0094] <Other embodiment 1> The disclosure of this embodiment also includes the following configuration.

[0095] (Configuration 1) A station device connectable to an access point device, A station device characterized by having a transmission control means for transmitting an MU-RTS TXS Trigger frame for sharing a transmission opportunity with other communication devices when the station device has acquired a transmission opportunity.

[0096] (Configuration 2) 2. The station device according to configuration 1, wherein the other communication device is an access point device to which the station device is connected.

[0097] (Configuration 3) A station device as described in configuration 1 or 2, characterized in that a specific value not included in the range of 0 to 2007 is stored in the AID12 subfield of the User Info field of the MU-RTS TXS Trigger frame that shares a transmission opportunity with the access point device.

[0098] (Configuration 4) 2. The communication device according to configuration 1, wherein the other communication device is another station device with which the station device has established a direct link.

[0099] (Configuration 5) A station device according to any one of configurations 1 to 3, characterized in that a Triggered TXOP Sharing Mode subfield of the MU-RTS TXS Trigger frame is set to 2.

[0100] (Configuration 6) A station device according to any one of configurations 1 to 3, characterized in that a Triggered TXOP Sharing Mode subfield of the MU-RTS TXS Trigger frame is set to 3.

[0101] (Configuration 7) The station device according to configuration 5 or 6, characterized in that when a frame including a CAS Control field in which the RDG / More PPDU subfield included in the CAS Control field is set to 0 is received from the other communication device and data to be transmitted is stored in a buffer, the transmission control means transmits a frame including the data to be transmitted to a destination of the data to be transmitted.

[0102] (Configuration 8) 8. A station device according to any one of configurations 1 to 7, characterized in that the MU-RTS TXS Trigger frame includes an EHT Variant User Info field.

[0103] (Configuration 9) 8. A station device according to any one of configurations 1 to 7, characterized in that the MU-RTS TXS Trigger frame includes a UHR Variant User Info field.

[0104] (Configuration 10) A station device described in any one of configurations 1 to 8, characterized in that when the transmission opportunity is acquired and data to be transmitted to the access point device is stored in a buffer, the transmission control means transmits a frame in UHR PPDU format including the data to the access point device.

[0105] (Configuration 11) A station device described in any one of configurations 1 to 9, characterized in that the station device is a device operating as a client of Wi-Fi Direct (registered trademark), and the other communication device transmits a MU-RTS TXS Trigger frame to the other communication device that is the group owner of the Wi-Fi Direct to which the station device is connected.

[0106] (Configuration 12) An access point device, a reception control means for receiving, when a station device connected to the access point device has acquired a transmission opportunity, from the station device, a MU-RTS TXS Trigger frame for sharing a transmission opportunity with the access point device; and a transmission control means for transmitting a data frame to another communication device during a transmission opportunity period shared by the MU-RTS TXS Trigger frame after receiving the MU-RTS TXS Trigger frame.

[0107] (Configuration 13) The access point device described in configuration 12, characterized in that even if the access point device successfully transmits a data frame to another communication device during the period of the transmission opportunity shared by the MU-RTS TXS Trigger frame, the access point device does not change the EDCA parameters used in contention access to parameters corresponding to the MU EDCA parameters.

[0108] (Configuration 14) A method for controlling a station device connectable to an access point device, comprising: A control method comprising a transmission control step of transmitting an MU-RTS TXS Trigger frame for sharing a transmission opportunity with other communication devices when the station device has acquired a transmission opportunity.

[0109] (Configuration 15) A method for controlling an access point device, comprising: a reception control step of receiving, from the station device connected to the access point device, a MU-RTS TXS Trigger frame for sharing a transmission opportunity with the access point device when the station device has acquired a transmission opportunity; a transmission control process for transmitting a data frame to another communication device during a period of a transmission opportunity shared by the MU-RTS TXS Trigger frame after receiving the MU-RTS TXS Trigger frame.

[0110] (Configuration 16) A program for causing a computer to execute the station device control method according to configuration 14.

[0111] (Configuration 17) 16. A program for causing a computer to execute the control method for the access point device according to claim 15.

[0112] <Other embodiment 2> The present invention can also be realized by supplying a program for implementing one or more of the functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0113] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0114] 101 AP 102 STA 103 STA 202 Control section

Claims

1. A station device connectable to an access point device, The station device is characterized by comprising a transmission control means for transmitting an MU-RTS TXS Trigger frame for sharing a transmission opportunity with other communication devices when the station device has acquired a transmission opportunity.

2. 2. The station device according to claim 1, wherein the other communication device is an access point device to which the station device is connected.

3. The station device according to claim 1, characterized in that a specific value not included in the range of 0 to 2007 is stored in the AID12 subfield of the User Info field of the MU-RTS TXS Trigger frame that shares a transmission opportunity with the access point device.

4. 2. The station device according to claim 1, wherein the other communication device is another station device with which the station device has established a direct link.

5. The station device according to claim 1 , wherein a Triggered TXOP Sharing Mode subfield of the MU-RTS TXS Trigger frame is set to 2.

6. The station device according to claim 1 , wherein a Triggered TXOP Sharing Mode subfield of the MU-RTS TXS Trigger frame is set to 3.

7. 6. The station device according to claim 5, wherein when a frame including a CAS Control field in which an RDG / More PPDU subfield included in the CAS Control field is set to 0 is received from the other communication device and data to be transmitted is stored in a buffer, the transmission control means transmits the frame including the data to be transmitted to a destination of the data to be transmitted.

8. 7. The station device according to claim 6, wherein when a frame including a CAS Control field in which an RDG / More PPDU subfield included in the CAS Control field is set to 0 is received from the other communication device and data to be transmitted is stored in a buffer, the transmission control means transmits a frame including the data to be transmitted to a destination of the data to be transmitted.

9. 9. The station device according to claim 1, wherein the MU-RTS TXS Trigger frame includes an EHT Variant User Info field.

10. 9. The station device according to claim 1, wherein the MU-RTS TXS Trigger frame includes a UHR Variant User Info field.

11. A station device as described in any one of claims 1 to 8, characterized in that when the transmission opportunity is acquired and data to be transmitted to the access point device is stored in a buffer, the transmission control means transmits a frame in UHR PPDU format including the data to the access point device.

12. The station device according to any one of claims 1 to 8, characterized in that the station device is a device that operates as a client of Wi-Fi Direct (registered trademark), and the other communication device transmits a MU-RTS TXS Trigger frame to the other communication device that is a group owner of the Wi-Fi Direct to which the station device is connected.

13. An access point device, a reception control means for receiving, when a station device connected to the access point device has acquired a transmission opportunity, from the station device, an MU-RTS TXS Trigger frame for sharing a transmission opportunity with the access point device; and a transmission control means for transmitting a data frame to another communication device during a period of a transmission opportunity shared by the MU-RTS TXS Trigger frame after receiving the MU-RTS TXS Trigger frame.

14. 14. The access point device according to claim 13, characterized in that even if the access point device successfully transmits a data frame to another communication device during the period of the transmission opportunity shared by the MU-RTS TXS Trigger frame, the access point device does not change the EDCA parameters used in contention access to parameters corresponding to the MU EDCA parameters.

15. A method for controlling a station device connectable to an access point device, comprising: The control method includes a transmission control step of transmitting, when the station device has acquired a transmission opportunity, an MU-RTS TXS Trigger frame for sharing the transmission opportunity with other communication devices.

16. A method for controlling an access point device, comprising: a reception control step of receiving, when a station device connected to the access point device has acquired a transmission opportunity, an MU-RTS TXS Trigger frame for sharing a transmission opportunity with the access point device from the station device; and a transmission control step of transmitting a data frame to another communication device during a period of a transmission opportunity shared by the MU-RTS TXS Trigger frame after receiving the MU-RTS TXS Trigger frame.

17. A program for causing a computer to execute the method for controlling a station device according to claim 15.

18. A program for causing a computer to execute the control method for an access point device according to claim 16.

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