Wireless communication device and wireless communication method

Abstract

To improve transmission efficiency.SOLUTION: A radio communication device performs communication with a base station device and other radio communication devices. The radio communication device includes: a reception section which receives a radio frame; a transmission section which transmits the radio frame; and a control section which controls transmission and reception of the radio frame. The reception section receives the radio frame, a PHY header of the received radio frame is demodulated, and the radio frame is transmitted to be within a NAV of the PHY header which is being currently received when first information for identifying a radio system included in the PHY header which is being currently received shows a radio system to which the radio communication device belongs and when a prescribed condition is satisfied.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to a communication device and a communication method. [Background technology]

[0002] The Institute of Electrical and Electronics Engineers Inc. (IEEE) continues to update the IEEE802.11 specification, the wireless local area network (WLAN) standard, to achieve faster communication speeds and more efficient frequency utilization. WLANs enable wireless communication using unlicensed bands, which can be used without a license from a national or regional authority. For personal use, such as at home, wireless Internet access from within a home has become possible by incorporating a WLAN access point function into a line termination device for connecting to a wide area network (WAN) line, such as the Internet, or by connecting a WLAN access point device (AP) to the line termination device. In other words, WLAN station devices (STAs) such as smartphones and PCs can connect to a WLAN access point device to access the Internet.

[0003] The IEEE802.11ax specification was finalized in February 2021, and specification-compliant wireless LAN devices and communication devices such as smartphones and PCs (personal computers) equipped with such wireless LAN devices have appeared on the market as Wi-Fi6 (a registered trademark, the name given to IEEE-802.11ax-compliant products certified by the Wi-Fi Alliance). Currently, standardization activities for IEEE802.11be, the successor to IEEE802.11ax, have begun. With the rapid spread of wireless LAN devices, the IEEE802.11be standard is examining how to further improve throughput per user in environments with dense deployment of wireless LAN devices.

[0004] IEEE802.11n and later standards have introduced frame aggregation as a technology to increase throughput by reducing overhead. Frame aggregation is broadly divided into A-MSDU (Aggregated MAC Service Data Unit) and A-MPDU (Aggregated MAC Protocol Data Unit). Frame aggregation improves transmission efficiency by enabling the transmission of large amounts of data at once, but it also increases the possibility of transmission errors. For this reason, IEEE802.11ax and later standards are expected to increase throughput by not only improving transmission efficiency through frame aggregation but also by providing efficient error control for each MPDU. In addition, mechanisms to increase TXOPs, such as OFDMA and inter-BSS spatial reuse, have been adopted, which are expected to improve transmission efficiency. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] IEEE 802.11-20 / 1046-08-00be, July.2020 Summary of the Invention [Problem to be solved by the invention]

[0006] As wireless LAN devices become more widespread, the areas in which they are used are expanding in urban areas, with some locations seeing double-digit numbers of wireless LAN devices in use. When traffic increases in such congested environments, the CSMA (Carrier Sense Multiple Access)-based wireless medium access used in the IEEE802.11 specification reduces transmission efficiency by reducing the time available for TXOPs due to collisions and exposed terminals. The IEEE802.11ax standard employs Inter-BSS spatial reuse technology to partially alleviate this issue, but this is still not sufficient.

[0007] The present invention has been made in consideration of the above circumstances, and discloses a communication device and a communication method that increase the opportunities to secure TXOP and improve transmission efficiency by realizing spatial reuse operation within the same wireless system (BSS). [Means for solving the problem]

[0008] The communication device and communication method according to the present invention for solving the above-mentioned problems are as follows.

[0009] (1) That is, a communication device according to one embodiment of the present invention is a wireless communication device that communicates with a base station device and other wireless communication devices, and includes a receiving unit that receives wireless frames, a transmitting unit that transmits wireless frames, and a control unit that controls the transmission and reception of wireless frames, wherein the receiving unit receives the wireless frame, demodulates the PHY header of the received wireless frame, and if first information for identifying a wireless system included in the currently received PHY header indicates the wireless system to which the wireless communication device belongs and if second information included in the currently received PHY header is specific information, transmits the wireless frame so that it fits within the NAV of the currently received PHY header.

[0010] (2) Furthermore, in a communication device according to one embodiment of the present invention, the second information is information indicating a sector, and the communication device transmits the radio frame when the second information does not indicate the sector to which the wireless communication device belongs.

[0011] (3) Furthermore, in a communication device according to one embodiment of the present invention, the second information is information indicating whether the communication is for a base station device, and the communication device transmits the radio frame when the second information indicates that the communication is for a base station device.

[0012] (4) Furthermore, in a communication device according to one embodiment of the present invention, the second information is information that identifies a destination wireless communication device, and the communication device transmits the wireless frame when the second information does not indicate the destination of the wireless frame to be transmitted.

[0013] (5) Also, a communication device according to one embodiment of the present invention is characterized in that the second information is information indicating whether or not it is a direct link, and the wireless frame is transmitted when the second information indicates a direct link.

[0014] (6) Furthermore, a communication method according to one embodiment of the present invention receives a wireless frame, demodulates a PHY header of the received wireless frame, and if first information for identifying a wireless system included in the currently received PHY header indicates a wireless system to which the wireless communication device belongs and second information included in the currently received PHY header is specific information, transmits the wireless frame so that it fits within the NAV of the currently received PHY header. [Effects of the Invention]

[0015] According to the present invention, it is possible to contribute to improving communication efficiency in communication using a wireless communication device conforming to the IEEE802.11 standard. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of division of radio resources according to an aspect of the present invention. [Figure 2] FIG. 10 is a diagram illustrating an example of a frame configuration according to an aspect of the present invention. [Figure 3] FIG. 10 is a diagram illustrating an example of a frame configuration according to an aspect of the present invention. [Figure 4] FIG. 1 illustrates an example of communication according to an aspect of the present invention. [Figure 5] 1 is a diagram illustrating an example of a configuration of a communication system according to an aspect of the present invention. [Figure 6] 1 is a block diagram illustrating an example of a configuration of a wireless communication device according to an aspect of the present invention. [Figure 7] 1 is a block diagram illustrating an example of a configuration of a wireless communication device according to an aspect of the present invention. [Figure 8] FIG. 2 is a schematic diagram of a radio frame transmission according to an aspect of the present invention. [Figure 9] FIG. 1 is a schematic diagram illustrating an example of a frame format according to an aspect of the present invention. [Figure 10] FIG. 2 is a schematic diagram of a radio frame transmission according to an aspect of the present invention. [Figure 11] FIG. 1 is a schematic diagram of sector operation according to one aspect of the present invention. [Figure 12] FIG. 2 is a schematic diagram of a radio frame transmission according to an aspect of the present invention. [Figure 13] FIG. 2 is a message flow diagram between wireless communication devices according to one aspect of the invention. [Figure 14] FIG. 1 is a timing chart according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] The communication system in this embodiment includes an access point device (also referred to as a base station device) and multiple station devices (also referred to as terminal devices). A communication system or network configured with the access point device and the station devices is called a basic service set (BSS, management range, cell). A station device according to this embodiment can have the functions of an access point device. Similarly, an access point device according to this embodiment can have the functions of a station device (terminal device, wireless communication device). Therefore, hereinafter, when simply referring to a communication device, the communication device can refer to both a station device and an access point device. An access point device may also communicate with other access point devices.

[0018] The base station device and terminal devices within the BSS communicate based on CSMA / CA (Carrier sense multiple access with collision avoidance). This embodiment focuses on infrastructure mode, in which a base station device communicates with multiple terminal devices. However, the method of this embodiment can also be implemented in ad hoc mode, in which terminal devices communicate directly with each other. In ad hoc mode, terminal devices form a BSS in place of a base station device. A BSS in ad hoc mode is also referred to as an IBSS (Independent Basic Service Set). Hereinafter, terminal devices forming an IBSS in ad hoc mode can also be considered as base station devices. The method of this embodiment can also be implemented in P2P (Peer-to-Peer) communication, in which terminal devices communicate directly with each other. One method for implementing P2P communication is Tunneled Direct Link Setup (TDLS). In TDLS, traffic flowing between terminal devices connected to a base station device is transmitted and received directly between the terminal devices without passing through the base station device. The method of this embodiment can also be implemented using WiFi Direct (registered trademark). In WiFi Direct, terminal devices form groups in place of base station devices. Hereinafter, a terminal device that is a group owner forming a group in WiFi Direct can also be considered as a base station device.

[0019] In the IEEE802.11 system, each device can transmit multiple frame types with a common frame format. The transmission frame is defined by the physical (PHY) layer, medium access control (MAC) layer, and logical link control (LLC) layer. The physical layer is also called the PHY layer, and the MAC layer is also called the MAC layer.

[0020] The frame transmitted by the PHY layer is called a physical protocol data unit (PPDU, PHY layer frame). A PPDU consists of a physical layer header (PHY header) that contains header information for signal processing at the physical layer, and a physical service data unit (PSDU, PHY layer frame), which is the data unit processed at the physical layer. A PSDU can be composed of an aggregated MPDU (A-MPDU), which aggregates multiple MAC protocol data units (MPDUs), which are the retransmission units in the wireless section.

[0021] The PHY header includes reference signals such as a short training field (STF) used for signal detection and synchronization, a long training field (LTF) used to acquire channel information for data demodulation, and control signals such as a signal (SIG) containing control information for data demodulation. Depending on the supported standard, STFs are classified into legacy STF (L-STF), high throughput STF (HT-STF), very high throughput STF (VHT-STF), high efficiency STF (HE-STF), and extremely high throughput STF (EHT-STF). Similarly, LTFs and SIGs are classified into L-LTF, HT-LTF, VHT-LTF, HE-LTF, L-SIG, HT-SIG, VHT-SIG, HE-SIG, and EHT-SIG. VHT-SIG is further classified into VHT-SIG-A1, VHT-SIG-A2, and VHT-SIG-B. Similarly, HE-SIG is classified into HE-SIG-A1 to HE-SIG-A4 and HE-SIG-B. In addition, assuming technical updates within the same standard, a Universal SIGNAL (U-SIG) field containing additional control information can be included.

[0022] Furthermore, the PHY header can include information for identifying the BSS that is the sender of the transmission frame (hereinafter also referred to as BSS identification information). The information for identifying the BSS can be, for example, the SSID (Service Set Identifier) ​​of the BSS or the MAC address of the base station device of the BSS. Furthermore, the information for identifying the BSS can be a value unique to the BSS (for example, BSS Color) other than the SSID or MAC address.

[0023] The PPDU is modulated according to the corresponding standard, for example, in the case of the IEEE802.11n standard, it is modulated into an Orthogonal Frequency Division Multiplexing (OFDM) signal.

[0024] An MPDU consists of a MAC layer header (MAC header) containing header information for signal processing at the MAC layer, a MAC service data unit (MSDU) or frame body, which is the data unit processed at the MAC layer, and a frame check sequence (FCS), which checks whether the frame is error-free. Multiple MSDUs can also be aggregated into an aggregated MSDU (A-MSDU).

[0025] Frame types for MAC layer transmissions are broadly classified into three types: management frames, which manage the connection status between devices; control frames, which manage the communication status between devices; and data frames, which contain the actual transmission data. Each type is further classified into multiple subframe types. Control frames include acknowledgement (Ack) frames, request to send (RTS) frames, and clear to send (CTS) frames. Management frames include beacon frames, probe request frames, probe response frames, authentication frames, association request frames, and association response frames. Data frames include data frames and polling (CF-poll) frames. Each device can determine the frame type and subframe type of a received frame by reading the contents of the frame control field in the MAC header.

[0026] The Ack may include a Block Ack, which can be used to notify multiple MPDUs that a reception is complete. The Ack may also include a Multi-STA Block Ack (M-BA), which includes a reception completion notification for multiple communication devices.

[0027] A beacon frame includes a field that describes the period (beacon interval) at which the beacon is transmitted and the SSID. A base station device can periodically broadcast a beacon frame within a BSS, and a terminal device can identify base station devices around the terminal device by receiving the beacon frame. The process by which a terminal device identifies a base station device based on a beacon frame broadcast by a base station device is called passive scanning. On the other hand, the process by which a terminal device searches for a base station device by broadcasting a probe request frame within a BSS is called active scanning. A base station device can transmit a probe response frame in response to the probe request frame, and the contents of the probe response frame are the same as those of a beacon frame.

[0028] After recognizing a base station device, the terminal device performs a connection process with the base station device. The connection process is classified into an authentication procedure and an association procedure. The terminal device transmits an authentication frame (authentication request) to the base station device with which it wishes to connect. Upon receiving the authentication frame, the base station device transmits to the terminal device an authentication frame (authentication response) containing a status code indicating whether the terminal device has been authenticated. By reading the status code written in the authentication frame, the terminal device can determine whether it has been authenticated by the base station device. Note that the base station device and terminal device can exchange authentication frames multiple times.

[0029] Following the authentication procedure, the terminal device transmits a connection request frame to the base station device to perform a connection procedure. When the base station device receives the connection request frame, it determines whether to permit the connection of the terminal device and transmits a connection response frame to notify the result. The connection response frame contains a status code indicating whether the connection process is successful, as well as an association identifier (AID) for identifying the terminal device. The base station device can manage multiple terminal devices by setting different AIDs for each terminal device for which it has issued a connection permission.

[0030] After the connection process is completed, the base station device and the terminal device perform actual data transmission. The IEEE802.11 system defines a distributed coordination function (DCF: Distributed Coordination Function), a point coordination function (PCF: Point Coordination Function), and their extended functions (enhanced distributed channel access (EDCA) and hybrid coordination function (HCF), etc.). The following describes an example in which a base station device transmits a signal to a terminal device using DCF, but the same applies when a terminal device transmits a signal to a base station device using DCF.

[0031] In DCF, a base station device and a terminal device perform carrier sense (CS) to check the usage status of wireless channels around the device before communication. For example, if a base station device, which is a transmitting station, receives a signal higher than a predetermined clear channel assessment level (CCA level) on the wireless channel, it postpones transmission of a transmission frame on the wireless channel. Hereinafter, a state in which a signal higher than the CCA level is detected on the wireless channel is called a busy state, and a state in which a signal higher than the CCA level is not detected is called an idle state. In this way, CS performed by each device based on the power of the signal actually received (received power level) is called physical carrier sense (physical CS). The CCA level is also called the carrier sense level (CS level) or the CCA threshold (CCAT). If a signal higher than the CCA level is detected, the base station device and the terminal device begin to demodulate at least the PHY layer signal.

[0032] A base station device performs carrier sensing for an interframe space (IFS) that corresponds to the type of transmission frame to be transmitted, and determines whether the wireless channel is busy or idle. The period during which the base station device performs carrier sensing varies depending on the frame type and subframe type of the transmission frame the base station device is about to transmit. The IEEE 802.11 system defines multiple IFSs with different durations, including the short interframe space (SIFS) used for transmission frames assigned the highest priority, the polling interframe space (PCF IFS: PIFS) used for transmission frames with relatively high priority, and the distributed control interframe space (DCF IFS: DIFS) used for transmission frames with the lowest priority. When a base station device transmits a data frame using DCF, the base station device uses DIFS.

[0033] After waiting for the DIFS, the base station device waits for a further random backoff time to prevent frame collisions. In IEEE 802.11 systems, a random backoff time called a contention window (CW) is used. CSMA / CA assumes that a transmission frame sent by a transmitting station is received by a receiving station without interference from other transmitting stations. Therefore, if two transmitting stations transmit frames at the same time, the frames collide and the receiving station cannot receive them correctly. Therefore, frame collisions are avoided by each transmitting station waiting for a randomly set time before starting transmission. When the base station device determines through carrier sense that the wireless channel is idle, it starts counting down the CW. Only when the CW reaches 0 does it acquire the right to transmit and can transmit a transmission frame to the terminal device. Note that if the base station device determines through carrier sense that the wireless channel is busy during the CW countdown, it stops the CW countdown. When the wireless channel becomes idle, the base station device resumes counting down the remaining CW following the previous IFS.

[0034] Next, the details of frame reception will be explained. A terminal device, which is a receiving station, receives a transmission frame, reads the PHY header of the transmission frame, and demodulates the received transmission frame. The terminal device can then determine whether the transmission frame is addressed to itself by reading the MAC header of the demodulated signal. The terminal device can also determine the destination of the transmission frame based on information written in the PHY header (for example, the group identification number (GID: Group identifier, Group ID) written in VHT-SIG-A).

[0035] If a terminal device determines that a received transmission frame is addressed to itself and demodulates the transmission frame without error, it must transmit an ACK frame to the base station, which is the transmitting station, indicating that the frame was received correctly. The ACK frame is one of the highest-priority transmission frames, which is transmitted after waiting only the SIFS period (no random backoff time is taken). The base station device terminates a series of communications upon receiving the ACK frame from the terminal device. If the terminal device does not receive the frame correctly, it does not transmit an ACK. Therefore, if the base station device does not receive an ACK frame from the receiving station within a certain period (SIFS + ACK frame length) after transmitting a frame, it considers the communication to have failed and terminates the communication. In this way, the end of a single communication (also called a burst) in an IEEE 802.11 system is always determined by whether or not an ACK frame is received, except in special cases such as the transmission of a beacon frame or other notification signal, or when fragmentation is used to divide the transmission data.

[0036] When a terminal device determines that a received transmission frame is not addressed to the terminal device, it sets a network allocation vector (NAV) based on the length of the transmission frame described in the PHY header or the like. The terminal device does not attempt communication during the period set in the NAV. In other words, the terminal device performs the same operation as when it determines that the wireless channel is busy by physical CS during the period set in the NAV, so communication control using the NAV is also called virtual carrier sense (virtual CS). In addition to being set based on information described in the PHY header, the NAV is also set by a request to send (RTS) frame or a clear to send (CTS) frame, which are introduced to solve the hidden terminal problem.

[0037] In contrast to DCF, in which each device performs carrier sensing and autonomously acquires the transmission right, in PCF, a control station called a Point Coordinator (PC) controls the transmission right of each device within the BSS. Generally, a base station device becomes the PC and acquires the transmission right for terminal devices within the BSS.

[0038] The communication period by PCF includes a contention-free period (CFP) and a contention period (CP). During the CP, communication is performed based on the DCF described above, and during the CFP, the PC controls the transmission right. The base station device, which is the PC, broadcasts a beacon frame describing the CFP period (CFP Max duration) and other information within the BSS prior to PCF communication. Note that the beacon frame broadcast at the start of PCF transmission uses PIFS and is transmitted without waiting for a CW. A terminal device that receives this beacon frame sets the CFP period described in the beacon frame as its NAV. Thereafter, until the NAV elapses or a signal announcing the end of the CFP within the BSS (for example, a data frame including CF-end) is received, the terminal device can acquire the transmission right only when it receives a signal signaling acquisition of the transmission right transmitted from the PC (for example, a data frame including CF-poll). During the CFP period, no frame collisions occur within the same BSS, so each terminal device does not take the random backoff time used in DCF.

[0039] A wireless medium can be divided into multiple resource units (RUs). FIG. 1 is a schematic diagram showing an example of how the wireless medium is divided. For example, in resource division example 1, a wireless communication device can divide the frequency resources (subcarriers) of the wireless medium into nine RUs. Similarly, in resource division example 2, a wireless communication device can divide the subcarriers of the wireless medium into five RUs. Of course, the resource division example shown in FIG. 1 is merely an example, and multiple RUs can each be configured with a different number of subcarriers. Furthermore, the wireless medium divided into RUs can include not only frequency resources but also spatial resources. A wireless communication device (e.g., an access point device) can simultaneously transmit frames to multiple terminal devices (e.g., multiple station devices) by placing frames addressed to different terminal devices in each RU. The access point device can write information indicating the division state of the wireless medium (resource allocation information) in the PHY header of a frame it transmits as common control information. Furthermore, the access point device can write information indicating the RU in which the frame addressed to each station device is placed (resource unit assignment information) as unique control information in the PHY header of the frame transmitted by the access point device itself.

[0040] Furthermore, multiple terminal devices (e.g., multiple station devices) can transmit frames simultaneously by placing frames in the RUs assigned to them. After receiving a frame (Trigger frame: TF) containing trigger information transmitted from an access point device, multiple station devices can wait a predetermined period of time before transmitting a frame. Each station device can grasp the RU assigned to itself based on the information stored in the TF. Furthermore, each station device can acquire an RU by random access based on the TF.

[0041] The access point device can simultaneously allocate multiple RUs to one station device. The multiple RUs can be configured with contiguous or non-contiguous subcarriers. The access point device can transmit one frame using the multiple RUs allocated to one station device, or can allocate multiple frames to different RUs for transmission. At least one of the multiple frames can be a frame containing common control information for multiple terminal devices that transmit resource allocation information.

[0042] A station device can be assigned multiple RUs by the access point device. The station device can transmit a single frame using the assigned multiple RUs. Furthermore, the station device can use the assigned multiple RUs to transmit multiple frames, each assigned to a different RU. The multiple frames can be of different frame types.

[0043] The access point device can also assign multiple AIDs to one station device. The access point device can assign RUs to each of the multiple AIDs assigned to one station device. The access point device can transmit different frames using the assigned RUs to each of the multiple AIDs assigned to one station device. The different frames can be of different frame types.

[0044] A single station device can also be assigned multiple AIDs by the access point device. A single station device can be assigned RUs for each of the multiple assigned AIDs. A single station device recognizes all RUs assigned to the multiple AIDs assigned to the station device as RUs assigned to the station device itself, and can transmit a single frame using the multiple assigned RUs. A single station device can also transmit multiple frames using the multiple assigned RUs. In this case, the multiple frames can contain information indicating the AIDs associated with the assigned RUs. The access point device can transmit different frames for the multiple AIDs assigned to a single station device using the assigned RUs. The different frames can be frames of different frame types.

[0045] Hereinafter, base station devices and terminal devices will be collectively referred to as wireless communication devices or communication devices. Information exchanged when one wireless communication device communicates with another wireless communication device will also be referred to as data. In other words, wireless communication devices include base station devices and terminal devices.

[0046] A wireless communication device has either a function for transmitting a PPDU or a function for receiving a PPDU, or both. Fig. 2 is a diagram showing an example of the structure of a PPDU transmitted by a wireless communication device. A PPDU conforming to the IEEE 802.11a / b / g standard is configured to include an L-STF, an L-LTF, an L-SIG, and a Data frame (MAC Frame, MAC Frame, payload, data section, data, information bits, etc.). A PPDU conforming to the IEEE 802.11n standard is configured to include an L-STF, an L-LTF, an L-SIG, an HT-SIG, an HT-STF, an HT-LTF, and a Data frame. A PPDU conforming to the IEEE 802.11ac standard is configured to include some or all of an L-STF, an L-LTF, an L-SIG, a VHT-SIG-A, a VHT-STF, a VHT-LTF, a VHT-SIG-B, and a MAC frame. The PPDU in the IEEE802.11ax standard is a configuration that includes some or all of the following: L-STF, L-LTF, L-SIG, RL-SIG (which is a time-repeated L-SIG), HE-SIG-A, HE-STF, HE-LTF, HE-SIG-B, and Data frames.The PPDU considered in the IEEE802.11be standard is a configuration that includes some or all of the following: L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, EHT-LTF, and Data frames.

[0047] The L-STF, L-LTF, and L-SIG enclosed by dotted lines in Fig. 2 are structures commonly used in the IEEE 802.11 standard (hereinafter, L-STF, L-LTF, and L-SIG are also collectively referred to as L-headers). For example, a wireless communication device conforming to the IEEE 802.11a / b / g standard can properly receive an L-header in a PPDU conforming to the IEEE 802.11n / ac standard. A wireless communication device conforming to the IEEE 802.11a / b / g standard can receive a PPDU conforming to the IEEE 802.11n / ac standard, treating it as a PPDU conforming to the IEEE 802.11a / b / g standard.

[0048] However, wireless communication devices that comply with the IEEE802.11a / b / g standards cannot demodulate the PPDU that follows the L-header and complies with the IEEE802.11n / ac standards, and therefore cannot demodulate information related to the transmitter address (TA), receiver address (RA), and duration / ID field used to set the NAV.

[0049] IEEE802.11 specifies a method of inserting Duration information into L-SIG as a method for wireless communication devices conforming to the IEEE802.11a / b / g standards to appropriately set NAV (or perform reception for a predetermined period of time). Information about the transmission rate in the L-SIG (RATE field, L-RATE field, L-RATE, L_DATARATE, L_DATARATE field) and information about the transmission duration (LENGTH field, L-LENGTH field, L-LENGTH) are used by wireless communication devices conforming to the IEEE802.11a / b / g standards to appropriately set NAV.

[0050] FIG. 3 is a diagram showing an example of a method for inserting Duration information into an L-SIG. In FIG. 3, a PPDU configuration conforming to the IEEE802.11ac standard is shown as an example, but the PPDU configuration is not limited to this. A PPDU configuration conforming to the IEEE802.11n standard and a PPDU configuration conforming to the IEEE802.11ax standard may also be used. TXTIME includes information on the length of the PPDU, aPreambleLength includes information on the length of the preamble (L-STF+L-LTF), and aPLCPHeaderLength includes information on the length of the PLCP header (L-SIG). L_LENGTH includes a Signal Extension, which is a virtual period set to ensure compatibility with the IEEE802.11 standard, and an N related to L_RATE. opsThe L_LENGTH is calculated based on aSymbolLength, which is information about the duration of one symbol (such as an OFDM symbol), aPLCPServiceLength, which indicates the number of bits included in the PLCP Service field, and aPLCPConvolutionalTailLength, which indicates the number of tail bits of the convolutional code. The wireless communication device can calculate L_LENGTH and insert it into the L-SIG. The wireless communication device can also calculate the L-SIG Duration. The L-SIG Duration indicates information about the duration of the PPDU including L_LENGTH and the duration of the Ack and SIFS that are expected to be transmitted from the destination wireless communication device in response to the PPDU.

[0051] An example of a MAC Frame format is shown in Figure 9. Here, MAC Frame refers to the Data Frame (MAC Frame, MAC frame, payload, data section, data, information bits, etc.) in Figure 2 and the MAC Frame in Figure 3. The MAC Frame includes Frame Control, Duration / ID, Address 1, Address 2, Address 3, Sequence Control, Address 4, QoS Control, HT Control, Frame Body, and FCS.

[0052] FIG. 4 shows an example of L-SIG Duration in L-SIG TXOP Protection. DATA (frame, payload, data, etc.) consists of a MAC frame and part of a PLCP header, or both. BA stands for Block Ack or Ack. PPDU includes L-STF, L-LTF, and L-SIG, and can further include one or more of DATA, BA, RTS, and CTS. While the example shown in FIG. 4 shows L-SIG TXOP Protection using RTS / CTS, CTS-to-Self may also be used. Here, MAC Duration is the period indicated by the value of the Duration / ID field. The initiator can also send a CF_End frame to notify the end of the L-SIG TXOP Protection period.

[0053] Next, a method for identifying a BSS from a frame received by a wireless communication device will be described. In order for a wireless communication device to identify a BSS from a frame received, it is preferable for the wireless communication device transmitting a PPDU to insert information for identifying the BSS (BSS color, BSS identification information, a value unique to the BSS) into the PPDU, and information indicating the BSS color can be written in the HE-SIG-A.

[0054] A wireless communication device can transmit an L-SIG multiple times (L-SIG Repetition). For example, a receiving wireless communication device can receive the L-SIG transmitted multiple times using Maximum Ratio Combining (MRC), thereby improving the demodulation accuracy of the L-SIG. Furthermore, when the wireless communication device has successfully received the L-SIG using MRC, it can interpret the PPDU including the L-SIG as a PPDU that complies with the IEEE 802.11ax standard.

[0055] Even while receiving a PPDU, the wireless communication device can receive a part of a PPDU other than the PPDU (for example, a preamble, L-STF, L-LTF, PLCP header, etc., as defined by IEEE 802.11) (also referred to as a dual reception operation). When the wireless communication device detects a part of a PPDU other than the PPDU during the PPDU reception operation, the wireless communication device can update some or all of the information related to the destination address, the source address, the PPDU, or the DATA period.

[0056] Ack and BA can also be called responses (response frames). In addition, probe responses, authentication responses, and connection responses can also be called responses. [1. First embodiment]

[0057] FIG. 5 is a diagram showing an example of a wireless communication system according to this embodiment. The wireless communication system 3-1 includes a wireless communication device 1-1 and wireless communication devices 2-1 to 2-3. The wireless communication device 1-1 is also referred to as a base station device 1-1, and the wireless communication devices 2-1 to 2-3 are also referred to as terminal devices 2-1 to 2-3. The wireless communication devices 2-1 to 2-3 and the terminal devices 2-1 to 2-3 are also referred to as a wireless communication device 2A and a terminal device 2A, as devices connected to the wireless communication device 1-1. The wireless communication device 1-1 and the wireless communication device 2A are wirelessly connected and can transmit and receive PPDUs to and from each other. The wireless communication system according to this embodiment may also include a wireless communication system 3-2 in addition to the wireless communication system 3-1. The wireless communication system 3-2 includes a wireless communication device 1-2 and wireless communication devices 2-4 to 2-6. The wireless communication device 1-2 is also referred to as a base station device 1-2, and the wireless communication devices 2-4 to 2-6 are also referred to as terminal devices 2-4 to 2-6. Furthermore, the wireless communication devices 2-4 to 2-6 and the terminal devices 2-4 to 2-6 are also referred to as wireless communication device 2B and terminal device 2B as devices connected to the wireless communication device 1-2. The wireless communication system 3-1 and the wireless communication system 3-2 form different BSSs, but this does not necessarily mean that the ESSs (Extended Service Sets) are different. An ESS indicates a service set that forms a LAN (Local Area Network). In other words, wireless communication devices that belong to the same ESS can be considered to belong to the same network from an upper layer. The BSSs are connected via a DS (Distribution System) to form an ESS. Each of the wireless communication systems 3-1 and 3-2 can further include multiple wireless communication devices.

[0058] 5, in the following description, it is assumed that a signal transmitted by wireless communication device 2A reaches wireless communication device 1-1 and wireless communication device 2B but does not reach wireless communication device 1-2. In other words, when wireless communication device 2A transmits a signal using a certain channel, wireless communication device 1-1 and wireless communication device 2B determine that channel to be busy, while wireless communication device 1-2 determines that channel to be idle. Also, it is assumed that a signal transmitted by wireless communication device 2B reaches wireless transmission device 1-2 and wireless communication device 2A but does not reach wireless communication device 1-1. In other words, when wireless communication device 2B transmits a signal using a certain channel, wireless communication device 1-2 and wireless communication device 2A determine that channel to be busy, while wireless communication device 1-1 determines that channel to be idle.

[0059] 6 is a diagram showing an example of the device configuration of wireless communication devices 1-1, 1-2, 2A, and 2B (hereinafter collectively referred to as wireless communication device 10-1, station device 10-1, or simply station device). Wireless communication device 10-1 is configured to include an upper layer unit (upper layer processing step) 10001-1, an autonomous distributed control unit (autonomous distributed control step) 10002-1, a transmitter (transmitting step) 10003-1, a receiver (receiving step) 10004-1, and an antenna unit 10005-1.

[0060] The upper layer processing unit 10001-1 performs information processing on layers higher than the physical layer, such as the MAC layer and LLC layer, for information handled within the wireless communication device itself (such as information related to transmitted frames and MIB (Management Information Base)) and frames received from other wireless communication devices.

[0061] The upper layer unit 10001-1 can notify the autonomous distributed control unit 10002-1 of information about frames and traffic being transmitted over a wireless medium. The information about frames and traffic may be, for example, control information included in a management frame such as a beacon, or measurement information reported by another wireless communication device to the wireless communication device itself. Furthermore, the information may be control information included in a management frame or a control frame without limiting the destination (it may be addressed to the device itself, to another device, or by broadcast or multicast).

[0062] 7 is a diagram showing an example of the device configuration of the autonomous distributed control unit 10002-1. The autonomous distributed control unit 10002-1 is also called a control unit 10002-1, and includes a CCA unit (CCA step) 10002a-1, a backoff unit (backoff step) 10002b-1, and a transmission determination unit (transmission determination step) 10002c-1.

[0063] The CCA unit 10002a-1 can determine the state of the radio resource (including determining whether it is busy or idle) using either or both of information about the power of a signal received via the radio resource and information about the received signal (including information after decoding) notified from the receiving unit 10004-1. The CCA unit 10002a-1 can notify the backoff unit 10002b-1 and the transmission determination unit 10002c-1 of the state determination information about the radio resource.

[0064] The backoff unit 10002b-1 can perform backoff using radio resource status determination information. The backoff unit 10002b-1 generates a CW and has a countdown function. For example, when the radio resource status determination information indicates an idle state, the backoff unit 10002b-1 can countdown the CW, and when the radio resource status determination information indicates a busy state, the backoff unit 10002b-1 can stop the CW countdown. The backoff unit 10002b-1 can notify the transmission determination unit 10002c-1 of the CW value.

[0065] The transmission decision unit 10002c-1 makes a transmission decision using either or both of the wireless resource status decision information and the CW value. For example, when the wireless resource status decision information indicates idle and the CW value is 0, the transmission decision unit 10002c-1 can notify the transmission decision information to the transmitting unit 10003-1. Also, when the wireless resource status decision information indicates idle, the transmission decision unit 10003-1 can notify the transmission decision information.

[0066] The transmitting unit 10003-1 includes a physical layer frame generating unit (physical layer frame generating step) 10003a-1 and a wireless transmitting unit (wireless transmitting step) 10003b-1. The physical layer frame generating unit (physical layer frame generating step) may also be referred to as a frame generating unit (frame generating step). The physical layer frame generating unit 10003a-1 has a function of generating a physical layer frame (hereinafter also referred to as a frame or PPDU) based on transmission decision information notified from the transmission decision unit 10002c-1. The physical layer frame generating unit 10003a-1 includes an encoding unit that performs error correction coding on data received from a higher layer to generate an encoded block. The physical layer frame generating unit 10003a-1 also has a function of performing modulation, precoding filter multiplication, etc. The physical layer frame generating unit 10003a-1 sends the generated physical layer frame to the wireless transmitting unit 10003b-1.

[0067] The frame generated by the physical layer frame generator 10003a-1 includes a trigger frame that instructs the wireless communication device, which is the destination terminal, to transmit the frame. The trigger frame includes information indicating the RU that the wireless communication device instructed to transmit the frame will use when transmitting the frame.

[0068] The wireless transmitter 10003b-1 converts the physical layer frame generated by the physical layer frame generator 10003a-1 into a radio frequency (RF) band signal to generate a radio frequency signal. The processing performed by the wireless transmitter 10003b-1 includes digital-to-analog conversion, filtering, frequency conversion from the baseband to the RF band, etc.

[0069] The receiving unit 10004-1 includes a wireless receiving unit (wireless receiving step) 10004a-1 and a signal demodulating unit (signal demodulating step) 10004b-1. The receiving unit 10004-1 generates information related to received signal power from an RF band signal received by the antenna unit 10005-1. The receiving unit 10004-1 can notify the CCA unit 10002a-1 of the information related to the received signal power and the information related to the received signal.

[0070] The wireless receiver 10004a-1 has the function of converting an RF signal received by the antenna 10005-1 into a baseband signal and generating a physical layer signal (e.g., a physical layer frame). The processing performed by the wireless receiver 10004a-1 includes frequency conversion from the RF band to the baseband, filtering, and analog-to-digital conversion.

[0071] The signal demodulation unit 10004b-1 has the function of demodulating the physical layer signal generated by the wireless receiving unit 10004a-1. The processing performed by the signal demodulation unit 10004b-1 includes channel equalization, demapping, error correction decoding, and the like. The signal demodulation unit 10004b-1 can extract, for example, information contained in the PHY header, information contained in the MAC header, and information contained in the transmission frame from the physical layer signal. The signal demodulation unit 10004b-1 can notify the upper layer unit 10001-1 of the extracted information. The signal demodulation unit 10004b-1 can extract any or all of the information contained in the PHY header, information contained in the MAC header, and information contained in the transmission frame. The evaluation unit (evaluation step) (10004c-1) performs a predetermined evaluation of the extracted information contained in the PHY header, MAC header, etc., and notifies the upper layer unit of the results of the evaluation.

[0072] Antenna unit 10005-1 has a function of transmitting the radio frequency signal generated by radio transmission unit 10003b-1 into wireless space, and also has a function of receiving the radio frequency signal and passing it to radio reception unit 10004a-1.

[0073] The wireless communication device 10-1 can cause wireless communication devices around the wireless communication device to set NAV for only that period by describing information indicating the period during which the wireless communication device itself uses the wireless medium in the PHY header or MAC header of a frame to be transmitted. For example, the wireless communication device 10-1 can describe information indicating that period in the Duration / ID field or Length field of a frame to be transmitted. The NAV period set in the wireless communication devices around the wireless communication device itself is referred to as the TXOP period (or simply TXOP) acquired by the wireless communication device 10-1. The wireless communication device 10-1 that has acquired the TXOP is referred to as the TXOP acquirer (TXOP holder). The frame type of the frame that the wireless communication device 10-1 transmits to acquire the TXOP is not limited to any particular type, and may be a control frame (for example, an RTS frame or a CTS-to-self frame) or a data frame.

[0074] The wireless communication device 10-1, which is a TXOP holder, can transmit frames to wireless communication devices other than itself during the TXOP. When the wireless communication device 1-1 is a TXOP holder, the wireless communication device 1-1 can transmit frames to the wireless communication device 2A during the TXOP period. Furthermore, the wireless communication device 1-1 can instruct the wireless communication device 2A to transmit a frame addressed to the wireless communication device 1-1 during the TXOP period. The wireless communication device 1-1 can transmit a trigger frame including information instructing the wireless communication device 2A to transmit a frame addressed to the wireless communication device 1-1 during the TXOP period.

[0075] The wireless communication device 1-1 may reserve TXOP for all communication bands (e.g., Operation bandwidth) over which frames may be transmitted, or may reserve TXOP for a specific communication band (e.g., Transmission bandwidth) over which frames are actually transmitted.

[0076] The wireless communication device that instructs the wireless communication device 1-1 to transmit a frame during the period of the acquired TXOP is not necessarily limited to the wireless communication device connected to the wireless communication device itself. For example, the wireless communication device can instruct wireless communication devices that are not connected to the wireless communication device itself to transmit a frame in order to make wireless communication devices in the vicinity of the wireless communication device itself transmit a management frame such as a Reassociation frame or a control frame such as an RTS / CTS frame.

[0077] This section also explains TXOP in EDCA, a data transmission method different from DCF. The IEEE 802.11e standard, which is related to EDCA, specifies TXOP from the perspective of guaranteeing Quality of Service (QoS) for various services such as video transmission and VoIP. Services are broadly classified into four access categories: VO (Voice), VI (Video), BE (Best Effort), and BK (Background). Generally, the order of priority is VO, VI, BE, and BK. Each access category has parameters for the minimum CW (CWmin), maximum CWmax, Arbitration IFS (AIFS), a type of IFS, and TXOP limit, which are the upper limit of transmission opportunities. These parameters are set to differentiate between high and low priority. For example, the CWmin, CWmax, and AIFS for VO, which has the highest priority for voice transmission, can be set to relatively small values ​​compared to other access categories, enabling data transmission to take priority over other access categories. For example, in VI, where the amount of data transmitted is relatively large for video transmission, setting a large TXOP limit makes it possible to secure longer transmission opportunities than in other access categories.In this way, the values ​​of the four parameters for each access category are adjusted to guarantee QoS according to the various services.

[0078] Next, an example of implementation of a direct link will be described using FIG. 8. Among the numbers used in FIG. 8, the same numbers as those in FIG. 5 are the same as those described in FIG. 5. A wireless system 3-1 includes a base station device 1-1, a wireless communication device 2-1 (terminal device 2-1), a wireless communication device 2-2 (terminal device 2-2), and a wireless communication device 2-3 (terminal device 2-3). When wireless communication device 2-2 transmits data to wireless communication device 2-1, a direct link refers to communication (4-1) via base station device 1-1 and direct communication (4-2) from wireless communication device 2-2 to wireless communication device 2-1 without going through base station device 1-1. When a direct link is used, wireless communication device 2-1 transmits a direct link discovery request to wireless communication device 2-2 via base station device 1-1. Having received the direct link discovery request via base station device 1-1, wireless communication device 2-2 transmits a direct link discovery response to wireless communication device 2-1 using the direct path. When the wireless communication device 2-1 successfully receives this direct link discovery response, it is determined that direct communication is possible between the wireless communication device 2-1 and the wireless communication device 2-2.

[0079] Subsequently, the wireless communication device 2-1 transmits a direct link setup request to the wireless communication device 2-2 via the base station device 1-1. The wireless communication device 2-1 transmitting this direct link setup request is sometimes referred to as the initiator. The wireless communication device 2-2 that receives the direct link setup request transmits a direct setup response to the wireless communication device 2-1 via the base station device 1-1. The wireless communication device 2-2 that transmits this direct setup response is sometimes referred to as the responder. After the direct link setup request and the direct link setup response are successfully exchanged, a direct link is established, and the wireless communication devices 2-1 and 2-2 can communicate directly with each other without going through the base station device 1-1. The direct link setup request and the direct link setup response may include various control information, such as information used in encrypted communication, such as key information. If the information used in encrypted communication is exchanged at the same time as the direct link setup request and the direct link setup response are exchanged, encryption may be used in the direct link.

[0080] Next, we will explain inter-BSS spatial reuse operation using Figure 8. When an interference signal is added to a desired signal in wireless communication, if the ratio of the power of the interference signal and noise to the power of the desired signal is equal to or greater than a predetermined value, the desired signal can be demodulated and decoded. Utilizing this fact means that when communication is taking place over a long distance, that is, when the wireless communication device is sufficiently far away from the wireless communication device in question, it is possible to simultaneously carry out long-distance communication and communication between multiple wireless communication devices in relatively close proximity. This transmission operation that utilizes the path loss that occurs due to the deployment situation and makes overlapping use of the wireless medium is called spatial reuse operation. Hereinafter, spatial reuse operation may be abbreviated as SR.

[0081] As an example, a case will be described in which wireless communication device 2-6 in wireless system 3-2 performs SR transmission for a signal transmitted from wireless communication device 2-3 to base station device 1-1 in wireless system 3-1. In this case, whether SR transmission can be performed without problems depends on the degree to which the SINR (Signal to Interference Noise Ratio) of the signal from wireless communication device 2-3 received by base station device 1-1 is degraded by the transmission from wireless communication device 2-6. If the path loss from wireless communication device 2-6 to base station device 1-1 is sufficiently large and the transmission power of wireless communication device 2-6 is sufficiently small, degradation of the SINR of the signal from wireless communication device 2-3 received by base station device 1-1 is acceptable. Various methods can be used to ensure path loss from wireless communication device 2-6 to base station device 1-1. One example is inter-BSS SR, which performs SR when wireless communication devices belong to different wireless systems (BSSs) and assumes that sufficient path loss is guaranteed. When the wireless communication device 2-6 in the wireless system 3-2 receives the signal 4-3 transmitted by the wireless communication device 2-3 in the wireless system 3-1, it reads the PHY header of the wireless frame of the signal 4-3 and determines which wireless system transmitted the signal 4-3. At this time, it may use information contained in the PHY header, called BSScolor, which is an abbreviation of the identifier indicating the wireless system, to identify that the signal is a wireless frame transmitted from a wireless system other than the wireless system 3-2.

[0082] After identifying the signal 4-3 as a wireless frame signal received from another wireless system, the wireless communication device 2-6 may read a NAV (Network Allocation Vector) indicating the transmission time of the signal 4-3 from the PHY header of the signal 4-3, prepare transmission data (wireless frame) so that the transmission is completed by the time indicated by the NAV, and transmit the data to the base station device 1-2 (4-4). During this transmission, the wireless communication device 2-6 may control the transmission power to reduce interference with the base station devices and wireless communication devices included in the wireless system 3-1. Information used for this transmission power may be received from the base station device 1-2. Furthermore, the wireless communication device 2-6 may perform transmission power control using the reception power when receiving various LTFs included in the preamble of the signal 4-3. Furthermore, the reception power when receiving various LTFs included in the preamble of the signal 4-3 may be used as the representative reception power of the signal 4-3.

[0083] In this embodiment, communications within the same wireless system are used as targets for SR (intra-BSS SR operation). An example of using a direct link when performing SR will be described with reference to FIG. 10. Among the numbers used in FIG. 10, the same numbers as those in FIG. 5 are the same as those described in FIG. 5. Wireless system 3-1 includes base station device 1-1 and wireless communication devices 2-1 to 2-3. It is assumed that a direct link has already been set up between wireless communication device 2-1 and wireless communication device 2-2. Wireless communication device 2-3 transmits data to base station device 1-1 (5-1). Wireless communication device 2-2 has data to transmit to wireless communication device 2-1, in other words, data that can be transmitted using a direct link, but once it detects the signal (5-1) by carrier sense, it temporarily suspends transmission. After detecting the signal (5-1), wireless communication device 2-2 receives the PHY header of the signal (5-1). From this PHY header, it obtains NAV (duration information) indicating the length of the signal (5-1). Thereafter, the wireless communication device 2-2 sets the length of the transmission data (length of the wireless frame) so that it does not exceed the NAV indicating the length of the signal (length of the wireless frame) of (5-1), and after setting the transmission power, transmits the data (wireless frame) to the wireless communication device 2-1 by superimposing it on the signal of (5-1) (5-2).

[0084] Furthermore, the condition for transmitting data (radio frame) (5-2) may include checking the information indicating uplink communication included in the PHY header, and checking whether the information indicating uplink communication indicates the uplink direction. If it indicates uplink communication, it indicates that the radio frame has been transmitted to the base station device.

[0085] An example of the above operation will be described with reference to Fig. 14. Reference numeral 1401 denotes a radio frame transmitted from radio communication device 2-3 to base station device 1-1, 1402 denotes an L-STF, 1403 denotes an L-LTF, 1404 denotes an L-SIG, 1405 denotes an RL-SIG, 1406 denotes a U-SIG, 1407 denotes an EHT-SIG, 1408 denotes an EHT-STF, 1409 denotes an EHT-LTF, and 1410 denotes a data field. The L-SIG (1404) contains information (duration information) indicating a NAV (1411) for the period until transmission of the radio frame (1401) is completed. The information indicating the NAV may be included in the U-SIG (1407) or EHT-SIG (1408) instead of the L-SIG (1404). Upon detecting the transmitted wireless frame (1401), the wireless communication device 2-2 temporarily stops transmission to the wireless communication device 2-1 and starts receiving the wireless frame (1401). Upon receiving the wireless frame (1401), the wireless communication device 2-2 demodulates the PHY header of the wireless frame (1401). This PHY header corresponds to at least one field of the L-SIG (1404), RL-SIG (1405), U-SIG (1406), and EHT-SIG (1407). In this embodiment, all fields are demodulated, but if the wireless frame does not include any of the fields, the other fields may be demodulated. The wireless communication device 2-2 obtains information indicating the NAV (1411) from the demodulated L-SIG (1404), sets the length of the wireless frame (1421) to be transmitted by the wireless communication device 2-2 so that it fits within the NAV (1411), and transmits the wireless frame (1421) to the wireless communication device 2-1. The information indicating that the communication is an uplink communication may be included in the U-SIG (1407) or EHT-SIG (1407), and when confirming the information indicating that the communication is an uplink communication, the wireless communication device 2-2 demodulates this U-SIG (1407) or EHT-SIG (1407). Thereafter, the wireless communication device 2-2 may confirm that the information indicating that the communication is an uplink communication and transmit the wireless frame (1421) to the wireless communication device 2-1.

[0086] The transmission power when transmitting (5-2) to this wireless communication device 2-1 is controlled to an extent that does not prevent base station device 1-1 from receiving communication (5-1) from wireless communication device 2-3. Information used for this power control may be included in a beacon and broadcast by base station device 1-1, or may be included in a trigger frame transmitted by base station device 1-1. Furthermore, when wireless communication device 2-2 performs direct link setup, base station device 1-1 may notify wireless communication device 2-2 of this information. Furthermore, the information used for power control used in this inter-BSS SR may be set as information separate from the information used for power control used in inter-BSS SR. Furthermore, if information for power control used in intra-BSS SR is not defined, the information used for power control used in inter-BSS SR may also be used as information for power control used in intra-BSS SR.

[0087] The setting of the transmission power of (5-2) transmitted by wireless communication device 2-2 to wireless communication device 2-1 as intra-BSS SR may be determined based on information for power control used in intra-BSS SR and the path loss between wireless communication device 2-2 and wireless communication device 2-1. The path loss between wireless communication device 2-2 and wireless communication device 2-1 may be measured from the received power when a reference signal transmitted by wireless communication device 2-2 or wireless communication device 2-1 is received, by exchanging information regarding the transmission power of wireless communication device 2-2 and wireless communication device 2-1 during communication between wireless communication device 2-2 and wireless communication device 2-1, such as direct link discovery or direct link setup. As an example, the transmission power of wireless communication device 2-2 during intra-BSS SR is set to satisfy the following formula: (Transmission power)+(Path loss between wireless communication device 2-2 and wireless communication device 2-1)<(Information for power control used in intra-BSS SR) (Equation 1) At this time, if the value of the expected received power in wireless communication device 2-1 = (transmit power) - (path loss between wireless communication device 2-2 and wireless communication device 2-1) is lower than the value required to demodulate the signal transmitted by wireless communication device 2-2, wireless communication device 2-2 may stop transmitting by intra-BSS SR. Also, if the transmit power that can be set by (Equation 1) is 0 or a negative value, wireless communication device 2-2 may stop transmitting by intra-BSS SR.

[0088] Furthermore, when setting the transmission power of (5-2) that wireless communication device 2-2 transmits to wireless communication device 2-1 as intra-BSS SR, a value indicating the path loss between wireless communication device 2-2 and base station device 1 may also be taken into consideration. The path loss between wireless communication device 2-2 and base station device 1-1 may be measured from the received power when reference signals (various LTFs) transmitted by wireless communication device 2-2 or base station device 1-1 are received by exchanging information regarding the transmission power of wireless communication device 2-2 and base station device 1-1 during communication between wireless communication device 2-2 and base station device 1-1, such as direct link discovery or direct link setup. As an example, the transmission power of wireless communication device 2-2 during intra-BSS SR is set to satisfy the following formula: (Transmission power)-(Path loss between wireless communication device 2-2 and base station device 1-1)<(Information for power control used in intra-BSS SR) (Equation 2) At this time, if the value of the expected received power in wireless communication device 2-1 = (transmit power) - (path loss between wireless communication device 2-2 and wireless communication device 2-1) is lower than the value required to demodulate the signal transmitted by wireless communication device 2-2, wireless communication device 2-2 may stop transmitting by intra-BSS SR. Also, if the transmit power that can be set by (Equation 2) is 0 or a negative value, wireless communication device 2-2 may stop transmitting by intra-BSS SR.

[0089] The explanation so far has been about the case where wireless communication device 2-2 uses uplink communication as the target for intra-BSS SR transmission. This is because base station device 1-1 can communicate with all wireless communication devices and can be assumed to be stationary in most cases, so it is possible to measure the path loss between the wireless communication device and base station device 1-1 and perform intra-BSS SR transmission that takes this into consideration. Furthermore, since it can be determined from the PHY header that the communication is in the same wireless system (BSS) and is uplink communication, it can be determined that the communication is directed to base station device 1-1, and therefore intra-BSS SR transmission becomes possible from the point where the PHY header is demodulated.

[0090] On the other hand, if it is assumed that wireless communication devices in a sufficiently large wireless system are uniformly distributed and the path loss between two wireless communication devices in the wireless system is considered to be sufficiently large with a certain probability, transmission using intra-BSS SR may be performed for downlink communications. Whether downlink communications are in the same wireless system may be determined from information for identifying the wireless system (BSS) and information for identifying uplink / downlink included in the PHY header.

[0091] Next, an example of transmission using intra-BSS SR when a single wireless system (BSS) is divided into multiple sectors will be described with reference to FIG. 11. Among the numbers used in FIG. 11, the same numbers as those in FIG. 5 are the same as those described in FIG. 5. 7-1 to 7-4 are communication areas (sectors) managed by base station device 1-1. The method by which base station device 1-1 manages each sector is not limited. As an example, base station device 1-1 may provide multiple beam antennas to configure each sector and switch between beams for each sector. Alternatively, an antenna capable of changing beams, such as an array antenna, may be used to use different beams for each sector. In a configuration using sectors, base station device 1-1 and wireless communication devices 2-1 to 2-3 add information indicating a sector ID to the PHY header of the data to be transmitted. A sector ID of 0 indicates communication using all sectors, while a sector ID of 1 or greater indicates communication using each of sectors 7-1 to 7-4. The wireless communication device 2-1 and the wireless communication device 2-2 belong to the sector 7-3 and use sector ID = 3. The wireless communication device 2-3 belongs to the sector 7-1 and uses sector ID = 1. Information indicating the sector may be included in the U-SIG (1406) or the EHT-SIG (1407).

[0092] The base station device 1-1 transmits transmission data (6-1) to the wireless communication device 2-3, with a sector ID of 1 indicating sector 7-1 in the PHY header. The wireless communication device 2-2 has data to transmit to the wireless communication device 2-1, but detects the transmission data (6-1) transmitted by the base station device 1-1 by carrier sense and does not transmit the data. The wireless communication device 2-2 demodulates the PHY header of the transmission data (6-1) transmitted by the base station device 1-1, and confirms from the BSS color and sector ID of the transmission data (6-1) that the transmission data (6-1) is for communication within the wireless system 3-1 and that a sector ID different from the sector ID to which the wireless communication device 2-2 belongs is used. The wireless communication device 2-2 then obtains NAV (duration information) from the PHY header, indicating the length of the signal (6-1). Thereafter, wireless communication device 2-2 adjusts the length of the transmission data so that it does not exceed NAV, which indicates the length of the signal (5-1), and after adjusting the transmission power, transmits the data to wireless communication device 2-1 by superimposing it on the signal (5-1) (5-2). The method for adjusting the transmission power is not limited, but it may be set using (Equation 1) or (Equation 2). Furthermore, as information used for power control used in inter-BSS SR, information for inter-BSS SR when sectors are used may be provided separately.

[0093] Next, a modified example will be described in which information indicating the destination of downlink communications is included in the PHY header, enabling identification of the communication device at the communication destination, and SR is performed for downlink communications. In this embodiment, as an example, color information (dist-color) indicating the destination is added to the PHY header. The dist-color is information for indicating the destination, and may be information for identifying a wireless communication device, such as a MAC address or at least one of an association ID (AID), shortened using a hash function or the like. The MAC address is 48 bits long, and the association ID is a maximum of 16 bits long, but may be shortened to 6 bits. The bit length after shortening is not limited to 6 bits, as long as it is set to a bit length sufficient to identify a wireless communication device within the wireless system (BSS). A wireless communication device that receives and demodulates the PHY header included in the transmission data can determine, from the dist-color included in the PHY header, whether the transmission data is addressed to a specific wireless communication device or to a different wireless communication device. This is because by knowing in advance at least one of the MAC address, AID, or dist-color of this specific wireless communication device, it is possible to know the dist-color that identifies this specific wireless communication device. Because dist-color is information that abbreviates the MAC address or AID, there may be wireless communication devices that use the same dist-color, but wireless communication devices with different dist-colors cannot be the same wireless communication device, so it can be used to determine whether the packet is addressed to a different wireless communication device.

[0094] A modified example using dist-color will be described using FIG. 12. Among the numbers used in FIG. 12, the same numbers as those in FIG. 5 are the same as those described in FIG. 5. Base station device 1-1 transmits transmission data (7-1) to wireless communication device 2-3. In this case, base station device 1-1 includes information indicating downlink communication in the PHY header and a dist-color using the AID assigned to wireless communication device 2-3. The information indicating downlink communication may be information that can identify whether the communication is uplink. Wireless communication device 2-2 has transmission data addressed to wireless communication device 2-1, but since it is receiving transmission data (7-1), it determines that the wireless medium is in use and goes into standby. Wireless communication device 2-2 receives the transmission data (7-1) and demodulates the PHY header included in the received data (7-1). If the PHY header includes information indicating downlink communication and a dist-color, it checks whether the dist-color indicates wireless communication device 2-1. If the dist-color does not indicate wireless communication device 2-1, wireless communication device 2-2 may set its transmission power and transmit transmission data (7-2) addressed to wireless communication device 2-1. This power setting may follow the procedure described above. The information for power control used in the intra-BSS SR used at this time may be set so that the control information used in the SR for downlink communication and the control information used in the SR for uplink communication are set separately. The procedure for checking both the information indicating downlink communication and the dist-color has been described above, but it is also possible to check only the dist-color.

[0095] Next, an example of performing SR on data transmitted via a direct link will be described. The wireless communication device 2-5 transmits transmission data (7-4) addressed to the wireless communication device 2-6. The PHY header of this transmission data (7-4) includes a dist-color. The wireless communication device 2-5 may or may not include information indicating an uplink or downlink direction in the PHY header. If information is included in the PHY header, it may indicate the downlink direction. The wireless communication device 2-5 may also include information indicating direct link communication in the PHY header. The wireless communication device 2-4 has transmission data addressed to the base station device 1-2, but since it is receiving the transmission data (7-4), it determines that the wireless medium is in use and enters standby mode. The wireless communication device 2-4 receives the transmission data (7-4) and demodulates the PHY header included in the received data (7-4). If the PHY header includes a dist-color but the dist-color does not indicate that the data is addressed to the base station device 1-2, the wireless communication device 2-4 sets its transmission power and transmits transmission data (7-3) to the base station device 1-1. This power setting may follow the procedure described above. The power control information used in the intra-BSS SR used at this time may be set separately for the control information used in the SR for downlink communications and the control information used in the SR for uplink communications. Although the procedure for checking both the information indicating downlink communications and the dist-color has been described above, it is also possible to check only the dist-color.

[0096] By operating as described above, it is possible to increase the transmission opportunities (TXOP) of the wireless communication device and improve transmission efficiency. Increasing the transmission opportunities (TXOP) has the effect of reducing latency. Therefore, SR may be performed when there is a setting for low latency communication from an upper layer or when there is a notification that the data included in the wireless frame is data for a low latency application. This makes it possible to improve transmission efficiency in cooperation with the application. [2. Common to all embodiments]

[0097] The communication device according to the present invention can communicate in a frequency band (frequency spectrum) called an unlicensed band, which does not require permission to use from a country or region, but the usable frequency band is not limited to this. The communication device according to the present invention can also be effective in, for example, a frequency band called a white band (for example, a frequency band allocated for television broadcasting but unused in some regions) that is not actually used despite permission to use it for a specific service from a country or region for the purpose of preventing interference between frequencies, or in a shared spectrum (shared frequency band) that is expected to be shared by multiple operators.

[0098] The program running on the wireless communication device according to the present invention is a program that controls a CPU and other components (a program that causes a computer to function) so as to realize the functions of the above-described embodiments of the present invention. Information handled by these devices is temporarily stored in RAM during processing, and then stored in various ROMs or HDDs, from which the CPU reads, modifies, and writes the information as needed. Recording media for storing the programs may include semiconductor media (e.g., ROMs, non-volatile memory cards, etc.), optical recording media (e.g., DVDs, MOs, MDs, CDs, BDs, etc.), and magnetic recording media (e.g., magnetic tapes, flexible disks, etc.). Executing a loaded program not only realizes the functions of the above-described embodiments, but may also realize the functions of the present invention by processing in cooperation with an operating system or other application programs, etc., based on instructions from the program.

[0099] Furthermore, when distributing the program on the market, the program can be stored and distributed on a portable recording medium, or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer is also included in the present invention. Furthermore, part or all of the communication device in the above-described embodiments may be realized as an LSI, which is typically an integrated circuit. Each functional block of the communication device may be individually formed into a chip, or part or all of the functional blocks may be integrated into a chip. When each functional block is formed into an integrated circuit, an integrated circuit control unit that controls them is added.

[0100] Furthermore, the integrated circuit method is not limited to LSI, and may be realized by dedicated circuits or general-purpose processors. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, it may also be possible to use an integrated circuit based on that technology.

[0101] It should be noted that the present invention is not limited to the above-described embodiments. The wireless communication device of the present invention is not limited to application to mobile station devices, but can of course be applied to stationary or non-mobile electronic devices installed indoors or outdoors, such as AV equipment, kitchen equipment, cleaning / washing equipment, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0102] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included in the scope of the claims. [Industrial Applicability]

[0103] The present invention is suitable for use in a communication device and a communication method. [Explanation of symbols]

[0104] 1-1, 1-2, 2-1~2-6, 2A, 2B Wireless communication equipment 3-1, 3-2 Management scope 7-1, 7-2, 7-3, 7-4 sectors 10-1 Wireless communication equipment 10001-1 Upper layer section 10002-1 (autonomous decentralized) control unit 10002a-1 CCA Department 10002b-1 Backoff section 10002c-1 Transmission decision unit 10003-1 Transmitter 10003a-1 Physical layer frame generator 10003b-1 Radio transmitter 10004-1 Receiver 10004a-1 Radio receiving unit 10004b-1 Signal demodulation unit 10004c-1 Evaluation section 10005-1 Antenna part 100-1, 100-3, 100-6, 100-11 Busy 100-4, 100-7 random backoff 100-2, 100-5, 100-8, 100-10 radio frames 1401,1421 radio frames

Claims

1. A wireless communication device that communicates with a base station device and another wireless communication device, a receiving unit for receiving a radio frame; a transmitter that transmits wireless frames; a control unit that controls transmission and reception of radio frames; the receiving unit receives a radio frame, demodulating a PHY header of the received wireless frame; When first information for identifying a wireless system included in a PHY header currently being received indicates a wireless system to which the wireless communication device belongs, If the second information included in the currently received PHY header is specific information, Transmit a wireless frame so that it fits within the NAV of the PHY header currently being received. A wireless communication device comprising:

2. 2. The wireless communication device according to claim 1, the second information is information indicating a sector, If the second information does not indicate a sector to which the wireless communication device belongs, transmit the radio frame A wireless communication device comprising:

3. 2. The wireless communication device according to claim 1, the second information is information indicating whether the communication is directed to a base station device, When the second information indicates that the communication is directed to a base station device, transmit the radio frame A wireless communication device comprising:

4. 2. The wireless communication device according to claim 1, the second information is information for identifying a destination wireless communication device, If the second information does not indicate a destination of the wireless frame to be transmitted, transmit the radio frame A wireless communication device comprising:

5. 2. The wireless communication device according to claim 1, the second information is information indicating whether or not the link is a direct link, If the second information indicates a direct link, transmit the radio frame A wireless communication device comprising:

6. A wireless communication method used by a base station device and a wireless communication device that communicates with another wireless communication device, Receives a radio frame, demodulating a PHY header of the received wireless frame; When first information for identifying a wireless system included in a PHY header currently being received indicates a wireless system to which the wireless communication device belongs, If the second information included in the currently received PHY header is specific information, Transmit a wireless frame so that it fits within the NAV of the PHY header currently being received. A wireless communication method comprising:

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