Wireless communication apparatus and wireless communication method

Abstract

To achieve both reduction in power consumption of a radio communication device and maintenance of communication quality of a radio link.SOLUTION: The carrier sensing unit 405 has three types of NAVs, i.e., a basic NAV, an intra-BSSNAV, and an LCNAV, and updates values of the basic NAV and the intra-BSSNAV with a value of the duration information of the received frame when respective conditions including that the received frame is not an AP low capability notification frame are satisfied, and [Condition 1] the received frame is identified as an intra-BSS frame. [Condition 2] The duration information is larger than the current LCNAV value. [Condition 3] the received frame is an AP low capability notification frame, the value of the LCNAV is updated with the value of the duration information.SELECTED DRAWING: Figure 11

Description

[Technical Field]

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

[0002] The Institute of Electrical and Electronics Engineers Inc. (IEEE) is continuously working on developing new standards for IEEE 802.11, the wireless LAN standard, in order to achieve higher efficiency, faster communication speeds, and improved frequency utilization efficiency in wireless LAN (Local Area Network) systems.

[0003] In the IEEE 802.11 series specifications, a wireless communication device in a wireless LAN system is called a station (STA: STAtion), an STA that connects multiple other STAs and provides network services is called an access point station (AP STA: Access Point STA), and an STA that connects to an AP STA and receives network services is called a non-access point station (non-AP STA).In the following, an AP STA is also called an access point (AP), access point device, or base station device, and a non-AP STA is also called a terminal, user terminal, terminal device, or user terminal device.

[0004] The conventional IEEE 802.11 standard adopts a power saving mechanism for non-AP STAs, one of the purposes of which is to reduce power consumption in battery-powered devices such as personal computers, mobile phones, smartphones, and portable information devices (Non-Patent Document 1, Non-Patent Document 2).

[0005] On the other hand, the power consumption of AP STAs has become a problem due to environmental impact and the widespread use of battery-powered access point devices such as mobile routers. IEEE 802.11 Task Group bn (TGbn) has specified that it will work on reducing the power consumption of AP STAs when formulating the next-generation wireless LAN standard (Non-Patent Document 3), and discussions have begun (Non-Patent Documents 4 to 7). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] IEEE Std 802.11-2020, p.2111, 1641-1642, 1647-1649, 2080-2081 [Non-patent document 2] IEEE Std 802.11ax-2021, p.291-292, 314-315, 404-406, 435-439 [Non-patent document 3] IEEE P802.11bn PAR [Non-patent document 4] IEEE 802.11-23 / 1835r0 [Non-Patent Document 5] IEEE 802.11-23 / 1965r2 [Non-patent document 6] IEEE 802.11-24 / 0782r0 [Non-Patent Document 7] IEEE 802.11-24 / 0813r0 Summary of the Invention [Problem to be solved by the invention]

[0007] The challenge is to achieve both low power consumption in wireless communication devices and maintaining the communication quality of wireless links. [Means for solving the problem]

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

[0009] (1) That is, a wireless communication device according to one aspect of the present invention is a wireless communication device that belongs to a first basic service set (BSS) and performs wireless communication, and includes a wireless receiving unit and a carrier sense unit, wherein the carrier sense unit performs virtual carrier sensing using a first network allocation vector (NAV), a second NAV, and a third NAV, and when the wireless receiving unit receives a frame, if a first condition is satisfied, the wireless receiving unit updates the first NAV with a first duration included in the received frame, if a second condition is satisfied, the second NAV with the first duration, and if a third condition is satisfied, the third NAV with the first duration, and the first condition is satisfied if the received frame is identified as a frame of a BSS different from the first BSS, or is not identified as a frame of the first BSS or a frame of a BSS different from the first BSS, the first duration is greater than the current first NAV value, and the receiving address of the received frame is a The second condition includes at least: the received frame is not an address; the received frame is not a frame notifying the access point device to transition to a low capability mode; the second condition includes at least: the received frame is identified as a frame of the first BSS; the first duration is greater than the current second NAV value; the receiving address of the received frame is not an address of the own device; the own device is not a transmission opportunity holder and the received frame is not a frame requiring an immediate response or the own device is not a transmission opportunity holder and the received frame is a trigger frame; the received frame is not a frame notifying the access point device to transition to a low capability mode; and the third condition includes at least: the received frame is identified as a frame of the first BSS; the first duration is greater than the current third NAV value; and the received frame is a frame notifying the access point device to transition to a low capability mode.

[0010] (2) Furthermore, a wireless communication device according to one embodiment of the present invention further includes a wireless transmission unit that transmits frames, and the carrier sense unit, when transmitting a predetermined frame, performs virtual carrier sense using the first NAV and the second NAV without taking into account the third NAV.

[0011] (3) Furthermore, a wireless communication device according to one embodiment of the present invention is an access point device, further comprising a communication control unit, wherein when the communication control unit determines to transition from high capacity mode to low capacity mode, it generates a first frame notifying the transition to low capacity mode, and the wireless transmitting unit transmits the first frame, wherein the first frame includes at least information indicating the transition to the low capacity mode and duration information indicating the duration of the low capacity mode.

[0012] (4) Also, a communication method according to one aspect of the present invention is a communication method in a wireless communication device that belongs to a first BSS and performs wireless communication, the communication method comprising: receiving a frame; performing virtual carrier sensing using a first NAV, a second NAV, and a third NAV; updating the first NAV with a first duration included in the received frame if a first condition is met when the frame is received; updating the second NAV with the first duration if a second condition is met when the frame is received; and updating the third NAV with the first duration if a third condition is met when the frame is received, wherein the first condition is that the received frame is identified as a frame of a BSS different from the first BSS, or is not identified as a frame of the first BSS or a frame of a BSS different from the first BSS; the first duration is greater than the current first NAV value; and updating the receiving address of the received frame is a receiving address of the wireless communication device. The second condition includes at least: the received frame is not an address; the received frame is not a frame notifying the access point device to transition to a low capability mode; the second condition includes at least: the received frame is identified as a frame of the first BSS; the first duration is greater than the current second NAV value; the receiving address of the received frame is not an address of the own device; the own device is not a transmission opportunity holder and the received frame is not a frame requiring an immediate response or the own device is not a transmission opportunity holder and the received frame is a trigger frame; the received frame is not a frame notifying the access point device to transition to a low capability mode; and the third condition includes at least: the received frame is identified as a frame of the first BSS; the first duration is greater than the current third NAV value; and the received frame is a frame notifying the access point device to transition to a low capability mode. [Effects of the Invention]

[0013] According to the wireless communication device and wireless communication method of the present invention, it is possible to achieve both low power consumption in the wireless communication device, particularly in the access point device, and maintaining the communication quality of the wireless link. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram illustrating an example of a configuration of a wireless communication system according to an aspect of the present invention. [Figure 2] FIG. 1 is a diagram illustrating an example of a PHY layer frame configuration in a wireless LAN system. [Figure 3] FIG. 1 is a diagram illustrating an example of a MAC layer frame configuration in a wireless LAN system. [Figure 4] 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 5] FIG. 1 is a diagram illustrating an example of a timing chart in a wireless communication system according to an aspect of the present invention. [Figure 6] FIG. 1 is a diagram illustrating an example of a timing chart in a wireless communication system according to an aspect of the present invention. [Figure 7] FIG. 1 is a diagram illustrating an example of a timing chart in a wireless communication system according to an aspect of the present invention. [Figure 8] FIG. 1 is a diagram illustrating an example of a timing chart in a wireless communication system according to an aspect of the present invention. [Figure 9] FIG. 1 is a diagram illustrating an example of a timing chart in a wireless communication system according to an aspect of the present invention. [Figure 10] FIG. 1 is a diagram illustrating an example of a timing chart in a wireless communication system according to an aspect of the present invention. [Figure 11] FIG. 1 is a diagram illustrating an example of a timing chart in a wireless communication system according to an aspect of the present invention. [Figure 12] FIG. 1 is a diagram illustrating an example of a timing chart in a wireless communication system according to an aspect of the present invention. [Figure 13] FIG. 1 is a diagram illustrating an example of a timing chart in a wireless communication system according to an aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The wireless communication system in this embodiment includes an access point device (AP STA, also referred to as a base station device) and multiple terminal devices (also referred to as non-AP STA). Furthermore, a wireless communication system and network configured from an access point device and terminal devices connected to the access point device is called a BSS (Basic Service Set, management range). Furthermore, a terminal 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 terminal device. Hereinafter, simply referring to an STA or wireless communication device refers to both an access point device and a terminal device.

[0016] The access point device and terminal devices within the BSS each perform wireless communication based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance). This embodiment focuses on infrastructure mode, in which an access point device performs wireless communication with multiple terminal devices, but the method of this embodiment can also be implemented in ad hoc mode, in which terminal devices perform direct wireless communication with each other. In ad hoc mode, one terminal device acts as an access point device and forms a BSS. A BSS in ad hoc mode is also called an IBSS (Independent Basic Service Set). Hereinafter, a terminal device that forms an IBSS in ad hoc mode can also be considered an access point device. [Example]

[0017] FIG. 1 is a diagram showing an example of a wireless communication system according to this embodiment. FIG. 1 shows an example of an environment in which a wireless communication system 100-1 (also referred to as BSS 100-1) configured with an access point (AP) device 101-1, a terminal device 102-1, and a legacy terminal device 103-1, and a wireless communication system 100-2 (also referred to as BSS 100-2) configured with an access point (AP) device 101-2, a terminal device 102-2, and a legacy terminal device 103-2 exist in such a manner that their communication areas partially or entirely overlap. In this embodiment, an example is described in which wireless frames transmitted by each wireless communication device are received by all other wireless communication devices (observable at a predetermined reception power or higher). Such other BSSs whose communication areas overlap are called OBSSs (Overlapping BSSs). In the example of the wireless communication system shown in FIG. 1, the BSSs 100-1 and 100-2 recognize each other as an OBSS. In the present embodiment, a legacy terminal device refers to a conventional terminal device to which the present invention is not applied, such as a terminal device compliant with the IEEE 802.11ax standard. Similarly, a legacy access point device refers to a conventional access point device to which the present invention is not applied, such as an access point device compliant with the IEEE 802.11ax standard. A legacy access point device and a legacy terminal device are collectively referred to as a legacy wireless communication device. The wireless communication system 100-1 and the wireless communication system 100-2 form different BSSs, but this does not necessarily mean that the ESSs (Extended Service Sets) representing service sets forming LANs are different. In other words, wireless communication devices belonging to the same ESS can be considered to belong to the same network from a higher layer. Furthermore, BSSs can be coupled via a DS (Distribution System) to form an ESS. Each of the wireless communication systems 100-1 and 100-2 can further include multiple terminal devices, legacy terminal devices, or both.

[0018] In an IEEE 802.11 wireless communication system, each wireless communication device can transmit multiple types of frames with a common frame format, which are defined in the physical (PHY) layer, medium access control (MAC) layer, and logical link control (LLC) layer.

[0019] A PHY layer frame is called a physical protocol data unit (PPDU, PHY layer frame). Hereinafter, a PHY layer frame is also referred to as a radio frame. Unless otherwise specified, the term "frame" refers to a radio frame. A PPDU includes a training field (TF) used for signal detection, propagation path estimation, and demodulation assistance in the physical layer, a signal field (SIG) containing information for signal processing in the physical layer, and a physical service data unit (PSDU, PHY layer frame), which is a data unit processed in the physical layer. A PSDU can also include an aggregated MPDU (A-MPDU), which aggregates multiple MAC protocol data units (MPDU, MAC layer frame), which serve as a retransmission unit in the wireless section.

[0020] Figure 2 shows an example of a PHY layer frame and PPDU configuration in a wireless LAN system. Figure 2 also shows an example of a PPDU configuration in the IEEE 802.11n (also known as High Throughput: HT), IEEE 802.11ac (also known as Very High Throughput: VHT), IEEE 802.11ax (also known as High Efficiency: HE), and IEEE 802.11be (also known as Extremely High Throughput: EHT). The PPDU includes multiple short training fields (STFs) used for signal detection and synchronization, and multiple long training fields (LTFs) used to acquire channel information for data demodulation. STFs are classified into L-STF (non-HT Short Training Field), HT-STF (High Throughput Short Training Field), VHT-STF (Very High Throughput Short Training Field), HE-STF (High Efficiency Short Training Field), and EHT-STF (Extremely High Throughput Short Training Field) depending on the standard they support. LTFs are similarly classified into L-LTF, HT-LTF, VHT-LTF, HE-LTF, and EHT-LTF depending on the standard they support. PPDUs that comply with standards prior to IEEE 802.11n are also called non-HT PPDUs.

[0021] Similarly, the SIGNAL field included in the PPDU is classified into L-SIG, HT-SIG, VHT-SIG, HE-SIG, EHT-SIG, etc. according to the corresponding standard. 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. Also, as shown in FIG. 2, the L-SIG field includes multiple subfields such as RATE and LENGTH. The LENGTH subfield of the L-SIG field indicates information about the length of the PPDU, such as the number of octets or the time length. Furthermore, assuming updates to the specifications within the same standard, a U-SIG (Universal SIG) field containing additional control information may be included. The RL-SIG field included in the PPDUs (HE PPDU and EHT PPDU) of the IEEE 802.11ax and IEEE 802.11be standards is a repetition of the L-SIG field, and can be used to distinguish the HE PPDU and EHT PPDU from PPDUs of earlier standards.

[0022] Furthermore, the PPDU can include information for identifying the BSS that is the sender of the 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 access point device of the BSS. The information for identifying the BSS can also be a value unique to the BSS (for example, BSS Color) other than the SSID or MAC address. Information indicating the BSS Color can be included in the HE-SIG-A or U-SIG.

[0023] A PPDU in accordance with the IEEE 802.11ax standard and the IEEE 802.11be standard may include a packet extension (PE) field to ensure the time required for receiving and processing the PPDU.

[0024] Figure 3 shows an example of the MPDU structure, which is a MAC layer frame in a wireless LAN system. The MPDU is composed of a MAC header containing information for signal processing in the MAC layer, a MAC Service Data Unit (MSDU) or frame body, which is a data unit input to and processed in the MAC layer, and a Frame Check Sequence (FCS) field, which checks whether the MAC layer frame is error-free. Multiple MSDUs can also be aggregated as an aggregated MSDU (A-MSDU) and included in the frame body.

[0025] Each wireless communication device can recognize the frame type and subframe type of a received MAC layer frame by reading the contents of the frame control field included in the MAC header. MAC layer frame types are broadly classified into three types: management frames that manage the connection status between wireless communication devices, control frames that manage the communication status between wireless communication devices, and data frames that contain the actual transmission data. Each type is further classified into multiple subframe types. Control frames include acknowledgement (Ack or ACK) frames, block acknowledgement (BA or BlockAck) frames, request to send (RTS) frames, and clear to send (CTS) frames. BAs can acknowledge multiple MPDUs (notifying that reception is complete). Management frames include beacon frames, probe request frames, probe response frames, authentication frames, association request frames, and association response frames. The data frames include data frames, polling (CF-Poll) frames, and the like.

[0026] The MAC header also includes a Duration / ID field. In some frame types, the Duration / ID field indicates the association ID (AID) of the sender of the frame. In other frame types, the Duration / ID field can indicate the duration of the wireless medium occupation by the transmission of the frame, or the duration of the wireless medium occupation by the transmission of the frame and the exchange of a series of frames associated with it. Note that the Duration / ID field is also simply called the Duration field when it indicates the duration.

[0027] The MAC header can also contain up to four address fields indicating MAC addresses, with the BSS identifier (BSSID), source address (SA), destination address (DA), transmitting address (TA), receiving address (RA), etc. displayed in the address fields at positions determined according to the frame type, etc. Hereinafter, the various address information indicated in the address fields of the MAC header will be collectively referred to as address information or MAC address information.

[0028] A beacon frame includes fields indicating the period (beacon interval) at which beacons are transmitted and the SSID, which is a string used to identify the BSS. An access point device can periodically broadcast a beacon frame within a BSS, and a terminal device can recognize nearby access point devices by receiving the beacon frame. The process by which a terminal device recognizes an access point device based on a beacon frame broadcast by an access point device is called passive scanning. On the other hand, the process by which a terminal device searches for an access point device by broadcasting a probe request frame within a BSS is called active scanning. The access point device can transmit a probe response frame in response to the probe request frame, and the content of the probe response frame is the same as the content of the beacon frame.

[0029] After recognizing an access point device, a terminal device performs a connection process with the access point device. The connection process is classified into an authentication procedure and an association procedure. The terminal device transmits an authentication request frame to the access point device to which it wishes to connect. Upon receiving the authentication request frame, the access point device transmits an authentication response frame to the terminal device, which includes a status code indicating whether the terminal device has been authenticated. By reading the status code included in the authentication response frame, the terminal device can determine whether its authentication request has been approved by the access point device. Note that the access point device and terminal device can exchange authentication request frames and authentication response frames (both of which are collectively referred to as authentication frames) multiple times.

[0030] Following the authentication procedure, the terminal device transmits a connection request frame to the access point device to perform a connection procedure. Upon receiving the connection request frame, the access point device determines whether to permit the terminal device to connect and transmits a connection response frame to notify the determination. The connection response frame contains an AID for identifying the terminal device in addition to a status code indicating whether the connection process is successful. The access point device can manage multiple terminal devices by assigning different AIDs to each terminal device for which it has issued connection permission.

[0031] After the connection process is completed, the access point device and the terminal device perform actual data transmission. The IEEE 802.11 system defines the Distributed Coordination Function (DCF), Point Coordination Function (PCF), and their extended Hybrid Coordination Function (HCF) as media access methods. The specific implementation methods for HCF are Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA).

[0032] An example of the operation when a wireless communication device transmits a wireless frame based on DCF will be described. In DCF, a wireless communication device performs carrier sense (CS) to check the usage status of wireless channels surrounding the wireless communication device prior to communication. For example, if a wireless communication device intends to transmit a frame receives a signal with a received power higher than a predetermined clear channel assessment level (CCA level) on the wireless channel during the carrier sense period performed prior to transmission, the wireless communication device postpones the transmission of the frame on the wireless channel. Hereinafter, a state in which a signal with a received power equal to or higher than the CCA level is detected on the wireless channel is referred to as a busy state of the wireless medium, and a state in which a signal with a received power equal to or higher than the CCA level is not detected is referred to as an idle state of the wireless medium. In this way, carrier sense performed by each wireless communication device based on the power level of a signal actually received is referred to as physical carrier sense (physical CS). The CCA level is also referred to as a carrier sense level (CS level) or a CCA threshold (CCAT). Furthermore, when the wireless communication device detects a signal with reception power equal to or higher than the CCA level, the wireless communication device starts an operation to demodulate the signal at least in the PHY layer.

[0033] A wireless communication device performs carrier sensing during an interframe space (IFS) that is set according to the frame type and subframe type to be transmitted, and determines whether the wireless channel is busy or idle. The IEEE 802.11 system defines multiple IFSs with different durations, including a short interframe space (SIFS) used for frames assigned the highest priority, a polling interframe space (PIFS: PCF IFS) used for frames with relatively high priority, and a distributed arbitration interframe space (DIFS: DCF IFS) used for frames with low priority. When transmitting data frames using DCF, a wireless communication device uses a DIFS.

[0034] After waiting for the DIFS period, the wireless communication device further waits for a random backoff time to prevent frame collisions. In the IEEE 802.11 system, a random backoff time based on a contention window (CW) is used. CSMA / CA assumes that a frame transmitted by a transmitting station is received by a receiving station without interference from other transmitting stations. Therefore, if multiple transmitting stations transmit frames at the same time, the frames may collide with each other, potentially preventing the receiving station from receiving the frame correctly. Therefore, frame collisions are avoided by having each transmitting station wait for a randomly set time before starting transmission. When the wireless communication device determines that the wireless channel is idle through carrier sense, it starts counting down a backoff counter set based on the CW. Only when the backoff counter reaches 0 does it acquire a transmission opportunity (TXOP) and become able to transmit a frame. The wireless communication device continues carrier sense even during the backoff counter countdown. If it determines that the wireless channel is busy again, it stops counting down the backoff counter. When the wireless channel becomes idle again, the wireless communication device waits for the same period as the previous IFS, and then resumes counting down the remaining part of the backoff counter. The TXOP acquisition procedure using the backoff counter is also called a backoff procedure.

[0035] The wireless communication device, which is the receiving station, receives the frame, reads information such as the SIGNAL field according to the standard of the frame, and demodulates the received frame.The wireless communication device can then determine whether the frame is addressed to the device itself by reading the MAC header of the demodulated signal.The wireless communication device can also determine the destination of the frame based on information contained in the SIGNAL field, such as a group identification number (GID: Group ID) contained in the VHT-SIG-A.

[0036] If a wireless communication device determines that a received frame is addressed to the device itself and demodulates the frame without error, it must transmit an Ack frame to the wireless communication device (transmitting station) indicating that the frame was received correctly. The Ack frame is one of the highest-priority frames that is transmitted by simply waiting for the SIFS period (without a random backoff time). The wireless communication device (transmitting station) terminates a series of communications upon receiving an Ack frame from the wireless communication device (receiving station). Note that if the wireless communication device (receiving station) fails to receive the frame correctly, the wireless communication device (receiving station) does not transmit an Ack frame. Therefore, if the wireless communication device (transmitting station) does not receive an Ack frame from the receiving station within a certain period (SIFS + Ack frame length) after transmitting the frame, it determines that the communication has 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 when transmitting a beacon frame or other notification signal, or when fragmentation is used to divide the transmitted data.

[0037] Next, an example of the operation when an access point device transmits a signal to a terminal device based on PCF will be described. Unlike DCF, in which each device performs carrier sensing and autonomously acquires the transmission right, in PCF, a control station called a point coordinator controls the transmission right of each device within the BSS. Generally, the access point device acts as the point coordinator and acquires the transmission right of the terminal device 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 carried out based on the DCF described above, and it is during the CFP that the point coordinator controls the transmission right. The access point device, which is the point coordinator, broadcasts a beacon frame including information such as the maximum duration of the CFP (CFP Max duration) 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 going through a backoff procedure. A terminal device that receives this beacon frame sets the value of the CFP Max duration included in the beacon frame in the NAV (Network Allocation Vector), which maintains a period during which no frame transmission is performed to the wireless medium. After that, until the duration set in the NAV has elapsed 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 from the point coordinator signaling acquisition of the transmission right for itself (for example, a data frame including CF-Poll). Note that, since packet collisions do not occur within the same BSS during the CFP period, each terminal device does not take the random backoff time used in DCF.

[0039] 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 quality of service (QoS) guarantees for various services such as video transmission and VoIP (Voice over IP). 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), 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 of VO, the highest priority service 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.

[0040] In addition, TIDs (Traffic IDentifiers) can be used to set QoS for MSDUs input from higher layers to the MAC layer, and eight of the TIDs can identify traffic categories (TCs), while the remaining eight can identify parameterized traffic streams (TSs).

[0041] Fig. 4 is a diagram showing an example of the configuration of wireless communication device 400 according to this embodiment. The example configuration of wireless communication device 400 shown in Fig. 4 is a configuration common to access point devices 101-1 and 101-2 and terminal devices 102-1 and 102-2 in Fig. 1. Note that the basic block configuration of legacy terminal devices 103-1 and 103-2 in Fig. 1 is the same as that of wireless communication device 400, but the operation of some blocks differs.

[0042] The wireless communication device 400 is composed of an upper layer unit (upper layer step) 401, a communication control unit (communication control step) 402, a wireless transmission unit (wireless transmission step) 403, a wireless reception unit (wireless reception step) 404, a carrier sense unit (carrier sense step) 405, and an antenna unit 406.

[0043] The upper layer unit 401 may be implemented with some or all of the functions of the layers above the MAC layer and may perform processing. Note that the functions of the upper layer unit 401 are not limited to this, and may further include, for example, some functions of the MAC layer.

[0044] The communication control unit 402 generates MPDUs for control frames and management frames, outputs them to the wireless transmission unit 403, and instructs transmission. The communication control unit 402 also uses the data unit (MSDU) input from the upper layer unit 401 as a frame body, and adds a MAC header including fields such as the BSSID of the BSS to which the wireless communication device 400 belongs, the source address, the destination address, the sending address, and the receiving address, QoS control information related to the MSDU, and a duration, as well as a Frame Check Sequence (FCS) for error detection, to generate an MPDU for a data frame, and outputs it to the wireless transmission unit 403 to instruct transmission. The duration can be set to the duration of wireless medium occupation by the transmission of the frame, the duration of wireless medium occupation by the transmission of the frame and the exchange of a series of frames associated with it, or the duration of a TXOP to be secured. The communication control unit 402 may also output an A-MPDU, which aggregates multiple MPDUs, to the wireless transmission unit 403.

[0045] The instruction to transmit a frame to the wireless transmitting unit 403 may be executed when the carrier sense result by the carrier sense unit 405 is in the idle state and after TXOP acquisition based on the backoff procedure. Note that the above carrier sense and backoff procedures can be omitted for frames that can be transmitted without carrier sense, such as an Ack frame for a received frame or a response frame for a frame addressed to the device itself from a TXOP holder.

[0046] The communication control unit 402 also processes the received MPDU input from the wireless receiving unit 404. The communication control unit 402 performs a cyclic redundancy check (CRC) on the received MPDU and compares it with the value in the FCS field to check for any errors in the MPDU. If the communication control unit 402 checks that the MPDU is error-free, it extracts the MAC header of the MPDU and identifies the frame type and subframe type from the frame control field. Based on the identified frame type and subframe type, the communication control unit 402 extracts the remaining fields of the MAC header and obtains information such as duration information, address information, and QoS control information indicated in each field. Note that an A-MPDU may also be input from the wireless receiving unit 404. In this case, the wireless control unit 402 separates the A-MPDU into individual MPDUs and performs the above-mentioned reception processing.

[0047] The communication control unit 402 identifies, from the acquired address information, whether the received MPDU is addressed to the own device (including multicast and broadcast including the own device) and whether it is a frame within the BSS to which the own device belongs (referred to as an intra-BSS frame) or a frame of another BSS (referred to as an inter-BSS frame). The communication control unit 402 inputs the address information, the identification result of whether it is an intra-BSS frame or not, and duration information to the carrier sense unit 405. Furthermore, if the communication control unit 402 identifies that the received MPDU is addressed to the own device and the MPDU contains a frame body, i.e., an MSDU, it outputs the MSDU to the upper layer unit 401. The communication control unit 402 may output information such as the acquired address information and QoS control information together with the MSDU to the upper layer unit 401.

[0048] The wireless transmitting unit 403 generates a PPDU by treating the MPDU or A-MPDU input from the communication control unit 402 as a PSDU and adding a training field and a SIGNAL field to the PSDU. For example, in the case of a PPDU compliant with the IEEE 802.11be standard, the wireless transmitting unit 403 generates a PPDU by adding L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, and EHT-LTF before the PSDU. Furthermore, the wireless transmitting unit 403 may add a PE field to the end of the PPDU as necessary.

[0049] The wireless transmitting unit 403 performs processes such as error correction coding, digital modulation, mapping, frequency-time conversion, digital-to-analog conversion, filtering, and up-conversion to radio frequency (RF) on the generated PPDU to generate a wireless signal, which is then transmitted from the antenna unit 406 at the transmission timing instructed by the communication control unit 402.

[0050] The wireless receiving unit 404 down-converts the wireless signal received by the antenna unit 406 and performs processing such as filtering and analog-to-digital conversion to obtain a digital received signal. If the wireless receiving unit 404 detects L-STF and L-LTF from the received signal and successfully synchronizes with the received frame, it can further perform time-frequency conversion, demapping, digital demodulation, error correction decoding, etc. on the obtained digital received signal to obtain a received PPDU. The wireless receiving unit 404 outputs the obtained PPDU to the communication control unit 402. Note that if the wireless receiving unit 404 fails to obtain the L-SIG field, i.e., if the parity check of the L-SIG field is not successful, it may abort the acquisition of the frame. Furthermore, if a BSS-specific value such as BSS Color is obtained from the HE-SIG-A or U-SIG and the BSS-specific value differs from that of the BSS to which the wireless receiving unit 404 belongs, the wireless receiving unit 404 may abort the acquisition of the frame.

[0051] The wireless receiving unit 404 monitors the received signal from the antenna unit 406, and if it does not detect a signal with a received power equal to or greater than a predetermined CCA level (hereinafter also referred to as the CCA-ED level) for energy detection (ED), it sets a CCA indication (also referred to as the PHY-CCA indication), which indicates whether the wireless medium is available, to an idle state and outputs it to the carrier sense unit 405.If it detects a signal with a received power equal to or greater than the CCA-ED level, it sets the CCA indication to a busy state and notifies the carrier sense unit 405.

[0052] When the wireless receiving unit 404 detects L-STF and L-LTF from the received signal at a reception power equal to or greater than a predetermined CCA level for signal detection (SD) (hereinafter also referred to as the CCA-SD level), the wireless receiving unit 404 sets the CCA indication to a busy state and notifies the carrier sense unit 405. This reception power detection is also called preamble detection. Furthermore, when the wireless receiving unit 404 successfully acquires the L-SIG field, the wireless receiving unit 404 maintains the CCA indication in a busy state for a period based on the LENGTH subfield in the L-SIG field. Note that the wireless receiving unit 404 may set the CCA-ED level higher than the CCA-SD level, and may set the CCA-SD level to −82 dBm and the CCA-ED level to −62 dBm, for example. Furthermore, if a value specific to a BSS, such as a BSS Color, is acquired from HE-SIG-A or U-SIG and the value differs from that of the BSS to which the device belongs, wireless receiving unit 404 may change the CCA-SD level to a higher value. In this case, wireless transmitting unit 403 preferably reduces the transmission power in conjunction with raising the CCA-SD level.

[0053] The carrier sense unit 405 receives a CCA indication from the wireless receiving unit 404, and receives the identification result of whether the received MPDU is addressed to the device itself and whether it is an intra-BSS frame or an inter-BSS frame, as well as duration information, from the communication control unit 402. Carrier sense based on this CCA indication is called physical carrier sense (physical CS).

[0054] The carrier sense unit 405 has an indicator called a Network Allocation Vector (NAV), which maintains time periods during which the device does not transmit frames to the wireless medium, regardless of the state of the physical CS. The NAV can be expressed as a countdown timer and is also called a NAV timer or a NAV counter. In the following description, the NAV will be described as being expressed as a countdown timer, but this is not limited to this. The carrier sense unit 405 of a terminal device has two types of NAV: a basic NAV and an intra-BSS NAV. The carrier sense unit 405 of an access point device can have two types of NAV: a basic NAV and an intra-BSS NAV. Updates to the NAV value will be described in detail later.

[0055] The carrier sense unit 405 determines that the virtual carrier sense (virtual CS) is in an idle state if both the basic NAV and the intra-BSS NAV are 0, and determines that the virtual CS is in a busy state if at least one NAV is non-zero.

[0056] The carrier sense unit 405 outputs to the communication control unit 402 that the carrier sense result is in an idle state when both the physical CS and the virtual CS are in an idle state, and that the carrier sense result is in a busy state when either the physical CS or the virtual CS is in a busy state.

[0057] Next, a low power consumption mode in the access point device according to this embodiment will be described. The access point device according to this embodiment has a low power consumption mode for the purpose of reducing power consumption. In the low power consumption mode, the access point device can restrict its operating capabilities, such as not transmitting frames from its own device or reducing or limiting all or part of its reception processing capability. From the perspective of reception processing capability, power consumption can be reduced, for example, by stopping all reception processing capabilities, or by limiting the receivable frequency bandwidth, modulation and coding scheme (MCS), spatial multiplexing number, number of wireless links, PPDU format, etc. to specific configurations, such as a frequency bandwidth of 20 MHz, an MCS with the lowest transmission rate, a spatial multiplexing number of 1, and one wireless link, or by limiting only non-HT PPDUs. However, such configurations, methods, and combinations are not limited to these. Low power consumption modes that reduce or limit all or part of the processing capabilities as described above include power save mode, doze mode, sleep mode, lower capability mode, low power listening mode, etc. Furthermore, states that are not the low power consumption mode include active mode, high capability mode, normal mode, etc. In the following, the low capability mode will be described as an example of the low power consumption mode, and the high capability mode as an example of a state that is not the low capability mode, but the present invention is not limited to this and other modes mentioned above may also be used.

[0058] During the period when the access point device is transitioning to low-capability mode, for example, there is a possibility that frames addressed to the access point device will not be received and will continue to be retransmitted, or that the connection will be severed due to the access point device not returning a necessary response frame, or that new terminal devices will not be able to connect.

[0059] Therefore, when transitioning to low capability mode, the access point device transmits a frame notifying surrounding wireless communication devices of the transition to low capability mode. The frame notifying the transition to low capability mode includes at least information indicating the transition to low capability mode and duration information indicating the duration of the low capability mode. As a frame notifying the transition to low capability mode, for example, a frame that can include information indicating the transition to low capability mode and duration information, such as a CTS-to-self frame, which is a CTS frame with the MAC address of the access point device set in the receiving address (RA), can be used. As another example, a frame that includes a broadcast address in the RA can be used. Also, a frame that includes a pre-set unicast address in the RA can be used. Hereinafter, a frame notifying the transition of an access point device to low capability mode is referred to as an AP low capability notification frame (AP LC notification frame).

[0060] When communication control unit 402 in the access point device decides to transition from high capability mode to low capability mode, it generates an AP low capability notification frame and outputs it to wireless transmission unit 403 to instruct transmission. After confirming that wireless transmission unit 403 has completed transmission of the AP low capability notification frame, communication control unit 402 may output an instruction to wireless transmission unit 403 and wireless reception unit 404 to transition to low capability mode. Furthermore, when the duration of low capability mode has expired or when communication control unit 402 in the access point device decides to return from low capability mode to high capability mode, it may output an instruction to wireless transmission unit 403 and wireless reception unit 404 to transition from low capability mode to high capability mode.

[0061] The communication control unit 402 in the access point device may decide to transition from high-capacity mode to low-capacity mode based on criteria such as the presence or absence of data in the transmission buffer, the presence or absence of data in the transmission buffer that has a high priority or a short allowable delay time in terms of QoS settings or access category, the communication status (frequency, transmission rate, data QoS settings and access category, etc.) between the device and a terminal device connected to the device, and, if the device is battery-powered, the remaining battery power.

[0062] When an instruction to transition to low-capacity mode is input from the communication control unit 402, the wireless transmission unit 403 in the access point device may reduce power consumption by stopping the operation of circuits involved in the transmission processing of wireless frames, such as digital-to-analog conversion circuits, filters, oscillators, upconverters, power amplifiers, etc.

[0063] When an instruction to transition to low-capacity mode is input from the communication control unit 402, the wireless receiving unit 404 in the access point device may reduce power consumption by stopping all or part of the operation of circuits involved in the reception processing of wireless frames, such as a low-noise amplifier (LNA), oscillator, downconverter, filter, analog-to-digital converter, etc.

[0064] In this way, when an access point device transitions to low capability mode, it transmits an AP low capability notification frame, thereby setting a NAV for surrounding wireless communication devices that may become communication partners during the low capability mode. This prevents surrounding wireless communication devices from transmitting frames addressed to the access point device while the access point device is in low capability mode, and prevents frequent frame retransmissions and disconnections with terminal devices that are caused by limitations in the processing power of the access point device.

[0065] However, if there are wireless communication devices in the vicinity that belong to a BSS other than the BSS formed by the access point device and that are able to receive the AP low capability notification frame, simply transmitting the AP low capability notification frame will prevent those wireless communication devices, i.e., wireless communication devices in the BSS as seen from the access point device, from transmitting frames. To avoid this problem, the NAV update conditions in carrier sense unit 405 are set as follows:

[0066] First, carrier sense unit 405 updates the basic NAV value with the value of the duration information of the received frame when all of the following four conditions are met: [Condition 1] The received frame is identified as an inter-BSS frame, or cannot be identified as either an intra-BSS frame or an inter-BSS frame. [Condition 2] The duration information of the received frame is greater than the current basic NAV value. [Condition 3] The receiving address (RA) of the received frame is not the address of the own device. [Condition 4] The received frame is not an AP low capability notification frame.

[0067] It should be noted that legacy wireless communication devices including the legacy terminal devices 103-1 and 103-2 cannot identify the AP low capability notification frame, and therefore condition 4 of the basic NAV update conditions is not taken into consideration in the determination.

[0068] Similarly, the carrier sense unit 405 updates the value of the intra-BSS NAV with the value of the duration information of the received frame when at least the following three conditions are met: [Condition 1] The received frame is identified as an intra-BSS frame. [Condition 2] The duration information of the received frame is greater than the current intra-BSS NAV value. [Condition 3] The RA of the received frame is not the address of the own device, the own device is not the TXOP holder and the received frame is a frame requesting an immediate response, or the own device is not the TXOP holder and the received frame is a trigger frame intended to prompt a response action from the communication partner.

[0069] The carrier sense unit 405 determines that the virtual CS is in an idle state if both the basic NAV and the intra-BSS NAV are 0, and determines that the virtual CS is in a busy state if at least one NAV is non-zero.

[0070] As a result of the above, a wireless communication device does not need to update its NAV when it receives an AP low capability notification frame from an access point device of a BSS other than the BSS to which the device belongs, thereby reducing the impact of access point devices of different BSSs transitioning to low capability mode.

[0071] Fig. 5 shows an example of a timing chart in the wireless communication system according to this embodiment. The configuration of the wireless communication devices in Fig. 5 is the same as that in Fig. 1, and includes an access point device 101-1, a terminal device 102-1, and a legacy terminal device 103-1 that constitute BSS 100-1, and an access point device 101-2, a terminal device 102-2, and a legacy terminal device 103-2 that constitute BSS 100-2. It is assumed that the basic NAV and intra-BSS NAV of all wireless communication devices are 0 as an initial state, and that neither of the two access point devices is in low capability mode. Also, Fig. 5 assumes an example in which a CTS-to-self frame is used as the AP low capability notification frame, but this is not limiting. Fig. 5 shows an example of a timing chart from when the access point device 101-1 transitions to low capability mode to when it returns to high capability mode.

[0072] The access point device 101-1 is initially in high capability mode M501, and when it decides to transition to low capability mode, it generates an AP low capability notification frame F510 and transmits it after a backoff procedure S506. During the period from time T504 when the transmission of the AP low capability notification frame F510 is completed to time T505 when the low capability mode duration expires, the access point device 101-1 transitions to low capability mode M502.

[0073] When the terminal device 102-1 and legacy terminal device 100-1 belonging to the BSS 100-1 constituting the access point device 101-1 receive the AP low capability notification frame F510, the above-mentioned intra-BSS NAV update conditions are met, so the intra-BSS NAV is updated based on the value of the duration information in the AP low capability notification frame F510 to non-zero states S507 and S508, and the virtual carrier sense enters a busy state during the period from time T504 to time T505.

[0074] On the other hand, the access point device 101-2, terminal device 102-2, and legacy terminal device 103-2 belonging to BSS 100-2 identify AP low capability notification frame F510 as an inter-BSS frame. The access point device 101-2 and terminal device 102-2 identify frame F510 as an AP low capability notification frame and do not update their basic NAV, but the legacy terminal device 103-2 cannot identify the AP low capability notification frame F510, so its basic NAV is updated by the value of the duration information in the AP low capability notification frame F510, as with other inter-BSS frames, to enter a non-zero state S509, and the virtual CS enters a busy state during the period from time T504 to time T505.

[0075] As a result, while access point device 101-1 is in low capability mode, frame transmissions addressed to access point device 101-1 can be suppressed, and frequent frame retransmissions and disconnections of terminal devices belonging to BSS 100-1 can be avoided.

[0076] At expiration time T505 of the low capability mode duration, the access point device 101-1 transitions from low capability mode M502 to high capability mode M503, and the intra-BSS NAV of the terminal device 102-1 and the legacy terminal device 103-1 becomes 0 and the virtual carrier sense becomes idle. Similarly, the basic NAV of the legacy terminal device 103-2 becomes 0 and the virtual CS becomes idle.

[0077] Fig. 6 shows an example of a timing chart in the wireless communication system according to this embodiment. Fig. 6 is an example of a timing chart in which terminal device 102-2 belonging to BSS 100-2 transmits data after access point device 101-1 transitions to low capability mode M502 in the same flow as Fig. 5, and parts with the same reference numerals as Fig. 5 are the same as Fig. 5. Explanation of parts similar to Fig. 5 will be omitted.

[0078] Because the basic NAV of the terminal device 102-2 is not updated by the AP low capability notification frame F510, the virtual CS remains in the idle state and frame transmission is possible. Even when the access point device 101-1 is in the low capability mode M502, when data to be transmitted to the access point device 101-2 occurs, the terminal device 102-2 transmits an RTS frame F608 to the access point device 101-2 after a backoff procedure S603. At this time, the duration information of the RTS frame F608 may be set to a duration obtained by summing the durations of the CTS frame F609, data frame F610, and Ack frame F611 that are scheduled to follow the RTS frame F608, and three SIFS intervals between those frames.

[0079] A wireless communication device belonging to BSS100-1 that has received an RTS frame F608 not addressed to itself updates its basic NAV with the value of the duration information in RTS frame F608, causing the basic NAV to become non-zero (S604, S605, S606).Furthermore, another wireless communication device belonging to BSS100-2 that has received an RTS frame F608 not addressed to itself updates its intra-BSS NAV with the value of the duration information in RTS frame F608, causing the intra-BSS NAV to become non-zero (S607).

[0080] When the access point device 101-2 receives the RTS frame F608 addressed to itself, if it is in a state where it can receive data, it transmits a CTS frame F609 to the terminal device 102-2 after the specified IFS period, SIFS, following the RTS frame F608, without going through the backoff procedure.

[0081] The terminal device 102-2 that has received the CTS frame F609 does not follow the backoff procedure, and transmits a data frame F610 addressed to the access point device 101-2 SIFS after the CTS frame F609.

[0082] Upon receiving the data frame F610, the access point device 101-2 performs error detection on the data frame F610, and if no error is detected, transmits an Ack frame F611 to the terminal device 102-2 SIFS after the data frame F610 without going through the backoff procedure.

[0083] In addition, in Figure 6, an example is shown in which terminal device 102-2 exchanges RTS frame F608 and CTS frame F609 and then transmits data frame F610, but if the length of data frame F610 is shorter than a predetermined length, it may transmit data frame F610 after backoff procedure S603 without exchanging RTS frame F608 and CTS frame F609.

[0084] As a result of the above, even if access point device 101-1 transmits AP low capability notification frame F510, wireless communication devices (access point device 101-2, terminal device 102-2) belonging to BSS 100-2, which is a different BSS from access point device 101-1, can continue to communicate without being affected by access point device 101-1's transition to low capability mode. (Variation 1)

[0085] Furthermore, when an access point device in the OBSS transitions to the low capability mode, the access point device itself may transition to the low capability mode. For example, when access point device 101-1 transitions to the low capability mode, access point device 101-2 may also transition to the low capability mode.

[0086] Fig. 7 shows an example of a timing chart in the wireless communication system according to this embodiment. Fig. 7 is an example of a timing chart in which access point device 101-1 transitions to low capability mode M502 in the same flow as Fig. 5, and then access point device 101-2 also transitions to low capability mode, and parts with the same reference numerals as Fig. 5 are the same as Fig. 5. Explanation of parts similar to Fig. 5 will be omitted.

[0087] When access point device 101-2, which is in high capability mode M701, receives AP low capability notification frame F510 from access point device 101-1, it determines whether it can also transition to low capability mode. If access point device 101-2 determines that it can transition to low capability mode, it generates AP low capability notification frame F709 and transmits it after backoff procedure S705. The example of FIG. 7 shows a case where the low capability mode expiration time of access point device 101-2 is set to coincide with low capability mode expiration time T505 of access point device 101-1, but this is not limited to this. The low capability mode may also be set to expire earlier or later than time T505. In the example of FIG. 7, the duration information of AP low capability notification frame F709 is set to a duration until time T505. The access point device 101-2 transitions to the low capability mode M702 from the time T704 when the transmission of the AP low capability notification frame F709 is completed to the time T505 when the low capability mode duration expires.

[0088] As a result of the above, in an environment where multiple access point devices exist, the probability that one access point device will transition to low capacity mode in response to the transition of other access point devices to low capacity mode increases, and it becomes possible to avoid frequent periods in which the virtual CS becomes busy due to each access point device transitioning to low capacity mode asynchronously, which would significantly hinder the acquisition of transmission opportunities for legacy wireless communication devices in particular. (Variation 2)

[0089] Another example of wireless communication device 400 according to this embodiment will be described. The configuration of wireless communication device 400 is the same as the configuration example in Fig. 4, but differs in the operation of carrier sense unit 405. Below, differences from the previous example will be described, and explanations of similar parts will be omitted.

[0090] In addition to the basic NAV and intra-BSS NAV, the carrier sense unit 405 also has a third NAV, which is a NAV associated with the low capability mode of the access point device in the BSS to which the carrier sense unit 405 belongs, and is hereinafter referred to as the lower capability NAV (LC NAV).

[0091] First, carrier sense unit 405 updates the basic NAV value with the value of the duration information of the received frame when all of the following three conditions are met: [Condition 1] The received frame is identified as an inter-BSS frame, or cannot be identified as either an intra-BSS frame or an inter-BSS frame. [Condition 2] The duration information of the received frame is greater than the current basic NAV value. [Condition 3] The receiving address (RA) of the received frame is not the address of the device itself.

[0092] Similarly, the carrier sense unit 405 updates the intra-BSS NAV value with the value of the duration information of the received frame when at least the following four conditions are met: [Condition 1] The received frame is identified as an intra-BSS frame. [Condition 2] The duration information of the received frame is greater than the current intra-BSS NAV value. [Condition 3] The RA of the received frame is not the address of the own device, the own device is not the TXOP holder and the received frame is a frame requesting an immediate response, or the own device is not the TXOP holder and the received frame is a trigger frame intended to prompt a response action from the communication partner. [Condition 4] The received frame is not an AP low capability notification frame.

[0093] Furthermore, the carrier sense unit 405 updates the LC NAV value with the value of the duration information of the received frame when at least the following three conditions are met: [Condition 1] The received frame is identified as an intra-BSS frame. [Condition 2] The duration information of the received frame is greater than the current LC NAV value. [Condition 3] The received frame is an AP low capability notification frame.

[0094] The carrier sense unit 405 determines that the virtual CS is in an idle state if all three NAVs, the basic NAV, intra-BSS NAV, and LC NAV, are 0, and determines that the virtual CS is in a busy state if at least one NAV is non-zero. However, the carrier sense unit 405 does not take the LC NAV into consideration for QoS settings, such as frames for which high priority is set in the access category or TID, or frames for which low latency is required, and determines that the virtual CS is in an idle state if two NAVs, the basic NAV and intra-BSS NAV, are 0, and determines that the virtual CS is in a busy state if either the basic NAV or intra-BSS NAV is non-zero.

[0095] FIG. 8 shows an example of a timing chart in the wireless communication system according to this embodiment. The configuration of the wireless communication devices in FIG. 8 is the same as that in FIG. 1, and includes an access point device 101-1, a terminal device 102-1, and a legacy terminal device 103-1 that constitute BSS 100-1, and an access point device 101-2, a terminal device 102-2, and a legacy terminal device 103-2 that constitute BSS 100-2. It is assumed that, as an initial state, the basic NAV and intra-BSS NAV of all wireless communication devices and the LC NAV of wireless communication devices except for the legacy terminal devices 103-1 and 103-2 that do not have LC NAV are 0, and it is also assumed that neither of the two access point devices is in low capability mode. Also, while FIG. 8 assumes an example in which a CTS-to-self frame is used as the AP low capability notification frame, this is not limiting. FIG. 8 shows an example of a timing chart from when the access point device 101-1 transitions to low capability mode to when it returns to high capability mode.

[0096] The access point device 101-1 is initially in high capability mode M801. When it decides to transition to low capability mode, it generates an AP low capability notification frame F812 and transmits it after a backoff procedure S806. From the time T804 when the transmission of the AP low capability notification frame F812 is completed to the time T805 when the low capability mode duration expires, the access point device 101-1 transitions to low capability mode M802. At this time, the access point device 101-1 transitions to a low capability mode in which its reception capability is restricted, and may be able to receive frames with predetermined settings, such as frames or non-HT PPDU frames restricted by configurations (parameters) such as a frequency bandwidth of 20 MHz, an MCS with a minimum transmission rate, a spatial multiplexing number of 1, and one wireless link, although the configurations (parameters) of the restricted frames are not limited to these. Alternatively, the access point device 101-1 may be in a state in which it does not transmit frames.

[0097] When terminal device 102-1 belonging to BSS100-1 constituting access point device 101-1 receives AP low capability notification frame F812, the above-mentioned LC NAV update conditions are met, so the LC NAV is updated based on the value of the duration information in AP low capability notification frame F812 to a non-zero state S807, and the virtual carrier sense is in a busy state except for some frames during the period from time T804 to time T805.

[0098] In the legacy terminal device 100-1 belonging to the BSS 100-1 constituting the access point device 101-1, when the AP low capability notification frame F812 is received, the above-mentioned intra-BSS NAV update conditions are met, so the intra-BSS NAV is updated based on the value of the duration information in the AP low capability notification frame F812 to a non-zero state S808, and the virtual carrier sense enters a busy state during the period from time T804 to time T805.

[0099] On the other hand, in the access point device 101-2, terminal device 102-2, and legacy terminal device 103-2 belonging to BSS100-2, the AP low capability notification frame F812 is identified as an inter-BSS frame, and the basic NAV is updated based on the value of the duration information of the AP low capability notification frame F810 to become non-zero states S809, S810, and S811, and the virtual CS becomes busy during the period from time T804 to time T805.

[0100] At expiration time T805 of the low capability mode duration, the access point device 101-1 transitions from low capability mode M802 to high capability mode M803, the LC NAV of the terminal device 102-1 and the intra-BSS NAV of the legacy terminal device 103-1 become 0, and the virtual carrier sense enters the idle state. Similarly, in the access point device 101-2, terminal device 102-2, and legacy terminal device 103-2 belonging to BSS 100-2, the basic NAV becomes 0 and the virtual CS enters the idle state.

[0101] As a result, while access point device 101-1 is in low capability mode, frame transmissions addressed to access point device 101-1 can be suppressed, and frequent frame retransmissions and disconnections of terminal devices belonging to BSS 100-1 can be avoided.

[0102] FIG. 9 shows an example of a timing chart in the wireless communication system according to this embodiment. FIG. 9 is an example of a timing chart in which the terminal device 101-2 transmits a frame requiring a low latency time after the access point device 101-1 transitions to the low capability mode M901 according to the same flow as in FIG. 8, and parts with the same reference numerals as in FIG. 8 are the same as in FIG. 8. Description of parts similar to FIG. 8 will be omitted. Note that FIG. 8 illustrates an example in which a frame requiring a low latency time is transmitted, but this is not limiting. The frame may be a frame for transmitting data for which a high priority is set in a QoS setting, for example, an access category or TID, or a frame for transmitting data that has been held in a transmission buffer for a longer period than a predetermined time. Furthermore, the access point device 101-1 may notify information regarding frames that are permitted to be transmitted to the device itself even when the device is in the low capability mode by including the information in an AP low capability notification frame F812 or a beacon frame.

[0103] The terminal device 102-1 receives the AP low capability notification frame F812 and is in state S807 with a non-zero LC NAV. When data requiring low latency occurs while in state S807, the terminal device 102-1 determines that the virtual CS is in the idle state by referring to the two NAVs, the basic NAV and the intra-BSS NAV, without taking the LC NAV into consideration, and after a random backoff procedure S906, transmits an RTS frame F907 to the access point device 101-1 requesting permission to transmit.

[0104] When access point device 101-1 detects and receives RTS frame F907 that can be received in low capability mode, it transitions from low capability mode M901 to high capability mode M902, and transmits CTS frame F908, which is a response frame to RTS frame F907, at time T904, SIFS after RTS frame F907. Note that, although Fig. 9 illustrates the timing at which access point device 101-1 switches from low capability mode M901 to high capability mode M902 as starting transmission of CTS frame F908, it may switch earlier.

[0105] Upon receiving the CTS frame F908, the terminal device 102-1 transmits, after an SIFS, a data frame F909 for transmitting data requiring a low latency time to the access point device 101-1.

[0106] When the access point device 101-1 receives the data frame F909 without error, it transmits an Ack frame F910 to the terminal device 102-1 after a SIFS. If the duration notified in the AP low capability notification frame F812 remains at time T905 when transmission of the Ack frame F910 is completed, the access point device 101-1 may again transition from the high capability mode M902 to the low capability mode M903.

[0107] In addition, in Figure 9, an example is shown in which terminal device 102-2 exchanges RTS frame F907 and CTS frame F908 before transmitting a data frame, but if the length of data frame F909 is shorter than a predetermined length, it may transmit data frame F909 after backoff procedure S603 without exchanging RTS frame F907 and CTS frame F908.

[0108] As a result of the above, when a high-priority frame, such as a frame requiring a low delay time, occurs in terminal device 102-1 while access point device 101-1 is in low-capability mode, terminal device 102-1 can transmit the frame with a low delay time as a priority. (Variation 3)

[0109] Another example of wireless communication device 400 according to this embodiment will be described. The configuration of wireless communication device 400 is the same as the configuration example in Fig. 4, but differs in the operation of carrier sense unit 405. Below, differences from the previous example will be described, and explanations of similar parts will be omitted.

[0110] In addition to the basic NAV and intra-BSS NAV, the carrier sense unit 405 also has a third NAV, which is a NAV associated with the low capability mode of the access point device in the BSS to which the carrier sense unit 405 belongs, and is hereinafter referred to as the low capability NAV (LC NAV).

[0111] First, carrier sense unit 405 updates the basic NAV value with the value of the duration information of the received frame when all of the following four conditions are met: [Condition 1] The received frame is identified as an inter-BSS frame, or cannot be identified as either an intra-BSS frame or an inter-BSS frame. [Condition 2] The duration information of the received frame is greater than the current basic NAV value. [Condition 3] The receiving address (RA) of the received frame is not the address of the own device. [Condition 4] The received frame is not an AP low capability notification frame.

[0112] Similarly, the carrier sense unit 405 updates the intra-BSS NAV value with the value of the duration information of the received frame when at least the following four conditions are met: [Condition 1] The received frame is identified as an intra-BSS frame. [Condition 2] The duration information of the received frame is greater than the current intra-BSS NAV value. [Condition 3] The RA of the received frame is not the address of the own device, the own device is not the TXOP holder and the received frame is a frame requesting an immediate response, or the own device is not the TXOP holder and the received frame is a trigger frame intended to prompt a response action from the communication partner. [Condition 4] The received frame is not an AP low capability notification frame.

[0113] Furthermore, the carrier sense unit 405 updates the LC NAV value with the value of the duration information of the received frame when at least the following three conditions are met: [Condition 1] The received frame is identified as an intra-BSS frame. [Condition 2] The duration information of the received frame is greater than the current LC NAV value. [Condition 3] The received frame is an AP low capability notification frame.

[0114] The carrier sense unit 405 determines that the virtual CS is in an idle state if all three NAVs, the basic NAV, intra-BSS NAV, and LC NAV, are 0, and determines that the virtual CS is in a busy state if at least one NAV is non-zero. However, the carrier sense unit 405 does not take the LC NAV into consideration for QoS settings, such as frames for which high priority is set in the access category or TID, or frames for which low latency is required, and determines that the virtual CS is in an idle state if two NAVs, the basic NAV and intra-BSS NAV, are 0, and determines that the virtual CS is in a busy state if either the basic NAV or intra-BSS NAV is non-zero.

[0115] Fig. 10 shows an example of a timing chart in the wireless communication system according to this embodiment. The configuration of the wireless communication devices in Fig. 10 is the same as that in Fig. 1, and includes an access point device 101-1, a terminal device 102-1, and a legacy terminal device 103-1 that constitute BSS 100-1, and an access point device 101-2, a terminal device 102-2, and a legacy terminal device 103-2 that constitute BSS 100-2. It is assumed that, as an initial state, the basic NAV and intra-BSS NAV of all wireless communication devices, and the LC NAV of wireless communication devices except for the legacy terminal devices 103-1 and 103-2 that do not have LC NAV, are 0, and it is also assumed that neither of the two access point devices is in low capability mode. Furthermore, Fig. 10 assumes an example in which a CTS-to-self frame is used as the AP low capability notification frame, but this is not limiting. Fig. 10 shows an example of a timing chart from when the access point device 101-1 transitions to low capability mode to when it returns to high capability mode.

[0116] The access point device 101-1 is initially in high capability mode M1001. When it decides to transition to low capability mode, it generates an AP low capability notification frame F1010 and transmits it after a backoff procedure S1006. From the time T1004 when the transmission of the AP low capability notification frame F1010 is completed to the time T1005 when the low capability mode duration expires, the access point device 101-1 transitions to low capability mode M1002. At this time, the access point device 101-1 transitions to a low capability mode in which its reception capability is restricted, and may be able to receive frames with predetermined settings, such as frames restricted by parameters such as a frequency bandwidth of 20 MHz, an MCS with a minimum transmission rate, a spatial multiplexing number of 1, and one wireless link, or non-HT PPDU frames, although the restricted frame configuration (parameters) is not limited to these. The access point device 101-1 may also be in a state in which it does not transmit frames.

[0117] When terminal device 102-1 belonging to BSS100-1 constituting access point device 101-1 receives AP low capability notification frame F1010, the above-mentioned LC NAV update conditions are met, so the LC NAV is updated based on the value of the duration information in AP low capability notification frame F1010 and becomes a non-zero state S1007, and the virtual carrier sense becomes busy except for some frames during the period from time T1004 to time T1005.

[0118] In the legacy terminal device 100-1 belonging to the BSS100-1 constituting the access point device 101-1, when the AP low capability notification frame F1010 is received, the above-mentioned intra-BSS NAV update conditions are met, so the intra-BSS NAV is updated based on the value of the duration information in the AP low capability notification frame F1010 to a non-zero state S1008, and the virtual carrier sense enters a busy state from time T1004 to time T1005.

[0119] On the other hand, the access point device 101-2, the terminal device 102-2, and the legacy terminal device 103-2 belonging to the BSS 100-2 identify the AP low capability notification frame F1010 as an inter-BSS frame. The access point device 101-2 and the terminal device 102-2 identify the frame F1010 as an AP low capability notification frame and do not update the basic NAV, but the legacy terminal device 103-2 Since the AP low capability notification frame F1010 cannot be identified, the basic NAV is updated according to the value of the duration information of the AP low capability notification frame F1010, as with other inter-BSS frames, to a non-zero state S1009, and the virtual CS is in a busy state from time T1004 to time T1005.

[0120] At expiration time T1005 of the low capability mode duration, the access point device 101-1 transitions from low capability mode M1002 to high capability mode M1003, the terminal device 102-1's LC NAV becomes 0 and the virtual carrier sense becomes idle, and the legacy terminal device 103-1's intra-BSS NAV becomes 0 and the virtual carrier sense becomes idle. Similarly, the legacy terminal device 103-2's basic NAV becomes 0 and the virtual CS becomes idle.

[0121] As a result, while access point device 101-1 is in low capability mode, frame transmissions addressed to access point device 101-1 can be suppressed, and frequent frame retransmissions and disconnections of terminal devices belonging to BSS 100-1 can be avoided.

[0122] FIG. 11 shows an example of a timing chart in the wireless communication system according to this embodiment. FIG. 11 is an example of a timing chart in which the terminal device 101-2 transmits a frame requiring a low latency time after the access point device 101-1 transitions to the low capability mode M1101 according to the same flow as in FIG. 10. Parts with the same reference numerals as in FIG. 10 are the same as in FIG. 10. Description of parts similar to FIG. 10 will be omitted. Note that FIG. 10 illustrates an example in which a frame requiring a low latency time is transmitted, but this is not limiting. The example may be a frame for transmitting data for which a high priority is set in a QoS setting, for example, an access category or TID, or a frame for transmitting data that has been held in a transmission buffer for a longer period than a predetermined time. Furthermore, the access point device 101-1 may notify information regarding frames that are permitted to be transmitted to the device itself even when the device is in the low capability mode by including the information in an AP low capability notification frame F1010 or a beacon frame.

[0123] The terminal device 102-1 receives the AP low capability notification frame F1010 and is in state S1007 with a non-zero LC NAV. When data requiring low latency occurs while in state S1007, the terminal device 102-1 determines that the virtual CS is in an idle state by referring to two NAVs, the basic NAV and intra-BSS NAV, without considering the LC NAV, and after a random backoff procedure S1106, transmits an RTS frame F1109 requesting permission to transmit to the access point device 101-1. At this time, the duration information of the RTS frame F1109 may be set to a duration calculated by adding together the durations of the CTS frame F1110, low latency data frame F1111, and Ack frame F1112 that are scheduled to follow the RTS frame F1109, and three SIFS intervals between those frames.

[0124] When access point device 101-1 detects and receives an RTS frame F1109 that can be received in low capability mode, it transitions from low capability mode M1101 to high capability mode M1102, and transmits a CTS frame F1110 that is a response frame to the RTS frame F1109 at time T1104, SIFS after the RTS frame F1109. Note that, in Fig. 11, the timing at which access point device 101-1 switches from low capability mode M1101 to high capability mode M1102 is shown as the same as the start timing of transmission of the CTS frame F1110, but the switching may occur earlier.

[0125] When the access point device 101-2 and the terminal device 102-2, which belong to a different BSS from the terminal device 102-1, receive the RTS frame F1109, they identify it as an inter-BSS frame and update their basic NAVs with the value of the duration information included in the RTS frame F1109. As a result, the basic NAVs of the access point device 101-2 and the terminal device 102-2 become non-zero (S1107, S1108), and the virtual CS becomes busy during the period from time T1104 to time T1105.

[0126] Upon receiving the CTS frame F1110, the terminal device 102-1 transmits, after an SIFS, a data frame F1111 for transmitting data requiring a low latency time, addressed to the access point device 101-1.

[0127] When the access point device 101-1 receives the data frame F1111 without error, it transmits an Ack frame F1112 to the terminal device 102-1 after a SIFS. If the duration notified in the AP low capability notification frame F1010 remains at time T1105 when transmission of the Ack frame F1112 is completed, the access point device 101-1 may again transition from the high capability mode M1102 to the low capability mode M1103.

[0128] In addition, in Figure 11, an example is shown in which terminal device 102-2 exchanges RTS frame F1109 and CTS frame F1110 and then transmits data frame F1111, but if the length of data frame F1111 is shorter than a predetermined length, data frame F1111 may be transmitted after backoff procedure S603 without exchanging RTS frame F1109 and CTS frame F1110.

[0129] As a result of the above, when a high-priority frame, such as a frame requiring a low delay time, occurs in terminal device 102-1 while access point device 101-1 is in low-capability mode, terminal device 102-1 can transmit the frame with a low delay time as a priority.

[0130] Fig. 12 shows an example of a timing chart in the wireless communication system according to this embodiment. Fig. 12 is an example of a timing chart in which terminal device 102-2 belonging to BSS 100-2 transmits data after access point device 101-1 transitions to low capability mode M1002 in the same flow as Fig. 10, and parts with the same reference numerals as Fig. 10 are the same as Fig. 10. Explanation of parts similar to Fig. 10 will be omitted.

[0131] Because the basic NAV of the terminal device 102-2 is not updated by the AP low capability notification frame F1010, the virtual CS remains in the idle state and frame transmission is possible. Even when the access point device 101-1 is in the low capability mode M1002, when data to be transmitted to the access point device 101-2 occurs, the terminal device 102-2 transmits an RTS frame F1207 to the access point device 101-2 after a backoff procedure S1203. At this time, the duration information of the RTS frame F1207 may be set to a duration obtained by summing the durations of the CTS frame F1208, data frame F1209, and Ack frame F1210 that are scheduled to follow the RTS frame F1207, and three SIFS intervals between those frames.

[0132] A wireless communication device belonging to BSS100-1 that receives an RTS frame F1207 not addressed to the device itself updates its basic NAV with the value of the duration information in the RTS frame F1207 (S1204, S1205). Also, another wireless communication device belonging to BSS100-2 that receives an RTS frame F1207 not addressed to the device itself updates its intra-BSS NAV with the value of the duration information in the RTS frame F1207 (S1206).

[0133] When the access point device 101-2 receives the RTS frame F1207 addressed to itself, if it is in a state where it can receive data, it transmits a CTS frame F1208 to the terminal device 102-2 after a SIFS following the RTS frame F1207 without going through the backoff procedure.

[0134] The terminal device 102-2 that has received the CTS frame F1208 does not follow the backoff procedure, but transmits a data frame F1209 addressed to the access point device 101-2 SIFS after the CTS frame F1208.

[0135] Upon receiving the data frame F1209, the access point device 101-2 performs error detection on the data frame F1209, and if no error is detected, transmits an Ack frame F1210 to the terminal device 102-2 SIFS after the data frame F1209 without going through the backoff procedure.

[0136] In addition, in Figure 12, an example is shown in which terminal device 102-2 exchanges RTS frame F1207 and CTS frame F1208 and then transmits data frame F1209, but if the length of data frame F1209 is shorter than a predetermined length, it may transmit data frame F1209 after backoff procedure S603 without exchanging RTS frame F1207 and CTS frame F1208.

[0137] As a result of the above, even if access point device 101-1 transmits AP low capability notification frame F1010, wireless communication devices (access point device 101-2, terminal device 102-2) belonging to BSS100-2, which is a different BSS from access point device 101-1, can continue communicating without being affected by access point device 101-1's transition to low capability mode.

[0138] Fig. 13 shows an example of a timing chart in the wireless communication system according to this embodiment. Fig. 13 is an example of a timing chart in which access point device 101-1 transitions to low capability mode M1002 in the same flow as Fig. 10, and then access point device 101-2 also transitions to low capability mode, and parts with the same reference numerals as Fig. 10 are the same as Fig. 10. Explanation of parts similar to Fig. 10 will be omitted.

[0139] When access point device 101-2, which is in high capability mode M1301, receives AP low capability notification frame F1010 from access point device 101-1, it determines whether it can also transition to low capability mode. If access point device 101-2 determines that it can transition to low capability mode, it generates AP low capability notification frame F1309 and transmits it after backoff procedure S1305. The example of FIG. 13 shows a case where the low capability mode expiration time of access point device 101-2 is set to coincide with low capability mode expiration time T1005 of access point device 101-1, but this is not limited to this. The low capability mode may also be set to expire earlier or later than time T1005. In the example of FIG. 13, the duration information of AP low capability notification frame F1309 is set to a duration up to time T1005. During the period from time T1304 when the transmission of the AP low capability notification frame F1309 is completed to time T1005 when the low capability mode duration expires, the access point device 101-2 transitions to the low capability mode M1302.

[0140] As a result of the above, in an environment where multiple access point devices exist, the probability that one access point device will transition to low capacity mode in response to the transition of other access point devices to low capacity mode increases, and it becomes possible to avoid frequent periods in which the virtual CS becomes busy due to each access point device transitioning to low capacity mode asynchronously, which would significantly hinder the acquisition of transmission opportunities for legacy wireless communication devices in particular. (Common to all embodiments)

[0141] The wireless 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 wireless communication device according to the present invention can also be effective in 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 for the purpose of preventing interference between frequencies even though permission to use it for a specific service is granted by a country or region, or in a shared spectrum (shared frequency band) that is expected to be shared by multiple operators.

[0142] 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, nonvolatile memory cards, solid-state drives, 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 based on instructions from the program.

[0143] 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 also falls within the scope of the present invention. Furthermore, part or all of the wireless communication device in the above-described embodiments may be realized as an LSI, which is typically an integrated circuit. Each functional block of the wireless 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 for controlling them is added. It goes without saying that the present invention also includes cases where programs and setting information are downloaded from a server computer to implement at least part of the functions of the above-described embodiments.

[0144] 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.

[0145] 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 and washing machines, air conditioners, office equipment, vending machines, and other household appliances.

[0146] 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]

[0147] The present invention is suitable for use in a wireless communication device and a wireless communication method. [Explanation of symbols]

[0148] 100-1, 100-2 Basic Service Set 101-1, 101-2 Access point devices 102-1, 102-2 terminal equipment 103-1, 103-2 Legacy terminal equipment 400 Wireless communication device 401 Upper Tier 402 Communication control unit 403 Radio transmitter 404 Radio receiver 405 Career Sense Department 406 Antenna section M501, M503, M701, M703, M801, M803, M902, M1001, M1003, M1102 High Capacity Mode M502, M702, M802, M901, M903, M1002, M1101, M1103 Low capacity mode F510, F709, F812, F1010 CTS-to-self frame (AP low capability notification frame) F608, 907, F1109, F1207 RTS Frame F609, F908, F1110, F1208 CTS frame F610, F1209 data frame F611, F910, F1112, F1210 Ack Frame F909, F1111 Low latency data frame

Claims

1. A wireless communication device that belongs to a first basic service set (BSS) and performs wireless communication, A radio receiver and a carrier sense unit are provided, the carrier sense unit performs virtual carrier sensing using a first network allocation vector (NAV), a second NAV, and a third NAV; When the wireless receiving unit receives a frame, if a first condition is satisfied, the first NAV is updated with a first duration period included in the received frame, if a second condition is satisfied, the second NAV is updated with the first duration period, and if a third condition is satisfied, the third NAV is updated with the first duration period; The first condition is: the received frame is identified as a frame of a BSS different from the first BSS, or is identifiable as neither a frame of the first BSS nor a frame of a BSS different from the first BSS; the first duration is greater than the current first NAV value; The receiving address of the received frame is not the address of the own device. The received frame is not a frame informing the access point device of its transition to a low capability mode. At least The second condition is: the received frame is identified as a frame of the first BSS; the first duration is greater than the current second NAV value; The receiving address of the received frame is not the address of the own device, the own device is not a transmission opportunity holder and the received frame is not a frame requiring an immediate response, or the own device is not a transmission opportunity holder and the received frame is a trigger frame. The received frame is not a frame informing the access point device of its transition to a low capability mode. At least The third condition is: the received frame is identified as a frame of the first BSS; the first duration is greater than the current third NAV value; The received frame is a frame notifying the access point device that it will transition to a low capability mode. A wireless communication device comprising at least:

2. a wireless transmission unit that transmits frames; The carrier sense unit performs virtual carrier sense using the first NAV and the second NAV without taking the third NAV into consideration when transmitting a predetermined frame.

2. The wireless communication device according to claim 1.

3. The wireless communication device is an access point device, A communication control unit is further provided, When the communication control unit determines to transition from the high capacity mode to the low capacity mode, the communication control unit generates a first frame notifying the transition to the low capacity mode; the wireless transmission unit transmits the first frame; The first frame includes at least information indicating a transition to the low capacity mode and duration information indicating a duration of the low capacity mode.

2. The wireless communication device according to claim 1.

4. A communication method in a wireless communication device that belongs to a first BSS and performs wireless communication, receiving a frame; performing a virtual carrier sense using the first NAV, the second NAV, and the third NAV; When a frame is received, if a first condition is satisfied, updating the first NAV with a first duration included in the received frame; updating the second NAV with the first duration if a second condition is met when receiving a frame; and updating the third NAV with the first duration if a third condition is met when receiving a frame; The first condition is: the received frame is identified as a frame of a BSS different from the first BSS, or is identifiable as neither a frame of the first BSS nor a frame of a BSS different from the first BSS; the first duration is greater than the current first NAV value; The receiving address of the received frame is not the address of the own device. The received frame is not a frame informing the access point device of its transition to a low capability mode. At least The second condition is: the received frame is identified as a frame of the first BSS; the first duration is greater than the current second NAV value; The receiving address of the received frame is not the address of the own device, the own device is not a transmission opportunity holder and the received frame is not a frame requiring an immediate response, or the own device is not a transmission opportunity holder and the received frame is a trigger frame. The received frame is not a frame informing the access point device of its transition to a low capability mode. At least The third condition is: the received frame is identified as a frame of the first BSS; the first duration is greater than the current third NAV value; The received frame is a frame notifying the access point device that it will transition to a low capability mode. A wireless communication method comprising at least:

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