Access point device, station device, and communication method

Abstract

This station device communicates with a first access point device and a second access point device and comprises: a reception unit that receives a low-latency announcement (LLA) frame from the second access point device; and a transmission unit that transmits a low-latency (LL) physical protocol data unit (PPDU) to the first access point device on the basis of the LLA frame. The LLA frame includes information indicating a plurality of resource units (RUs) used for the LL PPDU, and allocates the LL PPDU to at least one RU randomly selected from the plurality of RUs.

Description

Access point device, station device and communication method

[0001] The present application claims priority to Japanese Patent Application No. 2024-130173, filed on Aug. 6, 2024, the contents of which are incorporated herein by reference.

[0002] The Institute of Electrical and Electronics Engineers Inc. (IEEE) continues to update the specifications of the wireless LAN (Local Area Network) standard, IEEE 802.11, to achieve faster wireless LAN communications and more efficient frequency utilization. Wireless LANs enable wireless communication using unlicensed frequency bands, which can be used without a license from a national or regional authority. For personal use, such as at home, wireless Internet access from within a home has become possible by incorporating a wireless LAN access point function into a line termination device for connecting to a WAN (Wide Area Network) line to the Internet, or by connecting a wireless LAN access point device to the line termination device. This allows wireless LAN station devices, such as smartphones and personal computers, to connect to the wireless LAN access point device and access the Internet.

[0003] The IEEE 802.11ax standard was completed in 2021, and wireless LAN devices compliant with this standard, as well as communication devices such as smartphones and personal computers equipped with such wireless LAN devices, have appeared on the market as Wi-Fi 6 (a registered trademark, the name for IEEE 802.11ax-compliant products certified by the Wi-Fi Alliance). Currently, standardization activities for IEEE 802.11be, the successor standard to IEEE 802.11ax, are underway, and discussions are also underway for its successor, IEEE 802.11bn. With the rapid spread of wireless LAN devices, recent IEEE 802.11 standardization efforts are being considered to further improve throughput per user in environments where wireless LAN devices are densely deployed.

[0004] In the IEEE 802.11be standardization, discussions are underway regarding multi-link operation (MLO), which enables wireless communication devices to simultaneously maintain multiple link connections using multiple frequency bands, channels, etc. (see Non-Patent Document 1). One example of MLO is the simultaneous operation of three link connections in different frequency bands: a 2.4 GHz band connection, a 5 GHz band (5.2 GHz band, 5.3 GHz band, 5.6 GHz band, etc.), and a 6 GHz band connection. Of course, the combinations of frequency bands, channels, etc. are not limited to these, and various combinations are possible. In terms of frequency bands, in the future, high-frequency bands such as millimeter waves (28 GHz band, 45 GHz band, 60 GHz band, etc.) and (sub)terahertz waves (100 GHz to 300 GHz band) may also be used as one link constituting a multi-link. MLO allows wireless communication devices to simultaneously maintain multiple link connections using different wireless resources and communication settings. A wireless communication device can not only transmit and receive frames using multiple links simultaneously, but also switch the link connections for transmitting and receiving frames, i.e., change the frequency band, without performing a reconnection operation. Note that each link constituting a multilink is also called a physical layer link. A wireless communication device that supports MLO is called a multi-link device (MLD).

[0005] In addition, in the IEEE 802.11bn standardization, discussions are being held on preemption technology, which transmits generated traffic with low latency to support applications that require low-latency communications, such as VR / AR (Non-Patent Document 2). Generally, in wireless LANs where channel access is based on CSMA / CA, generated traffic cannot always be transmitted with the desired latency. Therefore, preemption secures wireless media in advance, thereby improving latency at the expense of frequency utilization efficiency.

[0006] IEEE 802.11-19 / 0773-08-00be, Nov. 2019IEEE 802.11-23 / 1886r3, Jan. 2024

[0007] Preemption technology is based on the premise that a wireless communication device reserves a wireless medium in advance. Furthermore, a wireless communication device can allow other wireless communication devices to use part of the wireless medium it has reserved. For example, an access point device can transmit low-latency traffic to a station device under its control. However, if a station device transmits low-latency traffic on an uplink while the access point device is performing downlink transmission on the wireless medium reserved by the access point device, the access point device will simultaneously perform downlink transmission and uplink reception, which can lead to issues such as increased hardware costs and reduced communication quality due to self-interference.

[0008] In order to solve the above-mentioned problems, an access point device, a station device, and a communication method according to one aspect of the present invention are as follows.

[0009] (1) That is, a station device according to one aspect of the present invention is a station device that communicates with a first access point device and a second access point device, and includes a receiving unit that receives an LLA (Low Latency Announcement) frame from the second access point device, and a transmitting unit that transmits an LL (Low Latency) PPDU (Physical Protocol Data Unit) to the first access point device based on the LLA frame, wherein the LLA frame includes information indicating a plurality of RUs (Resource Units) to be used for the LL PPDU, and the LL PPDU is assigned to at least one RU randomly selected from the plurality of RUs.

[0010] (2) Also, a station device according to one aspect of the present invention is described in (1) above, and when the LLA frame is an Inter BSS (Basic Service Set) PPDU, it enters spatial reuse operation without using multiple RUs used in the LL PPDU.

[0011] (3) Furthermore, a station device according to one aspect of the present invention is described in (1) above and transmits an LL trigger frame that triggers the LL PPDU to another station device.

[0012] (4) Furthermore, a station device according to one aspect of the present invention is described in (3) above, and if the LLA frame is an Intra BSS PPDU, sets an LL NAV (Network Allocation Vector) associated with the LL PPDU. If the LL NAV is set, the station device receives a trigger frame that triggers the LL PPDU, and if the Duration information described in the trigger frame indicates a value greater than the LL NAV, updates the LL NAV.

[0013] (5) Also, an access point device according to one aspect of the present invention is a first access point device that communicates with a station device, and includes a receiving unit that determines whether a wireless medium is idle, a transmitting unit that generates frames, and a control unit that controls the wireless medium, wherein the transmitting unit has a function of transmitting low latency traffic, and when the receiving unit determines that the wireless medium is idle, the transmitting unit transmits a frame including information indicating a time interval associated with the low latency traffic.

[0014] (6) Also, an access point device according to one aspect of the present invention is described in (5) above, wherein the control unit sets a PE (Pre-emption) resource in the wireless medium that allows transmission of an LL PPDU and divides the PE resource into a plurality of RUs, the transmission unit generates an LLA frame that includes information indicating a position of the PE resource and information indicating the plurality of RUs, the LLA frame includes a DATA field, and a pilot tone is set in the DATA field, and the transmission unit transmits the LLA frame in the wireless medium.

[0015] (7) Furthermore, an access point device according to one aspect of the present invention is described in (6) above, and further communicates with a second access point device, notifies the second access point device of information associated with the LLA frame, and instructs the second access point device to transmit the LLA frame.

[0016] (8) Also, a communication method according to one aspect of the present invention is a communication method for a first access point device and a station device communicating with a second access point device, comprising the steps of receiving an LLA (Low Latency Announcement) frame from the second access point device and transmitting an LL (Low Latency) PPDU (Physical Protocol Data Unit) to the first access point device based on the LLA frame, wherein the LLA frame includes information indicating a plurality of RUs (Resource Units) used for the LL PPDU, and further comprising the step of allocating the LL PPDU to at least one RU randomly selected from the plurality of RUs.

[0017] According to the access point device, station device, and communication method of the present invention, interference power can be suppressed even in an environment where low-latency traffic due to preemption and normal traffic are mixed, thereby contributing to improving frequency utilization efficiency.

[0018] FIG. 1 is a diagram showing an example of a MAC layer frame configuration related to a wireless LAN system. FIG. 2 is a diagram showing an example of a PPDU configuration related to a wireless LAN system. FIG. 3 is a diagram showing an example of a sounding procedure related to a wireless LAN system. FIG. 4 is a diagram showing an example of a configuration of a communication system according to an aspect of the present invention. FIG. 5 is a block diagram showing an example of a configuration of a station device according to an aspect of the present invention. FIG. 6 is a block diagram showing an example of a configuration of an access point device according to an aspect of the present invention. FIG. 7 is a diagram showing an example of a configuration of a communication system according to an aspect of the present invention. FIG. 8 is a diagram showing an example of a configuration of a signal configuration related to an aspect of the present invention. FIG. 9 is a diagram showing an example of a configuration of a communication system according to an aspect of the present invention.

[0019] The wireless communication system in this embodiment includes an access point device (also referred to as an AP or base station device) and multiple station devices (also referred to as STAs or terminal devices). The communication system and network configured with the access point device and the station devices are referred to as a basic service set (BSS, management range). The station device according to this embodiment can have the functions of an access point device. Similarly, the access point device according to this embodiment can have the functions of a station device. Therefore, hereinafter, when simply referring to a communication device or a wireless communication device, the communication device or wireless communication device can refer to both the access point device and the station device.

[0020] The access point device and station devices within the BSS communicate based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance). This embodiment focuses on infrastructure mode, in which an access point device communicates with multiple station devices. However, the method of this embodiment can also be implemented in ad hoc mode, in which station devices communicate directly with each other. In ad hoc mode, a single station device acts as an access point device to form a BSS. A BSS in ad hoc mode is also referred to as an IBSS (Independent Basic Service Set). Hereinafter, a station device forming an IBSS in ad hoc mode can also be considered an access point device. The method of this embodiment can also be implemented in Wi-Fi Direct (registered trademark), in which station devices communicate directly with each other. In Wi-Fi Direct, one station device acts as an access point device to form a group. This station device is called a group owner and can also be considered an access point device.

[0021] In the IEEE 802.11 system, each device can transmit multiple types of frames (communication 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.

[0022] A PHY layer frame is called a physical protocol data unit (PPDU, PHY layer frame). A PPDU is composed of a physical layer header (PHY header) containing information for signal processing in the physical layer, and a physical service data unit (PSDU, PHY service data unit), which is a data unit processed in the physical layer. A PSDU can be composed of an aggregated MPDU (A-MPDU), which aggregates multiple MAC protocol data units (MPDU, MAC layer frames), which serve as retransmission units in wireless sections.

[0023] The PHY header includes reference signals such as a short training field (STF) used for signal detection and synchronization, and a long training field (LTF) used to acquire channel information for data demodulation, as well as control signals such as a signal (SIG) containing control information for data demodulation. Furthermore, STF is classified into Legacy-STF (L-STF), High Throughput-STF (HT-STF), Very High Throughput-STF (VHT-STF), High Efficiency-STF (HE-STF), Extremely High Throughput-STF (EHT-STF), etc. depending on the corresponding standard, and LTF and SIG are similarly classified into L-LTF, HT-LTF, VHT-LTF, HE-LTF, L-SIG, HT-SIG, VHT-SIG, HE-SIG, and EHT-SIG. VHT-SIG is further classified into VHT-SIG-A1, VHT-SIG-A2, and VHT-SIG-B. Similarly, HE-SIG is classified into HE-SIG-A1 to HE-SIG-A4 and HE-SIG-B. In addition, a Universal SIGNAL (U-SIG) field containing additional control information may be included, assuming technology updates within the same standard.

[0024] Furthermore, the PHY header 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, a 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.

[0025] The PPDU is modulated according to the corresponding standard, for example, in the case of the IEEE 802.11n standard, it is modulated into an Orthogonal Frequency Division Multiplexing (OFDM) signal.

[0026] An MPDU consists of a MAC header containing information for signal processing at the MAC layer, a MAC Service Data Unit (MSDU) or frame body, which is a data unit processed at the MAC layer, and a Frame Check Sequence (FCS), which checks whether the frame is error-free (see Figure 1). Multiple MSDUs can also be aggregated as an Aggregated MSDU (A-MSDU).

[0027] Frame types in the MAC layer are broadly classified into three types: management frames that manage the connection status between devices, control frames that manage the communication status between devices, and data frames that contain 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. BlockAck can acknowledge (notify completion of reception) multiple MPDUs. Management frames include beacon frames, probe request frames, probe response frames, authentication frames, association request frames, and association response frames. Data frames include data frames and polling (CF-poll) frames. Each device can recognize the frame type and subframe type of a received frame by reading the contents of the frame control field included in the MAC header.

[0028] A beacon frame includes a field indicating the period (beacon interval) at which the beacon is transmitted and the SSID. An access point device can periodically broadcast a beacon frame within a BSS, and a station device can recognize surrounding access point devices by receiving the beacon frame. The act of a station device recognizing an access point device based on a beacon frame broadcast by an access point device is called passive scanning. On the other hand, the act of a station device searching for an access point device by broadcasting a probe request frame within a BSS is called active scanning. An 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 station device performs a connection process with the access point device. The connection process is classified into an authentication procedure and an association procedure. The station device transmits an authentication request frame to the access point device with which it wishes to connect. Upon receiving the authentication request frame, the access point device transmits an authentication response frame to the station device, the authentication response frame including a status code indicating whether the station device has been authenticated. The station device can determine whether its authentication request has been approved by the access point device by reading the status code included in the authentication response frame. The access point device and station 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 station 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 connection of the station device and transmits a connection response frame to notify the determination. The connection response frame contains a status code indicating whether the connection process is successful, as well as an association identifier (AID) for identifying the station device. The access point device can manage multiple station devices by setting different AIDs for each station device to which it has issued connection permission.

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

[0032] First, an example of the operation when an access point device transmits a signal to a station device based on DCF will be described. In DCF, the access point device and the station device perform carrier sense (CS) to check the usage status of the wireless channel around the device before communication. For example, if an access point device or a station device that is about 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 access point device or the station 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, 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. In this way, CS performed by each device based on the power level of the signal actually received is referred to as physical carrier sense (physical CS). The CCA level is also referred to as the carrier sense level (CS level) or the CCA threshold (CCAT). When the access point device and station device detect a signal with a reception power equal to or higher than the CCA level, they begin to demodulate at least the PHY layer signal.

[0033] An access point device performs carrier sensing during an interframe space (IFS) period set according to the type of frame to be transmitted, and determines whether the wireless channel is busy or idle. The period during which the access point device performs carrier sensing varies depending on the frame type and subframe type of the frame to be transmitted. The IEEE 802.11 system defines multiple IFS periods with different periods, 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, the access point device uses the DIFS.

[0034] After waiting for the DIFS period, the access point 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 frames correctly. Therefore, frame collisions are avoided by each transmitting station waiting for a randomly set time before starting transmission. When the access point 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 can it acquire the right to transmit and transmit a frame to the station device. If the access point device determines that the wireless channel is busy through carrier sense during the backoff counter countdown, it stops counting down the backoff counter. Then, when the wireless channel becomes idle again, the access point device waits for the same period as the previous IFS, and then resumes counting down the remaining part of the previous backoff counter.

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

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

[0037] When a station device determines that a received frame is not addressed to the station device, the station device sets a network allocation vector (NAV) based on the length of the frame included in the PHY header or the like. The station device does not attempt transmission during the period set in the NAV. In other words, the station device performs the same operation as when it determines that the wireless channel is busy by physical CS during the period set in the NAV. Therefore, communication control using NAV is also called virtual carrier sense (virtual CS). In addition to being set based on information included in the PHY header, the NAV is also set by RTS frames and CTS frames introduced to solve the hidden terminal problem.

[0038] Next, an example of the operation when an access point device transmits a signal to a station 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 (PC) controls the transmission right of each device within the BSS. Generally, an access point device becomes the PC and acquires the transmission right of the station device within the BSS.

[0039] The communication period by PCF includes a contention-free period (CFP) and a contention period (CP). During the CP, communication is performed based on the DCF described above, and the PC controls the transmission right during the CFP. The access point device, which is the PC, broadcasts a beacon frame including information such as the CFP duration (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 waiting for the CW. A station device that receives the beacon frame sets the CFP Max duration included in the beacon frame in its NAV. Thereafter, until the period set in the NAV elapses or a signal announcing the end of the CFP (e.g., a data frame including CF-end) is received within the BSS, the station device can acquire the transmission right only when it receives a signal signaling acquisition of the transmission right for the device from the PC (e.g., a data frame including CF-poll). During the CFP period, no packet collisions occur within the same BSS, so each station device does not take the random backoff time used in DCF.

[0040] The wireless communication device has either a function for transmitting a PPDU or a function for receiving a PPDU, or both. Fig. 2 is a diagram showing an example of the configuration of a PPDU transmitted by a wireless communication device. A PPDU conforming to the IEEE 802.11a / g standard is configured to include an L-STF, an L-LTF, an L-SIG, and a Data frame (MAC frame, payload, data section, data, information bits, etc.). A PPDU conforming to the IEEE 802.11n standard is configured to include an L-STF, an L-LTF, an L-SIG, an HT-SIG, an HT-STF, an HT-LTF, and a Data frame. A PPDU conforming to the IEEE 802.11ac standard is configured to include some or all of the following: L-STF, L-LTF, L-SIG, VHT-SIG-A, VHT-STF, VHT-LTF, VHT-SIG-B, and a Data frame. A PPDU conforming to the IEEE 802.11ax standard is configured to include some or all of the following: L-STF, L-LTF, L-SIG, RL-SIG, which is a time-repeated L-SIG, HE-SIG-A, HE-STF, HE-LTF, HE-SIG-B, and a Data frame. The PPDU being considered for the IEEE 802.11be standardization is a structure that includes some or all of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, HET-LTF, and Data frames.

[0041] The L-STF, L-LTF, and L-SIG enclosed by dotted lines in Figure 2 are structures commonly used in the IEEE 802.11 standard (hereinafter, L-STF, L-LTF, and L-SIG are also collectively referred to as the L-header). For example, a wireless communication device compatible with the IEEE 802.11a / g standard can properly receive an L-header in a PPDU compatible with the IEEE 802.11n / ac / ax / be standard. A wireless communication device compatible with the IEEE 802.11a / g standard can receive a PPDU compatible with the IEEE 802.11n / ac / ax / be standard as a PPDU compatible with the IEEE 802.11a / g standard.

[0042] However, wireless communication devices that comply with the IEEE 802.11a / g standards cannot demodulate PPDUs that comply with the IEEE 802.11n / ac / ax / be standards that follow the L-header, and therefore cannot demodulate information related to the transmitter address (TA), receiver address (RA), duration / ID field, etc.

[0043] IEEE 802.11 specifies a method of inserting Duration information into L-SIG as a method for a wireless communication device conforming to the IEEE 802.11a / g standard to appropriately set NAV (or perform reception operation for a predetermined period of time). Information on the transmission rate in the L-SIG (RATE field, L-RATE field, L-RATE, L_DATARATE, L_DATARATE field) and information on the transmission period (LENGTH field, L-LENGTH field, L-LENGTH) are used by a wireless communication device conforming to the IEEE 802.11a / g standard to appropriately set NAV.

[0044] The wireless communication device can transmit the L-SIG multiple times (L-SIG Repetition). In this case, the receiving wireless communication device can improve the demodulation accuracy of the L-SIG by receiving the L-SIG transmitted multiple times using maximal ratio combining (MRC), for example. Furthermore, when the wireless communication device has correctly received the L-SIG using MRC, it can interpret the PPDU including the L-SIG as a PPDU that complies with the IEEE 802.11ax or IEEE 802.11be standard.

[0045] Even during a PPDU reception operation, the wireless communication device can perform a reception operation of a part of a PPDU other than the PPDU (for example, a preamble, L-STF, L-LTF, PHY header, etc., as defined by IEEE 802.11) (also referred to as a dual reception operation). When the wireless communication device detects a part of a PPDU other than the PPDU during a PPDU reception operation, the wireless communication device can update some or all of the information related to the destination address, source address, PPDU, or Data period.

[0046] Ack and BA can also be called responses (response frames). Also, probe responses, authentication responses, and connection responses can also be called responses.

[0047] Fig. 3 is a diagram showing an example of a sounding procedure for the purpose of channel estimation of a wireless communication path in IEEE 802.11ax. In the example shown in Fig. 3, an access point device (AP) first transmits a Null Data PPDU (NDP) Announcement frame 3001 that specifies information indicating a station device (STA) that will be the target of the upcoming sounding (the receiver of the sounding frame) and the type of feedback information. The access point device then transmits an NDP frame 3002 including a training field for channel estimation SIFS after the NDP Announcement frame. The station device performs channel estimation based on the received NDP frame 3002, and transmits a frame, such as a Compressed Beamforming / CQI frame 3003, that feeds back the channel estimation result to the access point device SIFS after the NDP frame 3002. [1. First Embodiment]

[0048] FIG. 4 is a diagram showing an example of a wireless communication system according to this embodiment. Wireless communication system 4003-1 includes wireless communication device 4001-1 and wireless communication devices 4002-1 to 4002-3. Wireless communication device 4001-1 is also referred to as access point device 4001-1, and wireless communication devices 4002-1 to 4002-3 are also referred to as station devices 4002-1 to 3. Wireless communication devices 4002-1 to 4002-3 (station devices 4002-1 to 4002-3) are also referred to as wireless communication device 4002A (station device 4002A) as devices connected to wireless communication device 4001-1. Wireless communication device 4001-1 and wireless communication device 4002A are wirelessly connected and are capable of transmitting and receiving PPDUs to and from each other. The wireless communication system according to this embodiment may also include wireless communication system 4003-2 in addition to wireless communication system 4003-1. Wireless communication system 4003-2 includes wireless communication device 4001-2 and wireless communication devices 4002-4 to 4002-6. Wireless communication device 4001-2 is also referred to as access point device 4001-2, and wireless communication devices 4002-4 to 4002-6 are also referred to as station devices 4002-4 to 4002-6. Wireless communication devices 4002-4 to 4002-6 (station devices 4002-4 to 4002-6) are also referred to as wireless communication device 4002B (station device 4002B) as devices connected to wireless communication device 4001-2. Furthermore, when wireless communication device 4001-1 and wireless communication device 4001-2 (access point devices 4001-1, 4001-6) are described without specifying each other, they are also referred to as wireless communication device 4001 (access point device 4001), and when wireless communication devices 4002-1 to 4002-6 (station devices 4002-1 to 4002-6) are described without specifying each other, they are also referred to as wireless communication device 4002 (station device 4002). Wireless communication system 4003-1 and wireless communication system 4003-2 form different BSSs, but this does not necessarily mean that the ESSs (Extended Service Sets) representing service sets forming LANs (Local Area Networks) are different.In other words, wireless communication devices belonging to the same ESS can be regarded as belonging to the same network from a higher layer. Furthermore, BSSs are connected via a DS (Distribution System) to form an ESS. Note that each of the wireless communication systems 4003-1 and 4003-2 can also include multiple wireless communication devices.

[0049] 5 is a diagram showing an example of the configuration of station device 4002. Station device 4002 includes a wireless control unit (wireless control step) 5001, a timer unit (timer step) 5002, a wireless communication unit (wireless communication step) 5003, and an antenna unit 5004. Furthermore, wireless communication unit 5003 includes a physical layer frame generation unit (physical layer frame generation step) 5003a, a wireless transmission unit (wireless transmission step) 5003b, a wireless reception unit (wireless reception step) 5003c, a received power measurement unit (received power measurement step) 5003d, a channel estimation unit (channel estimation step) 5003e, and a signal demodulation unit (signal demodulation step) 5003f.

[0050] The wireless control unit 5001 performs information processing on layers higher than the physical layer, such as the MAC layer and LLC layer, for information handled within the wireless communication device itself (such as information related to frames to be transmitted and MIB (Management Information Base)) and frames received from other wireless communication devices, and also controls the wireless communication unit 5003.

[0051] The timer unit 5002 includes one or more timers and manages the timers related to the sounding process. Details of the timer unit 5002 will be described later. Note that, in the example of Fig. 5, the timer unit 5002 is described as being included in the wireless control unit 5001, but is not limited to this configuration. The timer unit 5002 may be provided outside the wireless control unit 5001 and configured to operate under control from the wireless control unit 5001.

[0052] The physical layer frame generation unit 5003a has a function of generating a physical layer frame (PPDU). The physical layer frame generation unit 5003a performs error correction coding, modulation, beamforming processing (precoding processing), etc. on the MAC layer frame sent from the wireless control unit 5001. The beamforming processing may be realized by multiplying the modulated signal by a beamforming matrix (beamforming filter) notified by the wireless control unit 5001. The physical layer frame generation unit 5003a outputs the generated physical layer frame to the wireless transmission unit 5003b.

[0053] The wireless transmitting unit 5003b converts the physical layer frame input from the physical frame generating unit 5003a into a signal in the radio frequency (RF) band and generates a wireless signal. The processing performed by the wireless transmitting unit 5003b includes digital-to-analog conversion, filtering, frequency conversion from baseband frequency to wireless frequency, etc. The wireless transmitting unit 5003b transmits the generated wireless signal via the antenna unit 5004.

[0054] The wireless receiving unit 5003c has a function of converting a wireless signal received via the antenna unit 5004 into a baseband signal and generating a physical layer signal (for example, a physical layer frame). The processing performed by the wireless receiving unit 5003c includes frequency conversion processing from a wireless frequency to a baseband frequency, filtering, analog-to-digital conversion, etc. The physical layer signal, which is the received signal converted into a digital signal by the wireless receiving unit 5003c, is input to a received power measuring unit 5003d, a channel estimating unit 5003e, and a signal demodulating unit 5003f.

[0055] The received power measurement unit 5003d measures the received power of the received signal input from the wireless receiving unit 5003c. The received power measurement unit 5003d can measure the received power of the radio wave received on the frequency channel to be measured, the received power of the LTF of the received physical layer frame, etc. The received power measurement unit 5003d can notify the wireless control unit 5001 of the measurement result of the received power.

[0056] The channel estimation unit 5003e estimates the channel state through which the physical layer frame has propagated, based on the received signal of the LTF (L-LTF, HT-LTF, VHT-LTF, HE-LTF, etc.) included in the physical layer frame received by the wireless receiving unit 5003c. The channel estimation unit 5003e can notify the signal demodulation unit 5003f and the wireless control unit 5001 of the channel estimation result.

[0057] The signal demodulation unit 5003f performs channel equalization, demodulation, error correction decoding, etc. on the physical layer frame received by the wireless receiving unit 5003c, and acquires information such as the PHY header and MAC layer frame. The channel equalization process can use the channel estimation results of the channel estimator 5003e, etc. The signal demodulation unit 5003f outputs the acquired PHY header and MAC layer frame to the wireless control unit 5001.

[0058] The wireless control unit 5001 can perform physical carrier sensing and virtual carrier sensing based on the received power measurement results in the received power measuring unit 5003 d and information acquired in the signal demodulation unit 5003 f, and can determine the state of the wireless channel (including determining whether it is in an idle state or a busy state). The wireless control unit 5001 can notify the wireless communication unit 5003 of this wireless channel state determination information.

[0059] When there is control information, data, etc. to be transmitted, the wireless control unit 5001 can start a backoff procedure using the wireless channel state determination information. The wireless control unit 5001 generates a backoff counter based on the CW and has a countdown function for the backoff counter. For example, the wireless control unit 5001 can count down the backoff counter when the wireless channel state determination information indicates an idle state, and can stop the countdown of the backoff counter when the wireless channel state determination information indicates a busy state. Furthermore, the wireless control unit 5001 makes a transmission decision using either the wireless channel state determination information or the backoff counter value, or both. For example, the wireless control unit 5001 can notify the wireless communication unit 5003 of transmission decision information when the wireless channel state determination information indicates an idle state and the backoff counter value is 0. Furthermore, the wireless control unit 5001 can notify the wireless communication unit 5003 of transmission decision information when the wireless resource state determination information indicates an idle state.

[0060] FIG. 6 shows an example of the configuration of an access point device 4001. The access point device 4001 includes a wireless control unit (wireless control step) 6001, a wireless communication unit (wireless communication step) 5003, and an antenna unit 5004. Furthermore, the wireless communication unit 5003 includes a physical layer frame generation unit (physical layer frame generation step) 5003a, a wireless transmission unit (wireless transmission step) 5003b, a wireless reception unit (wireless reception step) 5003c, a received power measurement unit (received power measurement step) 5003d, a channel estimation unit (channel estimation step) 5003e, and a signal demodulation unit (signal demodulation step) 5003f. The access point device 4001 of FIG. 6 is basically configured similarly to the station device 4002 of FIG. 5. Therefore, the following description will focus on the differences between the two, and will omit a description of similar parts. Furthermore, parts corresponding to those in the station device of FIG. 5 will be described using the same reference numerals.

[0061] The wireless control unit 6001 processes information handled within the wireless communication device (such as information related to frames to be transmitted and MIB (Management Information Base)) and frames received from other wireless communication devices at layers higher than the physical layer, such as the MAC layer and LLC layer, and also controls the wireless communication unit 5003.

[0062] The physical layer frame generation unit 5003a has a function of generating a physical layer frame (PPDU). The physical layer frame generation unit 5003a performs error correction coding, modulation, beamforming processing (precoding processing), etc. on the MAC layer frame sent from the wireless control unit 6001. The beamforming processing may be realized by multiplying the modulated signal by a beamforming matrix (beamforming filter) notified by the wireless control unit 6001. The physical layer frame generation unit 5003a outputs the generated physical layer frame to the wireless transmission unit 5003b.

[0063] The received power measurement unit 5003d measures the received power of the received signal input from the wireless receiving unit 5003c. The received power measurement unit 5003d can measure the received power of the radio wave received on the frequency channel to be measured, the received power of the LTF (L-LTF, HT-LTF, VHT-LTF, HE-LTF, etc.) of the received physical layer frame, etc. The received power measurement unit 5003d can notify the wireless control unit 6001 of the measurement result of the received power.

[0064] The channel estimation unit 5003e estimates the channel state through which the physical layer frame has propagated, based on the LTF received signal included in the physical layer frame received by the wireless receiving unit 5003c. The channel estimation unit 5003e can notify the signal demodulation unit 5003f and the wireless control unit 6001 of the channel estimation result.

[0065] The signal demodulation unit 5003f performs channel equalization, demodulation, error correction decoding, etc. on the physical layer frame received by the wireless receiving unit 5003c, and acquires information such as the PHY header and MAC layer frame. The channel equalization process can use the channel estimation results of the channel estimator 5003e, etc. The signal demodulation unit 5003f outputs the acquired PHY header and MAC layer frame to the wireless control unit 6001.

[0066] When there is control information, data, a beacon, or the like to be transmitted, the wireless control unit 6001 can start a backoff procedure using the wireless channel state determination information. The wireless control unit 6001 generates a backoff counter based on the CW and has a countdown function for the backoff counter. For example, the wireless control unit 6001 can count down the backoff counter when the wireless channel state determination information indicates an idle state, and can stop the backoff counter countdown when the wireless channel state determination information indicates a busy state. Furthermore, the wireless control unit 6001 makes a transmission decision using either the wireless channel state determination information or the backoff counter value, or both. For example, the wireless control unit 6001 can notify the wireless communication unit 5003 of transmission decision information when the wireless channel state determination information indicates an idle state and the backoff counter value is 0. Furthermore, the wireless control unit 6001 can notify the wireless communication unit 5003 of transmission decision information when the wireless resource state determination information indicates an idle state.

[0067] Next, an example will be described in which the access point device 4001 and the station device 4002 support multi-link operation (MLO), in which communication is performed simultaneously using two wireless links: a first wireless link and a second wireless link that uses a frequency band (or frequency channel) different from that of the first wireless link. Note that MLO is not limited to two wireless links, and multiple wireless links in different frequency bands (or frequency channels) can be used.

[0068] A multi-link device (MLD) is a device capable of multi-link communication through multi-link operation, and an access point device that supports MLO will be referred to as an MLD access point device, and a station device that supports MLO will be referred to as an MLD station device. Furthermore, MLD access point devices and MLD station devices will also be collectively referred to as MLD wireless communication devices. In this embodiment, the wireless communication devices 4001-1, 4001-2, 4002A, and 4002B described above will be described as MLD wireless communication devices, but in actual operation, not all wireless communication devices in a wireless communication system will necessarily support MLO.

[0069] The MLD access point device 10001 and the MLD station device 10002 will be described using FIG. 7 . The MLD wireless communication device is composed of multiple sub-wireless communication devices corresponding to the frequency bands (or frequency channels) of each wireless link (also referred to as a physical layer link) that constitutes the multilink. Each sub-wireless communication device may support all frequency bands (and frequency channels) supported by the MLD wireless communication device, or each may support only one of the frequency bands (or frequency channels). FIG. 8 shows an example in which the MLD access point device 10001 is composed of two sub-wireless communication devices, in this case, two sub-access point devices 10001-1 and 10001-2, and a multilink control unit 10011, but the number of sub-access point devices may be any number greater than or equal to two. Note that, hereinafter, when any one of the multiple sub-access point devices is described as a representative, it will be referred to as the sub-access point device 10001-N. 8 similarly shows an example in which the MLD station device 10002 is configured with two sub-wireless communication devices, in this case two substation devices 10002-1 and 10002-2, and a multi-link control unit 10012, but the number of substation devices may be any number greater than or equal to two. Note that, hereinafter, when any one of the multiple substation devices is described as a representative, it will be referred to as substation device 10002-N. Furthermore, the sub-wireless communication devices (sub-access point devices and substation devices) may be configured with some circuits within the wireless communication device, and may be referred to as sub-wireless communication units (sub-access point units, substation units).

[0070] 8 shows an example in which multiple sub-wireless communication devices are configured as logically separate blocks, but they may be physically configured as a single wireless communication device. Alternatively, multiple sub-wireless communication devices may be configured as physically separate devices. In this embodiment, a case in which each sub-wireless communication device is configured as a physically separate device will be described as an example.

[0071] The number of sub-access point devices included in one MLD access point device and the number of substation devices included in one MLD station device may vary depending on the grade, class, capabilities, etc. of each MLD wireless communication device. The higher the grade, class, and capabilities of an MLD wireless communication device, the greater the number of sub-wireless communication devices (sub-access point devices, substation devices) it may have. In other words, for each MLD wireless communication device present in a wireless communication system, the sub-wireless communication devices (sub-access point devices, substation devices) that make up each MLD wireless communication device may differ depending on the grade, class, capabilities, etc., and the numbers of these devices do not have to be the same.

[0072] The substation apparatus 10002-1 associates with the sub-access point apparatus 10001-1 and establishes a wireless link 10003-1 (first wireless link), and the substation apparatus 10002-2 associates with the sub-access point apparatus 10001-2 and establishes a wireless link 10003-2 (second wireless link).

[0073] The configuration of the sub-access point devices 10001-N in Fig. 7 is the same as the configuration of the access point device 4001 in Fig. 6, except that a multi-link control unit 10011 is connected to the wireless control unit 6001 of each sub-access point device 10001-N. The multi-link control unit 10011 controls the wireless links for each sub-access point device 10001-N and exchanges control information and transmitted / received data with each sub-access point device 10001-N. The multi-link control unit 10011 distributes transmitted data frames to the sub-access point devices 10001-1 and 10001-2, i.e., the wireless links 10003-1 and 10003-2, and aggregates received data frames from the sub-access point devices 10001-1 and 10001-2, i.e., the wireless links 10003-1 and 10003-2.

[0074] 7 is the same as the configuration of the station device 4002 in FIG. 5, except that a multilink control unit 10012 is connected to the wireless control unit 5001 of each substation device 10002-N. The multilink control unit 10012 controls the wireless links for each substation device 10002-N and exchanges control information and transmitted / received data with each substation device 10002-N. The multilink control unit 10012 distributes transmitted data frames to each of the substation devices 10002-1 and 10002-2, i.e., to each of the wireless links 10003-1 and 10003-2, and aggregates received data frames from each of the substation devices 10002-1 and 10002-2, i.e., to each of the wireless links 10003-1 and 10003-2.

[0075] In the following description, for the sake of simplicity, an example will be described in which the wireless links constituting the multilink are two, wireless link 10003-1 (first wireless link) and wireless link 10003-2 (second wireless link), but this is not limiting and the present invention is similarly applicable to a case in which the number of wireless links is three or more. Furthermore, an example will be described in which the frequency band of the first wireless link is 2.4 GHz and the frequency band of the second wireless link is 5 GHz, but the frequency band used by each wireless link can be set arbitrarily from frequency bands (or frequency channels) supported by the wireless communication system, such as the 2.4 GHz band, 5 GHz band, 6 GHz band, and 60 GHz band, and these frequency bands may change according to the laws and regulations of each country.

[0076] 8 is a schematic diagram showing how a wireless medium is secured according to one aspect of this embodiment. Prior to securing the wireless medium, the access point device (or sub-access point device) performs channel sensing including a backoff operation 801. If, for example, the interference power falls below a predetermined value for a predetermined period of time, the access point device can secure the wireless medium 802. Here, the time period and frequency bandwidth of the wireless medium 802 are not limited to predetermined values.

[0077] The access point device can configure a PE (Pre-emption) resource 803 in a portion of the reserved wireless medium 802, allowing communication of low-latency traffic. Here, the time period and frequency bandwidth of the PE resource 803 are not limited to predetermined values. Furthermore, its location must be within the range of the wireless medium 802. The access point device can transmit low-latency (LL) traffic through the PE resource 803. While the LL traffic is not limited to any particular type, it can be, for example, traffic that can be transmitted using a PPDU with a short frame length (e.g., 1 ms or less) compared to normal traffic, traffic that can be transmitted using a PPDU with a small occupied bandwidth (e.g., 1 MHz or less), or traffic that can be transmitted using a PPDU with a small configurable maximum transmit power (e.g., 10 dBm or less, the maximum transmit power of normal traffic). Hereinafter, a PPDU that transmits LL traffic (in other words, a PPDU for which frame exchange is performed in the PE resource 803) is also referred to as an LL PPDU.

[0078] The access point device can aggregate and transmit LL PPDUs and normal PPDUs to be transmitted using the PE resources 803. For example, the access point device can time-multiplex and transmit the LL PPDUs and normal PPDUs. For example, the access point device can frequency-multiplex and transmit the LL PPDUs and normal PPDUs. In this case, the normal PPDUs can be transmitted using the PE resources 803 on the assumption that they are aggregated with the LL PPDUs.

[0079] The access point device can permit a station device under its control to transmit an LL PPDU in the PE resource 803. In this case, the station device does not necessarily have to perform all channel access operations. For example, the station device can transmit the LL PPDU after waiting for a predetermined period (e.g., a PIFS period) without performing random backoff. The access point device can also transmit a trigger frame for causing the LL PPDU to be transmitted in the PE resource 803. The trigger frame can include information indicating that the frame triggered by the trigger frame is an LL traffic frame. The access point device can also transmit the trigger frame as an LL PPDU.

[0080] The access point device needs to notify station devices under its control and surrounding BSSs that the wireless medium 802 includes PE resources 803. Therefore, after securing the wireless medium 802, the access point device (or sub-access point device) according to this embodiment can transmit a Low Latency Announcement (LLA) frame 804 indicating that the wireless medium 802 includes PE resources 803.

[0081] The LLA frame includes a predetermined field in the PHY header or MAC header, and the predetermined field contains information identifying the LLA frame. The structure of the LLA frame is not limited, but it is preferable that its occupied bandwidth be the same as that of the wireless medium 802 or the PE resource 803. The LLA frame may also be a frame that does not include a DATA field. The LLA frame may also be configured as a frame whose time length is the same as that of the wireless medium 802, with the DATA field portion containing only a partial signal (e.g., a pilot tone). The LLA frame includes a PHY header and a MAC header that contain fields containing information (e.g., frame length and occupied bandwidth) that would normally be contained in the PHY header or MAC header of a PPDU, in addition to the fields containing the information associated with the PE resource 803 described above. This means that a wireless communication device that cannot interpret an LLA frame will interpret the LLA frame as the same frame as another PPDU.

[0082] 9 is a schematic diagram illustrating the frame transmission of an access point device that has reserved a wireless medium 802 including PE resources 803. In other words, when the access point device of this embodiment reserves the wireless medium 802, it transmits an LLA frame 904. The LLA frame 904 includes a PHY header with the same occupied bandwidth as the wireless medium 802, and the PHY header includes information indicating to station devices under its control and surrounding BSSs that the wireless medium 802 has PE resources 803. The LLA frame includes a DATA field, but the DATA field contains only pilot tones. In other words, the access point device continues transmitting LLA frames until the completion time of the wireless medium 802. If an LL PPDU 905 or a normal PPDU 906 occurs while the access point device is transmitting LLA frames, it can stop transmitting the LLA frames on the wireless medium occupied by the LL PPDU 905 and PPDU 906 and transmit the LL PPDU 905 and PPDU 905.

[0083] If the wireless communication device that receives the LLA frame is a wireless communication device that cannot recognize the LLA frame, the PHY header of the LLA frame contains the frame length (i.e., the occupied time of the wireless medium 802) and occupied bandwidth (i.e., the occupied bandwidth of the wireless medium 802) of the LLA frame, so the NAV is set for that period only and the frame transmission operation is not initiated.

[0084] Among wireless communication devices that can recognize an LLA frame, wireless communication devices that belong to a BSS different from the BSS to which the wireless communication device that transmitted the LLA frame belongs will recognize the LLA frame as an Inter-BSS PPDU. Therefore, for example, assuming that a lower transmission power is used than when transmitting a normal PPDU, it is possible to enter spatial reuse (SR) operation, which allows transmission operation, even while receiving the LLA frame of the Inter-BSS or an Inter-BSS PPDU frame triggered by the LLA frame. However, it is preferable not to enter SR operation in the PE resource 803 indicated by the LLA frame. Alternatively, it is possible to enter transmission operation in the PE resource 803 by using a lower transmission power in the PE resource 803 indicated by the LLA frame than in normal SR operation for transmission over the wireless medium 802. Therefore, a separate formula for calculating the transmission power used when spatially reusing an LLA frame may be provided.

[0085] The conditions for the wireless communication device according to this embodiment to enter spatial reuse operation include the transmit power value set for the frame to be transmitted, as described above. When the wireless communication device according to this embodiment enters spatial reuse operation and receives an inter-BSS PPDU, if the received power PD is equal to or less than a predetermined value, the frame can be transmitted. Here, the predetermined value is a value between the minimum receiver sensitivity PDmin and the maximum receiver sensitivity PDmax in a predetermined spatial reuse operation. Here, the wireless communication device according to this embodiment can change the values ​​of the minimum receiver sensitivity PDmin and the maximum receiver sensitivity PDmax when receiving the LLA frame. For example, the wireless communication device according to this embodiment can add a predetermined value to the minimum receiver sensitivity PDmin and the maximum receiver sensitivity PDmax. The predetermined value can be notified to wireless communication devices within the BSS by an access point device that manages the BSS to which the wireless communication device belongs. Note that the predetermined value may be a negative value.

[0086] Furthermore, if the transmission power set for a frame to be transmitted is P0 and the maximum configurable transmission power (or a predetermined fixed reference power) is Pref, and PD is smaller than the value obtained by subtracting P0 from Pref and adding the value obtained by adding PDmin, the wireless communication device can transmit a frame with P0 set as the transmission power. Here, the wireless communication device according to this embodiment can set the value to be added to PDmin to the value obtained by subtracting P0 from Pref and then further subtracting a predetermined value. Note that the predetermined value here may be a negative value.

[0087] Among wireless communication devices capable of recognizing an LLA frame, wireless communication devices (mainly station devices) belonging to the BSS to which the wireless communication device that transmitted the LLA frame belongs set an Intra NAV when receiving an Intra-BSS PPDU. A station device with an Intra NAV set can transmit frames triggered by a trigger frame transmitted from an access point device even during the Intra NAV setting period, and therefore continues receiving operations even while the Intra NAV is set. On the other hand, a station device according to this embodiment can transmit an LL PPDU in PE resource 803 without waiting for a trigger frame transmitted from the access point device, even when an Intra NAV is set. In this case, the station device does not necessarily need to perform carrier sensing when transmitting an LL PPDU (if the access point device controls whether or not to perform carrier sensing, the station device follows the control of the access point device).

[0088] When a station device for which Intra NAV is set transmits an LL PPDU using PE resources 803, the location of the LL PPDU relative to the PE resources 803 is not limited. For example, the access point device may include resource allocation information for the PE resources 803 in the LLA frame. For example, the access point device may divide the PE resources 803 into multiple resource units (RUs) and include information indicating the division status in the LLA frame. A station device for which Intra NAV is set may randomly select one (or multiple) RUs from the multiple RUs set in the PE resources 803 to transmit an LL PPDU.

[0089] Furthermore, a station device with an Intra NAV configured can transmit an LL trigger frame to another station device with an Intra NAV configured to trigger the transmission of the LL PPDU before transmitting the LL PPDU. The LL trigger frame includes information about the PHY header to be configured in the LL PPDU and information about the RU in which the station device transmitting the LL trigger frame places the LL PPDU. If the station device with an Intra NAV configured to receive the LL trigger frame is able to transmit the LL PPDU, the station device randomly selects an RU from among the multiple RUs configured in the PE resource 803, other than the RU in which the station device transmitting the LL trigger frame places the LL PPDU. The station device transmits the LL PPDU after waiting a predetermined period (e.g., SIFS) after receiving the LL trigger frame.

[0090] In the above description, it has been assumed that a wireless communication device that receives an LLA frame transmitted from a BSS to which the device belongs sets an Intra NAV, but a wireless communication device according to this embodiment can also set a NAV (for example, an LL NAV) different from the Intra NAV when it receives an LLA frame transmitted from a BSS to which the device belongs. A wireless communication device that has set an LL NAV can transmit an LL PPDU using the method described above, but it is not assumed that frame transmission will be triggered by a trigger frame other than the trigger frame that triggers an LL PPDU. In other words, when a wireless communication device that has set an LL NAV receives a trigger frame that triggers an LL PPDU and the Duration information (information associated with the length of the TXOP secured by the trigger frame) contained in the trigger frame indicates a value greater than the set LL NAV, the wireless communication device must update the LL NAV. However, if the above condition is not met, for example, if a trigger frame that does not trigger an LL PPDU is received, the wireless communication according to this embodiment ignores the trigger frame and does not update the LL NAV.

[0091] The access point device can also transmit an LLA frame from a sub-access point device. For example, the MLD access point device 10001 according to this embodiment sets a frequency that is common to at least a portion of the bandwidth for the link set between the sub-access point device 10001-1 and the sub-access point device 10001-2. Then, when the MLD access point device 10001 secures the wireless medium 802, the sub-access point device 10001-2 transmits an LLA frame, and the sub-access point device 10001-1 begins transmitting LL PPDUs and normal PPDUs, or receiving LL PPDUs that may be transmitted from a station device in the PE resource 803. Controlled in this manner, the MLD access point device 10001 according to this embodiment can simultaneously secure the PE resource 803 by transmitting an LLA frame and handle frame exchange in the PE resource 803.

[0092] When the MLD access point device 10001 according to this embodiment exchanges frames in the PE resource 803 with the sub-access point device 10001-1 and the sub-access point device 10001-2 transmits an LLA frame, the sub-access point device 10001-1 and the sub-access point device 10001-2 need to support simultaneous transmission and reception (STR), which performs frame transmission and frame reception at the same time. However, to support STR, the access point device needs to be equipped with an antenna and filter that suppresses self-interference, which is difficult for all MLD access point devices to support.

[0093] Therefore, an access point device according to this embodiment (a first access point device) can transmit an LLA frame in cooperation with another access point device (a second access point device). Fig. 10 is a schematic diagram showing an example of a communication system according to this embodiment. In Fig. 10, an access point device 1001 and an access point device 1002 are capable of exchanging information with each other. In other words, the access point device 1001 and the access point device 1002 are capable of exchanging frames or are connected by another network (for example, a wired LAN).

[0094] In this embodiment, when the access point device 1001 secures the wireless medium 802, the access point device 1002 transmits an LLA frame. For example, the access point device 1001 can transmit a trigger frame that triggers the access point device 1002 to transmit an LLA frame. Because the trigger frame contains information to be written in the LLA frame, the access point device 1002 can transmit an LLA frame after receiving the trigger frame.

[0095] Furthermore, the access point device 1001 according to this embodiment can transmit only a portion of the LLA frame after securing the wireless medium 802. For example, the access point device 1001 transmits the PHY header of the LLA frame but does not transmit the DATA field. When the access point device 1002 receives an LLA frame containing only the PHY header, it can construct the DATA field of the LLA frame from the information in the PHY header and transmit it.

[0096] Furthermore, the access point device 1001 according to this embodiment can cause the access point device 1002 to transmit an LLA frame via another network. After securing the wireless medium 802, the access point device 1001 notifies the access point device 1002 of information about the LLA frame via the other network. The access point device 1002 can construct and transmit an LLA frame based on the notified information.

[0097] In this embodiment, when the access point device 1001 and the access point device 1002 manage different BSSs, when the access point device 1002 transmits an LLA frame, it can transmit information indicating the BSS to which the wireless communication device that transmitted the LLA frame belongs (e.g., BSS Color), along with information indicating the BSS to which the access point device 1001 belongs.

[0098] Furthermore, when the wireless communication device according to this embodiment sets the LL NAV, the access point device 1002 may, as described above, write information indicating the BSS to which the access point device 1001 belongs, or information indicating the BSS to which the access point device 1002 belongs, in the BSS Color of the LLA frame.

[0099] The access point device 1002 that transmits the LLA frame can be defined as a separate wireless communication device. That is, the access point device 1002 can be defined as a wireless communication device that transmits at least an LLA frame only under the control of the access point device 1001. In this case, the access point device 1002 does not need to perform operations performed by the access point device 1001, such as transmitting beacon frames or responding to probe request frames. However, the access point device 1002 can perform operations performed by the access point device 1001 on behalf of the access point device 1001 in accordance with instructions from the access point device 1001. Note that, since the access point device 1002 is assumed to operate in accordance with instructions from the access point device 1001, it does not necessarily need to perform, for example, carrier sensing operations performed when entering a frame transmission operation. This means that the access point device 1002 can also be configured without a receiver. Alternatively, the access point device 1002 can be equipped with a receiver that only has the function of receiving frames transmitted from the access point device 1001. In other words, the access point device 1002 does not need to have capabilities equivalent to those of the access point device 1001 (for example, the number of frequency bands that can be supported simultaneously, the number of sub-access point devices that can be managed, the number of recognizable antennas, MCS, etc.), but only needs to have the function of receiving frames that the access point device 1001 wishes to transmit to the access point device 1002 and interpreting the contents of those frames. The access point device 1002 can also be defined as a sub-access point device included in the access point device 1001. However, the access point device 1002 will have fewer capabilities than the other sub-access point devices included in the access point device 1001. The access point device 1002 can also be defined as a wireless communication device under the management of the other sub-access point devices included in the access point device 1001.

[0100] According to the method described above, the wireless communication device according to this embodiment can exchange LL PPDUs with low delay and without increasing interference power, even in an environment where LL PPDUs and normal PPDUs coexist, thereby contributing to improving frequency utilization efficiency. [2. Common to all embodiments]

[0101] A communication device according to an embodiment of the present invention can communicate in a frequency band (frequency spectrum) that does not require permission to use from a country or region, which is called an unlicensed band, but the usable frequency band is not limited to this. The communication device according to an embodiment of the present invention can also be effective in a frequency band called a white band (e.g., a frequency band allocated for television broadcasting but unused in some regions) that is not actually used despite permission to use it for a specific service from a country or region for the purpose of preventing interference between frequencies, or in a shared spectrum (shared frequency band) that is expected to be shared by multiple operators.

[0102] A program running on a wireless communication device according to one aspect of the present invention is a program that controls a CPU and other components (a program that causes a computer to function) to implement the functions of the above-described embodiment according to one aspect of the present invention. Information handled by these devices is temporarily stored in RAM during processing, and then stored in various ROMs or HDDs, where it is read, modified, and written by the CPU as needed. Recording media for storing the program may include semiconductor media (e.g., ROM, non-volatile memory cards, etc.), optical recording media (e.g., DVDs, MOs, MDs, CDs, BDs, etc.), and magnetic recording media (e.g., magnetic tapes, flexible disks, etc.). Executing a loaded program not only implements the functions of the above-described embodiment, but may also implement the functions of the present invention by processing in cooperation with an operating system or other application programs based on instructions from the program.

[0103] 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 one aspect of the present invention. Furthermore, part or all of the communication device in the above-described embodiments may be realized as an LSI, which is typically an integrated circuit. Each functional block of the communication device may be individually formed into a chip, or part or all of the functional blocks may be integrated into a chip. When each functional block is formed into an integrated circuit, an integrated circuit control unit that controls them is added. Needless to say, downloading programs and setting information from a server computer to implement at least part of the functions of the above-described embodiments also falls within one aspect of the present invention.

[0104] Furthermore, the method of integration is not limited to LSI, but may be realized by a dedicated circuit or a general-purpose processor. 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.

[0105] It should be noted that the present invention is not limited to the above-described embodiments. The wireless communication device of the present invention is not limited to application to mobile station devices, but can of course be applied to stationary or non-mobile electronic devices installed indoors or outdoors, such as AV equipment, kitchen equipment, cleaning / washing appliances, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0106] 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.

[0107] One aspect of the present invention is suitable for use in a wireless communication device and a communication method.

[0108] 3001 NDP Announcement frame 3002 NDP frame 3003 Compressed Beamforming / CQI frame 4001-1, 4001-2 Wireless communication device (access point device) 4002-1 to 4002-6 Wireless communication device (station device) 4003-1, 4003-2 Wireless communication system 5001 Wireless control unit 5002 Timer unit 5003 Wireless communication unit 5003a Physical layer frame generation unit 5003b Wireless transmission unit 5003c Wireless reception unit 5003d Received power measurement unit 5003e Channel estimation unit 5003f Signal demodulation unit 5004 Antenna unit 6001 Wireless control unit 10001 MLD access point device 10001-1, 10001-2, 10001-N Sub-access point device 10002 MLD station equipment 10002-1, 10002-2, 10002-N Substation equipment 10011, 10012 Multi-link control unit

Claims

1. A station device that communicates with a first access point device and a second access point device, comprising: a receiver that receives an LLA (Low Latency Announcement) frame from the second access point device; and a transmitter that transmits an LL (Low Latency) PPDU (Physical Protocol Data Unit) to the first access point device based on the LLA frame, wherein the LLA frame includes information indicating a plurality of RUs (Resource Units) to be used for the LL PPDU, and the station device allocates the LL PPDU to at least one RU randomly selected from the plurality of RUs.

2. The station device according to claim 1, wherein if the LLA frame is an Inter Basic Service Set (BSS) PPDU, spatial reuse is performed without using multiple RUs used for the LL PPDU.

3. The station device according to claim 1, which transmits an LL trigger frame that triggers the LL PPDU to another station device.

4. The station device according to claim 3, wherein if the LLA frame is an Intra BSS PPDU, the station device sets an LL NAV (Network Allocation Vector) associated with the LL PPDU, and if the LL NAV is set, the station device receives a trigger frame that triggers the LL PPDU, and if the Duration information described in the trigger frame indicates a value greater than the LL NAV, the station device updates the LL NAV.

5. A first access point device that communicates with a station device, comprising: a receiving unit that determines whether a wireless medium is idle; a transmitting unit that generates frames; and a control unit that controls the wireless medium, wherein the transmitting unit has a function of transmitting low latency traffic, and when the receiving unit determines that the wireless medium is idle, the transmitting unit transmits a frame including information indicating a time interval associated with the low latency traffic.

6. The first access point device described in claim 5, wherein the control unit sets a PE (Pre-emption) resource in the wireless medium that allows transmission of an LL PPDU and divides the PE resource into multiple RUs; the transmission unit generates an LLA frame that includes information indicating the position of the PE resource and information indicating the multiple RUs; the LLA frame includes a DATA field, and a pilot tone is set in the DATA field; and the transmission unit transmits the LLA frame in the wireless medium.

7. The first access point device of claim 6, further communicating with a second access point device, notifying the second access point device of information associated with the LLA frame, and instructing the second access point device to transmit the LLA frame.

8. A communication method for a station device communicating with a first access point device and a second access point device, comprising: a step of receiving an LLA (Low Latency Announcement) frame from the second access point device; and a step of transmitting an LL (Low Latency) PPDU (Physical Protocol Data Unit) to the first access point device based on the LLA frame, wherein the LLA frame includes information indicating a plurality of RUs (Resource Units) to be used for the LL PPDU; and a step of allocating the LL PPDU to at least one RU randomly selected from the plurality of RUs.

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