Wireless communication apparatus and communication method

Abstract

To provide a radio communication device capable of dynamically changing an occupied bandwidth in an environment where interference power changes.SOLUTION: A wireless communication device in which a first link and a second link are set, the wireless communication device comprising: a transmission unit configured to transmit a first frame in the first link and transmit a second frame in the second link; and a reception unit configured to perform carrier sense in the first link and the second link, wherein at least some channel bands of the first link and the second link overlap each other, wherein the first frame includes a sub-channel having no signal in the channel band, the transmission unit transmits the second frame in the sub-channel having no signal in the second link, and an end of a frame transmission section secured by the second frame does not exceed an end of a frame transmission section secured by the first frame.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[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 (Local Area Network) communications and more efficient frequency utilization. Wireless LANs enable wireless communications 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 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 with densely packed wireless LAN devices.

[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. (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 connection (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. From the perspective 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 of the links constituting a multi-link. MLO allows wireless communication devices to simultaneously maintain multiple link connections using different wireless resources and communication-related settings. A wireless communication device can not only send and receive frames using multiple links simultaneously, but also switch the link connections for sending and receiving frames, i.e., change the frequency band, without performing a reconnection operation. 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] Furthermore, in a wireless LAN where channel access is generally based on CSMA / CA, even in an environment where a wide communication bandwidth is available, if interference power occurs in a portion of that bandwidth, the entire communication bandwidth cannot necessarily be used. Therefore, a technique called preamble puncturing, which transmits frames in which only the portion of the available communication bandwidth corresponding to the band where interference power is observed is deleted, has been discussed and specified (see Non-Patent Document 2). With preamble puncturing, frame exchange is performed by avoiding the band where interference power is observed, making it possible to use the available wireless medium with high efficiency. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] IEEE 802.11-19 / 0773-08-00be, Nov.2019 [Non-patent document 2] IEEE 802.11-16 / 1382r0, Nov. 2016 Summary of the Invention [Problem to be solved by the invention]

[0007] The preamble puncturing technique allows frame exchange to be performed by avoiding the band in which interference power is observed. This means that the wireless medium secured by the frame transmitted using the preamble puncturing technique is a wireless medium of a band other than the band in which interference power is observed. Therefore, even if the observed interference power disappears while transmitting a frame using the preamble puncturing technique, the wireless medium of the communication band in question is not secured, and therefore the communication band in question cannot be used. Therefore, the wireless communication device continues to transmit frames with an occupied bandwidth smaller than the available communication bandwidth, resulting in a problem of reduced frequency utilization efficiency. [Means for solving the problem]

[0008] The wireless communication device and 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 embodiment of the present invention is a wireless communication device in which a first link and a second link are set, and includes a transmitter that transmits a first frame on the first link and a second frame on the second link, and a receiver that performs carrier sensing on the first link and the second link, wherein at least a portion of the channel bands of the first link and the second link overlap, the first frame includes a subchannel within the channel band to which no signal is assigned, the transmitter transmits the second frame on the subchannel to which no signal is assigned in the second link, and the end of the frame transmission interval secured by the second frame does not exceed the end of the frame transmission interval secured by the first frame.

[0010] (2) Furthermore, a wireless communication device according to one aspect of the present invention is described in (1) above, and the end of the frame transmission interval reserved by the second frame and the end of the frame transmission interval reserved by the first frame are aligned.

[0011] (3) Furthermore, a wireless communication device according to one aspect of the present invention is described in (1) above, and the first frame includes control information indicating that the second frame can be set for a subchannel that does not have a signal.

[0012] (4) Furthermore, a wireless communication device according to one aspect of the present invention is described in (3) above, and the control information indicating that the second frame can be set includes information indicating the second link.

[0013] (5) Also, a communication method according to one aspect of the present invention is a communication method for a wireless communication device in which a first link and a second link are set, comprising the steps of transmitting a first frame on the first link and transmitting a second frame on the second link, and performing carrier sensing on the first link and the second link, wherein at least a portion of the channel bands of the first link and the second link overlap, and the first frame includes a subchannel with no signal within the channel band, and further comprising the step of transmitting the second frame on the subchannel with no signal in the second link, wherein the end of the frame transmission section secured by the second frame does not exceed the end of the frame transmission section secured by the first frame. [Effects of the Invention]

[0014] According to the wireless communication device and communication method of the present invention, when a communication band that has been avoided by preamble puncturing technology becomes available, frame exchange can be performed using that communication band, thereby contributing to improving frequency utilization efficiency. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating an example of a MAC layer frame configuration in a wireless LAN system. [Figure 2] FIG. 1 is a diagram illustrating an example of a PPDU configuration related to a wireless LAN system. [Figure 3] FIG. 1 is a diagram illustrating an example of a sounding procedure related to a wireless LAN system. [Figure 4] 1 is a diagram illustrating an example of a configuration of a communication system according to an aspect of the present invention. [Figure 5] 1 is a block diagram showing an example of the configuration of a station device according to an aspect of the present invention; [Figure 6] 1 is a block diagram illustrating an example of a configuration of an access point device according to an aspect of the present invention. [Figure 7] 1 is a diagram illustrating an example of a configuration of a communication system according to an aspect of the present invention. [Figure 8]FIG. 1 is a diagram illustrating an example of a signal configuration according to an aspect of the present invention. [Figure 9] FIG. 1 is a diagram illustrating an example of a signal configuration according to an aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The wireless communication system in this embodiment includes an access point device (AP, also referred to as a base station device) and multiple station devices (STA, also referred to as terminal devices). The communication system and network configured with the access point device and the station devices are called 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.

[0017] 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, one 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 that forms 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 forms a group in place of an access point device. This station device is called a group owner and can also be considered an access point device.

[0018] In the IEEE 802.11 system, each device can transmit multiple types of frames (communication frames) with a common frame format. The frames 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). A PPDU consists of a Physical layer header (PHY header) containing information for signal processing at the Physical layer, and a Physical Service Data Unit (PSDU, PHY layer frame), which is the data unit processed at the Physical layer. A PSDU can be configured to include an Aggregated MPDU (A-MPDU), which aggregates multiple MAC Protocol Data Units (MPDU, MAC layer frames), which are the units of retransmission in the wireless section.

[0020] The PHY header includes reference signals such as a short training field (STF) used for signal detection and synchronization, a long training field (LTF) used to acquire channel information for data demodulation, and control signals such as a signal (SIG) containing control information for data demodulation. Depending on the corresponding standard, STFs are classified as Legacy-STF (L-STF), High Throughput-STF (HT-STF), Very High Throughput-STF (VHT-STF), High Eficiency-STF (HE-STF), and Extremely High Throughput-STF (EHT-STF). Similarly, LTFs and SIGs are classified as L-LTF, HT-LTF, VHT-LTF, HE-LTF, L-SIG, HT-SIG, VHT-SIG, HE-SIG, and EHT-SIG. VHT-SIG is further classified into VHT-SIG-A1, VHT-SIG-A2, and VHT-SIG-B. Similarly, HE-SIG is classified into HE-SIG-A1 to HE-SIG-A4 and HE-SIG-B. In addition, assuming technical updates in the same standard, a Universal SIGNAL (U-SIG) field containing additional control information can be included.

[0021] 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, 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.

[0022] 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.

[0023] 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 the data unit processed at the MAC layer, and a Frame Check Sequence (FCS), which checks whether the frame is error-free (Figure 1). Multiple MSDUs can also be aggregated into an Aggregated MSDU (A-MSDU).

[0024] Frame types at the MAC layer are broadly classified into three: management frames, which manage the connection status between devices; control frames, which manage the communication status between devices; and data frames, which contain the actual transmitted data. Each of these 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 frame control field in the MAC header.

[0025] A beacon frame includes a field indicating the period (beacon interval) at which beacons are 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.

[0026] 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, which includes a status code indicating whether the station device has been authenticated. By reading the status code included in the authentication response frame, the station device can determine whether its own authentication request has been approved by the access point device. Note that 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.

[0027] Following the authentication procedure, the station device transmits a connection request frame to the access point device to initiate a connection procedure. Upon receiving the connection request frame, the access point device determines whether to permit the station device to connect and transmits a connection response frame to notify the result. The connection response frame contains a status code indicating whether the connection process is successful, as well as an association ID (AID) for identifying the station device. The access point device can manage multiple station devices by assigning different AIDs to each station device for which it has issued a connection permission.

[0028] After the connection process is completed, the access point device and station 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. Specific implementation methods for HCF include Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA).

[0029] 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 wireless channels 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. This 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 a carrier sense level (CS level) or a 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.

[0030] An access point device performs carrier sensing during an interframe space (IFS) that is 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 the access point device is about to transmit. The IEEE 802.11 system defines several IFSs with different durations, including the short interframe space (SIFS) used for frames assigned the highest priority, the polling interframe space (PIFS: PCF IFS) used for frames with relatively high priority, and the distributed arbitration interframe space (DIFS: DCF IFS) used for frames with low priority. When transmitting data frames using DCF, the access point device uses DIFS.

[0031] 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 frame correctly. Therefore, frame collisions are avoided by having each transmitting station wait for a randomly set time before starting transmission. When the access point device determines through carrier sense that the wireless channel is idle, it starts counting down a backoff counter set based on the CW. Only when the backoff counter reaches 0 does it acquire the right to transmit and transmit a frame to the station device. If the access point device determines through carrier sense that the wireless channel is busy 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.

[0032] 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 Identifier, Group ID) contained in VHT-SIG-A).

[0033] 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 an Ack frame from the station device. Note that if the station device does not 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 a 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.

[0034] When a station device determines that a received frame is not addressed to itself, it sets a network allocation vector (NAV) based on the length of the frame contained 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 based on physical CS during the period set in the NAV, so communication control using NAV is also called virtual carrier sense (virtual CS). In addition to being set based on information contained in the PHY header, the NAV is also set by RTS frames and CTS frames introduced to solve the hidden terminal problem.

[0035] 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 a station device within the BSS.

[0036] 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 a CW. The 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 within the BSS (e.g., a data frame including CF-end) is received, the station device can acquire the transmission right only when it receives a signal signaling acquisition of the transmission right for itself (e.g., a data frame including CF-poll) from the PC. 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.

[0037] A wireless communication device has either or both of a function for transmitting and receiving a PPDU. Fig. 2 is a diagram showing an example of the structure of a PPDU transmitted by a wireless communication device. A PPDU conforming to the IEEE 802.11a / 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 an L-STF, an L-LTF, an L-SIG, a VHT-SIG-A, a VHT-STF, a VHT-LTF, a VHT-SIG-B, and a Data frame. The 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 Data frames.The PPDU considered for the IEEE 802.11be standard is configured to include some or all of the following: L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, HET-LTF, and Data frames.

[0038] 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 conforming to the IEEE 802.11a / g standard can properly receive an L-header in a PPDU conforming to the IEEE 802.11n / ac / ax / be standard. A wireless communication device conforming to the IEEE 802.11a / g standard can receive a PPDU conforming to the IEEE 802.11n / ac / ax / be standard, treating it as a PPDU conforming to the IEEE 802.11a / g standard.

[0039] However, wireless communication devices that comply with the IEEE 802.11a / g standard 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.

[0040] IEEE 802.11 specifies a method for inserting duration information into L-SIG as a method for wireless communication devices conforming to the IEEE 802.11a / g standard to appropriately set NAV (or perform reception for a predetermined period of time). Information about the transmission rate in the L-SIG (RATE field, L-RATE field, L-RATE, L_DATARATE, L_DATARATE field) and information about the transmission duration (LENGTH field, L-LENGTH field, L-LENGTH) are used by wireless communication devices conforming to the IEEE 802.11a / g standard to appropriately set NAV.

[0041] 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 successfully received the L-SIG using MRC, it can interpret the PPDU including the L-SIG as a PPDU that complies with the IEEE 802.11ax or IEEE 802.11be standard.

[0042] Even while receiving a PPDU, the wireless communication device can receive a part of a PPDU other than the PPDU (for example, a preamble, L-STF, L-LTF, 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 the 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.

[0043] Ack and BA can also be called responses (response frames). In addition, probe responses, authentication responses, and connection responses can also be called responses.

[0044] 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 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 sounding to be performed (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]

[0045] 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, wireless communication device 4001-1 and wireless communication device 4001-2 (access point devices 4001-1, 4001-6) will also be referred to as wireless communication device 4001 (access point device 4001) when described without specifying each individual device, and wireless communication devices 4002-1 to 4002-6 (station devices 4002-1 to 4002-6) will also be referred to as wireless communication device 4002 (station device 4002) when described without specifying each individual device. 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. Also, 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 further include multiple wireless communication devices.

[0046] 5 is a diagram showing an example of the configuration of station device 4002. Station device 4002 includes a radio control unit (radio control step) 5001, a timer unit (timer step) 5002, a radio communication unit (radio communication step) 5003, and an antenna unit 5004. Furthermore, radio communication unit 5003 includes a physical layer frame generation unit (physical layer frame generation step) 5003a, a radio transmission unit (radio transmission step) 5003b, a radio reception unit (radio 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.

[0047] 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.

[0048] Timer unit 5002 includes one or more timers and manages the timers related to the sounding process. Details of timer unit 5002 will be described later. Note that, in the example of Fig. 5, timer unit 5002 is shown as being included in wireless control unit 5001, but is not limited to this configuration, and may be configured to be provided outside wireless control unit 5001 and to operate under control from wireless control unit 5001.

[0049] 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.

[0050] 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.

[0051] 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 (e.g., 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.

[0052] 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.

[0053] The channel estimation unit 5003e estimates the channel state through which the physical layer frame has propagated, based on a received signal of an 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.

[0054] 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.

[0055] The wireless control unit 5001 can perform physical carrier sensing and virtual carrier sensing based on the received power measurement result in the received power measuring unit 5003d and the information acquired in the signal demodulation unit 5003f, 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.

[0056] When there is control information, data, or the like 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, when the wireless channel state determination information indicates an idle state, the wireless control unit 5001 can countdown the backoff counter, and when the wireless channel state determination information indicates a busy state, the wireless control unit 5001 can stop the countdown. 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, when the wireless channel state determination information indicates an idle state and the backoff counter value is 0, the wireless control unit 5001 can notify the wireless communication unit 5003 of transmission decision information. Furthermore, when the wireless resource state determination information indicates an idle state, the wireless control unit 5001 can notify the wireless communication unit 5003 of transmission decision information.

[0057] FIG. 6 is a diagram showing 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 in FIG. 6 is basically configured similarly to the station device 4002 in 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 in FIG. 5 will be described using the same reference numerals.

[0058] The wireless control unit 6001 performs information processing for 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.

[0059] 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.

[0060] 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 radio waves 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.

[0061] 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 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.

[0062] 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.

[0063] 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, when the wireless channel state determination information indicates an idle state, the wireless control unit 6001 can countdown the backoff counter, and when the wireless channel state determination information indicates a busy state, the wireless control unit 6001 can stop the countdown. 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, when the wireless channel state determination information indicates an idle state and the backoff counter value is 0, the wireless control unit 6001 can notify the wireless communication unit 5003 of transmission decision information. Furthermore, when the wireless resource state determination information indicates an idle state, the wireless control unit 6001 can notify the wireless communication unit 5003 of transmission decision information.

[0064] 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.

[0065] 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 is referred to as an MLD access point device, and a station device that supports MLO is referred to as an MLD station device. Furthermore, MLD access point devices and MLD station devices are collectively referred to as MLD wireless communication devices. In this embodiment, wireless communication devices 4001-1, 4001-2, 4002A, and 4002B described above are described as MLD wireless communication devices, but in actual operation, not all wireless communication devices in a wireless communication system necessarily support MLO.

[0066] The MLD access point device 10001 and MLD station device 10002 will be described using Figure 7. An 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 called a physical layer link) that constitutes a multilink. Each sub-wireless communication device may be compatible with all frequency bands (and frequency channels) supported by the MLD wireless communication device, or each may be compatible with one of the frequency bands (or frequency channels). Figure 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 sub-access point device 10001-N. 8 shows an example in which the MLD station device 10002 is similarly configured with two sub-wireless communication devices, in this case two substation devices 10002-1 and 10002-2, and a multilink control unit 10012, but the number of substation devices may be any number equal to or greater than 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 a portion of the circuitry within the wireless communication device, and may be referred to as sub-wireless communication units (sub-access point units, substation units).

[0067] 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.

[0068] 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 more sub-wireless communication devices (sub-access point devices, substation devices) it may have. In other words, for each MLD wireless communication device existing in one 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.

[0069] Substation apparatus 10002-1 associates with sub-access point apparatus 10001-1 and establishes wireless link 10003-1 (first wireless link), while substation apparatus 10002-2 associates with sub-access point apparatus 10001-2 and establishes wireless link 10003-2 (second wireless link).

[0070] The configuration of sub-access point devices 10001-N in Fig. 7 is the same as the configuration of access point device 4001 in Fig. 6, except that a multi-link control unit 10011 is connected to a 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 sub-access point devices 10001-1 and 10001-2, i.e., wireless links 10003-1 and 10003-2, and aggregates received data frames from sub-access point devices 10001-1 and 10001-2, i.e., wireless links 10003-1 and 10003-2.

[0071] 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.

[0072] In the following explanation, 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, first link) and wireless link 10003-2 (second wireless link, second link), but the present invention is not limited to this and can be similarly applied to a case in which the number of wireless links is three or more. Also, an example will be described in which the frequency band of the first wireless link is the 2.4 GHz band and the frequency band of the second wireless link is the 5 GHz band, 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 may change according to the laws and regulations of each country.

[0073] FIG. 8 is a schematic diagram illustrating a communication method according to one aspect of this embodiment. In FIG. 8, it is assumed that the wireless communication device according to this embodiment is able to use communication bands (sub-channels) 801-1 to 801-4. In the following description, it is assumed that each of sub-channels 801-1 to 801-4 has a bandwidth of 20 MHz, but the method according to this embodiment is not limited to this bandwidth. The wireless communication device performs a channel access operation, including random backoff, on a sub-channel among sub-channels 801-1 to 801-4 that is set as a primary channel. In the following description, it is assumed that sub-channel 801-1 is the primary channel. While performing a channel access operation on the primary channel, the wireless communication device also measures interference power on the other sub-channels. Once it has confirmed that the wireless medium is secured on the primary channel, if no interference power is observed on the other sub-channels, it can transmit a frame (first frame) on all sub-channels.

[0074] The example of Figure 8 shows that an interference frame 804 is observed by the wireless communication device in subchannel 801-2. In this case, the wireless communication device cannot use subchannel 801-2 for frame transmission, but can transmit frames using subchannels 801-1, 801-3, and 801-4 using preamble puncturing (PP) technology. In the example of Figure 8, the wireless communication device transmits PPDUs 802-1, 802-3, and 802-4, each including a PHY header 803-1, a PHY header 803-3, and a PHY header 803-4. In other words, the wireless communication device according to this embodiment transmits a PPDU using available subchannels 801-1 to 801-4, including at least one subchannel with no signal (no signal assigned) within the PPDU band. In the example of Figure 8, the subchannel with no signal corresponds to subchannel 801-2. Furthermore, the wireless communication device according to this embodiment can include information indicating the subchannel without a signal in at least one of the PHY header 803-1, PHY header 803-3, and PHY header 803-4.

[0075] 8, the end timing of the interference signal 804 observed by the wireless communication device on subchannel 801-2 is earlier than the end timing of PPDU 802-1. This suggests that the wireless communication device may be able to use subchannel 801-2 in the time period following the end timing of the interference signal 804. However, since the wireless media reserved for PPDU 802-1, PPDU 802-3, and PPDU 802-4 transmitted by the wireless communication device are subchannels 801-1, 801-3, and 801-4, the wireless communication device must enter channel access operation to reserve subchannel 801-2 in order to transmit a frame on subchannel 801-2. However, because subchannel 801-2 is not a primary channel for the wireless communication device, the wireless communication device cannot perform a random backoff operation.

[0076] Therefore, the wireless communication device according to this embodiment utilizes the multi-link operation (MLO) described above. In the following description, the wireless communication device according to this embodiment is assumed to be an MLD access point device 10001, but it goes without saying that the following method can also be implemented by an MLD station device 10002.

[0077] 9 is a schematic diagram showing a communication method according to one aspect of this embodiment. The MLD access point device 10001 sets frequencies for the first wireless link set for the sub-access point device 10001-1 and the second wireless link set for the sub-access point device 10001-2 so that at least a portion of the channel bands overlap. For simplicity's sake, it is assumed below that the MLD access point device 10001 sets both the first wireless link and the second wireless link so that sub-channels 801-1 to 801-4 are available.

[0078] The MLD access point device 10001 can notify station devices belonging to the same BSS and access point devices and station devices belonging to other BSSs that frequencies for the first wireless link (first link) set to the sub-access point device 10001-1 and the second wireless link (second link) set to the sub-access point device 10001-2 will be set so that at least a portion of the channel bandwidths will overlap. Here, the first wireless link and the second wireless link include the operating channel bandwidth (Operation channel bandwidth) to be set, the communication band to be set, the sub-channel to be set, the RU allocation to be set, and the fact that at least a portion of the RUs to be used will overlap.

[0079] The MLD access point device 10001 sets the primary channel of sub-access point device 10001-1 to sub-channel 801-1. The MLD access point device 10001 then sets the primary channel of sub-access point device 10001-2 to sub-channel 801-2. There is no particular limitation on the method for setting the primary channel, but when the MLD access point device 10001 sets frequencies that have at least part of the same communication band for the sub-access point devices under its management, it is preferable to set different sub-channels as the primary channels for each.

[0080] Sub-access point device 10001-1 enters channel access operation on sub-channel 801-1, which is the primary channel. In the example of Fig. 9, because interfering signal 804 is observed on sub-channel 801-2, sub-access point device 10001-1 can transmit frames using sub-channels 801-1, 801-3, and 801-4. Here, sub-access point device 10001 can include information indicating a sub-channel with no signal (sub-channel 801-2 in this case) in at least one of PHY header 803-1, PHY header 803-3, and PHY header 803-4, and can also include information indicating that a PPDU (second frame) may be placed in the sub-channel with no signal.

[0081] The information indicating that a PPDU may be placed in the subchannel without a signal may be 1-bit information indicating whether or not a PPDU may be placed in the subchannel without a signal. Furthermore, the information indicating that a PPDU may be placed in the subchannel without a signal may be information indicating whether or not a PPDU is permitted to be placed in the subchannel without a signal. Furthermore, the information indicating that a PPDU may be placed in the subchannel without a signal may be information indicating whether or not a PPDU is prohibited from being placed in the subchannel without a signal. Furthermore, the information indicating that a PPDU may be placed in the subchannel without a signal may be information indicating a radio link on which a PPDU may be placed in the subchannel without a signal.

[0082] While the sub-access point device 10001-1 transmits a PPDU including a sub-channel with no signal on the first wireless link, the sub-access point device 10001-2 enters listening mode on the sub-channel 801-2 corresponding to the sub-channel with no signal. For example, since the sub-access point device 10001-2 has the primary channel set to the sub-channel 801-2, when the sub-channel 801-2 becomes idle, the sub-access point device 10001-2 can secure the wireless medium of the sub-channel 801-2 through a channel access operation.

[0083] The sub-access point device 10001-2 that has secured the wireless medium of the sub-channel 801-2 can transmit the PPDU 903 including the PHY header 902 on the sub-channel 801-2.

[0084] The sub-access point device 10001-2 that has secured the wireless medium of sub-channel 801-2 can set the end of the frame transmission section secured by PPDU 903 including PHY header 902 (the end time of the PPDU to be transmitted) so that it does not exceed the end of the frame transmission section secured by PPDU 802-1. Furthermore, the sub-access point device 10001-2 can align the end of the frame transmission section secured by PPDU 903 including PHY header 902 with the end of the frame transmission section secured by PPDU 802-1. Here, the sub-access point device 10001-2 can keep the difference between the end of the frame transmission section secured by PPDU 903 including PHY header 902 and the end of the frame transmission section secured by PPDU 802-1 to 8 us or less. Furthermore, if at least one of PPDU 903 and PPDU 802-1 is a trigger frame that triggers a frame and does not require the receiving communication device to perform carrier sensing, sub-access point device 10001-2 can set the difference between the end of the frame transmission section secured by PPDU 903 including PHY header 902 and the end of the frame transmission section secured by PPDU 802-1 to 4 us or less. By controlling in this manner, wireless communication devices receiving PPDU 802-1, PPDU 802-3, PPDU 802-4, and PPDU 903 do not need to support simultaneous transmission and reception in which transmission and reception operations are performed simultaneously.

[0085] According to the above explanation, sub-access point device 10001-2 has set sub-channel 801-2 as its primary channel, and therefore can transmit PPDU 903 on sub-channel 801-2. However, if sub-access point device 10001-1 measures an interfering signal on sub-channel 801-3, a sub-channel with no signal within the PPDU band transmitted by sub-access point device 10001-1 also becomes sub-channel 801-3. In this case, sub-access point device 10001-2 according to this embodiment cannot transmit PPDU 903 because its primary channel is not sub-channel 801-3.

[0086] Therefore, the MLD access point device according to this embodiment further includes a sub-access point device 10001-3, which can establish a third wireless link with sub-channel 801-3 set as the primary channel. Similarly, the MLD access point device according to this embodiment further includes a sub-access point device 10001-4, which can establish a fourth wireless link with sub-channel 801-4 set as the primary channel. In other words, the MLD access point device according to this embodiment can include sub-access point devices with wireless links established with sub-channels that are not set as primary channels in the first wireless link, among the sub-channels that sub-access point device 10001-1 can use in the first wireless link, as the primary channel. Controlled in this manner, the MLD access point device according to this embodiment can transmit a PPDU in a sub-channel with no signal within the PPDU band when a wireless medium is secured in the sub-channel with no signal.

[0087] The sub-access point device 10001-1 according to this embodiment can set an additional primary channel for the first wireless link, in addition to the primary channel, on a sub-channel other than the sub-channel on which the primary channel is set. Hereinafter, this additional primary channel will be referred to as a non-primary channel access (NPCA) primary channel. The MLD access point device according to this embodiment can set the NPCA primary channel set on the sub-access point device 10001-1 and the primary channel set on the sub-access point device 10001-2 to the same sub-channel. By controlling in this manner, if the sub-access point device 10001-1 is unable to secure a wireless medium on the primary channel, the sub-access point device 10001-1 attempts to secure a wireless medium on the NPCA primary channel. However, with NPCA, a delay occurs when transitioning operation from the primary channel to the NPCA primary channel. In such a case, the MLD access point device according to this embodiment can also have the sub-access point device 10001-2 transmit a PPDU over a second wireless link whose primary channel is set to the same sub-channel as the NPCA primary channel of the sub-access point device 10001-1, rather than using the NPCA primary channel in the sub-access point device 10001-1. Conversely, if the sub-access point device 10001-1 can secure a wireless medium over the primary channel while the sub-access point device 10001-2 is transmitting a PPDU, the sub-access point device 10001-1 can also transmit a PPDU that includes the primary channel as a sub-channel.

[0088] Furthermore, if the delay time required for the sub-access point device 10001-1 to transition from the primary channel to the NPCA primary channel becomes an issue, the sub-access point device 10001-2 can enter channel access operation (e.g., random backoff) on a second wireless link having the same sub-channel as the NPCA primary channel of the sub-access point device 10001-1 set as its primary channel, and after the sub-access point device 10001-2 has secured the wireless medium, the sub-access point device 10001-1 can transmit a PPDU on the NPCA primary channel in accordance with an instruction from the sub-access point device 10001-2. The MLD access point device according to this embodiment can also manage, in association with each other, a first link having a predetermined sub-channel set as its NPCA primary channel and a second link having the NPCA primary channel set as its primary channel. The MLD access point device according to this embodiment can share part of the channel access operation between the sub-access point device 10001-1 to which the first link is established and the sub-access point device 100001-2 to which the second link is established. For example, the NPCA primary channel of the sub-access point device 10001-1 and the primary channel of the sub-access point device 10001-2 can share the backoff value acquired in the random backoff operation. Furthermore, the NPCA primary channel of the sub-access point device 10001-1 and the primary channel of the sub-access point device 10001-2 can share the NAV value set.

[0089] According to the method described above, when a wireless communication device transmits a PPDU that includes a subchannel with no signal within the PPDU band, the device can further transmit the PPDU on the subchannel with no signal, thereby contributing to improving frequency utilization efficiency. [2. Common to all embodiments]

[0090] The communication device according to the present invention can communicate in a frequency band (frequency spectrum) called an unlicensed band, which does not require permission to use from a country or region, but the usable frequency band is not limited to this. The communication device according to the present invention can also be effective in 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.

[0091] The program running on the wireless communication device according to the present invention is a program that controls a CPU and other components (a program that causes a computer to function) so as to realize the functions of the above-described embodiments of the present invention. Information handled by these devices is temporarily stored in RAM during processing, and then stored in various ROMs or HDDs, from which the CPU reads, modifies, and writes the information as needed. Recording media for storing the programs may include semiconductor media (e.g., ROMs, non-volatile memory cards, etc.), optical recording media (e.g., DVDs, MOs, MDs, CDs, BDs, etc.), and magnetic recording media (e.g., magnetic tapes, flexible disks, etc.). Executing a loaded program not only realizes the functions of the above-described embodiments, but may also realize the functions of the present invention by processing in cooperation with an operating system or other application programs based on instructions from the program.

[0092] 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 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. 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.

[0093] 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.

[0094] It should be noted that the present invention is not limited to the above-described embodiments. The wireless communication device of the present invention is not limited to application to mobile station devices, but can of course be applied to stationary or non-mobile electronic devices installed indoors or outdoors, such as AV equipment, kitchen equipment, cleaning / washing equipment, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0095] 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]

[0096] The present invention is suitable for use in a wireless communication device and a communication method. [Explanation of symbols]

[0097] 3001 NDP Announcement Frame 3002 NDP Frame 3003 Compressed Beamforming / CQI Frame 4001-1, 4001-2 Wireless communication device (access point device) 4002-1~6 Wireless communication equipment (station equipment) 4003-1, 4003-2 Wireless communication systems 5001 Radio control unit 5002 Timer section 5003 Wireless Communication Department 5003a Physical layer frame generator 5003b Radio transmitter 5003c Wireless receiver 5003d Received power measurement unit 5003e Channel Estimation Unit 5003f signal demodulation unit 5004 Antenna part 6001 Radio control unit 10001 MLD access point device 10001-1, 10001-2, 10001-N sub-access point devices 10002 MLD station equipment 10002-1, 10002-2, 10002-N Substation Equipment 10011, 10012 Multi-link control unit

Claims

1. A wireless communication device in which a first link and a second link are established, a transmitter that transmits a first frame over the first link and a second frame over the second link; a receiver that performs carrier sensing on the first link and the second link; At least a part of the channel bands of the first link and the second link overlap; the first frame includes a subchannel with no signal allocation within the channel band; the transmitter transmits the second frame on the subchannel with no signal in the second link; a terminal end of a frame transmission interval secured by the second frame that does not extend beyond a terminal end of a frame transmission interval secured by the first frame;

2. The wireless communication device according to claim 1 , wherein an end of a frame transmission interval reserved for the second frame and an end of a frame transmission interval reserved for the first frame are aligned.

3. The wireless communication device according to claim 1 , wherein the first frame includes control information indicating that the second frame can be set for the subchannel with no signal.

4. The wireless communication device according to claim 3 , wherein the control information indicating that the second frame can be set includes information indicating the second link.

5. A communication method for a wireless communication device in which a first link and a second link are established, comprising: transmitting a first frame over the first link and a second frame over the second link; performing carrier sensing on the first link and the second link; At least a part of the channel bands of the first link and the second link overlap; the first frame includes a subchannel with no signal within the channel band; transmitting the second frame on the unsignaled subchannel in the second link; A communication method in which an end of a frame transmission interval secured by the second frame does not exceed an end of a frame transmission interval secured by the first frame.

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