Station device, access point device, and wireless communication method

Abstract

To make it possible to maintain good communication quality of a wireless link in wireless communication.SOLUTION: A station device uses a first wireless link and a second wireless link, sets communication quality between the station device and another station device, and measures the quality of each of the first wireless link and the second wireless link. In addition, the station device attempts to secure a wireless medium with a wireless link selected according to the quality measured in each wireless link and a medium securing condition based on the set communication quality.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a station device, an access point device, and a wireless communication method.

Background Art

[0002] IEEE (The Institute of Electrical and Electronics Engineers Inc.) has been continuously working on updating the specifications of IEEE 802.11, which is a wireless LAN standard, in order to achieve higher speed and more efficient frequency utilization in wireless LAN communication. In a wireless LAN, wireless communication can be performed using a frequency band (unlicensed band) that can be used without permission (license) from a country or region. For personal use such as in homes, a wireless LAN access point function is included in a line termination device for connecting to a WAN (Wide Area Network) line such as the Internet, or a wireless LAN access point device is connected to the line termination device, etc., so that Internet access from within a residence has been wirelessly enabled. As a result, a wireless LAN station device such as a smartphone or a personal computer can connect to a wireless LAN access point device and access the Internet.

[0003] In 2021, the standardization of IEEE 802.11ax was completed, and wireless LAN devices compliant with this standard, as well as communication devices such as smartphones and personal computers equipped with the wireless LAN devices, have entered the market as Wi-Fi 6 (registered trademark, the name for IEEE 802.11ax compliant products certified by the Wi-Fi Alliance) compatible products. Currently, as a successor standard to IEEE 802.11ax, the standardization activities of IEEE 802.11be are underway, and discussions are also progressing towards its successor standard, IEEE 802.11bn. With the rapid spread of wireless LAN devices, in recent IEEE 802.11 standardization, consideration has been given to further improving the throughput per user in the overcrowded environment of wireless LAN devices.

[0004] In addition, in the standardization of IEEE 802.11be, discussions are being held on Multi-Link Operation (MLO), which enables a wireless communication device to simultaneously use multiple frequency bands, channels, etc. to maintain connections with multiple links and communicate (Non-Patent Document 1). As an example of MLO, there is one that simultaneously operates three link connections in different frequency bands, such as a connection in the 2.4 GHz band, a connection in the 5 GHz band (5.2 GHz band, 5.3 GHz band, 5.6 GHz band, etc.), and a connection in the 6 GHz band. Of course, the combinations of frequency bands, channels, etc. are not limited to this, 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) can also be used as one link constituting a multi-link. According to MLO, a wireless communication device can simultaneously maintain multiple link connections with different wireless resources and communication-related settings. The wireless communication device can not only transmit and receive frames using multiple links simultaneously, but also switch the link connection for transmitting and receiving frames, that is, change the frequency band, without performing a reconnection operation. Here, each individual link constituting the multi-link is also called a physical layer link. In addition, a wireless communication device corresponding to MLO is called a Multi-Link Device (MLD).

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a wireless LAN, in order to achieve high speed and high frequency utilization efficiency, maintaining the communication quality of a wireless link is an issue. In particular, efficiency when using a plurality of wireless links becomes an issue.

Means for Solving the Problems

[0007] The wireless communication apparatus and wireless communication method according to the present invention for solving the above-described problems are as follows.

[0008] (1) That is, a station apparatus according to one aspect of the present invention is a station apparatus that communicates with another station apparatus using a plurality of wireless links including a first wireless link and a second wireless link, the station apparatus including a wireless communication unit that receives and transmits a wireless frame via the plurality of wireless links, and a wireless control unit, the wireless communication unit receiving first control information for setting communication quality regarding communication with the other station apparatus, the first control information including information indicating the first wireless link and the second wireless link, the wireless control unit performing quality measurement of the wireless link in the first wireless link and the second wireless link using the wireless communication unit, and attempting to acquire a transmission opportunity based on the first control information in at least one of the first wireless link and the second wireless link.

[0009] (2) Further, in the station apparatus according to one aspect of the present invention, the quality measurement of the wireless link is performed based on a first time and a second time, and the first time is the time when transmission preparation of the MPDU is completed.

[0010] (3) Further, in the station apparatus according to one aspect of the present invention, the second time is the time when the transmission of the MPDU is actually transmitted.

[0011] (4) Further, in the station apparatus according to one aspect of the present invention, the second time is the time when a response MPDU to the transmission of the MPDU is received.

[0012] (5) Also, in the station device according to one aspect of the present invention, the measurements at the first time and the second time are performed separately on the first link and the second link.

[0013] (6) Also, in the station device according to one aspect of the present invention, when measuring the wireless link quality, a quality indicator of the wireless link is determined based on the ratio of the time during which CCA is idle within a predetermined time period.

[0014] (7) Also, in the station device according to one aspect of the present invention, the wireless control unit includes a first timer corresponding to the first wireless link and a second timer corresponding to the second wireless link. After receiving the first control information, the first timer and the second timer are started. When the first timer expires, the MPDU is transmitted on the first wireless link and the first timer is reset. When the second timer expires, the MPDU is transmitted on the second wireless link and the second timer is reset. When the MPDU is transmitted on the first wireless link before the first timer expires, the first timer is reset. When the MPDU is transmitted on the second wireless link before the second timer expires, the second timer is reset.

[0015] (8) Also, the access point device according to one aspect of the present invention includes a wireless unit that communicates with the first station device and the second station device using at least a first wireless link and a second wireless link, and a control unit. When the first station device is set to communicate directly with the second station device, the first control information is transmitted to the first station device, and the first control information includes the medium acquisition conditions in the first wireless link or the second wireless link.

[0016] (9) Also, in the access point device according to one aspect of the present invention, the first control information includes second control information, and the second control information is information regarding a timer included in the first station device or the second station device, and the timer is used for conditions under which the first station device or the second station device transmits an MPDU.

[0017] (10) Also, in the wireless communication method according to one aspect of the present invention, first control information for setting communication quality regarding communication with the other station device is received, the first control information includes information indicating the first wireless link and the second wireless link, wireless link quality measurement is performed on the first wireless link and the second wireless link, and an attempt is made to acquire a transmission opportunity based on the first control information on at least one of the first wireless link and the second wireless link.

Advantages of the Invention

[0018] According to the wireless communication device and the wireless communication method of the present invention, it is possible to maintain good communication quality of a wireless link in wireless communication.

Brief Description of the Drawings

[0019]

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Figure 12

Embodiments for Carrying Out the Invention

[0020] The wireless communication system in the present embodiment includes an access point device (also referred to as an AP or a base station device) and a plurality of station devices (also referred to as STAs or terminal devices). In addition, a communication system and a network composed of an access point device and a station device are called a basic service set (BSS: Basic Service Set, management range). Further, the station device according to the present embodiment can have the functions of an access point device. Similarly, the access point device according to the present embodiment can have the functions of a station device. Therefore, hereinafter, when simply referred to as a communication device or a wireless communication device, the communication device or the wireless communication device can represent both an access point device and a station device.

[0021] The access point device and the station device within the BSS shall each perform communication based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance). In this embodiment, the infrastructure mode in which the access point device communicates with a plurality of station devices is targeted. However, the method of this embodiment can also be implemented in the ad-hoc mode in which station devices directly communicate with each other. In the ad-hoc mode, one station device serves as a substitute for the access point device to form a BSS. The BSS in the ad-hoc mode is also referred to as an IBSS (Independent Basic Service Set). Hereinafter, the station device that forms an IBSS in the ad-hoc mode can also be regarded as an access point device. The method of this embodiment can also be implemented in Wi-Fi Direct (registered trademark) in which station devices directly communicate with each other. In Wi-Fi Direct, one station device serves as a substitute for the access point device to form a group. The said station device is called a group owner and can also be regarded as an access point device.

[0022] In the IEEE 802.11 system, each device can transmit a plurality of types of frames (communication frames) having a common frame format. The frames are respectively defined in the physical (PHY: Physical) layer, the medium access control (MAC: Medium Access Control) layer, and the logical link control (LLC: Logical Link Control) layer.

[0023] The frame at the PHY layer is called a Physical Protocol Data Unit (PPDU: Physical layer frame). The PPDU is composed of a Physical layer header (PHY header) that contains information for signal processing at the physical layer and a Physical Service Data Unit (PSDU: PHY Service Data Unit) which is a data unit processed at the physical layer. The PSDU can be configured to include an Aggregated MPDU (A-MPDU) which aggregates multiple MAC Protocol Data Units (MPDU: MAC layer frames) that are retransmission units in the wireless section.

[0024] The PHY header includes reference signals such as a Short Training Field (STF: Short Training Field) used for signal detection and synchronization and a Long Training Field (LTF: Long Training Field) used for obtaining channel information for data demodulation, and control signals such as a Signal (SIG: Signal) that contains control information for data demodulation. Also, the STF is classified into Legacy-STF (L-STF), High Throughput-STF (HT-STF), Very High Throughput-STF (VHT-STF), High Eficiency-STF (HE-STF), Extremely High Throughput-STF (EHT-STF), etc. according to the corresponding standard, and the LTF and SIG are similarly classified into L-LTF, HT-LTF, VHT-LTF, HE-LTF, L-SIG, HT-SIG, VHT-SIG, HE-SIG, EHT-SIG. The VHT-SIG is further classified into VHT-SIG-A1, VHT-SIG-A2, and VHT-SIG-B. Similarly, the HE-SIG is classified into HE-SIG-A1~4 and HE-SIG-B. Also, assuming a technology update in the same standard, a Universal SIGNAL (U-SIG) field that contains additional control information can be included.

[0025] Furthermore, the PHY header can include information for identifying the BSS of the frame source (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. Also, the information for identifying the BSS can be a value unique to the BSS other than the SSID and MAC address (e.g., BSS Color, etc.). The information indicating the BSS Color can be included in the HE-SIG-A or U-SIG.

[0026] 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.

[0027] The MPDU is composed of a MAC header (MAC header) that includes information for signal processing at the MAC layer, etc., a MAC service data unit (MSDU: MAC Service Data Unit) or frame body that is a data unit processed at the MAC layer, and a frame check sequence (FCS: Frame Check Sequence) that checks whether there is an error in the frame (Figure 1). Also, a plurality of MSDUs can be aggregated as an aggregated MSDU (A-MSDU).

[0028] Frame types in the MAC layer are broadly classified into three types: management frames that manage connection states between devices, control frames that manage communication states between devices, and data frames that contain actual transmitted data. Each of these is further classified into multiple types of sub-frame types. Control frames include acknowledgement (Ack or ACK: Acknowledgement) frames, block acknowledgement (BA or BlockAck: Block Acknowledgement) frames, request to send (RTS: Request To Send) frames, clear to send (CTS: Clear To Send) frames, etc. BlockAck can perform acknowledgement (receiving completion notification) for multiple MPDUs. Management frames include beacon frames, probe request frames, probe response frames, authentication frames, association request frames, association response frames, etc. Data frames include data frames, CF-poll frames, etc. Each device can recognize the frame type and sub-frame type of the received frame by reading the content of the frame control field included in the MAC header.

[0029] The beacon frame includes fields indicating the period (Beacon interval) at which the beacon is transmitted and the SSID. The access point device can periodically notify the BSS of the beacon frame, and the station device can recognize the surrounding access point devices by receiving the beacon frame. The recognition of an access point device by a station device based on the beacon frame notified by the access point device is called passive scanning. On the other hand, the exploration of an access point device by a station device by notifying a probe request frame within the BSS is called active scanning. The access point device can transmit a probe response frame as a response to the probe request frame, and the content of the probe response frame is the same as the content of the beacon frame.

[0030] After recognizing the access point device, the station device performs a connection process for 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 that it wishes to connect to. When the access point device receives the authentication request frame, it transmits an authentication response frame containing a status code indicating the approval or disapproval of authentication for the station device to the station device. The station device can determine whether its authentication request to the access point device has been approved by reading the status code included in the authentication response frame. Note that the access point device and the station device can exchange the authentication request frame and the authentication response frame (both are collectively referred to as the authentication frame) multiple times.

[0031] After the authentication procedure, the station device sends a connection request frame to perform a connection procedure with the access point device. When the access point device receives the connection request frame, it determines whether to permit the connection of the station device and sends a connection response frame to notify the result. The connection response frame includes, in addition to a status code indicating the success or failure of the connection process, an association identifier (AID: Association IDentifier) for identifying the station device. By setting different AIDs for the station devices that have been permitted to connect, the access point device can manage multiple station devices.

[0032] After the connection process is performed, the access point device and the station device perform actual data transmission. In the IEEE 802.11 system, as media access methods, Distributed Coordination Function (DCF), Point Coordination Function (PCF), and Hybrid Coordination Function (HCF) which is an extension of these are defined. For HCF, as specific implementation means, Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA) are defined.

[0033] First, an example of the operation when the access point device transmits a signal to the 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 their own devices prior to communication. For example, when the access point device and the station device attempting to transmit a frame receive a signal with a received power higher than a predetermined clear channel assessment level (CCA level) in the wireless channel during the carrier sense period performed prior to transmission, they postpone the transmission of the frame in the wireless channel. Hereinafter, the state in which a signal with a received power equal to or higher than the CCA level is detected in the wireless channel is called the busy state, and the state in which a signal with a received power equal to or higher than the CCA level is not detected is called the idle state. In this way, the CS performed based on the power level of the signal actually received by each device is called physical carrier sense (physical CS). Note that the CCA level is also called the carrier sense level (CS level) or the CCA threshold (CCAT). Note that when the access point device and the station device detect a signal with a received power equal to or higher than the CCA level, they enter at least the operation of demodulating the signal in the PHY layer.

[0034] The access point device performs carrier sense during the period of the inter-frame space (IFS: Inter Frame Space) set according to the type of frame to be transmitted, and determines whether the wireless channel is in a busy state or an idle state. The period during which the access point device performs carrier sense varies depending on the frame type and sub-frame type of the frame that the access point device will transmit next. In the IEEE 802.11 system, a plurality of IFSs with different periods are defined, such as the Short IFS (SIFS) used for the frame with the highest priority, the Polling IFS (PIFS: PCF IFS) used for frames with relatively high priority, and the Distributed Coordination Function IFS (DIFS: DCF IFS) used for frames with low priority. When transmitting a data frame by DCF, the access point device uses DIFS.

[0035] 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 the contention window (CW) is used. In CSMA / CA, it is assumed that a frame transmitted by a certain transmitting station is received by the receiving station without interference from other transmitting stations. Therefore, if multiple transmitting stations transmit frames at the same timing, the frames may collide, and the receiving station may not be able to receive them correctly. Thus, each transmitting station waits for a time randomly set before starting transmission to avoid frame collisions. When the access point device determines that the wireless channel is idle by carrier sense, it starts counting down the backoff counter set based on the CW. It can obtain the right to transmit only when the backoff counter reaches 0 and can then transmit a frame to the station device. If the access point device determines that the wireless channel is busy by carrier sense during the countdown of the backoff counter, the countdown of the backoff counter is stopped. Then, when the wireless channel becomes idle again, the access point device continues to wait for the same period as the previous IFS and resumes the remaining countdown of the previous backoff counter.

[0036] The station device, which is the receiving station, receives the frame, reads the PHY header of the frame, and demodulates the received frame. Then, the station device can recognize whether the frame is addressed to itself by reading the MAC header of the demodulated signal. Note that the station device can also determine the destination of the frame based on the information contained in the PHY header (e.g., the group identifier (GID) contained in VHT-SIG-A).

[0037] If the station device determines that the received frame is addressed to itself and can correctly demodulate the frame without errors, it must send an Ack frame indicating that the frame has been correctly received to the access point device, which is the transmitting station. The Ack frame is one of the highest-priority frames transmitted after only waiting for the SIFS period (without taking a random backoff time). The access point device ends a series of communications upon receiving the Ack frame transmitted from the station device. Note that if the station device cannot correctly receive the frame, the station device does not send 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 frame transmission, it determines that the communication has failed and ends the communication. Thus, the end of a single communication (also called a burst) in the IEEE 802.11 system is determined by the presence or absence of an Ack frame reception, except for special cases such as the transmission of notification signals like beacon frames or when fragmentation used to divide transmitted data is employed.

[0038] If the station device determines that the received frame is not addressed to itself, it sets the Network Allocation Vector (NAV) based on the length of the frame (Length) included in the PHY header, etc. The station device does not attempt transmission during the period set in the NAV. That is, since the station device performs the same operation as when it determines that the wireless channel is busy by physical CS for the period set in the NAV, the communication control by the NAV is also called virtual carrier sense (virtual CS). In addition to being set based on the information included in the PHY header, the NAV is also set by RTS frames and CTS frames introduced to solve the hidden terminal problem.

[0039] Next, based on the PCF, an example of the operation when the access point device transmits a signal to the station device will be described. Different from the DCF where each device performs carrier sensing and autonomously acquires the right to transmit, in the PCF, a control station called a point coordinator (PC) controls the transmission rights of each device within the BSS. Generally, the access point device becomes the PC and acquires the transmission rights of the station devices within the BSS.

[0040] The communication period by the 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 rights during the CFP. The access point device that is the PC notifies the BSS of a beacon frame containing information such as the CFP period (CFP Max duration) prior to the PCF communication. Note that PIFS is used for the transmission of the beacon frame notified at the start of the PCF transmission, and it is transmitted without waiting for the CW. The station device that receives the beacon frame sets the CFP Max duration included in the beacon frame in the NAV. Thereafter, until the period set in the NAV elapses or a signal notifying the end of the CFP within the BSS (for example, a data frame containing CF-end) is received, the station device can acquire the transmission right only when it receives a signal (for example, a data frame containing CF-poll) that signals the acquisition of the transmission right for itself from the PC. Note that within the CFP period, packet collisions do not occur within the same BSS, so each station device does not take the random backoff time used in the DCF.

[0041] The wireless communication device has either or both of the functions of transmitting and receiving a PPDU. FIG. 2 is a diagram showing an example of the PPDU configuration transmitted by the wireless communication device. The PPDU corresponding to the IEEE 802.11a / g standard has a configuration including L-STF, L-LTF, L-SIG, and a Data frame (MAC frame, payload, data part, data, information bits, etc.). The PPDU corresponding to the IEEE 802.11n standard has a configuration including L-STF, L-LTF, L-SIG, HT-SIG, HT-STF, HT-LTF, and a Data frame. The PPDU corresponding to the IEEE 802.11ac standard has a configuration including some or all of L-STF, L-LTF, L-SIG, VHT-SIG-A, VHT-STF, VHT-LTF, VHT-SIG-B, and a Data frame. The PPDU corresponding to the IEEE 802.11ax standard has a configuration including some or all of L-STF, L-LTF, L-SIG, RL-SIG in which L-SIG is repeated temporally, HE-SIG-A, HE-STF, HE-LTF, HE-SIG-B, and a Data frame. The PPDU being considered for standardization in IEEE 802.11be has a configuration including some or all of L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, HET-LTF, and a Data frame.

[0042] L-STF, L-LTF, and L-SIG surrounded by a dotted line in FIG. 2 are configurations 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 corresponding to the IEEE 802.11a / g standard can appropriately receive the L-header in a PPDU corresponding to the IEEE 802.11n / ac / ax / be standard. A wireless communication device corresponding to the IEEE 802.11a / g standard can receive a PPDU corresponding to the IEEE 802.11n / ac / ax / be standard as if it were a PPDU corresponding to the IEEE 802.11a / g standard.

[0043] However, since a wireless communication device compliant with the IEEE 802.11a / g standard cannot demodulate a PPDU compliant with the IEEE 802.11n / ac / ax / be standard following the L-header, it cannot demodulate information regarding the transmitter address (TA: Transmitter Address), receiver address (RA: Receiver Address), Duration / ID field, etc.

[0044] As a method for a wireless communication device compliant with the IEEE 802.11a / g standard to appropriately set the NAV (or perform a reception operation for a predetermined period), IEEE 802.11 stipulates a method of inserting Duration information into the L-SIG. Information regarding the transmission rate within the L-SIG (RATE field, L-RATE field, L-RATE, L_DATARATE, L_DATARATE field), information regarding the transmission period (LENGTH field, L-LENGTH field, L-LENGTH) is used for a wireless communication device compliant with the IEEE 802.11a / g standard to appropriately set the NAV.

[0045] 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, for example, the L-SIG transmitted multiple times using maximal ratio combining (MRC). Furthermore, when the wireless communication device correctly receives and completes the L-SIG by MRC, it can interpret that the PPDU including the L-SIG is a PPDU compliant with the IEEE 802.11ax or IEEE 802.11be standard.

[0046] During the reception operation of a PPDU, the wireless communication device can perform the reception operation of a part of a PPDU other than the said PPDU (for example, a preamble, L-STF, L-LTF, PHY header, etc. 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 said PPDU during the reception operation of the PPDU, it can update part or all of the destination address, source address, PPDU, or information regarding the Data period.

[0047] Ack and BA can also be referred to as responses (response frames). Further, a probe response, an authentication response, and a connection response can be referred to as responses.

[0048] FIG. 3 is a diagram showing an example of a sounding procedure for channel estimation of a wireless communication path in IEEE 802.11ax. In an example of FIG. 3, first, an access point device (AP) transmits a Null Data PPDU (NDP) Announcement frame 3001 that specifies information such as a station device (STA) to be the target of sounding to be performed hereafter (the recipient of a sounding frame) and the type of feedback information. Further, after a SIFS period from the NDP Announcement frame, the access point device transmits an NDP frame 3002 including a training field for channel estimation. The station device performs channel estimation based on the received NDP frame 3002 and transmits a frame for feedback of the channel estimation result to the access point device, for example, a Compressed Beamforming / CQI frame 3003, after a SIFS period from the NDP frame 3002. [1. First Embodiment]

[0049] FIG. 4 is a diagram showing an example of a wireless communication system according to the present embodiment. The wireless communication system 4003-1 includes a wireless communication device 4001-1 and wireless communication devices 4002-1 to 4002-3. Note that the wireless communication device 4001-1 is also referred to as an access point device 4001-1, and the wireless communication devices 4002-1 to 4002-3 are also referred to as station devices 4002-1 to 3. In addition, the wireless communication devices 4002-1 to 4002-3 (station devices 4002-1 to 4002-3) are also referred to as a wireless communication device 4002A (station device 4002A) as a device connected to the wireless communication device 4001-1. The wireless communication device 4001-1 and the wireless communication device 4002A are wirelessly connected and are in a state where they can transmit and receive PPDUs to and from each other. In addition, the wireless communication system according to the present embodiment may include a wireless communication system 4003-2 in addition to the wireless communication system 4003-1. The wireless communication system 4003-2 includes a wireless communication device 4001-2 and wireless communication devices 4002-4 to 4002-6. Note that the wireless communication device 4001-2 is also referred to as an access point device 4001-2, and the wireless communication devices 4002-4 to 4002-6 are also referred to as station devices 4002-4 to 4002-6. In addition, the wireless communication devices 4002-4 to 4002-6 (station devices 4002-4 to 4002-6) are also referred to as a wireless communication device 4002B (station device 4002B) as a device connected to the wireless communication device 4001-2. Furthermore, when the wireless communication device 4001-1 and the wireless communication device 4001-2 (access point devices 4001-1, 4001-6) are described without being individually specified, they are also referred to as a wireless communication device 4001 (access point device 4001), and when the wireless communication devices 4002-1 to 4002-6 (station devices 4002-1 to 4002-6) are described without being individually specified, they are also referred to as a wireless communication device 4002 (station device 4002). The wireless communication system 4003-1 and the wireless communication system 4003-2 form different BSSs, but this does not necessarily mean that the ESSs (Extended Service Sets) representing the service sets forming the LAN (Local Area Network) are different.That is, wireless communication devices belonging to the same ESS can be regarded as belonging to the same network from the upper 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 a plurality of wireless communication devices.

[0050] Figure 5 is a diagram showing an example of the configuration of the station device 4002. The station device 4002 includes a radio control unit (radio control step) 5001, a timer unit (timer step) 5002, a wireless communication unit (wireless communication step) 5003, and an antenna unit 5004. Further, 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.

[0051] The radio control unit 5001 performs information processing of layers higher than the physical layer, such as the MAC layer and the LLC layer, on information handled within the own wireless communication device (information related to frames to be transmitted, MIB (Management Information Base), etc.) and frames received from other wireless communication devices, and controls the wireless communication unit 5003.

[0052] 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. In an example of FIG. 5, the timer unit 5002 is described as being included in the radio control unit 5001, but the configuration is not limited to this, and it may be provided outside the radio control unit 5001 and configured to operate under the control of the radio control unit 5001.

[0053] 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 radio control unit 5001. The beamforming processing may be realized by multiplying the beamforming matrix (beamforming filter) notified from the radio control unit 5001 by the modulated signal. The physical layer frame generation unit 5003a outputs the generated physical layer frame to the wireless transmission unit 5003b.

[0054] The wireless transmission unit 5003b converts the physical layer frame input from the physical frame generation unit 5003a into a signal in the radio frequency (RF) band and generates a wireless signal. The processes performed by the wireless transmission unit 5003b include digital-to-analog conversion, filtering, frequency conversion from baseband frequency to radio frequency, etc. The wireless transmission unit 5003b transmits the generated wireless signal through the antenna unit 5004.

[0055] The wireless reception unit 5003c has a function of converting the wireless signal received through the antenna unit 5004 into a baseband signal and generating a physical layer signal (for example, a physical layer frame). The processes performed by the wireless reception unit 5003c include frequency conversion processing from radio frequency to 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 reception unit 5003c, is input to the received power measurement unit 5003b, the channel estimation unit 5003e, and the signal demodulation unit 5003f.

[0056] The received power measurement unit 5003d measures the received power of the received signal input from the wireless reception unit 5003c. The received power measurement unit 5003d can measure the received power related to the radio wave received in the measurement target frequency channel, the received power of the LTF of the received physical layer frame, etc. The received power measurement unit 5003d can notify the measurement result of the received power to the radio control unit 5001.

[0057] The channel estimation unit 5003e estimates the channel state through which the physical layer frame has propagated based on the received signals of LTFs (such as L-LTF, HT-LTF, VHT-LTF, HE-LTF, etc.) included in the physical layer frame received by the wireless reception 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.

[0058] The signal demodulation unit 5003f performs channel equalization, demodulation, error correction decoding, etc. on the physical layer frame received by the wireless reception unit 5003c, and acquires information such as the PHY header and the MAC layer frame. The channel estimation result in the channel estimation unit 5003e, etc. can be used for the processing of channel equalization. The signal demodulation unit 5003f outputs the acquired PHY header and MAC layer frame to the wireless control unit 5001.

[0059] The wireless control unit 5001 performs physical carrier sensing and virtual carrier sensing based on the received power measurement result in the received power measurement unit 5003d and the information acquired by the signal demodulation unit 5003f, and can determine the state of the wireless channel (including determination of whether it is in an idle state or a busy state). The wireless control unit 5001 can notify the wireless communication unit 5003 of the state determination information of this wireless channel.

[0060] When there is control information, data, etc. to be transmitted, the wireless control unit 5001 can start a backoff procedure using the above-described 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 execute the countdown of the backoff counter, and when the wireless channel state determination information indicates a busy state, the wireless control unit 5001 can stop the countdown of the backoff counter. Further, the wireless control unit 5001 makes a transmission determination using either one or both of the wireless channel state determination information and the value of the backoff counter. For example, when the wireless channel state determination information indicates an idle state and the value of the backoff counter is 0, the wireless control unit 5001 can notify the wireless communication unit 5003 of the transmission determination information. Also, when the wireless resource state determination information indicates an idle state, the wireless control unit 5001 can notify the wireless communication unit 5003 of the transmission determination information.

[0061] FIG. 6 is a diagram showing an example of the configuration of the 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. Further, 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 also basically has the same configuration as the station device 4002 in FIG. 5. Therefore, in the following, the description will focus on the differences between the two, and the description of the same parts will be omitted. Also, the parts corresponding to the station device in FIG. 5 will be described with the same reference numerals.

[0062] The wireless control unit 6001 performs information processing for layers higher than the physical layer, such as the MAC layer and the LLC layer, on information handled within the wireless communication device itself (information related to frames to be transmitted, MIB (Management Information Base), etc.) and frames received from other wireless communication devices, and controls the wireless communication unit 5003.

[0063] 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 from the wireless control unit 6001. The physical layer frame generation unit 5003a outputs the generated physical layer frame to the wireless transmission unit 5003b.

[0064] The received power measurement unit 5003d measures the received power of the received signal input from the wireless reception unit 5003c. The received power measurement unit 5003d can measure the received power related to 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 measurement result of the received power to the wireless control unit 6001.

[0065] 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 reception unit 5003c. The channel estimation unit 5003e can notify the channel estimation result to the signal demodulation unit 5003f and the wireless control unit 6001.

[0066] The signal demodulation unit 5003f performs channel equalization, demodulation, error correction decoding, etc. on the physical layer frame received by the wireless reception unit 5003c, and acquires information such as the PHY header and the MAC layer frame. For the channel equalization process, the channel estimation result in the channel estimation unit 5003e can be used. The signal demodulation unit 5003f outputs the acquired PHY header and MAC layer frame to the wireless control unit 6001.

[0067] When there is control information, data, beacon, etc. to be transmitted, the wireless control unit 6001 can start the backoff procedure using the above-described 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 execute the countdown of the backoff counter, and when the wireless channel state determination information indicates a busy state, the wireless control unit 6001 can stop the countdown of the backoff counter. Further, the wireless control unit 6001 makes a transmission determination using either one or both of the wireless channel state determination information and the value of the backoff counter. For example, when the wireless channel state determination information indicates an idle state and the value of the backoff counter is 0, the wireless control unit 6001 can notify the wireless communication unit 5003 of the transmission determination information. Also, when the wireless resource state determination information indicates an idle state, the wireless control unit 6001 can notify the wireless communication unit 5003 of the transmission determination information.

[0068] FIG. 7 is a diagram showing an example of a sounding procedure in the wireless communication system according to the present embodiment. In FIG. 7, it is assumed that the connection of the wireless link (the first wireless link) between the access point device 4001 and the station device 4002 is established, and an example of the communication flow on the wireless link is shown on the left side, and an example of the state transition of a timer 5002-1 (also referred to as the first timer) provided in the timer unit 5002 of the station device 4002 is shown on the right side. Also, in FIG. 7, the timer 5002-1 is assumed to be in a non-active state (7101) at the start.

[0069] The access point device 4001 generates control information (first control information) including setting information regarding the timer 5002-1 provided in the station device 4002, sounding frame transmission conditions from the station device 4002, etc., and transmits a wireless frame 7001 including the control information to the station device 4002. The setting information regarding the timer 5002-1 may include a timer count initial value, a timer count expiration value, timer activation instruction information, timer reset instruction information, timer reset timing information, etc.

[0070] The station device 4002 that has received the wireless frame 7001 including the first control information acquires the first control information included in the wireless frame 7001, sets the timer count initial value, etc. of the timer 5002-1 according to the first control information, and then activates it (7002). By the activation 7002, the timer 5002-1 is reset to the timer count initial value, transitions from the inactive state 7101 to the active state 7102, and starts the countdown operation. The timer 5002-1 continues the countdown while in the active state. In FIG. 7, an example in which setting, resetting, activation, countdown start, etc. of the timer count initial value, etc. of the timer 5002-1 are executed at once by receiving the wireless frame 7001 has been described, but it is not limited to this. For example, setting and resetting of the timer count initial value, etc., activation and countdown start may be executed triggered by different wireless frames (control information included therein).

[0071] Also, in FIG. 7, the timer 5002-1 is assumed to be a countdown timer. An example was described in which it is reset to a preset timer count initial value and reaches the end state at count 0, but the present invention is not limited to this. For example, the timer count end value may be set to a value other than 0 separately. Alternatively, the timer 5002-1 may be configured as an up-counter, initialized to count 0 by reset, and reach the end state when the count reaches a preset timer count end value.

[0072] When the station device 4002 receives a wireless frame (first wireless frame) 7003 that requires a response and no error is detected in the wireless frame 7003, it transmits an Ack frame 7004 as a response frame to the wireless frame 7003, and then transmits a sounding frame 7005 (hereinafter, the sounding frame transmitted on the first wireless link is also referred to as the first sounding frame), and resets the timer 5002-1 to the timer count initial value (7006). The reset timer 5002-1 continues in the active state (7103) and starts counting down from the timer count initial value. Note that the timing of resetting the timer 5002-1 (7006) is not limited to the time of transmitting the sounding frame 7005, and can be set within a range where the effect does not change, such as between the timing of transmitting the Ack frame 7004 and the timing of transmitting the sounding frame 7005.

[0073] The wireless frame that requires a response is not limited to a data frame, and may be a frame including control information that requires a response. It is preferable that the transmission of the Ack frame 7004 and the transmission of the sounding frame 7005 are performed at intervals of SIFS, but the present invention is not limited to this, and other IFS used when the priority is high may be used. Further, the Ack frame and the sounding frame may be concatenated and transmitted. Alternatively, a new frame combining the Ack frame and the sounding frame may be defined and transmitted.

[0074] When receiving the wireless frame 7003, the sounding frame 7005 may be transmitted and the timer 5002-1 may be reset only when the count of the timer 5002-1 has reached (or is less than) a predetermined value. In this case, when the timer 5002-1 has not reached the predetermined value, that is, when the elapsed time from the previous sounding frame transmission is less than the predetermined time, the transmission of the sounding frame is suppressed, and the overhead due to the sounding frame transmission can be reduced.

[0075] The wireless frame 7003 may be a data frame that transmits an A-MPDU in which a plurality of MPDUs are aggregated, and the Ack frame may be a BlockAck frame. When using the BlockAck frame, the sounding frame 7005 may be transmitted and the timer 5002-1 may be reset only when the number or ratio of positive acknowledgments included in the BlockAck is less than a predetermined value. In this case, when the timer 5002-1 is not in the expired state and the state of the wireless link is good, the transmission of the sounding frame is suppressed, and the overhead due to the sounding frame transmission can be reduced.

[0076] When the count of the timer 5002-1 reaches 0 and enters the expired state (7104), the station device 4002 enters the sounding frame transmission waiting state (7007). When the timer 5002-1 expires, the station device 4002 performs carrier sensing, and after confirming that the wireless channel is in the idle state, starts the backoff procedure (7008). During the backoff period, if the wireless channel is in the idle state, the station device 4002 transmits the sounding frame 7009 and resets the timer 5002-1 (7010). The timer 5002-1 is reset to the initial timer count value and transitions to the active state, and starts the countdown operation (7105).

[0077] When the station device 4002 receives a wireless frame 7011 including control information (fourth control information) including information such as cancellation of the setting related to the timer 5002-1, it deactivates the timer 5002-1 (7012). The deactivated timer 5002-1 stops the countdown operation and transitions to the inactive state 7106.

[0078] The sounding frames 7005 and 7009 may be used, for example, as a set of two frames of an NDP frame or an NDP Announcement frame and an NDP frame, but are not limited thereto, and any frame configured to include a signal capable of estimating the channel between the station device 4002 and the access point device 4001 may be used.

[0079] The access point device 4001 that has received the sounding frames 7005 and 7009 from the station device 4002 may perform channel estimation between the station device 4002 and the access point device 4001 based on the received sounding frames, for example, and calculate a channel matrix, a beamforming matrix (beamforming filter), or the like.

[0080] Also, as a modification, when receiving other control information (third control information) instead of directly receiving the first control information from the access point device 4001, information corresponding to the first control information may be generated in the station device 4002 based on the received control information. As an example, when receiving setting information regarding QoS (Quality of Service), the station device 4002 may activate (7002) after setting the initial timer count value of the timer 5002-1 and the like. The station device 4002 may change the initial timer count value and the like according to the conditions required as QoS. When the allowable delay time is set short, the initial timer count value may be made small. Also, when bit rate guarantee is set, the initial timer count value may be made small. Further, the station device 4002 may set the initial timer count value of the timer 5002-1 and the like based on the capability information exchanged with the access point device 4001. The QoS setting may be set by the access point device 4001 according to the current traffic situation, or may be set by an application executed on the network. Also, an application executed on the network may acquire the QoS setting via the access point device 4002.

[0081] Also, as a modification, when receiving other control information instead of directly receiving the fourth control information from the access point device 4001, information corresponding to the fourth control information may be generated in the station device 4002 based on the received control information. As an example, when receiving setting information regarding QoS, the station device 4002 may deactivate (7012) the timer 5002-1. When the allowable delay time is set long, the timer 5002-1 may be deactivated. Also, when the bit rate setting is set to best effort, the timer 5002-1 may be deactivated.

[0082] As a modification, FIG. 8 shows an example of the sounding procedure when the timer unit 5002 of the station device 4002 includes a timer 5002-2 (also referred to as the third timer) in addition to the timer 5002-1 (the first timer). Hereinafter, the description will focus on the differences from the example of the sounding procedure in FIG. 7, and the description of the same parts will be omitted. Also, the parts corresponding to those in FIG. 7 will be described with the same reference numerals.

[0083] In FIG. 8, it is assumed that the connection of the wireless link (the first wireless link) between the access point device 4001 and the station device 4002 is established. An example of the communication flow on the wireless link is shown on the left side, and an example of the state transition of the timer 5002-1 and the timer 5002-2 included in the timer unit 5002 of the station device 4002 is shown on the right side. Also in FIG. 8, the timer 5002-1 and the timer 5002-2 are assumed to be in the non-active state (7101, 7201) at the start.

[0084] Different from the example of FIG. 7, the first control information included in the wireless frame 7001 transmitted by the access point device 4001 to the station device 4002 is generated to include, in addition to the setting information regarding the timer 5002-1 and the sounding frame transmission condition from the station device 4002, the setting information regarding the timer 5002-2, and the wireless frame 7001 including the control information is transmitted to the station device 4002. The setting information regarding the timer 5002-1 and the timer 5002-2 may include, for each timer, the timer count initial value, the timer count expiration value, the timer activation instruction information, the timer reset instruction information, the timer reset timing information, and the like. Here, the setting information may be selected such that the time (count number) until the timer expiration in the timer 5002-2 is shorter than the time until the timer expiration in the timer 5002-1.

[0085] The station device 4002 that has received the wireless frame 7001 containing the first control information acquires the first control information contained in the wireless frame 7001, and after setting the initial timer count values of the timer 5002-1 and the timer 5002-2 according to the first control information, activates both timers (7002, 7202). By the activation 7002, the timer 5002-1 and the timer 5002-2 are reset to the initial timer count values, and respectively transition from the inactive state 7101 and the inactive state 7202 to the active state 7102 and the active state 7202, and start the countdown operation. The timer 5002-1 and the timer 5002-2 continue the countdown while in the active state. Note that in FIG. 8, an example in which the setting, reset, activation, countdown start, etc. of the initial timer count values of the timer 5002-1 and the timer 5002-2 are executed at once by the reception of the wireless frame 7001 has been described, but it is not limited to this. For example, the setting and reset of the initial timer count values, etc., and the activation and countdown start may be executed by triggering with different wireless frames (control information contained therein).

[0086] Also, in FIG. 8, the timer 5002-1 and the timer 5002-2 are assumed to be countdown timers, and an example in which they become the initially set timer count value by reset and reach the expiration state at count 0 has been described, but it is not limited to this. For example, the timer count expiration value may be set to other than 0 separately. Alternatively, the timer 5002-1 and the timer 5002-2 may be configured as count-up timers, initialized to count 0 by reset, and reach the expiration state when the count reaches the initially set timer count expiration value.

[0087] When the station device 4002 receives a wireless frame (first wireless frame) 7003 that requires a response and no error is detected in the wireless frame 7003, it transmits an Ack frame 7004 as a response frame to the wireless frame 7003. At this time, if the timer 5002-2 is not in the expired state (active state), unlike the example in FIG. 7, the sounding frame 7005 is not transmitted following the Ack frame 7004. At this time, the timer 5002-1 is not reset either, and the timers 5002-1 and 5002-2 continue to be in the active state.

[0088] If the active state continues, the timer 5002-2 reaches count 0 earlier than the timer 5002-1 and transitions to the expired state (7203). At this time, the timer 5002-2 indicates that it has reached the expired state (7051).

[0089] When the station device 4002 receives a wireless frame 7051 that requires a response and no error is detected in the wireless frame 7051, it transmits an Ack frame 7052 as a response frame to the wireless frame 7051. At this time, further, if the timer 5002-2 is in the expired state (7203), a sounding frame 7053 is transmitted following the Ack frame 7052, and the timers 5002-1 and 5002-2 are reset to the timer count initial value (7054). The reset timers 5002-1 and 5002-2 become active states (7103, 7204) and start counting down from the timer count initial value. Note that the timing of resetting the timers 5002-1 and 5002-2 (7054) is not limited to the transmission time of the sounding frame 7053, and can be set within a range where the effect remains the same, such as between the transmission timing of the Ack frame 7052 and the transmission timing of the sounding frame 7053.

[0090] The wireless frames that require a response are not limited to data frames, and may also be frames containing control information that requires a response. Although it is preferable to transmit the Ack frame 7052 and the sounding frame 7053 at intervals of SIFS, it is not limited thereto, and other IFS used when the priority is high may be used. Furthermore, the Ack frame and the sounding frame may be concatenated and transmitted. Also, a new frame combining the Ack frame and the sounding frame may be defined and the frame may be transmitted.

[0091] The wireless frame 7051 may be a data frame that transmits an A-MPDU in which a plurality of MPDUs are aggregated, and the Ack frame may also be a BlockAck frame. When using the BlockAck frame, the sounding frame 7053 may be transmitted and the timers 5002-1 and 5002-2 may be reset only when the number or ratio of positive responses included in the BlockAck is less than a predetermined value. In this case, when the timer 5002-1 is not in the expired state, if the state of the wireless link is good, the transmission of the sounding frame is suppressed, and the overhead due to the sounding frame transmission can be reduced.

[0092] The station device 4002 indicates that the timer 5002-2 has reached count 0 and is in the expiration state (7205) (7055), and when the count of the timer 5002-1 reaches 0 and is in the expiration state (7104), it enters the standby state for transmitting a sounding frame (7007). When the timer 5002-1 expires, the station device 4002 performs carrier sensing, and after confirming that the wireless channel is in the idle state, it starts the backoff procedure (7008). During the backoff period, if the wireless channel is in the idle state, the station device 4002 transmits the sounding frame 7009 and resets the timer 5002-1 and the timer 5002-2 (7010). The timer 5002-1 and the timer 5002-2 are reset to the initial timer count value and transition to the active state, and start the countdown operation (7105, 7206).

[0093] Unlike the example in FIG. 7, the fourth control information included in the wireless frame 7011 transmitted by the station device 4002 to the access point device 4001 may include information such as cancellation of the setting related to the timer 5002-2 in addition to the information such as cancellation of the setting related to the timer 5002-1. Note that the information on cancellation of the setting related to the timer 5002-2 may be the same information as the information on cancellation of the setting related to the timer 5002-1. When the station device 4002 receives the wireless frame 7011 including the fourth control information, it deactivates the timer 5002-1 and the timer 5002-2 (7012). The deactivated timer 5002-1 and timer 5002-2 stop the countdown operation and transition to the inactive states 7106 and 7207.

[0094] As a modification, when receiving other control information without directly receiving the first control information from the access point device 4001, information corresponding to the first control information may be generated in the station device 4002 based on the received control information. As an example, when receiving setting information regarding QoS, the station device 4002 may set the initial timer counts of the timer 5002-1 and the timer 5002-2 and then activate (7002) them. The station device 4002 may change the initial timer counts and the like according to the conditions required as QoS. When the allowable delay time is set short, the initial timer counts may be made smaller. Also, when bit rate guarantee is set, the initial timer counts may be made smaller. Further, the station device 4002 may set the initial timer counts of the timer 5002-1 and the timer 5002-2 based on the capability information exchanged with the access point device 4001. The QoS setting may be set by the access point device 4001 according to the current traffic situation, or may be set by an application executed on the network. Also, an application executed on the network may acquire the QoS setting via the access point device 4002.

[0095] As a modification, when receiving other control information without directly receiving the fourth control information from the access point device 4001, information corresponding to the fourth control information may be generated in the station device 4002 based on the received control information. As an example, when receiving setting information regarding QoS, the station device 4002 may deactivate (7012) the timer 5002-1 and the timer 5002-2. When the allowable delay time is set long, the timer 5002-1 and the timer 5002-2 may be deactivated. Also, when the bit rate setting is set to best effort, the timer 5002-1 and the timer 5002-2 may be deactivated.

[0096] Fig. 9 shows a flowchart diagram of an example of the sounding procedure in the station device 4002 when using the timers 5002-1 and 5002-2.

[0097] When the station device 4002 transmits an Ack frame (Yes in step S9001), it checks whether the timer 5002-2 has expired (step S9002). If the timer 5002-2 has expired (Yes in step S9002), it transmits a sounding frame following the transmission of the Ack frame (step S9003), resets the timers 5002-1 and 5002-2 (step S9004), and returns to step S9001.

[0098] If No in step S9001, it checks whether the timer 5002-1 has expired (step S9005). If the timer 5002-1 has not expired (No in step S9005), it returns to step S9001. If the timer 5002-1 has expired (Yes in step S9005), it performs carrier sense (step S9006), performs a backoff procedure (step S9007), then transmits a sounding frame (step S9008), resets the timers 5002-1 and 5002-2 (step S9009), and returns to step S9001. Although not shown in the figure, if the wireless channel becomes busy during the carrier sense and backoff procedure, it retries from step S9006, but if a wireless frame to be received is detected, it returns to step S9001.

[0099] Next, as a modification example, an example will be described in which the access point device 4001 and the station device 4002 perform communication using two wireless links simultaneously, namely, 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, corresponding to multi-link operation (MLO: Multi-Link Operation). Note that MLO is not limited to two wireless links, and a plurality of wireless links in different frequency bands (or frequency channels) can be used.

[0100] A multi-link device (MLD: Multi-Link Device) is a device capable of multi-link communication by multi-link operation. An access point device corresponding to MLO is called an MLD access point device, and a station device corresponding to MLO is called an MLD station device. Also, the MLD access point device and the MLD station device are collectively referred to as an MLD wireless communication device. In the present embodiment, the wireless communication devices 4001-1, 4001-2, 4002A, and 4002B described above will be described as MLD wireless communication devices. However, in actual operation, not all wireless communication devices in the wireless communication system necessarily need to support MLO.

[0101] Using FIG. 10, the MLD access point device 10001 and the MLD station device 10002 will be described. The MLD wireless communication device is composed of a plurality of 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 a multi-link. Each sub-wireless communication device may correspond to all the frequency bands (as well as frequency channels) to which the MLD wireless communication device corresponds, or each may correspond to any one of the frequency bands (or frequency channels). In FIG. 10, an example is shown 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 the multi-link control unit 10011, but the number of sub-access point devices is any number of 2 or more. Hereinafter, when describing any one of the plurality of sub-access point devices as a representative, it is referred to as the sub-access point device 10001-N. Similarly, in FIG. 10, an example is shown in which the MLD station device 10002 is composed of two sub-wireless communication devices, in this case two sub-station devices 10002-1 and 10002-2, and the multi-link control unit 10012, but the number of sub-station devices is any number of 2 or more. Hereinafter, when describing any one of the plurality of sub-station devices as a representative, it is referred to as the sub-station device 10002-N. Also, the sub-wireless communication device (sub-access point device and sub-station device) may be composed of some circuits in the wireless communication device, and may also be referred to as a sub-wireless communication unit (sub-access point unit, sub-station unit).

[0102] In FIG. 10, an example is shown in which a plurality of sub-wireless communication devices are configured as logically separate blocks, but physically they may be composed of one wireless communication device. Alternatively, a plurality of sub-wireless communication devices may be physically configured as separate devices. In this embodiment, a case where each sub-wireless communication device is physically configured as a separate device will be described as an example.

[0103] Note that the number of sub - access point devices included in one MLD access point device and the number of sub - station devices included in one MLD station device may vary according to the grade, class, capabilities, etc. of each MLD wireless communication device. The higher the grade, class, and capabilities of the MLD wireless communication device, the larger the number of sub - wireless communication devices (sub - access point devices, sub - station devices) it may carry. That is, for each MLD wireless communication device existing in one wireless communication system, the sub - wireless communication devices (sub - access point devices, sub - station devices) constituting each MLD wireless communication device may be different according to the grade, class, capabilities, etc., and the numbers thereof do not have to match either.

[0104] The sub - station device 10002 - 1 connects (associates) to the sub - access point device 10001 - 1 and establishes a wireless link 10003 - 1 (the first wireless link). The sub - station device 10002 - 2 connects to the sub - access point device 10001 - 2 and establishes a wireless link 10003 - 2 (the second wireless link).

[0105] The configuration of the sub - access point device 10001 - N in FIG. 10 is the same as the configuration of the access point device 4001 in FIG. 6, except that the 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 to 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 the transmission data frames to the sub - access point devices 10001 - 1 and 10001 - 2, that is, to each wireless link 10003 - 1 and 10003 - 2, and aggregates the received data frames from each sub - access point device 10001 - 1 and 10001 - 2, that is, from each wireless link 10003 - 1 and 10003 - 2.

[0106] On the one hand, the configuration of the sub-station device 10002-N in FIG. 10 is the same as that of the station device 4002 in FIG. 5, except that the multi-link control unit 10012 is connected to the radio control units 5001 of the respective sub-station devices 10002-N. The multi-link control unit 10012 controls the radio links for the respective sub-station devices 10002-N and exchanges control information and transmission / reception data with the respective sub-station devices 10002-N. The multi-link control unit 10012 distributes the transmission data frames to the sub-station devices 10002-1 and 10002-2 of each radio link, that is, the respective radio links 10003-1 and 10003-2, and aggregates the received data frames from the sub-station devices 10002-1 and 10002-2 of each radio link, that is, the respective radio links 10003-1 and 10003-2.

[0107] In the following description, for the sake of simplicity, as an example, the case where the radio links constituting the multi-link are two radio links 10003-1 (first radio link) and 10003-2 (second radio link) will be described. However, the present invention is not limited to this, and the same applies to the case where the number of radio links is three or more. Further, the case where the frequency band of the first radio link is the 2.4 GHz band and the frequency band of the second radio link is the 5 GHz band will be described as an example. However, the frequency band used by each radio link can be arbitrarily set from the frequency bands (or frequency channels) supported by the radio communication system, such as the 2.4 GHz band, 5 GHz band, 6 GHz band, 60 GHz band, etc., and these may vary according to the regulations of each country.

[0108] An example of the sounding procedure in this modification will be described. The operations in each wireless link are the same as those in the case where there is one wireless link shown in FIG. 7. That is, in the first wireless link, the sub-access point device 10001-1 performs the same operation as the access point device 4001 in FIG. 7, and the station device 10002-1 performs the same operation as the station device 4002 in FIG. 7. In the second wireless link, the sub-access point device 10001-2 performs the same operation as the access point device 4001 in FIG. 7, and the station device 10002-2 performs the same operation as the station device 4002 in FIG. 7. Here, the timer provided in the timer unit 5002 of the station device 10002-1 is also called the timer 5002-1 (first timer) as in FIG. 7, and the timer provided in the timer unit 5002 of the station device 10002-2 is called the timer 5002-3 (second timer). Hereinafter, the description will focus on the differences from the example of the sounding procedure in FIG. 7, and the description of the same parts will be omitted.

[0109] Regarding the operation of the first wireless link, since it is the same as that in FIG. 7, the description thereof is omitted. In the second wireless link, when the sub-station device 10002-2 receives a wireless frame 7001-2 (read 7001 in FIG. 7 as 7001-2; the same applies hereinafter) including second control information including setting information regarding the timer 5002-3, sounding frame transmission conditions from the sub-station device 10002-2, etc. from the sub-access point device 10001-2, it activates (7002-2) after setting the initial value of the timer count of the timer 5002-3, etc. The setting information regarding the timer 5002-3 may include the initial value of the timer count, the expiration value of the timer count, timer activation instruction information, timer reset instruction information, timer reset timing information, etc. By the activation 7002-2, the timer 5002-3 is reset to the initial value of the timer count, transitions from the inactive state 7101-2 to the active state 7102-2, and starts the countdown operation. While the timer 5002-3 is in the active state, it continues to count down. Although an example has been described in which the setting, reset, activation, start of countdown, etc. of the initial value of the timer count of the timer 5002-3 are executed at once by the reception of the wireless frame 7001-2, the present invention is not limited thereto. For example, the setting and reset of the initial value of the timer count, etc., and the activation and start of countdown may be executed by triggering with different wireless frames (control information included therein).

[0110] Also, the timer 5002-3 is assumed to be a countdown timer, and an example has been described in which it becomes the initially set timer count value by reset and reaches the expiration state at count 0, but the present invention is not limited thereto. For example, the expiration value of the timer count may be set to a value other than 0 separately. Alternatively, the timer 5002-3 may be configured as an up-count timer, initialized to count 0 by reset, and reach the expiration state when the count reaches the initially set timer count expiration value.

[0111] When the substation device 10002-2 receives a wireless frame (second wireless frame) 7003-2 that requires a response and no error is detected in the wireless frame 7003-2, it transmits an Ack frame 7004-2 as a response frame for the wireless frame 7003-2, and then transmits a sounding frame 7005-2 (hereinafter, the sounding frame transmitted on the second wireless link is also referred to as the second sounding frame), and resets (7006-2) the timer 5002-3 to the timer count initial value. The reset timer 5002-3 continues in the active state (7103-2) and starts counting down from the timer count initial value. Note that the timing of resetting (7006-2) the timer 5002-3 is not limited to the time of transmitting the sounding frame 7005-2, and can be set within a range where the effect remains the same, such as between the timing of transmitting the Ack frame 7004-2 and the timing of transmitting the sounding frame 7005-2.

[0112] The wireless frame that requires a response is not limited to a data frame, and may be a frame that includes control information that requires a response. It is preferable that the transmission of the Ack frame 7004-2 and the transmission of the sounding frame 7005-2 are performed at intervals of SIFS, but it is not limited to this, and other IFS used when the priority is high may be used. Further, the Ack frame and the sounding frame may be concatenated and transmitted. Also, a new frame combining the Ack frame and the sounding frame may be defined and that frame may be transmitted.

[0113] When receiving the wireless frame 7003-2, the sounding frame 7005-2 may be transmitted and the timer 5002-3 may be reset only when the count of the timer 5002-3 has reached (or is below) a predetermined value. In this case, when the timer 5002-3 has not reached the predetermined value, that is, when the elapsed time since the previous sounding frame transmission is less than the predetermined time, the transmission of the sounding frame is suppressed, and the overhead due to the sounding frame transmission can be reduced.

[0114] The wireless frame 7003-2 may be a data frame that transmits an A-MPDU in which a plurality of MPDUs are aggregated, and the Ack frame may be a BlockAck frame. When using the BlockAck frame, the sounding frame 7005-2 may be transmitted and the timer 5002-3 may be reset only when the number or ratio of positive acknowledgments included in the BlockAck is less than a predetermined value. In this case, when the timer 5002-3 has not expired and the state of the wireless link is good, the transmission of the sounding frame is suppressed, and the overhead due to the sounding frame transmission can be reduced.

[0115] When the count of the timer 5002-3 reaches 0 and expires (7104-2), the sub-station device 10002-2 enters the sounding frame transmission waiting state (7007-2). When the timer 5002-3 expires, the sub-station device 10002-2 performs carrier sense, and after confirming that the wireless channel is in the idle state, starts the backoff procedure (7008-2). During the backoff period, if the wireless channel is in the idle state, the sub-station device 10002-2 transmits the sounding frame 7009-2 and resets the timer 5002-3 (7010-2). The timer 5002-3 is reset to the initial timer count value and transitions to the active state, and starts the countdown operation (7105-2).

[0116] When the substation device 10002-2 receives a wireless frame 7011-2 containing control information (sixth control information) including information such as cancellation of settings related to the timer 5002-3, it deactivates the timer 5002-3 (7012-2). The deactivated timer 5002-3 stops the countdown operation and transitions to the inactive state 7106. Note that when the substation device 10002-1 receives the fourth control information in the first wireless link, the substation device 10002-2 may also deactivate the timer 5002-3. Also, when the substation device 10002-2 receives the sixth control information in the second wireless link, the substation device 10002-1 may also deactivate the timer 5002-1.

[0117] Also, as a modification, when the substation device 10002-2 does not directly receive the second control information from the sub-access point device 10001-2 but receives other control information (fifth control information), information corresponding to the second control information may be generated in the substation device 10002-2 based on the received control information. As an example, when receiving setting information regarding QoS, the substation device 10002-2 may activate (7002-2) the timer 5002-3 after setting the timer count initial value and the like of the timer 5002-3. The substation device 10002-2 may change the timer count initial value and the like according to the conditions required as QoS. When the allowable delay time is set short, the timer count initial value may be made smaller. Also, when bit rate guarantee is set, the timer count initial value may be made smaller. Also, the substation device 10002-2 may set the timer count initial value and the like of the timer 5002-3 based on the capability information exchanged with the sub-access point device 10001-2. The QoS setting may be set by the sub-access point device 10001-2 according to the current traffic situation, or may be set by an application executed on the network. Also, an application executed on the network may acquire the QoS setting via the sub-access point device 10001-2.

[0118] Also, as a modification, when receiving other control information without directly receiving the sixth control information from the sub-access point device 10001-2, information corresponding to the sixth control information may be generated in the sub-station device 10002-2 based on the received control information. As an example, when receiving setting information regarding QoS, the sub-station device 10002-2 may deactivate (7012-2) the timer 5002-3. When the allowable delay time is set long, the timer 5002-3 may be deactivated. Also, when the bit rate setting is set to best effort, the timer 5002-3 may be deactivated.

[0119] Also, the sub-station device 10002-2 connected to the sub-access point device 10001-2 may be provided with a plurality of timers for sounding control. This sub-station device 10002-2 is provided with a second timer and a fourth timer in the same manner as the first timer and the third timer, and may be configured not to transmit a sounding frame when the fourth timer is not in an expired state when transmitting a response frame. Also, this sub-station device 10002-2 may be configured to perform carrier sensing when the second timer expires, confirm that the radio channel of the second link is in an idle state, and then perform back-off processing to transmit a sounding frame. This sub-station device 10002-2 may reset the second timer and the fourth timer after transmitting a sounding frame. It may be set such that the time until the fourth timer expires is shorter than the timer expiration time of the second timer.

[0120] When configured as an MLD, when the station device receives control information for changing settings such as the initial value of the timer count on any of the active links, for active links other than the link that received this control information, activation and deactivation of the timer may be performed. Also, when receiving setting information regarding QoS on any of the active links, for active links other than the link that received the QoS information, activation and deactivation of the timer may be performed.

[0121] According to the method described above, it is possible to maintain good communication quality of the wireless link in wireless communication.

[0122] As the following modification example, information for setting the required communication quality is exchanged between a plurality of station devices, the quality of a plurality of wireless links is measured between the station devices that have exchanged the information for setting the required communication quality, and an example of a configuration for attempting to secure a transmission opportunity (TXOP) on any of the plurality of wireless links based on the measured quality of the wireless links is shown below. The configurations of the station device and the access point device use the configurations described in FIGS. 4 and 5, but are not limited thereto.

[0123] Figure 11 shows an example of a flow in which the required communication quality is set when using two bands (Band1 and Band2) between a first station device (STA1) and a second station device (STA2), STA1 measures the quality of the wireless link in the two bands, and attempts to secure a transmission opportunity on the wireless link selected based on the measured quality of the wireless link. 11001 is a message including link quality setting request information transmitted from STA2 to STA1. This message includes information indicating that it is a setting of the link quality using Band1 and Band2. The method for setting the link quality is not particularly limited. As an example, communication quality determined by information regarding latency may be used, or when generating a wireless frame for transmission in the station device, it may be determined based on the period from the generation time of the protocol data unit (MPDU) generated at the MAC layer to the time when the generated MPDU is actually transmitted as a wireless frame. Also, it may be determined based on the period from the time when the MPDU is generated in one station device until the MPDU is transmitted as a wireless frame, received by the other station device, and retrieved as an MPDU from the MAC layer. Also, it may be determined based on the period from the time when an MPDU is generated and a wireless frame is transmitted in one station device until the time when a wireless frame including a confirmation response corresponding to that wireless frame is received. At this time, the mechanism used in Fine Timing Measurement (FTM) may be utilized to measure the round-trip time between stations, and the communication quality may be measured based on that round-trip time. FTM involves transmitting a Fine Timing Measurement Request frame from one STA, which is the initiator, to another STA (responder), and receiving a Fine Timing Measurement Response frame returned from the responder STA that has received the Fine Timing Measurement Request frame.At this time, the round-trip time can be obtained from the timing when the Fine Timing Measurement Request frame was transmitted and the timing when the Fine Timing Measurement Response frame was received. This FTM is specified in the IEEE 802.11-2020 specification, and this mechanism can be used. However, if a mechanism that can measure a more accurate round-trip time is specified in the future, that mechanism may also be used.

[0124] There are various methods for setting the required communication quality. As an example, when a certain communication quality is specified, if the period associated with the communication quality shown above is shorter than the period corresponding to the specified communication quality, it may be considered that the communication quality is satisfied. Also, not only one communication quality can be specified, but a plurality of communication qualities can be specified so that at least any one of them can be specified. As an example, a round-trip time of 2 milliseconds or less can be set as the communication quality for time synchronization, a round-trip time of 5 milliseconds or less can be set as the communication quality for real-time sensing, and a round-trip time of 10 milliseconds or less can be set for real-time video transmission. A plurality of communication qualities may be set in this way. Also, instead of the round-trip time, it may be set based on other time indicators such as the period from the time when the MPDU is generated to the time when it is actually transmitted as a wireless frame, or the period from the time when the MPDU is generated at one station device to the time when a wireless frame including an acknowledgment response is received.

[0125] Alternatively, the link quality measurement may be performed using the CCA (Clear Channel Assessment) function of the wireless link. As an example, in a certain wireless link, the received power is measured for a predetermined time, and the communication quality may be measured using at least one of the periods during which the CCA function determines the wireless link to be Busy and the periods during which it is determined to be Idle within the predetermined time. The time for measuring the communication quality is not limited to a fixed period and may be variable, and the communication quality may be measured based on the ratio of the time determined to be Busy or the ratio of the time determined to be Idle. As an example, when the ratio of the time that a certain wireless link is Idle exceeds 50%, the communication quality for transmitting Ultra High Definition (UHD) images, and when the ratio of the time that it is Busy is 20% or less, the communication quality for real-time sensing may be defined as such.

[0126] Alternatively, the link quality measurement may be performed by transmitting a sounding frame on the wireless link and receiving a sounding report for the sounding frame. The sounding report may be received by including NDP and NDP announcement in the sounding frame. The sounding report may be received in the form of a beamforming report, or may be received in the form of received power, path loss, channel information (Channel State Information), etc. The station device that has received the report may measure whether the wireless link meets a predetermined quality based on whether the reported received power exceeds a predetermined threshold. This threshold is not limited to one, and multiple thresholds may be used to represent the communication quality in multiple levels.

[0127] The communication quality setting may be expressed by one indicator or a combination of multiple indicators. As an example, the communication quality for real-time sensing may be that the round-trip time is 5 milliseconds or less and the ratio of the wireless link being idle is 50% or more. The wireless quality for UHD video transmission may be expressed using multiple indicators such as the round-trip time is 10 milliseconds or less, the ratio of the wireless link being busy is 20% or more, and the received power is -70 dBm or more. It is also possible to ensure the wireless medium when at least any one of these one or more indicators is satisfied.

[0128] 11002 is a message including link quality setting response information. When STA1 accepts the communication quality specified in the link quality setting request information, accept is included in the link setting response information. When STA1 does not accept the communication quality specified in the link quality setting request information, deny or reject is included in the link setting response information and is sent from STA1 to STA2. When STA1 sends the link quality setting response information including accept, if STA1 requires a different link quality instead of the link quality specified by STA2, a message 11002 including the link quality setting response information with information indicating the link quality required by STA1 attached to accept may be sent from STA1 to STA2. Also, when sending a message including the link quality setting response information including deny or reject, STA1 may send it to STA2 including information indicating the reason, such as a reason code. Hereinafter, the explanation will proceed on the premise that STA1 accepts the quality information specified in the link quality setting request information and sends the link setting response information including accept from STA1 to STA2.

[0129] STA1, which has sent the link setting response information including accept to STA2, starts measuring the quality of the wireless link using Band1 and the wireless link using Band2. Hereinafter, the case of using the sounding frame as the method for measuring the wireless link will be described, but it is not limited thereto, and other methods for measuring the wireless link may be used, or the measurement using the sounding frame and other methods for measuring the quality of the wireless link may be used in combination. STA1 transmits the sounding frame 11003 to STA2 on Band1. STA2, which has received the sounding frame 11003 on Band1, transmits the sounding report 11004 to STA1 on Band1. Also, before and after transmitting the sounding frame 11003, STA1 transmits the sounding frame 11005 to STA2 on Band2. STA2, which has received the sounding frame 11005 on Band2, transmits the sounding response frame 11006 to STA1 on Band2. In FIG. 11, it is described that after STA1 transmits the sounding frame 11003 on Band1, STA1 transmits the sounding frame 11005 on Band2, but it is not limited thereto. STA1 may transmit the sounding frame 11005 on Band2 before transmitting the sounding frame 11003 on Band1, or STA1 may transmit the sounding frame 11003 on Band1 and the sounding frame 11005 on Band2 simultaneously. STA1 obtains information regarding the received power of Band1 and information regarding the received power of Band2 from the received sounding reports 11004 and 11006, and measures the communication quality of Band1 and the communication quality of Band2. As an example of measuring the communication quality, it may be determined whether the received power of Band1 or the received power of Band2 exceeds the received power set as the link quality, and the band that exceeds may be determined to satisfy the set link quality.

[0130] STA1 periodically measures the link quality on Band1 and Band2. In Figure 11, STA1 transmits sounding frames 11007 and 11013 on Band1, and also transmits sounding frames 11009 and 11015 on Band2. STA1 receives sounding reports 11008 and 11014 on Band1, and receives sounding reports 11010 and 11016 on Band2. When a transmission request occurs in a state where it is determined that the link quality of Band1 meets the set communication quality as a result of STA1 transmitting sounding frames 11007 and 11009 to measure the link quality, STA1 attempts to secure the wireless medium on Band1 11011. If the wireless medium can be secured on Band1, STA1 transmits a data frame 11012 to STA2. As a modification, when neither Band1 nor Band2 meets the communication quality set when STA1 measures the communication quality, a band with better communication quality may be selected. Next, when a transmission request occurs in a state where it is determined that the link quality of Band2 meets the set communication quality as a result of STA1 transmitting sounding frames 11013 and 11015 to measure the link quality, STA1 attempts to secure the wireless medium on Band2 11017. If the wireless medium can be secured on Band2, STA1 transmits a data frame 11018 to STA2.

[0131] The management of the measurement interval of link quality may utilize one or more timers as described above. As an example, it includes a first timer corresponding to Band1 and a second timer corresponding to Band2. After receiving the link quality setting request 11001, the first timer and the second timer are started. When the first timer expires, a sounding frame 11003 is transmitted on Band1 and the first timer is reset. When the second timer expires, a sounding frame 11005 is transmitted on Band2 and the second timer is reset. When a sounding frame 11007 is transmitted on Band1 before the first timer expires, the first timer is reset. When a sounding frame 11009 is transmitted on Band2 before the second timer expires, the second timer is reset. Instead of transmitting the sounding frame, link quality may be measured by other methods. For example, a frame for round-trip measurement, such as a Fine Timing Measurement request frame, may be transmitted to measure the link quality.

[0132] When communication for setting the communication quality between STA1 and STA2 is no longer required, the communication quality setting may be cancelled. In FIG. 11, STA2 transmits a communication quality setting cancellation request 11019 to STA1 on Band1. Upon receiving it, STA1 transmits a communication setting cancellation response 11020 to STA2 on Band1 to cancel the communication quality setting between STA1 and STA2. The band for transmitting the communication quality setting cancellation request 11019 and the communication setting cancellation response 11020 is not limited to Band1 and may also be Band2. Also, the communication quality setting cancellation request 11019 and the communication setting cancellation response 11020 may be transmitted on different bands. Further, the station device that transmits the communication quality setting cancellation request 11019 is not limited to STA2. The communication quality setting may be cancelled by transmitting the communication quality setting cancellation request 11019 from STA1.

[0133] Next, as a modified example, the case where the communication quality between STA1 and STA2 is set via the AP will be described with reference to FIG. 12. The same numbers as those in FIG. 11 are assigned to the common messages and the like, and the description thereof will be omitted. FIG. 12 shows an example of the case where STA2 sets the communication quality with STA1 via the AP. 12001 is a communication quality setting request that STA2 transmits to the AP using Band1, and this communication quality setting request includes information indicating that it is a communication quality setting between STA1 and STA2. The AP that has received the communication quality setting request 12001 transmits a communication quality setting request 12002 to STA1 on Band1. The communication quality setting request 12002 includes information indicating that it is a communication quality setting between STA1 and STA2. STA1 that has received the communication quality setting request 12002 transmits a communication quality setting response 12003 to the AP on Band1. This communication quality setting response 12003 includes information on the communication quality setting between STA1 and STA2, and also includes information on the response to the communication quality setting request (accept, deny, reject, reason code, etc.). The AP that has received the communication quality setting response 12003 transmits a communication quality setting response 12004 to STA2 on Band1. This communication quality setting response 12004 includes information on the communication quality setting between STA1 and STA2, and also includes information on the response to the communication quality setting request (accept, deny, reject, reason code, etc.). The communication quality can be set by the above procedure. The transmission and reception of messages for setting the communication quality may use not only Band1 but also Band2, or different bands may be used between STA1-AP and STA2-AP.

[0134] Next, the flow when canceling the communication quality setting will be described. STA2 sends a communication quality setting cancellation request 12005 to the AP on Band2. This communication quality setting cancellation request 12005 contains information for requesting the cancellation of the communication quality setting between STA1 and STA2. The AP that has received the communication quality setting cancellation request 12005 sends a communication quality setting cancellation request 12006 to STA1 using Band2. This communication quality setting cancellation request 12006 contains information for requesting the cancellation of the communication quality setting between STA1 and STA2. STA1 that has received the communication quality setting cancellation request 12006 sends a communication quality setting cancellation response 12007 to the AP using Band2. This communication quality setting cancellation response 12007 contains information for confirming the cancellation of the communication quality setting between STA1 and STA2. The AP that has received the communication quality setting cancellation response 12007 sends a communication quality setting cancellation response 12008 to STA2 using Band2. This communication quality setting cancellation response 12008 contains information for confirming the cancellation of the communication quality setting between STA1 and STA2. The cancellation of the communication quality setting can be achieved through the above procedure. The sending and receiving of messages for canceling the communication quality may use not only Band2 but also Band1, and different bands may be used between STA1-AP and STA2-AP.

[0135] So far, an example has been shown where two wireless links (bands) are used and an attempt is made to secure a wireless medium using one of the bands. However, the system may be configured to attempt this using one or more bands out of three or more bands, not limited to this. For example, if there are two wireless links (bands that meet the set communication quality) out of three bands that meet the set communication quality, an attempt may be made to secure the wireless medium using each of the two bands. If the attempt to secure the wireless medium is successful using the two bands, data frames may be transmitted using both of the two bands. The payloads of the data frames transmitted using the two bands may include the same data, or may include data frames with different payloads. When transmitting payloads containing the same data using two bands, reliability can be improved, and when transmitting payloads containing different data using two bands, the communication speed can be improved.

[0136] As described above, by setting the communication quality between STA1 and STA2, measuring the quality of multiple wireless links, and controlling to attempt to acquire the wireless medium using a wireless link that meets the communication quality, it becomes possible to improve the communication efficiency. [2. Common to all embodiments]

[0137] The communication device according to the present invention can communicate in a frequency band (frequency spectrum) called an unlicensed band that does not require permission from a country or region, but the available frequency band is not limited to this. The communication device according to the present invention can also exhibit its effect, for example, in a frequency band called a white band that is not actually used for the purpose of preventing interference between frequencies, even though permission to use a specific service has been granted by a country or region (for example, a frequency band assigned for television broadcasting but not used in some regions), or in a shared spectrum (shared frequency band) that is expected to be shared by multiple operators.

[0138] The program operating in the wireless communication device according to the present invention is a program (a program that functions a computer) for controlling a CPU or the like so as to realize the functions of the above-described embodiment related to the present invention. Information handled by these devices is temporarily stored in the RAM during its processing, and then stored in various ROMs and HDDs, and is read out by the CPU as needed for correction and writing. As a recording medium for storing the program, any of a semiconductor medium (e.g., ROM, non-volatile memory card, etc.), an optical recording medium (e.g., DVD, MO, MD, CD, BD, etc.), a magnetic recording medium (e.g., magnetic tape, flexible disk, etc.) may be used. Further, by executing the loaded program, not only the functions of the above-described embodiment are realized, but also the functions of the present invention may be realized by jointly processing with an operating system or other application programs based on the instructions of the program.

[0139] When distributing it on the market, the program can be stored in a portable recording medium for distribution, or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer is also included in the present invention. Further, a part or all of the communication device in the above-described embodiment may typically be realized as an LSI which is an integrated circuit. Each functional block of the communication device may be individually chipized, or a part or all of them may be integrated and chipized. When each functional block is integrated into an integrated circuit, an integrated circuit control unit for controlling them is added. Needless to say, the present invention also includes the case where a program and setting information are downloaded from a server computer in order to implement at least a part of the functions of the above-described embodiment.

[0140] Further, the method of integrating into an integrated circuit is not limited to LSI and may be realized by a dedicated circuit or a general-purpose processor. Also, when an integrated circuit technology replacing LSI appears due to the progress of semiconductor technology, it is also possible to use an integrated circuit by such technology.

[0141] Note that the invention of the present application is not limited to the above-described embodiments. The wireless communication device of the present invention is not limited to being applied to a mobile station device, and can be applied to stationary or non-mobile electronic devices installed indoors or outdoors, such as AV devices, kitchen devices, cleaning and washing devices, air conditioning devices, office devices, vending machines, and other household devices.

[0142] As described above, the embodiments of this invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and designs within the scope not departing from the gist of this invention are also included in the claims.

Industrial Applicability

[0143] The present invention is suitable for use in a wireless communication device and a wireless communication method.

Explanation of Signs

[0144] 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 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 Sub-access point device 10001-2 Sub-access point device 10002 MLD station device 10002-1 Sub-station device 10002-2 Sub-station device 10003-1 First wireless link 10003-2 Second wireless link 10011 Multi-link control unit 10012 Multi-link control unit

Claims

1. A station device that communicates with other station devices using a plurality of wireless links including a first wireless link and a second wireless link, comprising a wireless communication unit that receives and transmits wireless frames over the plurality of wireless links, and a wireless control unit, wherein the wireless communication unit receives first control information for setting communication quality regarding communication with the other station devices, the first control information including information indicating the first wireless link and the second wireless link, the wireless control unit measures the quality of the wireless links in the first wireless link and the second wireless link using the wireless communication unit, and attempts to acquire a transmission opportunity based on the first control information in at least one of the first wireless link and the second wireless link.

2. The station device according to claim 1, wherein the quality measurement of the wireless link is performed based on a first time and a second time, the first time being the time when the transmission of the MPDU is ready.

3. The station device according to claim 2, wherein the second time is the time when the MPDU is actually transmitted.

4. The station device according to claim 2, wherein the second time is the time when a response MPDU to the transmission of the MPDU is received.

5. The station device according to claim 2, wherein the measurements of the first time and the second time are performed separately for the first wireless link and the second wireless link.

6. The station device according to claim 1, wherein, when measuring the quality of the wireless link, a quality index of the wireless link is determined based on a ratio of the time during which the CCA is idle within a predetermined time period.

7. The station device according to claim 2, wherein the wireless control unit includes a first timer corresponding to the first wireless link and a second timer corresponding to the second wireless link, starts the first timer and the second timer after receiving the first control information, and transmits the MPDU over the first wireless link and resets the first timer when the first timer expires. When the second timer expires, transmit the MPDU via the second wireless link and reset the second timer. When the MPDU is transmitted via the first wireless link before the expiration of the first timer, reset the first timer. A station device, characterized in that when the MPDU is transmitted via the second wireless link before the expiration of the second timer, the second timer is reset.

8. An access point device that communicates with a first station device and a second station device, comprising a wireless unit that communicates with the first station device and the second station device using at least a first wireless link and a second wireless link, and a control unit, when the first station device is set to communicate directly with the second station device, transmit first control information to the first station device, The first control information includes medium acquisition conditions in the first wireless link or the second wireless link. An access point device characterized by this.

9. The access point device according to claim 8, The first control information includes second control information, The second control information is information regarding a timer provided in the first station device or the second station device, and the timer is used for conditions under which the first station device or the second station device transmits an MPDU. An access point device characterized by this.

10. A wireless communication method for communicating with another station device using a plurality of wireless links including a first wireless link and a second wireless link, receiving first control information for setting communication quality regarding communication with the other station device, The first control information includes information indicating the first wireless link and the second wireless link, Performing quality measurement of the wireless link in the first wireless link and the second wireless link, A wireless communication method characterized by attempting to acquire a transmission opportunity based on the first control information on at least one of the first wireless link and the second wireless link.

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