Access point device, station device, and wireless communication method

Abstract

Provided is an integrated station device 7001 comprising a route selection unit 7002, gateway units 7003-1 to 7003-3, and sub-access point units 7004-1 to 7004-3, wherein the integrated station device 7001 is connected to an integrated station device provided with a plurality of sub-station units 7006-1 to 7006-3 through a plurality of bands, and controls bands used by traffic for an integrated station by using information on a layer 3 corresponding to each of the plurality of bands.　The present invention also includes a MAC layer unit that performs allocation control. In the allocation control, an index indicating an STA which satisfies an application request condition set from an upper layer and for which transmission is possible is stored in a list, and a wireless resource is allocated to the STA included in the list by using at least one of a plurality of frequencies.

Description

Access point device, station device and wireless communication method

[0001] The present invention relates to an access point device, a station device, and a wireless communication method. This application claims priority based on Japanese Patent Application No. 2023-202683 filed in Japan on November 30, 2023, and Japanese Patent Application No. 2023-223468 filed in Japan on December 28, 2023, the contents of which are incorporated herein by reference.

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

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

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

[0005] IEEE 802.11-19 / 0773-08-00be, Nov. 2019

[0006] In a wireless LAN using multiple links, maintaining the communication quality of wireless links by selecting multiple links is an issue in order to achieve high speed and efficient frequency utilization.

[0007] Recently, with the emergence and spread of various applications such as autonomous driving, telemedicine, and video transmission, the requirements imposed on applications are becoming increasingly diverse. In particular, with the spread of applications requiring high capacity and low latency, such as video transmission applications for AR / VR, cloud gaming, and the metaverse, it is expected that applications will be used in environments where many users are concentrated. For example, when assuming video transmission in an environment where many devices are concentrated, it is important to realize the application by selecting an appropriate frequency band according to the requirements, or by bundling multiple frequency bands to meet the requirements, so as to avoid traffic concentration on a single frequency band. In particular, in telemedicine, XR, and the like, when real-time performance is required, it is also possible to consider not assuming a send / receive buffer to reduce delay. To realize various applications, it is necessary to appropriately perform scheduling based on the application's requirements (e.g., allowable time or allowable delay time) and complete data transmission while satisfying the requirements.

[0008] In wireless LANs, maintaining the communication quality of wireless links is an issue in order to achieve high speeds and efficient frequency utilization, especially when multiple wireless links are used.

[0009] In order to solve the above-mentioned problems, an access point device, a station device, and a wireless communication method according to one aspect of the present invention are as follows.

[0010] (1) That is, an access point device according to one aspect of the present invention comprises a plurality of sub-access point units that use a plurality of different frequencies, a route selection unit that selects a frequency, and a gateway unit that controls traffic based on Layer 3 information, wherein each of the plurality of sub-access point units performs carrier sense prior to emitting radio waves, each of the sub-access point units connects to a respective sub-station unit provided in the station device, the gateway unit sets a different subnet for each of the sub-access point units, and the route selection unit selects one of the different subnets for traffic to the station device and sets the gateway unit to transmit the traffic to the station device to the sub-station unit through one of the plurality of sub-access point units to which the selected subnet is set.

[0011] (2) In addition, in an access point device according to one aspect of the present invention, the route selection unit selects one of the different subnets for traffic to the station device based on at least one of information from the layer 3 and a network controller.

[0012] (3) In addition, in an access point device according to one aspect of the present invention, the route selection unit is configured to transmit to the substation unit using at least one of the plurality of frequencies based on traffic information of the application.

[0013] (4) Furthermore, an access point device according to one aspect of the present invention configures the route selection unit to transmit to the substation unit using at least one of the multiple frequencies based on a list of indices indicating STAs that can transmit and meet application requirements set from a higher layer.

[0014] (5) In addition, an access point device according to one aspect of the present invention compares the minimum transmission rate based on the target video rate and the allowable time with the MCS rate based on the MCS (Moderation and Coding Scheme) to determine whether the application requirements are met.

[0015] (6) Furthermore, a station device according to one aspect of the present invention connects to the access point device described in (1) to (5) above and transmits information indicating application requirements to the access point device.

[0016] (A1) That is, a station device according to one embodiment of the present invention is a station device that communicates with other station devices using multiple wireless links including a first wireless link and a second wireless link, and includes a wireless communication unit that receives and transmits wireless frames over the multiple wireless links, and a wireless control unit, wherein the wireless communication unit receives first control information that sets communication quality for communication with the other station devices, the first control information includes information indicating the first wireless link and the second wireless link, and the wireless control unit uses the wireless communication unit to measure the quality of the wireless links in the first wireless link and the second wireless link, and attempts to acquire a transmission opportunity in at least one of the first wireless link and the second wireless link based on the first control information.

[0017] (A2) Furthermore, a station device according to one embodiment of the present invention measures the quality of the wireless link based on a first time interval and a second time interval, and the first time interval is the time when an MPDU is ready to be transmitted.

[0018] (A3) In addition, in a station device according to one aspect of the present invention, the second time instant is the time when the MPDU is actually transmitted.

[0019] (A4) In a station device according to an aspect of the present invention, the second time is a time at which a response MPDU in response to transmission of the MPDU is received.

[0020] (A5) Furthermore, in a station device according to one aspect of the present invention, the first time and the second time are measured separately in the first link and the second link.

[0021] (A6) Furthermore, a station device according to one embodiment of the present invention determines a quality index for the wireless link based on the percentage of time that the CCA is idle within a specified time period when measuring the wireless link quality.

[0022] (A7) In addition, in a station device according to one embodiment of the present invention, the control unit is provided with a first timer corresponding to the first wireless link and a second timer corresponding to the second wireless link, and after receiving the first control information, starts the first timer and the second timer, and when the first timer expires, transmits the MPDU on the first wireless link and resets the first timer, and when the second timer expires, transmits the MPDU on the second wireless link and resets the second timer, and resets the first timer when the MPDU is transmitted on the first wireless link before the first timer expires, and resets the second timer when the MPDU is transmitted on the second wireless link before the second timer expires.

[0023] (A8) Furthermore, an access point device according to one aspect of the present invention includes a radio 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, and when the first station device is set to communicate directly with the second station device, it transmits first control information to the first station device, and the first control information includes medium acquisition conditions for the first wireless link or the second wireless link.

[0024] (A9) In addition, in an access point device according to one embodiment of the present invention, the first control information includes second control information, and the second control information is information relating to a timer provided in the first station device or the second station device, and the timer is used as a condition for the first station device or the second station device to transmit an MPDU.

[0025] (A10) Also, a wireless communication method according to one aspect of the present invention receives first control information that sets communication quality for communication with the other station device, the first control information includes information indicating the first wireless link and the second wireless link, measures the quality of the wireless links in the first wireless link and the second wireless link, 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.

[0026] The wireless access point device and station device of the present invention make it possible to maintain good communication quality of a wireless link in wireless communication. Also, the wireless communication device and wireless communication method of the present invention make it possible to maintain good communication quality of a wireless link in wireless communication.

[0027] 1 is a diagram showing an example of a MAC layer frame configuration in a wireless LAN system. FIG. 2 is a diagram showing an example of a PPDU configuration in a wireless LAN system. FIG. 3 is a diagram showing an example of a sounding procedure in a wireless LAN system. FIG. 4 is a diagram showing an example of a configuration of a communication system according to an aspect of the present invention. FIG. 5 is a block diagram showing an example of a configuration of a station device according to an aspect of the present invention. FIG. 6 is a block diagram showing an example of a configuration of an access point device according to an aspect of the present invention. FIG. 7 is a diagram showing an example of a configuration of a wireless communication system according to an aspect of the present invention. FIG. 8 is a diagram showing an example of a configuration of a wireless communication system according to an aspect of the present invention. FIG. 9 is a diagram showing an example of a configuration of a wireless communication system according to an aspect of the present invention. FIG. 10 is a diagram showing an example of a communication system according to an aspect of the present invention. FIG. 11 is a diagram showing an example of a communication method according to an aspect of the present invention. FIG. 12 is a diagram showing an example of a communication method according to an aspect of the present invention. FIG. 13 is a diagram showing an example of a communication method according to an aspect of the present invention. FIG. 14 is a block diagram showing an example of a configuration of a station device according to an aspect of the present invention. FIG. 15 is a block diagram showing an example of a configuration of an access point device according to an aspect of the present invention. FIG. 16 is a diagram showing an example of a sounding procedure in a wireless communication system according to an aspect of the present invention. 1 is a flowchart illustrating an example of a sounding procedure in a station device according to an embodiment of the present invention; FIG. 2 is a diagram illustrating an example of a configuration of a communication system according to an embodiment of the present invention; FIG. 3 is a diagram illustrating a message flow of a communication system according to an embodiment of the present invention;

[0028] The wireless communication system in this embodiment includes an access point device (also referred to as an AP or base station device) and multiple station devices (also referred to as STAs or terminal devices). The communication system and network configured with the access point device and the station devices are referred to as a basic service set (BSS, management range). The station device according to this embodiment can have the functions of an access point device. Similarly, the access point device according to this embodiment can have the functions of a station device. Therefore, hereinafter, when simply referring to a communication device or a wireless communication device, the communication device or wireless communication device can refer to both the access point device and the station device.

[0029] The access point device and station devices within the BSS communicate based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance). This embodiment focuses on infrastructure mode, in which an access point device communicates with multiple station devices. However, the method of this embodiment can also be implemented in ad hoc mode, in which station devices communicate directly with each other. In ad hoc mode, a single station device acts as an access point device to form a BSS. A BSS in ad hoc mode is also referred to as an IBSS (Independent Basic Service Set). Hereinafter, a station device forming an IBSS in ad hoc mode can also be considered an access point device. The method of this embodiment can also be implemented in Wi-Fi Direct (registered trademark), in which station devices communicate directly with each other. In Wi-Fi Direct, one station device acts as an access point device to form a group. This station device is called a group owner and can also be considered an access point device.

[0030] In the IEEE 802.11 system, each device can transmit multiple types of frames (communication frames) with a common frame format, which are defined in the physical (PHY) layer, medium access control (MAC) layer, and logical link control (LLC) layer.

[0031] A PHY layer frame is called a physical protocol data unit (PPDU, PHY layer frame). A PPDU is composed of a physical layer header (PHY header) containing information for signal processing in the physical layer, and a physical service data unit (PSDU, PHY service data unit), which is a data unit processed in the physical layer. A PSDU can be composed of an aggregated MPDU (A-MPDU), which aggregates multiple MAC protocol data units (MPDU, MAC layer frames), which serve as retransmission units in wireless sections.

[0032] The PHY header includes reference signals such as a short training field (STF) used for signal detection and synchronization, and a long training field (LTF) used to acquire channel information for data demodulation, as well as control signals such as a signal (SIG) containing control information for data demodulation. Furthermore, STF is classified into Legacy-STF (L-STF), High Throughput-STF (HT-STF), Very High Throughput-STF (VHT-STF), High Efficiency-STF (HE-STF), Extremely High Throughput-STF (EHT-STF), etc. depending on the corresponding standard, and LTF and SIG are similarly classified into L-LTF, HT-LTF, VHT-LTF, HE-LTF, L-SIG, HT-SIG, VHT-SIG, HE-SIG, and EHT-SIG. VHT-SIG is further classified into VHT-SIG-A1, VHT-SIG-A2, and VHT-SIG-B. Similarly, HE-SIG is classified into HE-SIG-A1 to HE-SIG-A4 and HE-SIG-B. In addition, a Universal SIGNAL (U-SIG) field containing additional control information may be included, assuming technology updates within the same standard.

[0033] Furthermore, the PHY header can include information for identifying the BSS that is the sender of the frame (hereinafter also referred to as BSS identification information). The information for identifying the BSS can be, for example, the SSID (Service Set IDentifier) ​​of the BSS or the MAC address of the access point device of the BSS. The information for identifying the BSS can also be a value unique to the BSS (for example, a BSS Color) other than the SSID or MAC address. Information indicating the BSS Color can be included in the HE-SIG-A or U-SIG.

[0034] 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.

[0035] An MPDU consists of a MAC header containing information for signal processing at the MAC layer, a MAC Service Data Unit (MSDU) or frame body, which is a data unit processed at the MAC layer, and a Frame Check Sequence (FCS), which checks whether the frame is error-free (see Figure 1). Multiple MSDUs can also be aggregated as an Aggregated MSDU (A-MSDU).

[0036] Frame types in the MAC layer are broadly classified into three types: management frames that manage the connection status between devices, control frames that manage the communication status between devices, and data frames that contain actual transmission data. Each type is further classified into multiple subframe types. Control frames include acknowledgement (Ack or ACK) frames, block acknowledgement (BA or BlockAck) frames, request to send (RTS) frames, and clear to send (CTS) frames. BlockAck can acknowledge (notify completion of reception) multiple MPDUs. Management frames include beacon frames, probe request frames, probe response frames, authentication frames, association request frames, and association response frames. Data frames include data frames and polling (CF-poll) frames. Each device can recognize the frame type and subframe type of a received frame by reading the contents of the frame control field included in the MAC header.

[0037] A beacon frame includes a field indicating the period (beacon interval) at which the beacon is transmitted and the SSID. An access point device can periodically broadcast a beacon frame within a BSS, and a station device can recognize surrounding access point devices by receiving the beacon frame. The act of a station device recognizing an access point device based on a beacon frame broadcast by an access point device is called passive scanning. On the other hand, the act of a station device searching for an access point device by broadcasting a probe request frame within a BSS is called active scanning. An access point device can transmit a probe response frame in response to the probe request frame, and the content of the probe response frame is the same as the content of the beacon frame.

[0038] After recognizing an access point device, a station device performs a connection process with the access point device. The connection process is classified into an authentication procedure and an association procedure. The station device transmits an authentication request frame to the access point device with which it wishes to connect. Upon receiving the authentication request frame, the access point device transmits an authentication response frame to the station device, the authentication response frame including a status code indicating whether the station device has been authenticated. The station device can determine whether its authentication request has been approved by the access point device by reading the status code included in the authentication response frame. The access point device and station device can exchange authentication request frames and authentication response frames (both of which are collectively referred to as authentication frames) multiple times.

[0039] Following the authentication procedure, the station device transmits a connection request frame to the access point device to perform a connection procedure. Upon receiving the connection request frame, the access point device determines whether to permit the connection of the station device and transmits a connection response frame to notify the determination. The connection response frame contains a status code indicating whether the connection process is successful, as well as an association identifier (AID) for identifying the station device. The access point device can manage multiple station devices by setting different AIDs for each station device to which it has issued connection permission.

[0040] After the connection process is completed, the access point device and the station device perform actual data transmission. In the IEEE 802.11 system, the Distributed Coordination Function (DCF), the Point Coordination Function (PCF), and their extended Hybrid Coordination Function (HCF) are defined as media access methods. Specific implementation methods of the HCF include Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA).

[0041] First, an example of the operation when an access point device transmits a signal to a station device based on DCF will be described. In DCF, the access point device and the station device perform carrier sense (CS) to check the usage status of the wireless channel around the device before communication. For example, if an access point device or a station device that is about to transmit a frame receives a signal with a received power higher than a predetermined clear channel assessment level (CCA level) on the wireless channel during the carrier sense period performed prior to transmission, the access point device or the station device postpones the transmission of the frame on the wireless channel. Hereinafter, a state in which a signal with a received power equal to or higher than the CCA level is detected on the wireless channel is referred to as a busy state, and a state in which a signal with a received power equal to or higher than the CCA level is not detected is referred to as an idle state. In this way, CS performed by each device based on the power level of the signal actually received is referred to as physical carrier sense (physical CS). The CCA level is also referred to as the carrier sense level (CS level) or the CCA threshold (CCAT). When the access point device and station device detect a signal with a reception power equal to or higher than the CCA level, they begin to demodulate at least the PHY layer signal.

[0042] An access point device performs carrier sensing during an interframe space (IFS) period set according to the type of frame to be transmitted, and determines whether the wireless channel is busy or idle. The period during which the access point device performs carrier sensing varies depending on the frame type and subframe type of the frame to be transmitted. The IEEE 802.11 system defines multiple IFS periods with different periods, including a short interframe space (SIFS) used for frames assigned the highest priority, a polling interframe space (PIFS: PCF IFS) used for frames with relatively high priority, and a distributed arbitration interframe space (DIFS: DCF IFS) used for frames with low priority. When transmitting data frames using DCF, the access point device uses the DIFS.

[0043] After waiting for the DIFS period, the access point device further waits for a random backoff time to prevent frame collisions. In the IEEE 802.11 system, a random backoff time based on a contention window (CW) is used. CSMA / CA assumes that a frame transmitted by a transmitting station is received by a receiving station without interference from other transmitting stations. Therefore, if multiple transmitting stations transmit frames at the same time, the frames may collide with each other, potentially preventing the receiving station from receiving the frames correctly. Therefore, frame collisions are avoided by each transmitting station waiting for a randomly set time before starting transmission. When the access point device determines that the wireless channel is idle through carrier sense, it starts counting down a backoff counter set based on the CW. Only when the backoff counter reaches 0 can it acquire the right to transmit and transmit a frame to the station device. If the access point device determines that the wireless channel is busy through carrier sense during the backoff counter countdown, it stops counting down the backoff counter. Then, when the wireless channel becomes idle again, the access point device waits for the same period as the previous IFS, and then resumes counting down the remaining part of the previous backoff counter.

[0044] The receiving station, a station device, receives the frame, reads the PHY header of the frame, and demodulates the received frame. The station device can then determine whether the frame is addressed to itself by reading the MAC header of the demodulated signal. The station device can also determine the destination of the frame based on information contained in the PHY header (e.g., a group identification number (GID: Group ID) contained in VHT-SIG-A).

[0045] If a station device determines that a received frame is addressed to itself and demodulates the frame without error, it must transmit an Ack frame to the access point device, which is the transmitting station, indicating that the frame was received correctly. The Ack frame is one of the highest-priority frames that is transmitted after waiting only an SIFS period (without a random backoff time). The access point device terminates a series of communications upon receiving the Ack frame from the station device. If the station device fails to receive a frame correctly, it will not transmit an Ack frame. Therefore, if the access point device does not receive an Ack frame from the receiving station (station device) within a certain period (SIFS + Ack frame length) after transmitting the frame, it will determine that the communication has failed and terminate the communication. Thus, the end of a single communication (also called a burst) in an IEEE 802.11 system is always determined by whether or not an Ack frame is received, except in special cases such as when a beacon frame or other notification signal is transmitted or when fragmentation is used to divide the transmitted data.

[0046] When a station device determines that a received frame is not addressed to the station device, the station device sets a network allocation vector (NAV) based on the length of the frame included in the PHY header or the like. The station device does not attempt transmission during the period set in the NAV. In other words, the station device performs the same operation as when it determines that the wireless channel is busy by physical CS during the period set in the NAV. Therefore, communication control using NAV is also called virtual carrier sense (virtual CS). In addition to being set based on information included in the PHY header, the NAV is also set by RTS frames and CTS frames introduced to solve the hidden terminal problem.

[0047] Next, an example of the operation when an access point device transmits a signal to a station device based on PCF will be described. Unlike DCF, in which each device performs carrier sensing and autonomously acquires the transmission right, in PCF, a control station called a Point Coordinator (PC) controls the transmission right of each device within the BSS. Generally, an access point device becomes the PC and acquires the transmission right of the station device within the BSS.

[0048] The communication period by PCF includes a contention-free period (CFP) and a contention period (CP). During the CP, communication is performed based on the DCF described above, and the PC controls the transmission right during the CFP. The access point device, which is the PC, broadcasts a beacon frame including information such as the CFP duration (CFP Max duration) within the BSS prior to PCF communication. Note that the beacon frame broadcast at the start of PCF transmission uses PIFS and is transmitted without waiting for the CW. A station device that receives the beacon frame sets the CFP Max duration included in the beacon frame in its NAV. Thereafter, until the period set in the NAV elapses or a signal announcing the end of the CFP (e.g., a data frame including CF-end) is received within the BSS, the station device can acquire the transmission right only when it receives a signal signaling acquisition of the transmission right for the device from the PC (e.g., a data frame including CF-poll). During the CFP period, no packet collisions occur within the same BSS, so each station device does not take the random backoff time used in DCF.

[0049] The wireless communication device has either a function for transmitting a PPDU or a function for receiving a PPDU, or both. Fig. 2 is a diagram showing an example of the configuration of a PPDU transmitted by a wireless communication device. A PPDU conforming to the IEEE 802.11a / g standard is configured to include an L-STF, an L-LTF, an L-SIG, and a Data frame (MAC frame, payload, data section, data, information bits, etc.). A PPDU conforming to the IEEE 802.11n standard is configured to include an L-STF, an L-LTF, an L-SIG, an HT-SIG, an HT-STF, an HT-LTF, and a Data frame. A PPDU conforming to the IEEE 802.11ac standard is configured to include some or all of the following: L-STF, L-LTF, L-SIG, VHT-SIG-A, VHT-STF, VHT-LTF, VHT-SIG-B, and a Data frame. A PPDU conforming to the IEEE 802.11ax standard is configured to include some or all of the following: L-STF, L-LTF, L-SIG, RL-SIG, which is a time-repeated L-SIG, HE-SIG-A, HE-STF, HE-LTF, HE-SIG-B, and a Data frame. The PPDU being considered for the IEEE 802.11be standardization is a structure that includes some or all of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, HET-LTF, and Data frames.

[0050] The L-STF, L-LTF, and L-SIG enclosed by dotted lines in Figure 2 are structures commonly used in the IEEE 802.11 standard (hereinafter, L-STF, L-LTF, and L-SIG are also collectively referred to as the L-header). For example, a wireless communication device compatible with the IEEE 802.11a / g standard can properly receive an L-header in a PPDU compatible with the IEEE 802.11n / ac / ax / be standard. A wireless communication device compatible with the IEEE 802.11a / g standard can receive a PPDU compatible with the IEEE 802.11n / ac / ax / be standard as a PPDU compatible with the IEEE 802.11a / g standard.

[0051] However, wireless communication devices that comply with the IEEE 802.11a / g standards cannot demodulate PPDUs that comply with the IEEE 802.11n / ac / ax / be standards that follow the L-header, and therefore cannot demodulate information related to the transmitter address (TA), receiver address (RA), duration / ID field, etc.

[0052] IEEE 802.11 specifies a method of inserting Duration information into L-SIG as a method for a wireless communication device conforming to the IEEE 802.11a / g standard to appropriately set NAV (or perform reception operation for a predetermined period of time). Information on the transmission rate in the L-SIG (RATE field, L-RATE field, L-RATE, L_DATARATE, L_DATARATE field) and information on the transmission period (LENGTH field, L-LENGTH field, L-LENGTH) are used by a wireless communication device conforming to the IEEE 802.11a / g standard to appropriately set NAV.

[0053] The wireless communication device can transmit the L-SIG multiple times (L-SIG Repetition). In this case, the receiving wireless communication device can improve the demodulation accuracy of the L-SIG by receiving the L-SIG transmitted multiple times using maximal ratio combining (MRC), for example. Furthermore, when the wireless communication device has correctly received the L-SIG using MRC, it can interpret the PPDU including the L-SIG as a PPDU that complies with the IEEE 802.11ax or IEEE 802.11be standard.

[0054] Even during a PPDU reception operation, the wireless communication device can perform a reception operation of a part of a PPDU other than the PPDU (for example, a preamble, L-STF, L-LTF, PHY header, etc., as defined by IEEE 802.11) (also referred to as a dual reception operation). When the wireless communication device detects a part of a PPDU other than the PPDU during a PPDU reception operation, the wireless communication device can update some or all of the information related to the destination address, source address, PPDU, or Data period.

[0055] Ack and BA can also be called responses (response frames). Also, probe responses, authentication responses, and connection responses can also be called responses.

[0056] Fig. 3 is a diagram showing an example of a sounding procedure for the purpose of channel estimation of a wireless communication path in IEEE 802.11ax. In the example shown in Fig. 3, an access point device (AP) first transmits a Null Data PPDU (NDP) Announcement frame 3001 that specifies information indicating a station device (STA) that will be the target of the upcoming sounding (the receiver of the sounding frame) and the type of feedback information. The access point device then transmits an NDP frame 3002 including a training field for channel estimation SIFS after the NDP Announcement frame. The station device performs channel estimation based on the received NDP frame 3002, and transmits a frame, such as a Compressed Beamforming / CQI frame 3003, that feeds back the channel estimation result to the access point device SIFS after the NDP frame 3002. [1. First Embodiment]

[0057] FIG. 4 is a diagram showing an example of a wireless communication system according to this embodiment. Wireless communication system 4003-1 includes wireless communication device 4001-1 and wireless communication devices 4002-1 to 4002-3. Wireless communication device 4001-1 is also referred to as access point device 4001-1, and wireless communication devices 4002-1 to 4002-3 are also referred to as station devices 4002-1 to 3. Wireless communication devices 4002-1 to 4002-3 (station devices 4002-1 to 4002-3) are also referred to as wireless communication device 4002A (station device 4002A) as devices connected to wireless communication device 4001-1. Wireless communication device 4001-1 and wireless communication device 4002A are wirelessly connected and are capable of transmitting and receiving PPDUs to and from each other. The wireless communication system according to this embodiment may also include wireless communication system 4003-2 in addition to wireless communication system 4003-1. Wireless communication system 4003-2 includes wireless communication device 4001-2 and wireless communication devices 4002-4 to 4002-6. Wireless communication device 4001-2 is also referred to as access point device 4001-2, and wireless communication devices 4002-4 to 4002-6 are also referred to as station devices 4002-4 to 4002-6. Wireless communication devices 4002-4 to 4002-6 (station devices 4002-4 to 4002-6) are also referred to as wireless communication device 4002B (station device 4002B) as devices connected to wireless communication device 4001-2. Furthermore, when wireless communication device 4001-1 and wireless communication device 4001-2 (access point devices 4001-1, 4001-6) are described without specifying each other, they are also referred to as wireless communication device 4001 (access point device 4001), and when wireless communication devices 4002-1 to 4002-6 (station devices 4002-1 to 4002-6) are described without specifying each other, they are also referred to as wireless communication device 4002 (station device 4002). Wireless communication system 4003-1 and wireless communication system 4003-2 form different BSSs, but this does not necessarily mean that the ESSs (Extended Service Sets) representing service sets forming LANs (Local Area Networks) are different.In other words, wireless communication devices belonging to the same ESS can be regarded as belonging to the same network from a higher layer. Furthermore, BSSs are connected via a DS (Distribution System) to form an ESS. Note that each of the wireless communication systems 4003-1 and 4003-2 can also include multiple wireless communication devices.

[0058] 5 is a diagram showing an example of the configuration of station device 4002. Station device 4002 includes a wireless control unit (wireless control step) 5001, a wireless communication unit (wireless communication step) 5003, and an antenna unit 5004. Furthermore, wireless communication unit 5003 includes a physical layer frame generation unit (physical layer frame generation step) 5003a, a wireless transmission unit (wireless transmission step) 5003b, a wireless reception unit (wireless reception step) 5003c, a received power measurement unit (received power measurement step) 5003d, a channel estimation unit (channel estimation step) 5003e, and a signal demodulation unit (signal demodulation step) 5003f.

[0059] The wireless control unit 5001 performs information processing on layers higher than the physical layer, such as the MAC layer and LLC layer, for information handled within the wireless communication device itself (such as information related to frames to be transmitted and MIB (Management Information Base)) and frames received from other wireless communication devices, and also controls the wireless communication unit 5003.

[0060] The physical layer frame generation unit 5003a has a function of generating a physical layer frame (PPDU). The physical layer frame generation unit 5003a performs error correction coding, modulation, beamforming processing (precoding processing), etc. on the MAC layer frame sent from the wireless control unit 5001. The beamforming processing may be realized by multiplying the modulated signal by a beamforming matrix (beamforming filter) notified by the wireless control unit 5001. The physical layer frame generation unit 5003a outputs the generated physical layer frame to the wireless transmission unit 5003b.

[0061] The wireless transmitting unit 5003b converts the physical layer frame input from the physical frame generating unit 5003a into a radio frequency (RF) band signal to generate a wireless signal. The processing performed by the wireless transmitting unit 5003b includes digital-to-analog conversion, filtering, frequency conversion from baseband frequency to wireless frequency, etc. The wireless transmitting unit 5003b transmits the generated wireless signal via the antenna unit 5004.

[0062] The wireless receiving unit 5003c has a function of converting a wireless signal received via the antenna unit 5004 into a baseband signal and generating a physical layer signal (for example, a physical layer frame). The processing performed by the wireless receiving unit 5003c includes frequency conversion processing from a wireless frequency to a baseband frequency, filtering, analog-to-digital conversion, etc. The physical layer signal, which is the received signal converted into a digital signal by the wireless receiving unit 5003c, is input to the received power measuring unit 5003b, the channel estimating unit 5003e, and the signal demodulating unit 5003f.

[0063] The received power measurement unit 5003d measures the received power of the received signal input from the wireless receiving unit 5003c. The received power measurement unit 5003d can measure the received power of the radio wave received on the frequency channel to be measured, the received power of the LTF of the received physical layer frame, etc. The received power measurement unit 5003d can notify the wireless control unit 5001 of the measurement result of the received power.

[0064] The channel estimation unit 5003e estimates the channel state through which the physical layer frame has propagated, based on the received signal of the LTF (L-LTF, HT-LTF, VHT-LTF, HE-LTF, etc.) included in the physical layer frame received by the wireless receiving unit 5003c. The channel estimation unit 5003e can notify the signal demodulation unit 5003f and the wireless control unit 5001 of the channel estimation result.

[0065] The signal demodulation unit 5003f performs channel equalization, demodulation, error correction decoding, etc. on the physical layer frame received by the wireless receiving unit 5003c, and acquires information such as the PHY header and MAC layer frame. The channel equalization process can use the channel estimation results of the channel estimator 5003e, etc. The signal demodulation unit 5003f outputs the acquired PHY header and MAC layer frame to the wireless control unit 5001.

[0066] The wireless control unit 5001 can perform physical carrier sensing and virtual carrier sensing based on the received power measurement results in the received power measuring unit 5003 d and information acquired in the signal demodulation unit 5003 f, and can determine the state of the wireless channel (including determining whether it is in an idle state or a busy state). The wireless control unit 5001 can notify the wireless communication unit 5003 of this wireless channel state determination information.

[0067] When there is control information, data, etc. to be transmitted, the wireless control unit 5001 can start a backoff procedure using the wireless channel state determination information. The wireless control unit 5001 generates a backoff counter based on the CW and has a countdown function for the backoff counter. For example, the wireless control unit 5001 can count down the backoff counter when the wireless channel state determination information indicates an idle state, and can stop the countdown of the backoff counter when the wireless channel state determination information indicates a busy state. Furthermore, the wireless control unit 5001 makes a transmission decision using either the wireless channel state determination information or the backoff counter value, or both. For example, the wireless control unit 5001 can notify the wireless communication unit 5003 of transmission decision information when the wireless channel state determination information indicates an idle state and the backoff counter value is 0. Furthermore, the wireless control unit 5001 can notify the wireless communication unit 5003 of transmission decision information when the wireless resource state determination information indicates an idle state.

[0068] FIG. 6 shows an example of the configuration of an access point device 4001. The access point device 4001 includes a wireless control unit (wireless control step) 6001, a wireless communication unit (wireless communication step) 5003, and an antenna unit 5004. Furthermore, the wireless communication unit 5003 includes a physical layer frame generation unit (physical layer frame generation step) 5003a, a wireless transmission unit (wireless transmission step) 5003b, a wireless reception unit (wireless reception step) 5003c, a received power measurement unit (received power measurement step) 5003d, a channel estimation unit (channel estimation step) 5003e, and a signal demodulation unit (signal demodulation step) 5003f. The access point device 4001 of FIG. 6 is basically configured similarly to the station device 4002 of FIG. 5. Therefore, the following description will focus on the differences between the two, and will omit a description of similar parts. Furthermore, parts corresponding to those in the station device of FIG. 5 will be described using the same reference numerals.

[0069] The wireless control unit 6001 processes information handled within the wireless communication device (such as information related to frames to be transmitted and MIB (Management Information Base)) and frames received from other wireless communication devices at layers higher than the physical layer, such as the MAC layer and LLC layer, and also controls the wireless communication unit 5003.

[0070] The physical layer frame generation unit 5003a has a function of generating a physical layer frame (PPDU). The physical layer frame generation unit 5003a performs error correction coding, modulation, beamforming processing (precoding processing), etc. on the MAC layer frame sent from the wireless control unit 6001. The beamforming processing may be realized by multiplying the modulated signal by a beamforming matrix (beamforming filter) notified by the wireless control unit 6001. The physical layer frame generation unit 5003a outputs the generated physical layer frame to the wireless transmission unit 5003b.

[0071] The received power measurement unit 5003d measures the received power of the received signal input from the wireless receiving unit 5003c. The received power measurement unit 5003d can measure the received power of the radio wave received on the frequency channel to be measured, the received power of the LTF (L-LTF, HT-LTF, VHT-LTF, HE-LTF, etc.) of the received physical layer frame, etc. The received power measurement unit 5003d can notify the wireless control unit 6001 of the measurement result of the received power.

[0072] The channel estimation unit 5003e estimates the channel state through which the physical layer frame has propagated, based on the LTF received signal included in the physical layer frame received by the wireless receiving unit 5003c. The channel estimation unit 5003e can notify the signal demodulation unit 5003f and the wireless control unit 6001 of the channel estimation result.

[0073] The signal demodulation unit 5003f performs channel equalization, demodulation, error correction decoding, etc. on the physical layer frame received by the wireless receiving unit 5003c, and acquires information such as the PHY header and MAC layer frame. The channel equalization process can use the channel estimation results of the channel estimator 5003e, etc. The signal demodulation unit 5003f outputs the acquired PHY header and MAC layer frame to the wireless control unit 6001.

[0074] When there is control information, data, a beacon, or the like to be transmitted, the wireless control unit 6001 can start a backoff procedure using the wireless channel state determination information. The wireless control unit 6001 generates a backoff counter based on the CW and has a countdown function for the backoff counter. For example, the wireless control unit 6001 can count down the backoff counter when the wireless channel state determination information indicates an idle state, and can stop the backoff counter countdown when the wireless channel state determination information indicates a busy state. Furthermore, the wireless control unit 6001 makes a transmission decision using either the wireless channel state determination information or the backoff counter value, or both. For example, the wireless control unit 6001 can notify the wireless communication unit 5003 of transmission decision information when the wireless channel state determination information indicates an idle state and the backoff counter value is 0. Furthermore, the wireless control unit 6001 can notify the wireless communication unit 5003 of transmission decision information when the wireless resource state determination information indicates an idle state.

[0075] 7 is a diagram showing one aspect of the configuration of a wireless communication system according to this embodiment. A sub-access point unit has the same function as the access point apparatus shown above, and a sub-station unit has the same function as the station apparatus. 7001 is an integrated access point apparatus, and 7005 is an integrated station apparatus.

[0076] The integrated access point device 7001 includes a route selection unit 7002, gateway units 7003-1 to 7003-3, and sub-access point units 7004-1 to 7004-4. Each sub-access point unit uses a different frequency band. In this embodiment, sub-access point unit 7004-1 corresponds to frequency band 1 (band 1), sub-access point unit 7004-2 corresponds to frequency band 2 (band 2), and sub-access point unit 7004-3 corresponds to frequency band 3 (band 3). For example, frequency band 1 may be the 2.4 GHz band, frequency band 2 may be the 5 GHz band, and frequency band 3 may be the 6 GHz band. The combination of frequency bands is not limited to this, and wireless LANs using other frequency bands such as millimeter wave bands such as 60 GHz and sub-gigahertz bands (Sub 1G), personal area networks capable of IP communication, and cellular communication systems may also be used. The number of bands used is not limited to three, as long as it is plural.

[0077] The gateway units 7003-1 to 7003-3 are connected to the sub-access point units 7004-1 to 7004-3, respectively. The gateway units 7003-1 to 7003-3 are responsible for the IP addresses / subnets used by the sub-access point units 7004-1 to 7004-3, respectively. The IP addresses / subnets used by the gateway units 7004-1 to 7004-3 are set to be different. As an example, the IP address / subnet used by the gateway unit 7003-1 may be 192.168.1.1 / 24, the IP address / subnet used by the gateway unit 7003-2 may be 192.168.2.1 / 24, and the IP address / subnet used by the gateway unit 7003-3 may be 192.168.3.1 / 24. The subnet masks used do not have to be uniform, and different subnet masks may be used. Furthermore, the IP addresses / subnets used are not limited to IPv4 and may also be IPv6, and a dual stack of IPv4 and IPv6 may also be used. The gateway units 7003-1 to 7003-3 may also have a function for allocating IP addresses / subnets used by the substation units 7006-1 to 7006-3, such as an IPv4 DHCP (Dynamic Host Configuration Protocol) server function, a function for handling IPv6 RS (Router Solicitation) and RA (Router Advertisement) messages, and a DHCPv6 (Dynamic Host Configuration Protocol for IP Version 6) server function. When allocating IP addresses / subnets to be used by the substation units 7006-1 to 7006-3, the gateway units 7003-1 to 7003-3 may refer to specific information held by the substation units 7006-1 to 7006-3, such as MAC addresses, in order to allocate the same IP addresses / subnets to the substation units 7006-1 to 7006-3 if possible.

[0078] The gateway units 7003-1 to 7003-3 are configured by the route selection unit 7002 to determine whether or not to forward identification information included in the traffic used by the integrated station device 7005, for example, IP packets addressed to a representative IP address. In other words, the gateway units 7003-1 to 7003-3 perform forwarding control using information from Layer 3. When the route selection unit 7002 determines that Band 1 should be used for traffic bound for the integrated station device 7005, it configures the gateway unit 7003-1 to forward the representative IP address used by the integrated station device 7005, and configures the gateway units 7003-2 and 7003-3 not to forward the representative IP address used by the integrated station device 7005. When the route selection unit 7002 determines that band 2 should be used for traffic destined for the integrated station device 7005, it sets the gateway unit 7003-2 to forward the representative IP address used by the integrated station device 7005, and sets the gateway units 7003-1 and 7003-3 not to forward the representative IP address used by the integrated station device 7005. When the route selection unit 7002 determines that band 3 should be used for traffic destined for the integrated station device 7005, it sets the gateway unit 7003-3 to forward the representative IP address used by the integrated station device 7005, and sets the gateway units 7003-1 and 7003-2 not to forward the representative IP address used by the integrated station device 7005. In addition, the gateway units 7003-1 to 7003-3 forward information received from the sub-access point devices 7004-1 to 7004-3 to the external network. With this configuration, the integrated access point device 7001 can set traffic destined for a specific integrated station device to use the band selected by the route selection unit 7002.

[0079] In Figure 7, the integrated access point device 7001 is configured to have one gateway unit per sub-access point unit, with each gateway unit connected to an external network. However, these multiple gateway units may be implemented as a single gateway unit with multiple network interfaces. The integrated access point device 7001 may have the same number of network interfaces as the sub-access point units, and a specific network interface may be connected only to a specific sub-access point unit, thereby linking that network interface to a specific band. The gateway may select one of the network interfaces as the forwarding destination of the representative IP address used by the integrated station device 7005, thereby selecting the band used by traffic destined for the specific integrated station device. The network interface may not be a physical interface, but may be a virtual network interface used by the OS (Operating System) used by the integrated access point device 7001.

[0080] The route selection unit 7002 selects a band to be used by traffic destined for a specific integrated station device by configuring the gateway units 7003-1 to 7003-3 using one or more pieces of information. The information used is not particularly limited, and may include Layer 1 information obtained from the sub-access point units 7004-1 to 7004-3, such as the received signal strength indicator (RSSI) value for each band, changes in the RSSI over time, the modulation and coding scheme (MCS) used, and error rate. The route selection unit 7002 may also select a band by obtaining information about applications running on the integrated station device 7005 via the sub-station units 7006-1 to 7006-3 within the integrated station device 7005. The route selection unit 7002 may also select a band by obtaining information from a device external to the integrated access point device 7001. As an example, the route selector 7002 may select a band based on Layer 1 information obtained from a Layer 1 monitor 7009 outside the integrated access point device 7001, such as information obtained from a Layer 1 monitor 7009 that measures information such as the RSSI value for each band, changes in RSSI over time, and the MCS being used, or information about application traffic obtained from a network control device connected to the external network, such as an SDN (Software Designed Network) 7010 controller. The external device is not limited to these, and various other devices may be used, such as a device that selects a better route (band) by learning past traffic using application traffic and Layer 1 information. Furthermore, if the application information determines that the quality of the currently set band does not meet the quality required by the application, the route selector 7002 may configure the gateway units 7003-1 to 7003-3 to select another band. The application information may be information obtained from an application running on the integrated station device 7005, or may be information about an application running on a device connected to the integrated access point device 7001.

[0081] The integrated station device 7005 includes substation units 7006-1 to 7006-3, an operating system (OS) execution unit 7007, and an application execution unit 7008. The OS execution unit 7007 and the application execution unit 7008 are conceptual blocks and may be implemented as an OS running on certain hardware and an application running on that OS. Three substation units 7006-1 to 7006-3 are connected to the hardware running the OS. The substation unit 7006-1 uses band 1, the substation unit 7006-2 uses band 2, and the substation unit 7006-3 uses band 3. Each of the substation units 7006-1 to 7006-3 is configured to automatically connect to the sub-access point units 7004-1 to 7004-3, or to connect in response to instructions from the OS execution unit 7007. The OS execution unit 7007 assigns IP addresses / subnets to be used by each of the substation units 7006-1 to 7006-3. As an example, the IP address / subnet used by substation unit 7006-1 may be 192.168.1.11 / 24, the IP address / subnet used by substation unit 7006-2 may be 192.168.2.11 / 24, and the IP address / subnet used by substation unit 7006-3 may be 192.168.3.11 / 24. These IP addresses / subnets may be set using DHCP, in which case the IP addresses / subnets used by each of substation units 7006-1 to 7006-3 may be set in accordance with the IP address information offered by each of gateway units 7003-1 to 7003-3.

[0082] The OS execution unit 7007 treats one of the IP addresses used by each of the substation units 7006-1 to 7006-3 as a representative IP address, and sets the IP address used by an application running in the application execution unit 7008 to be the representative IP address. The OS execution unit 7007 sets traffic addressed to the representative IP address that arrives at a substation unit other than the representative IP address to be forwarded by IP forwarding to the I / F of the substation unit in which the representative IP address is set. Furthermore, traffic to an external network may be sent via the substation unit in which the representative IP address is set.

[0083] By configuring the integrated access point device 7001 and the integrated station device 7005 as described above, communication using multiple bands becomes possible while using the representative IP address configured in the integrated station device 7005. It also becomes possible to dynamically change the band to be used. Furthermore, since the sub-access point units 7004-1 to 7004-3 and the sub-station units 7006-1 to 7006-3 operate in the same way as conventional access point devices and station devices, access control using carrier sense is performed in each band, enabling coexistence with conventional wireless LANs.

[0084] Next, an example of a modified example in which a band selection function is also implemented on the integrated station device side will be described using FIG. 8. The integrated access point device 8001 has the same configuration as the integrated access point device 7001 described using FIG. 7, and operates in the same way except that the external network connected to the integrated access point device is distinguished as external network 1, so description thereof will be omitted. The integrated station device 8005 is composed of substation units 8006-1 to 8006-3, gateway units 8011-1 to 8011-3, an operating system (OS) execution unit 8007, and an application execution unit 8008. The OS execution unit 8007 and the application execution unit 8008 are conceptual blocks and may be implemented as an OS running on certain hardware and an application running on that OS. Each of the substation units 8006-1 to 8006-3 is connected to each of the gateway units 8011-1 to 8011-3. Substation unit 8006-1 and gateway unit 8011-1 use band 1, substation unit 8006-2 and gateway unit 8011-2 use band 2, and substation unit 8006-3 and gateway unit 8011-3 use band 3. By setting this from the OS execution unit 8007, each of gateway units 8011-1 to 8011-3 controls whether or not to forward traffic input from the OS execution unit 8007 or external network 2 to substation units 8006-1 to 8006-3. For traffic generated by application execution unit 8008 and destined for external network 1, or traffic input from external network 2 and destined for external network 1, it is possible to control the band used by that traffic by setting one of gateway units 8011-1 to 8011-3 to forward the traffic. The gateway units 8011-1 to 8011-3 may be configured so that one gateway unit has multiple I / Fs, and each I / F may be configured to correspond to each of the substation units 8006-1 to 8006-3, and the band used may be controlled by controlling the I / F to which traffic is forwarded.

[0085] The OS execution unit 8007 may also control the bands to be used based on the traffic conditions generated by the application execution unit 8008, information input from external devices, such as the RSSI value for each band input from the layer 1 monitor 2 8012, changes over time, and the MCS (Modulation and Codec Schemes) being used. With the above configuration, it becomes possible for the integrated station 8005 to control the bands to be used.

[0086] Next, as a modified example, an example of a wireless communication system that implements a scheduling method based on application requirements is shown. In an embodiment of the present invention, an AP can perform scheduling based on application requirements transmitted from a higher layer to a lower layer (e.g., from the application layer to the MAC layer). The application is assumed to be video transmission from the AP to a STA, including real-time video transmission applications such as streaming. Applications other than video transmission can also be considered. Furthermore, application requirements can be set, such as video resolution, video frame rate, required image quality, required transmission rate (hereinafter also referred to as target video rate), acceptable jitter, and acceptable delay time. Hereinafter, a case in which a target video rate and acceptable delay time are set as application requirements will be described, but this is not limited to this. Accordingly, a scheduling method based on application requirements is hereinafter a scheduling method based on video transmission requirements, and represents a method for performing data transmission while satisfying the video transmission requirements. A scheduling method based on application requirements can aim to increase the number of applications running (hereinafter also referred to as the number of applications accommodated or the number of apps accommodated). In this embodiment, when application requirements are included, the method can be applied not only to data frames but also to management frames and control frames.

[0087] To increase the number of applications that can be accommodated, it is important to improve not only the throughput (bit throughput) calculated from the number of bits that can be transmitted per unit time (video throughput), but also the throughput calculated from the number of bits that can be transmitted per unit time while satisfying the required conditions (video throughput). In this case, the difference between the bit throughput and the video throughput represents the unnecessary occupation of radio resources that occurs when video packets are transmitted even when the required conditions cannot be met. The unnecessary occupation of radio resources can cause interference with other wireless communication devices. To increase the number of applications that can be accommodated, it is important to improve the video throughput while minimizing the difference between the bit throughput and the video throughput.

[0088] As a scheduling method based on application requirements, a scheduling method based on video transmission requirements will be described. Video information (hereinafter referred to as video packets) generated on the AP side and addressed to a STA is divided into multiple transmission packets (PPDUs or PPDU frames) and transmitted. Video packets are generated at time intervals based on the video segment length, and the information volume of the video packet is set based on the target video rate and video segment length. To improve video throughput, all transmission packets constituting a video packet must be transmitted while satisfying the requirements. Transmission of a transmission packet that does not satisfy the video transmission requirements means that the video packet has failed to be transmitted, is not counted as video throughput, and may cause a deterioration in video quality, etc.

[0089] The scheduling method based on video transmission requirements is a method of not allocating video packets addressed to users who do not satisfy the video transmission requirements, but instead allocating video packets addressed to users who satisfy the video transmission requirements (hereinafter also referred to as an allocation control method based on application requirements). Furthermore, when video packets are transmitted in multiple transmission packets, a method may be used in which transmission of video packets addressed to other users is not started until transmission of video packets addressed to a user that has been allocated earlier is completed (hereinafter also referred to as a transmission order control method). Each method will be described later. The two methods can also be combined and used as a single scheduling method.

[0090] FIG. 9 illustrates an example of a wireless communication system according to this embodiment, but is not limited thereto. Wireless communication systems 3-1, 3-2, and 3-3 are each a BSS. Hereinafter, wireless communication devices 1-1, 1-2, and 1-3 may be access point devices, base station devices, AP-MLD devices, etc. Wireless communication devices 2-1, 2-2, and 2-3 may be station devices, terminal devices, Non-AP-MLD devices, etc. For example, wireless communication devices 1-1 to 2-3 constituting each of the wireless communication systems 3-1 to 3 may include wireless communication devices 2-1 to 2-3. Although the wireless communication systems 3-1 to 3 form different BSSs, this does not necessarily mean that the ESSs (Extended Service Sets) are different. An ESS refers to a service set that forms a LAN (Local Area Network). In other words, wireless communication devices belonging to the same ESS can be considered to belong to the same network from a higher layer. Furthermore, BSSs are connected via a DS (Distribution System) to form an ESS. The wireless communication systems 3-1, 3-2, and 3-3 can cooperate with each other to bundle a plurality of wireless communication systems into one wireless communication system.

[0091] An example of a wireless communication device according to this embodiment is shown in Figures 10 and 11. Figure 10 shows an example of a wireless communication device 10000-1, and Figure 11 shows an example of an autonomous distributed control unit 10002-1. The wireless communication device 10000-1 includes an upper layer unit 10001-1, a MAC layer unit 10001a-1, an autonomous distributed control unit 10002-1, a transmitting unit 10003-1, a physical layer frame generating unit 10003a-1, a wireless transmitting unit 10003b-1, a receiving unit 10004-1, a wireless receiving unit 10004a-1, a signal demodulating unit 10004b-1, and an antenna unit 10005-1. The autonomous distributed control unit 10002-1 includes a CCA unit 10002a-1, a backoff unit 10002b-1, and a transmission determining unit 10002c-1 shown in Figure 11.

[0092] The receiver 10004-1 of the wireless communication device 10000-1 receives a radio frequency band signal via the antenna 10005-1, and the radio receiver 10004a-1 generates a physical layer signal from the radio frequency band signal. The radio receiver 10004a-1 notifies the CCA unit 10002a-1 of the autonomous distributed control unit 10002-1 of the preamble demodulation result, and notifies the transmission decision unit 10002c-1 that the physical layer signal has been received. The signal demodulator 10004b-1 performs error correction decoding, etc., demodulates the PPDU frame from the physical layer signal, extracts any or all of the physical layer header, MAC header, and data portion, and transmits them to the upper layer unit 10001-1.

[0093] FIG. 12 shows a wireless communication device 10000-2 that corresponds to the block diagrams of FIGS. 10 and 11 and is multilink compatible. Hereinafter, descriptions of the same parts as those in the block diagrams of FIGS. 10 and 11 will be omitted. The wireless communication device (10000-1 or 10000-2) is not limited to one of them unless otherwise specified. In the following embodiments, the wireless communication device 10000-1 is described as being applied, but the wireless communication device 10000-2 is also valid. Meanwhile, the wireless communication device 10000-2 has two or more wireless frequency bands (wireless frequency bands A to Z), each of which is configured with an independent transmitter and receiver. For example, the MAC layer 10001a-1 of the upper layer 10001-1 in FIG. 12 can perform allocation processing or transmission order control for each link based on the requirements of the application, which will be described later. The MAC layer section 10001a-1 of the upper layer section 10001-1 in Figures 10 and 12, which performs allocation processing or transmission order control based on the requirements of the application, is also called an allocation control section, a transmission order control section, or a control section meaning both of these.

[0094] The upper layer unit 10001-1 of the wireless communication device 10000-1 transmits the generated packets to the MAC layer unit 10000a-1 and generates an MPDU or an A-MPDU (Aggregated MAC Protocol Data Unit) that aggregates the MPDUs. Specifically, the upper layer unit 10001-1 transmits the generated video packets and application requirements to the MAC layer unit 10001a-1. The MAC layer unit 10001a-1 then divides the generated video packets into multiple transmission packets, creates MPDUs, A-MPDUs, and PDSUs, and performs allocation processing or transmission order control based on the application requirements described below. The MAC layer unit 10001a-1 transmits the generated PSDUs to the physical layer frame generation unit 10003a-1 of the transmission unit 10003-1. The wireless communication device 10000-2 may notify the AP of the application requirements by notifying the AP from the STA in an arbitrary frame.

[0095] The CCA unit 10002a-1 of the autonomous distributed control unit 10002-1 performs carrier sensing, determines the channel state (idle / busy), and notifies the backoff unit 10002b-1 of the result. When receiving a physical layer signal, the transmission determination unit 10002c-1 waits for the interframe space (IFS). The transmission determination unit 10002c-1 can use DIFS as the interframe space, and when notified of the start of PPDU frame transmission, requests the backoff unit 10002b-1 to start counting down the backoff counter after DIFS has elapsed. Note that the backoff unit 10002b-1 can start counting down the backoff counter when the channel state is idle and the transmission determination unit 10002c-1 has requested the start of counting down the backoff counter. On the other hand, when the channel state is busy, the backoff counter counting down can be suspended. Backoff unit 10002b-1 notifies transmission decision unit 10002c-1 of the value of the backoff counter. Then, when the value of the backoff counter is 0, transmission decision unit 10002c-1 generates a PPDU frame from the physical layer signal using physical layer frame generation unit 10003a-1 of transmission unit 10003-1. The PPDU frame is modulated and coded and transmitted to wireless transmission unit 10003b-1. Wireless transmission unit 10003b-1 converts the PPDU frame into a radio frequency band signal, generates a physical layer signal, and transmits the physical layer signal via the antenna unit.

[0096] An allocation control method based on application requirements will now be described. Allocation control is performed by the MAC layer unit 10001a-1. The allocation control method based on application requirements is a control method implemented on the AP side, and can be implemented after backoff ends. The AP calculates the minimum transmission rate (hereinafter also referred to as the minimum transmission rate) required to transmit the amount of information in the remaining video packets within the allowable delay time (or within the allowable time) for the video packets that have been generated at the time backoff ends. The minimum transmission rate R tx_min can be calculated from the following formula:

[0097]

[0098] B in the above formula (1) ｖｉｄｅｏ_ｐａｃｋｅｔ is the amount of information in the generated video packets, and indicates the amount of information (bits) in the remaining video packets. ｎｅｘｔ_ｖｉｄｅｏ_ｐａｃｋｅｔ is the next video packet generation time (t), T ｂａｃｋｏｆｆ_ｅｎｄ indicates the backoff end time (t). In this modification, the backoff end time is the start time of scheduling by the AP, that is, the timing when allocation control based on the requirements of the application starts. Therefore, T ｎｅｘｔ_ｖｉｄｅｏ_ｐａｃｋｅｔ -T ｂａｃｋｏｆｆ_ｅｎｄ indicates the remaining allowable delay time. ｏｖｅｒｈｅａｄ indicates the overhead time (t) that occurs when transmitting video packets. This overhead is the sum of the frame length (t) of the PHY header and MAC header, the DIFS length (t) × the number of transmission packet transmissions −1, the maximum backoff time × the number of transmission packet transmissions −1, the SIFS length (t) × the number of transmission packet transmissions, and the ACK frame length (t) × the number of transmission packet transmissions. Note that t represents time. The number of transmission packet transmissions is N ｔｘ＿ｐａｃｋｅｔ and can be calculated from the following formula:

[0099]

[0100] In the above formula (2), Nmaximum_aggregation_size indicates the maximum aggregation number of MPDUs. However, if the frame length (t) of the transmission packet calculated based on the above formula (2) exceeds a predetermined transmission burst length (t) in relation to the MCS set in the transmission packet, etc., the transmission packet can be configured by adopting an aggregation number that is less than the predetermined transmission burst length (t).

[0101] The MCS rate (R ｍｃｓ ) is the lowest transmission rate R ｔｘ＿ｍｉｎIf the above conditions are met, the AP can determine that it is in a state where it can allocate wireless resources to video packets addressed to the user (which may be a STA or an application running on a device connected to the STA). If a video packet is made up of multiple transmission packets, the AP can determine that it is in a state where it can allocate wireless resources to the video packets addressed to the user (which may be a STA or an application running on a device connected to the STA). ｍｃｓ is the lowest transmission rate R ｔｘ＿ｍｉｎ It can be determined that transmission packets addressed to users with a rate of 100 or more can be allocated to radio resources. The AP stores user indexes indicating video packets addressed to users that can be transmitted and meet the requirements for video transmission in a list (hereinafter also referred to as a transmittable list). Meanwhile, the MCS rate R calculated from the MCS set for the transmission packets in the above formula (1) is ｍｃｓ is the lowest transmission rate R ｔｘ＿ｍｉｎ If the MCS rate is less than the maximum rate, the video packets addressed to the user cannot satisfy the requirements for video transmission, and therefore the user index (index representing the STA) is not saved in the ready list. ｍｃｓ , the lowest transmission rate R ｔｘ＿ｍｉｎ The MAC layer unit 10001a-1 of the AP starts transmitting transmission packets in the transmission order determined by the scheduler, but does not allocate wireless resources to transmission packets addressed to users not included in the ready list, and instead allocates wireless resources to video packets addressed to users included in the ready list.

[0102] FIG. 13 shows an overview of allocation control based on application requirements. FIG. 13(a) shows scheduling without allocation control based on application requirements, and FIG. 13(b) shows scheduling with allocation control based on application requirements. In FIG. 13, the AP performs scheduling every time DIFS (20000-1, 30000-1) and backoff (20000-2, 30000-2) ends. The scheduler is not limited to a specific one such as Max CIR, PF, or APF. On the AP side, video packets addressed to STA#1 (20001-1, 30001-1), video packets addressed to STA#2 (20002-1, 30002-1), and video packets addressed to STA#3 (20003-1, 30003-1) are generated, and a target video rate and allowable delay time (20000-4, 30000-4) are set as required conditions for the video packets addressed to each STA. Video packets addressed to STAs are represented by vertical arrows, and the height indicates the amount of information in the generated video packets. The unit of control interval for video packets is the video segment length. The allowable delay time can be the interval between video packet generation based on the video segment length, and is shown by a horizontal line. In the figure, DIFS is indicated by 20000-1 and 30000-1, and backoff is indicated by 20000-2 and 30000-2. In the figure, SIFS are indicated by 20000-5 and 30000-5, and ACKs are indicated by 20000-6 and 30000-6. A video packet addressed to a STA is composed of one transmission packet (20000-3, 30000-3), and the number written on the transmission packet indicates the destination STA. While FIG. 13 shows the AP transmitting a video packet to the STA (downlink communication (hereinafter, DL)) and the STA transmitting an ACK frame to the AP (uplink communication (hereinafter, UL)), in an embodiment of the present invention, the STA may transmit a video packet to the AP via UL, and the AP may transmit an ACK frame to the STA via DL. Hereinafter, symbols for overlapping figures in the figures will be omitted. DL is indicated by 20000-7, and UL is indicated by 20000-8.

[0103] In FIG. 13(a), as a result of scheduling by the AP, transmission is initiated in the following order: a transmission packet addressed to STA#2 (20002-3), a transmission packet addressed to STA#1, and a transmission packet addressed to STA#3 (omitted in the figure). The numbers shown in the transmission packets in the figure indicate the destination STA. In the figure, the transmission packet addressed to STA#2 is successfully transmitted within the allowable delay time, while the transmission packet addressed to STA#1 is transmitted beyond the allowable delay time and times out. The timeout generates a difference between bit throughput and video throughput. The medium occupancy time required to transmit a transmission packet addressed to STA#1 that does not meet the required conditions means unnecessary occupation of radio resources, which may cause interference with other systems. Although omitted in the figure, the transmission packet addressed to STA#3 also times out.

[0104] 13B, the AP performs allocation control based on the application requirements each time the backoff ends. The AP allocates the minimum transmission rate R based on the video transmission requirements (target video rate and allowable delay time) set in the video packets addressed to STA#1, STA#2, and STA#3. ｍｉｎ , the MCS rate R based on the MCS set for the video packets addressed to STA#1, STA#2, and STA#3. ｍｃｓ The AP calculates the MCS rate R based on the MCS set in the transmission packet addressed to the STA. ｍｃｓ , and the minimum transmission rate R ｔｘ＿ｍｉｎ13B, the MCS rates set for the video packets addressed to STA#2 and STA#3 are equal to or greater than the minimum transmission rate, while the MCS rate set for the video packet addressed to STA#1 is less than the minimum transmission rate. That is, the ready list includes the user indexes of STA#2 and STA#3. The AP performs scheduling, and similarly to FIG. 13A, transmits the transmission packets addressed to STA#2, followed by the transmission packets of STA#1 and STA#3 in that order. The transmission packets addressed to STA#2 are included in the ready list, indicating that they are video packets addressed to STAs that meet the requirements for video transmission and are transmittable, and therefore can start transmitting the transmission packets according to the scheduler. On the other hand, the transmission packets addressed to STA#1 are not included in the ready list, and therefore cannot start transmitting. However, the AP assigns transmission packets addressed to STA#3, which are included in the ready list, instead of the transmission packets addressed to STA#1, and can complete the transmission without timing out. In the embodiment of the present invention, a timeout occurs when the time taken from when the AP transmits a transmission packet to when it receives an ACK frame from the STA exceeds the allowable delay time.

[0105] In an embodiment of the present invention, allocation control based on application requirements can be applied to, for example, typical scheduling methods focusing on bit throughput, such as Maximum Carrier-to-Interference Power Ratio (Max CIR), which uses the MCS set for transmission packets addressed to users as a metric; Proportional Fairness (PF), which improves bit throughput while ensuring fairness among users; and Application Proportional Fairness (APF), which takes application requirements into account. For example, in a scheduling method using Max CIR, a lower MCS is set for transmission packets addressed to a STA that are allocated last compared to the first. Setting a lower MCS can result in transmission exceeding the allowable delay time, potentially causing video packets to time out. Video packet timeouts occur when transmission of user-addressed transmission packets is initiated without considering the video transmission requirements, and are a problem that occurs regardless of scheduling.

[0106] The transmission of video packets that exceed the allowable delay time has the problem of reducing the allowable delay time of video packets destined for other users by the amount of the delay when video packets destined for other users have already been generated or when transmission packets constituting video packets destined for other users are queued / pending for transmission. This causes video packets to time out. Allocation control based on application requirements is a method of not allocating radio resources to video packets destined for users who cannot meet the video transmission requirements, but instead allocating radio resources to video packets destined for users who meet the video transmission requirements, thereby solving the above problem. As a result, radio resources can be used efficiently from the perspective of video throughput, and video throughput and the number of applications accommodated can be improved.

[0107] FIG. 14 shows a flowchart of allocation processing based on application requirements. This flowchart represents processing on the AP side. First, the processing from S1-1 to S1-10 will be described. The start of processing in FIG. 14 (S1-1) is performed after backoff has ended. In initialization of the ready-to-transmit list (S1-2), a ready-to-transmit list is initialized to store user indexes that can transmit video packets while satisfying the video transmission requirements. S1-3 to S1-10 are loop processing, in which user index i is looped for all users (also referred to as STAs or terminals). The loop processing from S1-3 to S1-10 is processing for storing user indexes that can transmit video packets while satisfying the video transmission requirements in the ready-to-transmit list. In this loop processing, when the remaining information amount of the video packet is 0 or less in S1-4, the process proceeds to end of the loop (S1-10). For example, if no video packet addressed to the STA has been generated at the start of processing (S1-1), or if the transmission of the video packet addressed to the STA has been completed (i.e., the transmission of all transmission packets constituting the video packet has been completed), the process moves to the end of the loop (S1-10). If the remaining information amount of the video packet is greater than 0 in S1-4, the MCS is updated (S1-5), the MCS rate is calculated (S1-6), and the minimum transmission rate is calculated (S1-7). In S1-6, the MCS rate R ｍｃｓ , S1-7, the lowest transmission rate R ｔｘ＿ｍｉｎ is calculated. In S1-8, it is determined whether the MCS rate is equal to or greater than the minimum transmission rate (also referred to as determination processing). In S1-9, the user index whose MCS rate is equal to or greater than the minimum transmission rate is saved in the transmittable list. If the MCS rate is less than the minimum transmission rate, the loop ends (S1-10). However, if the user index i has not been incremented to N, i is incremented and the process returns to S1-3. Note that the names of the variables and processing steps described in the flowcharts below are not limited to those described in the flowcharts, as long as they are used for the same purpose. Also, in the flowcharts below, Y indicates a determination result of True, and N indicates a determination result of False.

[0108] Next, the processing of S1-11 to S1-18 will be described. In S1-11, the AP determines the transmission order of transmission packets addressed to the STA according to the scheduler metrics. The result of S1-11 is saved in the transmission order list (tx_order in FIG. 14). S1-12 to S1-18 are loop processing, and determine the user index to which the transmission packet is to be sent. The loop termination processing (S1-18) ends when a break occurs (S1-17) or when user index i has been looped for all users (all STAs). S1-13 shows processing (transmission order determination processing) for performing loop processing in the order of tx_order determined by the scheduling processing of S1-11. Note that the user index of the destination returned by tx_order is distinguished as j. In S1-14, when the remaining amount of information in the video packet is 0 or less, the process proceeds to the end of the loop (S1-18). However, if the user index i has not been incremented to N, i is incremented and the process returns to S1-3. For example, if no video packet addressed to the STA has been generated at the time of the start of processing (S1-1), or if the transmission of the video packet addressed to the STA has been completed (i.e., the transmission of all transmission packets constituting the video packet has been completed), the process proceeds to the end of the loop (S1-18). If the remaining amount of information in the video packet is greater than 0 in S1-14, the destination user index j is determined as the destination tx_target of the transmission packet in S1-15 (destination determination). After the break (S1-17), the process proceeds to the end of the loop (S1-18) and processing from S1-19 onwards.

[0109] Then, in S1-19, it is determined whether tx_target, which indicates the destination of the transmission packet, is included in the ready-to-transmit list saved in S1-9 (determination process). If tx_target is included in the ready-to-transmit list saved in S1-9, allocation process (S1-20), PPDU creation process (S1-21), and PPDU transmission process (S1-22) are performed, and the process proceeds to end (S1-23). ​​S1-20 is a process for determining whether to transmit a transmission packet addressed to tx_target. S1-22 refers to a process for allocating a PPDU frame to a radio resource and transmitting it. If tx_target is not included in the ready-to-transmit list saved in S1-9 in S1-19, the process proceeds to end (S1-23).

[0110] The allocation process based on the application requirements in the wireless communication device 10000-1 and the wireless communication device 10000-2 will now be described. The autonomous distributed control unit 10002-1 can transmit a backoff end notification from the backoff unit 10002b-1 to the transmission determination unit 10002c-1. At this time, S1-1 in the flowchart of FIG. 14 is started. Steps from initialization of the transmittable list (S1-2) to allocation processing (S1-20) can be performed by the MAC layer unit 10001a-1 of the upper layer unit 10001-1. Meanwhile, the transmitting unit 10003-1 can perform PPDU creation processing (S1-21) in the physical layer frame generation unit 10003a-1 and PPDU transmission processing (S1-22) in the wireless transmitting unit 10003b-1. After transmitting the PPDU, the wireless communication device ends processing (S1-23) and starts backoff again.

[0111] A transmission order control method according to an embodiment of the present invention will now be described. Transmission order control is applied when a video packet is divided into two or more transmission packets for transmission. By not starting transmission of video packets addressed to other users until transmission of video packets addressed to a user that has been assigned earlier is completed, the transmission order of transmission packets addressed to a user is prevented from being changed. Figure 15 shows an overview of transmission order control. Figure 15(a) shows scheduling without transmission order control, and Figure 15(b) shows scheduling with transmission order control. The scheduler in Figure 15 is not limited to a specific one, such as Max CIR, PF, or APF. The AP performs transmission order control each time backoff ends. In FIG. 15, the AP generates video packets addressed to STA#1 (40001-1, 50001-1) and video packets addressed to STA#2 (40002-1, 50002-1), and the target video rate and allowable delay time (40000-4, 50000-4) are set as required conditions for the video packets addressed to each STA. The video packets addressed to the STA are represented by vertical arrows, and their height indicates the amount of information in the generated video packets. The allowable delay time is the interval between video packet occurrences and is indicated by horizontal lines. Note that FIG. 15 shows an example in which the video packet addressed to the STA is composed of two transmission packets, and the first and second transmission packets are shown separately in the figure. When the second transmission packet is completely transmitted within the allowable delay time, the video packet is counted. In the figure, DIFS is shown as 40000-1 and 50000-1, and backoff is shown as 40000-2 and 50000-2. In the figure, SIFS is shown as 40000-5 and 50000-5, and ACK is shown as 40000-6 and 50000-6. DL communication is shown as 40000-7 and 50000-7, and UL communication is shown as 40000-8 and 50000-8.

[0112] In FIG. 15(a), as a result of scheduling performed each time backoff ends, transmission is initiated in the following order: the first transmission packet (40000-3) addressed to STA#2, the first transmission packet addressed to STA#1, the second transmission packet addressed to STA#2, and the second transmission packet addressed to STA#1. The numbers shown in the transmission packets in the figure indicate the ordinal number of the transmission packet addressed to the STA to which it is addressed. For example, the number 2-1 written in the transmission packet in the figure indicates the first transmission packet addressed to STA#2. FIG. 15(a) shows a situation in which transmission of a video packet addressed to STA#1 is initiated during transmission of a video packet addressed to STA#2. The video packets addressed to STA#2 and STA#1 cannot be transmitted within the allowable delay time, resulting in a timeout. A timeout not only generates a difference between bit throughput and video throughput, but also causes interference to other systems due to the medium occupancy time required to transmit transmission packets that do not meet the required conditions.

[0113] In FIG. 15(b), the AP performs scheduling and transmission order control each time backoff ends. After starting transmission of the first transmission packet (50000-3) addressed to STA#2, the AP starts transmission of the second transmission packet addressed to STA#2, even if the scheduler sets transmission of the first transmission packet addressed to STA#1. In other words, with scheduling with transmission order control, the AP does not start transmission of the video packet addressed to STA#1 until transmission of the video packet addressed to STA#2 is completed. In FIG. 15(b), the AP transmits the first and second transmission packets addressed to STA#2 within the allowable delay time and completes transmission of the video packets. In other words, scheduling with transmission order control reduces the difference between bit throughput and video throughput, thereby improving video throughput. Note that in FIG. 15(b), if transmission of the second transmission packet addressed to STA#2 exceeds the allowable delay time, both packets time out, just as in the case without transmission order control. In this case, by combining allocation control based on application requirements with transmission order control, only users who can transmit video packets that satisfy the allowable delay time can be allocated, thereby improving video throughput.

[0114] FIG. 16 shows a flowchart of transmission order control according to an embodiment of the present invention. This flowchart describes the transmission process on the AP side, in which transmission of video packets addressed to other users is not initiated until transmission of video packets addressed to a previously assigned user is completed. Hereafter, explanations of steps that represent processes similar to those of the application requirement-based allocation control method shown in FIG. 14 will be omitted. Other steps not directly related to transmission order control itself, such as MCS update processing, will be omitted. Transmission order control begins (S2-1) after backoff is completed. In S2-2, the AP determines the transmission order of transmission packets addressed to STAs according to the scheduler metrics. The result of S2-2 is saved in a transmission order list (tx_order). Note that tx_order stores user indices for all users. S2-3 to S2-10 are loop processes that determine the user index of the transmission packets to be sent. S2-6 and S2-7 are the main processes of transmission order control, and will be described later. The process for terminating this loop (S2-10) is terminated when a break occurs (S2-9) or when the user index i has been looped for all users (all STAs). S2-4 shows the process for performing loop processing in the order of tx_order determined by the scheduling process of S2-2. In S2-5, when the remaining information amount of the video packet is 0 or less, the process proceeds to the end of the loop (S2-10). However, if the user index i has not been incremented to N, i is incremented and the process returns to S2-3. For example, if no video packet addressed to the STA has been generated at the time of the start of processing (S2-1), or if the transmission of the video packet addressed to the STA has been completed (i.e., the transmission of all transmission packets constituting the video packet has been completed), the process proceeds to the end of the loop (S2-10).

[0115] The main steps of transmission order control, S2-6 and S2-7, will be described. In S2-6, it is determined whether the user index (In_progress_sta_index) of a user whose video packet is currently being transmitted is 0 (determination process). If In_progress_sta_index is not 0, it indicates that a video packet (or transmission packet) addressed to the previously assigned user (addressed to STA) exists and is currently being transmitted. In this case, in S2-7, In_progress_sta_index is stored in tx_target, which is the destination user index, so that transmission of video packets addressed to other users is not initiated until transmission of the video packets addressed to the previously assigned user is completed. In other words, the process of S2-7 makes it possible not to initiate transmission of video packets addressed to other users until transmission of all transmission packets constituting the video packet addressed to the previously assigned user is completed. If In_progress_sta_index is 0, the user index j set by scheduling is stored in tx_target, which is the destination of the transmission packet (S2-8, also referred to as updating the user index).

[0116] FIG. 17 shows a flowchart of transmission order control according to an embodiment of the present invention. This flowchart describes the reception process on the AP side, explaining the operation related to setting and initializing the user index (In_progress_sta_index) for video packets currently being transmitted. The processes of S3-1 to S3-9 are initiated after the PPDU frame is received (after the ACK frame is received). In S3-2, reception processing is performed for the PPDU frame received from the destination tx_target determined in FIG. 16. In S3-3, if the number of MPDUs received without error is greater than 0, the remaining information amount of the video packet is updated in S3-4. On the other hand, if the number of MPDUs received without error is 0 or less in S3-3, i.e., if all MPDUs are erroneous, In_progress_sta_index is initialized in S3-5, and processing ends (S3-9). S3-6 is a process (determination process) for determining whether all video packets have been transmitted. If the amount of remaining information in the video packet updated in S3-4 is 0 or less, In_progress_sta_index is initialized in S3-7, and the process ends (S3-9). Note that S3-4 may be performed in the transmission process rather than the reception process. If the amount of remaining information in the video packet updated in S3-4 is greater than 0, that is, if the video packet is in the middle of transmission, In_progress_sta_index is stored in tx_target, which is the destination user index, in S3-8 so that transmission of video packets addressed to other users is not started until transmission of the video packets addressed to the previously assigned user is completed, and the process ends (S3-9). Note that the number of MPDUs received without error in S3-3 may be set to a natural number other than 0.

[0117] The transmission order control in the wireless communication devices 10000-1 and 10000-2 will now be described. The autonomous distributed control unit 10002-1 can transmit the end of backoff from the backoff unit 10002b-1 to the transmission decision unit 10002c-1. At this time, S2-1 in the flowchart of FIG. 16 is started. The scheduling (S2-2) to the loop end (S2-10) can be performed by the MAC layer unit 10001a-1 of the upper layer unit 10001-1. Meanwhile, the transmission unit 10003-1 can perform PPDU creation processing (S2-11) in the physical layer frame generation unit 10003a-1 and PPDU transmission processing (S2-12) in the wireless transmission unit 10003b-1. After transmitting the PPDU, the wireless communication device ends processing (S2-13) and starts backoff again.

[0118] The receiving unit 10004-1 of the wireless communication device receives a radio frequency band signal via the antenna unit 10005-1. At this time, S3-1 in the flowchart of FIG. 17 is started. In S3-2, the wireless receiving unit 10004a-1 generates a physical layer signal from the radio frequency band signal, and the wireless receiving unit 10004a-1 notifies the CCA unit 10002a-1 of the autonomous distributed control unit 10002-1 of the demodulation result of the preamble, and can also notify the transmission decision unit 10002c-1 that the physical layer signal has been received. In addition, the signal demodulation unit 10004b-1 performs error correction decoding, etc., and demodulates the PPDU frame (ACK frame) from the physical layer signal, thereby extracting any or all of the physical layer header, MAC header, and data portion, and transmitting them to the upper layer unit 10001-1. The steps from S3-3 onwards can be performed by the MAC layer unit 10001a-1 of the upper layer unit 10001-1.

[0119] Another modified example is described below. Fig. 18 is a diagram showing an example of the configuration of a station device 4002. The station device 4002 includes a radio control unit (radio control step) a5001, a timer unit (timer step) a5002, a radio communication unit (radio communication step) a5003, and an antenna unit a5004. Furthermore, the radio communication unit a5003 includes a physical layer frame generation unit (physical layer frame generation step) a5003a, a radio transmission unit (radio transmission step) a5003b, a radio reception unit (radio reception step) a5003c, a received power measurement unit (received power measurement step) a5003d, a channel estimation unit (channel estimation step) a5003e, and a signal demodulation unit (signal demodulation step) a5003f.

[0120] The wireless control unit a5001 performs information processing on layers higher than the physical layer, such as the MAC layer and LLC layer, for information handled within the wireless communication device itself (such as information related to frames to be transmitted and MIB (Management Information Base)) and frames received from other wireless communication devices, and also controls the wireless communication unit a5003.

[0121] The timer unit a5002 includes one or more timers and manages the timers related to the sounding process. Details of the timer unit a5002 will be described later. Note that, in the example of Fig. 18, the timer unit a5002 is illustrated as being included in the wireless control unit a5001, but is not limited to this configuration. The timer unit a5002 may be provided outside the wireless control unit a5001 and configured to operate under control from the wireless control unit a5001.

[0122] The physical layer frame generator a 5003a has the function of generating a physical layer frame (PPDU). The physical layer frame generator a 5003a performs error correction coding, modulation, beamforming processing (precoding processing), etc. on the MAC layer frame sent from the wireless control unit a 5001. Beamforming processing may be achieved by multiplying the modulated signal by a beamforming matrix (beamforming filter) notified by the wireless control unit a 5001. The physical layer frame generator a 5003a outputs the generated physical layer frame to the wireless transmission unit a 5003b.

[0123] The wireless transmission unit a5003b converts the physical layer frame input from the physical frame generation unit a5003a into a radio frequency (RF) band signal to generate a wireless signal. The processing performed by the wireless transmission unit a5003b includes digital-to-analog conversion, filtering, and frequency conversion from baseband frequency to wireless frequency. The wireless transmission unit a5003b transmits the generated wireless signal via the antenna unit a5004.

[0124] The wireless receiver a5003c has the function of converting a wireless signal received via the antenna unit a5004 into a baseband signal and generating a physical layer signal (e.g., a physical layer frame). The processing performed by the wireless receiver a5003c includes frequency conversion from a wireless frequency to a baseband frequency, filtering, analog-to-digital conversion, etc. The physical layer signal, which is the received signal converted into a digital signal by the wireless receiver a5003c, is input to the received power measurement unit a5003b, the channel estimation unit a5003e, and the signal demodulation unit a5003f.

[0125] The received power measurement unit a 5003d measures the received power of the received signal input from the wireless receiving unit a 5003c. The received power measurement unit a 5003d can measure the received power of the radio wave received on the frequency channel to be measured, the received power of the LTF of the received physical layer frame, etc. The received power measurement unit a 5003d can notify the wireless control unit a 5001 of the measurement result of the received power.

[0126] The channel estimation unit a 5003 e estimates the channel state through which the physical layer frame has propagated based on the received signal of the LTF (L-LTF, HT-LTF, VHT-LTF, HE-LTF, etc.) included in the physical layer frame received by the wireless receiving unit a 5003 c. The channel estimation unit a 5003 e can notify the signal demodulation unit a 5003 f and the wireless control unit 5001 of the channel estimation result.

[0127] The signal demodulation unit a 5003f performs channel equalization, demodulation, error correction decoding, etc. on the physical layer frame received by the wireless receiving unit a 5003c to obtain information such as the PHY header and MAC layer frame. The channel equalization process can use the channel estimation results from the channel estimator a 5003e. The signal demodulation unit a 5003f outputs the obtained PHY header and MAC layer frame to the wireless control unit a 5001.

[0128] The wireless control unit a5001 can perform physical carrier sensing and virtual carrier sensing based on the received power measurement results from the received power measurement unit a5003d and information acquired from the signal demodulation unit a5003f, and can determine the state of the wireless channel (including determining whether it is in an idle state or a busy state). The wireless control unit a5001 can notify the wireless communication unit a5003 of this wireless channel state determination information.

[0129] When there is control information, data, etc. to be transmitted, the wireless control unit a5001 can start a backoff procedure using the wireless channel state determination information. The wireless control unit a5001 generates a backoff counter based on the CW and has a countdown function for the backoff counter. For example, the wireless control unit a5001 can count down the backoff counter when the wireless channel state determination information indicates an idle state, and can stop the backoff counter countdown when the wireless channel state determination information indicates a busy state. Furthermore, the wireless control unit a5001 makes a transmission decision using either the wireless channel state determination information or the backoff counter value, or both. For example, the wireless control unit a5001 can notify the wireless communication unit a5003 of transmission decision information when the wireless channel state determination information indicates an idle state and the backoff counter value is 0. Furthermore, the wireless control unit a5001 can notify the wireless communication unit a5003 of transmission decision information when the wireless resource state determination information indicates an idle state.

[0130] FIG. 19 shows an example of the configuration of an access point device 4001. The access point device 4001 includes a wireless control unit (wireless control step) a6001, a wireless communication unit (wireless communication step) a5003, and an antenna unit a5004. Furthermore, the wireless communication unit a5003 includes a physical layer frame generation unit (physical layer frame generation step) a5003a, a wireless transmission unit (wireless transmission step) a5003b, a wireless reception unit (wireless reception step) a5003c, a received power measurement unit (received power measurement step) a5003d, a channel estimation unit (channel estimation step) a5003e, and a signal demodulation unit (signal demodulation step) a5003f. The access point device 4001 of FIG. 19 is basically configured similarly to the station device 4002 of FIG. 18. Therefore, the following description will focus on the differences between the two, and will omit a description of similar parts. Furthermore, parts corresponding to those in the station device of FIG. 18 will be described using the same reference numerals.

[0131] The wireless control unit a6001 performs information processing on layers higher than the physical layer, such as the MAC layer and LLC layer, for information handled within the wireless communication device itself (such as information related to frames to be transmitted and MIB (Management Information Base)) and frames received from other wireless communication devices, and also controls the wireless communication unit a5003.

[0132] The physical layer frame generator a 5003a has the function of generating a physical layer frame (PPDU). The physical layer frame generator a 5003a performs error correction coding, modulation, beamforming processing (precoding processing), etc. on the MAC layer frame sent from the wireless control unit a 6001. Beamforming processing may be achieved by multiplying the modulated signal by a beamforming matrix (beamforming filter) notified by the wireless control unit a 6001. The physical layer frame generator a 5003a outputs the generated physical layer frame to the wireless transmission unit a 5003b.

[0133] The received power measurement unit a 5003d measures the received power of the received signal input from the wireless receiving unit a 5003c. The received power measurement unit a 5003d can measure the received power of the radio waves received on the frequency channel to be measured, the received power of the LTF (L-LTF, HT-LTF, VHT-LTF, HE-LTF, etc.) of the received physical layer frame, etc. The received power measurement unit a 5003d can notify the wireless control unit a 6001 of the measurement result of the received power.

[0134] The channel estimation unit a 5003 e estimates the channel state through which the physical layer frame has propagated based on the LTF received signal included in the physical layer frame received by the wireless receiving unit a 5003 c. The channel estimation unit a 5003 e can notify the signal demodulation unit a 5003 f and the wireless control unit a 6001 of the channel estimation result.

[0135] The signal demodulation unit a 5003f performs channel equalization, demodulation, error correction decoding, etc. on the physical layer frame received by the wireless receiving unit a 5003c to obtain information such as the PHY header and MAC layer frame. The channel equalization process can use the channel estimation results from the channel estimator a 5003e. The signal demodulation unit a 5003f outputs the obtained PHY header and MAC layer frame to the wireless control unit a 6001.

[0136] When there is control information, data, a beacon, or the like to be transmitted, the wireless control unit a6001 can start a backoff procedure using the wireless channel state determination information. The wireless control unit a6001 generates a backoff counter based on the CW and has a countdown function for the backoff counter. For example, the wireless control unit a6001 can countdown the backoff counter when the wireless channel state determination information indicates an idle state, and can stop the backoff counter when the wireless channel state determination information indicates a busy state. Furthermore, the wireless control unit a6001 makes a transmission decision using either the wireless channel state determination information or the backoff counter value, or both. For example, the wireless control unit a6001 can notify the wireless communication unit a5003 of transmission decision information when the wireless channel state determination information indicates an idle state and the backoff counter value is 0. Furthermore, the wireless control unit a6001 can notify the wireless communication unit a5003 of transmission decision information when the wireless resource state determination information indicates an idle state.

[0137] Fig. 20 is a diagram showing an example of a sounding procedure in the wireless communication system according to this embodiment. Fig. 20 assumes that a wireless link (first wireless link) between the access point device 4001 and the station device 4002 has been established. The left side shows an example of the communication flow in the wireless link, and the right side shows an example of the state transition of timer a 5002-1 (also referred to as the first timer) included in the timer unit a 5002 of the station device 4002. Also, in Fig. 20, timer a 5002-1 is assumed to be in an inactive state (a 7101) at the start.

[0138] The access point device 4001 generates control information (first control information) including setting information for a timer a 5002-1 included in the station device 4002, conditions for transmitting a sounding frame from the station device 4002, and the like, and transmits a radio frame a 7001 including the control information to the station device 4002. The setting information for the timer a 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, and the like.

[0139] Upon receiving a radio frame a7001 containing first control information, the station device 4002 acquires the first control information contained in the radio frame a7001, sets the timer count initial value of the timer a5002-1 according to the first control information, and activates the timer (a7002). Activation a7002 resets the timer a5002-1 to its timer count initial value, transitions from the inactive state a7101 to the active state a7102, and begins countdown operation. The timer a5002-1 continues countdown while in the active state. Note that, in FIG. 20, an example has been described in which the setting of the timer count initial value of the timer a5002-1, resetting, activation, and countdown start are all performed simultaneously upon reception of the radio frame a7001. However, this is not limiting. For example, the setting and resetting of the timer count initial value, activation, and countdown start may each be triggered by a different radio frame (or the control information contained in the different radio frames).

[0140] 20, timer a 5002-1 is assumed to be a countdown timer, and an example has been described in which the timer count is reset to a preset initial value and reaches an expiration state when the count reaches 0, but this is not limiting, and for example, the timer count expiration value may be set separately to a value other than 0. Alternatively, timer 5002-1 may be configured as a count-up timer that is initialized to a count of 0 when reset and reaches an expiration state when the count reaches a preset timer count expiration value.

[0141] When the station device 4002 receives a radio frame (first radio frame) a7003 requiring a response and detects no errors in the radio frame a7003, it transmits an Ack frame a7004 as a response frame to the radio frame a7003, followed by a sounding frame a7005 (hereinafter, the sounding frame transmitted over the first radio link will also be referred to as the first sounding frame), and resets (a7006) the timer a5002-1 to its initial timer count value. The reset timer a5002-1 remains active (a7103) and starts counting down from its initial timer count value. Note that the timing of the reset of the timer a5002-1 (a7006) is not limited to the transmission of the sounding frame a7005, and can be set anywhere between the timing of transmitting the Ack frame a7004 and the timing of transmitting the sounding frame a7005, as long as the effect is not changed.

[0142] The radio frame requiring a response is not limited to a data frame, but may be a frame containing control information requiring a response. The transmission of the Ack frame a 7004 and the sounding frame a 7005 is preferably performed at an interval of SIFS, but this is not limitative and other IFSs used for high priority transmissions may be used. Furthermore, the Ack frame and the sounding frame may be transmitted concatenated. Alternatively, a new frame combining the Ack frame and the sounding frame may be defined and transmitted.

[0143] When receiving the radio frame a 7003, only if the count of the timer a 5002-1 has reached a predetermined value (or is less than or equal to the predetermined value), the sounding frame a 7005 may be transmitted and the timer a 5002-1 may be reset. In this case, if the timer a 5002-1 has not reached the predetermined value, i.e., if the time elapsed since the previous sounding frame transmission is less than the predetermined time, the transmission of the sounding frame is suppressed, thereby reducing the overhead caused by the sounding frame transmission.

[0144] The radio frame a 7003 may be a data frame for transmitting an A-MPDU in which multiple MPDUs are aggregated, and the Ack frame may be a BlockAck frame. When a BlockAck frame is used, the sounding frame a 7005 may be transmitted and the timer a 5002-1 may be reset only if the number or ratio of acknowledgments included in the BlockAck is less than a predetermined value. In this case, if the timer a 5002-1 has not expired and the radio link condition is good, the transmission of the sounding frame is suppressed, thereby reducing the overhead caused by the sounding frame transmission.

[0145] When the timer a 5002-1 reaches 0 and enters the expiration state (a 7104), the station device 4002 enters a sounding frame transmission standby state (a 7007). When the timer a 5002-1 expires, the station device a 4002 performs carrier sense to confirm that the wireless channel is in an idle state, and then starts the backoff procedure (a 7008). If the wireless channel is in an idle state during the backoff period, the station device 4002 transmits a sounding frame a 7009 and resets the timer a 5002-1 (a 7010). The timer a 5002-1 is reset to its initial timer count value, transitions to the active state, and starts countdown operation (a 7105).

[0146] When the station device 4002 receives a radio frame a 7011 including control information (fourth control information) including information such as setting and canceling the timer a 5002-1, the station device 4002 deactivates the timer a 5002-1 (a 7012). The deactivated timer a 5002-1 stops counting down and transitions to an inactive state a 7106.

[0147] Sounding frames a7005 and a7009 may be, for example, an NDP frame or a set of an NDP Announcement frame and an NDP frame, but are not limited to these and may be any frame that includes a signal that can estimate the channel between station device 4002 and access point device 4001.

[0148] The access point device 4001, which receives sounding frames a7005 and a7009 from the station device 4002, may, for example, perform channel estimation between the station device 4002 and the access point device 4001 based on the received sounding frames, and calculate a channel matrix, a beamforming matrix (beamforming filter), etc.

[0149] As a modified example, when the station device 4002 receives other control information (third control information) instead of receiving the first control information directly from the access point device 4001, the station device 4002 may generate information corresponding to the first control information based on the received control information. As an example, when receiving setting information related to QoS (Quality of Service), the station device 4002 may set an initial timer count value for timer a 5002-1 and then activate the timer (a 7002). The station device 4002 may change the initial timer count value based on the QoS requirements. When a short allowable delay time is set, the initial timer count value may be reduced. Furthermore, when a bit rate guarantee is set, the initial timer count value may be reduced. Furthermore, the station device 4002 may set the initial timer count value for timer a 5002-1 based on 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 running on the network. Furthermore, an application running on the network may obtain the QoS settings via the access point device 4002 .

[0150] As a modified example, when the fourth control information is received without being received directly from the access point device 4001, the station device 4002 may generate information corresponding to the fourth control information based on the received control information. As an example, when QoS-related setting information is received, the station device 4002 may deactivate timer a 5002-1 (a 7012). When the allowable delay time is set to a long time, timer a 5002-1 may be deactivated. Furthermore, when the bit rate setting is set to best effort, timer a 5002-1 may be deactivated.

[0151] As a modified example, Fig. 21 shows an example of a sounding procedure in which the timer unit 5002 of the station device 4002 includes a timer a 5002-2 (also referred to as a third timer) in addition to a timer a 5002-1 (first timer). The following description will focus on differences from the example of the sounding procedure in Fig. 20, and will omit a description of similar parts. Also, parts corresponding to those in Fig. 20 will be described using the same reference numerals.

[0152] 21 assumes that a wireless link (first wireless link) between the access point device 4001 and the station device 4002 has been established, with the left side showing an example of the communication flow over the wireless link and the right side showing an example of the state transitions of timers a5002-1 and a5002-2 provided in the timer unit a5002 of the station device 4002. Also, in FIG. 21, timers a5002-1 and a5002-2 are assumed to be inactive (a7101, a7201) at the start.

[0153] 20 , the first control information included in the wireless frame a7001 transmitted from the access point device 4001 to the station device 4002 is generated to include setting information for the timer a5002-2 in addition to setting information for the timer a5002-1 and sounding frame transmission conditions from the station device 4002, and the wireless frame a7001 including the control information is transmitted to the station device 4002. The setting information for the timer a5002-1 and the timer a5002-2 may include timer count initial values, timer count expiration values, timer activation instruction information, timer reset instruction information, timer reset timing information, etc. for each timer. Here, each setting information may be selected so that the time until timer a5002-2 expires is shorter than the time (count number) until timer a5002-1 expires.

[0154] Upon receiving radio frame a7001 containing first control information, station device 4002 acquires the first control information contained in radio frame a7001, sets the timer count initial values ​​of timers a5002-1 and a5002-2 according to the first control information, and activates both timers (a7002, a7202). Activation a7002 resets timers a5002-1 and a5002-2 to their timer count initial values, transitions them from inactive state a7101 and inactive state a7201 to active state a7102 and active state a7202, respectively, and begins countdown operation. Timers a5002-1 and a5002-2 continue counting down while in the active state. In addition, in Figure 21, an example has been described in which the setting, resetting, activation, and countdown start of timer count initial values ​​of timers a5002-1 and a5002-2 are performed all at once upon receiving radio frame a7001, but this is not limited to this. For example, the setting and resetting of timer count initial values, activation, and countdown start may each be triggered by a different radio frame (or the control information contained therein).

[0155] 21, timer a 5002-1 and timer a 5002-2 are assumed to be countdown timers, and an example has been described in which they are reset to a preset timer count initial value and reach an expiration state at a count of 0, but this is not limiting, and for example, the timer count expiration value may be set separately to a value other than 0. Alternatively, timer a 5002-1 and timer a 5002-2 may be configured as count-up timers that are initialized to a count of 0 by reset and reach an expiration state when the count reaches a preset timer count expiration value.

[0156] When the station device 4002 receives a radio frame (first radio frame) a7003 that requires a response and no error is detected in the radio frame a7003, it transmits an Ack frame a7004 as a response frame to the radio frame a7003. At this time, if the timer a5002-2 has not yet expired (if it is in the active state), the sounding frame a7005 is not transmitted following the Ack frame a7004, unlike the example in Fig. 20. At this time, the timer a5002-1 is not reset, and the timers a5002-1 and a5002-2 continue to be active.

[0157] If the active state continues, the timer a 5002-2 will reach a count of 0 earlier than the timer a 5002-1 and transition to the expired state (a 7203). At this time, the timer a 5002-2 will display the fact that it has reached the expired state (a 7051).

[0158] When the station device 4002 receives a radio frame a7051 requiring a response and detects no errors in the radio frame a7051, it transmits an Ack frame a7052 as a response frame to the radio frame a7051. If the timer a5002-2 has expired (a7203) at this time, it transmits a sounding frame a7053 following the Ack frame a7052 and resets the timers a5002-1 and a5002-2 to their initial timer count values ​​(a7054). The reset timers a5002-1 and a5002-2 enter the active state (a7103, a7204) and begin counting down from their initial timer count values. In addition, the timing of resetting (a7054) timer a5002-1 and timer a5002-2 is not limited to the time of transmitting sounding frame a7053, but can be set within a range that does not change the effect, such as between the timing of transmitting Ack frame a7052 and the timing of transmitting sounding frame a7053.

[0159] The radio frame requiring a response is not limited to a data frame, but may be a frame containing control information requiring a response. The transmission of the Ack frame a 7052 and the sounding frame a 7053 is preferably performed at an interval of SIFS, but this is not limitative and other IFSs used for high priority transmissions may be used. Furthermore, the Ack frame and the sounding frame may be transmitted concatenated. Alternatively, a new frame combining the Ack frame and the sounding frame may be defined and transmitted.

[0160] The radio frame a 7051 may be a data frame for transmitting an A-MPDU in which multiple MPDUs are aggregated, and the Ack frame may be a BlockAck frame. When a BlockAck frame is used, the sounding frame a 7053 may be transmitted and the timers a 5002-1 and a 5002-2 may be reset only if the number or ratio of acknowledgments included in the BlockAck is less than a predetermined value. In this case, if the timer a 5002-1 has not expired and the radio link condition is good, the transmission of the sounding frame is suppressed, thereby reducing the overhead caused by the sounding frame transmission.

[0161] The station device 4002 indicates that timer a5002-2 has counted down to 0, indicating an expiration state (a7205) (a7055), and when timer a5002-1 has counted down to 0, indicating an expiration state (a7104), the station device 4002 enters a sounding frame transmission standby state (a7007). When timer a5002-1 expires, the station device 4002 performs carrier sense to confirm that the wireless channel is in an idle state, and then initiates a backoff procedure (a7008). If the wireless channel remains in an idle state during the backoff period, the station device 4002 transmits a sounding frame a7009 and resets timers a5002-1 and a5002-2 (a7010). Timers a5002-1 and a5002-2 are reset to their initial timer count values, transition to the active state, and begin countdown operations (a7105, a7206).

[0162] Unlike the example of FIG. 20 , the fourth control information included in the wireless frame a7011 transmitted from the access point device 4001 to the station device 4002 may include information such as deactivating the setting of timer a5002-2 in addition to information such as deactivating the setting of timer a5002-1. Note that the deactivation information for timer a5002-2 may be the same information as the deactivation information for timer a5002-1. When the station device 4002 receives the wireless frame a7011 including the fourth control information, it deactivates timers a5002-1 and a5002-2 (a7012). The deactivated timers a5002-1 and a5002-2 stop counting down and transition to the inactive states a7106 and a7207.

[0163] As a modified example, the station device 4002 may not directly receive the first control information from the access point device 4001, but may instead generate information corresponding to the first control information based on the received control information when it receives other control information. As an example, when it receives QoS-related setting information, the station device 4002 may set the timer count initial values ​​of timer a 5002-1 and timer a 5002-2 and then activate them (a 7002). The station device 4002 may change the timer count initial values ​​based on the QoS requirements. When a short allowable delay time is set, the timer count initial values ​​may be reduced. When a bit rate guarantee is set, the timer count initial values ​​may be reduced. The station device 4002 may also set the timer count initial values ​​of timer a 5002-1 and timer a 5002-2 based on the capability information exchanged with the access point device 4001. The QoS settings may be set by the access point device 4001 according to the current traffic situation, or by an application running on the network. Furthermore, an application running on the network may obtain the QoS settings via the access point device 4002 .

[0164] As a modified example, when the fourth control information is received without being received directly from the access point device 4001, the station device 4002 may generate information corresponding to the fourth control information based on the received control information. As an example, when QoS-related setting information is received, the station device 4002 may deactivate timer a5002-1 and timer a5002-2 (a7012). When the allowable delay time is set to a long time, timer a5002-1 and timer a5002-2 may be deactivated. Furthermore, when the bit rate setting is set to best effort, timer a5002-1 and timer a5002-2 may be deactivated.

[0165] FIG. 22 shows a flowchart of an example of a sounding procedure in the station device 4002 when the timers a 5002-1 and a 5002-2 are used.

[0166] When the station device 4002 transmits an Ack frame (Yes in step S9001), it checks whether the timer a 5002-2 has expired (step S9002). If the timer a 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 a 5002-1 and a 5002-2 (step S9004), and returns to step S9001.

[0167] If the answer is No in step S9001, it is checked whether timer a 5002-1 has expired (step S9005). If timer a 5002-1 has not expired (No in step S9005), the process returns to step S9001. If timer a 5002-1 has expired (Yes in step S9005), carrier sense is performed (step S9006), a backoff procedure is performed (step S9007), a sounding frame is transmitted (step S9008), timers a 5002-1 and a 5002-2 are reset (step S9009), and the process returns to step S9001. Although not shown, if the wireless channel becomes busy during the carrier sense and backoff procedure, a retry is performed from step S9006, but if a wireless frame to be received is detected, the process returns to step S9001.

[0168] Next, as a modified example, an example will be described in which the access point device 4001 and the station device 4002 support multi-link operation (MLO), in which communication is performed simultaneously using two wireless links: a first wireless link and a second wireless link that uses a frequency band (or frequency channel) different from that of the first wireless link. Note that MLO is not limited to two wireless links, and multiple wireless links in different frequency bands (or frequency channels) can be used.

[0169] A multi-link device (MLD) is a device capable of multi-link communication through multi-link operation, and an access point device that supports MLO will be referred to as an MLD access point device, and a station device that supports MLO will be referred to as an MLD station device. Furthermore, MLD access point devices and MLD station devices will also be collectively referred to as MLD wireless communication devices. In this embodiment, the wireless communication devices 4001-1, 4001-2, 4002A, and 4002B described above will be described as MLD wireless communication devices, but in actual operation, not all wireless communication devices in a wireless communication system will necessarily support MLO.

[0170] The MLD access point device a10001 and the MLD station device a10002 will be described using FIG. 23. The MLD wireless communication device is composed of multiple sub-wireless communication devices corresponding to the frequency bands (or frequency channels) of each wireless link (also referred to as a physical layer link) that constitutes the multilink. Each sub-wireless communication device may support all frequency bands (and frequency channels) supported by the MLD wireless communication device, or each may support only one of the frequency bands (or frequency channels). FIG. 23 shows an example in which the MLD access point device a10001 is composed of two sub-wireless communication devices, in this case, two sub-access point devices a10001-1 and a10001-2, and a multilink control unit a10011. However, the number of sub-access point devices may be any number greater than or equal to two. Note that, hereinafter, when any one of the multiple sub-access point devices is described as a representative, it will be referred to as the sub-access point device a10001-N. 23 shows an example in which the MLD station device a10002 is similarly configured with two sub-wireless communication devices, in this case two substation devices a10002-1 and a10002-2, and a multi-link control unit a10012, but the number of substation devices may be any number greater than or equal to two. Note that, hereinafter, when describing any one of the multiple substation devices as a representative, it will be referred to as substation device a10002-N. Furthermore, the sub-wireless communication devices (sub-access point devices and substation devices) may be configured with some circuits within the wireless communication device, and may be referred to as sub-wireless communication units (sub-access point units, substation units).

[0171] 23 shows an example in which multiple sub-wireless communication devices are configured as logically separate blocks, but they may be physically configured as a single wireless communication device. Alternatively, multiple sub-wireless communication devices may be configured as physically separate devices. In this embodiment, a case in which each sub-wireless communication device is configured as a physically separate device will be described as an example.

[0172] The number of sub-access point devices included in one MLD access point device and the number of substation devices included in one MLD station device may vary depending on the grade, class, capabilities, etc. of each MLD wireless communication device. The higher the grade, class, and capabilities of an MLD wireless communication device, the greater the number of sub-wireless communication devices (sub-access point devices, substation devices) it may have. In other words, for each MLD wireless communication device present in a wireless communication system, the sub-wireless communication devices (sub-access point devices, substation devices) that make up each MLD wireless communication device may differ depending on the grade, class, capabilities, etc., and the numbers of these devices do not have to be the same.

[0173] The substation apparatus a10002-1 connects (associates) with the sub-access point apparatus a10001-1 and establishes a wireless link a10003-1 (first wireless link). The substation apparatus a10002-2 connects to the sub-access point apparatus a10001-2 and establishes a wireless link a10003-2 (second wireless link).

[0174] The configuration of the sub-access point device a10001-N in Fig. 23 is the same as the configuration of the access point device 4001 in Fig. 19, except that a multi-link control unit a10011 is connected to the wireless control unit a6001 of each sub-access point device a10001-N. The multi-link control unit a10011 controls the wireless links for each sub-access point device a10001-N and exchanges control information and transmitted / received data with each sub-access point device a10001-N. The multi-link control unit a10011 distributes transmitted data frames to the sub-access point devices a10001-1 and a10001-2, i.e., the wireless links a10003-1 and a10003-2, and aggregates received data frames from the sub-access point devices a10001-1 and a10001-2, i.e., the wireless links a10003-1 and a10003-2.

[0175] On the other hand, the configuration of the substation equipment a10002-N in Fig. 23 is the same as the configuration of the station equipment 4002 in Fig. 18, except that the multilink control unit a10012 is connected to the wireless control unit a5001 of each substation equipment a10002-N. The multilink control unit a10012 controls the wireless links for each substation equipment a10002-N and exchanges control information and transmitted / received data with each substation equipment a10002-N. The multilink control unit a10012 distributes transmitted data frames to each substation equipment a10002-1 and a10002-2, i.e., each wireless link a10003-1 and a10003-2, and aggregates received data frames from each substation equipment a10002-1 and a10002-2, i.e., each wireless link a10003-1 and a10003-2.

[0176] In the following description, for the sake of simplicity, an example will be described in which the wireless links constituting the multilink are two, wireless link a10003-1 (first wireless link) and wireless link a10003-2 (second wireless link), but this is not limited to this and the present invention can be similarly applied to cases in which the number of wireless links is three or more. Furthermore, an example will be described in which the frequency band of the first wireless link is 2.4 GHz and the frequency band of the second wireless link is 5 GHz, but the frequency band used by each wireless link can be set arbitrarily from frequency bands (or frequency channels) supported by the wireless communication system, such as the 2.4 GHz band, 5 GHz band, 6 GHz band, and 60 GHz band, and these may change according to the laws and regulations of each country.

[0177] An example of a sounding procedure in this modified example will be described below. The operations in each wireless link are the same as those in the case of one wireless link shown in FIG. 20. That is, in the first wireless link, sub-access point device a10001-1 performs the same operation as access point device 4001 in FIG. 20, and substation device a10002-1 performs the same operation as station device 4002 in FIG. 20. In the second wireless link, sub-access point device a10001-2 performs the same operation as access point device 4001 in FIG. 20, and substation device a10002-2 performs the same operation as station device 4002 in FIG. 20. Here, the timer provided in the timer unit a5002 of the substation device a10002-1 will be referred to as timer a5002-1 (first timer), as in Fig. 20, and the timer provided in the timer unit a5002 of the substation device a10002-2 will be referred to as timer a5002-3 (second timer). The following will mainly explain the differences from the example of the sounding procedure in Fig. 20, and will omit explanations of similar points.

[0178] The operation of the first wireless link is the same as that shown in Fig. 20, and therefore a description thereof will be omitted. In the second wireless link, when the substation apparatus a10002-2 receives from the sub-access point apparatus a10001-2 a wireless frame a7001-2 (replace a7001 in Fig. 20; the same applies below) containing second control information including setting information for the timer a5002-3 and sounding frame transmission conditions from the substation apparatus a10002-2, the substation apparatus a10002-2 sets an initial timer count value for the timer a5002-3 and activates the timer (a7002-2). The setting information for the timer a5002-3 may include an initial timer count value, a timer count expiration value, timer activation instruction information, timer reset instruction information, timer reset timing information, and the like. Activation a7002-2 resets timer a5002-3 to its timer count initial value, transitions from inactive state a7101-2 to active state a7102-2, and starts counting down. Timer a5002-3 continues counting down while in the active state. Note that, although an example has been described in which reception of radio frame a7001-2 causes timer a5002-3 to perform the setting of the timer count initial value and the like, resetting, activation, and countdown start all at once, this is not limitative. For example, the setting and resetting of the timer count initial value and the like, activation, and countdown start may each be triggered by a different radio frame (or control information contained in the radio frame).

[0179] Also, the timer a 5002-3 is assumed to be a countdown timer, and an example has been described in which it is reset to a preset timer count initial value and reaches an expiration state when the count reaches 0, but this is not limiting, and for example, the timer count expiration value may be set separately to a value other than 0. Alternatively, the timer a 5002-3 may be configured as a count-up timer that is initialized to a count of 0 when reset and reaches an expiration state when the count reaches a preset timer count expiration value.

[0180] When the substation apparatus a10002-2 receives a wireless frame (second wireless frame) a7003-2 requiring a response and detects no errors in the wireless frame a7003-2, it transmits an Ack frame a7004-2 as a response frame to the wireless frame a7003-2, and then transmits a sounding frame a7005-2 (hereinafter, the sounding frame transmitted over the second wireless link will also be referred to as the second sounding frame), and resets the timer a5002-3 to its initial timer count value (a7006-2). The reset timer a5002-3 remains active (a7103-2) and starts counting down from its initial timer count value. The timing of resetting timer a5002-3 (a7006-2) is not limited to the time when sounding frame a7005-2 is transmitted, but can be set within a range that does not change the effect, such as between the time when Ack frame a7004-2 is transmitted and the time when sounding frame a7005-2 is transmitted.

[0181] The radio frame requiring a response is not limited to a data frame, but may be a frame containing control information requiring a response. The transmission of the Ack frame a 7004-2 and the sounding frame a 7005-2 is preferably performed at an interval of SIFS, but this is not limitative and other IFSs used for high priority transmissions may be used. Furthermore, the Ack frame and the sounding frame may be linked and transmitted. Alternatively, a new frame combining the Ack frame and the sounding frame may be defined and transmitted.

[0182] When receiving radio frame a 7003-2, sounding frame a 7005-2 may be transmitted and timer a 5002-3 may be reset only if the count of timer a 5002-3 has reached a predetermined value (or is less than the predetermined value). In this case, sounding frame transmission is suppressed when timer a 5002-3 has not reached the predetermined value, i.e., when the elapsed time since the previous sounding frame transmission is less than the predetermined time, thereby reducing the overhead caused by sounding frame transmission.

[0183] The radio frame a 7003-2 may be a data frame transmitting an A-MPDU in which multiple MPDUs are aggregated, and the Ack frame may be a BlockAck frame. When a BlockAck frame is used, the sounding frame a 7005-2 may be transmitted and the timer a 5002-3 may be reset only if the number or ratio of acknowledgments included in the BlockAck is less than a predetermined value. In this case, if the timer a 5002-3 has not expired and the radio link condition is good, the transmission of the sounding frame is suppressed, thereby reducing the overhead caused by the sounding frame transmission.

[0184] When the timer a5002-3 reaches 0 and enters the expiration state (a7104-2), the substation apparatus a10002-2 enters a sounding frame transmission standby state (a7007-2). When the timer a5002-3 expires, the substation apparatus a10002-2 performs carrier sense to confirm that the wireless channel is in an idle state, and then starts the backoff procedure (a7008-2). If the wireless channel is in an idle state during the backoff period, the substation apparatus a10002-2 transmits a sounding frame a7009-2 and resets the timer a5002-3 (a7010-2). The timer a5002-3 is reset to its initial timer count value, transitions to the active state, and starts countdown operation (a7105-2).

[0185] When the substation device a10002-2 receives a radio frame a7011-2 including control information (sixth control information) including information such as setting and canceling timer a5002-3, the substation device a10002-2 deactivates timer a5002-3 (a7012-2). The deactivated timer a5002-3 stops counting down and transitions to an inactive state a7106. Note that when the substation device a10002-1 receives the fourth control information over the first radio link, the substation device a10002-2 may also deactivate timer a5002-3. Also, when the substation device a10002-2 receives the sixth control information over the second radio link, the substation device a10002-1 may also deactivate timer a5002-1.

[0186] As a modified example, when the substation device a10002-2 receives other control information (fifth control information) instead of receiving the second control information directly from the sub-access point device a10001-2, the substation device a10002-2 may generate information corresponding to the second control information based on the received control information. For example, when receiving QoS-related setting information, the substation device a10002-2 may set an initial timer count value for the timer a5002-3 and then activate the timer (a7002-2). The substation device a10002-2 may change the initial timer count value based on the QoS requirements. When a short allowable delay time is set, the initial timer count value may be reduced. When a bit rate guarantee is set, the initial timer count value may be reduced. The substation device a10002-2 may also set the initial timer count value for the timer a5002-3 based on the capability information exchanged with the sub-access point device a10001-2. The QoS settings may be set by the sub-access point device a 10001-2 depending on the current traffic situation, or may be set by an application running on the network. Alternatively, the application running on the network may obtain the QoS settings via the sub-access point device a 10001-2.

[0187] As a modified example, when the sixth control information is not received directly from the sub-access point device a10001-2 but other control information is received, the substation device a10002-2 may generate information corresponding to the sixth control information based on the received control information. As an example, when QoS setting information is received, the substation device a10002-2 may deactivate the timer a5002-3 (a7012-2). When the allowable delay time is set to a long time, the timer a5002-3 may be deactivated. Furthermore, when the bit rate setting is set to best effort, the timer a5002-3 may be deactivated.

[0188] Furthermore, the substation apparatus a10002-2 connected to the sub-access point apparatus a10001-2 may be equipped with multiple timers for sounding control. This substation apparatus a10002-2 may be equipped with a second timer and a fourth timer, as well as the first timer and the third timer, and may be configured not to transmit a sounding frame if the fourth timer has not yet expired when transmitting a response frame. Furthermore, this substation apparatus a10002-2 may be configured to perform carrier sensing when the second timer expires to confirm that the wireless channel of the second link is in an idle state, and then perform backoff processing to transmit a sounding frame. After transmitting the sounding frame, this substation apparatus a10002-2 may reset the second timer and the fourth timer. The time until the fourth timer expires may be set to be shorter than the time until the second timer expires.

[0189] When configured as MLD, when a station device receives control information for changing settings such as a timer count initial value on one of its active links, it may activate or deactivate the timer for the active links other than the link on which it received this control information. Also, when it receives setting information related to QoS on one of its active links, it may activate or deactivate the timer for the active links other than the link on which it received the QoS information.

[0190] According to the method described above, it is possible to maintain good communication quality of the wireless link in wireless communication.

[0191] As a next modified example, an example of a configuration is shown below in which information for setting a required communication quality is exchanged between multiple station devices, the quality of multiple wireless links is measured between the station devices that have exchanged the information for setting the required communication quality, and an attempt is made to secure a transmission opportunity (TXOP) for one of the multiple wireless links based on the measured wireless link quality. The configurations of the station device and access point device are shown in Figures 4 and 18, but are not limited to these.

[0192] FIG. 24 shows an example of a flow in which a required communication quality is set when two bands (Band1, Band2) are used between a first station device (STA1) and a second station device (STA2), STA1 measures the quality of the wireless links in the two bands, and attempts to secure a transmission opportunity via the wireless link selected based on the measured wireless link quality. Reference numeral a11001 denotes a message containing link quality setting request information transmitted from STA2 to STA1. This message includes information indicating that the link quality is set to use Band1 and Band2. The method for setting the link quality is not particularly limited. For example, the communication quality determined by information regarding latency may be used. Alternatively, when a wireless frame for transmission is generated by a station device, the link quality may be determined based on the period from the time a protocol data unit (MPDU) generated at the MAC layer to the time the generated MPDU is actually transmitted as a wireless frame. Alternatively, the link quality may be determined based on the period from the time an MPDU is generated by one station device, the MPDU is transmitted as a wireless frame, the other station device receives the wireless frame, and the MPDU is extracted from the MAC layer. Alternatively, one of the station devices may generate an MPDU and determine the quality of communication based on the period from the time the wireless frame is transmitted to the time the wireless frame containing the corresponding acknowledgment is received. In this case, the mechanism used in Fine Timing Measurement (FTM) may be used to measure the round-trip time between stations, and the communication quality may be measured based on this round-trip time. In FTM, one STA (initiator) sends a Fine Timing Measurement Request frame to another STA (responder), and receives a Fine Timing Measurement Response frame returned from the responder STA that received the Fine Timing Measurement Request frame.At this time, the round trip time can be calculated from the timing when the Fine Timing Measurement Request frame is sent and the timing when the Fine Timing Measurement Response frame is received. This FTM is specified in the IEEE 802.11-2020 specification, and this mechanism can be used, but if a mechanism that can measure round trip time with higher accuracy is specified in the future, that mechanism can also be used.

[0193] Various methods can be used to set the required communication quality. For example, when a certain communication quality is specified, the communication quality may be satisfied if the period associated with the communication quality is shorter than the period corresponding to the specified communication quality. Furthermore, instead of only one communication quality being specified, at least one of multiple communication qualities may be specified. For example, multiple communication qualities may be set, such as a round-trip time of 2 milliseconds or less for time synchronization, a round-trip time of 5 milliseconds or less for real-time sensing, and a round-trip time of 10 milliseconds or less for real-time video transmission. Furthermore, instead of the round-trip time, the required communication quality may be set based on other time indicators, such as the period from the time an MPDU is generated to the time it is actually transmitted as a wireless frame, or the period from the time an MPDU is generated by one station device to the time a wireless frame including an acknowledgment is received.

[0194] Alternatively, link quality may be measured using the CCA (Clear Channel Assessment) function of the wireless link. For example, the received power of a wireless link may be measured for a predetermined period of time, and 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 the CCA function determines the wireless link to be idle. The time for measuring communication quality may not be limited to a fixed period of time, but may be variable. Communication quality may be measured based on the percentage of time determined to be busy or the percentage of time determined to be idle. For example, communication quality may be defined as being suitable for transmitting ultra-high definition (UHD) images when the percentage of time a wireless link is idle exceeds 50%, and communication quality may be defined as being suitable for real-time sensing when the percentage of time a wireless link is idle is 20% or less.

[0195] Alternatively, link quality may be measured by transmitting a sounding frame over the wireless link and receiving a sounding report for the sounding frame. A sounding frame containing an NDP and an NDP announcement may be transmitted to receive a sounding report. 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 state information, or the like. A station device that receives the report may determine whether the wireless link satisfies a predetermined quality level based on whether the reported received power exceeds a predetermined threshold. Instead of using only one threshold, multiple thresholds may be used to express communication quality in multiple stages.

[0196] The communication quality setting may be expressed by one index or a combination of multiple indexes. For example, the communication quality for real-time sensing may be expressed using multiple indexes, such as a round-trip time of 5 milliseconds or less and a wireless link idle rate of 50% or more, and the wireless quality for UHD video transmission may be expressed using multiple indexes, such as a round-trip time of 10 milliseconds or less, a wireless link busy rate of 20% or more, and a received power of -70 dBm or more. A wireless medium may be secured when at least one of these indexes is satisfied.

[0197] Message a11002 includes link quality setting response information. If STA1 accepts the communication quality specified in the link quality setting request information, it includes accept in the link setting response information. If STA1 does not accept the communication quality specified in the link quality setting request information, it includes deny or reject in the link setting response information and sends it to STA2. When STA1 includes accept in the link setting response information and sends it, if STA1 requires a different link quality than the link quality specified by STA2, STA1 may send message a11002 including link quality setting response information to STA2, along with accept, along with information indicating the link quality requested by STA1. Furthermore, when sending a message including link quality setting response information including deny or reject, STA1 may also include information indicating the reason, such as a reason code, and send it to STA2. The following explanation will be given assuming that STA1 accepts the quality information specified in the link quality setting request information and sends link setting response information including accept to STA1 to STA2.

[0198] STA1, which has sent link setup response information including "accept" to STA2, begins measuring the quality of the wireless link using Band1 and the wireless link using Band2. Below, we will explain the case where sounding frames are used as the wireless link measurement method, but this is not limited to this; other wireless link measurement methods may be used, or measurement using sounding frames may be used in combination with other wireless link quality measurement methods. STA1 transmits sounding frame a11003 to STA2 in Band1. STA2, which receives sounding frame a11003 in Band1, transmits sounding report a11004 to STA1 in Band1. Also, STA1 transmits sounding frame a11005 to STA2 in Band2, around the time of transmitting sounding frame a11003. STA2, which receives sounding frame a11005 in Band2, transmits sounding response frame a11006 to STA1 in Band2. 24 illustrates STA1 transmitting sounding frame a11003 in Band 1 and then transmitting sounding frame a11005 in Band 2, but this is not limiting. STA1 may transmit sounding frame a11005 in Band 2 before transmitting sounding frame a11003 in Band 1, or STA1 may simultaneously transmit sounding frame a11003 in Band 1 and sounding frame a11005 in Band 2. STA1 obtains information regarding the received power of Band 1 and information regarding the received power of Band 2 from the received sounding reports a11004 and a11006, and measures the communication quality of Band 1 and Band 2. As an example of measuring communication quality, it may be determined whether the received power of Band 1 or Band 2 is higher than the received power set as the link quality, and the band that is higher may be determined to satisfy the set link quality.

[0199] STA1 periodically measures link quality in Band 1 and Band 2. In Fig. 24, STA1 transmits sounding frames a11007 and a11013 in Band 1 and also transmits sounding frames a11009 and a11015 in Band 2, and STA1 receives sounding reports a11008 and a11014 in Band 1 and sounding reports a11010 and a11016 in Band 2. If STA1 transmits sounding frames a11007 and a11009 and measures the link quality, and determines that the link quality in Band 1 satisfies the set communication quality, and a transmission request occurs, STA1 attempts to secure a wireless medium a11011 in Band 1, and if it is able to secure a wireless medium in Band 1, it transmits data frame a11012 to STA2. As a variant, if STA1 measures the communication quality and finds that the set communication quality is not met for both Band 1 and Band 2, it may select a band with better communication quality. Next, when STA1 transmits sounding frames a11013 and a11015 and measures the link quality, and determines that the link quality of Band 2 meets the set communication quality, and a transmission request occurs, STA1 attempts to secure a wireless medium in Band 2 a11017, and once the wireless medium in Band 2 is secured, it transmits data frame a11018 to STA2.

[0200] As described above, one or more timers may be used to manage the link quality measurement interval. As an example, a first timer corresponding to Band 1 and a second timer corresponding to Band 2 may be provided. After receiving a link quality setting request a11001, the first and second timers may be started. When the first timer expires, a sounding frame a11003 may be transmitted in Band 1 and the first timer may be reset. When the second timer expires, a sounding frame a11005 may be transmitted in Band 2 and the second timer may be reset. When a sounding frame a11007 is transmitted in Band 1 before the first timer expires, the first timer may be reset. When a sounding frame a11009 is transmitted in Band 2 before the second timer expires, the second timer may be reset. Instead of transmitting sounding frames, link quality may be measured by other methods. For example, link quality may be measured by transmitting a frame for round-trip measurement, such as a Fine Timing Measurement request frame.

[0201] When communication between STA1 and STA2 with the communication quality set is no longer necessary, the communication quality setting may be canceled. In FIG. 24 , STA2 transmits a communication quality setting cancellation request a11019 to STA1 in Band 1, and STA1, upon receiving the request, transmits a communication setting cancellation response a11020 to STA2 in Band 1, thereby canceling the communication quality setting between STA1 and STA2. The band for transmitting the communication quality setting cancellation request a11019 and the communication setting cancellation response a11020 is not limited to Band 1, and may be Band 2, or the communication quality setting cancellation request a11019 and the communication setting cancellation response a11020 may be transmitted in different bands. Furthermore, the station device that transmits the communication quality setting cancellation request a11019 is not limited to STA2; STA1 may also transmit the communication quality setting cancellation request a11019 to cancel the communication quality setting.

[0202] Next, a modified example in which communication quality between STA1 and STA2 is set via an AP will be described using FIG. 25 . Messages and the like common to FIG. 24 are numbered the same as in FIG. 24 , and their description will be omitted. FIG. 25 shows an example in which STA2 sets communication quality between STA1 and STA1 via an AP. Reference numeral a12001 denotes a communication quality setting request that STA2 sends to the AP using Band 1, and this communication quality setting request includes information indicating that the communication quality setting is between STA1 and STA2. Upon receiving communication quality setting request a12001, the AP sends communication quality setting request a12002 to STA1 over Band 1. The communication quality setting request a12002 includes information indicating that the communication quality setting is between STA1 and STA2. Upon receiving communication quality setting request a12002, STA1 sends communication quality setting response a12003 to the AP over Band 1. This communication quality setting response a12003 includes information on the communication quality setting between STA1 and STA2, as well as information on the response to the communication quality setting request (accept, deny, reject, reason code, etc.). The AP that received the communication quality setting response a12003 transmits a communication quality setting response a12004 to STA2 on Band1. This communication quality setting response a12004 includes information on the communication quality setting between STA1 and STA2, as well as information on the response to the communication quality setting request (accept, deny, reject, reason code, etc.). The communication quality can be set using the above procedure. Messages for setting the communication quality can be sent and received using Band2 instead of Band1, and different bands can be used between STA1 and the AP and between STA2 and the AP.

[0203] Next, the flow for canceling the communication quality setting will be described. STA2 transmits a communication quality setting cancellation request 12005 to the AP over Band 2. This communication quality setting cancellation request a12005 includes information for requesting cancellation of the communication quality setting between STA1 and STA2. Upon receiving the communication quality setting cancellation request a12005, the AP transmits a communication quality setting cancellation request a12006 to STA1 over Band 2. This communication quality setting cancellation request a12006 includes information for requesting cancellation of the communication quality setting between STA1 and STA2. Upon receiving the communication quality setting cancellation request a12006, STA1 transmits a communication quality setting cancellation response a12007 to the AP over Band 2. This communication quality setting cancellation response a12007 includes information confirming that the communication quality setting between STA1 and STA2 will be cancelled. Upon receiving the communication quality setting cancellation response a12007, the AP transmits a communication quality setting cancellation response a12008 to STA2 over Band 2. This communication quality setting cancellation response a12008 includes information confirming that the communication quality setting between STA1 and STA2 will be cancelled. The above procedure makes it possible to cancel the communication quality setting. The message for cancelling the communication quality setting is not limited to Band2, but Band1 may also be used for sending and receiving the message. Also, different bands may be used between STA1 and the AP and between STA2 and the AP.

[0204] So far, we have shown an example of using two wireless links (bands) and attempting to secure a wireless medium using one of the bands. However, this is not limiting; the system may be configured to attempt to secure a wireless medium using one or more bands from three or more bands. For example, if there are two wireless links among three bands that satisfy the set communication quality (two bands that satisfy the communication quality), an attempt may be made to secure a wireless medium using each of the two bands. If the wireless medium is successfully secured using the two bands, data frames may be transmitted using both bands. The payloads of the data frames transmitted using the two bands may contain the same data, or data frames with different payloads may be transmitted. Sending payloads containing the same data using the two bands can improve reliability, while sending payloads containing different data using the two bands can improve communication speed.

[0205] As described above, by setting the communication quality between STA1 and STA2, measuring the quality of multiple wireless links, and controlling the system to attempt to acquire the wireless medium via a wireless link that satisfies the communication quality, it is possible to improve communication efficiency. [2. Common to all embodiments]

[0206] A communication device according to an embodiment of the present invention can communicate in a frequency band (frequency spectrum) that does not require permission to use from a country or region, which is called an unlicensed band, but the usable frequency band is not limited to this. The communication device according to an embodiment of the present invention can also be effective in a frequency band called a white band (e.g., a frequency band allocated for television broadcasting but unused in some regions) that is not actually used despite permission to use it for a specific service from a country or region for the purpose of preventing interference between frequencies, or in a shared spectrum (shared frequency band) that is expected to be shared by multiple operators.

[0207] A program running on a wireless communication device according to one aspect of the present invention is a program that controls a CPU and other components (a program that causes a computer to function) to implement the functions of the above-described embodiment according to one aspect of the present invention. Information handled by these devices is temporarily stored in RAM during processing, and then stored in various ROMs or HDDs, where it is read, modified, and written by the CPU as needed. Recording media for storing the program may include semiconductor media (e.g., ROM, non-volatile memory cards, etc.), optical recording media (e.g., DVDs, MOs, MDs, CDs, BDs, etc.), and magnetic recording media (e.g., magnetic tapes, flexible disks, etc.). Executing a loaded program not only implements the functions of the above-described embodiment, but may also implement the functions of the present invention by processing in cooperation with an operating system or other application programs based on instructions from the program.

[0208] Furthermore, when distributing the program on the market, the program can be stored and distributed on a portable recording medium or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer also falls within one aspect of the present invention. Furthermore, part or all of the communication device in the above-described embodiments may be realized as an LSI, which is typically an integrated circuit. Each functional block of the communication device may be individually formed into a chip, or part or all of the functional blocks may be integrated into a chip. When each functional block is formed into an integrated circuit, an integrated circuit control unit that controls them is added. Needless to say, downloading programs and setting information from a server computer to implement at least part of the functions of the above-described embodiments also falls within one aspect of the present invention.

[0209] Furthermore, the method of integration is not limited to LSI, but may be realized by a dedicated circuit or a general-purpose processor. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, it may also be possible to use an integrated circuit based on that technology.

[0210] It should be noted that the present invention is not limited to the above-described embodiments. The wireless communication device of the present invention is not limited to application to mobile station devices, but can of course be applied to stationary or non-mobile electronic devices installed indoors or outdoors, such as AV equipment, kitchen equipment, cleaning / washing appliances, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0211] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included in the scope of the claims.

[0212] One aspect of the present invention is suitable for use in a wireless communication device and a wireless communication method.

[0213] 3001 NDP Announcement frame 3002 NDP frame 3003 Compressed Beamforming / CQI frame 4001-1, 4001-2 Wireless communication device (access point device) 4002-1 to 4002-6 Wireless communication device (station device) 4003-1, 4003-2 Wireless communication system 5001 Wireless control unit 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 7001, 8001 Integrated access point device 7002, 8002 Route selection unit 7003-1 to 7003-3, 8003-1 to 7003-3 Gateway unit 7004-1 to 7004-3, 8005-1 to 7005-3 Sub-access point units 7005, 8005 Integrated station equipment 7006-1 to 7006-3, 8006-1 to 7006-3 Sub-station units 7007, 8007 Operating system (OS) execution units 7008, 8008 Application execution units 7009, 8009, 8012 Layer 1 monitors 7010, 8010 SDN controllers 10000-1, 10000-2 Wireless communication devices 10001-1 Upper layer unit 10001a-1 MAC layer unit 10002-1 Autonomous distributed control unit 10002a-1 CCA unit 10002b-1 Backoff unit 10002c-1 Transmission decision unit 10003-1 Transmission unit 10003a-1, 10003c-1 Physical layer frame generation unit 10003b-1, 10003d-1 Wireless transmission unit 10004-1 Receiver 10004a-1, 10004c-1 Wireless reception unit 10004b-1, 10004d-1 Signal demodulation unit 10005-1 Antenna unit 20001-1, 20002-1, 20003-1, 30001-1, 30002-1, 30003-1, 40001-1, 40002-1, 50001-1, 50002-1 Video packets 20000-1, 30000-1, 40000-1, 50000-1 DIFS 20000-2, 30000-2, 40000-2, 50000-2 Backoff 20000-3, 30000-3, 40000-3, 50000-3 Transmission packets20000-4, 30000-4, 40000-4, 50000-4 Allowable delay time 20000-5, 30000-5, 40000-5, 50000-5 SIFS 20000-6, 30000-6, 40000-6, 50000-6 ACK 20000-7, 30000-7, 40000-7, 50000-7 DL communication 20000-8, 30000-8, 40000-8, 50000-8 UL communication S1-1, S2-1, S3-1 Start of processing S1-2 Initialization of transmittable list S1-3, S1-12, S2-3 Loop processing S1-4, S1-8, S1-14, S1-16, S1-19, S2-5, S2-6, S3-3, S3-6 Determination process S1-5 MCS update process S1-6 MCS rate calculation process S1-7 Minimum transmission rate calculation process S1-9 Save to transmission available list S1-10, S1-18, S2-10 End of loop S1-11, S2-2 Scheduling S1-13, S2-4 Determining transmission order S1-15, S2-7, S2-8 Determining transmission destination S1-17, S2-9 Break S1-20 Allocation process S1-21, S2-11 PPDU creation process S1-22, S2-12 PPDU transmission process S1-23, S2-13, S3-9 End of processing S3-2 Reception processing S3-4 Update of remaining information amount of video packet S3-5, S3-7 Initialization S3-8 Update of user index a5001 Wireless control unit a5002 Timer unit a5003 Wireless communication unit a5003a Physical layer frame generation unit a5003b Wireless transmission unit a5003c Wireless reception unit a5003d Received power measurement unit a5003e Channel estimation unit a5003f Signal demodulation unit a5004 Antenna unit a6001 Wireless control unit a10001 MLD access point device a10001-1 Sub-access point device a10001-2 Sub-access point device a10002 MLD station device a10002-1 Sub-station device a10002-2 Sub-station device a10003-1 First wireless link a10003-2 Second wireless link a10011 Multilink control unit a10012 Multilink control unit

Claims

1. An access point device which performs wireless communication with a station device, comprising: a plurality of sub-access point units which use a plurality of different frequencies; a route selection unit which selects a frequency; and a gateway unit which controls traffic based on identification information contained in the traffic, wherein each of the plurality of sub-access point units performs carrier sense prior to emission of radio waves; each of the sub-access point units is connected to a respective sub-station unit provided in the station device; the gateway unit sets a different subnetwork for each of the sub-access point units; and the route selection unit selects one of the different subnetworks for traffic to the station device and sets the gateway unit to transmit the traffic to the station device to the sub-station unit through one of the plurality of sub-access point units which is set to the selected subnetwork.

2. An access point device according to claim 1, wherein the route selection unit selects one of the different subnets for traffic to the station device based on at least one of information from a layer 3 and a network controller.

3. An access point device according to claim 1, wherein said route selection unit sets said substation unit to transmit using at least one of said plurality of frequencies based on traffic information of an application.

4. An access point device as described in claim 1, wherein the route selection unit sets the substation unit to transmit using at least one of the multiple frequencies based on a list of indexes indicating STAs that can transmit and satisfy application requirements set from a higher layer.

5. An access point device according to claim 4, which compares a minimum transmission rate based on a target video rate and an allowable time with an MCS rate based on an MCS (Moderation and Coding Scheme) to determine whether the application requirements are met.

6. A station device connected to an access point device according to any one of claims 1 to 5, the station device transmitting information indicating application requirements to the access point device.

7. A wireless communication method for communicating with another station device using multiple wireless links including a first wireless link and a second wireless link, comprising: receiving first control information for setting communication quality for the communication with the other station device; the first control information including information indicating the first wireless link and the second wireless link; measuring wireless link quality in the first wireless link and the second wireless link; and attempting to acquire a transmission opportunity in at least one of the first wireless link and the second wireless link based on the first control information.

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