WO2026018470A1 - Station device, access point device, and communication method - Google Patents

Abstract

This station device includes an upper layer unit and a lower layer unit. The upper layer unit determines that the lower layer unit is to transition to a non-primary channel access (NPCA) primary channel on the basis of information (first information) indicating one or more values notified by an NPCA information element.

Description

Station device, access point device, and communication method

The present invention relates to a station device, an access point device, and a communication method.
This application claims priority to Japanese Patent Application No. 2024-116158, filed on July 19, 2024, the contents of which are incorporated herein by reference.

IEEE 802.11be, which will achieve even faster speeds than the IEEE 802.11 wireless LAN (Local Area Network) standard, is currently being standardized by the IEEE (The Institute of Electrical and Electronics Engineers Inc.), and wireless LAN devices compliant with the draft specification are now appearing on the market. Standardization activities have now begun for IEEE 802.11bn, the successor to IEEE 802.11be. A key theme in the standardization of IEEE 802.11bn is the realization of Ultra High Reliability (UHR).

Wireless LANs can send and receive frames using unlicensed bands, which allow wireless communication without requiring permission (licenses) from national or regional authorities. For personal use, such as at home, wireless Internet access from within the home has been made possible by including wireless LAN access point functionality in line termination devices for connecting to WAN (Wide Area Network) lines to the Internet, or by connecting wireless LAN access point devices (also called access point devices) to line termination devices. In other words, wireless LAN station devices (also called station devices) such as smartphones and personal computers can access the Internet by connecting to a wireless LAN access point device. When wireless LANs were first introduced in homes, there was often only one wireless LAN access point device per home, but these days, multiple wireless LAN access point devices are being introduced to expand the coverage of the wireless LAN usage area within the home. In particular, for personal use, wireless LAN mesh networks that enable wireless communication between wireless LAN access point devices (backhaul) are preferred to simplify network construction. On the other hand, for enterprise use, wired connections such as Ethernet (registered trademark) between wireless LAN access point devices are preferred to increase the reliability of frame transmission. However, because there is a trade-off between communication performance and the complexity of equipment installation, the decision on whether to use a wireless or wired connection between wireless LAN access point devices may be made based on the use case, taking that balance into consideration.

Meanwhile, in the United States, the 6 GHz band (5.925 to 7.125 GHz) is now available as an unlicensed band, while in Europe and Japan, the use of the lower frequencies of the 6 GHz band (5.925 to 6.425 GHz) is permitted, with consideration also underway for the upper frequencies (6.425 to 7.125 GHz). Similar considerations are also underway in other countries around the world. Due to these trends, it is expected that wireless LANs will be able to use the 6 GHz band in addition to the 2.4 GHz and 5 GHz bands. In order to accommodate the expansion of applicable frequencies, the Wi-Fi Alliance has formulated Wi-Fi 6E (registered trademark), an extended version of Wi-Fi 6, which will use the 6 GHz band.

The 6 GHz band is a frequency band between approximately 5.925 and 7.125 GHz, which means that a total of approximately 1.2 GHz of bandwidth will be newly available, which translates into an increase of 14 channels in 80 MHz-wide channels and 7 channels in 160 MHz-wide channels. Because abundant frequency resources will be available, the maximum channel bandwidth available to a single wireless LAN communication system (equivalent to BSS, described below) will expand from 160 MHz in IEEE 802.11ax to 320 MHz, double the bandwidth in IEEE 802.11be.

While the 2.4 GHz band offers relatively wide coverage (the range over which communication is possible), it is also subject to greater interference between communication devices and has a relatively narrow usable bandwidth. The 5 GHz and 6 GHz bands offer wide communication bandwidths, but do not offer wide coverage. Therefore, to implement a variety of services and applications over a wireless LAN, it is desirable to bundle or switch between frequency bands (2.4 GHz, 5 GHz, 6 GHz, etc., or channels or subchannels within each frequency band) depending on the use case. However, devices using conventional wireless LAN communication standards were unable to bundle and use different frequency bands (2.4 GHz, 5 GHz, 6 GHz, etc.) used for communication. Furthermore, to switch frequency bands (2.4 GHz, 5 GHz, 6 GHz, etc.), it was necessary to first disconnect from the current frequency band and then reconnect to another frequency band.

In response, IEEE 802.11be specifies Multi-Link Operation (MLO), which enables communications devices to use multiple frequency bands and connect via multiple links. One example is simultaneous operation of three link connections: a 2.4 GHz band connection, a 5 GHz band connection, and a 6 GHz band connection. Naturally, the combinations of frequency bands, channels, and subchannels, as well as the number of simultaneous connections, are not limited to these combinations and are diverse. From the perspective of frequency bands, in the future, millimeter waves (45 GHz band, 60 GHz band, etc.) may also be used as one of the links that make up Multi-Link. MLO allows communications devices to maintain multiple link connections that use different wireless resources and communication-related settings. In other words, MLO allows communications devices to simultaneously maintain link connections on different frequency bands. Not only can frames be sent and received using multiple links simultaneously, but it also makes it possible to switch link connections (change frequency bands) for sending and receiving frames without reconnecting.

Furthermore, in the IEEE 802.11bn standardization, discussions are underway regarding Non-Primary Channel Access (NPCA) (Non-Patent Document 1). In conventional technology, the maximum operating bandwidth is specified to be wider as the generation becomes newer: 40 MHz for IEEE 802.11n, 80 MHz for IEEE 802.11ac, 160 MHz for IEEE 802.11ax, and 320 MHz for IEEE 802.11be. However, in reality, these are managed by dividing them into multiple 20 MHz sub-channels. It was necessary to designate one 20 MHz sub-channel as the primary channel, first acquire a transmission opportunity (transmission right) on the primary channel, and then proceed to acquire a transmission opportunity on a 20 MHz sub-channel other than the primary channel. Therefore, if a transmission opportunity on the primary channel cannot be obtained, no transmission opportunity can be obtained, even if multiple 20 MHz sub-channels other than the primary channel are idle (unused). In the case of standards up to IEEE 802.11be, if the right to transmit on the 20 MHz primary channel cannot be obtained, the remaining 300 MHz bandwidth cannot be used even if it is idle. The mechanism for obtaining transmission opportunities based on the primary channel is a remnant of the technological development of wireless LAN, which maintained backward compatibility. Wireless communication technologies that use the same frequency band as wireless LAN include Licensed Assisted Access (LAA), but unlike wireless LAN, there are no channel access restrictions based on the primary channel, which puts wireless LAN technology at a disadvantage in terms of obtaining transmission opportunities. Therefore, a new channel access method is being considered for IEEE 802.11bn, which would allow multiple 20 MHz sub-channels other than the primary channel to be used even if a transmission opportunity on the 20 MHz primary channel cannot be obtained.

IEEE 802.11-24/0495-00-00bn, May.2024

NPCA is a technology in which, when the NAV is set to the 20 MHz primary channel and the channel is busy due to, for example, the occurrence of frame transmission and reception in an OBSS (Overlapping Basic Service Set), some or all of the wireless communication devices belonging to the BSS (Basic Service Set) make a channel transition (channel switch, channel change) to the NPCA primary channel, and if a transmission opportunity is obtained at the channel transition destination, frames may be transmitted and received between the wireless communication devices. Here, the NPCA primary channel is a sub-channel other than the primary channel that is included in the operation bandwidth (operation channel) of the wireless communication system. It is generally a 20 MHz sub-channel, but may be a sub-channel with a larger bandwidth. Regardless of whether frames are transmitted and received on the NPCA primary channel, the system will basically return to the primary channel before the end of the NAV set by the OBSS and attempt to obtain a transmission opportunity on the primary channel. In order to improve wireless medium utilization efficiency, it is necessary to establish a method for appropriately controlling the transition to the NPCA primary channel.

The communication device and communication method according to the present invention, which solve the above-mentioned problems, are as follows.

(1) In other words, a station device according to one aspect of the present invention comprises an upper layer section and a lower layer section, and the upper layer section determines that the lower layer section will transition to the NPCA primary channel based on information (first information) indicating one or more values notified in an NPCA (Non-Primary Channel Access) information element.

(2) Furthermore, a station device according to one aspect of the present invention is described in (1) above, communicates with an access point device, and includes a receiving unit, wherein the receiving unit receives a first frame transmitted by the access point device, and the first frame includes the NPCA information element.

(3) Furthermore, a station device according to one aspect of the present invention is described in (1) above, wherein the receiving unit receives a second frame from a wireless communication device other than a BSS (Basic Service Set) configured by the access point device, and when at least one of the first information regarding the second frame satisfies a channel transition condition, the upper layer unit notifies the lower layer unit of a transition to the NPCA primary channel.

(4) Furthermore, a station device according to one aspect of the present invention is described in (1) above, wherein one of the first pieces of information is a NAV (Network Allocation Vector) threshold, and the channel transition condition is that the NAV set based on the second frame exceeds the NAV threshold.

(5) Furthermore, a station device according to one aspect of the present invention is described in (1) above, wherein one of the first information is a bandwidth threshold, and the channel transition condition is that the bandwidth set based on the second frame is below the bandwidth threshold.

(6) Furthermore, a station device according to one aspect of the present invention is described in (1) above, wherein one of the first pieces of information is a received power threshold, and the channel transition condition is that the received power of the second frame falls below the received power threshold.

(7) Furthermore, an access point device according to one aspect of the present invention is an access point device that communicates with one or more station devices, and includes a transmitter. The transmitter transmits a frame to at least one of the one or more station devices, the frame including an NPCA information element, and the NPCA information element including information indicating an NPCA primary channel.

(8) Furthermore, a station device according to one aspect of the present invention is described in (7) above, wherein the NPCA information element includes information indicating one or more thresholds for channel transition conditions to the NPCA primary channel.

(9) Furthermore, a station device according to one aspect of the present invention is described in (7) above, wherein the threshold is a NAV threshold.

(10) Furthermore, a station device according to one aspect of the present invention is described in (7) above, wherein the threshold is a bandwidth threshold.

(11) Furthermore, a station device according to one aspect of the present invention is described in (7) above, wherein the threshold is a received power threshold.

(12) Furthermore, a communication method according to one aspect of the present invention is a communication method in a wireless communication system configured with an access point device and one or more station devices, in which the access point device transmits a frame including an NPCA information element to the station device, the NPCA information element including information indicating an NPCA primary channel and information indicating one or more thresholds for channel transition conditions to the NPCA primary channel, and the station device transitions to the NPCA primary channel when a frame received from a wireless communication device other than a BSS configured by the access point device satisfies the channel transition conditions.

According to the present invention, in a wireless LAN communication system that supports NPCA (Non-Primary Channel Access), the effective frequency utilization efficiency during channel transitions can be improved by analyzing frame transmission and reception in surrounding wireless LAN communication systems and determining whether or not to transition to the NPCA primary channel based on their characteristics.

FIG. 10 is a diagram illustrating an example of a frame configuration according to an aspect of the present invention. FIG. 10 is a diagram illustrating an example of a frame configuration according to an aspect of the present invention. 1 is a diagram illustrating an example of the architecture of a wireless communication device according to one aspect of the present invention. 1 is a schematic diagram illustrating an example of division of a wireless medium according to one aspect of the present invention. FIG. 1 is a diagram illustrating an example of a configuration of a communication system according to an aspect of the present invention. 1 is a block diagram illustrating an example of a configuration of a wireless communication device according to an aspect of the present invention. 1 is a block diagram illustrating an example of a configuration of a wireless communication device according to an aspect of the present invention. 1 is a block diagram illustrating an example of a configuration of a wireless communication device according to an aspect of the present invention. FIG. 10 is a diagram illustrating an example of a frame configuration according to an aspect of the present invention. FIG. 1 is a diagram illustrating an example of a configuration of a frame sequence according to an aspect of the present invention. FIG. 1 is a diagram illustrating an example of a configuration of a frame sequence according to an aspect of the present invention. 1 is a diagram illustrating an example of a configuration of a communication system according to an aspect of the present invention. FIG. 2 is a diagram illustrating an example of a frame sequence according to an aspect of the present invention. FIG. 10 is a diagram showing an example of a Primitive sequence according to one embodiment of the present invention. FIG. 10 is a diagram showing an example of a Primitive sequence according to one embodiment of the present invention. FIG. 10 is a diagram showing an example of a Primitive sequence according to one embodiment of the present invention.

The communication system in this embodiment comprises an access point device (also referred to as a wireless base station device, base station device, AP (Access Point), etc.) and multiple station devices (also referred to as wireless terminal devices, terminal devices, non-AP STA, etc.). Furthermore, the network consisting of the access point device and the station devices is called a basic service set (BSS: Basic service set, management range). Below, when simply referring to a communication device or wireless communication device, this can refer to both station devices and access point devices.

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, but 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, station devices form a BSS in place of access point devices. A BSS in ad hoc mode is also referred to as an IBSS (Independent Basic Service Set). Hereinafter, station devices that form an IBSS in ad hoc mode can also be considered as access point devices. 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, station devices form a Group in place of access point devices. In the following, the group owner station device that forms a group in Wi-Fi Direct can also be considered an access point device.

Figure 3 shows an architecture diagram of a wireless communication device (including access point devices and station devices). The MAC layer corresponds to the layer above the PHY layer. The MAC layer may also be referred to as the upper layer, and the PHY layer as the lower layer. The PHY layer includes a management entity called the PLME (Physical Layer Management Entity), and PHY layer management functions are activated via the PLME. Similarly, the MAC layer includes a management entity called the MLME (Medium Access Control sublayer Management Entity), and MAC layer management functions are activated via the MLME.

The SME (Station Management Entity) is a layer-independent entity whose role is to collect layer-specific status such as PHY and MAC, and to set parameter values specific to layers such as PHY and MAC. There is an interface called the MLME SAP (Service Access point) between the SME and MLME, and the MAC layer and SME interact by exchanging MLME SAP Primitives via the MLME SAP. There is an interface called the PLME SAP between the SME and PLME, and the PHY layer and SME interact by exchanging PLME SAP Primitives via the PLME SAP. The MAC layer and communication layers above the MAC layer interact by exchanging MAC Service Primitives (also called MAC SAP Primitives) via the MAC SAP. The MAC layer and PHY layer interact by exchanging PHY Service Primitives (also called MAC SAP Primitives) via PHY SAPs. MLME SAP Primitives, PLME SAP Primitives, MAC Service Primitives, PHY Service Primitives, etc. are collectively referred to as Primitives.

In an IEEE 802.11 system, each wireless communication device can transmit frames of multiple frame types that share a common frame format. Frames are defined at the physical (PHY) layer, medium access control (MAC) layer, and logical link control (LLC) layer.

A PHY layer frame is called a physical protocol data unit (PPDU, PHY protocol data unit, physical layer frame, radio frame, frame). A PPDU consists of a physical layer header (PHY header), which contains header information for signal processing at the physical layer, and a physical service data unit (PSDU, PHY service data unit, MAC layer frame), which is the data unit processed at the physical layer. A PSDU can be composed of a MAC protocol data unit (MPDU), which is the unit of retransmission in the radio section, or an aggregated MPDU (A-MPDU), which aggregates multiple MAC protocol data units.

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. STF is further classified into non-High throughput-STF (non-HT STF or L-STF), High throughput-STF (HT-STF), Very high throughput-STF (VHT-STF), High efficiency-STF (HE-STF), and Extremely High Throughput-STF (EHT-STF) depending on the corresponding standard. 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, assuming technical updates within the same standard, it can include a Universal SIGNAL (U-SIG) field containing additional control information.

Furthermore, the PHY header can include information identifying the BSS from which the frame was sent (hereinafter also referred to as BSS identification information). The information 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 identifying the BSS can also be a value unique to the BSS (such as a BSS Color) other than the SSID or MAC address.

The PPDU is modulated according to the corresponding standard. For example, in the case of the IEEE 802.11b standard, it is modulated into a spread spectrum (DSSS; Direct Sequence Spread Spectrum) signal, and in the case of the IEEE 802.11a standard and its successors (IEEE 802.11g/n/ac/ax/be/bn, etc.), it is modulated into an orthogonal frequency division multiplexing (OFDM) signal.

A wireless communication device has either the function of transmitting or the function of receiving PPDUs, or both. Figure 1 shows an example of the structure of a PPDU transmitted by a wireless communication device. A PPDU that complies with the IEEE 802.11a/b/g standard is structured to include L-STF, L-LTF, L-SIG, and a Data frame (MAC Frame, MAC frame, payload, data section, data, information bits, etc.). An HT PPDU (High throughput PPDU) that complies with the IEEE 802.11n standard is structured to include L-STF, L-LTF, L-SIG, HT-SIG, HT-STF, HT-LTF, and a Data frame. A VHT PPDU (Very High Throughput PPDU) conforming to the IEEE 802.11ac standard is composed of some or all of the following: L-STF, L-LTF, L-SIG, VHT-SIG-A, VHT-STF, VHT-LTF, VHT-SIG-B, and a MAC frame. A HE PPDU (High Efficiency PPDU) conforming to the IEEE 802.11ax standard is composed of some or all of the following: L-STF, L-LTF, L-SIG, RL-SIG, which is a temporally repeated L-SIG, HE-SIG-A, HE-STF, HE-LTF, HE-SIG-B, and a Data frame. The EHT PPDU (Extremely High Throughput PPDU) standardized by IEEE 802.11be 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.

Figure 2 shows an example of an MPDU structure. An MPDU (also known as a MAC frame) consists of a MAC header containing header information for signal processing at the MAC layer, a MAC service data unit (MSDU) or frame body, which is the data unit processed at the MAC layer, and a frame check sequence (FCS), which checks the frame for errors. The MAC header contains a Frame Control field, Duration/ID field, Address 1 field, Address 2 field, Address 3 field, Sequence Control field, Address 4 field, QoS Control field, HT Control field, Frame Body field, and FCS field. The Frame Control field indicates the frame type (such as management frame, control frame, data frame, or extension frame). The Duration/ID field (which may simply be called the Duration field) contains a value corresponding to the length of the transmission opportunity. The frame's sending address (TA: Transmitter Address) and receiving address (RA: Receiver Address) can be determined from information in the Address 1 field, Address 2 field, Address 3 field, Address 4 field, etc.

The L-STF, L-LTF, and L-SIG in Figure 1 are structures commonly used in the IEEE 802.11 standard (hereinafter, L-STF, L-LTF, and L-SIG are collectively referred to as the L-header). For example, a wireless communication device that complies with the IEEE 802.11a/b/g standard can properly receive an L-header in a PPDU that complies with the IEEE 802.11n/ac standard. A wireless communication device that complies with the IEEE 802.11a/b/g standard can receive a PPDU that complies with the IEEE 802.11n/ac standard, treating it as a PPDU that complies with the IEEE 802.11a/b/g standard.

However, wireless communication devices that support the IEEE 802.11a/b/g standards cannot demodulate the PPDU that follows the L-header and is compatible with the IEEE 802.11n/ac standards, and therefore cannot demodulate the information contained in the MAC header regarding the transmitter address (TA), receiver address (RA), or the Duration field used to set the network allocation vector (NAV).

IEEE 802.11 specifies a method for inserting Duration information into L-SIG as a method for wireless communication devices that comply with the IEEE 802.11a/b/g standards to appropriately set their NAV (or perform reception for a specified period of time). Information about the transmission rate in L-SIG (RATE field, L-RATE field, L-RATE, L_DATARATE, L_DATARATE field) and information about the transmission period (LENGTH field, L-LENGTH field, L-LENGTH) are used by wireless communication devices that comply with the IEEE 802.11a/b/g standards to appropriately set their NAV.

Next, we will explain how a wireless communication device identifies the BSS from a frame it receives. In order for a wireless communication device to identify the BSS from a frame it receives, it is preferable for the wireless communication device transmitting the PPDU to insert information for identifying the BSS (BSS Color, BSS identification information, a value unique to the BSS) into the PPDU. Information indicating the BSS Color can be included in the HE-SIG-A.

A wireless communication device can transmit L-SIG multiple times (L-SIG Repetition). For example, a receiving wireless communication device can receive L-SIG transmitted multiple times using Maximum Ratio Combining (MRC), thereby improving the demodulation accuracy of the L-SIG. Furthermore, when the wireless communication device has successfully received the L-SIG using MRC, it can interpret the PPDU containing that L-SIG as a PPDU that complies with the IEEE 802.11ax standard.

Even while receiving a PPDU, the wireless communication device can receive parts of a PPDU other than the PPDU in question (for example, the preamble, L-STF, L-LTF, PHY header, etc., as specified by IEEE 802.11) (also known as dual reception). If the wireless communication device detects parts of a PPDU other than the PPDU in question while receiving the PPDU, it can update some or all of the destination address, source address, and information related to the PPDU or DATA period.

MAC layer frame types are broadly classified into three types: management frames (also called management frames or wireless management frames), which manage the connection status between wireless communication devices; control frames (also called control frames or wireless control frames), which manage the communication status between wireless communication devices; and data frames, which contain the actual transmitted data. Each of these is further classified into multiple subframe types. Control frames include acknowledgement (Ack) frames, request to send (RTS) frames, and clear to send (CTS) frames. Management frames include beacon frames, probe request frames, probe response frames, authentication frames, association request frames, association response frames, and deauthentication frames. Data frames include data frames, polling (QoS CF-poll) frames, etc. Each wireless communication device can determine the frame type and subframe type of a received frame by reading the contents of the Frame Control field contained in the MAC header.

MMPDU (MAC Management Protocol Data Unit) is a data unit exchanged between MAC entities, and may include a Mesh Control field and a Management MIC (Message Integrity Code) element (MME: Management MIC Element). A MAC frame is formed by concatenating at least the MAC header, MMPDU (stored in the frame body section in Figure 2), and inspection section, and is called a management frame.

Note that an Ack may also include a Block Ack. A Block Ack can be used to notify completion of reception of multiple MPDUs.

A beacon frame includes the period at which the beacon is transmitted (Beacon interval), a field that describes the SSID, and an information element. Access point devices can periodically broadcast beacon frames within the BSS, and station devices can learn of the presence and capability of access point devices around the station device by receiving the beacon frames. The process by which a station device learns of an access point device based on beacon frames broadcast by an access point device is called passive scanning. On the other hand, the process by which a station device searches for an access point device by broadcasting a probe request frame within the BSS is called active scanning. The access point device can send a probe response frame in response to the probe request frame, and the content of the probe response frame is equivalent to that of a beacon frame.

After recognizing an access point device, a station device performs a connection process with the access point device. The connection process is divided into an authentication procedure and an association procedure. The station device sends an authentication frame (authentication request) to the access point device with which it wishes to connect. When the access point device receives the authentication frame, it sends an authentication frame (authentication response) to the station device that includes a status code indicating whether or not the station device has been authenticated. By reading the status code written in the authentication frame, the station device can determine whether or not its own wireless communication device has been authorized to authenticate by the access point device. Note that the access point device and station device can exchange authentication frames multiple times.

Following the authentication procedure, the station device sends a connection request frame to the access point device to perform the connection procedure. When the access point device receives the connection request frame, it determines whether to allow the station device to connect and sends a connection response frame to notify the result. In addition to a status code indicating whether the connection process is successful, the connection response frame contains an association identification number (AID: Association identifier) to identify the station device. By setting different AIDs for each station device that has been granted connection permission, the access point device is able to identify and manage multiple station devices.

After the connection process is completed, the access point device and station device perform the actual frame transmission and reception (also known as frame exchange). IEEE 802.11 systems define a distributed control mechanism (DCF: Distributed Coordination Function), a centralized control mechanism (PCF: Point Coordination Function), and mechanisms that extend these (enhanced distributed channel access (EDCA) and hybrid coordination function (HCF), etc.). The following explains an example where an access point device sends a frame to a station device using DCF.

In DCF, access point devices and station devices perform carrier sense (CS) to check the usage status of wireless channels around the wireless communication device before transmitting a frame. For example, the following explanation assumes that the wireless communication device (transmitting station) that plans to transmit a frame is an access point device, but the same applies when the transmitting station is a station device. If the access point device receives a signal higher than a predetermined clear channel assessment level (CCA level) on the wireless channel, it postpones transmitting the frame on that wireless channel. Hereinafter, a state in which a signal above the CCA level is detected on the wireless channel is called a busy state, and a state in which a signal above the CCA level is not detected is called an idle state. In this way, CS performed by each wireless communication device based on the power of the signal actually received (received power level) is called physical carrier sense (physical CS). The CCA level is also called the carrier sense level (CS level) or CCA threshold (CCAT). Furthermore, when an access point device or station device detects a signal at or above the CCA level, it will begin demodulating at least the PHY layer signal.

The access point device performs carrier sensing at an inter-frame space (IFS) that corresponds to the type of frame being 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 it is about to transmit. The IEEE 802.11 system defines several IFSs with different durations, including the short inter-frame space (SIFS) used for transmission frames assigned the highest priority, the inter-frame space (PCF IFS) used for transmission frames with a relatively high priority, and the distributed control inter-frame space (DCF IFS) used for transmission frames with the lowest priority.

After waiting for the DIFS period, the access point device further waits for a random backoff time to prevent frame collisions. In IEEE 802.11 systems, the random backoff time is set within the contention window (CW). CSMA/CA assumes that a transmission frame sent by a transmitting station will be received by the wireless communication device serving as the receiving station without interference from other transmitting stations. Therefore, if two transmitting stations transmit frames at the same time, the frames will collide and the receiving station will not be able to receive them correctly. Therefore, frame collisions are avoided by each transmitting station waiting for a randomly set time before starting transmission. When the access point device (corresponding to the transmitting station in this explanation) determines through carrier sense that the wireless channel is idle, it begins counting down its backoff counter. Only when the backoff counter reaches 0 does it obtain a transmission opportunity and can send a frame to the station device (corresponding to the receiving station in this explanation). If the access point device determines through carrier sense that the wireless channel is busy while the backoff counter is counting down, it stops counting down the backoff counter. If the wireless channel then becomes idle, the access point device waits for the same period (DIFS) as the previous IFS, and then resumes counting down the remaining backoff counter.

The receiving station, the station device, receives the frame, reads the PHY header of the frame, and demodulates the received frame. The station device can then read the MAC header of the demodulated signal to determine whether the frame is addressed to its own wireless communication device. The station device can also determine the destination of the frame based on the information contained in the PHY header (for example, in the case of a frame equivalent to a VHT PPDU, the group identification number (GID: Group ID) contained in the VHT-SIG-A).

If a station device determines that the received frame is addressed to its own wireless communication device and is able to demodulate the frame without error, it must send an Ack frame to the access point device, which is the transmitting station, indicating that the frame was received correctly. An Ack frame is one of the highest priority frames that is sent after waiting for a SIFS period without any random backoff time. When the access point device receives an Ack frame sent from the station device, one frame transmission/reception (frame exchange) is completed successfully. Note that if the station device does not receive the frame correctly, it will not send an Ack. Therefore, if the access point device does not receive an Ack frame from the receiving station for a certain period of time (such as SIFS + Ack frame length) after sending a frame, it can consider one frame transmission/reception (frame exchange) to have failed. In this way, the end of a single frame exchange 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 sending a notification signal such as a beacon frame, or when fragmentation is used to divide the transmitted data.

If a station device determines that a received frame is not addressed to its own wireless communication device, it sets its network allocation vector (NAV) based on a response corresponding to the length of the acquired transmission opportunity, which is written in the MAC header or PHY header. The station device does not attempt communication for 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 for the period set in the NAV, so communication control using the NAV is also called virtual carrier sense (virtual CS). The NAV can be set based on information written in the MAC header or PHY header, and in the case of frames equivalent to HE PPDUs, the value written in the TXOP field included in the HE-SIG-A may be used. Furthermore, the NAV is also set by request to send (RTS) frames and clear to send (CTS) frames, which are introduced to solve the hidden terminal problem, and the value written in the Duration field included in the MAC header is used.

In contrast to DCF, in which each wireless communication device performs carrier sensing and autonomously acquires transmission opportunities, in PCF a control station called a Point Coordinator (PC) controls the transmission opportunities of each wireless communication device within the BSS. Generally, an access point device becomes the PC and acquires the right to transmit for station devices within the BSS.

The communication period using PCF includes a contention-free period (CFP) and a contention period (CP). During the CP, communication is carried out based on the DCF described above, and it is during the CFP that the PC controls the transmission opportunity. The access point device, which is the PC, broadcasts a beacon frame containing the CFP period (CFP Max duration) and other information within the BSS prior to PCF communication. The beacon frame broadcast at the start of PCF transmission uses PIFS and is transmitted without waiting for the random backoff time. The station device that receives this beacon frame sets the CFP period described in the beacon frame to its NAV. Thereafter, until the NAV elapses or a signal announcing the end of CFP within the BSS (e.g., a data frame containing CF-end) is received, the station device can only acquire a transmission opportunity if it receives a signal signaling acquisition of a transmission opportunity sent from the PC (e.g., a data frame containing CF-poll). During the CFP period, packet collisions do not occur within the same BSS, so each station device does not take the random backoff time used in DCF.

A wireless medium can be divided into multiple resource units (RUs). Figure 4 is a schematic diagram showing an example of the division state of a wireless medium. For example, in resource division example 1, a wireless communication device can divide the frequency resource (subcarriers) of the wireless medium into nine RUs. Similarly, in resource division example 2, a wireless communication device can divide the subcarriers of the wireless medium into five RUs. Of course, the resource division example shown in Figure 4 is merely an example, and, for example, multiple RUs can each be configured with a different number of subcarriers. Furthermore, the wireless medium divided into RUs can include not only frequency resources but also spatial resources. A wireless communication device (e.g., an access point device) can simultaneously transmit frames to multiple wireless communication devices (e.g., multiple station devices) by placing frames addressed to different station devices in each RU. An access point device can include information indicating the division state of the wireless medium (resource allocation information) as common control information in the PHY header of frames transmitted by its own wireless communication device. Furthermore, the access point device can include information (resource unit assignment information) indicating the RU in which the frame addressed to each station device is placed as unique control information in the PHY header of the frame transmitted by its own wireless communication device.

Furthermore, multiple wireless communication devices (e.g., multiple station devices) can transmit frames simultaneously by placing the frames in the RUs assigned to them. After receiving a frame containing trigger information (Trigger frame: TF) sent from an access point device, multiple station devices can wait a predetermined period of time before transmitting the frame. Each station device can ascertain the RU assigned to its own wireless communication device based on the information contained in the TF. Furthermore, each station device can acquire an RU by random access based on the TF.

An access point device can simultaneously allocate multiple RUs to one station device. The multiple RUs can be configured with consecutive or non-consecutive subcarriers. The access point device can transmit a single frame using the multiple RUs allocated to one station device, or can allocate multiple frames to different RUs for transmission. At least one of the multiple frames can be a frame containing common control information for the multiple station devices that transmit resource allocation information.

A single station device can be assigned multiple RUs by the access point device. The station device can transmit a single frame using the multiple assigned RUs. Furthermore, the station device can use the multiple assigned RUs to transmit multiple frames, each assigned to a different RU. The multiple frames can each be of a different frame type.

The access point device can assign multiple AIDs to one station device. The access point device can assign RUs to each of the multiple AIDs assigned to one station device. The access point device can transmit different frames using the assigned RUs for each of the multiple AIDs assigned to one station device. The different frames can be of different frame types.

A single station device can be assigned multiple AIDs by an access point device. A single station device can be assigned an RU for each of the multiple assigned AIDs. A single station device recognizes all RUs assigned to the multiple AIDs assigned to its own wireless communication device as RUs assigned to its own wireless communication device, and can transmit a single frame using the multiple assigned RUs. A single station device can also transmit multiple frames using the multiple assigned RUs. At this time, the multiple frames can be transmitted including information indicating the AIDs associated with the assigned RUs.

[1. First Embodiment]

The wireless communication system of this embodiment will be described using Figure 5. Wireless communication system 3-1 (also referred to as BSS 3-1) includes access point device 1-1 and station devices 2-1, 2-12, 2-13, and 2-123. Station devices 2-1, 2-12, 2-13, and 2-123 are also collectively referred to as station device 2A (terminal device 2A) as station devices connected (associated) with access point device 1-1. Access point device 1-1 and station device 2A are wirelessly connected and are capable of sending and receiving frames to and from each other.

Wireless communication system 3-2 (also referred to as BSS3-2) comprises access point device 1-2 and station devices 2-2, 2-21, 2-23, and 2-213. Furthermore, station devices 2-2, 2-21, 2-23, and 2-213 are collectively referred to as station device 2B (terminal device 2B) as devices connected (associated) with access point device 1-2. Access point device 1-2 and station device 2B are wirelessly connected and are capable of sending and receiving frames to and from each other.

Wireless communication system 3-3 (also referred to as BSS 3-3) comprises access point device 1-3 and station devices 2-3, 2-31, 2-32, 2-34, and 2-312. Furthermore, station devices 2-3, 2-31, 2-32, 2-34, and 2-312 are collectively referred to as station device 2C (terminal device 2C) as devices connected (associated) with access point device 1-3. Access point device 1-3 and station device 2C are wirelessly connected and are capable of sending and receiving frames to and from each other.

Wireless communication system 3-4 (also referred to as BSS 3-4) comprises access point device 1-4 and station device 2-4. Station device 2-4 is also collectively referred to as station device 2D (terminal device 2D) as a device connected to access point device 1-4. Access point device 1-4 and station device 2D are wirelessly connected and can send and receive frames to and from each other. Station device 2-4 sends and receives frames only to and from access point device 1-4, with which it is connected.

Also, in FIG. 5, access point device 1-1 is located within the coverage of wireless communication system 3-2 of access point device 1-2 and within the coverage of wireless communication system 3-3 of access point device 1-3, but outside the coverage of wireless communication system 3-4 of access point device 1-4. Similarly, access point device 1-2 is located within the coverage of wireless communication system 3-1 of access point device 1-1 and within the coverage of wireless communication system 3-3 of access point device 1-3, but outside the coverage of wireless communication system 3-4 of access point device 1-4. Similarly, access point device 1-3 is located within the coverage of wireless communication system 3-1 of access point device 1-1 and within the coverage of wireless communication system 3-2 of access point device 1-2, but outside the coverage of wireless communication system 3-4 of access point device 1-4. On the other hand, access point device 1-4 is located within the coverage of wireless communication system 3-3 of access point device 1-3, but outside the coverage of wireless communication system 3-1 of access point device 1-1, and outside the coverage of wireless communication system 3-2 of access point device 1-2. Therefore, access point devices 1-1, 1-2, and 1-3 can send and receive wireless frames to and from each other, but access point 1-4 can only send and receive wireless frames to and from access point device 1-3.

Wireless communication system 3-1, wireless communication system 3-2, wireless communication system 3-3, and wireless communication system 3-4 form different BSSs, but this does not necessarily mean that the ESSs (Extended Service Sets) are different. ESS refers to a service set that forms a LAN (Local Area Network). In other words, wireless communication devices that belong to the same ESS can be considered to belong to the same network from a higher layer. In addition, BSSs are connected via a DS (Distribution System) to form an ESS. Note that each of wireless communication systems 3-1, 3-2, 3-3, and 3-4 can also be equipped with multiple wireless communication devices.

Figure 6 shows an example of the device configuration of wireless communication devices 1-1, 1-2, 1-3, 1-4, 2A, 2B, 2C, and 2D (hereinafter collectively referred to as wireless communication device 10000-1). Wireless communication device 10000-1 includes an upper layer unit (upper layer processing step) 10001-1, an autonomous distributed control unit (autonomous distributed control step) 10002-1, a transmitter (transmission step) 10003-1, a receiver (reception step) 10004-1, and an antenna unit 10005-1.

The upper layer unit 10001-1 includes a MAC layer frame generation unit (MAC frame generation step) 10001a-1 and an upper layer control unit (upper layer control step) 10001b-1. The MAC layer frame generation unit 10001a-1 adjusts the information bits to a size that fits within the Framebody and adds a MAC header and FCS to generate a MAC frame. The information bits include not only data for configuring a data frame, but also management data for configuring a management frame and control data for configuring a control frame. The upper layer control unit 10001b-1 not only controls within the upper layer unit 10001-1, but also controls communication with the DS and communication with the physical layer. For example, it may control whether the MAC frame is sent to the DS or to the physical layer (the autonomous distributed control unit 10002-1 and physical layer frame generation unit 10003a-1, described below).

Upper layer unit 10001-1 has MAC layer functionality, is connected to other networks and other BSSs via a DS (Distribution System), and can notify autonomous distributed control unit 10002-1 of traffic-related information. Traffic-related information may be, for example, information addressed to other wireless communication devices, or control information contained in management frames or control frames. Upper layer unit 10001-1 may also have MLME functionality.

Figure 7 shows an example of the device configuration of the autonomous distributed control unit 10002-1. The autonomous distributed control unit 10002-1 includes a CCA unit (CCA step) 10002a-1, a backoff unit (backoff step) 10002b-1, and a transmission decision unit (transmission decision step) 10002c-1.

The CCA unit 10002a-1 can determine the status of the radio resource (including whether it is busy or idle) using either or both of the information about the received signal power received via the radio resource and the information about the received signal (including information after decoding) notified by the receiving unit 10004-1. The CCA unit 10002a-1 can notify the backoff unit 10002b-1 and the transmission determination unit 10002c-1 of the status determination information for the radio resource.

The backoff unit 10002b-1 can perform the backoff procedure using radio resource status determination information. The backoff unit 10002b-1 has a countdown function for the random backoff time set within the CW. For example, if the radio resource status determination information indicates idle, it can count down the backoff counter, and if the radio resource status determination information indicates busy, it can stop the backoff counter countdown. The backoff unit 10002b-1 can notify the transmission determination unit 10002c-1 of the backoff counter value.

The transmission decision unit 10002c-1 makes a transmission decision using either the wireless resource status decision information or the back-off counter value, or both. For example, when the wireless resource status decision information indicates idle and the back-off counter value is 0, the transmission decision information can be notified to the transmitting unit 10003-1. Also, when the wireless resource status decision information indicates idle, the transmission decision information can be notified to the transmitting unit 10003-1.

Transmitting unit 10003-1 includes a physical layer frame generating unit (physical layer frame generating step) 10003a-1 and a wireless transmitting unit (wireless transmitting step) 10003b-1. The physical layer frame generating unit 10003a-1 has the function of generating a physical layer frame (PPDU) based on transmission decision information notified by the transmission decision unit 10002c-1. The physical layer frame generating unit 10003a-1 performs error correction coding, modulation, precoding filter multiplication, etc. on the transmission frame sent from the upper layer. The physical layer frame generating unit 10003a-1 outputs the generated physical layer frame to the wireless transmitting unit 10003b-1.

The physical layer frame generator 10003a-1 applies error correction coding to the information bits input from the MAC layer, but the unit of error correction coding (coding block length) is not limited to any particular unit. For example, the physical layer frame generator 10003a-1 can divide the information bit sequence input from the MAC layer into information bit sequences of a predetermined length, apply error correction coding to each sequence, and create multiple coding blocks. Note that when constructing the coding blocks, dummy bits can also be inserted into the information bit sequence input from the MAC layer.

The frames generated by the physical layer frame generation unit 10003a-1 contain control information. This control information includes information indicating in which RU (here, RU includes both frequency resources and spatial resources) data addressed to each wireless communication device is located. Furthermore, the frames generated by the physical layer frame generation unit 10003a-1 contain a trigger frame that instructs the wireless communication device, which is the destination terminal, to transmit a frame. This trigger frame contains information indicating the RU that the wireless communication device instructed to transmit the frame will use when transmitting the frame.

The wireless transmitter 10003b-1 converts the physical layer frame generated by the physical layer frame generator 10003a-1 into a radio frequency (RF) band signal, generating a radio frequency signal. The processing performed by the wireless transmitter 10003b-1 includes digital-to-analog conversion, filtering, and frequency conversion from the baseband to the RF band.

The receiving unit 10004-1 includes a radio receiving unit (radio receiving step) 10004a-1 and a signal demodulating unit (signal demodulating step) 10004b-1. The receiving unit 10004-1 generates information related to the received signal power from the RF band signal received by the antenna unit 10005-1. The receiving unit 10004-1 can notify the CCA unit 10002a-1 of the information related to the received signal power and the information related to the received signal.

The wireless receiver 10004a-1 has the function of converting RF band signals received by the antenna unit 10005-1 into baseband signals and generating physical layer signals (e.g., physical layer frames). The processing performed by the wireless receiver 10004a-1 includes frequency conversion from the RF band to the baseband, filtering, and analog-to-digital conversion.

The signal demodulation unit 10004b-1 has the function of demodulating the physical layer signal generated by the wireless receiving unit 10004a-1. The processing performed by the signal demodulation unit 10004b-1 includes channel equalization, demapping, error correction decoding, and the like. The signal demodulation unit 10004b-1 can extract, for example, information contained in the physical layer header, information contained in the MAC header, and other information contained in the MAC frame from the physical layer signal. The signal demodulation unit 10004b-1 can output the extracted information to the upper layer unit 10001-1. The signal demodulation unit 10004b-1 can extract any or all of the information contained in the physical layer header, information contained in the MAC header, and other information contained in the MAC frame.

Antenna unit 10005-1 has the function of transmitting the radio frequency signal generated by wireless transmission unit 10003b-1 into wireless space toward other wireless device 10000-1. Antenna unit 10005-1 also has the function of receiving the radio frequency signal transmitted from other wireless device 10000-1.

The wireless communication device 10000-1 can cause wireless communication devices surrounding the wireless communication device to set a NAV for that period by including information indicating the period during which the wireless medium will be used based on the transmission opportunity acquired by the wireless communication device in the PHY header or MAC header of the frame it transmits. For example, the wireless communication device 10000-1 can include information indicating that period in the Duration field of the MAC header of the frame it transmits, or the L-SIG Length field included in the PHY header, the L-SIG Length field included in the PHY header, the HE-SIG-A TXOP field in the case of an HE PPDU, or the U-SIG TXOP field in the case of an EHT PPDU. The NAV period set in the wireless communication devices surrounding the wireless communication device will be referred to as the transmission opportunity (or TXOP period, or simply TXOP) acquired by the wireless communication device 10000-1. The wireless communication device 10000-1 that acquires the transmission opportunity is called the TXOP acquirer (TXOP holder). The frame type transmitted by wireless communication device 10000-1 to notify it of the acquired transmission opportunity is not limited to any particular type, and may be a control frame (for example, a CTS frame, an RTS frame, a CTS-to-self frame, etc.), or a data frame transmitted in a format such as Non-HT PPDU, HT PPDU, VHT PPDU, EHT PPDU, or UHR-PPDU.

Wireless communication device 10000-1, which is the TXOP holder, can transmit frames to wireless communication devices other than itself during the transmission opportunity. If wireless communication device 1-1 is the TXOP holder, wireless communication device 1-1 can transmit frames to wireless communication device 2A during the transmission opportunity. Furthermore, wireless communication device 1-1 can instruct wireless communication device 2A to transmit a frame addressed to wireless communication device 1-1 during the transmission opportunity. Wireless communication device 1-1 can transmit a trigger frame including information instructing wireless communication device 2A to transmit a frame addressed to wireless communication device 1-1 during the transmission opportunity.

Wireless communication device 1-1 may acquire transmission opportunities for all communication bands (operation bandwidth, operation channel, etc.) in which frames may be transmitted and received, or may acquire transmission opportunities for specific communication bands or channels, such as the communication bands (transmission and reception bandwidth, transmission and reception channel) in which frames are actually transmitted and received.

The wireless communication devices to which wireless communication device 1-1 instructs frame transmission and reception during the acquired transmission opportunity period are not necessarily limited to wireless communication devices connected to the wireless communication device itself. For example, a wireless communication device can instruct wireless communication devices not connected to the wireless communication device itself to transmit and receive frames using a trigger frame or the like in order to have wireless communication devices in the vicinity of the wireless communication device transmit management frames such as reassociation frames, control frames such as RTS/CTS frames, and data frames.

Furthermore, we will also explain transmission opportunities in EDCA, a channel access method (data transmission method) different from DCF. The IEEE 802.11e standard is related to EDCA, and specifies transmission opportunities from the perspective of QoS (Quality of Service) guarantees for various services such as video transmission and VoIP. Services are broadly classified into four access categories: VO (VOice), VI (VIdeo), BE (Best Effort), and BK (Background). Generally, the order of priority is VO, VI, BE, and BK. Each access category has parameters (EDCA parameters) that are set as a set of the minimum CW value CWmin, the maximum CWmax, the length of AIFS (Arbitration IFS), a type of IFS, and the TXOP limit, which is the upper limit of transmission opportunities. The values are set to create differences in priority between access categories. For example, by setting the CWmin, CWmax, and AIFS of VO, which has the highest priority for voice transmission, to relatively small values compared to other access categories, data transmission can be prioritized over other access categories. For example, in VI, which transmits a relatively large amount of data for video transmission, setting the TXOP limit large makes it possible to secure longer transmission opportunities than other access categories. In this way, the EDCA parameter values for each access category are adjusted to guarantee QoS according to the various services.

In this embodiment, the signal demodulation unit 10004b-1 of the station device performs decoding processing on the received signal at the physical layer, and can perform error detection. Here, the decoding processing includes decoding processing on the error correction code applied to the received signal. Here, error detection includes error detection using an error detection code (e.g., a cyclic redundancy check (CRC) code) that has been previously assigned to the received signal, and error detection using an error correction code that originally has error detection functionality (e.g., a low-density parity check (LDPC) code). Decoding processing at the physical layer can be applied to each coding block.

The upper layer unit 10001-1 receives the physical layer decoding results from the signal demodulation unit 10004b-1 and decodes the MAC layer signal. The MAC layer then performs error detection to determine whether the MAC layer signal sent by the station device that sent the received frame was correctly decoded.

The wireless communication device may be a multi-link device (MLD) capable of multi-link communication. An access point device that supports MLD will be referred to as an MLD access point device, and a station device that supports MLD will be referred to as an MLD station device. Furthermore, MLD access point devices and MLD station devices will collectively be referred to as MLD wireless communication devices.

The MLD access point device 20000-1 and MLD station device 30000-1 will be described using Figure 8. An MLD wireless communication device is composed of multiple sub-wireless communication devices corresponding to the frequency bands (or channels, or sub-channels) of each link (also called physical layer links) that make up the multi-link. Figure 8 shows an example in which the MLD access point device 20000-1 is composed of three sub-wireless communication devices, in this case three sub-access point devices (20000-2, 200000-3, and 20000-4), but the number of sub-access point devices can be any number greater than or equal to one. Similarly, Figure 8 shows an example in which the MLD station device 30000-1 is composed of three sub-wireless communication devices, in this case three substation devices (30000-2, 300000-3, and 30000-4), but the number of substation devices can be any number greater than or equal to one. Note that the sub-wireless communication device (sub-access point device, sub-station device, etc.) may be composed of a portion of the circuitry within the wireless communication device, and may be referred to as a sub-wireless communication unit (sub-access point unit, sub-station unit).

In Figure 8, for the sake of explanation, multiple sub-wireless communication devices are shown as logically separate blocks (squares), but they may also be physically configured as a single wireless communication device. Alternatively, they may be physically configured as separate sub-wireless communication devices, in which case each sub-access point device transmits and receives necessary information via connections 9-1 and 9-2, and each substation device transmits and receives necessary information via connections 9-3 and 9-4. In this embodiment, the MLD wireless communication device is physically configured from a single wireless communication device (10000-1), and its configuration is the same as that described above using Figures 6 and 7.

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, and capabilities 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 located within a wireless communication system, the number of sub-wireless communication devices (sub-access point devices, substation devices) that make up that MLD wireless communication device may vary depending on the grade, class, and capabilities, and these numbers do not have to be the same.

Substation device 30000-2 connects (associates) with sub-access point device 20000-2 and establishes link 1. Substation device 30000-3 connects (associates) with sub-access point device 20000-3 and establishes link 2. Substation device 30000-4 connects (associates) with sub-access point device 20000-4 and establishes link 3. In this embodiment, the number of links constituting the multi-link is three, but this is not limited to three and any number can be used. In this embodiment, the carrier frequency of link 1 is 2.4 GHz, the carrier frequency of link 2 is 5 GHz, and the carrier frequency of link 3 is 6 GHz. However, the frequencies used by each link can be set arbitrarily from the 2.4 GHz, 5 GHz, 6 GHz, 60 GHz, or other frequency bands, channels, and sub-channels supported by the wireless communication system, and may vary depending on the laws and regulations of each country.

Here, with regard to channel access in an IEEE 802.11 system, the acquisition of transmission opportunities is performed for each 20 MHz bandwidth, as will be further explained using Figure 11. For example, assume that a wireless communication system is constructed using an IEEE 802.11ax-compliant access point device, with a total operating bandwidth of 80 MHz, consisting of subchannels CH1 to CH4, each with a 20 MHz bandwidth. One of CH1 to CH4 is set as the primary channel. For example, if CH1 is set as the primary channel, CH2 adjacent to CH1 is called the secondary channel, the combination of CH1 and CH2 is called the 40 MHz primary channel, and the combination of CH3 and CH4 adjacent to the 40 MHz primary channel is called the 40 MHz secondary channel. Note that the acquisition of transmission opportunities based on the backoff time count and carrier sense on the primary channel also affects the acquisition of transmission opportunities on other channels.

Assuming that the primary channel is set to CH1, an example of the frame transmission procedure when station device 2-1 transmits a frame to access point device 1-1 is described below. Station device 2-1 performs carrier sensing on CH1 after a random backoff time and determines that CH1 is idle. If station device 2-1 determines that CH1 is idle, it may transmit RTS frame 11-11 on CH1. If the primary channel, CH1, is idle, it may also perform carrier sensing on the remaining channels, CH2 to CH4, and if it confirms that they are idle, it may transmit RTS frames 11-12 to 11-14. Note that if primary channel CH1 is busy, it cannot proceed to the carrier sensing procedure on channels other than the primary channel, CH2 to CH4. Upon receiving the RTS frame, access point device 1-1 checks the wireless channel conditions on CH1 to CH4 and, if it determines that they are idle, transmits CTS frames 11-21 to 11-24 indicating this on each of CH1 to CH4, which are received by station device 2-1. The station device may determine that radio channels CH1 to CH4 are available for use and transmit data frames 11-31 to 11-34. In other words, data frames can be transmitted using the entire 80 MHz channel bandwidth.

On the other hand, even if station device 2-1 transmits an RTS frame, there are cases where the CTS frame cannot be received on some of CH1 to CH4. For example, access point device 1-1 receives RTS frames 11-41 to 11-44 on each of CH1 to CH4, checks the wireless channel conditions, determines that only CH3 and CH4 are idle, and transmits CTS frames (11-53, 11-54) only to CH3 and CH4. If station device 2-1 cannot receive a CTS frame on CH1, which is the primary channel, it cannot transmit a data frame on any of CH1 to CH4. In other words, the decision on whether to transmit a data frame depends on the conditions of the primary channel.

As another example, there may be cases where a CTS frame is received on the primary channel, CH1, but not on any of CH1 to CH4. For example, an access point device that receives RTS frames 11-61 to 11-64 on each of CH1 to CH4 checks the wireless channel conditions and determines that only CH1 and CH2 are idle, and transmits CTS frames (11-71, 11-72) only to CH1 and CH2. Although station device 2-1 is able to transmit data frames because it received a CTS frame on the primary channel, CH1, it detects that only CH1 and CH2 are idle, and transmits data frames 11-81 and 11-82. In other words, station device 2-1 can only use 40 MHz of the 80 MHz bandwidth.

In addition, the access point device may write information indicating the primary channel set in the wireless communication system that it configures in an OCI (Operating Channel Information) information element or the like. The access point device includes the OCI information element in management frames such as beacons and probe responses and transmits them to the station device. The station device can identify the primary channel from the contents of the OCI information element included in the received management frame. The access point device may write information indicating the primary channel in an information element other than the OCI information element, include it in the management frame, and transmit it to the station device.

An overview of Non-Primary Channel Access (NPCA) is provided below. First, in the channel access method of the prior art, as previously explained using Figure 11, when the operating bandwidth is composed of multiple 20 MHz subchannels, if a transmission opportunity (transmission right) is acquired on the 20 MHz subchannel set as the primary channel, the system can proceed to the step of determining whether the remaining subchannels can be used. In other words, if a transmission opportunity cannot be acquired on the 20 MHz subchannel set as the primary channel, the remaining subchannels cannot be used either. NPCA is a technology that improves frequency utilization efficiency by allowing channel access that can acquire transmission opportunities on subchannels other than the primary channel without acquiring a transmission opportunity on the primary channel, which was required in the prior art. Specifically, even if a transmission opportunity on the primary channel cannot be acquired, if a transmission opportunity on the NPCA primary channel (also referred to as the NPCA primary channel or secondary primary channel) is attempted and acquired, frames can be transmitted on other idle subchannels as well. From the perspective of channel access, the NPCA primary channel can be said to have a role equivalent to that of the primary channel.

NPCA is a technology in which, when the NAV is set to the 20 MHz primary channel and is busy due to, for example, the occurrence of OBSS frame transmission/reception, some or all of the wireless communication devices belonging to the BSS make a channel transition (channel switch) to the NPCA primary channel, and if a transmission opportunity is obtained at the channel transition destination, frames may be transmitted and received between the wireless communication devices. Here, the NPCA primary channel is a sub-channel other than the primary channel that is included in the operation bandwidth (operation channel) of the wireless communication system. It is generally a 20 MHz sub-channel, but it can also be a sub-channel with a larger bandwidth. Regardless of whether frames are transmitted and received on the NPCA primary channel, the system will basically return to the primary channel before the NAV set by the OBSS expires and attempt to obtain a transmission opportunity on the primary channel. If medium access recovery processing is allowed, the system may return to the primary channel after the NAV set by the OBSS expires. Note that frames transmitted via OBSS are referred to as OBSS frames.

The NPCA establishment procedure (also referred to as the configuration procedure) according to this embodiment will now be described. The access point device may store information related to the NPCA in an NPCA information element and notify it in management frames such as beacons and probe responses. Figure 9 shows an example of the configuration of an NPCA information element. The NPCA information element includes a field indicating at least one NPCA primary channel (NPCA primary channel, secondary primary channel), but may also include fields indicating other NPCA primary channel candidates. As mentioned above, channels (frequencies) in wireless LANs are basically handled in 20 MHz subchannel units, and the NPCA primary channel field may contain a channel number assigned in 20 MHz units. The NPCA primary channel may be 20 MHz wide or wider; for example, if the NPCA primary channel is 40 MHz wide, a channel number corresponding to that may be listed.

The NPCA information element may include a field indicating the NPCA maximum bandwidth. The NPCA maximum bandwidth indicates the maximum bandwidth that may be used for transmitting and receiving frames when a transmission opportunity is obtained on the NPCA primary channel.

The NPCA primary channel and NPCA maximum bandwidth may be changed dynamically or may be set to a fixed value. The NPCA primary channel and NPCA maximum bandwidth may be determined by monitoring wireless frames transmitted and received in OBSSs surrounding the BSS in question, and based on statistical information created from bandwidth occupancy status, frame transmission and reception frequency, received power in the BSS in question, etc. In this case, information obtained by the access point device via other station devices using functions such as neighbor reporting and beacon reporting may be used. The NPCA primary channel may be set to a channel that is a predetermined minimum separation bandwidth (also referred to as minimum separation channel, minimum number of separation channels, etc.) away from the primary channel. The minimum separation bandwidth may be determined in advance using an MIB (Management Information Base), etc. In the 6 GHz band, channel numbers 5, 21, 37, 53, 59, 69, 85, 101, 117, 133, 149, 165, 181, 197, 213, and 229 are designated as PSCs (Preferred Scanning Channels) to reduce the number of scanned channels, and the NPCA primary channel may be selected from among the PSCs.

The NPCA information element may include a field indicating the NPCA execution threshold, which indicates the condition value for transitioning to the NPCA primary channel. Examples of NPCA execution thresholds include the NPCA NAV threshold, NPCA bandwidth threshold, and NPCA received power threshold. The purpose of setting these values is to prevent unconditional transition to the NPCA primary channel and improve the effectiveness of actual frequency utilization efficiency when transitioning to the NPCA primary channel. Therefore, if this purpose can be achieved, condition values other than the three types mentioned above may be adopted and described in the NPCA execution threshold field of the NPCA information element. The NPCA information element may include at least one condition value from the NPCA NAV threshold, NPCA bandwidth threshold, NPCA received power threshold, and other thresholds, or it may include multiple condition values. Furthermore, what is described in the NPCA execution threshold field does not necessarily have to be a threshold, but may also be a value, index value, or range. These condition values may be managed by the MIB. Note that the content described above as being written in the NPCA execution threshold field does not necessarily have to be notified by the access point device, and may be a value specified by the standard and commonly used by wireless communication devices that comply with the standard.

The NPCA information element may include an NPCA enable/disable field that indicates whether NPCA is enabled or disabled at the time a management frame or the like containing the NPCA information element is transmitted. The access point devices that make up the BSS can monitor wireless frames transmitted and received in surrounding OBSSs, and switch between enabling and disabling NPCA depending on the bandwidth occupancy status, frame transmission and reception frequency, and reception power in the BSS. If the NPCA enable/disable field indicates NPCA is disabled, wireless communication devices included in the BSS will not execute NPCA. If the NPCA enable/disable field indicates NPCA is enabled, wireless communication devices included in the BSS may execute NPCA.

In this embodiment, the negotiation procedure that serves as preliminary preparation for executing NPCA will be explained using the sequence diagram in Figure 10. While Figure 10 shows station device 2-1 as an example, it may be any station device included in station device 2A. Station device 2-1 that intends to execute NPCA may transmit an NPCA participation request frame (10-1) to access point device 1-1. The NPCA participation request frame may include capability information of the station device, and examples of capability information may include the delay time required to transition between the primary channel and the NPCA primary channel (channel transition delay time), as well as information specific to the NPCA primary channel (maximum channel bandwidth, maximum operating bandwidth, maximum bandwidth, maximum MCS (Modulation and Coding Scheme), maximum number of streams, maximum transmit power, receiver sensitivity, etc.).

The access point device 1-1 transmits an NPCA participation response frame (10-2) to the station device 2-1. The NPCA participation response frame (10-2) contains at least status information indicating whether the station device 2-1 has "permitted (success, accepted)" or "rejected (failed)" the NPCA. The access point device 1-1 may determine the content of the status information in accordance with the NPCA permission conditions. The NPCA permission conditions may be managed using an MIB or the like.

The access point device 1-1 may determine whether to "permit (succeed, accept)" or "reject (fail)" the NPCA for the station device 2-1 based on the station device's capability information included in the NPCA participation request frame (10-1). For example, a channel transition delay time upper limit may be set in the MIB or the like, and the NPCA permission condition (also referred to as the NPCA participation condition or NPCA acceptance condition) may be that the channel transition delay time of the station device is shorter than the channel transition delay time upper limit ("less than or equal to (≦)" or "less than (<)")). If the channel transition delay time of the station device is longer than the channel transition delay time upper limit ("exceeds (>)" or "greater than or equal to (≧)"), it may determine that the efficiency of NPCA in the entire wireless communication system may be reduced, and may "reject (fail)" the NPCA participation request of the station device.

Alternatively, the access point device may decide whether to "permit (succeed, accept)" or "reject (fail)" NPCA to the station device without basing it on the station device capability information included in the NPCA participation request frame (10-1). For example, the maximum number of NPCA-enabled station devices that the access point device can manage (the upper limit of the number of NPCA station devices) may be set in an MIB or the like, and the NPCA permission condition (also referred to as the NPCA participation condition or NPCA acceptance condition) may be that the number of stations permitted for NPCA be kept less than the maximum number of NPCA station devices ("less than or equal to (≦)" or "less than (<)"). If permitting NPCA to the station device would exceed the maximum number of NPCA station devices ("exceed (>)" or "greater than or equal to (≧)"), the access point device may determine that the efficiency of NPCA in the entire wireless communication system may be reduced, and may "reject (fail)" the NPCA participation request from the station device.

NPCA permission conditions are not limited to those based on the upper limit of channel transition delay time and the maximum number of NPCA station devices mentioned above. Any conditions can be used as long as they can limit the station devices that are capable of NPCA within the BSS managed by the access point device.

The access point device 1-1 can adjust and limit the number of station devices that execute NPCA by notifying "permission (success, acceptance)" or "denial (failure)" in the status information of the NPCA participation response frame (10-2). One reason for imposing such a limit is that as the number of station devices participating in NPCA increases, the competition for medium acquisition among each station device increases after the NPCA primary channel transition, which can result in poor efficiency. However, station devices that are notified of "permission (success, acceptance)" in the status information of the NPCA participation response frame (10-2) do not necessarily have to execute NPCA.

There are at least two methods for enabling the NPCA operation of station device 2-1. In method 1, the access point device 1-1 may "enable (valid, possible)" the NPCA operation of station device 2-1 by notifying "allowed (success, accepted)" in the status information of the NPCA participation response frame (10-2). In method 2, the access point device 1-1 may "enable (valid, possible)" the NPCA operation of station device 2-1 by sending an NPCA enable frame (10-3) in addition to "allowed (success, accepted)" in the status information of the NPCA participation response frame (10-2). The access point device 1-1 may "disable (not possible)" the NPCA operation of station device 2-1 by sending an NPCA disable frame (10-4). The access point device 1-1 may report the NPCA valid frame (10-3) or the NPCA invalid frame (10-4) using a broadcast frame, or may notify the frame individually using a unicast frame. By broadcasting the NPCA valid frame or NPCA invalid frame to station devices, it is possible to enable or disable NPCA collectively throughout the entire wireless communication system. By individually transmitting the NPCA valid frame or NPCA invalid frame to station devices, it is possible to flexibly control and adjust the number of station devices participating in the NPCA. The access point device may decide whether to select Method 1 or Method 2 through settings in the MIB or the like, depending on operational policies, etc.

NPCA join response frames, NPCA valid frames, NPCA invalid frames, etc. may be management frames (action frames, etc.). The NPCA join request may be included in the association request sent by the station device 2-1 when connecting to the access point device 1-1, and the NPCA join response may be included in the association response sent by the access point device 1-1 to the station device 2-1.

The station device 2-1 may unilaterally notify the access point device 1-1 that it will discontinue execution of the NPCA by sending an NPCA withdrawal request frame (10-5) to the access point device 1-1. Alternatively, the station device 2-1 may check the value of the status information (such as "Permitted (success, accepted)" or "Rejected (failure)") included in the NPCA withdrawal response frame (10-6) sent from the access point device 1-1, and if the value is "Permitted (success, accepted)," discontinue execution of the NPCA.

The NPCA withdrawal request frame and NPCA withdrawal response frame may be management frames (such as action frames). The NPCA withdrawal request may be included in a disassociation frame or deauthentication frame sent by the station device 2-1 when disconnecting from the access point device 1-1.

An example of the operation of NPCA (Non-Primary Channel Access) in this embodiment will be described using Figure 12. Assume that NPCA has been enabled for access point device 1-1 and station device 2-1 through the negotiation procedure described in Figure 10. Assume that wireless communication system 3-1 (BSS1) and wireless communication system 3-2 (BSS2), whose wireless communication coverage overlaps with BSS1, both use 20 MHz subchannel CH1 as their primary channel. Assume also that CH4 is set as the NPCA primary channel. Considering BSS1 as the center, BSS2, whose wireless coverage overlaps, is the BSS configured by access point device 1-2, a wireless communication device other than BSS1 configured by access point device 1-1. BSS2 is called an OBSS (Overlapping BSS), and frames transmitted and received in BSS2 are called OBSS frames. Similarly, if we consider BSS2 as the center, BSS1 becomes the OBSS, and frames sent and received in BSS1 become OBSS frames. In the example of Figure 12, the behavior of NPCA will be explained with BSS1 as the main focus, BSS2 is called the OBSS, and frame sending and receiving within BSS1 is called a BSS frame, and frame sending and receiving within BSS2 is called an OBSS frame. Also, for ease of explanation, Figure 12 shows only one station device 2-1, but multiple station devices 2A may also be present.

When access point device 1-2, which is part of an OBSS and has obtained a transmission opportunity on primary channel CH1, decides to transmit and receive wireless frames only on the 20 MHz bandwidth of CH1 out of the 80 MHz bandwidth of CH1 to CH4, it transmits an RTS frame 12-21 to station device 2-2, its communication partner. Station device 2-2 receives RTS frame 12-21 on CH1 and transmits a CTS frame 12-22. The Duration field of RTS frame 12-21 indicates T21 as the period for which the obtained transmission opportunity will be maintained, indicating that the period T21 will be used as the time for frame exchange (frame transmission/receive) 12-23 between access point device 1-2 and station device 2-2. Similarly, the Duration field of CTS frame 12-22 specifies T22 as the duration for which the acquired transmission opportunity will be maintained, indicating that the time until T22 expires will be used for frame exchange 12-23 between access point device 1-2 and station device 2-2. Note that frame exchange 12-23 consists of one or more frame transmissions between access point device 1-2 and station device 2-2 within BSS2, which corresponds to OBSS.

The access point device 1-1 and station device 2-1 belonging to BSS1 can receive RTS frame 12-21 and CTS frame 12-22 in OBSS, and update their NAV according to the Duration field included in each frame. They detect that at least CH1 is occupied by OBSS for time T21 after receiving RTS frame 11-21, or for time T22 after receiving CTS frame 12-22, and manage CH1 so that frame transmission and reception in BSS1 does not occur during that period. When a transmission opportunity for primary channel CH1 is acquired through OBSS, the access point device 1-1 and station device 2-1 belonging to BSS1 and with NPCA enabled may proceed to the step of determining whether to start NPCA.

The following describes the operation when the NPCA information element includes an NPCA NAV threshold. The access point device 1-1 or station device 2-1 will not transition to the NPCA primary channel if the NAV value set by the OBSS (such as the aforementioned T21 and T22 values) is below the NPCA NAV threshold or a value based on information indicating the NAV threshold ("less than or equal to (≦)" or "less than (<)"). The access point device 1-1 or station device 2-1 may transition to the NPCA primary channel if the NAV value set by the OBSS (such as the aforementioned T21 and T22 values) is above the NPCA NAV threshold ("exceeds (>)" or "greater than or equal to (≧)"). By setting an NPCA NAV threshold as the NPCA primary channel transition condition and controlling transition to the NPCA primary channel, inefficient channel transitions are suppressed.

Figure 12 shows an example where the NAV value set by OBSS (such as the aforementioned T21 and T22 values) exceeds the NPCA NAV threshold, and access point device 1-1 and station device 2-1 transition to the NPCA primary channel. A hardware delay equivalent to the aforementioned channel switch delay occurs for the channel transition, the magnitude of which varies depending on the wireless communication device.

After access point device 1-1 and station device 2-1 transition to the NPCA primary channel, access point device 1-1 waits for a period of xIFS (referring to any type of IFS, such as PIFS, AIFS, or DFIS), then starts counting down a backoff counter set with a random backoff time. When the backoff counter value reaches 0, it becomes possible to transmit frames. The example in Figure 12 shows a case in which access point device 1-1 acquires and manages a transmission opportunity. In preparation for frame exchange 12-13, access point device 1-1 transmits an ICF (Initial Control Frame) 12-11, and station device 2-1 transmits an ICF response 12-12. Although not shown in Figure 12, if multiple station devices 2A are participating in NPCA, each station device transmits an ICF response 12-12. Note that frame exchange 12-13 consists of one or more frame transmissions between access point device 1-1 and station device 2A within BSS1.

An MU-RTS (Multi-User RTS) frame or a BSRP (Buffer Status Report Poll) frame may be used as the ICF 12-11. The MU-RTS frame specifies the radio resources (radio resource units specified on the frequency axis, time axis, space axis, etc.) to be allocated to each of multiple station devices 2A, and allocates the radio resources to station devices 2A that respond with an ICF response 12-12, transmitting a downlink radio frame. The downlink frame transmission is included in frame exchange 12-13. Each station device 2A that receives the BSRP frame requests radio resources by transmitting an ICF response 12-12 to notify the amount of data stored in its transmission buffer and scheduled for transmission. The access point device 1-1 that receives the ICF response 12-12 transmits a trigger frame containing information specifying the radio resources to be allocated to each station device in response to the request, and each station device transmits an uplink radio frame using the allocated radio resources. The trigger frame transmission and the uplink radio frame transmission are included in frame exchange 12-13.

In the example of Figure 12, because ICF response 12-12 is transmitted on CH2 to CH4, frame exchange 12-13 is also performed on CH2 to CH4. Frame exchange 12-13 may be performed only on the channel from CH2 to CH4 on which ICF response 12-12 was transmitted. For example, if ICF response 12-12 is transmitted only on CH4, which is the NPCA primary channel, and CH2, frame exchange 12-13 may also be performed with some 20 MHz subchannels punctured, such that only CH4 and CH2 are used.

After the frame exchange 12-13 is completed, the access point device 1-1 and station device 2A may transition from the NPCA primary channel to the primary channel without receiving instructions from another wireless communication device before the end of the NAV set by the OBSS (T21 set by the RTS frame 12-21, T22 set by the CTS frame 12-22, etc.).

Alternatively, after frame exchange 12-13 is completed, a channel return frame 12-14 may be sent from access point 1-1 to station device 2A to instruct a channel transition from the NPCA primary channel to the primary channel. The NAV value for the primary channel may be stored in channel return frame 12-14. If access point device 1-1 has the ability to keep the NAV for the primary channel up to date in addition to the NAV for the NPCA primary channel while operating on the NPCA primary channel, station device 2A will be able to grasp the latest NAV information for the primary channel before returning from the NPCA primary channel to the primary channel.

Basically, access point device 1-1 and station device 2A return to the primary channel before the end of the NAV set by OBSS (T21 set by RTS frame 12-21, T22 set by CTS frame 12-22, etc.). However, if they return to the primary channel after the NAV (T21 or T22), the latest NAV information would normally be unknown and medium access recovery processing would be required, resulting in a delay before the acquisition of transmission opportunities on the primary channel could be resumed. However, by access point device 1-1 notifying the latest NAV on the primary channel in channel return frame 12-14 transmitted on the NPCA primary channel, station device 2A does not need to perform medium access recovery processing when transitioning to the primary channel, and can resume acquiring transmission opportunities on the primary channel relatively quickly.

An example of the NPCA (Non-Primary Channel Access) procedure in this embodiment will be explained using Figure 13. While Figure 12 shows an example in which the NAV is calculated based on the RTS frame 12-21 and CTS frame 12-22 in the OBSS, Figure 13 differs in that the NAV is calculated from the frame exchange 13-23 in the OBSS. Other aspects, such as the configuration, mechanism, and behavior of the ICF 13-11, ICF response 13-12, frame exchange 13-13, and Channel return frame 13-14 in Figure 13, are the same as those of the ICF 12-11, ICF response 12-12, frame exchange 12-13, and Channel return frame 12-14 in Figure 12.

The access point device 1-1 and station device 2-1 belonging to BSS1 receive frame exchange 13-23 in the OBSS and, by referencing the PHY header, MAC header, etc., can determine the time (T31) that the primary channel will be occupied by frame exchange 13-23, as well as the planned use of 20 MHz sub-channels other than the primary channel. The PHY header structure differs depending on the standard (IEEE802.11a, IEEE802.11b, IEEE802.11g, IEEE802.11n, IEEE802.11ac, IEEE802.11ax, IEEE802.11be, IEEE802.11bn, etc.), and each will be explained below.

If frame exchange 13-23 begins with an HE PPDU (IEEE 802.11ax PPDU), the BSS color field in the HE-SIG-A field can be used to determine whether it corresponds to OBSS, the Bandwidth field can be used to determine the planned use of other 20 MHz subchannels including the primary channel, and the TXOP field can be used to determine the planned medium occupancy time (equivalent to T31) and set the NAV.

If frame exchange 13-23 begins with an EHT PPDU (IEEE 802.11be PPDU) or a UHR PPDU (IEEE 802.11bn PPDU), the BSS color field in the U-SIG field can be used to determine whether it is an OBSS, the Bandwidth field can be used to determine the planned use of other 20 MHz subchannels including the primary channel, and the TXOP field can be used to determine the planned medium occupancy time (equivalent to T31) and set the NAV.

If frame exchange 13-23 begins with a VHT PPDU (IEEE 802.11ac PPDU), it can be determined whether or not it corresponds to OBSS from the contents of the Group ID field and Partial AID in the VHT-SIG-A field, and the planned use of other 20 MHz subchannels, including the primary channel, can be determined from the BW field. The Length field of the L-SIG can be used as a guide to the medium occupancy time (equivalent to T31) to set the NAV.

If frame exchange 13-23 begins with an HT PPDU (IEEE 802.11n PPDU) or non-HT PPDU, it is not possible to obtain from the PHY header information such as whether it corresponds to OBSS, information about the medium occupancy time, or information about the planned use of other 20 MHz subchannels, including the primary channel. By decoding the MAC header and referencing Address 1, Address 2, Address 3, and Address 4, it is possible to determine whether it corresponds to OBSS, and to obtain information about the medium occupancy time (equivalent to T31) from the Duration field and set the NAV.

The following describes the operation when the NPCA information element includes the NPCA bandwidth threshold or information indicating the NPCA bandwidth threshold. When the OBSS frame exchange 13-23 begins with an EHT PPDU, the access point device 1-1 or station device 2-1 demodulates the PHY header of the EHT PPDU and can determine whether it corresponds to an OBSS from the BSS color field of the U-SIG field, and can determine the planned use of other 20 MHz subchannels, including the primary channel, from the Bandwidth field. If the bandwidth planned to be occupied by the OBSS exceeds the NPCA bandwidth threshold ("exceeds (>)" or "greater than or equal to (≧)"), the access point device 1-1 or station device 2-1 will not transition to the NPCA primary channel. If the bandwidth planned to be occupied by the OBSS is below the NPCA bandwidth threshold ("less than or equal to (≦)" or "less than (<)"), the station device 2-1 may transition to the NPCA primary channel. By setting an NPCA bandwidth threshold as the NPCA primary channel transition condition, transitions to the NPCA primary channel are controlled, thereby suppressing inefficient channel transitions.

The following describes the operation when the NPCA information element includes the NPCA received power threshold or information indicating the NPCA received power threshold. In Figure 12, the access point device 1-1 or station device 2-1 receives an RTS frame 12-21 or a CTS frame 12-22 and can calculate the OBSS received power (RSSI) related to the wireless frames transmitted and received via OBSS. In Figure 13, the access point device 1-1 or station device 2-1 can calculate the OBSS received power related to the wireless frames transmitted and received via OBSS from the OBSS frame exchange 13-23. When the access point device 1-1 or station device 2-1 receives a frame transmitted and received via OBSS and its received power (referred to as the OBSS received power) exceeds the NPCA received power threshold ("exceeds (>)" or "greater than or equal to (≧)"), it does not transition to the NPCA primary channel. Access point device 1-1 or station device 2-1 may transition to the NPCA primary channel if the OBSS received power falls below the NPCA received power threshold ("less than or equal to (≦)" or "less than (<)"). By setting an NPCA received power threshold and setting it as the NPCA primary channel transition condition, transition to the NPCA primary channel is controlled, thereby suppressing inefficient channel transitions.

If the NPCA execution threshold field of the NPCA information element includes multiple conditions, such as the NPCA NAV threshold, the NPCA bandwidth threshold, the NPCA received power threshold, or information indicating some or all of these, the behavior of the access point device 1-1 and the station device 2-1 can vary widely. For example, the transition to the NPCA channel may occur only when all conditions are met, or the transition to the NPCA channel may occur when a specific combination of multiple conditions is met (for example, a combination of the NPCA NAV threshold and the NPCA bandwidth threshold, or a combination of the NPCA NAV threshold and the NPCA received power threshold, etc.), or the transition to the NPCA channel may occur when any one of the conditions is met. Which condition is selected may be determined by the policy of the access point device 1-1, or may be specified in one of the fields included in the NPCA information element, or may be specified in the MIB.

Figure 3 shows an architecture diagram of wireless communication devices (including access point devices and station devices). This section explains the primitives used for notifications (including requests, responses, confirmations, indications, etc.) between the MAC layer and the PHY layer via the PHY SAP for NPCA.

Using Figure 14, we will explain a first example of a Primitive sequence for realizing NPCA. The MAC layer configures the PHY layer by notifying (also called issuing) the PHY layer with Primitive PHY-CONFIG.request 14-1. PHY-CONFIG.request 14-1 takes the parameter PHYCONFIG_VECTOR as an argument. PHYCONFIG_VECTOR is a collection of parameters for configuring the PHY layer, such as the parameters OPERATION_CHANNEL, CHANNEL_WIDTH, CENTER_FREQUENCY_SEGMENT_0, and CENTER_FREQUENCY_SEGMENT_1. For example, the parameter OPERATED_CHANNEL is information indicating a value used to specify the primary channel, and the parameter CHANNEL_WIDTH is information indicating a value used to specify the operation bandwidth of the wireless communication system. To notify the PHY layer of the NPCA primary channel, the MAC layer may include the parameter NPCA_CHANNEL in PHYCONFIG_VECTOR, and the parameter NPCA_CHANNEL may be set to information indicating a value used to specify the NPCA primary channel.

The information indicating the value used to specify the primary channel (also referred to as primary channel information or primary channel number) is set in the MIB dot11CurrentPrimaryChannel at the PHY layer. The information indicating the value used to specify the NPCA primary channel (also referred to as NPCA primary channel information or NPCA primary channel number) may be set in a different MIB from dot11CurrentPrimaryChannel at the PHY layer.

The MAC layer notifies the PHY layer of the data string it is requesting to send using Primitive PHY-DATA.request 14-2, setting DATA and USER_INDEX as arguments. The argument DATA contains the data string that the PHY layer is requested to frame and send. The PHY layer notifies it that it has received the data string using Primitive PHY-DATA.confirm 14-3.

The MAC layer notifies the PHY layer of a request to transmit a wireless frame by setting TXVECTOR as an argument to Primitive PHY-TXSTART.request14-4. TXVECTOR is a collection of parameters related to the wireless frame generated by the PHY layer, such as the parameters FORMAT and CH_BANDWIDTH. The parameter FORMAT is information indicating the type of PPDU (HT PPDU, VHT PPDU, HE PPDU, EHT PPDU, etc.), and the parameter CH_BANDWIDTH is information indicating the transmission bandwidth. The MAC layer may include the parameter NPCA_CHANNEL or a parameter instructing transmission using the NPCA primary channel in TX_VECTOR to notify the PHY layer whether the wireless frame should be transmitted on the primary channel or the NPCA primary channel. The parameter NPCA_CHANNEL may be a Boolean parameter, and may be used such that FALSE instructs transmission on the primary channel and TRUE instructs transmission on the NPCA primary channel, or vice versa. When transmission on the primary channel is instructed, the carrier sensing procedure first targets the primary channel. On the other hand, when transmission on the NPCA primary channel is instructed, the carrier sensing procedure first transitions from the primary channel to the NPCA primary channel, and the NPCA primary channel is targeted for carrier sensing, avoiding transmission on at least the primary channel.

The parameter NPCA_CHANNEL may be set with information indicating the value used to specify the aforementioned NPCA primary channel (also referred to as NPCA primary channel information or NPCA primary channel number). If the parameter NPCA_CHANNEL stores the NPCA primary channel number, it is assumed that transmission on the NPCA primary channel is instructed, and the carrier sense procedure first involves transitioning from the primary channel to the NPCA primary channel, making the NPCA primary channel the target of carrier sense, and at least avoiding transmission on the primary channel. On the other hand, if the value stored in the parameter NPCA_CHANNEL is a special value such as all zeros (all octets are X'00) or all Fs (all octets are X'FF), it is assumed that transmission on the primary channel is instructed, and the carrier sense procedure first involves making the primary channel the target of carrier sense. Note that the special value is not limited to all zeros or all Fs, and may be any value that is pre-set as a number indicating the primary channel, such as the aforementioned primary channel information or primary channel number.

The PHY layer uses the Primitive PHY-RXSTART.request to notify the MAC layer of the reception of a wireless LAN frame. The argument to Primitive PHY-RXSTART.request is set to RXVECTOR. RXVECTOR is a collection of parameters related to the wireless frame received by the PHY layer, such as the parameters FORMAT and CH_BANDWIDTH. The parameter FORMAT is information indicating the type of PPDU (HT PPDU, VHT PPDU, HE PPDU, EHT PPDU, etc.), and the parameter CH_BANDWIDTH is information indicating the reception bandwidth. The PHY layer may include the parameter NPCA_CHANNEL in RX_VECTOR to notify the MAC layer whether the wireless frame was received on the primary channel or the NPCA primary channel. The parameter NPCA_CHANNEL may be a Boolean, and may be used such that FALSE means reception on the primary channel and TRUE means reception on the NPCA primary channel, or vice versa.

In this way, in the first example, the basic configuration of the PHY layer is first performed with Primitive PHY-CONFIG.request 14-1, and the timing of NPCA execution (channel transition from the primary channel to the NPCA primary channel) may be indicated with Primitive PHY-TXSTART.request.

A second example of a Primitive sequence for realizing NPCA will be explained using Figure 15. In the first example explained in Figure 14, Primitive PHY-CONFIG.request notifies NPCA primary channel information from the MAC layer to the PHY layer, but execution of NPCA is instructed by Primitive PHY-TXSART.request. In the second example explained in Figure 15, Primitive PHY-CONFIG.request notifies NPCA primary channel information from the MAC layer to the PHY layer and also instructs execution of NPCA. In other respects, the contents explained in Figures 14 and 15 are equivalent.

The MAC layer configures the PHY layer by notifying (also known as issuing) the PHY layer with the Primitive PHY-CONFIG.request. PHY-CONFIG.request takes the parameter PHYCONFIG_VECTOR as an argument. For example, PHYCONFIG_VECTOR may include the parameter NPCA_CHANNEL, which may be information indicating the value used to specify the NPCA primary channel. PHYCONFIG_VECTOR may also include the parameter NPCA_CHANNEL_EN. The parameter NPCA_CHANNEL_EN may be a Boolean parameter, and may be used such that FALSE indicates channel setting to the primary channel and TRUE indicates channel setting to the NPCA primary channel, or vice versa.

For example, by issuing PHY-CONFIG.request15-1 with the parameter NPCA_CHANNEL_EN set to FALSE, the channel may first be set to the primary channel, or if it is already set to the NPCA primary channel, NPCA may be cancelled (a channel transition from the NPCA primary channel to the primary channel). By issuing PHY-CONFIG.request15-2 with the parameter NPCA_CHANNEL_EN set to TRUE, NPCA is executed (a channel transition from the primary channel to the NPCA primary channel).

The MAC layer notifies the PHY layer of a request to send a wireless frame by setting TXVECTOR as an argument to Primitive PHY-TXSTART.request 15-5. In the second example for implementing NPCA, the channel transition from the primary channel to the NPCA primary channel is completed before PHY-TXSTART.request is issued.

The information indicating the value used to specify the primary channel (also referred to as primary channel information or primary channel number) mentioned above is set in MIB dot11CurrentPrimaryChannel at the PHY layer. Information indicating the value used to specify the NPCA primary channel (also referred to as NPCA primary channel information or NPCA primary channel number) may also share MIB dot11CurrentPrimaryChannel at the PHY layer. In other words, primary channel information may be set in dot11CurrentPrimaryChannel when frames are sent and received on the primary channel, and NPCA primary channel information may be set when frames are sent and received on the NPCA primary channel after NPCA is executed.

A third example of a Primitive sequence for realizing NPCA will be explained using Figure 16. In the second example explained in Figure 15, Primitive PHY-CONFIG.request notifies the PHY layer of NPCA primary channel information from the MAC layer, and also instructs the execution of NPCA. In the third example explained in Figure 16, Primitive PHY-CONFIG.request notifies the PHY layer of NPCA primary channel information from the MAC layer, but Primitive PHY-NPCA.request instructs the PHY layer to execute NPCA. In other respects, the contents explained in Figures 15 and 16 are equivalent. Note that Primitive PHY-NPCA.request is a different Primitive from Primitive PHY-CONFIG.request and PHY-TXSTART.request.

The MAC layer configures the PHY layer by notifying (also known as issuing) the PHY layer with the Primitive PHY-CONFIG.request. The PHY-CONFIG.request takes the parameter PHYCONFIG_VECTOR as an argument. For example, PHYCONFIG_VECTOR may include the parameter NPCA_CHANNEL, which may be information indicating the value used to specify the NPCA primary channel.

The MAC layer may issue a Primitive PHY-NPCA.request to the PHY layer to instruct a channel transition from the primary channel to the NPCA primary channel. The parameter NPCA_CHANNEL_EN may be included as an argument. The parameter NPCA_CHANNEL_EN may be a Boolean parameter, and may be used in such a way that FALSE instructs channel setting to the primary channel and TRUE instructs channel setting to the NPCA primary channel, or vice versa.

For example, the MAC layer notifies (or issues) the PHY layer with Primitive PHY-CONFIG.request 16-1, thereby performing basic configuration of the PHY layer and setting the channel to the primary channel. Next, the MAC layer may issue Primitive PHY-NPCA.request with the parameter NPCA_CHANNEL_EN set to TRUE to instruct the channel setting from the primary channel to the NPCA primary channel.

Information indicating the value used to specify the primary channel (also referred to as primary channel information or primary channel number) is set in the MIB dot11CurrentPrimaryChannel at the PHY layer. Information indicating the value used to specify the NPCA primary channel (also referred to as NPCA primary channel information or NPCA primary channel number) may be set in a MIB different from dot11CurrentPrimaryChannel at the PHY layer.

The above describes an exemplary embodiment in which a transmission opportunity is acquired by transitioning from a primary channel to a subchannel other than the primary channel using NPCA (Non-Primary Channel Access) technology, and frame exchange is performed. This embodiment can also be applied to DSO (Dynamic Subchannel Operation) technology and IDC (In-Device Coexistence) technology. Modern wireless communication devices are equipped with multiple wireless communication technologies. For example, smartphones are equipped with wireless LAN, 4G/5G cellular communication technology, Bluetooth (registered trademark), UWB (Ultra Wideband), and other wireless communication technologies. When different wireless communication technologies use the same frequency band, wireless interference can occur, resulting in degradation of the wireless communication performance of each. One method for avoiding this is DSO technology or IDC technology, which controls different wireless communication technologies so that they do not use the same frequency during the same time period.
[2. Common to all embodiments]

The communications device of the present invention can communicate in frequency bands (frequency spectrum) known as unlicensed bands, which do not require permission to use from a country or region, but the frequency bands that can be used are not limited to this. For example, the communications device of the present invention can also be effective in frequency bands known as white bands (for example, frequency bands allocated for television broadcasting but unused in some regions) that are not actually used despite permission to use specific services from a country or region for the purpose of preventing interference between frequencies, or in shared spectrum (shared frequency bands) that are expected to be shared by multiple operators.

The program that runs on the wireless communication device according to the present invention is a program that controls the CPU and other components (a program that causes a computer to function) so as to realize the functions of the above-described embodiments of the present invention. Information handled by these devices is temporarily stored in RAM during processing, and is then stored in various ROMs or HDDs, from which it is read, modified, and written as needed by the CPU. The recording medium for storing the program may be any of semiconductor media (e.g., ROM, non-volatile memory card, etc.), optical recording media (e.g., DVD, MO, MD, CD, BD, etc.), magnetic recording media (e.g., magnetic tape, flexible disk, etc.), etc. Furthermore, not only are the functions of the above-described embodiments realized by executing the loaded program, but the functions of the present invention may also be realized by processing in cooperation with an operating system or other application programs, etc., based on the program's instructions.

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 is also included in the present invention. Furthermore, some or all of the communication devices 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 some or all 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.

Furthermore, the integrated circuit method is not limited to LSI, and may be realized using dedicated circuits or general-purpose processors. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, it may also be possible to use integrated circuits using that technology.

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 also 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.

The above describes an embodiment of the present invention in detail with reference to the drawings, but 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.

The present invention is suitable for use in communication devices and communication methods.

1-1, 1-2, 1-3, 1-4 Access point devices 2-1, 2-12, 2-13, 2-123, 2-2, 2-21, 2-23, 2-213, 2-3, 2-31, 2-32, 2-34, 2-312, 2-4 Station devices 3-1, 3-2, 3-3, 3-4 Communication area (coverage)
10000-1 Wireless communication device 10001-1 Upper layer unit 10001a-1 MAC layer frame generation unit 10001b-1 Upper layer control unit 10001c-1 Access function unit 10002-1 Autonomous distributed control unit 10002a-1 CCA unit 10002b-1 Backoff unit 10002c-1 Transmission decision unit 10003-1 Transmitting unit 10003a-1 Physical layer frame generation unit 10003b-1 Wireless transmitting unit 10004-1 Receiving unit 10004a-1 Wireless receiving unit 10004b-1 Signal demodulating unit 10005-1 Antenna section 11-11, 11-12, 11-13, 11-14, 11-21, 11-22, 11-23, 11-24, 11-31, 11-32, 11-33, 11-34, 11-41, 11-42, 11-43, 11-44, 11-53, 11-54, 11-61, 11-62, 11-63, 11-64, 11-71, 11-72, 11-81, 11-82 Frame 12-11, 12-12, 12-14, 12-21, 12-22 Frame 12-13, 12-23 Frame exchange 13-11, 13-12, 13-14 Frame 13-13, 13-23, Frame exchange 14-1, 14-2, 14-3, 14-4, 14-5 Primitive
15-1, 15-2, 15-3, 15-4, 15-5, 15-6 Primitive
16-1, 16-2, 16-3, 16-4, 16-5, 16-6, 16-7 Primitive
20000-1 MLD access point device 20000-2, 20000-3, 20000-4 sub-access point device 30000-1 MLD station devices 30000-2, 30000-3, 30000-4 sub-station devices

Claims (12)

A station device comprising an upper layer unit and a lower layer unit,
The upper layer unit determines that the lower layer unit transitions to an NPCA primary channel based on information (first information) indicating one or more values notified by an NPCA (Non-Primary Channel Access) information element.
Station equipment. 2. The station device according to claim 1,
a receiving unit for receiving a frame transmitted by the access point device,
the receiving unit receives a first frame transmitted by the access point device;
the first frame includes the NPCA information element;
The station device according to claim 1 . the receiving unit receives a second frame from a wireless communication device other than a BSS (Basic Service Set) configured by the access point device,
For the second frame, if at least one of the first information satisfies a channel transition condition,
The upper layer notifies the lower layer of a transition to the NPCA primary channel.
The station device according to claim 2 . One of the first information is a NAV (Network Allocation Vector) threshold,
the channel transition condition is that the NAV set based on the second frame exceeds the NAV threshold.
The station device according to claim 3. one of the first pieces of information is a bandwidth threshold;
the channel transition condition is that the bandwidth set based on the second frame falls below the bandwidth threshold;
The station device according to claim 3. one of the first information is a received power threshold;
the channel transition condition is that the received power of the second frame falls below the received power threshold.
The station device according to claim 3. An access point device for communicating with one or more station devices,
A transmitter unit is provided,
the transmitting unit transmits a frame to at least one of the one or more station devices;
The frame includes an NPCA information element,
The NPCA information element includes information indicating an NPCA primary channel.
Access point device. The NPCA information element includes information indicating one or more thresholds for a channel transition condition to the NPCA primary channel.
8. The access point device according to claim 7. The threshold is a NAV threshold.
9. The access point device according to claim 8. the threshold is a bandwidth threshold;
9. The access point device according to claim 8. The threshold is a received power threshold.
9. The access point device according to claim 8. A communication method in a wireless communication system configured with an access point device and one or more station devices,
The access point device transmits a frame including an NPCA information element to the station device;
The NPCA information element includes information indicating an NPCA primary channel and information indicating one or more thresholds for a channel transition condition to the NPCA primary channel;
the station device transitions to the NPCA primary channel when a frame received from a wireless communication device other than the BSS constituted by the access point device satisfies the channel transition condition;
Communication method.