Access point apparatus and wireless communication method

Abstract

To maintain response processing in such a state that a reception operation is disabled in the power saving state of an access point device.SOLUTION: When receiving a probe request from the station device, the first access point device performs both of a first operation of transmitting a probe response without including the MAC address of the second access point device and a second operation of transmitting a probe response including the MAC address of the second access point device.SELECTED DRAWING: Figure 11

Description

[Technical Field]

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

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

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

[0004] Furthermore, in the IEEE 802.11be standardization, discussions are underway to enable wireless communication devices to simultaneously use multiple frequency bands, channels, etc., and maintain multiple link connections for communication (Non-Patent Document 1). In the IEEE 802.11bn standardization, studies are underway to achieve goals such as further increasing throughput, reducing latency, and reducing the power consumption of access point devices (Non-Patent Document 2). As for methods for reducing the power consumption of access point devices, methods such as reducing the number of simultaneously used links, reducing the number of simultaneously used streams, and scheduling are being discussed (Non-Patent Document 3). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] IEEE 802.11 P802.11be Project Authorization Request [Non-patent document 2] IEEE 802.11 P802.11bn Project Authorization Request [Non-patent document 3] IEEE 802.11-24 / 2040r0 Summary of the Invention [Problem to be solved by the invention]

[0006] In reducing the power consumption of access point devices, it has been shown that the amount of power that can be reduced by reducing the number of simultaneously used links or streams is limited, and so reducing power consumption during reception is important (Non-Patent Document 3). Disabling various functional blocks is an effective way to reduce power consumption during reception. Depending on the functional block that is disabled, reception may become impossible, and current wireless LAN specifications are based on the premise that reception is always ongoing. Therefore, in order to significantly reduce power consumption in access point devices, communication processing when the access point device is in sleep mode becomes an issue. [Means for solving the problem]

[0007] The access point device and wireless communication method according to the present invention for solving the above-mentioned problems are as follows.

[0008] (1) That is, a first access point device according to one embodiment of the present invention is a first access point device that communicates with one or more station devices and one or more access point devices including a second access point device, and includes an antenna unit, a wireless communication unit that transmits and receives wireless frames using the antenna unit, and a wireless control unit that controls the wireless communication unit and performs CSMA (Carrier Sense Multiple Access) operation using IFS (Inter Frame Space) to control transmission, and when the wireless communication unit receives a probe request from one of the station devices, it performs both a first operation of transmitting a probe response without including the MAC address of the second access point device, and a second operation of transmitting a probe response including the MAC address of the second access point device.

[0009] (2) In addition, in the first access point device according to one aspect of the present invention, the IFS used in the first operation is different from the IFS used in the second operation.

[0010] (3) In the first access point device according to the aspect of the present invention, the second time instant is a time instant at which the MPDU is actually transmitted.

[0011] (4) Furthermore, in the first access point device according to one aspect of the present invention, the information indicating that the second operation is enabled includes capability information of the second access point device.

[0012] (5) Furthermore, a first access point device according to one embodiment of the present invention, while performing CSMA operation to transmit the probe response, stops transmitting the probe response when it receives a probe response including the MAC address of the first access point device.

[0013] (6) Furthermore, in a first access point device according to one embodiment of the present invention, when transmitting a probe response including a MAC address of the first access point device and subsequently transmitting a probe response including a MAC address of the second access point device in the second operation, the IFS used between transmitting the probe response including the MAC address of the first access point device and transmitting the probe response including the MAC address of the second access point device is a predetermined IFS different from SIFS (Short Inter Frame Space).

[0014] (7) Furthermore, a first access point device according to one embodiment of the present invention performs both the first operation and the second operation when the SSID included in the received probe request is a wild card SSID.

[0015] (8) Furthermore, a first access point device according to one embodiment of the present invention performs the first operation and transmits a probe response when the SSID included in the received probe request is a wildcard SSID, and includes in the probe response at least a multiple BSSID element including the MAC address of the second access point device.

[0016] (9) Furthermore, a first access point device according to one embodiment of the present invention includes an antenna unit, a wireless communication unit that transmits and receives wireless frames using the antenna unit, and a wireless control unit that controls the wireless communication unit and performs CSMA (Carrier Sense Multiple Access) operation using IFS (Inter Frame Space) to control transmission, and when information indicating that the second access point device will transition to a power saving state is received from one of the one or more access point devices, the wireless control unit performs both a first operation of transmitting a beacon frame using the CSMA operation without including a MAC address of the second access point device, and a second operation of transmitting a beacon frame using the CSMA operation including the MAC address of the second access point device.

[0017] (10) Furthermore, a wireless communication method according to one embodiment of the present invention controls transmission by performing CSMA (Carrier Sense Multiple Access) operation using IFS (Inter Frame Space), and when a probe request is received from one of the station devices, performs both a first operation of transmitting a probe response without including the MAC address of the second access point device, and a second operation of transmitting a probe response including the MAC address of the second access point device. [Effects of the Invention]

[0018] According to the access point device and wireless communication method of the present invention, the processing to be performed when the access point device goes into a sleep state is defined, and it is possible to reduce the impact of going into a sleep state. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram illustrating an example of a MAC layer frame configuration in a wireless LAN system. [Figure 2] FIG. 1 is a diagram illustrating an example of a PPDU configuration related to a wireless LAN system. [Figure 3] FIG. 1 is a diagram illustrating an example of a sounding procedure related to a wireless LAN system. [Figure 4] 1 is a diagram illustrating an example of a configuration of a communication system according to an aspect of the present invention. [Figure 5] 1 is a block diagram showing an example of the configuration of a station device according to an aspect of the present invention; [Figure 6] 1 is a block diagram illustrating an example of a configuration of an access point device according to an aspect of the present invention. [Figure 7] 1 is a diagram illustrating an example of a configuration of a wireless communication system according to an aspect of the present invention. [Figure 8] 1 is a diagram illustrating an example of a proxy response procedure in a wireless communication system according to an aspect of the present invention. [Figure 9] FIG. 2 is a timing chart illustrating an example of wireless medium access in a wireless communication system according to an embodiment of the present invention. [Figure 10] FIG. 10 is a diagram illustrating an example of a proxy response procedure of a communication system according to an aspect of the present invention. [Figure 11] FIG. 10 is a diagram illustrating an example of a proxy beacon transmission procedure of a communication system according to an aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The wireless communication system in this embodiment includes an access point device (AP, also referred to as a base station device) and multiple station devices (STA, also referred to as terminal devices). The communication system and network configured with the access point device and the station devices are called a basic service set (BSS, management range). The station device according to this embodiment can have the functions of an access point device. Similarly, the access point device according to this embodiment can have the functions of a station device. Therefore, hereinafter, when simply referring to a communication device or a wireless communication device, the communication device or wireless communication device can refer to both the access point device and the station device.

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

[0022] In the IEEE 802.11 system, each device can transmit multiple types of frames (communication frames) with a common frame format. The frames are defined in the physical (PHY) layer, medium access control (MAC) layer, and logical link control (LLC) layer.

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

[0024] The PHY header includes reference signals such as a short training field (STF) used for signal detection and synchronization, a long training field (LTF) used to acquire channel information for data demodulation, and control signals such as a signal (SIG) containing control information for data demodulation. Depending on the corresponding standard, STFs are classified as Legacy-STF (L-STF), High Throughput-STF (HT-STF), Very High Throughput-STF (VHT-STF), High Eficiency-STF (HE-STF), and Extremely High Throughput-STF (EHT-STF). Similarly, LTFs and SIGs are classified as L-LTF, HT-LTF, VHT-LTF, HE-LTF, L-SIG, HT-SIG, VHT-SIG, HE-SIG, and EHT-SIG. VHT-SIG is further classified into VHT-SIG-A1, VHT-SIG-A2, and VHT-SIG-B. Similarly, HE-SIG is classified into HE-SIG-A1 to HE-SIG-A4 and HE-SIG-B. In addition, assuming technical updates in the same standard, a Universal SIGNAL (U-SIG) field containing additional control information can be included.

[0025] Furthermore, the PHY header can include information for identifying the BSS that is the sender of the frame (hereinafter also referred to as BSS identification information). The information for identifying the BSS can be, for example, the SSID (Service Set IDentifier) ​​of the BSS or the MAC address of the access point device of the BSS. The information for identifying the BSS can also be a value unique to the BSS (for example, BSS Color) other than the SSID or MAC address. Information indicating the BSS Color can be included in the HE-SIG-A or U-SIG.

[0026] The PPDU is modulated according to the corresponding standard, for example, in the case of the IEEE 802.11n standard, it is modulated into an Orthogonal Frequency Division Multiplexing (OFDM) signal.

[0027] An MPDU consists of a MAC header containing information for signal processing at the MAC layer, a MAC Service Data Unit (MSDU) or frame body, which is the data unit processed at the MAC layer, and a Frame Check Sequence (FCS), which checks whether the frame is error-free (Figure 1). Multiple MSDUs can also be aggregated into an Aggregated MSDU (A-MSDU).

[0028] Frame types at the MAC layer are broadly classified into three: management frames, which manage the connection status between devices; control frames, which manage the communication status between devices; and data frames, which contain the actual transmitted data. Each of these is further classified into multiple subframe types. Control frames include acknowledgement (Ack or ACK) frames, block acknowledgement (BA or BlockAck) frames, request to send (RTS) frames, and clear to send (CTS) frames. BlockAck can acknowledge (notify completion of reception) multiple MPDUs. Management frames include beacon frames, probe request frames, probe response frames, authentication frames, association request frames, and association response frames. Data frames include data frames and polling (CF-poll) frames. Each device can recognize the frame type and subframe type of a received frame by reading the frame control field in the MAC header.

[0029] A beacon frame includes a field indicating the period (beacon interval) at which beacons are transmitted and the SSID. An access point device can periodically broadcast a beacon frame within a BSS, and a station device can recognize surrounding access point devices by receiving the beacon frame. The act of a station device recognizing an access point device based on a beacon frame broadcast by an access point device is called passive scanning. On the other hand, the act of a station device searching for an access point device by broadcasting a probe request frame within a BSS is called active scanning. An access point device can transmit a probe response frame in response to the probe request frame, and the content of the probe response frame is the same as the content of the beacon frame.

[0030] After recognizing an access point device, a station device performs a connection process with the access point device. The connection process is classified into an authentication procedure and an association procedure. The station device transmits an authentication request frame to the access point device with which it wishes to connect. Upon receiving the authentication request frame, the access point device transmits an authentication response frame to the station device, which includes a status code indicating whether the station device has been authenticated. By reading the status code included in the authentication response frame, the station device can determine whether its own authentication request has been approved by the access point device. Note that the access point device and station device can exchange authentication request frames and authentication response frames (both of which are collectively referred to as authentication frames) multiple times.

[0031] Following the authentication procedure, the station device transmits a connection request frame to the access point device to initiate a connection procedure. Upon receiving the connection request frame, the access point device determines whether to permit the station device to connect and transmits a connection response frame to notify the result. The connection response frame contains a status code indicating whether the connection process is successful, as well as an association ID (AID) for identifying the station device. The access point device can manage multiple station devices by assigning different AIDs to each station device for which it has issued a connection permission.

[0032] After the connection process is completed, the access point device and station device perform actual data transmission. The IEEE 802.11 system defines the Distributed Coordination Function (DCF), Point Coordination Function (PCF), and their extended Hybrid Coordination Function (HCF) as media access methods. Specific implementation methods for HCF include Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA).

[0033] First, an example of the operation when an access point device transmits a signal to a station device based on DCF will be described. In DCF, the access point device and the station device perform carrier sense (CS) to check the usage status of wireless channels around the device before communication. For example, if an access point device or a station device that is about to transmit a frame receives a signal with a received power higher than a predetermined clear channel assessment level (CCA level) on the wireless channel during the carrier sense period performed prior to transmission, the access point device or the station device postpones the transmission of the frame on the wireless channel. Hereinafter, a state in which a signal with a received power equal to or higher than the CCA level is detected on the wireless channel is referred to as a busy state, and a state in which a signal with a received power equal to or higher than the CCA level is not detected is referred to as an idle state. This CS performed by each device based on the power level of the signal actually received is referred to as physical carrier sense (physical CS). The CCA level is also referred to as a carrier sense level (CS level) or a CCA threshold (CCAT). When the access point device and station device detect a signal with a reception power equal to or higher than the CCA level, they begin to demodulate at least the PHY layer signal.

[0034] An access point device performs carrier sensing during an interframe space (IFS) that is set according to the type of frame to be transmitted, and determines whether the wireless channel is busy or idle. The period during which the access point device performs carrier sensing varies depending on the frame type and subframe type of the frame the access point device is about to transmit. The IEEE 802.11 system defines several IFSs with different durations, including the short interframe space (SIFS) used for frames assigned the highest priority, the polling interframe space (PIFS: PCF IFS) used for frames with relatively high priority, and the distributed arbitration interframe space (DIFS: DCF IFS) used for frames with low priority. When transmitting data frames using DCF, the access point device uses DIFS.

[0035] After waiting for the DIFS period, the access point device further waits for a random backoff time to prevent frame collisions. In the IEEE 802.11 system, a random backoff time based on a contention window (CW) is used. CSMA / CA assumes that a frame transmitted by a transmitting station is received by a receiving station without interference from other transmitting stations. Therefore, if multiple transmitting stations transmit frames at the same time, the frames may collide with each other, potentially preventing the receiving station from receiving the frame correctly. Therefore, frame collisions are avoided by having each transmitting station wait for a randomly set time before starting transmission. When the access point device determines through carrier sense that the wireless channel is idle, it starts counting down a backoff counter set based on the CW. Only when the backoff counter reaches 0 does it acquire the right to transmit and transmit a frame to the station device. If the access point device determines through carrier sense that the wireless channel is busy during the backoff counter countdown, it stops counting down the backoff counter. Then, when the wireless channel becomes idle again, the access point device waits for the same period as the previous IFS, and then resumes counting down the remaining part of the previous backoff counter.

[0036] The receiving station, a station device, receives the frame, reads the PHY header of the frame, and demodulates the received frame. The station device can then determine whether the frame is addressed to itself by reading the MAC header of the demodulated signal. The station device can also determine the destination of the frame based on information contained in the PHY header (e.g., a group identification number (GID: Group Identifier, Group ID) contained in VHT-SIG-A).

[0037] If a station device determines that a received frame is addressed to itself and demodulates the frame without error, it must transmit an Ack frame to the access point device, which is the transmitting station, indicating that the frame was received correctly. The Ack frame is one of the highest-priority frames that is transmitted after waiting only an SIFS period (without a random backoff time). The access point device terminates a series of communications upon receiving an Ack frame from the station device. Note that if the station device does not receive a frame correctly, it will not transmit an Ack frame. Therefore, if the access point device does not receive an Ack frame from the receiving station (station device) within a certain period (SIFS + Ack frame length) after transmitting a frame, it determines that the communication has failed and terminates the communication. In this way, the end of a single communication (also called a burst) in an IEEE 802.11 system is always determined by whether or not an Ack frame is received, except in special cases such as when transmitting a beacon frame or other notification signal, or when fragmentation is used to divide the transmitted data.

[0038] When a station device determines that a received frame is not addressed to itself, it sets a network allocation vector (NAV) based on the length of the frame contained in the PHY header or the like. The station device does not attempt transmission during the period set in the NAV. In other words, the station device performs the same operation as when it determines that the wireless channel is busy based on physical CS during the period set in the NAV, so communication control using NAV is also called virtual carrier sense (virtual CS). In addition to being set based on information contained in the PHY header, the NAV is also set by RTS frames and CTS frames introduced to solve the hidden terminal problem.

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

[0040] The communication period by PCF includes a contention-free period (CFP) and a contention period (CP). During the CP, communication is performed based on the DCF described above, and the PC controls the transmission right during the CFP. The access point device, which is the PC, broadcasts a beacon frame including information such as the CFP duration (CFP Max duration) within the BSS prior to PCF communication. Note that the beacon frame broadcast at the start of PCF transmission uses PIFS and is transmitted without waiting for a CW. The station device that receives the beacon frame sets the CFP Max duration included in the beacon frame in its NAV. Thereafter, until the period set in the NAV elapses or a signal announcing the end of the CFP within the BSS (e.g., a data frame including CF-end) is received, the station device can acquire the transmission right only when it receives a signal signaling acquisition of the transmission right for itself (e.g., a data frame including CF-poll) from the PC. During the CFP period, no packet collisions occur within the same BSS, so each station device does not take the random backoff time used in DCF.

[0041] A wireless communication device has either or both of a function for transmitting and receiving a PPDU. Fig. 2 is a diagram showing an example of the structure of a PPDU transmitted by a wireless communication device. A PPDU conforming to the IEEE 802.11a / g standard is configured to include an L-STF, an L-LTF, an L-SIG, and a Data frame (MAC frame, payload, data section, data, information bits, etc.). A PPDU conforming to the IEEE 802.11n standard is configured to include an L-STF, an L-LTF, an L-SIG, an HT-SIG, an HT-STF, an HT-LTF, and a Data frame. A PPDU conforming to the IEEE 802.11ac standard is configured to include some or all of an L-STF, an L-LTF, an L-SIG, a VHT-SIG-A, a VHT-STF, a VHT-LTF, a VHT-SIG-B, and a Data frame. The PPDU conforming to the IEEE 802.11ax standard is configured to include some or all of the following: L-STF, L-LTF, L-SIG, RL-SIG (which is a time-repeated L-SIG), HE-SIG-A, HE-STF, HE-LTF, HE-SIG-B, and Data frames.The PPDU considered for the IEEE 802.11be standard is configured to include some or all of the following: L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, HET-LTF, and Data frames.

[0042] The L-STF, L-LTF, and L-SIG enclosed by dotted lines in Figure 2 are structures commonly used in the IEEE 802.11 standard (hereinafter, L-STF, L-LTF, and L-SIG are also collectively referred to as the L-header). For example, a wireless communication device conforming to the IEEE 802.11a / g standard can properly receive an L-header in a PPDU conforming to the IEEE 802.11n / ac / ax / be standard. A wireless communication device conforming to the IEEE 802.11a / g standard can receive a PPDU conforming to the IEEE 802.11n / ac / ax / be standard, treating it as a PPDU conforming to the IEEE 802.11a / g standard.

[0043] However, wireless communication devices that comply with the IEEE 802.11a / g standard cannot demodulate PPDUs that comply with the IEEE 802.11n / ac / ax / be standards that follow the L-header, and therefore cannot demodulate information related to the transmitter address (TA), receiver address (RA), duration / ID field, etc.

[0044] IEEE 802.11 specifies a method for inserting duration information into L-SIG as a method for wireless communication devices conforming to the IEEE 802.11a / g standard to appropriately set NAV (or perform reception for a predetermined period of time). Information about the transmission rate in the L-SIG (RATE field, L-RATE field, L-RATE, L_DATARATE, L_DATARATE field) and information about the transmission duration (LENGTH field, L-LENGTH field, L-LENGTH) are used by wireless communication devices conforming to the IEEE 802.11a / g standard to appropriately set NAV.

[0045] The wireless communication device can transmit the L-SIG multiple times (L-SIG Repetition). In this case, the receiving wireless communication device can improve the demodulation accuracy of the L-SIG by receiving the L-SIG transmitted multiple times using Maximal Ratio Combining (MRC), for example. Furthermore, when the wireless communication device has successfully received the L-SIG using MRC, it can interpret the PPDU including the L-SIG as a PPDU that complies with the IEEE 802.11ax or IEEE 802.11be standard.

[0046] Even while receiving a PPDU, the wireless communication device can receive a part of a PPDU other than the PPDU (for example, a preamble, L-STF, L-LTF, PHY header, etc., as defined by IEEE 802.11) (also referred to as a dual reception operation). When the wireless communication device detects a part of a PPDU other than the PPDU during the PPDU reception operation, the wireless communication device can update some or all of the information related to the destination address, source address, PPDU, or Data period.

[0047] Ack and BA can also be called responses (response frames). In addition, probe responses, authentication responses, and connection responses can also be called responses.

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

[0049] 4 is a diagram showing an example of a wireless communication system according to this embodiment. Wireless communication system 4003-1 includes wireless communication device 4001-1 and wireless communication devices 4002-1 to 4002-3. Wireless communication device 4001-1 is also referred to as access point device 4001-1, and wireless communication devices 4002-1 to 4002-3 are also referred to as station devices 4002-1 to 3. Wireless communication devices 4002-1 to 4002-3 (station devices 4002-1 to 4002-3) are also referred to as wireless communication device 4002A (station device 4002A) as devices connected to wireless communication device 4001-1. Wireless communication device 4001-1 and wireless communication device 4002A are wirelessly connected, and are capable of transmitting and receiving PPDUs to and from each other. The wireless communication system according to this embodiment may also include wireless communication system 4003-2 in addition to wireless communication system 4003-1. Wireless communication system 4003-2 includes wireless communication device 4001-2 and wireless communication devices 4002-4 to 4002-6. Wireless communication device 4001-2 is also referred to as access point device 4001-2, and wireless communication devices 4002-4 to 4002-6 are also referred to as station devices 4002-4 to 4002-6. Wireless communication devices 4002-4 to 4002-6 (station devices 4002-4 to 4002-6) are also referred to as wireless communication device 4002B (station device 4002B) as devices connected to wireless communication device 4001-2. Furthermore, wireless communication device 4001-1 and wireless communication device 4001-2 (access point devices 4001-1, 4001-6) will also be referred to as wireless communication device 4001 (access point device 4001) when described without specifying each individual device, and wireless communication devices 4002-1 to 4002-6 (station devices 4002-1 to 4002-6) will also be referred to as wireless communication device 4002 (station device 4002) when described without specifying each individual device. Wireless communication system 4003-1 and wireless communication system 4003-2 form different BSSs, but this does not necessarily mean that the ESSs (Extended Service Sets) representing service sets forming LANs (Local Area Networks) are different.In other words, wireless communication devices belonging to the same ESS can be regarded as belonging to the same network from a higher layer. Also, BSSs are connected via a DS (Distribution System) to form an ESS. Note that each of the wireless communication systems 4003-1 and 4003-2 can further include multiple wireless communication devices.

[0050] 5 is a diagram showing an example of the configuration of station device 4002. Station device 4002 includes a radio control unit (radio control step) 5001, a timer unit (timer step) 5002, a radio communication unit (radio communication step) 5003, and an antenna unit 5004. Furthermore, radio communication unit 5003 includes a physical layer frame generation unit (physical layer frame generation step) 5003a, a radio transmission unit (radio transmission step) 5003b, a radio reception unit (radio reception step) 5003c, a received power measurement unit (received power measurement step) 5003d, a channel estimation unit (channel estimation step) 5003e, and a signal demodulation unit (signal demodulation step) 5003f.

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

[0052] Timer unit 5002 includes one or more timers and manages the timers related to the sounding process. Details of timer unit 5002 will be described later. Note that, in the example of Fig. 5, timer unit 5002 is shown as being included in wireless control unit 5001, but is not limited to this configuration, and may be configured to be provided outside wireless control unit 5001 and to operate under control from wireless control unit 5001.

[0053] The physical layer frame generation unit 5003a has a function of generating a physical layer frame (PPDU). The physical layer frame generation unit 5003a performs error correction coding, modulation, beamforming processing (precoding processing), etc. on the MAC layer frame sent from the wireless control unit 5001. The beamforming processing may be realized by multiplying the modulated signal by a beamforming matrix (beamforming filter) notified by the wireless control unit 5001. The physical layer frame generation unit 5003a outputs the generated physical layer frame to the wireless transmission unit 5003b.

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

[0055] The radio receiving unit 5003c has a function of converting a radio signal received via the antenna unit 5004 into a baseband signal and generating a physical layer signal (for example, a physical layer frame). The processing performed by the radio receiving unit 5003c includes frequency conversion processing from a radio frequency to a baseband frequency, filtering, analog-to-digital conversion, etc. The physical layer signal, which is the received signal converted into a digital signal by the radio receiving unit 5003c, is input to the received power measuring unit 5003b, the channel estimating unit 5003e, and the signal demodulating unit 5003f.

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

[0057] The channel estimation unit 5003e estimates the channel state through which the physical layer frame has propagated, based on a received signal of an LTF (L-LTF, HT-LTF, VHT-LTF, HE-LTF, etc.) included in the physical layer frame received by the wireless receiving unit 5003c. The channel estimation unit 5003e can notify the signal demodulation unit 5003f and the wireless control unit 5001 of the channel estimation result.

[0058] The signal demodulation unit 5003f performs channel equalization, demodulation, error correction decoding, etc. on the physical layer frame received by the wireless receiving unit 5003c, and acquires information such as the PHY header and MAC layer frame. The channel equalization process can use the channel estimation results of the channel estimator 5003e, etc. The signal demodulation unit 5003f outputs the acquired PHY header and MAC layer frame to the wireless control unit 5001.

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

[0060] When there is control information, data, or the like to be transmitted, the wireless control unit 5001 can start a backoff procedure using the wireless channel state determination information. The wireless control unit 5001 generates a backoff counter based on the CW and has a countdown function for the backoff counter. For example, when the wireless channel state determination information indicates an idle state, the wireless control unit 5001 can countdown the backoff counter, and when the wireless channel state determination information indicates a busy state, the wireless control unit 5001 can stop the countdown. Furthermore, the wireless control unit 5001 makes a transmission decision using either the wireless channel state determination information or the backoff counter value, or both. For example, when the wireless channel state determination information indicates an idle state and the backoff counter value is 0, the wireless control unit 5001 can notify the wireless communication unit 5003 of transmission decision information. Furthermore, when the wireless resource state determination information indicates an idle state, the wireless control unit 5001 can notify the wireless communication unit 5003 of transmission decision information.

[0061] FIG. 6 is a diagram showing an example of the configuration of an access point device 4001. The access point device 4001 includes a wireless control unit (wireless control step) 6001, a wireless communication unit (wireless communication step) 5003, and an antenna unit 5004. Furthermore, the wireless communication unit 5003 includes a physical layer frame generation unit (physical layer frame generation step) 5003a, a wireless transmission unit (wireless transmission step) 5003b, a wireless reception unit (wireless reception step) 5003c, a received power measurement unit (received power measurement step) 5003d, a channel estimation unit (channel estimation step) 5003e, and a signal demodulation unit (signal demodulation step) 5003f. The access point device 4001 in FIG. 6 is basically configured similarly to the station device 4002 in FIG. 5. Therefore, the following description will focus on the differences between the two, and will omit a description of similar parts. Furthermore, parts corresponding to those in the station device in FIG. 5 will be described using the same reference numerals.

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

[0063] The physical layer frame generation unit 5003a has a function of generating a physical layer frame (PPDU). The physical layer frame generation unit 5003a performs error correction coding, modulation, beamforming processing (precoding processing), etc. on the MAC layer frame sent from the wireless control unit 6001. The beamforming processing may be realized by multiplying the modulated signal by a beamforming matrix (beamforming filter) notified by the wireless control unit 6001. The physical layer frame generation unit 5003a outputs the generated physical layer frame to the wireless transmission unit 5003b.

[0064] The received power measurement unit 5003d measures the received power of the received signal input from the wireless receiving unit 5003c. The received power measurement unit 5003d can measure the received power of radio waves received on the frequency channel to be measured, the received power of the LTF (L-LTF, HT-LTF, VHT-LTF, HE-LTF, etc.) of the received physical layer frame, etc. The received power measurement unit 5003d can notify the wireless control unit 6001 of the measurement result of the received power.

[0065] The channel estimation unit 5003e estimates the channel state through which the physical layer frame has propagated, based on the received signal of the LTF included in the physical layer frame received by the wireless receiving unit 5003c. The channel estimation unit 5003e can notify the signal demodulation unit 5003f and the wireless control unit 6001 of the channel estimation result.

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

[0067] When there is control information, data, a beacon, or the like to be transmitted, the wireless control unit 6001 can start a backoff procedure using the wireless channel state determination information. The wireless control unit 6001 generates a backoff counter based on the CW and has a countdown function for the backoff counter. For example, when the wireless channel state determination information indicates an idle state, the wireless control unit 6001 can countdown the backoff counter, and when the wireless channel state determination information indicates a busy state, the wireless control unit 6001 can stop the countdown. Furthermore, the wireless control unit 6001 makes a transmission decision using either the wireless channel state determination information or the backoff counter value, or both. For example, when the wireless channel state determination information indicates an idle state and the backoff counter value is 0, the wireless control unit 6001 can notify the wireless communication unit 5003 of transmission decision information. Furthermore, when the wireless resource state determination information indicates an idle state, the wireless control unit 6001 can notify the wireless communication unit 5003 of transmission decision information.

[0068] This embodiment will be described as an example of an embodiment with two access point devices (AP1 7001, AP2 7002) and one station device (STA 7003) as shown in FIG. 7 . The number of access point devices is not limited to two and may be three or more, and the number of station devices may be two or more. It is assumed that BSS1 (7004) managed by access point device 1 (AP1 7001) and BSS2 (7005) managed by access point device 2 (AP2 7002) partially overlap. It is also assumed that BSS1 (7004) and BSS2 (7005) use a certain frequency band, for example, the 5 GHz band, and use the same primary channel. It is assumed that information can be exchanged between access point device 1 (7001) and access point device 2 (7002) using a secure communication means other than the communication means using the frequency band in which the primary channel is set, such as a wired communication means or a wireless communication means using another frequency. Station device (7003) is located at a position where BSS1 (7004) and BSS2 (7005) overlap, and station device (7003) is capable of communicating with both access point device 1 (7001) and access point device 2 (7002).

[0069] The access point device 1 (7001) and the access point device 2 (7002) operate in cooperation with each other. Examples of cooperation include using a common ESSID, sharing indicators used for QoS, and sharing information related to power control. Next, an example will be described in which the access point device 1 (7001) and the access point device 2 (7002) cooperate and respond to an inquiry from a station device on their behalf when one of the access point devices is in a power saving state. The power saving state of the access point device is not particularly limited, and various methods of reducing the power consumption of the access point device may be used to enter the power saving state. For example, the power saving state may be entered by stopping the operation of the wireless transmission unit (5003b) responsible for the primary channel to disable immediate transmission, stopping the operation of the wireless reception unit (5003c) responsible for the primary channel to disable reception, or stopping the operation of the signal demodulation unit (5003f) to disable demodulation of received signals. The method of transitioning to the power save state is not particularly limited, and may be, for example, a method of scheduling the transition to the power save state and the wake-up time in advance, or a method of transitioning to the power save state and waking up irregularly.Examples of conditions for transitioning to the power save state irregularly include a state in which the station device using the primary channel is not connected to the access point device, or a state in which data to be transmitted using the primary channel is not held.

[0070] FIG. 8A shows an example of a flow for performing a proxy response. Initially, assume that access point device 1 (AP1) is in a power-saving state. In this state, a station device (STA) transmits a probe request 8001 using a primary channel likely used by access point device 1. If access point device 1 were awake, it would transmit a probe response 8002. However, since access point device 1 is in a power-saving state, the probe response 8002 is not transmitted. Access point device 2 (AP2), associated with access point device 1, confirms that the probe response 8002 has not been transmitted from access point device 1, and then transmits a proxy probe response 8003 to the station device on behalf of access point device 1. Then, access point device 2 may transmit a message 8004 to access point device 1 using a means other than the wireless communication means used on the primary channel, such as a wired network, that includes at least one of information indicating that the proxy probe response 8003 has been transmitted or information indicating a wake-up request. Upon receiving the message 8004, access point device 1 transitions to an awake state. The access point device 1 that has transitioned to the awake state transmits an association response 8006 in response to the association request 8005 transmitted by the station device, and transitions to the connection procedure that follows this operation. The connection procedure is in accordance with the IEEE 802.11 specifications.

[0071] Next, using FIG. 8(b), we will explain the flow when a proxy probe response is not required and the flow when a proxy probe response is requested depending on the power saving state of an access point device through cooperation between access point devices. Initially, the access point device 1 is in the power saving state and then transitions to the awake state. While the access point device 1 is in the awake state, it receives a probe request 8011 from the station device. Upon receiving the probe request 8011, the awake access point device 1 transmits a probe response 8012 to the station device. Upon confirming that the access point device 1 has transmitted the probe response 8012, the access point device 2 cancels transmission of the proxy probe response 8013. While awake, the access point device 1 may transmit a message 8014 to the access point device 2 indicating that it is currently awake. Upon receiving the message 8014, the access point device 2 may determine that the access point device 1 does not require a proxy probe response and may stop transmitting any further proxy probe responses.

[0072] Thereafter, the access point device 1 transitions to the power saving state. Prior to transitioning to the power saving state, the access point device 1 transmits a message 8015 to the access point device 2 indicating transition to the power saving state. This message 8015 indicating transition to the power saving state signifies permission (or enabling or permitting) of a proxy probe response. In this embodiment, this message 8015 indicating transition to the power saving state is transmitted from the access point device 1 to the access point device 2, but it may also be transmitted from another access point device to the access point device 2. The access point device 1 may include in this message 8015 some or all of the information to be included in the proxy probe response. For example, it may include all or part of the capability information of the access point device 1, the BSSID, the ESSID, and at least some of the MAC address of the currently connected station device. The access point device 1 that transmitted the message 8015 transitions to the power saving state. After the access point device 1 transitions to the power saving state, even if the station device transmits a probe request 8016, the access point device 1 does not transmit a probe response 8017 because it is in the power saving state. The access point device 2 confirms that the access point device 1 does not transmit a probe response 8017, and transmits a proxy probe response 8018 to the station device. At this time, the proxy probe response 8018 may include all or part of the information included in the message 8015.

[0073] Next, an example of a procedure in which the access point device 2 transmits a proxy probe response after confirming that the access point device 1 has not transmitted a probe response will be described with reference to FIG. 9 . Here, as an example, a case will be described in which the access point device 2 changes the IFS (Inter Frame Space) between transmitting a normal probe response and transmitting a proxy probe response. An example of a normal probe response is a probe response that includes information indicating that the address field of the MAC frame transmitting the probe response frame, for example, the source address field, does not include the MAC address of the access point device 1 that is the proxy response target, but includes the MAC address of the access point device 2 in the source address field. An example of a proxy probe response is a probe response that includes information indicating the MAC address of the access point device 1 that is the proxy response target, for example, the source address field, of the MAC frame transmitting the probe response frame. First, a station device transmits a probe request 9001 to the access point device 2. Upon receiving the probe request 9001, the access point device 2 transmits a normal probe response 9002 using the DCF procedure. The IFS1 used at this time may be a DIFS for DCF. After the wireless medium becomes clear, the station device waits for DIFS (from t1 to t2), then performs random backoff (9003), and then transmits a normal probe response (9002). Next, the station device transmits a probe request (9004) to the access point device 1. The access point device 1 does not transmit a probe response because it is in a power saving state. After receiving the probe request (9004), the access point device 2 waits for IFS2 (from t3 to t4), which is different from IFS1, and then performs random backoff (9006). For example, IFS2 may be set to a time longer than IFS1, i.e., a time longer than DIFS. The access point device 2 continues to monitor whether a probe response is transmitted from the access point device 1 from the start time t3 of IFS2 to the end time t5 of the random backoff (9006).After confirming that no probe response is sent from the access point device 1 until t5, the access point device 2 sends a proxy probe response 9005 to the station device. By changing IFS1 and IFS2 in this way, in other words, by setting IFS2 longer than IFS1, it becomes easier to determine whether the access point device 1 is in a state where it can send a normal probe request, and whether it needs to send a proxy probe response.

[0074] Next, we will show an example of the procedure for sending a proxy probe response to a probe request addressed to multiple devices, especially when the SSID is a wildcard SSID. The following explanation uses a wildcard SSID as an example, but a similar procedure can be used when one SSID designates multiple access point devices. A wildcard SSID is an SSID that specifies all SSIDs by specifying a length of 0 as the SSID value. An example of this procedure is shown in Figure 10(a). Assume that access point device 1 is in power saving mode. The station device transmits a probe request (10001) specifying a wildcard SSID to designate all access points. Access point device 1, which is in power saving mode, does not transmit a probe response (10002) corresponding to the probe request (10001). Access point device 2 receives the probe request (10001) and then transmits a probe response (10003) linked to the SSID managed by access point device 2 using the DCF procedure. The MAC address used when transmitting this probe response (10003) is the MAC address of access point device 2. The access point device 2 then confirms that the access point device 1 has not transmitted a probe response (10002), and transmits a proxy probe response (10004) using the DCF procedure. The IFS used when transmitting this proxy probe response (10004) may not be the shortest IFS (SIFS), but may be set to an IFS longer than SIFS, such as DIFS, so that the probe response can be transmitted when the access point device 1 is awake. The transmission order of the probe response (10003) and the proxy probe response (10004) may also be reversed. This proxy probe response is transmitted using the SSID used by the access point device 1, and the MAC address included in the proxy probe response (10004) is the MAC address of the access point device 1. The IFS used for the probe response (10003) and the IFS used when transmitting the proxy probe response (10004) may be different.The access point device 2 that transmitted the proxy probe response (10004) transmits information (10005) to the access point device 1, via a wired connection or other means, indicating that the proxy probe response has been transmitted. Upon receiving this information (10005) indicating that the proxy probe response has been transmitted, the access point device 1 transitions to an awake state. After transitioning to the awake state, the access point device 1 becomes able to send an association response 10007 in response to an association request 10006 transmitted by the station device. After transitioning to the awake state, the access point device 1 may transition again to a sleep state under certain conditions, such as if it has not received an association request for a predetermined period of time.

[0075] Next, a modified example will be described with reference to FIG. 10(b). In response to a probe request addressed to multiple destinations, instead of sending a proxy probe response, a multiple BSSID field or a similar format is used, and a proxy response field containing information to be sent in the proxy probe response is included in the probe response. The access point device 1 is assumed to be in a power-saving mode. This modified example also shows an example of a procedure for sending a proxy probe response to a probe request addressed to multiple destinations, particularly when the SSID is a wildcard SSID. The station device sends a probe request (10101) specifying a wildcard SSID to designate all access points. The access point device 1 in a power-saving mode does not send a probe response (10102) corresponding to the probe request (10101). The access point device 2 receives the probe request (10101) and then sends a probe response (10103) linked to the SSID managed by the access point device 2 using the DCF procedure. The MAC address used when sending this probe response (10103) is the MAC address of the access point device 2. The information element included in this probe response (10103) may include information indicating the SSID of the access point device 1 responding on behalf of the access point device 1, and information indicating part or all of the capability information of the access point device 1. As an example, a Multiple BSSID element may be used, and an SSID element may be included as a subelement of the Multiple BSSID element, and the SSID of the access point device 1 may be included in this SSID element. Alternatively, a Multiple BSSID-Index element may be included as a subelement of the Multiple BSSID element, and the BSSID (MAC address) of the access point device 1 may be included in this Multiple BSSID-Index element. Furthermore, a new information element may be defined that includes information indicating the SSID of the access point device 1, and information indicating part or all of the capability information of the access point device 1.The access point device 2 that transmitted the probe response (10103) transmits information (10104) indicating that it has transmitted the probe response (10103) including information about the access point device 1 to the access point device 1 by means of a wired connection or the like. Upon receiving the information (10104) indicating that it has transmitted the probe response (10103), the access point device 1 transitions to an awake state. After transitioning to the awake state, the access point device 1 becomes able to send back an association response 10106 in response to an association request 10105 transmitted by the station device. After transitioning to the awake state, the access point device 1 may transition again to a sleep state under certain conditions, such as when it has not received an association request for a predetermined period of time.

[0076] Next, a modified example in which a proxy beacon is transmitted instead of a proxy probe response will be described with reference to FIG. 11. Assume that there are access point devices 1 and 2, which can cooperate to transition to a power saving state. FIG. 11 illustrates an example in which access point device 1 transitions to a power saving state, while access point device 2 transmits a proxy beacon during that time. Access point device 1 is awake, and transmits beacons (11001-1, 11001-2) using the DCF procedure based on the beacon period set for access point device 1. Thereafter, at time t1, it transitions to the power saving state. After transitioning to the power saving state, access point device 1 stops transmitting beacons at the set beacon period interval (11001-3, 11001-4, 11001-5). The access point device 2 transmits beacons (11002-1, 11002-2, ..., 11002-5, 11002-6) in accordance with the DCF procedure based on the beacon period set in the access point device 2. The access point device 1 and the access point device 2 are linked, and the access point device 2 is aware of the possibility that the access point device 1 will transition to a power saving state. The access point device 2 is aware of the beacon period of the access point device 1 by receiving a beacon transmitted by the access point device 1, by being notified in advance via wireless communication, or by way of a wired connection between the access point device 1 and the access point device 2. The access point device 2 monitors the beacons transmitted by the access point device 1 while transmitting beacons (11002-1, 11002-2, ..., 11002-5, 11002-6). The access point device 2 monitors the beacons (11001-1, 11001-2) transmitted by the access point device 1, and detects that the beacon (11001-2) that the access point device 1 was scheduled to transmit using the beacon period of the access point device 1 was not transmitted, and transmits a proxy beacon (11003-3).The TXOP reserved for the beacon (11002-3) transmitted by the access point device 2 may be used to transmit this proxy beacon (11003-3). In FIG. 11, the access point device 2 uses the TXOP reserved for transmitting the beacon (11002-3) to transmit the proxy beacon (11003-3) immediately after transmitting the beacon (11002-3). The access point device 2 may use some or all of the MAC address, SSID, BSSID, and capability information included in the proxy beacon (11003-3) as information to be used by the access point device 1 when transmitting a beacon. Furthermore, some or all of the MAC address, SSID, BSSID, and capability information used by the access point device 2 when transmitting a proxy beacon may be those included in the beacon transmitted by the access point device 1, or may use values ​​based on information previously communicated from the access point device 1 to the access point device 2. Furthermore, an access point device other than the access point device 1 may notify the access point device 2 that the access point device 1 is in a sleep state.

[0077] While the access point device 1 is in the power saving state, the access point device 2 confirms that the access point device 1 is not transmitting beacons (11001-3, 11001-4, 11001-5) and transmits proxy beacons (11003-3, 11003-4, 11003-5). The station device receives the proxy beacon (11003-5) and transmits a probe request (11004) to the access point device 1. Since the access point device 1 is in the sleep state, it cannot respond to the probe request (11004) at this point. The access point device 2 confirms that the access point device 1 cannot respond to the probe request (11004) and transmits a message (11005) to the access point device 1 via another means, such as a wired connection, that includes all or part of the contents of the probe request (11004) transmitted from the station device to the access point device 1. Upon receiving the message (11005), the access point device 1 transitions from sleep mode to wake-up mode at time t2. After waking up, the access point device 1 transmits a probe response (11006) to the station device. After waking up, the access point device 1 also transmits beacons (11001-6).

[0078] As described above, when one of the access point devices transitions to a power saving state, one of the other access point devices performs a proxy transmission (proxy probe response transmission, proxy beacon transmission, etc.), thereby ensuring responsiveness within the wireless network. Furthermore, it becomes possible to increase the opportunities for one of the access point devices to transition to a power saving state, thereby reducing the power consumption of the entire wireless network. [2. Common to all embodiments]

[0079] The communication device according to the present invention can communicate in a frequency band (frequency spectrum) called an unlicensed band, which does not require permission to use from a country or region, but the usable frequency band is not limited to this. The communication device according to the present invention can also be effective in a frequency band called a white band (for example, a frequency band allocated for television broadcasting but unused in some regions) that is not actually used for the purpose of preventing interference between frequencies even though permission to use it for a specific service is granted by a country or region, or in a shared spectrum (shared frequency band) that is expected to be shared by multiple operators.

[0080] The program running on the wireless communication device according to the present invention is a program that controls a CPU and other components (a program that causes a computer to function) so as to realize the functions of the above-described embodiments of the present invention. Information handled by these devices is temporarily stored in RAM during processing, and then stored in various ROMs or HDDs, from which the CPU reads, modifies, and writes the information as needed. Recording media for storing the programs may include semiconductor media (e.g., ROMs, non-volatile memory cards, etc.), optical recording media (e.g., DVDs, MOs, MDs, CDs, BDs, etc.), and magnetic recording media (e.g., magnetic tapes, flexible disks, etc.). Executing a loaded program not only realizes the functions of the above-described embodiments, but may also realize the functions of the present invention by processing in cooperation with an operating system or other application programs based on instructions from the program.

[0081] Furthermore, when distributing the program on the market, the program can be stored and distributed on a portable recording medium, or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer also falls within the scope of the present invention. Furthermore, part or all of the communication device in the above-described embodiments may be realized as an LSI, which is typically an integrated circuit. Each functional block of the communication device may be individually formed into a chip, or part or all of the functional blocks may be integrated into a chip. When each functional block is formed into an integrated circuit, an integrated circuit control unit that controls them is added. It goes without saying that the present invention also includes cases where programs and setting information are downloaded from a server computer to implement at least part of the functions of the above-described embodiments.

[0082] Furthermore, the integrated circuit method is not limited to LSI, and may be realized by dedicated circuits or general-purpose processors. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, it may also be possible to use an integrated circuit based on that technology.

[0083] It should be noted that the present invention is not limited to the above-described embodiments. The wireless communication device of the present invention is not limited to application to mobile station devices, but can of course be applied to stationary or non-mobile electronic devices installed indoors or outdoors, such as AV equipment, kitchen equipment, cleaning / washing equipment, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0084] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included in the scope of the claims. [Industrial Applicability]

[0085] The present invention is suitable for use in a wireless communication device and a wireless communication method. [Explanation of symbols]

[0086] 3001 NDP Announcement Frame 3002 NDP Frame 3003 Compressed Beamforming / CQI Frame 4001-1, 4001-2 Wireless communication device (access point device) 4002-1~6 Wireless communication equipment (station equipment) 4003-1, 4003-2 Wireless communication systems 5001 Radio control unit 5002 Timer section 5003 Wireless Communication Department 5003a Physical layer frame generator 5003b Radio transmitter 5003c Wireless receiver 5003d Received power measurement unit 5003e Channel Estimation Unit 5003f signal demodulation unit 5004 Antenna part 6001 Radio control unit

Claims

1. a first access point device in communication with one or more station devices and one or more access point devices including a second access point device, An antenna unit; a wireless communication unit that transmits and receives wireless frames using the antenna unit; a wireless control unit that controls the wireless communication unit and performs a CSMA (Carrier Sense Multiple Access) operation using an IFS (Inter Frame Space) to control transmission; When the wireless communication unit receives a probe request from one of the station devices, a first operation of transmitting a probe response without including a MAC address of the second access point device; a first operation of transmitting a probe response including a MAC address of the second access point device; and a second operation of transmitting a probe response including a MAC address of the second access point device.

2. 2. The first access point device according to claim 1, 2. The first access point device according to claim 1, wherein the first operation and the second operation use different IFSs.

3. 2. The first access point device according to claim 1, The first access point device performs the second operation after receiving information indicating that the second operation is enabled from the second access point device.

4. 4. The first access point device according to claim 3, The information indicating that the second operation is enabled includes capability information of the second access point device.

5. 2. The first access point device according to claim 1, The first access point device, while performing a CSMA operation to transmit the probe response, stops transmitting the probe response if it receives a probe response including a MAC address of the first access point device.

6. 2. The first access point device according to claim 1, The first access point device is characterized in that when transmitting a probe response including the MAC address of the first access point device and then transmitting a probe response including the MAC address of the second access point device in the second operation, the IFS used between transmitting the probe response including the MAC address of the first access point device and transmitting the probe response including the MAC address of the second access point device is a predetermined IFS different from SIFS (Short Inter Frame Space).

7. 2. The first access point device according to claim 1, The first access point device is characterized in that it performs both the first operation and the second operation when the SSID included in the received probe request is a wild card SSID.

8. 2. The first access point device according to claim 1, The first access point device is characterized in that, when the SSID included in the received probe request is a wildcard SSID, the first operation is performed to send a probe response, and the probe response includes at least a multiple BSSID element including the MAC address of the second access point device.

9. a first access point device in communication with one or more station devices and one or more access point devices including a second access point device, An antenna unit; a wireless communication unit that transmits and receives wireless frames using the antenna unit; a wireless control unit that controls the wireless communication unit and performs a CSMA (Carrier Sense Multiple Access) operation using an IFS (Inter Frame Space) to control transmission; When the second access point device receives information indicating that the second access point device will transition to a power saving state from any one of the one or more access point devices, The wireless control unit a first operation of transmitting a beacon frame in the CSMA operation without including a MAC address of the second access point device; a second operation of transmitting a beacon frame including the MAC address of the second access point device in the CSMA operation;

10. 1. A wireless communication method for use in a first access point device communicating with one or more station devices and one or more access point devices, including a second access point device, comprising: It controls transmission by using IFS (Inter Frame Space) and CSMA (Carrier Sense Multiple Access) operation. Upon receiving a probe request from one of the station devices, a first operation of transmitting a probe response without including a MAC address of the second access point device; a second operation of transmitting a probe response including the MAC address of the second access point device;

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