Access point device, station device, and communication method

Abstract

Provided is an access point device for maintaining a first connection and a second connection, the access point device comprising a reception unit for receiving, in the first connection, a first frame including information associated with the second connection, and a transmission unit for determining whether or not to transmit a second frame using the first frame in the second connection.

Description

Access point device, station device, and communication method

[0001] The present invention relates to an access point device, a station device, and a communication method. This application claims priority to Japanese Patent Application No. 2020-113674, filed on July 1, 2020, the contents of which are incorporated herein by reference.

[0002] The Institute of Electrical and Electronics Engineers Inc. (IEEE) is currently working on the specification of IEEE 802.11ax, which will achieve even faster speeds than the IEEE 802.11 wireless LAN (Local Area Network) standard, and wireless LAN devices compliant with the draft specification have appeared on the market. Currently, standardization activities for IEEE 802.11be, the successor to IEEE 802.11ax, have begun. With the rapid spread of wireless LAN devices, the IEEE 802.11be standardization is also considering further improvements in throughput per user in environments where wireless LAN devices are densely deployed.

[0003] In a wireless LAN, frames can be transmitted using an unlicensed band, which allows wireless communication without requiring permission (license) from a country or region. Currently, the 2.4 GHz and 5 GHz bands are widely used unlicensed bands. While the 2.4 GHz band offers relatively wide coverage, it is subject to significant interference between communication devices and does not offer a wide communication bandwidth. On the other hand, the 5 GHz band offers a wide communication bandwidth but does not offer a wide coverage. Therefore, to realize various services and applications using a wireless LAN, it is necessary to appropriately switch the frequency band used. However, in conventional wireless LAN devices, switching the frequency band used for communication requires the current connection to be disconnected.

[0004] Therefore, in the IEEE 802.11be standardization, discussions are being held on multi-link operation (MLO), which enables a communication device to maintain multiple connections (links) (see Non-Patent Document 1). Multi-link operation allows a communication device to maintain multiple connections that use different wireless resources and communication-related settings. In other words, by using multi-link operation, a communication device can simultaneously maintain connections on different frequency bands, thereby enabling it to change the frequency band for transmitting frames without performing a reconnection operation.

[0005] IEEE 802.11-20 / 0115-04, Jan. 2020.

[0006] However, using multiple connections means that the target communication area becomes larger in area. Therefore, in a dense environment with a large number of communication devices, the influence of surrounding interference cannot be ignored, and communication efficiency in unlicensed bands cannot be improved simply by increasing the number of connections.

[0007] One aspect of the present invention has been made in consideration of the above problems, and its purpose is to disclose an access point device, a station device, and a communication method that improve communication efficiency by using multiple connections in a terminal-dense environment where a large number of communication devices exist.

[0008] In order to solve the above-mentioned problems, an access point apparatus, a station apparatus, and a communication method according to one aspect of the present invention are as follows.

[0009] (1) That is, an access point device according to one aspect of the present invention is an access point device that maintains a first connection and a second connection, and includes: a receiving unit that receives a first frame in the first connection, the first frame including information associated with the second connection; and a transmitting unit that uses the first frame to determine whether to transmit a second frame in the second connection.

[0010] (2) Also, an access point device according to one aspect of the present invention is described in (1) above, wherein the information associated with the second connection is information indicating the state of a NAV set for the second connection by a station device transmitting the first frame, and when the NAV is associated with a second basic service set (BSS) different from a first BSS managed by the access point device, the transmitter transmits the second frame to the station device transmitting the first frame based on the second connection, and receives a response frame for the second frame on the first connection.

[0011] (3) Also, an access point device according to one aspect of the present invention is described in (2) above, wherein the transmitting unit transmits a frame including information indicating a connection through which a station device transmitting the first frame transmits a response frame for the second frame.

[0012] (4) Furthermore, the access point device according to one aspect of the present invention is described in (1) above, wherein the transmitter transmits a frame that triggers transmission of the first frame.

[0013] (5) Furthermore, in the access point device according to one aspect of the present invention, as set forth in (4) above, the destination of the first frame is a plurality of station devices.

[0014] (6) Also, a station device according to one aspect of the present invention is a station device that maintains a first connection and a second connection, and includes a transmitter that transmits a first frame including information associated with the second connection over the first connection, and a receiver that receives a frame over the second connection after the transmitter has transmitted the first frame.

[0015] (7) Also, an access point device according to one aspect of the present invention is an access point device that maintains multiple connections, and includes: a receiving unit that performs carrier sensing on the multiple connections; and, when the wireless medium of at least one of the multiple connections is determined to be idle, a transmitting unit that transmits frames on the connection whose wireless medium is determined to be idle and on at least one connection included in the multiple connections that is different from the connection whose wireless medium is determined to be idle, and the receiving unit receives a response frame for a frame transmitted on the at least one connection different from the connection whose wireless medium is determined to be idle on the connection whose wireless medium is determined to be idle.

[0016] (8) Also, an access point device according to one aspect of the present invention is described in (7) above, wherein the transmitting unit includes, in a frame transmitted in at least one connection other than the connection in which the wireless medium is determined to be idle, information indicating a connection in the plurality of connections through which a response frame to a frame transmitted in at least one connection other than the connection in which the wireless medium is determined to be idle is transmitted.

[0017] (9) Also, a communication method according to one aspect of the present invention is a communication method for an access point device that maintains a first connection and a second connection, comprising: a step of receiving a first frame based on the first connection, the first frame including information associated with the second connection; and a step of determining, based on the first frame, whether to transmit a second frame based on the second connection.

[0018] According to one aspect of the present invention, in a terminal-dense environment where a large number of communication devices exist, communication efficiency can be improved by using multiple connections, thereby contributing to improving user throughput of wireless LAN devices.

[0019] FIG. 1 is a diagram showing an example of a frame configuration according to an aspect of the present invention. FIG. 1 is a diagram showing an example of a frame configuration according to an aspect of the present invention. FIG. 2 is a diagram showing an example of communication according to an aspect of the present invention. FIG. 3 is a schematic diagram showing an example of division of a wireless medium according to an aspect of the present invention. FIG. 4 is a diagram showing an example of a configuration of a communication system according to an aspect of the present invention. FIG. 5 is a block diagram showing an example of a configuration of a wireless communication device according to an aspect of the present invention. FIG. 6 is a block diagram showing an example of a configuration of a wireless communication device according to an aspect of the present invention. FIG. 7 is a schematic diagram showing an example of an encoding method according to an aspect of the present invention. FIG. 8 is a diagram showing an example of communication according to an aspect of the present invention. FIG. 9 is a diagram showing an example of communication according to an aspect of the present invention. FIG. 10 is a diagram showing an example of communication according to an aspect of the present invention.

[0020] The communication system according to this embodiment includes a wireless transmitting device (access point device, base station device) and multiple wireless receiving devices (station devices, terminal devices). A network including the base station device and the terminal devices is called a basic service set (BSS, management range). A station device according to this embodiment can have the functions of an access point device. Similarly, an access point device according to this embodiment can have the functions of a station device. Therefore, hereinafter, when simply referring to a communication device, the communication device can refer to both a station device and an access point device.

[0021] The base station device and terminal devices within the BSS communicate based on CSMA / CA (Carrier sense multiple access with collision avoidance). This embodiment focuses on infrastructure mode, in which a base station device communicates with multiple terminal devices, but the method of this embodiment can also be implemented in ad hoc mode, in which terminal devices communicate directly with each other. In ad hoc mode, terminal devices form a BSS in place of a base station device. A BSS in ad hoc mode is also referred to as an IBSS (Independent Basic Service Set). Hereinafter, a terminal device forming an IBSS in ad hoc mode can also be considered a base station device.

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

[0023] The PHY layer transmission frame is called a physical protocol data unit (PPDU, PHY layer frame). A PPDU consists of a physical layer header (PHY header) containing header information for signal processing at the physical layer, and a physical service data unit (PSDU, PHY layer frame), which is a data unit processed at the physical layer. A PSDU can be composed of an aggregated MPDU (A-MPDU), which aggregates multiple MAC protocol data units (MPDUs), which serve as retransmission units in wireless sections.

[0024] 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.

[0025] 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 Legacy-STF (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 in the same standard, a Universal SIGNAL (U-SIG) field containing additional control information can be included.

[0026] The SIG may include information for demodulating the received frame, such as information indicating the modulation method and coding rate (MCS), the number of spatial data multiplexing (number of layers), the number of spatially multiplexed users, information indicating whether space-time coding is used (e.g., information indicating whether space-time coding transmit diversity is used), information indicating the destination of the frame, and information associated with the frame length of the frame (TXOP, etc.).

[0027] Furthermore, the PHY header may include information for identifying the BSS that is the sender of the transmission frame (hereinafter also referred to as BSS identification information). The information for identifying the BSS may be, for example, the SSID (Service Set Identifier) ​​of the BSS or the MAC address of the base station device of the BSS. The information for identifying the BSS may also be a value unique to the BSS (for example, a BSS Color) other than the SSID or MAC address.

[0028] Since the PHY header including the SIG contains information necessary for data demodulation, it is desirable that the PHY header be resistant to wireless errors. It is also desirable that the PHY header be correctly received by wireless LAN devices other than the destination wireless LAN device. Considering the existence of wireless LAN devices in poor communication environments, it is desirable that a highly redundant modulation method and coding rate be set for the PHY header, particularly the SIG. For example, a communication device can set a modulation method with a small modulation multi-level number, such as BPSK modulation, and a low coding rate for the PHY header.

[0029] An MPDU consists of a MAC header, which contains header information for signal processing at the MAC layer, a MAC service data unit (MSDU) or frame body, which is a data unit processed at the MAC layer, and a frame check sequence (FCS), which checks whether the frame is error-free. Multiple MSDUs can also be aggregated as an Aggregated MSDU (A-MSDU).

[0030] Frame types for MAC layer transmission are broadly classified into three types: 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 transmission data. Each type 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, and association response frames. Data frames include data frames and polling (CF-poll) frames. Each device can determine the frame type and subframe type of a received frame by reading the contents of the frame control field in the MAC header.

[0031] The Ack may include a Block Ack, which can be used to notify completion of reception of multiple MPDUs.

[0032] A beacon frame includes a field that describes the period (beacon interval) at which the beacon is transmitted and the SSID. A base station device can periodically broadcast a beacon frame within a BSS, and a terminal device can identify base station devices around the terminal device by receiving the beacon frame. The process by which a terminal device identifies a base station device based on a beacon frame broadcast by a base station device is called passive scanning. On the other hand, the process by which a terminal device searches for a base station device by broadcasting a probe request frame within a BSS is called active scanning. The base station device can transmit a probe response frame in response to the probe request frame, and the contents of the probe response frame are the same as those of a beacon frame.

[0033] After recognizing a base station device, the terminal device performs a connection process with the base station device. The connection process is classified into an authentication procedure and an association procedure. The terminal device transmits an authentication frame (authentication request) to the base station device with which it wishes to connect. Upon receiving the authentication frame, the base station device transmits to the terminal device an authentication frame (authentication response) containing a status code indicating whether the terminal device has been authenticated. By reading the status code written in the authentication frame, the terminal device can determine whether it has been authenticated by the base station device. Note that the base station device and terminal device can exchange authentication frames multiple times.

[0034] Following the authentication procedure, the terminal device transmits a connection request frame to the base station device to perform a connection procedure. Upon receiving the connection request frame, the base station device determines whether to permit the connection of the terminal device 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 identifier (AID) for identifying the terminal device. The base station device can manage multiple terminal devices by setting different AIDs for each terminal device to which it has issued connection permission.

[0035] After the connection process is completed, the base station device and the terminal device perform actual data transmission. In the IEEE 802.11 system, a distributed coordination function (DCF), a point coordination function (PCF), and their extended functions (enhanced distributed channel access (EDCA) and hybrid coordination function (HCF) etc.) are defined. The following describes an example in which a base station device transmits a signal to a terminal device using DCF.

[0036] In DCF, base station devices and terminal devices perform carrier sense (CS) to check the usage status of wireless channels around the devices before communication. For example, if a base station device, which is a transmitting station, receives a signal higher than a predetermined clear channel assessment level (CCA level) on the wireless channel, it postpones transmission of a transmission frame on the wireless channel. Hereinafter, a state in which a signal 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 higher than the CCA level is not detected is referred to as an idle state. CS performed by each device based on the power of the signal actually received (received power level) is referred to as physical carrier sense (physical CS). The CCA level is also referred to as the carrier sense level (CS level) or CCA threshold (CCAT). When a signal higher than the CCA level is detected, the base station device and terminal device begin demodulating at least the PHY layer signal.

[0037] Note that, hereinafter, when simply referred to as carrier sense, this includes the case where virtual carrier sense, described below, is performed. Furthermore, hereinafter, when simply referred to as carrier sense level, this also includes the case where the communication device refers to the minimum receiving sensitivity, which indicates the received signal power at which the communication device demodulates at least the PHY layer signal. That is, when a communication device receives a frame, if the communication device observes that the received signal power of the frame is equal to or greater than the minimum receiving sensitivity, the communication device must demodulate at least the PHY layer signal for that frame. This means that if the communication device observes that the received signal power is equal to or less than the minimum receiving sensitivity, the communication device does not need to demodulate the frame, and the communication device can attempt to transmit the frame. Therefore, the carrier sense level and the minimum receiving sensitivity can be considered to have the same meaning.

[0038] A base station device performs carrier sensing for an interframe space (IFS) corresponding to the type of transmission frame to be transmitted, and determines whether the wireless channel is busy or idle. The period during which the base station device performs carrier sensing varies depending on the frame type and subframe type of the transmission frame to be transmitted. The IEEE 802.11 system defines multiple IFSs with different durations, including a short interframe space (SIFS) used for transmission frames assigned the highest priority, a polling interframe space (PCF IFS: PIFS) used for transmission frames with relatively high priority, and a distributed control interframe space (DCF IFS: DIFS) used for transmission frames with the lowest priority. When a base station device transmits a data frame using DCF, the base station device uses DIFS.

[0039] After waiting for the DIFS, the base station device further waits for a random backoff time to prevent frame collisions. In the IEEE 802.11 system, a random backoff time called a contention window (CW) is used. CSMA / CA assumes that a transmission frame sent by a transmitting station is received by a receiving station without interference from other transmitting stations. Therefore, if two transmitting stations transmit frames at the same time, the frames collide, and the receiving station cannot receive the frames correctly. Therefore, frame collisions are avoided by each transmitting station waiting for a randomly set time before starting transmission. When the base station device determines through carrier sense that the wireless channel is idle, it starts counting down the CW. Only when the CW reaches 0 does it acquire the right to transmit and can transmit a transmission frame to the terminal device. Note that if the base station device determines through carrier sense that the wireless channel is busy during the CW countdown, it stops the CW countdown. Then, when the radio channel becomes idle, the base station device restarts counting down the remaining CW following the previous IFS.

[0040] The terminal device, which is the receiving station, receives the transmitted frame, reads the PHY header of the transmitted frame, and demodulates the received transmitted frame.The terminal device can then determine whether the transmitted frame is addressed to itself by reading the MAC header of the demodulated signal.The terminal device can also determine the destination of the transmitted frame based on information written in the PHY header (e.g., the group identifier (GID) written in the VHT-SIG-A).

[0041] If a terminal device determines that the received transmission frame is addressed to itself and successfully demodulates the transmission frame, it must transmit an ACK frame to the base station, which is the transmitting station, indicating that the frame was received correctly. The ACK frame is one of the highest-priority transmission frames, which is transmitted after waiting only an SIFS period (no random backoff time is taken). The base station device terminates a series of communications upon receiving the ACK frame from the terminal device. If the terminal device fails to receive the frame correctly, it does not transmit an ACK. Therefore, if the base station device does not receive an ACK frame from the receiving station within a certain period (SIFS + ACK frame length) after transmitting the frame, it will consider the communication to have failed and terminate the communication. Thus, the end of a single communication (also called a burst) in an IEEE 802.11 system is always determined by whether or not an ACK frame is received, except in special cases such as when transmitting a beacon frame or other notification signal, or when fragmentation is used to divide the transmission data.

[0042] When a terminal device determines that a received transmission frame is not addressed to the terminal device, the terminal device sets a network allocation vector (NAV) based on the length of the transmission frame described in the PHY header or the like. The terminal device does not attempt communication during the period set in the NAV. In other words, the terminal device performs the same operation as when it determines that the wireless channel is busy by physical CS during the period set in the NAV, so communication control using the NAV is also called virtual carrier sense (virtual CS). In addition to being set based on information described in the PHY header, the NAV is also set by a request to send (RTS) frame or a clear to send (CTS) frame, which are introduced to solve the hidden terminal problem.

[0043] In contrast to 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, a base station device becomes the PC and acquires the transmission right for terminal devices within the BSS.

[0044] 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 during the CFP, the PC controls the transmission right. A base station device, which is a PC, broadcasts a beacon frame containing the CFP duration (CFP Max duration) and other information within the BSS prior to PCF communication. Note that the beacon frame broadcast at the start of PCF transmission uses a PIFS and is transmitted without waiting for a CW. A terminal device that receives the beacon frame sets the CFP duration described in the beacon frame as its NAV. Thereafter, until the NAV elapses or a signal announcing the end of the CFP within the BSS (e.g., a data frame including a CF-end) is received, the terminal device can acquire the transmission right only when it receives a signal signaling acquisition of the transmission right transmitted from the PC (e.g., a data frame including a CF-poll). During the CFP period, no packet collisions occur within the same BSS, so each terminal device does not take the random backoff time used in DCF.

[0045] A wireless medium can be divided into multiple resource units (RUs). FIG. 4 is a schematic diagram showing an example of how a wireless medium is divided. For example, in resource division example 1, a wireless communication device can divide the frequency resources (subcarriers, frequency tones, and tones) 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 FIG. 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 AP) can simultaneously transmit frames to multiple terminal devices (e.g., multiple STAs) by placing frames addressed to different terminal devices in each RU. The AP can include information indicating the division status of the wireless medium (resource allocation information) in the PHY header of a frame transmitted by the AP as common control information. Furthermore, the AP can write information indicating the RU in which the frame addressed to each STA is placed (resource unit assignment information) as unique control information in the PHY header of the frame transmitted by the AP itself.

[0046] Furthermore, multiple terminal devices (e.g., multiple STAs) can simultaneously transmit frames by placing frames in their assigned RUs and transmitting them. After receiving a frame (Trigger frame: TF) containing trigger information transmitted from the AP, the multiple STAs can wait a predetermined period of time before transmitting frames. Each STA can grasp the RU assigned to itself based on the information contained in the TF. Furthermore, each STA can acquire an RU by random access based on the TF.

[0047] An AP can simultaneously allocate multiple RUs to one STA. The multiple RUs can be configured on consecutive or non-consecutive subcarriers. The AP can transmit one frame using the multiple RUs allocated to one STA, 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 multiple terminal devices that transmit resource allocation information.

[0048] One STA can be assigned multiple RUs by the AP. The STA can transmit one frame using the assigned multiple RUs. Also, the STA can use the assigned multiple RUs to transmit multiple frames, each assigned to a different RU. The multiple frames can be frames of different frame types.

[0049] An AP can assign multiple AIDs (Association IDs) to one STA. The AP can assign RUs to each of the multiple AIDs assigned to one STA. The AP can transmit different frames to each of the multiple AIDs assigned to one STA using the assigned RUs. The different frames can be frames of different frame types.

[0050] A single STA can be assigned multiple AIDs (Associate IDs) by an AP. Each STA can be assigned an RU for each of the multiple AIDs. A single STA recognizes all RUs assigned to its own AIDs as its own RUs and can transmit a single frame using the multiple RUs. A single STA can also transmit multiple frames using the multiple RUs. In this case, the multiple frames can include information indicating the AIDs associated with each assigned RU. The AP can transmit different frames for each of the multiple AIDs assigned to a single STA using the assigned RUs. The different frames can be of different frame types.

[0051] Hereinafter, base station devices and terminal devices will be collectively referred to as wireless communication devices or communication devices. Information exchanged when one wireless communication device communicates with another wireless communication device will also be referred to as data. In other words, wireless communication devices include base station devices and terminal devices.

[0052] A wireless communication device has either a function for transmitting a PPDU or a function for receiving a PPDU, or both. Fig. 1 is a diagram showing an example of the configuration of a PPDU transmitted by a wireless communication device. A PPDU conforming to the IEEE 802.11a / b / g standard is configured to include an L-STF, an L-LTF, an L-SIG, and a Data frame (MAC Frame, MAC Frame, payload, data section, data, information bits, etc.). A PPDU conforming to the IEEE 802.11n standard is configured to include an L-STF, an L-LTF, an L-SIG, an HT-SIG, an HT-STF, an HT-LTF, and a Data frame. A PPDU conforming to the IEEE 802.11ac standard is configured to include some or all of the following: L-STF, L-LTF, L-SIG, VHT-SIG-A, VHT-STF, VHT-LTF, VHT-SIG-B, and a MAC frame. A PPDU considered in the IEEE 802.11ax standard is configured to include some or all of the following: L-STF, L-LTF, L-SIG, RL-SIG, which is a time-repeated L-SIG, HE-SIG-A, HE-STF, HE-LTF, HE-SIG-B, and a Data frame. The PPDU considered in the IEEE 802.11be standard is configured to include some or all of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, HET-LTF, and Data frames.

[0053] The L-STF, L-LTF, and L-SIG enclosed by dotted lines in Figure 1 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 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.

[0054] However, wireless communication devices that comply with the IEEE 802.11a / b / g standards cannot demodulate the PPDU that follows the L-header and complies with the IEEE 802.11n / ac standards, and therefore cannot demodulate information related to the transmitter address (TA), receiver address (RA), and the Duration / ID field used to set the NAV.

[0055] IEEE 802.11 specifies a method of inserting Duration information into L-SIG as a method for wireless communication devices conforming to the IEEE 802.11a / b / g standards to appropriately set NAV (or perform reception operation for a predetermined period of time). Information on the transmission rate in the L-SIG (RATE field, L-RATE field, L-RATE, L_DATARATE, L_DATARATE field) and information on the transmission period (LENGTH field, L-LENGTH field, L-LENGTH) are used by wireless communication devices conforming to the IEEE 802.11a / b / g standards to appropriately set NAV.

[0056] FIG. 2 is a diagram showing an example of a method for inserting Duration information into L-SIG. In FIG. 2, a PPDU configuration corresponding to the IEEE 802.11ac standard is shown as an example, but the PPDU configuration is not limited to this. A PPDU configuration corresponding to the IEEE 802.11n standard and a PPDU configuration corresponding to the IEEE 802.11ax standard may also be used. TXTIME includes information on the length of the PPDU, aPreambleLength includes information on the length of the preamble (L-STF+L-LTF), and aPLCPHeaderLength includes information on the length of the PLCP header (L-SIG). L_LENGTH is a virtual period set to achieve compatibility with the IEEE 802.11 standard, and is related to Signal Extension and L_RATE. ｏｐｓIt is calculated based on aSymbolLength, which is information about the duration of one symbol (symbol, OFDM symbol, etc.), aPLCPServiceLength, which indicates the number of bits included in the PLCP Service field, and aPLCConvolutionalTailLength, which indicates the number of tail bits of the convolutional code. The wireless communication device can calculate L_LENGTH and insert it into L-SIG. The wireless communication device can also calculate L-SIG Duration. L-SIG Duration indicates information about the duration obtained by adding together the duration of a PPDU including L_LENGTH and the duration of an Ack and SIFS that are expected to be transmitted from the destination wireless communication device in response to the PPDU.

[0057] FIG. 3 is a diagram showing an example of L-SIG Duration in L-SIG TXOP Protection. DATA (frame, payload, data, etc.) is composed of a MAC frame and part of a PLCP header, or both. BA is Block Ack or Ack. PPDU includes L-STF, L-LTF, and L-SIG, and can further include any one or more of DATA, BA, RTS, and CTS. While the example shown in FIG. 3 shows L-SIG TXOP Protection using RTS / CTS, CTS-to-Self may also be used. Here, MAC Duration is the period indicated by the value of the Duration / ID field. In addition, the initiator can transmit a CF_End frame to notify the end of the L-SIG TXOP Protection period.

[0058] Next, a method for identifying a BSS from a frame received by a wireless communication device will be described. In order for a wireless communication device to identify a BSS from a frame received, it is preferable for the wireless communication device transmitting a 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 described in HE-SIG-A.

[0059] The wireless communication device can transmit the L-SIG multiple times (L-SIG Repetition). For example, the receiving wireless communication device receives the L-SIG transmitted multiple times using MRC (Maximum Ratio Combining), thereby improving the demodulation accuracy of the L-SIG. Furthermore, when the wireless communication device has correctly received the L-SIG using MRC, it can interpret the PPDU including the L-SIG as a PPDU conforming to the IEEE 802.11ax standard.

[0060] Even during the operation of receiving a PPDU, the wireless communication device can perform an operation of receiving a part of a PPDU other than the PPDU (for example, a preamble, L-STF, L-LTF, PLCP 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 operation of receiving a PPDU, it can update some or all of the destination address, source address, and information related to the PPDU or DATA period.

[0061] Ack and BA can also be called responses (response frames). Also, probe responses, authentication responses, and connection responses can also be called responses. [1. First Embodiment]

[0062] FIG. 5 is a diagram showing an example of a wireless communication system according to this embodiment. The wireless communication system 3-1 includes a wireless communication device 1-1 and wireless communication devices 2-1 to 2-4. The wireless communication device 1-1 is also referred to as a base station device 1-1, and the wireless communication devices 2-1 to 2-4 are also referred to as terminal devices 2-1 to 2-4. The wireless communication devices 2-1 to 2-4 and the terminal devices 2-1 to 2-4 are also referred to as a wireless communication device 2A and a terminal device 2A, respectively, as devices connected to the wireless communication device 1-1. The wireless communication device 1-1 and the wireless communication device 2A are wirelessly connected and are capable of transmitting and receiving PPDUs to and from each other. In addition to the wireless communication system 3-1, the wireless communication system 3-2 includes a wireless communication device 1-2 and wireless communication devices 2-5 to 2-8. The wireless communication device 1-2 is also referred to as a base station device 1-2, and the wireless communication devices 2-5 to 2-8 are also referred to as terminal devices 2-5 to 2-8. Furthermore, the wireless communication devices 2-5 to 2-8 and the terminal devices 2-5 to 2-8 are also referred to as wireless communication device 2B and terminal device 2B as devices connected to the wireless communication device 1-2. The wireless communication system 3-1 and the wireless communication system 3-2 form different BSSs, but this does not necessarily mean that the ESSs (Extended Service Sets) are different. An ESS indicates a service set that forms a LAN (Local Area Network). In other words, wireless communication devices belonging to the same ESS can be considered to belong to the same network from a higher layer. Note that the wireless communication systems 3-1 and 3-2 may also include multiple wireless communication devices.

[0063] 5, in the following description, it is assumed that a signal transmitted by wireless communication device 2A reaches wireless transmission device 1-1 and wireless communication device 2B but does not reach wireless communication device 1-2. In other words, when wireless communication device 2A transmits a signal using a certain channel, wireless communication device 1-1 and wireless communication device 2B determine that channel to be busy, while wireless communication device 1-2 determines that channel to be idle. Also, it is assumed that a signal transmitted by wireless communication device 2B reaches wireless transmission device 1-2 and wireless communication device 2A but does not reach wireless communication device 1-1. In other words, when wireless communication device 2B transmits a signal using a certain channel, wireless communication device 1-2 and wireless communication device 2A determine that channel to be busy, while wireless communication device 1-1 determines that channel to be idle.

[0064] 6 is a diagram showing an example of the device configuration of wireless communication devices 1-1, 1-2, 2A, and 2B (hereinafter collectively referred to as wireless communication device 10-1, station device 10-1, or simply station device). Wireless communication device 10-1 is configured to include an upper layer unit (upper layer processing step) 10001-1, an autonomous distributed control unit (autonomous distributed control step) 10002-1, a transmitter (transmitting step) 10003-1, a receiver (receiving step) 10004-1, and an antenna unit 10005-1.

[0065] The upper layer unit 10001-1 is connected to other networks and can notify the autonomous distributed control unit 10002-1 of traffic information. The traffic information may be, for example, information addressed to other wireless communication devices, or control information included in management frames or control frames.

[0066] 7 is a diagram showing an example of the device configuration of the autonomous distributed control unit 10002-1. The autonomous distributed control unit 10002-1 is configured to include a CCA unit (CCA step) 10002a-1, a backoff unit (backoff step) 10002b-1, and a transmission determination unit (transmission determination step) 10002c-1.

[0067] The CCA unit 10002a-1 can determine the state of the radio resource (including determining whether it is busy or idle) using either or both of information about the received signal power received via the radio resource and information about the received signal (including information after decoding) notified from the receiving unit. The CCA unit 10002a-1 can notify the backoff unit 10002b-1 and the transmission determination unit 10002c-1 of the state determination information of the radio resource.

[0068] The backoff unit 10002b-1 can perform backoff using radio resource state determination information. The backoff unit 10002b-1 generates a CW and has a countdown function. For example, when the radio resource state determination information indicates idle, the backoff unit 10002b-1 can countdown the CW, and when the radio resource state determination information indicates busy, the backoff unit 10002b-1 can notify the transmission determination unit 10002c-1 of the value of the CW.

[0069] The transmission decision unit 10002c-1 makes a transmission decision using either the wireless resource status decision information or the CW value, or both. For example, when the wireless resource status decision information indicates idle and the CW value is 0, the transmission decision unit 10002c-1 can notify the transmission decision information to the transmitting unit 10003-1. Also, when the wireless resource status decision information indicates idle, the transmission decision unit 10002c-1 can notify the transmission decision information to the transmitting unit 10003-1.

[0070] The 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 from 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 notifies the wireless transmitting unit 10003b-1 of the generated physical layer frame.

[0071] FIG. 8 is a diagram illustrating an example of error correction coding performed by the physical frame generator according to this embodiment. As shown in FIG. 8, information bit (systematic bit) sequences are arranged in the shaded areas, and redundant (parity) bit sequences are arranged in the open areas. A bit interleaver is appropriately applied to each of the information bits and redundant bits. The physical frame generator can read the required number of bits from the arranged bit sequences, with the starting position determined according to the value of the redundancy version (RV). Adjusting the number of bits enables flexible changes in the coding rate, i.e., puncturing. Note that while FIG. 8 shows a total of four RVs, the RV options are not limited to specific values ​​in the error correction coding according to this embodiment. The RV positions must be shared among station devices.

[0072] The physical layer frame generator performs error correction coding on the information bits transferred from the MAC layer, but the unit for performing error correction coding (coding block length) is not limited to any particular value. For example, the physical layer frame generator can divide the information bit sequence transferred from the MAC layer into information bit sequences of a predetermined length, and perform error correction coding on each of the information bit sequences to form multiple coding blocks. In addition, when forming the coding blocks, dummy bits can also be inserted into the information bit sequence transferred from the MAC layer.

[0073] The frames generated by the physical layer frame generator 10003a-1 include 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 allocated. The frames generated by the physical layer frame generator 10003a-1 also include a trigger frame that instructs the wireless communication device, which is the destination terminal, to transmit a frame. This trigger frame includes information indicating the RU to be used when the wireless communication device instructed to transmit the frame transmits the frame.

[0074] The wireless transmission unit 10003b-1 converts the physical layer frame generated by the physical layer frame generation unit 10003a-1 into a radio frequency (RF) band signal to generate a radio frequency signal. The processing performed by the wireless transmission unit 10003b-1 includes digital-to-analog conversion, filtering, frequency conversion from the baseband band to the RF band, etc.

[0075] The receiving unit 10004-1 includes a wireless receiving unit (wireless receiving step) 10004a-1 and a signal demodulation unit (signal demodulation step) 10004b-1. The receiving unit 10004-1 generates information about 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 information about received signal power and information about the received signal.

[0076] The wireless receiving unit 10004a-1 has the function of converting an RF band signal received by the antenna unit 10005-1 into a baseband signal and generating a physical layer signal (e.g., a physical layer frame). The processing performed by the wireless receiving unit 10004a-1 includes frequency conversion from the RF band to the baseband, filtering, and analog-to-digital conversion.

[0077] 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, etc. The signal demodulation unit 10004b-1 can extract, for example, information contained in the physical layer header, information contained in the MAC header, and information contained in the transmission frame from the physical layer signal. The signal demodulation unit 10004b-1 can notify the upper layer unit 10001-1 of the extracted information. Note that 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 information contained in the transmission frame.

[0078] The antenna unit 10005-1 has a function of transmitting the radio frequency signal generated by the wireless transmission unit 10003b-1 into wireless space toward the wireless device 0-1, and also has a function of receiving the radio frequency signal transmitted from the wireless device 0-1.

[0079] The wireless communication device 10-1 can cause wireless communication devices around the wireless communication device 10-1 to set NAVs for only that period by writing information indicating the period during which the wireless communication device 10-1 will use the wireless medium in the PHY header or MAC header of the frame it transmits. For example, the wireless communication device 10-1 can write information indicating that period in the Duration / ID field or Length field of the frame it transmits. The NAV period set in the wireless communication devices around the wireless communication device 10-1 is referred to as the TXOP period (or simply TXOP) acquired by the wireless communication device 10-1. The wireless communication device 10-1 that has acquired the TXOP is referred to as the TXOP acquirer (TXOP holder). The frame type of the frame that the wireless communication device 10-1 transmits to acquire the TXOP is not limited to any particular type, and may be a control frame (e.g., an RTS frame or a CTS-to-self frame) or a data frame.

[0080] The wireless communication device 10-1, which is a TXOP holder, can transmit frames to wireless communication devices other than itself during the TXOP. When the wireless communication device 1-1 is a TXOP holder, the wireless communication device 1-1 can transmit frames to the wireless communication device 2A during the TXOP period. Furthermore, the wireless communication device 1-1 can instruct the wireless communication device 2A to transmit a frame addressed to the wireless communication device 1-1 during the TXOP period. The wireless communication device 1-1 can transmit a trigger frame including information instructing the wireless communication device 2A to transmit a frame addressed to the wireless communication device 1-1 during the TXOP period.

[0081] The wireless communication device 1-1 may reserve a TXOP for all communication bands (e.g., Operation bandwidth) over which frames may be transmitted, or may reserve a TXOP for a specific communication band (e.g., Transmission bandwidth) over which frames are actually transmitted.

[0082] The wireless communication device that instructs the wireless communication device 1-1 to transmit a frame during the acquired TXOP period is not necessarily limited to the wireless communication device connected to the wireless communication device itself. For example, the wireless communication device can instruct wireless communication devices that are not connected to the wireless communication device itself to transmit a frame in order to have wireless communication devices in the vicinity of the wireless communication device itself transmit a management frame such as a Reassociation frame or a control frame such as an RTS / CTS frame.

[0083] In this embodiment, the signal demodulator of the station device can perform decoding and error detection on the received signal in the physical layer. Here, the decoding includes decoding of the error correction code applied to the received signal. Here, the error detection includes error detection using an error detection code (e.g., a cyclic redundancy check (CRC) code) previously assigned to the received signal, or error detection using an error correction code that originally has an error detection function (e.g., a low-density parity check (LDPC) code). The decoding in the physical layer can be applied to each coding block.

[0084] The upper layer transfers the result of decoding the physical layer in the signal demodulation unit to the MAC layer. The MAC layer restores the MAC layer signal from the transferred physical layer decoding result. The MAC layer then performs error detection to determine whether the MAC layer signal transmitted by the station device that transmitted the received frame was correctly restored.

[0085] A communication device according to this embodiment can maintain multiple connections (links). Here, maintaining a connection means being able to transmit and receive frames based on predetermined settings. FIG. 9 is a schematic diagram illustrating communication according to this embodiment. As shown in FIG. 9, the access point device 1-1 according to this embodiment can maintain connections between station devices 2-1 and 2-2 using different carrier frequencies. For example, the access point device 1-1 according to this embodiment can set a 2.4 GHz frequency for connection 9-1 with station device 2-1 and a 5 GHz frequency for connection 9-2 with station device 2-2.

[0086] FIG. 10 is a schematic diagram showing communication according to this embodiment. As shown in FIG. 10, the access point device 1-1 according to this embodiment can maintain two connections with the station device 2-1. For example, a frequency in the 2.4 GHz band can be set for the connection 10-1, and a frequency in the 5 GHz band can be set for the connection 10-2. By setting the frequencies in this manner, the access point device 1-1 can exchange frames with the station device 2-1 using the two frequencies.

[0087] The communication device according to this embodiment can determine whether to transmit frames using multiple connections depending on the state of the wireless medium, thereby enabling efficient frame transmission.

[0088] FIG. 11 is a schematic diagram illustrating communication according to this embodiment. According to the example of FIG. 11, the access point device and the station device can exchange frames using two connections: connection 10-1 (first connection) and connection 10-2 (second connection). Naturally, the method according to this embodiment also includes cases in which the access point device maintains three or more connections. Here, the access point device first transmits a medium securing frame for each connection to secure the wireless medium for a certain period of time. The medium securing frame contains information indicating the time period during which the access point device secures the wireless medium. While the example of FIG. 11 shows the access point device simultaneously transmitting frames for securing the wireless medium over connections 10-1 and 10-2, the method according to this embodiment is not limited to this. That is, the access point device can transmit frames for securing the wireless medium at different times over multiple connections. However, even in this case, it is desirable that the end timing of the period during which the frames for securing the wireless medium secure the wireless medium be the same across the multiple connections. This indicates that the time periods (information associated with the NAV described in the frames) reserved by the medium securing frames transmitted over each connection may be the same or different.

[0089] The medium reservation frame is not limited to any particular frame. For example, the access point device can transmit a Request to Send (RTS) frame for each connection as a frame for reserving the wireless medium. The access point device can also transmit a Multi-User RTS (MU-RTS) frame, which is an RTS frame addressed to multiple users. The access point device can also transmit a trigger frame, which triggers a response frame (first response frame) to a station device, as a frame for reserving the wireless medium. The following description will be given taking as an example a case where the access point device transmits an RTS frame as a frame for reserving the wireless medium.

[0090] Each station device that receives an RTS frame transmitted by the access point device in each connection determines whether to transmit a first response frame (first frame) based on the state of the wireless medium of the connection that received the RTS frame. For example, if the station device determines that the wireless medium through which the RTS frame was received is idle, the station device transmits a Clear to Send (CTS) frame as the first response frame in the connection through which the RTS frame was received. On the other hand, if the station device determines that the wireless medium through which the RTS frame was received is busy, the station device does not transmit a CTS frame in the connection. Note that the first response frame transmitted by the station device is not limited to a CTS frame. The station device may transmit a control frame other than a CTS frame, a management frame, or a data frame as the first response frame. However, it is preferable that the station device include information in the first response frame indicating that the first response frame is a frame handed over by the access point device. The access point device may also specify the information that the station device includes in the first response frame.

[0091] For a connection in which a CTS frame is received, the access point device determines that the wireless medium for that connection has been secured and can transmit a frame. On the other hand, for a connection in which a CTS frame is not received, the access point device determines that the wireless medium for that connection has not been secured and does not transmit a frame. Conventional communication devices allow accurate wireless medium security between communication devices by exchanging RTS and CTS frames between them. If an access point device is able to transmit an RTS frame but is unable to receive a CTS frame, this means that the station device that received the RTS frame has determined that the wireless medium is busy. In this case, the station device may have determined that the wireless medium is busy based on a frame (OBSS frame) belonging to a BSS managed by an access point device other than the access point device. If the station device determines that the wireless medium is busy based on the OBSS frame, the station device may not be able to attempt frame transmission, but may be able to receive frames on the wireless medium.

[0092] Therefore, in this embodiment, when a station device receives an RTS frame over multiple connections and is capable of transmitting a CTS frame as a response frame over at least one of the connections, the station device can include, in the CTS frame, information indicating the status of the wireless medium of connections other than the connection transmitting the CTS frame. In the following description, the station device will be described using an example in which the station device transmits a CTS frame as a response frame. However, the type of frame including information indicating the status of the wireless medium of connections other than the connection transmitting the frame is not limited to a CTS frame. Control frames other than CTS frames, management frames, and data frames may also be used. However, it goes without saying that the response frame must include information that allows the access point device and station device receiving the response frame to recognize that the response frame includes information indicating the status of the wireless medium of connections other than the connection transmitting the response frame. This information can be explicitly described in the PHY header or MAC header. This information can also be implicitly notified to the access point device and station device by the modulation scheme or signal constellation applied to the response frame.

[0093] Here, the information indicating the state of the wireless medium may be information indicating the state of the NAV set by the station device transmitting the CTS frame for each connection. For example, the station device may include information indicating whether the station device has set a NAV for the connection 10-2 in the CTS frame transmitted over the connection 10-1. Furthermore, the station device may include information indicating the attributes of the NAV set by the station device for the connection 10-2 in the CTS frame transmitted over the connection 10-1, such as whether the NAV set by the station device for the connection 10-2 is an NAV (intra-NAV) set by a frame associated with a BSS to which the station device belongs, an NAV (inter-NAV, OBSS-NAV) set by a frame associated with a BSS to which the station device does not belong, or an NAV (Basic-NAV) set when the BSS to which the frame that caused the NAV to be set belongs is unknown.

[0094] The information indicating the state of the wireless medium may be information indicating interference power in each connection. Here, the information indicating interference power includes a received signal strength indicator (RSSI) and a received channel power indicator (RCPI). The information indicating interference power also includes information indicating the received power of the legacy header portion of the frame being received by the station device in the connection. The legacy header portion includes at least a portion of L-STF, L-LTF, and L-SIG. The station device may also notify the access point device of the difference between the desired received power in the second connection and the received power of the header portion of the medium securing frame received in the second connection.

[0095] Returning to Figure 11, an access point device that receives a CTS frame on connection 10-1 including information indicating the wireless medium information of connection 10-2 can, after a predetermined period of time has elapsed, transmit a frame (second frame) to the station device on connection 10-1, while also being able to determine whether to transmit a frame to the station device on connection 10-2 using the information indicating the wireless medium information of connection 10-2.

[0096] For example, if the information about the wireless medium of connection 10-2 indicates that the NAV set by the station device for connection 10-2 is OBSS-NAV, the access point device can transmit frames over connection 10-2. As explained above, if the frame that caused the station device to determine that the wireless medium for connection 10-2 was busy was an OBSS frame, the station device is likely to be able to receive frames even if it is unable to transmit frames. Naturally, the OBSS frame is likely to reduce the received signal-to-interference power ratio (SIR) of frames transmitted by the access point device over connection 10-2. However, by appropriately setting the modulation method and coding rate to be applied to the frames, the access point device can ensure that the station device correctly receives frames received over connection 10-2.

[0097] For example, if the wireless medium information for connection 10-2 indicates the interference power measured by the station device in connection 10-2, the access point device can transmit a frame in connection 10-2 if the station device can meet the desired reception quality in connection 10-2.

[0098] A station device that receives a frame on both connections 10-1 and 10-2 transmits a response frame (second response frame) triggered by the frame. For example, the station device demodulates each frame on both connections 10-1 and 10-2 and performs error detection. The station device then transmits an ACK frame containing information indicating whether the frame was received correctly as a second response frame to the access point device. At this time, it is not desirable for the station device to transmit a second response frame on connection 10-2, where the station device has determined that the wireless medium is busy based on the OBSS frame. Therefore, the station device can transmit a second response frame triggered by a frame received on connection 10-2 on connection 10-1. Alternatively, the station device can include information contained in the second response frame triggered by a frame received on connection 10-2 in the second response frame triggered by a frame received on connection 10-1, and then transmit the second response frame on connection 10-1. In this way, the station device may be described as transmitting the second response frame on connection 10-1, even if the information contained in the second response frame caused by the frame received on connection 10-2 is included in the second response frame caused by the frame received on connection 10-1 and then transmitted on connection 10-1.

[0099] When the station device receives a frame over the connection 10-2, it can determine whether to update its NAV. When the station device receives a frame from the access point device over the connection 10-2, it can refrain from updating its inter-NAV and Basic NAV. Furthermore, the station device can refrain from transmitting frames over the connection 10-1 during the time period during which it transmits the second response frame. That is, when the station device receives a frame from the access point device over the connection 10-2, it demodulates the frame. However, if the inter-NAV or Basic NAV expires during reception of the frame, the station device can update the NAV over the connection 10-1 during the time period until it completes transmission of the second response frame.

[0100] The access point device can write information indicating the connection for transmitting the second response frame to the station device in the PHY header or MAC header of a frame to be transmitted after receiving the first response frame.

[0101] As described above, the connection through which the station device transmits the second response frame can be set by the access point device, but it can also be set by the station device. For example, the station device can transmit the second response frame over the connection through which the station device transmitted the first response frame. If the station device transmits the first response frame over multiple connections, the station device can randomly select the connection through which the second response frame is transmitted from among the multiple connections through which the first response frame is transmitted, or can select the connection with the lowest frequency. Alternatively, the station device can set priorities for multiple connections in advance, and transmit the second response frame over the connection with the highest priority.

[0102] A station device can directly include information about connections for which the station device cannot receive in a response frame to a medium reservation frame transmitted by an access point device. Here, the connection information can be a channel number shared with the access point device. Furthermore, the access point device can broadcast information about the connections it maintains using a beacon frame or the like, and at this time, can assign numbers (IDs) to the multiple connections it maintains. The station device can treat these numbers as connection information.

[0103] When the access point device transmits a frame over connection 10-2, the access point device can transmit the frame after performing carrier sensing including a random backoff operation. In this case, after receiving the first response frame, the frame transmission start timings of the frames transmitted over connection 10-1 and the frames transmitted over connection 10-2 do not match between connection 10-1 and connection 10-2. However, it is preferable for the access point device to match the frame ends of the frames transmitted over connection 10-1 and connection 10-2. Alternatively, the access point device can set the frame end of the frame transmitted over connection 10-2 to be earlier than the frame end of the frame transmitted over connection 10-1. Furthermore, prior to performing carrier sensing over connection 10-2, the access point device can transmit a frame (first release frame) over connection 10-2 that releases the wireless medium secured by the previously transmitted RTS frame.

[0104] If the access point device performs carrier sensing when transmitting a medium securing frame, it is not necessarily required to perform carrier sensing when transmitting a frame on the connection 10-2.

[0105] The information about the multiple connections that the station device writes in the response frame can further include multiple pieces of information within each connection. For example, if connection 10-2 is a channel with a bandwidth of 80 MHz, the station device can further divide the 80 MHz channel into four bands of 20 MHz each, and for each band, write information indicating the status of the wireless medium, such as the NAV status and received power status shown above, in the response frame to notify the access point device. This means that the response frame transmitted by the station device contains multiple fields for describing information indicating the status of the wireless medium, and these multiple fields include a field for describing information about each connection and, if each connection has multiple channels, a field for describing information indicating the status of each wireless medium.

[0106] By controlling in this manner, the access point device and the station device can efficiently exchange frames using multiple connections in a dense environment where many access point devices and station devices exist, thereby improving system efficiency. [2. Second Embodiment]

[0107] The configurations of the access point device and station device constituting this embodiment are the same as those of the first embodiment.

[0108] 12 is a schematic diagram showing a communication state according to this embodiment. In this embodiment, the access point device sets up a connection requesting a response frame from the station device depending on the state of the wireless medium of the multiple connections.

[0109] Consider a case where an access point device determines that connection 10-1 is in an idle state on the wireless medium, while connection 10-2 is in a busy state due to an OBSS frame. Normally, when the wireless medium is determined to be busy, the communication device cannot transmit frames on the wireless medium. However, if a predetermined criterion is met, the communication device can transmit frames if the reason for determining that the wireless medium is busy is due to an OBSS frame.

[0110] Therefore, the access point device transmits frames on each of the connections 10-1 and 10-2, but does not expect a response frame to be transmitted from the station device on the connection 10-2. If the frame transmitted by the access point device on the connection 10-2 triggers a response frame, the access point device can instruct the station device to transmit the response frame on the connection 10-1 or to include information contained in the response frame in a frame transmitted on the connection 10-1.

[0111] Since the access point device knows that the wireless medium for connection 10-2 is determined to be busy by the OBSS frame, it can transmit frames according to the criteria for frame transmission on connection 10-2. However, there is no guarantee that the access point device can correctly receive frames transmitted by the station device on connection 10-2. Therefore, the access point device can notify the station device to transmit, on connection 10-1, response frames triggered by frames transmitted by the access point device on connection 10-2.

[0112] When an access point device transmits a frame using multiple connections, the wireless medium must be in an idle state for at least one of the connections. That is, if the access point device determines that the wireless medium is busy for all of the multiple connections through which the access point device attempts to transmit a frame based on either an OBSS frame or a frame belonging to a BSS managed by the access point device, the access point device cannot transmit the frame even if the multiple connections include a connection for which the wireless medium is determined to be busy based on the OBSS frame. In other words, if the access point device can guarantee that it can receive a response frame transmitted from a station device through at least one of the multiple connections through which the access point device transmits a frame, the access point device can transmit a frame through the connection for which the wireless medium is determined to be busy based on the OBSS frame. [3. Common to All Embodiments]

[0113] A communication device according to an embodiment of the present invention can communicate in a frequency band (frequency spectrum) that does not require permission to use from a country or region, which is called an unlicensed band, but the usable frequency band is not limited to this. The communication device according to an embodiment of the present invention can also be effective in, for example, a frequency band called a white band that is not actually used for purposes such as preventing interference between frequencies even though permission to use the band is granted for a specific service by a country or region (for example, a frequency band allocated for television broadcasting but unused in some regions), or in a shared spectrum (shared frequency band) that is expected to be shared by multiple operators.

[0114] Furthermore, the communication device according to one aspect of the present invention is not limited to a specific communication standard. For example, when a communication standard that is primarily intended for a frequency band known as a licensed band, for which permission for use has been obtained from a country or region (e.g., a communication standard approved by ITU-R as IMT-Advanced or IMT-2020) is introduced into an unlicensed band, the communication device can also demonstrate its effectiveness with the communication standard.

[0115] A program running on a wireless communication device according to one aspect of the present invention is a program (a program that causes a computer to function) that controls a CPU and other components to implement the functions of the above-described embodiment according to one aspect of the present invention. Information handled by these devices is temporarily stored in RAM during processing, and then stored in various ROMs or HDDs, where it is read, modified, and written by the CPU as needed. Recording media for storing the program may include semiconductor media (e.g., ROM, non-volatile memory cards, etc.), optical recording media (e.g., DVDs, MOs, MDs, CDs, BDs, etc.), magnetic recording media (e.g., magnetic tapes, flexible disks, etc.), etc. Furthermore, not only are the functions of the above-described embodiment implemented by executing the loaded program, but the functions of the present invention may also be implemented by processing in cooperation with an operating system or other application programs, etc., based on instructions from the program.

[0116] 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 one aspect of the present invention. Furthermore, part or all of the communication device in the above-described embodiments may be realized as an LSI, which is typically an integrated circuit. Each functional block of the communication device may be individually formed into a chip, or part or all of the functional blocks may be integrated into a chip. When each functional block is formed into an integrated circuit, an integrated circuit control unit that controls them is added.

[0117] Furthermore, the method of integration is not limited to LSI, but may be realized by a dedicated circuit or a general-purpose processor. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, it may also be possible to use an integrated circuit based on that technology.

[0118] 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.

[0119] 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.

[0120] One aspect of the present invention is suitable for use in an access point device, a station device, and a communication method.

[0121] 1-1, 1-2 Access point device 2-1 to 8 Station device 3-1, 3-2 Management range 10001-1 Upper layer unit 10002-1 Autonomous distributed control unit 10002a-1 CCA unit 10002b-1 Backoff unit 10002c-1 Transmission decision unit 10003-1 Transmitter 10003a-1 Physical layer frame generator 10003b-1 Wireless transmitter 10004-1 Receiver 10004a-1 Wireless receiver 10004b-1 Signal demodulator 10005-1 Antenna unit

Claims

1. An access point device using a plurality of links, comprising: a memory; a transmission circuit unit configured to transmit, via a second link, a response frame including first information corresponding to a first link, the transmission circuit unit being electrically connected to the memory. The first information includes a first ID for the first link. The response frame further includes information regarding power for the first link. The access point device.

2. The access point device according to claim 1, wherein the response frame includes information regarding interference power of the first link.

3. The response frame further includes second information corresponding to the second link. The second information includes a second ID for the second link. The access point device according to claim 1.

4. A station device using a plurality of links, comprising: a memory; a reception circuit unit configured to receive, via a second link, a response frame including first information corresponding to a first link, the reception circuit unit being electrically connected to the memory. The first information includes a first ID for the first link. The response frame further includes information regarding power for the first link. The station device.

5. The station device according to claim 4, wherein the response frame includes information regarding interference power of the first link.

6. The response frame further includes second information corresponding to the second link, and the second information includes a second ID for the second link. The station device according to claim 4.

7. A communication method for an access point device using a plurality of links, comprising: transmitting, via a second link, a response frame including first information corresponding to a first link. The first information includes a first ID for the first link. The response frame further includes information regarding power for the first link. The communication method.