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

Technical Field

[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 in Japan on July 1, 2020, the content of which is incorporated herein by reference.

Background Art

[0002] IEEE802.11ax, which realizes further high-speedization of IEEE802.11, a wireless LAN (Local Area Network) standard, is being standardized by IEEE (The Institute of Electrical and Electronics Engineers Inc.), and wireless LAN devices compliant with the specification draft have appeared on the market. Currently, as a successor standard to IEEE802.11ax, the standardization activity of IEEE802.11be has been started. With the rapid spread of wireless LAN devices, in the standardization of IEEE802.11be as well, consideration is being given to further improving the throughput per user in an overcrowded environment of wireless LAN devices.

[0003] In a wireless LAN, frame transmission can be performed using an unlicensed band in which wireless communication can be carried out without permission (license) from a country or region. Currently widely used unlicensed band frequencies are the 2.4 GHz band and the 5 GHz band. The 2.4 GHz band can achieve relatively wide coverage, but is greatly affected by interference between communication devices and also cannot achieve a wide communication bandwidth. On the other hand, the 5 GHz band can achieve a wide communication bandwidth, but cannot achieve wide coverage. Therefore, in order to realize various services and applications with a wireless LAN, it is necessary to appropriately switch the frequency band to be used. However, in conventional wireless LAN devices, in order to switch the frequency band used for communication, it was necessary to disconnect the current connection once.

[0004] Therefore, in the IEEE 802.11be standardization, discussions have been held regarding Multi-link Operation (MLO), which enables communication devices to maintain multiple connections (links) (see Non-Patent Document 1). According to Multi-link Operation, a communication device can maintain multiple connections with different wireless resources and communication settings. In other words, by using Multi-link Operation, a communication device can simultaneously maintain connections on different frequency bands, making it possible to change the frequency band to which frames are transmitted without performing a reconnection operation. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] IEEE 802.11-20 / 0115-04, Jan.2020. [Overview of the project] [Problems that the invention aims to solve]

[0006] However, using multiple connection operations means that the target communication area becomes wider in terms of surface area. Therefore, in terminal-dense environments with a large number of communication devices, the effects of surrounding interference become significant, 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 view 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 using multiple connections in a terminal-dense environment where there are many communication devices. [Means for solving the problem]

[0008] An access point device, a station device, and a communication method according to one aspect of the present invention for solving the above-mentioned problems 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, comprising: a receiving unit that receives a first frame containing information associated with the second connection in the first connection; and a transmitting unit that determines whether or not to transmit a second frame in the second connection using the first frame.

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

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

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

[0013] (5) In addition, an access point device according to one aspect of the present invention is as described in (4) above, wherein the destination of the first frame is a plurality of station devices.

[0014] (6) Another station device according to one aspect of the present invention is a station device that maintains a first connection and a second connection, comprising: a transmitting unit that transmits a first frame containing information associated with the second connection in the first connection; and a receiving unit that receives a frame in the second connection after the transmitting unit has transmitted the first frame.

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

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

[0017] (9) Another 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 the steps of: receiving a first frame containing information associated with the second connection based on the first connection; and determining, based on the first frame, whether or not to transmit a second frame based on the second connection. [Effects of the Invention]

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

Brief Description of the Drawings

[0019] [Figure 1] It is a diagram showing an example of a frame configuration according to one aspect of the present invention. [Figure 2] It is a diagram showing an example of a frame configuration according to one aspect of the present invention. [Figure 3] It is a diagram showing an example of communication according to one aspect of the present invention. [Figure 4] It is a schematic diagram showing an example of the division of a wireless medium according to one aspect of the present invention. [Figure 5] It is a diagram showing an example of a configuration of a communication system according to one aspect of the present invention. [Figure 6] It is a block diagram showing an example of a configuration of a wireless communication device according to one aspect of the present invention. [Figure 7] It is a block diagram showing an example of a configuration of a wireless communication device according to one aspect of the present invention. [Figure 8] It is a schematic diagram showing an example of an encoding method according to one aspect of the present invention. [Figure 9] It is a diagram showing an example of communication according to one aspect of the present invention. [Figure 10] It is a diagram showing an example of communication according to one aspect of the present invention. [Figure 11] It is a diagram showing an example of communication according to one aspect of the present invention. [Figure 12] It is a diagram showing an example of communication according to one aspect of the present invention.

Modes for Carrying Out the Invention

[0020] The communication system in this embodiment comprises a wireless transmitting device (access point device, base station device) and a plurality of wireless receiving devices (station device, terminal device). The network composed of the base station device and terminal devices is called a basic service set (BSS). Furthermore, the station device in this embodiment may have the functions of an access point device. Similarly, the access point device in this embodiment may have the functions of a station device. Therefore, in the following, when simply referring to a communication device, it can refer to both a station device and an access point device.

[0021] The base station equipment and terminal equipment within the BSS shall communicate based on CSMA / CA (Carrier sense multiple access with collision avoidance). In this embodiment, the infrastructure mode in which the base station equipment communicates with multiple terminal equipment is targeted, but the method of this embodiment can also be implemented in ad-hoc mode in which terminal equipment communicates directly with each other. In ad-hoc mode, terminal equipment takes the place of the base station equipment and forms the BSS. The BSS in ad-hoc mode is also called IBSS (Independent Basic Service Set). In the following, terminal equipment that forms the IBSS in ad-hoc mode can also be considered as base station equipment.

[0022] In an IEEE 802.11 system, each device can transmit multiple frame types of transmit frames that share a common frame format. Transmit frames are defined at the Physical (PHY) layer, the Medium Access Control (MAC) layer, and the Logical Link Control (LLC) layer, respectively.

[0023] The transmission frame of the PHY layer is called a Physical Protocol Data Unit (PPDU: PHY protocol data unit, physical layer frame). A PPDU consists of a Physical Layer Header (PHY header) which contains header information for signal processing at the physical layer, and a Physical Service Data Unit (PSDU: PHY service data unit, MAC layer frame), which is a data unit processed at the physical layer. A PSDU can be composed of an Aggregated MPDU (A-MPDU), which is an aggregate of multiple MAC Protocol Data Units (MPDUs: MAC protocol data units) that serve as retransmission units in the wireless section.

[0024] PPDU is modulated according to the corresponding standard. For example, under the IEEE 802.11n standard, it is modulated into an orthogonal frequency division multiplexing (OFDM) signal.

[0025] The PHY header contains reference signals such as the Short Training Field (STF), used for signal detection and synchronization, and the Long Training Field (LTF), used to acquire channel information for data demodulation, as well as control signals such as the Signal (SIG), which contains control information for data demodulation. Furthermore, STFs are classified according to the corresponding standard into categories such as 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). Similarly, LTFs and SIGs are classified into L-LTF, HT-LTF, VHT-LTF, HE-LTF, L-SIG, HT-SIG, VHT-SIG, HE-SIG, and EHT-SIG. VHT-SIG is further classified into VHT-SIG-A1, VHT-SIG-A2, and VHT-SIG-B. Similarly, HE-SIG is classified into HE-SIG-A1 to HE-SIG-A4 and HE-SIG-B. In addition, a Universal SIGNAL (U-SIG) field containing additional control information may be included to accommodate technical updates within the same standard.

[0026] The SIG may include information for demodulating the received frame, such as information indicating the modulation scheme and coding rate (MCS), spatial data multiplexing (number of layers), number of spatial multiplexing users, information indicating whether or not spatiotemporal coding is performed (for example, information indicating whether or not spatiotemporal coding transmission diversity is performed), 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 that identifies the BSS that originated from the transmitted frame (hereinafter also referred to as BSS identification information). This BSS identification information may be, for example, the SSID (Service Set Identifier) ​​of the BSS or the MAC address of the base station device of the BSS. Alternatively, the BSS identification information may be a value unique to the BSS other than the SSID or MAC address (for example, the BSS Color).

[0028] Furthermore, since the PHY header, including the SIG, contains information necessary for data demodulation, it is desirable that it 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 with poor communication environments, it is desirable that the PHY header, especially the SIG, be configured with a highly redundant modulation scheme and coding rate. For example, a communication device can configure the PHY header with a low modulation level, such as BPSK modulation, and a low coding rate.

[0029] An MPDU consists of a MAC layer header (MAC header) containing 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 into an aggregated MSDU (A-MSDU).

[0030] MAC layer transmission frames 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 of these is further classified into multiple subframe types. Control frames include Acknowledge (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 included in the MAC header.

[0031] Note that Ack may include Block Ack. Block Ack can send reception completion notifications to multiple MPDUs.

[0032] A beacon frame contains fields that indicate the beacon transmission interval and the SSID. Base station equipment can periodically broadcast beacon frames within the Base Station Service Station (BSS), and terminal equipment can identify nearby base station equipment by receiving these beacon frames. When terminal equipment identifies base station equipment based on beacon frames broadcast by base station equipment, this is called passive scanning. On the other hand, when terminal equipment searches for base station equipment by broadcasting a probe request frame within the BSS, this is called active scanning. Base station equipment can transmit a probe response frame in response to the probe request frame, and the contents of the probe response frame are equivalent to those of the beacon frame.

[0033] After recognizing the base station device, the terminal device initiates a connection process to the base station device. The connection process is classified into authentication and association procedures. The terminal device sends an authentication frame (authentication request) to the base station device it wishes to connect to. Upon receiving the authentication frame, the base station device sends an authentication frame (authentication response) to the terminal device, which includes a status code indicating whether or not authentication was granted to the terminal device. By reading the status code in the authentication frame, the terminal device can determine whether or not it has been authorized to authenticate by the base station device. Note that the base station device and the terminal device can exchange authentication frames multiple times.

[0034] Following the authentication procedure, the terminal device sends a connection request frame to the base station device to initiate the connection procedure. Upon receiving the connection request frame, the base station device determines whether to allow the connection from the terminal device and sends a connection response frame to notify the terminal device of this decision. The connection response frame contains a status code indicating whether the connection process was successful or not, as well as an Association Identifier (AID) to identify the terminal device. The base station device can manage multiple terminal devices by assigning a different AID to each terminal device for which it has granted connection permission.

[0035] After the connection process is completed, the base station equipment and terminal equipment perform actual data transmission. The IEEE 802.11 system defines a Distributed Coordination Function (DCF), a Point Coordination Function (PCF), and extended mechanisms such as Enhanced Distributed Channel Access (EDCA) and Hybrid Coordination Function (HCF). The following explanation will use the case where the base station equipment transmits a signal to the terminal equipment using DCF as an example.

[0036] In DCF, base station and terminal equipment perform carrier sense (CS) to check the usage status of radio channels around their devices prior to communication. For example, if a base station (transmitting station) receives a signal higher than a predetermined clear channel assessment level (CCA level) on a radio channel, it will postpone the transmission of the transmission frame on that radio channel. In the following, the state in which a signal of CCA level or higher is detected on the radio channel will be called the busy state, and the state in which no signal of CCA level or higher is detected will be called the idle state. This CS, performed by each device based on the power of the signal actually received (received power level), is called physical carrier sense (physical CS). The CCA level is also called the carrier sense level (CS level) or CCA threshold (CCAT). When base station and terminal equipment detect a signal of CCA level or higher, they will at least begin the operation of demodulating the PHY layer signal.

[0037] In the following, when we simply refer to "carrier sense," we include cases where virtual carrier sense, as described later, is implemented. Also, in the following, when we simply refer to "carrier sense level," we also include cases where it 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 it observes a received signal power of the frame that is equal to or greater than the minimum receiving sensitivity, it is necessary to demodulate at least the PHY layer signal for that frame. This means that if the communication device observes a received signal power below the minimum receiving sensitivity, it is not necessary to demodulate the frame, and the communication device can attempt to transmit the frame. Therefore, carrier sense level and minimum receiving sensitivity can be considered to have the same meaning.

[0038] Base station equipment performs carrier sensing on transmitted frames for a frame interval (IFS: Inter frame space) appropriate to the type of frame to determine whether the radio channel is busy or idle. The duration of carrier sensing by the base station equipment varies depending on the frame type and subframe type of the transmitted frame that the base station equipment will transmit. In the IEEE 802.11 system, multiple IFSs with different durations are defined, including the short frame interval (SIFS: Short IFS) used for the highest priority transmitted frames, the polling frame interval (PCF IFS: PIFS) used for relatively high priority transmitted frames, and the distributed control frame interval (DCF IFS: DIFS) used for the lowest priority transmitted frames. When base station equipment transmits data frames using DCF, the base station equipment uses DIFS.

[0039] After waiting for DIFS, the base station equipment waits for an additional random backoff time to prevent frame collisions. In IEEE 802.11 systems, a random backoff time called the Contention window (CW) is used. CSMA / CA assumes that a transmission frame sent by one transmitting station is received by a receiving station without interference from other transmitting stations. Therefore, if transmitting stations send transmission frames at the same time, the frames will collide, and the receiving station will not be able to receive them correctly. To avoid this, each transmitting station waits for a randomly set time before starting to transmit, thus preventing frame collisions. When the base station equipment determines through carrier sense that the radio channel is idle, it starts a CW countdown, and only when the CW countdown reaches 0 does it acquire the right to transmit and send a transmission frame to the terminal device. If the base station equipment determines through carrier sense that the radio channel is busy during the CW countdown, it stops the CW countdown. Then, when the radio channel becomes idle, following the IFS, the base station equipment resumes the remaining CW countdown.

[0040] The receiving terminal device receives the transmission frame, reads the PHY header of the transmission frame, and demodulates the received transmission frame. The terminal device can then read the MAC header of the demodulated signal to determine whether the transmission frame is addressed to itself. The terminal device can also determine the destination of the transmission frame based on the information contained in the PHY header (for example, the group identifier (GID) listed in VHT-SIG-A).

[0041] If a terminal device determines that a received transmission frame is intended for itself and has successfully demodulated the frame without error, it must send an ACK frame to the base station (the transmitting station) to indicate that the frame was received correctly. The ACK frame is one of the highest-priority transmission frames and is sent only during the SIFS period (without any random backoff time). The base station terminates the communication series upon receiving the ACK frame from the terminal device. If the terminal device fails to receive the frame correctly, it will not send an ACK. Therefore, if the base station does not receive an ACK frame from the receiving station within a certain period (SIFS + ACK frame length) after transmitting the frame, it considers the communication to have failed and terminates the communication. Thus, the termination of a single communication (also called a burst) in an IEEE 802.11 system is always determined by the presence or absence of an ACK frame, except in special cases such as the transmission of broadcast signals like beacon frames or when fragmentation is used to divide the transmitted data.

[0042] If a terminal device determines that a received transmission frame is not intended for itself, it sets a Network Allocation Vector (NAV) based on the length of the transmission frame as described in the PHY header, etc. The terminal device does not attempt communication for the period set in the NAV. In other words, the terminal device performs the same action as if the physical CS had determined that the wireless channel was busy for the period set in the NAV, so communication control by NAV is also called virtual carrier sense (virtual CS). In addition to being set based on the information described in the PHY header, the NAV is also set by Request to Send (RTS) frames and Clear to Send (CTS) frames, which are introduced to resolve the hidden terminal problem.

[0043] In DCF, each device performs carrier sensing and autonomously acquires transmission rights, whereas in PCF, a control station called a Point Coordinator (PC) controls the transmission rights of each device within the BSS. Generally, the base station device acts as the PC and acquires the transmission rights of the terminal devices within the BSS.

[0044] The PCF communication period includes a Contention-Free Period (CFP) and a Contention Period (CP). During the CP, communication is conducted based on the DCF described above, and the PC controls the transmission right only during the CFP. The base station equipment, which is the PC, broadcasts a beacon frame containing the CFP duration (CFP Max duration), etc., into the BSS prior to PCF communication. PIFS is used to transmit the beacon frame broadcast at the start of PCF transmission, and it is transmitted without waiting for CW. Upon receiving the beacon frame, the terminal equipment sets the CFP duration described in the beacon frame to the NAV. Thereafter, until the NAV has elapsed or a signal (e.g., a data frame containing CF-end) broadcasting the end of the CFP into the BSS is received, the terminal equipment can only acquire transmission right if it receives a signal (e.g., a data frame containing CF-poll) from the PC signaling the acquisition of transmission right. Furthermore, since packet collisions do not occur within the same BSS during the CFP period, 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). Figure 4 is a schematic diagram showing one example of a wireless medium division state. For example, in resource division example 1, the wireless communication device can divide the frequency resource (subcarrier, frequency tone, tone), which is the wireless medium, into 9 RUs. Similarly, in resource division example 2, the wireless communication device can divide the subcarrier, which is the wireless medium, into 5 RUs. Of course, the resource division examples shown in Figure 4 are just examples, and for example, multiple RUs can be composed of different numbers of subcarriers. In addition, the wireless medium divided into RUs can include not only frequency resources but also spatial resources. A wireless communication device (e.g., AP) can transmit frames to multiple terminal devices (e.g., multiple STAs) simultaneously by placing frames destined for different terminal devices in each RU. The AP can include information indicating the state of wireless medium division (resource allocation information) as common control information in the PHY header of the frames it transmits. Furthermore, the AP can include resource unit assignment information (resource unit assignment information) indicating the RU to which each frame destined for each STA is located, as unique control information, in the PHY header of the frame it transmits.

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

[0047] An AP can simultaneously assign multiple RUs to a single STA. These multiple RUs may consist of consecutive subcarriers or discontinuous subcarriers. The AP can transmit a single frame using the multiple RUs assigned to a single STA, or it can transmit multiple frames, each assigned to a different RU. At least one of these multiple frames may be a frame containing common control information for multiple terminal devices transmitting resource allocation information.

[0048] A single STA can be assigned multiple RUs from an AP. The STA can use the assigned RUs to transmit a single frame. Alternatively, the STA can use the assigned RUs to transmit multiple frames, each assigned to a different RU. These multiple frames can each be of a different frame type.

[0049] An AP can assign multiple AIDs (Association IDs) to a single STA. An AP can assign a RU (Ruler) to each of the multiple AIDs assigned to a single STA. Using the assigned RUs, the AP can transmit different frames to each of the multiple AIDs assigned to a single STA. These different frames can be of different frame types.

[0050] A single STA can be assigned multiple AIDs (Associate IDs) by an AP. A single STA can be assigned a RU (Ruler Unit) to each of the multiple AIDs it has been assigned. An STA recognizes all the RUs assigned to each of the multiple AIDs assigned to it as RUs assigned to itself, and can transmit a single frame using these assigned RUs. Furthermore, an STA can transmit multiple frames using these assigned RUs. In this case, each of these multiple frames can contain information indicating the AID associated with its assigned RU. An AP can transmit different frames to each of the multiple AIDs assigned to a single STA using the assigned RUs. These different frames can be of different frame types.

[0051] Hereafter, base station equipment and terminal equipment will be collectively referred to as wireless communication equipment or communication equipment. Furthermore, the information exchanged when one wireless communication device communicates with another will be referred to as data. In other words, wireless communication equipment includes both base station equipment and terminal equipment.

[0052] A wireless communication device has either the function to transmit PPDUs, the function to receive them, or both. Figure 1 shows an example of a PPDU configuration transmitted by a wireless communication device. A PPDU compliant with the IEEE 802.11a / b / g standard includes L-STF, L-LTF, L-SIG, and a Data frame (MAC Frame, MAC frame, payload, data section, data, information bits, etc.). A PPDU compliant with the IEEE 802.11n standard includes L-STF, L-LTF, L-SIG, HT-SIG, HT-STF, HT-LTF, and a Data frame. A PPDU compliant with the IEEE 802.11ac standard includes L-STF, L-LTF, L-SIG, VHT-SIG-A, VHT-STF, VHT-LTF, VHT-SIG-B, and some or all of a MAC frame. The PPDU considered in the IEEE 802.11ax standard is a configuration that includes L-STF, L-LTF, L-SIG, RL-SIG (a temporally repeated L-SIG), HE-SIG-A, HE-STF, HE-LTF, HE-SIG-B, and some or all of the Data frames. The PPDU considered in the IEEE 802.11be standard is a configuration that includes L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, HET-LTF, and some or all of the Data frames.

[0053] The L-STF, L-LTF, and L-SIG enclosed by the dotted lines in Figure 1 are configurations commonly used in the IEEE 802.11 standard (hereinafter, L-STF, L-LTF, and L-SIG will be collectively referred to as L-headers). For example, a wireless communication device compliant with the IEEE 802.11a / b / g standard can properly receive the L-header in a PPDU compliant with the IEEE 802.11n / ac standard. A wireless communication device compliant with the IEEE 802.11a / b / g standard can receive a PPDU compliant with the IEEE 802.11n / ac standard as if it were a PPDU compliant with the IEEE 802.11a / b / g standard.

[0054] However, wireless communication devices compliant with the IEEE 802.11a / b / g standards cannot demodulate the PPDU compliant with the IEEE 802.11n / ac standards that follows the L-header. Therefore, they cannot demodulate information related to the Transmission Address (TA), Receiver Address (RA), and the Duration / ID field used for NAV settings.

[0055] IEEE 802.11 specifies a method for inserting Duration information into the L-SIG as a way for wireless communication devices compliant with the IEEE 802.11a / b / g standards to properly set NAV (or perform receiving operations for a predetermined period). The transmission speed information (RATE field, L-RATE field, L-RATE, L_DATARATE, L_DATARATE field) and transmission duration information (LENGTH field, L-LENGTH field, L-LENGTH) within the L-SIG are used by wireless communication devices compliant with the IEEE 802.11a / b / g standards to properly set NAV.

[0056] Figure 2 shows an example of how Duration information is inserted into the L-SIG. While Figure 2 shows a PPDU configuration corresponding to the IEEE 802.11ac standard as an example, the PPDU configuration is not limited to this. PPDU configurations corresponding to the IEEE 802.11n standard and IEEE 802.11ax standard are also acceptable. TXTIME contains information about the length of the PPDU, aPreambleLength contains information about the length of the preamble (L-STF + L-LTF), and aPLCPHeaderLength contains information about the length of the PLCP header (L-SIG). L_LENGTH is a virtual period set to maintain 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 contained in the PLCP Service field, and aPLCPConvolutionalTailLength, which indicates the number of tail bits of the convolutional code. The radio communication device can calculate L_LENGTH and insert it into L-SIG. The radio communication device can also calculate L-SIG Duration. L-SIG Duration indicates information about the duration of the PPDU containing L_LENGTH and the sum of the duration of the Ack and SIFS that are expected to be transmitted from the destination radio communication device in response.

[0057] Figure 3 shows an example of L-SIG Duration in L-SIG TXOP Protection. DATA (frame, payload, data, etc.) consists of the MAC frame and part or both of the PLCP header. BA is either Block Ack or Ack. PPDU includes L-STF, L-LTF, and L-SIG, and can also include DATA, BA, RTS, or CTS, or one or more of them. The example shown in Figure 3 uses RTS / CTS for L-SIG TXOP Protection, but CTS-to-Self may also be used. Here, MAC Duration is the period indicated by the value in the Duration / ID field. The Initiator can also send a CF_End frame to notify the end of the L-SIG TXOP Protection period.

[0058] Next, a method for identifying the BSS from a frame received by a wireless communication device will be described. In order for a wireless communication device to identify the BSS from a frame received, it is preferable for the wireless communication device transmitting the PPDU to insert information for identifying the BSS (BSS color, BSS identification information, and a value unique to the BSS) into the PPDU. Information indicating the BSS color can be described in HE-SIG-A.

[0059] A wireless communication device can transmit an L-SIG multiple times (L-SIG Repetition). For example, a receiving wireless communication device can improve the demodulation accuracy of the L-SIG by receiving multiple L-SIGs using MRC (Maximum Ratio Combining). Furthermore, if the wireless communication device successfully receives the L-SIG using MRC, it can interpret the PPDU containing the L-SIG as a PPDU compliant with the IEEE 802.11ax standard.

[0060] A wireless communication device can receive parts of a PPDU other than the PPDU itself (for example, the preamble, L-STF, L-LTF, PLCP header, etc. as defined by IEEE 802.11) even while receiving a PPDU (this is also called dual reception). If the wireless communication device detects parts of a PPDU other than the PPDU while receiving a PPDU, it can update some or all of the destination address, source address, and information regarding the PPDU or DATA period.

[0061] Ack and BA can also be referred to as responses (response frames). Furthermore, probe responses, authentication responses, and connection responses can also be referred to as responses. [1. First Embodiment]

[0062] Figure 5 shows an example of a wireless communication system according to this embodiment. Wireless communication system 3-1 includes wireless communication device 1-1 and wireless communication devices 2-1 to 2-4. Wireless communication device 1-1 is also referred to as base station device 1-1, and wireless communication devices 2-1 to 2-4 are also referred to as terminal devices 2-1 to 2-4. Wireless communication devices 2-1 to 2-4 and terminal devices 2-1 to 2-4 are also referred to as wireless communication device 2A and terminal device 2A, respectively, as devices connected to wireless communication device 1-1. Wireless communication device 1-1 and wireless communication device 2A are wirelessly connected and are in a state where they can send and receive PPDU to and from each other. In addition to wireless communication system 3-1, the wireless communication system according to this embodiment also includes wireless communication system 3-2. Wireless communication system 3-2 includes wireless communication device 1-2 and wireless communication devices 2-5 to 2-8. Wireless communication device 1-2 is also referred to as base station device 1-2, and wireless communication devices 2-5 to 2-8 are also referred to as terminal devices 2-5 to 2-8. Furthermore, wireless communication devices 2-5 to 2-8 and terminal devices 2-5 to 2-8 are also referred to as wireless communication device 2B and terminal device 2B, respectively, as devices connected to wireless communication device 1-2. Although wireless communication systems 3-1 and 3-2 form different BSSs, this does not necessarily mean that they have different ESSs (Extended Service Sets). An ESS represents 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 perspective. Note that wireless communication systems 3-1 and 3-2 may also be equipped with multiple wireless communication devices.

[0063] In Figure 5, for the following explanation, it is assumed that the signal transmitted by wireless communication device 2A reaches wireless transmitter 1-1 and wireless communication device 2B, but does not reach wireless communication device 1-2. That is, when wireless communication device 2A transmits a signal using a certain channel, wireless communication device 1-1 and wireless communication device 2B determine that the channel is busy, while wireless communication device 1-2 determines that the channel is idle. Also, it is assumed that the signal transmitted by wireless communication device 2B reaches wireless transmitter 1-2 and wireless communication device 2A, but does not reach wireless communication device 1-1. That is, when wireless communication device 2B transmits a signal using a certain channel, wireless communication device 1-2 and wireless communication device 2A determine that the channel is busy, while wireless communication device 1-1 determines that the channel is idle.

[0064] Figure 6 shows 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 includes a higher layer section (higher layer processing step) 10001-1, an autonomous distributed control section (autonomous distributed control step) 10002-1, a transmitting section (transmitting step) 10003-1, a receiving section (receiving step) 10004-1, and an antenna section 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. Traffic information may be, for example, information addressed to other wireless communication devices, or control information contained in management frames or control frames.

[0066] Figure 7 shows an example of the device configuration of the autonomous distributed control unit 10002-1. The autonomous distributed control unit 10002-1 includes a CCA unit (CCA step) 10002a-1, a backoff unit (backoff step) 10002b-1, and a transmission decision unit (transmission decision step) 10002c-1.

[0067] The CCA unit 10002a-1 can determine the status of a radio resource (including whether it is busy or idle) using either or both of the information notified by the receiving unit regarding the received signal power received via the radio resource and / or information regarding the received signal (including the decoded information). The CCA unit 10002a-1 can notify the backoff unit 10002b-1 and the transmission determination unit 10002c-1 of the status determination information of the radio resource.

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

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

[0070] The transmission unit 10003-1 includes a physical layer frame generation unit (physical layer frame generation step) 10003a-1 and a wireless transmission unit (wireless transmission step) 10003b-1. The physical layer frame generation 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 generation unit 10003a-1 applies error correction coding, modulation, pre-recording filter multiplication, etc., to the transmission frame sent from the upper layer. The physical layer frame generation unit 10003a-1 notifies the wireless transmission unit 10003b-1 of the generated physical layer frame.

[0071] Figure 8 shows an example of error correction coding in the physical frame generation unit according to this embodiment. As shown in Figure 8, the shaded area contains the information bit (systematic bit) sequence, and the open area contains the redundant (parity) bit sequence. Bit interleavers are appropriately applied to both the information bits and the redundant bits. The physical frame generation unit can read the required number of bits from the arranged bit sequence as the starting position, which is determined according to the value of the redundancy version (RV). By adjusting the number of bits, flexible changes in the coding rate, i.e., puncturing, become possible. In Figure 8, there are four possible RV values, but in the error correction coding according to this embodiment, the RV selection is not limited to a specific value. The RV position needs to be shared among the station devices.

[0072] The physical layer frame generation unit applies error correction coding to the information bits transmitted from the MAC layer, but the unit in which error correction coding is applied (coded block length) is not limited to any particular value. For example, the physical layer frame generation unit can divide the information bit sequence transmitted from the MAC layer into information bit sequences of a predetermined length, apply error correction coding to each, and create multiple coded blocks. Furthermore, when constructing coded blocks, dummy bits can be inserted into the information bit sequence transmitted from the MAC layer.

[0073] The frame generated by the physical layer frame generation unit 10003a-1 includes control information. This control information includes information indicating which RU (where RU includes both frequency resources and spatial resources) the data destined for each wireless communication device is located in. The frame generated by the physical layer frame generation unit 10003a-1 also includes a trigger frame that instructs the destination terminal wireless communication device to transmit the frame. This trigger frame includes information indicating the RU that the wireless communication device will use when transmitting the frame after being instructed to do so.

[0074] The wireless transmitter 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 transmitter 10003b-1 includes digital-to-analog conversion, filtering, and frequency conversion from the baseband band to the RF band.

[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 regarding the received signal power from the RF band signal received by the antenna unit 10005-1. The receiving unit 10004-1 can notify the CCA unit 10002a-1 of the information regarding the received signal power and the information regarding the received signal.

[0076] The wireless receiver unit 10004a-1 has the function of converting the 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 receiver unit 10004a-1 includes frequency conversion from the RF band to the baseband band, 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 receiver 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 from the physical layer signal, for example, information contained in the physical layer header, information contained in the MAC header, and information contained in the transmission frame. The signal demodulation unit 10004b-1 can notify the higher layer unit 10001-1 of the extracted information. The signal demodulation unit 10004b-1 can extract any or all of the information contained in the physical layer header, the MAC header, and the transmission frame.

[0078] The antenna unit 10005-1 has the function of transmitting the radio frequency signal generated by the radio transmission unit 10003b-1 to the radio device 0-1 in the radio space. The antenna unit 10005-1 also has the function of receiving the radio frequency signal transmitted from the radio device 0-1.

[0079] The wireless communication device 10-1 can cause surrounding wireless communication devices to set NAV for a specific period by including information indicating the period during which it 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 include information indicating the period in the Duration / ID field or Length field of the frame it transmits. The NAV period set in the surrounding wireless communication devices will be called the TXOP period (or simply TXOP) acquired by the wireless communication device 10-1. The wireless communication device 10-1 that acquired the TXOP will be called the 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; it may be a control frame (e.g., an RTS frame or a CTS-to-self frame) or a data frame.

[0080] A wireless communication device 10-1, which is a TXOP holder, can transmit frames to wireless communication devices other than itself within the TXOP. If wireless communication device 1-1 is a TXOP holder, wireless communication device 1-1 can transmit frames to wireless communication device 2A within the TXOP period. Also, wireless communication device 1-1 can instruct wireless communication device 2A to transmit frames addressed to wireless communication device 1-1 within the TXOP period. Wireless communication device 1-1 can transmit a trigger frame to wireless communication device 2A within the TXOP period that includes information instructing wireless communication device 2A to transmit frames addressed to wireless communication device 1-1.

[0081] The wireless communication device 1-1 may reserve a TXOP for the entire communication band where frame transmission may occur (e.g., Operation bandwidth), or it may reserve a TXOP for a specific communication band (Band), such as the communication band on which frames are actually transmitted (e.g., Transmission bandwidth).

[0082] The wireless communication device that issues a frame transmission instruction within the TXOP period acquired by wireless communication device 1-1 is not necessarily limited to wireless communication devices connected to itself. For example, a wireless communication device can instruct wireless communication devices not connected to itself to transmit frames in order to have wireless communication devices in its vicinity transmit management frames such as Reassociation frames or control frames such as RTS / CTS frames.

[0083] In this embodiment, the signal demodulation unit of the station device can perform decoding and error detection on the received signal at the physical layer. Here, the decoding process includes decoding of the error correction code applied to the received signal. Here, error detection includes error detection using an error detection code (e.g., cyclic redundancy check (CRC) code) that is pre-assigned to the received signal, or error detection using an error correction code (e.g., low-density parity check (LDPC)) that has an inherent error detection function. The decoding process at the physical layer can be applied to each encoded block.

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

[0085] The communication device according to this embodiment can maintain multiple connections (links). Maintaining a connection means that frames can be transmitted and received based on predetermined settings. Figure 9 is a schematic diagram showing the communication according to this embodiment. As shown in Figure 9, the access point device 1-1 according to this embodiment can maintain connections between station device 2-1 and station device 2-2 using different carrier frequencies. For example, the access point device 1-1 according to this embodiment can set a frequency in the 2.4 GHz band for connection 9-1 with station device 2-1 and a frequency in the 5 GHz band for connection 9-2 with station device 2-2.

[0086] Figure 10 is a schematic diagram showing the communication process according to this embodiment. As shown in Figure 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 connection 10-1, and a frequency in the 5 GHz band can be set for connection 10-2. By setting it in this way, the access point device 1-1 can perform frame exchange with the station device 2-1 using two frequencies.

[0087] The communication device according to this embodiment can decide whether or not to transmit a frame using multiple connections depending on the state of the wireless medium. This can be achieved by efficiently transmitting frames.

[0088] Figure 11 is a schematic diagram showing the communication process according to this embodiment. In the example in Figure 11, the access point device and the station device can perform frame exchange using two connections, connection 10-1 (first connection) and connection 10-2 (second connection). Naturally, the method according to this embodiment also includes cases where the access point device maintains three or more connections. Here, the access point device first transmits a media reservation frame for each connection to reserve the wireless medium for a certain period of time. The media reservation frame contains information indicating the time interval for which the access point device reserves the wireless medium. In the example in Figure 11, the access point device transmits frames to reserve the wireless medium simultaneously for connection 10-1 and connection 10-2, but the method according to this embodiment is not limited to this. That is, the access point device can transmit frames to reserve the wireless medium at different timings for multiple connections. However, even in this case, it is desirable that the end of the period for which the frame to reserve the wireless medium reserves the wireless medium (end timing) be common to all of the multiple connections. This indicates that the time intervals reserved by the media reservation frames transmitted for each connection (information associated with the NAV described in the frame) may coincide, but may also differ.

[0089] The medium reservation frame is not limited to any particular type. For example, an access point device can send a Request to Send (RTS) frame for each connection as the frame for reserving the wireless medium. An access point device can also send a Multi-User RTS (MU-RTS) frame, which is an RTS frame addressed to multiple users. Furthermore, an access point device can send a trigger frame as the frame for reserving the wireless medium, which triggers a response frame (a first response frame) from the station device. The following explanation will use the case where an access point device sends an RTS frame as the frame for reserving the wireless medium as an example.

[0090] When a station device receives an RTS frame transmitted by an access point device at each connection, it decides whether or not to transmit a first response frame (first frame) based on the state of the wireless medium at the connection that received the RTS frame. For example, if the station device determines that the wireless medium that received the RTS frame is idle, it transmits a Clear to send (CTS) frame as the first response frame at the connection that received the RTS frame. On the other hand, if the station device determines that the wireless medium at the connection that received the RTS frame is busy, it does not transmit a CTS frame at that connection. Note that the first response frame transmitted by the station device is not limited to a CTS frame. The station device can also transmit a control frame, management frame, or data frame as the first response frame, which is different from a CTS frame. However, it is desirable for the station device to include information in the first response frame indicating that it is a frame that the access point device has moved. The access point device can also instruct the station device on the information to include in the first response frame.

[0091] When an access point device receives a CTS frame, it determines that it has secured the wireless medium for that connection and can transmit a frame. On the other hand, when it does not receive a CTS frame, it determines that it has not secured the wireless medium for that connection and does not transmit a frame. With conventional communication devices, wireless medium can be secured accurately between communication devices by exchanging RTS frames and CTS frames between them. If an access point device is able to transmit an RTS frame but does not receive a CTS frame, it 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 the BSS managed by a different access point device. If the station device has determined that the wireless medium is busy based on an OBSS frame, the station device cannot attempt to transmit a frame, but it may be able to perform a frame reception operation on the wireless medium.

[0092] Therefore, in the case where the station device according to this embodiment receives RTS frames in multiple connections and can transmit a CTS frame as a response frame in at least one connection, the CTS frame may include information indicating the state of the wireless media of connections other than the one transmitting the CTS frame. In the following description, the case in which the station device transmits a CTS frame as a response frame is used as an example, but the type of frame that includes information indicating the state of the wireless media of connections other than the one transmitting the frame is not limited to a CTS frame. It may also be a control frame, management frame, or data frame other than a CTS frame. However, it goes without saying that the response frame must contain information that allows the access point device and the station device that receive the response frame to recognize that the response frame includes information indicating the state of the wireless media of connections other than the one 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 the station device by the modulation scheme and signal point arrangement applied to the response frame.

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

[0094] Information indicating the state of the wireless medium can include information indicating interference power at each connection. Here, information indicating interference power includes the Received Signal Strength Indicator (RSSI) and the Received Channel Power Indicator (RCPI). Furthermore, information indicating interference power includes information indicating the received power of the legacy header portion of the frame received by the station device at the connection. The legacy header portion includes at least a portion of the L-STF, L-LTF, and L-SIG. The station device can also notify the access point device of the difference between the desired received power at the second connection and the received power of the header portion of the medium-reserved frame received at the second connection.

[0095] Returning to Figure 11, when an access point device receives a CTS frame containing information indicating the wireless medium information of connection 10-2 at connection 10-1, after a predetermined period of time has elapsed, it can decide whether or not to transmit a frame (second frame) to the station device at connection 10-1, while using the information indicating the wireless medium information of connection 10-2 to decide whether or not to transmit a frame to the station device at connection 10-2.

[0096] For example, if the information of the wireless medium in 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 a frame in connection 10-2. As explained earlier, if the frame that caused the station device to determine that the wireless medium in connection 10-2 was busy was an OBSS frame, the station device is highly likely to be able to receive the frame even if it cannot transmit it. Naturally, the received signal-to-interference power ratio (SIR) of the frame transmitted by the access point device in connection 10-2 is likely to decrease due to the OBSS frame, but by appropriately setting the modulation scheme and coding rate applied to the frame, the access point device can enable the station device to correctly receive the frame received in connection 10-2.

[0097] For example, if the information on the wireless medium of connection 10-2 is information indicating the interference power measured by the station device at connection 10-2, the access point device can transmit a frame at connection 10-2 if the station device can achieve the desired reception quality at connection 10-2.

[0098] In both connection 10-1 and connection 10-2, the station device that receives a frame transmits a response frame (second response frame) resulting from that frame. For example, the station device demodulates each frame in both connection 10-1 and connection 10-2 and performs error detection. Then, it transmits an ACK frame containing information indicating whether or not the frame was received correctly as the second response frame to the access point device. In this case, it is undesirable for the station device to transmit the second response frame in connection 10-2, where the OBSS frame indicates that the wireless medium is busy. Therefore, the station device can transmit the second response frame resulting from the frame received in connection 10-2 in connection 10-1. Alternatively, the station device can include the information contained in the second response frame resulting from the frame received in connection 10-2 into the second response frame resulting from the frame received in connection 10-1, and then transmit it in connection 10-1. Thus, even when the information contained in the second response frame caused by the frame received at connection 10-2 is included in the second response frame caused by the frame received at connection 10-1, and then transmitted at connection 10-1, it may also be described as the station device transmitting the second response frame at connection 10-1.

[0099] When the station device receives a frame at connection 10-2, it can decide whether or not to update the NAV. When the station device receives a frame from the access point device at connection 10-2, it can choose not to update inter-NAV and Basic NAV. Also, the station device can choose not to transmit frames during the time interval in which it is transmitting the second response frame at connection 10-1. In other words, when the station device receives a frame from the access point device at connection 10-2, it performs demodulation processing of the frame, but if inter-NAV or Basic NAV expires while receiving the frame, the station device can update the NAV at connection 10-1 during the time interval until it has finished transmitting the second response frame.

[0100] The access point device may include information indicating the connection to which it will transmit a second response frame to the station device in the PHY header or MAC header of the frame it transmits after receiving the first response frame.

[0101] As explained earlier, the connection to which the station device transmits the second response frame can be configured by the access point device, but it can also be configured by the station device. For example, the station device can transmit the second response frame to the same connection to which it transmitted the first response frame. If the station device has transmitted the first response frame to multiple connections, it may randomly select the connection to which it transmits the second response frame from among those connections, or it may select the connection with the lowest frequency. Furthermore, priorities can be set for multiple connections in advance, and the station device can transmit the second response frame to the connection with the highest priority.

[0102] The station device can directly include information about connections it cannot receive in the response frame to the media allocation frame transmitted by the access point device. Here, the connection information can be a channel number shared with the access point device. The access point device can also broadcast information about connections it maintains via beacon frames, etc., and can assign numbers (IDs) to the multiple connections it maintains. The station device can treat these numbers as connection information.

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

[0104] Furthermore, if the access point device performs carrier sensing when transmitting a media allocation frame, it is not necessarily required to perform carrier sensing when transmitting a frame in connection 10-2.

[0105] The station device can include multiple connection details in its response frame, and within each connection, it can include additional details. For example, if connection 10-2 is an 80MHz bandwidth channel, the station device can further divide the 80MHz channel into four 20MHz bands and, for each band, include information indicating the state of the wireless medium, such as the NAV status and received power status, 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 information indicating the state of the wireless medium. These fields include a field for information about each connection, and, if each connection has multiple channels, a field for information indicating the state of each wireless medium.

[0106] This control allows access point devices and station devices to efficiently exchange frames using multiple connections in dense environments where numerous access point and station devices exist, thereby improving system efficiency. [2. Second Embodiment]

[0107] The configuration of the access point device and station device constituting this embodiment is the same as in Embodiment 1.

[0108] Figure 12 is a schematic diagram showing the communication process according to this embodiment. In this embodiment, the access point device sets up connections that request response frames from the station device according to the status of the wireless media of multiple connections.

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

[0110] Therefore, the access point device transmits frames in connection 10-1 and connection 10-2, respectively, but does not expect the station device to transmit a response frame in connection 10-2. If the frame transmitted by the access point device in connection 10-2 is a frame that would trigger a response frame, the access point device can instruct the station device to transmit the response frame in connection 10-1, or to include the information contained in the response frame in the frame transmitted in connection 10-1.

[0111] The access point device knows that connection 10-2 is busy on the wireless medium based on the OBSS frame, and therefore can transmit a frame in accordance with the criteria for transmitting a frame on connection 10-2. On the other hand, the access point device cannot guarantee that it will correctly receive the frame transmitted by the station device on connection 10-2. Therefore, the access point device can notify the station device to transmit the response frame caused by the frame transmitted by the access point device on connection 10-2 on connection 10-1.

[0112] Furthermore, when an access point device transmits a frame using multiple connections, the wireless medium of at least one connection must be idle. In other words, if all of the multiple connections on which the access point device intends to transmit a frame are determined to have a busy wireless medium based on either an OBSS frame or a frame belonging to the BSS managed by the access point device, the access point device cannot transmit a frame even if there is a connection among the multiple connections that is determined to have a busy wireless medium due to an OBSS frame. To put it another way, if the access point device has a guarantee that it can receive a response frame transmitted from the station device on at least one of the multiple connections on which it transmits a frame, it can transmit a frame on a connection that is determined to have a busy wireless medium due to an OBSS frame. [3. Common to all embodiments]

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

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

[0115] A program that operates in a wireless communication device according to one aspect of the present invention is a program that controls the CPU and the like (a program that makes the computer function) in order to realize the functions of the above embodiment according to one aspect of the present invention. The information handled by these devices is temporarily stored in RAM during processing, and then stored in various ROMs or HDDs, and read, modified, and written by the CPU as needed. The recording medium for storing the program may be any of the following: semiconductor media (e.g., ROM, non-volatile memory card, etc.), optical recording medium (e.g., DVD, MO, MD, CD, BD, etc.), magnetic recording medium (e.g., magnetic tape, flexible disk, etc.). Furthermore, in addition to realizing the functions of the above embodiment by executing the loaded program, the functions of the present invention may also be realized by processing in cooperation with the operating system or other application programs, etc., based on the instructions of the program.

[0116] Furthermore, when distributing the program to the market, it can be stored on a portable recording medium and distributed, 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. In addition, some or all of the communication device in the above-described embodiment may be realized as an LSI, which is typically an integrated circuit. Each functional block of the communication device may be individually chipped, or some or all of them may be integrated into a single chip. When each functional block is made into an integrated circuit, an integrated circuit control unit is added to control them.

[0117] Furthermore, the method of implementing integrated circuits is not limited to LSIs; it may also be implemented using dedicated circuits or general-purpose processors. Additionally, if advancements in semiconductor technology lead to the emergence of integrated circuit technologies that can replace LSIs, it is possible to use integrated circuits based on those technologies.

[0118] Furthermore, the present invention is not limited to the embodiments described above. The wireless communication device of the present invention is not limited to application to mobile station equipment, but can also be applied to stationary or non-movable electronic devices installed indoors or outdoors, such as AV equipment, kitchen equipment, cleaning and washing machines, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0119] While embodiments of this invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and designs and the like that do not depart from the spirit of this invention are also included in the scope of the claims. [Industrial applicability]

[0120] One aspect of the present invention is suitable for use in access point devices, station devices, and communication methods. [Explanation of symbols]

[0121] 1-1, 1-2 Access Point Devices 2-1~8 Station Equipment 3-1, 3-2 Scope of Management 10001-1 Upper layer section 10002-1 Autonomous Distributed Control Unit 10002a-1 CCA Department 10002b-1 Back-off section 10002c-1 Transmission determination unit 10003-1 Transmitter 10003a-1 Physical layer frame generation unit 10003b-1 Wireless Transmitter 10004-1 Receiving Unit 10004a-1 Wireless Receiver 10004b-1 Signal demodulation section 10005-1 Antenna section

Claims

1. An access point device that uses multiple links, A receiving unit that receives a request frame corresponding to the first link on the first link, The system includes a transmitting unit that, upon receiving the aforementioned request frame, transmits a response frame containing second information corresponding to the second link over the first link, The second information includes a second ID for the second link. The response frame further includes information regarding power for the second link in the access point device.

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

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

4. A station device that uses multiple links, A transmitting unit that transmits a request frame corresponding to the first link over the first link, The system includes a receiving unit that, when the aforementioned request frame is transmitted, receives a response frame on the first link containing second information corresponding to the second link, The second information includes a second ID for the second link. The response frame further includes information regarding the power for the second link, in the station device.

5. The response frame includes information relating to the interference power of the second link, as described in claim 4. Station equipment.

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

7. A communication method for an access point device using multiple links, The steps include receiving a request frame corresponding to the first link on the first link, The process includes, upon receiving the request frame, transmitting a response frame containing second information corresponding to the second link on the second link, The second information includes a second ID for the second link. The response frame further includes information regarding the power for the second link, communication method.

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