JP2023130529A - Communication device and communication method - Google Patents

Abstract

To provide a communication device and a communication method that can achieve low-delay communication by improving the frame transmission/reception responsiveness of a wireless communication device that connects to a child access point device in a multi-AP wireless communication system.SOLUTION: In a multi-AP wireless communication system, when wireless communication is performed between wireless LAN access point devices, one data frame may be relayed from a wireless LAN access point 1-1 to a destination wireless LAN station device 2-2 via another wireless LAN access point device 1-2. The same data frame is transmitted twice over a wireless medium, consuming twice the wireless medium and slowing down the time it takes to complete receiving the data frame. To resolve this, the station device 2-2 connected to one of child access point devices 1-2 directly receives a data frame 12-1 that the parent access point device 1-1 transmits to the child access point device 1-2 and decodes it.SELECTED DRAWING: Figure 12

Description

The present invention relates to a communication device and a communication method.

IEEE802.11ax, which will further speed up the wireless LAN (Local Area Network) standard IEEE802.11, is being standardized by the IEEE (The Institute of Electrical and Electronics Engineers Inc.) and is compliant with the draft specification. Wireless LAN devices have appeared on the market. Currently, standardization activities for IEEE802.11be have been started as a successor standard to IEEE802.11ax. With the rapid spread of wireless LAN devices, in the IEEE802.11be standardization, studies are being conducted to further improve throughput per user in environments where wireless LAN devices are crowded.

In a wireless LAN, frames can be transmitted using an unlicensed band that allows wireless communication without requiring permission (license) from the country or region. For personal use such as at home, wireless LAN access point functionality may be included in a line termination device for connecting to a WAN (Wide Area Network) line to the Internet, or a wireless LAN access point device may be connected to a line termination device. As a result, internet access from within the residence has become wireless. In other words, a wireless LAN station device such as a smartphone or a PC (Personal Computer) can access the Internet by connecting to a wireless LAN access point device. When wireless LAN was first introduced into homes, there was often only one wireless LAN access point device in the residence, but these days, multiple wireless LAN access point devices are being introduced and The coverage of the wireless LAN area is being expanded. In particular, for personal use, a wireless LAN mesh network that wirelessly communicates between wireless LAN access point devices (backhaul) is preferred in order to simplify network construction. On the other hand, for enterprises, it is preferred that wireless LAN access point devices be connected by wire, such as Ethernet (registered trademark), in order to improve the reliability of frame transmission. However, there is a trade-off between communication performance and the complexity of equipment installation, so consider the balance and choose a wired or wireless connection between wireless LAN access point devices depending on the use case. may be determined.

Furthermore, in the IEEE802.11be standardization, discussions are underway regarding Multi-AP (Multi Access Point), in which multiple wireless LAN access point devices cooperate to transmit and receive frames to one wireless LAN station device (non-standard). (See Patent Document 1). In the prior art, basically, a wireless LAN access point device transmits a frame by considering only the wireless LAN station device connected to the wireless LAN access point device. However, the wireless LAN access point device in the Multi-AP wireless communication system operates in cooperation with other wireless LAN access point devices, and the wireless LAN station devices connected to other wireless LAN access point devices are also taken into account. You will be able to send frames. Wireless LAN access point devices in the prior art estimated propagation characteristics based on Channel Sounding only for wireless LAN station devices connected to the own device for beam forming, etc., but wireless LAN access point devices in Multi-AP wireless communication systems The access point device also needs to estimate the propagation characteristics based on Channel Sounding for wireless LAN station devices connected to other wireless LAN access point devices. As a result, the transmission and reception of management frames and control frames related to Channel Sounding increases.

IEEE 802.11-19/1578-01-0be, Nov. 2019.

Not only Channel Sounding but also various functions realized by Multi-AP increase the transmission and reception of management frames and control frames, which can also be said to increase the overhead for subsequent data frame transmission and reception. In particular, when wireless communication is performed between wireless LAN access point devices, for example, one data frame is relay transmitted from one wireless LAN access point to the destination wireless LAN station device via another wireless LAN access point device. Sometimes it is done. Simply put, the same data frame may be transmitted at least twice on the wireless medium, which means that the wireless medium is consumed twice and the time required for the wireless LAN station device to complete reception of the data frame is delayed. .

A communication device and a communication method according to the present invention for solving the above-mentioned problems are as follows.

(1) That is, a communication device according to one aspect of the present invention includes a parent access point device, one or more child access point devices connected to the parent access point device, and one or more child access point devices connected to the child access point device. In a network configured of station devices, a station device connected to one of the child access point devices receives a data frame transmitted by the parent access point device to the child access point device, and transmits the data frame to the child access point device. decrypt.

(2) Furthermore, the communication device according to one aspect of the present invention is described in (1) above, and decodes the data frame when a destination address of the data frame indicates the station device.

(3) Furthermore, the communication device according to one aspect of the present invention is described in (1) above, and after decoding the data frame, transmits a response frame to the child access point device.

(4) Furthermore, the communication device according to one aspect of the present invention is described in (1) above, and transmits a response frame to the parent access point device after decoding the data frame.

(5) A communication device according to one aspect of the present invention includes a parent access point device, one or more child access point devices connected to the parent access point device, and one or more stations connected to the child access point device. In a network configured of devices, the child access point device receives a data frame transmitted by the parent access point device and transfers it to the station device, and the child access point device transmits a response frame to the parent access point device. , simultaneously transfer the data frame to the station device.

(6) A communication device according to one aspect of the present invention includes a parent access point device, one or more child access point devices connected to the parent access point device, and one or more stations connected to the child access point device. In a network configured of devices, the child access point device receives a data frame transmitted by the parent access point device and transfers it to the station device, wherein the station device receives the data frame and transfers the data frame to the station device. When transmitting a response frame indicating success to the child access point, the forwarding of the data frame is stopped.

(7) A communication device according to one aspect of the present invention includes a parent access point device, one or more child access point devices connected to the parent access point device, and one or more stations connected to the child access point device. In a network configured of devices, a parent access point device receives a data frame transmitted by a station device connected to one of the child access point devices and decodes the data frame.

(8) Furthermore, the communication device according to one aspect of the present invention is described in (7) above, and when the destination address of the data frame indicates the parent access point device, the communication device decodes the data frame. do.

According to the present invention, in a Multi-AP wireless communication system, it is possible to improve the responsiveness of frame transmission and reception of a wireless communication device connected to a child access point device and realize low-delay communication.

FIG. 2 is a diagram illustrating an example of a frame configuration according to one aspect of the present invention. FIG. 2 is a diagram illustrating an example of a frame configuration according to one aspect of the present invention. FIG. 3 is a diagram illustrating an example of communication according to one aspect of the present invention. FIG. 2 is a schematic diagram illustrating an example of dividing a wireless medium according to one aspect of the present invention. 1 is a diagram illustrating an example of a configuration of a communication system according to one aspect of the present invention. FIG. 1 is a block diagram illustrating a configuration example of a wireless communication device according to one aspect of the present invention. FIG. 1 is a block diagram illustrating a configuration example of a wireless communication device according to one aspect of the present invention. FIG. 2 is a schematic diagram illustrating an example of an encoding method according to one aspect of the present invention. FIG. 2 is a diagram illustrating an example of a frame configuration according to one aspect of the present invention. 3 is an example of information related to a frame address according to one aspect of the present invention. 3 is an example of the flow of frames in a configuration example of a communication system according to one aspect of the present invention. FIG. 2 is a schematic diagram of communication according to one aspect of the present invention. FIG. 2 is a schematic diagram of communication according to one aspect of the present invention. FIG. 2 is a schematic diagram of communication according to one aspect of the present invention.

The communication system in this embodiment includes a wireless transmitting device (access point device, base station device: Access point, base station device) and a plurality of wireless receiving devices (station device, terminal device: station, terminal device). Further, a network composed of base station devices and terminal devices is called a basic service set (BSS: management range). Furthermore, the station device according to this embodiment can have the function of an access point device. Similarly, the access point device according to this embodiment can have the function of a station device. Therefore, in the following, when a communication device is simply referred to, the communication device can refer to both a station device and an access point device.

It is assumed that base station devices and terminal devices within a BSS perform communication based on CSMA/CA (Carrier sense multiple access with collision avoidance). In this embodiment, an infrastructure mode in which a base station apparatus communicates with a plurality of terminal apparatuses is targeted, but the method of this embodiment can also be implemented in an ad hoc mode in which terminal apparatuses directly communicate with each other. In ad hoc mode, a terminal device forms a BSS in place of a base station device. BSS in ad hoc mode is also called IBSS (Independent Basic Service Set). In the following, a terminal device that forms an IBSS in ad hoc mode can also be regarded as a base station device. The method of this embodiment can also be implemented using WiFi Direct (registered trademark), in which terminal devices directly communicate with each other. WiFi
In Direct, a terminal device forms a group in place of a base station device. In the following, a terminal device of a group owner that forms a group in WiFi Direct can also be regarded as a base station device.

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

A 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) that includes header information for signal processing in the physical layer, and a physical service data unit (PSDU) that is a data unit processed in the physical layer. MAC layer frame), etc. A PSDU can be composed of an aggregated MPDU (A-MPDU) in which a plurality of MAC protocol data units (MPDUs), which are retransmission units in a wireless section, are aggregated.

The PHY header includes a short training field (STF) used for signal detection and synchronization, a long training field (LTF) used to obtain channel information for data demodulation, etc. , and a control signal such as a signal (SIG) containing control information for data demodulation. In addition, STF can be classified into legacy STF (L-STF), high throughput STF (HT-STF), and very high throughput STF (VHT-STF), depending on the corresponding standard. It is classified into high throughput-STF), high efficiency STF (HE-STF), and extremely high throughput STF (EHT-STF), and LTF and SIG are similarly L- Classified into 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-A1-4 and HE-SIG-B. Furthermore, assuming technology updates in the same standard, a Universal SIGNAL (U-SIG) field containing additional control information may be included.

Furthermore, the PHY header can include information that identifies the BSS that is the source of the transmission frame (hereinafter also referred to as BSS identification information). The information identifying the BSS can be, for example, the SSID (Service Set Identifier) of the BSS or the MAC address of the base station device of the BSS. Further, the information identifying the BSS can be a value unique to the BSS (eg, BSS Color, etc.) other than the SSID or MAC address.

The PPDU is modulated according to the corresponding standard. For example, in the case of the IEEE802.11n standard, the signal is modulated into an orthogonal frequency division multiplexing (OFDM) signal.

An MPDU consists of a MAC layer header (MAC header) containing header information for signal processing in the MAC layer, and a MAC service data unit (MSDU) or MAC service data unit (MSDU), which is a data unit processed in the MAC layer. It consists of a frame body and a frame check sequence (FCS) that checks whether there are any errors in the frame. Moreover, a plurality of MSDUs can also be aggregated as an aggregated MSDU (A-MSDU).

The frame types of MAC layer transmission frames are broadly classified into three types: management frames that manage the connection status between devices, control frames that manage the communication status between devices, and data frames that include actual transmission data. Each of these is further classified into multiple subframe types. The control frames include a reception completion notification (Ack) frame, a transmission request (RTS) frame, a reception preparation completion (CTS) clear to send) frame, and the like. Management frames include beacon frames, probe request frames, probe response frames, authentication frames, association request frames, association response frames, etc. included. The data frame includes a data frame, a polling (CF-poll) frame, and the like. Each device can understand the frame type and subframe type of the received frame by reading the contents of the frame control field included in the MAC header.

Note that Ack may include Block Ack. Block Ack can notify reception completion for multiple MPDUs.

The beacon frame includes a field in which a beacon is transmitted (Beacon interval) and an SSID. The base station device can periodically broadcast a beacon frame within the BSS, and by receiving the beacon frame, the terminal device can know base station devices around the terminal device. The process in which a terminal device learns about a base station device based on a beacon frame broadcast from the base station device is called passive scanning. On the other hand, when a terminal device broadcasts a probe request frame within the BSS to search for a base station device, this is called active scanning. The base station device can transmit a probe response frame as a response to the probe request frame, and the content of the probe response frame is equivalent to that of a beacon frame.

After the terminal device recognizes the base station device, it performs a connection process to the base station device. The connection process is classified into an authentication procedure and an association procedure. A terminal device transmits an authentication frame (authentication request) to a base station device with which it wishes to connect. Upon receiving the authentication frame, the base station device transmits an authentication frame (authentication response) including a status code indicating whether or not the terminal device can be authenticated to the terminal device. By reading the status code written in the authentication frame, the terminal device can determine whether or not the terminal device is authorized to be authenticated by the base station device. Note that the base station device and the terminal device can exchange authentication frames multiple times.

Following the authentication procedure, the terminal device transmits a connection request frame to the base station device in order to perform a connection procedure. When the base station device receives the connection request frame, it determines whether or not to permit connection of the terminal device, and transmits a connection response frame to notify that fact. In addition to a status code indicating whether connection processing is possible, the connection response frame includes an association identifier (AID) for identifying the terminal device. The base station apparatus can manage a plurality of terminal apparatuses by setting a different AID for each terminal apparatus that has issued connection permission.

After the connection process is performed, the base station device and the terminal device perform actual data transmission. In the IEEE802.11 system, there are distributed control functions (DCF: Distributed Coordination Function), centralized control functions (PCF: Point Coordination Function), and expanded mechanisms such as enhanced distributed channel access (EDCA), A hybrid control function (HCF: Hybrid coordination function, etc.) is defined. In the following, an example will be described in which a base station apparatus transmits a signal to a terminal apparatus using DCF.

In DCF, a base station device and a terminal device perform carrier sense (CS) to check the usage status of wireless channels around the base station device and the terminal device prior to communication. For example, if a base station device that is a transmitting station receives a signal higher than a predetermined clear channel assessment level (CCA level) on the wireless channel, it stops transmitting the transmission frame on the wireless channel. put off. Hereinafter, a state in which a signal higher than the CCA level is detected in the radio channel will be referred to as a busy state, and a state in which a signal higher than the CCA level is not detected will be referred to as an idle state. In this way, CS performed by each device based on the power (received power level) of the signal actually received is called physical carrier sense (physical CS). Note that the CCA level is also called a carrier sense level (CS level) or a CCA threshold (CCA threshold: CCAT). Note that when the base station device and the terminal device detect a signal of the CCA level or higher, they start an operation of demodulating at least the PHY layer signal.

The base station device performs carrier sense on the transmission frame to be transmitted by a frame interval (IFS) depending on the type, and determines whether the wireless channel is in a busy state or an idle state. The period during which the base station device carries out carrier sensing differs depending on the frame type and subframe type of the transmission frame that the base station device will transmit from now on. In the IEEE 802.11 system, multiple IFS with different durations are defined.Short IFS (SIFS) is used for transmission frames given the highest priority, and Short IFS (SIFS) is used for transmission frames with relatively high priority. There is a polling frame interval (PCF IFS: PIFS) used, a distributed control frame interval (DCF IFS: DIFS) used for the lowest priority transmission frame, etc. When the base station device transmits a data frame using DCF, the base station device uses DIFS.

After waiting for DIFS, the base station apparatus 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 transmitted by a certain transmitting station is received by a receiving station without interference from other transmitting stations. Therefore, if transmitting stations transmit frames at the same timing, the frames will collide with each other, and the receiving station will not be able to 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 that the wireless channel is in an idle state through carrier sense, it starts counting down the CW, and only when the CW reaches 0 does it acquire the transmission right and can transmit a transmission frame to the terminal device. Note that if the base station apparatus determines that the wireless channel is in a busy state through carrier sense during the CW countdown, the CW countdown is stopped. Then, when the wireless channel becomes idle, the base station device restarts the countdown of the remaining CW following the previous IFS.

A terminal device, which is a receiving station, receives a transmission frame, reads a PHY header of the transmission frame, and demodulates the received transmission frame. Then, by reading the MAC header of the demodulated signal, the terminal device can recognize whether the transmission frame is addressed to the terminal device itself. Note that the terminal device may also determine the destination of the transmission frame based on the information written in the PHY header (for example, the group identification number (GID: Group ID) written in VHT-SIG-A). It is possible.

If the terminal device determines that the received transmission frame is addressed to its own device and is able to demodulate the transmission frame without error, it transmits an ACK frame indicating that the frame was correctly received to the base station device that is the transmitting station. Must. The ACK frame is one of the highest priority transmission frames that is transmitted only waiting for the SIFS period (no random backoff time is taken). The base station device ends a series of communications upon receiving the ACK frame transmitted from the terminal device. Note that if the terminal device cannot correctly receive the frame, the terminal device does not transmit an ACK. Therefore, if the base station apparatus does not receive an ACK frame from the receiving station for a certain period (SIFS+ACK frame length) after transmitting the frame, the base station apparatus considers the communication to have failed and terminates the communication. In this way, the end of one communication (also called a burst) in the IEEE 802.11 system occurs in special cases such as when transmitting a broadcast signal such as a beacon frame, or when fragmentation is used to divide transmitted data. Except for the following cases, the determination is always made based on whether or not an ACK frame is received.

If the terminal device determines that the received transmission frame is not addressed to itself, it uses a network allocation vector (NAV) based on the length of the transmission frame written in the PHY header etc. vector). The terminal device does not attempt communication during the period set in NAV. In other words, the terminal device performs the same operation for the period set in NAV as if it were determined by the physical CS that the wireless channel is in a busy state, 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, NAV is also set based on the request to send (RTS) frame introduced to solve the hidden terminal problem, and the ready-to-receive (CTS) frame.
Clear to send) frame.

In contrast to DCF, in which each device performs carrier sense and autonomously acquires transmission rights, in PCF, a control station called a point coordinator (PC) controls transmission rights of each device within the BSS. Generally, a base station device becomes a PC and acquires the transmission right of a terminal device within the BSS.

The communication period by PCF includes a contention free period (CFP) and a contention period (CP). Communication is performed between the CPs based on the DCF described above, and the PC controls transmission rights between the CFPs. A base station device, which is a PC, broadcasts a beacon frame in which a CFP period (CFP Max duration) and the like are described within the BSS prior to PCF communication. Note that PIFS is used to transmit the beacon frame broadcast at the start of PCF transmission, and is transmitted without waiting for CW. The terminal device that has received the beacon frame sets the CFP period written in the beacon frame to NAV. From then on, until the NAV elapses or a signal notifying the end of CFP is received within the BSS (for example, a data frame including CF-end), the terminal device sends a signal to acquire the transmission right transmitted from the PC. The transmission right can be acquired only when a signal (for example, a data frame containing CF-poll) is received. Note that within the CFP period, packet collisions within the same BSS do not occur, so each terminal device does not take the random backoff time used in DCF.

A wireless medium may be divided into multiple resource units (RUs). FIG. 4 is a schematic diagram showing an example of a divided state of a wireless medium. For example, in resource division example 1, the wireless communication device can divide the frequency resource (subcarrier), which is a wireless medium, into nine RUs. Similarly, in resource division example 2, the wireless communication device can divide the subcarrier, which is a wireless medium, into five RUs. Naturally, the example of resource division shown in FIG. 4 is just one example, and for example, a plurality of RUs can be configured with different numbers of subcarriers. Furthermore, the wireless medium divided into RUs can include not only frequency resources but also spatial resources. A wireless communication device (for example, an AP) can simultaneously transmit frames to multiple terminal devices (for example, multiple STAs) by arranging frames addressed to different terminal devices in each RU. The AP can write information (resource allocation information) indicating the state of division of the wireless medium as common control information in the PHY header of the frame transmitted by the AP itself. Further, the AP can write information (resource unit assignment information) indicating the RU in which frames addressed to each STA are allocated as unique control information in the PHY header of the frame transmitted by the AP.

Furthermore, multiple terminal devices (for example, multiple STAs) can simultaneously transmit frames by arranging and transmitting frames in respective assigned RUs. After receiving a frame (Trigger frame: TF) containing trigger information transmitted from the AP, the plurality of STAs can wait for a predetermined period and then transmit the frame. Each STA can grasp the RU assigned to its own device based on the information described in the TF. Further, each STA can acquire an RU by random access based on the TF.

The AP can simultaneously allocate multiple RUs to one STA. The plurality of RUs can be made up of continuous subcarriers or can be made up of discontinuous subcarriers. The AP can transmit one frame using multiple RUs assigned to one STA, or can transmit multiple frames by assigning them to different RUs. At least one of the plurality of frames may be a frame including common control information for a plurality of terminal devices that transmit resource allocation information.

One STA can be assigned multiple RUs by the AP. A STA can transmit one frame using multiple assigned RUs. Further, the STA can use the multiple assigned RUs to allocate multiple frames to different RUs and transmit them. The plurality of frames can be frames of different frame types.

The AP can assign multiple AIDs to one STA. The AP can allocate RUs to each of multiple AIDs allocated to one STA. The AP can transmit different frames to multiple AIDs assigned to one STA using the assigned RUs. The different frames may be of different frame types.

One STA can be assigned multiple AIDs by the AP. One STA can be assigned RUs to each of a plurality of assigned AIDs. One STA recognizes that the RUs assigned to each of the multiple AIDs assigned to the own device are all RUs assigned to the own device, and transmits one frame using the multiple assigned RUs. can do. Furthermore, one STA can transmit multiple frames using the assigned multiple RUs. At this time, information indicating the AID associated with each allocated RU can be written in the plurality of frames and transmitted. The AP can transmit different frames to multiple AIDs assigned to one STA using the assigned RUs. The different frames may be of different frame types.

Hereinafter, the base station device and the terminal device will be collectively referred to as a wireless communication device or a communication device. Information exchanged when one wireless communication device communicates with another wireless communication device is also called data. That is, the wireless communication device includes a base station device and a terminal device.

The wireless communication device has either or both of a function of transmitting a PPDU and a function of receiving a PPDU. FIG. 1 is a diagram showing an example of a PPDU configuration transmitted by a wireless communication device. IEEE
PPDU compatible with the 802.11a/b/g standard has a structure that includes L-STF, L-LTF, L-SIG, and Data frames (MAC Frame, MAC frame, payload, data part, data, information bits, etc.). be. A PPDU compatible with the IEEE802.11n standard has a configuration including L-STF, L-LTF, L-SIG, HT-SIG, HT-STF, HT-LTF, and Data frames. PPDUs compatible with the IEEE802.11ac standard include part or all of L-STF, L-LTF, L-SIG, VHT-SIG-A, VHT-STF, VHT-LTF, VHT-SIG-B, and MAC frames. The structure is as follows. The PPDUs considered in the IEEE802.11ax standard are L-STF, L-LTF, L-SIG, RL-SIG in which L-SIG is temporally repeated, HE-SIG-A, HE-STF, HE- This configuration includes part or all of LTF, HE-SIG-B, and Data frames. The PPDUs considered in the IEEE802.11be standard are L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, HET-LTF, and part of the Data frame or This is a configuration that includes everything.

L-STF, L-LTF, and L-SIG surrounded by dotted lines in Figure 1 are configurations commonly used in the IEEE802.11 standard (below, L-STF, L-LTF, and L-SIG are (also collectively referred to as L-header). For example, a wireless communication device compatible with the IEEE 802.11a/b/g standard can appropriately receive an L-header in a PPDU compatible with the IEEE 802.11n/ac standard. A wireless communication device compatible with the IEEE 802.11a/b/g standard can receive a PPDU compatible with the IEEE 802.11n/ac standard, regarding it as a PPDU compatible with the IEEE 802.11a/b/g standard. .

However, since wireless communication devices compatible with the IEEE 802.11a/b/g standards cannot demodulate the PPDU that follows the L-header and supports the IEEE 802.11n/ac standards, ), the receiving address (RA), and information regarding the Duration/ID field used for NAV settings cannot be demodulated.

IEEE 802.11 inserts Duration information into L-SIG as a method for wireless communication devices compatible with the IEEE 802.11a/b/g standards to appropriately set NAV (or perform reception operations for a predetermined period). It stipulates how to do so. Information regarding the transmission rate within L-SIG (RATE field, L-RATE field, L-RATE, L_DATARATE, L_DATARATE field) and information regarding the transmission period (LENGTH field, L-LENGTH field, L-LENGTH) is based on the IEEE 802. A wireless communication device compatible with the 11a/b/g standard is used to appropriately set the NAV.

FIG. 2 is a diagram illustrating an example of a method for inserting Duration information into L-SIG. Although FIG. 2 shows a PPDU configuration compatible with the IEEE802.11ac standard as an example, the PPDU configuration is not limited to this. A PPDU configuration compatible with the IEEE802.11n standard and a PPDU configuration compatible with the IEEE802.11ax standard may be used. TXTIME includes information regarding the length of the PPDU, aPreambleLength includes information regarding the length of the preamble (L-STF+L-LTF), and aPLCPHeaderLength includes information regarding the length of the PLCP header (L-SIG). L_LENGTH is Signal Extension, which is a virtual period set for compatibility with the IEEE802.11 standard, N _ops related to L_RATE, aSymbolLength, which is information regarding the period of one symbol (symbol, OFDM symbol, etc.); aP indicating the number of bits included in the PLCP Service field
It is calculated based on LCPServiceLength and aPLCPConvolutionalTailLength, 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. Additionally, the wireless communication device can calculate L-SIG Duration. L-SIG Duration indicates information regarding the total period of the PPDU including L_LENGTH and the period of the Ack and SIFS expected to be transmitted from the destination wireless communication device in response.

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 a part or both of a PLCP header. Moreover, BA is Block Ack or Ack. The PPDU can be configured to include L-STF, L-LTF, and L-SIG, and further include one or more of DATA, BA, RTS, and CTS. Although 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 a period indicated by the value of Duration/ID field. Additionally, the Initiator can transmit a CF_End frame to notify the end of the L-SIG TXOP Protection period.

Next, a method for identifying a BSS from a frame received by a wireless communication device will be described. In order for the wireless communication device to identify the BSS from the received frame, the wireless communication device that transmits the PPDU must include information for identifying the BSS (BSS color, BSS identification information, a value unique to the BSS) in the PPDU. It is preferable to insert it. Information indicating the BSS color can be written in HE-SIG-A.

The wireless communication device can transmit L-SIG multiple times (L-SIG Repetition). For example, a wireless communication device on the receiving side receives L-SIG transmitted multiple times using MRC (Maximum Ratio Combining), thereby improving the demodulation accuracy of L-SIG. Furthermore, when the wireless communication device completes correctly receiving the L-SIG using MRC, it can interpret that the PPDU including the L-SIG is a PPDU that complies with the IEEE802.11ax standard.

Even while receiving a PPDU, the wireless communication device must receive a portion of the PPDU other than the PPDU (for example, a preamble defined by IEEE802.11, L-STF, L-LTF, PLCP header, etc.). (also called double reception operation). When a wireless communication device detects a part of a PPDU other than the PPDU during a PPDU reception operation, the wireless communication device updates part or all of the information regarding the destination address, source address, PPDU or DATA period. I can do it.

Ack and BA can also be called a response (response frame). Further, a probe response, an authentication response, and a connection response can be called a response.
[1. First embodiment]

A Multi-AP wireless communication system is comprised of a wireless communication system provided by two or more access point devices. FIG. 5 is a diagram showing an example of the Multi-AP wireless communication system according to the present embodiment, and is an example configured of three wireless communication systems: a wireless communication system 3-1, a wireless communication system 3-2, and a wireless communication system 3-3. It is. In a Multi-AP wireless communication system, in addition to the conventional frame transmission and reception between one access point device and one or more station devices, multiple access point devices cooperate to send and receive frames between the station device and the station device. It also aims to send and receive data. Basically, the communication areas and coverages (3-1, 3-2, and 3-3 in this example) provided by each wireless communication system are configured to overlap. In this example, the Multi-AP wireless communication system is configured from three wireless communication systems, but of course, it may be configured from more than three wireless communication systems.

The wireless communication system 3-1 includes a wireless communication device 1-1 and wireless communication devices 2-1, 2-12, 2-13, and 2-123. Note that the wireless communication device 1-1 is also referred to as a base station device 1-1, and the wireless communication devices 2-1, 2-12, 2-13, and 2-123 are referred to as terminal devices 2-1, 2-12, and 2-1. Also called 13, 2-123. Furthermore, the wireless communication devices 2-1, 2-12, 2-13, and 2-123 are connected (associated) with the wireless communication device 1-1, including the wireless communication device 2A and the terminal device 2A. Also called. The wireless communication device 1-1 and the wireless communication device 2A are wirelessly connected and are in a state where they can send and receive PPDUs to and from each other. Furthermore, although the wireless communication device 2-12 is connected to the wireless communication device 1-1, it can also transmit and receive frames that operate cooperatively with the wireless communication device 1-2. Although the wireless communication device 2-13 is connected to the wireless communication device 1-1, it can also transmit and receive frames that operate cooperatively with the wireless communication device 1-3. Although the wireless communication device 2-123 is connected to the wireless communication device 1-1, it can also transmit and receive frames operated cooperatively with the wireless communication device 1-2 and the wireless communication device 1-3. The wireless communication device 2-1 transmits and receives frames only to the wireless communication device 1-1 to which it is connected.

The wireless communication system 3-2 includes a wireless communication device 1-2 and wireless communication devices 2-2, 2-21, 2-23, and 2-213. Note that the wireless communication device 1-2 is also referred to as the base station device 1-2, and the wireless communication devices 2-2, 2-21, 2-23, and 2-213 are referred to as the terminal devices 2-2, 2-21, and 2-2. Also called 23, 2-213. Further, the wireless communication devices 2-2, 2-21, 2-23, and 2-213 are also referred to as the wireless communication device 2B and the terminal device 2B as devices connected to the wireless communication device 1-2. The wireless communication device 1-2 and the wireless communication device 2B are wirelessly connected and are in a state where they can send and receive PPDUs to and from each other. Furthermore, although the wireless communication device 2-21 is connected to the wireless communication device 1-2, it can also transmit and receive frames that operate cooperatively with the wireless communication device 1-1. Although the wireless communication device 2-23 is connected to the wireless communication device 1-2, it can also transmit and receive frames that operate cooperatively with the wireless communication device 1-3. Although the wireless communication device 2-123 is connected to the wireless communication device 1-1, it can also transmit and receive frames operated cooperatively with the wireless communication device 1-2 and the wireless communication device 1-3. The wireless communication device 2-2 transmits and receives frames only to the wireless communication device 1-2 to which it is connected.

The wireless communication system 3-3 includes a wireless communication device 1-3 and wireless communication devices 2-3, 2-31, 2-32, and 2-312. Note that the wireless communication device 1-3 is also referred to as a base station device 1-3, and the wireless communication devices 2-3, 2-31, 2-32, and 2-312 are referred to as terminal devices 2-3, 2-31, and 2-3. Also called 32, 2-312. Furthermore, the wireless communication devices 2-31, 2-32 and the terminal devices 2-31, 2-32 are also referred to as the wireless communication device 2C and the terminal device 2C as devices connected to the wireless communication device 1-3. The wireless communication device 1-2 and the wireless communication device 2B are wirelessly connected and are in a state where they can send and receive PPDUs to and from each other. Furthermore, although the wireless communication device 2-31 is connected to the wireless communication device 1-3, it can also transmit and receive frames that operate cooperatively with the wireless communication device 1-1. Although the wireless communication device 2-32 is connected to the wireless communication device 1-3, it can also transmit and receive frames that operate cooperatively with the wireless communication device 1-2. Although the wireless communication device 2-312 is connected to the wireless communication device 1-3, it can also transmit and receive frames operated cooperatively with the wireless communication device 1-1 and the wireless communication device 1-2. The wireless communication device 2-3 transmits and receives frames only to the wireless communication device 1-3 to which it is connected.

Wireless communication devices (access point devices) 1-1, 1-2, and 1-3 each configure a wireless communication system, and at least one access point device is a parent access point device (parent AP) (Coordinator access point device). (Coordinator AP), Sharing access point device (Sharing AP), etc.) is a child access point device (Child AP) (Coordinated access point device (Coordinated AP), Shared access point device ( It assumes the role of centrally controlling the Shared AP (also known as Shared AP) and issues instructions. Furthermore, the parent access point device may handle data frames transmitted to or received from station devices connected to each access point device. That is, the station device receives the data frame transmitted by the parent access point device via the child access point device. Furthermore, the data frame transmitted by the station device may be received by the parent access point device via the child access point device.

As an example according to this embodiment, using FIG. 5, wireless communication devices 1-2 and 1-3, which are child access point devices, are connected to a wireless communication device 1-1, which is a parent access point device. However, this is just an example. A wireless communication device 1-2, which is a child access point device, connects to a wireless communication device 1-1, which is a parent access point device, and a wireless communication device, which is a child access point device, connects to the wireless communication device 1-2, which is a child access point device. 1-3, and other access point devices may also connect to the wireless communication device 1-3. There is no limit to the number of access point devices that can be connected in series (depth of connection, number of stages of connection). Also, two or more multiple access point devices can be connected to one (parent or child) access point device, and access point devices that are branched from and connected to one (parent or child) access point device. There is no limit to the number of . Therefore, there are various types of connection topologies for Multi-AP wireless communication systems that include multiple access point devices.

The wireless communication device 2-2 is connected to the child access point device 1-2 and does not receive cooperative operations from other access point devices (in this example, the wireless communication devices 1-1 and 1-3). In this case, the data frame transmitted by the wireless communication device 1-1 is received by the wireless communication device 2-2 via the wireless communication device 1-2. Similarly, the wireless communication device 2-3 is connected to the child access point device 1-3 and receives cooperative operations from other access point devices (in this example, wireless communication devices 1-1 and 1-3). do not have. In this case, the data frame transmitted by the wireless communication device 1-1 is received by the wireless communication device 2-3 via the wireless communication device 1-3.

FIG. 9 shows an example of the MAC Frame format. The MAC Frame here refers to the Data frame (MAC Frame, payload, data section, data, information bits, etc.) in FIG. 1 and the MAC Frame in FIG. 2. MAC Frame includes Frame Control, Duration/ID, Address1, Address2, Address3, Sequence Control, Address4, QoS Control, HT Control, Frame Body, and FCS.

Although the wireless communication system 3-1, the wireless communication system 3-2, and the wireless communication system 3-3 form different BSSs, this does not necessarily mean that their ESSs (Extended Service Sets) are different. ESS indicates a service set forming a LAN (Local Area Network). In other words, wireless communication devices belonging to the same ESS can be considered by the upper layer to belong to the same network. Further, the BSSs are combined via a DS (Distribution System) to form an ESS. Note that each of the wireless communication systems 3-1, 3-2, and 3-3 may further include a plurality of wireless communication devices.

FIG. 10 summarizes the addresses written in the Address1, Address2, Address3, Sequence Control, and Address4 fields included in FIG. 9 in a table according to the values of FromDS and ToDS. FromDS and ToDS information are included in the FrameControl field in FIG. 9. The value of FromDS is 1 when the frame is transmitted from a DS, and 0 when the frame is transmitted from a source other than the DS. The value of ToDS is 1 when the frame is received by the DS, and 0 when the frame is received by a non-DS. Note that SA refers to Source Address, and DA refers to Destination Address. The table in FIG. 10 shows that the meanings of Address 1 to Address 4 change depending on the values of FromDS and ToDS.

FIG. 6 is a diagram showing an example of the device configuration of wireless communication devices 1-1, 1-2, 1-3, 2A, 2B, and 2C (hereinafter collectively referred to as wireless communication devices 10000-1). . The wireless communication device 10000-1 includes an upper layer section (upper layer processing step) 10001-1, an autonomous distributed control section (autonomous distributed control step) 10002-1, a transmitting section (transmitting step) 10003-1, and a receiving section. The configuration includes (receiving step) 10004-1 and an antenna section 10005-1.

The upper layer section 10001-1 is connected to other networks and can notify the autonomous decentralized control section 10002-1 of information regarding traffic. The information regarding traffic may be, for example, information addressed to another wireless communication device, or may be control information included in a management frame or a control frame.

FIG. 7 is a diagram showing an example of the device configuration of the autonomous decentralized control unit 10002-1. The autonomous decentralized control unit 10002-1 has a configuration including a CCA unit (CCA step) 10002a-1, a backoff unit (backoff step) 10002b-1, and a transmission determination unit (transmission determination step) 10002c-1. be.

The CCA section 10002a-1 uses either or both of the information regarding the received signal power received via the radio resource and the information regarding the received signal (including information after decoding) notified from the receiving section. , it is possible to determine the status of the wireless resource (including determining whether it is busy or idle). 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.

The backoff unit 10002b-1 can perform backoff using the wireless resource state determination information. The backoff unit 10002b-1 generates a CW and has a countdown function. For example, when the wireless resource status determination information indicates idle, the CW countdown can be executed, and when the wireless resource status determination information indicates busy, the CW countdown can be stopped. The backoff unit 10002b-1 can notify the transmission determination unit 10002c-1 of the CW value.

The transmission determination unit 10002c-1 makes a transmission determination using either or both of the radio resource state determination information and the CW value. For example, when the wireless resource status determination information indicates idle and the CW value is 0, transmission determination information can be notified to the transmitter 10003-1. Further, when the wireless resource state determination information indicates idle, transmission determination information can be notified to the transmitter 10003-1.

The transmitting unit 10003-1 has a configuration including 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 generation unit 10003a-1 has a function of generating a physical layer frame (PPDU) based on the transmission determination information notified from the transmission determination unit 10002c-1. The physical layer frame generation unit 10003a-1 performs error correction encoding, modulation, precoding filter multiplication, etc. on the transmission frame sent from the upper layer. Physical layer frame generation section 10003a-1 notifies wireless transmission section 10003b-1 of the generated physical layer frame.

FIG. 8 is a diagram showing an example of error correction encoding by the physical frame generation unit according to the present embodiment. As shown in FIG. 8, information bit (systematic bit) sequences are placed in the shaded area, and redundant (parity) bit sequences are placed in the white area. A bit interleaver is appropriately applied to each of the information bits and redundant bits. The physical frame generation unit can read out the required number of bits from the arranged bit sequence as a starting position determined according to the value of the redundancy version (RV). By adjusting the number of bits, the coding rate can be changed flexibly, that is, puncturing can be performed. Note that in FIG. 8, a total of four types of RV are shown, but in the error correction encoding according to this embodiment, the options for RV are not limited to specific values. The location of the RV needs to be shared between the station devices.

The physical layer frame generation unit performs error correction encoding on the information bits transferred from the MAC layer, but the unit (encoded block length) in which the error correction encoding is applied is not limited to any particular unit. do not have. For example, the physical layer frame generation unit may divide the information bit sequence transferred from the MAC layer into information bit sequences of a predetermined length, perform error correction encoding on each of the information bit sequences, and create multiple encoded blocks. can. Note that when configuring a coded block, dummy bits can also be inserted into the information bit sequence transferred from the MAC layer.

The frame generated by the physical layer frame generation unit 10003a-1 includes control information. The control information includes information indicating in which RU (here, an RU includes both frequency resources and spatial resources) data addressed to each wireless communication device is placed. Furthermore, the frame generated by the physical layer frame generation unit 10003a-1 includes a trigger frame that instructs the wireless communication device that is the destination terminal to transmit the frame. The trigger frame includes information indicating the RU used when the wireless communication device instructed to transmit the frame transmits the frame.

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

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

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

The signal demodulator 10004b-1 has a function of demodulating the physical layer signal generated by the wireless receiver 10004a-1. Processing performed by signal demodulation section 10004b-1 includes channel equalization, demapping, error correction decoding, and the like. The signal demodulation unit 10004b-1 can extract, for example, information included in the physical layer header, information included in the MAC header, and information included in the transmission frame from the physical layer signal. The signal demodulation section 10004b-1 can notify the extracted information to the upper layer section 10001-1. Note that the signal demodulator 10004b-1 can extract any or all of the information included in the physical layer header, the MAC header, and the transmission frame.

The antenna section 10005-1 has a function of transmitting the radio frequency signal generated by the radio transmitting section 10003b-1 to the radio space toward the radio device 0-1. Furthermore, the antenna section 10005-1 has a function of receiving a radio frequency signal transmitted from the wireless device 0-1.

By writing information indicating the period during which the wireless communication device 10000-1 uses the wireless medium in the PHY header and MAC header of the frame to be transmitted, the wireless communication device 10000-1 transmits NAV to wireless communication devices around the wireless communication device for only the relevant period. Can be set. For example, the wireless communication device 10000-1 can write information indicating the period in the Duration/ID field or Length field of the frame to be transmitted. The NAV period set in wireless communication devices around the wireless communication device 10000-1 will be referred to as the TXOP period (or simply TXOP) acquired by the wireless communication device 10000-1. The wireless communication device 10000-1 that has acquired the TXOP is called a TXOP acquirer (TXOP holder). The frame type of the frame that the wireless communication device 10000-1 transmits to acquire TXOP is not limited to any particular type, and may be a control frame (for example, an RTS frame or a CTS-to-self frame), or a data frame. But it's okay.

The wireless communication device 10000-1, which is a TXOP holder, can transmit frames to wireless communication devices other than itself between the TXOPs. If the wireless communication device 1-1 is a TXOP holder, the wireless communication device 1-1 can transmit a frame to the wireless communication device 2A within the period of the TXOP. 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 within the TXOP period. The wireless communication device 1-1 can transmit a trigger frame including information instructing the wireless communication device 1-1 to transmit a frame to the wireless communication device 2A within the TXOP period.

The wireless communication device 1-1 may secure TXOP for all communication bands (for example, Operation bandwidth) in which frames may be transmitted, or may secure TXOP for all communication bands (for example, Operation bandwidth) in which frames may be transmitted (for example, Transmission bandwidth). may be reserved for a specific communication band.

The wireless communication device that instructs frame transmission within the TXOP period acquired by the wireless communication device 1-1 is not necessarily limited to the wireless communication device connected to the wireless communication device 1-1. For example, a wireless communication device sends a message to a wireless communication device that is not connected to the wireless communication device in order to cause the wireless communication devices around the device to transmit a management frame such as a Reassociation frame, or a control frame such as an RTS/CTS frame. , can instruct frame transmission.

Furthermore, TXOP in EDCA, which is a data transmission method different from DCF, will also be explained. The IEEE802.11e standard is related to EDCA, and specifies TXOP from the viewpoint of guaranteeing QoS (Quality of Service) for various services such as video transmission and VoIP. Services are broadly divided into VO (VOice), VI (VIdeo), and BE (Best).
It is classified into four access categories: Effort) and BK (BacK ground). Generally, the order of priority is VO, VI, BE, and BK. Each access category has parameters such as the minimum CW value CWmin, the maximum value CWmax, AIFS (Arbitration IFS), which is a type of IFS, and TXOP limit, which is the upper limit of transmission opportunities. The value is set. For example, the CWmin, CWmax, and AIFS of a VO with the highest priority for audio transmission can be set to relatively small values compared to other access categories, thereby allowing data to be prioritized over other access categories. Transmission becomes possible. For example, in a VI where the amount of data to be transmitted is relatively large due to video transmission, by setting a large TXOP limit, it is possible to take a longer transmission opportunity than in other access categories. In this way, the values of the four parameters for each access category are adjusted for the purpose of guaranteeing QoS according to various services.

In this embodiment, the signal demodulation unit of the station device can perform decoding processing on the received signal in the physical layer and perform error detection. Here, the decoding process includes a decoding process for the error correction code applied to the received signal. Here, error detection includes error detection using an error detection code (for example, a cyclic redundancy check (CRC) code) added to the received signal in advance, or error detection using an error correction code that originally has an error detection function (for example, a low-density parity code). Includes error detection using check code (LDPC). Decoding processing in the physical layer can be applied to each encoded block.

The upper layer section transfers the result of decoding the physical layer in the signal demodulation section to the MAC layer. The MAC layer restores the MAC layer signal from the transferred physical layer decoding result. Then, error detection is performed in the MAC layer, and it is determined whether the MAC layer signal transmitted by the station device that is the source of the received frame has been correctly restored.

The wireless communication device according to the present embodiment demodulates the PPDU frame detected by carrier sensing if it can be demodulated, checks Address 1 to Address 4 included in the MAC Frame, and if DA indicates the MAC address of the device itself. It is possible to decode the Frame Body. Further, the frame body may be decoded not only in the DA but also in the case where any one of Address 1 to Address 4 matches the MAC address of the device itself. In the conventional technology, the Frame Body is decoded only when the RA indicates the MAC address of its own device.

The contents of Address1 to Address4 will be explained using FIG. 11, which was created by extracting the minimum elements from FIG. 5. Assume that the wireless communication device 2-2 receives a data frame 11-1 transmitted by the wireless communication device 1-1 as a data frame 11-2 via the wireless communication device 1-2. In the data frame 11-1 that the wireless communication device 1-1 transmits to the wireless communication device 1-2, FromDS is 1, ToDS is 1, Address1 is the MAC address of the wireless communication device 1-2, and Address2 is the wireless communication device 1- 1 and Address 3 are the MAC addresses of the wireless communication device 2-2. In the data frame 11-2 that the wireless communication device 1-2 transmits to the wireless communication device 2-2, FromDS is 1, ToDS is 0, Address1 is the MAC address of the wireless communication device 2-2, and Address2 is the wireless communication device 1- 2 MAC address. In this way, Address 3 of the data frame 11-1 and Address 1 of the relayed data frame 11-2 are DA, which in this example is the MAC address of the wireless communication device 2-2. In other words, the wireless communication device 2-2 carrier-senses the data frame 11-1 addressed to the wireless communication device 1-2 and demodulates the data frame 11-1 if it is possible to demodulate the data frame 11-1 addressed to the wireless communication device 1-2. Since the MAC address is 2, it can be decoded. In the prior art, the wireless communication device 2-2 demodulates and decodes only when the RA of the data frame is the MAC address of the wireless communication device 2-2.

Similarly, a case will be described in which the wireless communication device 2-3 receives a data frame 11-3 transmitted by the wireless communication device 1-1 as a data frame 11-4 via the wireless communication device 1-3. In the data frame 11-3 that the wireless communication device 1-1 transmits to the wireless communication device 1-3, FromDS is 1, ToDS is 1, Address1 is the MAC address of the wireless communication device 1-3, and Address2 is the wireless communication device 1- 1 and Address 3 are the MAC addresses of the wireless communication device 2-3. In the data frame 11-4 that the wireless communication device 1-3 transmits to the wireless communication device 2-3, FromDS is 1, ToDS is 0, Address1 is the MAC address of the wireless communication device 2-3, and Address2 is the wireless communication device 1- The MAC address will be 3. In this way, Address 3 of the data frame 11-3 and Address 1 of the relayed data frame 11-4 are DA, which in this example is the MAC address of the wireless communication device 2-3. In other words, the wireless communication device 2-3 carrier-senses the data frame 11-3 addressed to the wireless communication device 1-3 and demodulates the data frame 11-3 if it is possible to demodulate the data frame 11-3 addressed to the wireless communication device 1-3. Since it is a MAC address of 3, it can be decoded. In the prior art, the wireless communication device 2-3 demodulates and decodes only when the RA of the data frame is the MAC address of the wireless communication device 2-3.

In this way, when the wireless communication device according to the present embodiment can carrier sense and demodulate the data frame flowing on the wireless medium, the RA checks Address1 to Address4 included in the MAC Frame, and the RA determines the MAC address of the own device. Even if the DA does not indicate the MAC address of its own device, it can be decoded if the DA indicates its own MAC address. Furthermore, it may be possible to decode the Frame Body not only for DA but also when any of Address 1 to Address 4 matches the MAC address of the device itself.

FIG. 12 shows an overview of communication along the time axis in the case where the data frame transmitted by the wireless communication device 1-1 described above is received by the wireless communication device 2-2 via the wireless communication device 1-2. show. Note that the square shown below the horizontal line indicating the time axis means a downlink frame, and the square shown above means an uplink frame. In the data frame 12-1 (corresponding to 11-1 in FIG. 11) that the wireless communication device 1-1 transmits to the wireless communication device 1-2, FromDS is 1, ToDS is 1, and Address1 (corresponding to RA) is wireless. The MAC address of the communication device 1-2, Address2 (corresponding to TA), is the MAC address of the wireless communication device 1-1, and Address3 (corresponding to DA) is the MAC address of the wireless communication device 2-2. The wireless communication device 1-2 designated as RA receives the data frame 12-1 and transmits a response frame 12-2 to the wireless communication device 1-1.

In this embodiment, the wireless communication device 2-2 designated as the DA can also receive, demodulate, and decode the data frame 12-1, thus achieving lower delay compared to conventional communication procedures. be able to. The wireless communication device 2-2 receives the data frame 12-1, and may or may not transmit the response frame 12-5 to the wireless communication device 1-2. Alternatively, the wireless communication device 2-2 may or may not receive the data frame 12-1 and transmit the response frame 12-5 to the wireless communication device 1-1.

The conventional communication procedure described above is to relay the data frame 12-1 received by the wireless communication device 1-2 to the wireless communication device 2-2 as a data frame 12-3 (corresponding to 11-2 in FIG. 11). It is a procedure. In data frame 12-3, FromDS is 1, ToDS is 0, Address1 (corresponding to RA and DA) is the MAC address of wireless communication device 2-2, and Address2 (corresponding to TA) is the MAC address of wireless communication device 1-2. becomes. The wireless communication device 2-2 designated as RA receives the data frame 12-3 and transmits a response frame 12-4 to the wireless communication device 1-2. As shown in FIG. 12, there is a time difference of t1 between the time when the wireless communication device 2-2 completes receiving the data frame 12-1 and the time when the wireless communication device 2-2 completes receiving the data frame 12-3. The contents of the data carried in each of the data frames 12-1 and 12-3 are substantially the same. In other words, the wireless communication device 2-2 receives, demodulates and decodes the data frame 12-1, thereby making it possible to complete the reception much earlier than time t1.

Note that the response frame 12-5 may be multiplexed with the response frame 12-2 and transmitted, and OFDMA is one of the multiplexing methods. The wireless communication device 1-1 can specify in advance which RU each response frame uses. Another method is to use Multi-link Operation (MLO), which allows wireless communication devices to maintain multiple connections (Multi-link), which is being discussed in the IEEE 802.11be standardization. You can also. In addition to the 2.4 GHz band and 5 GHz band, the carrier frequency of each connection (link) in MLO includes 6 GHz band, 60 GHz band, etc., and may change depending on the laws and regulations of each country. For example, if a wireless communication system uses connection 1 (link 1) and connection 2 (link 2) in MLO, and data frame 12-1 is transmitted on link 1, wireless communication device 2-1 sends a response frame 12-2 over link 1, and wireless communication device 2-2 may multiplex the response frame by transmitting response frame 12-5 over link 2. In this way, multiple response frames are transmitted using different connections (links) at the same timing. Alternatively, wireless communication device 1-2 transmits a response frame 12-2, after which wireless communication device 2-2 transmits a response frame 12-5, and then wireless communication device 1-2 transmits a data frame. 12-3 may be transmitted in a time-division manner. That is, between the response frame 12-2 and the data frame 12-3, the wireless communication device 2-2 transmits the response frame 12-5.

Furthermore, multiplexing of data frames and response frames will be explained using FIG. 13. The response frame 13-5 (12-5 in FIG. 12) may be multiplexed and transmitted with the response frame 13-2 (12-2 in FIG. 12), and the data frame 13-7 may also be multiplexed and transmitted. It's okay. As described above, the multiplexing method includes the use of OFDMA and MLO. In this case, the wireless communication device 1-2 speeds up the transmission of the data frame 13-3 (12-3 in FIG. 12) addressed to the wireless communication device 2-2 and transmits it as a data frame 13-7. -1 is multiplexed with the response frame 13-2 to be transmitted. It is also multiplexed with a response frame 13-5 that may be transmitted by the wireless communication device 2-2. As a result, the wireless communication device 2-2 can accelerate the transmission of the response frame 13-4 (12-4 in FIG. 12) and transmit the response frame 13-8. In other words, the communication time can be shortened by the time t2, which is the difference between the transmission completion time of the response frame 13-4 and the transmission completion time of the response frame 13-8.

As mentioned above, when the wireless communication device 2-2 receives the data frame 12-1, the MAC
The information of ToDS, FromDS, and Address1 to Address4 included in the Frame is checked. From Address1 (RA), the frame is targeted for reception by wireless communication device 1-2, and from Address3 (DA), the final destination is the wireless communication device. It can be seen that it is 2-2. As a result, when the wireless communication device 2-2 receives the data frame 12-1, it may transmit a response frame 12-5 to the wireless communication device 1-2 designated as the RA. If response frame 12-5 indicates successful reception, wireless communication device 1-2 may cancel transmission of data frame 12-3. In other words, the data frame 12-3 and response frame 12-4 are not transmitted, and the corresponding time of the wireless medium can be released for other uses.
The wireless communication device 1-2 transmits a frame that notifies the end of CFP within the Multi-AP system. Alternatively, a frame notifying the end of CFP to the wireless communication device 1-1 corresponding to the parent access point device is transmitted, and the wireless communication device 1-1 transmits a frame notifying the end of CFP within the Multi-AP system. Further, if the response frame 12-5 indicates reception failure, the wireless communication device 1-2 transmits the data frame 12-3 to the wireless communication device 2-2.

Furthermore, when the wireless communication device 2-2 receives the data frame 12-1, it may transmit a response frame 12-5 to the wireless communication device 1-1 designated as the TA. If the response frame 12-5 indicates successful reception, the wireless communication device 1-1 can determine that the data frame has been successfully received by the wireless communication device 2-2, which is the DA. Therefore, even if the response frame 12-2 transmitted by the wireless communication device 1-2 indicates a reception failure, it can be ignored and there is no need to retransmit the data frame 12-1.

The data frame 12-1 may be composed of not only one DU (Data Unit) but also a plurality of DUs. DU (Data Unit) is a unit of retransmission in a wireless section to which a MAC header and FCS are added, and examples of DU include MPDU and A-MSDU, but are not limited to these. When the data frame 12-1 is composed of multiple DUs, the wireless communication device 2-2 may successfully receive some DUs but fail to receive other DUs, and frame a response that reflects this fact. may be generated. In other words, the response frame 12-5 indicates which DU included in the data frame 12-1 was successfully received and which DU was unsuccessfully received. In this case, the wireless communication device 1-2 may create the data frame 12-3 using all DUs included in the data frame 12-1. Alternatively, the wireless communication device 2-2 may generate the data frame 12-3 modified to include only the DUs that the wireless communication device 2-2 failed to receive. Wireless communication device 2-2 receives data frame 12-3 and transmits response frame 12-4 to wireless communication device 1-2. The contents of the response frame 12-4 are generated by also considering the contents of the response frame 12-5. When the wireless communication device 2-2 successfully receives an identifiable specific DU included in a data frame in at least one of the data frames 12-1 and 12-3, it is considered that the reception has been successful. In other words, the result of receiving the data frame 12-1 and the result of receiving the data frame 12-3 are ORed.

Wireless communications have a high probability of frames being intercepted by outsiders, and MAC frames transmitted and received over wireless media are encrypted to ensure security. In a Multi-AP wireless communication system, other access point devices such as a parent access point device (parent AP) (also called a Coordinator access point device (Coordinator AP), a Sharing access point device (Sharing AP), etc.) There is a communication device that plays the role of centrally controlling the multi-AP system, and may also manage security keys for encrypting the MAC frames of all access point devices and station devices participating in the Multi-AP system. In other words, the wireless communication device 1-1, which plays the role of the parent access point device in this example, uses the security key for encrypting the MAC frame transmitted and received between the wireless communication device 1-1 and the wireless communication device 1-2. It is also possible to notify the wireless communication device 2-2 of such information in advance. The wireless communication device 2-2 uses the information such as the security key notified from the wireless communication device 1-1 to transmit the data frame (Fig. 12-1 in 12, 13-1 in FIG. 13), etc. can also be decoded.

Up to this point, an embodiment has been described in the downlink direction in which a station device receives a data frame transmitted by a parent access point device via a child access point device. A similar technique can be applied to the uplink in the opposite direction, that is, for example, when a data frame transmitted by a station device is received by a parent access point device via a child access point device. In other words, the embodiments described so far can be applied even if the wireless communication devices that transmit data frames are replaced with the wireless communication device 1-1, which is the parent access point device, and the wireless communication device 2-2, which is the station device. This will be explained using FIG. 14.

FIG. 14 shows an overview of communication along the time axis when a data frame transmitted by the wireless communication device 2-2 is received by the wireless communication device 1-1 via the wireless communication device 1-2. There is. In the data frame 14-1 (corresponding to 11-2 in FIG. 11) that the wireless communication device 2-2 transmits to the wireless communication device 1-2, FromDS is 0, ToDS is 1, and Address1 (corresponding to RA) is wireless. The MAC address of the communication device 1-2, Address2 (corresponding to TA) is the MAC address of the wireless communication device 2-2, Address3 (corresponding to DA) is the MAC address of the wireless communication device 1-1 (or the MAC of the gateway of the LAN network) address, etc.). The wireless communication device 1-2 designated as RA receives the data frame 14-1 and transmits a response frame 14-2 to the wireless communication device 2-2.

On the other hand, since the wireless communication device 1-1 designated as DA can also receive, demodulate, and decode the data frame 14-1, it is possible to achieve lower delay compared to conventional communication procedures. The wireless communication device 1-1 receives the data frame 14-1 and may or may not transmit the response frame 14-5 to the wireless communication device 1-2. Alternatively, the wireless communication device 1-1 may or may not receive the data frame 14-1 and transmit the response frame 14-5 to the wireless communication device 2-2.

The conventional communication procedure described above is to convert data frame 14-1 (corresponding to 11-2 in FIG. 11) received by wireless communication device 1-2 to data frame 14-3 (corresponding to 11-1 in FIG. 11). This is a procedure for relaying transmission to the wireless communication device 1-1. In data frame 14-3, FromDS is 1, ToDS is 1, Address1 (corresponding to RA) is the MAC address of wireless communication device 1-1, and Address2 (corresponding to TA) is the MAC address of wireless communication device 1-2. . The wireless communication device 1-1 designated as RA receives the data frame 14-3 and transmits a response frame 14-4 to the wireless communication device 1-2. As shown in FIG. 14, there is a time difference of t3 between the time when the wireless communication device 1-1 completes receiving the data frame 14-1 and the time when the wireless communication device 1-1 completes receiving the data frame 14-3. The contents of the data carried in each of the data frames 14-1 and 14-3 are substantially the same. In other words, by receiving the data frame 14-1, demodulating and decoding it, the wireless communication device 1-1 can complete the reception by a considerable amount of time t3.

Note that the response frame 14-5 may be multiplexed with the response frame 14-2 and transmitted. OFDMA is one of the multiplexing methods, and it is up to the wireless communication device 1 to decide which RU each response frame uses. -1 can be specified in advance. Alternatively, MLO can be used, for example, if the wireless communication system uses connection 1 (link 1) and connection 2 (link 2) in MLO, data frame 14-1 is sent on link 1. If so, the wireless communication device 2-1 can transmit the response frame 14-2 over link 1, and the wireless communication device 1-1 can transmit the response frame 14-5 over link 2. In this way, multiple response frames are transmitted using different connections (links) at the same timing. Alternatively, wireless communication device 1-2 transmits a response frame 14-2, after which wireless communication device 1-1 transmits response frame 14-5, and then wireless communication device 1-2 transmits a data frame. 14-3 may be transmitted in a time-division manner. That is, between the response frame 14-2 and the data frame 14-3, the wireless communication device 1-1 transmits the response frame 14-5.
[2. Common to all embodiments]

The communication device according to the present invention can communicate in a frequency band (frequency spectrum) called a so-called unlicensed band, which does not require permission from the country or region. is not limited to this. For example, the communication device according to the present invention uses a white band that is not actually used for the purpose of preventing interference between frequencies, even though the country or region has given permission to use it for a specific service. (For example, frequency bands allocated for television broadcasting but not used in some areas) and shared spectrum (shared frequency bands) that are expected to be shared by multiple carriers. It is possible to demonstrate the effect.

The program that operates on the wireless communication device according to the present invention is a program that controls the CPU, etc. (a program that causes the computer to function) so as to realize the functions of the above embodiments related to the present invention. The information handled by these devices is temporarily stored in the RAM during processing, then stored in various ROMs and HDDs, and read, modified, and written by the CPU as necessary. Recording media for storing programs include semiconductor media (for example, ROM, nonvolatile memory card, etc.), optical recording media (for example, DVD, MO, MD, CD, BD, etc.), magnetic recording media (for example, magnetic tape, flexible disk, etc.). Furthermore, by executing the loaded program, the functions of the embodiments described above are not only realized, but also the functions of the embodiment described above are realized by processing in collaboration with the operating system or other application programs based on the instructions of the program. In some cases, the functions of the invention may be realized.

Furthermore, when distributing the program on the market, the program can be stored in a portable recording medium and distributed, or it can be transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer is also included in the present invention. Further, part or all of the communication device in the embodiments described above may be realized as an LSI, which is typically an integrated circuit. Each functional block of the communication device may be individually formed into a chip, or some or all of them may be integrated into a chip. When each functional block is integrated into an integrated circuit, an integrated circuit control section is added to control the functional blocks.

Moreover, the method of circuit integration is not limited to LSI, but may be implemented using a dedicated circuit or a general-purpose processor. Further, if an integrated circuit technology that replaces LSI emerges due to advances in semiconductor technology, it is also possible to use an integrated circuit based on this technology.

Note 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 is also applicable to stationary or non-movable electronic devices installed indoors or outdoors, such as AV devices, kitchen devices, cleaning/laundry devices, etc. Needless to say, it can be applied to appliances, air conditioning equipment, office equipment, vending machines, and other household equipment.

The embodiments of this invention have been described above in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and designs etc. within the scope of the gist of this invention may also be claimed. Included in the range.

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

1-1, 1-2, 1-3 Access point device 2-1, 2-12, 2-13, 2-123, 2-2, 2-21, 2-23, 2-213, 2-3, 2-31, 2-32, 2-312 Station devices 3-1, 3-2, 3-3 Management range 10001-1 Upper layer section 10002-1 Autonomous decentralized control section 10002a-1 CCA section 10002b-1 Backoff section 10002c-1 Transmission determination section 10003-1 Transmission section 10003a-1 Physical layer frame generation section 10003b-1 Radio transmission section 10004-1 Receiving section 10004a-1 Radio receiving section 10004b-1 Signal demodulation section 10005-1 Antenna section 11-1 ~11-4 Data frames 12-1, 12-3 Data frames 12-2, 12-4, 12-5 Response frames 13-1, 13-3, 13-7 Data frames 13-2, 13-4, 13 -5, 13-8 Response frame 14-1, 14-3 Data frame 14-2, 14-4, 14-5 Response frame

Claims (8)

a parent access point device; and one or more child access point devices connected to the parent access point device;
In a network composed of one or more station devices connected to the child access point device,
receiving a data frame that the parent access point device transmits to the child access point device;
decoding the data frame;
A station device characterized by: When the destination address of the data frame indicates the station device,
decoding the data frame;
The station device according to claim 1, characterized in that: After decoding said data frame,
transmitting a response frame to the child access point device;
The station device according to claim 1, characterized in that: After decoding said data frame,
transmitting a response frame to the parent access point device;
The station device according to claim 1, characterized in that: a parent access point device; and one or more child access point devices connected to the parent access point device;
In a network composed of one or more station devices connected to the child access point device,
The child access point device receives a data frame transmitted by the parent access point device and transfers it to the station device,
simultaneously transmitting a response frame to the parent access point device and transferring the data frame to the station device;
A child access point device characterized by: a parent access point device; and one or more child access point devices connected to the parent access point device;
In a network composed of one or more station devices connected to the child access point device,
The child access point device receives a data frame transmitted by the parent access point device and transfers it to the station device,
when the station device receives the data frame and transmits a response frame indicating success to the child access point;
stopping the transfer of the data frame;
A child access point device characterized by: a parent access point device; and one or more child access point devices connected to the parent access point device;
In a network composed of one or more station devices connected to the child access point device,
receiving a data frame transmitted by a station device connected to one of the child access point devices;
decoding the data frame;
A parent access point device characterized by: When the destination address of the data frame indicates the parent access point device,
decoding the data frame;
8. The parent access point device according to claim 7.

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