JP6954000B2 - Wireless communication equipment, wireless communication systems and wireless communication methods - Google Patents

Description

The present invention relates to wireless communication devices, wireless communication systems and wireless communication methods.

Conventionally, a CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) method has been adopted as a communication standard for wireless LAN (Local Area Network) and the like. When this method is adopted, the access point (AP) measures the received power (carrier sense) before transmitting data, and confirms that there are no other devices transmitting signals in the vicinity. Then start communication.

On the other hand, the wireless LAN system of IEEE802.11n or later adopts a beamforming technique that narrows the radiation direction of a signal and improves the received power by controlling the relative phases of a plurality of transmitting antennas. In the wireless LAN system that performs beamforming, the carrier sense method is, for example, the first method that performs carrier sense at a virtual measurement point including the beamforming gain, or carrier sense based on the average received power of each antenna. There is a second method to do.

In the first method, since the reception sensitivity is low in the direction in which the antenna gain is low due to beamforming, it is difficult to detect signals from other devices. Therefore, even if a signal is transmitted from the first device in the direction in which the antenna gain is low due to beamforming, the AP determines that it is idle as a result of carrier sense. Then, the AP starts transmission to the second device in the direction in which the antenna gain is high due to beamforming. In this case, in the second device, the signal transmitted from the AP interferes with the signal transmitted from the first device, and the reception quality deteriorates. Further, in the second method, the carrier sense is performed without considering the direction of the beam, so that the AP detects the signal from the other device even when the beam from the other device is not directed to the transmission destination device. However, signal transmission may be stopped unnecessarily.

Therefore, conventionally, when a signal from another device is received, the MAC information of the source device and the destination device is read from the MAC (Media Access Control) frame portion of the received signal, and the direction to the source device and the destination device are reached. An AP has been proposed that prohibits communication in the direction of. According to this AP, communication can be performed while reducing interference with signals by other devices.

JP-A-2009-159273 Japanese Unexamined Patent Publication No. 2010-199804

By the way, the frame of the wireless LAN is composed of a physical header unit and a MAC frame unit that follows the physical header unit, and error correction is applied to each of them individually. Therefore, the conventional AP receives the MAC information of the source device and the destination device until the end of the frame. In other words, the conventional AP has a limit in speeding up the communication process because it is difficult to determine the direction in which communication is prohibited unless the conventional AP receives the signal until the end of the frame.

The disclosed technique is made in view of the above, and provides a wireless communication device, a wireless communication system, and a wireless communication method capable of executing wireless communication processing at high speed while reducing interference with signals by other devices. The purpose is.

In one aspect, the wireless communication device is characterized by having an antenna, a group identification unit, a transmission destination candidate determination unit, and a selection unit. The antenna transmits / receives a signal in which the physical header portion of the signal includes identification information of the group to which the source device of the signal belongs. When the antenna receives the physical header part of the signal, the group identification unit acquires the group identification information from the physical header part of the received signal and identifies the group to which the source device of the received signal belongs. The destination candidate determination unit determines a candidate for the destination device of the received signal based on the group specified by the specific unit. The selection unit selects a beam in a direction in which the interference power in the candidate of the transmission destination device is equal to or less than a predetermined value, and transmits a signal from the antenna.

Wireless communication processing can be executed at high speed while reducing interference with signals from other devices.

FIG. 1 is a diagram showing an example of a wireless communication system according to an embodiment. FIG. 2 is a diagram showing a wireless LAN frame format. FIG. 3 is a block diagram showing an example of the configuration of the AP. FIG. 4 is a diagram showing an example of information stored in the database. FIG. 5 is a diagram illustrating processing of the wireless communication system according to the embodiment. FIG. 6 is a diagram illustrating processing of the wireless communication system according to the embodiment. FIG. 7 is a diagram illustrating processing of the wireless communication system according to the embodiment. FIG. 8 is a diagram illustrating processing of the wireless communication system according to the embodiment. FIG. 9 is a diagram illustrating processing of the wireless communication system according to the embodiment. FIG. 10 is a diagram illustrating processing of the wireless communication system according to the embodiment. FIG. 11 is a flowchart showing a processing flow in the AP. FIG. 12 is a diagram illustrating data transmission timing in the prior art. FIG. 13 is a diagram for explaining the data transmission timing in this embodiment. FIG. 14 is a diagram showing an example of a configuration of AP hardware.

Hereinafter, examples of the wireless communication device, the wireless communication system, and the wireless communication method disclosed in the present application will be described in detail with reference to the drawings. The following examples are examples, and the configuration and the like in the disclosed technology are not limited by the following examples.

[Example of communication system]
FIG. 1 is a diagram showing an example of a wireless communication system according to an embodiment. As shown in FIG. 1, the wireless communication system 1 has a plurality of AP10-1 to 10-2 (base stations) and a plurality of terminals 20-1 to 20-4. In the following, when each of the plurality of AP10-1 to 10-2 is generically referred to without distinction, it is simply referred to as AP10. Further, when each of the plurality of terminals 20-1 to 20-4 is generically referred to without distinction, it is simply referred to as the terminal 20. Further, the wireless communication system 1 illustrated in FIG. 1 has two AP10s and four terminals 20, but the number of AP10s and terminals 20 is not limited to this. Further, in the following, each AP 10 and each terminal 20 may be collectively referred to as a wireless communication device.

The terminal 20 wirelessly communicates with the AP 10 via a wireless LAN. The terminal 20 is equipped with an omnidirectional antenna. The AP10 wirelessly communicates with the terminal 20 via a wireless LAN. AP10 performs beamforming and transmits a signal after beamforming.

Then, the AP10-1 performs wireless communication based on a wireless LAN between, for example, terminals 20-1 and terminals 20-3 located within the range where the radio waves transmitted from the AP10-1 can reach with a communication strength. .. The AP10-2 performs wireless communication based on a wireless LAN between, for example, terminals 20-2 and terminals 20-4 located within the reach of radio waves transmitted from the AP10-2 with a communication strength.

AP10-1 to 10-2 and the plurality of terminals 20-1 to 20-4 perform wireless communication according to a wireless LAN standard such as IEEE802.11ax or IEEE802.11ah. Therefore, the frame format of IEEE802.11ax or IEEE802.11ah transmitted by the AP10 and the terminal 20 will be described with reference to FIG.

FIG. 2 is a diagram showing a wireless LAN frame format. As shown in FIG. 2, the frame has a physical header section and a MAC frame (PSDU) section (hereinafter, referred to as a MAC frame section) that follows the frame, and each of them is individually error-corrected. ..

The physical header part is a header having information on the physical connection form. The physical header section has a PLCP (Physical Layer Convergence Protocol) preamble section and a PLCP header section. The PLCP preamble section includes a signal for time synchronization added to the beginning of the frame. The PLCP header section includes information for receiving the data section such as the transmission rate and information such as the data length.

In addition, the MAC frame unit corresponds to user data. The MAC frame unit has a MAC header unit and a data unit. The MAC header section includes the MAC address of the wireless communication device that is the source of this frame, the MAC address of the wireless communication device that is the transmission destination of this frame, BSSID, and the like. The data unit is a payload in which user data is stored.

Here, in IEEE802.11ax or IEEE802.11ah, a new field called BSS Color has been added to the PLCP preamble section. The BSS Color identifies the BSS (Basic Service Set) to which the frame belongs. In other words, the BSS Color is the identification information of the group to which the signal source device belongs.

As shown in FIG. 1, in the following description, AP10-1, terminal 20-1, and terminal 20-3 belong to group A1 (BSS Color "1"). Therefore, the PLC preamble part of the physical header part of each signal transmitted by AP10-1, terminal 20-1, and terminal 20-3 includes BSS Color "1".

Further, AP10-2, terminal 20-2 and terminal 20-4 belong to group A2 (BSS Color "2"). Therefore, the PLC preamble portion of the physical header portion of each signal transmitted by the AP 10-2, the terminal 20-2, and the terminal 20-4 includes the BSS Color "2". Then, the subsequent communication method will be described by taking as an example the processing when the AP10-1 transmits data to the terminal 20-1 and the terminal 20-3.

AP10-1 receives the physical header part of the wireless LAN frame at the time of carrier sense, and reads BSS Color from the PLCP preamble part in the received physical header part. Then, when the AP10-1 determines by the read BSS Color that the received wireless LAN frame is a signal transmitted from a device belonging to a different BSS, the AP10-1 of the wireless LAN frame received based on the determined BSS. Determine candidates for destination devices. Subsequently, AP10-1 adjusts the direction of the beam so that the interference power received in the candidate of the transmission destination device is equal to or less than a predetermined value, and transmits data by the adjusted beam. As a result, the AP10-1 can execute wireless communication processing at high speed while reducing interference with signals by other devices.

[AP configuration example]
Next, the configuration of AP10 will be described with reference to FIG. FIG. 3 is a block diagram showing an example of the configuration of AP10. As shown in FIG. 3, the AP 10 includes an antenna 11, a reception processing unit 12, a database 13, a reception data processing unit 14, a selection unit 15, a data buffer 16, a transmission data processing unit 17, and a transmission processing unit 18.

The antenna 11 is a directional antenna capable of forming directivity in a specific direction. The antenna 11 has, for example, a plurality of antenna elements. In this embodiment, the antenna 11 has a plurality of antenna elements having directivity in different directions. The AP10 performs beamforming by operating the antenna element corresponding to the target radiation direction among the plurality of antenna elements. The AP10 controls the relative phases of the antenna elements with respect to the plurality of antenna elements, thereby relatively increasing the antenna gain in the specific direction, thereby increasing the transmission power of the radio waves in the specific direction and the transmission power of the radio waves in the specific direction. Beamforming may be performed to increase the received power. Further, the antenna 11 may be a rotary antenna capable of directivity in any direction by rotating an antenna element having directivity in one direction.

The reception processing unit 12 performs processing such as down-conversion and analog / digital conversion on the signal received by the antenna 11, and outputs the processed data to the reception data processing unit 14.

The database 13 sets in advance the identification information of the other wireless communication device, the type of the other wireless communication device, the BSS Color of the other wireless communication device, and the direction of arrival of the beam by the other wireless communication device in the own device. It is stored in association with each wireless communication device.

FIG. 4 is a diagram showing an example of information stored in the database 13. As shown in the table of FIG. 4, the information stored in the database 13 is composed of the BSS Color, the identification information of the source device, and a plurality of items of the beam arrival direction observed in the AP10. The source device identification information also includes information indicating the type of the source device. In the following description, for simplification of the description, the AP 10 uses an antenna 11 having six antenna elements having directivity in different directions to estimate the arrival direction of the received signal and to estimate the data. The case of performing wireless communication will be described as an example.

For example, in the database 13, as shown in the first row of the table in FIG. 4, for "AP" in which the identification information of the source device is "10-2", the BSS Color is "2" and the beam I remember that the arrival direction is the third of the six directions. Further, as shown in the second row of the table in FIG. 4, the “terminal” whose source device identification information is “20-2” is BSS Color “2”, and the beam arrival direction is the second. I remember that it was in the direction of.

The reception data processing unit 14 processes the data output from the reception processing unit 12. The reception data processing unit 14 reads the BSS Color from the physical header unit of the reception signal. Then, when the received BSS Color determines that this signal belongs to a different BSS, the received data processing unit 14 determines a candidate for a destination device for the received signal based on the determined BSS. do. Further, the received data processing unit 14 reads data from the physical header unit and the MAC frame unit of the received signal. Then, the reception data processing unit 14 determines the type of the source device of the reception signal, the identification information, the BSS Color, and the reception signal based on the data read from the physical header unit and the MAC frame unit and the arrival direction of the reception signal. Is stored in the database 13 in association with the arrival direction of.

The reception data processing unit 14 includes an arrival direction estimation unit 141, a BSS Color identification unit 142, a source candidate determination unit 143, a transmission destination candidate determination unit 144, and a storage unit 145. The BSS Color specific unit 142 is an example of a group specific unit.

The arrival direction estimation unit 141 estimates the arrival direction of the received signal based on the received power of the received signal received by the antenna 11. Then, the arrival direction estimation unit 141 outputs the arrival direction of the estimated reception signal to the transmission source candidate determination unit 143 and the storage unit 145. For example, the arrival direction estimation unit 141 measures the reception power of each of the antenna elements in the six directions, and estimates that the direction of the antenna element having the largest reception power is the arrival direction of the received signal. The arrival direction estimation unit 141 may estimate the arrival direction of the received signal by using another method.

The BSS Color specifying unit 142 identifies the physical header unit from the data output from the reception processing unit 12, acquires the BSS Color from the specified physical header unit, and specifies the BSS Color. Then, the BSS Color specific unit 142 outputs the acquired BSS Color to the source candidate determination unit 143, the transmission destination candidate determination unit 144, and the storage unit 145. Further, the BSS Color identification unit 142 identifies the MAC frame unit from the data output from the reception processing unit 12, and acquires the identification information of the source device from the specified MAC frame unit. Further, the BSS Color identification unit 142 specifies the type of the source device based on the information in the header unit of the MAC frame unit. The BSS Color specific unit 142 refers to, for example, the Frame Control bit included in the header unit of the MAC frame unit, and determines whether or not the received signal is a beacon signal. Then, the BSS Color specific unit 142 determines that the type of the source device is AP10 when the received signal is a beacon signal, and determines that the type of the source device is the terminal 20 when the received signal is not a beacon signal. Then, the BSS Color specific unit 142 outputs the type and identification information of the source device to the storage unit 145.

The storage unit 145 stores the BSS color output from the BSS color specific unit 142, the identification information of the source device, and the type of the source device in the database 13 in association with the arrival direction output from the arrival direction estimation unit 141. do.

The source candidate determination unit 143 determines a wireless communication device belonging to the BSS Color specified by the BSS Color identification unit 142 and located at a location relative to the arrival direction of the received signal as a candidate for the source device of the received signal. The source candidate determination unit 143 determines a candidate for the source device of the received signal with reference to the database 13.

In other words, the source candidate determination unit 143 refers to the database 13 and obtains a device corresponding to both the arrival direction of the received signal estimated by the arrival direction estimation unit 141 and the BSS Color specified by the BSS Color identification unit 142. Determined as a candidate for the source device. For example, when the BSS Color is specified as "2" and the estimated arrival direction is the third direction, the source candidate determination unit 143 refers to the table of FIG. 4 and refers to the AP10-2 and the terminal. 20-4 is determined as a candidate for the source device.

The transmission destination candidate determination unit 144 determines the candidate of the transmission destination device of the received signal based on the BSS Color specified by the BSS Color identification unit 142. The transmission destination candidate determination unit 144 selects a wireless communication device among the wireless communication devices belonging to the BSS Color specified by the BSS Color identification unit 142 that the candidate of the source device can perform wireless communication, and is a candidate for the transmission destination device of the received signal. To determine as. The destination candidate determination unit 144 refers to the database 13, and among the wireless communication devices belonging to the specified BSS Color, the candidate of the source device can wirelessly communicate according to the type of the candidate of the source device. The communication device is determined as a candidate for the destination device of the received signal.

For example, when AP10-2 and terminal 20-4 of BSS Color "2" are candidates for the source device, the destination of this received signal is AP10-2, terminal 20-2 and terminal 20-2 belonging to BSS Color "2". It can be seen that the terminal is 20-4. Therefore, in this case, the destination candidate determination unit 144 determines AP10-2, the terminal 20-2, and the terminal 20-4 as the destination device candidates. Further, for example, when the terminal 20-2 of the BSS Color "2" is a candidate for the source device, it can be seen that the transmission destination of this received signal is the AP10-2 belonging to the BSS Color "2". Therefore, in this case, the destination candidate determination unit 144 determines AP10-2 as the destination device candidate.

The selection unit 15 selects a beam in a direction in which the interference power in the candidate of the destination device determined by the transmission destination candidate determination unit 144 is equal to or less than a predetermined value, and transmits a signal from the antenna 11. In other words, the selection unit 15 prohibits the beam in the direction corresponding to the candidate of the destination device determined by the destination candidate determination unit 144. Then, the selection unit 15 selects the wireless communication device of the transmission destination based on the beams in a plurality of directions in which the interference power in the candidate of the transmission destination device is equal to or less than a predetermined value. The selection unit 15 has a beam selection unit 151 and a terminal selection unit 152.

The beam selection unit 151 selects a beam in a direction in which the interference power in the candidate of the transmission destination device is equal to or less than a predetermined value. The beam selection unit 151 selects a beam in a direction in which the interference power in the candidate of the destination device is equal to or less than a predetermined value with reference to the database 13. For example, when the candidate of the destination device is AP10-2 and the terminal 20-4, the beam selection unit 151 refers to the table shown in FIG. 4 and refers to the direction of the arrival direction “3” of the AP10-2. Select a beam with a radiation pattern that has a low antenna gain. For example, the beam selection unit 151 selects beams in the arrival directions “1”, “2” and “4” to “6”, which are directions other than the arrival direction “3” of AP10-2.

When data to be transmitted to the terminal 20 is generated, the terminal selection unit 152 determines whether or not it is possible to form a beam toward the transmission destination terminal 20 based on the direction of the beam selected by the beam selection unit 151. judge. When it is possible to form a beam directed to the destination terminal 20, the terminal selection unit 152 selects a beam directed to the destination terminal 20, instructs the data buffer 16 to transmit data, and selects the beam. Information is output to the transmission processing unit 18. For example, when the direction selected by the beam selection unit 151 includes the direction of the beam used for data transmission to the transmission destination terminal 20, the terminal selection unit 152 points to the transmission destination terminal 20. It is judged that the beam can be formed. On the other hand, when it is difficult to form a beam toward the transmission destination terminal 20, the terminal selection unit 152 waits for data transmission for a predetermined period of time. For example, when the direction selected by the beam selection unit 151 does not include the direction of the beam used for data transmission to the transmission destination terminal 20, the terminal selection unit 152 directs the beam to the transmission destination terminal 20. It is determined that it is difficult to form a beam.

The data buffer 16 stores transmission data output from the upper layer. The data buffer 16 notifies the received data processing unit 14 of the presence / absence of transmission data. Further, the data buffer 16 notifies the terminal selection unit 152 of the information of the terminal 20 as the destination of the transmission data. Further, when the terminal selection unit 152 instructs the data buffer 16 to transmit data, the data buffer 16 outputs the transmission data to the transmission data processing unit 17. Further, when the terminal selection unit 152 notifies the data buffer 16 of the transmission standby, the data buffer 16 waits for the transmission of the transmission data for a predetermined time.

The transmission data processing unit 17 performs processing such as adding a physical header to the transmission data output from the data buffer 16 to generate a transmission signal.

The transmission processing unit 18 performs digital / analog conversion and up-conversion processing on the transmission signal generated by the transmission data processing unit 17. Then, the transmission processing unit 18 performs beamforming processing on the transmission signal so that a beam in a direction corresponding to the information output from the terminal selection unit 152 of the beam selection unit 151 is formed, and the transmission processing unit 18 performs beamforming processing via the antenna 11. , Send to the destination terminal 20.

[Database creation process]
Next, the database creation process in AP10-1 will be described. 5 and 6 are diagrams for explaining the processing of the wireless communication system 1 according to the embodiment. 5 and 6 describe a process in which AP10-1 in the area A1 creates a database. It is assumed that AP10-1 can form beams in six directions in the first to sixth directions (described as (1) to (6) in FIG. 5).

Here, the AP10 of the wireless LAN periodically transmits a beacon signal for notifying the terminal 20 of the existence of its own device by an omnidirectional antenna gain. Therefore, when the AP10-1 receives the beacon signal transmitted from the other AP10, it can be determined that the received signal is a signal from the other AP10.

For example, as shown in FIG. 5, the case where AP10-1 receives the beacon signal W1 transmitted by AP10-2 from the third direction will be described as an example. In FIG. 5, the beam formed in the third direction is filled with hatching.

In this case, the AP10-1 detects that the received power of the antenna element corresponding to the third direction is relatively larger than the received power of the other antenna element, so that the signal arrives from the third direction. Detect that. In addition, AP10-1 acquires BSS Color "2" from the physical header portion of the received signal. Then, AP10-1 refers to the Frame Control bit included in the MAC header portion of the received signal, and determines whether or not the received signal is a beacon signal. In the example of FIG. 5, since the signal received from the third direction is the beacon signal, it is determined that the source device of this beacon signal is another AP10. Further, AP10-1 acquires the identification information (for example, MAC address) of the source device of the beacon signal and the identification information (for example, MAC address) of the destination device from the MAC header portion of the beacon signal. As a result, AP10-1 identifies that the source device of this beacon signal is AP10-2 of BSS Color "2" (see frame Ca in FIG. 5).

Subsequently, the AP10-1 has the BSS Color "2" to which the source device of the beacon signal belongs, the type "AP" of the source device and the identification information "10-2", and the arrival direction "3" among the acquired information. ] Is associated and stored in the database 13. As a result, the information shown in the first line of FIG. 4 is recorded in the database 13.

Subsequently, FIG. 6 is referred to. For example, a case where the signal W2 is transmitted from the terminal 20-2 to the AP10-2 will be described as an example. Since the terminal 20-2 transmits the signal W2 with the omnidirectional antenna gain, the AP10-1 receives the signal W2 transmitted from the terminal 20-2 from the second direction as shown in FIG. .. In FIG. 6, the beam formed in the second direction is filled with hatching.

In this case, the AP10-1 detects that the received power of the antenna element corresponding to the second direction is relatively larger than the received power of the other antenna element, so that the signal arrives from the second direction. Detect that. Further, AP10-1 acquires BSS Color "2" from the physical header portion of the received signal. Then, AP10-1 refers to the Frame Control bit included in the MAC header portion of the received signal, and determines that the received signal is not a beacon signal. Further, AP10-1 acquires the identification information of the source device and the identification information of the transmission destination device of the received signal from the MAC header portion of the received signal. As a result, AP10-1 identifies that the source device of this received signal is the terminal 20-2 of the BSS Color "2" (see frame Cb in FIG. 6).

Subsequently, AP10-1 determines that the source device of the received signal is the terminal 20 because the received signal is not a beacon signal. Then, AP10-1 stores predetermined information among the acquired information in the database 13. Specifically, among the acquired information, the AP10 includes the BSS Color "2" to which the source device of the received signal belongs, the type "terminal" and the identification information "20-2" of the source device, and the arrival direction. The "2" is associated with the database 13 and stored in the database 13. As a result, the information shown in the second line of FIG. 4 is recorded in the database 13.

As described above, the AP10-1 uses the BSS Color acquired from the physical header portion of the signal by the other wireless communication device and the identification information of the source device acquired from the MAC address section in the direction of arrival and the type of the device. It is stored in the database 13 in association with.

[Send processing]
Next, the transmission process in the wireless communication system 1 will be described with reference to FIGS. 7 to 10. 7 to 10 are diagrams for explaining the processing of the wireless communication system 1 according to the embodiment. Hereinafter, with reference to FIGS. 7 to 10, a process in which AP10-1 in the region A1 transmits data to terminals 20-1 and 20-3 belonging to the same BSS Color will be described as an example.

For example, as shown in FIG. 7, it is assumed that the terminal 20-2 transmits a signal to the AP10-2 when the transmission data to the terminals 20-1 and 20-3 is generated in the AP10-1. AP10-1 detects the signal in the second direction as a result of carrier sense. In FIG. 7, the beam formed in the second direction is filled with hatching. AP10-1 detects BSS Color "2" from the physical header portion of the signal received from the terminal 20-2.

Subsequently, the AP10-1 refers to the database 13 in the own device, and transmits the terminal 20-2 (see the frame C1 in FIG. 8) having the BSS Color “2” and the arrival direction “2” as the source device. To determine as. Since the terminal 20-2 wirelessly communicates with the AP10-2, the AP10-1 determines that the destination device of this received signal is the AP10-2 (see frame C2 in FIG. 8).

Therefore, AP10-1 transmits a beam in a direction that does not interfere with the third direction in which AP10-2 arrives (in FIG. 8, the beam formed in the third direction is hatched). select. That is, is AP10-1 prohibiting the beam in the third direction, and is it possible to form a beam in the direction of the terminal 20-1 and the terminal 20-3 from the beams in the directions other than the third direction? Judge whether or not. In the example of FIG. 8, since the beam directed to the terminal 20-1 is in the fourth direction and the beam directed toward the terminal 20-3 is in the second direction, the AP10-1 is the terminal 20-1 and the terminal. It is determined that it is possible to form a beam in the direction of 20-3. Therefore, AP10-1 selects beams in the second and fourth directions. Therefore, the AP10-1 is the terminal 20-1 in the fourth direction and the terminal 20-3 in the second direction, respectively, or one of them (for example, the one with the earlier input to the transmission buffer), as shown by the arrows W4a and W4b. ) Can send data.

In this way, the AP10-1 selects a beam in a direction other than the third direction and transmits data to the terminals 20-1 and 20-3, thereby reducing the interference with the AP10-2 while reducing the interference with the AP10-2. Wireless communication processing can be executed at high speed.

Next, a case where AP10-1 detects a received signal from the third direction as a result of carrier sense will be described with reference to FIGS. 9 and 10. In FIG. 9, the beam formed in the third direction is filled with hatching. AP10-1 receives the physical header part of the signal and detects BSS Color "2" from this physical header part.

Subsequently, AP10-1 refers to the database 13 in the own device, and is the terminal 20-4 (see frame C3 in FIG. 9) having BSS Color “2” and the arrival direction “3” and AP10-2. (See frame C4 in FIG. 9) is determined as a candidate for the source device. The terminal 20-4 wirelessly communicates with the AP10-2 (see arrow W5 in FIG. 10). In addition, AP10-2 wirelessly communicates with terminals 20-2 and 20-4 (see arrows W6a and 6b in FIG. 10). Therefore, AP10-1 determines that the candidates for the destination device of the received signal are AP10-2, terminal 20-2, and terminal 20-4 (see frames C5 to C7 in FIG. 10).

As a result, AP10-1 interferes with the third direction which is the arrival direction of AP10-2, the second direction which is the arrival direction of the terminal 20-2, and the third direction which is the arrival direction of the terminal 20-4. Select a beam in a direction that does not. In FIG. 10, the beams formed in the second and third directions are hatched. That is, AP10-1 prohibits the beam in the second direction and the third direction, and the terminals 20-1 and the terminal 20-3 are among the beams in the directions other than the second direction and the third direction. It is determined whether or not it is possible to form a beam in the direction of. In the example of FIG. 10, since the beam directed to the terminal 20-1 is in the fourth direction and the beam directed toward the terminal 20-3 is in the second direction, the AP10-1 is in the direction of the terminal 20-1. It is determined that it is possible to form a beam in the direction of the terminal 20-3, but it is difficult to form a beam in the direction of the terminal 20-3. Therefore, AP10-1 selects the beam in the fourth direction and waits for a predetermined period of data transmission to the terminal 20-3. As a result, AP10-1 transmits data only to the terminal 20-1 in the fourth direction (see arrow W7a in FIG. 10), and data transmission to the terminal 20-3 in the second direction is stopped (FIG. 10). See arrow W7b).

In this way, the AP10-1 selects beams in directions other than the second and third directions and transmits data only to the terminal 20-1, thereby causing the AP10-2, the terminal 20-2, and the terminal 20 to transmit data. It is possible to execute wireless communication processing at high speed while reducing interference with -4.

[Processing flow in AP]
Next, the flow of data processing in AP10 will be described. FIG. 11 is a flowchart showing the flow of processing in AP10.

As shown in FIG. 11, the AP10 determines whether or not the physical header portion has been received (step S1). Subsequently, when the AP10 determines that the physical header unit has been received (step S1: Yes), the arrival direction estimation unit 141 has the arrival direction of the received signal based on the received power of the received signal measured for each antenna element. Is estimated (step S2).

In parallel with the process of step S2, the BSS Color specifying unit 142 acquires the BSS Color from the physical header unit of the received signal and specifies the BSS Color to which the source device of the received signal belongs (step S3). Further, the BSS Color identification unit 142 identifies the MAC frame unit from the data output from the reception processing unit 12, and acquires the identification information of the source device from the specified MAC header unit. Further, the BSS Color identification unit 142 specifies the type of the source device based on the information of the MAC frame unit. In the example of FIG. 11, the case where steps S2 and S3 are executed in parallel is shown, but steps S2 and S3 may be executed in this order, or steps S3 and S2 may be executed in this order.

Next, the reception data processing unit 14 determines whether or not transmission data exists in the data buffer 16 (step S4). When the reception data processing unit 14 determines that the transmission data does not exist in the data buffer 16 (step S4: No), the transmission processing becomes unnecessary, so the reception data processing unit 14 performs a process for creating the database 13. Specifically, the BSS Color specific unit 142 acquires the identification information of the source device and the destination device from the MAC frame unit of the received signal (step S5). Then, the storage unit 145 stores the identification information of the source device in the database 13 in association with the arrival direction, the type of the source device, and the BSS Color (step S6). Then, the process shown in step S1 is executed again.

On the other hand, when the reception data processing unit 14 determines that the transmission data exists in the data buffer 16 (step S4: Yes), the reception data processing unit 14 performs the following processing for the transmission of the transmission data. First, the source candidate determination unit 143 determines a candidate for the source device using the database 13 from the BSS Color and the arrival direction (step S7). Then, the destination candidate determination unit 143 determines the candidate of the destination device, and the beam selection unit 151 acquires the direction corresponding to the candidate using the database 13 (step S8).

Subsequently, the beam selection unit 151 selects a beam other than the beam corresponding to the direction of the destination candidate as the beam in the direction in which the interference power in the candidate of the destination device is equal to or less than a predetermined value (step S9). Then, the terminal selection unit 152 determines whether or not it is possible to form a beam toward the transmission destination terminal 20 based on the direction of the beam selected by the beam selection unit 151. When it is possible to form a beam directed to the destination terminal 20, the terminal selection unit 152 selects a beam directed to the destination terminal 20, instructs the data buffer 16 to transmit data, and selects the beam. Is output to the transmission processing unit 18 (step S10). If it is difficult to form a beam toward the destination terminal 20, the terminal selection unit 152 waits for data transmission for a predetermined period of time. Then, the AP 10 transmits a signal from the antenna 11 after processing the transmission data by the transmission data processing unit 17 and the transmission processing unit 18 (step S11). Then, the process shown in step S1 is executed again.

Further, when the AP10 determines that the physical header unit has not been received (step S1: No), the reception data processing unit 14 determines whether or not the transmission data exists in the data buffer 16 (step S12). .. When the reception data processing unit 14 determines that the transmission data exists in the data buffer 16 (step S12: Yes), the AP 10 executes data transmission using the beam directed to the transmission destination terminal 20 (step S13). .. On the other hand, when the received data processing unit 14 determines that the transmission data does not exist in the data buffer 16 (step S12: No), the process shown in step S1 is executed again.

[Data transmission timing]
Here, the data transmission timing between the AP 10 and the conventional AP will be described with reference to FIGS. 12 and 13. FIG. 12 is a diagram illustrating data transmission timing in the prior art. FIG. 13 is a diagram for explaining the data transmission timing in this embodiment.

In the conventional AP, in order to transmit data in a direction of reducing interference with other devices at the time of data transmission, the MAC addresses of the source device and the destination device have been acquired from the received signal by the other device. Therefore, as shown in FIG. 12, the conventional AP receives up to the MAC frame portion of the frame Dr1'transmitted from another device. That is, it is difficult for the conventional AP to determine the communication prohibition direction unless the frame Dr1'is received until the end.

Therefore, it is difficult for the conventional AP to transmit the frame Ds'for transmission data only after all the reception times T1 of the frame Dr1' have elapsed, and there is a limit in speeding up the communication processing.

On the other hand, in AP10 of this embodiment, the direction of reducing the interference with other devices by acquiring the BSS Color of the physical header portion instead of the MAC addresses of the source device and the destination device is selected. .. That is, as shown in FIG. 13, the AP10 can determine the communication prohibition direction by receiving up to the physical header portion of the frame Dr1 transmitted from another device.

Therefore, the AP10 of the present embodiment can transmit the frame Ds for transmission data by executing the determination process of the communication prohibition direction at the reception time T2 (<T1) to the physical header portion of the frame Dr1. .. Therefore, the AP10 of the present embodiment can speed up the communication process while reducing the interference with other devices as compared with the conventional AP.

[Effect of Examples]
In the wireless communication system 1 of the present embodiment, a signal including a BSS Color to which the source device of the signal belongs is wirelessly communicated in the physical header portion of the signal. When the AP10 of this embodiment receives the physical header part of the signal, it acquires the BSS Color from the physical header part of the received signal and identifies the BSS Color to which the source device of the received signal belongs. Then, the AP10 determines the candidate of the destination device of the received signal based on the specified BSS Color. Subsequently, the AP 10 selects a beam in a direction in which the interference power in the candidate of the transmission destination device is equal to or less than a predetermined value, and causes the antenna 11 to transmit a signal.

As described above, the AP10 of the present embodiment selects the beam direction for reducing the interference power with the signal by the other device based on the information in the physical header portion of the received signal. As a result, faster wireless communication processing can be executed and given to other devices as compared with the case where the beam direction for reducing the interference power with the signal by the other device is selected after receiving the entire received signal. Interference can also be reduced.

Further, the AP10 of this embodiment estimates the arrival direction of the received signal based on the received power of the received signal. Then, the AP10 determines a wireless communication device belonging to the specified BSS Color and located at a location relative to the arrival direction of the received signal as a candidate for the source device of the received signal. Subsequently, the AP10 determines, among the wireless communication devices belonging to the specified BSS Color, a wireless communication device capable of wireless communication as a candidate for the source device as a candidate for the destination device for the received signal.

In this way, the AP10 determines as a candidate for the source device and a candidate for the destination device of the received signal from the arrival direction of the received signal estimated to be BSS Color, so that interference with the signal by other devices can be reduced. Can be done.

Further, the AP10 of this embodiment sets the identification information of the other device, the type of the other device, the identification information of the group to which the other device belongs, and the direction of arrival of the beam by the other device in the own device for each device. It is associated and stored in the database 13. Then, the AP 10 refers to the database 13 to determine a candidate for the source device of the received signal. Further, the AP10 refers to the database 13 and selects a device that can wirelessly communicate with the source device candidate according to the type of the source device candidate among the devices belonging to the specified BSS Color. Determined as a candidate for the destination device.

As described above, the AP10 of the present embodiment holds the above database 13 and can determine the transmission destination candidate of the source device by referring to the database 13.

Further, the AP10 of the present embodiment obtains the identification information of the source device of the received signal obtained from the MAC frame unit when the received signal is received up to the MAC frame unit. Then, the AP 10 stores the identified information of the source device of the obtained received signal in the database 13 in association with the BSS Color obtained from the physical header unit, the estimated arrival direction, and the type of the source device.

As described above, the AP10 of the embodiment receives the MAC frame portion of the received signal by another device as appropriate except at the time of data transmission. Then, in addition to the information read from the physical frame unit, the AP 10 stores the identification information and type of the source device read from the MAC frame unit, and the arrival direction of the received signal in the database 13. As a result, the AP10 can create an appropriate database 13 and can update the data in the database 13.

Further, the AP10 of the embodiment selects a beam in a direction in which the interference power in the candidate of the transmission destination device is equal to or less than a predetermined value, and selects the terminal 20 of the transmission destination based on the selected beam. Therefore, when there are a plurality of terminals 20 to be data transmitted, the AP 10 does not transmit data to all the terminals 20, but selects the terminal 20 to be transmitted based on the selected beam. Allows the device to reduce interference with the signal. Further, the AP10 can flexibly set the transmission target according to the selected beam, such as transmitting data to the terminal 20 whose gain is larger than a predetermined value among the selected beams.

[Modification 1]
This embodiment can be applied to devices other than AP10 as long as it is a device that performs beamforming processing to perform wireless communication. This embodiment may be applied to, for example, the terminal 20 facing the AP10.

[Modification 2]
Further, in the present embodiment, an example in which the AP10 determines the candidate of the destination device by using the arrival direction of the received signal in addition to the BSS Color acquired from the physical header part of the received signal has been described. Not limited to this. The AP10 may determine the candidate of the destination device using only the BSS Color acquired from the physical header portion of the received signal.

In this case, the AP10 determines all the AP10s and terminals 20 belonging to the acquired BSS Color as candidates for the destination device. Then, the AP10 may select a beam direction that reduces the interference power with the signal by all the AP10s belonging to this BSS Color and the terminal 20.

For example, in the example shown in FIG. 7, when AP10-1 acquires BSS Color "2" from the physical header portion of the received signal, all AP10-2 and terminals 20-2 belonging to this BSS Color "2", 20-4 is a candidate for the destination device. Then, the AP10 emits a beam from the first, fourth to sixth directions other than the third direction corresponding to the AP10-2 and the terminal 20-4 and the second direction corresponding to the terminal 20-2. Select it and send the data.

In this way, when the AP 10 determines the candidate of the destination device using only the BSS Color, it is not necessary to associate the arrival direction with the database 13, so that the capacity of the database 13 can be reduced. Further, in this case, since the AP10 can omit the process of estimating the arrival direction, the process up to the data transmission can be simplified.

Further, in the above-described embodiment, the wireless communication system 1 in which a plurality of terminals 20 perform wireless communication with the AP 10 has been exemplified, but the disclosed technology is not limited to this. The wireless communication system 1 of the embodiment may be configured such that one terminal 20 wirelessly communicates with the AP 10.

[AP hardware]
The AP10 of each of the above-described embodiments is realized by hardware as shown in FIG. 14, for example. FIG. 14 is a diagram showing a configuration example of the hardware of AP10. The AP10 has a processor 101, a memory 102, a wireless communication module 103, and an interface circuit 104 as hardware components, for example, as shown in FIG. The processor 101 is, for example, a CPU (Central Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or the like. Further, the AP 10 may have an LSI (Large Scale Integrated circuit) including the processor 101 and peripheral circuits. The memory 102 is, for example, a RAM such as an SDRAM (Synchronous Dynamic Random Access Memory), a ROM (Read Only Memory), a flash memory, or the like.

The reception processing unit 12 and the transmission processing unit 18 are realized by the wireless communication module 103. The reception data processing unit 14, the selection unit 15, and the transmission data processing unit 17 are realized by the processor 101. The database 13 and the data buffer 16 are realized by the memory 102. The data or the like used by the processor 101 is stored in the memory 102. The interface circuit 104 is realized by, for example, a NIC (Network Interface Card) or the like.

1 Wireless communication system 10,10-1,10-2 AP
11 Antenna 12 Reception processing unit 13 Database 14 Reception data processing unit 15 Selection unit 16 Data buffer 17 Transmission data processing unit 18 Transmission processing unit 20, 20-1 to 20-4 Terminal 141 Arrival direction estimation unit 142 BSS Color Specific unit 143 Transmission Original candidate determination unit 144 Destination candidate determination unit 145 Storage unit 151 Beam selection unit 152 Terminal selection unit

Claims (6)

An antenna that transmits and receives a signal in which the identification information of the group to which the source device of the signal belongs is included in the physical header portion of the signal.
When the antenna receives the physical header part of the signal, the group identification part that acquires the identification information of the group from the physical header part of the received signal and specifies the group to which the source device of the received signal belongs, and the group identification part.
A storage unit that stores the identification information of the other wireless communication device and the identification information of the group to which the other wireless communication device belongs in association with the arrival direction of the signal transmitted from the other wireless communication device in the own device. When,
A transmission destination candidate determination unit that refers to the storage unit and determines the direction of a candidate of the transmission destination device of the received signal based on the arrival direction associated with the group specified by the group identification unit.
A selector interference power in the direction of a candidate of the destination device you select a beam of the radiation pattern equal to or less than a predetermined value,
A wireless communication device including a transmission processing unit that transmits a signal using a beam of a radiation pattern selected by the selection unit. An arrival direction estimation unit that estimates the arrival direction of the received signal based on the received power of the received signal, and an arrival direction estimation unit.
Referring to the storage unit, belonging to the group identified by the group identifying unit, a wireless communication device located in a location that corresponds to the direction of arrival of the received signal is determined as a candidate of the transmission source device of the received signal Source candidate determination department and
Have more
The storage unit further stores the type of the other wireless communication device in association with the arrival direction of the signal transmitted from the other wireless communication device in the own device.
The destination candidate determination unit can wirelessly communicate with the candidate of the source device among the wireless communication devices belonging to the group specified by the group identification unit with reference to the type stored in the storage unit. The wireless communication device according to claim 1 , wherein the direction of the wireless communication device is determined as a candidate direction of the destination device for the received signal. Identification information of another wireless communication device that is the source of the received signal obtained from the MAC frame section when the received signal is received up to the MAC (Media Access Control) frame section, and group identification information obtained from the physical header section. , the type of the transmission source of the other wireless communication device on the receiving signal obtained from the type of the received signal, in association with been DOA estimated by the arrival direction estimation unit, storage unit for storing in said storage unit The wireless communication device according to claim 2, further comprising. The selection unit uses a radiation pattern when transmitting a signal from its own device to another wireless communication device from among a beam of a plurality of radiation patterns in which the interference power in the direction of the candidate of the destination device is equal to or less than a predetermined value. The wireless communication device according to any one of claims 1 to 3, wherein the wireless communication device is selected. A wireless communication system having a plurality of wireless communication devices including a base station and a plurality of terminals that perform wireless communication with the base station.
The base station
An antenna that transmits and receives a signal in which the identification information of the group to which the source device of the signal belongs is included in the physical header portion of the signal.
When the antenna receives the physical header part of the signal, the group identification part that acquires the identification information of the group from the physical header part of the received signal and specifies the group to which the source device of the received signal belongs, and the group identification part.
The identification information of the wireless communication device other than the base station and the identification information of the group to which the other wireless communication device belongs correspond to the arrival direction of the signal transmitted from the other wireless communication device in the base station. A storage unit that can be attached and stored,
A transmission destination candidate determination unit that refers to the storage unit and determines the direction of a candidate of the transmission destination device of the received signal based on the arrival direction associated with the group specified by the group identification unit.
A selector interference power in the direction of a candidate of the destination device you select a beam of the radiation pattern equal to or less than a predetermined value,
A wireless communication system including a transmission processing unit that transmits a signal using a beam of a radiation pattern selected by the selection unit. The wireless communication device
A signal including the identification information of the group to which the source device of the signal belongs is received in the physical header part of the signal, and the signal is received.
The identification information of the group is acquired from the physical header portion of the received signal, and the group to which the source device of the received signal belongs is specified.
A storage unit that stores the identification information of the other wireless communication device and the identification information of the group to which the other wireless communication device belongs in association with the arrival direction of the signal transmitted from the other wireless communication device in the own device. The direction of the candidate of the destination device of the received signal is determined based on the arrival direction associated with the specified group.
A beam having a radiation pattern in which the interference power in the direction of the candidate of the destination device is equal to or less than a predetermined value is selected.
Send a signal with a beam of selected radiation pattern,
A wireless communication method characterized by performing processing.

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