JP5744987B2 - Method and apparatus for performing direction search and wireless communication using a plurality of wireless channels in a wireless communication system - Google Patents

Description

  The present invention relates to wireless communication, and more particularly, to a method and apparatus for performing direction search and wireless communication using a plurality of frequency bands, that is, a plurality of wireless channels, in a wireless communication system.

  Along with the development of wired and wireless communication technology, an environment is established where various communication devices can connect to a broadband communication network and receive services anytime and anywhere on the ground. However, the maritime communication system has a relatively slow development speed despite the very old communication. Most maritime communication systems are limited to voice-centric communication services except for simple character transmission services.

  It is difficult to construct an infrastructure for wired communication at sea, and there is no choice but to rely on services centered on wireless communication. Maritime communication is based on the limit of radio frequency coverage, MF (Medium Frequency), HF (High Frequency), VHF (Very High). Frequently, ships that operate over long distances rely on expensive satellite communications.

  In the maritime communication field to which such a marine communication system is applied, GMDSS (Global Maritime Distress and Safety System) has been implemented since the end of the 1990s. For the safety of life at sea, GMDSS uses digital communication technology, satellite communication technology, etc. to navigate the ship to land rescue organizations and neighbors from any ship in the world. It is a system that makes it possible to promptly and accurately rescue a ship, and to appropriately receive information on navigation safety from the land.

  Recently, the International Maritime Organization (IMO) has established a strategy for developing E-Navigation. E-Navigation utilizes a Ship Automatic Identification System (AIS) that enables a variety of information related to ship characteristics, cargo, operations, etc. to be transmitted and received in real time. A method that can be collected, integrated, exchanged, represented and analyzed. By utilizing this, it is possible to construct an international ITS (International Transport System) that can accept data and multimedia.

  In addition, communication technologies such as wireless local area networks (WLANs) and WiMAX (World Interoperability for Microwave Access) reflecting recent radio wave technologies are being considered for modernization of maritime communications on ports and ships. Recently, AIS using the VHF band linked with satellites has emerged as an offshore infrastructure communication network.

  The technical problem of the present invention is to provide a method and apparatus for searching for a wireless communication direction in a wireless communication system.

  Another technical problem of the present invention is to provide a method and apparatus for performing wireless communication in a wireless communication system.

  Another technical problem of the present invention is to provide a method and apparatus for searching for a wireless communication direction using a plurality of directional antennas.

  Another technical problem of the present invention is to provide a method and apparatus for searching for a wireless communication direction using a plurality of frequency bands.

  Another technical problem of the present invention is to provide a method and apparatus for performing wireless communication using a directional antenna.

  Another technical problem of the present invention is to provide a communication method and apparatus capable of obtaining a frequency diversity effect in an environment where a change in received intensity by distance due to a frequency is severe due to interference of reflected seawater waves on the sea. It is to be.

  Another technical problem of the present invention is to provide a method and an apparatus for searching for a wireless communication direction using a low frequency with a long communication distance.

  Another object of the present invention is to provide a method and apparatus for performing direction search and wireless communication using a plurality of wireless channels in a wireless communication system used at sea.

  According to one embodiment of the present invention, a wireless communication apparatus including a plurality of directional antennas is provided. The apparatus includes a plurality of directional antennas including a first directional antenna group using a frequency band A and a second directional antenna group using a frequency band B in different directions. A first RSS measurement unit that measures RSS # 1, which is the received signal strength of each of the directional antennas constituting the directional antenna group, and the received signal of each of the directional antennas constituting the second directional antenna group A second RSS measurement unit that measures RSS # 2, which is the strength, and a directional antenna having the highest received signal strength among the directional antennas constituting the first directional antenna group based on RSS # 1 The first antenna selection unit that selects the directional antennas that constitute the second directional antenna group based on the RSS # 2 A second antenna selection unit that selects a directional antenna having a high signal strength, a first communication unit that executes a first radio communication using the frequency band A, and a second radio that uses the frequency band B. A second communication unit that executes communication, and a first unit that controls connection between a directional antenna selected from directional antennas constituting the first directional antenna group and the first communication unit. Antenna switch, and a second antenna switch that controls connection between the directional antenna selected from the directional antennas constituting the second directional antenna group and the second communication unit. It is characterized by that.

  According to another aspect of the present invention, a wireless communication apparatus including a plurality of directional antennas is provided. The apparatus includes a plurality of directional antennas including a first directional antenna group using a frequency band A and a second directional antenna group using a frequency band B in different directions, and the first directional antenna. A first RSS measurement unit that measures RSS # 1, which is a received signal strength of each of the directional antennas constituting the directional antenna group, and a received signal strength of each of the directional antennas constituting the second directional antenna group A second RSS measurement unit that measures RSS # 2, a first communication unit that performs radio communication using frequency band A, and a second communication unit that performs radio communication using frequency band B Based on the RSS # 1 and RSS # 2, the directional antennas constituting the first directional antenna group and the directional antennas constituting the second directional antenna group. Communication using a specific directional antenna selected from a tenor and using the same frequency band as the frequency band used by the selected specific directional antenna from among the first communication unit and the second communication unit A selection unit that selects a unit, and an antenna switch that controls connection between the selected specific directivity antenna and a communication unit selected from the first communication unit and the second communication unit It is characterized by.

  According to another aspect of the present invention, a wireless communication apparatus including a plurality of directional antennas is provided. The apparatus includes a plurality of directional antennas including a first directional antenna group using a frequency band A and a second directional antenna group using a frequency band B in different directions, and the first directional antenna. A first RSS measurement unit that measures RSS # 1, which is the received signal strength of each of the directional antennas that constitute the directional antenna group, and the directivity that constitutes the first directional antenna group based on the RSS # 1 The directivity which confirms the direction of a received signal based on the direction which the confirmed directional antenna goes to confirms the directional antenna with the largest received signal strength among the antennas, and constitutes the second directional antenna group An antenna selection unit that selects a directional antenna whose azimuth includes the direction of the received signal from among the antennas, the second radio using the frequency band B Communication unit for executing signal, and characterized in that it comprises an antenna switch for controlling the connection between the selected directional antenna and the communication unit.

  According to another aspect of the present invention, a wireless communication method for a wireless communication apparatus including a plurality of directional antennas is provided. The method measures RSS # 1, which is the received signal strength of the first directional antenna using the frequency band A in different directions, and uses the frequency band B in different directions. Measuring RSS # 2, which is the received signal strength of the second directional antenna, and based on the measured RSS # 1 and RSS # 2, the first directional antenna and the second directional antenna Selecting a directional antenna having the highest received signal strength from among the first communication unit using the frequency band A and the second using the frequency band B included in the wireless communication device. Among the communication units, a step of connecting a communication unit that uses the same frequency band as that used by the selected directional antenna to the selected directional antenna. , And a step of performing wireless communication by using at least one directional antenna and the connected communication unit said selected.

  According to the present invention, it is possible to detect a transmission / reception direction of a radio signal, that is, a direction of a communication target through a plurality of frequency bands even in a marine communication environment where a change in reception intensity according to distance is severe due to interference of a sea surface reflected wave. And frequency diversity can be obtained in wireless communication.

  In addition, according to the present invention, even when the target is far away, the direction of the communication target is detected using a low frequency band (for example, 2.4 GHz) having a long communication distance, and more data can be transmitted. Thus, wireless communication can be performed using a high frequency band (for example, 5.8 GHz) that is less affected by interference.

2 shows an example of a plurality of directional antenna arrangements according to the present invention. 6 shows another example of a plurality of directional antenna arrangements according to the present invention. 1 shows an example of a wireless communication device including a plurality of directional antennas according to the present invention. 6 shows another example of a wireless communication device including a plurality of directional antennas according to the present invention. 6 shows another example of a wireless communication device including a plurality of directional antennas according to the present invention. 6 is a flowchart illustrating an example of a method for performing wireless communication by a wireless communication apparatus including a plurality of directional antennas according to the present invention.

  Hereinafter, some embodiments of the present invention will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components have the same reference numerals as much as possible even if they are displayed on other drawings. . Further, in describing the embodiments of the present invention in this specification, when it is determined that a specific description of a related known configuration or function makes the gist of the present specification unclear, the detailed description thereof is omitted. .

  In describing the components of the present specification, terms such as first, second, A, B, (a), and (b) can be used. Such terms are merely for distinguishing the constituent elements from other constituent elements, and the essence and order of the corresponding constituent elements are not limited by the terms. When a component is described as being “coupled”, “coupled” or “connected” to another component, the component may be directly coupled or connected to another component. It should be understood that other components can be “coupled”, “coupled” or “connected” between each component.

  In the present invention, a directional antenna having an arbitrary azimuth and elevation is used. Communication in the VLF and HF bands uses reflected waves from the ionosphere, and communication in the LF and MF bands allows communication up to several hundred kilometers away using surface waves (ground wave). It is. However, since the ionospheric reflection does not occur in the VHF / UHF / SHF band, communication can be performed via direct waves using the troposphere and reflected waves from the ground surface. Therefore, there is a need to use a directional antenna having directionality.

  In the present invention, the plurality of directional antennas are directed in different directions. The plurality of directional antennas may be disposed so as to surround a fixed rotation axis. For example, four directional antennas having an azimuth angle of 90 degrees (when the number of the plurality of directional antennas is n, n = 4, the same applies hereinafter) surround a fixed rotation axis and are directed in different directions. Can be arranged as follows. Alternatively, six (n = 6) directional antennas having an azimuth angle of 60 degrees may be arranged so as to surround a fixed rotation axis and be directed in different directions. The azimuth and number of directional antennas are merely examples, and directional antennas with larger or smaller azimuths may be used to implement the present invention, with fewer or more numbers. Of course, directional antennas can also be used. In addition, the directional antenna may alternately use two or more specific frequency bands in a clockwise or counterclockwise direction, and two or more antennas using different specific frequency bands may be used. They can also be arranged one above the other.

  As an example, the directional antenna is composed of antenna directional antenna groups that use a specific frequency band, and uses one antenna of the directional antenna group (ANT_A) that uses the frequency band A and the frequency band B. One antenna of the directional antenna group (ANT_B) can be alternately arranged. In this case, it is natural that the number of directional antennas constituting ANT_A may be different from the number of directional antennas constituting ANT_B.

  As another example, the directional antenna using the frequency band A and the directional antenna using the frequency band B form a group (ANT_AB), and a plurality of ANT_AB1, ANT_AB2,. The directional antenna using the frequency band A of the ANT_AB and the directional antenna using the frequency band B can be arranged in pairs in the vertical and horizontal directions or the diagonal direction.

  Here, the use of a specific frequency band by the directional antenna means that a communication module (for example, an RF module) transmits and receives signals using a specific frequency band by the directional antenna. The same applies hereinafter.

  For example, when the plurality of directional antennas include a directional antenna that uses the frequency band A and a directional antenna that uses the frequency band B, the directivity that uses the frequency band A among the plurality of directional antennas. The directional antenna and the directional antenna using the frequency band B can be alternately arranged in the clockwise direction or the counterclockwise direction. Specifically, it will be described with reference to the drawings.

  FIG. 1 shows an example of a plurality of directional antenna arrangements according to the present invention. Here, A indicates that the corresponding antenna uses the frequency band A, and B indicates that the corresponding antenna uses the frequency band B.

  Referring to FIG. 1, four directional antennas 101, 102, 103, and 104 are arranged so as to surround a fixed rotation axis and are directed in different directions. Preferably, the four directional antennas 101, 102, 103, 104 can be directed in an external direction around the constant rotation axis. Each of the four directional antennas 101, 102, 103, 104 can perform communication within a certain azimuth angle. The four directional antennas 101, 102, 103, 104 are sequentially arranged in the clockwise direction, and use the frequency band A and the frequency band B alternately. That is, the directional antenna 101 uses the frequency band A, the directional antenna 102 uses the frequency band B, the directional antenna 103 uses the frequency band A, and the directional antenna 104 uses the frequency band B.

  FIG. 2 shows another example of a plurality of directional antenna arrangements according to the present invention. Here, A indicates that the corresponding antenna uses the frequency band A, and B indicates that the corresponding antenna uses the frequency band B.

  Referring to FIG. 2, six directional antennas 201, 202, 203, 204, 205, and 206 are arranged so as to surround a fixed rotation axis and are directed in different directions. Preferably, the six directional antennas 201, 202, 203, 204, 205, and 206 can be directed in an external direction around the constant rotation axis. The plurality of directional antennas 201, 202, 203, 204, 205, and 206 can each perform communication within a certain azimuth angle. The six directional antennas 201, 202, 203, 204, 205, 206 are sequentially arranged in the clockwise direction, and use the frequency band A and the frequency band B alternately. That is, the directional antenna 201 uses the frequency band A, the directional antenna 202 uses the frequency band B, the directional antenna 203 uses the frequency band A, the directional antenna 204 uses the frequency band B, The directional antenna 205 uses the frequency band A, and the directional antenna 206 uses the frequency band B.

  In the example of FIGS. 1 and 2, only two frequency bands A and B (when m is the number of frequency bands to be used, m = 2, the same applies hereinafter) are used, but this is only an example. In some cases, three or more (m ≧ 3) frequency bands may be used alternately. In the example of FIGS. 1 and 2, the directional antenna using the frequency band A and the directional antenna using the frequency band B are sequentially arranged at a certain angle, but this is only an example. The directional antenna using the frequency band A and the directional antenna using the frequency band B form a group (ANT_AB), and a plurality of ANT_ABs are arranged around the fixed rotation axis, and the frequency band A of the ANT_AB is defined. The directional antenna to be used and the directional antenna using the frequency band B can be arranged in pairs in the vertical and horizontal directions or the diagonal direction.

  The above-described directional antenna is included in the wireless communication apparatus according to the present invention. The wireless communication device can perform wireless communication by searching for a wireless communication direction at sea via the directional antenna.

  FIG. 3 shows an example of a wireless communication apparatus including a plurality of directional antennas according to the present invention.

  Referring to FIG. 3, a wireless communication apparatus according to the present invention includes a plurality of directional antennas 300, a first RSS measurement unit 310, a second RSS measurement unit 320, a first antenna selection unit 330, and a second antenna selection. Part 340, first antenna switch 350, second antenna switch 360, first communication part 370, and second communication part 380.

  As described above, the plurality of directional antennas 300 are arranged so as to surround a fixed rotation axis, and can sequentially use a plurality of different frequencies in different directions. FIG. 3 shows a case where the plurality of directional antennas 300 include six directional antennas 301, 302, 303, 304, 305, and 306, and the plurality of directional antennas 300 include frequency band A and frequency band. The case where B is used alternately is shown. For example, the frequency band A is a 2.4 GHz band, and the frequency band B is a 5.8 GHz band. Specifically, the directional antenna 301 uses the frequency band A, the directional antenna 302 uses the frequency band B, the directional antenna 303 uses the frequency band A, and the directional antenna 304 uses the frequency band B. The directional antenna 305 uses the frequency band A, and the directional antenna 306 uses the frequency band B. In this case, a set of directional antennas 301, 303, and 305 using the frequency band A is called a first antenna group, and a set of directional antennas 302, 304, and 306 using the frequency band B is It can be referred to as a second antenna group.

  The first RSS measurement unit 310 measures RSS # 1 which is a received signal strength (RSS: Received Signal Strength) of the directional antennas 301, 303, and 305 included in the first antenna group. The second RSS measurement unit 320 measures RSS # 2, which is the received signal strength of the directional antennas 302, 304, and 306 included in the second antenna group. Here, the received signal strength (for example, RSS # 1 and RSS # 2) can indicate an average value of the signal strength received during a certain time. The same applies hereinafter.

  The first antenna selection unit 330 determines the frequency based on RSS # 1 that is the received signal strength of the directional antennas 301, 303, and 305 included in the first antenna group measured by the first RSS measurement unit 310. From the directional antennas 301, 303, and 305 that use the band A, the directional antenna # 1 that is the directional antenna having the highest received signal strength is selected. The second antenna selection unit 340 determines the frequency based on RSS # 2, which is the received signal strength of the directional antennas 302, 304, and 306 included in the second antenna group measured by the second RSS measurement unit 320. From the directional antennas 302, 304, and 306 that use the band B, the directional antenna # 2 that is the directional antenna having the highest received signal strength is selected.

  The first antenna switch 350 controls the connection between the directional antenna selected by the first antenna selection unit 330 and the first communication unit 370. As an example, an antenna selection signal # 1 indicating the selected directional antenna # 1 is received from the first antenna selection unit 330, and based on this, between the directional antenna # 1 and the first communication unit 370. Controls the connection of As another example, in some cases, when the first antenna selection unit 330 reselects an arbitrary directional antenna from the directional antennas 301, 303, and 305 included in the first antenna group, The antenna switch 350 controls connection between the reselected other directional antenna and the first communication unit 370.

  The second antenna switch 360 controls connection between the directional antenna selected by the second antenna selection unit 340 and the second communication unit 380. The second antenna switch 360 receives the antenna selection signal # 2 indicating the directional antenna # 2 selected from the second antenna selection unit 340, and sets the directional antenna # 2 to the second directional antenna # 2 based on this. The communication unit 380 is connected. In some cases, when the second antenna selection unit 340 reselects an arbitrary directional antenna from the directional antennas 302, 304, and 306 included in the second antenna group, the second antenna switch 360 is selected. Controls the connection between the re-selected other directional antenna and the second communication unit 380.

  The first communication unit 370 performs wireless communication via the directional antenna # 1. The first communication unit 370 can transmit and receive at least one of voice and data information using the frequency band A. The second communication unit 380 performs wireless communication via the directional antenna # 2. The second communication unit 380 can transmit and receive at least one of voice and data information using the frequency band B.

  According to the present invention, the direction in which a radio signal is received can be detected by independently measuring and comparing the received signal strength (RSS) of signals received in frequency band A and frequency band B. In addition, since it is possible to perform radio communication by selecting a directional antenna having the highest received signal strength for each frequency band, it is possible to obtain frequency diversity.

  On the other hand, the first communication unit 370 measures the SNR # 1 (Signal to Noise Ratio) indicating the signal-to-noise ratio of the received signal when performing wireless communication via the directional antenna # 1. The transmitted SNR # 1 can be transmitted to the first antenna selection unit 330. When the value of the SNR # 1 is below a certain limit, the first antenna selection unit 330 is based on the current received signal strength of the directional antennas 301, 303, and 305 included in the antenna group of the frequency band A. The directional antenna having the highest received signal strength can be reselected from among the directional antennas 301, 303, and 305 that use the frequency band A. Similarly, when the second communication unit 380 performs wireless communication via the directional antenna # 2, the second communication unit 380 measures the SNR # 2 indicating the signal-to-noise ratio of the received signal, and the measured SNR # 2 2 antenna selection unit 340. When the value of the SNR # 2 is equal to or less than a certain limit, the second antenna selection unit 340 is based on the current received signal strength of the directional antennas 302, 304, and 306 included in the antenna group of the frequency band B. The directional antenna having the highest received signal strength can be reselected from among the directional antennas 302, 304, and 306 that use the frequency band B.

  As an example, the first RSS measurement unit 310 measures the RSS # 1 periodically or aperiodically, and the first antenna selection unit 330 determines that the value of the SNR # 1 is less than a certain limit. In some cases, a directional antenna having the highest received signal strength can be reselected from among the directional antennas constituting the first directional antenna group based on the RSS # 1 measured most recently. Similarly, the second RSS measurement unit 320 measures the RSS # 2 periodically or aperiodically, and the second antenna selection unit 340 determines that the value of the SNR # 2 is less than a certain limit. In some cases, the directional antenna having the highest received signal strength can be reselected from among the directional antennas constituting the second directional antenna group based on the RSS # 2 measured most recently.

  As another example, when the value of the SNR # 1 is equal to or less than a certain limit, the first RSS measurement unit 310 remeasures the RSS # 1, and in this case, the first antenna selection unit 330 Based on the re-measured RSS # 1, the directional antenna having the highest received signal strength can be reselected from among the directional antennas constituting the first directional antenna group. Similarly, the second RSS measurement unit 320 re-measures the RSS # 2 when the value of the SNR # 2 is equal to or less than a predetermined limit. In this case, the second antenna selection unit 340 Based on the remeasured RSS # 2, the directional antenna having the highest received signal strength can be reselected from among the directional antennas constituting the second directional antenna group.

  Meanwhile, each of the first communication unit 370 and the second communication unit 380 can operate independently, and any one of the first communication unit 370 and the second communication unit 380 can be operated. It can also operate selectively only.

  In FIG. 3, the first communication unit 370 for the frequency band A and the second communication unit 380 for the frequency band B are shown independently. However, the first communication unit 370 and the second communication unit 380 are It is configured by one unit, and wireless communication with respect to the frequency band A or the frequency band B can be selectively executed.

  FIG. 4 shows another example of a wireless communication apparatus including a plurality of directional antennas according to the present invention.

  Referring to FIG. 4, the wireless communication apparatus according to the present invention includes a plurality of directional antennas 400, a first RSS measurement unit 410, a second RSS measurement unit 420, a selection unit 430, an antenna switch 450, and a first communication unit. 470, a second communication unit 480, and a communication unit switch 490.

  The description of the plurality of directional antennas 400, the first RSS measurement unit 410, the second RSS measurement unit 420, the first communication unit 470, and the second communication unit 480 includes the content described in FIG. In the following, the description will be made mainly on different configurations as follows.

  The selection unit 430 includes the RSS # 1 and the second reception signal strength of the directional antennas 401, 403, and 405 included in the first antenna group that uses the frequency band A measured by the first RSS measurement unit 410. The specific directional antenna is selected based on RSS # 2 that is the received signal strength of the directional antennas 402, 404, and 406 included in the second antenna group that uses the frequency band B measured by the RSS measuring unit 420. The selected specific directional antenna is any one of the plurality of directional antennas 400.

  As an example, the selection unit 430 can select a directional antenna having the highest received signal strength among the plurality of directional antennas 400 as the specific directional antenna. In this case, the selection unit 430 checks the frequency band used by the directional antenna having the highest received signal strength. That is, the selection unit 430 checks whether the frequency band used by the directional antenna having the highest received signal strength is the frequency band A or the frequency band B. Thereafter, the selection unit 430 selects a communication unit that uses the confirmed frequency band from the first communication unit 470 and the second communication unit 480, and designates the selected communication unit. Is transmitted to the communication unit switch 490.

  For example, when the frequency band used by the directional antenna with the highest received signal strength is frequency band A, the selection unit 430 transmits a communication unit selection signal instructing the first communication unit 470 to the communication unit switch 490. When the frequency band used by the directional antenna having the highest received signal strength is the frequency band B, a communication unit selection signal for instructing the second communication unit 480 is transmitted to the communication unit switch 490. Based on the communication unit selection signal, the communication unit switch 490 transmits voice and data information to a communication unit (for example, at least one of the first communication unit 470 and the second communication unit 480) indicated by the selection signal. At least one of them can be transmitted.

  In addition, the selection unit 430 transmits an antenna selection signal indicating the selected directional antenna and the selected communication unit to the antenna switch 450. The antenna switch 450 connects the selected directional antenna and the selected communication unit.

  For example, when the directional antenna having the highest received signal strength is the directional antenna 403, the selection unit 430 selects the directional antenna 403, and the frequency band used by the directional antenna 403 is the frequency band A. The communication unit selection signal for instructing the first communication unit 470 using the frequency band A is transmitted to the communication unit switch 490. The selection unit 430 transmits an antenna selection signal that instructs the directional antenna 403 and the first communication unit 470 to the antenna switch 450. In this case, the antenna switch 450 connects the directional antenna 403 and the first communication unit 470.

  Also in this case, as described above, the selected communication unit can measure the signal-to-noise ratio of the received signal and transmit information on the measured signal-to-noise ratio to the selection unit 430. When the value of the signal-to-noise ratio is equal to or less than a certain limit, the selection unit 430 re-directs the directional antenna 401 included in the first antenna group (using the frequency band A) measured by the first RSS measurement unit 410. , 403, 405 and the current received signal strength of the directional antennas 402, 404, 406 included in the second antenna group (using the frequency band B) measured by the second RSS measuring unit 420. A directional antenna with the highest received signal strength can be selected, and communication unit selection using a frequency band used by the selected directional antenna can be executed.

  As an example, the first RSS measurement unit 410 measures the RSS # 1 periodically or aperiodically, and the second RSS measurement unit 420 periodically or aperiodically measures the RSS # 2. The selection unit 430 measures the plurality of antennas based on the RSS # 1 and the RSS # 2 measured most recently, i.e., the first signal, when the value of the signal-to-noise ratio is less than a certain limit. From the directional antennas constituting the directional antenna group and the directional antennas constituting the second directional antenna group, the directional antenna having the highest received signal strength can be reselected.

  As another example, the first RSS measurement unit 410 re-measures the RSS # 1 when the value of the signal-to-noise ratio is below a certain limit, and the second RSS measurement unit 420 If the value of the noise ratio is below a certain limit, the RSS # 2 is remeasured, and in this case, the selection unit 430 determines the first directivity based on the remeasured RSS # 1 and RSS # 2. A directional antenna with the highest received signal strength can be reselected from among the directional antennas constituting the antenna group and the directional antennas constituting the second directional antenna group.

  As described in detail with reference to FIGS. 3 and 4, according to the present invention, the reception direction of a radio signal can be detected through comparison of received signal strength, and a packet including at least one of voice and data information can be detected. The transmission / reception can be performed via at least one communication unit among the first communication unit using the frequency band A and the second communication unit using the frequency band B.

  FIG. 5 shows another example of a wireless communication apparatus including a plurality of directional antennas according to the present invention. In FIG. 5, there are first antenna groups 501, 503, and 505 that use the frequency band A and second antenna groups 502, 504, and 506 that use the frequency band B, but the communication unit has the frequency band B Only the communication unit 580 to be used exists. In this case, first RSS measurement section 510 measures RSS # 1, which is the received signal strength of directional antennas 501, 503, and 505 constituting the first directional antenna group that uses frequency band A. The RSS # 1 is used for direction detection of received signals. That is, in this case, the antenna selection unit 530 determines the radio signal reception direction (that is, the communication target) based on RSS # 1 that is the reception signal strength of the directional antennas 501, 503, and 505 using the frequency band A. Detect direction). That is, the antenna selection unit 530 confirms the directional antenna # 1 having the highest received signal strength among the directional antennas constituting the first antenna groups 501, 503, and 505 based on the RSS # 1, and The direction of the received signal can be detected based on the direction of the directional antenna #. The antenna selection unit 530 selects the directional antenna # 2 whose azimuth includes the detection direction from the directional antennas 502, 504, and 506 that use the frequency band B. The antenna selection unit 530 transmits an antenna selection signal indicating the selected directional antenna # 2 to the antenna switch 550, and the antenna switch 550 connects the selected directional antenna and the communication unit 580. The wireless communication apparatus can execute wireless communication in the detection direction based on the selected directional antenna # 2 and the communication unit 580.

  For example, the reception direction of a wireless signal can be detected using a low frequency band, and wireless communication can be performed using a high frequency band in the detection direction. For example, the frequency band A is a lower frequency band than the frequency band B, as in the case where the frequency band A is a 2.4 GHz band and the frequency band B is a 5.8 GHz band. In general, when a low frequency is used, the communication distance becomes long. Therefore, the reception direction of the radio signal is detected based on the low frequency band, and more data can be transmitted. This is because wireless communication is performed using the frequency band. In such a case, a transmission RF signal generator for the frequency band A may be further included in the wireless communication device so that the wireless communication device can measure the received signal strength for the frequency band A.

  Also in this case, as described above, the communication unit 580 can measure the signal-to-noise ratio of the received signal and transmit information on the measured signal-to-noise ratio to the antenna selection unit 530. When the value of the signal-to-noise ratio is equal to or less than a certain limit, the antenna selection unit 530 returns to the directional antenna included in the first antenna group that uses the frequency band A measured by the first RSS measurement unit 510 again. Based on the current received signal strengths of 501, 503, and 505, reconfirming the directional antenna having the highest received signal strength, and redetecting the direction of the received signal based on the direction of the reselected directional antenna. Can do. In this case, the antenna selection unit 530 selects a directional antenna whose azimuth includes the direction of the re-detected received signal from among the directional antennas 502, 504, and 506 constituting the second directional antenna group. Can be reselected.

  As an example, the first RSS measurement unit 510 measures the RSS # 1 periodically or aperiodically, and the antenna selection unit 530 is the most when the value of the signal-to-noise ratio is below a certain limit. Based on the recently measured RSS # 1, the directional antenna having the highest received signal strength is reconfirmed among the directional antennas constituting the first directional antenna group, and the reconfirmed directional antenna is directed. Re-detect the direction of the received signal based on the direction, and re-select the directional antenna whose azimuth includes the re-detected direction of the received signal from the directional antennas constituting the second directional antenna group. can do.

  As another example, the first RSS measurement unit 510 re-measures the RSS # 1 when the value of the signal-to-noise ratio is equal to or less than a certain limit, and the antenna selection unit 530 determines the re-measured RSS. Based on # 1, the directional antenna having the highest received signal strength among the directional antennas constituting the first directional antenna group is reconfirmed, and the received signal is determined based on the direction in which the reconfirmed directional antenna is directed. And re-selecting a directional antenna whose azimuth includes the direction of the re-detected received signal from the directional antennas constituting the second directional antenna group.

  In the example of FIGS. 3 to 5, the directional antenna using the frequency band A and the directional antenna using the frequency band B are sequentially arranged around a fixed rotation axis. However, this is only an example. The directional antenna using the frequency band A and the directional antenna using the frequency band B form a group (ANT_AB), and a plurality of ANT_ABs are arranged around the fixed rotation axis, and the frequency band A of the ANT_AB is defined. As described above, the directional antenna to be used and the directional antenna using the frequency band B can be arranged in pairs in the vertical and horizontal directions or the diagonal direction.

  FIG. 6 is a flowchart illustrating an example of a method in which a wireless communication apparatus including a plurality of directional antennas according to the present invention performs wireless communication.

  A wireless communication device according to the present invention includes a plurality of directional antennas. The plurality of directional antennas are directed in different directions. The plurality of directional antennas are disposed so as to surround a fixed rotation axis, and sequentially use a plurality of different frequency bands in a clockwise or counterclockwise direction. For example, the plurality of directional antennas may include a first directional antenna that uses the frequency band A and a second directional antenna that uses the frequency band B. In this case, the plurality of directional antennas Among these, the directional antenna using the frequency band A and the directional antenna using the frequency band B can be sequentially arranged in the clockwise or counterclockwise direction to detect the received signal. Alternatively, among the plurality of directional antennas, the directional antenna using the frequency band A and the directional antenna using the frequency band B form a group (ANT_AB), and the plurality of ANT_ABs surround the constant rotation axis. In addition, the directional antenna using the frequency band A of the ANT_AB and the directional antenna using the frequency band B can be arranged in pairs in the vertical and horizontal directions or the diagonal direction so as to detect a received signal.

  The wireless communication device according to the present invention may include a plurality of communication units each including different frequency bands used by the plurality of directional antennas. For example, when the plurality of directional antennas include a first directional antenna that uses the frequency band A and a second directional antenna that uses the frequency band B, the wireless communication device uses the frequency band A. A first communication unit to be used and a second communication unit to use the frequency band B can be included.

  Referring to FIG. 6, the wireless communication apparatus measures RSS # 1, which is the received signal strength of a directional antenna that uses frequency band A (S600).

  The wireless communication apparatus measures RSS # 2, which is the received signal strength of the directional antenna using the frequency band B (S610).

  The wireless communication device compares the received signal strength based on the measured RSS # 1 and RSS # 2, and the received signal strength is the highest among the first directional antenna and the second directional antenna. A directional antenna having a large value is selected (S620). The wireless communication apparatus can detect the reception direction of the wireless signal based on the direction toward the selected directional antenna.

  The wireless communication device includes the directional antenna selected from the first communication unit using the frequency band A and the second communication unit using the frequency band B included in the wireless communication device. The communication unit that uses the frequency band used by is selected, and the connection between the selected directional antenna and the selected communication unit is controlled (S630).

  The wireless communication device performs wireless communication using the selected communication unit and the selected directional antenna (S640).

  Further, the wireless communication apparatus can measure a signal-to-noise ratio of a signal received by the selected communication unit. When the value of the signal-to-noise ratio is equal to or less than a certain limit, the wireless communication apparatus determines whether the first directional antenna and the second directional antenna are based on the current RSS # 1 and the RSS # 2. A directional antenna having the highest signal strength can be selected again.

  As an example, the wireless communication device can measure the RSS # 1 and RSS # 2 periodically or aperiodically in S620, and the signal-to-noise ratio is below a certain limit, The wireless communication apparatus has a directivity having the highest received signal strength among the first directional antenna and the second directional antenna based on the RSS # 1 and the RSS # 2 measured most recently. The antenna can be reselected. Further, the wireless communication apparatus reselects a communication unit that uses the same frequency band as the frequency band used by the reselected directional antenna from the first communication unit and the second communication unit. , And can be reconnected to the reselected directional antenna. The wireless communication device can execute wireless communication via the reselected directional antenna and the reselected communication unit.

  As another example, when the value of the signal-to-noise ratio is equal to or less than a certain limit, the wireless communication apparatus remeasures the RSS # 1 and the RSS # 2. In this case, the radio communication device uses the re-measured RSS # 1 and RSS # 2 to configure the first directional antenna group and the second directional antenna group. A directional antenna having the highest received signal strength can be reselected from the antennas. Further, the wireless communication apparatus reselects a communication unit that uses the same frequency band as the frequency band used by the reselected directional antenna from the first communication unit and the second communication unit. , And can be reconnected to the reselected directional antenna. The wireless communication device can execute wireless communication via the reselected directional antenna and the reselected communication unit.

  Through the present invention, it is possible to obtain frequency diversity in a marine communication environment where the change in received intensity according to distance is drastically due to interference of sea surface reflected waves, and to detect the transmission / reception direction of radio signals, that is, the direction of a communication target. can do. In addition, even when the target is far away, the direction of the communication target is detected using a lower frequency band (for example, 2.4 GHz), and the higher frequency band (for example, 5.8 GHz) is used. Wireless communication can also be performed.

  The above description is merely illustrative of the technical idea of the present invention, and a person having ordinary knowledge in the technical field to which the present invention belongs does not depart from the essential characteristics of the present invention. Various modifications and variations are possible. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but are for explanation. The scope of the technical idea of the present invention is limited by such an embodiment. It is not something. The protection scope of the present invention should be construed by the claims, and all technical ideas within the equivalent scope should be construed as being included in the scope of the right of the present invention.

Claims (20)

A wireless communication device including a plurality of directional antennas,
A plurality of directional antennas including a first directional antenna group using the frequency band A and a second directional antenna group using the frequency band B in different directions;
A first RSS measurement unit that measures RSS # 1, which is the received signal strength of each of the directional antennas constituting the first directional antenna group;
A second RSS measurement unit that measures RSS # 2 that is the received signal strength of each of the directional antennas constituting the second directional antenna group;
A first antenna selection unit that selects a directional antenna having the highest received signal strength from among the directional antennas constituting the first directional antenna group based on the RSS # 1;
A second antenna selection unit that selects a directional antenna having the highest received signal strength from among the directional antennas constituting the second directional antenna group based on the RSS # 2.
A first communication unit that executes the first wireless communication using the frequency band A;
A second communication unit that performs the second wireless communication using the frequency band B;
A first antenna switch for controlling connection between a directional antenna selected from directional antennas constituting the first directional antenna group and the first communication unit; and
A second antenna switch for controlling connection between a directional antenna selected from directional antennas constituting the second directional antenna group and the second communication unit;
The first communication unit measures SNR # 1, which is a signal-to-noise ratio of a received signal, when executing the first wireless communication,
The second communication unit measures SNR # 2 that is a signal-to-noise ratio of a received signal when executing the second wireless communication,
The first RSS measurement unit measures the RSS # 1 periodically or aperiodically, the second RSS measurement unit measures the RSS # 2 periodically or aperiodically, When the value of the SNR # 1 is equal to or less than a certain limit, the first antenna selection unit determines the directional antennas that constitute the first directional antenna group based on the RSS # 1 measured most recently. Reselect the directional antenna with the highest received signal strength
When the value of the SNR # 2 is equal to or less than a certain limit, the second antenna selection unit determines the directional antennas that constitute the second directional antenna group based on the RSS # 2 measured most recently. A radio communication apparatus, wherein a directional antenna having the highest received signal strength is reselected from among them.   The plurality of directional antennas are arranged so as to surround a fixed rotation axis, and among the plurality of directional antennas, a directional antenna using the frequency band A and a directional antenna using the frequency band B are a watch. The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus is alternately arranged in a direction or a counterclockwise direction.   Of the plurality of directional antennas, a directional antenna that uses frequency band A and a directional antenna that uses frequency band B are arranged in pairs in the vertical and horizontal directions or diagonal directions, and form a pair. The wireless communication device according to claim 1, wherein the antenna is disposed so as to surround a fixed rotation axis. A wireless communication device including a plurality of directional antennas,
A plurality of directional antennas including a first directional antenna group using the frequency band A and a second directional antenna group using the frequency band B in different directions;
A first RSS measurement unit that measures RSS # 1, which is the received signal strength of each of the directional antennas constituting the first directional antenna group;
A second RSS measurement unit that measures RSS # 2 that is the received signal strength of each of the directional antennas constituting the second directional antenna group;
A first antenna selection unit that selects a directional antenna having the highest received signal strength from among the directional antennas constituting the first directional antenna group based on the RSS # 1;
A second antenna selection unit that selects a directional antenna having the highest received signal strength from among the directional antennas constituting the second directional antenna group based on the RSS # 2.
A first communication unit that executes the first wireless communication using the frequency band A;
A second communication unit that performs the second wireless communication using the frequency band B;
A first antenna switch for controlling connection between a directional antenna selected from directional antennas constituting the first directional antenna group and the first communication unit; and
A second antenna switch for controlling connection between a directional antenna selected from directional antennas constituting the second directional antenna group and the second communication unit;
The first communication unit measures SNR # 1, which is a signal-to-noise ratio of a received signal, when executing the first wireless communication,
The second communication unit measures SNR # 2 that is a signal-to-noise ratio of a received signal when executing the second wireless communication,
The first RSS measurement unit re-measures the RSS # 1 when the value of the SNR # 1 is equal to or less than a certain limit,
The second RSS measurement unit re-measures the RSS # 2 when the value of the SNR # 2 is equal to or less than a certain limit,
The first antenna selection unit reselects a directional antenna having the highest received signal strength from among the directional antennas constituting the first directional antenna group based on the remeasured RSS # 1. And
The second antenna selection unit reselects a directional antenna having the highest received signal strength from among the directional antennas constituting the second directional antenna group based on the remeasured RSS # 2. A wireless communication device.   The plurality of directional antennas are arranged so as to surround a fixed rotation axis, and among the plurality of directional antennas, a directional antenna using the frequency band A and a directional antenna using the frequency band B are a watch. The wireless communication device according to claim 4, wherein the wireless communication device is alternately arranged in a direction or a counterclockwise direction.   Of the plurality of directional antennas, a directional antenna that uses frequency band A and a directional antenna that uses frequency band B are arranged in pairs in the vertical and horizontal directions or diagonal directions, and form a pair. The wireless communication apparatus according to claim 4, wherein the antenna is disposed so as to surround a fixed rotation axis. A wireless communication device including a plurality of directional antennas,
A plurality of directional antennas including a first directional antenna group using the frequency band A and a second directional antenna group using the frequency band B in different directions;
A first RSS measurement unit that measures RSS # 1, which is the received signal strength of each of the directional antennas constituting the first directional antenna group;
A second RSS measurement unit that measures RSS # 2 that is the received signal strength of each of the directional antennas constituting the second directional antenna group;
A first communication unit that performs wireless communication using the frequency band A;
A second communication unit that performs wireless communication using the frequency band B;
A specific directional antenna is selected from the directional antennas constituting the first directional antenna group and the directional antennas constituting the second directional antenna group based on the RSS # 1 and RSS # 2. A selection unit that selects a communication unit that uses the same frequency band as the frequency band used by the selected specific directional antenna from the first communication unit and the second communication unit; and
An antenna switch for controlling a connection between the selected specific directional antenna and the communication unit selected from the first communication unit and the second communication unit;
The communication unit selected from the first communication unit and the second communication unit measures a signal-to-noise ratio of a received signal when performing wireless communication,
The first RSS measurement unit measures the RSS # 1 periodically or aperiodically, the second RSS measurement unit measures the RSS # 2 periodically or aperiodically, When the value of the signal-to-noise ratio is below a certain limit, the selection unit configures the first directivity antenna group based on the RSS # 1 and the RSS # 2 measured most recently. Reselecting the directional antenna with the highest received signal strength from the directional antennas with the highest received signal strength among the directional antennas constituting the antenna and the second directional antenna group, Wireless communication device.   The plurality of directional antennas are arranged so as to surround a fixed rotation axis, and among the plurality of directional antennas, a directional antenna using the frequency band A and a directional antenna using the frequency band B are a watch. The wireless communication device according to claim 7, wherein the wireless communication device is alternately arranged in a direction or a counterclockwise direction.   Of the plurality of directional antennas, a directional antenna that uses frequency band A and a directional antenna that uses frequency band B are arranged in pairs in the vertical and horizontal directions or diagonal directions, and form a pair. The wireless communication apparatus according to claim 7, wherein the directional antenna is disposed so as to surround a fixed rotation axis. A wireless communication device including a plurality of directional antennas,
A plurality of directional antennas including a first directional antenna group using the frequency band A and a second directional antenna group using the frequency band B in different directions;
A first RSS measurement unit that measures RSS # 1, which is the received signal strength of each of the directional antennas constituting the first directional antenna group;
A second RSS measurement unit that measures RSS # 2 that is the received signal strength of each of the directional antennas constituting the second directional antenna group;
A first communication unit that performs wireless communication using the frequency band A;
A second communication unit that performs wireless communication using the frequency band B;
A specific directional antenna is selected from the directional antennas constituting the first directional antenna group and the directional antennas constituting the second directional antenna group based on the RSS # 1 and RSS # 2. A selection unit that selects a communication unit that uses the same frequency band as the frequency band used by the selected specific directional antenna from the first communication unit and the second communication unit; and
An antenna switch for controlling a connection between the selected specific directional antenna and the communication unit selected from the first communication unit and the second communication unit;
The communication unit selected from the first communication unit and the second communication unit measures a signal-to-noise ratio of a received signal when performing wireless communication,
The first RSS measurement unit re-measures the RSS # 1 when the value of the signal-to-noise ratio is below a certain limit,
The second RSS measurement unit re-measures the RSS # 2 when the value of the signal-to-noise ratio is below a certain limit,
The selection unit includes a directional antenna that configures the first directional antenna group and a directional antenna that configures the second directional antenna group based on the remeasured RSS # 1 and RSS # 2. A radio communication apparatus, wherein a directional antenna having the highest received signal strength is reselected from antennas.   The plurality of directional antennas are arranged so as to surround a fixed rotation axis, and among the plurality of directional antennas, a directional antenna using the frequency band A and a directional antenna using the frequency band B are a watch. The wireless communication apparatus according to claim 10, wherein the wireless communication apparatus is alternately arranged in a direction or a counterclockwise direction.   Of the plurality of directional antennas, a directional antenna that uses frequency band A and a directional antenna that uses frequency band B are arranged in pairs in the vertical and horizontal directions or diagonal directions, and form a pair. The wireless communication apparatus according to claim 10, wherein the antenna is disposed so as to surround a fixed rotation axis. A wireless communication device including a plurality of directional antennas,
A plurality of directional antennas including a first directional antenna group using the frequency band A and a second directional antenna group using the frequency band B in different directions;
A first RSS measurement unit that measures RSS # 1, which is the received signal strength of each of the directional antennas constituting the first directional antenna group;
Based on RSS # 1, a directional antenna having the highest received signal strength is confirmed among the directional antennas constituting the first directional antenna group, and reception is performed based on the direction in which the confirmed directional antenna is directed. An antenna selector that detects a direction of a signal and selects a directional antenna whose azimuth includes the direction of the received signal from among the directional antennas constituting the second directional antenna group;
A communication unit that performs the second wireless communication using the frequency band B; and
An antenna switch for controlling connection between the selected directional antenna and the communication unit;
The communication unit measures a signal-to-noise ratio of a received signal when performing wireless communication,
The first RSS measurement unit measures the RSS # 1 periodically or aperiodically, and the selection unit is most recently measured when the value of the signal-to-noise ratio is below a certain limit. Based on the RSS # 1, the directional antenna having the highest received signal strength among the directional antennas constituting the first directional antenna group is reconfirmed, and based on the direction in which the reconfirmed directional antenna is directed. Re-detecting the direction of the received signal, and re-selecting a directional antenna whose azimuth includes the re-detected direction of the received signal from the directional antennas constituting the second directional antenna group. A wireless communication device.   The plurality of directional antennas are arranged so as to surround a fixed rotation axis, and among the plurality of directional antennas, a directional antenna using the frequency band A and a directional antenna using the frequency band B are a watch. The wireless communication apparatus according to claim 13, wherein the wireless communication apparatus is alternately arranged in a direction or a counterclockwise direction.   Of the plurality of directional antennas, a directional antenna that uses frequency band A and a directional antenna that uses frequency band B are arranged in pairs in the vertical and horizontal directions or diagonal directions, and form a pair. The wireless communication apparatus according to claim 13, wherein the antenna is disposed so as to surround a fixed rotation axis.   The wireless communication apparatus according to claim 13, wherein the frequency band A is a frequency band lower than the frequency band B. A wireless communication device including a plurality of directional antennas,
A plurality of directional antennas including a first directional antenna group using the frequency band A and a second directional antenna group using the frequency band B in different directions;
A first RSS measurement unit that measures RSS # 1, which is the received signal strength of each of the directional antennas constituting the first directional antenna group;
Based on RSS # 1, a directional antenna having the highest received signal strength is confirmed among the directional antennas constituting the first directional antenna group, and reception is performed based on the direction in which the confirmed directional antenna is directed. An antenna selector that detects a direction of a signal and selects a directional antenna whose azimuth includes the direction of the received signal from among the directional antennas constituting the second directional antenna group;
A communication unit that performs the second wireless communication using the frequency band B; and
An antenna switch for controlling connection between the selected directional antenna and the communication unit;
The communication unit measures a signal-to-noise ratio of a received signal when performing wireless communication,
The first RSS measurement unit re-measures the RSS # 1 when the value of the signal-to-noise ratio is below a certain limit,
The selection unit reconfirms a directional antenna having the highest received signal strength among directional antennas constituting the first directional antenna group based on the remeasured RSS # 1, and reconfirms the reconfirmation. The direction of the received signal is re-detected based on the direction of the directed directional antenna, and the azimuth includes the direction of the re-detected received signal from among the directional antennas constituting the second directional antenna group. A wireless communication apparatus, wherein a directional antenna is reselected.   The radio communication apparatus according to claim 17, wherein the frequency band A is a frequency band lower than the frequency band B. A wireless communication method for a wireless communication device including a plurality of directional antennas,
Measuring RSS # 1, which is the received signal strength of the first directional antenna using the frequency band A, in different directions;
Measuring RSS # 2, which is the received signal strength of the second directional antenna using the frequency band B, in different directions;
Selecting a directional antenna with the highest received signal strength from the first directional antenna and the second directional antenna based on the measured RSS # 1 and RSS # 2.
Of the first communication unit using the frequency band A and the second communication unit using the frequency band B included in the wireless communication device, the frequency band used by the selected directional antenna; Connecting a communication unit using the same frequency band to the selected directional antenna;
Performing wireless communication using the selected at least one directional antenna and the connected communication unit;
Measuring the signal-to-noise ratio of the received signal;
If the signal-to-noise ratio is less than a certain limit, the most from among the first directional antenna and the second directional antenna based on the RSS # 1 and the RSS # 2 measured most recently. Reselecting a directional antenna with a high received signal strength;
A communication unit that uses the same frequency band as the frequency band used by the reselected directional antenna is selected from the first communication unit and the second communication unit, and the reselected directivity is selected. Coupling to an antenna; and
Performing wireless communication using the reselected directional antenna and the reselected communication unit; and
Measuring the RSS # 1 includes measuring the RSS # 1 periodically or aperiodically;
The step of measuring the RSS # 2 includes a method of measuring the RSS # 2 periodically or aperiodically. A wireless communication method for a wireless communication device including a plurality of directional antennas,
Measuring RSS # 1, which is the received signal strength of the first directional antenna using the frequency band A, in different directions;
Measuring RSS # 2, which is the received signal strength of the second directional antenna using the frequency band B, in different directions;
Selecting a directional antenna with the highest received signal strength from the first directional antenna and the second directional antenna based on the measured RSS # 1 and RSS # 2.
Of the first communication unit using the frequency band A and the second communication unit using the frequency band B included in the wireless communication device, the frequency band used by the selected directional antenna; Connecting a communication unit using the same frequency band to the selected directional antenna;
Performing wireless communication using the selected at least one directional antenna and the connected communication unit;
Measuring the signal-to-noise ratio of the received signal;
Re-measuring RSS # 1, which is the received signal strength of the first directional antenna, if the signal to noise ratio is below a certain limit;
Re-measuring RSS # 2, which is the received signal strength of the second directional antenna, if the signal to noise ratio is below a certain limit;
Based on the re-measured RSS # 1 and RSS # 2, the directional antenna having the highest received signal strength is reselected from the first directional antennas and the second directional antenna. Step;
A communication unit that uses the same frequency band as the frequency band used by the reselected directional antenna is reselected from the first communication unit and the second communication unit, and the reselected directivity is selected. Coupling to a sex antenna; and
Performing wireless communication using the reselected directional antenna and the reconnected communication unit.

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