JP5354526B2 - Wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system including a receiver including a directional antenna capable of controlling directivity and a communication path forming unit thereof, and preferably a communication path suitable for tracking and monitoring a plurality of signals at all times. For example, even if one of the electromagnetic wave communication paths such as the millimeter wave band is interrupted by an obstacle, it is possible to switch to another communication path instantly and transmit and receive stably without interruption. The present invention relates to a communication system.

  In a wireless communication system using an electromagnetic wave in a high frequency band such as a millimeter wave band, a directional antenna having a high antenna gain is generally used. In order to realize a high antenna gain, a physically large antenna such as an aperture antenna or an array antenna is required. In addition, since a directivity antenna having a large antenna gain usually cannot change its directivity, it can communicate in only one direction, and at the same time, it is very difficult to physically adjust the alignment between the antennas.

  As a directional antenna that can change the direction of the directivity while realizing a high antenna gain, there is a beam forming antenna. A beam forming antenna controls and changes the directivity of a beam by supplying signal power whose phase and amplitude are accurately adjusted to a plurality of antenna elements.

  If such beam forming becomes possible, it is possible to obtain an antenna gain that covers the large propagation attenuation that is a drawback of millimeter waves, and at the same time, the directivity can be directed in an arbitrary direction, so that the terminal can be moved. Become.

  In a wireless communication device that uses a directional antenna such as a beam forming antenna and that uses millimeter-wave radio waves, which have a strong signal straightness, the directionality of the antenna in the direction where the strength of the radio waves from the partner wireless communication device is strongest. I was aiming.

  On the other hand, in a wireless communication system using an electromagnetic wave in a high frequency band such as a millimeter wave band, signal attenuation due to propagation is large and diffraction cannot be expected. Therefore, communication cannot be performed only by a person entering the communication path. For this reason, communication is always performed on a suitable communication path, and the reflected wave reflected on the wall surface is always tracked. When the direct wave currently used is interrupted, other suitable communication path such as a reflected wave is used. It is necessary to switch to.

  With reference to FIG. 10 and FIG. 11, for example, a case where two conventional transceivers 100 and 200 having directional antennas 100 a and 200 b having variable directivities such as beam forming antennas transmit and receive signals will be described.

  When the transceiver 100 radiates a directional radio wave (hereinafter referred to as “beam”) using the directional antenna 100a, the transceiver 200 receives the beam using the directional antenna 200a. As shown in FIG. 10, the transceiver 200 includes a modulation / demodulation unit 201 that modulates and demodulates a beam received by the directional antenna 200a, and a received power detection that detects a beam having the maximum received power from the received beams. And an antenna control unit 203 that controls the directional antenna 200a to change the directivity of the directional antenna 200a so as to receive the beam having the maximum received power detected by the received power detection unit 202. Since the transceiver 100 and the transceiver 200 have substantially the same structure, detailed description of the transceiver 100 is omitted.

  In the example shown in FIGS. 10 and 11, a beam from the transceiver 100 directly passes to the transceiver 200 as a suitable communication path between the directional antenna 200 a of the transceiver 200 and the directional antenna 100 a of the transceiver 100. An incoming direct wave communication path P0 and a reflected wave communication path P1 arriving at the transmitter / receiver 200 after the beam from the transmitter / receiver 100 is reflected by a reflector R such as a wall exist. In FIG. However, when the communication path P0 is blocked by an obstacle, the transceiver 100 and the transceiver 200 switch the communication path P0 to the communication path P1 as shown in FIG. The continuity of communication is maintained.

  At this time, for example, the received power detection unit 202 of the transceiver 200 includes a received beam including a beam that has passed through the communication path P0 and a beam that has passed through the communication path P1 among the received beams. By comparing the respective powers, the beam having the maximum received power is detected, and the communication path of the beam having the maximum received power is set as a suitable communication path. The antenna control unit 203 changes the fixed beam of the directional antenna 200a so as to receive the beam having the maximum reception power detected by the reception power detection unit 202.

  With reference to FIG. 12, the case where the transceivers thus configured communicate with each other will be described. FIG. 12 shows a personal computer in which the transceiver 100 is installed at home and the transceiver 200 as a mobile phone. The transceiver 100 and the transceiver 200 use the direct-wave communication path P0 as a suitable communication path ((a) in FIG. 12). However, the communication path P0 is blocked by an obstacle due to passage of a person or the like. When this occurs ((b) in FIG. 12), the received power detection unit of each transceiver searches for and detects another suitable communication path ((c) in FIG. 12), and the antenna control unit of each transceiver. Changes the directivity of the directional antenna 200a in the direction of the detected communication path P1, and resumes communication ((d) of FIG. 12).

  However, in communication using a conventional directional antenna, the communication path is inevitably interrupted ((b) in FIG. 12) until another suitable communication path is searched for and detected ((c) in FIG. 12). There is a problem that the communication is interrupted until it takes time and communication is resumed ((d) in FIG. 12). Further, when another suitable communication path shown in FIG. 12D is detected, communication may be interrupted unless an appropriate communication path is detected.

  In the first place, even if the receiver has a function of searching for a suitable signal, a communication path cannot exist in an environment without a reflected wave, and therefore, it is impossible to search for another communication path.

  Therefore, the present invention has been made in view of the above-described conventional technology, and always performs communication using a suitable communication path in a wireless communication system including an antenna capable of controlling directivity. For example, the communication path of an electromagnetic wave such as a millimeter wave band An object of the present invention is to provide a wireless communication system capable of stably transmitting and receiving without switching between communication paths even when one is blocked by an obstacle.

According to one aspect of the present invention, a transmitting device that transmits a signal wave, a receiving device that includes a directional antenna having directivity and receives a signal wave, and a signal wave transmitted from the transmitting device is directly or reflected. And a communication path forming unit that forms a communication path for guiding the signal wave to the directional antenna, wherein the receiving device selects a suitable signal wave communication path. The directivity direction of the directional antenna is directed to a suitable communication path selected by the selection means and the suitable route selection means, and the preferred communication path selected by the suitable route selection means passes through the directional antenna. An antenna control unit that receives a signal wave, and the preferred path selection unit constantly tracks a plurality of signal waves including a signal wave that has passed through a communication path formed by the communication path forming unit, The direction and the reception quality of each of the number of signal waves are constantly measured, and a suitable signal wave communication path is selected based on the measured direction and the reception quality of the plurality of signal waves. The signal wave that has passed through the preferred communication path selected by the preferred route selection means is continuously directed to the directional antenna by directing the directionality of the directional antenna to the preferred communication path selected by the route selection means. And receiving it. Further, the directional antenna is a beam forming antenna, the preferred route selection means, you select a communication path suitable signal wave by tracking signals arriving through the communication path. The tracking signal according to a preferred path selection means, for each cluster of the plurality of communication paths exist discretely, a tracking of a plurality of beams in the cluster, the preferred route selecting means, the plurality of beam by tracking the beam that is suitable for communication and select always for each cluster, the selection of a suitable signal wave of the communication path by the preferred routing hand stage, a communication path by the beam that is appropriate to a plurality of communication selected for each the cluster wireless communication system characterized in that it is a choice.

  Here, the “plurality of signal waves” may naturally include direct waves. For example, even if the communication path is switched instantaneously, communication is disconnected when there are no multiple reflected waves, that is, when there is no switching path. By creating different communication paths with a large number of reflected waves having significant power around the transmitter / receiver, communication can be continued by instantaneously switching the communication paths. With this configuration, the wireless communication system according to the present invention directly transmits a signal wave transmitted from the transmission apparatus, a reception apparatus that receives a signal wave with a directional antenna having directivity, and a signal wave transmitted from the transmission apparatus. Or a communication path forming unit that forms a communication path that reflects and guides a signal wave to a directional antenna, wherein the receiving apparatus selects a suitable signal wave communication path. Directing the directivity direction of the directional antenna to the preferred communication path selected by the selection means and the preferred route selection means, and receiving the signal wave that has passed through the preferred communication path selected by the preferred route selection means for the directional antenna And a suitable path selection means that always tracks a plurality of signal waves including a signal wave that has passed through a communication path formed by the communication path forming section, and that each of the plurality of signal waves Direction and reception quality are always measured almost simultaneously, and a suitable signal wave communication path is selected based on the measured direction and reception quality of the plurality of signal waves, and the antenna control unit selects the preferred path selected by the preferred path selection means. The directivity direction of the directional antenna is directed to the correct communication path, and the signal wave that has passed through the preferred communication path selected by the preferred path selection means is continuously received by the directional antenna. For example, even if one of the used communication paths is blocked by an obstacle, the signal wave can be continuously received without interruption. For this reason, for example, the present invention can be applied to the case where wireless communication is performed using an electromagnetic wave that has strong straightness such as a millimeter wave band, has a large attenuation due to propagation, and cannot be expected to be diffracted.

  Further, in the wireless communication system of the present invention, the suitable route selection means constantly measures the direction and reception quality of each of the signal wave passing through the communication path used for communication and the other plurality of signal waves, When it is determined that the quality of the signal wave passing through the communication path used for the communication received by the directional antenna has deteriorated from a predetermined level, the antenna control unit receives the reception quality of each of the other plurality of signal waves. The direction of the directivity antenna may be instantaneously switched to the preferred communication path selected by the preferred path selection unit based on the signal wave so that the signal wave is continuously received. With this configuration, the receiving apparatus of the present invention can continuously receive a signal wave without interruption even if one of the communication paths is blocked by an obstacle. For this reason, for example, the present invention can be applied to the case where wireless communication is performed using an electromagnetic wave that has strong straightness such as a millimeter wave band, a large attenuation due to propagation, and cannot be expected to be diffracted.

  According to the wireless communication system of the present invention, the communication path forming unit may be formed of a highly reflective reflector, for example, a square or circular metal plate. Here, “high reflectivity” means a height that can reflect an incoming signal wave and at least generate a reflected wave that can be identified as a signal wave in the receiving device. It may be determined relatively according to. With this configuration, the wireless communication system of the present invention can be constructed easily and easily at a low cost. As the communication path forming unit, for example, a metal band may be simply attached to furniture such as a wall, a personal computer, a keyboard, a desk, and a bookshelf so as to satisfy a predetermined condition.

  In the wireless communication system of the present invention, the communication path forming unit may superimpose a signal wave passing through a communication path formed by the communication path forming unit with a signal wave passing through another communication path including a direct wave. The reflector may be arranged so as to form a communication path in consideration of the beam width of the directional antenna of the receiving device so that the directional antenna of the receiving device is not received.

  With this configuration, in the wireless communication system of the present invention, the communication path forming unit superimposes the signal wave passing through the communication path formed by the communication path forming unit with the signal wave passing through other communication paths including the direct wave. Since the communication path can be formed in consideration of the beam width of the directional antenna of the receiving device so that it is not received by the directional antenna of the receiving device, a high-quality signal with little delay dispersion is received by the receiving device. Can be provided.

  In the wireless communication system of the present invention, the communication path forming unit includes a signal wave that passes through a communication path formed by the communication path forming unit, and a signal wave that passes through any other communication path including a direct wave. When the signal is superimposed and received by the directional antenna of the receiving device, the received power of the signal wave passing through the communication path formed by the communication path forming unit and the signal passing through any of the other communication paths A distance between the directional antenna of the receiving device and the directional antenna of the transmitting device, and the directional antenna of the receiving device and the transmitting device so that the difference in received power of the waves is greater than a predetermined threshold. The communication path is formed in consideration of the distance between the directional antenna and the communication path forming unit, the reflectance of the communication path forming unit, and the beam width of the directional antenna of the receiving device. It may be a reflector.

  With this configuration, in the wireless communication system of the present invention, the communication path forming unit is a signal in which the signal wave passing through the communication path formed by the communication path forming unit passes through any other communication path including a direct wave. When it is received by the directional antenna of the receiving device while being superimposed on a wave, it passes through the received power of the signal wave that passes through the communication path formed by the communication path forming unit and one of the other communication paths. A distance between the directional antenna of the reception device and the directional antenna of the transmission device, and the directional antenna of the reception device so that a difference in received power of signal waves to be larger than a predetermined threshold Forming a communication path in consideration of the distance between the directional antenna and the communication path forming unit of the transmitting apparatus, the reflectance of the communication path forming unit, and the beam width of the directional antenna of the receiving apparatus Even if the signal wave passing through the communication path formed by the signal path forming unit is superimposed on the signal wave passing through any other communication path including the direct wave and received by the directional antenna of the receiving device It is possible to provide a high-quality signal to the receiving device.

  Furthermore, the communication path forming unit may further include an absorber that is disposed around the communication path and weakens the intensity of the signal wave. Specifically, the incoming beam or signal wave is reflected around the reflector or directional antenna of the communication path forming unit that forms the communication path in order to suppress the generation of reflected waves that may cause interference. However, an absorber that weakens to at least a degree that can be identified as a signal wave may be arranged in at least the receiving device. With this configuration, the wireless communication system of the present invention can further reduce delay dispersion and realize an ideal communication environment. The absorber may reflect an incoming beam or signal wave, but may have a low reflectivity that weakens at least below a level that can be identified as a signal wave by the receiving device, or at least to the receiving device. It may be an object that is scattered so that the reflected wave that can be identified as a signal wave does not generate a reflected wave. The material, arrangement, reflectance, and degree of scattering of the absorber may be relatively determined according to mounting.

According to the present invention, there is provided a wireless communication system including a receiving device that includes an antenna capable of controlling directivity and receives a signal wave. The wireless communication system always performs communication using a good communication path, for example, the communication path used. even one that is blocked by an obstacle, it is possible to provide a wireless communication system that can be stably transmitted and received without interruption by switching the communication path.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a wireless communication system 1 according to an embodiment of the present invention. As shown in FIG. 1, the wireless communication system 1 of the present embodiment includes a transceiver 10 having a directional antenna 10a, a transceiver 20 having a directional antenna 20a, and a plurality of reflectors R1 to R4. Each of the directional antennas 10a and 20a physically has one directivity, and the directivity is variable. The present invention can be applied to a wireless communication system including three or more transmitters / receivers. However, in order to facilitate understanding, in the present embodiment, the transmitter / receiver 10 and the transmitter / receiver 20 are used. In the following description, it is assumed that the master plays a role of controlling time timing, and the transceiver 20 takes the role of a slave. Further, the transceiver 10 may be configured only as a transmitter, and the transceiver 20 may be configured only as a receiver. Further, the antenna of the transceiver 10 may not be the directional antenna 10a.

  As shown in FIG. 1, the transceiver 10 further includes a transceiver 11 that transmits and receives signals via the directional antenna 10a, and a beam that has arrived through a suitable communication path among the beams that have arrived at the directional antenna 10a. The communication path selection unit 12 to be selected, the frame formation unit 13 that forms information to be transmitted in a predetermined frame, and the directional antenna 10a are controlled, so that the communication path selected by the communication path selection unit 12 is connected to the directional antenna 10a. A directivity control unit 14 that matches directivity and a CPU (not shown) that controls the overall functions and operations of the transceiver 10 are included.

The transceiver 20 includes a transceiver 21 that transmits and receives signals via the directional antenna 20a, and a quality monitor that constantly monitors the quality of each beam arriving at the directional antenna 20a, including the beam used for communication. and parts 22, quality monitoring section beams each quality B ₁ was monitored at _22, B _2, a memory 23 for storing · · · B _N, via a suitable communications path from the beam arriving at the directional antenna 20a A communication path selection unit 24 that selects an incoming beam, a directivity control unit 25 that controls the directivity antenna 20a to adjust the directivity of the directivity antenna 20a to the communication path selected by the communication path selection unit 24, and transmission / reception CPU (not shown) that controls the overall functions and operations of the machine 20. The quality monitor unit 22 monitors the quality of the incoming beam. The quality monitor unit 22, the memory 23, and the communication route selection unit 24 constitute a preferred route selection unit.

  The plurality of reflectors R1 to R4 positioned between the transceiver 10 and the transceiver 20 are provided for artificially forming a communication path. The reflectors R1 to R4 will be described in detail later, but may be, for example, a wall, a highly reflective metal plate, a metal tape attached to a wall, a personal computer, a keyboard, a desk, a bookshelf, or the like. In the present embodiment, it is assumed that the reflector has a reflectivity enough to reflect an incoming beam and generate a reflected wave that can be monitored as a beam at least by the quality monitor unit 22.

Under the control of the CPU, the transceiver 20 determines the direction of the beam arriving by the directivity control unit 25, for example, a communication path P0 using direct waves, and a communication path P1 using an existing object R1 such as a wall or shelf as a reflector. The communication paths P <b> 2 to P <b> 4 that are artificially formed by the reflectors R <b> 2 to R <b> 4 that are artificially installed are identified, and the quality monitor unit 22 also acquires information on the direction of each beam from the directivity control unit 25. . Further, the quality monitor unit 22 tracks all or part of the signals passing through the communication paths P0 to P4 thus identified and monitors the quality, and the quality B ₁ , B ₂ ,. _N is stored in the memory 23 together with the direction. The communication path selection unit 24 selects a suitable communication path used for communication based on the signal quality B ₁ , B ₂ ,... B _N stored in the memory 23. The directivity control unit 25 controls the directional antenna 20a to direct the directivity of the directional antenna 20a in the direction of a suitable communication path selected by the communication path selection unit 24, so that the transceiver 10 and the transceiver 20 And to enable stable communication. With this configuration, the transceiver 20 always tracks two or more incoming waves as well as the currently used incoming waves, monitors the quality, selects the incoming waves that can be used for communication, The directivity of the directional antenna 20a can be directed to the communication path. Therefore, even if a person crosses, for example, even if the signal quality of the communication path currently used for communication deteriorates, the transceiver 20 immediately selects another suitable communication path, and the directional antenna Since communication can be performed by switching the directivity of 20a, stable communication can be performed without interrupting communication.

  In the present embodiment, the transmitter / receiver 10 and the transmitter / receiver 20 are suitable for a system that performs communication by a time division multiple access method. The transceiver 10 transmits a signal in a configuration having a frame (also referred to as a “super frame”) formed by the frame forming unit 13. FIG. 2 shows an example of a frame structure formed by the frame forming unit 13 of the transceiver 10.

  The frame is composed of a plurality of time slots (hereinafter referred to as “slots”) which are basic units for performing time division multiple access. In the present embodiment, for ease of explanation, a single transmitter / receiver 20 is used as an object with which the transmitter / receiver 10 communicates. However, the present invention is not limited to this, and a plurality of transmission / reception is performed by repeating this frame. You may communicate with the machine 20. The frame includes a beacon B that transmits a synchronization signal serving as a time reference, tracking slots TS0 to TSN that transmit a tracking signal for each communication path, and a communication slot CS used for communication.

  Specifically, the transceiver 10 transmits a beacon indicating a time reference for each frame. Thereafter, a tracking signal is transmitted in the tracking slot in the direction of the direct wave passing through the communication path P0 and the direction of the reflected wave passing through the communication paths P1 to P4. In the present embodiment, five tracking slots, TS0 to TS4, are used. Each of the tracking slots TS0 to TS4 is associated with each of the communication paths identified by the directivity control unit 25, and their timing is notified by a beacon. By securing tracking slots TS0 to TS4 that are temporally independent for all or a part of the communication paths P0 to P4 existing between the transceiver 10 and the transceiver 20, the transceiver 20 is always in a plurality. Tracking for controlling the antenna directivity with respect to all or part of the communication paths P0 to P4 can be performed. In addition, a time for data transmission / reception is secured in the communication slot CS after the tracking slots TS0 to TS4.

  Based on the information of the beacon B included in the frame, the transceiver 20 uses a direct wave that has arrived through the communication path P0 and a reflected wave that has arrived through any of the communication paths P1 to P4, or a plurality of reflected waves. The tracking is performed by adjusting the directivity of a plurality of incoming waves, and simultaneously the signal quality of the plurality of incoming waves is monitored. A communication path is selected and determined from the result of monitoring, and communication is performed by the transmission / reception unit 21. When the incoming wave used is interrupted, the signal quality is rapidly deteriorated, so that the quality monitor unit 22 can immediately detect it. When the quality monitoring unit 22 detects that the quality of the incoming wave used for communication has deteriorated beyond a predetermined level, the communication path selection unit 24 immediately tracks the quality monitoring unit 22 The communication is continued by switching to the communication path with the best quality among the other incoming waves being monitored. As a result, even when the communication path used for communication is interrupted by a person passing through, stable communication can be ensured without interrupting communication. The quality monitor unit 22 may monitor, for example, received signal strength detection (RSSI: Receive Signal Strength Indication) as the received power of the received signal, similarly to the conventional detection unit. Further, the delay dispersion may be monitored in addition to the received power from the frame of the signal transmitted by the transceiver 10. Further, at least one of a signal-to-noise ratio (SNR), a signal-to-interference and noise ratio (SINR), a bit error rate, a frame error rate, and a packet error rate is always set. Measurement may be performed to monitor the signal-to-noise ratio, signal-to-interference / noise ratio, bit error rate, frame error rate, packet error rate, etc. of the plurality of signal waves. The method will be described in detail below.

  FIG. 3 shows the internal structure of the tracking slot TS0 constituting the frame as an example of the tracking slot. Since the internal structure of the tracking slot constituting the frame is substantially the same, detailed description of the internal structure of the other tracking slots is omitted.

  As shown in FIG. 3A, in the tracking slot TS0 in the frame, the quality monitoring unit 22 monitors the tracking tracking pattern for tracking the beam, that is, the signal, and the quality of the beam, that is, the signal. Patterns for quality monitoring are included. For example, as shown in FIG. 3B, the quality monitor pattern may be used for delay dispersion measurement described in detail later. The communication path selection unit 24 selects a suitable communication path mainly based on the received power of the beam and the delay dispersion, but the present invention is not limited to this. The quality monitor pattern may be used for BER (Bit Error Rate) measurement as shown in FIG. Further, signal tracking and communication path quality monitoring may be performed simultaneously in the tracking pattern. Further, for example, as shown in FIG. 3D, a pattern capable of simultaneously performing tracking and quality monitoring may be used. In addition to this, for example, a pattern for monitoring a signal-to-noise ratio, a signal-to-interference / noise ratio, a frame error rate, and a packet error rate may be provided. Furthermore, when using two or more measured values such as delay dispersion, signal-to-noise ratio, signal-to-interference / noise ratio, frame error rate, and packet error rate for quality evaluation, for example, measured values of delay dispersion May be evaluated by weighting each measured value according to the importance. Or, compare the delay dispersion first, and if they are approximately the same, compare the signal-to-noise ratio, or if the delay dispersion is high, do not select even if the received power is high. When the high measured values are substantially the same, the next measured values may be compared. These can be selected according to the characteristics of the signal wave used and the implementation.

  Further, in the conventional tracking tracking, only the beam used for the signal and the adjacent beam have been tracked. However, the quality monitor unit 22 of the present embodiment has a plurality of beams, that is, discrete signals with greatly different arrival directions of the signals. The operation of tracking a plurality of beams propagating in this manner, that is, a plurality of signal blocks, is performed. Hereinafter, the tracking tracking executed by the quality monitoring unit 22 of the present embodiment configured as described above will be described in detail.

  FIG. 4 is a diagram illustrating the relationship between the arrangement of the transceivers 10 and 20 and the beam communication paths P0 to P2. FIG. 5 is a diagram showing a lump of signals (hereinafter referred to as “cluster”) formed by the three communication paths P0 to P2 viewed from the transceiver 20 on the cross section A of FIG. With reference to FIG. 4 and FIG. 5, the tracking tracking executed by the quality monitor unit 22 of the present embodiment will be described.

  As shown in FIG. 4, in this example, the two transceivers 10 and 20 are arranged to face each other, and the communication path P0 by the direct line-of-sight wave and the two reflected wave communication paths P1 and P2 by the reflectors R1 and R2 Is present. As shown in FIG. 5, the communication path P0 by direct line-of-sight waves forms a cluster C0, and the two reflected wave communication paths P1 and P2 by reflectors R1 and R2 form clusters C1 and C2. For this reason, the clusters C1, C2, and C3 exist apart from each other, and are therefore received by the transceiver 20 as discrete signal waves.

  In the conventional tracking tracking, only the beam used for communication and the adjacent beam are tracked. Therefore, as shown in FIG. 5, it is not possible to detect other clusters that exist apart from each other. Therefore, when the beam used for communication is interrupted, adjacent beams are also interrupted at the same time, making it difficult to continue communication. Unlike the conventional tracking tracking, the quality monitoring unit 22 according to the present embodiment first has a plurality of clusters C0 that are separated from each other and are formed by communication paths having greatly different arrival directions, for example, P0, P1, and P2. , C1 and C2 are always tracked.

  Each cluster includes a plurality of beams. In FIG. 5, the cluster C1 includes nine beams, the cluster C2 includes six beams, and the cluster C3 includes four beams. For each cluster, a beam suitable for communication is selected from a plurality of beams included in the cluster. This operation is equivalent to conventional beam tracking. In FIG. 5, beams BC0, BC1, and BC2 are selected as suitable beams for communication among the clusters C1, C2, and C3, and the beams adjacent to the beams are adjacent beams. In this way, the beam BC0, BC1, BC2 suitable for communication is always selected for each cluster, and the beam used for communication is selected from the plurality of beams suitable for communication selected for each cluster. Even if a cluster of communication paths used for communication is cut off due to a person passing by, etc., communication can be performed by switching to a suitable communication beam in the cluster of other communication paths instantly. , Communication can be maintained continuously.

  FIG. 6 is a diagram for explaining the outline of the operation of the wireless communication system 1 of the present embodiment configured as described above. In FIG. 6, the transceiver 10 is illustrated as a personal computer in which the transceiver 10 is installed at home, and the transceiver 20 is illustrated as a mobile phone. With reference to FIG. 6, the case where the transceivers 10 and 20 communicate with each other in the wireless communication system 1 of the present embodiment configured as described above will be described.

  As shown in FIG. 6, the transmitter / receiver 20 communicates with, for example, a direct-wave communication path P0. Is monitored (FIG. 6A). When the communication path P0 is blocked by an obstacle due to a person passing or the like and cannot be used for communication, the quality monitor unit 22 of the transceiver 20 detects that the communication path selection unit 24 of the transceiver 20 The quality monitoring unit 22 tracks and the quality monitoring unit 22 immediately selects a suitable communication path P1 from among the other communication paths monitored by the quality monitoring unit 22, and the directivity control unit 25 selects the selected communication path P1. The communication is continued by changing the directivity of the directional antenna 20a in the direction ((B) of FIG. 6). Even after switching the communication path from P0 to P1, the quality monitor unit 22 of the transceiver 20 can search for a new suitable communication path P2 and similarly select the communication path by always tracking the communication path P2. The situation is always secured ((C) in FIG. 6). For this reason, the wireless communication system 1 always performs communication using a good communication path, and communication is not interrupted.

<Preferred communication path formation>
In order to stabilize communication between the transceiver 10 and the transceiver 20, it is desirable to form a communication path by arranging a plurality of reflectors between or around the transceiver 10 and the transceiver 20. Already explained. The inventor conducted various studies on the conditions for forming a suitable communication path, and clarified preferable reflectors and reflector installation conditions. Hereinafter, preferred reflectors and installation conditions thereof will be described based on the results of experiments conducted by the inventors. In the present embodiment, the reflector that forms the communication path constitutes a part of the communication path forming unit.
About preferred reflectors

  In order to specify the conditions of a preferable reflector disposed between the transmitter Tx and the receiver Rx, an experiment for measuring the received power by changing the shape and size of the reflector was performed, and the results are shown in FIGS. Summarized in FIG. 7 is a diagram illustrating a relationship among the transmitter Tx, the receiver Rx, and the reflector R when the experiment is performed. The transmitter Tx and the receiver Rx were placed on a metal desk. The beam width of the directional antenna At of the transmitter Tx is 15 degrees, and the beam width of the directional antenna Ar of the receiver Rx is 60 degrees. In addition, the directional antenna At of the transmitter Tx and the directional antenna Ar of the receiver Rx are equidistant from the surface including the reflecting surface of the reflector R, and the tip of the directional antenna At of the transmitter Tx. And the tip of the directional antenna Ar of the receiver Rx and the reflection point of the reflector R are arranged to form an equilateral triangle. In order to obtain a suitable reflected wave, the reflector R needs to have a reflectivity that is high enough to reflect the incoming beam and at least produce a reflected wave that can be identified as a beam to the receiver Rx. A metal tape was used as the reflector R, and was placed on a polystyrene foam. The following experiment was conducted by changing the shape and length of the metal tape.

  FIG. 8 is a diagram illustrating a change in received power with respect to the shape of the metal tape. From FIG. 8, it was demonstrated that the received power increases when the metal tape is lengthened up to a length of 10 cm. It can be seen that the most preferred shape is 10 cm positive.

  FIG. 9 is a diagram showing changes in received power and delay dispersion with respect to the length of the metal tape. In this figure, it can be seen that when the length of the metal tape is 30 cm, the received power is maximized and the delay dispersion is minimized. Metal tape has the highest reflectivity. When a reflector having such a high reflectivity is in the energy of the beam, the reflector is reflected until the reflection area of the reflector reaches a predetermined value, that is, a size that reflects all of the energy of the incoming beam. The reflected energy increases in proportion to the reflection area. For this reason, it can be seen that the received power of the reflected wave tends to increase until the length of the metal tape reaches 30 cm.

  It can be seen from the graphs of FIGS. 7 to 9 that when the reflection area of the reflector becomes larger than a predetermined value, the received power increases and the delay dispersion decreases. Further, it is considered that the shape of the reflector is more advantageous when the shape of the reflection region is large, such as a square or a circle.

  As described above, the wireless communication system according to the present invention directly transmits a signal wave transmitted from the transmission apparatus, a reception apparatus that includes the directional antenna having directivity and receives the signal wave, and a signal wave transmitted from the transmission apparatus. Or a communication path forming unit that forms a communication path that reflects and guides to a directional antenna of the receiving apparatus, wherein the receiving apparatus selects a suitable signal wave communication path. Directing the directivity direction of the directional antenna to the preferred communication path selected by the preferred route selection means, and causing the directional antenna to receive the signal wave that has passed through the preferred communication path selected by the preferred route selection means An antenna control unit, and the preferred path selection unit always tracks a plurality of signal waves including a signal wave that has passed through the communication path formed by the communication path forming unit, and receives each direction and reception of the plurality of signal waves. The quality is constantly measured, and a suitable signal wave communication path is selected based on the measured direction of the plurality of signal waves and the reception quality, and the antenna control unit always selects a suitable communication path selected by the suitable path selection unit. The directional antenna is directed so that the signal wave that has passed through the preferred communication path selected by the preferred route selection means is continuously received by the directional antenna, so communication is always performed through the preferred communication path. Even if one of the communication paths performing communication is blocked by an obstacle, the signal wave can be continuously received without interruption. For this reason, for example, the present invention can be applied to the case where wireless communication is performed using an electromagnetic wave that has strong straightness such as a millimeter wave band, a large attenuation due to propagation, and cannot be expected to be diffracted.

  Moreover, in the wireless communication system of the above-described embodiment, the case where the communication path forming unit of the present invention is applied together with the transmission apparatus and the reception apparatus that automatically select the communication path has been described, but the present invention is not limited to this. . The communication path forming unit of the present invention can be installed alone. For example, it is a reflector having a high reflectivity, and a signal wave passing through a communication path formed by a communication path formed by a place where the delay dispersion is low by human measurement of the delay dispersion, specifically, a communication path unit includes a direct wave. Arranged so that the communication path is formed in consideration of the beam width of the directional antenna of the receiving device so that it is not received by the directional antenna of the receiving device superimposed on the signal wave passing through another communication path Or when a signal wave passing through a communication path formed by a communication path forming unit is received by a directional antenna of a receiving apparatus superimposed on a signal wave passing through any other communication path including a direct wave Is directed to the receiving device so that the difference between the received power of the signal wave passing through the communication path formed by the communication path forming unit and the received power of the signal wave passing through any of the other communication paths exceeds a predetermined threshold. Antenna antenna and transmitter directivity Considering the distance between the tenors, the distance between the directional antenna of the receiving device and the directional antenna of the transmitting device and the communication path forming unit, the reflectance of the communication path forming unit, and the beam width of the directional antenna of the receiving device A special transmitter or receiver is not essential if it is arranged so as to form a communication path.

  Heretofore, the wireless communication system and the communication path forming unit thereof have been described. The communication path forming unit constituting the wireless communication system of the present invention may be simply affixed to a furniture such as a wall, a personal computer, a keyboard, a desk, or a book shelf so that the predetermined condition is satisfied. Or you may form with a circular metal plate. Thus, the structure is simple and can be constructed easily and inexpensively. If this communication path forming unit, a controllable directional antenna, and a transmission / reception device for controlling the directivity of the directional antenna are provided, the transmission / reception device can also be applied to various communication devices such as mobile phones and computers. For example, a general computer including a CPU and a memory can be operated by a program that functions as each of the above-described units. In addition, since high-frequency electromagnetic waves such as millimeter waves that can be used in the wireless communication system of the present invention are not restricted, a wide band can be used. For example, an in-vehicle millimeter wave radar, a 60 GHz band millimeter wave video system (wireless home) Link), 120 GHz band high-definition video uncompressed transmission system, inter-vehicle / road-to-vehicle wireless system, 55 GHz band millimeter-wave mobile camera for broadcasting, weapon / dangerous material fluoroscopic scanner (camera), concrete crack inspection device, foreign material contamination inspection device, in envelope It can be used for various applications such as a dangerous goods inspection system and HDTV (High Definition Television) wireless transmission at home.

It is a schematic block diagram of the radio | wireless communications system of one embodiment of this invention. It is a figure which shows an example of the frame structure which the frame formation part of the transmitter / receiver which comprises the radio | wireless communications system of FIG. 1 forms. It is a figure which shows an example of the tracking slot contained in the flame | frame of FIG. It is a figure which shows the relationship between arrangement | positioning of the transmitter / receiver and communication path which comprise the radio | wireless communications system of one embodiment of this invention. It is a figure which shows the cluster formed of the communication path seen from the transmitter / receiver of the slave side which comprises the radio | wireless communications system of FIG. It is a figure explaining the outline | summary of operation | movement of the radio | wireless communications system of FIG. It is a figure explaining the relationship between a transmitter, a receiver, and a reflector. It is a figure which shows the change of the received power with respect to the shape of the metal tape measured on condition of FIG. It is a figure which shows the change of the received power and delay dispersion | variation with respect to the length of the metal tape measured on condition of FIG. It is a figure which shows the state which the conventional transmitter / receiver is communicating using a direct wave. It is a figure which shows the state which the conventional transmitter / receiver switches to an indirect wave and is communicating, when it obstruct | occludes with the obstruction in the direct wave. It is a figure explaining the process in which the conventional transmitter / receiver performs communication, switching a communication path.

10 Transceiver (Transmitter)
10a Directional antenna 11 Transmission / reception unit 12 Communication path selection unit 13 Frame forming unit 14 Directivity control unit (antenna control unit)
20 Transceiver (Receiver)
20a Directional antenna 21 Transmitter / receiver 22 Quality monitor (preferred route selection means)
23 memory (preferred route selection means)
24 communication route selection unit (preferred route selection means)
25 Directivity control unit (antenna control unit)
P0 Direct wave communication path P1 to P4 Reflected wave communication path R1 to R3 Reflector (communication path forming unit)
50 Delay dispersion calculation unit 51 ADC
52 N-stage shift register unit 53 Reference code data string unit 55 Multiplication circuit 100 Conventional transceiver (transmitter)
100a Directional antenna 200 Conventional transceiver (receiver)
200a Directional antenna

Claims (6)

A transmission device for transmitting a signal wave;
A receiving device for receiving a signal wave with a directional antenna having directivity;
A communication path forming unit that forms a communication path that directly or reflects a signal wave transmitted from the transmitting apparatus and guides the signal wave to the directional antenna of the receiving apparatus,
The receiving device is:
Preferred route selection means for selecting a suitable signal wave communication route;
Directing the directivity direction of the directional antenna to the preferred communication path selected by the preferred path selection means, and receiving the signal wave that has passed through the preferred communication path selected by the preferred path selection means to the directional antenna An antenna control unit
The suitable path selection means always tracks a plurality of signal waves including a signal wave that has passed through a communication path formed by the communication path forming unit, and always measures the direction and reception quality of each of the plurality of signal waves. Then, select a suitable signal wave communication path based on the measured direction and reception quality of the plurality of signal waves,
The antenna controller preferably directs the direction of the directivity of the directional antenna to the preferred communication path selected by the preferred path selection means, and the preferred communication selected by the preferred path selection means for the directional antenna. Continue to receive the signal wave that has passed through the path,
The directional antenna is a beam forming antenna;
The suitable route selection means selects a communication route of a suitable signal wave by tracking a signal that arrives through the communication route ,
Signal tracking by the preferred route selection means includes:
The tracking of a plurality of beams included in a cluster, for each cluster of a plurality of communication paths existing in a discrete manner ,
The preferred route selection means includes:
By tracking the plurality of beams, a beam suitable for communication is always selected for each cluster,
Selection of a suitable signal wave communication path by the preferred path selection means,
This is the selection of communication paths using beams suitable for multiple communications selected for each cluster.
Wireless communication system comprising a call. The preferred path selection means constantly measures the direction and reception quality of each of the signal wave passing through the communication path used for communication and the other plurality of signal waves, and the communication is received by the directional antenna. When it is determined that the quality of the signal wave passing through the communication path used has deteriorated from a predetermined level, the antenna control unit selects the suitable path selection unit based on the reception quality of each of the other plurality of signal waves. suitable communication path, the direction of the directivity of the directional antenna Te toggle, characterized in that to continue receiving the signal wave, a radio communication system according to claim 1, wherein.   The wireless communication system according to claim 1, wherein the communication path forming unit is formed of a reflector having a high reflectance.   The communication path forming unit receives a signal wave passing through a communication path formed by the communication path forming unit with a signal wave passing through another communication path including a direct wave and receives the signal wave on the directional antenna of the receiving apparatus. 2. The wireless communication according to claim 1, wherein the reflector is arranged so as to form a communication path in consideration of a beam width of the directional antenna of the receiving device. system.   The communication path forming unit is configured to superimpose a signal wave passing through a communication path formed by the communication path forming unit with a signal wave passing through any other communication path including a direct wave. The difference between the received power of the signal wave passing through the communication path formed by the communication path forming unit and the received power of the signal wave passing through any of the other communication paths is greater than a predetermined threshold value. The distance between the directional antenna of the receiver and the directional antenna of the transmitter, the distance between the directional antenna of the receiver and the directional antenna of the transmitter and the communication path forming unit, The wireless device according to claim 1, wherein the wireless communication device is a reflector arranged to form a communication path in consideration of a reflectance of the communication path forming unit and a beam width of a directional antenna of the receiving apparatus. Communication system Beam.   The wireless communication system according to claim 1, wherein the communication path forming unit further includes an absorber disposed around the communication path to weaken the intensity of the signal wave.

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