JP4044089B2 - Road-to-vehicle wireless communication system - Google Patents

Description

  The present invention relates to a road-to-vehicle wireless communication system that performs communication between wireless ports arranged at predetermined intervals along a road and a vehicle traveling on the road.

  Currently, development of a road-to-vehicle wireless communication system that performs communication between a wireless port arranged along a road and a vehicle traveling on the road is in progress. FIG. 9 shows a typical example of an existing road-to-vehicle wireless communication system.

  A plurality of wireless ports 1001 to 1004 are arranged at predetermined intervals along the road, and are connected to a wireless control station 1008 having jurisdiction over them by a transmission path. Each wireless port transmits and receives wirelessly to / from cars 1005 to 1007 traveling on the road.

  Here, when the large vehicle 1009 is located between the vehicle 1006 traveling on the road and the wireless port 1002 that transmits and receives to / from the vehicle 1006, the traveling vehicle 1006 and the wireless port are shadowed by the large vehicle 1009. There is a problem that the communication quality with 1002 deteriorates.

  As a method of solving the deterioration of the downlink from the wireless port to the car, the traveling vehicle 1006 is configured to adaptively change the antenna pattern of another wireless port 1003 located in a place where the traveling vehicle 1006 can be seen without an obstacle. It is conceivable to enable reception. However, if the radio port or radio control station quickly detects the occurrence of shadowing and performs antenna control of the radio port 1003, there is a problem that complicated control processing is required.

  In order to overcome such a problem, a configuration has been proposed in which signals having the same contents are simultaneously transmitted from a plurality of wireless ports installed in the jurisdiction area of the same control station. According to this, even if a signal from one radio port is blocked by an obstacle, shadowing is avoided by receiving a signal having the same content from a neighboring radio port. However, in this method, a plurality of signals transmitted from different directions at different transmission distances are received on the mobile station side while shadowing is not occurring. For this reason, there is a problem that the influence of fading is large and the wireless communication continues in a state where the communication quality is deteriorated.

  Further, in the conventional road-to-vehicle wireless communication system, every time the boundary of the control area of each control station is crossed, the communication channel used by the wireless port in the control area of the control station must be channeled. There's a problem.

  Further, when the road-to-vehicle wireless communication system is applied to ITS (Intelligent Road Traffic System), an attempt has been made to move the area where wireless communication is performed at the same frequency by following the vehicle. In the wireless communication system, there is a problem that a random channel search must be performed each time the traveling speed of the vehicle does not match the moving speed of the area.

  In order to solve the above-described problems, a first object of the present invention is to provide a road-to-vehicle wireless communication system that can reduce the influence of shadowing while avoiding fading.

  A second object of the present invention is to provide a road-to-vehicle wireless communication system that does not require a channel search at the boundary between areas served by wireless port groups.

  A third object of the present invention is to shift to a corresponding individual communication channel without performing a random channel search even when the speed of a traveling vehicle deviates from the moving speed of an area communicating at the same frequency. An object is to provide a road-to-vehicle wireless communication system capable of performing the above.

  A fourth object of the present invention is to provide a mobile station radio apparatus for a road-to-vehicle radio communication system that does not require a channel search at an area boundary.

  The fifth object of the present invention is to shift to a dedicated channel of the corresponding frequency without the need for a random channel search even when the speed of the traveling vehicle does not match the moving speed of the communication area at the same frequency. An object of the present invention is to provide a mobile station radio apparatus for a road-to-vehicle radio communication system.

  In order to achieve the first object, a road-to-vehicle wireless communication system of the present invention includes a control station, a plurality of wireless ports installed at predetermined intervals in an area controlled by the control station, and these wireless ports. Each radio port has a multicast channel dedicated to downlink from the radio port to the vehicle, and an individual transmission channel that transmits at an individual frequency, and each mobile station radio Has two series of receiving circuits. Of the plurality of wireless ports, the same information is simultaneously transmitted from two or more wireless ports using a multicast channel, and the mobile station radio receives the multicast channel regularly in one of the two receiving circuits. To do.

  As a modulation method for transmission on a multicast channel, an OFDM (Orthogonal Frequency Division Multiplexing) method is used, and when a predetermined interval between wireless ports is L meters, a guard time of (L / 300) microseconds or more is provided. Take a frame structure. A guard time of (L / 300) microseconds or more is defined as a propagation relative of (L / 300) microseconds or less for the same signal arriving at a speed of light from two adjacent wireless ports via a multicast channel. This is because a delay difference occurs.

  When using normal phase shift keying (PSK) or quadrature amplitude modulation (QAM) for the OFDM subcarrier, the guard time length is Ts × 0.2 seconds or less so as not to be affected by frequency selective fading. Preferably, it is set to Ts × 0.05 seconds or less. Here, Ts is the reciprocal of the modulation symbol rate of the OFDM subcarrier and is called a symbol period. The reason why the guard time is Ts × 0.2 seconds or less is that this range is a range in which the influence of frequency selective fading is not so great.

  For example, an emergency signal necessary for automatic driving unique to ITS (Intelligent Transport System) is placed on the multicast channel having such a frame configuration. As a result, the influence of fading can be avoided and the influence of shadowing can be effectively reduced.

  In order to achieve the second object, a road-to-vehicle wireless communication system includes a control station, a plurality of wireless ports, and a mobile station radio that performs wireless communication with these wireless ports. One or more downlink dedicated multicast channels to the machine are used. At least two or more wireless ports among the plurality of wireless ports simultaneously transmit the same information through the same multicast channel. The same information includes a color code that identifies a group to which a wireless port that transmits this information simultaneously belongs.

The mobile station radio has two series of receiving circuits, and one of these receives the color code constantly. The mobile station radio compares the color code received this time with the color code received last time, and if the result of comparison is that the color code has changed to a different color code (that is, a group of radio ports that transmit the same information on the same multicast channel) Is automatically set to the communication channel used at that time at the start point of the area served by the group of wireless ports corresponding to the new color code, based on the color code after the change.

  In the same information transmitted by the wireless port through the multicast channel, in addition to the color code described above, the identification number of the communication channel used at that time at the start point of the area served by the group represented by the same color code Is also included.

  Such a road-to-vehicle wireless communication system eliminates the need for channel search control even when an area using a different multicast channel is entered, reducing the control load on the infrastructure side (mobile station side).

  In addition, when the region itself that communicates with the communication channel of the same frequency moves at an arbitrary speed in ITS or the like, each wireless port further has a function of switching the beam pattern of the antenna according to the movement of the mobile station. As a result, communication can be continued on the same channel, and the quality of wireless communication is improved.

  In order to achieve the third object, in the road-to-vehicle wireless communication system, each wireless port has a function of switching the beam pattern of the antenna according to the movement of the mobile station, and is an area where communication can be performed using a communication channel of the same frequency. An identification code indicating the moving speed is simultaneously transmitted on the multicast channel. The mobile station radio detects the moving speed of the mobile station itself, compares the moving speed of the mobile station with the moving speed in the same frequency region sent via the multicast channel, and obtains the speed difference. When the speed difference becomes larger than the threshold value on the plus side, a change request to the next communication channel (that is, the next communication channel on the traveling direction side of the mobile station) is transmitted to the wireless port. When the speed difference becomes larger than the threshold value on the negative side, a change request to the next communication channel (the communication channel behind the mobile station) is transmitted to the wireless port.

  With such a configuration, even when the moving speed of the traveling vehicle does not match the moving speed of the area communicating at the same frequency by ITS or the like, it is possible to smoothly shift to an appropriate communication channel.

  In order to achieve the fourth object, the mobile station radio of the present invention is a group of radio ports for simultaneously transmitting the same information on the same multicast channel from the information sent from the radio port on the multicast channel. A color code extraction circuit for extracting a color code representing the communication channel, a communication channel identification number extraction circuit for extracting the identification number of the communication channel used at the time at the start point of the area served by this wireless port group, and this extraction A comparison circuit that compares the color code extracted with the previous color code and a communication channel that starts communication on the communication channel corresponding to the color code after the change when the current color code changes from the previous color code And a setting circuit.

  In order to achieve the fifth object of the present invention, the mobile station radio of the present invention represents the moving speed of the area where communication is performed at the same frequency from the information sent from the radio port through the multicast channel. The area speed code extraction circuit for extracting the area speed code, the vehicle speed detection circuit for detecting the speed of the vehicle on which the mobile station radio is mounted, the difference between the detected vehicle speed and the area movement speed is obtained, and the speed difference is calculated. A comparison circuit for comparing with a threshold value, and a communication channel addition / subtraction instruction generation circuit for generating a change request to a communication channel having a frequency suitable for the vehicle speed based on the comparison result.

  As a first feature of the present invention, each wireless port uses a multicast channel and a dedicated communication channel, and at least two or more wireless ports transmit the same information simultaneously on the same multicast channel. The mobile station radio has two series of receiving circuits and steadily receives a multicast channel signal from the radio port in one series. Thereby, the influence of shadowing can be reduced.

  As a second feature of the present invention, each wireless port has a multicast channel signal, a color code for identifying a group to which the wireless port belongs, and a communication channel used at that time at the start point of the area served by the group. The ID number is put on and sent. The mobile station radio compares the current color code with the previously received color code. If the color codes are different as a result of the comparison, an individual communication channel is set as the communication channel used at that time at the start point of the area served by the group corresponding to the new color code. Therefore, channel search at the handoff destination becomes unnecessary at the area boundary.

  As a third feature of the present invention, each wireless port transmits an area speed code for recognizing a moving speed of an area in which communication can be continued on the same channel on a multicast channel. The mobile station radio compares the traveling speed of the vehicle on which the mobile station radio is mounted with the transmitted area movement speed, and determines the difference. When the speed difference exceeds a threshold value, the communication channel is set to a channel corresponding to the vehicle speed. As a result, even when the speed of the mobile station radio device deviates from the moving speed of the area communicated on the same channel, it is possible to quickly shift to the optimum communication channel.

  The present invention is described in detail below.

<First Embodiment>
FIG. 1 is a diagram showing a configuration example of a road-vehicle wireless communication system according to a first embodiment of the present invention. The road-to-vehicle wireless communication system of FIG. 1 includes a wireless control station 108, a plurality of wireless ports 101 to 104 installed at predetermined intervals L along a road, and mobile stations mounted on vehicles 105 to 107 traveling on the road. Wireless devices 105A to 107A.

  FIG. 2 shows a frame configuration of the multicast channel 201, the dedicated transmission channels F1 to F4, and the multicast channel 201 used in downlink communication from the radio port shown in FIG. 1 to the mobile station radio. At least two of the plurality of wireless ports 101 to 104 in the area controlled by the same control station 108 are connected to the mobile station wireless devices 105A to 107A using, for example, a downlink multicast channel 201 having a frequency of Fm. At the same time, the same payload 202 is transmitted. An OFDM (Orthogonal Frequency Division Multiplex) method is used as a modulation method for the transmission. That is, the fixed frequency Fm is time-divided and several hundred carriers (subcarriers) orthogonal to each other are used.

Since each carrier wave has an orthogonal relationship, its frequency components can be superimposed on each other, and much more carrier waves can be packed as compared with a normal frequency division multiplexing system.

  On the other hand, the individual transmission channels F1 to F4 are assigned by the control station 108 according to the position, time, and the like.

  Each mobile station radio 105A-107A has two series of receiving circuits, and in one of the two series of receiving circuits, constantly receives the same information transmitted from the radio port through the multicast channel, and others The individual frequency channel communication is performed in one series. In the payload 202 of the multicast channel, for example, an emergency signal required in a system such as ITS-specific automatic operation is placed. Thus, even when shadowing by the large vehicle 109 occurs in the mobile station radio 106A, an emergency signal or the like can be reliably received from the adjacent radio port 103 via the multicast channel. A detailed configuration of the mobile station radio having two reception circuits will be described later with reference to FIG. 4 and FIG.

  As a frame configuration of the multicast channel of the present invention, a guard time 203 having a specific length is provided between frames as shown in FIG. That is, when the distance between adjacent wireless ports is L meters, the guard time is (L / 300) microseconds or more.

  Since the propagation speed of the radio wave is 3 × 10 8 [m / s], the difference in propagation relative delay in which the multicast channel signal having the same content reaches the traveling vehicle 106 from two adjacent wireless ports is the road of the traveling vehicle 106 Regardless of the upper position (L / 300), it becomes less than microseconds. Therefore, OFDM is used as the modulation method of the multicast channel, and a guard time of (L / 300) microseconds or more is provided so that the two signals do not conflict.

  In addition, when normal PSK (phase shift keying) or QAM (quadrature amplitude modulation) is used for the OFDM subcarrier, the length of the guard time is set to Ts × 0 so as not to be affected by frequency selective fading. .2 seconds or less, preferably Ts × 0.05 seconds or less. Here, Ts is the reciprocal of the modulation symbol rate of the OFDM subcarrier and is called a symbol period.

If the guard time is within the above range, deterioration due to frequency selective fading can be prevented even when a plurality of radio waves are received. By using the OFDM method, even when high-speed transmission is required, by adjusting the number of subcarrier divisions, the above condition, that is, the guard time 203 is (L / 300) microseconds or more and Ts × 0. The condition of 2 seconds or less (preferably Ts × 0.05 seconds or less) can be realized. Here, an example in which PSK or QAM is used as a subcarrier modulation scheme is shown. However, when an anti-multiwave modulation scheme such as DSK, PSK-RZ, or PSK-VP is used, the upper limit of the guard time is (Ts It is also conceivable to extend it to about × 1) seconds to (Ts × 2) seconds.

  In addition, although the present Example showed the application example to ITS of road-to-vehicle communication, it is also possible to apply to the communication and broadcasting system which need to notify a signal with high reliability at the time of emergency.

Second Embodiment
FIG. 3 is a diagram showing a configuration of a road-to-vehicle radio communication system according to the second embodiment of the present invention, and FIG. 4 is a diagram showing a mobile station radio used in the system of FIG.

  As a feature of the second embodiment, as a payload of the downlink dedicated multicast channel shown in FIG. 2, a group code for identifying a group of radio ports simultaneously transmitting using the same multicast channel (herein referred to as a color code) And the identification number of the communication channel (for example, the downlink individual communication channel or the uplink individual communication channel in FIG. 2) used at the start point of the area served by the group of wireless ports that transmit simultaneously.

  In the example of FIG. 3, the wireless ports 303 and 304 are connected to the wireless control station 301 and transmit the same multicast channel signal. This multicast channel signal includes a color code #a for identifying a group to which the wireless ports 303 and 304 that transmit signals using the same multicast belong as one of payloads. This color code #a is assigned in advance to the radio control station 301 to which these radio ports are connected.

  In FIG. 3, two ports 303 and 302 are depicted as wireless ports connected to the wireless control station 301, but a plurality of wireless ports are connected to the control station 301. It has jurisdiction over a group of one or more radio ports consisting of at least two radio ports. Each group of wireless ports transmits the same information simultaneously using the same multicast channel. Therefore, not only the color code #a of the group to which the wireless ports 303 and 304 belong, but also the color code of another wireless port group using another multicast channel is assigned to the wireless control station 301 in advance.

  As another payload included in the multicast channel signal, the group to which the wireless ports 303 and 304 belong is used at the start point of the area where the service is performed (located on the left hand side of FIG. 3 and not shown in FIG. 3) at that time. Contains the identification number of the communication channel.

  On the other hand, the wireless ports 305 and 306 are connected to the wireless control station 302, and these two wireless ports transmit the same multicast channel signal. The color code #b representing the group to which the wireless ports 305 and 306 belong is assigned to the wireless control station 302 in advance. The payload of the multicast channel signal transmitted from the wireless ports 305 and 306 to the mobile station 307 includes the color code #b. As another payload, the identification number of the communication channel used at that time at the start point 308 of the area served by the group to which the wireless ports 305 and 306 belong (in FIG. 3, the identification number of the communication channel of the frequency F1). included.

  A multicast channel signal including the color code of the group to which the radio port belongs and the identification number of the communication channel used at that time at the start point of the area served by this group is received by the mobile station radio 308.

  FIG. 4 shows a configuration example of the mobile station radio 308 used in the road-to-vehicle radio communication system of FIG. The mobile station radio 308 includes an antenna 401, a high frequency circuit 402, a multicast channel reception circuit 403, and a dedicated transmission channel reception circuit 412. The mobile station radio 308 receives the multicast channel signal steadily by the multicast channel receiving circuit 403 out of the two types (two series) of receiving circuits 403 and 412, and the other receiving circuit 412 receives the individual downlink signal. Receives signals sent on a frequency communication channel.

  A digital signal from the multicast channel demodulated and detected by the reception circuit 403 is input to the control circuit 405. In the control circuit 405, the color code extraction circuit 407 extracts a color code representing the group to which the transmission source wireless port belongs from the demodulated digital signal of the multicast channel. The extracted color code is input to the color code comparison circuit 410. The color code storage circuit 406 stores the previously extracted color code, and the previous color code is also input to the color code comparison circuit 410 at the same time.

  The color code comparison circuit 410 compares the color code extracted this time with the previous color code. As a result of the comparison, when the color code received this time is different from the previous color code, the color code comparison circuit 410 outputs a change information signal to the call channel setting circuit 411. This change information signal triggers the call channel setting circuit 411.

  On the other hand, the communication channel identification number extraction circuit 408 recognizes the communication channel used at that time from the demodulated multicast digital signal at the start point of the area served by the group to which the wireless port that transmitted the multicast channel signal belongs. Extract the number. The extracted communication channel identification number is input to the call channel setting circuit 411. The communication channel setting circuit 411 triggered by the change information signal from the color code comparison circuit 410 sends a command to the transmission circuit 404 to start communication on the communication channel corresponding to the identification number based on the identification number of the communication channel. Send. The transmission circuit 404 controls the high frequency circuit 402 and transmits through the antenna 401 so that the transmission signal transmitted from the transmission signal generation circuit 409 can be transmitted through the communication channel specified by the command. With such a configuration, even when entering an area using a different multicast channel, setting to the corresponding communication channel is automatically performed smoothly.

  The mobile station radio having such a configuration constantly receives a multicast channel signal, and at the time of the color code of the group to which the radio port that transmitted the multicast channel signal belongs and the start point of the area served by this group. Communication channel information representing the frequency being used can be used. Therefore, when the mobile station radio 308 enters the communication area of #b from the communication area of #a, the change is immediately detected, and the start point of the new communication area is determined based on the change of the color code. Thus, it is possible to quickly switch to the frequency F1 used at that time. That is, channel search control such as random search becomes unnecessary, and there is an advantage that the control load on the infrastructure side of the road-to-vehicle wireless communication system is reduced.

  The color code representing the same multicast channel is arranged at the beginning of the multicast channel frame shown in FIG. 2, immediately after the synchronization bit string at the beginning of the frame, or immediately before the error control bit string at the end. preferable. Such an arrangement reduces the impact of breaking a portion of the burst that transmits the color code due to co-channel interference at the boundary 308 (FIG. 3) of the radio ports belonging to different groups (ie using different multicast channels). be able to.

  As in the second embodiment, even when spanning a group of a plurality of radio ports, an emergency signal payload is placed on a frame at a specific position in the superframe, so that the mobile station radio can As in the first embodiment, the signal can be received reliably.

  As a modification of the road-to-vehicle wireless communication system of the second embodiment, in addition to the configurations and functions shown in FIGS. 3 and 4, each wireless port has a function of switching the beam pattern of the antenna according to the movement of the mobile station radio. Is possible.

  FIG. 5 is a diagram for explaining the antenna switching function of each wireless port. As shown in FIG. 5, mobile stations (eg, 505, 506, 507, 508, and 509) in the service area on the road communicate with each of the wireless ports 501, 502, 503, and 504 through the same communication channel. So that the beam pattern of the antenna can be switched along with the movement of the mobile station. In FIG. 5, it is assumed that the region using the same frequency moves at a speed 511. The beam pattern can be switched by a known method such as changing the antenna directivity using an adaptive array antenna that electronically changes the weighting of each signal of the antenna elements arranged in an array as necessary. .

    FIG. 6 is a diagram for explaining the moving speed of the region using the same frequency shown in FIG. For example, at a certain time t1, there is an area in which communication is performed at the frequency F3 in the vicinity immediately below the wireless port 503, and communication is performed at the frequency F2 in the adjacent area. At the next time t2, the area in which communication is performed at the frequency F3 moves in the traveling direction of the mobile station (to the right in FIG. 6) as the mobile station moves. If the moving distance of the area during this period is d, the moving speed v of the area is represented by d / (t2-t1).

  By switching the beam pattern of the antenna of the radio port along with the movement of the mobile station, the mobile station radio can continue to communicate on the same communication channel within the service area of the radio port, and the communication quality Will improve. In addition, even when a region that communicates at the same frequency moves as shown in FIG. 5, it is used at a specific time at the start point of an area that is served by a group of wireless ports that transmit the same information on the same multicast channel. An individual communication channel can be shifted smoothly by reporting the identification number of the communication channel on the payload of the multicast channel signal.

<Third Embodiment>
FIG. 7 is a diagram of a road-to-vehicle radio communication system according to the third embodiment of the present invention, and FIG. 8 is a configuration diagram of a mobile station radio used in the communication system of FIG.

  In the third embodiment, as described in connection with FIG. 6, in a system in which the area where radio communication is performed at the same frequency moves according to the movement of the mobile station, the speed of the mobile station (that is, the mobile station radio is installed). When the traveling vehicle speed) deviates from the moving speed of the area, a system capable of appropriately dealing with it and maintaining high-quality wireless communication is provided. The moving speed of the area where communication is performed at the same frequency is appropriately changed according to the speed of the traveling vehicle, as monitored by the control station. However, it is difficult to match the moving speed of the vehicle and the moving speed of the area in real time, and there may be a deviation between the vehicle speed and the moving speed of the area.

  As a feature of the third embodiment, as a payload of a multicast channel simultaneously transmitted from a wireless port, communication used at that time at the start point of a communication area serviced by a group of wireless ports transmitting the same information through the same multicast channel A channel identification number and a code for identifying a moving speed v in an area where communication can be continued on the same communication channel in this communication area are included.

  In the example of FIG. 7, the mobile station 707-1 enters the area served by the group to which the wireless ports 705 and 706 belong from the area served by the group to which the wireless ports 703 and 704 belong, across the area boundary 708. , 707-2. The mobile station radio 708-2 mounted on the mobile station 707 receives the multicast channel signal from the radio port 705 in the new area. The payload of this multicast channel signal includes a communication channel identification code representing the communication channel F3 used at that time at the start point of the area served by this group, and a moving speed v in an area where communication can be continued on the same communication channel. Is included.

  Such a multicast channel signal is steadily received by the mobile station radio 708 having two reception circuits.

  In FIG. 7, each of the radio ports 703, 704, 705, and 706 has a function of switching the beam pattern of the antenna along with the movement of the mobile station so that the mobile station radio can continue communication on the same communication channel. Have. Such a function is the same as that described in the second embodiment, and a description thereof is omitted here.

  FIG. 8 is a configuration diagram of the mobile station radio 708 used in the road-to-vehicle radio communication system of FIG. The mobile station radio 708 includes an antenna 801, a high frequency circuit 802, a multicast channel receiving circuit 803, and an individual transmission channel receiving circuit 811 and receives a signal from a radio port. A multicast channel signal is received, demodulated, and detected by the multicast channel receiving circuit 803, and the detected digital signal of the multicast channel is input to the control circuit 805.

  In the control circuit 805, the area speed code extraction circuit 707 extracts the area speed code from the detected multicast digital signal. On the other hand, the vehicle speed measuring circuit 806 detects the traveling speed of the vehicle on which the mobile station radio 708 is mounted.

The extracted area speed code and the detected vehicle speed are input to the thresholded speed comparison circuit 809 for comparison. That is, the comparison circuit 809 compares the moving speed of the area represented by the area speed code with the vehicle speed to obtain the difference, and further compares the obtained difference with a threshold value. If the speed difference exceeds the threshold value as a result of the comparison, a message to that effect is output to the call channel number add / subtract command circuit 810, and the call channel number add / subtract command circuit 810 is triggered. The call channel number increment / decrement command circuit 810 determines whether the speed difference exceeds the threshold value in the plus direction or exceeds the threshold value in the minus direction (that is, whether the mobile station speed is faster or slower than the territory speed). Accordingly, a change request command for changing the identification number of the communication channel is transmitted to the transmission signal generation circuit 808 using the uplink channel to the wireless port. The transmission circuit 804 controls the high frequency circuit 802 so that the transmission signal transmitted from the transmission signal generation circuit 808 can be transmitted, and transmits a change request to the wireless port through the antenna 801.

  In the example of FIG. 7, when the vehicle speed becomes faster than the area movement speed, a change request is transmitted to change the individual communication channel to F2, and when the vehicle speed becomes slower than the area movement speed, the individual communication is performed. Send a change command to change the channel to F4.

  Even if the traveling vehicle cannot keep up with the moving speed of the area where the traveling vehicle is communicating at the same frequency, the mobile station radio function makes it possible to smoothly switch the individual communication channel without performing a random channel search. it can.

  Similarly to the second embodiment, since the multicast channel signal includes the identification code of the communication channel used at the start point of the destination group area, the channel can be changed smoothly even at the boundary of the area. Is done.

  In the first to third embodiments, the example of using the OFDM scheme with guard time as the modulation method of the multicast channel has been described. However, the multi-wave modulation modulation scheme such as DSK, PSK-RZ, PSK-VP, etc. It is also possible to use. In this case, the upper limit of the guard time can be extended to (Ts × 1) seconds to (Ts × 2) seconds.

1 is a diagram showing a road-to-vehicle wireless communication system according to a first embodiment of the present invention. It is a figure which shows the flame | frame structure of the downlink multicast channel used with the radio | wireless communications system of FIG. It is a figure which shows the road-vehicle radio | wireless communications system which concerns on 2nd Embodiment of this invention. It is a block diagram of the mobile station radio | wireless machine used with the radio | wireless communications system of FIG. In the system of FIG. 3, it is a figure for demonstrating the case where the area | region where communication is continued with the same frequency moves according to the movement of a mobile station. It is a figure for demonstrating the moving speed of an area | region. It is a figure which shows the road-vehicle radio | wireless communications system which concerns on 3rd Embodiment of this invention. It is a block diagram of the mobile station radio | wireless machine used with the radio | wireless communications system of FIG. It is a figure which shows the conventional road-vehicle radio | wireless communications system.

Explanation of symbols

108, 301, 302, 510, 701, 702 Radio control stations 101-104, 303-306, 501-504, 703-706 Radio ports 105A-107A, 308, 708 Mobile station radio 201 Multicast channel 202 Payload 203 Guard time 403, 803 Multicast channel reception circuit 412, 811 Individual transmission channel reception circuit 407 Color code extraction circuit 410 Color code comparison circuit 411 Communication channel setting circuit 807 Area speed code extraction circuit 809 Speed comparison circuit 810 Communication channel number increase / decrease command generation circuit

Claims (5)

A control station,
A plurality of radio ports each having a corresponding radio zone;
A mobile station radio that performs radio communication with the radio port;
Each of the plurality of radio ports transmits a signal using a multicast channel dedicated to downlink from the radio port to the mobile station radio and an individual transmission / reception channel that performs transmission / reception at an individual frequency. At least two or more wireless ports simultaneously transmit the same signal on the same multicast channel,
The mobile station radio has two series of receiving circuits, and in one of the two series of receiving circuits, constantly receives the same information transmitted from the radio port through a multicast channel,
The same information transmitted on the multicast channel includes an identification code for identifying a group to which two or more wireless ports that transmit the same information simultaneously and an individual transmission / reception channel used at the start point of the area served by the group. Including an identification number,
The mobile station radio compares the received identification code of the same information with the previously received identification code, and if the result of comparison is different, a group of radio ports corresponding to the identification code included in the same information A road-to-vehicle wireless communication system, wherein the remaining one series of receiving circuits is automatically set in the individual transmission / reception channel corresponding to the identification number of the individual transmission / reception channel used at the start point of the service area. A control station,
A plurality of radio ports each having a corresponding radio zone;
The roadside vehicle-to-vehicle wireless communication system includes a mobile station radio that performs wireless communication with the wireless port, and an area that performs wireless communication at the same frequency moves according to movement of the mobile station,
Each of the plurality of radio ports transmits a signal using a multicast channel dedicated to downlink from the radio port to the mobile station radio and an individual transmission / reception channel that performs transmission / reception at an individual frequency. At least two or more wireless ports simultaneously transmit the same signal on the same multicast channel,
The mobile station radio has two series of receiving circuits, and in one of the two series of receiving circuits, constantly receives the same information transmitted from the radio port through a multicast channel,
The same information transmitted on the multicast channel includes an area speed code indicating the moving speed of the area that can communicate on the communication channel of the same frequency,
The mobile station radio detects the moving speed of the mobile station itself, obtains a speed difference between the detected moving speed and the moving speed of the area obtained from the area speed code, and according to the value of the speed difference, A road-to-vehicle wireless communication system, wherein a communication channel change request is transmitted to the wireless port.   Each wireless port uses an OFDM (Orthogonal Frequency Division Multiplexing) method as a modulation method at the time of transmission on the multicast channel, and when a predetermined interval between the wireless ports is L meters, (L / 300) microseconds The road-to-vehicle wireless communication system according to claim 1, wherein the road-to-vehicle wireless communication system has a transmission frame configuration having the above guard time.   The identification code of the group is arranged at any one of a head of a communication burst, immediately after a synchronization bit string at a head, and immediately before an error control bit string at a tail. Road-to-vehicle wireless communication system.   3. The road-to-vehicle wireless communication system according to claim 1, wherein each of the wireless ports includes a beam pattern switching unit that switches a beam pattern of an antenna of the wireless port according to movement of the mobile station wireless device. .

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