JP2000049683A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the danger of a communication fault caused by a hit in the radio communication system provided with plural base stations for transmitting respectively different base station identification signals and mobile stations connected through leakage coaxial (LCX) cables and radio channels to the base stations. SOLUTION: A mobile station 50 is provided with a front antenna 13, a rear antenna 13' arranged backward to have a prescribed distance from this front antenna, a first receiver 14 for demodulating a signal received by the front antenna, a second receiver 14' for demodulating a signal received by the rear antenna, and a switching control part 17 for switching and controlling the outputs of the first and second receivers. When the same base station identification signal is received by the first and second receivers, this switching control part performs control so as to execute diversity reception, when the first receiver is disabled for reception, only the output of the second receiver is selectively controlled and when different base station identification signals are received by the first and second receivers, only the output of the first receiver is selectively controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system for performing radio communication between a mobile station and a ground station, and to a radio zone switching system in a radio communication system including a plurality of base stations and a mobile station. It is.

[0002]

2. Description of the Related Art Conventionally, in this type of radio communication system, when a mobile station communicates over a plurality of base station zones, different base station identification signals are transmitted from each base station and received by the mobile station. A method of connecting a mobile station to a base station by using a series of sequences such as returning a base station identification signal as a base station designation signal has been generally used. According to this method, when the next zone is vacant, connection can be continued and only the zone where the mobile station is required is occupied, so that there is an advantage that communication efficiency is good.

FIG. 2 shows an example of a conventional wireless communication system. In FIG. 2, reference numerals 1 and 2 denote leaky coaxial cables (hereinafter referred to as LCX cables) for radiating and receiving radio waves, each of which forms a different wireless zone. 3 is L
The base station A in the LCX1 zone connected to CX1,
A radio base station includes the duplexer 5, the receiver 6, the transmitter 10, and the base station identification signal generator 11. Similarly, 4 is L
The base station B in the LCX2 zone connected to CX2, which comprises a duplexer 5 ', a receiver 6', a transmitter 10 ', and a base station identification signal generator 11'. Each base station transmits a different base station identification signal, and the mobile station returns the received base station identification signal as a base station designation signal. Each base station is connected to the control device 30 and transmits a base station designation signal returned from the mobile station to the control device 3.
Supply 0. The control device 30 controls the base station designation signals based on the base station designation signals detected by the base station designation signal detectors 7 and 7 '.
The switch 8 is switched to select the base station system to receive, and the switch 12 similarly selects the transmission base station system.
The line connection device 9 is connected to the control device 30 and a terminal such as a telephone. On the other hand, reference numeral 13 denotes an antenna 13 connected to the mobile station 40. The radio wave received by the antenna 13 is demodulated by the receiver 14 via the duplexer, and
9. The other output from the receiver 14 is supplied to the base station identification signal detector 16, and the result is output to the line connection device 19. The transmission output from the line connection device 19 is combined with a base station designation signal according to the base station identification signal, and transmitted by the antenna 13 via the transmitter 20 and the duplexer.

Next, the operation of the conventional example shown in FIG. 2 will be described. In the figure, a base station identification signal generator 1 in a base station A3
1 is transmitted from the transmitter 10 and is always transmitted from the LCX 1 via the duplexer 5. Similarly, the signal generated from the base station identification signal generator 11 'in the base station B4 is transmitted from the transmitter 10', and is transmitted to the duplexer 5 '.
Is always transmitted from the LCX2 via. However, this identification signal is different between the LCX1 zone and the LCX2 zone. When the mobile station 40 is passing through the LCX1 zone, the radio wave from the LCX1 is received by the antenna 13 of the mobile station 40, and the base station identification signal is detected by the base station identification signal detector 16 via the duplexer and the receiver 14. Is detected. At this time, when the mobile station 40 transmits, the communication line is connected to the base station A3 in the LCX1 zone by adding a signal specifying the LCX1 zone as the base station specifying signal and transmitting the signal. When the mobile station 40 deviates from the LCX1 zone and enters the adjacent LCX2 zone, the antenna 13 of the mobile station 40 receives radio waves from the LCX2 zone, and the base station identification signal detector detects the base station in the LCX2 zone. The identification signal of B4 is detected. The base station designation signal when transmitting is designated by LCX2 zone,
The communication line is connected to the base station B4 in two zones.

[0005] On the other hand, when the mobile station 40 is located in the middle of different zones, no signal can be received during a period in which the radio waves from the LCX1 zone and the radio waves from the LCX2 zone are mixed, and the mobile station is disconnected. I will. Also, the next LCX2
The connection is also disconnected during the period until the zone identification signal is detected. This is due to the nature of the radio waves that the radio waves can reach as close as possible even if they are located off the LCX cable. If it takes longer to get to the next zone, there will be less interference,
An extremely weak radio wave continues for a long time, and as a result, the radio wave cannot be sufficiently received. in this way,
In the related art, in a place where radio waves coexist, such as at a boundary between zones, an instantaneous interruption of the time during which interference occurs and the time required for redetection occurs reliably. This problem does not differ from the case where the signal is received by a single antenna simply because the operation of the receiving system is single even if the conventional spatial diversity technique is used. For example, when antennas are arranged on the left and right, the reception state of radio waves is exactly the same as that of a single antenna. In addition, when the antennas are arranged before and after, since radio waves to be received are different for each zone, there is a state where sufficient radio waves cannot be received as a result.

[0006]

As described above, in the zone switching system according to the prior art, it is difficult to receive a signal due to radio wave interference between the reception of the previous base station designation signal and the reception of the next base station designation signal. It takes time to complete the movement of the area and to finish detecting the base station designation signal.
For this reason, during a call, the call is temporarily inaudible, and during data transmission, data is interrupted.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a mobile station comprising: a front antenna; a rear antenna disposed at a predetermined distance d behind the front antenna; A first receiver for demodulating a signal received by an antenna, a second receiver for demodulating a signal received by a rear antenna, and switching control between an output of the first receiver and an output of the second receiver. And a switching control unit that controls diversity reception when the same base station identification signal is received by the first and second receivers. When reception becomes impossible, only the output of the second receiver is selectively controlled, and the first and second outputs are selected.
When different receivers receive different base station identification signals,
Only the receiver output is controlled selectively.

Further, the distance d between the front antenna and the rear antenna of the mobile station is detected in order to detect a section length L of the mobile station in the radio communication system that cannot be received and a base station identification signal received by the mobile station. Distance x which converted distance t of time into
Is set to be longer than the distance L + x.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. In FIG. 1, reference numeral 1 denotes LCX1 forming an LCX1 zone, and reference numeral 2 denotes LX forming an LCX2 zone.
CX2 and CX3 are base stations A in an LCX1 zone connected to LCX1, and CX4 is a base station B in an LCX2 zone connected to LCX2. In the figure, the radio waves received by the base stations in each zone are demodulated by the receivers 6, 6 'via the duplexers 5, 5'. When transmitting from each base station, the base station identification signals from the base station identification signal generators 11 and 11 'are combined with the transmission signal and modulated by the transmitters 10 and 10'. 'And transmitted from each LCX cable.

A signal demodulated by the base station in each zone is given to the control device 30, and the designated signals are detected by the base station designated signal detectors 7, 7 '. The base station side designated by the designation signal is selected by the switch 8 and output to the line connection device 9 to configure a communication line. On the other hand, based on the signal output from the line connection device 9, the switch 12
, The base station specified by the identification signal is selected and connected to the transmission line of the specified base station.

On the other hand, in the mobile station 50, 13 is a front antenna installed in front of the mobile station, 13 'is rearward from the front antenna 13, at least a section length L that is difficult to receive,
A distance x obtained by converting the time t for detecting the base station identification signal into a distance (for example, at the maximum speed or average speed of the mobile station).
And a rear antenna that is installed at a distance d longer than the distance L + x. Radio waves received by the antennas 13 and 13 'are passed through the duplexer to the receivers 14 and 14'.
Is demodulated. The demodulated output is input to the diversity receiver 15, and one of the receiver outputs having a good reception state (for example, the output having the stronger received electric field strength) is selected. After performing the diversity selection, one demodulated output is output to the switch 18 as a diversity output. Further, the other outputs of the receivers 14 and 14 'are bisected, one of which is input to the switch 18, and the other is supplied to the base station identification signal detectors 16 and 16'. Base station identification signals are detected by these detectors 16 and 16 ′ and input to the switching controller 17. The switching controller 17 controls the switches 18 and 21 according to the flowchart shown in FIG. 3, and the switched received signal is input to the line connection device 19. The line connection device 19 synthesizes the base station designation signal, modulates the signal with the transmitter 20, and outputs the modulated signal to the antenna 13 or 13 'via the switch 21. The identification signals generated from the base station identification signal generators 11 and 11 'in each base station are transmitted from the transmitters 10 and 10' and are always transmitted from the LCX cable via the duplexer. However,
This identification signal is different between the LCX1 zone and the LCX2 zone. The identification signal is a tone signal if it is an analog signal, a unique keyword code signal or the like if it is a digital signal, and a signal that does not significantly affect the original transmission and reception is used.

In this embodiment, it is possible to realize a wireless communication system in which instantaneous interruption is significantly reduced at the time of zone switching by using the switching controller performing the control operation shown in FIG. Next, the operation will be described. Mobile station 50 is L
When passing through the CX1 zone, both antennas 13 and 13 'of the mobile station 50 receive the base station identification signal from the LCX1 and the detection result is given to the switching controller 17. The switching controller 17 detects the identification signal of the LCX1 zone from both reception procedures, and controls the switching unit 18 to pass the diversity result of the receiver to the control device. The transmitting antenna is a rear antenna, and the base station designation signal selects the base station of the base station identification signal received by the rear antenna.

Next, the mobile station 50 sets the LCX1 zone and the LCX1 zone.
When moving to the boundary of the X2 zone, first, the antenna 13 in front of the mobile station is in a state where reception is difficult. At this time, since the switching controller 17 cannot receive the signal by the front antenna 13, the switching device 1 is set so that only the rear antenna 13 ′ is effective.
8 is controlled. The transmitting antenna is a rear antenna, and the base station designation signal selects the base station of the base station identification signal received by the rear antenna. As the mobile station 50 progresses, the front antenna 13 enters the LCX2 zone,
The base station identification signal of the X2 zone is received. At this time, since the rear antenna 13 'is installed with a sufficient distance 1 from the front antenna 13, the base station identification signal of the LCX1 zone is still received. The switching controller 17
Since the base station identification signal received by the front antenna 13 and the base station identification signal received by the rear antenna 13 ′ are different, it recognizes that it is a boundary of a zone and passes the reception output of the front antenna 13 to the control device. Control. Further, the transmitting antenna is also set to be the front antenna, and the base station specifying signal is the base station specifying signal received by the front antenna. At this stage, the base station switches the zone.

[0014] Further, as the mobile station advances, it becomes difficult to receive with the rear antenna 13 '. In this case, the upper state is maintained, and transmission and reception are performed only with the front antenna 13. When the mobile station 50 moves through the LCX2 zone completely through the zone boundary, the same base station designation signal is received by both the front antenna and the rear antenna.
In the same manner as when moving within one zone, switching control is performed so that diversity reception and rear antenna transmission are performed. As described above, even if the front antenna cannot be received, it can be received by the rear antenna, and when the front antenna can receive radio waves in the next zone, transmission and reception of only the front antenna By switching and establishing transmission / reception with the next base station, the instantaneous interruption time can be substantially only the switching time. Thereafter, when the reception from the rear antenna is established, the mode can be returned to the normal mode by performing the diversity reception.

[0015]

According to the present invention, switching can be performed almost instantaneously at the boundary of the base station zone, and a radio communication system in which the danger of communication failure is significantly reduced can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional technique.

FIG. 3 is a flowchart illustrating an example of a wireless zone switching method according to the present invention.

[Explanation of symbols]

1: LCX cable 3: LCX1 zone base station 4: LCX2 zone base station 5,
5 ': duplexer, 6, 6': base station receiver,
7, 7 ': base station designation signal detector, 8: reception system switch, 9: line connection device, 10, 10':
Base station transmitter, 11, 11 ': base station identification signal transmitter, 13, 13': mobile station antenna, 14, 1
4 ': mobile station receiver, 15: diversity receiver,
16, 16 ': base station identification signal detector, 17: switching controller, 18: mobile station reception system switch, 19: line connection device, 20: mobile station transmitter, 21: mobile station transmission system switch, 30 : Control device, 40, 50: mobile station.

Claims (3)

[Claims] 1. A wireless communication system comprising: a plurality of base stations each transmitting a different base station identification signal; and a mobile station connected to the base station via a wireless line. A rear antenna disposed rearward from the front antenna at a predetermined distance d,
A first receiver for demodulating a signal received by the front antenna, a second receiver for demodulating a signal received by the rear antenna, and an output of the first receiver and an output of the second receiver. A switching control unit for performing switching control, wherein the switching control unit controls to perform diversity reception when the same base station identification signal is received by the first and second receivers, and performs first reception. When the receiver becomes unreceivable, only the second receiver output is selectively controlled, and when the first and second receivers receive different base station identification signals, only the first receiver output is selectively controlled. A wireless communication system characterized in that: 2. The wireless communication system according to claim 1, wherein a distance d between a front antenna and a rear antenna of the mobile station.
Is the distance L + x obtained by adding the section length L of the mobile station in the wireless communication system that cannot be received and the distance x obtained by converting the time for detecting the base station identification signal by the mobile station.
A wireless communication system characterized by being set to be longer as described above. 3. The wireless communication system according to claim 1, wherein the plurality of base stations are connected to different LCX cables, respectively, and communicate with the mobile station via the LCX cables. Wireless communication system.