JP2601201B2 - Mobile communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly to a mobile communication system for transmitting data such as TV signal transmission from a transmitting station to a mobile station.

[0002]

2. Description of the Related Art A conventional mobile communication system will be described below with reference to FIG. In the configuration shown in the figure, on the transmission side, a video signal 101, which is an output signal of the TV camera 1, is modulated by a modulator 4 and then converted to a radio frequency by a transmission high-frequency unit 5 and provided to a transmission antenna 6. The radio signal 106 output from the transmitting antenna 6 is received by the receiving antenna 7 and
After undergoing the amplification, the signal is demodulated by the demodulator 9 through a frequency conversion process to become a video signal 109.

[0003] In the case of mobile communication such as reception by a receiver mounted on a vehicle or the like, if there is an obstacle such as a tree or a building, a shadow wing phenomenon in which a radio wave is greatly attenuated occurs (hereinafter, shadow wing). Described), instantaneous line disconnection occurs. In this case, the receiving side has a problem that a demodulated image is disturbed because a correct video signal cannot be obtained. As a method of solving the disorder of the received image due to the shadow wing, there is a method of repairing information loss using retransmission means performed in normal data transmission. However, in real-time signal transmission such as live TV broadcasting, real-time transmission is performed. Had the disadvantage of losing. For this reason, in the related art, during the line disconnection, the storage unit 1 uses an out-of-sync signal output from the synchronization determination signal 113.
4 is controlled to switch to the immediately preceding video signal 115 stored in the storage unit 14 in advance, thereby preventing image disturbance. When there is no shadow wing, the switch 12 outputs a normal synchronization signal as the determination signal 113 and switches the switch 12 so that the output signal of the demodulator 9 becomes the output signal 114 as it is.

The above prior art is disclosed in, for example,
No. 5081.

[0005]

In the conventional method, it is possible to prevent the reconstructed image from being disturbed. However, it is not possible to prevent the loss of information when the line is momentarily interrupted due to a shadow wing or the like. Had become. Transmission side objective is missing information does not occur even in the event the line - stop of the present invention
The purpose is to provide an expression .

[0006]

According to a mobile communication system of the present invention, in a mobile communication system in which a signal is transmitted from a transmitting station to a mobile station via an (original signal) wireless line, the transmitting station includes: First delay means for delaying an original signal by a predetermined delay time, and the signal delayed by the first delay means within a predetermined time and the original signal not overlapping at the same time as the predetermined time Time by processing each at high speed
Combining means for compressing and combining the signals; and means for transmitting an output signal of the combining means. A receiving means for receiving the signal transmitted from the transmitting station to the mobile station; Demodulating means for demodulating a combined signal of the combining means from the received signal, separating means for separating an output of the demodulating means into a signal delayed by the first delay means and the original signal, and the separating means A second delay means for delaying the original signal separated by the same time as the first delay means, and when the received signal is normal, a signal delayed by the first delay means is selected, and Switching means for switching the original signal to select a signal delayed by the second delay means when the signal is abnormal.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment of the present invention at the time of live TV broadcasting. The video signal 101 (original signal) output from the TV camera 1 is converted into a digital signal by the A / D converter 20 and then delayed for a predetermined time by the delay unit 2 to obtain a delayed signal 102. In the synthesizer 3, the output signal 116 of the A / D converter 20 is output.
And the delay signal 102 are synthesized. After the signal 103 synthesized by the synthesizer 3 is modulated by the modulator, the signal 103 is converted into a radio frequency by the transmission high frequency unit and supplied to the transmission antenna 6. The radio signal 106 output from the transmitting antenna 6 is received by the receiving antenna 7 of the receiving station, is amplified by the receiving high-frequency unit 9, is frequency-converted, demodulated by the demodulator 9, and separated by the separator 10.
The signal is divided into a signal 111 input to the delay unit 11 and a signal 110 input directly to the switch 12. Separated demodulated signal 1
11 is delayed by the same time as the transmission side by a delay unit 11 and input to the switch 12 together with the output signal of the separator 110.
The switch 12 outputs a synchronization determination signal 11 output from the demodulator 9.
3 when the demodulated signal is synchronized, the output signal 1
10 is selected, and the delay unit 112
Output signal 112 is selected. The output signal of the switch outputs the received video signal 114, and the analog video signal (original signal) is restored by the D / A converter 21.

FIG. 2 shows a temporal change of a signal waveform of each part of the present invention.

In FIG. 1, reference numeral 116 denotes an A / D converter 20.
, And the time slots 2, 3, and 4 are provided for each time slot at an equal interval T (sec).

Reference numeral 102 denotes an output signal 1 of the A / D converter 20.
16 is delayed by 2T (sec) by the delay unit 2. 1
03 denotes an output signal of the synthesizer 3 and the signal 102 is 2
A signal processed at twice the speed and a signal processed at twice the speed of the signal of the A / D converter 20 are synthesized.
As a result, the signal 103 includes, for example, the time slot 0 and the time slot 2 in the time slot 3 of the signal 116.
Are synthesized at T / 2 (sec).
In the case of time slot 2 of signal 116 and time slot 0 (D) of signal 103, for example,
(D), 2).

Reference numeral 109 denotes an output signal of the demodulator on the receiving side. In this figure, the delay time in the wireless transmission path is omitted for simplification.

Here, it is assumed that a reception electric field failure occurs in a time slot (-1 (D), 1) corresponding to the time slot 2 of the signal 116 due to a shadowing or the like in the reception electric field.

The separator 10 receives the signal 109 and outputs the time slot (−1 (D), 1) in which the failure has occurred to the signal 11.
0 and the signal 111 are separated.

Here, the signal 110 is on the front side (delayed signal) of the combined time slot of the signal 109,
The signal 111 is after the time slot of the signal 109 (a signal that is not delayed).

The undelayed signal 111 is input to the delay unit 11 and delayed by the same time as the time delayed by the delay unit 2 (in this example, two time slots) to become a signal 112.

A signal 113 is a synchronization determination signal of the demodulator 9 and is a time slot (−1) of the signal 109 in which a failure has occurred.
(D), 1), and outputs an asynchronous detection signal after one time slot.

A signal 114 is an output signal of the switch 12. When the output of the signal 113 is at a low level, the signal 110 is selected.
When the signal 110 is at the high level, the signal 110 is selected, and when the output of the signal 113 to be asynchronous is at the high level, the signal 112 is selected. As a result, as the signal 114, a signal which is not affected at all is continuously obtained.

In the present embodiment, for example,
Since a digital delay circuit using a normally used D flip-flop can be used, the configuration is easy.

In the above embodiment, the case where the video signal is converted into a digital signal and subjected to digital processing has been described. However, when the original signal is a digital data signal, it is not necessary to convert the digital signal into a digital signal.

FIG. 3 shows a second embodiment of the present invention, in which a data generator 31 and a data receiver 32 are provided and the A / D
The configuration is the same as that of FIG. 1 except that the converter 20 and the D / D converter 21 are not provided. That is, in this example, the delay processing is performed on the digital signal as it is.

The details of the signal waveforms of the respective parts of this embodiment are omitted because they are the same as the time slots in FIG.

[0022]

As described above, according to this method, even if an instantaneous interruption fault occurs in the transmission line due to shadowing or the like, signal transmission can be performed without loss of information. In this embodiment, the TV relay is described as an example, but it is clear that the present invention is effective for all systems that transmit data in real time.

[Brief description of the drawings]

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

FIG. 2 is a timing chart of the first embodiment of the present invention.

FIG. 3 is a block diagram of a second embodiment of the present invention.

FIG. 4 is a block diagram of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 TV camera 2 delay unit 3 combiner 4 modulator 5 transmission high frequency unit 6 transmission antenna 7 transmission antenna 8 reception high frequency unit 9 demodulator 10 separator 11 delay unit 12 switching unit 13 TV receiver 14 storage unit 20 A / D conversion Device 21 D / A converter 31 data generator 32 data receiver

Claims (4)

(57) [Claims] In a mobile communication system in which a signal is transmitted from a transmitting station to a mobile station via an (original signal) wireless line, a first signal for delaying the original signal by a predetermined delay time is provided to the transmitting station. Delay means, and processing the signal delayed by the first delay means within a predetermined time and the original signal at high speed so as not to overlap at the same time as the predetermined time .
A synthesizing means for synthesizing temporally compressed Ri, and means for transmitting an output signal of said combining means, to the mobile station, receiving means for receiving a signal transmitted from the transmitting station, the receiving Demodulating means for demodulating the combined signal of the combining means from the received signal obtained by the means, separating means for separating the output of the demodulating means into the signal delayed by the first delay means and the original signal, A second delay unit that delays the original signal separated by the separation unit by the same time as the first delay unit, and when the received signal is normal, selects the signal delayed by the first delay unit. Switching means for switching the original signal to select a signal delayed by the second delay means when the received signal is abnormal. 2. The control device according to claim 1, wherein the switching unit controls the demodulation unit by outputting a determination signal for determining that the received signal is synchronized when the received signal is synchronized and outputting an abnormal signal when the received signal is asynchronous. The mobile communication system according to claim 1, wherein 3. The mobile communication system according to claim 1, wherein said synthesizing means temporally compresses the first delayed signal and the original signal by processing at a high speed. 4. The mobile station according to claim 1, wherein the transmitting station includes analog-to-digital conversion means when the original signal is an analog signal, and the mobile station includes digital-to-analog conversion means. Body communication system.