JPS596642A - Synchronizing method of mobile communication satellite - Google Patents

Abstract

PURPOSE:To send transmission data having the same phase without the influence of the range and topography between base stations by compensating of transmission data signals of a mobile comnunication system in phase on the basis of the frame synchronizing signal of a digital signal. CONSTITUTION:A transmission data frame synchronization detecting circuit 14 detects the frame synchronization of a delayed transmission data signal (d) and outputs a transmission data frame synchronizing signal (e). A read-out timing signal generating circuit 15 outputs a timing signal (b) synchronized with the signal (e). A signal (g) from a memory circuit 17 is sent to a transmitter. A satellite telemetry frame synchronizing signal (a) is outputted by demodulating signal (h) from a satellite telemetry signal receiver. A reset pulse generating circuit 19 outputs a reset pulse (j) at the timing making the signal (a) coincide with the signal (b) by a phase compensation requesting signal, the signal (a) is counted by the pulse (j) and a reference timing signal (k) for phase compensation is outputted. The timing of signal (b) is changed on the basis of a signal (k) and the transmission data signals (g) of the whole base stations are uniformed in phase.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a mobile communication system in which a central base station and a plurality of peripheral base stations transmit the same transmission data signal in the same phase to a mobile terminal. The present invention relates to a technique for correcting the phase of transmission data signals sent from a central base station and each peripheral base station based on a digital signal sent from a satellite that has a lock.

In a mobile communication system, transmission data signals are transmitted between one central base station and each peripheral base station via terrestrial communication lines, but the phase of the transmission data signals may shift due to changes in the route of the terrestrial communication lines, etc. One of the known methods for performing this phase correction is to perform phase correction based on a phase correction signal transmitted wirelessly from the central base station. A certain peripheral base station had the drawback of not being able to receive radio waves from the central base station, making it impossible to perform phase correction.

Another drawback is that when the service area expands, phase correction cannot be performed for distant peripheral base stations that cannot be reached by radio waves from the central base station.

Another known method is to slave-synchronize a mobile communication system to a clock extracted from a digital signal from a satellite, and each peripheral base station transmits data transmitted from the central base station based on the frame synchronization signal of the digital signal from the satellite. There is a method to correct the phase of the satellite, but this method requires a complex circuit that receives the digital signal from the satellite at the central base station, extracts the clock from the received signal, and converts the speed to the clock of the mobile communication system. However, since the clock of the mobile communication system is dependent on the clock of the digital signal from the satellite, the reliability of the mobile communication system is dominated by the reliability of the satellite.

In order to solve these drawbacks, the present invention corrects the phase of the transmitted data signal of the mobile communication system based on the frame synchronization signal of the digital signal without subordinating the clock of the mobile communication system to the digital signal from the satellite. This is what I decided to do.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows one embodiment of the present invention. In the figure, a central base station 1 and peripheral base stations 2 receive telemetry signals emitted from a satellite 5 using a receiving antenna 3 and a receiver 4, and send the demodulated digital signals to a central base station phase correction circuit 6. Alternatively, it is sent to the peripheral base station phase correction circuit 7. The sign converting device 8 generates a transmission data signal and sends it to the central base station phase correction circuit 6 and the peripheral base station phase correction circuit 7 via the terrestrial communication line 9, and at the same time transmits the terrestrial communication line 9 from each peripheral base station. It constantly monitors the phase of the transmitted data signal that is returned via the central base station, and when a phase shift is detected, it issues a phase correction request to the central base station phase correction circuit 6. Upon receiving the phase correction request, the central base station phase correction circuit 6 creates a reset pulse based on the frame synchronization signal of the satellite telemetry signal, and sends it to the peripheral base station phase correction circuit 7. The transmission data signal is subjected to phase correction in each phase correction circuit based on the reset pulse in the central base station and peripheral base stations, and is sent to the transmitter 1o and emitted from the transmission antenna.

FIG. 2 is a diagram for explaining the principle of phase correction of the present invention. In Figure 2, 11 is the received satellite telegram) I
Let the period of the J-time signal frame synchronization signal be Po.

12 is a timing signal of transmission data whose period is Pl
shall be. Considering the case where the frame synchronization signal 11 of the satellite telemetry signal and the timing signal 1z of the transmission data are synchronized, if both signals are made to match at a certain time To, the time corresponding to the period S of each of the two signals will be After a lapse of time Tl, both signals match again.

Time Tl is the pulse of the IJ double signal frame synchronization signal 11, which is reset at time To.
It is obtained by counting the number of times corresponding to the period pI of the timing signal 12 of the transmission data. Also, since the timing 12 of the transmission data can be moved by adjusting the timing of reading from the memory, the frame synchronization signal counter of the satellite telemetry signal of the peripheral base station should be reset with the reset signal from the central base station at time 'ro. For example, the peripheral base station can detect a shift in transmission data timing with respect to time T1 and correct the phase.

If the frame synchronization signal 11 of the satellite telemetry signal and the timing signal 12 of the transmission data are not synchronized, the two signals may be slightly different by 1 in time, but by forcibly adjusting the timing signal of the transmission data of all stations. Phase correction can be performed.

FIG. 3 shows a phase correction circuit of a central base station according to an embodiment of the present invention.

In FIG. 3, the transmission data signal C sent out from the encoding device 7 of FIG. 1 is delayed by a fixed delay circuit 13 for a predetermined time depending on the distance between the central base station and the peripheral base stations. The transmission data frame synchronization detection circuit 14 detects frame synchronization of the delayed transmission data signal d,
Outputs the transmit data frame synchronization signal. The read timing signal generation circuit 15 outputs a read timing signal synchronized with the transmission data frame synchronization signal. This signal corresponds to the transmission data timing signal 12 described above in FIG. 2. The write timing signal generation circuit 16 outputs a write timing signal f which is also synchronized with the transmission data frame synchronization signal 6 and has the same period as the read timing signal.

The memory circuit 17 is for variable delay, and the transmission data signal d is written in by the write timing signal f and read out by the read timing signal S. The signal t output from the memory circuit 17 is transmitted to the transmitter 1 in FIG.
sent to 0.

On the other hand, the signal demodulated by the IJ signal receiver 4 in FIG. 1 is sent to a satellite telemetry frame synchronization detection circuit 18, which outputs a satellite telemetry frame synchronization signal a. This signal α corresponds to the IJ double signal frame synchronization signal 11 (satellite telemetry) in the explanation of FIG. 2 mentioned above. Reset pulse generation [119
is a zero satellite telemetry frame synchronization signal counter 2 which outputs a reset pulse I at the timing when the satellite telemetry frame synchronization signal α and the readout timing signal coincide with each other according to the phase correction request signal sent from the encoding device 7.
After being reset by the zero reset pulse J, the satellite telemetry frame synchronization signal α is counted and a reference timing signal system for phase correction is output. The timing at which this signal A is issued is the time T in the explanation of FIG.
Corresponds to 1. By changing the timing of the read timing signal with reference to signal A, the transmission data signals t of all X other stations are adjusted to have the same phase.

FIG. 4 shows a phase correction circuit of a peripheral base station according to an embodiment of the present invention. This circuit is exactly the same as the central base station phase correction circuit shown in FIG. 3 except for the reset pulse generation circuit 15, and receives the reset pulse J from the central base station and operates as the central base station phase correction circuit. Phase correction is performed in the same operation.

Satellite telemetry in one embodiment of the present invention) The period Po of the IJ double signal frame synchronization signal is 32 milliseconds, and the period Pl of the read timing signal is 155 milliseconds. The data transmission time between the central base station and peripheral base stations is P. (32 milliJ seconds), so no malfunction will occur due to a delay in the reset signal.

Furthermore, in this embodiment, when a phase correction request is received from the encoding device 7, a reset pulse is issued at a timing that coincides with the one-satellite telemetry frame synchronization signal a and the readout timing signal, but the satellite telemetry frame synchronization signal a
If a method is adopted in which the phase relationship between the IJ frame synchronization signal 4 and the readout timing signal is detected and the relative phase relationship between the IJ frame synchronization signal 4 and the readout timing signal is detected, and the relative phase relationship between the IJ frame synchronization signal 4 and the readout timing signal 4 is detected and the relative phase relationship between the IJ frame synchronization signal 4 and the satellite telemetry signal It is possible to issue a reset signal at the timing of the pulse.

As explained above, according to the method of the present invention, in a mobile communication system, the phase of transmitted data is based on the digital signal of the satellite, which is asynchronous with the clock of the mobile communication system. Since the correction is performed, the same phase is not affected by the distance or topography between the central base station and surrounding base stations, and the reliability of the mobile communication system is not completely dominated by the reliability of the satellite. transmission data can be sent, and the effect is great.

On the other hand, the present invention has the advantage that it can be easily realized with a relatively simple circuit of about 30 digital controllers.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the present invention, FIG. 2 is a diagram for explaining the principle of phase correction of the present invention, and FIG. 3 is a phase correction circuit of a central base station according to one embodiment of the present invention. FIG. 4 is a diagram showing a phase correction circuit of a peripheral base station according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Central base station, 2... Peripheral base station, 3... Receiving antenna, 4... Receiver, 5... Satellite, 6...
Central base station phase correction circuit, 7... Peripheral base station phase correction circuit, 8... Encoding device, 9... Ground communication line, 10
... Transmission 4L l 1... Frame synchronization signal of satellite telemetry signal, 12... Timing signal of transmission data, 13... Fixed delay circuit, 14... Transmission data frame synchronization detection circuit, 15...・Read timing generation circuit, 16...Write timing generation circuit, 17...
- Memory circuit, 18... Satellite telemetry frame synchronization detection circuit, 19... Reset pulse generation circuit, 20.
...Frame synchronization signal counter, Po ...satellite telemetry) IJ double signal frame synchronization signal period, Pl...
- Cycle of the timing signal of the transmission data, To... Time when the frame synchronization signal of the satellite telemetry signal and the timing signal of the transmission data coincide, T1... Time T. Time after time S has elapsed since S...Satellite telemetry) Time corresponding to the product of the period Po of the IJ double signal frame synchronization signal and the period of the timing signal of the transmission data, 4...Satellite telemetry frame synchronization signal, k ... Read timing signal, c, dSg... Transmission data signal, L... Transmission data frame synchronization signal, f... Write timing signal, I... Satellite telemetry signal, Lu...
...Standard Timing Signal Agent Patent Attorney Takashi Honma Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In a mobile communication system consisting of a central base station, multiple peripheral base stations, and multiple mobile terminals, the central base station and peripheral base stations each receive a digital signal from a satellite, and the fixed period included in the received signal is A specific position on the waveform of an arbitrary pulse in the pulse train is set as the base point, and from the time of the base point, it corresponds to the product or least common multiple of the period of the pulse train and the period of the transmission data being transmitted by the mobile communication system. A mobile communications satellite synchronization method, characterized in that the phase of the transmitted data is corrected so that the relative phase relationship between the received signal and the transmitted data at the specific position is the same as the relative phase relationship between the received signal and the transmitted data at a time after a lapse of time.