RU2127488C1 - Phase-lead synchronization method and device for mobile radio communication systems - Google Patents

Abstract

FIELD: electric communications. SUBSTANCE: delay time in signal propagation from base station is measured at mobile station and sync signals of the latter are set with phase lead relative to reference sync signals of base station for mentioned delay time. EFFECT: improved carrying capacity of time-shared channels. 2 cl, 3 dwg

Description

 The present invention relates to techniques for electrical communications and can be used in systems of mobile radio communications (SPR).

 A known synchronization method in the DSS, based on the transmission of the reference signal, which is used for synchronization, transmission of identification codes, etc. This method is described, for example, in applications for inventions: EPO N 0037519 "Mobile radio network with synchronization operating on the entire network" dated 10/14/81, bull. N 41, and PCT N 91/00658 "Method of synchronization in a cellular network of mobile radio communications" from 10.01.91, bull. N 2.

 However, this method leads to a complication of the equipment and an increase in its overall dimensions.

 The closest in technical essence to the proposed one is the method used in the European Digital Cellular Broadcasting Network GSM, described in the journal "Information Transmission. / Express Information, edited by Prof. MD Venediktov, Moscow, VINITI, 1994, N 28, p. 9-39.

This method consists in the fact that in the frame structure with time division of channels (VRK) using clock pulses (TI)
- transmit from the base station (BS) to the mobile station (PS) the synchronization package (SP) in time;
- TI and SP generators are tuned in time to the PS in synchronism with the reference TI and SP received from the BS.

To implement this method, the GSM system uses the device described in the aforementioned magazine "Express Information" on page 15. An enlarged block diagram of this device is presented in figure 1, where the following notation:
1 - mobile station (PS);
2 - communication channel (CS);
3 - base station (BS);
4 - switching and control center (CCU).

 The device operates as follows. BS3 transmits on KS2 to PS1 using TI a digital signal in the form of frames (packets) containing SP and information. At PS1, the signal is received, the time adjustment of the TI and SP generators is synchronized with the reference TI and SP received from the BS, and information is received. Information from PS1 is transmitted to BS3 in the same way, with the only difference being that the SP is not transmitted towards BS3. All device operation is performed in duplex mode. TsKU4 serves a group of cells and provides all types of connections, control and switching that PS1 needs (call control and routing, radio channel switching, PS1 “relay transmission” when moving it from one cell to another, access to the city telephone exchange). CCU4 is connected to the BS3 interface.

 However, the communication channels with WRC built using this synchronization method have a low throughput due to the presence of a relatively large protective time interval between them.

 To eliminate this drawback, a method is proposed based on reducing the guard interval by introducing pre-emptive synchronization signals PS with respect to the reference synchronization signals BS at the time of propagation of the signal from PS to BS.

The proposed synchronization method is as follows:
- transmit from BS to PS using TI a digital signal containing a reference SP in time (request);
- TI and SP generators are tuned in time to the PS in synchronism with the reference TI and SP received from the BS;
- transmit from the PS to the BS signal containing the SP (response);
- fix at the PS the moment of signal transmission to the BS (response);
- relay BS to PS signal SP (response to response);
- fix at the PS the moment of arrival of the relay signal of the SP from the BS (response to response);
- calculate on the PS the delay time of the propagation of the signal from the BS;
- install TI and SP generators on the PS with a lead in relation to the reference TI and SP BS for the time delay of signal propagation to the BS.

 This synchronization process is repeated with a period determined by the maximum speed of the MS.

To implement the proposed method, a device is used, the block diagram of which is presented in figure 2, where it is indicated:
1 - block determining the delay time of the signal (BOVZ);
2 - mobile station (PS);
3 - shaper proactive signal (FUS);
4 - communication channel (CS);
5 - base station (BS);
6 - switching and control center (CCU).

 The device contains series-connected PS2, KS4, BS5, TsKU6, the second outputs of which are outputs to the PBX, the second outputs of PS2 through series-connected BOVZ1 and FUS3 are connected to the second inputs of PS2 and, in addition, to the second inputs of FUS3.

 The proposed device operates as follows. In synchronization mode, BS5 transmits via KS4 to PS2 using TI a digital signal in the form of frames (packets) containing a reference SP and information (request). At PS2, this signal is received, the time adjustment of the TI and SP generators is synchronized with the reference TI and SP received from BS5. As a result of this, TI and SP PS2 turn out to be phased with reference TI and SP BS5. Then they transmit from PS2 through KS4 to BS5 a signal containing a SP (response), and at the same time start from PS2 BOVZ1 of the signal. BS5 relays on KS4 to PS2 the signal SP (response to response). PS2 receives a relay signal SP (response to response) from BS5 and simultaneously stops BOVZ1. Thus, in BOVZ1 there is a certain delay time for the signal to pass through KS4 from PS2 to BS5 and vice versa (double signal delay time from PS2 to BS5). Then the signal from BOVZ1 arrives at FUS3, which generates, using control signals from PS2, a pre-emptive signal proportional to the delay time of the signal through KS4 from PS2 to BS5 (single delay time). In fact, FUS3 divides the double signal delay time defined in BOVZ1 in half. The pre-emptive signal generated in this way arrives from FUS3 to PS2 and installs the TI and SP generators there with a phase advance (lead) in relation to the reference TI and SP BS5 for the propagation delay time of the signal to BS5. This ends the synchronization mode.

 Further, the device switches to the information exchange mode, in which information from BS5 is transmitted via KS4 to PS2 and, similarly, in the opposite direction.

 All device operation is performed in duplex mode. CCU6 serves a group of cells and provides all types of connections, control and switching that PS2 needs (call management and routing, radio channel switching, PS2 “relay transmission” when moving it from one cell to another, access to the city telephone exchange). CCU6 is connected to the BS5 interface.

 Then the device switches back to synchronization mode and the process described previously is repeated. The repetition period of the synchronization mode is determined by the maximum speed of the MS.

 The operation of the proposed device is illustrated by the timing diagrams presented in figure 3.

 The proposed device is implemented on the basis of blocks known from the technical literature. For example, as BOVZ1, you can use a binary counter on the 533IE7 chip, and as FUS3 you can use the shift register on the 533IE16 chip. In this case, the use of the shift register as FUS3 is due to the fact that the halving of the delay time, determined by BOVZ1, is reduced in the binary number system, in fact, to a shift by one digit to the right (towards the lower digits).

 The technical efficiency of the proposed method and device synchronization is to increase the throughput of such communication systems with WRC in comparison with the known. This is due to the fact that in communication systems with WRC using this method of synchronization by reducing the time detuning between the synchronization signals of the MS and BS (by introducing the lead of the PS clock signals to the propagation delay time of the signal to the BS), the protective time interval between the channels can be reduced.

Claims (2)

 1. The synchronization method with pre-emption for a mobile radio communication system, which consists in transmitting from a base station (BS) to a mobile station (PS) using pulses of a digital signal containing a reference clock synchronization clock, clock generators and synchronization clocks are tuned in time to the MS synchronously with received clock pulses and a reference clock package, characterized in that they transmit a signal containing a clock package from the PS to the BS, fix the moment of transmission of this signal to the PS, and relay this signal to the BS, receive send the relay signal to the PS and record the moment of its reception, calculate the transit time of the signal containing the clock from PS to the BS, set the clock and clock generators with a lead in relation to the clock pulses and the reference clock for the time the signal containing the clock goes from PS to BS.  2. A device for implementing the method, comprising a mobile station (PS) connected to a base station (BS) by a communication channel, characterized in that a series-connected block for determining the delay time of the passage of a signal containing a clock transmission from PS to BS and a pre-emitter signal is introduced, designed to generate a pre-emptive signal for installing clock and clock generators located on the PS, and the output of the PS is connected to the input of the unit for determining the delay time of the signal passage and to a second input of the anticipatory signal for transmitting control signals, whose output is connected to an input of MS.

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