KR20000065723A - Apparatus for clock generating of base station modem in mobile communication system - Google Patents

Abstract

PURPOSE: A device for generating clocks of a base station modem in a mobile communication system is provided to supply changed clocks according to a communication area, so as to communicate with a terminal in an extended base station radius. The device is provided to selectively use modem clocks in one base station modem, so as to process all signals in a general base station radius and the extended base station radius to improve base station modem functions. CONSTITUTION: A global positioning system(GSP) clock receiver(100) receives a pulse per 2 second(/PP2S) and a system clock(19.6608Mhz) from a global positioning system(GSP). A system clock divider(200) divides the system clock into many clocks, and transmits the divided system clocks to base station modems in a base station modem unit(700). A pulse per 2 second(/PP2S) divider(300) divides the /PP2S into many /PP2Ss, and transmits the divided /PP2Ss to the base station modems. The base station modems are synchronized with the system clock and the /PP2Ss, and modulate transmitting data and demodulate receiving data.

Description

Apparatus for clock generating of base station modem in mobile communication system}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to base station modem clock generation in a code division multiple access (CDMA) mobile communication system. In particular, the present invention relates to a base station modem clock in a mobile communication system in which a cell communication area is extended by supplying a base station modem ASIC by changing a system reference clock. It relates to a generator.

In general, in a CDMA mobile communication system, all mobile stations (terminals) and base stations are time-synchronized based on the CDMA system reference time. Here, the base station synchronizes time with the CDMA system reference time received from the GPS receiver, and the mobile station obtains the long code timing of the CDMA system and the time information of the system timing from the synchronization channel message sent by the base station. Synchronize the timing and system timing with the long code timing and system timing of the mobile station. This synchronization allows the mobile station to recover the signal transmitted from the base station and the base station to recover the signal transmitted from the mobile station.

Herein, the mobile station obtains time information through a message transmitted from the base station and sets a reference time to synchronize with the base station.

The forward link (base station to mobile station) has a pilot channel, a synchronization channel, a calling channel and a forward call channel, and the reverse link (mobile station to base station) has an access channel and a reverse call channel. The mobile station first acquires a pilot channel and acquires a synchronization channel (synchronization channel message) in synchronization with the obtained pilot channel. The mobile station obtains time information from the system time data (SYS_TIMEs) included in the sync channel message, where the system time data (SYS_TIMEs) obtains the pilot PN offset at 320 ms past the end of the last 80 ms super frame of the sync channel message received by the mobile station. It means the system time when subtracted.

At this time, the reference time set by the mobile station is delayed due to the signal propagation delay from the base station to the mobile station and the signal processing delay at the mobile station compared to the base station reference time. The mobile station having set the reference time as described above transmits a signal in accordance with the set reference time. The mobile station sets the reference time and transmits the signal in synchronization with the set reference time because the CDMA system generates and extracts the signal based on the time. This reverse link signal is delayed by the propagation delay and received by the base station. That is, the base station transmits in accordance with the system reference time, but the reverse link signal is received with a time delay (hereinafter referred to as "bidirectional propagation delay") compared to the system reference time.

1 is a block diagram illustrating a base station modem clock supply device in a general CDMA mobile communication system.

As shown, the GPS clock receiving unit 10 for receiving / PP2S (pulse per 2 second) and the system clock (19.6608Mhz) which is a reference signal supplied from the GPS; A system clock distributor 20 for distributing a plurality of system clocks (SYS_CLK) of 19.6608Mhz received by the GPS clock receiver 10 to the base station modem unit 40; A PP2S distribution unit 30 for distributing a plurality of / PP2Ss obtained from the GPS clock receiving unit 10 to the base station modem unit 40; A plurality of base station modems 40-1 to 40-n for modulating and demodulating the transmission signal and the reception signal in synchronization with the system clock and / PP2S obtained in the system clock distribution unit 20 and the PP2S distribution unit 30, respectively. The base station modem unit 40 is configured.

In the general CDMA mobile communication system configured as described above, the base station modem clock supply device receives and supplies a reference signal / PP2S and a system clock (19.6608Mhz) supplied from the GPS from the GPS clock receiver 10.

Then, the system clock distributor 20 distributes a plurality of system clocks of 19.6608Mhz obtained from the GPS clock receiver 10 into a plurality of base station modems in the base station modem unit 40, and also supplies the PP2S distribution unit 30. ) Also distributes a plurality of / PP2S supplied from the GPS clock receiving unit 10 to each base station modem in the base station modem unit 40.

Accordingly, each of the base station modems 40-1 to 40-n in the base station modem unit 40 modulates a transmission signal to be transmitted to the terminal in synchronization with the supplied system clock and / PP2S, and receives the received signal transmitted from the terminal. Will be demodulated.

In this way, the base station modem used in the base station operates by receiving the / PP2S, which is a reference signal supplied by GPS, and a system clock (19.6608Mhz).

Meanwhile, the terminal transmits a signal in synchronization with a synchronization channel supplied from the base station.

In this case, the signal transmitted from the terminal is input by delaying the / PP2S reference time, which is a GPS reference signal, but the base station modem can demodulate a delay less than about 410PN chip (333.66Hz). If we convert 333.66㎲ into distance, it is about 50km.

In other words, a call with a terminal located within a distance of about 50 km from the base station is possible, but a call with a terminal located more than 50 km from the base station is impossible.

In the general CDMA system as described above, the maximum allowance of the bidirectional propagation delay is limited in hardware of the base station modem ASIC. That is, the maximum possible cell call radius in timing is limited to 50 km, which causes a problem in that many base stations need to be installed in a large area with low traffic density.

In addition, when the base station is difficult to install, such as at sea, it causes a limit of the service radius.

Accordingly, the present invention has been proposed to solve various problems occurring in the general CDMA mobile communication system as described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide a base station modem clock generator in a mobile communication system in which a cell communication area is expanded by changing and supplying a system reference clock to a base station modem ASIC.

The present invention for achieving the above object,

A base station modem clock supply apparatus for a CDMA mobile communication system, comprising: a system clock distribution unit for distributing a plurality of system clocks obtained at a GPS clock receiver; and a PP2S distribution unit for distributing a plurality of / PP2S obtained at the GPS clock receiver.

A central processing unit for setting a delay time to extend a call radius;

A control signal generator for generating a clock delay control signal to generate a delay clock corresponding to the delay time set by the central processing unit;

A call radius expansion clock generation unit for delaying and outputting / PP2S obtained by the GPS clock receiver by a predetermined time according to the clock delay control signal obtained by the control signal generator;

The transmission signal is modulated and the received signal is demodulated by selectively using a delayed / PP2S obtained from the call radius expansion clock generation unit and a distributed / PP2S obtained from the PP2S distribution unit, synchronized with the system clock obtained from the system clock distribution unit. Characterized in that consisting of a base station modem unit consisting of a plurality of base station modem.

1 is a block diagram showing a base station modem clock supply apparatus in a general mobile communication system;

2 is a block diagram showing a base station modem clock generator in a mobile communication system according to the present invention;

3 is a detailed block diagram of the call radius expansion clock generator of FIG.

<Explanation of symbols for main parts of drawing>

400: central processing unit

500: control signal generator

600: call radius expansion clock generator

610: latch 620: counter

630: comparator 640: D flip-flop

650: Inverter 660: Oagate

670: Multiplexer

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention according to the technical spirit as described above in detail.

2 is a block diagram of a base station modem clock generator in a mobile communication system according to the present invention.

As shown, a GPS clock receiver 100 for receiving / PP2S and a system clock (SYS_CLK) from the GPS, and a system clock distributor 200 for distributing a plurality of system clocks obtained from the GPS clock receiver 100; A PP2S distributor 300 for distributing a plurality of / PP2Ss obtained from the GPS clock receiver 100, a central processing unit 400 for setting a delay time to extend a call radius, and the central processing unit 400 The GPS clock according to the control signal generator 500 for generating a clock delay control signal so as to generate a delay clock corresponding to the delay time set by?) And the clock delay control signal obtained from the control signal generator 500. The call radius expansion clock generator 600 outputs the delayed / PP2S obtained by the receiver 100 by a predetermined time, and the call radius synchronized with the system clock obtained by the system clock distribution unit 200. A base station modem unit comprising a plurality of base station modems for modulating a transmission signal and demodulating a reception signal by selectively using the delayed / PP2S obtained from the long clock generator 600 and the distributed / PP2S obtained from the PP2S distribution unit 300. It consists of 700.

In the above description, the call radius extension clock generator 600 includes a latch 610 for latching a delay time for a clock delay obtained by the control signal generator 500 and a / PP2S obtained by the GPS clock receiver 100. A counter 620 for counting a system clock SYS_CLK, a comparator 630 for comparing an output signal of the counter 620 with an output signal of the latch 610, and outputting a result signal; A D flip-flop 640 that is cleared by PP2S and latches input data in synchronization with a signal output from the comparator 630, and an inverter 650 which phase-inverts the output signal of the D flip-flop 640; An output of the oragate 660 according to an OR gate 660 for logically combining the output signal of the inverter 650 and the output signal of the comparator 630 and the control signal output from the control signal generator 500. Signal and outputted from the GPS clock receiver 100 Consists of a multiplexer 670 that selects one of / PP2S and outputs it to the delay clock (/ dly_pp2s).

In the mobile communication system according to the present invention configured as described above, the base station modem clock generator receives the / PP2S and the system clock (19.6608Mhz) transmitted from the GPS by the GPS clock receiver 100. The system clock distributor 200 distributes a plurality of system clocks SYS_CLK obtained from the GPS clock receiver 100 to some base station modems (1-N / 2) of each base station modem in the base station modem unit 700. The PP2S distribution unit 300 distributes a plurality of / PP2S obtained from the GPS clock receiving unit 100 to a plurality of base station modems (1-N / 2) in the base station modem unit 700. Will be supplied). Accordingly, some base station modems (corresponding to 1-N / 2) in the base station modem unit 700 modulate the transmission data in synchronization with the supplied system clock and / PP2S, and demodulate the received data.

This operation is the same as the operation of the existing base station modem, and if the call radius is to be extended, the control signal generator 500 controls the delay time for generating the delay clock for the call radius extension in the central processing unit 400. Set to.

Accordingly, the control signal generator 500 generates a control signal corresponding to the set delay time and transmits the control signal to the call radius extension clock generator 600.

As shown in FIG. 3, the call radius extension clock generator 600 latches the delay time obtained from the control signal generator 500 in the latch 610, and the counter 620 receives the GPS clock receiver 100. Count the system clock (SYS_CLK) obtained from the (). That is, the counter 620 is cleared when / PP2S occurs in the GPS clock receiver 100 and counts the input system clock SYS_CLK. When the / PP2S occurs during counting, the counted value so far is transmitted to the comparator 630 at a later stage and cleared again to recount the system clock.

The comparator 630 compares the signal output from the counter 620 with the signal output from the latch 610 to determine whether they are the same. If the two values are the same, the comparator 630 generates a "low" pulse. do. Multiple such pulses occur within the / PP2S pulse, in which case only the first pulse is valid.

To this end, the D flip-flop 640 of the rear stage uses the / PP2S signal as a clear signal to generate a low signal when the / PP2S signal is generated. In this case, the output of the comparator 630 is input to the D flip-flop 640 as a clock, and the D flip-flop 640 is synchronized with the clock to output the input data to the output. That is, the output is " high ". Next, even if the next output of the comparator 630 occurs, the D flip-flop 640 maintains the previous output. When / PP2S occurs again, the output is shifted to "low" again, and when the output of the comparator 630 is changed, the operation of sending a high signal to the output is repeated.

The signal output from the D flip-flop 640 is inverted in phase by the inverter 650, and the OR gate 660 logically combines the output of the inverter 650 with the output of the comparator 630. The result is transmitted to the multiplexer 670, the multiplexer 670 is a delay clock for the radial expansion and the GPS output from the oragate 660 according to the control signal output from the control signal generator 500 One of / PP2S obtained by the clock receiving unit 100 is selected and output.

That is, the multiplexer 670 is delayed by selecting / PP2S output from the GPS clock receiver 100 when the control signal is not generated from the control signal generator 500, that is, when the base station radius is not extended. The clock (/ dly_pp2s) is supplied to the remaining base station modems except for some of the base station modems (corresponding to 1-N / 2) in the base station modem unit 700. In this case, it operates in the same manner as a general base station modem clock generator.

However, when a control signal is generated from the control signal generator 500, that is, when the base station radius is extended, the multiplexer 670 selects a clock output from the oragate 660 to delay clock dly_ / pp2s. ) Is supplied to the remaining base station modem except for some base station modems (corresponding to 1-N / 2) in the base station modem unit 700.

Accordingly, when the base station modem unit 700 operates in a general base station radius mode, all base station modems process transmission and reception data in synchronization with the existing system clock SYS_CLK and / PP2S. However, when operating in the base station radius extension mode, the remaining base station modems except for some of the base station modems (corresponding to 1-N / 2) use the delayed clock (dly_ / pp2s) obtained by the multiplexer 670 to transmit data. Modulate and demodulate received data. By changing the clock supplied to the base station modem in this way, the base station radius can be extended.

As described above, according to the present invention, the base station modem clock is changed and provided according to the call area, so that a call can be made with the terminal even in an extended base station radius, which is a case out of the basic call area.

In addition, since the call radius can be extended without the addition of a separate base station, there is an advantage that the base station installation cost can be reduced.

In addition, since a single base station modem selectively uses a modem clock to process all signals of a general base station radius and an extended base station radius, it is possible to improve the function of the base station modem.

Claims (3)

A base station modem clock supply apparatus for a CDMA mobile communication system, comprising: a system clock distribution unit for distributing a plurality of system clocks obtained at a GPS clock receiver; and a PP2S distribution unit for distributing a plurality of / PP2S obtained at the GPS clock receiver. A central processing unit for setting a delay time to extend a call radius; A control signal generator for generating a clock delay control signal to generate a delay clock corresponding to the delay time set by the central processing unit; A call radius expansion clock generation unit for delaying and outputting / PP2S obtained by the GPS clock receiver by a predetermined time according to the clock delay control signal obtained by the control signal generator; The transmission signal is modulated and the received signal is demodulated by selectively using a delayed / PP2S obtained from the call radius expansion clock generation unit and a distributed / PP2S obtained from the PP2S distribution unit, synchronized with the system clock obtained from the system clock distribution unit. A base station modem clock generator in a mobile communication system, characterized in that it comprises a base station modem comprising a plurality of base station modem. The system of claim 1, wherein the call radius extension clock generation unit comprises: a latch for latching a delay time for a clock delay obtained by the control signal generator; and a system clock (SYS_CLK) according to / PP2S obtained by the GPS clock receiver. A counter to compare the output signal of the counter with the output signal of the latch and output the resultant signal, and a D flip to latch input data in synchronization with the signal cleared by the / PP2S and output from the comparator. A flop, an inverter for inverting the output signal of the D flip-flop, an orifice for ORing the output signal of the inverter and the output signal of the comparator, and the oragate according to a control signal output from the control signal generator Selects one of the output signal and the / PP2S output from the GPS clock receiver and outputs the delayed clock (/ dly_pp2s) A base station modem clock generator in a mobile communication system, characterized in that configured in the multiplexer. According to claim 1, wherein the base station modem unit, within the basic base station call radius, all base station modems process transmission and reception data in synchronization with the system clock and PP2S provided from the GPS, and in the extended radius of the base station call radius is extended Some base station modems process transmission and reception data in synchronization with the system clock and PP2S provided from the GPS, and the other base station modems except the base station modems are synchronized with a delay clock (dly_pp2s) obtained from the call radius extension clock generator. A base station modem clock generator in a mobile communication system, characterized by processing transmission and reception data.