WO2003081810A1

WO2003081810A1 - Indoor cdma mobile communication system for simultaneously supplying a traffic signal, control signal and gps signal using a lan cable and control method thereof

Info

Publication number: WO2003081810A1
Application number: PCT/KR2003/000529
Authority: WO
Inventors: Joong-Han Choi
Original assignee: Airpoint Co., Ltd
Priority date: 2002-03-26
Filing date: 2003-03-18
Publication date: 2003-10-02
Also published as: AU2003212696A1; JP2005520447A

Abstract

An indoor CDMA mobile communication system and control method thereof that simultaneously supplies a traffic signal, control signal and GPS signal using a LAN cable installed indoors or outdoors. The system includes a GPS antenna for receiving a GPs signal outputted from a satellite, a coaxial cable for transmitting the received GPS signal, a GPS signal matching section composed of a GPS receiver for receiving and demodulating the GPS signal and an encoder for modulating and encoding the traffic signal, control signal and GPS signal so as to transmit the signals to match characteristics of the LAN cable in consideration of electric and mechanical characteristics of the LAN cable, and at least one base transceiver subsystem including a GPS signal decoder for converting the modulated and encoded signals transmitted through the LAN cable, connecting to the GPS signal matching section through the LAN cable, and operating in synchronization with the decoded GPS signal. The system uses general LAN (e.g., Ethernet) cables without the necessity of a separate installation work, and thus the installation costs and the complexity of wires can be reduced.

Description

INDOOR CDMA MOBILE COMMUNICATION SYSTEM FOR

SIMULTANEOUSLY SUPPLYING A TRAFFIC SIGNAL, CONTROL SIGNAL

AND GPS SIGNAL USING A LAN CABLE AND CONTROL METHOD THEREOF

Technical Field

The present invention relates generally to an indoor code division multiple access (CDMA) mobile communication system and a control method thereof, and more particularly to an indoor CDMA mobile communication system and a control method thereof that simultaneously supply a traffic signal, control signal and global positioning system (GPS) signal using a local area network (LAN) cable installed indoors or outdoors in order to effect synchronization of a base transceiver subsystem (BTS) internal system and a BTS external network in an indoor or outdoor CDMA cellular mobile communication system.

Background Art

CDMA synchronization-related timing signals provided from a GPS to a CDMA mobile communication network are signals of a time of date (TOD), one pulse per second (1PPS) and lOMHz, respectively, and the CDMA cellular mobile communication network performs a system synchronization using these signals. According to the related art, as shown in FIG. 1, one GPS is installed and operated for each base transceiver subsystem (BTS). Also, as shown in FIG. 2, a method for using one GPS signal in various BTSs has been proposed to save costs. Referring to FIGs. 1 and 2, the construction and function of the related art systems will be explained.

FIG. 1 illustrates the construction of one related art CDMA mobile communication subsystem for GPS operation. In this system, one GPS is installed and operated in each BTS. As shown in FIG. 1, the related art CDMA mobile communication subsystem includes a GPS antenna 100, installed outdoors, for receiving signals from a GPS satellite, a coaxial cable 110 for transmitting the signals received through the GPS antenna 100, a GPS receiver 120 for demodulating the GPS signal received through the coaxial cable 110, a GPS signal transmission cable 130 for transmitting the demodulated signal, and a base transceiver subsystem (BTS) 140 that operates in synchronization with timing information received through the GPS signal transmission cable 130.

A high-frequency signal of 1.2GHz/1.5GHz is received from a GPS satellite through the GPS antenna 100, and the received signal is inputted to the GPS receiver

120 through the coaxial cable 110. The GPS receiver 120 demodulates this signal to produce timing signals of TOD, 1PPS and 10MHz. The demodulated timing signals are transferred to the BTS 140 through the GPS signal transmission cable 130, and the BTS 140 performs the network system synchronization using the timing signals. Meanwhile, in order to provide a service for shaded areas, a repeater 160 is connected to the BTS 140 and an optical cable 150 is used for connecting between the BTS 140 and the repeater 160. According to the method of FIG. 1, one GPS receiver 120 is required for each BTS, and it is general to locate the GPS receiver near the BTS 140 in order to minimize attenuation, noise effect, etc., according to a distance between the GPS receiver 120 and the BTS 140. Meanwhile, the GPS receiver 120 may be installed in the BTS 140.

However, since it is general to install the GPS antenna 100 outdoors and the expensive coaxial cable 110 for fully transmitting the high-frequency signal received through the GPS antenna 100 to the GPS receiver 120 should be installed, it requires a great cost and the optical cable 150 should be used for connection between the BTS 140 and the repeater 160.

FIG. 2 illustrates the construction of another related art CDMA mobile communication subsystem in which a remote GPS system having a GPS receiver and a BTS interface implemented into one unit is separately located. Referring to FIG. 2, the related art CDMA mobile communication subsystem includes a GPS antenna 200 for receiving GPS satellite signals, a coaxial cable 210 for transmitting the received signals to a GPS receiver 221, a remote GPS system 220 composed of the GPS receiver 221 for restoring timing of the signals received through the coaxial cable 210 and a BTS interface 222 for dividing restored timing signals among BTSs, GPS signal transmission cables 230 for transmitting the timing information, traffic signal transmission cables 240 for transmitting traffic information, clock dividing section 251 for dividing GPS information received through the GPS signal transmission cables 230, and BTSs 250 that operate in synchronization with signals outputted from the clock dividing sections 251.

A high-frequency signal received from a GPS satellite through the GPS antenna 200 is inputted to the GPS receiver 221 through the coaxial cable 210, and the

GPS receiver 221 restores the timing information. The restored timing information is converted into signal forms required for the BTS 250 through the BTS interface 222, and the converted signals are then inputted to the clock dividing sections 251 through the GPS signal transmission cables 230. The clock dividing sections 251 divide clock signals by converting the signals inputted thereto into signal forms required for respective constituent elements of the BTSs 250. At this time, the remote GPS system 220 may be separately located as shown in FIG. 2 or included in one of the BTSs 250. In this case, traffic signals outputted from the BTSs 250 are transmitted through the traffic signal transmission cables 240.

However, according to the method of FIG. 2, the GPS signal can be supplied to many BTSs 250 using one GPS receiver 221, but separate GPS signal transmission cables 230 should be installed and it costs a great deal to install optical cables 260 among the BTSs 250 and repeaters 270 to cost a great deal. Especially, the electric transfer characteristics of the high-frequency signal of 10MHz, which is required in the BTSs 250, deteriorate according to a transmission medium used for signal transmission and the distance between the BTS interface 222 and the BTS 250, and thus a special process for a long-distance transmission is required.

Disclosure of the Invention

Therefore, an object of the present invention is to solve the problems involved in the prior art and to provide an indoor CDMA mobile communication system that simultaneously supplies a traffic signal that is user data, control signal and GPS signal received through one GPS receiver using a general LAN cable (for example, a twisted pair cable), which has been installed or is to be installed indoors or outdoors, without any separate installation work. The present invention also proposes a method of restoring a clock signal using a LAN cable while maintaining a modulation technique for heightening a reliability of transmission up to a long distance and a high degree of precision. In addition, the present invention proposes a method of enabling many subsystems to use one received GPS signal.

Meanwhile, it is another object of the present invention to provide a simple and economic indoor CDMA mobile communication system that enables remote subsystem reset control and power supply to remote radio units (e.g., repeaters) through a GPS signal matching section by defining a reset signal and power supply of an existing LAN cable. It is still another object of the present invention to provide an indoor CDMA mobile communication system that provides flexibility in service expansion for shaded areas and simplicity in operation, repair and maintenance by using a general LAN cable for connection to repeaters instead of an optical cable.

In more detail, the indoor CDMA mobile communication system according to the present invention can be achieved by using the following methods. As described above, timing-related signals provided to the indoor CDMA cellular mobile communication system through a GPS receiver are three kinds of signals of TOD, 1PPS and 10MHz, and these signals are used for synchronization between base transceiver subsystems (BTSs) or internal synchronous signals of a BTS during a handoff operation. Meanwhile, a twisted pair cable is composed of 8 (e.g., 4 pairs of) copper lines, 4 lines (e.g., 2 pairs) of which are used for transmission of a traffic signal and the remaining 4 lines (e.g., 2 pairs) of which are for backup. At least 3 pairs of lines are required for transmission of the GPS signals required in the BTS with the TOD, 10MHz and IPPS clock signals. In order to solve this, three methods may be used: First is to modulate and transmit the IPPS and 10MHz signals through a pair of lines, to define and transmit a reset signal through a remaining pair of lines, and to process and transmit the TOD signal as IP packets through traffic signal transmission cables since the TOD signal does not require severe transfer characteristics in comparison to the IPPS or

10MHz clock signal. Second is to allocate a pair of lines to the IPPS and 10MHz modulated signals, and to transmit the TOD information through the remaining pair of lines. Third is to allocate and transmit the IPPS and 10MHz signals through two pairs of lines, respectively. Meanwhile, as the frequency of a signal increases, the attenuation of the signals also increases, and in order to improve the transfer characteristics, it is required that a transmitting end divides a lOMHz signal by N and transmits 10/N MHz signals, and then a receiving end receives and restores the divided signals to the original 10MHz signal. In case of transmitting the lOMHz signal through a LAN cable, the electric transfer characteristics deteriorate due to the attenuation and delay as the distance between the transmitting and the receiving ends becomes greater. In order to solve this, a frequency is divided to match the transfer characteristics of the LAN cable or its encoding is performed to match the transfer characteristics of the transmission medium. Also, an encoder for perform a function of mixing two signals and transmitting a mixed signal through one line and a decoder for performing a function of restoring the GPS signal encoded through the LAN cable to the original signal are provided.

Brief Description of the Drawings

The above objects, other features and advantages of the present invention will become more apparent by describing the preferred embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1 is a block diagram of one related art CDMA mobile communication subsystem having a separately installed GPS receiver.

FIG. 2 is a block diagram of another related art CDMA mobile communication subsystem in which a GPS receiver and a BTS interface are implemented into one unit. FIG. 3 is a block diagram of an indoor CDMA mobile communication subsystem having a separately installed GPS-signal matching section according to the present invention.

FIG. 4 is a block diagram of an indoor CDMA mobile communication subsystem in which a GPS-signal matching section is located in a control station system according to the present invention.

FIG. 5 is a block diagram of a base transceiver subsystem.

FIG. 6 is a block diagram of a control block of a hub.

FIG. 7 is a view illustrating the allocation of traffic signals for an existing LAN cable.

FIGs. 8 to 10 are views illustrating allocation of traffic signals and control signals of a LAN cable according to the present invention.

FIG. 11 is a timing diagram explaining an encoding technique for supplying an IPPS signal and a 10/N MHz signal using one line according to the present invention. FIG. 12 is a block diagram of an existing DPLL.

FIG. 13 is a block diagram of an accumulated average DPLL designed to have a high degree of precision according to the present invention.

Best Mode for Carrying Out the Invention Now, the indoor CDMA mobile communication system and the control method thereof according to preferred embodiments of the present invention will be described in detail with reference to the annexed drawings.

FIG. 3 is a block diagram of an indoor CDMA mobile communication subsystem having a separately installed GPS-signal matching section according to the present invention, and FIG. 4 is a block diagram of an indoor CDMA mobile communication subsystem in which a GPS-signal matching section is located in a control station system according to the present invention. As shown in FIGs. 3 and 4, the indoor CDMA mobile communication subsystem using a general LAN cable according to the present invention includes a GPS antenna 300 or 400 for receiving a high-frequency signal from a satellite, a coaxial cable 310 or 410 for transmitting the

GPS signal received through the GPS antenna 300 or 400, a . GPS receiver 321 or 4211 for receiving and demodulating the GPS signal received from the coaxial cable 310 or 410, an encoder 322 or 4212 for modulating and encoding waveforms for transmitting signals to match the characteristics of a LAN cable in consideration of the electric and mechanical characteristics of the LAN cable, general LAN cables 330 or 430 such as twisted lines for transmitting the received GPS signal to base transceiver subsystems (BTSs), GPS signal decoders 351 or 451 for converting the signals received through the LAN cables 330 or 430 into the original GPS signals, and the BTSs 350 or 450 that operate in synchronization with the decoded GPS signals.

In this case, in order to transfer the information received through the GPS antenna 300 or 400 to the BTSs 350 or 450, it is preferable that at least one hub 340,

370, 440 or 470 is installed between the BTSs 350 or 450 and the GPS signal matching section 320 or 421 and between the BTSs 350 or 450 and the repeaters or remote radio units 390 or 490.

The encoder 322 or 4212 performs the modulation for transmitting three kinds of signals through the two pairs of lines as described above, and may employ a dedicated hub for efficiently transmitting the control signal if needed. The circuit construction in the encoder 322 or 4212 for impedance matching or hub 340 or 440 may be changed according to the number of BTSs connected thereto. The decoder 351 or 451 demodulates the modulated signals of IPPS and 10MHz and restores the clock by performing an accumulated average DPLL function.

Referring to FIGs. 3 and 4, an example of the GPS signal transmission will be explained. A GPS signal received from a satellite through the GPS antenna 300 or 400 is inputted to the GPS receiver 321 or 4211 through the coaxial cable 310 or 410. The GPS receiver 321 or 4211 produces clock signals of IPPS, TOD and 10MHz that are timing signals, and the clock signals are inputted to the encoder 322 or 4212. The encoder modulates the signals to match the LAN cable characteristics, and transfers the synchronous signal to N BTSs 350 or 450 through transmission media (e.g., LAN cables) connected to the hub 340. The BTSs 350 or 450 operate to match the synchronous clock. At this time, the BTSs 350 or 450 may use repeaters or remote radio units 390 or 490 in order to provide a service for shaded areas. In this case, the traffic information and the control information outputted from the BTSs 350 or 450 are inputted to the hubs 370 or 470 though the LAN cables 360 or 460, the signals which have passed through the hubs 370 or 470 are transmitted to the repeaters or the remote radio units 390 or 490 through the LAN cables 380 or 480, and then propagate on the air through the antenna. Backward signals from a mobile communication terminal (not illustrated) to the BTS 350 or 450 are transferred through a reverse process to the above-described process. The hub line-collects and drives the LAN cables, and uses only a protocol of a lower layer such as a physical layer and a link layer without using an upper protocol in order to minimize a transfer delay of the hub. Meanwhile, the GPS-signal matching section 320 or 421 may be separately installed as shown in FIG. 3, or may be included in a control station 420 as shown in FIG. 4 or in one of the BTSs. Also, in order to provide a service for shaded areas or areas where the strength of a radio wave is weak, it is possible to use the LAN cables through the hubs 340, 360, 440, 470 or 520 for transmission to the repeaters or remote radio units 370, 480 or 530. Here, the control station 420 serves to control a predetermined number of BTSs, for example, 4-5 BTSs.

FIG. 5 is a block diagram of a base transceiver subsystem. As shown in FIG. 5, at least one hub 520 is connected to the base transceiver subsystem (BTS) 500 through a LAN cable, and at least one repeater or remote radio unit 530 is connected to the respective hub 520. FIG. 6 is a block diagram of a hub according to an embodiment of the present invention. In FIG. 6, a first Ethernet matching section 610 drives connection lines of a LAN cable 680 connected to a BTS, or modulates/demodulates the clock signal. A packet processing section 620 multiplexes information inputted from the BTS into frames to send the frames to second Ethernet matching sections 630 and 660, or demultiplexes the frames into the information to send the information to the first

Ethernet matching section 610. Also, the packet processing section 620 separates information from the BTS into frames in order to send the frames from the BTS to the second Ethernet matching sections 630 and 660, or sends the information from the second Ethernet matching sections 630 and 660 to the BTS. Meanwhile, a clock restoring section 670 is provided to precisely restore the clock of 25MHz coming from the BTS and send the restored clock to the packet processing section 620.

The operation of the present invention as constructed above will now be explained in detail with reference to FIGs. 3 to 6 and drawings to be explained later.

As described above, the signal received through the GPS antenna 300 or 400 is inputted to the GPS receiver 321 or 4211 through the coaxial cable 310 or 410, and the

GPS receiver 321 or 4211 demodulates the timing signals of TOD, IPPS and 10MHz. The three demodulated timing signals are transmitted to the BTSs through the LAN cables 330 or 430. At this time, the existing LAN cables 330 or 430 are composed of 4 pairs of lines. Among them, two pairs have already been used for the traffic, and the remaining two pairs are used for transmission of the three GPS signals of TOD, IPPS and lOMHz. The encoder 322 or 4212 encodes the three kinds of signals using two pairs of lines, modifies the signals to match the transmission medium, and transmits the modified signals to the existing LAN cables 330 or 430. As shown in FIG. 7, diverse methods as illustrated in FIGs. 8 to 10 are used to transmit the three kinds of signals of TOD, IPPS and 10MHz through two backup pairs of lines. FIG. 8 shows an example of allocation of traffic and control signals of the LAN cable according to the present invention. The IPPS and lOMHz signals are encoded and simultaneously transmitted through a pair of lines, and a reset signal is allocated to a remaining pair of lines. The TOD signal is transmitted as data through the traffic lines since the TOD signal does not require a high degree of precision. The reset signal is used to remotely reset the BTS in the event that the BTS that receives the GPS clock through the LAN cable operates abnormally.

FIG. 9 shows another example of allocation of traffic and control signals of the LAN cable according to the present invention. The IPPS and lOMHz signals are allocated to one line, and the TOD signal is allocated to another remaining line. The two remaining lines are used for the traffic.

FIG. 10 shows still another example of allocation of traffic and control signals of the LAN cable according to the present invention. The IPPS and 10MHz signals are allocated to respective lines. The 10/N MHz signal is restored to the lOMHz signal using a digital phase locked loop (DPLL) circuit.

FIG. 11 is a timing diagram explaining an encoding technique for simultaneously supplying the lOMHz clock signal and the IPPS signal using a pair of lines. The lOMHz is converted into a 10/N MHz signal, which is obtained by dividing the lOMHz signal by N, in order to minimize attenuation characteristics due to the cable. In order to integrate the IPPS signal and the 10/N MHz signal outputted from the

GPS receiver into one signal, a pulse logic that indicates a start of the pulse is shifted from logic 0 to logic 1. In the present invention, in order to discriminate the two signals, the IPPS signal is compulsorily shifted from logic 0 to logic 1 on the center of the 10/N MHz clock as shown in FIG. 11, and the 10/N MHz signal and the IPPS signal are AND-gated to produce the clock. A transfer clock is in the form of 00 and 11 under the

10/N MHz clock, but 01 is produced at a point where the IPPS signal is generated. The receiving end judges the IPPS signal by the waveform of the signal received through a pair of lines, e.g., if the received signal is in the form of 01, while it judges the 10/N MHz signal if the received signals is in the form of 00 and 11, and this enables the discrimination between the IPPS signal and the 10/N MHz signal. Accordingly, both the IPPS signal and the 10/N MHz signal can simultaneously be transmitted through a pair of lines, and the receiving end can demodulate the IPPS signal and the 10/N MHz signal, respectively.

FIG. 12 is a block diagram of an existing DPLL. The existing DPLL includes a phase comparator PC, a digital loop filter (DLP), and a voltage-controlled oscillator VCO. The phase comparator PC serves to generate a voltage corresponding to a phase difference between an input signal and an output of the voltage-controlled oscillator VCO, and the NCO varies its oscillated frequency according to the voltage corresponding to the phase difference. The digital loop filter DLP removes high- frequency components generated in the phase comparator PC, and determines the synchronous characteristics of PLL. The phase comparator PC compares the phase of the input signal with that of the voltage-controlled oscillator NCO and generates the voltage corresponding to the phase difference. This voltage is inputted to the voltage- controlled oscillator NCO through the digital loop filter DLP. The voltage-controlled oscillator NCO outputs a frequency signal corresponding to the inputted voltage so that the difference between the input signal of the phase comparator PC and the output of the voltage-controlled oscillator VCO decreases. However, since the output signal of the DPLL circuit as shown in FIG. 12 is dependent upon only one sample value just previously inputted, it is not suitable for a DPLL circuit that requires a high degree of precision. FIG. 13 is a block diagram of an accumulated average DPLL circuit designed to have a high degree of precision according to the present invention. This circuit is provided with an accumulated average unit, installed in front of the existing DPLL circuit, for obtaining an accumulated average value of the input signal, and restores the clock using the accumulated average value for a predetermined period, so that a high degree of precision can be secured. The operation of the accumulated average circuit of

FIG. 13 is as follows: The input signals (e.g., at maximum, M sample values) are continuously accumulated and the accumulated average value is inputted to the phase comparator PC. The phase comparator PC compares the accumulated average value with the output of the voltage-controlled oscillator VCO, and thus the variation of the output voltage thereof is finely adjusted. Accordingly, the time required for diverging from an asynchronous state to a synchronous state is long, but if the synchronization is once performed, it becomes possible to restore the input signal with a high degree of precision.

Industrial Applicability

As apparent from the above description, an indoor CDMA mobile communication system according to the present invention does not require a separate installation of an expensive GPS cable that is required for synchronization of the system, can transmit GPS information using a LAN cable (e.g., a twisted pair cable) installed indoors or outdoors for a traffic, and can simultaneously supply traffic information, control information, power supply, reset signal, etc. Thus, it can be simply installed and costs for installation of a GPS supply unit and for installation and operation of repeaters or radio remote units.

The present invention provides an advantage that the GPS signal and the traffic signal can be used using the LAN cable installed in existing buildings without the necessity of a separate installation. That is, the present invention provides a construction that can simultaneously transmit three kinds of signals of TOD, IPPS and 10MHz or IPPS, lOMHz and reset signals using two pairs of lines allocated for backup of the existing LAN cables, and thus the existing LAN cables can be used as they are. Especially, the present invention provides an inexpensive high-precision DPLL by applying a dividing circuit for minimizing attenuation and distortion due to the distance of the LAN cable and an accumulated average DPLL technique for restoring the 10MHz signal. The present invention simultaneously transmits the TOD signal through a traffic line, and enables a remote reset control of a base transceiver subsystem that receives the GPS signal through a GPS-signal matching section by allocating the reset signal, so that the costs required for repair and maintenance can be greatly reduced. In addition, in case that many GPSs are required indoors or in a place where base transceiver subsystems close together, one GPS can be shared using the existing LAN cables without any separate installation, and thus the costs and space required for the installation, repair and maintenance, and operation of the system can be greatly reduced. Especially, the present invention enables sharing of the GPS clock even in a base transceiver subsystem that is installed underground and hardly receives the GPS clock. In order to cover shaded areas or areas where radio waves are weak, the present invention provides flexibility in service expansion by using a general LAN cable for connection to repeaters or remote radio units instead of the existing expensive optical cables or special coaxial cables. The forgoing embodiments are merely exemplary and are not to be construed as limiting the present invention. The present teachings can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.

Claims

1. An indoor CDMA mobile communication system for simultaneously supplying a traffic signal, control signal and global positioning system (GPS) signal using a local area network (LAN) cable, the system comprising: a GPS antenna for receiving a GPS signal outputted from a satellite;

■ a coaxial cable for transmitting the received GPS signal; a GPS signal matching section composed of a GPS receiver for receiving and demodulating the GPS signal, and an encoder for modulating and encoding the traffic signal, control signal and GPS signal so as to transmit the signals^* to match characteristics of the LAN cable in consideration of electric and mechanical characteristics of the LAN cable; and at least one base transceiver subsystem including a GPS signal decoder for converting the modulated and encoded signals transmitted through the LAN cable, connecting to the GPS signal matching section through the LAN cable, and operating in synchronization with the decoded GPS signal.

2. The indoor CDMA mobile communication system of claim 1, further comprising a hub, connected between the GPS signal matching section and the base transceiver subsystem, for collecting and driving connection lines of the LAN cable.

3. The indoor CDMA mobile communication system of claim 1, further comprising at least one repeater or remote radio unit connected to the base transceiver subsystem in order to cover shaded areas or to expand service areas.

4. The indoor CDMA mobile communication system of claim 3, further comprising at least one hub, connected between the base transceiver subsystem and the repeater or remote radio unit, for collecting and driving connection lines of the LAN cable connected to the repeater or remote radio unit.

5. The indoor CDMA mobile communication system of claim 4, wherein the hub comprises: a first Ethernet matching section for driving connection lines of the LAN cable or modulating/demodulating a clock signal; a packet processing section for performing a framing/inverse framing operation and a multiplexing/demultiplexing operation for converting input data into a form required for the base transceiver subsystem and the remote radio unit to transfer the converted data, the packet processing section being capable of identifying a desired remote radio unit; a clock restoring section for a 25MHz clock transferred from the base transceiver subsystem; and at least one second Ethernet matching section for driving the LAN cable of the remote radio unit or modulating/demodulating the clock.

6. The indoor CDMA mobile communication system of claim 1, wherein the GPS signal matching section is included in a control station for controlling a certain number of base transceiver subsystems.

7. The indoor CDMA mobile communication system of claim 1, wherein the GPS signal matching section is included in one of the base transceiver subsystems.

8. The indoor CDMA mobile communication system of claim 1, wherein the base transceiver subsystem comprises: at least one hub connected to a LAN cable; and at least one repeater or remote radio unit connected to the hub.

9. The indoor CDMA mobile communication system of claim 1, wherein the encoder uses an accumulated average digital phase locked loop (DPLL) circuit for converting a 10MHz signal among timing signals received by the GPS receiver into a 10/N MHz signal by dividing the 10MHz signal by N, inverse-converting the 10/N MHz signal into the 10MHz signal, and restoring a clock signal based on the timing signal of one pulse per second (IPPS).

10. The indoor CDMA mobile communication system of claim 1, wherein the decoder uses a digital phase locked loop (DPLL) circuit which comprises: an accumulated average unit for obtaining an accumulated average of an input signal; a phase comparator for generating a voltage corresponding to a phase difference between the input signal and an output of a voltage-controlled oscillator; a digital loop filter for removing high-frequency components generated in the phase comparator, and determining synchronous characteristics of the PLL circuit; and the voltage-controlled oscillator for varying it oscillation frequency according to a voltage corresponding to the phase difference.

11. The indoor CDMA mobile communication system of claim 1, wherein the LAN cable is a twisted pair cable.

12. A control method for an indoor CDMA mobile communication system for simultaneously supplying a traffic signal, control signal and global positioning system (GPS) signal using a local area network (LAN) cable, the system including a GPS signal matching section composed of a GPS receiver for receiving and demodulating a GPS signal, and an encoder for modulating and encoding waveforms in order to transmit the traffic signal through two pairs of lines of the LAN cable having four pairs of lines and to transmit the signals through the two remaining backup pairs of lines to match characteristics of the LAN cable, and at least one base transceiver subsystem including a GPS signal decoder for converting the modulated and encoded signals transmitted through the LAN cable into the original GPS signal, the method comprising: transferring a clock signal by applying a modulation/demodulation technique for modulating timing signals of time of date (TOD), one pulse per second (IPPS) and lOMHz from the GPS signal received by the GPS receiver and transmitting the timing signals through the two backup pairs of lines.

13. The control method of claim 12, wherein the IPPS signal and the lOMHz signal are modulated and simultaneously transmitted through a pair of lines among the two backup pairs of lines, a reset signal is allocated to the remaining pair of lines, and the TOD signal is transmitted through the lines through which the traffic signal is transmitted.

14. The control method of claim 12, wherein the IPPS signal and a 10/N MHz signal are allocated to a pair of lines among the two backup pairs of lines, and the TOD signal is allocated to the remaining pair of lines.

15. The control method of claim 12, wherein the IPPS signal is allocated to a pair of lines among the two backup pairs of lines, and a 10/N MHz signal is allocated to the remaining pair of lines.

16. The control method of claim 14 or 15, wherein the 10MHz signal among the timing signals received by the GPS receiver is converted into the 10/N MHz signal by dividing the lOMHz signal by N, the 10/N MHz signal is converted into the 10MHz signal, and the clock signal is restored based on the IPPS signal.