Patent Abstract:
A signal supply apparatus for a public and private mobile communication system. The apparatus has Internet protocol base transceiver subsystems, and a private base station controller that controls the Internet protocol base transceiver subsystems. Instead of having a global positioning system receiver (GPSR) in each of the Internet protocol base transceiver subsystems to receive time of day (TOD) signals, the TOD signals are relayed to each of the Internet protocol base transceiver subsystems via a LAN cable. It is only the base station controllers that have the GPSR that receives the TOD signals. Then, these TOD signals are relayed from the base station controller to respective collective base station transceivers and then from each collective base station transceiver to their respective Internet protocol base transceiver subsystems via a LAN cable.

Full Description:
CLAIM OF PRIORITY 
   This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. § 119 from my application entitled SIGNAL SUPPLY APPARATUS FOR PUBLIC AND PRIVATE MOBILE COMMUNICATION SYSTEM filed with the Korean Industrial Property Office on 27 Sep. 2001 and there duly assigned Serial No. 2001-59972. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a mobile communication system, and more particularly to a signal supply apparatus in a system that can provide both public and private mobile communication services. 
   2. Description of the Prior Art 
   In a general mobile communication system, a base station controller (BSC) receives a reference clock signal from a satellite, and synchronizes its internal equipment. For instance, the BSC provides a link between the BSC and a mobile switching center (MSC), a link between the BSC and a base transceiver subsystem (BTS), and a vocoder. In order to receive the reference clock from the satellite, a global positioning system receiver (GPSR) is mounted in the respective BSCs and BTSs, respectively. The GPSR receives GPS information that includes the reference clock and time of day (TOD) information from the satellite, and provides the GPS information to the corresponding equipment. 
   As described above, in order to receive the reference clock, the GPSR should be mounted on the respective BSCs and BTSs. However, if it is possible to supply the GPS information including at least the reference clock to the respective BTSs that belong to the BSC in a state that the GPSR is mounted only in the corresponding BSC, the system cost can be reduced. Also, if it is possible to supply the GPS information including at least the reference clock to the BSC and BTS using the existing lines, the cost of system installation can be reduced. 
   U.S. Patent Application Publication No. 2001/0046215 to Kim pertains to a public/private mobile telephone system where only pBSC  203  has a GPS receiver. However, Kim &#39;215 does not teach relaying the date and time information received by the GPS receiver over a LAN cable to a large plurality of Internet protocol private base transceiver subsystems to run a clock in these Internet protocol private base transceiver subsystems, thereby avoiding the need of many GPS receivers. 
   U.S. Patent Application Publication No. 2001/0024455 to Thaler et al. teaches distributing a reference time signal throughout a IEEE 1394 network. Thaler &#39;455 contemplate receiving the reference signal from GPS. Non 1394 networks are also contemplated. Thaler &#39;455 teaches that the network may be wired or wireless. An 8 kHz clock is contemplated in  FIG. 4 . Thaler &#39;455 also teaches distribution of the time reference signal over a LAN. 
   U.S. Patent Application Publication No. 2002/0072381 to Becker et al, teaches transmission of time synchronization signals from one base station to another in a mobile telephone communication system. Becker &#39;381 seeks to do this to reduce the costs of having numerous GPS receivers in a mobile phone system. The synchronization signals are transmitted by wireless communications. 
   However, I have not seen the transmission of time and date signals received from a GPS receiver to a large number of private base transceiver subsystems in a public/private mobile communications system. Further, I have not seen the transmission of GPS time and date information over a LAN cable to a large number of private base transceiver subsystems. Further, I have not seen the transmission of GPS time and date signals to recipient private base transceiver subsystems to generate a plurality of internal clocks in these private base transceiver subsystems where the private base transceiver subsystems do not have a GPS receiver or a GPS antenna. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a signal supply apparatus for a public and private mobile communication system that enables a base station controller to receive GPS information and to supply a reference clock and TOD information to the base station controller and base transceiver subsystems. 
   It is also an object of the present invention to provide a signal supply apparatus that enables a base station controller to supply a reference clock and TOD information to the base station controller and base transceiver subsystems using the existing lines. 
   It is further an object of the present invention to distribute to a large number of private base transceiver subsystems GPS time and date information over a LAN cable. 
   It is still yet another object of the present invention to generate internal clocks in a large number of private base transceiver subsystems using GPS information sent over a cable. 
   It is yet also another object of the present invention to generate internal clocks in a large number of private base transceiver subsystems from GPS time and date signals where the private base transceiver subsystems do not have either a GPS receiver or a GPS antenna. 
   In order to accomplish these objects, there is provided a signal supply apparatus for a public and private mobile communication system including a plurality of Internet protocol base transceiver subsystems each having a plurality of Internet protocol private base transceiver subsystems which can be connected by an Internet protocol, respectively; and a private base station controller that controls the plurality of Internet protocol base transceiver subsystems and checks their status, the private base station controller receiving a reference clock and time of day (TOD) information from a satellite, and transmitting to the plurality of Internet protocol base transceiver subsystems various kinds of signals including the TOD information and a sync clock having a frequency that can be transmitted through a local area network (LAN) cable; wherein each of the Internet protocol base transceiver subsystems comprises the plurality of Internet protocol private base transceiver subsystems that can be connected by the Internet protocol through the LAN cable, and generate various kinds of clocks internally required using the sync clock; and collective base transceiver subsystems, connected to the plurality of Internet protocol private base transceiver subsystems through the LAN cable, for performing a function of the base station controller with respect to the plurality of Internet protocol base transceiver subsystems and performing a function of one base transceiver subsystem with respect to the private base station controller, the collective base transceiver subsystems performing a conversion and inverse conversion of a call service signal from the private base station controller into the Internet protocol, and transmitting various kinds of signals including the sync signal and the TOD information transmitted by the private base station controller and the call service signal converted into the Internet protocol to the plurality of Internet protocol base transceiver subsystems through the LAN cable. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
       FIG. 1  is a block diagram of a network for explaining the concept of a public and private mobile communication service; 
       FIG. 2  is a block diagram of the public and private communication service equipment according to an embodiment of the present invention; 
       FIG. 3  is a view illustrating a connection state of signal lines for supplying signals from a pBSC to IP-pBTSs; 
       FIG. 4  is a block diagram of a cBTS matching section constructed for internal or external mounting of cBTSs in a system; and 
       FIG. 5  is a timing diagram of sync clock signals. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The mobile communication network is classified into a public mobile communication network and a private (or intra-office) mobile communication network, and if the mobile communication service is provided with the interlocking of the two networks, it will be much convenient to users. This is called a public and private mobile communication system.  FIG. 1  shows the construction of a public and private mobile communication system that can provide both a public mobile communication service and a private mobile communication service. In order to provide both the public and private mobile communication services, the public and private mobile communication system, as shown in  FIG. 1 , has a public/private shared cell area  14  that is a public and private shared communication service area, and is provided with a public/private communication service equipment  12 . It is preferable that the public/private shared cell area  14  is allocated for the convenience of a specified group (company, institution, school, etc.) in providing a communication service. For instance, if it is assumed that a specified company uses a building, an area to which the building belongs may be allocated as the public/private shared cell area  14 . It is preferable that allocation of the public/private shared cell area  14  is made in agreement with a public mobile communication service provider in advance. In this case, a private base transceiver subsystem (private BTS:  8 - k ) in the public/private shared cell area  14  can be recognized as a public BTS from a viewpoint of the public mobile communication system. In the description, in order to discriminate the BTSs belonging to the public mobile communication system, i.e., the BTSs  6 - 1  to  6 - k , and  8 - 1  illustrated in  FIG. 1 , from the private BTS  8 - k  in the public/private shared cell area  14 , the private BTS  8 - k  is called “pBTS”. The pBTS  8 - k  is in radio communication with a mobile station (MS)  24  located in the public/private shared cell area  14 , and performs a function of managing radio resources. The pBTS  8 - k  is connected to a base station controller (BSC) of the public mobile communication system, for instance, BSC  4 - m  illustrated in  FIG. 1 , through the public/private communication service equipment  12 . The public/private communication service equipment  12  is connected to the BSC  4 - m  of the public mobile communication system, a public switch telephone network/integrated services digital network (PSTN/ISDN)  16 , and an Internet protocol network  18 . The public/private communication service equipment  12  performs the mobile communication service so that the public mobile communication service and the private mobile communication service can be selectively provided to mobile stations (MSs) in the public/private communication shared cell area  14 , for example, an MS  24  of  FIG. 1 . If the MS  24  is registered in the public/private communication service equipment  12  so that it can receive the private mobile communication service, the MS  24  can receive the private mobile communication service in addition to the public mobile communication service. However, if the private mobile communication service of the MS is not registered in the public/private communication service equipment  12 , the MS  24  can receive only the public mobile communication service. Also, the public/private communication service equipment  12  performs a wire communication service with the PSTN/ISDN  16  and the IP network  18 . 
   Meanwhile, the public mobile communication network is typically called a public land mobile network (PLMN), and includes, as illustrated in  FIG. 1 , a plurality of mobile switching centers (MSCs)  2 - 1  to  2 - n , a plurality of base station controllers (BSCS)  4 - 1  to  4 - m , a plurality of base transceiver subsystems (BTSs)  6 - 1  to  6 - k , and  8 - 1  to  8 - k , mobile stations (MSs)  20  and  22 , and a home location register/visitor location register (HLR/VLR)  10 . The plurality of MSCs  2 - 1  to  2 - n  are connected to the plurality of BSCs  4 - 1  to  4 - m , respectively, and the plurality of BSCs  4 - 1  to  4 - m  are connected to the plurality of BTSs  6 - 1  to  6 - k , and  8 - 1  to  8 - k , respectively. Especially, the pBTS  8 - k  among the plurality of BTSs  8 - 1  to  8 - k  is connected to the BSC  4 - m  of the public mobile communication system. The respective MSCs  2 - 1  to  2 - n  controls the connection of the respective BSCs  4 - 1  to  4 - m  to the PSTN/ISDN or another MSC in the public mobile communication network. The respective BSCs  4 - 1  to  4 - m  perform a wireless link control and a handoff function, and the respective BTSs  6 - 1  to  6 - k , and  8 - 1  to  8 - k  constitute wireless communication paths along with the MS  20 ,  22 , and  24  which belong to their own communication service areas, i.e., which belong to their cell areas, and manage the wireless resources. In the HLR/VLR  10 , the HLR performs a function of registering subscriber locations and a database function of storing subscriber information, and the VLR is a database for temporarily storing information of the MS existing in the cell area of the corresponding MSC among the plurality of MSCs  2 - 1  to  2 - n . If the MS moves to a cell area that is managed by another MSC, the information stored in the corresponding VLR is deleted. In the description, in order to discriminate from the public/private shared cell area  14 , the communication service areas of the BTSs  6 - 1  to  6 - k , and  8 - 1  to  8 - k  of the public mobile communication system are called public dedicated cell areas. As an example, the communication service area of the BTS  8 - 1  among the BTSs  6 - 1  to  6 - k , and  8 - 1  to  8 - k  of the public mobile communication system is marked as the public dedicated cell area  15  in  FIG. 1 . Typically, the public dedicated cell area  15  is much wider than the public/private shared cell area  14  determined for the convenience of a specified group in providing a communication service. 
   In  FIG. 1 , an E 1  line  30  connects the public/private communication service equipment  12  to the pBTS  8 - k , and thus whenever a new pBTS is added, a new E 1  line should be installed. This causes an increase of the installation cost and inconvenience in system installation. 
   In the embodiment of the present invention, considering that the place where the private mobile communication service is to be used is a building of a specified group and the typical LAN cables have already been installed in the building, the existing LAN cables are used instead of new E 1  lines. 
     FIG. 2  is a block diagram of the public and private communication service equipment according to an embodiment of the present invention. In  FIG. 2 , collective base transceiver subsystems (cBTSs)  46 - 1  to  46 - 5  in Internet protocol base transceiver subsystems (IP-BTSs)  44 - 1  to  44 - 5  are connected to corresponding Internet protocol private base transceiver subsystems (IP-pBTSs)  48 - 1  to  48 - 6 , respectively, through LAN cables  64 . 
   Referring to  FIG. 2 , an Internet protocol private branched exchange (IP-PBX)  32  is a private exchange having a voice over Internet protocol (VoIP) function. The IP-PBX  32  accommodates intra-office wire subscribers  34  by connecting to a PSTN/ISDN  16 , and can connect to an intra-office dedicated digital telephone  36 . Also, the IP-PBX  32  has a VoIP card mounted therein, and supports the VoIP function. In case of connecting to a private base station controller (pBSC)  38 , the IP-PBX is also used as a switching system. That is, the IP-PBX  32  switches a private mobile communication service (i.e., intra-office call), which is not the public network connection, under the control of the pBSC  38 . The IP-PBX  32  is connected to the pBSC  38  by the E 1  line, and has a LAN port for the VoIP support. 
   The pBSC  38  is abase station controller that controls the lower IP-BTSs  44 - 1  to  44 - 5  and checks their status. If the public mobile communication service is requested from the MS located in the public/private shared cell area  14 , the pBSC  38  serves to directly bypass the request to the public BSC  4 - m  of  FIG. 1  without passing through the IP-PBX  32 . The pBSC  38  is divided into 4 parts: a system clock supply section  50 , an asynchronous transfer mode (ATM) switching and pBSC main control section  52 , a public network BSC and IP-BTS connection section  54 , and an IP-PBX connection section  56 . 
   The system clock supply section  50  includes a GPSR and a master clock distribution board assembly (MCDA). The system clock supply section  50  receives GPS information including a reference clock and TOD information from a satellite, and supplies various kinds of signals required for respective blocks and sync clocks to the blocks. In the embodiment of the present invention, signals transmitted from the system clock supply section  50  to the IP-BTSs  44 - 1  to  44 - 5  include the TOD information and the power supply voltage, and the sync clocks includes sync clocks having a frequency of 8 KHz, which can be transmitted through the LAN cable  64 , and an even second signal Even_Sec. 
   The ATM switching and pBSC main control section  52  includes an ATM switch, an alarm signal collection section, and a main control section. The ATM switch performs an ATM switching function, and the alarm signal collection section collects alarm signals applied by the respective blocks. The main control section performs the whole control of the respective blocks of the pBSC  38 , and is connected to the call management section  40  by an optical cable to inform the alarm signals collected by the alarm signal collection section to the call management section  40 . The public BSC and IP-BTS connection section  54  is a block for connecting to a public network PLMN (i.e., BSC  4 - m  in the embodiment of  FIG. 1 ). The IP-PBX connection section  56  converts an audio compressed signal received from the MS into a pulse code modulation (PCM) signal, and transfers the PCM signal through the E 1  lines. The respective blocks of the pBSC  38  communicate with one another through a multiplexer and demultiplexer for multiplexing and demultiplexing the ATM cells. The multiplexer and demultiplexer multiplexes the ATM cells coming out of respective sources, and transfers the multiplexed ATM cells to a destination. The multiplexer and demultiplexer also performs a demultiplexing operation opposite to the above multiplexing operation. 
   An IP network connection section  42  is a block for connecting to an IP network  18 , and is composed of a hub and a router. The call management section  40  is the pBSC management equipment that provides to the users operation status of the pBSC  38  and the IP-BTSs  44 - 1  to  44 - 5  and various kinds of alarms generated during operation in a graphic user interface (GUI) environment. Also, the call management section downloads a program required by the respective blocks during the system operation through the pBSC main control section in the pBSC  38 , and automatically updates the program when it is changed. The call management section  40  also performs a remote control of the pBSC  38  and the IP-BTSs  44 - 1  to  44 - 5  so that the environment or operation of the pBSC  38  or the IP-BTSs  44 - 1  to  44 - 5  can be changed during the system operation. 
   The IP-BTSs  44 - 1  to  44 - 5  are parts that allocate the wireless resources, and interface with the MS located in the public/private shared cell area (i.e.,  14  in  FIG. 1 ) by sending an actual radio frequency (RF) signal. Also, the respective IP-BTSs  44 - 1  to  44 - 5  receives audio data from a public network BSC and IP-BTS connection section  54  of the pBSC  38 , converts the audio data into an RF signal, and then transmits the RF signal through an antenna. In the opposite operation, the respective IP-BTSs also receives an RF signal from the MS, converts the RF signal into a digital compressed signal, and then sends the digital compressed signal to the pBSC  38 . Specifically, each of the respective IP-BTSs  44 - 1  to  44 - 5  is composed of one cBTS and  6  IP-pBTSs at maximum, and from the viewpoint of the pBSC  38 , they are managed and operated as one BTS. 
   The IP-BTS  44 - 1  among the IP-BTSs  44 - 1  to  44 - 5  is composed of one cBTS  46 - 1  and  6  IP-pBTSs  48 - 1  to  48 - 6 . The pBSC  38  and the cBTS  46 - 1  are connected through an ATM-E 1  line  62  in the same manner as the connection between the existing BSC and the BTS, but the connection among the  6  IP-pBTSs  48 - 1  to  48 - 6  corresponding to the cBTS  46 - 1  is made through a LAN cable  64 . As the cBTS  46 - 1  and the  6  IP-pBTSs  48 - 1  to  48 - 6  are connected through the LAN cable  64 , transmission control protocol (TCP) and user datagram protocol (UDP) communications can be performed between the cBTS  46 - 1  and the  6  IP-BTSs  48 - 1  to  48 - 6 . Since the LAN cable  64  is typically installed wherever the public and private mobile communication service is received, a plurality of IP-pBTSs can be installed using the LAN cable  64  with the installation cost of the system reduced. Also, the additional installation of the IP-pBTSs can be conveniently performed. 
   The cBTS  46 - 1  in the IP-BTS  44 - 1  that is one among the blocks constructed to accommodate the plurality of IP-BTSs and the LAN cable  64  is located between the IP-pBTSs  48 - 1  to  48 - 6  and the pBSC  38 . The cBTS  46 - 1  performs a function of a base station controller with respect to the IP-pBTSs  48 - 1  to  48 - 6 , and performs a function of a base transceiver subsystem with respect to the pBSC  38 . That is, the cBTS  46 - 1  performs various kinds of functions for enabling the 6 IP-pBTSs  48 - 1  to  48 - 6  at maximum provided in the IP-BTS  44 - 1  to be regarded as one BTS from the viewpoint of the pBSC  38 . The various kinds of functions of the cBTS  46 - 1  will be explained in detail below.
         wireless resources management, call control, statistics, status, alarm, etc.   status management of the IP-pBTSs  48 - 1  to  48 - 6  and information providing to the pBSC  38     IP-to-ATM mapping function   ATM/inter-processor communication (IPC) control function (ATM adaptation later (AAL) 0/2/5)   real-time transport protocol (RTP) control function with the IP-pBTSs   handoff control function among the lower corresponding IP-pBTSs  48 - 1  to  48 - 6  connected to the cBTS  46 - 1  itself (at this time, ATM path information is not changed.)   base station controller identifier (ID) control function for handoff with other IP-pBTSs (including cBTS). Different base transceiver subsystem IDs are given to the respective IP-pBTSs  48 - 1  to  48 - 6 , but the cBTS  46 - 1  is controlled by the base transceiver subsystem ID which is known to the network.       

   The respective IP-pBTSs  48 - 1  to  48 - 6  connected to the cBTS  46 - 1  through the LAN cable  64  perform the following function. Each of the IP-pBTSs  48 - 1  to  48 - 6  is composed of a wireless channel control section, a modem section, a radio frequency/intermediate frequency (RF/IF) section, an IP connection section, an antenna section (distributed antenna), etc., and accommodates 32 channels for an audio subscriber and 4 channels for a data subscriber (based on 144 kbps). Also, the channel control section performs an IP connection for a bi-directional accommodation and a status control of the IP-pBTS in consideration of a channel management performance. The antenna section is composed of 1-8 distributed antennas to accommodate an attenuation of 0-9 dbm. The respective IP-pBTSs  48 - 1  to  48 - 6  perform the RTP control function with the cBTS  46 - 1 . 
   Though the IP-BTS  44 - 1  and its internal blocks have been explained as above, it should be understood that the remaining IP-BTSs  44 - 2  to  44 - 5  and their internal blocks perform the same operation as the IP-BTS  44 - 1  and its internal blocks. 
     FIG. 3  is a view illustrating a connection state of signal lines for supplying signals from the pBSC  38  to the IP-pBTSs  48 - 1  to  48 - 6  corresponding to the cBTSs  46 - 1  to  46 - 5 .  FIG. 3  shows two cBTSs  46 - 1  and  46 - 2  among 5 cBTSs  46 - 1  to  46 - 5  and 6 IP-pBTSs  48 - 1  to  48 - 6  corresponding to the cBTSs  46 - 1  and  46 - 2 . 
   It is preferable that the pBSC  38  and the cBTSs  46 - 1  to  46 - 5  are mounted together on a shelf. Various kinds of signals and the sync clock provided from the system clock supply section  50  of the pBSC  38  are supplied to the cBTSs  46 - 1  to  46 - 5  through a clock supply cable  62 . As shown in  FIG. 3 , the various kinds of signals and the sync clock are a sync clock of 8 KHz, an even second signal Even_Sec, a TOD signal, and a power supply voltage of −48V. The timing of the sync clock of 8 KHz and the even second signal Even_Sec is illustrated in  FIG. 5 . Referring to  FIG. 5 , the even second signal Even_Sec has a pulse width corresponding to one period of a 4.096 MHz signal, and the 8 KHz signal has a pulse width corresponding to two periods of the 4.096 MHz signal. However, the phase of a 1.544 MHz signal is not consistent with that of the even second signal Even_Sec. 
   Referring again to  FIG. 3 , the TOD signal among the various kinds of signals and the sync clock is applied to the cBTS  46 - 1 , cBTS  46 - 2 , and cBTSs  46 - 3  to  46 - 5  in order. Between the public BSC and IP-BTS connection section  54  of the pBSC  38  and the cBTSs  46 - 1  to  46 - 5  is connected an ATM-E 1  line  60 , and an ATM E 1  signal is transmitted/received through the ATM-E 1  line  60 . Also, between the cBTSs  46 - 1  to  46 - 5  and the corresponding IP-pBTSs  48 - 1  to  48 - 6  is connected the LAN cable  64 . The LAN cable  64  is composed of 4 lines of the E 1  signal and 4 lines of the reference clock, and can be installed with a length as long as 200 meters at maximum. 
   The cBTSs  46 - 1  to  46 - 5  located between the pBSC  38  and the IP-pBTSs  48 - 1  to  48 - 6  are in an ATM-E 1  connection with the pBSC  38 , and in an IP connection with the IP-pBTSs  48 - 1  to  48 - 6  through an Ethernet port. That is, the respective cBTSs  46 - 1  to  46 - 5  receive the ATM-E 1  signal from the pBSC  38 , convert the ATM-E 1  signal into an IP signal, and then transfer the IP signal to the IP-pBTSs  48 - 1  to  48 - 6 . The respective cBTSs  46 - 1  to  46 - 5  supply the even second signal Even_Sec that is the sync clock required by the IP-pBTSs  48 - 1  to  48 - 6 , the 8 KHz signal, and the TOD signal to the lower IP-pBTSs  48 - 1  to  48 - 6 . The clock signals required by the IP-pBTSs  48 - 1  to  48 - 6  are, for example, a 10 MHz signal, 29.4912 MHz signal, 4.096 MHz signal, 1.544 MHz signal, even second signal Even_Sec, etc. However, since the high-frequency signals in the range of about several to several tens of MHz cannot be sent far (i.e., 200 m at maximum), only the even second signal Even_Sec that is the sync clock and the 8 KHz signal are supplied. In this case, the respective IP-pBTSs  48 - 1  to  48 - 6  provide the sync clock to their internal phase locked loop (PLL) logic as the reference signal, and the required clocks (for example, the 10 MHz, 29.4912 MHz, 4.096 MHz, and 1.544 MHz) synchronized by the PLL logic are generated. 
   One cBTS is designed to control 6 IP-pBTSs at maximum. Accordingly, if it is assumed that 5 cBTSs are mounted, each cBTS accommodates 6 IP-pBTSs at maximum, and thus 30 IP-pBTSs are connected from the viewpoint of one pBSC  38 . If 30 IP-pBTSs  48 - 1  to  48 - 6  are directly connected to one pBSC  38 , the corresponding number of E 1  lines (i.e., 30 E 1  lines) is required. Also, the capacity that can be processed by the pBSC  38  is limited. Thus, in the embodiment of the present invention, the cBTSs  46 - 1  to  46 - 5  are mounted between the pBSC  38  and the IP-pBTSs  48 - 1  to  48 - 6 , so that the cBTSs process the signals which are not required to pass through the pBSC  38 . 
     FIG. 4  is a block diagram of a cBTS matching section  100  constructed for the internal or external mounting of 5 cBTSs  46 - 1  to  46 - 5  in the system. The cBTS matching section  100  to be explained later is provided with connectors and slots installed therein in order to support all the internal and external mounting of the cBTSs  46 - 1  to  46 - 5  in the system. 
   Referring to  FIG. 4 , The ATM-E 1  signal received from the pBSC  38  through the ATM-E 1  cable is connected to a connector  70  illustrated in  FIG. 4 , and then connected to an IP-pBTS connector  78  through patterns. Between the IP-pBTS connector  78  and cBTS slots  84 - 1  to  84 - 5  for mounting the cBTSs  46 - 1  to  46 - 6  are connected backboard patterns (in case of built-in cBTS) or cables (in case of armored cBTS). The sync clock signal of 8 KHz and the even second signal Even_Sec received from the pBSC  38  through the clock supply cable  62  are connected to a connector  72  through the clock supply cable  62 , and then connected to an IP-pBTS clock connector  80  through the patterns. Between the IP-pBTS clock connector  80  and cBTS slots  84 - 1  to  84 - 5  for mounting the cBTSs  46 - 1  to  46 - 5  are connected backboard patterns (in case of built-in cBTS) or cables (in case of armored cBTS). The TOD signal received from the pBSC  38  through the clock supply cable  62  is connected to a clock driving section  76  through a connector  74 . The TOD signal is driven by the clock driving section  76 , and connected to the IP-pBTS clock connector  80 . The TOD signal transmitted from the system clock supply section of the pBSC  38  is received only through a pre-provided port, and since it is required for the cBTS to receive the TOD signal through 5 ports, the clock-driving section  76  is provided. The clock driving section  76  provides the TOD signal to the IP-pBTS clock connector  80  and to the system clock supply section  50  of the pBSC  38  through a connector  82  by allocating one port. 
   The signal lines connected to the CBTS slots  84 - 1  to  84 - 5  through the backboard patterns (in case of built-in cBTS) and the cables (in case of armored cBTS), as shown in  FIG. 4 , are 4 ATM-E 1  signal lines ATM-E 1 , and  6  clock signal lines 8 KHz+/−, Even_Sec +/−, and TOD TX+/TOD TX−. The respective cBTS slots  84 - 1  to  84 - 5  are connected through patterns to 6 connectors  86 - 1  to  86 - 6  and  88 - 1  to  88 - 6  provided for the connection to the 6 IP-pBTSs  48 - 1  to  48 - 6 . 
   The transfer of the E 1  signal and the sync clock from one cBTS to 6 IP-pBTS  48 - 1  to  48 - 6  using the LAN cable  64  according to the embodiment of the present invention has the following advantages. 
   Typically, the clock signals required by the BTS are generated using the GPSR mounted in the BTS. That is, the GPSR mounted in the BTS receives the reference clock from the satellite, and generates clocks required by the respective blocks through the internal PLL logic based on the reference clock. In the embodiment of the present invention, since it is not easy in cost, installation, maintenance and repair to mount the GPSR for each IP-pBTS in a structure that can accommodate 30 IP-pBTSs at maximum, an 8-wire LAN cable is used. The existing LAN cable can be used as they are, or a new LAN cable may be installed. The newly installed LAN cable is used not only for the transmission of the E 1  signal, sync clock, and TOD information according to the embodiment of the present invention, but also for the data transmission in a network terminal using an Ethernet port. In the embodiment of the present invention, among the 8 wires of the LAN cable, 4 lines are used for the transmission of the E 1  signal Tx+/Tx− and Rx+/Rx−, and the remaining 4 lines are used for the transmission of the sync clock of 8 KHz and the even second signal Even_Sec. Since the 8 KHz signal and the even second signal Even_Sec (0.5 Hz) are low-frequency signals of several to several tens of Hz, the loss due to the length of line is small. Accordingly, the IP-pBTS that received the 8 KHz signal and the even second signal Even_Sec (0.5 Hz) through the LAN cable can reproduce the required clocks through the PLL logic based on the 8 KHz signal and the even second signal Even_Sec. Also, the TOD signal received from the satellite by the system clock supply section  50  is provided to the respective IP-BTS under the control of the pBSC main control section of the ATM switching and pBSC main control section  52  in the pBSC  38 . Since the IP-pBTSs  48 - 1  to  48 - 6  according to the embodiment of the present invention do not mount the GPSR therein, the TOD signal is directly transmitted from the system clock supply section  50  to the respective IP-pBTSs  48 - 1  to  48 - 6 . The TOD signal is a message having a specified format, and thus can be outputted from the system clock supply section  50  to the respective IP-BTSs through the cBTS. 
   In the embodiment of the present invention, an unshielded twisted pair (UTP) cable represented as a high-speed and extremely high-speed information communication cable is used as the LAN cable  64  provided between the cBTSs  46 - 1  to  46 - 5  and the IP-pBTSs  48 - 1  to  48 - 6 , respectively. 
   As described above, according to the present invention, the GPSR is not mounted in the BSC and the pBTS, respectively, and thus the system cost can be reduced. Also, the required signals and the sync signal are supplied to the pBTS through only one line of the LAN cable, and thus the cost for system installation can be reduced with the convenience in construction greatly increased. Also, the present invention can support both the internal mount and the external mount of the cBTS in the system to provide convenience to users. 
   Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Technology Classification (CPC): 7