Abstract:
An apparatus and method for controlling a transmission power of a base transceiver station in a CDMA mobile communication system is disclosed. The apparatus for controlling a transmission power in a CDMA mobile communication system, including: a central processing unit (CPU) for performing control operation according to a power control require signal of a user; a gain controller for outputting a gain signal according to the CPU control; and a gain variable amplifier for regulating transmission power by varying according to the gain signal of the gain controller.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a code division multiple access (CDMA) mobile communication system; and, more particularly, to an apparatus and method for controlling transmission power of a CDMA mobile communication system, which can regulate the transmission power based on a power control command. 
   DESCRIPTION OF THE PRIOR ART 
   In a code division multiple access (CDMA) mobile communication, an additional repeater or a base transceiver station subsystem (hereinafter, referred to as a BTS) is established to increase communication quality or to solve a shade region problem. 
   Transmission power of the BTS is regulated and operated in the beginning of system establishment so, in case of installing the additional repeater or BTS, the transmission power of the current operating BTS may be re-regulated. 
   However, during the re-regulating period, the BTS cannot provide communication services, which makes users inconvenient. Moreover, the re-regulating operation is usually performed manually. An operator regulates the transmission power of the BTS manually by using a measuring equipment, however in this case, an accurate power regulating is difficult and regulating time is prolonged. 
   Therefore, when the transmission power of the BTS is regulated manually, there are disadvantages in that system efficiency is decreased and service interrupt time is long. 
   SUMMARY OF THE INVENTION 
   It is, therefore, an object of the present invention to provide an apparatus and method for controlling a transmission power of a CDMA mobile communication system, which can regulate the transmission power by using a command, in case of establishing an additional repeater or BTS. 
   To achieve the above object, in the present invention, a base power is set up, when an additional repeater is established, or the established repeater is removed and an additional BTS is established, all transmission power of the BTS is regulated by using an operator command. 
   In accordance with an aspect of the present invention, there is provided an apparatus for controlling a transmission power in a CDMA mobile communication system, including: a central processing unit (CPU) for performing control operation according to a power control require signal of a user; a gain controller for outputting a gain signal according to the CPU control; and a gain variable amplifier for regulating transmission power by varying according to the gain signal of the gain controller. 
   In accordance with another aspect of the present invention, there is provided a method for controlling a transmission power control in a CDMA mobile communication system, comprising the steps of: a) regulating a transmission power of a base transceiver station (BTS) to 0 dB; b) checking whether a power control request of an operator exists or not; c) determining whether the power control request of the operator is a first power control or a second power control; and d) re-regulating the transmission power of the BTS by varying a gain of an amplifier according to the determining result. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and aspects of the invention will become apparent from the following description of the embodiments with reference to the accompanying drawings, in which: 
       FIG. 1  is a block diagram illustrating a transmission power control circuit of a CDMA mobile communication system in accordance with the present invention; 
       FIG. 2  is a diagram showing a gain variable amplifier in  FIG. 1 ; and 
       FIG. 3  is a flow chart showing a transmission power re-regulate operation of BTS in FIG.  1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereinafter, a transmission power control circuit of a CDMA mobile communication system according to the present invention will be described in detail referring to the accompanying drawings. 
   A power control circuit of the BTS includes a modulating and amplifying block, which modulates and amplifies a base band signal to an intermediate frequency signal, a block of modulating the intermediate frequency signal to a radio frequency (RF), a power amplifier and a band pass filter. 
   Each of the blocks has gain for amplifying the base band signal so that total transmission power is generated, but the gain of each block and power amplifier have some margin, so any one block may control the whole transmission power. 
   The block of varying and amplifying the base band signal to the intermediate frequency signal undertakes the above-referenced role, so in case of establishing an additional repeater, the transmission power has to be re-regulated. 
   In the present invention, a base power is set up, and then all transmission power of the BTS is regulated in accordance with an operator command when an additional repeater is established, or the established repeater is removed and an additional BTS is established. 
     FIG. 1  is a block diagram illustrating a transmission power control circuit of a CDMA mobile communication system in accordance with the present invention. Referring to  FIG. 1 , the transmission power control circuit includes a CPU  10  for generating a power control signal based on a command from the operator, a gain controller  11  for outputting a gain signal according to the control signal from the CPU  10  control and a gain variable amplifier  12  for regulating the transmission power by varying the gain to 0 dB or 3 dB according to the gain signal of the gain controller  11 . 
   The gain variable amplifier includes a gain regulator  12   a  and a gain variable amplifier  12   b . The gain regulator  12   a  regulates a gain of the gain variable amplifier  12   b  to 0 dB or 3 dB, according to the gain control signal of the gain controller  11 . 
   That is, when the repeater is used, the gain regulator  12   a  regulates the gain of the gain variable amplifier  12   b  to 0 dB, otherwise, regulates it to 3 dB. 
   When using the repeater, a two-way filter is used thereby decreasing the gain about 3 dB. In order to maintain the transmission power of BTS as much as before, the gain should be increased about 3 dB. However, if another additional device except the repeater is established, gain-regulating value of the gain regulator  12   a  may be changed. 
   An operation of the transmission power control circuit of the BTS in accordance with the present invention will be described. 
   When the transmission power control circuit of the BTS is initialized, the CPU  10  operates the gain controller  11  to perform a power control initializing operation at step S 1  which regulates the transmission power of the BTS to 0 dB, and sets power condition flag to “0” at step S 2 , which represents that the gain of the gain variable amplifier  12   b  is set to 0 dB. 
   That is, according to the control signal from the CPU  10 , the gain controller  11  outputs a gain control signal for setting the gain of the amplifier  12   b  to 0 dB, and according to the gain control signal, the gain regulator  12   a  of the gain variable amplifier  12  controls the gain of the gain variable amplifier  12   b  to 0 dB, thereby the power being controlled. 
   When an additional repeater is established, or an established repeater is removed and another additional repeater is established, the operator re-regulates the power of the BTS by using a power control command. The power control command is inputted to the CPU  10  through an interprocessor communication (IPC), so the CPU  10  outputs a power control signal, which corresponds to the inputted power control command, to the gain controller  11 . 
   The CPU  10  checks whether a power control request from the operator exists or not at step S 3 , and if the power control request does not exist, then maintains current status and repeats the step S 3 . 
   If the power control request from the operator exists, then the CPU  10  checks whether the power control request is 0 dB power control or 3 dB power control at steps S 4  and S 5 . 
   Since gain of the gain variable amplifier  12   b  is to be regulated from 0 dB to 3 dB when a repeater is additionally established, the gain of the gain variable amplifier  12   b  is to be regulated from 3 dB to 0 dB when an additional repeater is established after removing the installed repeater. 
   Also, according to the checking result, the CPU  10  outputs the power control signal to the gain controller  11  then, sets a corresponding power control flag to “0” or “1” at steps S 5  and S 6 . At this time, the power control flag “1” means the gain of the gain variable amplifier  12   b  is set to 3 dB. Therefore, according to the power control signal, the gain controller  11  outputs the gain control signal to the gain variable amplifier  12 , and according to the gain control signal, the gain regulator  12   a  regulates the gain of the gain variable amplifier  12   b  to 0 dB or 3 dB, such that the gain variable amplifier  12   b  controls power with 0 dB or 3 dB gain. 
   In the present invention, a base power is set up, and then all transmission power of the BTS is regulated in accordance with an operator command when an additional repeater is established, or the established repeater is removed and an additional BTS is established. As a result, the present invention may minimize a service interrupt period, which is caused by re-regulating of transmission power, and increase reliability and efficiency of the system. 
   Although the preferred embodiments of the invention have been disclosed 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.