KR100318936B1 - Apparatus and method for forward power controlling in cdma mobile communication system - Google Patents

Abstract

According to the present invention, in an apparatus for forward power control in a code division multiple access mobile communication system, an S-I-AL (SIR) is measured on a frame-by-frame basis using all demodulation symbols in a received frame of a forward user channel. (SIR) measuring unit, a symbol rate detecting unit for detecting symbol rate information provided at a predetermined position in a received frame of the forward user channel, a threshold value variable according to the detected frame symbol rate information, and the detected value And a controller for comparing the S-I-Al (SIR) to generate a corresponding forward power control command signal.

Description

Forward power control device and method in code division multiple access mobile communication system {APPARATUS AND METHOD FOR FORWARD POWER CONTROLLING IN CDMA MOBILE COMMUNICATION SYSTEM}

The present invention relates to a code division multiple access mobile communication system, and more particularly, to a forward power control apparatus and method provided in a receiving apparatus.

In general, power control in a code division multiple access (hereinafter referred to as CDMA) type mobile communication system can be classified into forward power control and reverse power control. . In this case, the forward power control allows a mobile station to maintain a constant signal interference ratio (hereinafter referred to as SIR) for a forward traffic channel received from a base station. In other words, forward power control improves the transmission power of a base station for a mobile station in a poor channel environment and lowers the transmission power of the base station for a mobile station in a good channel environment. This ensures stable data demodulation, and system-wide, forward power control can increase the capacity of each cell by avoiding wasting power on traffic channels to mobile stations.

On the other hand, the corner problem (Corner Problem) of the forward channel is a problem that the mobile station at the cell boundary or the mobile station at the back of the building is subjected to a lot of interference by the base stations other than the serving base station. In this case, the mobile station requires more receive power than the mobile station located close to the base station. Accordingly, the mobile station notifies the service base station of the channel state based on the error rate of the received frame, and the service base station adjusts the transmission power so that the mobile station maintains a predetermined threshold received power based on the channel state of the informed mobile station. In this case, the above-described forward power control may be closed loop power control.

The state measurement of the channel may be performed by measuring the ratio (SIR) of the strength of the signal received by the mobile station to the strength of the interference signal. The mobile station may also compare the measured SIR with a threshold that varies according to the frame error rate from the demodulator and notify the base station of the result. The threshold may vary in direct proportion to the frame error rate. Forward power control by a variable threshold corresponding to the frame error rate is referred to as outer-loop power control.

Meanwhile, in the CDMA-2000 wireless standard, a channel measurement method for forward power control measures a ratio of received power of a forward user channel and an intensity of interference from other cells, that is, SIR. The method measures the interference signal values for each path demodulated by a rake receiver provided to the mobile station, and measures the strength of the user channel received signal for each path to determine a ratio of the two signal strengths, that is, SIR and a predetermined threshold value. To compare.

The method of measuring the strength of the interference signal is proposed using a pilot channel, a method using a synchronization channel, and a method of measuring the strength of an approximate interference signal including orthogonal noise components. It is becoming.

The received strength measurement method for the forward user channel, which is currently proposed, is performed by measuring the size of power control command symbols transmitted from the base station to the mobile station for the reverse closed circuit power control. That is, in the related art, the mobile station only needs to determine and square the position and size of the power control command symbols transmitted for each power control group of the forward traffic channel signal. However, the conventional method used only part of the power control group for the measurement of the forward user channel. Therefore, the number of symbols used for the measurement of the forward user channel is insufficient to cause inaccurate forward channel measurement. For example, if only three to four power control command symbols of 36 symbols of one 1.25 msec power control group are used for forward user channel reception strength measurement, an incorrect value is measured in a poor channel environment such as a fading channel. Can be. This causes the mobile station to notify the base station of an incorrect forward power control command, which prevents the base station from performing the desired forward power control. That is, the base station may have a situation in which lower transmission power is lowered or higher transmission power is further increased due to the wrong forward power control command, thereby preventing efficient power usage. In particular, the use of an unnecessarily high transmission power by the above-mentioned causes an additional problem of reducing the total used cell capacity.

FIG. 1 illustrates an example of a configuration of obtaining an SIR value of a forward user channel using a reverse power control symbol in a conventional CDMA mobile communication system.

The finger 100 performs PN despreading and orthogonal despreading on the received signal, and outputs a demodulated symbol to a combiner through the despreading. On the other hand, the finger 100 is implemented in plurality in order to demodulate a symbol for a received signal for each different path. The combiner sums output values of fingers corresponding to each path, and outputs the summed value to the channel decoder.

The despreader 110 provided in the finger 100 multiplies the input I channel and the Q channel by the PN sequence output from the PN generator 160 to despread it. The multiplier 115 multiplies the output of the despreader 110 by the orthogonal code Wt for a traffic channel from an orthogonal code generator (not shown) to extract data of an orthogonal demodulated traffic channel. do. In addition, the symbol accumulator 120 accumulates and outputs the output of the multiplier 115 in symbol units.

The multiplier 140 multiplies the output of the despreader 110 by the orthogonal code Wo for the pilot channel generated from the orthogonal code generator to extract data of the pilot channel. In addition, the symbol accumulator 145 accumulates the output of the multiplier 140 in symbol units and performs an operation of accumulating the symbols.

The multiplier 125 takes a conjugate conjugate to the output from the symbol accumulator 145 and multiplies the output of the symbol accumulator 120. That is, the multiplier 125 compensates the phase component of the traffic channel data by multiplying the size of the pilot channel and the conjugate complex number of the phase component by the data of the traffic channel. The multiplier 125 outputs the demodulated symbol to a combiner (not shown).

Meanwhile, the power control symbol squarer 130 measures power values of reverse power control command symbols inserted at predetermined positions of orthogonal demodulated channel data output from the symbol accumulator 120. The symbol accumulator 135 accumulates the output of the power control symbol squarer 130 in symbol units and outputs the received signal strength of the forward user channel. In this case, the cumulative interval is inserted with two symbols for each power control group, and one frame including a total of 32 reverse power control command symbols may be defined as a corresponding cumulative interval.

The interference signal measuring unit 150 inputs the output of the despreader 110 and measures the interference signal strength. The divider 155 divides the received signal strength of the forward user channel by the strength of the interference signal to obtain an SIR, and outputs the SIR to a forward power controller (not shown). The forward power controller adds each SIR from a plurality of fingers to measure the SIR sum of the signals received in all paths, and determines a forward power control command to be provided to the base station according to a frame error rate of a channel decoder (not shown). It plays a role.

Referring to the description of FIG. 1, it can be seen that the conventional method of obtaining the reception strength of the forward user channel is to square the reverse power control command symbols transmitted for each power control group of the forward traffic channel signal.

On the other hand, in order to solve the problem of the conventional method of using only a portion of the power control group for the measurement of the forward user channel, a method of using all the symbols of the received forward user channel for the measurement has been sought. However, in order to measure the forward user channel using all the symbols, the fact that the received user data has a symbol rate of the received frame varies every 20 ms according to the user's voice activity. That is, the transmission power per symbol of each data frame is changed by the repetition of the transmitting end. For example, the power per symbol of the frame rate of 4800bps is half that of 9600bps. In addition, the power per symbol of the frame rate of 2400bps is one quarter compared to the case of 9600bps. As a result, in order to measure the forward user channel using all the symbols, the SIR value, which is the basis of the channel measurement, and the threshold value without considering the symbol rate of each received frame cannot be compared with each other.

Of course, the symbol rate of the received frame may be detected by the channel decoding operation after symbol demodulation, but at the point of time when the symbol rate of the received frame is detected, the fading channel environment through which the received signal has already been changed is impossible to measure the channel. Done. Therefore, if each data frame format is provided with information about the symbol rate of the frame, and the power measuring device of the receiving side can recognize the information about the symbol rate of the received frame, all symbols of the received frame are used to correct the information. Forward user channel measurements will be possible. In this case, the apparatus for measuring power on the receiving side considers the transmission power per symbol that varies according to the symbol rate of the received frame by comparing the SIR value for each received frame with a threshold value that changes in response to the recognized symbol rate information.

Accordingly, an object of the present invention is to provide a data frame structure in which symbol rate information is provided so that the strength of a forward user channel received signal is accurately measured in a code division multiple access mobile communication system.

Another object of the present invention is to provide an apparatus and method for performing forward power control by measuring SIR of a forward user channel using all symbols in a received frame in a code division multiple access mobile communication system.

Another object of the present invention is to measure the SIR of a forward user channel using all symbols in a received frame in a code division multiple access mobile communication system, and measure the threshold and the measured SIR corresponding to the symbol rate of the received frame. In comparison, an apparatus and method for performing accurate forward power control are provided.

In order to achieve the above object, the present invention provides a method for measuring a S-eye (SIR) on a frame-by-frame basis using a demodulation symbol in a received frame of a forward user channel. An S-IR measuring unit, a symbol rate detecting unit for detecting symbol rate information provided at a predetermined position in a received frame of the forward user channel, and a threshold variable according to the detected frame symbol rate information And a controller for comparing the detected value with the detected S-eye (SIR) to generate a corresponding forward power control command signal.

In addition, the present invention provides a method for forward power control in a code division multiple access mobile communication system, the method comprising: measuring S-I-Al (SIR) on a frame-by-frame basis using all demodulation symbols in a received frame of a forward user channel; Detecting symbol rate information provided at a predetermined position in a received frame of a user channel; comparing the detected S-I-AL (SIR) with a threshold value that is variable according to the detected frame symbol rate information; Generating a forward power control command signal.

1 is a diagram illustrating a configuration for measuring an SIR value of a forward user channel in a conventional CDMA mobile communication system.

2 is a diagram illustrating a configuration of a forward user data frame according to an embodiment of the present invention.

3 is a diagram illustrating a configuration of a forward power control apparatus in a CDMA mobile communication system according to an embodiment of the present invention.

4 is a diagram showing a detailed configuration of the SIR measurement unit shown in FIG.

5 is a diagram showing an output configuration of a finger according to an embodiment of the present invention.

6 illustrates a control flow for forward power control in a CDMA mobile communication system according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In the following description of the present invention, detailed descriptions of related well-known functions or configurations are omitted when it is determined that the detailed description may unnecessarily obscure the subject matter of the present invention.

In the CDMA mobile communication system, the present invention performs accurate forward user channel measurement using all symbols of the received frame. In this case, the present invention considers that the symbol rate of the forward user channel frame is variable. According to the present invention, frame symbol rate information is added to a format of a user channel frame. The forward power control apparatus recognizes the information and generates a corresponding forward power control command by comparing the measured SIR value with a threshold value that varies according to the frame symbol rate information.

2 illustrates a configuration of a forward user data frame according to an embodiment of the present invention.

As shown, the forward user data frame has a period of 20 ms and consists of 16 power control groups. Each power control group also consists of 18 symbols. The symbol rate information of the frame according to the present invention may be included in any one of the power control groups. 2 assumes that the frame symbol rate information symbol is included in the first power control group. That is, the power control group is composed of power control command symbols for reverse power control, user data symbols, and frame symbol rate information symbols newly added according to the present invention.

The frame symbol rate information symbols may be provided at positions of the last 6 symbols of 18 symbols of a predetermined power control group in a received frame so as not to overlap with power control command symbols for reverse power control. The number of frame symbol rate information symbols may be plural. For example, it can be two or four.

The frame symbol rate information symbol is inserted after puncturing the symbol at a predetermined position within each frame after the channel encoding operation is completed on the transmitting side. The transmission power of the frame symbol rate information symbol may be larger than that of other symbols. For example, 0dB, 3dB, 6dB, etc. can be selected. Because of this, the frame symbol rate information will be stably demodulated after passing through the fading channel.

On the other hand, the frame symbol rate information symbol does not need to be transmitted for every power control group, as compared with the power control command symbol being transmitted every power control group of a frame. Therefore, the effect of the frame symbol rate information symbol is negligible compared to the effect of the power control command symbol on decoding at the receiving side. The reason why the power control command symbol and the frame symbol rate information symbols affect the decoding is to extract the power control command symbol and the frame symbol rate information symbols before decoding and insert a predetermined symbol in place of the extracted symbol. do. In this case, the symbols to be inserted instead are symbols that are different from the data symbols, so that an error occurs in decoding. In addition, as the deinterleaving is performed on the received symbols before decoding, the influence of the power control command symbol and the frame symbol rate information symbols becomes smaller. The reason is that the frame symbol rate information symbols are provided as a continuous symbol at the reception, but through deinterleaving, the continuous symbol is spread over the entire frame. The same applies to the power control command symbol. In general, it will be obvious that an error occurs in symbols that are separated from each other, and thus has less effect than an error occurs in consecutive symbols.

The power control apparatus to be described later recognizes symbol rate information of a predetermined position in a symbol demodulated reception frame and varies a threshold value compared with an SIR value for each received frame according to the recognized information.

3 is a diagram illustrating a configuration of a forward power control apparatus according to an embodiment of the present invention in a CDMA mobile communication system.

Referring to FIG. 3, the PN despreader 300 provided in the receiver performs PN despreading by multiplying the received signal by a mobile station generated PN sequence. The first path traffic orthogonal despreader 311 to the Nth path traffic orthogonal despreader 3N1 respectively multiply the received signal PN despread by the orthogonal code for the traffic channel to perform orthogonal despreading.

Each of the first path channel estimator 313 to the Nth path channel estimator 3N3 detects the magnitude and phase of a pilot signal with respect to the PN despread signal. The multipliers 315 to 3N5 each take a conjugate complex number of the magnitude and phase of the pilot signal detected for each path. The multipliers 315 to 3N5 multiply the received signals of the user channel orthogonally despread for each path by the conjugate complex number of the magnitude and phase of the pilot signal to perform phase compensation. The multipliers 315 to 3N5 output the demodulated symbols (the first path demodulation symbol 319 to the Nth path demodulation symbol 3N9) for each path.

The first path interference signal measuring device 317 to the Nth path interference signal measuring device 3N7 measure noise components of the received signals for each PN despread path, respectively, and thus the first path interference signal strengths 310 to Nth path interference. The signal strength 3N0 is output. The interference signal measuring instruments 317 to 3N7 may use a pilot channel or a synchronization channel. In addition, the interference signal measuring devices 317 to 3N7 may measure the strength of the approximate interference signal including even orthogonal noise components.

The SIR measuring unit 321 inputs first path demodulation symbols 319 to N-th path demodulation symbols 3N9. The SIR measuring unit 321 measures the received strength of each demodulation symbol in units of frames. That is, the SIR measuring unit 321 squares all the symbols in the corresponding frame to obtain the received power intensities for each path. In addition, the SIR measurement unit 321 obtains SIR values for each path by dividing the received strengths of the frame units obtained for each path by the first path interference signal strength 310 to the Nth path interference signal strength 3N0. The SIR measuring unit 321 adds SIR values for respective paths, calculates an average of the result values, and outputs the SIR 327.

The symbol rate detection unit 323 of the forward power control device 320 receives at least one path demodulation symbol among demodulation symbols from the first path demodulation symbol 319 to the Nth path demodulation symbol 3N9 as an input. do. The symbol rate detecting unit 323 detects a symbol rate of the corresponding frame from the received demodulation symbol. In the format of a user data frame according to the present invention, information on a symbol rate is provided at a predetermined position. The format of the user data frame may be shown in FIG.

The controller 325 inputs the SIR 327 and the symbol rate 329 described above. The controller 325 has a threshold that varies by symbol rate. For example, if the threshold of the symbol rate 9600bps is '1', the threshold of the symbol rate 4800bps may be '1/2'. In addition, the threshold of the symbol rate 2400bps may be '1/4'. The controller 325 varies the threshold according to the symbol rate 329 and compares the SIR 327 with the variable threshold to generate a forward power control command 331. For example, the controller 325 may generate a forward power control command 331 corresponding to a down when the SIR 327 is greater than a threshold variable according to the symbol rate, and the SIR 327 If it is smaller than the threshold value that varies according to the symbol rate, it is possible to generate a forward power control command 331 corresponding to Up. The controller 325 may input frame error rate information 333 from the channel decoding unit (not shown) to perform outer loop power control.

4 illustrates a configuration of the SIR measuring unit 321 according to an embodiment of the present invention. Hereinafter, a description will be given with reference to FIG. 3.

Referring to FIG. 4, the squarers 411 to 4N1 input first path demodulation symbols 319 to N-th path demodulation symbols 3N9, respectively, and receive all symbols in the frame for each received frame. Calculate the received power by square. The divider 413 through the divider 4N3 divide the received strengths of the frame units, which are obtained for each path, into the first path interference signal strengths 310 and the Nth path interference signal strengths 3N0, respectively. The values (first path SIR 415 to N-th path SIR 4N5) are output. The averager 410 adds the first path SIR 415 to the N-th path SIR 4N5, calculates an average thereof, and outputs the SIR 327. In FIG. 4, the configuration of the squarer 411 to the squarer 4N1 and the configuration of the divider 413 to the divider 4N3 may be provided in the path-specific fingers.

5 is a view showing an output configuration of a finger according to an embodiment of the present invention. On the other hand, according to an embodiment of the present invention, the configuration of measuring the received signal strength of the forward user channel for each path and the configuration for obtaining the SIR is omitted in the finger of FIG. In addition, the demodulation symbol and the interference signal strength output from the finger for each path are applied to the forward power controller 320 and the combiner (not shown) of FIG. 3.

N (1 n N: where n is a positive integer) The despreader 510 provided in the path finger multiplies the received I channel signal and the received Q channel signal by a PN_I sequence and a PN_Q sequence from a PN generator (not shown) to despread it. Do this. The multiplier 515 extracts the data of the orthogonal demodulated traffic channel by multiplying the despread I channel by the orthogonal code Wt for the traffic channel which is a user data channel from an orthogonal code generator (not shown). The multiplier 520 also multiplies the despread Q channel by the orthogonal code Wt for the traffic channel from the orthogonal code generator to extract data of the orthogonal demodulated traffic channel.

The symbol accumulator 535 and the symbol accumulator 540 accumulate orthogonal demodulated I channel data and Q channel data in symbol units, respectively. The pilot filter 525 and the pilot filter 530 extract data of I and Q pilot channels with respect to the output of the despreader 510, respectively. The phase compensator 545 inputs the outputs of the symbol accumulator 535, the symbol accumulator 540, the pilot filter 525, and the pilot filter 530, and outputs phase components of demodulated symbols of the I and Q channels. To compensate. The buffer 550 and the buffer 555 output the nth path I demodulation symbol 570 and the nth path Q demodulation symbol 580, respectively. Here, the n-th path I demodulation symbol 570 and the n-th path Q demodulation symbol 580 are demodulated in any one path from the first path demodulation symbol 319 to the N-th path demodulation symbol 3N9 of FIG. 3. Corresponds to the symbol. The nth path I demodulation symbol 570 and the nth path Q demodulation symbol 580 are output to a forward power control device 320 and a combiner according to the present invention. In addition, the interference signal measuring unit 560 measures the noise component of the PN despread signal and outputs the nth path interference signal strength 590. The nth path interference signal strength 590 corresponds to the interference signal strength of any one path among the first path interference signal strength 310 to the Nth path interference signal strength 3N0 of FIG. 3. The n-th path interference signal strength 590 is output to the forward power control device 320 according to the present invention.

6 is a flowchart illustrating a forward power control method according to an embodiment of the present invention in a CDMA mobile communication system.

Referring to FIG. 6, the SIR measuring unit 321 illustrated in FIG. 3 inputs demodulation symbols 319 to 3N9 and interference signal strengths 310 to 3N0 for each path in step 610, and forward user channel. The SIR of each frame is measured using all the symbols in the received frame. In this case, step 610 is to obtain the received power strength for each path of the forward user channel by squaring all demodulation symbols 319 to 3N9 in the received frames for each path, and the received power strengths of the forward user channel for each path. The SIR of each path may be obtained by dividing the interference signal strengths of each path, and the SIR may be calculated by adding the SIR of each path and taking the average thereof. Obtaining the received power strength for each path of the forward user channel is performed by the squarers 411 to 4N1 of FIG. 4, and obtaining the SIR for each path is performed by the dividers 413 to 4N3 of FIG. 4. do. In addition, the step of calculating the SIR is performed by the averager 410 of FIG.

In operation 620, the symbol rate detecting unit 323 shown in FIG. 3 inputs demodulation symbols for each path, and detects symbol rate information of the frame at a predetermined position in a frame of each forward user channel. Determine. In this case, the frame symbol rate information may be composed of frame symbol rate information symbols in any one of the predetermined power control groups of the frame. The frame symbol rate information symbols may be provided at positions not overlapping with power control symbols for reverse power control. In addition, the frame symbol rate information symbols may be provided by the puncturing operation of the transmitter.

The controller 325 illustrated in FIG. 3 varies the threshold according to the detected frame symbol data rate in step 630. At this time, for example, if the threshold of the symbol rate of 9600bps is '1', the threshold of the symbol rate of 4800bps may be '1/2'. In addition, the threshold of the symbol rate 2400bps may be '1/4'.

In operation 640, the controller 325 compares the measured SIR of the frame unit with the variable threshold to generate a corresponding forward power control command. For example, the controller 325 may generate a forward power control command 331 corresponding to a down when the SIR is greater than a threshold variable according to the symbol rate, and the SIR may be applied to the symbol rate. Accordingly, if the threshold value is smaller than the threshold value, the forward power control command 331 corresponding to the up may be generated. Also, the controller 325 may input frame error rate information 333 from the channel decoding unit to perform outer loop power control.

As described above, in the CDMA mobile communication system, the present invention performs accurate forward user channel measurement using all symbols of the received frame. In this case, the present invention considers that the symbol rate of the forward user channel frame is variable. According to the present invention, frame symbol rate information is added to a format of a user channel frame. The forward power control apparatus recognizes the information and generates a corresponding forward power control command by comparing the measured SIR value with a threshold value that varies according to the frame symbol rate information.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims of the present invention.

As described above, the present invention enables the CDMA mobile communication system to perform accurate forward user channel measurement using all symbols of the received frame, so that the base station needs to reduce the transmission power unnecessarily to maintain the SNR required by the mobile station. You can prevent wasting. As a result, the present invention not only prevents unnecessary waste of forward transmission power, but also has an advantage of reducing unnecessary total cell capacity reduction.

Claims (18)

A forward power control apparatus in a code division multiple access mobile communication system, An S-IR measuring unit for receiving all demodulation symbols in a received frame of the forward user channel and measuring S-i-AL (SIR) on a frame basis; A symbol rate detecting unit detecting symbol rate information inserted at a predetermined position in a received frame of the forward user channel; And a controller for varying a threshold value according to the detected symbol rate information and generating a forward power control command by comparing the variable threshold with the measured S-I-AL (SIR). A forward power control device in a code division multiple access mobile communication system. The method of claim 1, wherein the symbol rate information, The forward power control apparatus in a code division multiple access mobile communication system, which is provided in any one of the power control groups of the received frame and is recorded at a position not overlapping with the positions of the reverse power control symbols. The method of claim 1, wherein the controller, If the measured S-eye (SIR) is greater than the variable threshold, a forward power control command corresponding to Down is generated, and the measured S-eye (SIR) is the variable threshold. The forward power control device in a code division multiple access mobile communication system, characterized in that for generating a forward power control command corresponding to Up when the value is smaller than the value. The method of claim 1, wherein the threshold value, The apparatus for forward power control in a code division multiple access mobile communication system, characterized in that it is changed in proportion to the symbol rate according to the detected symbol rate information. A forward power control apparatus in a code division multiple access mobile communication system, S-I (SIR) measuring unit for receiving the demodulation symbols of the different paths and the interference signal strength of the different paths to measure the S-I-Al (SIR) in units of frames, A symbol rate detecting unit configured to receive demodulation symbols of at least one path among the demodulation symbols of the different paths and detect symbol rate information from demodulation symbols of a set position; And a controller for varying a threshold value according to the detected symbol rate information and generating a forward power control command by comparing the variable threshold with the measured S-I-AL (SIR). A forward power control device in a code division multiple access mobile communication system. The method of claim 5, wherein the S-eye (SIR) measuring unit, Squares for measuring the received strength of the demodulation symbols for different paths, Dividers for measuring S-eyes (SIRs) in units of frames per path by the interference signal strength of the same path as the reception strength from the squarers; Forward power control in a code division multiple access mobile communication system comprising an averaging unit for measuring a final S-I (SIR) by calculating an average value of S-Is (SIRs) from the dividers. Device. The method of claim 5, wherein the symbol rate information, The forward power control apparatus in a code division multiple access mobile communication system, which is provided in any one of the power control groups of the received frame and is recorded at a position not overlapping with the positions of the reverse power control symbols. The method of claim 5, wherein the controller, If the measured S-eye (SIR) is greater than the variable threshold, a forward power control command corresponding to Down is generated, and the measured S-eye (SIR) is the variable threshold. The forward power control device in a code division multiple access mobile communication system, characterized in that for generating a forward power control command corresponding to Up when the value is smaller than the value. The method of claim 5, wherein the threshold value, The apparatus for forward power control in a code division multiple access mobile communication system, characterized in that it is changed in proportion to the symbol rate according to the detected symbol rate information. A forward power control method in a code division multiple access mobile communication system, Receiving all demodulation symbols in a received frame of a forward user channel and measuring S-I-Al (SIR) on a frame-by-frame basis; Detecting symbol rate information recorded at a predetermined position within a received frame of the forward user channel; And varying a threshold value according to the detected symbol rate information, and generating a forward power control command by comparing the variable threshold with the measured S-I-AL (SIR). A forward power control method in code division multiple access mobile communication system. The method of claim 10, wherein the symbol rate information, A forward power control method in a code division multiple access mobile communication system, characterized in that it is provided in any one of the power control groups of the received frame, and is recorded in a position that does not overlap with the position of the reverse power control symbols. The method of claim 10, wherein generating the forward power control command comprises: If the measured S-eye (SIR) is greater than the variable threshold, a forward power control command corresponding to Down is generated, and the measured S-eye (SIR) is the variable threshold. The forward power control method in a code division multiple access mobile communication system characterized by generating a forward power control command corresponding to Up if smaller than a value. The method of claim 10, wherein the threshold value, The forward power control method in a code division multiple access mobile communication system characterized in that it is variable in proportion to the symbol rate according to the detected symbol rate information. A forward power control method in a code division multiple access mobile communication system, A process of measuring S-I-Al (SIR) in units of frames by receiving demodulation symbols of different paths and interference signal strengths of different paths; Receiving symbol demodulation symbols of at least one path among the demodulation symbols of different paths and detecting symbol rate information from demodulation symbols of a set position; And varying a threshold value according to the detected symbol rate information, and generating a forward power control command by comparing the variable threshold value with the measured S-I-AL (SIR). A forward power control method in code division multiple access mobile communication system. The method of claim 14, wherein the measuring of the S-I-Al (SIR) comprises: Measuring the reception strength of the demodulation symbols for different paths; Measuring an S-I-R (SIR) in units of frames per path by the interference signal strength of the same path as the reception strength from the squarers; The forward power control method in a code division multiple access mobile communication system comprising the step of measuring the final S-I (SIR) by calculating the average value of the measured S-I-Al (SIR). The method of claim 14, wherein the symbol rate information, A power control method of a code division multiple access mobile communication system, characterized in that it is provided in any one of the power control group of the received frame, and is recorded in a position not overlapping with the position of the reverse power control symbols. The method of claim 14, wherein generating the forward power control command comprises: If the measured S-eye (SIR) is greater than the variable threshold, a forward power control command corresponding to Down is generated, and the measured S-eye (SIR) is the variable threshold. The forward power control method in a code division multiple access mobile communication system characterized by generating a forward power control command corresponding to Up if smaller than a value. The method of claim 14, wherein the threshold value, The forward power control method in a code division multiple access mobile communication system characterized in that it is variable in proportion to the symbol rate according to the detected symbol rate information.