KR0183001B1 - Method of estimating eb/no in ds/cdma with a pilot signal - Google Patents

Abstract

The present invention synchronizes the pseudo noise (pn code: hereinafter referred to as pn code) used in the code division communication method and obtains the received power of the signal. Then, the pn code which is not synchronized or the pn code Code is used to obtain a distortion power by using a correlation of a pilot signal to obtain a mutual ratio of the two powers to obtain a noise power in a reverse link of a direct spreading code division multiple access The present invention relates to a method and apparatus for determining energy per bit (E _b / N _o ) for a density, and it is possible to quickly determine the quality of a reverse link on-line without significantly increasing the complexity of the hardware configuration, The power of a signal transmitted from the mobile station to the base station can be quickly controlled.

Description

Method and apparatus for obtaining energy per bit (Eb / No) with respect to noise power density in a DS / CDMA system with a pilot signal

The present invention relates to a method and apparatus for determining energy per bit (E _b / N _o ) for a noise power density in a direct spread code division multiple access (DS / CDMA) communication scheme with pilot signals, More specifically, after synchronizing the pseudo noise (pn code: hereinafter referred to as pn code) used in the code division communication method, the received power of the signal is obtained, and then the pn code or the pn code the power of the received signal using the pn code is despread to obtain the distortion power using the correlation of the pilot signals to determine the mutual ratio of the two powers so that the noise power in the reverse link of the direct spreading code division multiple access (E _b / N _o ) per unit of energy density and a device therefor.

The basic principle of the spread spectrum communication method is to spread the original signal band so as to have a transmission bandwidth wider than the bandwidth (bandwidth: BW) of the original signal to be transmitted, By using the principle to sufficiently broaden the bandwidth of the signal, communication is possible even at a very low signal-to-noise ratio (SNR).

The communication scheme using the spread spectrum technique is divided into a direct sequence (DS), a frequency hopping (FH), a time hopping (TH), a chirp modulation and a hybrid ).

Although the CDMA (DS / CDMA) method using dual direct spreading has various advantages, there are many technical disputes, among which there is a lot of controversy about the power control method of the mobile station. The power control of the mobile station is a control requirement that is necessary to solve the near-far interference problem that occurs because all the mobile stations in the cell use the same frequency band. The power control of the base station used in the DS / CDMA communication scheme The system must know the state of the signal received from each mobile station on the reverse link to precisely control the transmit power of the mobile station as described above.

The following conventional power control methods have been proposed and used to determine the state of a received signal.

As a first method, a received signal strength indicator (RSSI) indicating the strength of a received signal is measured to estimate the state of the received signal. As a second method, a bit error rate (BER) is measured In this method, an off-line method of checking a BER state by periodically transmitting a specific pattern to a packet of a signal to be transmitted, and a method of extracting a BER when demodulating an error correction code Or a method using CRC or the like. A third method is a method of directly predicting the state of a received signal from a demodulated signal or a clock.

However, among the above-mentioned conventional methods, the first method has a problem that it is difficult to apply to the reverse link because a plurality of channels share the same frequency in the DS / CDMA communication method. The second method has a problem of transmitting unnecessary data While the third method does not cause unnecessary transmission or delay of data, but it is difficult to implement due to the complexity of the calculation and the signal processing speed is lowered .

Therefore, the present invention has been made in order to solve the above-mentioned problems, and it is possible to measure in a short time without complicated calculation to detect the state of a signal, and a system of the DS / (E _b / N _o ) for a noise power density in a direct spread code division multiple access (DS / CDMA) communication scheme having a pilot signal using only necessary signals, It is another object of the present invention to provide a method and apparatus for obtaining a received power and a distorted power by obtaining an average value of received power for a predetermined period of time to obtain a bit for noise power density that improves the accuracy of the ratio of the received power to the distorted power is to provide the method for obtaining the energy per (E _b / N _o), still another object of the present invention can use the sum of the received power calculated for a predetermined time Is to provide a method for obtaining an energy (E _b / N _o) per bit to noise power density capable of measuring the quality of the state, is still another object of the present invention, synchronized pn code and the phase of the other pn code (E _b / N _o ) with respect to the noise power density, which improves the accuracy of the measured value of the distortion power by doubly finding and averaging the distortion power by despreading the same signal, respectively, Another purpose of the present invention is to improve the accuracy of the measured value of the distorted power by despreading different pn codes different from the synchronized pn code to the same signal to double the distortion power, (E _b / N _o) the method is to provide a seek, a further object of the present invention, in the distortion power in the wanted job rapid measurement possible to estimate to the nearest It is to provide a method for obtaining an energy (E _b / N _o) per bit to the power density, yet another object of the present invention, to detect the state of the signal does not involve complex calculations measurement is possible in a short period of time, and Also, the energy per bit (E) for the noise power density in a direct spread code division multiple access (DS / CDMA) communication scheme having a pilot signal using only the signals that the DS / _b / N _o) it is to provide a device to obtain a further object of the present invention, by each of the despread in the same synchronization the pn code and the phase is different pn code signal by averaging calculated distortion power with dual distortion power It is another object of the present invention to provide an apparatus for determining energy per bit (E _b / N _o ) for a noise power density that improves the accuracy of a measured value, (E _b / N _o ) with respect to a noise power density that improves the accuracy of the measured value of the distortion power by despreading different pn codes to the same signal to obtain a double distortion power by averaging the distortion power. It is still another object of the present invention to provide an apparatus and method for estimating a quality of a reception state by accumulating received power for a predetermined period and using the accumulated value to obtain energy per bit (E _b / N _o ) .

[Title of the Invention]

Method and apparatus for obtaining energy per bit (Eb / No) with respect to noise power density in a DS / CDMA system with a pilot signal

BRIEF DESCRIPTION OF THE DRAWINGS Fig.

1 shows a structure of a transmitting part of a mobile station of a reverse link,

2 shows the synchronization part of the pn code of the base station of the reverse link,

FIG. 3 is a block diagram of a method for obtaining the energy per bit (E _b / N _o ) for the noise power density according to the present invention and an embodiment implementing the apparatus,

FIG. 4 is a block diagram of a method for obtaining an approximate value of the distortion power according to the present invention and another embodiment implementing the apparatus,

FIG. 5 is a simulation model for verifying the effect of the present invention,

6 shows the variation of the estimated energy per bit (E _b / N _o ) with respect to the noise power density versus the change of the white noise when there is no interference of the other channel on the reverse link,

7 shows a change in the estimated value of Eb / No when another user is using another channel,

FIG. 8 shows a change in the estimated value of Eb / No when another user uses another channel and white noise also exists,

FIG. 9 shows the mean value and standard deviation of the estimated Eb / No value obtained when the estimated time of Eb / No is changed.

DESCRIPTION OF THE REFERENCE NUMERALS

A1-An: adder M1-Mn: multiplier

10-13: low pass filter 15, 16: D / A converter

20, 21: Low pass filter 30, 31: A / D converter

40, 41: decimator 50-55: integrator

60-65: Squared 70-72: Square root

80: Synchronization acquisition and tracking logic 90: pn code generator

100: demodulation / conversion unit 101, 102: low-pass filter

103, 104: A / D converter 110:

120: reception power calculation unit 121-122: integrator

123,124: squared machine 125: square root machine

130: Synchronization determination / control unit 131: Synchronization determination / controller

140: first distortion signal generator 150: second distortion signal generator

160: First Distortion Power Operator 161, 162: Integrator

163, 164: Squaring unit 165:

166: Square root multiplier 170: Second distortion power computing unit

171, 172: integrator 173, 174: squarer

175: Totalizer 176: Square root

180: power ratio calculating unit 181:

182, 183: integrator 184: non-operator

200: approximate power calculator 201: comparator

202: selector 203, 204: multiplier

205: summer 301: transmission block

302: Receiving block

According to another aspect of the present invention, there is provided a method for determining energy per bit (E _b / N _o ) of a noise power density according to the present invention includes: establishing synchronization of a reverse link using a pilot signal; Obtaining received power from an input signal; Obtaining a distortion power of an input signal by despreading an input signal with a pn code having no correlation with a synchronized pn code; And obtaining a ratio of the received power to the distortion power; (E _b / N _o ) of the noise power density according to the present invention is characterized in that the step of obtaining the received power and the step of obtaining the distortion power are steps of Repeatedly obtaining; And summing the obtained power; And the ratio of the received power to the distortion power is obtained by obtaining a ratio of the summed power, and the ratio of the energy per bit E _b / N to the noise power density according to the present invention _o) the method steps to obtain the distortion power of obtaining is, to simultaneously despread the in phase than the synchronous pn code delayed pn code and the phase advanced pn code to the input signal two distortion power of the input signal (P _a, P _B) ; And obtaining a distortion power corresponding to an average of the two distortion powers (P _A , P _B ); (E _b / N _o ) of the noise power density according to the present invention, the step of obtaining the distortion power may be a step of calculating a distortion power of the pn code having a code different from the synchronized pn code Simultaneously despreading the input signal with the sign to obtain two distortion powers (P _A , P _B ) of the input signal; And obtaining a distortion power corresponding to an average of the two distortion powers (P _A , P _B ); (E _b / N _o ) with respect to the noise power density according to the present invention, the step of obtaining the distortion power may be a step of obtaining an I phase (in-phase) signal comparing the size of the power (P _I) and a Q phase (Quadrature phase) power (P _Q) of the signal; And obtaining an approximate value of the received distortion power by multiplying a power of a smaller one of the two powers (P _I , P _Q ) by a constant of a predetermined magnitude and adding it to a larger power; And the constant multiplied in the above is another feature that limits the size to a range of 1/4 and 1/2 in order to obtain a more accurate estimation value.

According to another aspect of the present invention, there is provided an apparatus for obtaining energy per bit (E _b / N _o ) of a noise power density according to the present invention includes: a first local code generating unit for generating a first code; Demodulating and converting means for demodulating the received radio signal into an I-phase signal and a Q-phase signal, respectively, and converting the demodulated signal into a digital signal; Despreading means for despreading I phase and Q phase signals output from the demodulation and conversion means using a Walsh code and a first pn code; Receiving power calculation means for calculating a received power by using the powers of the despread I-phase and Q-phase signals; Wherein the first pn code is synchronized with the local first code by comparing the power obtained by the reception power calculation means with a reference value, and when the synchronization is not established, the phase of the first pn code controlled by the first pn code generation means is changed A synchronization determining and controlling means Second pn code generation means for generating a second pn code having no correlation with the first pn code synchronized by the synchronization determination and control means; First distortion signal generation means for generating a distortion signal by despreading I phase and Q phase signals output from the demodulation and conversion means using the second pn code; Distortion power calculating means for obtaining distortion power using the distorted signal; And power ratio calculation means for calculating a ratio of the received power calculated by the received power calculation means to the calculated distortion power; (E _b / N _o ) with respect to the noise power density according to the present invention is characterized in that the apparatus for obtaining energy per bit (E _b / N _o ) Third pn code generating means for generating the third pn code; And second distortion signal generation means for generating a distortion signal by despreading the I phase and Q phase signals output from the demodulation and conversion means using the third pn code; Wherein the distortion power calculation means calculates an average power of the power of the distortion signal output from the first distortion signal generation means and the power of the distortion signal output from the second distortion signal generation means, The second pn code generating means generates another second pn code whose phase is delayed with respect to the synchronized first pn code. The second pn code generating means generates energy (E _b / N _o ) per bit with respect to the noise power density according to the present invention A third pn code generating means for generating a third pn code having a code different from the first pn code synchronized by the synchronization determination and control means; And second distortion signal generation means for generating a distortion signal by despreading the I phase and Q phase signals output from the demodulation and conversion means using the third pn code; Wherein the distortion power calculation means calculates an average power of the power of the distortion signal output from the first distortion signal generation means and the power of the distortion signal output from the second distortion signal generation means, The second pn code generating means has another feature in generating a second pn code having a code different from the synchronized first pn code, and the energy per bit (E _b / N _o ), The power ratio calculating means includes: integrating means for accumulating the value of the received power; And comparison means for comparing the accumulated value of the received power with certain reference values; The present invention is further characterized in that it is constituted by further comprising:

In the method of obtaining the energy per bit (E _b / N _o ) for the noise power density in the direct spread code division multiple access (DS / CDMA) communication method comprising the steps as described above, Synchronous with the pn code of the pilot channel of the link and simultaneously calculating the total power of the demodulated signal and the distorted signal despread by the pn code synchronized with the received signal and obtaining the total power, A pn code having a code different from or in phase with a synchronized pn code is despread with respect to a received signal to calculate a distortion power of the signal, The received power is obtained. (E _b / N _o ) with respect to the noise power density is calculated by performing an appropriate calculation (the operation of subtracting 1 from the power ratio and multiplying the subtracted value by the noise bandwidth ratio with respect to the data rate) Can be obtained.

In the above method, in order to increase the accuracy of the measured power, a step of obtaining the ratio of the received power to the distorted power by obtaining a power value by repeating a predetermined number of times or more instead of the power at the specific time in each power obtaining step In the step of calculating the power value of the despread signal, it is also possible to improve the speed of obtaining the power value instead of estimating the approximate value of the power value instead of calculating the power value by correct calculation .

In the apparatus for obtaining the energy per bit (E _b / N _o ) of the noise power density in the direct spread code division multiple access (DS / CDMA) communication system configured as described above, the demodulation and conversion means converts the received signal into I Phase signal and a Q-phase signal, and then converts the demodulated signal into digital data, and outputs a Walsh code for the two digital signals (S _P , S _Q ) and a Walsh code And the reception power calculating means adds and squares each of the despread signals, sums the two signals, obtains a square root, inputs the sum to the power ratio calculating means, Value or a square root value to the synchronous determination and control means. The synchronization determination and control means determines that synchronization is not established when the input sum power value is compared with a predetermined reference value and controls the first pn code generation means to change the phase of the first pn code, , It is determined that the synchronization has been established and the fact that the synchronization has been established is notified to the power ratio calculation means. On the other hand, the first distortion signal generation means despreads the two digital signals (S _P , S _Q ) using a second code which is not correlated with the first pn code output from the second pn code generation means, The distorted power calculation means inputs the distorted power value obtained by performing the same process as the received power calculation means with respect to the despread signal to the power ratio calculation means, The power ratio calculation means calculates the ratio of the two powers inputted when the synchronization determination and control means notifies the fact that the synchronization is established and obtains the ratio of the received power to the distortion power so as to calculate a proper calculation When the subtracting 1 and perform multiplying the noise band ratio for the data to the average value of the subtraction operation), energy per bit to noise power density (E _b / N _o) It is possible to get.

In addition to the first distortion signal generation means, the same second distortion signal generation means and distortion power calculation means are added in parallel, and a third pn code which is not correlated with the first pn code output from another third pn code generation means is Wherein the power ratio calculating means includes a power average means for calculating a distortion power by using the value of the distortion power by the first distortion signal generating means and the value of the distortion power by the second distortion signal generating means The second pn code and the third pn code may have a pn code different from the first pn code or be a pn code having the same code as the same code.

Hereinafter, an embodiment of a method and an apparatus for obtaining energy per bit (E _b / N _o ) for a noise power density in a direct spread code division multiple access (DS / CDMA) communication system having a pilot signal according to the present invention , A transmitter and a receiver of a reverse link will be described first and then described in detail with reference to the accompanying drawings.

FIG. 1 shows a structure of a transmitter of a reverse link mobile station using a pilot signal, and FIG. 2 shows a synchronization unit of a pn code of a base station of a reverse link.

First, the pilot signal of the mobile station is divided into an I phase and a Q phase by an unmodulated signal, multiplied by a hardamard code W _P in multipliers M 1 and M 2, and then allocated to two spread codes P _I and P _Q Multiplied by the multipliers M3 and M4, respectively, and then passed through the low-pass filters 10 and 11, respectively. On the other hand, a traffic channel having I phase and Q phase data (d _I , d _Q ) is multiplied by a Hardamard code (W _P ) of the pilot channel and an Orthogonal Hardamard code (W _T ) Are multiplied by spreading codes (P _I , P _Q ) and pass through the low-pass filters 12, 13, respectively. The signal of the low-pass filtered pilot channel and the signal of the traffic channel are added in the adders A1 and A2 for the I phase and the Q phase respectively and then transmitted to the multipliers M5 and M6 via the D / A converters 15 and 16 deohaejyeo the next adder (A3), each multiplied by a carrier wave _{(cosw c t, sinw c t} ) is transmitted.

The transmitted signal is synchronized by the pn code synchronizer of the reverse link of FIG. 2, and the process of synchronizing is as follows.

First, the signal (r (t)) received through the antenna to the I-phase and Q-phase signal by multiplying the rough and then converted to an intermediate frequency band being again demodulated carrier asynchronous cosw _c t _c t -sinw and for processing in the RF processing stage The corresponding carrier waves are removed, and the low-pass filters 20 and 21 are respectively converted into baseband signals. The baseband signal is oversampled to a plurality of samples per chip of a pn code by A / D converters 30 and 31 and then transmitted to decimators 40 and 41 . The decimators 40 and 41 select decimated punctual / early / late samples P, E and L using the HOLD signal obtained in the initial synchronization and synchronization tracking process, the pn code P _I and the pn code P _Q are multiplied by the punctual / early / late samples P, E and L and the correlation value is multiplied by the Hardamard code W _p , 55, squarers 60-65, and square root multipliers 70, 71, 72. Using the obtained values r _E , r _P , and r _L , the synchronization acquisition and tracking logic 80 performs synchronization acquisition and tracking and controls the pn code generator 90 that generates the pn code And a signal (Selection Control) for adjusting the decimation time of the decimators 40 and 41, as shown in FIG. Selected by the the HOLD signal and Selection Control signal decimated sample signal (E, P, L) and the pn code and the above-described process using repeated (P _I, P _Q) This process is the synchronization acquisition and tracking logic Until the synchronization acquisition and tracking logic 80 determines that synchronization is established or maintained, and the synchronous tracking process for continuously maintaining the synchronization even after the synchronization establishment, Is repeated.

When the synchronization of the pn code of the reverse link is established according to the above procedure, the per-bit energy (E _b / N _o ) of the noise power density according to the present invention is obtained. In the third method, FIG. 2 is a block diagram of an embodiment of the present invention, and will be described in detail below with reference to the block diagrams. FIG.

One embodiment of an apparatus for obtaining energy per bit (E _b / N _o ) with respect to a noise power density according to the present invention comprises demodulating a received signal r (t) into an I phase signal and a Q phase signal respectively A despreading unit 110 for despreading the digital signal using a Walsh code W _P and local pn codes P _I and P _Q , A synchronization decision / control unit 130 for receiving the received power and determining the synchronization and controlling the phase of the local pn code, a demodulator / demodulator 130 for demodulating the demodulated and converted digital signal, A first distortion signal generator 140 for generating a first distortion signal, a second distortion signal generator 150 for generating a second distortion signal, and a second distortion signal generator 150 for calculating a distortion power of the first distortion signal and the second distortion signal The first distortion power calculator 160 and the second distortion power calculator 170, and the first distortion power and second distortion power calculator 170, A power calculation unit 120 and a synchronization determination and control unit 130. The demodulation and conversion unit 100, the dynamic calculation unit 110, the reception power calculation unit 120, and the synchronization determination and control unit 130 Is input / output at the synchronous part of the pn code without any other configuration because it has the same configuration as the components except for the channel for processing the early sample signal and the delayed sample signal of the pn code synchronous part of the second diagram Only the signal can be used. The internal structure of the first distortion signal generator 140 and the second distortion signal generator 150 is substantially the same as the internal structure of the despreader 110. However, And there is no despreading process by the sign.

In one embodiment of the method for obtaining the energy per bit (E _b / N _o ) of the noise power density according to the present invention, the received power is calculated by using the following equation The pn code is synchronized and the reception power is obtained through the demodulation / conversion unit 100, the despreading unit 110, the reception power calculation unit 120, and the synchronization determination / control unit 130 , The distortion power for obtaining the energy per bit (E _b / N _o ) for the noise power density is obtained by the following theories and methods.

First, in order to obtain a relational expression of the ratio of the received power to the distortion power and the energy per bit (E _b / N _o ) to the noise power density, the power of the pilot signal is P _P , the power of the indirect signal is P _I , The power is P _N , the total received power is P _T , and the distortion power is P _D.

P _T and P _D are as follows.

P _T = P _P + P _I + P _N , and

P _D = P _I + P _N.

Here, when the ratio of P _T to P _D is obtained,

.

Since P _P is the pilot power, it can be assumed to be the carrier power (C) of the reverse link, and P _D is the power (N) of noise and interference

. therefore,

. On the other hand, E _b / N _o can be obtained from C / N, and their relationship is as follows.

Where W is the noise band and R _b is the data rate.

Therefore, when the total received power and the distorted power are obtained, the ratio of the carrier power C to the power N of noise and interference and the energy per bit E _b with respect to the noise power density N _o , When the mobile station obtains the above value from the signal received from the base station, the base station sets the closed circuit power control so that the received power reaching the base station is constant according to the value, The transmission power of the mobile station can be controlled.

A method for estimating the distortion power proposed by the present invention is as follows.

If the pn code of the signal received from each mobile station in the reverse link agrees with the phase of the pn code of the base station's local pn code generator for demodulating the signal from the mobile station (i.e., synchronization of the pn code is established) pilot signal power (P _P) and distortion power (P _D) is received, if the total signal received power (P _T), while conceivable as pn code synchronization has been established in which the power of interference and noise are together (P _I + P _N = P _D ). That is, if the synchronization of the pn code is not established in the spread spectrum communication method, the interference signal of the other channel can be considered as white noise, so that the distortion power can be obtained using the pn code that is not synchronized.

First, when the synchronization of the pn code is established through the demodulation / conversion unit 100, the despreading unit 110, the reception power calculation unit 120, and the synchronization determination / control unit 130 as described above, The unit 140 despreads the digital signal output from the demodulation and conversion unit 100 using a pn code whose phase is delayed by a predetermined chip or more from the synchronized pn code, The demodulator / demultiplexer 150 despreads the digital signal output from the demodulator / demultiplexer 100 using a pn code whose phase is more than a predetermined chip or more than the synchronized pn code. Preferably, the delay or progress of the pn code is spaced such that the phases are not influenced by the signal components due to the multipath. The distortion power of each of the first and second distortion signals despread in the first and second distortion power calculators 160 and 170 is obtained by the power ratio calculator 180 .

Meanwhile, the power ratio operator 180 obtains the average value of the power of the first distortion signal and the power of the second distortion signal through the averager 181, stores the average value in the integrator 182, 120 also stores in the integrator 183 the received power. If the average value of the received power and the distortion power over a predetermined number of times is added to the integrators 182 and 183, the sum of the two values is divided by the non-operator 184 to obtain the ratio of the received power to the distortion power And this value can be used as a base value for controlling the transmission power of the mobile station. It is also possible to measure and judge the quality of the received signal and the reception state by adjusting the integration time of the integrators 121 and 122 of the reception power calculator 120 and the sum of the reception power of the integrator 183 of the power ratio calculator 180 Do.

The pn code used for generating the first distortion signal and the second distortion signal may use a pn code different in code from the synchronized pn code instead of using a different code.

In order to improve the speed of obtaining the ratio of the received power to the distortion power, it is possible to remove the first and second quadrants 182 and 183 of the power ratio calculator 180 to perform the power ratio calculation by one power measurement, A summing unit 165 and 175 for adding the squared values and a square root unit 166 and 176 for calculating the square root of the summed value are connected to the multipliers 160 and 170, respectively, by integrators 161 and 162, 171 and 172, squarers 163 and 164, and 173 and 174, A comparator 201 for comparing the magnitude of the input despread I-phase signal and the Q-phase signal, a selector 202 controlled by the comparator 201, And an approximate power calculator 200 composed of two multipliers 203 and 204 and a summer 205 for multiplying the despread I phase signal and the Q phase signal. In the approximate power calculator 200, the magnitudes of both signals input first are compared in the comparator 201, and the comparator 201 controls the selector 202 to calculate a constant A having a constant value, Is multiplied by the multipliers 203 and 204, and the signal of the larger value is multiplied by a constant of 1, respectively. Each of the signals multiplied by the above is added to the sum ratio calculator 203 and input to the power ratio calculator 180. That is, the approximate power calculator 200 replaces an operation of calculating the distortion power by performing the following operation.

The output value of the approximate power calculator = max (| α |, | β |) + A × min (| | | | |) where α and β represent the received signal power and the distortion power, respectively.

Also, instead of the same configuration as in the above-described embodiment, distortion power may be obtained by configuring only one channel for obtaining distortion power. In this case, the averager 181 is also removed from the power ratio calculator 180, So that it can be easily implemented.

(E _b / N _o ) with respect to the noise power density in a direct spread code division multiple access (DS / CDMA) communication system having the pilot signal according to the present invention configured as described above and a method The apparatus can quickly determine the quality of the reverse link on-line without greatly increasing the complexity of the hardware configuration, and can quickly control the transmission power of the mobile station using the determined data.

A method and an apparatus for obtaining energy per bit (E _b / N _o ) with respect to a noise power density according to the present invention include a method of calculating a ratio of a received power to a distorted power Even if the received power from the mobile station is lowered, the distortion power is also lowered. If the quality of the call can be maintained, the control for increasing the transmission power of the mobile station is not performed. Therefore, It is a very useful invention that can maintain the quality of a communication channel without generating the effect of interference acting as a distorted power.

Hereinafter, the effects of the present invention will be more objectively verified by using computer simulation results.

The model for the simulation is the same as the fifth embodiment. In the model, the processing gain is 128 by spreading to 128 chips per bit of data.

6 shows the variation of the estimated energy per bit (E _b / N _o ) with respect to the noise power density for changes in white noise (AWGN: Additive White Gaussian noise) when there is no interference of the other channel on the reverse link, At this time, the number of bits per sample of the A / D converter in the receiving block 302 is 8 bits and the time to estimate E _b / N _o is 2 ms (= 72 bits = 9216 chips). In the transmitting block 301, McCllelan FIR filter with bit time (BT) = 0.5 was used to shape the filter. The estimated E _b / N _o is calculated for every data bit, and then the average value for 72 bits is calculated.

As shown in Figure 6, the estimated if only white noise without interference E _b / N _o values well the real E _b / N _o value, as well as to linearly proportional to the real E _b / N _o value It can be seen that it reflects.

7 shows the variation of the estimated energy per bit (E _b / N _o ) with respect to the noise power density when another user is using another channel. When all users transmit pilots with a constant power, Shows how the estimated value of E _b / N _o of the corresponding user and the remaining users changes when the pilot power of the mobile station changes.

The condition of this simulation is that five users transmit pilot and data at a constant power and the pilot power of the other user changes from -6dB to 6dB compared to the pilot power of the other user.

When the toned solid line is an estimated E _b / N _o value of the sixth user in the broken lines it will display the any one estimate E _b / N _o value of the other five people, to be the same value for all users In this case, E _b / N _o is 10 × log ₁₀ (128/11) = 10.7 dB ㏈ , which is close to the actual value, which is 10.4 dB in the actual estimated value in FIG. 7. Simulations are done several times and the average of the values is found, and the estimate will be the same as the actual value. In the graph of FIG. 7, as the transmission power of the sixth user increases, the corresponding user's estimated E _b / N _o value also linearly increases. As the transmission power acts as a distortion power, _b / N _o decreases linearly. Even when the transmission power of the sixth user decreases, the estimated E _b / N _o values of the users decrease and increase, respectively. As a result, It can be seen that the method and apparatus for obtaining the energy per bit (E _b / N _o ) for the noise power density according to the present invention reflects the actual E _b / N _o value.

FIG. 8 shows the simulation results of FIG. 7, with the exception of the presence of white noise, and the resulting E _b / N _o value. The graph of FIG. 8 shows that the change of the estimated E _b / N _o value is slightly lower than that of the result of FIG. 7 due to the influence of white noise, and thus the method and apparatus proposed by the present invention It is possible to estimate the quality or power ratio of the reverse link simply and efficiently.

FIG. 9 shows the mean and standard deviation of the estimated E _b / N _o values obtained when the estimated time of E _b / N _o is changed. This simulation is performed when 10 users exist. In the graph of FIG. 9, it can be seen that the standard deviation of the estimated value becomes larger as the estimated time of E _b / N _o becomes shorter. Since the standard deviation of the estimated value is about 1 dB up to the estimated time of 0.5 ms, The method and apparatus proposed by the present invention is a very economical and superior invention capable of performing the closed circuit power control of the reverse link by determining the E _b / N _o value quickly on-line by limiting the estimated time to a short time of 0.5 ms .

Claims (16)

Establishing synchronization of the reverse link using a pilot signal; Obtaining received power from an input signal; Obtaining a distortion power of an input signal by despreading an input signal with a pn code having no correlation with a synchronized pn code; (Eb / No) for noise power density in a direct spread code division multiple access (DS / CDMA) communication system having a pilot signal consisting of a ratio of the reception power to the distortion power How to obtain. 2. The method of claim 1, further comprising: subtracting 1 from the ratio of the received power to the distortion power; And a step of multiplying the subtracted value by a ratio of a noise band to a data rate to obtain an energy per bit (Eb / No) with respect to a noise power density, wherein the energy per bit (Eb / No). The method of claim 1, wherein the step of obtaining the received power comprises: obtaining a received power at a predetermined time; Repeating the step of obtaining the received power; Obtaining a sum of the received powers obtained repeatedly; And determining a quality of a reception state by using the sum of the obtained reception powers. The method of claim 1, further comprising the step of: determining an energy Eb / No per bit with respect to a noise power density. The method of claim 1, wherein the step of obtaining the received power comprises: obtaining a received power at a predetermined time; Repeating the step of obtaining the received power; And obtaining a sum of the received powers obtained repeatedly; Wherein the step of obtaining the distortion power includes: obtaining a distortion power at a predetermined time point; Repeating the step of obtaining the distortion power; And obtaining a sum of the distortion power obtained repeatedly; Wherein the step of obtaining the ratio of the received power to the distortion power includes a step of obtaining a ratio of a sum of the received powers to a sum of the distorted powers, Eb / No). 5. The method of claim 4, further comprising: subtracting 1 from a ratio of a sum of the received power to a sum of the distortion power; And multiplying the subtracted value by a ratio of a noise band to a data rate to obtain an energy per bit (Eb / No) with respect to a noise power density; (Eb / No) for the noise power density further comprising: The method as claimed in any one of claims 1 to 5, wherein the step of obtaining the distortion power comprises: despreading a delayed pn code of a synchronized pn code to an input signal to obtain a distortion power PA of the input signal, a step of despreading a pn code preceding a pn code with respect to an input signal to obtain a distortion power PB of the input signal; And obtaining a distortion power corresponding to an average of the two distortion powers (PA, PB); (Eb / No) with respect to the noise power density, which is obtained by dividing the noise power per unit time. The method of claim 6, wherein the step of determining the distortion power (P _A , P _B ) comprises: calculating a power (PI) of an I-phase signal and a power (PQ) of a Q- Comparing the sizes of the first and second regions; And obtaining an approximate value of the received distortion power by multiplying a small power of the two powers by a constant of a constant size and adding the result to a large power to obtain an energy per bit (Eb / No) with respect to the noise power density. The method as claimed in any one of claims 1 to 5, wherein the step of obtaining the distortion power comprises: obtaining a distortion power (P _A ) of an input signal by despreading a pn code different from a synchronized pn code to an input signal, Obtaining a distortion power (P _B ) of an input signal by despreading an input signal with a pn code different from the pn code; And obtaining a distortion power corresponding to an average of the two distortion powers (P _A , P _B ); (E _b / N _o ) with respect to the noise power density. The method as claimed in claim 8, wherein the step of obtaining the respective distorted powers (P _A , P _B ) comprises the steps of: calculating a power (P ₁ ) of an I-phase signal and a power of a Q- P _Q ); And obtaining an approximate value of the received distortion power by multiplying a small power out of the two powers by a constant size constant to add to a large power; (E _b / N _o ) with respect to the noise power density. Claim 7 according to any one of claims 9, wherein the predetermined size of the constant energy per bit to noise power density, characterized by using the same or smaller than a half equal to 1/4 or greater (E _b / N _o ). 6. The method of claim 1, wherein the step of determining the distortion power comprises: comparing a magnitude of a power (P _Q ) of a signal; And obtaining an approximate value of the received distortion power by multiplying a small power of the two powers by a constant of a predetermined magnitude and adding it to a large power to obtain energy E _b / N _o per bit with respect to the noise power density. 12. The method of claim 11, wherein the predetermined constant is a value equal to or less than 1/2 and equal to or greater than 1/4. The energy per bit (E _b / N _o ) . First pn code generating means for generating a first pn code; Demodulating and converting means for demodulating a received signal into an I-phase signal and a Q-phase signal, respectively, and then converting the demodulated signal into a digital signal; Despreading means for despreading I phase and Q phase signals output from the demodulation and conversion means using a Walsh code and a first pn code; Receiving power calculation means for calculating a received power by using the powers of the despread I-phase and Q-phase signals; Wherein the first pn code is synchronized with the local first code by comparing the power obtained by the reception power calculation means with a reference value, and when the synchronization is not established, the phase of the first pn code controlled by the first pn code generation means is changed A synchronization determining and controlling means Second pn code generation means for generating a second pn code having no correlation with the first pn code synchronized by the synchronization determination and control means; First distortion signal generation means for generating a distortion signal by despreading I phase and Q phase signals output from the demodulation and conversion means using the second pn code; Distortion power calculating means for obtaining distortion power using the distorted signal; And power ratio calculation means for calculating a ratio of the received power calculated by the received power calculation means to the calculated distortion power; (Eb / No) with respect to the noise power density in a direct spread code division multiple access (DS / CDMA) communication scheme having a pilot signal comprising a pilot symbol and a pilot symbol. 14. The apparatus according to claim 13, further comprising: third puncture code generation means for generating a third puncture symbol phase-advanced with respect to the first punctured code synchronized by the synchronous determination and control means; And second distortion signal generation means for generating a distortion signal by despreading the I phase and Q phase signals output from the demodulation and conversion means using the third pn code; Wherein the power ratio calculating means calculates a power average of the power of the distortion signal output from the first distortion signal generating means and the average power of the power of the distortion signal output from the second distortion signal generating means, (Eb / No) with respect to the noise power density, characterized in that the second pn code generating means generates a second pn code whose phase is delayed with respect to the synchronized first pn code . The apparatus as claimed in claim 13, further comprising: third puncturing means for generating a third puncturing code different from a first punctured code synchronized by the synchronous judging and controlling means; And second distortion signal generation means for generating a distortion signal by despreading the I phase and Q phase signals output from the demodulation and conversion means using the third pn code; Wherein the power ratio calculating means calculates a power average of the power of the distortion signal output from the first distortion signal generating means and the average power of the power of the distortion signal output from the second distortion signal generating means, Wherein the second pn code generating means generates a second pn code different from the synchronized first pn code, wherein the second pn code generating means generates a second pn code different from the synchronized first pn code. The system of claim 13, 14 or 15, wherein the power ratio calculation means comprises: integrating means for accumulating the value of the received power; And comparison means for comparing the accumulated value of the received power by the integration means with certain reference values; (Eb / No) with respect to the noise power density.