KR980012981A - Method and apparatus for determining energy per bit (Eb / No) with respect to noise power density in a DS / CDMA system having 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 or the Pn code Code is used to despread a signal to obtain a distortion power by using a correlation of pilot signals 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 (Eb / No) with respect to density, and can quickly determine the quality of a reverse link on-line without greatly increasing the complexity of the hardware configuration. The power of a signal transmitted from the mobile station to the base station can be rapidly controlled using the determined data.

Description

BRIEF DESCRIPTION OF THE DRAWINGS Fig.

1 shows a structure of a transmission part of a mobile station in 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 energy per bit (Eb / No) for a noise power density according to the present invention and an embodiment implementing the apparatus,

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,

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

6 shows the variation of the estimated energy Bb / No per bit with respect to the noise power density with respect to 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,

9 shows an average value and a standard deviation of the estimated Eb / No value obtained when the estimated time of Bb / No is changed.

DESCRIPTION OF THE REFERENCE NUMERALS

Al-An: summing unit Ml-Mn:

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

20, 21: Low-pass filter 30.31: A / D converter

40, 41: decimator 57-55: 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, 174: 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:

163,164: Squaring unit 165:

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

171,172: integrator 173,174: square

175: Totalizer 176: Square root

180: power ratio calculating unit 181:

182, 183: integrator 184:

200: approximate power calculator 201: comparator

202: selectors 203 and 204:

205: summer 301: transmission block

302: Receiving block

DETAILED DESCRIPTION OF THE INVENTION [

[Object of the invention]

[TECHNICAL FIELD OF THE INVENTION AND RELATED ART OF THE SAME]

The present invention relates to a method and apparatus for determining the energy per bit (EbNo) for a noise power density in a direct spread code division multiple access (DS / CDMA) communication scheme with a pilot signal, and more particularly, 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 which is not synchronized or the pn code whose phase is different from the synchronized pn code is used And calculating a distortion power using the correlation of the received pilot signal and the pilot signal to obtain a mutual ratio of the two powers, thereby obtaining an energy per bit for the noise power density in the reverse link of the direct spreading code division multiple access Bb / No) and a device therefor.

The basic principle of the spread spectrum communication method refers to a method of communicating by spreading a band of the original signal so as to have a transmission bandwidth wider than the bandwidth (bandwidth: BW) of the original signal to be transmitted. Using the basic principle of spreading communication, if the bandwidth of the signal is sufficiently broadened, it is possible to communicate even at a very low signal-to-noise ratio (SNR).

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

The CDMA (DS / CDMA) scheme using dual direct spreading has various advantages, but there are many technical disputes, and there is a lot of controversy about the power control method of the mobile station among them. 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 of the reverse link offset 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.

The first method is to estimate the received signal strength by measuring the received signal strength indicator (Rssl) indicating the strength of the received signal. The second method is to measure the bit error rate (BER) 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 scheme. The second method has the problem of transmitting unnecessary data and the problem of causing block delay according to the processing of the received signal, while the third method does not cause unnecessary data transmission or delay, but it is difficult to implement due to complicated calculation And the signal processing speed is lowered.

[Technical Problem]

Accordingly, the present invention has been made to overcome the above-described problems, and it is an object of the present invention to provide a method and apparatus for detecting a signal state without complicated calculation, (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 Another object of the present invention is to provide a method of obtaining the energy per unit time (E _b / N _o ) Another object of the present invention is to provide a method for obtaining energy per bit (E _b / N _o ) with respect to a noise power density capable of measuring the quality of a new phase. (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 ), and another object of the present invention is to provide a method for estimating distortion power by approximating it to obtain a distortion power, (E _b / N _o ) for the noise power density. It is still another object of the present invention to provide a method and apparatus for measuring a signal in a DS / CDMA communication system, which can perform measurement in a short time without complicated calculations for detecting a state of a signal, (E _b / N _o ) for a noise power density in a direct spread code division multiple access (DS / CDMA) communication system having a plurality of signals, and a further object of the present invention is to provide a device (B _b / N _o ) with respect to the noise power density, which improves the accuracy of the measured value of the distorted power by doubly obtaining and averaging the distorted power by despreading each pn code different in phase from the pn code, And to provide a device for obtaining the above-mentioned information. It is still another object of the present invention to provide a method and a system for decoding bits of a noise power density that improves the accuracy of measured values of distortion power by despreading different pn codes different from the synchronized pn codes, Another object of the present invention is to provide an apparatus for obtaining the energy per unit time (B _b / N _o ) per unit time, and it is an object of the present invention to provide a noise power density (B _b / N _o ) per bit of the output signal of the output terminal.

[Structure and operation of the invention]

According to another aspect of the present invention, there is provided a method for obtaining 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. The method for obtaining the energy per bit (E _b / N _o ) of the noise power density according to the present invention is characterized by comprising: Wherein the step of obtaining the distortion power and the step of obtaining the distortion power repeatedly obtain respective target powers; 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 )) is obtained by simultaneously despreading a pn code whose phase is delayed from the synchronized pn code and a pn code whose phase is above the synchronized pn code to the input signal to obtain two distortion powers (P _A , P _B ); And obtaining a distortion power corresponding to an average of the two distortion powers (P _A , P _B ). Another characteristic is that the energy per bit (E _b / N _o ) Comprises the steps of simultaneously despreading an input signal with a pn code having a code different from the synchronized pn code to obtain two distortion powers (P _A , P _B ) of the input signal, and a step 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 is a step of obtaining an I-phase (In-phase) signal Comparing magnitudes of power (P ₁ ) and power (Pa) of a Q phase (quadrature phase) signal; Multiplying a power of a smaller one of the two powers (P _I / P _a ) by a constant of a predetermined magnitude and adding the power to a larger power to obtain an approximate value of the received distortion 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.

In order to achieve the above object, there is provided an apparatus for obtaining energy per bit (E _b / N _o ) of a noise power density according to the present invention, comprising: first local pn code generating means for generating a first pn code; Demodulation means for demodulating the received radio 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 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 pn code by comparing the power obtained by the reception power calculating means with a reference value, and when the synchronization is not established, the phase of the first pn code A second pn code generating means for generating a second pn code whose crrelation is raised with the first pn code synchronized by the synchronous decision 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; The apparatus for obtaining energy per bit (E _b / N _o ) with respect to the noise power density according to the present invention is characterized in that the apparatus includes a first pn code synchronized with the synchronous determination and control means, Third pn code generating means for generating a third pn code whose phase is ahead; 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 The calculation means calculates the average power of the power of the signal output from the first distortion signal generation means and the power of the distortion signal output from the second distortion signal generation means, There is another feature in generating a second pn code whose phase is delayed with respect to the first pn code. An apparatus for obtaining energy per bit (E _b / N _o ) with respect to a noise power density according to the present invention includes: Third pn code generating means for generating a third pn code having a code different from the first pn code synchronized by the 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 is further characterized by generating a second pn code having a code different from the synchronized first pn code, and the energy per bit (Bb / No), the power ratio calculating means includes: an integrating means for accumulating a value of received power; And comparison means for comparing the accumulated value of the received power with certain reference values.

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, Synchronized with the pn code of the pilot channel of the link, calculates the total power of the demodulated signal and the distorted signal despread by the pn code synchronized with the received signal at the same time as the synchronization is confirmed, 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 subtracting 1 from the power ratio and multiplying the subtracted value by the noise band 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 .

Further, in the apparatus for obtaining the energy per bit (E _b / N _o ) for the noise density in the direct spread code division multiple access (DS / CDMA) communication system configured as described above, Phase signals 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 the reception power calculating means adds and squares each of the despread signals, sums the two signals, obtains a square root thereof, and inputs the sum to the power ratio calculating means And outputs the sum or square root to the synchronization determination and control means. The synchronization determination and control means determines that synchronization is not established if 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, If it is equal to or greater than the predetermined standard criterion, 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 generating 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 generating means , And the despread signal is input to the distortion power calculation means. When the distortion power calculation means inputs the distortion power value obtained by performing the same process as the reception power calculation means on the despread signal to the power ratio calculation means , The power ratio calculating means calculates the ratio of the two powers inputted when the synchronism judging means and the control means are notified of the fact that the synchronization is established and outputs the calculated ratio to obtain the ratio of the received power to the distorted power, If the operation (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) is performed, the energy per bit It is possible to obtain the (E _b / N _o).

The second distortion signal generation means and the distortion power calculation means are added in parallel to the first distortion signal generation means in addition to the first distortion signal generation means so that the first pn code outputted from another third pn code generation means is non- The power ratio calculating means may be provided with a power averaging means so that 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 may have the same code as the first pn code, Let it be a pn 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 a multiplier Ml and M2, and then divided into two spread codes P _A and P _B 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 one phase and Q phase data (d _I , d _Q ) is multiplied by a Hardamard code (W _P ) of a pilot channel and a Hardamard code (M _T ) (P _I , P _Q ) and passes 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 Al and A2 for the I phase and the Q phase signal, respectively, and then are supplied to the multipliers M5 and M6 via the D / A converters 15 and 16 each carrier wave is transmitted from deohaejyeo (next adder (A3) multiplied by cow _e t, _e t sinw.

The transmitted signal is synchronized and synchronized by the Pn code synchronizer of the reverse link of FIG. 2 as follows.

First, the signal (r (t)) input through an antenna is processed by the RF processing stage to the next via I phase and Q-phase signal is multiplied by a conversion into an intermediate frequency band being again demodulated carrier asynchronous cosw _e t _e t for the -sinw The corresponding carrier is removed, and the low-pass spreaders 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 positive / early / late samples P, B and L using the HOLD signal obtained in the initial synchronization and synchronization tracking process, (P _I ) and a pn code (P _a ) are multiplied by punctua 1 / early / 1ate samples (P, B and L) and multiplied by a Hardamard code (W _P ) -55), squaring units 60-65 and square root units 70, 71, and 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 (Seletion Control) for adjusting the decimation time of the decimators 40 and 41 are output. The above process is repeated using the decimated sample signals E, P, L and pn codes P _I , P _Q selected by the HOLD signal and the Seletion Control signal, 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 energy E _b / N _o per bit of the noise power density according to the present invention is obtained. FIG. 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 Demodulation and conversion unit 100 for converting the digital signal into a digital signal. 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 reception power calculator 120 for calculating the power of the despread signal, A synchronization determination / control unit 130 for receiving the received power and determining whether to synchronize and controlling the phase of a local Pn code, a first distortion signal generator 130 for generating a first distortion signal of the demodulated and converted digital signal, A second distortion signal generator 140 for generating a first distortion signal and a second distortion signal, a first distortion power calculator 160 for calculating a distortion power of the first distortion signal and the second distortion signal, And a power ratio operator 180 for calculating an average value of the first distortion power and the second distortion power and the reception power value. The demodulator / demodulator 100, The reception power calculation unit 120, and the synchronization determination and control unit 130, Since the configuration is the same as that of the components excluding the channel for processing the early sample signal and the late sample signal in the pn code synchronous part, only the signal input / output from the synchronous part of the pn code can be used have. The first distortion signal generation unit 140 generates a second distortion signal. The second distortion signal generation unit 150 generates the first distortion signal. The internal structure of the first distortion signal and the second generation unit 150 includes the despreading Is substantially the same as the internal structure of the spreading code 110 except that the despreading signal is different and there is no despreading process by Walsh codes.

In one embodiment of a method for obtaining the energy E _b / N _o per bit for the noise power density according to the present invention, the received power is calculated as follows: The Pn code is synchronized and the reception power is obtained through the demodulation and transformation unit 100, the despreading unit 110, the reception power calculation unit 120, and the synchronization determination / , 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, to find the 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 interference signal is P _I , The power is P _N , the total received power is P _T , and the distortion power is P _D.

Since P _T and P _D are respectively as follows.

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

P _D = P _l + P _N.

Here, we obtain the ratio of P _T to P _D.

.

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 of noise and intermittent power (N)

. therefore,

. On the other hand, E _b / N _o can be obtained from C / N.

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 the noise and the interference and the energy E _b per bit for the noise total work N _o according to the above- If the above value is obtained from the signal received from the base station from each mobile station, the absolute value of the received power of the base station is determined so that the received power reaching the base station is constant according to the value. It is possible to control the transmission output of the mobile station according to the relative value.

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

If the Pe 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, the demodulation and conversion unit 100 as described above. When the synchronization of the pn code is established through the despreading unit 110, the reception power calculator 120 and the synchronization decision / control unit 130, the first distortion signal generator 140 generates a phase difference Spreads the digital signal output from the demodulation and conversion unit 100 using a pn code delayed by a predetermined number of chips or more, and the second distortion signal generation unit 150 generates a second distortion signal, And despreads the digital signal output from the demodulation and conversion unit 100 using a pn code preceding the chip. 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 to generate the first distortion signal and the second distortion signal may use a pn code different in code from that of the synchronized pn code.

Further, in order to improve the speed at which the ratio of the received power to the distortion power is to be improved, the integrator 182, 183 of the power ratio calculator 180 may be removed 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, 4, the input diagram includes a comparator 201 for comparing the magnitude of the 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 ( , ) + A 占 min ( , ) Where α and β represent the received signal power and the distorted power, respectively.

Also, instead of the 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.

[Effects of the Invention]

(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 device 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 transmit power of the mobile station using the read 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 reception power received from the mobile station is lowered, the distortion power is also lowered, and if the quality of the call can be maintained, the control for increasing the transmission power of the mobile station is not performed, 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 shown in FIG. 5. In the model, the processing gain is 128 by spreading to 128 chips per 1 bit of data.

6 shows a variation of the estimated energy E _b / N _o per bit with respect to the noise power density with respect to the change of AWGN (Additive White Gaussian noise) when there is no interference of other channels on the reverse link, At this time, the number of bits per sample of the A / D converter in the reception block 302 is S bits, and the time for estimating E _b / N _o is 2 ms (= 72 bits = 9216). In the transmission block 301, McCllelan FIR filter with a bit time (BT) = 0.5 to shape the image. 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 estimation in the case where the interference signal in noise Earl White 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 a different channel. It is assumed that all users transmit a pilot 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 with constant power and the pilot power of the other user changes from -6dB to 6dB compared to the pilot power of the other user.

The solid line is the sixth user estimate E _b / N _o values in Fig. 7, the dotted line will display the any one estimate E _b / N _o value of the remaining five users, if that same value for all users. In this case, the value of E _b / N _o is 10 × 1 log ₁₀ (128/11) = 17.7 dB. In FIG. 7, the actual estimated value is 10.4 dB, which is close to the actual value. Simulations are done several times and the average of the gulls will be the same as the actual value. In the graph of Fig. When the transmission power of the sixth user increases the consequent user estimate E _b / N _o value also increases linearly, and estimates, as the other user have the transmission power acts in the distortion power E _b / N _o value And the estimated E _b / N _o values of the users decrease and increase, respectively, when the transmission power of the sixth user decreases. Therefore, the noise power density according to the present invention It can be seen that the method and apparatus for obtaining the energy per bit (E _b / N _o ) reflects the actual E _b / N _o value.

FIG. 8 is the same as the simulation condition of FIG. 7 except for the presence of white noise and the resulting estimate of E _b / N _o . The graph of FIG. 8 shows that the change of the estimated E _b / N _o value is slightly lower than that of FIG. 7 due to the influence of the white noise. 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 an average value and a standard deviation of the estimated E _b / N _o value obtained when the estimated time of E _b / N _o is changed. This simulation is performed when ten users exist. Since Referring to FIG. 9, a graph of E _b / N _o of the estimation time to  used with a standard deviation of sureuk estimates to find out increases, the estimated time is approximately the standard deviation of the estimate has approximately 0.5ms IdB, the present invention The method and apparatus proposed by the present invention can estimate the E _b / N _o value quickly on-line by limiting the estimated time to a short time of 0.5 ms, which is very economical and capable of performing the closed circuit power control of the reverse link It is well known that it is an invention.

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; And obtaining a ratio of the received power to the distortion power; (E _b / N _o ) with respect to the noise power density in a direct spread code division multiple access (DS / CDMA) communication system having a pilot signal consisting of a pilot signal. 2. The method of claim 1, further comprising: subtracting 1 from the ratio of the received power to the distortion power; and multiplying the subtracted value by the ratio of the noise band to the data rate to obtain the energy per bit (Eb / No); (Bb / N7) for the noise power density further comprising: 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 the reception section using the sum of the obtained reception powers; To obtain an energy E _b / N _o per bit with respect to the 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 power 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 the sum of the received power to the sum of the distortion power, / 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; (Bb / No) for the noise power density including 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: 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); (E _b / N _o ) with respect to the noise power density. 7. The method of claim 6, wherein the step of determining the distortion power (P _A , P _B ) comprises: calculating a power (PQ) of a quadrature phase signal and a power PI of a phase- Comparing the sizes of the first and second regions; 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; (Eb / No) with respect to the noise power density, which is obtained by dividing the noise power per unit time. 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, (P _B ) of the input signal by despreading the input signal with a pn code different from the input pn code; And obtaining a corresponding distortion power of the 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 each of the distortion powers P _A and P _B comprises: calculating a power P _{I of an I} -phase signal and a power P P of a Q- comparing the sizes of _a ); 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 per bit (E _b / N _o ) of the noise power density Claim 7 according to any one of claims 9, wherein the predetermined size of a constant energy-per-bit for the japeung power density which is characterized by using the same or smaller than 1/2 or larger than 1/4 go value (E _b / N _o ). 6. The method according to any one of claims 1 to 5, The step of obtaining the distortion power includes: comparing magnitudes of power (P _a ) 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 an energy per bit (E _b / N _o ) with respect to a 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 the received signal into an I phase signal and a Q phase signal, respectively, and then converting the received signal into a digital signal; Despreading means for despreading the 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 pn code by comparing the power obtained by the reception power calculation means with a reference value, and if synchronization is not established, A synchronous judgment and control means for changing the phase; 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 generating means for generating a distortion signal by despreading the I phase and Q phase signals using the second pn code; Distortion power calculating means for obtaining a distortion power using the distorted signal and power ratio calculating means for obtaining a ratio of the received power calculated by the received power calculating means to the calculated distortion power; (E _b / N _o ) for a noise power work in a direct spread code division multiple access (DS / CDMA) communication scheme having a pilot signal comprising a pilot signal and a pilot signal. The apparatus of claim 13, further comprising: third pn code generating means for generating a third pn code whose phase precedes the first pn code synchronized by the synchronization determining 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, further comprising means, and wherein the 2 pn code generating means of the synchronization of the first energy per bit to noise power density, characterized in that the phase is key in case of a delayed claim 2 pn code for 7n code (E _b / N _o ). 14. The apparatus of claim 13, further comprising: third pn code generation means for generating a third pn code different from the first pn code synchronized by the synchronization decision discard control means; and third pn code generation means for generating I p phase and Q Second distortion signal generation means for generating a distortion signal by despreading the phase signal using the third pn code; Wherein the power ratio calculating means calculates the power ratio calculating means for calculating the average power of the distortion signal output from the first distortion signal generating means and the average power of the distortion signal output from the second distortion signal generating means, Wherein the second pn code generating means further comprises means for generating a second pn code different from the synchronized first pn code, wherein the energy per bit (E _b / N _o ). 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 integrating means with certain reference intervals; (Bb / No) to the noise power density. ※ Note: It is disclosed by the contents of the first application.