KR100340197B1 - Narrowband Interference Canceller System with Adaptive Compensation Filter and its Method in CDMA System - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a narrowband interference noise control apparatus and method using an adaptive compensation circuit in a code division multiple access system.

2. The technical problem to be solved by the invention

The present invention provides a narrowband interference noise control device to remove / suppress the narrowband interference noise as much as possible by using an autoregressive, least square average (LMS) algorithm, and an adaptive compensation algorithm before despreading a received signal. And a computer readable recording medium having recorded thereon a method and a program for realizing the method.

3. Summary of Solution to Invention

An interference noise control apparatus applied to a code division multiple access system, comprising: analog-to-digital (A / D) conversion means for converting a received analog signal into a digital signal;

Digital downconversion means (DDC) for converting the converted digital signal into a baseband signal; Autoregressive, least mean square (LMS) algorithms and adaptive compensation algorithms are used to remove narrowband interference noise signal components from the transformed baseband signal and control the final output to a predetermined reference range. Adaptive interference noise control means for; Digital upconverting means (DUC) for converting the digital signal from which the narrowband interference noise is removed into a digital upconverting frequency band signal; And digital-to-analog (D / A) converting means for converting the converted digital upconverted frequency band signal into an analog signal.

4. Important uses of the invention

Used for interference noise control in code division multiple access system.

Description

Narrowband Interference Canceler System with Adaptive Compensation Filter and its Method in CDMA System using Adaptive Compensation Circuit in Code Division Multiple Access System

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a narrowband interference noise control apparatus and method therefor in a code division multiple access system. The present invention relates to autoregressive, least mean square (LMS) algorithm before despreading a received signal. And a narrowband interference noise control apparatus for maximizing elimination / suppression of introduced narrowband interference noise using an adaptive compensation algorithm, and a method and a computer readable recording medium recording a program for implementing the method.

Source technologies related to code division multiple access (CDMA), which have been conventionally studied and used for military purposes, are now generalized and are commercialized to promote breakthroughs in information and communication. In addition, in domestic and overseas wireless communication and mobile communication field, CDMA technology is applied to develop CDMA system and personal mobile communication (PCS) system and applied to mobile communication field. Development and early development of next generation mobile communication (IMT-2000) system It is in preparation for service.

However, the spread spectrum communication method, which is a characteristic of CDMA technology, spreads the information signal to be spread as a spread signal and then transmits the received information signal by communicating with a transmission bandwidth (broadband signal) much wider than the bandwidth of the information signal to be transmitted. On the side, if the same spreading signal is used to despread, the original information signal is extracted. That is, while transmitting information from a transmitter and reaching a receiver through a wireless transmission channel, noise and interference signal components are included in a spreading band transmitted to reach a receiver, and the received signal is despread from the receiver to perform an information signal. Can be extracted.

The subscriber capacity of the CDMA system having such characteristics is expressed by the following Equation 1.

Where N is the number of subscribers acceptable, W / R is the processing gain, E _b / N _o is the ratio of noise and interference to signal energy, F is the frequency reuse efficiency, S is the cell split gain, and V is the transmission rate. Adjustment gain.

In the system using CDMA technology, the low data rate code is spread over a wide band so that the same performance is achieved by using an error correction code having a much lower code rate than that of the frequency division multiple access (FDMA) and the time division multiple access (TDMA) methods. A lower signal energy to noise energy ratio is required to maintain.

In fact, E _b / N _o in Equation (1) is changed by various propagation environment conditions such as multipath fading, moving speed, and change of interference signal received from other systems, and it is important to determine the subscriber capacity. It is variable, and this value should be minimized to increase the subscriber capacity and the noise energy ratio should be reduced.

That is, although the system is very robust against the interference noise signal component due to the characteristics of the CDMA technology using the spread spectrum communication method, it becomes difficult to transmit information when the interference noise signal becomes stronger than the spread signal to some extent. In order to avoid noise and interference in the wireless environment, there is a method of performing powerful power control, but a new method is required for unexpected interference noise signals.

As a countermeasure against such an unexpected interference noise signal, it has been studied to control a narrowband interference noise signal by using an adaptive signal processing algorithm.

However, antenna diversity technology, interleaving technology, and equalizers as countermeasures for anticipated interference and unexpected interference noises operating in a wireless environment to increase subscriber capacity and improve system efficiency. (Equalization), Correlation, Frequency Hopping, RAKE Receiver, and Power Control, etc. are adopted for each field, but there is a problem that it is not getting satisfactory interference cancellation effect. .

In other words, a combination and antenna diversity technique for processing a received signal having a different fading pattern, and a predictive antenna selection diversity (PASD) method for measuring signal intensity by measuring a radio path signal in the past and a continuous continuous error Interleaving technique for distributing and transmitting frame signals in multiple time slots for correcting the signal, linear equalizer technique for correcting inter-symbol (ISI) between symbols of a received signal, and Decision Feedback Equalizer (DFE) , Nonlinear equalizer technology using Maximum Likelihood Sequential Estimation (MLSE) algorithm, frequency hopping method used to overcome fading in GSM method, to overcome delay distortion of received signal by multipath fading Lake receiver technology and power control method are used, but CDMA source technology is used. There was a problem that the subscriber capacity calculated by using the service cannot be utilized.

The main cause of the problem is that it is impossible to completely eliminate the interference noise signal being mixed in the radio path and the noise signal generated in the system, and also because of the technical shortcomings used above.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a narrowband interference noise control apparatus and method and method for realizing narrowband interference noise using an adaptive compensation circuit in a code division multiple access system are provided. Its purpose is to provide a computer readable recording medium having recorded thereon a program.

That is, the present invention uses narrowband interference to control the introduced narrowband interference noise using autoregressive, least mean square (LMS) algorithm, and adaptive compensation algorithm before despreading the received signal. It is an object of the present invention to provide a noise control device and a method thereof and a computer-readable recording medium recording a program for realizing the method.

1 is a block diagram of an embodiment of a narrowband interference noise control apparatus using an adaptive compensation circuit in a code division multiple access system according to the present invention.

2 is a diagram illustrating an embodiment of the adaptive interference noise controller of FIG. 1 according to the present invention;

Figure 3 is an embodiment configuration of the first comparative analysis of Figure 2 according to the present invention.

4 is a block diagram of an embodiment of the interference noise controller and the adaptive compensation filter of FIG. 2 according to the present invention;

Figure 5 is a configuration diagram of an embodiment of a second comparative analysis of Figure 2 according to the present invention.

6 is an explanatory diagram of an output level adjusting function compared to a reference level applied to the present invention.

7 is a diagram illustrating an embodiment of the adaptive interference cancellation filter of FIG. 4 in accordance with the present invention.

8 is a block diagram of an embodiment of the adaptive compensation filter of FIG. 4 according to the present invention;

9 is a flowchart illustrating a narrowband interference noise control method using adaptive compensation in a code division multiple access system according to the present invention.

* Explanation of symbols on the main parts of the drawing

100: analog-to-digital (A / D) converter 102: digital down converter (DDC)

104: adaptive interference noise control unit 106: digital upconverter (DUC)

108: digital-to-analog (D / A) converter 200: first comparative analysis unit

204: interference noise controller 206: adaptive compensation filter

208: second comparative analysis unit

In order to achieve the above object, the present invention provides an interference noise control apparatus applied to a code division multiple access system, comprising: analog-to-digital (A / D) conversion means for converting a received analog signal into a digital signal; Digital downconverting means (DDC) for converting the converted digital signal into a baseband signal; Autoregressive, least mean square (LMS) algorithms and adaptive compensation algorithms are used to remove narrowband interference noise signal components from the transformed baseband signal and control the final output to a predetermined reference range. Adaptive interference noise control means for; Digital upconverting means (DUC) for converting the digital signal from which the narrowband interference noise is removed into a digital upconverting frequency band signal; And digital-to-analog (D / A) converting means for converting the converted digital upconverted frequency band signal into an analog signal.

The present invention provides an interference noise control method applied to a narrowband interference noise control apparatus in a code division multiple access system, comprising: a first step of converting a received analog signal into a digital signal; Converting the converted digital signal into a baseband signal; A method for controlling narrowband interference noise signal components from the transformed baseband signal using autoregressive, least square average (LMS) algorithms, and adaptive compensation algorithms, and controlling the final output within a predetermined reference range. Three steps; Converting the digital signal from which the narrowband interference noise has been removed into a digital upconversion frequency band signal; And a fifth step of converting the converted digital upconverted frequency band signal into an analog signal.

The present invention also provides a narrowband interference noise control device having a processor for controlling narrowband interference noise in a code division multiple access system, comprising: a first function of converting a received analog signal into a digital signal; A second function of converting the converted digital signal into a baseband signal; A method for controlling narrowband interference noise signal components from the transformed baseband signal using autoregressive, least square average (LMS) algorithms, and adaptive compensation algorithms, and controlling the final output within a predetermined reference range. 3 functions; A fourth function of converting the digital signal from which the narrowband interference noise is removed into a digital upconversion frequency band signal; And a computer readable recording medium having recorded thereon a program for realizing a fifth function of converting the converted digital upconverted frequency band signal into an analog signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an embodiment of a narrowband interference noise control apparatus using an adaptive compensation circuit in a code division multiple access system according to the present invention.

The narrowband interference noise control apparatus using the adaptive compensation circuit includes an analog-to-digital (A / D) converter 100, a digital down converter (DDC) 102, an adaptive interference noise controller 104, and a digital upconverter. (DUC: Digital Up Converter) 112, and digital-to-analog (D / A) converter 108.

The A / D converter 100 converts an RF / IF analog signal including CDMA information into a digital signal.

The digital down converter (DDC) 102 selects a desired FA from among digital signals converted and quantized at an appropriate sampling rate in the IF band, and converts the digital signal of the selected IF band into a baseband ( The decimation is performed in 1/4 to 1/8 to convert to baseband and to facilitate digital processing of oversampled signals.

The adaptive interference noise control unit 104 utilizes an autoregressive and least square mean (LMS) algorithm and an adaptive compensation algorithm to control the interference contained in the signal input from the digital down converter (DDC) 102. Eliminates and suppresses band interference noise signal components.

Digital up converter (DUC) 106 is converted to baseband by digital down converter (DDC) 102 and decimated from 1/4 to 1/8 to adaptive interference noise control unit 104. The narrowband interference noise signal component is removed and suppressed, and the output signal having gain control is restored to the state before conversion by the digital down-converter 102 and interpolated.

The D / A converter 108 converts the digital signal upconverted and interpolated by the digital upconverter into an initially received analog RF / IF signal.

In more detail, it is as follows.

The A / D converter 100 converts a series of FAs divided / allocated into a predetermined frequency band according to the frequency allocation (FA) criterion of the CDMA system to the entire band or the divided unit FAs of the received RF / IF band. Converts analog signals to digital signals at intermediate frequencies.

That is, the analog IF signal is sampled using a sample-and-hold amplifier at a constant sampling rate, and the sampled data is quantized to a constant bit.

The power level of the analog IF signal input to the A / D converter 100 is a signal higher than a certain level in the RF / IF part so that the A / D converter 100 does not leave a dynamic range that can be processed. It should be adjusted to the reference level within the dynamic range of the A / D converter 100 and transmitted to the input of the A / D converter 100. If the input signal level is the setting reference level of the dynamic range of the A / D converter 100, In case of exceeding, overflow or saturation occurs, and A / D conversion cannot be performed or is recognized as a constant maximum level.

Therefore, it is necessary to adjust the level in the RF / IF part, and the method of adjusting the level is Total AGC (Total Automatic Gain Control) or FA unit AGC and Total ALC (Total Automatic). Level Control) or FA unit ALC method.

However, AGC aims to ensure that the received signal has the desired power level, and that stability problems must be kept within the dynamic range of the receiving device (A / D converter) by ensuring that the amplitude of the information signal is within a certain reference level. Consideration should be given.

In addition, AGC adjusts the gain to a certain amount regardless of the interference noise signal coming from the surroundings, and therefore, it is not possible to immediately respond to a change in the power level of the interference noise for interference noise such as a large amplitude impulse signal. Errors caused by sudden ingress or destruction cannot be handled.

For example, if only an information signal source comes in during the initialization of the system, the AGC adjusts the gain based on the received information signal. In this case, when an interference noise signal having a power equivalent to that of the original signal is suddenly introduced, the power of the entire signal is doubled. Thus, the original signal is clipped in the process of A / D conversion, thereby quantizing error. ) Will occur.

In addition, when the receiver receives strong narrowband interference noise, such as impulse interference noise, to the wireless transmission line, the performance of the system may be degraded. Therefore, the receiver may not meet the originally designed system performance. The operation of the receiver becomes unstable and the transmission data cannot be detected.

Even more problematic is that large-band interference noise can not be adaptively eliminated because it is impossible to predict when and at which frequency band narrow-band interference noise will be applied. Adjust the level carefully so that it becomes the input of the A / D converter by adjusting the level to the appropriate level.

In addition, the digital down converter (DDC) 102 is a baseband capable of processing data of the IF band digitized by the A / D converter 100 by a standard digital signal processor (DSP). It converts data to frequency, performs decimation, narrowband lowpass filtering, gain reduction, resampling, and polar transformations.

That is, IF input data sampled with a resolution of 12 bits (Bits) is converted to baseband by a digital mixer and a negatively controlled oscillator (NCO), and the decimation is a CIC filter (4). 32: 5th) (Cascaded Integrator Comb), which is capable of up to 5 decimates by a halfband filter, followed by a programmable 255 Finite Impulse Response (FIR) filter. Will follow. Output data from the FIR filter is scaled by digital AGC before being resampled in a polyphase FIR filter.

The adaptive interference noise control unit 104 is composed of a CPU, an MPU, or a digital signal processor (DSP) and various peripheral circuits, and performs self-regression on the received narrowband interference noise signal component. Digital signal processing and adaptive compensation algorithms using autoregressive and real time adaptive algorithms eliminate and suppress narrowband interference noise included in CDMA information signals and control the final output within a certain reference range. Perform the function.

The general functions of the digital up-converter 106 and the D / A converter 108 perform the inverse functions of the digital down-converter 102 and the A / D converter 100, and the sampling rate of the D / A converter 108 Rate) is set higher than the sampling rate of the A / D converter 100 to improve conversion efficiency.

In this case, when the A / D converter 100 converts the analog signal of the FA frequency selected from the FA of the line divided / assigned into a constant frequency band according to the frequency allocation rule of the CDMA system into a digital signal, After removing and suppressing the band interference noise signal component, the digital signal shall be rearranged in FA order by adding an ADD or MUX function for synthesizing the signal in each FA unit according to the frequency allocation regulation.

The A / D converter 100, the DDC 102, the adaptive interference noise control unit 104, the DUC 106, and the D / A converter 108 to perform unique functions as described above are each functional single component. It can be developed by applying it as a part, or it can be developed as Field Programmable Gate Array (FPGA) and ASIC (Integrated Circuit).

In addition, the light and short functional module can be applied to various fields and can be applied to all systems to which future CDMA technology is applied, as well as existing CDMA and personal mobile communication (PCS) systems.

2 is a diagram illustrating an embodiment of the adaptive interference noise controller of FIG. 1 according to the present invention.

The adaptive interference noise control unit 104 includes a first comparison analyzer 200 (FIG. 3), an interference noise controller 204 (FIG. 4), an adaptive compensation filter 206 (FIG. 4), and a second comparison analyzer 208. (FIG. 5), which will be described in FIGS. 3 to 5.

3 is a diagram illustrating an embodiment of a first comparative analysis unit of FIG. 2 according to the present invention.

The first comparative analysis unit 200 is composed of an absolute value and the average value calculator (ABS) 300 and a signal detection and control signal generator 302, the main functions and functions of the CPU, MPU or digital signal processor (Digital Signaling Processor) In this case, the digital down converter (DDC) 102 may perform a part of a function or, if necessary, the operation process as follows.

In the digital output signal of the A / D converter 100 and the DDC 102, the absolute value calculator 300 obtains the absolute value of the digitally converted signal. The reason for obtaining the absolute value is that the output values of the A / D converter 100 and the DDC 102 should be within a constant amplitude level rather than having a constant power level. For example, if the square value is used to have a constant power level, it is advantageous to use an absolute value since a value greater than 1 becomes larger and a value smaller than 1 becomes smaller.

The average calculator 300 is located at the rear end of the absolute value calculator 300, sets a predetermined window for the output of the absolute value calculator, obtains a peak value from the samples in each window, and then obtains a predetermined number of windows in each window. Average the peaks. The reason for obtaining the peak value is to ensure a stable output that operates within a constant amplitude level, and is for general information processing for adjusting the final output level of the narrowband interference noise control device. The size of the window is adjustable and the average of the peaks is intended to be insensitive to noise.

The signal detection and control signal generator 302 detects the level of the output of the average calculator 300 to adjust the final output level of the narrowband interference noise control device, and stores the reference level, the upper limit threshold, and the lower limit threshold in advance. After analyzing the predicted value which needs to adjust the current gain and the final output level in comparison with the maximum value and the minimum value, the output of the average value calculator 300 sensed through the first output is sent to the interference noise controller 204, and 2 outputs a control signal for adjusting the final output level of the narrow-band interference noise control device according to the comparison / analysis result and outputs it to the second comparison analysis unit (208).

4 is a diagram illustrating an embodiment of the interference noise controller and the adaptive compensation filter of FIG. 2 according to the present invention.

The interference noise controller 204 and the adaptive compensation filter 206 are the combiner 406, 408, the divider 410, 412, the adaptive interference cancellation filter 404, the adaptive compensation filter 400, and the adaptive compensation algorithm 402. It consists of.

In the application of an algorithm for minimizing the error signal that asymptotically converges to the information signal, it is the most ideal system when the error signal is gradually approached to "0" and "0" is achieved. However, errors exist in all systems, and system stability is a problem due to errors. Therefore, adding a compensation circuit in order to reduce the output error of the system due to the received narrowband interference noise signal component can give an output error and improve the convergence function.

The interference noise controller 204 and the adaptive compensation filter 206 may be composed of a central processing unit (CPU), a microprocessor (MPU) or a digital signal processor (DSP) and various peripheral circuits, and receive narrowband interference noise. The digital signal processing method using the autoregressive and least squares average (LMS) algorithm and the adaptive compensation algorithm perform the functions of eliminating and suppressing narrowband interference noise included in the CDMA information signal.

The main function of the first combiner 406 is the output signal Z _k of the first comparison analyzer 200 and the estimated output value of the adaptive interference cancellation filter 404 ( And combines the backward feedback signal of) to generate the output error value ε _k .

The output error value of the first combiner is adapted to be the minimum mean square value by the CLMS algorithm and the second combiner 408 is an estimate of the output error value ε _k of the first combiner 406 ( ) And an output estimate of the adaptive interference cancellation filter 404 ( Of the feedback feedback signal of the Is generated, and the output error value ε _k of the first combiner 406 serves as an input of the adaptive compensation filter 400.

In addition, the output V _k of the adaptive compensation filter 400 acts on the adaptive compensation least squares average algorithm (CLMS Algorithm) 402 to generate a weighting coefficient function of the adaptive interference cancellation filter and the adaptive compensation filter, thereby adaptive interference cancellation. The values of the filter and adaptive compensation filter are adapted at each sampling instant.

Accordingly, the output of the adaptive interference cancellation filter 404 is adaptively changed and output at each sampling moment, and the output value is backward feedback coupled to the first combiner 406 so that the square mean value of the output error of the first combiner is minimized. Adaptive operation

The adaptive algorithms applied to the interference noise controller 204 and the adaptive compensation filter 206 are divided into two, and the first algorithm is the least square average (LMS) algorithm applied to the adaptive interference cancellation filter 404 of FIG. The second algorithm is an adaptive compensation algorithm applied to the adaptive compensation filter 206 of FIG. 8, and the two algorithms are collectively referred to as a Compensated Adaptive LMS Algorithm (CLMS algorithm) 402.

Here, the adaptive compensation algorithm is called the adaptive compensation algorithm because it is related to the adaptive compensation filter, and the basic structure and function of the algorithm is generally similar to the verified least square average (LMS) algorithm.

The two algorithms have similar characteristics and shapes, and adjust the adaptive weighting coefficient of the adaptive interference cancellation filter 404 and the adaptive weighting coefficient of the adaptive compensation filter 208 by applying the output of the adaptive compensation filter 400. do.

In addition, the CLMS algorithm 402 removes the interference noise signal by minimizing the output estimation error signal of the adaptive compensation filter 400 and outputs only the desired information signal. In other words, the output estimation error signal converges to the desired information signal.

A detailed configuration diagram of the adaptive noise canceling filter (ANF) 404 is shown in FIG. 7, and an input signal of the adaptive interference canceling filter is adaptive weighting factor function (a _i ) to a time delayed signal by a time delay having a size T _{c. , k} ) can be modeled through a finite impulse response filter (FIR filter), an infinite impulse response filter (IIR filter), and an adaptive filter in the form of various other digital filters. ((Equation 2) in the description of FIG. 7).

The detailed configuration diagram of the adaptive compensation filter 400 is illustrated in FIG. 8, and an input signal of the adaptive compensation filter is primarily an output signal processed by the adaptive interference cancellation filter 404 and an output of the first comparison analyzer. The signal Z _k is combined (406) and output as an error signal, which is time-delayed and processed by a time delay of size T _c in the adaptive compensation filter. The input signal of the adaptive compensation filter 208 has a time delay of magnitude T _{c and} a finite impulse response filter (FIR filter) multiplied by the adaptive weighting factor function c _{i, k} of the adaptive compensation filter, infinite. It can be modeled through an Infinite Impulse Response Filter (IIR Filter) and other digital adaptive filters (see Equation 3 in the description of FIG. 8).

The adaptive compensation filter 400 has a main purpose of eliminating the vibration convergence and the interference noise cancellation function of the adaptive interference cancellation filter, and adds it to the output of the adaptive interference cancellation filter.

As described above, the output signals of the interference noise controller 204 and the adaptive compensation filters 206 and 400 of FIG. 4 including the adaptive interference cancellation filter 404 and the adaptive compensation filter 400 are transmitted to the CLMS algorithm 402. Signal processing is performed according to the above process, and the narrowband interference noise signal component received by the above process is removed and suppressed to output only necessary CDMA information signals.

5 is a configuration diagram of an embodiment of a second comparative analysis unit of FIG. 2 according to the present invention.

The second comparison analyzer 208 includes a gain analyzer 500 and a gain adjuster 502. The main functions and functions are centralized in a CPU, an MPU, or a digital signal processor (DSP), and digitally upward as necessary. The converter (DUC) 106 may perform some of the functions, and the detailed functional operations of the second comparison analyzer 208 are as follows.

The input of the gain analyzer 500 is composed of the output of the adaptive compensation filter of FIG. 4 and the output of the signal detection and control signal generator 302 of the first comparison analyzer 200.

The function and operation of the gain analyzer 500 and the gain adjuster 502 are not clearly separated from each other, mutual functions and operations are made by mixing, the main function is for gain control of the first comparison analyzer 200 Gain control is performed to output an output value according to the final output level set in FIG. 6 using the control signal and the output of the adaptive compensation filter 206.

In other words, the signal level between the upper and lower thresholds is lowered below the upper threshold and the signal level between the lower and minimum thresholds is adjusted above the lower threshold and the upper limit is adjusted.The final output level is centered on the reference level. In this way, the gain is appropriately adjusted so as to exist within the upper limit threshold and the lower limit threshold.

6 is an explanatory diagram of an output level adjustment function compared to a reference level applied to the present invention, and shows a final output model of a narrowband interference noise control device.

The final output of the narrowband interference noise control device is gain adjusted to output the output value according to the final output level set in the CDMA system to which it is mounted. In other words, the signal level between the upper limit threshold and the maximum value is lowered below the upper limit threshold, and the signal level between the lower limit threshold and the minimum value is adjusted by the upper limit of the gain above the lower limit threshold, and the final output level is centered on the reference level. Adjust the gain appropriately so that it is within the upper and lower thresholds.

If the signal level input to the narrowband interference noise control device exceeds the maximum set by the CDMA system in which it is mounted (the A / D conversion dynamic range of the A / D converter), the A / D converter As a result, a saturation error occurs, which tends to degrade the performance of the entire system.

Therefore, it is necessary to adjust the level of the signal so that the input signal overflowed for the stabilization of the system can exist within the dynamic range of the A / D converter.

In general, the signal level in the CDMA system can set the system output level or system connection level at each connection point, module unit, unit unit, and can also variously adjust the signal level according to the mounting position of the present invention.

As an example, an output signal level based on a connection point of a low noise amplifier (LNA) module of a CDMA receiving system may be modeled as follows. That is, the value of +/- 40dBm is set as the upper limit maximum value and the lower limit minimum value based on the reference level 0dBm, and the value exceeding this range is processed by the overflow (Over Flow) to perform the gain control.

In addition, the output threshold level of the system is set to +/- 20dBm based on the reference level (0dBm) so that each value has a dynamic output range of 40dBm using the upper and lower thresholds. Therefore, when the signal output level exists between the maximum value and the upper limit threshold and between the minimum value and the lower limit threshold, gain control is performed so that the level of the output signal is within the dynamic output range.

7 is a diagram illustrating an embodiment of the adaptive interference cancellation filter of FIG. 4 according to the present invention.

Detailed schematic diagram of an adaptive interference filter (ANF) 404, comprising a combiner 700, 702, a time delay 704, and a plurality of multipliers 706.

The third combiner 700 is a coupler that performs the same function as the second combiner 408 of FIG. 4, and estimates the output error value ε _k ( ) And Output Estimation of Adaptive Interference Cancellation Filter The feedback signal of the feedback signal coupled to the input of the adaptive interference cancellation filter 404 ).

The adaptive interference cancellation filter uses its input signal ( ) Is time-delayed by a time delay of size T _c , and multiplied by an adaptive weighting factor function (a _{i, k} ) produced by the adaptive transfer function of the CLMS algorithm to remove interference noise. It can be modeled as a digital adaptive filter consisting of a Finite Impulse Response Filter or an Infinite Impulse Response Filter (IIR), and the fourth combiner 702 adds the entirety of the output modeled by the digital adaptive filter. The backward feedback output to the third combiner 700, the adaptive weighting coefficient algorithm is as shown in Equation (2).

Where a _k is the adaptive weighting coefficient function, μ _a is the adaptive weighting coefficient, γ _{k, a} is the input power estimation function of the adaptive interference cancellation filter, ρ (ε _k ) is the transfer function of the adaptive interference cancellation filter, and Z _k is adaptive Estimated input vector function of the interference cancellation filter.

The adaptive weighting coefficient function of Equation (2) is corrected and supplemented at the sampling moment, and the adaptive weighting coefficient acts in a direction to reduce the difference (error) between the received signal and the output value, and thus the CLMS algorithm. Satisfy. That is, the purpose of the weight function is to minimize the final output error and to minimize the mean square value of the error.

8 is a diagram illustrating an embodiment of the adaptive compensation filter of FIG. 4 according to the present invention.

Adaptive Compensated Filter 206, 400 consists of combiners 802, 804, time delay 800, and multiple multipliers 806.

The fifth coupler 802 is the output error value ε _k of the first coupler 406 of FIG. 4 and the output value of the sixth coupler 804 in the adaptive compensation filter ( Combined with the backward feedback of), it produces an error output (V _k ).

The adaptive compensation filter 400 estimates the error output of the fifth combiner 802 ( ) Is time-delayed by the time delay device 800 of size T _c and multiplied by the adaptive weighting coefficient function C _{i, k} produced by the adaptive transfer function of the CLMS algorithm 402 (806). ), A digital adaptive filter composed of a finite impulse response filter (FIR filter) or an infinite impulse response filter (IIR filter) that compensates for interference noise.

The sixth combiner 804 adds the entirety of the output modeled by the digital adaptive filter and outputs the backward feedback to the fifth combiner. The adaptive weighting coefficient algorithm is expressed by Equation 3 below.

That is, FIG. 8 is a detailed configuration diagram of the adaptive compensation filter 400 applied to the output terminal. The input signal of the adaptive compensation filter is primarily an output signal processed by the adaptive interference cancellation filter 404. ) And the input signal Z _k (output signal of the first comparison analyzer) of FIG. 4 are combined (406) and output as an error signal (ε _k ), which is time-delayed by a time delay of size T _c in the adaptive compensation circuit. do.

Where c _k is the adaptive weighting coefficient function, μ _c is the adaptive weighting coefficient, γ _{k, c} is the input power estimation function of the adaptive compensation filter, ν _k is the output estimation function of the adaptive compensation filter, and E _k is the estimation of the adaptive compensation filter. Input vector function.

The adaptive weighting coefficient function of the adaptive compensation filter of Equation 3 is corrected and supplemented at the sampling instant in the same manner as the adaptive weighting coefficient function of the adaptive interference cancellation filter of Equation 2, and the adaptive compensation filter is adaptive. The weighting factor satisfies the LMS algorithm by acting to reduce the difference between the received signal and the added value.

That is, the purpose of the weight function of the adaptive compensation filter is to minimize the error value of the output signal through the adaptive compensation filter and minimize the mean square value of the error.

The adaptive compensation filter 400 has a main purpose of eliminating the vibration convergence and the interference noise canceling function of the adaptive interference cancellation filter 404, and is added to the output of the adaptive interference cancellation filter 404.

9 is a flowchart illustrating a narrowband interference noise control method using an adaptive compensation algorithm in a code division multiple access system according to the present invention.

Since the detailed description has already been made in the relevant part, the overall method will be described here (see FIGS. 1 to 8).

Receives an RF / IF analog signal containing CDMA information and converts it into a digital signal (900), selects a desired FA from the A / D converted signal that is converted to an appropriate sampling rate in the IF band and quantized. In operation 902, the digital signal of the selected IF band is converted to the baseband and decimated from 1/4 to 1/8 to facilitate digital processing of the oversampled signal.

Thereafter, autoregressive and least squares average (LMS) algorithms and adaptive compensation algorithms are used to remove and suppress narrowband interference noise signal components and control the final output within a predetermined reference range (904).

Then, the output signal converted to baseband and decimated from 1/4 to 1/8 to remove or suppress narrowband interference noise signal components is restored to the original RF / IF signal and interpolated. After 906, the upconverted digital signal is converted into an initially received analog RF / IF signal.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by.

The present invention as described above has the following excellent effects.

First, the adaptive compensation least square average (CLMS) algorithm is applied to the narrowband interference noise signal component from the outside in the system using the CDMA technology, thereby improving the efficiency of eliminating and suppressing the narrowband interference noise signal component. And smooth transmission of the CDMA information signal.

Second, by minimizing the output error by the adaptive compensation algorithm to maintain a constant level of the output signal can increase the stability and efficiency of the system.

Third, since the interference noise signal components are removed before despreading, the efficiency of interference noise cancellation can be improved and various scattered interference noise canceling functions can be centralized.

Fourth, it is possible to prevent an error due to a change in power level due to sudden input of a large level of interference noise, and to prevent a system failure due to a large power signal input.

Fifth, it is possible to prevent quality degradation and call disconnection of subscriber information caused by narrowband interference noise signal components.

Sixth, proper gain control can be performed to stabilize the output level of an irregularly changed reception signal.

Seventh, it is possible to shorten the steady state convergence time and minimize the steady state error signal by adjusting the values of the adaptive compensation least square mean (CLMS) algorithm and the adaptive coefficient by autoregression.

Eighth, after reaching a steady state, the signal can be traced in detail and quickly responded to sudden power changes in the received signal.

Secondly, the interference caused by the narrowband interference noise can be prevented by removing the narrowband interference noise signal component that is mixed and received in the original transmission signal in a specific frequency band.

Tenth, it is the development of the first step of the SDR (Software Defined Radio) technology, which is expected to be used in the future information and wireless communication, can be applied as a basic technology of the future wireless communication system.

Eleventh, by narrowing down the narrowband interference noise canceller, it can be applied to a CDMA system and a repeater system.

Secondly, it can be applied to a terminal by light and short reduction of the module.

Thirteenth, due to the CDMA technical characteristics using the wideband spreading scheme, the CDMA frequency can be newly used and the frequency utilization efficiency can be improved by overlapping with the narrowband frequency already in use.

Fourteenth, it can be applied to cellular and PCS systems, IMT-2000 systems, and CDMA technologies that are currently commercially available.

Claims (10)

An interference noise control apparatus applied to a code division multiple access system, Analog-to-digital (A / D) conversion means for converting the received analog signal into a digital signal; Digital downconversion means (DDC) for converting the converted digital signal into a baseband signal; Autoregressive, least mean square (LMS) algorithms and adaptive compensation algorithms are used to remove narrowband interference noise signal components from the transformed baseband signal and to bring the final output into a predetermined reference range. Adaptive interference noise control means for controlling; Digital upconverting means (DUC) for converting the digital signal from which the narrowband interference noise is removed into a digital upconverting frequency band signal; And Digital-to-analog (D / A) converting means for converting the converted digital upconverted frequency band signal into an analog signal Narrowband interference noise control device using an adaptive compensation circuit comprising a. The method of claim 1, The adaptive interference noise control means, First comparing and analyzing means for generating a control signal by obtaining an average value of the digital output signal of the digital down-converting means and comparing the predetermined reference values with respect to the output of the digital-to-analog (D / A) converting means; Interference noise control and compensation means for controlling narrowband interference noise signal components from the transformed baseband signal using an autoregressive, least square average (LMS) algorithm, and an adaptive compensation algorithm; And Second comparative analysis means for adjusting the output of the interference noise control and compensation means according to the control signal of the first comparative analysis means Narrowband interference noise control device using an adaptive compensation circuit comprising a. The method of claim 2, The first comparative analysis means, An absolute value and an average value calculating means for obtaining an absolute value of the digital output signal of the digital downconverting means, setting a predetermined window to obtain a peak value among sampling values, and calculating an average of the peak values obtained in each window; And After sensing the output of the absolute value and the average value calculation unit and comparing it with predetermined reference values for the output of the digital-to-analog (D / A) converting means, the output of the detected absolute value and average value calculation unit is the interference Signal detection and control signal generation means for transmitting to the noise control and compensation means, and to generate the control signal according to the comparison result and to the second comparison analysis means Narrowband interference noise control device using an adaptive compensation circuit comprising a. The method according to any one of claims 1 to 3, The interference noise control and compensation means, First combining means for obtaining an error signal between an output signal of the first comparison analysis means and an estimated output value of the adaptive interference cancellation filtering means; The output value of the adaptive compensation means is fed back to obtain an error output with the output of the first coupling means, and then delayed, and then combined with the first adaptive weighting coefficient function generated by the adaptive weighting factor generating means to compensate for interference noise. The adaptive compensation means for removing the; Second combining means for feeding back an estimated output value of the adaptive interference cancellation filtering means and combining it with an estimated value of an error signal of the first combining means to generate an input value of the adaptive interference cancellation filtering means; The adaptive weighting coefficient generating means for generating a first adaptive weighting coefficient function for the adaptive compensation means and a second adaptive weighting coefficient function for the adaptive interference cancellation filtering means by square-averaging the output value of the adaptive compensation means; ; And The adaptive interference elimination filtering means for eliminating interference noise in combination with the generated adaptive weighting factor function after delaying the output of the second combining means Narrowband interference noise control device using an adaptive compensation circuit comprising a. The method of claim 4, wherein The adaptive weighting coefficient function generating means, An apparatus for controlling narrowband interference noise using an adaptive compensation circuit, which generates an adaptive weighting coefficient function using a least mean square (LMS) algorithm. An interference noise control method applied to a narrowband interference noise control apparatus in a code division multiple access system, A first step of converting the received analog signal into a digital signal; Converting the converted digital signal into a baseband signal; A method for controlling narrowband interference noise signal components from the transformed baseband signal using autoregressive, least square average (LMS) algorithms, and adaptive compensation algorithms, and controlling the final output within a predetermined reference range. Three steps; A fourth step of converting the digital signal from which the narrowband interference noise has been removed into a digital upconversion frequency band signal; And A fifth step of converting the converted digital up-converted frequency band signal into an analog signal Narrowband Interference Noise Control Method Using Adaptive Compensation The method of claim 6, The third step, A sixth step of obtaining an average value of the baseband digital signal of the second step and then generating a control signal by comparing the predetermined reference values with respect to the final output; A seventh step of optimally controlling narrowband interference noise signal components from the transformed baseband digital signal using an autoregressive, least square average (LMS) algorithm, and an adaptive compensation algorithm; And An eighth step of adjusting the output of the seventh step according to the control signal of the sixth step Narrowband interference noise control method using adaptive compensation comprising a. The method of claim 7, wherein The sixth step, A ninth step of obtaining an absolute value of the baseband digital signal, setting a predetermined window to obtain a peak value among sampling values, and obtaining an average of peak values obtained from each window; And A tenth step of sensing the average value output of the ninth step and generating the control signal according to a comparison result with predetermined reference values for the final output stored therein; Narrowband interference noise control method using adaptive compensation comprising a. The method according to any one of claims 6 to 8, The seventh step, An eleventh step of obtaining an error signal between the average value output of the ninth step and the estimated output value of the adaptive interference cancellation filtering means; Generating a first adaptive weighting coefficient function for the adaptive compensation means and a second adaptive weighting coefficient function for the adaptive interference cancellation filtering means by square-averaging the output value of the adaptive compensation means; A thirteenth step of feeding back the estimated output value of the adaptive interference elimination filtering means to obtain a combined signal with the estimated value of the error signal of the eleventh step and delaying it, and then combining the second adaptive weighting factor function to remove the interference noise; ; And A fourteenth step of feeding back the output value of the adaptive compensation means to obtain an error signal with the error signal of the eleventh step and delaying it, and then combining the first adaptive weighting coefficient function to compensate for interference noise Narrowband interference noise control method using adaptive compensation comprising a. In a narrowband interference noise control device having a processor for controlling narrowband interference noise in a code division multiple access system, A first function of converting the received analog signal into a digital signal; A second function of converting the converted digital signal into a baseband signal; A method for controlling narrowband interference noise signal components from the transformed baseband signal using autoregressive, least square average (LMS) algorithms, and adaptive compensation algorithms, and controlling the final output within a predetermined reference range. 3 functions; A fourth function of converting the digital signal from which the narrowband interference noise is removed into a digital upconversion frequency band signal; And A fifth function of converting the converted digital upconversion frequency band signal into an analog signal A computer-readable recording medium having recorded thereon a program for realizing this.