KR20020036391A - Apparatus and method for synchronizing phase of carrier wave - Google Patents

Abstract

PURPOSE: A method for synchronizing a phase of a carrier wave and an apparatus are provided to perform a non-linear process of an input signal by depressing an uncertain phase component of the vicinity of a zero point. CONSTITUTION: A matching filter(102) recovers a wave of a received signal which is downward converted into a base band. A non-linear section(104) performs a non-linear amplifying operation with respect to an amplitude and a phase of an input signal. The non-linear section(104) includes a continuous judging section. The continuous judging section compares an amplitude of the input signal with a threshold value and grants a weight according to the threshold value. An adder(106) adds non-liner amplified components for an estimated symbol period. A rotating amount calculator calculates a rotating amount of a phase based on the added value.

Description

Apparatus and method for synchronizing phase of carrier wave}

The present invention relates to Viterbi & Viterbi, which is a carrier phase synchronization technique using nonlinearity, and more particularly, a nonlinear process of an input signal size during a nonlinearization process of a phase estimator input signal is performed by a soft determiner. The present invention relates to a carrier phase synchronization method and apparatus using a soft decision nonlinearizer.

Conventional techniques related to phase estimation techniques using nonlinearities are described in a paper published by Andrew J. Viterbi and Audrey M Viterbi (IEEE, July 1983, P544).

1 is a block diagram of a conventional Viterbi & Viterbi phase estimation algorithm.

The conventional phase estimator adds a non-linear amplified component 20 for multiplying the magnitude of the signal output from the matched filter 10, the matched filter 10 at the receiving end, and non-linear amplifying the phase, and the non-linear amplified component for the estimated symbol interval. The unit 30 includes a rotation amount calculation unit 40 for calculating the rotation amount of the phase from the added value to perform phase synchronization of the carrier wave.

In the conventional phase estimator, the received signal down-converted to the baseband is reconstructed by the matching filter 10, and then only the optimum sample point is input to the nonlinearization unit 20.

Then, the magnitude and phase of the signal input to the nonlinearization unit 20 undergoes a nonlinearization process.

The nonlinearization unit 20 includes a power unit 22 and a multiplier 24, and the magnitude component of the signal is multiplied by an arbitrary integer L through the power unit 22, so that the signal amplitude is non-linearly amplified. .

In addition, the phase component is multiplied by an arbitrary integer M through the multiplier 24. The arbitrary integer M is the alphabet size of the modulation scheme, and this process removes the modulation components of the nonlinearizer input signal.

The output signal of the nonlinearization unit 20 is input to the adder 30, and is further divided into I and Q components and added for each component during the estimation period P. Here, P represents an estimation section.

The phases of the added I and Q components are estimated during the estimation period, and finally, the amount of rotation of the phase is estimated by dividing by the integer (M) multiplied by the phase nonlinear process.

As described above, in the conventional phase estimator, a large multiplier is used to multiply the magnitude of the input signal input to the nonlinearizer. Therefore, there is a problem in that the conventional phase estimator is implemented in hardware and becomes very complicated and its size becomes very large.

Accordingly, an object of the present invention is to provide a carrier phase synchronization method for performing phase synchronization of a carrier by suppressing an uncertain phase component of a near zero component by using a soft determiner using a comparator and a weight assigning unit. To provide a device.

1 is a block diagram of a conventional Viterbi & Viterbi phase estimation algorithm.

2 is a block diagram of a general phase estimation and compensator.

3 is a block diagram of a phase estimation algorithm in accordance with the present invention.

4 is a diagram illustrating a PDF (Probability Density Function) of a signal when the quantization level is two.

FIG. 5 is a diagram illustrating a PDF (Probability Density Function) of a signal when the quantization level is 2. FIG.

Accordingly, in order to achieve the above object, a non-linear unit for soft-determining the magnitude of the output signal received through the matching filter of the receiving end and non-linear amplification of the phase; An adder for adding the nonlinear amplified components during the estimated symbol interval; And a rotation amount calculator for calculating a rotation amount of the phase from the added value.

In order to achieve the above object, a carrier phase synchronization method comprising: a non-linearity step of softly determining the magnitude of an output signal received through a matching filter of a receiver and non-linear amplifying a phase; An addition step of adding the nonlinear amplified components during the estimated symbol interval; And calculating a rotation amount of the phase from the added value. A carrier phase synchronization method is provided.

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

2 is a block diagram of a general phase estimation and compensator.

In FIG. 2, the input signal is converted into a digital signal by the sampler 52, and the signal passes through the matching filter 54 to restore the waveform.

Compensates for the distortion caused by the time delay between the transmitter and receiver by STR 56 (Symbol Timing Recovery), and the phase measurer 58 measures and calculates the phase from this signal and then post-processor 62 Is driven to compensate the phase with the calculated value (64).

At this time, since a time for calculation is required, the time difference between the sample and the phase value to be compensated by delaying the time using the buffer 60 is matched.

3 is a block diagram of a phase estimation algorithm in accordance with the present invention.

In the phase estimator according to the present invention, the received signal down-converted to the baseband is reconstructed by the matching filter 102 and then only the optimal sample point is input to the nonlinearizer 104 through various synchronizations.

The signal input to the nonlinearization unit 104 undergoes a nonlinearity in the magnitude and phase of the signal.

Here, the nonlinearity of the signal size is softly determined by the soft determiner 11.

Therefore, the phase estimation algorithm according to the present invention, unlike the conventional phase estimation algorithm structure shown in FIG. 1, reduces the hardware complexity by using the soft decision structure, and when an integer (L) value that is a power factor increases Performance improvement occurs compared to

4 is a diagram illustrating a PDF (Probability Density Function) of a signal when the quantization level is two.

Herein, when the signal-to-noise ratio (Eb / No) of the channel is 10 dB, the PDF (Probability Density Function) of the received signal is present from about 0.8. The threshold value is the value at which the Probability Density Function (PDF) of the signal begins to exist.

The threshold is used to determine the critical section. That is, the weight is set to 0 when the magnitude of the nonlinearizer input signal is 0 to 0.8, and is assigned to 1 when the size of the nonlinearizer input signal is 0.8 or more.

FIG. 5 is a diagram illustrating a PDF (Probability Density Function) of a signal when the quantization level is 2. FIG.

Herein, when the signal-to-noise ratio (Eb / No) of the channel is 20 dB, the PDF (Probability Density Function) of the received signal exists from about 1.2. The threshold value is the value at which the Probability Density Function (PDF) of the signal begins to exist.

The threshold is used to determine the critical section. That is, the weight is set to 0 when the magnitude of the nonlinearizer input signal is 0 to 0.8, and +0.5 when the magnitude is 0.8 to 1.2. And if it is 1.2 or more, it is allocated as +1.

On the other hand, the non-linearization of the signal phase is multiplied.

The phase component is multiplied by an arbitrary integer M through the multiplier 112. The arbitrary integer M is the alphabet size of the modulation scheme, and this process removes the modulation components of the nonlinearizer input signal.

The output signal of the nonlinearizer 104 is input to the adder 106, and is further divided into I and Q components and added for each component during the estimation period P. FIG. Here, P represents an estimation section.

The phases of the added I and Q components are estimated during the estimation period, and finally, the amount of rotation of the phase is estimated by dividing by M multiplied by the phase nonlinear process.

The present invention is not limited to the above-described embodiments, and of course, modifications can be made by those skilled in the art without departing from the spirit of the present invention. Therefore, the scope of the claims in the present invention will not be defined within the scope of the detailed description, but will be limited to the claims below.

According to the present invention, by using a soft decision structure instead of the conventional descent process, there is an advantage of reducing the hardware burden by a large multiplier, and it is possible to effectively suppress the uncertain phase component near the zero which is an original function of the conventional descent process.

The resultant performance is the same as compared with the conventional structure, or if the squared value (L) is large can be improved performance.

Claims (8)

In the carrier phase synchronization device, A non-linear unit for softly determining the magnitude of the output signal received through the matching filter of the receiver and non-linear amplifying the phase; An adder for adding the nonlinear amplified components during the estimated symbol interval; And And a rotation amount calculator for calculating a rotation amount of the phase from the added value. The method of claim 1, And the nonlinear amplifier includes a soft determiner for comparing the magnitude of the input signal with a threshold value and assigning a weight according to the threshold value. The method of claim 2, And the soft determiner adjusts a threshold value and a quantization level according to a signal-to-noise state of a channel, assuming a QPSK modulation scheme. The method of claim 3, wherein And the threshold value is a value at which a PDF of a signal starts to exist based on a case where signal-to-noise ratios of the channels are 10 dB and 20 dB. In the carrier phase synchronization method, A nonlinear step of softly determining the magnitude of the output signal received through the matching filter of the receiver and nonlinearly amplifying the phase; An addition step of adding the nonlinear amplified components during the estimated symbol interval; And Computing the amount of rotation of the phase from the added value; carrier phase synchronization method comprising a. The method of claim 5, And the non-linearization step includes a soft determiner for comparing the magnitude of the input signal with a threshold value and assigning a weight according to the threshold value. The method of claim 6, And the soft determiner adjusts a threshold value and a quantization level according to a signal-to-noise state of a channel, assuming a QPSK modulation scheme. The method of claim 7, wherein The threshold value is a carrier phase synchronization method, characterized in that the PDF starts to exist on the basis of the signal-to-noise ratio of the channel 10dB and 20dB.