KR20000003241A - Viterbi interface device of wireless subscriber network - Google Patents

Abstract

PURPOSE: A viterbi interface device of wireless subscriber network is provided to increase the efficiency of double signalizing. CONSTITUTION: A viterbi interface device of wireless member network comprises: a critical value voltage control device(410) for controlling the critical value voltage of the 1st and 2nd channel signal delivered from a transmission terminal; a limiting device(420) for limiting the critical value voltage of the 1st and 2nd channel signal escaped from a standard range, inputted the 1st and 2nd channel signal from the critical value voltage control device; a fan-shaped quantizing device(430) for spirally reducing the bit number of the 1st and 2nd channel signal outputted from the limiting device; a non-spiral shaped quantizing device(440) for reducing the 1st and the 2nd channel signal outputted from the spiral quantizing device.

Description

Viterbi interface device at receiving end of wireless subscriber network

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Viterbi Interface (Viterbi Interface) device of a receiving end of a wireless subscriber network, and more particularly, to quantize a signal received from a transmitting end of a wireless subscriber network using a code division multiple access (CDMA) scheme. A Viterbi interface device.

1 is a block diagram of a receiving end of a typical wireless subscriber network.

As shown in FIG. 1, the receiving end of a typical wireless subscriber network includes a correlator 110, a channel estimator 120, a channel compensator 130, a derepeater 140, a signal combiner 150, And a Viterbi interface 160, a deinterleaving unit 170, and a Viterbi decoder 180.

Referring to the operation of the demodulation system of a general wireless subscriber network having the structure as described above is as follows.

When the signal of the channel is transmitted from the transmitting end to the correlator 110 and the channel estimator 120, the correlator 110 multiplies the signal of the transmitted channel with a predetermined pseudo random number sequence and then integrates the multiplied result value. Determining a signal that matches the code of the user using the to output the signal corresponding to the code of the channel to the channel compensator 130. In addition, since the phase and amplitude of the channel signal are distorted in the process of being transmitted from the transmitting end to the receiving end, the channel estimator 120 estimates the phase and amplitude of the channel signal before the distortion through the transmitted channel signal. The phase and amplitude estimates of the signal are passed to the channel compensator 130.

Subsequently, the channel compensator 130 compensates the phase and amplitude of the channel signal transmitted from the correlator 110 according to the phase and amplitude estimation values of the channel signal transmitted from the channel estimator 120 and outputs the same to the inverse repeater 140. . Since the transmitter repeats the signal several times and transmits the signal to the receiver, the inverse repeater 140 receives the output signal of the channel compensator 130 and restores the repeated symbol to the symbol before it is repeated and outputs it to the signal combiner 150. . In this case, the recovered symbol has a wide dynamic range according to channel conditions, power control, and interference between users. As such, the channel signal transmitted through the multipath from the transmitter to the signal combiner 150 of the receiver is combined by the signal combiner 150 and transmitted to the Viterbi interface 160.

The Viterbi interface 160 rounds the channel signals of the plurality of bits thus rounded to make the channel signals of the predetermined bits, quantizes the channel signals of the predetermined bits, and forms a signal suitable for the Viterbi decoder 180. The conversion is output to the deinterleaving unit 170.

In order to prevent a channel signal aggregation error, the transmitting end interleaves the data of the channel signal and transmits the data to the receiving end. In this way, the data of the rearranged channel signals through the interleaving process is de-interleaved by the deinterleaving unit 170. The data are deinterleaved and passed to the Viterbi decoder 180. Subsequently, the Viterbi decoder 180 decodes and outputs the channel signal encoded and transmitted by the transmitter.

FIG. 2 is a block diagram of the Viterbi interface of FIG. 1.

As shown in FIG. 2, the Viterbi interface of the receiver of the conventional wireless subscriber network includes first and second threshold voltage measuring units 210 and 220, and first and second selector units 230 and 240. And a connection part 250.

The operation of the Viterbi interface of the receiving end of the conventional wireless subscriber network having the structure as described above is as follows.

The first threshold voltage measuring unit 210 measures the threshold voltage of the I-channel signal transmitted from the signal combiner 150, and outputs the measured threshold voltage measurement value to the first selector 230. In this case, the threshold voltage measurement value output from the first threshold voltage measurement unit 210 is used as the selection signal of the first selection unit 230. In addition, the second threshold voltage measuring unit 220 measures the threshold voltage of the Q channel signal transmitted from the signal combiner 150 and outputs the measured threshold voltage measurement value to the second selector 240. In this case, the threshold voltage measurement value output from the second threshold voltage measurement unit 220 is used as the selection signal of the second selection unit 240.

The first selector 230 uses the threshold voltage measurement value output from the first threshold voltage measurement unit 210 as the selection signal, and the threshold voltage of the I channel signal equal to or greater than the reference threshold voltage and the I channel equal to or less than the reference threshold voltage. The threshold voltage of the signal is selectively delivered to the connection 250. In addition, the second selector 240 uses the threshold voltage measurement value output from the second threshold voltage measurement unit 220 as a selection signal, so that the threshold voltage of the Q channel signal equal to or greater than the reference threshold voltage and the Q channel equal to or less than the reference threshold voltage are determined. The threshold voltage of the signal is selectively delivered to the connection 250. In this way, the I-channel signal and the Q-channel signal, which are cut through the first and second selectors 230 and 240 to the threshold voltage higher than the reference threshold voltage and the threshold voltage lower than the reference threshold voltage and transmitted to the connection unit 250, are decoded. The interleaving unit 170 is connected.

3 shows the threshold voltage characteristics of the input signal cut by the Viterbi interface of FIG. 2, (a) shows a portion where the threshold voltage of the I-channel signal and the threshold voltage of the Q-channel signal are larger than the reference threshold voltage. (b) shows a portion where the threshold voltage of the I-channel signal and the threshold voltage of the Q-channel signal are smaller than the reference threshold voltage.

However, in the case of the conventional Viterbi interface described above, the symbol of the restored input signal has a wide dynamic range, but the Viterbi decoder at the receiving end inputs 3 to 4 bits of information to make a soft decision. Since it is lowered, the error increases according to the range of the input signal, and there is a problem in that the performance of the Viterbi decoder is degraded.

Accordingly, the present invention has been made to solve the above problems, and since the data received and demodulated from the transmitting end of the wireless subscriber network changes according to the situation and interference of the communication channel, the dynamic range according to the input signal input from the transmitting end. It is an object of the present invention to provide a Viterbi interface device of a receiving end that can increase decoding efficiency by quantizing an input signal while changing the.

1 is a block diagram of a receiving end of a typical wireless subscriber network.

2 is a block diagram of a Viterbi interface device at a receiving end of a conventional wireless subscriber network.

3 is a threshold voltage characteristic diagram of an input signal input to the Viterbi interface of FIG. 2.

Figure 4 is a block diagram of one embodiment of the Viterbi interface device of the receiving end of the wireless subscriber network according to the present invention.

FIG. 5 is an explanatory diagram showing a change in an input signal constellation and a change in a range of threshold voltages according to a power level of an input signal input to a receiver of a wireless subscriber network according to the present invention.

6 is an operation characteristic diagram of the nonlinear quantization unit of FIG. 4;

Explanation of symbols on the main parts of the drawings

410: threshold voltage adjusting unit 420: limiting unit

430: linear quantization unit 440: nonlinear quantization unit

In order to achieve the above object, a Viterbi interface device of a receiver of a wireless subscriber network according to the present invention adjusts a threshold voltage for adjusting threshold voltages of first and second channel signals transmitted from a transmitter, compared to a preset reference value. Way; Limiting means for receiving first and second channel signals from the threshold voltage adjusting means and limiting threshold voltages of the first and second channel signals outside the reference range; Linear quantization means for linearly decreasing the number of bits of the first and second channel signals output from said limiting means; And non-linear quantization means for non-linearly reducing the number of bits of the first and second channel signals output from the linear quantization means.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 4 to 6.

Figure 4 is a block diagram of an embodiment of the Viterbi interface device of the receiving end of the wireless subscriber network according to the present invention.

As shown in FIG. 4, in the Viterbi interface device of the receiving end of the wireless subscriber network of the present invention, the input terminal is connected to the threshold voltage adjusting unit 410 connected to the output of the signal combiner 150 of FIG. Limiting unit 420 connected to the output terminal of the adjusting unit 410, a linear quantizer 430 connected to the output terminal of the limiting unit 420, the input terminal is connected to the output terminal of the linear quantization unit 430 And an output terminal having a nonlinear quantization unit 440 connected to an input terminal of the deinterleaving unit 170 of FIG. 1.

The threshold voltage adjusting unit 410 includes a measuring unit 411 for measuring the energy of data of the I channel signal and the Q channel signal, and an energy measurement value of the data of the I channel signal transmitted from the measuring unit 411 and the Q channel. An average value calculator 412 for calculating an average value of the energy measured values of the data of the signal, a comparator 413 for comparing the magnitude of the average value output from the average value calculator 412 with a preset reference value, and a comparator A filtering unit 414 for filtering the comparison value transmitted from 413, a first variable gain 415 for adjusting the gain of the I-channel signal according to the output signal of the filtering unit 414, and a filtering unit In accordance with the output signal of 414, a second variable gain 416 is provided for adjusting the gain of the Q channel signal.

The operation of the threshold voltage adjusting unit having such a structure will be described in detail as follows.

When the measuring unit 411 measures the energy of the data of the I-channel signal and the Q-channel signal output from the signal combiner 150 of FIG. 1 and transmits the energy to the average value calculating unit 412, the average value calculating unit 412 is transferred. The average value of the energy measurement value of the data of the I-channel signal and the energy measurement value of the data of the Q-channel signal is calculated and output to the comparator 413. Subsequently, the comparison unit 413 compares the predetermined reference value with the magnitude of the energy average value of the data of the I-channel signal and the Q-channel signal transmitted from the average value calculation unit 412 and outputs it to the filtering unit 414. The filtering unit 414 filters the output signal of the comparator 413, and the filtered signal is used as the variable gain control signal of the first and second variable gains 415 and 416. Accordingly, the first variable gain 415 is controlled by the output signal of the filtering unit 414 to adjust the gain of the I-channel signal transmitted from the signal combiner 150, which is suitable for decoding by the Viterbi decoder 180. An I channel signal having a gain value is output to the limiting unit 420. In addition, the second variable gain 416 is controlled by the output signal of the filtering unit 414 to adjust the gain of the Q channel signal transmitted from the signal combiner 150, which is suitable for decoding by the Viterbi decoder 180. The Q channel signal having the gain value is output to the limiting unit 420.

The limiting unit 420 may include a first limiter 421 for limiting the threshold voltage of the I channel signal transmitted from the first variable gain 415, and a threshold voltage of the Q channel signal transmitted from the second variable gain 416. And a second limiter 422 for limiting.

The linear quantizer 430 may include a first linear quantizer 431 for linearly reducing the number of bits of the I-channel signal transmitted from the first limiter 421 and a Q channel transmitted from the second limiter 422. A second linear quantizer 432 is provided for linearly reducing the number of bits in the signal.

The nonlinear quantizer 440 includes a first nonlinear quantizer 441 and a Q transmitted from the second linear quantizer 432 for reducing the number of bits of the I-channel signal transmitted from the first linear quantizer 431. A second nonlinear quantizer 442 is provided for reducing the number of bits in the channel signal.

Referring to the operation of the Viterbi interface device of the receiving end of the wireless subscriber network of the present invention having the structure as described above in detail as follows.

When the I-channel signal and the Q-channel signal are transmitted from the threshold voltage adjusting unit 410 to the limiting unit 420, the first limiter 421 of the limiting unit 420 is transferred to the I-channel transmitted from the first variable gain 415. Soft limiting the dynamic range of the threshold voltage of the signal outputs an I-channel signal having a signal range suitable for decoding by the Viterbi decoder 180 to the first linear quantizer 431. In addition, the second limiter 422 of the limiting unit 420 softly limits the dynamic range of the threshold voltage of the Q-channel signal transmitted from the second variable gain 416, thereby allowing the Viterbi decoder 180 to perform a soft limit. A Q channel signal having a signal range suitable for decoding is output to the second linear quantizer 432.

Subsequently, the first linear quantizer 431 of the linear quantizer 430 linearly quantizes the M-bit I-channel signal transmitted from the first limiter 421 to convert the N-bit I-channel signal to the first nonlinear quantization. The N-bit I-channel signal is non-linearly quantized through the first nonlinear quantizer 441 and transmitted to the deinterleaving unit 170 of FIG. 1. In addition, the second linear quantizer 432 of the linear quantizer 430 linearly quantizes the M-bit Q channel signal transmitted from the second limiter 422 to convert the N-bit Q channel signal to the second nonlinear quantization. The N-bit Q channel signal is nonlinearly quantized through the second nonlinear quantizer 442 and transmitted to the deinterleaving unit 170 of FIG. 1. Here, the I channel signal and the Q channel signal transmitted from the first and second nonlinear quantizers 441 and 442 to the deinterleaving unit 170 are log values having P bits. And P is a natural number, where M> N> P.)

5 is an explanatory diagram showing a change in an input signal constellation and a change in a range of threshold voltages according to a power level of an input signal input to a receiving end of a wireless subscriber network according to the present invention.

Referring to FIG. 5, in order for the Viterbi decoder 180 of FIG. 1 to perform optimally, relative changes are more important than absolute values of symbols of the input signal. Since the Viterbi decoder 180 may not perform optimal performance when extracted, the present invention allows the Viterbi decoder 180 to perform optimally by varying the positions of bits for extraction.

FIG. 6 illustrates the operating characteristics of the nonlinear quantization unit of FIG. 4, wherein (a) is a maximum range for nonlinear quantization, and (b) is a range that is half of the maximum range of (a).

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the Viterbi interface device of the receiving end of the wireless subscriber network of the present invention does not extract fixed bits when forming a symbol of the input signal, and softly determines the dynamic range of the input signal to variably reduce the bits. In this case, the Viterbi decoder 180 can achieve the best performance, thereby reducing the loss of the signal received from the transmitting end to the receiving end.

Claims (5)

Threshold voltage adjusting means for adjusting threshold voltages of the first and second channel signals transmitted from the transmitting end in comparison with a preset reference value; Limiting means for receiving first and second channel signals from the threshold voltage adjusting means and limiting threshold voltages of the first and second channel signals outside the reference range; Linear quantization means for linearly decreasing the number of bits of the first and second channel signals output from said limiting means; And Non-linear quantization means for non-linearly reducing the number of bits of the first and second channel signals output from the linear quantization means Viterbi interface device of the receiving end of the wireless subscriber network comprising a. The method of claim 1, The threshold voltage adjusting means, Measuring means for measuring energy of data of said first and second channel signals; Average value calculating means for calculating an average value of an energy measurement value of the data of the first channel signal and an energy measurement value of the data of the second channel signal transmitted from the measuring means; Comparison means for comparing the magnitude of the reference value with the average value output from the average value calculation means; Filtering means for filtering the comparison value transferred from the comparison means; First gain adjusting means for adjusting a gain of the first channel signal according to the output signal of the filtering means; And Second gain adjusting means for adjusting the gain of the second channel signal according to the output signal of the filtering means; Viterbi interface device of the receiving end of the wireless subscriber network comprising a. The method according to claim 1 or 2, The limiting means, A first limiting unit for limiting a threshold voltage of the first channel signal transferred from the first gain adjusting means; And A second limiting unit for limiting a threshold voltage of the second channel signal transmitted from the second gain adjusting means; Viterbi interface device of the receiving end of the wireless subscriber network comprising a. The method of claim 3, wherein The linear quantization means, A first linear quantizer for linearly reducing the number of bits of the first channel signal transmitted from the first limiting unit; And A second linear quantizer for linearly decreasing the number of bits of the second channel signal transmitted from the second limiting unit Viterbi interface device of the receiving end of the wireless subscriber network comprising a. The method of claim 4, wherein The nonlinear quantization means, A first nonlinear quantizer for reducing the number of bits of the first channel signal transmitted from the first linear quantizer; And A second nonlinear quantizer for reducing the number of bits of the second channel signal transmitted from the second linear quantizer Viterbi interface device of the receiving end of the wireless subscriber network comprising a.