KR200315503Y1 - CDMA signal receiver - Google Patents

Abstract

SUMMARY OF THE INVENTION The present invention provides a signal receiver suitable for efficiently removing unwanted noise and improving a call quality. The present invention provides a quadrature detector that receives a signal from a user and converts the signal into an I signal and a Q signal. The first and second receiving filters restricting the bands of the output I and Q signals, respectively, and the I and Q signals output from the first and second receiving filters by the orthogonal coefficients are inputted at the transmitting side. An orthogonal filter for despreading and despreading by the used spreading code, a BPSK demodulation unit for compensating for the phase shift of the I-carrier and the Q-signal carrier to the Q-signal output from the orthogonal filter, and the output of the BPSK demodulation unit Determination circuit unit for detecting a signal and outputting the corresponding binary digital signal, I signal and Q signal output from the BPSK demodulation unit and the determination circuit A tap coefficient for calculating a quadrature coefficient of the quadrature filter according to the output signals of the first and second determination error extraction units and extracting the determination error from the output signal And a control unit and first and second switching units for selecting whether to output an output signal of the decision circuit unit to the first and second decision error extraction units or to output a training signal.

Description

Signal receiver

The present invention relates to a code division multiple access (CDMA) method, and to a signal receiving apparatus suitable for effectively removing unwanted noise and improving call quality.

Hereinafter, a signal receiver according to the prior art will be described with reference to the accompanying drawings.

1 is a block diagram illustrating a signal receiving apparatus according to the prior art.

As shown in FIG. 1, a quadrature detector 11 receiving a signal from users and converting the signal into quadrature signals of I and Q sequences, and an I signal and Q output from the quadrature detector 11 The first receiving filter 12 and the second receiving filter 13 which limits the band of the signal, and the I and Q bands output from the first receiving filter 12 and the second receiving filter 13 receive a transmitter ( Carrier phase for the signals output from the first and second multipliers 14 and 15, and the signals output from the first and second multipliers 14 and 15. And a decision circuit section 17 for detecting an output signal of the BPSK demodulator 16 and outputting a binary digital signal corresponding thereto. do.

The operation of the conventional signal receiver configured as described above is as follows.

As shown in FIG. 1, the signal received through the antenna has a phase difference of 90 ° with respect to the received signal using the original received signal (I signal) and the phase shifter 11a in the quadrature detector 11. Convert to a signal (Q signal).

Thereafter, the bandwidth of the I signal is limited by the first reception filter 12 and the bandwidth of the Q signal is limited by the second reception filter 13.

The I signal passing through the first reception filter 12 is multiplexed with the spreading code by the first multiplier 14, and the Q signal passing through the second reception filter 13 is the second multiplier 15. Is multiplexed with the spreading code.

The spreading code and the multiplexed I and Q signals are input to the BPSK demodulator 16. The BPSK demodulator 16 synchronizes the carrier phase with respect to the input I and Q signals.

Thereafter, the I signal and the Q signal output from the BPSK demodulator 16 are output by making a binary digital signal corresponding thereto in the decision circuit unit 17.

However, the conventional signal receiver as described above has the following problems.

In general, in a mobile communication system, a transmission signal power of a mobile station is limited to a small size, and a callable area is also limited in units of cells.

Thus, to accommodate a wider coverage area, many cells are placed, which are located at the center of each base station.

As such, an unwanted interference signal (noise) is received between subscribers in many cells, which interferes with the quality of the call.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a signal receiving apparatus suitable for efficiently removing unwanted noise and improving a call quality.

1 is a block diagram of a signal receiving apparatus according to the prior art

2 is a block diagram of a signal receiving apparatus of the present invention

Explanation of symbols for main parts of the drawings

21: Quadrature Detector 21a: Phase Shifter

22,23: First and second receiving filter 24: Orthogonal filter

25 BPSK demodulator 26 Decision circuit part

27,28: first and second determination error extraction unit 29: tap coefficient control unit

30,31: 1st, 2nd switching part

The signal receiver of the present invention for achieving the above object is a quadrature detector for receiving a signal from a user and converts the signal into an I signal and a Q signal, and limits the band of the I signal and the Q signal output from the quadrature detector, respectively. The first and second reception filters and the input orthogonal coefficients despread the I and Q signals output from the first and second reception filters by a spreading code used on the transmitting side to despread ( a despread orthogonal filter, a BPSK demodulator for compensating carrier phase shifts from the I and Q signals output from the orthogonal filter, and an output signal of the BPSK demodulator to detect and output a binary digital signal A circuit part, first and second decision error extracting parts for extracting a decision error from an I signal and a Q signal output from the BPSK demodulation part and an output signal of the decision circuit part; A tap coefficient controller configured to calculate an orthogonal coefficient of the orthogonal filter and output the orthogonal coefficient to the orthogonal filter according to the output signal of the first and second determination error extraction units, and output the output signal of the determination circuit unit to the first and second determination error extraction units. It comprises a first and second switching unit for selecting whether to apply or output as a training signal (Training).

First, when the interference signal can be removed by using a spreading code, it is good to make the spreading code as long as possible.

Since the removal of the interference signal is limited by the orthogonal characteristics, the removal of the interference signal by the orthogonal filter should spread the M-ary modulation signal to improve the coping function for fading in the transmission channel.

Hereinafter, a signal receiving device of the present invention will be described with reference to the accompanying drawings.

2 is a block diagram illustrating a signal receiving apparatus of the present invention.

As shown in FIG. 2, the signal receiving apparatus of the present invention receives a signal from a user, converts the signal into an I signal and a Q signal, and outputs the quadrature detector 21 and the I signal output from the quadrature detector 21. And I and Q signals output from the first and second reception filters 22 and 23 and the first and second reception filters 22 and 23 respectively limiting the bands of the and Q signals. An orthogonal filter 24 despread by the orthogonal coefficients, a BPSK demodulator 25 for compensating carrier phase shifts from the I and Q signals output from the orthogonal filter 24, and the BPSK demodulator Decision circuit section 26 for detecting the output signal of (25) and outputting it as a binary digital signal corresponding thereto, I signal and Q signal from the BPSK demodulation section 25, and the output signal of the decision circuit section 26. First and second decision error extractors 27 and 28 for extracting a decision error from the first and second decision errors; A tap coefficient controller 29 which calculates an orthogonal coefficient of the orthogonal filter and outputs the orthogonal coefficient to the orthogonal filter 24 according to the output signals of the first and second determination error extraction units 27 and 28, and the decision circuit unit First and second switching units 30 and 31 for selecting whether to output the output signal of the first and second determination error extraction units 27 and 28 or as a training signal. It is configured by.

Here, since the output signal of the decision circuit section 26 is a binary digital signal, the quadrature filter 24 despreads using the spreading code used at the transmitting side.

Referring to the operation of the signal receiver of the present invention configured as described above are as follows.

As shown in FIG. 2, the signal received through the antenna has a phase difference of 90 ° with respect to the received signal using the original received signal (I signal) and the phase shifter 21a in the quadrature detector 21. Convert to a signal (Q signal).

Thereafter, the bandwidth of the I signal is limited by the first reception filter 22 and the bandwidth of the Q signal is limited by the second reception filter 23.

The outputs of the first and second reception filters 22 and 23 are despread by the orthogonal coefficients output from the tap coefficient controller 29 in the orthogonal filter 24, and the BPSK demodulator 25 is Compensation for the carrier phase shift from the output of the quadrature filter 24.

The decision circuit section 26 determines whether the output of the BPSG demodulator 25 is high or not. The first and second switching units 30 and 31 output the output of the decision circuit unit 26 as an output or output of a training signal.

Convergence using the training signal is used as a decision signal for the initial stage of reception. Thus, after convergence, decision errors are extracted from the outputs of the decision circuit unit 26 and the BPSK demodulator 25.

The tap coefficient control unit 29 calculates an orthogonal coefficient from the outputs of the first and second decision error extraction units 27 and 28 and outputs the orthogonal filter 24 to the orthogonal filter 24.

One of the outputs of the decision circuit section 26 is a binary digital signal transmitted from the transmitter.

Therefore, the orthogonal filter 24 despreads using the spreading code used at the transmitting side.

On the other hand, in CDMA communication, there is a limit to reducing the interference signal, especially in the mobile communication system it is difficult to remove all the interference signal.

This is because there is interference between cells as well as interference between internal cells. Therefore, the number of removable interference signals can be determined by the length of the spreading code.

In a CDMA communication system, a binary digital signal is first spread and then scrambled with different I and Q codes.

That is, the signal is QPSK demodulated on a chip basis so that the transmission signal can be randomized.

Since the signal from the same cell shape and multiple cell regions are multiplexed with the original signal, the transmission channel is regarded as noise, so the optimal reception performance can be restored by an appropriate error correction method in the receiver.

As a result, it is possible to increase the number of subscribers that can transmit signals at any given moment.

Therefore, in the present invention, the transmission signal can be regarded as a QPSK signal, but it can be regarded as a BPSK signal from the viewpoint of information bit transmission. The reason is that QPSK modulation does not work directly in bits.

As described above, the signal receiving apparatus of the present invention has the following effects.

In the present invention, since the orthogonal coefficient is calculated using the spreading code used at the transmitting side in the tap coefficient controller and outputted to the orthogonal filter, the magnitude of the interference signal can be controlled by controlling the degree of spreading of the I and Q signals.

This can improve the quality of a call by efficiently removing unwanted noise by removing interference signals between cells.

Claims (1)

A quadrature detector which receives a signal from a user and converts the signal into an I signal and a Q signal, First and second reception filters respectively limiting bands of the I signal and the Q signal output from the quadrature detector; An orthogonal filter which despreads and spreads the I and Q signals output from the first and second receiving filters by the spreading codes used at the transmitting side by the input orthogonal coefficients; A BPSK demodulator for compensating for the carrier phase shift from the I and Q signals output from the quadrature filter; A determination circuit unit which detects an output signal of the BPSK demodulator and outputs a binary digital signal corresponding thereto; First and second decision error extracting units for extracting a decision error from an I signal and a Q signal output from the BPSK demodulator and an output signal of the decision circuit unit; A tap coefficient controller configured to calculate an orthogonal coefficient of the orthogonal filter based on an output signal and a diffusion code of the first and second decision error extraction units, and output the orthogonal filter to an orthogonal filter; And a first and second switching unit for selecting whether to output the decision signal of the decision circuit unit to the first and second decision error extraction units or to output the training signal as a training signal. Device.