KR20010091140A - Apparatus for receiver of communication system and Method for demodulating signal using the same - Google Patents

Abstract

PURPOSE: A receiver for a communication system and a signal demodulating method using the same are provided to decrease the size of a system and increase a signal processing time by demodulating a signal transmitted from a plurality of mobile terminals using one channel demodulator through a time division and a two-stage high-speed Hadamard conversion. CONSTITUTION: A despreader(400) despreads a sample data stored in an input sample buffer using a time division method. The first portion high-speed Hadamard converter(401) correlates the despreaded sample data and outputs correlated values. A portion buffer(402) stores specific correlated values among the correlated values output from the first portion high-speed Hadamard converter(401). A register(403) stores the correlated values currently processed in the first portion high-speed Hadamard converter(401). A multiplexer(404) selects correlated values with reference to digital signals same to the specific correlated values among the specific correlated values stored in the portion buffer(402) and the correlated values stored in the register(403). The second portion high-speed Hadamard converter(450) outputs a last correlated value with reference to a set Walsh chip using each correlated value output from the multiplexer(404). A combiner(406) adds the last correlated values output from the second portion high-speed Hadamard converter(450) and obtains a combined gain. A duplex maximum metric generator(407) generates a soft decision metric for decoding using an energy output from the combiner(406).

Description

Receiver for communication system and method for demodulating signal {Apparatus for receiver of communication system and Method for demodulating signal using the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system, and more particularly, to a demodulator of a communication system and a signal demodulation method thereof, which are suitable for efficiently demodulating signals transmitted from a plurality of users in a mobile communication system using a code division multiple access scheme (CDMA). It is about.

Currently, TIA's IS-95 CDMA communication system using spread spectrum technology is used as a mobile communication system.

This IS-95 CDMA communication system is a direct sequence CDMA coherent forward link and noncoherent reverse link using a 1.2288 MHz PN chip. Is done.

Hereinafter, a signal transmission / reception process of the IS-95 communication system will be described in detail.

First, the reverse link through the transmitter of the mobile terminal is described. The signal output from the vocoder is channel coded through a convolutional encoder and a block interleaver, modulated in a 64 orthogonal modulator, and then modulated by 307.2K. Converted to a Walsh chip symbol.

This 307.2K Walsh chip symbol is spread and scrambled by a 1.2288Mhz masked long code, which is then divided into I and Q channels and spread in a short Pien sequence.

The signal spread in the short PN sequence is then filtered, multiplied with the carrier via an offset QPSK modulator, converted to a radio frequency (RF) signal and transmitted via the antenna.

On the other hand, the operation of the base station receiver is as follows.

FIG. 1 is a block diagram showing a part of a conventional base station receiver, and FIG. 2 is a detailed block diagram of a channel demodulator shown in FIG.

1 and 2, an analog receiver 100 for converting a plurality of radio frequency (RF) signals received through an antenna into digital signals, and a plurality of despreading and demodulating the converted digital signals, respectively. Channel demodulators 101a to 101n.

Here, each of the channel demodulators 101a to 101n includes a plurality of despreaders 200a to 200n for demodulating the digital signals output from the analog receiver 100 and signals output from the respective despreaders 200a to 200n. And a fast Hadamard transformer 202 for outputting 64 correlation values by 64-ary correlating signals stored in the buffer 201, and the high speed Hadamard converter 202. A combiner 203 that squares and adds the 64 correlations, and a dual maximum metric generator 204 that generates a metric for a soft decision on the energy value output from the combiner 203. It is composed.

A plurality of channel demodulators 101a to 101n are provided to process signals transmitted from each mobile terminal, and each channel demodulator 101a to 101n is assigned to each mobile terminal to demodulate signals transmitted from the corresponding mobile terminal. In charge.

The operation of the base station receiver configured as described above is as follows.

First, the analog receiver 100 removes a carrier frequency from a radio frequency (RF) signal received through an antenna and converts the carrier frequency into a baseband digital signal through an analog / digital converter (not shown) to convert the channel demodulators 101a to 101n. Send to either.

Then, each of the despreaders 200a to 200n of the channel demodulators 101a to 101n despreads the baseband received signal by multiplying the short PN code, and then multiplies the long PN code to perform despreading and descrambling. do. Each of these despreaders 200a-200n is referred to as a finger for processing reflected radio frequency (RF) signals received.

Thereafter, the signals output from each of the despreaders 200a to 200n are stored in the buffer 201, and the signals stored in the buffer 201 are processed through a 64-ary correlator (not shown). Fast Hadamard Transform (FHT) is used for this purpose.

Accordingly, the fast Hadamard transformer 202 outputs 64 correlation values, and the correlation values are combined to obtain a combined gain through a hard decision process that is squared and added through the combiner 203.

Thereafter, the dual maximum metric generator 204 generates a soft decision metric for deinterleaving and decoding of the next stage by using the energy value output from the combiner 203.

However, such a conventional base station receiver has a problem in that the load of the system is increased and the processing of the received signal is delayed by including a plurality of demodulation circuits that perform the same function to process signals received from a plurality of mobile terminals. .

Accordingly, an object of the present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to quickly process signals received from a plurality of mobile terminals and to reduce the system load, and a receiver of a communication system and signal demodulation using the same. It is to provide a method.

According to an aspect of the present invention for achieving the above object, a receiver of a communication system is an analog receiver for receiving a radio frequency signal transmitted from a plurality of mobile terminals and converts to a baseband digital signal, respectively, and the converted A buffer for storing the sample data corresponding to the PEN chip already set in each digital signal, and a channel demodulator for demodulating the sample data of each stored digital signal by time division.

Preferably, the buffer stores sample data corresponding to 128 Pien chips, and the channel demodulator despreads the sample data stored in the buffer by a time division method, and outputs the data by correlating the despread sample data. A first partial fast Hadamard transformer, a partial buffer storing specific correlation values among the correlation values output from the first partial fast Hadamard converter, and a correlation value output from the first partial fast Hadamard converter A mux for selecting and outputting a specific correlation value stored in the partial buffer and a specific correlation value stored in the partial buffer and the correlation values stored in the register for the same digital signal, and each correlation output from the mux A second partial fast madmad converter for outputting a correlation value for the Walsh chip set using the values; The group consists of a dual maximum metric generator 2 to the high speed is in addition of the correlation value output from the Hadamard converter using the energy output from the coupler with the coupler to obtain a combined gain generate soft decision metric for decoding.

According to another aspect of the present invention for achieving the other object as described above, the signal demodulation method of the communication system comprises the steps of receiving the radio frequency signals transmitted from a plurality of mobile terminals and converting them into baseband digital signals, respectively; Storing sample data corresponding to the PEN chip already set in each converted digital signal, despreading and correlating the stored sample data to generate first correlation values for the corresponding digital signal, and generating the first correlation value Storing the second correlation values by despreading and correlating the remaining sample data of the digital signal, storing the generated second correlation values, and receiving each of the stored correlation values in time division. Outputting final correlation values corresponding to a second correlating predetermined PEN chip; The ductile values are used to generate a soft crystal metric.

1 is a block diagram showing a part of a conventional base station receiver;

FIG. 2 is a detailed block diagram of the channel demodulator shown in FIG.

3 is a block diagram illustrating a receiver of a communication system according to the present invention.

4 is a detailed block diagram of the channel demodulator shown in FIG.

FIG. 5 is a detailed circuit diagram of the second partial high speed Hadamard converter shown in FIG.

6 illustrates an example of a processing slot of each apparatus in demodulating a signal of a receiver according to the present invention.

Explanation of symbols for the main parts of the drawings

400: despreader 401: first part high speed Hadamard converter

402: buffer 403: register

404: mux 405: second part high speed Hadamard converter

406: Combiner 407: Double Max Metric Generator

Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

The present invention proposes a signal demodulator of a communication system capable of demodulating signals received from a plurality of mobile terminals using one channel demodulator and a signal demodulating method using the same.

3 is a block diagram illustrating a receiver of the communication system according to the present invention, and FIG. 4 is a detailed block diagram of the channel demodulator shown in FIG.

3 to 4, a receiver of a communication system according to the present invention includes an analog receiver 300 for receiving radio frequency signals transmitted from a plurality of mobile terminals and converting them into baseband digital signals, respectively, An input sample buffer 301 for storing sample data corresponding to the PEN chip already set in each digital signal, and a channel demodulator 302 for demodulating the sample data of each stored digital signal by time division.

In this case, the channel demodulator 302 is a first partial fast that correlates and outputs the despreader 400 which despreads the sample data stored in the input sample buffer 301 by a time division method, and the despread sample data. In the partial converter 401, the partial buffer 402 for storing specific correlation values among the correlation values output from the first partial fast Hadamard converter 401, and in the first partial fast Hadamard converter 401 A register 403 for storing correlation values currently being processed, and a correlation value for a digital signal equal to the specific correlation value among the specific correlation values stored in the partial buffer 402 and the correlation values stored in the register 403. A second partial fast Hadamard converter 40 for outputting a mux 404 for selecting and outputting a respective one, and a final correlation value for Walsh chips set by using the correlation values output from the mux 404. 5) a combiner 406 that obtains a combined gain by adding the final correlation values output from the second partial fast Hadamard transformer 405 and a soft decision for decoding using the energy output from the combiner 406. It consists of a dual maximum metric generator 407 that generates a metric.

The operation of the receiver of the communication system configured as described above is as follows.

The analog receiver 300 removes a carrier frequency from a radio frequency (RF) signal received through an antenna and converts the carrier frequency into a baseband digital signal through an analog / digital converter (not shown).

Then, the input sample buffer 301 extracts and stores predetermined data from the digital signal output from the analog receiver 300 to process the signals received from the plurality of mobile terminals by time multiplexing.

In this case, in order to obtain a 64-ary correlation, 256 pien chips of data are generally required. When this 256 pien chip period is set as one processing slot, the processing slot is set to (number of users × fingers). Divide it to create that many secondary processing slots.

In general, a CDMA communication system supports a plurality of sectors. That is, radio frequency (RF) signals are received via multiple antennas, which are then stored in the input sample buffer 301 via different paths. Therefore, if there are 12 antennas, the size of the input sample buffer 301 should be 12 times the amount of data that can be processed in one auxiliary processing slot.

Therefore, in the present invention, the size of the processing slot is reduced to 128 pien chip period so that the sample data corresponding to 128 pien chips is stored in the input sample buffer 301.

The sample data stored in the input sample buffer 301 is input to the channel demodulator 302, and the channel demodulator 302 processes the sample data input from the input sample buffer 301 into time division and converts the sample data into the PEN code of each mobile terminal. Diffusion and accumulate 4 Pien chips to produce 64 Walsh chips.

In this case, since the PY chips that can be processed in one sub processing slot are 128 PY chips, one fast Hadamard converter cannot generate 64 correlation values in one sub processing slot.

Therefore, by dividing the fast Hadamard converter, the first Hadamard converter 401 combines the sum of the first 16 Walsh chips of the 32 Walsh chips (128 Phen chips / 4) and the next 16 Walsh chips processed in one auxiliary processing slot. Make a difference and store it in the buffer 402. This buffer 402 serves to store the result of the first partial fast Hadamard transform of all assigned slots. therefore. The size of this buffer 402 is (number of users x number of fingers x 32 x resolution).

In this case, the fast Hadamard transform is a Hadamard function. Therefore, the result of the partial Hadamard transform can be used next. Therefore, the result of the first partial fast Hadamard transform stored in the buffer 402 is the following 32 Walsh chip. It is then used together after the processing to perform a complete fast Hadamard transform.

On the other hand, the register 403 stores the result values of the part fast Hadamard transform currently being processed by the first part fast Hadamard converter 401, and the mux 404 is the part stored in the register 403 and the buffer 402. It outputs each of the fast Hadamard transform results.

The second partial fast Hadamard converter 405 then outputs a correlation of 64-ary using the output of the register 403 and buffer 402 output through the mux 404, and the combiner 406 The combined gain is obtained by adding the 64-ary correlation results of the various assigned fingers, and the double maximal metric generator 407 generates a soft decision metric for decoding.

Here, the detailed structure of the second partial high speed Hadamard converter is shown in FIG.

6 is a diagram illustrating an example of a processing slot of each device when demodulating a signal of a receiver according to the present invention.

Referring to Fig. 6, the processing slot has 128 pien chips as the period, and there are 128 auxiliary processing slots in the 128 pien chips period.

In this case, if a total of n fingers are allocated, it is denoted as U _n , m-1, m, and m + 1 are sequence numbers of 128 pien chip data, and 256 pien chip data is (m-2, m Assume that they have the order -1), (m, m + 1).

The despreader then despreads and accumulates 128 PEN chip data using the assigned slot, and the despread and accumulated data is sent to the first partial fast Hadamard converter for processing.

On the other hand, the time slot of the second partial high-speed Hadamard converter has a one-slot delay compared to the slot of the corresponding signal, and U _{1, m} is represented by IDLE. This is because in the case of U _{1, m} , since the first 128 pien chip data of 256 pien chip data is not necessary, the second partial fast Hadamard transformation is not necessary.

The U _{1, m} slot signal, which is the output of the first partial high-speed Hadamard converter, is stored in the buffer shown in FIG.

In the processing slot 1 shown in Fig. 6, a slot of U _{1 and m + 1} processes a signal of a finger, such as a finger assigned to a U _{1, m} slot, wherein the first partial high speed processed at U _{1, m + 1} is processed. The output of the Hadamard converter is stored in the register 403 shown in FIG.

Then, the second partial high-speed Hadamard converter first receives the signal stored in the buffer as input at U _{1, m} and U _{1, m + 1} slots, and then receives the signal stored in the register according to the muxing operation to perform a 64 Walsh chip. Produce the output of a fast Hadamard transform on.

The output of the fast Hadamard transform thus generated is processed by deinterleaving and decoding through a combiner and a double maximal metric generator.

As described above, according to the receiver of the communication system and the signal demodulation method using the same according to the present invention, signals transmitted from a plurality of mobile terminals are demodulated by time division and two-speed fast Hadamard transformation using one channel demodulator. This can reduce system size and increase signal processing time.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the examples, but should be defined by the claims.

Claims (4)

An analog receiver which receives radio frequency signals transmitted from a plurality of mobile terminals and converts them into baseband digital signals, respectively; A buffer for storing sample data corresponding to the PEN chip already set in each of the converted digital signals; And a channel demodulator configured to receive demodulated data of each digital signal and demodulate it by time division. The receiver of claim 1, wherein the buffer stores sample data corresponding to 128 Pen chips. The method of claim 1, wherein the channel demodulator, A despreader for despreading the sample data stored in the buffer by a time division method; A first partial fast Hadamard transformer for correlating and outputting the despread sample data; A partial buffer for storing certain correlation values among correlation values output from the first partial fast Hadamard converter; A register for storing correlation values output from the first partial fast Hadamard converter; A mux for selecting and outputting correlation values for a digital signal identical to the specific correlation value among the correlation values stored in the partial buffer and the correlation values stored in the register, respectively; A second partial fast Hadamard converter for outputting a final correlation value for the Walsh chip set by using the correlation values output from the mux; A combiner to obtain a combined gain by adding correlation values output from the second partial fast Hadamard converter; And a dual maximum metric generator for generating a soft decision metric for decoding using the energy output from the combiner. Receiving and converting radio frequency signals transmitted from a plurality of mobile terminals into baseband digital signals, respectively; Storing sample data corresponding to PN chips already set in each of the converted digital signals; Despreading and correlating the stored sample data to generate first correlation values for the corresponding digital signal, and storing the generated first correlation values; Despreading and correlating the remaining sample data of the digital signal to generate second correlation values, and storing the generated second correlation values; Receiving each of the stored correlation values by time division and performing second correlation, and outputting final correlation values corresponding to the predetermined predetermined PEN chip; And generating a soft decision metric using the outputted final correlation values.