KR100339343B1 - Communication System, Signalling Processing Method in the same - Google Patents

Abstract

More particularly, the present invention relates to a communication system for generating a pair of turbo coding having the same performance by changing the output order of a configuration coder in a turbo coding generator, and a signal processing method of the communication system The communication system according to the present invention generates two types of coded bit streams for the input bit stream and switches the generated two types of coded bit streams in response to the external switching control signal, And a reception apparatus for demodulating the two types of bit streams received from the transmission apparatus in accordance with the transmission apparatus, Can be easily and simply encoded with different codes of the different coding methods, Hayeoteumeuro the coding is effective for enhancing coding gain, as well as gain coupling.

Description

TECHNICAL FIELD [0001] The present invention relates to a communication system and a signal processing method of the system.

More particularly, the present invention relates to a communication system for generating a pair of turbo coding having the same performance by changing the output order of a configuration coder in a turbo coding generator, and a signal processing method of the communication system .

Generally, next generation mobile communication using code division multiple access (CDMA) method supports high speed data transmission up to millions of bits per second (Mbps), and this next generation high speed data communication is 10 ^-5 ~ 10 ^- Lt; RTI ID = 0.0 > ⁶ , < / RTI >

For this reason, there is a limitation in applying the convolutional coding technique, which is mainly used in existing communication systems, to the high-speed data communication.

Accordingly, a turbo coding technique capable of maintaining a low packet error probability even in a poor mobile communication environment is widely used, and the turbo coding technique has recently been widely adopted as a standard of a mobile communication system.

FIG. 1 is a block diagram illustrating an apparatus configuration for explaining a turbo coding generation procedure according to the related art. Referring to FIG.

Referring to FIG. 1, a parallel concatenated turbo encoder, which is a turbo code encoder, includes two constituent encoders 10 and 11 connected in parallel and a turbo interleaver interposed therebetween. (12).

The first constituent encoder 10 inserts the parity bits Y _0k and Y _1k for the information bits X _k and the second constituent encoder 11 compares the error bits X _k ' Detection bits Y _0k ', Y _1k ' are inserted.

The parallel coupled turbo encoder according to the related art outputs information bits and error detection bits in the order of X _k Y _0k Y _1k X _k 'Y _0k ' Y _1k '.

FIG. 2 is a block diagram illustrating an apparatus for generating a downlink transmission signal using a conventional turbo coder. Referring to FIG.

Referring to FIG. 2, a parallel turbo encoder of FIG. 1 is used as a basic turbo encoder 201 to generate an encoded stream, and then, through symbol puncturing 202 and rate matching 204, N to match.

Then, a transmission signal in the downlink is generated through the interleaving 205, the modulator and the spreader 206.

At this time, the bits output through the basic turbo encoder 201 generate a single-pattern output signal such as 'X _k Y _0k Y _1k X _k ' Y _0k 'Y _1k '.

The receiving end of the single-pattern output signal demodulates the signal according to the configuration shown in FIG.

3, the signals are recovered through the first and second demodulators and inverse transformers 301 and 302, and the signals output from the respective demodulators and despreaders 301 and 302 are soft-combined by the combiner 303 , Generates one bit stream having a small error rate, decodes it from the bit stream of the original length through the deinterleaving and rate matching 304 and the de-puncturing 305, and outputs the bit information input bit X _k .

However, in addition to a single signal using such a turbo coding scheme, some communication systems require a coding scheme requiring another encoded output sequence.

For example, there is a Hybrid Type Automatic Repeat Request (Hybrid Type III ARQ) scheme.

4 is a flowchart illustrating a procedure of a hybrid type ARQ scheme according to the related art.

Referring to FIG. 4, in the Hybrid Type ARQ scheme, when a transmitter adds information to a cyclic redundancy code, encodes the information, and transmits a signal, (S20), demodulates and decodes the signal, and determines whether the same signal is present in the buffer (S21).

If the same signal does not exist, it is immediately stored in the buffer (S22). If the same signal is present, it is combined with the signal of the buffer and stored in the buffer (S23)

If there is no abnormality in the cyclic redundancy code (CRC) by searching for the cyclic redundancy code (S24), the receiving end sends an acknowledgment (abbreviated as ACK) and empties the buffer (S26)

If there is an error in the cyclic redundancy code (CRC), the information signal having the error is stored in the retransmission buffer, and the receiving end sends a non-acquisition signal (NACK) (S25).

When the transmitting terminal receives the acquisition signal (ACK) from the receiving terminal, it transmits the next information, but when receiving the non-acquisition signal (NACK), it transmits the same signal again.

Therefore, the receiver receives the retransmitted signal, combines the received signal with the signal stored in the buffer, demodulates the information, and sends an acquisition signal (ACK) when there is no abnormality in the cyclic redundancy code (CRC) Sends an acquisition signal (NACK) to request another retransmission of the same information, and at the same time stores the signal coupled to the retransmission buffer.

In this case, when the information transmitted from the transmitting end to the receiving end is transmitted with the same code, the probability of occurrence of the error increases again. If the channel environment is similar to that of the transmitted information, the gain due to the combining can not be expected. It is necessary to encode the information in a bit pattern of a scheme and transmit the information.

In addition to the Hybrid Automatic Repeat Request (ARQ) scheme, a different encoded sequence is required in a transmission diversity scheme or a convolutional coding scheme.

In the convolutional coding scheme, different encoding polynomials are obtained while maintaining the same limited length of the encoder, thereby obtaining different encoding schemes of the same performance.

In addition, in the turbo coding method in which the range of application is widening recently, another encoding method can be obtained by changing the polynomial or changing the interleaver of the turbo encoder.

However, in order to apply other encoding codes in such a turbo coding scheme to an existing system, it is necessary to apply a puncturing pattern having the same performance, to memorize the patterns found by the symbol puncturing section, The puncturing stage is complicated to perform chirping.

In addition, since the limited length of the turbo coding scheme is low, the number of generated polynomials is not large, and thus, a method of changing polynomials is not suitable.

The method of changing the interleaver of the turbo encoder has a problem of increasing complexity at the receiving end.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a method and apparatus for generating a pair of turbo coding having the same performance without increasing a configuration complexity of a communication system, And to provide an apparatus therefor.

According to an aspect of the present invention, there is provided an apparatus for generating two types of coded bit streams for an input bit stream and generating two types of coded bits in response to an external switching control signal, A transmitting device for transmitting the modulated bit strings by switching the columns and a receiving device for switching and demodulating the two types of bit strings received from the transmitting device in accordance with the transmitting device.

Preferably, the transmission apparatus further comprises: a turbo encoder for performing coding with two types of bit streams for the input bit streams; and a switching unit for switching the bit streams of the two types of coded signals in response to the external switching control signal And a transmitter for modulating bit streams of different bit patterns output by the switch with a desired coding rate and transmitting the modulated bit streams to a receiver, wherein the receiver is configured to receive two types of bits And a decoder for decoding the bit streams output from the switch. The decoding apparatus of the present invention comprises: a demultiplexer for demultiplexing the demodulated bit streams;

According to another aspect of the present invention, there is provided a method of decoding a bitstream, comprising: a first transmission path unit for performing coding on an input bitstream to generate a first bitstream; And a second transmission path unit for generating a second bit string having a bit pattern different from that of the first bit string; a first reception unit for demodulating the first bit string received from the first transmission path unit; A second receiving path unit for demodulating the second bit stream received from the second transmission path and switching the received bit stream in accordance with the transmission order, And a receiver for decoding the bit streams output from the combiner.

According to an aspect of the present invention, there is provided a method comprising: coding input bitstreams with two types of bitstreams; switching between the two types of coded bitstreams; , Modulating the switched bit streams with a desired coding rate, and transmitting the modulated bit streams; demodulating the transmitted bit streams to convert them into original bit sequences; Correcting and combining the bitstreams, and decoding the combined bitstreams.

1 is a block diagram illustrating an apparatus configuration for explaining a turbo coding generation procedure according to the related art;

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a turbo encoder, and more particularly,

3 is a flowchart illustrating a procedure of a general hybrid type ARQ scheme.

4 is a block diagram illustrating an apparatus configuration for explaining a turbo decoding generation procedure according to the related art;

FIG. 5 is a block diagram illustrating an apparatus for generating a transmission signal in a downlink using a turbo encoder according to the present invention. Referring to FIG.

6 is a block diagram showing an example of using a turbo coding device according to the present invention.

7 is a block diagram showing another example using the turbo coding generator according to the present invention.

Description of the Related Art [0002]

401: basic turbo encoder

402: Switch

403: Symbol Puncturing

404: Turbo encoder

405: Rate matching

406: Interleaving

407: Modulator and diffuser

408:

In the present invention, the output from a conventional turbo encoder is _{X k Y 0k Y 1k X k} 'Y 0k'' to the same _{as, X k Y 0k Y 1k X} k' Y 1k Y 0k 'Y 1k' bit in addition to X _k 'Y _0k ' Y _1k 'X _k Y _0k Y _1k We can also output a coded stream with the same bit pattern as Y _1k and decode it, and propose a signal processing method of this system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

Referring to FIG. 1, the structure of a turbo encoder of a turbo code is basically composed of two constituent encoders connected to each other and an interleaver interposed therebetween.

The constituent encoder is an error for the same said first constituent coder information bits in and the parity bit (Y _0k, Y _1k) inserted on the (X _k), the second configuration encoder interleaved information bits (X _k ') Detection bits Y _0k ', Y _1k ' are inserted.

Each of the constituent encoders is a same Recursive Systematic Convolutional encoder, and its output outputs the input X _k as it is and at least one parity bit Y _k of at least one bit.

That is, it has two or more bits of output for one bit input. Therefore, the ratio of the input to the output indicating the coding rate may be 1/2, 1/3 or 1/4.

In FIG. 1, since the constituent encoder for outputting the bit pattern as described above has at least one bit, when two bits of parity are added, bits having a coding rate of 1/6 are output.

In order to obtain the coding sequence of the desired coding rate from the output bits of the 1/6 coding rate, the required coding rate (1/2, 1/3, 1/4) is satisfied by puncturing the output 6 bits as necessary .

In this case, when it is necessary to transmit information coded in different schemes to one information, the bit streams output from the respective constituent encoders of the basic turbo encoder 401 are different from each other A switch capable of performing mutual output conversion from a serial pattern to a parallel pattern or from a parallel pattern to a serial pattern so as to be a bit string having a bit pattern is output to output a desired encoding sequence.

FIG. 5 is a block diagram illustrating an apparatus for generating a transmission signal in a downlink using a turbo encoder according to the present invention. Referring to FIG.

Referring to FIG. 5, the transmission signal generation using the turbo encoder according to the present invention can be roughly divided into a basic turbo encoder 401 and a basic turbo encoder 401 using a serial pattern or a parallel pattern A switch 402 for selectively outputting an encoded stream having a desired bit pattern and a transmitter 408 for modulating the signal output from the switch 402 at a desired coding rate and transmitting the modulated signal to a receiver.

The transmitting unit 408 includes a symbol puncturing unit 403 for modulating a signal at a desired coding rate, a rate matching unit 405, an interleaving unit 406, and a modulator and a spreader unit 407.

With this configuration, assuming that the bit pattern output from the basic turbo encoder 401 is output in the same bit pattern as X _k Y _0k Y _1k X _k 'Y _0k ' Y _1k 'as in the prior art, ), A bit pattern such as X _k 'Y _0k ' Y _1k 'X _k Y _0k Y _1k is output in addition to the bit pattern.

The two types of bit strings having different bit patterns are performed by switching the switch 402 to output the output bit strings having a desired bit pattern in response to an external control signal.

That is, when the input bit X _k enters the input of the basic turbo encoder 401, the first constituent encoder outputs the encoding sequence in the same bit pattern as X _k Y _0k Y _{1k based} on FIG.

If the input bit X _k is interleaved by the turbo inverters and is input to the second constituent encoder, the second constituent encoder outputs the encoded string in the same bit pattern as X _k 'Y _0k ' Y _1k ' Output.

That is, when the bit pattern such as X _k Y _0k Y _1k X _k 'Y _0k ' Y _1k 'is changed in the order of output by the switch responding to the external control signal, X _k ' Y _0k 'Y _1k ' X _k Y _0k Y _It is also output in the same bit pattern as _1k .

The code string thus output is code-generated at a desired coding rate by symbol puncturing 403 and rate matching 405 as in the conventional art. Thereafter, interleaving 406, modulator and spreader 407, A desired transmission signal in the downlink is generated.

At this time, the symbol puncturing stage stores and applies only one optimal puncturing pattern. Then, by changing only the order of X _k Y _0k Y _1k and X _k 'Y _0k ' Y _1k ', the two coding schemes have completely the same performance due to the double-sidedness of the constituent encoder of the parallel concatenated turbo code.

One of the embodiments of the coding scheme proposed in the present invention is a transmission antenna diversity system for transmitting the same information using two antennas in a transmitter or a soft handover mode for entering the same information from two base stations For example.

6 is a block diagram showing an example of using a turbo-coding generator according to the present invention.

That is, in the existing principle, the same signal is transmitted from two antennas or two base stations. That is, only the encoding method to output in the order of _{X k Y 0k Y 1k X k} 'Y 0k' Y 1k ' is used in the two base stations.

However, as shown in FIG. 6, in the transmission diversity or the handover between two base stations using the principle of the present invention, one antenna (or first base station) uses X _k Y _0k Y _1k X _k 'Y _0k ' Y _k ', and Y _k ' are output to the other antenna (or the second base station) in the order of X _k 'Y _0k ' Y _1k 'X _k Y _0k Y _1k ' A signal generated by a method of encoding is sent.

Therefore, each transmission path unit simply obtains another encoding sequence using the turbo code encoding scheme according to the present invention, and transmits the different encoding sequences.

6, each transmitting apparatus of a communication system for performing transmission diversity or inter-base station handover using a turbo coding generator according to the present invention includes first transmission path units 504 and 508 And second transmission path sections 512 and 516 shown at the lower end.

The first transmission path units 504 and 508 and the second transmission path units 512 and 516 are mainly composed of turbo coder 504 and 512 and transmission units 508 and 516.

Each of the turbo encoders 504 and 512 includes respective basic turbo encoders 501 and 509 and switches 502 and 510.

Each of the transmission units 508 and 516 includes respective symbol puncturing units 503 and 511, rate matching units 505 and 513, interleaving units 506 and 514, and a modulator and spreaders 507 and 515.

With this configuration, the bit pattern output from the first basic turbo encoder 501 in the first transmission path unit 504 and 508 is expressed by X _k Y _0k Y _1k X _k 'Y _0k ' Y _1k ' The bit pattern output through the first switch 502 outputs a bit pattern similar to X _k 'Y _0k ' Y _1k 'X _k Y _0k Y _1k in addition to the bit pattern.

The two types of bit strings having different bit patterns are performed by switching the first switch 502 to output the output bit strings having a desired bit pattern in response to an external control signal.

That is, when the input bit X _k enters the input of the first basic turbo coder 501, the first constituent encoder outputs the coded stream in the same bit pattern as X _k Y _0k Y _{1k based} on Fig.

If the input bit X _k is interleaved by the turbo inverters and is input to the second constituent encoder, the second constituent encoder outputs the encoded string in the same bit pattern as X _k 'Y _0k ' Y _1k ' Output.

That is, when the bit pattern such as X _k Y _0k Y _1k X _k 'Y _0k ' Y _1k 'is changed in the order of output by the switch responding to the external control signal, X _k ' Y _0k 'Y _1k ' X _k Y _0k Y _It is also output in the same bit pattern as _1k .

The code string thus output is code-generated at a desired coding rate by the first symbol puncturing 503 and the first rate matching 505 as in the conventional art. After this, the first interleaving 506 and A first modulator and a spreader 507 generate a desired first transmission signal bit stream in the downlink.

This process is also repeated in the second transmission path units 512 and 516 to generate a second bit string having a different bit pattern from the first bit string.

That is, when it is _assumed that the first bit string has the same bit pattern as X _k Y _0k Y _1k X _k 'Y _0k ' Y _1k ', the second bit string is X _k ' Y _0k 'Y _1k ' X _k Y _0k Y _1k . Similarly, when the first bit string has the same bit pattern as X _k 'Y _0k ' Y _1k 'X _k Y _0k Y _1k , the second bit string is X _k Y _0k Y _1k X _k ' Y _0k 'Y _1k '.

The first bit string and the second bit string are transmitted to the receiving end through the different transmission path units, thereby being used as a transmission signal for performing transmission diversity or inter-base station handover.

In this case, encoded for output in the order of _{X k Y 0k Y 1k X k} 'Y 0k' Y 1k ' created by the encoding method and outputting a sequence of signals or _{X k' Y 0k 'Y 1k} ' X k Y 0k Y 1k Only two of the signals generated by the method are transmitted. According to the method proposed by the present invention, since two transmission signals have the same performance, it is advantageous to easily operate the system regardless of the performance regardless of the performance .

In case of soft handover between the base stations, only one of the two transmission terminals may be used. That is, when the mobile station is applied to the soft handover mode, only one transmission end is used when the mobile station moves out of the handover region.

On the other hand, the receiving end, which receives the transmission signals according to different encoding schemes as described above through different paths, decodes the transmission signals in a different configuration as shown in FIG.

In other words, in the prior art based on FIG. 4, since the two reception signals are signals encoded in the same manner, they are demodulated and combined at the receiving end and then decoded through deinterleaving, rate matching and defuncturing, Since the signal is transmitted to the receiving end through two paths or two different antennas according to the different encoding schemes according to the present invention, the receiving end of FIG. 7 decodes the signals received through the different paths by the following configuration .

Referring to FIG. 7, a receiving apparatus according to the present invention includes a first receiving path unit 610 for demodulating a first bit string received from a first transmission path unit in FIG. 6, And a second reception path unit 611 for demodulating the second bit stream.

The first receiving path unit 610 further includes a first demodulator and an inverse transformer 601, a first interleaving and rate matching 602 and a first de-puncturing 603, The length of the input bit string is demodulated.

The second receiving path unit 611 includes a second demodulator and an inverse transformer 606, a second interleaving and rate matching unit 607 and a second decoding unit 608, And demodulates it into the length of the input bit string.

The input bit stream of the original length demodulated from the first and second receiving path units 610 and 611 is generated as one information bit stream by the combiner 604. At this time, The bit strings output from the second reception path units 610 and 611 are input to and coupled to the combiner 604 according to the order transmitted from the transmission apparatuses in FIG.

At this time, the output bit streams of the second receiving path unit 611 are switched by the switch 609 responding to the external control signal so that the order of the output bit streams of the first receiving path unit 610 is the same, do.

The first and second bit streams received by the combiner 604 are generated as one information bit stream having a minimum error rate, which is decoded by the decoder 605.

As another application example of the present invention, considering a Hybrid ARQ scheme, a transmitter generates a sequence in the order of X _k Y _0k Y _1k X _k 'Y _0k ' Y _1k ' When a retransmission request is received from the receiving end, the signal to be retransmitted is transmitted in the order of X _k 'Y _0k ' Y _1k 'X _k Y _0k Y _1k ' .

As described above, according to the present invention, one information can be easily and simply encoded into two different codes having the same performance.

Therefore, when transmitting a signal to only one transmission path, the same performance is shown in comparison with the existing principle. However, when signals are transmitted to two transmission path sections, in addition to the diversity effect of the existing principle, There is an improvement in the performance obtained by sending codes encoded in different orders.

In other words, considering a case where the CRC of a retransmitted signal in an automatic repeat request (ARQ) scheme of a hybrid type is abnormal and a signal stored in a receiver buffer is combined with a retransmitted signal, The coding gain can be enhanced as well as the combining gain.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention.

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

Claims (5)

A transmitter for generating two types of coded bit streams for the input bit stream and switching the generated two types of coded bit streams in response to an external switching control signal to transmit the modulated bit streams; And a reception apparatus for demodulating two types of bit streams received from the transmission apparatus in accordance with the transmission apparatus. 2. The apparatus of claim 1, wherein the transmitter comprises: a turbo encoder for performing coding with two types of bit streams for the input bit streams; A switch for switching the coded two types of bit streams in response to the external switching control signal; And a transmitter for modulating bit streams of different bit patterns output by the switch with a desired coding rate and transmitting the modulated bit streams to a receiver. The apparatus of claim 1, wherein the receiver comprises: a demodulator for demodulating two types of bit streams received from the transmitter; A switch for switching the demodulated bit streams according to the transmission apparatus; And a decoder for decoding the bit strings output from the switch. A first transmission path unit for coding the input bit stream to generate a first bit stream; And a second transmission path unit configured to perform coding and switching on the input bit stream to generate a second bit stream having a bit pattern different from the first bit stream; A first reception path unit for demodulating the first bit stream received from the first transmission path unit, A second reception path unit for demodulating a second bit sequence received from the second transmission path and switching the transmission sequence according to the transmission sequence, A combiner for combining the bit strings output from the respective reception path units, And a decoder for decoding the bit streams output from the combiner. Coding the input information bit stream with two types of bit streams; Switching the two types of coded bit streams; Modulating the switched bit streams with a desired coding rate and transmitting the modulated bit streams; Demodulating each of the transmitted bit strings to convert them into bit strings of original length; Transforming the transformed bitstreams according to an original transmission order and combining the transformed bitstreams; And decoding the combined bit streams.