KR20020087850A - Turbo encoder/decoder and method thereof - Google Patents

Abstract

PURPOSE: A turbo encoder/decoder and a method thereof are provided, which can achieve a long delay component improvement, a reduction of an iterative decoding number, a system performance improvement and a system operation efficiency. CONSTITUTION: According to a turbo encoding method used in a channel encoding of a wireless communication system, an input information bit stream Dk is interleaved with the first interleaver(202) when k is a positive integer. Then, the first parity bit stream y1k is obtained by encoding the bit stream interleaved in the previous step. The interleaved bit stream is interleaved with the second interleaver(206), and then, the second parity bit stream y2k is obtained by encoding the bit stream interleaved in the previous step.

Description

Turbo encoder / decoder and method thereof

The present invention relates to a turbo encoder / decoder and a method thereof, and more particularly, a turbo encoder / decoder for improving system performance and system operation efficiency by modifying a turbo code used for channel encoding / decoding of a wireless communication. It is about a method.

Next-generation mobile communication systems require reliable transmission of high-speed multimedia data, and strong channel coding and efficient modulation schemes are required to increase reliability of high-speed data. International Mobile Telecommunications-2000 (IMT-2000), which is the definitive edition of mobile telecommunications, unifies the specifications of various mobile phone systems currently operated by each country so that the same terminal can be used anywhere in the world. As the next generation mobile communication system, it is proposed to have specifications such as 2Mbps high-speed data communication centered on ITU and introduced in each country according to the standard.

"Optimal decoding of linear codes for minimizing symbol error rate (IEEE Trans. Inform. Theory, vol. IT-20, pp. Published in March 1974) by LR Bahl, J. Cocke, F. Jelinek, and J. Raviv. 248-287, March 1974) describes the BCJR algorithm. Also, in 1993, C. Berrou, A. Glavieux, and P. Thimajshima improved the BCJR algorithm by decoding convolutional coding and applied the 'turbo code' to a special type of concatenated code via an interleaver. 'Was designed.

Turbo code has recently been adopted as a standard for channel code for high-speed data transmission in next-generation mobile communication such as IMT-2000 by the International Telecommunication Union (ITU). The turbo code presented by Berrou et al. Has a lot of interest because of its relatively simple decoding algorithm in Additive White Gaussian Noise (AWGN) environment and its breakthrough performance at a low signal-to-noise ratio of 0.7 dB at 18 iterations. It is also known as a robust coding scheme that is reliable on fading channels. Turbo code performs better depending on the number of iterations and the size of the interleaver, and for interleavers that significantly affect the performance of turbo code in CDMA-2000 (Code Division Multiple Access-2000) and Association of Radio Industries and Business (ARIB). Research is actively underway.

Since the excellent performance of the turbo code was first introduced, research has been actively conducted around the world. The performance of the turbo code is due to the repetitive decoding performed in the interleaver and the decoder inherent in the encoder, and thus, a huge delay time is required to obtain such performance. Therefore, when the turbo code was first introduced, it was known that the encoding method using the turbo code could be applied only to a field where real time processing was not required such as space communication.

However, as much research has been conducted recently, research results on the relationship between the distance characteristics and the performance of turbo codes, or the efficient interleaver design accordingly, have been produced. Much effort has been invested in the development of the turbo code encoding method for real-time communication services in mobile communication systems, centered on the University of Kaiserslautern, Germany. In Korea, this research is being conducted by several research institutes and universities, and has been proposed as a transmission standard for the International Mobile Telecommunication (IMT) -2000 system.

1 shows a block diagram of a conventional turbo system. The turbo system s. L. "Turbo-Codes and high spectral efficiency modulation (Communications, 1994. ICC'94, IEEE International Conference on, pp. 645-649 Vol. 2, 1994.), SL Goff, A. Glavieux, published in 1994 by Goff et al. C. Berrou). The structure of the general turbo encoder 10 is connected to the configuration coders 102, 104 based on two Recursive Systematic Convolutional Code (RSCC) in parallel as shown in Figure 1 and between the two configuration coders (102, 104) The turbo interleaver 106 is inserted.

The input information bits of this turbo code are input to the first constituent encoder 102, and the order is intermixed by the interleaver 106, and then to the second constituent encoder 106 again. This allows the codeword of the parallel concatenated code to contain this information bit ( Parity check bits generated by the encoder 102 and 104, respectively. , It is composed of

The decoder 12 of the turbo code basically consists of a combination of a maximum a posteriori (MAP) decoder 120, 124, an interleaver 122, a deinterleaver 126, 128, and a soft limiter 130. The recursive structure can be calculated using the MAP decoding algorithm, and the BER (Bit Error Rate) performance is improved as the number of iterative decoding increases, showing the closest performance to the Shannon limit in terms of BER. Each of the MAP decoders 120 and 124 receives an information bit, a parity bit, and an extra bit as an input to generate a log likelihood ratio (LLR) for each bit. The additional information constituting this LLR becomes the prior information of the next decoder stage to increase the reliability of the decoding. In Fig. 1, the decoder located at the front and the rear end is composed of a soft-input / soft-output decoder, and the output value is used for iterative decoding. The first decoder 120 generates soft-decision information by using the received information bits and the parity bits, and the values are rearranged through the interleaver 122 and then the second decoder 124 of the second decoder 124. Used for secondary decoding. The second decoder 124 also generates soft-decision information using the received information bits and parity bits rearranged by the interleaver, and the value generated by the first decoder 120, which value is In the iterative decoding, the feedback is fed back to the input value of the first decoder 120.

The decoding of the turbo code is performed by repeatedly applying a symbol unit decoding using a MAP (maximum a posteriori) algorithm. The encoder may use, for example, two RSC constituent encoders, whereby the decoder of the turbo code consists of two MAP decoders 120 and 124 concatenated by the interleaver 122. The extra information generated by the first decoder 120 should be used by the second decoder 124. For this purpose, the algorithm of each decoder uses soft-in / soft-out decoding. It must be an algorithm. In addition, the soft output generated by the second decoder 124 is recursively input to the first decoder 120 again, and by repeating this process, the entire decoding process is iterative decoding. In this way, iterative decoding is performed to improve BER.

This will be described in more detail with reference to FIG. 1. In Figure 1, Is the input information bit string, Input information is interleaver The bit string after passing. Information bits of turbo encoder And parity bits Is output in the same order as [1 2 3 4 5 6 7 8 9], which is the order of input strings, and is input to the first decoder 120 of the decoder 12 through the channel. The second parity bit, Is the interleaver pattern = [~ 5 ~ 6 ~ 9 ~ 1 ~ 4 ~ 2 ~ 8 ~ 3 ~ 7 ~] , It is input to the second decoder 124 through the channel in a different order than. The Log-Likelihood Ratio (LLR) value for the information bits generated by the first decoder 120 is again interleaved before being input to the second decoder 124. By being Have the same order, and are transmitted with a slight time difference on the transmitted frame. , Wow Is combined in a decoder of the Maximum A posteriori Probability (MAP) algorithm, and thus the time diversity effect can be obtained in the turbo encoder 10. In addition, the LLR value for the information bit output from the second decoder 124 may be deinterleaved. ), The original [1 2 3 4 5 6 7 8 9] has a sequence sequence, and the first decoder 120 performs the repeated decoding while obtaining the time diversity effect.

The turbo code has an error correction capability that is close to Shannon's channel capacity through an iterative decoding method, and it is possible to calculate a recursive structure and has a very high calculation amount. Increasing the number of iterative decodings in the turbo code results in better performance, but causes slow operation due to long delays. Therefore, when turbo code is applied to a real system, there is a problem of an increase in system performance and an interchangeable choice of delay.

In addition, as the number of times of repeated decoding increases, battery consumption in the terminal increases. Particularly, in the next generation high-speed wireless Internet mobile communication as well as the existing wireless communication system, the battery consumption is expected to increase due to the large LCD.

Accordingly, there is still a need for turbo codes used in wireless communication channel codes to be designed to extend the life of the battery and increase system operating efficiency by reducing the number of repetitive decoding times.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a turbo encoding method and a turbo decoding method which improve long delay components, decrease repetition decoding times, improve system performance, and improve system operation efficiency, which are problems of conventional turbo codes.

Another object of the present invention is to provide a turbo encoder and a turbo decoder for performing the turbo encoding method.

1 is a block diagram showing the structure of a conventional turbo system.

2 is a block diagram showing the structure of a turbo encoder according to a preferred embodiment of the present invention.

3 is a flow chart showing the main steps of a turbo encoding method according to a preferred embodiment of the present invention carried out in the turbo encoder of FIG.

Figure 4 is a block diagram showing the structure of a turbo decoder according to a preferred embodiment of the present invention.

5A and 5B are flowcharts showing main steps of a turbo decoding method according to a preferred embodiment of the present invention performed in the turbo decoder of FIG.

6 is a graph showing simulation results for the case where the BER characteristics of the conventional turbo encoding / decoding method and the turbo encoding / decoding method according to the present invention are shown while changing the frame length based on the block interleaver.

7 is a graph illustrating a comparison of BER characteristics of a conventional turbo encoding method and decoding method and a turbo encoding method and decoding method according to the present invention by fixing a frame length to 1024 bits and varying an interleaver.

8 is a graph illustrating a comparison between the performance of a conventional turbo code according to the number of repetitions and the turbo code according to the present invention.

9 is a graph comparing the performance of the Turbo Coded MC-CDMA system and the ETD-Turbo Coded MC-CDMA system.

In the turbo encoding method according to the present invention for achieving the above technical problem, in the turbo encoding method used for channel encoding of a wireless communication system, (a) Is a predetermined positive integer Interleaving a to a first interleaver; (b) the interleaved bit string in step (a) Construct-code the first parity bit string Obtaining a; (c) bit stream interleaved in step (a) Interleaving a second interleaver; And (d) the interleaved bit string in step (c). Construct-code a second parity bit string To obtain; characterized in that it comprises a.

In the turbo encoding method, after the step (d), the first parity bit string obtained in the step (b) is obtained. And the second parity bit string obtained in the step (d). Multiplexing and transmitting through a channel; preferably further includes.

In addition, the turbo decoding method according to the present invention for achieving the above technical problem, (a) Is a predetermined positive integer Interleaving a first interleaver, and interleaving a bit stream. Construct-code the first parity bit string Obtaining an interleaved bit stream Interleaving a second interleaver, and the interleaved bit stream Construct-code a second parity bit string The information bit stream encoded by the turbo encoding method comprising the step of obtaining the information and transmitted through a wireless communication channel. And parity bit strings Inputting; (b) a sequence of information bits through the channel ( ) And the interleaved information bit stream ( Obtaining; (c) the parity bit is passed through the channel By demultiplexing Wow Separating into; (d) interleaved information bit streams ( ) And the first interleaver ( Parity bit string () ), And will be described below. To decrypt the LLR value ( Obtaining; And (e) aligning the order of the Log-likelihood Ratio (LLR) values transmitted between the decoders.

In addition, the turbo decoding method, after the step (e), (f) LLR value ( )in And dictionary information ( By removing) Obtaining; (g) external information ( By interleaving the previous information of the second decoder ( Obtaining; (h) Interleaving the interleaved bit stream Obtaining; (i) dictionary information ( ), Through two interleavers Wow To decrypt the dictionary information ( Obtaining; (j) output from the second decoder in Wow By removing the external information ( Obtaining; And (k) external information ( ) By deinterleaving the first decoder Obtaining; (l) after sufficient repetitive decoding To the second deinterleaver ( Deinterleaving); And (m) information bits by soft limiting on the deinterleaved bit stream. It is preferable to further include; determining).

In addition, the turbo encoder according to the present invention for achieving the above another technical problem. Is a predetermined positive integer A first interleaver to interleave the first interleaver; Interleaved Bit String Construct-code the first parity bit string A first encoder for outputting; Interleaved Bit String A second interleaver to interleave the second interleaver; And interleaved bit stream Construct-code a second parity bit string It characterized in that it comprises a; a second encoder for outputting the.

In addition, the turbo decoder according to the present invention for achieving the above another technical problem Is a predetermined positive integer Interleaving a first interleaver, and interleaving a bit stream. Construct-code the first parity bit string Obtaining an interleaved bit stream Interleaving a second interleaver, and the interleaved bit stream Construct-code a second parity bit string The information bit stream encoded by the turbo encoding method comprising the step of obtaining the information and transmitted through a wireless communication channel. And parity bit strings To enter the information bit string ( ) And the interleaved information bit stream ( ) 3rd Interleaver () ); Parity bit is passed through the channel To Wow Demultiplexer to separate into; Interleaved information bit stream ( ) And the first interleaver (204: Parity bit string () ), And will be described below. To decrypt the LLR value ( A first decoder to obtain; A fourth interleaver provided between the first decoder and the second decoder to match a log-likelihood ratio (LLR) value transmitted between the decoders ) And the first deinterleaver ( ); LLR value output from the first decoder )in And dictionary information ( By removing) A first adder for obtaining < RTI ID = 0.0 > Interleaving the interleaved bit stream ) Fifth interleaver ( ); Dictionary Information ( ), Through two interleavers Wow To decrypt the dictionary information ( A second decoder to obtain; Output from the second decoder in Wow By removing the external information ( A second adder for obtaining < RTI ID = 0.0 > After enough repetitive decoding A second deinterleaver for deinterleaving ); And by soft limiting the deinterleaved bit strings. Soft limiter to determine); characterized in that it comprises a.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram illustrating a structure of a turbo encoder according to a preferred embodiment of the present invention, and FIG. 3 is a flowchart illustrating main steps of a turbo encoding method according to a preferred embodiment of the present invention performed in the turbo encoder of FIG. 2. As shown. 3 is often referenced below.

2, a turbo encoder 20 according to a preferred embodiment of the present invention includes a first interleaver 202, a first encoder 204, a second interleaver 206, and a second encoder 208. do. Compared with the conventional turbo encoder, the turbo encoder according to the present invention has one more interleaver inserted so that the first interleaver ( ) And the second interleaver ( The difference is that it has two interleavers. here, Represents the input bit string, Wow Represents the interleaver , , And Each represents an output bit string.

The operation of the turbo encoder as described above will be described.

First interleaver ( ) Is the input information bit string ( ) And the interleaved information bit stream ( ) Is output (step S302). Next, the first encoder 204 is interleaved information bit string ( ) Is encoded to form a first parity bit string ( ) Is output (step S304).

Next, the second interleaver ( ) Is the interleaved information bit stream ( ) To interleave the first interleaver ( ) And the second interleaver ( Bit strings ) Is output (step S306). First interleaver ( ) And the second interleaver ( Bit strings ) Is a new array ( Is defined as

Next, the second encoder 208 is interleaved bit string ( ) And the second parity bit string ( ) Is output (step S308).

First parity bit string obtained in the step S304 And the second parity bit string obtained in the step S308. Is multiplexed by a multiplexer (not shown) and transmitted over a wireless channel.

if, = [5 6 9 1 4 2 8 3 7], = [8 2 7 4 3 6 9 5 1] In the case of having the same order as the first interleaver 202: String of information passed by ) The first interleaver 202 is represented by the same interleaving pattern as ) And the second interleaver (206: Input bit string () ) Is the new interleaving pattern = [3 6 8 1 9 2 7 4 5] The output bit string of the encoder 20 can be represented as shown in Table 1.

In the conventional turbo encoder Wow Has the same order, and the interleaver ( Passed) Only pass the channel in the order of the interleaving pattern. On the other hand, as shown in Table 1, the output of the turbo encoder 20 according to the embodiment of the present invention , , And 2 shows two interleavers ( , By outputting in a different order, respectively, the receiver reaches the receiver through different paths, thereby increasing the time diversity effect in the decoding step.

On the other hand, Figure 4 is a block diagram showing the structure of a turbo decoder according to a preferred embodiment of the present invention, Figures 5a and 5b of the turbo decoding method according to a preferred embodiment of the present invention performed in the turbo decoder of Figure 4 The main steps are shown in a flowchart.

Referring to FIG. 4, the turbo decoder 40 according to the preferred embodiment of the present invention may include a third interleaver 402. ), A demultiplexer 404, a first decoder 406, and a first adder 408. In addition, the turbo decoder 40 is a fourth interleaver 410: ), Fifth interleaver 412 ), And a second decoder 414. The turbo decoder 40 also includes a second adder 416, a second deinterleaver 418, a second deinterleaver 420, and a soft limiter 422.

The operation of the turbo decoder 40 will be described. First, the turbo decoder 40 receives Wow Is input. here Is a string of information input bits ) Passes through the channel. Third interleaver 402: ) Is the string of information bits ( ) And the interleaved information bit stream ( ) Is obtained (step S502).

The demultiplexer 404 is a form in which parity bits pass through the channel. To Wow (Step S504). here, Is the first interleaver 204 of the encoder 20: Parity bit string) Is the first interleaver 204 ) And the second interleaver (208: ) Both are rough, i.e. Indicates a parity bit string.

Next, the first decoder 406 stores the interleaved information bit stream ( ) And the first interleaver (204: Parity bit string () ), And will be described below. To decrypt the LLR value ( ) Is obtained (step S506).

On the other hand, the fourth interleaver 410 provided between the first decoder 406 and the second decoder 414 of the turbo decoder 40: ) And the first deinterleaver ( ) To match the Log-likelihood Ratio (LLR) values transmitted between the decoders 406 and 414.

Table 2 shows the input order of the first decoder 406. Referring to Table 2, Has the order [1 2 3 4 5 6 7 8 9] of the input bit string input from the turbo encoder 20, The third interleaver 402 before being input to the first decoder 406 to decode in order ) = [5 6 9 1 4 2 8 3 7] Is input to the first decoder 406.

Next, Table 3 shows the input order of the second decoder 414. Here, too, as in the first decoder 406 and The third interleaver 402 to match the input order of ) And the fourth interleaver 410: Rough) It is input to the second decoder 414 in the order of = [3 6 8 1 9 2 7 4 5].

Next, the first adder 408 is a LLR value (outputted from the first decoder 406). )in And dictionary information ( By removing) ) Is obtained (step S508). Next, the fourth interleaver 410: ) Is external information ( By interleaving the previous information of the second decoder 414 ( ) Is obtained (step S510).

Fifth interleaver 412 ) Interleaving the interleaved bit stream ) Is obtained (step S512). The second decoder 414 is a dictionary information ( ), Through two interleavers Wow To decrypt the dictionary information ( ) Is obtained (step S514).

On the other hand, the second adder 416 is output from the second decoder 414 in Wow By removing the external information ( ) External information ( ) Is again the first deinterleaver 418: Deinterleaving by the first information of the first decoder 406 ( ) After sufficient repetitive decoding (step S516) is made through this process, Is the second deinterleaver 420: Deinterleaved by and Will be out of effect. Next, by soft limiting by the soft limiter 422, the information bit ( ) Is determined.

The structural features will be described again in the encoder and decoder sections, respectively. One more interleaver, and in the decoder , and Interleaver array different from the existing decoder configuration And ) And deinterleaver array ( And )

Now, the performance effects of the turbo encoding method / decoding method and the turbo encoder / decoder according to the present invention as described above will be described. In order to evaluate the performance of the turbo encoding method / decoding method and the turbo encoder / decoder according to the present invention, the performance of the conventional turbo code form and the performance were compared and analyzed. The turbo encoder proposed in the present invention increases the time diversity effect of the turbo code and improves the system performance by using one more interleaver as compared to the conventional turbo encoder.

For evaluation, four kinds of interleavers, in this embodiment, a block interleaver, a helical interleaver, a random interleaver, and a mother interleaver, are used for bit strings having three different frame lengths. (mother interleaver) was combined to simulate a mixed AWGN (Rayleigh fading) and additive white Gaussian noise (AWGN). In the simulation environment, the code rate of the turbo code was 1/3, the number of iterations was repeated five times, and the log-MAP (maximum a posteriori probability) algorithm was used for decoding.

FIG. 6 is a graph showing simulation results for the case of showing the BER characteristics of the conventional turbo encoding / decoding method and the turbo encoding / decoding method according to the present invention while changing the frame length based on the block interleaver. 6, prior art_512, prior art_1024, and prior art_4096 show BER characteristics of a conventional turbo encoding / decoding method using a block interleaver. Each frame length is 512 bits and 1024 bits. , And 4096 bits. In addition, the present invention_512, the present invention_1024, and the present invention_4096 are characteristics of the turbo encoding / decoding method according to the present invention, in which the first interleaver and the second interleaver use a block interleaver, and each frame length is 512. Bits, 1024 bits, and 4096 bits. As can be seen from the simulation results, the block interleaver is used, and the block length is 1024 bits and 4096 bits, and the block length is 1024 bits and 4096 bits. . Especially if they have the same frame length (4096 bits) In the BER of the present invention, the turbo encoding method / decoding method corresponding to the present invention_4096 is better than the conventional turbo encoding method / decoding method corresponding to the prior art 4096. Of It can be seen that is about 1dB lower.

Next, FIG. 7 shows a graph comparing the BER characteristics of the conventional turbo encoding method and the decoding method and the turbo encoding method and the decoding method according to the present invention by fixing the frame length to 1024 bits and varying the interleaver. As is known in many studies, random interleaver is better than turbo code using block interleaver, but in practice, random interleaver is ideal and is known as an interleaver technology that is difficult to use.

However, referring to FIG. 7, in the case of the turbo encoding method and the decoding method according to the present invention using two block interleavers (block_block), Of Shows a BER similar to that of a conventional turbo coder using an ideal random interleaver, and when the block interleaver and the helical interleaver are used in the turbo coder according to the present invention, the performance is better than the turbo code using the random interleaver. Is showing.

Next, FIG. 8 is a graph illustrating a comparison of the BER characteristics of the conventional turbo encoding method and the decoding method according to the number of repetitions and the turbo encoding method and the decoding method according to the present invention. Referring to FIG. 8, Of = 4 dB, frame length is fixed at 1024 bits, the conventional turbo coding method and decoding method using a block interleaver and the turbo coding method and decoding according to the present invention using two block interleaver compared BER according to the number of iterative decoding It became. In the turbo encoding method and the decoding method according to the present invention, even if the number of iterations is about twice, It can be seen that the abnormality is maintained. In other words, since the turbo encoding method and the decoding method according to the present invention use two interleavers, they may be complicated in configuration. However, the delay due to repetitive decoding, which is one of the disadvantages of the turbo code, can be drastically reduced, and the performance and operation of the system It can be seen that it is excellent in efficiency.

The performance effect when the encoder and decoder are applied to the system will be described. The turbo encoding method and the decoding method according to the present invention were applied to an MC-CDMA system to evaluate the performance. For more efficient analysis, the number of iterations for the Turbo Coded MC-CDMA system using the block interleaver and the Turbo Coded MC-CDMA system using the two block interleavers Of We reviewed the performance of the system for.

9 is a graph illustrating a comparison between the performance of a Turbo Coded MC-CDMA system employing a conventional turbo coding method and a decoding method and a Turbo Coded MC-CDMA system employing a turbo coding method and a decoding method according to the present invention. In FIG. 9, # 1, # 3, and # 5 represent the number of times of repeated decoding, and represent 1, 3, and 5 times, respectively. As the number of iterations increases, the probability of error in the system is lowered, but the delay is increased, so the selection of an appropriate number of iterations is important. The average Turbo Coded system chooses three to five times on average.

Referring to FIG. 9, in the case of the Turbo Coded MC-CDMA system to which the turbo code encoding method and the decoding method according to the present invention are applied in the simulation result, the result of performing the three times of iterative decoding times is the turbo to which the conventional turbo coding method and decoding method are applied. It can be seen that the coded MC-CDMA system exhibits better performance than the case of five times of repeated decoding times.

According to the present invention as described above, it is possible to reduce the delay of the turbo code by reducing the number of iterative decoding during turbo encoding and decoding. In addition, when the turbo encoding method and the decoding method according to the present invention are applied to a system such as MC-CDMA, the ETD- according to the present invention can be reduced in comparison with the conventional TurboCoded system since the error probability can be reduced and the number of repeated decoding can be reduced. You can see that the Turbo Coded system is more efficient.

The scope of the present invention is not limited to the above embodiments, but may be modified or modified by those skilled in the art within the scope of the present invention as defined by the appended claims.

In addition, the turbo encoding method and the decoding method according to the present invention as described above can be created by a program executed in a personal or server-class computer. Program codes and code segments constituting the program can be easily inferred by computer programmers in the art. The program may also be stored in a computer readable recording medium or an integrated circuit in the form of an application specific IC (ASIC). The computer readable recording medium includes a magnetic recording medium, an optical recording medium, and a propagation medium.

As described above, according to the present invention, the performance of the system is improved by increasing the time diversity effect as compared to the conventional turbo coding method, and the delay due to the iterative decoding which is the biggest problem of the conventional turbo decoding method. By reducing the efficiency of the system can be improved.

Claims (8)

In the turbo coding method used for channel coding of a wireless communication system, (a) Is a predetermined positive integer Interleaving a to a first interleaver; (b) the interleaved bit string in step (a) Construct-code the first parity bit string Obtaining a; (c) bit stream interleaved in step (a) Interleaving a second interleaver; And (d) bit stream interleaved in step (c) Construct-code a second parity bit string Obtaining a; Turbo encoding method comprising a. The method of claim 1, wherein after step (d), First parity bit string obtained in step (b) And the second parity bit string obtained in the step (d). Multiplexing and transmitting the signal through a channel; (a) Is a predetermined positive integer Interleaving a first interleaver, and interleaving a bit stream. Construct-code the first parity bit string Obtaining an interleaved bit stream Interleaving a second interleaver, and the interleaved bit stream Construct-code a second parity bit string The information bit stream encoded by the turbo encoding method comprising the step of obtaining the information and transmitted through a wireless communication channel. And parity bit strings Inputting; (b) a sequence of information bits through the channel ( ) And the interleaved information bit stream ( Obtaining; (c) the parity bit is passed through the channel By demultiplexing Wow Separating into; (d) interleaved information bit streams ( ) And the first interleaver (204: Parity bit string () ), And will be described below. To decrypt the LLR value ( Obtaining; And (e) aligning the order of the Log-likelihood Ratio (LLR) values transmitted between the decoders. The method of claim 3, wherein after step (e), (f) LLR value ( )in And dictionary information ( By removing) Obtaining; (g) external information ( By interleaving the previous information of the second decoder ( Obtaining; (h) Interleaving the interleaved bit stream Obtaining; (i) dictionary information ( ), Through two interleavers Wow To decrypt the dictionary information ( Obtaining; (j) The second adder 416 is output from the second decoder 414. in Wow By removing the external information ( Obtaining; And (k) external information ( ) By deinterleaving the first decoder Obtaining; (l) after sufficient repetitive decoding To the second deinterleaver ( Deinterleaving); And (m) Information bits (by soft limiting) Determining a); the turbo decoding method further comprising. In the turbo encoder used for channel coding of a wireless communication system, Is a predetermined positive integer A first interleaver to interleave the first interleaver; Interleaved Bit String Construct-code the first parity bit string A first encoder for outputting; Interleaved Bit String A second interleaver to interleave the second interleaver; And Interleaved Bit String Construct-code a second parity bit string And a second encoder for outputting the turbo encoder. The method of claim 5, First parity bit string And second parity bit stream And a multiplexer for multiplexing the turbo encoder. Is a predetermined positive integer Interleaving a first interleaver, and interleaving a bit stream. Construct-code the first parity bit string Obtaining an interleaved bit stream Interleaving a second interleaver, and the interleaved bit stream Construct-code a second parity bit string The information bit stream encoded by the turbo encoding method comprising the step of obtaining the information and transmitted through a wireless communication channel. And parity bit strings By typing String of information bits passed through the channel ( ) And the interleaved information bit stream ( ) Third interleaver ( ); Parity bit is passed through the channel To Wow Demultiplexer to separate into; Interleaved information bit stream ( ) And the first interleaver ( Parity bit string () ), And will be described below. To decrypt the LLR value ( A first decoder to obtain; A fourth interleaver provided between the first decoder and the second decoder to match a log-likelihood ratio (LLR) value transmitted between the decoders ) And the first deinterleaver ( ); LLR value output from the first decoder )in And dictionary information ( By removing) A first adder for obtaining < RTI ID = 0.0 > Interleaving the interleaved bit stream ) Fifth interleaver ( ); Dictionary Information ( ), Through two interleavers Wow To decrypt the dictionary information ( A second decoder to obtain; Output from the second decoder in Wow By removing the external information ( A second adder for obtaining < RTI ID = 0.0 > After enough repetitive decoding A second deinterleaver for deinterleaving ); And By soft limiting the deinterleaved bit stream, the information bits ( Turbo limiter comprising a; soft limiter for determining. The method of claim 7, wherein The fourth interleaver ( ) Is external information ( By interleaving the previous information of the second decoder ( ), The first deinterleaver ( ) Is external information ( ) By deinterleaving the previous information of the first decoder Turbo decoder, characterized in that for outputting.