Reduced latency turbo decoding
Marc Fossorier2005, IEEE 6th Workshop on Signal Processing Advances in Wireless Communications, 2005.
Sign up for access to the world's latest research
checkGet notified about relevant papers
checkSave papers to use in your research
checkJoin the discussion with peers
checkTrack your impact
Abstract
Reduced latency versions of iterative decoders for turbo codes are presented and analyzed. The proposed schemes converge faster than standard and shuffled decoders. EXIT charts are used to analyze the performance of the proposed algorithms. Both theoretical analysis and simulation results show that the new schedules offer good performance / complexity trade-offs.
Related papers
Iterative Decoding of Turbo Codes
Journal of Advanced College of Engineering and Management, 2018
This paper presents a Thesis which consists of a study of turbo codes as an error-control Code and the software implementation of two different decoders, namely the Maximum a Posteriori (MAP), and soft-Output Viterbi Algorithm (SOVA) decoders. Turbo codes were introduced in 1993 by berrouet at [2] and are perhaps the most exciting and potentially important development in coding theory in recent years. They achieve near-Shannon-Limit error correction performance with relatively simple component codes and large interleavers. They can be constructed by concatenating at least two component codes in a parallel fashion, separated by an interleaver. The convolutional codes can achieve very good results. In order of a concatenated scheme such as a turbo codes to work properly, the decoding algorithm must affect an exchange of soft information between component decoders. The concept behind turbo decoding is to pass soft information from the output of one decoder to the input of the succeeding one, and to iterate this process several times to produce better decisions. Turbo codes are still in the process of standardization but future applications will include mobile communication systems, deep space communications, telemetry and multimedia. Finally, we will compare these two algorithms which have less complexity and which can produce better performance.
Performance Comparison of Turbo Decoding Algorithms
2010
Turbo coding is the most commonly used error correcting scheme in wireless systems resulting in maximum coding gain. In this paper, a comparative study of the symbol-bysymbol maximum a posteriori (MAP) algorithm, its logarithmic versions, namely, Log-MAP and Max-Log-MAP decoding algorithms used in SISO Turbo Decoders are analyzed. The performance of Turbo coding algorithms are carried out in terms of bit error rate (BER) by varying parameters such as Frame size, number of iterations and choice of interleaver. Keywords-: Iterative decoding; MAP decoding; Turbo Codes.
Increasing the speed of parallel decoding of turbo codes
2009 Ph.D. Research in Microelectronics and Electronics, 2009
Iterative Decoding Termination Schemes for Turbo Code Performance Optimization
2013
Use of turbo codes is more popular in most of the wireless applications, because of its greater Error control ability. The BER performance reaches to the Shannon's channel capacity limit. Turbo code implementation using SISO decoders with iterative MAP decoding algorithms introduces large time delay to recover the transmitted information bits. This results in increasing Wi-Max system complexity and storage requirement (Memory size). In this paper, the efforts have been made to propose the methods for effective termination of iterations to make the decoder efficient, in terms of reduction in the time delay and the requirement of memory size while maintaining the BER performance. Authors have propose various termination techniques which help in reducing the complexity as compare to conventional MAP decoding algorithm for same BER performance.
Soft-Output Decoding Algorithms In Iterative Decoding of Turbo Codes
JPL TDA Progress …, 1996
Turbo Codes: From First Principles to Recent Standards
Elsevier eBooks, 2014
This chapter is a general introduction to the original turbo codes discovered in the early 1990s and also known as convolutional turbo codes or parallel concatenated convolutional codes. It presents the main concepts of coding theory introduced with the invention of turbo codes, put in an historical perspective. The overall structures of the encoder and decoder are analyzed and some fundamental guidelines for the design of turbo codes with good performance are provided. Then, the basics of turbo decoding are introduced and the main component decoding algorithms are briefly described. Finally, the very first proof-of-concept implementations are described and the pioneer telecommunication applications and current transmission standards using turbo codes are reviewed.
Iterative Decoding Termination Schemes for Turbo Code Performance Optimization In Mobile Wi-Max Environment
2013
Use of turbo codes is more popular in most of the wireless applications, because of its greater Error control ability. The BER performance reaches to the Shannon’s channel capacity limit. Turbo code implementation using SISO decoders with iterative MAP decoding algorithms introduces large time delay to recover the transmitted information bits. This results in increasing Wi-Max system complexity and storage requirement (M emory size). In this paper, the efforts have been made to propose the methods for effective termination of iterations to make the decoder efficient, in terms of reduction in the time delay and the requirement of memory size while maintaining the BER performance. Authors have propose various termination techniques which help in reducing the complexity as compare to conventional MAP decoding algorithm for same BER performance.
Turbo Codes: Promises and Challenges
Channel coding is a powerful technique to get reliable communication over noisy channels. The performance of the coding system is bounded by Shannon limit. Lately, the proposal of parallel-concatenated convolutional code (PCCC), called turbo codes, has increased the interest in the coding area since these codes give most of the gain promised by the channel-coding theorem. Because turbo codes did not actually results from applying a pre existing theory, most of their outstanding features remain to be explained. The objective of this paper is to introduce turbo codes and the key elements to their superiority. Open problems and unresolved issues will be highlighted.
A practical algorithm for turbo-decoding enhancement
2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512), 2004
It has been demonstrated that the BER (bit error rate) performance of turbo codes may be enhanced by applying an adaptive control technique to suppress transient dynamics in the turbo-decoding algorithm. In this work, we extend the method to a suboptimal decoding scheme, which is more suitable for practical implementation, and discuss the effect of metrics quantization.
A parallel APP decoding algorithm for accelerating decoding throughput of turbo codes
2008 IEEE International Symposium on Wireless Communication Systems, 2008
We propose a parallel a posteriori probability (APP) decoding algorithm for increasing the decoding throughput of turbo codes. The parallel decoding algorithm divides a noisy codeword into multiple sub-blocks which are decoded in parallel. The authors in [1] proposed utilizing the forward and backward variables computed by neighbor sub-blocks in the previous iteration as the initial boundary conditions for each sub-block in the current iteration. We extend this algorithm by organizing sub-blocks into odd and even numbered groups, which perform recursions in unison but in the opposite directions. This enables more efficient utilization of the boundary conditions. We show by means of numerical simulations that our proposed algorithm further improves the decoding throughput of turbo codes in highly parallel decoding scenarios.
Related topics
Related papers
A Survey Paper on Different Turbo Decoders and Their Comparison
In order to have reliable communication, channel coding is often employed. Turbo code as a powerful coding technique has been widely studied and used in communication systems. Turbo coding is an advanced forward error c o r r e c t i o n a l g o r i t h m . U l t i m a t e Performance that approaches the Shannon limit requires a new approach using iteratively run soft in/soft out (SISO) decoders called turbo decoders. However, the implementation of various Turbo Decoders suffers from a large delay and high power consumption. For this reason, they are not suitable for many applications like mobile communication systems. In this paper, a comparative study has been made and various decoding algorithm used in SISO Turbo Decoders have been analyzed viz. MAP, Log-MAP, Max-Log-MAP and SOVA, to overcome this drawback. This paper examines the principles of turbo coding and decoding algorithms and compare their BER performance.
Analysis of Structure of Efficient Encoding Approach of Turbo Decoder
Communications on Applied Electronics, 2015
To deal with n numbers of user simultaneously and error free communication with maximum utilization of limited spectrum, BER(bit error rate) improvement is an open challenge for communication engineers. In this paper work is an attempt to implement such an error control code Turbo code in which BER improve by using various efficient encoding and decoding designs. Turbo code provides modest decoding complexity for large block length and better bit error rate as compared to other code. According to [7] RSC encoder provides minimum error probability is implemented. For testing AWGN wireless channel is used. Recursive structure along with BPSK modulation is used. The decoding algorithm such as Viterbi algoritm,MAP(maximum a posterior),BCJR (bahl, cocke, jelinek and raviv)can be used .
Towards an optimal parallel decoding of turbo codes
2006
High throughput decoding of turbo-codes can be achieved thanks to parallel decoding. However, for finite block sizes, the initialisation duration of each half-iteration reduces the activity of the processing units, especially for higher degrees of parallelism. To solve this issue, a new decoding scheduling is proposed, with a partial processing overlapping of two successive half iterations. Potential memory conflicts introduced by this new scheduling are solved by a constrained interleaver design. An example of application of the proposed technique shows that the complexity of the decoder is reduced by 25 % compared to a conventional approach.
THE EFFECT OF DECODING ITERATIONS ON THE PERFORMANCE OF TURBO CODE
This paper introduces the effect of decoding iterations on the performance of a new class of convolutional codes called Turbo Code. Turbo Code encoder is built using a parallel concatenation of two Recursive Systematic Convolutional (RSC) codes. The associated decoder is implemented using a feedback-decoding rule in an iterative manner.
Fast Decodable Turbo Codes
IEEE Communications Letters, 2007
Decoding delay is an important consideration for the use of turbo codes in practical applications. We propose a new structure for turbo codes which is very suitable for parallel decoding. It is shown by union bound analysis and simulation results that the proposed system performance is comparable to that of the classical turbo codes
On the suboptimality of turbo decoding in the case of short frame turbo codes and a way to improve the performance
Turbo codes are becoming a widespread and mature coding scheme, as they are included in the standards of the third generation of mobile communication systems [1]. They were originally shown to perform very well from long to medium sizes of blocks [2] thanks to their good codewords weight distribution – i.e. good free distance and low multiplicity of low weight codewords -and to the ability of iterative decoding to perform near optimum decoding in the sense of Maximum Likelihood (ML). However in recent releases of the standards they are also intended to be used for short sizes of blocks, down to 40 bits, and in those cases turbo decoding no longer provides ML decoding. The aim of this paper is first to quantify the suboptimality of turbo decoding when applied to short Parallel Concatenated Convolutional Codes as compared to ML decoding, and then to provide a way to improve the turbo decoding process in those cases. In this view the ML bounds of the considered short turbo codes are de...
A Concept Paper on‘Complexity and Performance Trade-offs of SISO Turbo Decoders’
Turbo codes are the best coding scheme for error correction in high-speed wireless systems because they achieve the highest coding gain. However, the implementation of various Turbo Decoders suffers from a large delay and high power consumption. For this reason, they are not suitable for many applications like mobile communication systems. In this paper, a comparative study has been made and various decoding algorithm used in SISO Turbo Decoders have been analyzed viz. MAP, Log-MAP, Max-Log-MAP and SOVA, to overcome this drawback. It presents the discussion of complexity and performance trade-offs of SISO Turbo decoders
Performance of Turbo Product Code Decoding in Wireless Communication
2014
In this paper, the effect of TPC decoding using Chase-II algorithm with reduced number of test patterns (TPs) is evaluated using the AWGN channel in orthogonal frequency division multiplexing (OFDM) mode. The TPC is constructed with multi-error-correcting extended BoseChaudhuri-Hocquengem (eBCH) codes. TPs are classified into different conditions based on the relationship between syndromes and the number of errors so that TPs with the same codeword are not decoded except the one with the least number of errors. The parameters considered are bit error rate (BER), Eb/N0, data rate and code rate. The research contribution shows that the percent of TPs need to be decoded for eBCH(128, 113, 2) when p = 2 for 1st iteration it is between 22% 16% and from 5th iteration onwards it is between 14% 12% for SNR = 1.5dB, 1.8dB, 2.0dB, 2.2dB, 2.4dB and 2.5dB in 802.16 system, respectively. This research contribution helps to make the 802.16 systems simpler, reduces the decoding time, complexity an...
A Novel Approach for Turbo Decoding In ISI Channel
International Journal of Computer Applications, 2012
Turbo codes are family of forward error correcting codes, whose performance is near Shannon limit. Turbo decoding is based on the maximum a-posterior algorithm (MAP) algorithm. In this paper, the problem of turbo decoding in ISI channel is studied. A Super-trellis structure method has been presented and modified turbo decoding is suggested. Two methods have been suggested for turbo decoding in ISI channel. In the first method, we take all possible combinations of output of encoder-2 and in method-2, output of each encoder is passed through channel filter independently. Method-2 performs better than method-1 but requires higher bandwidth. The improvement in performance is demonstrated through simulations.
Loading Preview
Sorry, preview is currently unavailable. You can download the paper by clicking the button above.