Unequal error protection on the turbo-encoder output bits

Mohammadi, A.H.S.; Khandani, Amir K.

doi:10.1109/icc.1997.609963

Cited by 5 publications

(3 citation statements)

References 3 publications

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“…Moreover, the accurate knowledge of the weight spectrum of a Turbo code could be utilized to improve its performance by locating and improving those comparatively unreliable bits [4]- [5]. As a result, computing the weight spectra of Turbo codes is a topic of great importance in the design of Turbo codes, and has attracted much research effort so far.…”

Section: Introductionmentioning

confidence: 99%

Some New Results on Recursive Convolutional Codes and Their Applications

Chen

Mow

Fan

2006

2006 IEEE Information Theory Workshop - ITW '06 Chengdu

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In this paper, a novel decomposition representation is firstly proposed to transform a recursive convolutional code into the serial concatenation of a unit-recursive-convolutional (URC) code with unit nominator polynomial and a non-recursive convolutional (NRC) code. Since the recursive convolutional (RC) code can be regarded as a linear system if all-zero initial state is assumed, the impulse response analysis (IRA) can be applied to reveal the characteristics of the URC code, as well as the RC code. Then, a linear-algebra-like analysis method is developed to enable the computation of the impulse response via the finite field matrix manipulation. It is shown that the equivalent block generation matrix can be used to characterize an RC code completely. Moreover, there is a certain cycle (or period) in the impulse response of any RC code, which corresponds to the state transition cycle of its constituent URC code. It is disclosed that the Hamming weight in every cycle equals half of the cycle length plus one if the denominator polynomial is primitive. Furthermore, the generation matrix of its constituent URC code could be utilized to determine the ending state of an RC code for any input. Finally, it is revealed that the minimum Hamming weight of an RC code can be calculated from the generation matrix of the reverse RC code under some input constraints, thus providing an alternative algorithm for the modified Viterbi algorithm proposed for the weight spectrum calculation of Turbo codes.

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Section: Introductionmentioning

confidence: 99%

Some New Results on Recursive Convolutional Codes and Their Applications

Chen

Mow

Fan

2006

2006 IEEE Information Theory Workshop - ITW '06 Chengdu

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“…The value of is 1 if a transition from states to occurs, and is 0 otherwise. The probability is given by if if otherwise (10) where a priori probabilities are estimated by the other decoder through the iterative decoding process. The conditional probability in (9) is given by (11) where , according to ; , according to the value of the th code symbol generated when the state transits from to with input ; constant which has no influence on the decoding process.…”

Section: B Decoding Metricmentioning

confidence: 99%

“…The reason for different diversity levels for different turbo code symbols is that the various code symbols do not contribute to the bit error rate in an identical manner. In [10] and [11], different energy was assigned to the two kinds of outputs of a turbo encoder, information symbols and parity symbols, for an AWGN channel, to increase the Euclidean distance and thus improve the performance. In CDMA systems, however, a different energy assignment is not desirable since more signal energy assigned to a transmitted symbol of one user would result in stronger interference to the other users.…”

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confidence: 99%

Performance of a turbo coded multicarrier DS/CDMA system with nonuniform repetition coding

Kim

Milstein²,

Song³

2001

IEEE J. Select. Areas Commun.

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Abstract-This paper presents a turbo coded multicarrier direct sequence code division multiple access (DS/CDMA) system, where the outputs of a turbo encoder are repetition coded at multiple rates and transmitted in parallel over a number of subchannels. A performance bound useful in the so-called error floor region is obtained for Rayleigh fading channels when different diversity orders are given to each turbo code symbol. Simulation results are also provided for the low signal-to-noise ratio (SNR) region where the bound is not applicable. It is observed that the error floor can be lowered, with some performance loss in the low SNR region, by applying nonuniform repetition coding to the turbo code symbols.Index Terms-Multicarrier DS/CDMA, nonuniform repetition coding, turbo coding.

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A New Unequal Power Allocation Scheme for Asymmetric Turbo Code System

Balakrishnan

2008

Wireless Pers Commun

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In this paper, a modified unequal power allocation scheme for the different bits of asymmetric turbo encoder has been investigated to enhance the performance. The simulation results and performance bound for the asymmetric turbo code with modified Unequal Power Allocation (UPA) scheme are obtained and compared with the system with typical UPA and without UPA. From the performance results, it is observed that the proposed asymmetric turbo code with modified UPA performs better than the system without UPA and with typical UPA and it provides a coding gain of 0.4-0.52 dB.

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Unequal error protection on the turbo-encoder output bits

Cited by 5 publications

References 3 publications

Some New Results on Recursive Convolutional Codes and Their Applications

Some New Results on Recursive Convolutional Codes and Their Applications

Performance of a turbo coded multicarrier DS/CDMA system with nonuniform repetition coding

A New Unequal Power Allocation Scheme for Asymmetric Turbo Code System

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