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A New Method for Performance Evaluation of TurboCodes
 IEEE Transactions on Communications
, 2004
"... In this paper , a new method for the performance evaluation of TurboCodes is presented. The method is based on estimating the Probability Density Function (pdf ) of the bit Log Likelihood Ratio (LLR) by using an exponential model. It is widely known that the pdf of the bit LLR is close to the no ..."
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In this paper , a new method for the performance evaluation of TurboCodes is presented. The method is based on estimating the Probability Density Function (pdf ) of the bit Log Likelihood Ratio (LLR) by using an exponential model. It is widely known that the pdf of the bit LLR is close to the normal density, and the proposed approach takes advantage of this property to simplify the calculations. The moment matching method is combined with the maximum entropy principle to estimate the parameters of the new model. A simple method for computing the confidence intervals for the estimated parameters, as well as for the Bit Error Rate (BER) is presented. The corresponding results are adopted to compute the number of samples that are required for a given precision of the estimated values. It is demonstrated that this method requires significantly fewer samples than the conventional MonteCarlo (MC) simulation.
A New Method for Performance Evaluation of TurboCodes Using . . .
 IEEE TRANSACTIONS ON COMMUNICATIONS
, 2004
"... In this paper, we present a new method for the performance evaluation of TurboCodes. The method ..."
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In this paper, we present a new method for the performance evaluation of TurboCodes. The method
Invariance Properties and Performance Evaluation of Bit Decoding Algorithms
, 2004
"... Certain properties of optimal bitwise APP (A Posteriori Probability) decoding of binary linear block codes are studied. The focus is on the Probability Density Function (pdf) of the bit LogLikelihoodRatio (LLR). A general channel model with discrete (not necessarily binary) input and discrete or c ..."
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Certain properties of optimal bitwise APP (A Posteriori Probability) decoding of binary linear block codes are studied. The focus is on the Probability Density Function (pdf) of the bit LogLikelihoodRatio (LLR). A general channel model with discrete (not necessarily binary) input and discrete or continuous output is considered. It is proved that under a set of mild conditions on the channel, the pdf of the bit LLR of a specific bit position is independent of the transmitted codeword. It is also shown that the pdf of a given bit LLR, when the corresponding bit takes the values of zero and one, are symmetric with respect to each other (reflection of one another with respect to the vertical axis). In the case of channels with binary inputs, a su#cient condition for two bit positions to have the same pdf is presented. An analytical method for approximate performance evaluation of binary linear block codes using an Additive White Gaussian Noise (AWGN) channel model with Binary Phase Shift Keying (BPSK) modulation is proposed. The pdf of the bit LLR is expressed in terms of the GramCharlier series expansion. This expansion requires knowledge of the statistical moments of the bit LLR. An analytical method for calculating these moments which is based on some recursive calculations involving certain weight enumerating functions of the code is introduced. It is proved that the approximation can be as accurate as desired, using enough numbers of terms in the GramCharlier series expansion. A new method for the performance evaluation of TurboLike Codes is presented. The method is based on estimating the pdf of the bit LLR by using an exponential model. The moment matching method is combined with the maximum entropy principle to estimate iii the parameters of the new model. A ...
Invariance Properties of Binary Linear Codes Over a Memoryless Channel With Discrete Input
"... Abstract—This work studies certain properties of the probability density function (pdf) of the bit loglikelihood ratio (LLR) for binary linear block codes over a memoryless channel with discrete input and discrete or continuous output. We prove that under a set of mild conditions, the pdf of the bi ..."
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Abstract—This work studies certain properties of the probability density function (pdf) of the bit loglikelihood ratio (LLR) for binary linear block codes over a memoryless channel with discrete input and discrete or continuous output. We prove that under a set of mild conditions, the pdf of the bit LLR of a specific bit position is independent of the transmitted codeword. It is also shown that the pdf of a given bit LLR when the corresponding bit takes the values of zero and one are symmetric with respect to each other (reflection of one another with respect to the vertical axis). For the case of channels with binary input, a sufficient condition for two bit positions to have the same pdf is presented. Index Terms—Bit decoding, block codes, geometrically uniform, loglikelihood ratio (LLR), probability density function (pdf), regular channel, symmetric channel. I.