On the analysis of the MAP equalizer performance within an iterative receiver

In this paper, we consider an iterative receiver composed of a Maximum A Posteriori (MAP) equalizer and a MAP decoder. During the iterations, the equalizer and the decoder exchange extrinsic information and use them as a priori in order to improve their performance. We consider here an iterative receiver including a channel estimator. We propose to study analytically the impact of both the a priori information and the channel estimation errors on the equalizer performance. We show that it is equivalent to a shift in terms of signal-to-noise ratio (SNR) and we provide an analytical expression. Simulation results show that the analytical expression we give approximate quite well the equalizer performance.

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“…In [5], we showed that this bound is tight. When the channel is not perfectly estimated, the probability of the error event can be rewritten as…”

Section: Proof-part1: P (E M )mentioning

confidence: 92%

“…In [5], we assumed that the channel is perfectly estimated by the receiver and we showed that the use of the a priori information by the MAP equalizer is equivalent to a gain in SNR. In this paper, we consider a more realistic scheme where the channel estimation is not perfect.…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of the MAP equalizer within an iterative receiver including a channel estimator

Sellami

Roumy²,

Fijalkow³

IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004

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“…In this paper, we consider the case where the equalizer has a priori information on the data, provided by another module in the receiver, for instance the decoder in a turbo-equalizer [3]. In [4], we analyzed the impact of the a priori information on the MAP equalizer performance. Since the results presented in [4] hold only for unreliable a priori, we propose here to extend the analysis to the case of reliable a priori.…”

Section: Introductionmentioning

confidence: 99%

“…In [4], we analyzed the impact of the a priori information on the MAP equalizer performance. Since the results presented in [4] hold only for unreliable a priori, we propose here to extend the analysis to the case of reliable a priori. The study in [4] has been performed considering the a posteriori probabilities at the output of the equalizer.…”

Section: Introductionmentioning

confidence: 99%

“…Since the results presented in [4] hold only for unreliable a priori, we propose here to extend the analysis to the case of reliable a priori. The study in [4] has been performed considering the a posteriori probabilities at the output of the equalizer. However, the basic idea behind iterative processing is to exchange extrinsic probabilities among the equalizer and the decoder rather than a posteriori probabilities, in order to achieve successively refined performance [3].…”

Section: Introductionmentioning

confidence: 99%

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Performance analysis of the map equalizer with a priori and distribution of the extrinsic LLRS

Sellami

Roumy²,

Fijalkow³

IEEE 6th Workshop on Signal Processing Advances in Wireless Communications, 2005.

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ISECS, Route Menzel Chaker km 0.5,B.P 868,3018 Sfax, Tunisia ABSTRACT To combat the effects of intersymbol interference, the optimal equalizer to be used is based on maximum a posteriori (MAP) detection. We consider the case where the MAP equalizer is provided with a priori information on the transmitted data, as in a turbo equalizer. We propose to study analytically the impact of the a priori on the MAP equalizer performance. We distinguish two cases: the case of unreliable a priori and the case of reliable a priori. We show that when the a priori is reliable, it is better to perform the detection of the transmitted symbols based on the Q posteriori outputs of the MAP equalizer rather than on the a priori only. In a turbo equalizer, the equalizer and the decoder exchange extrinsic Lag Likelihood Ratios (LLRs). We propose here to study analytically their distribution. The aim of this study is to perform in the future the analytica1 convergence analysis of turbo equalizers using the MAP equalization.

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On the analysis of the MAP equalizer performance within an iterative receiver

Cited by 2 publications

References 9 publications

Performance analysis of the MAP equalizer within an iterative receiver including a channel estimator

Performance analysis of the MAP equalizer within an iterative receiver including a channel estimator

Performance analysis of the map equalizer with a priori and distribution of the extrinsic LLRS

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