We present an optimized channel coding scheme for OFDM transmitter. Traditional coding methods use regular codes, in the sense that each bit participates in the same way to the channel encoding. Our approach consists in using a priory assumption on the channel available at the transmitter in order to optimize the coding scheme. We have considered the… (More)
— We introduce a wide class of LDPC codes, large enough to include LDPC codes over finite fields, rings or groups as well as some non-linear codes. A belief propagation decoding procedure with the same complexity as for the decoding of LDPC codes over finite fields is also presented. Moreover, an encoding procedure is developed.
The blind separation problem of linear time-dependent mixtures is addressed in this paper. We have developed a new algorithm based on the minimization of the mutual information as well as a penalized term which ensures an a priori normalization of the estimated sources (outputs) and so, avoids the scale indeterminacy. The criterion minimization is done… (More)
This paper deals with optimized channel coding for OFDM transmissions (COFDM) over frequency-selective channels using irregular low-density parity-check (LDPC) codes. Firstly, we introduce a new characterization of the LDPC code irregularity called " irregularity profile. " Then, using this parameterization, we derive a new criterion based on the… (More)
Recommended by Luc Vandendorpe Orthogonal frequency division multiplexing (OFDM) is the modulation technique used in most of the high-rate communication standards. However, OFDM signals exhibit high peak average to power ratio (PAPR) that makes them particularly sensitive to nonlinear distortions caused by high-power amplifiers. Hence, the amplifier needs… (More)
In this paper, a new algorithm estimating channel impulse response (CIR) length and noise variance for orthogonal frequency division multiplexing (OFDM) systems with adaptive guard interval (GI) length is proposed. To estimate the CIR length and the noise variance, the different statistical characteristics of the additive noise and the mobile radio channels… (More)