Factor graph based detection approach for high-mobility OFDM systems with large FFT modes

In this article, a novel detector design is proposed for orthogonal frequency division multiplexing (OFDM) systems over frequency selective and time varying channels. Namely, we focus on systems with large OFDM symbol lengths where design and complexity constraints have to be taken into account and many of the existing ICI reduction techniques can not be applied. We propose a factor graph (FG) based approach for maximum a posteriori (MAP) symbol detection which exploits the frequency diversity introduced by the ICI in the OFDM symbol. The proposed algorithm provides high diversity orders allowing to outperform the free-ICI performance in high-mobility scenarios with an inherent parallel structure suitable for large OFDM block sizes. The performance of the mentioned near-optimal detection strategy is analyzed over a general bit-interleaved coded modulation (BICM) system applying low-density parity-check (LDPC) codes. The inclusion of pilot symbols is also considered in order to analyze how they assist the detection process

Linear Predictive Detection for Power Line Communications Impaired by Colored Noise

Robust detection algorithms capable of mitigating the effects of colored noise are of primary interest in communication systems operating on power line channels. In this paper, we present a sequence detection scheme based on linear prediction to be applied in single-carrier power line communications impaired by colored noise. The presence of colored noise and the need for statistical sufficiency requires the design of an optimal front-end stage, whereas the need for a low-complexity solution suggests a more practical suboptimal front-end. The performance of receivers employing both optimal and suboptimal front-ends has been assessed by means of minimum mean square prediction error (MMSPE) analysis and bit-error rate (BER) simulations. We show that the proposed optimal solution improves the BER performance with respect to conventional systems and makes the receiver more robust against colored noise. As case studies, we investigate the performance of the proposed receivers in a low-voltage (LV) power line channel limited by colored background noise and in a high-voltage (HV) power line channel limited by corona noise