IEEE Transactions on Signal Processing, vol. 62, no. 6, pp. 1576-1589, Mar. 15, 2014.

A Factor Graph Approach to Joint OFDM Channel Estimation and Decoding in Impulsive Noise Environments

Marcel Nassar (1), Philip Schniter (2) and Brian L. Evans (3)

(1) Mobile Solutions Lab, Samsung Information Systems America, San Diego, CA USA.
mnassar@utexas.edu

(2) Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH USA
schniter@ece.osu.edu

(3) Department of Electrical and Computer Engineering, Wireless Networking and Communications Group, The University of Texas at Austin, Austin, TX USA
bevans@ece.utexas.edu

Paper Draft

Smart Grid Communications Research at UT Austin

Abstract

We propose a novel receiver for orthogonal frequency division multiplexing (OFDM) transmissions in impulsive noise environments. Impulsive noise arises in many modern wireless and wireline communication systems, such as Wi-Fi and powerline communications, due to uncoordinated interference that is much stronger than thermal noise. We first show that the bit-error-rate optimal receiver jointly estimates the propagation channel coefficients, the noise impulses, the finite alphabet symbols, and the unknown bits. We then propose a near-optimal yet computationally tractable approach to this joint estimation problem using loopy belief propagation. In particular, we merge the recently proposed "generalized approximate message passing" (GAMP) algorithm with the forward-backward algorithm and soft-input soft-output decoding using a "turbo" approach. Numerical results indicate that the proposed receiver drastically outperforms existing receivers under impulsive noise and comes within 1 dB of the matched-filter bound. Meanwhile, with N tones, the proposed factor-graph-based receiver has only O(N log N) complexity, and it can be parallelized.

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Last Updated 04/10/13.