An implementation of a soft error decoder in a multipath faded COFDM system

This paper presents a method to implement a soft error decoder. The presented decoder is optimized for use in a high-bit rate data communications system using orthogonal frequency division modulation (OFDM) over an indoor fading channel. A short description of the target system is given, and boundary conditions for the propagation environment are derived. An estimator for the attenuation caused by frequency selective fading on each OFDM carrier is presented, together with a method to estimate the variance of the channel noise. An algorithm to determine a measure of per-bit correctness probability is developed, and a soft error decoder is presented using the per-bit correctness probability. Simulation results are presented for a simulated Rayleigh fading channel and for a measured indoor channel