Approaching capacity on correlated fading channels with unknown state

Abstract

This paper presents a new coding scheme with capacity approaching performance for correlated fading channels with unknown state. The transceiver employs a deep interleaver to decompose the original channel into a bank of independent fading sub-channels. Sub-channels are successively decoded and decisions are fed back as new training symbols. The unknown state of each sub-channel can be estimated from past channel observations and future channel outputs. We show that the sub-channel has the same capacity as the original channel, given a sufficiently large estimation window. Therefore, the correlated fading channel capacity can be approached if each sub-channel uses an optimized capacity achieving code. Simulations show a universal performance within 1 dB of capacity upper bound regardless of fading rate. The scheme is also robust against decision feedback errors when the sub-channels use a long LDPC code