Capacity and coding for flat fading channels without channel state information

This paper presents a method for calculating arbitrarily tight upper and lower bounds on the capacity of a flat fading channel with M-ary inputs, where the fading process is modelled as a Gaussian random process with any spectral density. Neither the transmitter nor the receiver knows the channel state. The paper also presents a practicable method for adapting any family of codes designed for i.i.d. channels to work on correlated fading channels. Thus, the near-capacity performance of existing codes with iterative decoders can be translated directly to fading channels.