1. An apparatus comprising: a receiver module configured to process a signal received over a wireless channel, wherein the received signal reflects a source signal comprising a plurality of source symbols, and includes linear inter-symbol interference (ISI) effects induced based on one or more of a faster-than-Nyquist (FTN) signaling rate and a tight frequency roll-off applied to the source signal, and non-linear interference effects induced based on high-power amplification for transmission over the wireless channel; wherein the receiver module is configured to process the received signal based on a plurality of decoding iterations, and wherein the receiver module comprises: a likelihood metric computing module configured to generate a set of soft information of a current decoding iteration based on a current estimate of the source signal and a final set of soft information from a previous decoding iteration; wherein the current estimate of the source signal is based on an estimate of the linear ISI effects and the non-linear interference effects, which is based on the final set of soft information from the previous decoding iteration.