Cross layer optimization of iterative OFDM reception with clipping

An optimized automatic repeat request (ARQ) iterative receiver for orthogonal frequency division multiplexing (OFDM) transmission, suitable for application in double selective multipath channels in the presence of transmitter clipping is presented. The receiver is an optimized maximum aposteriori expectation maximization (MAP-EM) Turbo processor that exploits information from previous, failed transmissions of a packet. The system uses an imbedded pilot structure for initial channel estimation. We show that this configuration achieves performance very close to a system without clipping, even in hard clipping scenarios. Therefore, the proposed scheme represents a very efficient adaptive platform for OFDM ARQ when transmission non-linearities are present.