Adaptive Forward Error Correction for Channels with Feedback.

Abstract

Forward error correction (FEC) without feedback always has to transmit maximum redundancy for the worst case of errors to be corrected. With feedback the redundancy can be adapted to actual channel disturbances. For Maximum-Distance-Separable (MDS) algebraic block codes, including Reed-Solomon (RS) codes, methods are described and analyzed, where parity symbols are transmitted only until enough redundancy is received to correct and detect reliably all errors and erasures in the transmitted sequence. The expected coderate is shown to be much higher than without feedback, even close to capacity for a variety of channels with and without memory, and resaonably better than the cutoff rate estimate for FEC. The method proves to be very robust against the length distribution of errors bursts.