SPECTRAL EFFICIENCY MAXIMIZATION USING PRAGMATIC MODERN RATE-COMPATIBLE CODE FAMILIES

In communication links employing incremental redundancy (IR), the strength of the code used for forward error correction is adapted in order to maximize instantaneous spectral efficiency in time-varying channels. In this paper, a simple two-phase IR transmission. scheme is studied in a block fading channel in order to illuminate the effects on protocol design and achievable spectral efficiency of the performance, rate range, and rate granularity of the chosen. rate-compatible (RC) code family. Two pragmatic RC families based on Flexible Low-Density Parity-Check (F-LDPC) codes are studied alongside a notional family with infinite rate precision that matches theoretical guidelines for the performance of practical coding schemes (i.e., limits on finite block size and non-vanishing block error rate transmission over modulation constrained channels) at all points.