Performance of variable rate bit interleaved coding for high bandwidth efficiency

We propose a bandwidth efficient error correction scheme, namely the variable rate adaptive bit-interleaved coded modulation (ABICM), for wireless mobile channel. The code rate and modulation level are varied according to the current channel state to exploit the time-varying nature of the wireless channel. Design challenges to achieve symbol-by-symbol adaptation and component codes design are addressed. A multi-level puncturing scheme is proposed to solve the problem of symbol-by-symbol puncturing and interleaving. The optimal adaptation thresholds are derived. It is found that there are significant gains relative to the fixed rate coding in terms of SNR and throughput. It is also found that the ABICM scheme is essentially not degraded in small interleaving depths. This makes the ABICM very suitable for real time applications.