Adaptive bit-interleaved coded modulation

Adaptive coded modulation is a powerful method for achieving a high spectra l efficiency over fading channels. Recently proposed adaptive schemes have employed set-partitioned trellis-coded modulation (TCM) and have adapted th e number of uncoded bits on a given symbol based on the corresponding chann el estimate. However, these adaptive TCM schemes will not perform well in s ystems where channel estimates are unreliable, since uncoded bits are not p rotected from unexpected fading. In this paper, adaptive bit-interleaved co ded modulation (BICM) is introduced. Adaptive BICM schemes remove the need for parallel branches in the trellis-even when adapting the constellation s ize, thus making these schemes robust to errors made in the estimation of t he current channel fading value. This motivates the design of adaptive BICM schemes, which will lead to adaptive systems that can support users with h igher mobility than those considered in previous work. In such systems, num erical results demonstrate that the proposed schemes achieve a moderate ban dwidth efficiency gain over previously proposed adaptive schemes and conven tional (nonadaptive) schemes of similar complexity.