Adaptive Bit - Interleaved Coded Modulation Fortime - Varying Channels Using Outdated Fading

Adaptive signaling schemes, which employ the current channel fading values to optimize the transmitted signal, have recently been presented for time-varying Rayleigh fading channels. These schemes have employed set-partitioned trellis-coded modulation (TCM) and have adapted the number of uncoded bits on a given symbol based on the corresponding channel estimate. However, the characterization of the channel variation indicates that the proposed adaptive TCM schemes will not perform well on channels with high mobility, as uncoded bits are unreliable on such channels. Thus, in this paper, adaptive bit-interleaved coded modulation is introduced. As will be shown, adaptive bit-interleaved coded modulationschemes can be used to remove the need for parallel branches in the trellis-even when the signal sets are being adapted. This observation is used to design adaptive signaling schemes for highly mobile systems that demonstrate a signiicant bandwidth eeciency gain over previously proposed adaptive TCM schemes and conventional (nonadaptive) schemes.