Iterative source coded modulation: turbo error concealment by iterative demodulation

In this paper we propose to combine the exploitation of residual source redundancy and iterative demodulation of multilevel modulations in a turbo-like process to improve error concealment for the source codec parameters. The developed system, denoted as iterative source coded modulation (ISCM), uses the bandwidth efficiently since no channel code increases the transmitted bit rate. Thus, ISCM is suitable for communication systems without channel coding, but it can be enhanced by a channel code to resemble a multiple turbo code. Furthermore, without a complex channel decoder ISCM requires relatively low computational complexity. Nonetheless, simulations demonstrate considerable performance gains by ISCM with few iterations and small interleaver sizes. Additionally, measures are derived to ensure a correct relation between the unequal error protection in multilevel modulation and the different significance of bits of source codec parameters.