Hierarchical QAM BICM MIMO systems with iterative decoding and applications to media broadcast

Abstract

The paper presents an approach to the design of layered BICM MIMO systems using multi-stage iterative decoding and Soft Output M-Algorithm (SOMA) based component decoders. The systems consider transmission based on multilevel coding linked to hierarchical QAM constellations. The receivers are iterative designs with a view to supporting high-rates. These receiver designs can also be used to obtain reduced complexity. The performance of the SOMA schemes are compared to achievable rate bounds for multi-level D-BLAST based schemes. The D-BLAST receivers illustrate general limitations of non-iterative approaches. The multi-layer transmission approach provides a natural support for unequal error protection (UEP), and can be used to balance tradeoffs between robust coverage vs quality in media broadcast applications. Rough predictions on such tradeoffs are given using layered MPEG2 video as a media example.