Bit-interleaved coded irregular modulation

We consider a simple method to improve the adaptiveness and flexibility of bit-interleaved coded modulation (BICM) with different iterative decoding schemes for bandwidth efficient transmission. The basic idea is to apply different signal constellations and mappings within one code word. The combination of different signal constellations allows a fine adaptation of the data rate to the channel characteristics with the modulation, even if only the average channel state is known at the transmitter. For a receiver performing iterative demapping and decoding (so called BICM-ID system), the mixture of different mappings enables an optimisation of the iterative decoding process according to the system requirements. We call this approach bit-interleaved coded irregular modulation (BICIM) and analyse it using EXIT charts, capacity, error bounds and error rate simulations. Copyright (C) 2006 AEIT.