Performance of low-density parity-check codes with 16-QAM in fading channels

The rate design rules for the multilevel coding (MLC) are studied over the Rayleigh fading channel. By simulations on 16-QAM and Ungerboeck mapping, it is speculated that the coding exponent rule is yet the best for finite length. The MLC scheme using low-density parity-check (LDPC) codes performs within 2dB above the capacity limit at the bit error rate 10-5 for bandwidth efficiency 2-bits/symbol in the fully interleaved channel with channel state information. LDPC schemes suffer less signal-to-noise ratio penalty in correlated channels.