Convergence analysis of SCCPM with iterative decoding
P. Moqvist, Tor Aulin · 2002
A convergence analysis of serially concatenated continuous phase modulation (SCCPM) with iterative decoding is presented, based on extrinsic information density evolution. Earlier conclusions from union bounds to maximum likelihood decoding that could not be verified by simulations can now be explained. This includes the effect of more complex outer codes and of inner CPM systems with input weight 1 error events. Due to their trivial feed-forward polynomial, all CPM systems provide good initial decoder convergence. Still the role of the CPM state complexity is not well explained. Finally, bit error rate performance per iteration is estimated from the diagrams, showing good coherence with simulation results.