Power and bandwidth efficient LDPC coded CPM with iterative decoding

In this paper, in order to improve bit error performance, bandwidth efficiency and reduction of complexity compared to related schemes such as turbo codes, we combine low-density parity-check (LDPC) codes and continuous phase modulation (CPM) and introduce a new scheme, called LDPC coded CPM (LDPCC-CPM). At the receiver, an iterative detection method based on SISO algorithm is proposed. Then the effect of LDPC code length, code rate, iterative number and modulation index on the performance of the system is studied. In our proposed scheme, LDPC and CPM, are considered together to improve both error performance and bandwidth efficiencies. The combination also can achieve better trade-off between power efficiency and bandwidth efficiency than SCCPM. Analysis and simulations show that - among the evaluated systems - the octal 2RC systems provide the highest power/bandwidth efficiency. As an example, rate 1/2-coded octal 2RC with modulation index 1/2 reaches 10^-5 bit error probability at E_b/N₀=2dB with information block length 768 bits.