Power and Bandwidth Efficient Q-Ary LDPC Coded Partial Response Continuous Phase Modulation

Continuous Phase Modulation (CPM) provides an attractive option for spectral efficient communication systems. Binary low-density parity-check (LDPC) coded CPM can improve power efficiency and attain high error correcting capacity, but the convergence of threshold is still much higher than Shannon limit. In order to improve bit error performance, bandwidth efficiency and reduction of convergence threshold compared to above-mentioned scheme, we employ LDPC codes over GF(q>2) as the outer code. In this paper, the combination of q-ary LDPC coding and partial response CPM (PRCPM) is presented, then the effect of LDPC code length, code rate and iterative number on the performance of the system is studied. In the proposed scheme, q-ary LDPC codes and PRCPM are considered together to improve both error performance and bandwidth efficiencies, and the combination can achieve better trade-off between power efficiency and bandwidth efficiency than binary LDPC coded CPM. Meanwhile, the LDPC codes over GF(q) combined with q-ary CPM can avoid the conversion from bit probability to symbol probability and its inversion in combination of binary LDPC coded q-ary CPM, and improve reliability of information transmission.