Joint design of concatenated SPC codes and QAM modulation

This paper studies a simple coded modulation scheme for concatenated SPC codes and QAM modulation. By analyzing the approximate union bound on SPC codes considered QAM modulation, we find that in order to improve the BER performance, the parity-check bits should get stronger protection from the modulation by enlarging the Euclidean distance. On the contrary, the information bits don´t need so much protection from the modulation. At last, the optimum power distribution between the parity-check bits and the information bits is obtained. And simulation results also support our conclusion.