Constellation Design of Nonequiprobable Signal and Its Application in Parallel Combinatory Spread Spectrum System

In the parallel combinatory spread spectrum (PCSS) system, the modulated symbols are with different probability, rather than equal probability like in the original communication system. Hence the existing constellation for equal probability points are no longer the best choice. In this paper, for the symbols with different probability, a constellation design method is provided to achieve a lager minimum Euclidean distance than the convolutional constellation. Further, according to this method, a new constellation is designed for the PCSS. The simulation results show that the PCSS with the new designed constellation achieves a better performance than the original PCSS.