Constellation Optimization Based on DDPG for Cayley Differential Unitary Space-Time Code

In multiple-input multiple-output (MIMO) systems, differential space-time coding is an effective transmission scheme in which channel knowledge is not required at the receiver. Cayley differential unitary space-time code has the advantages of high transmission rate, suitable for arbitrary antenna sizes as well as easy to encode and decode. To find the optimal constellation for Cayley differential unitary space-time code, the general exhaustive search method is computationally intensive and slow to converge. In this paper, a method based on deep determined policy gradient (DDPG) is proposed to search for the optimal constellation arrangement of the mapping parameters efficiently for Cayley differential unitary space-time code. Simulation results demonstrate the effectiveness of the proposed scheme based on DDPG.