Beamforming with superposition coding in multiple antenna satellite communications

In this paper, we study an optimization algorithm for beamforming with superposition coding (SCBF) and its application to multiple antenna satellite communication systems. Motivated by the channel asymmetries that are caused by both the variability of the physical channel conditions and the heterogeneity among the satellite terminals, we propose to implement SCBF in the forward link of a multi-beam satellite system. Unlike existing orthogonal transmission schemes, we multiplex multiple users' information in the power domain through SCBF in order to utilize time and spectrum resources more efficiently. To facilitate non-orthogonal multiplexing transmission in an energy efficient manner, we solve a minimum power optimization problem. Dedicated algorithms with low computational complexities are then designed to find globally optimal solutions in all scenarios. Finally, we extend our method to the computation of the rate region problem.