Joint Scheduling and Precoding for Frame-Based Multigroup Multicasting in Satellite Communications

Recent satellite standards enforce the coding of multiple users' data in a frame. This transmission strategy mimics the well-known physical layer multigroup multicasting (MGMC). However, typical beam coverage with a large number of users and limited frame length lead to the scheduling of only a few users. Moreover, in the emerging aggressive frequency reuse systems, scheduling is coupled with precoding. This is addressed in this work, through the joint design of scheduling and precoding for frame -based MGMC satellite systems. This aim is formulated as the maximization of the sum-rate under per beam power constraint and minimum SINR requirement of scheduled users. Further, a framework is proposed to transform the non -smooth sum rate objective with integer scheduling and non-convex SINR constraints as a difference-of-convex problem that facilitates the joint update of scheduling and precoding. Therein, an efficient convex-concave procedure based algorithm is proposed. Finally, the gains in sum rate (up to 50%) obtained by the jointed design over state-of-the-art methods are shown through Monte-Carlo simulations.