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 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 SR objective with integer scheduling and nonconvex 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 (up to 50%) obtained by the
jointed design over state-of-the-art methods is shown through
Monte-Carlo simulations.