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

Abstract

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.

Joint User Scheduling, and Precoding for Multicast Spectral Efficiency in Multigroup Multicast Systems

“…Similar to most of the works in the literature, we presume that users are already grouped for the MGMC systems according to some criteria [2], [4], [8]. The design of user scheduling and precoding are coupled [7], [8], [10]. Therefore, the optimal performance requires the joint design of user scheduling and precoding [7]; this is compactly referred to as joint design in this paper.…”

“…The infeasibility of MGMC is a crucial problem to be dealt with; it is typically addressed by user scheduling (also referred to as admission control in the literature) [5], [6]. Further, precoding impacts IGI [7], [8], thereby influencing the user scheduling.…”

“…The design of user scheduling and precoding are coupled [7], [8], [10]. Therefore, the optimal performance requires the joint design of user scheduling and precoding [7]; this is compactly referred to as joint design in this paper. To the best of our knowledge, the joint design for the maximization of MC-SE is not considered in the literature.…”

“…The decoupled design of user grouping and precoding without admission control is considered in [8] for satellite systems. The true joint design of scheduling and precoding is initially addressed in [10] for unicast scenario and in [7] for frame-based MGMC scenario in satellite systems. However, the solutions of [7], [10] considered only SE maximization and its extension to MC-SE is not straightforward.…”

“…The true joint design of scheduling and precoding is initially addressed in [10] for unicast scenario and in [7] for frame-based MGMC scenario in satellite systems. However, the solutions of [7], [10] considered only SE maximization and its extension to MC-SE is not straightforward. The joint design problem is highly complex as it inherits the complications in non-convex maximization and multiplicative nature and binary variables in MC-SE.…”