Multicast Multigroup Precoding and User Scheduling for Frame-Based Satellite Communications

TL;DR

This paper develops an optimal multicast precoding and user scheduling framework for multibeam satellite systems, improving throughput and availability under power constraints, with significant gains demonstrated through realistic simulations.

Contribution

It introduces a novel optimization approach for frame-based precoding with power and availability constraints, and a multicast-aware user scheduling policy for satellite communications.

Findings

Up to 30% throughput gains over conventional systems.

Effective handling of power and availability constraints.

Enhanced multiuser diversity through channel-aware scheduling.

Abstract

The present work focuses on the forward link of a broadband multibeam satellite system that aggressively reuses the user link frequency resources. Two fundamental practical challenges, namely the need to frame multiple users per transmission and the per-antenna transmit power limitations, are addressed. To this end, the so-called frame-based precoding problem is optimally solved using the principles of physical layer multicasting to multiple co-channel groups under per-antenna constraints. In this context, a novel optimization problem that aims at maximizing the system sum rate under individual power constraints is proposed. Added to that, the formulation is further extended to include availability constraints. As a result, the high gains of the sum rate optimal design are traded off to satisfy the stringent availability requirements of satellite systems. Moreover, the throughput maximization with a granular spectral efficiency versus SINR function, is formulated and solved. Finally, a multicast-aware user scheduling policy, based on the channel state information, is developed. Thus, substantial multiuser diversity gains are gleaned. Numerical results over a realistic simulation environment exhibit as much as 30% gains over conventional systems, even for 7 users per frame, without modifying the framing structure of legacy communication standards.