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

Abstract

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 perantenna 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.

Constructive Multiuser Interference in Symbol Level Precoding for the MISO Downlink Channel

“…It can be seen from the structure of the matrix in (20) that rotation in the (b k ,b j )-plane does not change the directions of the remaining beamforming vectors. Therefore, it just modifies the value of ξ kk , and the precoder reads as…”

Generalized Multicast Multibeam Precoding for Satellite Communications

“…Additionally, the gateway serves a set of K g beams out of the K, leading to a total amount of served users equal to K g Q. We will assume a known 19 feed allocation per gateway and fixed N g and K g . Precisely, we will consider that the feeds are assigned in a consecutive fashion over the channel matrix as it is defined in the following.…”

Symbol-Level Multiuser MISO Precoding for Multi-Level Adaptive Modulation

“…This is necessary because the user expects to receive the same modulation type for all useful symbols in a frame in order to properly adjust the detection regions. The users are notified about their corresponding modulations through the signaling preamble of the frame 3 .…”