Combining Adaptive Coding and Modulation with Hierarchical Modulation in Satcom Systems

TL;DR

This paper proposes combining adaptive coding, modulation, and hierarchical modulation in satellite communication systems to significantly improve throughput, demonstrating over 10% gains in realistic DVB-S2 scenarios.

Contribution

It introduces a novel scheme that integrates time sharing with hierarchical modulation, including a new hierarchical 16-APSK, to enhance satellite broadcast throughput.

Findings

Over 10% throughput improvement in DVB-S2 scenarios

Hierarchical 16-APSK boosts DVB-S2 performance

Effective receiver grouping strategies enhance gains

Abstract

We investigate the design of a broadcast system in order to maximise the throughput. This task is usually challenging due to the channel variability. Forty years ago, Cover introduced and compared two schemes: time sharing and superposition coding. Even if the second scheme was proved to be optimal for some channels, modern satellite communications systems such as DVB-SH and DVB-S2 mainly rely on time sharing strategy to optimize the throughput. They consider hierarchical modulation, a practical implementation of superposition coding, but only for unequal error protection or backward compatibility purposes. We propose in this article to combine time sharing and hierarchical modulation together and show how this scheme can improve the performance in terms of available rate. We introduce the hierarchical 16-APSK to boost the performance of the DVB-S2 standard. We also evaluate various strategies to group the receivers in pairs when using hierarchical modulation. Finally, we show in a realistic use case based on DVB-S2 that the combined scheme can provide throughput gains greater than 10% compared to the best time sharing strategy.