Improving Broadcast Channel Rate Using Hierarchical Modulation
The authors investigate the design of a broadcast system where the aim is to maximize the throughput. This task is usually challenging due to the channel variability. Modern satellite communications systems such as DVB-SH and DVB-S2 mainly rely on time sharing strategy to optimize throughput. They consider hierarchical modulation but only for unequal error protection or backward compatibility purposes. They propose in this paper to combine time sharing and hierarchical modulation together and show how this scheme can improve the performance in terms of available rate. They present the gain on a simple channel modeling the broadcasting area of a satellite. Their work is applied to the DVB-SH standard, which considers hierarchical modulation as an optional feature.