Optimising DVB-S2 spectral efficiency with hierarchical modulation for broadband applications

Abstract

We study the design of a digital video broadcasting -satellite -second generation broadband system in order to maximise spectral efficiency. This task is usually challenging because of channel variability. The solution adopted in modern satellite communications systems relies mainly on a time-sharing strategy. Recently, we demonstrated the advantage of combining time sharing with hierarchical modulation to increase the transmission rate of such systems. However, the optimal spectral efficiency remained an open question. In this paper, we show that the optimal transmission rate is the solution of a linear programming problem. We study the performance of the optimal scheme for interactive satellite services in the context of a digital video broadcasting -satellite -second generation system. et al. optimised APSK modulations with respect to several criteria (minimum Euclidean distance and mutual information) for nonlinear channel [9]. This work serves as a guideline to the DVB-S2 standard. However, they did not address the design of hierarchical modulation. As already mentioned, hierarchical modulations merge several streams in a same symbol. The principle is to share the available energy between each stream. In this paper, we consider two layers hierarchical modulations where two streams are merged in each constellation symbol as depicted in Figure 1. The extension to n-layers hierarchical modulation will be discussed in Section 5.As each stream usually does not use the same amount of energy, hierarchical modulations often rely on non-uniform constellations, where the symbols are not uniformly distributed in the space. The use Digital video broadcasting -satellite -second generation.

Adaptive hierarchical coding and modulation scheme over satellite channels

“…Consequently, Hossain et al [2] proposed an adaptive hierarchical scheme from BPSK to 64‐QAM, which supplies one voice sub‐channel and two data sub‐channels. Hereafter, some researchers [3–5] focus on coded signals, which are closer to systems in practice. A HM scheme [3] with time sharing was proposed to obtain at most gain, where APSK constellations with different LDPC code rates in DVB‐S2 are introduced.…”

“…A HM scheme [3] with time sharing was proposed to obtain at most gain, where APSK constellations with different LDPC code rates in DVB‐S2 are introduced. And further user grouping strategy [5] was studied by means of convex optimisation when there are a number of receivers. Two‐best user opportunistic scheduling [6] was proposed to solve the problem of multi‐user diversity in HM systems.…”