Extensive analysis and evaluation of the DVB S2X superframe for multi-state land mobile satellite channel

Abstract

The key enabling technology for satellite communication is the digital video broadcasting via satellite (DVB-S) standards. It featured high modulation and coding (MODCOD) schemes for reliable high quality communication link. Its operation under the clear line of sight condition has been outstanding. However, in situation where the user terminal is mobile, additional propagation challenges are introduced which further exhaust system resources and increase system design complexity. The extension of its second generation is the DVB-S2X, which offers additional functionality such as very narrow filtering roll-off factor and the superframe structure, suitable for operation at even very low signal-to-noise ratio (SNR). In this paper, a novel multi-state land mobile satellite (LMS) channel was modelled, leading to three different channel conditions – lightly-shadowed, shadowed and heavily-shadowed. Using these channels, the new system's performance is extensively analysed to determine the gains it offer to mobile channels. As a novel approach, the number of bundled Physical Layer (PL) frames contained in the superframe was made variable, and the results show that increasing the number of PL frames per superframe further improves system performance depending on the channel condition and MODCOD. For instance, for a lightly shadowed channel, superframe implementation for the 64-APSK (7/9) presents a 1 dB gain for 9 bundled PL frames and increasing the number of bundled PL frames to 12 offered an additional 0.7 dB gain. Thus, adaptive MODCOD may be combined with a variable-frame superframe implementation to improve the performance of a mobile satellite communication system and achieve a more efficient trade-off between power and spectral efficiencies than is possible with adaptive MODCOD alone.