Cross-Layer Rate Control of VoIP over DVB-S2/RCS

This paper presents a study of the cross-layer optimisation of real time traffic transmission over satellite systems implementing DVB-S2/RCS. In particular, we focus on voice over IP (VoIP) transmission and we aim at reducing total transmission delay and jitter. We propose an end-user-centric scenario where codec rate adaptation is performed. Two possible cross-layer codec rate adaptations have been analyzed. First, we propose a bank of codecs be available at both transmission ends and a codec switch is performed driven by the RTCP (real time control protocol) reports. In this case a transport-to-application layer cross-layer information flow is required. Second, we propose the use of adaptive wideband codecs (inherently cross-layer across the network). Realistic modelling is considered for both the system and (Ka band) channel. We present an analysis of the two proposed cross-layer mechanism showing the potentiality of both approaches even in long-delay scenarios such as a GEO satellite system.