On the Evaluation of Header Compression for VoIP Traffic over DVB-RCS

The transition towards the ´All IP´ environment was long ago foreseen, but the actual shift towards this goal did not happen until recently. This inevitable convergence is naturally coupled with a number of significant advantages, but also introduces some problems that were not present before. One of these, which is the focus of this paper, is the efficient transport of voice traffic over IP (VoIP). Since voice streams consist of numerous but small packets, the overhead that is caused by the RTP/UDP/IP headers is comparable - if not higher than the capacity required for the actual payload. This handicap becomes even more severe in the case of radio communications, where the scarcity of bandwidth demands an as efficient as possible utilization. The above facts make the introduction of header compression algorithms necessary, in order to mitigate the problem of overwhelming overhead. This paper describes the design and implementation of a software platform that aims to evaluate the performance of a well known header compression scheme within the context of DVB-RCS. More specifically, the focus of this work is to assess quantitatively the gains in capacity and the degradation of quality of service, when the Compressed RTP header compression scheme is employed in this satellite environment. The presented testbed models the impairments of the satellite channel and applies the header compression mechanism on real VoIP traffic.