Performance of Voice over IP in DVB-RCS and iDirect satellite networks
Résumé
Thanks to their global coverage, satellite networks aim to reach any remote area with an increasing portion of their capabilities used to carry data packets. They, already, constitute a plain component of the global communication and information structure providing broadband interactive and broadcasting services. The ability of carrying voice over IP is becoming a vital objective for telecommunication systems of different physical structures. This is mainly motivated by the cost effective alternative supplied by VoIP compared to traditional telephony as well as the convergence of wired, wireless, terrestrial and satellite networks toward the "all over IP". Communication systems take advantages of the ability of IP to act as a data container regardless of the traffic nature in addition to permitting end to end connectivity over heterogeneous underlying networks In a spite of clear advantages, VoIP over satellite systems raises particular challenges specific to the satellite environment, such as delay and overhead. In this article, we explore constraints and issues related to supplying VoIP over satellite systems. Furthermore. we investigate the possible solutions to optimise transmission of such an application over VSAT networks. Focus is made upon two of the most mature technologies of the market. The first is DVB-RCS [1] which annexes a return path to the successful DVB-S [2] broadcasting standard in order to allow bidirectional IP connectivity via a satellite. Late 2006, up to 150 deployed networks and over 50,000 operational terminals are relying on DVB-RCS to deliver IP broadband services [3]. The second is iDirect a proprietary technology designed with the specific concern of providing IP based applications. This technology is emerging as a new reference for the VSAT networks with up to 400 hubs and 7500 terminals drawing up operational networks over the world. Both technologies are already sensitively deployed in the market. Consequently, we do not intend to prove which technology is the best. The main purpose of the study is to explore the way these technologies cope with the issues inherent from transmitting different IP applications, mainly VoIP, over satellite networks in an operational context. It is shown that both technologies provide consistent solutions to support constraining IP services over satellite.