A network coded ARQ protocol for broadcast streaming over hybrid satellite systems

Due to the high round trip delay in satellite systems, the retransmission of lost packets using conventional ARQ schemes is performed in a very rigid manner and after a very long time of the initial packet transmission. This results in a high average packet delay and packet drop rate in broadcast streaming applications. Moreover, conventional ARQ schemes are generally inefficient in broadcast scenarios. In this paper, we propose a network coded ARQ protocol that performs both proactive and reactive packet retransmissions in hybrid satellite systems. The proposed protocol employs a network coding approach to generate efficient proactive retransmission packets without the knowledge of lost packets. This not only allows the transmission of these coded retransmissions before the arrival of the initial packets to their destinations but also achieves more efficient packet recovery compared to conventional ARQ. Reactive retransmissions in response to packet acknowledgments are then employed if one or more packets are still lost. Simulation results show considerable gains for our proposed protocol over the selective repeat ARQ protocol in terms of average packet delay, packet drop rate and goodput.