Reducing Retransmissions in Point-to-Point Satellite Transmissions

This paper presents a mechanism that reduces the number of retransmissions needed to ensure reliable unicast transmissions over a shared broadcast channel. This improves the bandwidth occupancy by information packets and potentially reduces the end-to-end jitter and delay. After each block transmission, the mechanism determines the minimal set of information packets to retransmit, builds a specic Reed-Solomon code from this set and then sends repair packets produced with this code instead of retransmitting the information packets. The mechanism was analysed theoretically and evaluated numerically under many di erent conditions (variable packet loss rate, number of receivers, etc.). Both the erasure channel and the error channel were explored. In most cases, the system can be set up such that it uses less retransmissions than a classical ARQ mechanism: most of the time, 40% up to 95% less. Such a mechanism is clearly useful in satellite contexts.