Enhancing reliable multicast transport to mitigate the impact of blockage

Mobile wireless communication is susceptible to signal blockage, which is loss of signal, typically due to physical obstruction, over a longer duration relative to fading. Measurements indicate that blockage has a significant impact on reliability in both open and rural areas. Reliable multicast, a transport layer mechanism, attempts to gain network performance by eliminating duplicate packets transmitted from a sender to multiple receivers along common paths while providing guaranteed packet delivery to all receivers. The gain achieved by multicasting places limits on the ability to optimize transmission to heterogeneous receiver channel characteristics in an individualized manner at the multicast transport layer. A simple, low overhead protocol extension to mitigate the impact of blockage upon reliable multicast is proposed by piggybacking on reliable multicast congestion control feedback.