Packet erasure coding with random access to reduce losses of delay sensitive multislot messages

Abstract

Many commercial and military systems use some form of random access. ALOHA type protocols are particularly useful for multicast traffic and have low complexity; however, they suffer from low capacity and large loss probabilities. The inclusion of packet level erasure coding in single channel ALOHA protocols is a new area. This paper demonstrates a novel combination of a medium access layer tailored to and used with packet level erasure coding; this new protocol not only reduces message loss, but also decreases delays of multislot messages. It is shown how packet level erasure coding can be used with a tailored random access protocol to render multislot messages more robust against collisions. This resilience to collisions is shown to hold both when limited feedback and no feedback are available. Despite the increased utilization of the collision channel with the additional traffic produced by the erasure code, it is demonstrated to result in a significant decrease in the probability of loss of multislot and single slot messages. The tradeoffs between message loss probability and delays are shown for a range of medium access transmission designs used in conjunction with the erasure coding.