A comparison of two methods for fountain-coded file distribution in an ad hoc network with relays

We investigate two approaches to fountain-coded broadcast file distribution in an ad hoc packet radio network. In the first method, all destinations receive fountain-coded packets directly from the source. In the second method, after one destination obtains the file, it acts as a relay node by applying continued fountain coding to the file and sending the encoded packets to other destinations. The other destinations combine the fountain-coded packets they received from the source with those they obtain from the relay node. We compare the performance of the two methods when they are employed in a network whose links have Rayleigh fading. As performance benchmarks, we also examine two conventional broadcast techniques that use automatic repeat request (ARQ) for retransmission of erased packets.