Throughput of Rateless Codes Over Broadcast Erasure Channels

In this paper, we characterize the throughput of a broadcast network with n receivers using rateless codes with block size K. We assume that the underlying channel is a Markov modulated erasure channel that is i.i.d. across users, but can be correlated in time. We characterize the system throughput asymptotically in n. Specifically, we explicitly show how the throughput behaves for different values of the coding block size K as a function of n, as n -> infinity. For finite values of K and n, under the more restrictive assumption of Gilbert-Elliott erasure channels, we are able to provide a lower bound on the maximum achievable throughput. Using simulations, we show the tightness of the bound with respect to system parameters n and K and find that its performance is significantly better than the previously known lower bounds.