In this work we consider coding over packets that randomly arrive to a source node for transmission to a single destination. We present a queueing model for a random linear coding scheme that adapts to the amount of traffic at the source node. If there is only one packet in the queue when the channel becomes free, then reliable transmission is carried out by retransmitting lost packets. If there are at least two packets in the queue, then random linear coding is carried out over the number of packets available in the queue when the channel becomes free. We provide a bulk-service queuing model and results on the delay of this random linear coding scheme, and show that its delay performance asymptotically approaches that of a retransmission scheme.

In this work we find the capacity of a compound finite-state channel with time-invariant deterministic feedback. The model we consider involves the use of fixed length block codes. Our achievability result includes a proof of the existence of a universal decoder for the family of finite-state channels with feedback. As a consequence of our capacity result, we show that feedback does not increase the capacity of the compound Gilbert-Elliot channel. Additionally, we show that for a stationary and uniformly ergodic Markovian channel, if the compound channel capacity is zero without feedback then it is zero with feedback. Finally, we use our result on the finite-state channel to show that the feedback capacity of the memoryless compound channel is given by inf θ max QX I(X; Y |θ).

We present a systematic network coding strategy for cooperative communication, in which some nodes may replicateand-forward packets in addition to sending random linear combinations of the packets. We argue that if this strategy is used only at certain nodes in the network, the throughput will not be reduced relative to random linear network coding. Furthermore, if packets can traverse the entire network in their systematic (uncoded) form, per-packet delay can be reduced, decoding complexity can be reduced, and the potential to recover packets from incomplete coded blocks will be improved. We describe this approach and provide an analysis of the packet loss rate for fixed-rate coding on a multihop path.