  We study the performance of random linear network coding for time division
duplexing channels with Poisson arrivals. We model the system as a bulk-service
queue with variable bulk size. A full characterization for random linear
network coding is provided for time division duplexing channels [1] by means of
the moment generating function. We present numerical results for the mean
number of packets in the queue and consider the effect of the range of
allowable bulk sizes. We show that there exists an optimal choice of this range
that minimizes the mean number of data packets in the queue.
