  In this paper, we study the problem of multirate packet delivery in
heterogeneous packet erasure broadcast networks. The technical challenge is to
enable users receive packets at different rates, as dictated by the quality of
their individual channel. We present a new analytical framework for
characterizing the delivery rate and delivery delay performance of a previously
proposed non-block-based network coding scheme in the literature. This scheme
was studied in homogeneous network settings. We show for the first time, via
new theoretical analysis and simulations that it can actually achieve multirate
packet delivery. Using acknowledgments from each user, we show that the user
with the highest link capacity achieves the maximum possible throughput. Also,
a non-zero packet delivery rate is possible for other users, and the delivery
rate depends on the difference between the packet arrival rate at the sender
and the link capacity of each user. The accuracy of our analytical framework is
confirmed by comparing the results with simulations for different settings of
packet arrival rate at the sender and link capacities.
