Abstract—Network coding has been proposed recently as an
efficient method to increase network throughput by allowing
network nodes to combine packets instead of simply forwarding
them. However, packet combinations in the network may increase
delay, complexity and even generate overly redundant information
when they are not designed properly. Typically, the best
performance is not achieved when all the nodes perform network
coding. In this paper, we address the problem of efficiently placing
network coding nodes in overlay networks, so that the rate of
innovating packets is kept high, and the delay for packet delivery
is kept small.We first estimate the expected number of duplicated
packets in each network node. These estimations permit to select
the nodes that should implement network coding, so that the
innovating rate increases. Two algorithms are then proposed for
the cases where a central node is aware of the full network
statistics and where each node knows the local statistics from its
neighbor, respectively. The simulation results show that in the
centralized scenario the maximum profit from network coding
comes by adding only a few network coding nodes. A similar
result is obtained with the algorithm based on local statistics,
which moreover performs very close to the centralized solution.
These results show that the proper selection of the network
coding nodes is crucial for minimizing the transmission delay
in streaming overlays.