  This paper considers quantum network coding, which is a recent technique that
enables quantum information to be sent on complex networks at higher rates than
by using straightforward routing strategies. Kobayashi et al. have recently
showed the potential of this technique by demonstrating how any classical
network coding protocol gives rise to a quantum network coding protocol. They
nevertheless primarily focused on an abstract model, in which quantum resource
such as quantum registers can be freely introduced at each node. In this work,
we present a protocol for quantum network coding under weaker (and more
practical) assumptions: our new protocol works even for quantum networks where
adjacent nodes initially share one EPR-pair but cannot add any quantum
registers or send any quantum information. A typically example of networks
satisfying this assumption is {\emph{quantum repeater networks}}, which are
promising candidates for the implementation of large scale quantum networks.
Our results thus show, for the first time, that quantum network coding
techniques can increase the transmission rate in such quantum networks as well.
