Minimum-Cost Multicast over Coded Packet Networks

Streaming data to di↵erent receivers from a single source is a very common scenario. In general this would be achieved by using single source multicast, for which finding the most cost-ecient paths is very hard as it has to be computed in a centralized manner and is only a↵ordable for little networks since it is not solvable in polynomial time. Although today’s networks use e.g. heuristics to quickly find sub-optimal solutions to transmit data from one source to multiple receivers, it would be nice to find even better solutions in less time. However, changing the problem a little bit might help. Although routers are currently only able to forward and copy packets, there is no reason to limit them to only those functionalities. Having a network of routers capable of network coding ‐ meaning being able to apply an arbitrary causal function on multiple incoming packets, resulting in one outgoing packet ‐ can change this. This work gives an introduction to finding optimal cost solutions for multicast in a coded packet network, and shows that finding these solutions is possible in a decentralized manner resulting in only polynomial e↵ort to calculate.