A non-monetary protocol for peer-to-peer content distribution in wireless broadcast networks with network coding

This paper studies the problem of content distribution in wireless peer-to-peer networks with selfish nodes. In this problem a group of wireless nodes exchange data over a lossless broadcast channel. Each node aims to increase its own download rate and minimize its upload rate. We propose a distributed protocol that provides incentives for the nodes to participate in the content distribution. Our protocol does not require any exchange of money, reputation, etc., and hence can be easily implemented without additional infrastructure. Moreover, our protocol can be easily modified to employ network coding. Focusing on the important case in which the system contains two files that need to be distributed, we derive a closed-form expression of Nash Equilibria. We also derive the prices of anarchy, both from each node's perspective and the whole system's perspective. Furthermore, we propose a distributed mechanism where the strategy of each node is only based on the local information and show that the mechanism converges to a Nash Equilibrium. We also introduce an approach for calculating Nash Equilibria for systems that incorporate network coding when more than two files need to be distributed.