On the credit evolution of credit-based incentive protocols in wireless mesh networks

In designing wireless mesh networks (WMNs), incentive mechanisms are often needed so to encourage nodes to relay or forward packets for other nodes. However, there is a lack of fundamental understanding on the interactions between the incentive mechanisms and the underlying protocols (e.g., shortest-path routing, ETX routing or back-pressure scheduling), and whether integration of these protocols will lead to a robust network, i.e., networks can sustain a given traffic workload. The objective of this paper is to present a general mathematical framework via stochastic difference equations to model the interaction of incentive mechanisms and various underlying protocols. We first present a credit evolution model to quantify the expected credit variation of each node in WMN, then use the norm of the expected credits variation to quantify the credit disparity. We also propose the use of differentiated pricing and show how it can achieve credit equality among nodes, resulting in a more robust network under different traffic loading. Our analytical framework can help researchers to model other incentive/routing protocols so to analyze the robustness of the underlying networks.