Data Caching in Ad Hoc Networks Using Game-Theoretic Analysis

Extensive research has been performed to study selfish data caching in ad hoc networks using game-theoretic analysis. However, due to the caching problem's theoretical root in classic facility location problem and k-median problem, most of the research assumes i), the data items are initially outside of the network, and ii), the caching cost is either a constant or not considered. In this paper, we study a general data caching model in which the data item is initially in the network, and both caching and access cost are distance-dependent in multi-hop ad hoc networks. We first show the studied problem is NP-hard. We construct a pure Nash Equilibrium, in which a node will not deviate its caching strategy if others remain theirs. However, a NE may not guarantee social optimal cost -- due to the selfishness of each node, the price of anarchy, which is the relative cost of the lack of cooperation among nodes, could be as large as $O(N)$, where $N$ is number of nodes in the network. Using an external incentive mechanism based upon a payment model, we construct a Nash Equilibrium wherein social optimal is also achieved.