A reward-based incentive mechanism for file caching in delay tolerant networks

This paper introduces a new incentive mechanism for content caching in Delay Tolerant Network (DTN) aiming to improve the performance under relays energy cost. We model this distributed network problem as non-cooperative game, we focus on the source-relay interaction to investigate how far data transmission could be sustained. For instance, due to a limited capacity storage and battery lifetime the relay could abstain from cooperation. Thus implementing such a mechanism is crucial, the source offers the relay some positive reward in order for this latter to accept caching and forwarding the content to the final destination. However, the relay may either accept or reject this offer, depending on the reward value and the expected energy consumption due to this operation. Next, we exhibit some sufficient conditions ensuring existence of Nash equilibria for this game. Further, we discuss their efficiency using the concept of price of anarchy. Moreover, we propose two fully distributed algorithms to reach the equilibria (both for pure and mixed equilibria). We validate our proposal using extensive numerical examples and numerous simulation runs, and draw some conclusions and insightful remarks.