Hierarchically Social-Aware Incentivized Caching for D2D Communications

The data caching in Device-to-Device (D2D) networks enables the quick data access in mobile networks. The D2D channels allows content sharing when two devices are in close proximity which can help improve resource utilization and network capacity. Due to the selfish nature of users, they wish to get as much replication as possible in the opportunistic connections, seeking to maximize their own profit. However, caching resources for other nodes may lead cost to the node who serves as cache. It lacks incentives for mobile nodes to cache for other peers in D2D network. In this paper, we use an incentive method to make mobile nodes cache for others and aim to minimize the total cost of getting object data in the network. The total cost is occurred by the cache placement of cache nodes and accessing cost of the other nodes. We consider the social ties and physical distance as the factors for the cost. We model the data cache problem as a socially-aware payment game, and we introduce a hierarchical caching scheme to incentive nodes to cache, which use the user relationship to construct the cost function. In order to model user relationship, we divide the network into three categories in perspective a node: self, friends and strangers. We obtain the Nash equilibrium of the game and propose a heuristic algorithm to solve the cache placement problem. The extensive simulation results show that our algorithm gain significant cache benefit.