A Physical-social-based Group Utility Maximization framework for Cooperative Caching in Mobile Networks

Cooperative caching in the device-to-device (D2D) networks is an effective solution to the problem of offloading data traffic at peak times. However, one of the main challenges of cooperative caching is the selfish nature of the user, and some users only cache what they are interested in and don't care about other people's needs. In this paper, we investigate a physical-social-based cooperative caching framework, considering the physical-social tie as a non-monetary incentive to motivate the data cache and share between users by using D2D communication. Specifically, we first define a novel physical-social tie, combining the physical factors and social relationship. After that, we formulate two mathematical programming models with or without the consideration of indirect physical-social tie, to find an optimal caching strategy with the target of maximizing the social group utility. Moreover, we adopt Six Degrees of Separation to analyze the indirect physical-social tie between users when these social users with direct physical-social tie cannot meet the date request of the user, and then devise an indirect social group formation algorithm (ISGFA) to obtain the indirect social group of the user. Finally, simulation results shows that the caching scheme obtained from our model is efficient and outperforms other caching schemes that without considering the physical-social tie.