Energy-Aware Cooperative Content Distribution Over Wireless Networks: Optimized and Distributed Approaches

In this paper, we address the problem of optimal energy-aware content distribution over wireless networks with mobile-to-mobile cooperation. Given a number of mobile terminals (MTs) interested in downloading a common content via a base station (BS), the MTs are grouped into cooperative groups or coalitions. Within each coalition, an optimally chosen coalition head downloads the content from the BS and either unicasts or multicasts it to the other MTs. The centralized optimization formulations are derived for both unicasting and multicasting among the MTs, along with the suitable simplifications to reduce the complexity of the optimization formulations. Then, a polynomial time heuristic algorithm is proposed to solve the optimization problems for relatively large networks where the optimal solution becomes computationally complex. Furthermore, a distributed algorithm, which is based on coalitional game theory, is developed to allow the MTs to choose, independently, which coalitions to join. Performance results for various scenarios demonstrate that the proposed algorithms lead to significant reduction in the total energy consumed by the MTs. In addition, the proposed centralized and distributed algorithms are shown to have relatively low complexity while achieving a near-optimal performance.