On the Cooperation for Content Caching from a Coalitional Game Perspective

Abstract

Cooperative content caching has been demonstrated to achieve significant performance gain over the conventional content caching paradigm by exploiting content diversity through the participation of multiple cooperative nodes. Although cooperative content caching has the potential to increase the efficiency, an improper coalition formation may result in severe performance degradation. Therefore, the cooperative nodes should be carefully selected according to their interests in different content objects. In this paper, we develop an analytical framework for cooperative content caching from a coalitional game perspective. The cooperation issue for content caching among nodes is studied by the coalitional game theory, and the associated problems are analyzed in different cases that the utility transfer among nodes is allowed or not. If the utility transfer is allowed, by exploiting the properties of the coalitional costs, we derive the non-empty property of the core of a transferable utility coalitional game, and prove that the grand coalition is stable in spite of the presence of coalition costs. If the utility transfer is not allowed, we adopt a non-transferable utility coalitional game model. The grand coalition is not always stable in the presence of coalition costs. A merge and split algorithm is proposed to form the coalitional structure for iteratively improving the caching performance. Finally, the simulation results demonstrate the cooperation gains on both the sum and individual utilities in different scenarios.