A Constrained Coalition Formation Game for Multihop D2D Content Uploading

This paper investigates relay-based schemes in cellular systems, where multihop device-to-device (D2D) communications are exploited for content uploading toward the eNodeB. All user equipments (UEs) are sources of their own content and form a multihop D2D chain, with the head of the chain being in charge of uploading all the generated content to the eNodeB. By pooling the cellular radio resources assigned to the D2D chain and by using high-quality short-range radio links, the proposed cooperative content uploading scheme guarantees lower upload delays than in the traditional cellular mode operation. To model the D2D chain formation in a cell and to best characterize self-interested users concerned about their own payoff, a constrained coalition formation game is defined, where each UE is a player whose cost is identified as the content upload time. The solution of the game determines the stable feasible partition for the UEs in the cell. We demonstrate through simulations that with this solution the content uploading time is reduced by 52% with respect to the traditional cellular mode.