Mode selection for energy-efficient D2D communications in LTE-advanced networks: A coalitional game approach

We consider the problem of mode selection for device-to-device (D2D) communications in LTE-advanced networks. We propose a solution based on a coalitional game among D2D links to select their communications modes. The solution is given by three coalitions which represent the groups of D2D links using cellular mode, reuse mode, and dedicated mode of transmission. The D2D links in the same coalition cooperatively select the subchannels and use the corresponding transmission mode such that the total power is minimized while their rate requirements are satisfied. The D2D links can make a decision to leave and join a coalition based on their individual transmission costs. The individual transmission cost of each D2D link is a function of the transmission power and the price of channel occupancy which depends on the D2D link's communications mode. We find stable coalitions as the solution of the mode selection problem. The stable coalitions represent the system states in which no D2D link can change its communication mode and have lower transmission cost without making others worse off. A discrete-time Markov chain-based analysis and a distributed algorithm are presented to obtain the stable coalitions.