Abstract
Non-orthogonal multiple access (NOMA) and orthogonal frequency division multiple access (OFDMA) are two typical access techniques which can be applied for cellular systems. A hybrid scheme leveraging the advantages of NOMA and OMA schemes has been recently proved to be a promising approach to reduce the interference among users and enhance the performance of cellular device to device (D2D) networks. In this paper, we study the problem of resource allocation and mode selection for content fetching in a cellular D2D network. In order to improve the energy efficiency of the network, we formulate the joint problem as a system energy efficiency maximization problem. As this problem is a non-linear fractional problem that cannot be solved conveniently, we transform it into power allocation subproblem and content fetching mode selection subproblem, and then using the Lagrange dual method and a heuristic algorithm solve these two subproblems, respectively. The presented numerical results demonstrate the effectiveness of the proposed algorithm.