Flow-Level Performance of Device-to-Device Overlaid OFDM Cellular Networks

In this paper, we study the flow-level performance of an Orthogonal Frequency Division Multiple (OFDM)-based cellular network with underlay D2D, where the uplink cellular spectrum is shared by the cellular and D2D users. In specific, we formulate a coupled processor queuing system with two types of queues to model the flow-level system behavior, where the service rates are derived based on the stochastic point processes of user positions. Since the state space of the queuing model grows exponentially with the number of D2D users and cells, we use the model decomposition and iteration technique to derive its approximate steady-state solution and obtain the flow-level performance in terms of mean delay and energy consumption. Simulations are performed to verify the analytical results under different traffic loads. The proposed flow-level performance model has practical implications for the network deployment and parameter tuning with regard to D2D communications.