Resource sharing optimization for device-to-device wireless system with femtocells

To offload the traffic from macrocell systems and improve the spectrum efficiency, device-to-device(D2D) communications and femtocell systems are introduced in the 4G LTE-A as an underlay to the cellular systems by reusing the cellular resources. This paper aims to optimize the transmit power and resource allocation for D2D transmitter, femtocell users and cellular users to better utilize uplink resources in a cellular system. We first consider a scenario where there is only one D2D pair which can reuse frequency resources of multiple cellular users and derive an optimal power assignment strategy to achieve the highest throughput of D2D pair. Furthermore we propose a joint power and resource allocation strategy in a multi-femtocell system to maximize the throughput of D2D pairs with the smallest possible total power consumption. Through simulations, we show that the proposed intelligent allocation strategy can both increase D2D throughput by exploring spatial reuse gain and reduce total power consumption.