Network Connectivity Optimization for Device-to-Device Wireless System With Femtocells

The demand for high-data-rate transmission has triggered the design and development of advanced cellular networks, such as fourth-generation (4G) Long-Term Evolution (LTE) networks. However, their poor coverage and relatively high interference can significantly impair data transmission. Femtocells and device-to-device (D2D) communication are promising solutions that have recently gathered interest. Operating in the licensed spectrum, femtocells provide users with higher capacity and coverage than their earlier designs, and they will be offered by cellular operators to enable high-data-rate local services in future LTE-Advanced networks. As an underlay to the cellular networks, D2D communication enables nearby devices to communicate directly with each other by reusing cellular resources, which reduces interference in the cellular network compared with communication through base stations (BSs). However, the tight integration of femtocells and D2D communication creates a challenge for existing network design and has been studied less in the literature. In this paper, we propose an open-access algorithm for femtocell BSs (FBSs) in D2D LTE-Advanced networks, to optimize network connectivity. Additionally, a greedy algorithm is proposed to balance macrocell BSs and FBSs to maximize network connectivity. The simulation results demonstrate the effectiveness of the proposed algorithms.