Enhancing QoS in 5th generation Het-Net via synergistic TVWS spectrum sharing for distributed adaptive small cells

Abstract

5G mobile network is expected to support an exploding traffic demand by densifying the network with heterogeneous deployment of multiple cells. Such dense network in LTE band results in spectrum scarcity and leads to high system interference. This brought in the necessity to incorporate Dynamic Spectrum Access (DSA) to additional bands for communication. The possibilities of utilizing TV White Spaces (TVWS) in cellular communication is recently considered by many researchers. However, considering the spatio-temporal variability and quality of available channels among these white spaces, there exists certain design challenges. In this paper, we present a solution to the spectrum shortage for 5G, by making the small cells in Heterogeneous Network (Het-Net) operate in TVWS. A channel detection model is developed, for identifying the available TVWS, by considering both channel sensing and geo-location database access. This improves the system accuracy. Further, a synergistic algorithm is developed, that assigns sub channels to mobile users by determining an optimum transmission power level for every mobile user on its allocated sub channel, such that it satisfies the required interference and minimum data rate constraints. The problem of jointly selecting the optimal sub channel as well as the transmission power level is formulated as a Mixed Integer Non-Linear Programming problem. The formulated problem is proved to be NP Hard, which motivated the utilization of a numerical heuristic approach to solve the problem. A Geometric WaterFilling algorithm with Sub Channel Peak Power and Multi-user Interference Constraint (GWSPI) is developed, that solves the problem in reduced time, while achieving optimal results. A detailed complexity analysis and extensive simulation analysis of the proposed method is executed to prove its efficiency compared to some standard approaches. The proposed approach shows improvement in terms of interference management and transmission power control, giving a near optimal result in real life scenario.