A Novel Game Theoretic Method for Efficient Downlink Resource Allocation in Dual Band 5G Heterogeneous Network

Hybrid heterogeneous wireless networks utilizing both traditional microwave frequency band and millimetre wave band are currently been investigated as a potential approach to meet the increasing demand for ultra-high rate transmission with the severe microwave spectrum scarcity and requirement for low power network devices. In this paper, we investigate downlink resource allocation in two-tier heterogeneous networks comprising of a macrocell transmitting at a microwave frequency and dual-band small cells utilizing both microwave and millimetre wave frequencies. We present a novel architecture with dual band small cell base stations. The small cell coverage area is divided into two regions where the users in the inner and outer regions are served by the associated small cells on millimetre wave and microwave frequencies, respectively. We formulate a two layer game theory based approach for maximizing energy efficiency and spectral efficiency of the system with optimal usage of available radio resources. The proposed game theoretic approach comprises of a non-cooperative frequency assignment game as its first layer and a multi-objective optimization based game as the second layer. In the frequency assignment game, each small cell base station selects a frequency band from either the microwave band or millimetre wave band for each of its associated users by maximizing the data rate of its users. The solution to the frequency assignment game is obtained via Pure Strategy Nash Equilibrium. The utility function of the game in the second layer involves power and sub-carrier allocation via the joint maximization of both energy efficiency and spectral efficiency of the network. The utility function is formulated as a multi-objective optimization problem which is converted into a single objective problem and solved using Lagrangian dual relaxation. Simulations results show that the proposed dual band heterogeneous network with game theoretic resource allocation offers improved sum rate, energy efficiency and spectral efficiency compared to classical shared spectrum heterogeneous network utilizing only microwave frequency band.