Efficient Resource Allocation Algorithms for Energy Efficiency Maximization in Ultra-Dense Network

Energy efficiency has now become a key pillar in the design of communication networks. With millions more base stations and billions of connected devices, the demand for energy-efficient system design and operation will be even more compelling in the fifth generation (5G) communication network.In this paper, we focus on maximizing the downlink system energy efficiency (EE) of the 5G ultra dense network through efficient resource allocation algorithms. First, a constrained EE maximize problem is formulated. However, the resulting optimization problem is challenging due to its non-convex nature. To overcome this issue, the transformations based on fractional programming theory are applied, so that the primal problem can be converted into a convex form. Then, we adopt a centralized algorithm to solve the optimization problem and get the global optimal EE. In order to reduce the complexity, an efficient distributed algorithm based on alternating direction method of multipliers (ADMM) is further proposed. The simulation results show that both the centralized algorithm and the distributed algorithm converge to the same EE, but the latter one has lower computational complexity.