Energy-Efficient Joint Resource Allocation and User Association for Heterogeneous Wireless Networks with Multi-Homed User Equipments

This paper investigates the resource allocation and user association for time-varying heterogeneous wireless network (HetNet), where the multi-homed user equipment (UE) utilizes multiple access options (AOs) simultaneously. Firstly, a stochastic optimization model is proposed to maximize the long-term energy efficiency (EE), which is defined as the ratio of long-term total throughput to the long-term corresponding energy consumption. A modified fractional programming method is proposed to convert the long-term EE maximize problem into an instance throughput-minus-energy optimization problem, which is proved as a mixed integer nonlinear optimization (MINO). The continuity relaxation and Lagrange dual method are proposed to solve the MINO problem. Then, a utility-based selection algorithm is developed to determine the optimal associated AO sets for each UE. After that, the dynamic EE-based resource allocation algorithm is developed to allocate the AOs radio resource energy efficiently, which depends only on the current network state information. Our simulation results show that the proposed algorithm achieves EE performance improvement compared to other general algorithms.