Handoff Optimization for Joint Base Station Association and Power Control with Proportional Fairness in NOMA Small-Cell Networks

The handoff rate and load balancing are two important issues that have a great impact on the spectrum and energy efficiency in the small cell networks. This paper investigates the handoff optimization in small cell networks with power-domain non-orthogonal multiple access that uses successive interference cancellation, considering the fairness among base stations. We study the joint base station association and power control problem by considering the motion of mobile users and load balancing in the small cell networks. Under the maximum allowable transmit power and minimum average-rate constraints, two optimization problems are formulated using the number of associated mobile users, the number of handoffs, and the transmit power of all MUs. The total power consumption minimization and the system-wide and handoff utility maximization problems are combined into a single-stage optimization problem through the weighted sum method. We solve the formulated problem using a game theory-based algorithm and primal decomposition theory. The simulation results show that our proposed algorithm can significantly reduce the frequent handoffs and bring a fair power-controlled BS association in small cell networks.