Energy-Efficient Bias-Based User Association for Heterogeneous Networks in LTE-Advanced

Abstract

Heterogeneous network (HetNet) deployment is a promising technique for improving energy efficiency in 4G and beyond wireless cellular systems. The major challenge of enhancing energy efficiency in HetNet is a poor cell selection when the conventional reference signal received power (RSRP) or biased RSRP (BRSRP) cell selection algorithm is employed. These cell selection techniques limit the potential of HetNet in improving transmission energy efficiency. The proposed energy-efficient bias setting strategy is an adaptive BRSRP cell selection algorithm. It uses energy efficiency as cell load metric for adaptive picocell range extension (CRE). The algorithm efficiently estimates the varying energy efficiency in each cell, then, based on the optimality gap of the energy efficiency, it adopts an optimized bias value per cell. Simulations using LTE system level simulator shows the proposed adaptive bias setting improves energy efficiency, average UE throughput and system capacity by 6.7, 9.7 and 6.9%, respectively when compared with BRSRP with a fixed bias of 6 dB. Although the proposed adaptive bias exhibits low offloading gain from PeNB to MeNB as against BRSRP, the system load balance has improved when compared with RSRP.