Performance of Adaptive Control CRE against Cluster Size for UE Layout in Multiband HetNets

Heterogeneous networks (HetNets) combined with macrocells and picocells in the same coverage are expected to increase system capacity and/or effectively utilize a wide frequency band in fifth-generation (5G) mobile systems and beyond. In HetNets, cell range expansion (CRE) using a positive cell selection offset (CSO) is an important technique that can allow more user equipment (UE) to access picocells. A higher-order modulation scheme such as 1024-quadrature amplitude modulation (QAM) is expected to increase data rates in 5G. This paper describes a personal picocell scheme using adaptive control CRE through the use of two different CSOs to improve user throughput in a multiband HetNet. In particular, we investigate the user throughput of the adaptive control CRE against the cluster size for UE layout defined as the radius of circle centered at each pico-evolved Node B (picoeNB), using a new modulation and coding scheme (MCS) incorporating 1024-QAM. From these results, we confirm that the proposed adaptive control CRE can improve the 5percentile user throughput by 4% compared with conventional CRE while maintaining the average user throughput for a cluster size of 40 m. We also show that a cluster size of 20 m can improve the average and 5-percentile user throughputs by 29% and 13% respectively compared with a cluster size of 40 m. This work will provide a remarkably effective solution for designing multiband HetNets with the use of an MCS incorporating 1024-QAM in 5G and beyond.