Dual Connectivity in Heterogeneous Small Cell Networks with mmWave Backhauls

Wooseong Kim

doi:10.1155/2016/3983467

Abstract

Ultradense Network (UDN) with small cells is a key feature to begin a new era of 5G communication, which provides higher data rate, and accommodate explosive mobile traffic. Recently, mmWave-based wireless backhauls accelerate deployment of the UDN by reducing cost of fiber-optic cabling to small cells. The small cells can deliver user data to macro enhanced NodeBs (eNBs) using multihop relay in wireless backhaul mesh that consists of small and macro cell eNBs connected by the mmWave links. For such a heterogeneous small cell network (HetNet), 3GPP introduced dual connectivity (i.e., dual connections to macro and small cell eNBs), which is an attractive standard feature to manage user mobility and network access in the small cells. In this paper, we exploit dual connectivity scheme in a HetNet with the mmWave-based backhaul mesh which introduces two main challenges for throughput maximization, multihop routing from small to macro cell, and selection of a small cell eNB for user equipment (UE). We establish an optimization model and find an optimal solution in terms of throughput and fairness using an IBM CPLEX solver. Additionally, we propose a heuristic algorithm for complexity reduction and compare it with the optimal results in evaluation.

Highlights

Fast growing mobile traffic demands small cell deployment at urban hot spots, which can increase effectively network capacity by cell densification and data rate with proximity to user equipment (UE). 5G projects [1, 2] address Ultradense Network (UDN) with the small cells as a key technology to accommodate 10–100x increasing traffic
MmWave-based backhauls from an small eNBs (SeNBs) to an macro eNB (MeNB) or gateway are created by multiple LoS links between enhanced NodeBs (eNBs), by which SeNBs and MeNBs form a multihop wireless mesh network (WMN) and the eNBs deliver user equipment (UE) data by multihop routing in the mesh network
To reduce the calculation time, we propose a simple heuristic algorithm for the SeNB selection and multihop routing in dual connectivity procedure which can perform close to optimal results of the IBM CPLEX in terms of UE throughput and fairness

Summary

Introduction

Higher path loss due to oxygen absorption and rain effect than conventional cellular spectrum limits backhaul range between two eNBs. mmWave-based backhauls from an SeNB to an MeNB or gateway are created by multiple LoS links between eNBs, by which SeNBs and MeNBs form a multihop wireless mesh network (WMN) and the eNBs deliver user equipment (UE) data by multihop routing in the mesh network. UEs are controlled by the macro cell in terms of network access, handover, security, and so forth, while user data are delivered by both cells simultaneously This CA is difficult to apply in the mmWave-based backhaul mesh network because multihop delay in the backhaul causes asynchronous transmission in the macro and small cells.

Heterogeneous Networks

System Model

Performance Evaluation

Related Works

Findings

Conclusion