5G Ultra-Dense Cellular Networks

Traditional ultra-dense wireless networks are recommended as a complement for cellular networks and are deployed in partial areas, such as hotspot and indoor scenarios. Based on the massive multiple-input multi-output antennas and the millimeter wave communication technologies, the 5G ultra-dense cellular network is proposed to deploy in overall cellular scenarios. Moreover, a distribution network architecture is presented for 5G ultra-dense cellular networks. Furthermore, the backhaul network capacity and the backhaul energy efficiency of ultra-dense cellular networks are investigated to answer an important question, that is, how much densification can be deployed for 5G ultra-dense cellular networks. Simulation results reveal that there exist densification limits for 5G ultra-dense cellular networks with backhaul network capacity and backhaul energy efficiency constraints.

Introduction

To meet 1000× wireless traffic volume increment in the next decade, the fifth generation (5G) cellular network is becoming a hot research topic in telecommunication companies and academia. First, massive multiple-input multiple-output (MIMO) technology was proposed to improve the spectrum efficiency of 5G mobile communication systems [1]. Second, millimeter-wave communications was presented to extend the transmission bandwidth for 5G mobile communication systems [2]. Furthermore, the small cell concept has appeared to raise throughput and save energy consumption in cellular scenarios [3]. To satisfy seamless coverage, a larger number of small cells have to be densely deployed for 5G cellular networks. As a consequence, the ultra-dense cellular network is emerging as one of the core characteristics of 5G cellular networks. However, the study of ultra-dense cellular networks is still in an initial stage. Some basic studies, such as the network architecture and cellular densification limits, need to be further investigated for future 5G cellular networks.