Wireless backhauling of 5G small cells: challenges and solution approaches

Dense deployment of small cells over traditional macrocells is considered as a key enabling technique for the emerging 5G cellular networks. However, a fundamental challenge is to provide an economical and ubiquitous backhaul connectivity to these small cells. There is a wide range of backhaul solutions that together can address the backhaul challenges of 5G networks. In this context, this article provides an overview of the different backhaul solutions and highlights the perceived challenges in backhauling small cells. A qualitative overview of the existing research studies and their critical assumptions are then discussed. Next, for backhauling downlink traffic of a small cell user, we characterize the cellular region in which the downlink transmission capacity for a user served by a given half-duplex small cell becomes limited by the backhaul link capacity. We then illustrate solution techniques such as full-duplex backhauling to improve the performance of wireless backhauling for small cells.