  5G is finally here. Initial deployments are already operational in several
major cities and first 5G-capable devices are being released. Though it is not
limited only to millimeter wave deployments, the main promise of 5G lies in the
utilization of the high bandwidth available at high frequencies. However,
high-frequency deployments are coverage-limited and require denser placement of
base stations, which can increase the cost significantly. One of the main
contributing factors to the cost is fiber deployment. Integrated access
backhauling (IAB), where part of the wireless spectrum is used for the backhaul
connection of base stations instead of fiber, is an attractive solution that
could make dense deployments economically viable. With this main objective,
3GPP is in the process of standardizing multi-hop IAB networks. This paper
provides an overview of the main features of the multi-hop IAB 3GPP rel-16
standard and the rationale behind the design choices.
