Integrated Access and Backhaul: A Key Enabler for 5G Millimeter Wave Deployments

Integrated access and backhaul (IAB) is an important new feature in 5G NR that enables rapid and cost-effective millimeter wave (mmWave) deployments through self-backhauling in the same spectrum. IAB deployments can achieve excellent cell edge coverage, for example edge user rates of at least 100 Mbps, while significantly reducing the number of fiber connections required per square kilometer. This paper provides an introduction and primer on IAB, and contrasts IAB with the many failed multihop relay systems that preceded it. We conduct a large scale study of coverage and rate performance based on a plausible deployment in Chicago Lincoln Park neighborhood , utilizing ray tracing in the 39 GHz band. The study demonstrates that, as theory predicts, an IAB solution provides a massive coverage advantage for early mmWave rollouts with only a small number of fiber-connected (donor) base stations, e.g. less than 10 per square km. We show that as the UE and traffic loads increase over time as the 5G ecosystem matures, the per user throughput can be maintained by replacing IAB (relay) nodes with donor nodes, i.e. slowly extending the fiber network.