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, uplink rates above 100 Mb/s, while significantly reducing the amount of required fiber. This article provides a primer on IAB, contrasting it with the many failed multihop systems that preceded it. We conduct a large-scale study of coverage and rate performance based on a plausible deployment in Chicago's 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, for example, less than 10/km(2). We show that as the UE and traffic loads increase over time as the 5G eco-system matures, the per user throughput can be maintained by replacing IAB (relay) nodes with donor nodes, that is, slowly extending the fiber network.