  In this paper, we introduce and study the potentials and challenges of
integrated access and backhaul (IAB) as one of the promising techniques for
evolving 5G networks. We study IAB networks from different perspectives. We
summarize the recent Rel-16 as well as the upcoming Rel-17 3GPP discussions on
IAB, and highlight the main IAB-specific agreements on different protocol
layers. Also, concentrating on millimeter wave-based communications, we
evaluate the performance of IAB networks in both dense and suburban areas.
Using a finite stochastic geometry model, with random distributions of IAB
nodes as well as user equipments (UEs) in a finite region, we study the service
coverage rate defined as the probability of the event that the UEs' minimum
rate requirements are satisfied. We present comparisons between IAB and hybrid
IAB/fiber-backhauled networks where a part or all of the small base stations
are fiber-connected. Finally, we study the robustness of IAB networks to
weather and various deployment conditions and verify their effects, such as
blockage, tree foliage, rain as well as antenna height/gain on the coverage
rate of IAB setups, as the key differences between the fiber-connected and IAB
networks. As we show, IAB is an attractive approach to enable the network
densification required by 5G and beyond.
