  The recently proposed NR-ready integrated access and backhaul (IAB)
architecture promises to bring a cost-efficient deployment solution for both
coverage extension and capacity boosting in future 5G/5G+ systems. While its
impact on the coverage extension was thoughtfully addressed in the literature,
the effect of advanced functionalities such as multi-hop, multi-connectivity,
and multi-beam operations on the throughput remains unclear. We review and
characterize the system-level impact of these capabilities on the performance
of self-backhauled IAB systems operating in half-duplex mode and utilizing
millimeter-wave (mmWave) technology across both access and backhaul. Our
results indicate that the throughput gain of multi-hopping and multi-beaming is
significant even without multi-connectivity operation. Another important
learning is that in all-mmWave systems with link blockage, multi-connectivity
with link switching allows achieving self-load balancing. Finally, we outline
future research directions.
