# Millimeter Wave Integrated Access and Backhaul in 5G: Performance Analysis and Design Insights

## TL;DR

This paper analyzes the performance of 5G millimeter wave HetNets with integrated access and backhaul, providing insights into resource allocation strategies and their impact on user rates in the presence of wireless backhaul constraints.

## Contribution

It develops an analytical framework for IAB-enabled 5G HetNets, comparing resource allocation schemes and revealing limitations of densification and user offloading.

## Key findings

- Offloading users to small cells may not improve rates in IAB networks.
- Densifying small cells does not necessarily enhance user rates due to backhaul bottlenecks.
- Resource allocation strategy significantly impacts downlink rate coverage in IAB HetNets.

## Abstract

With the emergence of integrated access and backhaul (IAB) in the fifth generation (5G) of cellular networks, backhaul is no longer just a passive capacity constraint in cellular network design. In fact, this tight integration of access and backhaul is one of the key ways in which 5G millimeter wave (mm-wave) heterogeneous cellular networks (HetNets) differ from traditional settings where the backhaul network was designed independently from the radio access network (RAN). With the goal of elucidating key design trends for this new paradigm, we develop an analytical framework for a two-tier HetNet with IAB where the macro base stations (MBSs) provide mm-wave backhaul to the small cell base stations (SBSs). For this network, we derive the downlink rate coverage probability for two types of resource allocations at the MBS: 1) integrated resource allocation (IRA): where the total bandwidth (BW) is dynamically split between access and backhaul, and 2) orthogonal resource allocation (ORA): where a static partition is defined for the access and backhaul communications. Our analysis concretely demonstrates that offloading users from the MBSs to SBSs may not provide similar rate improvements in an IAB setting as it would in a HetNet with fiber-backhauled SBS. Our analysis also shows that it is not possible to improve the user rate in an IAB setting by simply densifying the SBSs due to the bottleneck on the rate of wireless backhaul links between MBS and SBS.