NeutRAN: An Open RAN Neutral Host Architecture for Zero-Touch RAN and Spectrum Sharing

Obtaining access to exclusive spectrum, cell sites, Radio Access Network (RAN) equipment, and edge infrastructure imposes major capital expenses to mobile network operators. A neutral host infrastructure, by which a third-party company provides RAN services to mobile operators through network virtualization and slicing techniques, is seen as a promising solution to decrease these costs. Currently, however, neutral host providers lack automated and virtualized pipelines for onboarding new tenants and to provide elastic and on-demand allocation of resources matching operators' requirements. To address this gap, this paper presents NeutRAN, a zero-touch framework based on the O-RAN architecture to support applications on neutral hosts and automatic operator onboarding. NeutRAN builds upon two key components: (i) an optimization engine to guarantee coverage and to meet quality of service requirements while accounting for the limited amount of shared spectrum and RAN nodes, and (ii) a fully virtualized and automated infrastructure that converts the output of the optimization engine into deployable micro-services to be executed at RAN nodes and cell sites. NeutRAN was prototyped on an OpenShift cluster and on a programmable testbed with 4 base stations and 10 users from 3 different tenants. We evaluate its benefits, comparing it to a traditional license-based RAN where each tenant has dedicated physical and spectrum resources. We show that NeutRAN can deploy a fully operational neutral host-based cellular network in around 10 seconds. Experimental results show that it increases the cumulative network throughput by 2.18x and the per-user average throughput by 1.73x in networks with shared spectrum blocks of 30 MHz. NeutRAN provides a 1.77x cumulative throughput gain even when it can only operate on a shared spectrum block of 10 MHz (one third of the spectrum used in license-based RANs).