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).Comment: 13 pages, 11 figures, 1 table. IEEE Transactions on Mobile Computing,
August 202