A Global Overview of Spectrum Sharing Initiatives.
The successful commercialization of the CBRS band in the United States has reverberated through the wireless industry. For the first time, the market is transitioning away from being carrier-led and is, instead, morphing into a diverse ecosystem of users and applications, with newcomers appearing in the form of enterprises, neutral hosts and utilities.
All of this is being underpinned by the democratization of spectrum access through new sharing frameworks, which are based on use-it-or-lose-it thinking. At their most basic level, it means that registered users can tap lightly licensed spectrum – a type that guarantees both equal access and reliability in the transmission of high-priority and high-value traffic – on an opportunistic basis.
The benefits of such a sharing framework are multifaceted. Not only does it topple financial barriers to entry by radically reducing spectrum acquisition costs, but it also fulfils the common objective of regulators to maximize efficiency in the use of spectrum by making rights available to as many users as possible.
The Lowdown on Spectrum Sharing: Focusing on Licensed Shared Access (LSA).
Simply put, spectrum sharing is the collective use of a portion of spectrum by two or more parties. The “sharing” element can be characterised as either Licensed Shared Access (LSA) or License-Exempt Access from a regulatory perspective.
(Note that this is not to be confused with dynamic spectrum sharing, a technology that enables wireless carriers to dynamically share capacity between 4G LTE and 5G NR in the same frequency band).
Of the two types of sharing, Licence-Exempt Access is the one with the least regulatory intervention. It enables any party to leverage the common spectrum resource without a need for a license. This approach does not revolve around a hierarchy of use and spectrum availability is only provided on a best effort basis. There may be a limited number of regulatory-defined constraints such as radiated power.
Licensed Shared Access (LSA), conversely, is based on a regulator-defined sharing hierarchy. The spectrum that is to be shared is already occupied by incumbent users, and a limited number of licenses are issued to enable additional users to exploit the spectrum in accordance with the sharing rules.
This article is focused on licensed sharing. In ensuring that all licensees can provide a certain level of QoS, it is recognised as the more robust carrier-grade option for users with high-priority traffic. Nonetheless, the license-exempt model is of equal importance and suited to other applications such as data-offloading.
The nature of sharing in the CBRS band aligns with LSA, comprising three hierarchical tiers of priority and regulated in real-time by the Spectrum Access System (SAS). Prior to the implementation of sharing, the band was licensed to and underutilised by specific users (including the United States Armed Forces) and for specific uses (including fixed satellite services and ship-based radar).
The United Kingdom: A Front Runner buoyed by Innovative Policymaking.
For years, the United Kingdom has been recognised as a connectivity front runner thanks to the Office of Communications’ (Ofcom) innovative policymaking and supportive government initiatives. In particular, there has been a sharp focus on the enhancement of connectivity in rural and underserved areas, exemplified by the ongoing Shared Rural Network (SRN) programme.
In 2019, the regulator announced a landmark new framework for enabling shared use of spectrum on a localised basis. It invited businesses to apply for “Shared Spectrum Licenses” across the 1.8-2.3GHz, 3.8-4.2GHz, 3.8-4.2GHz and 24.25-26.5GHz bands (with the latter mmWave bands restricted to indoor low-power use).
The licenses are divided into two distinct types: the Shared Access License and the Local Access License. The former permits users to deploy the required number of base stations in a circular area with a 50-metre radius without further authorisation from Ofcom. Meanwhile, shared access licenses are generally only issued for deployments in rural areas on a per-site basis due to higher permissible transmit power and larger potential interference area.
Given the low spectrum acquisition and maintenance costs associated with these licenses, Ofcom positions them as suitable for businesses of every size. Through the framework, it has sought to enable use cases including private LTE networks across sectors such as aviation, utilities, manufacturing and enterprise.
Mobile signal specialist StrattoOpencell (which is part of the FreshWave Group) became one of the most high-profile companies to take advantage of the shared spectrum scheme when it announced a three-year agreement with Vodafone to leverage the operator’s 2600MHz spectrum.
Stratto set out to use the spectrum to provide a 120Mbps wireless broadband service to consumers and businesses without access to a fixed service, initially supporting users at a holiday site in Devon through the deployment of an outdoor network of 4G LTE small cells.
European Union: Burgeoning Sharing Opportunities.
Spurred by CBRS, since 2012, the European Union has urged its Member States to “foster the collective and shared use of spectrum where appropriate” through its Radio Spectrum Policy Programme (RSPP).
This ambition is underpinned at an EU level by the belief among policymakers that spectrum sharing can act as a springboard for economic growth and enhanced international competitiveness.
In 2019, German regulator, BNetzA, made this a reality when it reserved 10MHz of spectrum in the 3.7-3.8GHz bands for use by private companies. Unsurprisingly, the regulator has been greeted with “great interest” for this spectrum, and almost one hundred applications were reported up to last November. High-profile applicants have included Bosch, BMW, BASF, Lufthansa, Siemens and Volkswagen.
A number of research and educational facilities are also taking advantage of the spectrum to deploy private LTE and 5G campus networks.
In France, meanwhile, a portion of the 2.6GHz band (2570-2620 MHz) has been offered to urban-based businesses by regulator ARCEP. Other beneficiaries include the operator of Paris’ airports, ADP Group and Hub One, as well as major utilities company EDF and mobility company TransDev, each of which now has access to private 4G and 5G licenses for periods spanning between five and ten years.
The Dutch have also eyed spectrum sharing for some time now, with a portion of the 3.4GHz and 3.7-3.8GHz available for local use. A license was granted to The Port of Rotterdam last year, which has developed a private LTE network to connect everything from containers to transport vehicles and workers.
Further afield, spectrum sharing initiatives can be found in Hong Kong (26 and 28GHz bands), Australia and Japan.
Conclusion: Shared Spectrum is a Springboard for Economic Recovery amid the COVID-19 Pandemic:
The early success of CBRS has blazed a trail in innovative spectrum policy, providing a replicable blueprint for countries and regulators to follow around the globe. With the implementation of sharing frameworks, the finite resource can be exploited in a more efficient manner, thereby maximising economic value through the realisation of new use cases from private enterprise networks to neutral hosts and beyond.