Use of shared spectrum at the national level06.10.2020
Types of spectrum sharing licensing regimes
Shared access regimes are one way for regulators to open spectrum to more users and to facilitate the use of spectrum bands, especially when an exclusive use is not possible in the short term. Spectrum sharing can either be part of a licensed or unlicensed regime. Under licensed shared access (LSA), use is authorized by a licence for a set of different types of services or between users, under conditions defined in the licence to avoid harmful interference. Under an unlicensed or licence-exempt regime, no licence is required, and the number of users is not limited by the regulator. However, users must adhere to technical restrictions (e.g., power limits, maximum levels of out-of-band transmissions, etc.).
Licensed shared access
Licensed shared access arrangements can help regulators strike a balance between making the most amount of spectrum available while safeguarding access to spectrum for incumbent services. This approach can foster spectrum efficiency by leveraging spectrum that may be underused by providing access when spectrum cannot be released in all areas or within a reasonable time. Regulators usually adopt a licensed access approach when spectrum use must be managed to mitigate harmful interference, which can be done through dynamic or static coordination approaches.
The establishment of LSA frameworks requires the definition of the prioritization of users in the proposed band and conditions that each user tier can expect for access to the spectrum. Furthermore, the terms and technical operating conditions that will manage interference between different users, and a mitigation plan in case of harmful interference should be defined.
Examples of national approaches to spectrum sharing
Several regulators have sharing regimes in place, including among others:
The shared access framework proposed in the United States for the 3.5 GHz band dynamically manages spectrum use between incumbent users, priority access licensees, and general authorized access users through a spectrum access system (SAS). Incumbent users are most protected against harmful interference, whereas general users receive no protection from other users. The SAS assigns spectrum to users dynamically, according to the users’ priority and current use in a geographic area. This manages spectrum use dynamically between incumbent federal and non-federal users of the band and citizens broadband radio service (CBRS), to accommodate various uses, including the fifth generation (5G) and the Internet of Things (IoT) applications.
The United Kingdom established a Shared Access Licence, which is available for the 1 800 MHz (1 781.7-1 785 MHz/1 876.7-1 880 MHz), 2.3 GHz (2 390-2 400 MHz), 3.8-4.2 GHz, and 24.25-26.5 GHz bands. There are two types of licences available, either low- or medium-power licences that define use according to technical operating parameters. The two types of licences can be used for all the bands, except for the 24.25-26.5 GHz band, which is only valid for indoor low-power use. The four shared access bands have various potential uses, including for private networks, mobile rural or indoor coverage, or fixed wireless access. The licences have unlimited validity, as long as the annual licence fees are paid and the terms and conditions of the licence are upheld. The regulator will assess applications for shared use of the spectrum to ensure non-interference with existing licensees and will grant licences on a first-come, first-served basis.
The United Kingdom also established a Local Access Licence, which provides access to unused mobile spectrum. The licence grants access to mobile spectrum that is unused in certain geographic areas, upon agreement with existing licensees that the new user is unlikely to cause interference or constrain plans. The licence will specify the location and terms of access to avoid interference with the incumbent operator and will have a validity of up to three years. The licence cannot be renewed; a new application would have to be filed. Given that unused spectrum is likely to be in less-populated areas, the regulator expects these local access licences to support wireless broadband services or local private networks. While spectrum trading and leasing are possible under existing mobile spectrum rules, it has been used most often to transfer rather than share spectrum rights.
Hong Kong, China designated 400 MHz of spectrum in the 26/28 GHz (27.95-28.35 GHz) bands to be available as shared spectrum for a localized wireless broadband service, in blocks of 100 MHz. The licences will permit non-exclusive use of spectrum in a defined area of no more than 50 square kilometres. Since the use is tied to a geographic area, the same frequency channel can be reused in different areas around the region. Licences will be issued initially for five years, with the possibility for renewal for an additional five years.
China assigned licences to China Telecom Group, China United Network Communications Group (China Unicom), and China Radio and Television Network (also known as China Broadcasting Network), authorizing the shared use of the 3 300-3 400 MHz band. The spectrum is awarded on a shared basis to promote the coinvestment and sharing of infrastructure. Interference is mitigated through nationwide, indoor-only use. This marks the first time the Ministry of Industry and Information Technology (MIIT) has taken such a shared approach.
It should be noted that mobile operators have pointed out that licensed shared access to spectrum should not be considered a replacement for exclusive nationwide access to mobile spectrum. While shared spectrum may be a complement, operators stress the need for exclusive spectrum to meet quality of service and coverage standards and to provide investment certainty in network deployments (GSMA 2019). Also, while the above examples show how regulators have set frameworks to encourage spectrum sharing, existing spectrum frameworks often allow users to enter into spectrum sharing agreements voluntarily when spectrum is not being used. This is the same concept as described in the LSA model but, in this case, operators can do so voluntarily under defined compensation terms.
Source: Mitchell Luo on Unsplash.
Licence-exempt bands provide access to spectrum without a heavy regulatory burden. This licensing category grants non-exclusive use of spectrum upon adherence to certain operating parameters. Since spectrum in these bands is shared, it is especially important that users maintain emissions within the permitted range and that the equipment being used adheres to type approval requirements.
Users of this type of spectrum are sometimes required to register with the regulator and pay a nominal fee, and users must adhere to specifications tied to the spectrum use. This is sometimes referred to as unlicensed spectrum and may also be called a class licence, especially if some sort of registration is required. For instance, the Netherlands permits the use of certain frequencies bands by Bluetooth, Wi-Fi, contactless payment, remote controls for car locks, and other types of equipment characterized by a low transmission power, without a licence or notification to the regulator before use. Other types do require notification in the Netherlands, such as maritime mobile communication and amateur radio equipment (Ministry of Economic Affairs and Climate 2016: 29-30). Those which do require notification usually must do so regularly (e.g. annually).
The lower regulatory burden of these bands has made them a breeding ground for innovation. Several applications operate in licence-exempt bands, including Bluetooth, Wi-Fi, radiofrequency identification (RFID), industrial, scientific, and medical (ISM) equipment, and other short-range devices. These bands are expected to continue to play an important role in the future, considering that Wi-Fi and IoT applications often operate in licence-exempt bands. Cisco projects that Wi-Fi will offload 59 per cent of mobile traffic from cellular networks by 2022 (Cisco 2019: 17). Unlicensed bands have also been noted for their potential in mobile broadband networks, including in 5G deployments. Together with licensed spectrum, licence-exempt spectrum can provide additional capacity and higher bandwidths. Mobile technologies can also operate in licence-exempt bands on a standalone basis to offer local area networks, for instance in neighbourhood networks or for private enterprise networks to support Industrial IoT (Qualcomm 2017).
Administrations have recognized the potential of unlicensed spectrum and are considering opening additional bands on a licence-exempt basis. The United States recently released the 6 GHz spectrum and several bands above 100 GHz for licence-exempt use. The United Kingdom issued a consultation in 2020 to release additional bands for unlicensed use in the 5-6 GHz and 100-200 GHz bands. Argentina had a consultation on a proposition to allow unlicensed use on a secondary basis in rural areas with less than 100 000 residents, as a possible solution to improve rural broadband connectivity (Resolution 21/2019).
Regulators are encouraged to continue to value licence-exempt spectrum and consider the possibilities of releasing additional spectrum on a licence-exempt basis in certain bands to support future applications. Regulators should conduct due diligence to ensure coexistence with other users and establish clear guidelines and operating parameters for unlicensed use to avoid harmful interference.
Market implementation of spectrum sharing
Active infrastructure RAN sharing
An increasing number of mobile network operators are teaming up with competitors to share infrastructure and investment costs. This evolved out of a need to densify networks in urban centres and also fulfil coverage obligations in less populated areas. While widely implemented for 3G and 4G networks, infrastructure sharing is especially important to reduce the costs of 5G network deployments. Cooperation is more commonly focused on passive infrastructure, like masts, towers, and sites, although some agreements include sharing active infrastructure, such as transmitters and antennas.
Radio access network (RAN) agreements define the terms that operators obtain to share networks, which include active elements of RAN in some cases, like spectrum resources. Mobile operators in Denmark, Finland, France, Poland, and Sweden have undertaken sharing agreements that include spectrum, under defined terms that specify the geographic area of sharing and/or the timeframe of the sharing agreement (BEREC 2018: 10-11). In May 2020, China Mobile Communications Group (China Mobile) and China Broadcasting Network Corporation (CBN) signed a framework agreement to share spectrum to facilitate 5G deployment and coverage.
Source: China Mobile 2020.
Such sharing arrangements allow operators to split the burden of network investment and to accelerate the time needed to deploy national networks. Many regulators are in favour of actions that encourage network deployment and investment, which aligns with the goals of the spectrum sharing models.
However, this model does have potential risks to competition, depending on many variables, including the conditions of the sharing agreements, the extent of the joint activities, and the competitiveness of the market. Regulators oversee such agreements to mitigate these risks and uphold market competition. For instance, the spectrum sharing could be allowed only for a specific period or in certain areas, or until sufficient spectrum is released. Such measures would avoid only one national network being deployed in a specific area and encourage network redundancy and protect competition. Other regulatory measures could be put in place to prevent the parties from acting like a merged entity, gaining market dominance in the market, or decreasing competition in the wholesale or retail markets. Regulators should consider allowing active infrastructure sharing to encourage a quicker deployment of networks and a shared burden of investment among operators, while also putting in place safeguards to protect competition.
New ways of using spectrum: network slicing and dynamic spectrum sharing
One of the aims of spectrum sharing is to promote more efficient spectrum use. Network slicing and dynamic spectrum sharing (DSS) are two technological innovations that are helping operators to use spectrum more efficiently in their networks. Network slicing is a form of network virtualization made possible through software-defined networks and network function virtualization. It allows several service networks, or slices, to be served with the same physical infrastructure (OECD 2019: 28-29). This enables operators to provide different types of services per network slice, tailored to the necessary service characteristics such as latency, speed, security, or reliability.
Source: Ashwood-Smith 2017.
As mobile operators transition from 4G to 5G networks, network slicing can help them to efficiently use spectrum to meet their needs as more data-heavy 5G applications begin to be supported. However, network slicing is expected to be particularly impactful once 5G networks have been fully rolled out, when different 5G usage scenarios take root, and it can be applied on a large scale.
Dynamic spectrum sharing has also been discussed as a way to use mobile spectrum more efficiently as operators transition from 4G to 5G networks. DSS allows operators to use existing 4G spectrum to provide 5G service through a software upgrade. It uses existing infrastructure, facilitating the transition from a 4G network, to a non-standalone 5G network, to finally a standalone 5G network. With DSS, an operator can dynamically assign spectrum to 4G and 5G, depending on the traffic to the cell. Since the updates can be made over software, DSS may ease the financial burden as existing hardware and sites can be reused (as long as they are 5G-compatible) and decrease the time to upgrade the network.
Ashwood-Smith, Peter. 2017. “Why End-to-End Network Slicing Will Be Important for 5G.” ITU News, July 4, 2017 https://news.itu.int/why-end-to-end-network-slicing-will-be-important-for-5g/.
BEREC (Body of European Regulators for Electronic Communications). 2018. BEREC Report on Infrastructure Sharing. BoR (18). 116. https://berec.europa.eu/eng/document_register/subject_matter/berec/download/0/8164-berec-report-on-infrastructure-sharing_0.pdf.
China Mobile. 2020. “Collaborative Framework Agreement in relation to 5G Co-Construction and Sharing Entered into Between Parent Company and China Broadcasting Network Corporation Ltd.” Press release. https://www.chinamobileltd.com/en/file/view.php?id=230559.
Cisco. 2019. Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update, 2017-2022. https://s3.amazonaws.com/media.mediapost.com/uploads/CiscoForecast.pdf.
FCC (Federal Communications Commission). 2019. FCC Opens Spectrum Horizons for New Services and Technologies”. https://www.fcc.gov/document/fcc-opens-spectrum-horizons-new-services-technologies-0.
FCC (Federal Communications Commission). 2020a. “FCC Establishes Procedures for 3.5 GHz Band Auction.” Public Notice. https://www.fcc.gov/document/fcc-establishes-procedures-35-ghz-band-auction-0.
FCC (Federal Communications Commission). 2020b. Unlicensed Use of the 6 GHz Band. https://docs.fcc.gov/public/attachments/DOC-363490A1.pdf.
GSMA. 2019. Spectrum Sharing: GSMA Public Policy Position. https://www.gsma.com/spectrum/wp-content/uploads/2019/09/Spectrum-Sharing-PPP.pdf.
MIIT (Ministry of Industry and Information Technology). 2020. “The Ministry of Industry and Information Technology Permits China Telecom, China Unicom, and China Radio and Television to Jointly Use the Indoor Frequency of the 5G System.” Press release. February 10, 2020. http://www.miit.gov.cn/n1146290/n1146402/c7671201/content.html.
Ministry of Economic Affairs and Climate. 2016. Radio Spectrum Policy Memorandum. https://www.government.nl/binaries/government/documents/reports/2017/03/07/radio-spectrum-policy-memorandum- 2016/Netherlands_Radio_Spectrum_Policy_Memorandum_2016.pdf.
OECD (Organisation of Economic Cooperation and Development). 2019. The Road to 5G Networks. OECD Digital Economy Papers, No. 284. Paris: OECD. https://doi.org/10.1787/2f880843-en.
OFCA (Office of the Communications Authority). 2019. Guidelines for Submission of Applications for Assignment of Shared Spectrum in the 26 GHz and 28 GHz Bands.” https://www.coms-auth.hk/filemanager/statement/en/upload/515/gn132019.pdf.
Ofcom (Office of Communications). 2019a. Enabling Wireless Innovation Through Local Licensing: Shared Access to Spectrum Supporting Mobile Technology. https://www.ofcom.org.uk/__data/assets/pdf_file/0033/157884/enabling-wireless-innovation-through-local-licensing.pdf.
Ofcom (Office of Communications). 2019b. Local Access Licence. https://www.ofcom.org.uk/__data/assets/pdf_file/0037/157888/local-access-licence-guidance.pdf.
Ofcom (Office of Communications). 2020a. Improving Spectrum Access for Wi-Fi: Spectrum Use in the 5 and 6 GHz Bands. https://www.ofcom.org.uk/__data/assets/pdf_file/0038/189848/consultation-spectrum-access-wifi.pdf.
Ofcom (Office of Communications). 2020b. Further Consultation: Supporting Innovation in the 100-200 GHz Range. https://www.ofcom.org.uk/consultations-and-statements/category-2/supporting-innovation-100-200-ghz.
Qualcomm. 2017. “3GPP Starts Study on 5G NR Spectrum Sharing.” Press release. April 26, 2017. https://www.qualcomm.com/news/onq/2017/04/26/3gpp-starts-study-5g-nr-spectrum-sharing.