Spectrum use is no longer confined to commercial wireless services with traditional long-term, wide-area licenses, running in separate bands to permanently dedicated services such as radar, or maritime and aviation communications. While sharing of bands has been relatively common, the majority of examples have been static and predictable.
However, a growing array of applications now involves radio spectrum allocated for short time durations and/or in localised areas. This trend is forcing regulators and spectrum managers to rethink coordination, enforcement, and sensing strategies to ensure efficient use of frequency resources and avoid interference.
Unlike the stable decades-long nationwide mobile licenses of the past or manual person-to-person agreements for audiovisual systems at events, these emerging use cases present unique challenges and opportunities. There is a growing range of dynamic spectrum sharing options and real-time management of multiple frequency bands.
As the number of spectrum decisions and transactions rises, there is a clear need to consider new and scalable administration mechanisms. In particular, automation, better sensing and monitoring, and eventually AI-based capabilities will prove essential.
Temporary spectrum allocations
Innovative use cases across multiple industries are driving demand for spectrum that is temporary (often with allocations lasting for hours, days, or weeks) and geographically constrained (covering perhaps a building, campus, or event venue).
Key examples include:
- Private 4G/5G Pop-Up Networks: Companies, local authorities, and event organisers can deploy private LTE/5G on-site for concerts, sports events, trade shows, or disaster recovery. These ad-hoc networks provide local coverage and capacity (often via portable “network-in-a-box” systems or cells-on-wheels) for a short period, without relying on public networks. They can support high-bandwidth applications like live video streaming for broadcasters, card payment terminals for merchants, or secure communications for staff. Such networks give users control and customisation, but only need spectrum in a confined area and time window.
- Audiovisual PMSE Systems (Programme Making & Special Events): Wireless microphones, in-ear monitors, cameras, and other equipment used in broadcasting and live events fall under the heading of PMSE. These devices operate at event venues for the duration of a production or show, often in UHF bands. Major events like the Glastonbury Festival, the US Super Bowl or Olympics push PMSE spectrum to its limits, with hundreds of licenses for audio systems as well as dedicated video channels for live broadcast. Spectrum management may reuse the same spectrum bands on different stages, with tight schedules often administered manually. As some traditional frequency ranges get squeezed by mobile services allocations, regulators have had to get creative: additional ranges may be “borrowed” from a variety of incumbents, even including the military.
- Test and trial licenses: Many countries have significant numbers of wireless innovators, as well as research and academic projects working on future wireless concepts and technologies. Vendors, operators, test labs and various vertical industries all need access to spectrum to run lab and field trials, experiments or test newly-manufactured equipment. Even regulatory agencies themselves set up “sandboxes” or other mechanisms for studying wireless technologies.
- Military Communications: Defence-sector agencies – and their suppliers - frequently set up field communications (tactical radio links, mobile command networks, radar systems) for exercises or missions in specific locales. These operations may last days or months in a theatre, using spectrum only in that area. Often, the spectrum is assigned on a non-permanent basis, since after the exercise, the frequencies can be released. Military systems also may hop frequencies or use spread spectrum for security, adding complexity to coordination. While armed forces typically have priority access (and can override civil use in emergencies), day-to-day they face similar issues of avoiding interference with local commercial networks or each other. For example, a military training exercise near a city might need short-term clearance to use a band also used by civil operators, requiring careful timing and geofencing of transmissions.
- Public Safety and Emergency Networks: First responders and public safety agencies increasingly deploy temporary networks during emergencies and large incidents. Examples include portable LTE systems (e.g. deployable FirstNet nodes in the US, or CityMesh’s Land Rover in Belgium) or ad-hoc mesh networks set up at disaster sites, perhaps even using drones as nodes. These ensure temporary mission-critical connectivity at the scene. Public safety also uses dedicated channels (e.g. for firefighters’ radios) that might lie idle until an incident occurs. Managing these intermittent needs is tricky – the spectrum must be immediately available when needed for an emergency, yet one incident’s communications could interfere with another if not coordinated in real time.
- Future Needs: New applications, devices and technologies will further drive short-term localised spectrum use. Pop-up IoT networks and robotic control links on construction sites or for energy/resource exploration, might operate for the project’s duration. New augmented reality/VR and e-sports events, drone swarms, and temporary connected vehicle test tracks are other examples where localised high-capacity spectrum may be needed on demand.
The common thread here is flexibility – users want spectrum when and where they need it, without long-term nationwide licenses. The technologies involved may be standard cellular 4G and 5G, variants of Wi-Fi and its underlying IEEE 802.11, or specialised options for military, industrial or audiovisual use-cases.
Spectrum Sharing Frameworks
Around the world, regulators are developing new frameworks to enable these localised, short-term uses while protecting incumbents. Although full details are outside the scope of this article, notable examples include:
- United States – CBRS Dynamic Sharing: A three-tier sharing model which protects incumbent federal users such as the Navy and Priority Access Licenses (PALs) with up to 10-year leases, allocated by county, but also permits more opportunistic and location-specific General Authorized Access (GAA), coordinating via a cloud-based Spectrum Access System (SAS).
- Europe: Administrative Local 5G Licenses: UK and EU regulators have taken a less dynamic approach to local and temporary licensing for private networks, with a patchwork of different bands available, mostly for enterprise private 4G / 5G and fixed wireless access. Germany has campus licenses in 3.7–3.8GHz, France offers 2.6GHz frequencies for localised industrial use, and the UK has multiple options including 3.8–4.2GHz. CEPT is also investigating that band for pan-European private wireless. However, some of the application mechanisms are done with manual forms and processes, so are often not flexible enough for one-off events and pop-ups. There are exceptions for major events, but at present the number of spectrum transactions and temporary allocations is still constrained.
- Rest of the World: A number of countries have similar local 5G initiatives to Europe or are developing them, including South Korea, Japan, Bahrain, and Australia. Others have more experience of spectrum leasing by incumbent MNOs or other organisations. The Middle East is balancing the needs of its mobile and government users against the growing numbers of major events to deal with (eg, sports tournaments), which need both audiovisual and high-capacity wireless data.
There are multiple other options being developed for spectrum sharing, for instance in the 6GHz band, which is being made available wholly or partially for indoor Wi-Fi and unlicensed use at low powers in some markets, but with options for higher power and outdoor use. There is a mechanism called AFC (automated frequency coordination) that manages interference to incumbent uses such as fixed links. Europe is investigating various models of “hybrid sharing” which could incorporate public mobile access in the band as well. (A subsequent article will cover 6GHz developments).
More temporary & local networks = more spectrum awareness
Granting many short-term, granular spectrum allocations introduces complex coordination problems that did not exist under long-term exclusive licensing. Key challenges include:
- Time Conflicts: When multiple short-term users have overlapping schedules on the same frequencies, interference is possible. For example, two neighbouring film crews might both get licenses to use wireless cameras in a band on the same day in the same city, or two pop-up 5G networks might unknowingly schedule operations at the same weekend. This requires databases and booking systems or portals, as well as mechanisms to deal with (and enforce) over-runs.
- Geographic (Space) Conflicts: Local licenses are by nature close to one another. The small coverage areas mean many independent users could exist within a city or campus such as a port, raising the issue of boundary interference between adjacent private networks. This may require geofences or cooperation between neighbours, or more sophisticated tools for automated spectrum management. Regulators may need to “referee” in disputes.
- Frequency Conflicts: Even when separated by time or space, short-term users can conflict if frequencies overlap or are too close. Many short-duration licenses operate in shared bands, with older or variable-quality equipment, which may have a too-wide emission mask. User error in selecting the wrong bands may be a higher risk, with more events and untrained personnel.
Traditional spectrum enforcement (finding rogue transmitters, spotting higher power than permitted, or resolving interference complaints) becomes exponentially harder with short-term pop-up uses. By the time an interference is reported and investigators arrive, the offending device might have already shut down or moved. Transient interferers such as an unlicensed jammer at an event might evade detection if enforcement isn’t immediate.
In other words, more real-time data and cooperation are essential. Some problems can be addressed by better notification mechanisms, such as crowdsourcing, but in many situations, there will be a need for automated and structured awareness of the spectrum environment. That could be the responsibility of the regulator, the site/event owner, or a third-party spectrum manager.
The role of sensing
Sensing technology is thus emerging as a critical tool for managing temporary or local networks, especially as the numbers and use-case variants scale up. Some sensor functions can be integrated into the devices or networks using the spectrum (for instance, in Wi-Fi accessing AFC systems), while other systems use dedicated external sensing.
Professional sensing is required for monitoring out-of-band transmitters, or temporary sources of interference. Given that many of the pop-up or temporary use-cases are for business- or safety-critical applications, there are obvious security risks that need more strict compliance.
Regulators have long used spectrum monitoring equipment to police the airwaves, but the short-term use model may prompt upgrades, for instance with multi-band sensor systems, sensitive antennas and enhanced signal processing for quick geolocation of problematic transmitters. There will also be many new stakeholders involved, such as venue owners, enterprises with private networks, broadcasters and others.
The US CBRS example also involves the military, which does not want to disclose its operational details, so necessitates the use of a dedicated sensor network linked to the SAS function. Something similar may evolve for other markets and spectrum bands as well. We may even see “sensing-as-a-service” models, where independent parties deploy sensor networks and provide data to regulators or spectrum databases.
Conclusion
We are starting to see an explosion of temporary and localised spectrum use. This has huge potential upside for businesses and communities, but also comes with challenges. Such “democratisation” of wireless technology is driving a need for more and better short-term spectrum management, as well as streamlined request and allocation methods. Much of this will be enshrined in new spectrum-sharing policies adopted by regulators, hopefully on a more standardised and internationally harmonised basis than has been seen in the past.
The tolerance for interference is arguably lower for short-term users than for years-long licenses. A one-time event cannot be rescheduled, so any spectrum failure is highly visible. That in turn implies more automated coordination and better monitoring / enforcement, including via databases and sensors. We can also expect to see much more emphasis on AI and machine learning to model, predict and analyse spectrum usage patterns, pre-empting conflicts, and spotting anomalies.
Regulators and spectrum professionals must critically assess these trends – and plan for ongoing cycles of trials and upgrades, matching innovation in use cases, growth in demand – and also emergence of new interference risks.