Navigating the future of military and commercial spectrum sharing

Introduction

Radio frequency (RF) spectrum is a finite and highly valuable resource, underpinning a vast array of applications and services, from civilian mobile communications and Wi-Fi to critical military systems such as radar or battlefield command and control. 

Historically, a significant part of the radio spectrum has been exclusively allocated for government and military use. In recent years, the growth in demand from sectors such as public and private 5G (and future 6G) networks, satellite communications (both LEO and GEO), unlicensed short-range wireless and other emerging technologies has intensified the competition for available frequencies, and focused attention on whether some defence spectrum could be repurposed.​ The potential returns from spectrum auctions for mobile use have drawn the attention of many. 

Supply exceeds demand

Simultaneously, the military's own reliance on wireless and RF technologies has been evolving as well. Modern defence systems require more dynamic, agile, and data-intensive communication systems, necessitating greater flexibility. They require complex networked systems for situational awareness. Autonomous systems (drones) in the air, on the ground, and in water all need connectivity while remaining resistant to jamming and electronic warfare. New missions such as peacekeeping and disaster relief require wireless communications both within the military and with civilians and other agencies. 

Taken together, demand for spectrum exceeds supply in many places. Traditional methods of reallocating or clearing spectrum bands are often protracted and costly, making them less viable in addressing immediate needs.​ Exclusive usage rights are preferred by defence and commercial organisations alike, but they may not be possible, especially as newer high-capacity network technologies use wider bandwidths. 

Reassigning a band typically means years of regulatory process, relocation of incumbent systems, and high costs to compensate incumbents or buy new equipment. A recent US Defence Department study of the 3GHz range concluded that forcing the military to vacate the 3.1–3.45GHz band could take decades and up to hundreds of billions of dollars – essentially “not a viable option”. 

Sophisticated spectrum sharing solution

In this context, greater use and sophistication of spectrum sharing emerge as a pragmatic solution. By enabling multiple users—and multiple different wireless systems and protocols—to coexist within the same frequency bands, sharing strategies can optimise spectrum utilisation without compromising the integrity of critical services or undermining innovation and economic development.  

Regulatory bodies, defence agencies, and policymakers are increasingly recognising the importance of developing frameworks that facilitate such coexistence, balancing the needs of both military and commercial stakeholders.​ However, this acceptance is still not universal—many within the cellular industry, in particular, still resist the notion, as do some more conservative voices within the defence sector. 

Military use-cases for radio spectrum  

Before examining sharing options, it is worth giving some background on why the defence sector is so dependent on radio frequency resources. The military's wireless and spectrum requirements are highly diverse, encompassing various applications:​ 

• Radar Systems: Radar is a core military use of spectrum, across fixed air-defence and missile-tracking installations, maritime vessels, airborne platforms, and ground vehicles for surveillance, navigation, and targeting.​ These radars often occupy frequencies in multiple bands (e.g. S-band around 2-4GHz, C-band around 4-8GHz and X-band around 8-12GHz). But these ranges are also now attractive for 5G, commercial satellite communications or other systems such as Wi-Fi. Sharing with radars is challenging, because high-power pulses can significantly interfere with communications systems and vice-versa. 

• Advanced Communications: The defence sector requires extensive personal and data connectivity at both local and wide-area levels, as well as in operational settings. Armed forces worldwide are experimenting with 5G technology for their own communications needs, both mission-critical and base operations. Over time, there are expectations of traditional national or proprietary radio systems integrating with hardened versions of 5G / future 6G for secure, high-speed voice and data transmission. There are also standard “enterprise-grade” wireless network requirements for automating warehouses, connecting AR/VR devices and so on. Using 5G also has interoperability benefits for joint military forces and multinational cooperation, such as those under NATO command. 

• Missile defence and tracking systems: Spectrum-intensive systems like missile defence introduce unique sharing considerations. They rely not just on precision radars (often X-band or Ku-band for detection and tracking) but also secure data links to interceptor projectiles, and between dispersed units for fire-control purposes. The growing threat of both slow-moving drones and new hypersonic missiles expands the range of system requirements and spectrum needs.  

• Space communications: The military is a heavy user of satellites for positioning, navigation, and timing systems such as GPS and communication systems. This again requires significant spectrum resources, across a broad range of bands from UHF (hundreds of MHz) up through Ka-band (around 30GHz). The proliferation of commercial LEO constellations means thousands of new satellites and ground stations emitting in bands that overlap or sit next to military satellite communications. This raises coordination issues for both uplink and downlink.  

• Unmanned Aerial, Ground and Maritime Systems (drones): Military unmanned platforms, ranging from small reconnaissance drones to large weaponised UAVs and UGVs require reliable radio links for control and data, including real-time video transmission. This often relies heavily on reliable and agile spectrum access, working across multiple bands to counter electronic warfare systems. While some small drones use unlicensed Wi-Fi bands (2.4 GHz, 5 GHz) or commercial 4G / 5G for control, larger systems may use dedicated military bands and satcom for beyond-line-of-sight connectivity. The conflict in Ukraine has led to many further innovations to circumvent jamming, including the use of relays, creativity in finding unusual bands or frequency-hopping – and in some circumstances even the use of spooled fibre instead of wireless. 

• Aviation and maritime systems: Air and sea assets use multiple wireless technologies for navigation, positioning and control. For instance, “station-keeping” is an application to keep aircraft or ships at a fixed distance from each other.  

• Civil-military coordination: During peacekeeping, disaster relief, and civil defence operations, effective communication with civilian authorities is crucial. This implies using military wireless systems in civilian spectrum bands and with commercial telecom infrastructure, sometimes (but not always) in coordination with incumbent commercial users. This also means that a deployable radio system might need to function in a foreign country’s frequency bands 

Furthermore, all of these applications now face adversaries in contested electronic warfare environments where jamming and interference are serious threats. This means future military radios and radars must dynamically adapt, changing frequencies or altering waveforms to maintain robust communications or to avoid detection by foes.  

Sharing scenarios 

Several models for spectrum sharing between military and commercial entities are possible. Some exist today, while others are undergoing research or remain hypothetical:​ 

• Tiered and medium-dynamic sharing: This refers to tiered systems, which are similar to the US Citizens Broadband Radio Service (CBRS) model for 3.55–3.7GHz. Here, military and commercial users share bands with a Spectrum Access System (SAS) managing priorities.​ The SAS enforces protections for the top (defence) tier of users, but dynamically assigns frequencies to lower-tier commercial users when incumbents are inactive. This is suitable for relatively predictable and slow-changing environments, such as commercial sharing with intermittent naval radar – ships move quite slowly, and obviously only in coastal areas. Changes can be made over the course of minutes or hours. The trade-off is added complexity and slight uncertainty for commercial users. 

• Highly dynamic sharing: Research is ongoing into systems that allow real-time spectrum allocation, accommodating highly mobile military assets like airborne radars. This may require changing permissions and priorities in seconds or even sub-second intervals, as aircraft appear over the horizon, or as fast-moving ground vehicles come into range. This also typically requires wider area coverage and control, as sharing locations may be much less predictable.​ Low-latency requirements may preclude the use of SAS-type databases, instead relying on devices sensing each other and autonomously negotiating spectrum use. Techniques like listen-before-talk (already used in Wi-Fi’s radar-avoidance mechanism) could be enhanced by AI that predicts when a radar will sweep a given frequency, allowing a 5G cell to temporarily vacate just in time. While there is huge potential here, the engineering challenges should not be underestimated – it will take time and a huge amount of testing before this can be applied to critical systems’ spectrum.  

• Geographic carve-outs: A more straightforward sharing scenario is carving out protection zones for military use within otherwise commercial bands. This involves designating specific areas, such as military bases, key defence manufacturing sites or test ranges, where commercial spectrum use is restricted to protect sensitive operations. This approach can also be refined by using designated time-windows for sharing, as well as location – for instance during scheduled flight training or testing periods. 

• Military use of private 5G: Defence sites are themselves ideal candidates for deploying localised private 5G networks on shared or local-licensed spectrum, under similar conditions to those for enterprise locations. ​Many have requirements for connectivity in warehouses, training and administrative buildings, or for vehicles and cameras across a mid-size area. There are also maritime uses of private networks, either for creating a “bubble” across a group of ships, or for littoral connectivity near a coast, for example including buoys or other assets. 

• Military as a spectrum-sharing tenant on commercial networks: This is essentially “reverse sharing”, i.e. allowing military users to operate on commercially-licensed spectrum, or to share commercial networks with dedicated "slices" or partitions.​ This scenario is attractive for non-combat or home-country use (e.g., on bases, or for National Guard units) where partnering with carriers can be more efficient than deploying parallel networks.  

• Agile, opportunistic, or covert sharing: This describes systems that enable military users to utilise commercial or other spectrum bands covertly or when underutilised. This can enhance operational flexibility and resilience, especially as modern conflict scenarios assume the electromagnetic environment will be highly dynamic and adversarial. One plausible vision is a cognitive radio system that can switch from a jammed or interference-prone frequency to an idle channel somewhere else and shift communications there covertly – even if that is notionally a commercial band. Another option is behind enemy lines - for instance, a Special Forces team might clandestinely use frequencies allocated to a local cellular network to communicate, blending in with civilian traffic to avoid drawing attention. 

• International adaptability: Developing equipment and protocols that allow military operations to adapt to varying national spectrum allocations is important, especially for overseas deployments.​ Allied militaries often operate in each other’s territory for joint exercises or coalitions. Spectrum sharing here is about compatibility with the host nation’s allocations, or perhaps using a local version of dynamic sharing systems, such as a SAS database. 

Each of these scenarios shows a different facet of spectrum sharing for defence. Some are regulator-driven (e.g. CBRS, coordination zones), some are technology-driven (cognitive radio, network slicing), and some are operational tactics.  

They are not mutually exclusive – the future likely involves elements of all, depending on context. The overarching theme of sharing is flexibility: rules and systems that ensure military connectivity can be maintained securely when needed, and spectrum can be opened to others when it’s not, rather than lying idle. 

Examples of military spectrum sharing 

There are various public ongoing or trial examples of spectrum-sharing involving the military, plus others that are confidential. Some relevant projects include: 

• The previously mentioned US CBRS sharing scheme. This is already on its second iteration, with ongoing development and refinement of various of the rules, systems, and processes. 

• More recently, the US auctioned 100 MHz in the 3.45–3.55 GHz range for 5G, under rules that establish geographic coordination zones around dozens of military radar sites instead of blanket exclusion. In these “Cooperative Planning Areas” and “Periodic Use Areas,” carriers can deploy but must adjust power or cede channels when the DoD is operating nearby. 

• The UK MoD has started sharing the 2.3GHz band, and there has been a comprehensive study on sharing options conducted for the Spectrum Policy Forum.  

• US DoD trials of private 5G for AR / VR, automated warehouses, and distributed command and control 

• The European 5G-VINNI project to create a military-grade network slice on public 5G networks, and another EU project, FUDGE-5G, around private networks for defence 

• In Norway, an MNO called Ice is providing a nationwide 5G network slice exclusively for the Norwegian Armed Forces  
• An early Licensed Shared Access (LSA) pilot in Finland’s 2.3 GHz band allowed a commercial mobile operator to use frequencies ordinarily reserved for defence. 

Spectrum sensing and monitoring for sharing scenarios 

While there are multiple sharing options, each band and use case may require a tailored technological solution. There is no one-size-fits-all; a radar band might need a sensor-driven dynamic approach, whereas a communication band might allow scheduling or geographic splits. 

Sophisticated filtering and antenna techniques (like beamforming and null steering) can reduce interference between disparate systems. Automation platforms such as spectrum controllers and cognitive radios may be required to handle split-second decisions that humans cannot reliably make at scale. 

In some cases, effective spectrum sharing hinges on the ability to monitor and manage spectrum usage dynamically. This requires various scenarios for spectrum sensing and modelling. There may be a network of receivers listening for incumbent-user signatures, such as radar, then informing commercial tenants to vacate that frequency in that area. Advances in machine learning and pattern-recognition could greatly enhance automated spectrum monitoring, allowing systems to flag potential conflicts or intrusions faster. 

Key scenarios for spectrum sensing 

• Spectrum awareness: Deploying sensors to map current spectrum usage, identifying opportunities for sharing without causing interference.​ 

• Real-time sensing: Utilising advanced sensing technologies to detect and respond to changes in spectrum occupancy, crucial for highly dynamic sharing models. A radio can’t reliably hop to a free channel if it doesn’t know which channels are free or estimate how long they might stay free. 

• Interference detection: If interference does occur during sharing, it is important to quickly pinpoint the source and resolve it. Spectrum monitoring networks help here by triangulating signals and measuring spectrum use against the allowed patterns.​ 

• Operational situation awareness: Military units in the field increasingly need the ability to detect and characterise signals around them locally. Even a small infantry platoon could benefit from a readout of nearby spectrum occupancy with portable sensors – identifying friendly, hostile, or unknown signals in real time. 

• Compliance monitoring: For large-scale systems such as CBRS or other national commercial/military sharing models, it is essential that all parties adhere to agreed-upon sharing protocols. Putting monitoring systems in place to detect and address violations or anomalies in shared bands. They provide evidence that incumbents are protected and that secondary users are getting fair access when available. 

Conclusions 

The evolving demand / supply imbalance of spectrum necessitates a collaborative approach to sharing between military and commercial entities. Full exclusivity is no longer realistic in all situations. Spectrum sharing is no longer just a theoretical nice-to-have; it is rapidly becoming a strategic and technical imperative, and arguably one in which the West holds a firm lead. 

By embracing innovative sharing models and investing in advanced database, sensing, filtering, and monitoring technologies, it is possible to meet the demands of all stakeholders, without compromising operational integrity or limiting innovation and business potential. Regulatory frameworks must evolve in tandem, fostering an environment where flexibility and cooperation are paramount.​ The narrative is no longer about whether to share, but about how best to share. 

The airwaves need not be a battleground – with the right approach, they can be a shared resource powering both future 6G smartphones and sixth-generation fighter jets.