The Two Main Direct-to-Device D2D Spectrum Options Explained
Direct-to-device, often shortened to D2D, is one of the most important developments in satellite and mobile communications. It refers to satellite services that connect directly to ordinary phones or other mass-market devices rather than relying only on specialist satellite terminals. But one of the biggest questions behind D2D is not just how the satellites work. It is which spectrum is used.
At the moment, there are two main direct-to-device D2D spectrum options. The first is to use terrestrial mobile spectrum, typically spectrum already associated with mobile network operators. The second is to use mobile-satellite service spectrum, usually called MSS spectrum. GSMA’s 2025 and 2026 guidance describes these as two distinct spectrum paths for D2D services, while Ericsson’s 2025 technical review says both the terrestrial mobile spectrum model and the MSS model are viable pathways for expanding mobile coverage from space.
Why Spectrum Matters So Much in D2D
Spectrum is not just a regulatory detail. It shapes what kinds of D2D services can be delivered, how easily they can be authorised, what handsets may work, how interference is managed, and how quickly a service can scale. Ofcom’s 2025 D2D statement makes this clear by setting out a specific UK framework for authorising D2D services in mobile spectrum bands, while also continuing separate work on the future use of 2 GHz MSS spectrum.
Option 1: Terrestrial Mobile Spectrum
The first major option is to use the spectrum that is already licensed for terrestrial mobile services. In this model, satellite operators typically work with mobile network operators so that the satellite service acts as an extension of the mobile network in areas not covered by terrestrial infrastructure.
Ofcom’s 2025 decision explicitly concerns the use of spectrum bands used by the UK’s mobile network operators for D2D services. It says these services can increase outdoor geographic coverage and provide a basic backup service in the event of terrestrial outages. GSMA also says regulators are permitting D2D using mobile spectrum through terrestrial spectrum licences.
Why this model is attractive
- It fits more naturally with the existing mobile ecosystem.
- It can support ordinary smartphones using familiar cellular standards.
- It aligns with operator partnerships and mainstream mobile service models.
- It makes D2D feel more like an extension of mobile coverage than a separate satellite product.
Ericsson’s review says the terrestrial mobile spectrum model leverages a mature terrestrial ecosystem, which is one reason it has drawn so much industry attention.
The downside
The difficulty is that this path creates more complex interference and regulatory questions because the same spectrum is already used by terrestrial mobile networks. Ericsson notes that this model demands sophisticated interference management and more complex regulatory navigation.
Option 2: MSS Spectrum
The second main option is to use mobile-satellite service spectrum. This is spectrum already associated with satellite use rather than ordinary terrestrial mobile use. In this model, the D2D service is built more directly on satellite spectrum rights.
GSMA’s 2025 guidance and Analysis Mason’s 2025/2026 commentary both describe MSS as one of the two main strategic spectrum paths for D2D deployment. Ofcom has also been separately reviewing the future use of the 2 GHz MSS band, and its consultation documents specifically mention D2D activity using awarded 2 GHz MSS frequencies.
Why this model is attractive
- It sits in a more established satellite regulatory environment.
- It can reduce interference risk compared with sharing terrestrial mobile spectrum.
- It fits naturally with satellite operators already holding MSS rights.
- It may provide a cleaner policy path in some markets.
Ericsson’s 2025 technical review says the MSS model offers a more stable regulatory environment, lower interference risk, and support from 3GPP-backed technical specifications.
The downside
The challenge is that MSS-based D2D may be more limited from a handset perspective. Ofcom’s 2025 technical material notes that D2D in MSS spectrum may require hardware or firmware updates depending on the RF chipsets used, and may therefore require customers to migrate to newer compatible models. It also notes that in some conditions, MSS-based D2D may be limited to messaging.
Mobile Spectrum vs MSS Spectrum: What Is the Real Difference?
The key difference is not just “terrestrial versus satellite.” It is about ecosystem fit.
- Mobile spectrum D2D is more closely tied to operator-led mobile extension models.
- MSS spectrum D2D is more closely tied to traditional satellite rights and satellite-led service models.
GSMA explicitly describes these as two distinct spectrum paths with different regulatory implications. Analysis Mason similarly says there are two spectrum strategy options for deploying satellite D2D services: MSS spectrum and mobile spectrum.
Which Option Is Better?
There is no universal winner. The answer depends on the business model, the target handset base, the operator relationship, and the regulatory environment.
Mobile spectrum is often more attractive where the goal is broad integration with the mainstream mobile ecosystem and support for standard smartphones as naturally as possible.
MSS spectrum is often more attractive where the satellite operator already holds spectrum rights and wants a more satellite-native path with potentially lower interference risk.
Ericsson’s 2025 summary is useful here: both are viable pathways, but they come with different trade-offs.
Why Regulators Care
Regulators care because D2D changes how spectrum is used and how rights intersect between terrestrial and satellite systems. Ofcom’s recent work makes clear that D2D is no longer hypothetical in the UK. It has created a framework for mobile-spectrum D2D while continuing work on MSS-related questions as separate strands.
That means the future of D2D will be shaped as much by spectrum policy as by satellite engineering.
What This Means for the Market
The market is likely to keep using both options. Some providers may focus mainly on operator-led mobile spectrum partnerships. Others may emphasise MSS-based services. Some, as recent Light Reading reporting suggests, may even pursue multiband approaches that include both MSS and terrestrial mobile spectrum.
So the practical future of D2D is unlikely to be one spectrum model defeating the other. It is more likely to be a mixed market in which different services use different spectrum paths depending on what they are trying to achieve.
Final Thoughts
The two main direct-to-device D2D spectrum options are terrestrial mobile spectrum and MSS spectrum. The mobile-spectrum model is attractive because it fits naturally with the mainstream mobile ecosystem, but it creates more interference-management and regulatory complexity. The MSS model offers a more satellite-native path with lower interference risk in some cases, but it may place more limits on handset support and service evolution. Current GSMA, Ofcom, Ericsson, and Analysis Mason material all support this two-path view of the D2D market.
Craig Miles
Helping organisations understand wireless, RF & satellite communications.
Advisor • Trainer • TEDx Speaker • Founder, Yesway Communications