Short Messaging Service Study

Status date

To conduct a study into the feasibility and viability of including a Short Messaging Service (SMS) within Galileo. The service could support a number of functions including both civil and commercial applications, resulting in savings to civil agencies, enhanced safety of life features and revenue generation for commercial entities.

The use of the SMS to validate and accurately locate Search and Rescue (S&R) signals prior to the dispatch of resources would enhance the accurate and rapid location of distress signals. This provides enhanced safety of life capability and significant cost savings to regional Search and Rescue agencies across multiple jurisdictions due to reduced false alarm levels. The potential for new revenue generating applications is also significant based on the growing number of successful SMS applications that continue to emerge in terrestrial wireless networks. Suitably structured, an SMS capability could enhance or enable new revenue generating services for Galileo.

The study explores the technical, civil and commercial aspects of including SMS within the Galileo services.

The key issues in the study revolve mainly around the interoperability of the envisaged SMS service and the baselined Search and Rescue (S&R) service onboard Galileo. A standalone SMS payload must be form and fit compatible with the S&R payload to minimize impacts to the spacecraft design. Alternatively, a combined SMS/S&R payload must still meet the mass, volume and power resources set aside for the standalone S&R payload. In either case, the use of the existing S&R antenna for either a dual-mode payload or a standalone SMS payload must be investigated to minimize any impacts to the spacecraft design.


The combination of global, real-time S&R service with two-way messaging capability has several key advantages for both the Search and Rescue community as well as Galileo S&R/SMS customers.

The use of the SMS to validate and accurately locate S&AR signals prior to the dispatch of resources would enhance the accurate and rapid location of distress signals. The ability to respond to verified distress signals results in significant cost savings, as a high proportion of the signals received currently are false alarms.

SMS allows not only for acknowledgement of S&R beacon activation to the user but also allows the user to provide refined location information and information on the nature of any medical emergencies. This results in enhanced safety of life capability through the appropriate allocation of Emergency and Medical assets for the specific circumstances of the distress event. At the same time, such a two way service would also enable rescuers to provide temporary first-aid directions while en route to the distressed persons.

The service could also be used to support monitoring and rescue operations following natural disasters in remote regions, or to provide messaging to polar regions - unavailable through other satellite platforms, or to support Long Range Automatic Identification System (AIS) for marine safety and security applications.

The SMS payload itself functions as a simple transponder, as does the S&R payload. The key feature of the proposed SMS service is compatibility with the S&R service with no major impacts to the Galileo spacecraft design.

During this study, two options will be pursued: a standalone SMS payload deployed on some fraction of the Galileo spacecraft (with the remainder of the spacecraft carrying an S&R payload) or a dual-mode SMS/S&R payload deployed on every Galileo spacecraft.

In the case of a standalone SMS payload, the unit must be form and fit compatible with the baseline S&R payload including mass, volume, and power allotments. The relative distribution of SMS and S&R payloads within the constellation must be determined from analysis.

Alternatively, a dual-mode payload must accommodate the functionalities of both SMS and S&R payloads within the allotted volume, mass and power and must enable switching between modes on command.

The study incorporates all aspects of a possible SMS service. Market demand for SMS service will be investigated and service scenarios including billing structures will be suggested. An assessment of any relevant regulatory issues especially concerning available spectrum will be performed. The baseline technical design of the SMS service will be formulated including such aspects as mission architecture, payload architecture, air interface, network and terminal requirements. In addition, a program plan including schedule, budget and work breakdown will be developed for a phase A study.

Current status

Potential Applications:

  • Current global demand focused on Safety, Security and Surveillance

  • (particularly maritime) aligns with Galileo SMS - Galileo SMS provides an enhancement of Safety of Life and SAR

  • Potential to support a wider range of applications in the mobile market
Mission Design Summary:

  • Low data rate bursts (1 kbit/s)

  • L band uplink (2 MHz total bandwidth) and UHF band downlink (1.1 MHz total bandwidth) for the user link

  • C band feeder link is assumed for the Gateway link

  • Initial deployment should be 3 satellites per plane with the SMS payload

  • SMS gateway are assumed to be co-located with the SAR MEOLUTs with a 3.8 m antenna
Payload Design Summary:

  • A dual mode analog SMS/SAR transponder is feasible within the power and mass envelope available on the satellite (100 W and 15 kg)

  • In orbit switching of the payload between SMS and SAR mode possible

  • A separate antenna is necessary for the C band gateway link

  • A common SMS/SAR antenna is selected for the user link

  • Must be Galileo NAV RX enabled

  • Single carrier SMS signal

  • Operating in half-duplex

  • SMS implementation within Galileo spacecraft is technically feasible

  • Development of space and ground SMS hardware is compatible with Galileo FOC schedule