As of today, Unmanned Aerial Vehicles (UAV) fly exclusively in segregated airspace. Their communication link encompasses both Payload data and Command & Control flows. When beyond the radio line-of-sight, they use mainly Ku-band satellite communications, often through commercial satellites, which are utilized thanks to transponder lease schemes. When under radio line-of-sight conditions, they rely on a wide range of solutions, mainly in C, Ku, S and UHF bands.
In the near future, all civil and military UAV applications will require access to non-segregated airspace at some point in the flight pattern. A seamless integration into air traffic system with an equivalent level of safety as a manned aircraft must be achieved. A key driver is the ability to ensure safe and secure communications between the Unmanned Aircraft Control Station (UACS) and the UAV. ICAO (International Civil Aviation Organisation) recommends, for these communications, the use of aeronautical safety spectrum, acknowledging how crucial they are for the safe integration of UAV within non-segregated airspace.
Figure: Segregated airspace versus non-segregated airspace
The next World Radio Conference 2012 (WRC-2012) will have to decide on the identification of globally harmonized spectrum for UAS safe operation in non-segregated airspace. To accomplish this, in the frame of ITU (International Telecommunications Union) discussions for WRC-2012 preparation, various regulatory methods are envisaged and will be analyzed in the frame of ESPRIT project, each one corresponding to a different alternative in terms of system solution. ESPRIT project objectives can be summarized as follows:
- Propose a preliminary satellite system design for UAS C2 (Command & Control) taking into consideration the requirements coming from current regulation and certification policies and standards at European and International level (ICAO, EASA, Eurocontrol, EFC, FP7, SESAR, STANAG standards, US DoD initiatives and EDA SIGAT findings).
- Develop a business case analysis from the UAS C2 service provider perspective, and an analysis of the operational concept of the satellite system.
- Taking into account the status of the regulatory studies and the preliminary system design for UAS C2 defined in the frame of this project, define an action plan and actively contribute towards CEPT and ITU studies under WRC-2012 agenda item 1.3 to ensure a globally harmonized spectrum for UAS safe operation in non-segregated airspace.
The Key issues at stake in the frame of this project are the following:
- With the introduction of medium and high altitude UAV, with extreme long range and endurance, there is a growing requirement for BLOS (Beyond Line of Sight) capabilities, for both control and mission data,
- As of today, UAS operating in segregated airspace mainly use Ku-band FSS satellite communications, often through commercial satellites, which are utilized thanks to transponder lease schemes. However, this is not in line with ICAO position for the operation of UAS in non segregated airspace: UAS C2 links need to use safety bands, i.e. AMS(R)S bands. Indeed, ICAO recommends, for these links, the use of aeronautical safety spectrum, acknowledging how crucial they are for the safe integration of UAV within non-segregated airspace,
- WRC2012 to be held in February 2012, is a key milestones for the allocation of new worldwide and harmonized frequency bands to UAS control links.
ESPRIT project key benefits will be the following
- The system that will be proposed in the frame of ESPRIT will offer a high capacity, be compatible with very stringent availability requirements and will be in line with ICAO position at WRC 2012,
- Based on a satellite architecture, ESPRIT design will offer some key benefits such as an extensive satellite coverage, and thus the capability to operate in remote areas without any terrestrial infrastructure,
- Finally, provided that a worldwide frequency allocation is chosen, the ESPRIT solution will provide a global and unified Command and Control capability beyond-line-of-sight conditions and thus, offer, through a single equipment, an universal access to all civil airspaces worldwid.
The preliminary architecture presented below provides an initial baseline that will have to be refined in the frame of ESPRIT project.
The UACS (UA Control Stations) are connected to a satellite communications system. Each UACS is able to command and control one or various UAV. The UACS are supposed to be outside the communication system.
This system should be compatible with very stringent availability requirements and should be able to offer a high capacity.
Finally, depending on the frequency allocation finally chosen, the solution could provide a global and unified Command & Control capability beyond-line-of-sight conditions and, thus, offer, through a single piece of equipment, a universal access to all civil airspaces worldwide.
During the 9-month project duration the following plan will be implemented in order to fulfill the objectives of the project:
- Provide a status on current regulation and certification policies and standardization activities to allow UA flight in non segregated airspaces,
- Define and justify the satellite mission and system requirements and propose a preliminary design of a new satellite system and its operations,
- Define the required modifications to existing or planned satellite systems so that they would qualify for UAS C2,
- Establish a deployment plan for both a new and existing satellite system solution,
- Provide a cost assessment and a business case analysis under the UAS C2 service provider point of view,
- Provide a radio regulatory status review and an action plan definition including the contribution to regulatory meetings under WRC 2012 agenda item 1.3 on globally harmonized spectrum for UAS safe operation in non-segregated airspace.
The project has been finalised.