Aircraft connectivity challenges
Flight efficiency benefits from the introduction of advanced operational concepts and cutting-edge technologies in aviation. The modernisation of aviation infrastructure is underway based on digitalisation, automation and hyperconnectivity.
Higher levels of connectivity entail a new generation of broadband air-ground communication data links which are to be implemented in the framework of future communication infrastructure (FCI) technologies based on ICAO’s Aeronautical Telecommunication Network (ATN) Internet Protocol Suite (IPS).
FCI encompasses legacy (i.e. VHF voice and VHF Data Link Mode 2) as well as new communication systems. The new FCI communication systems include the Aeronautical Mobile Airport Communications System (AeroMACS), satellite-based data link(s) (SATCOM), covering oceanic and continental environments, and the terrestrial L-band Digital Aeronautical Communications System (LDACS) for continental airspace.
The new FCI data links will sustain new advanced operational concepts like trajectory-based operations, relying on near real-time downlink of flight management parameters. Air traffic control will no longer be based on where the aircraft “is” but on where the aircraft “will be”. There will be an optimal synchronisation between the airborne- and ground-based trajectories, the exchange of time constraints.
Huge benefits can be achieved if FCI technologies are implemented based on distributed software-defined radio (SDR) architectures. Such benefits range from upgradability and reusability of the design (since a greater number of common radio functions are implemented through software), weight savings on wiring and equipment, reduction of RF interference and functional flexibility facilitating integration between communication, navigation and surveillance data exchanges.
SDR as an interoperability multiplier and avionics optimiser
SDR technologies are reconfigurable and programmable, with multiple functions integrated in one “box”/form factor, mitigating space constraints, reducing hardware and rationalising equipage. The rapidly evolving SDR digital electronics render practical the use of one single transceiver equipment to receive and transmit different radio waveforms based solely on software.
Today’s avionics architectures remain fragmented and insufficiently integrated. Modern SDR technologies eliminate conventional packaging architectures, organising the integration of the radio functional blocks over two separate pieces of equipment (Figure 1):
• Antenna unit (AU) (with RF front end) – integrated close/next to the antenna and including analogue/superheterodyne radio components (e.g. power amplifier (PA), low noise amplifier (LNA)), AD/DC conversion stage and, sometimes, certain elements of the digital processing stages);
• Radio unit (RU) – located in the avionics bay, comprising a high performance single board computer/computing platform to digitally process (through software) the remaining stages among the digital radio functional blocks. This unit can be multi-instantiated to support, concurrently, multiple aircraft radios.
Figure 1 - (A) Conventional and (B) distributed software-defined radio architectures
The radio unit will be able to host and process simultaneously multiple waveforms and support avionics interfaces (Figure 2). Based on strong partitioning, it is possible to merge radio software onto a common platform supporting the software corresponding to multiple radios.