Direct-to-Device Connectivity for Aviation: Opportunities for Integrated CNS Services

Satellites are a key component of aeronautical telecommunication networks for supporting communication, navigation, and surveillance (CNS) services. Satellite communication, also known as SATCOM, acts as a bridge between aircraft and terrestrial infrastructure and establishes air-to-ground data (A2G) datalinks to connect aircraft with the air navigation service providers. For example, SwiftBroadband-Safety (SB-S) has been emerged to provide a global, secure, broadband IP connection for both operations and safety communications to aircraft, which can support CPDLC and ADS-C services with the same safety services, helping airlines to be ready for future air traffic management evolutions. Iridium, partnership
with Aireon, supports satellite-based automatic dependent surveillance – broadcast (ADS-B) in oceanic areas. Global navigation satellite system (GNSS) is the underlying technology that enables safe navigation and provides precise location data for ADS-B [1].

As an important milestone, Airbus and OQ Technology through their fruitful collaboration have demonstrated the feasibility of connecting an unmanned aircraft, carrying a 5G user equipment, to a low-Earth orbit (LEO) satellite running a full stack of 5G base station. Recently, many major airlines started to offer Starlink connectivity to passengers enabling Internet services including browsing and 4K video streaming. Despite these advancements, small unmanned aircraft may not be able to benefit from traditional satellite systems, whose terminals are often large and energy-hungry.

Direct-to-Device (D2D) connectivity is an emerging concept in new space era satellite communications [3]. D2D connects compact consumer devices e.g., smartphones, wearables, and machine type device directly to Earth orbiting satellites without relying on terminal or mediator gateways. Due to small device form factors and high energy efficiency, D2D appears as a promising solution for meeting the CNS service requirements of unmanned aircraft system (UAS). Particularly, D2D devices due to small form factor and low energy consumption can be mounted on the unmanned aircraft and could provide satellite-based A2G links to support CNS services. D2D links can enable beyond-line-of-sight coverage over remote and oceanic regions, augments GNSS accuracy through correction data and 5G NTN support, and facilitates transmission of ADS-B and ADS-C, enabling situational awareness,and resilient CNS operations for UAS.