Aerial User Equipment

Description

An Aerial UE (User Equipment) is a term introduced in 3GPP Release 18 to describe a UE that supports Uncrewed Aircraft Systems (UAS) and has an aerial subscription. This type of UE is designed to provide cellular connectivity to drones or other aerial vehicles, enabling beyond-visual-line-of-sight (BVLOS) operations and advanced use cases such as aerial inspection, delivery, and surveillance. The Aerial UE must support mandatory capabilities as specified in TS 36.306 for LTE and TS 38.306 for 5G NR, and must undergo successful authentication and authorization of the aerial subscription as described in TS 23.256.

The architecture for Aerial UE involves several network elements. The UE itself is equipped with cellular modems and possibly additional sensors for flight control. The network must support the aerial subscription, which is a subscription profile that allows the UE to access aerial services. The authentication and authorization procedures are defined in TS 23.256, which specifies the UAS authentication and authorization framework. This involves the UAS Service Supplier (USS) and the UAS Traffic Management (UTM) system, which interact with the 3GPP network to authorize the UE for aerial operations. The network also needs to support specific capabilities such as flight path reporting, location reporting, and possibly command and control (C2) communication.

In terms of radio access, the Aerial UE operates like a regular UE but may have different radio characteristics due to its altitude and mobility. The 3GPP specifications in TS 36.101 and TS 38.101 define additional RF requirements for aerial UEs, such as power control and interference mitigation, to ensure coexistence with terrestrial UEs. The network may also apply different mobility management, as aerial UEs can move in three dimensions and may require handovers between cells and even between different altitudes. The Aerial UE may support features like flight path information reporting, which allows the network to optimize handovers and resource allocation.

The Aerial UE concept is part of the broader 3GPP work on UAS connectivity, which aims to integrate drones into cellular networks. This includes support for C2 communication, which is critical for remote piloting, and for payload communication, such as video streaming. The Aerial UE must be able to handle these different types of traffic with appropriate QoS. The network may use network slicing to provide dedicated resources for aerial services. Security is also a key aspect, with authentication and authorization ensuring that only authorized UEs can access aerial services.

In Release 19, the definition of Aerial UE was revised to focus on the communication aspect rather than the subscription details. The new definition states: 'UE performing Aerial UE communication, as defined in TS 36.300 clause 23.17 and TS 23.256.' This change reflects a shift towards describing the UE by its function rather than its subscription status, and it aligns with the ongoing evolution of UAS support in 3GPP. The term continues to be relevant as 3GPP enhances support for aerial vehicles in 5G-Advanced and beyond.

Purpose & Motivation

The Aerial UE concept was created to address the growing demand for cellular connectivity for Uncrewed Aircraft Systems (UAS), commonly known as drones. Before its introduction, drones typically relied on Wi-Fi or proprietary radio links, which have limited range and reliability. Cellular networks offer wide-area coverage, high reliability, and security, making them ideal for beyond-visual-line-of-sight operations. However, integrating drones into cellular networks posed unique challenges, such as interference management, mobility in three dimensions, and regulatory requirements for aerial operations.

The Aerial UE term was introduced in Release 18 to define a UE that meets the specific requirements for aerial communication. It solves the problem of identifying and authorizing drones that are allowed to use cellular networks for aerial operations. The aerial subscription ensures that only authorized UEs can access aerial services, which is crucial for safety and security. The mandatory capabilities ensure that the UE can support the necessary features for aerial communication, such as flight path reporting and C2 communication.

Furthermore, the Aerial UE concept enables the network to apply differentiated treatment to aerial UEs, such as optimized handover parameters and interference mitigation techniques. This helps maintain the quality of service for both aerial and terrestrial users. The evolution of the definition in Release 19 reflects the maturation of the technology, moving from a subscription-centric view to a communication-centric view, which is more aligned with how the UE is used in practice. Overall, the Aerial UE concept is a key enabler for the safe and efficient integration of drones into cellular networks.