For the purposes of the present document, the terms and definitions given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905. Above ground level (AGL): Command and Control (C2) Communication: Uncrewed Aerial System (UAS): Uncrewed Aerial System Traffic Management (UTM): UAV controller: UxNB:

For the purposes of the present document, the following symbols apply:

For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905. BVLOS C2 Remote ID UAS UAV UTM

An Uncrewed Aerial System (UAS) is the combination of an Uncrewed Aerial Vehicle (UAV), sometimes called a drone, and a UAV controller. A UAV is an aircraft without a human pilot onboard - instead, in some cases. the UAV can be controlled from an operator via a UAV controller and will have a range of autonomous flight capabilities. The communication system between the UAV and UAV controller is, within the scope of this specification and in some scenarios, provided by the 3GPP system. The UAS model considers also the scenario where the UAV controller communicates with the UAV via mechanisms outside the scope of 3GPP. UAVs range in size and weight from small, light aircraft often used for recreational purposes to large, heavy aircraft which are often more suited to commercial applications. Regulatory requirements vary across this range and vary on a regional basis. The communication requirements for UAS cover both the Command and Control (C2), and uplink and downlink data to/from the UAS components towards both the serving 3GPP network and network servers. The applicable C2 communication modes is depicted in clause 4.2. Uncrewed Aerial System Traffic Management (UTM) is used to provide a number of services to support UAS and their operations including but not limited to UAS identification and tracking, authorisation, enforcement, regulation of UAS operations, and also to store the data required for UAS(s) to operate. It also allows authorised users (e.g., air traffic control, public safety agencies) to query the identity and metadata of a UAV and its UAV controller.

When using 3GPP network as the transport network for supporting UAS services, the following C2 communication are considered to provision UAS services by guaranteeing QoS for the C2 communication: Direct C2 communication: Network-Assisted C2 communication: UTM-Navigated C2 communication: In general, Direct C2 communication and Network-Assisted C2 communication are used by a human-operator using a UAV controller. UTM-Navigated C2 communication is used by the UTM to provide cleared flying routes and routes updates. In order to ensure the service availability and reliability of the C2 communication for UAS operation, especially when the UAV is flying beyond line of sight (BLOS) of the operator, redundant C2 communication links can be established for any C2 communication links from UAV controller or UTM to a UAV. For reliability and service availability consideration, it is possible to activate more than one C2 communication with one as a backup link for C2 communication or switch among the applicable links for C2 communication.

• For example, Direct C2 communication can be used at first and then switch to the Network-Assisted C2 communication when the UAV is flying BLOS.
• For example, UTM-navigated C2 communication can be utilized whenever needed, e.g. for air traffic control, the UAV is approaching a No Drone Zone, and detected potential security threats, etc.

There are four control modes considered in the C2 communication for the UAV operation that are with different requirements, e.g. on message intervals, sizes, and end to end latencies, etc., including steer to waypoints, direct stick steering, automatic flight by UTM and approaching autonomous navigation infrastructure.

• Steer to waypoints: the control message contains flight declaration, e.g. waypoints, sent from the UAV controller or UTM to the UAV. The control mode is used in both of direct C2 communication and network-assisted C2 communication.
• Direct stick steering: the control message contains direction instructions sending from the UAV controller to the UAV while optionally video traffic is provided as feedback from the UAV to the UAV controller. The control mode is used in both of direct C2 communication and network-assisted C2 communication.
• Automatic flight by UTM: the control message contains a pre-scheduled flight plan, e.g. array of 4D polygons, sent from the UTM to the UAV, which thereafter flies autonomously with periodic position reporting. The control mode is used in UTM-Navigated C2 communication.
• Approaching autonomous navigation infrastructure: the control message contains direction instructions, e.g. waypoints, altitudes and speeds from the UTM to the UAV. When the UAV is landing/departing, the UTM coordinates more closely with autonomous navigation infrastructure, e.g. vertiport or package distribution center. The control mode is used in UTM-Navigated C2 communication.

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Beyond UAV related requirements, the 3GPP can be used to support for a wide range of applications and scenarios by using low altitude UAVs in various commercial and government sectors. New service level requirements and KPIs for supporting various UAV applications by the 3GPP system have been identified and specified e.g. Service requirements and KPIs related to command and control (C2), payload (e.g. camera) and the operation of radio access nodes on-board UAVs.

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