Estimation of Future Communications Bandwidth Requirements for Unmanned Aircraft Systems Operating in the National Airspace System

Abstract

[Abstract] There are significant activities taking place to establish the procedures and requirements for safe and routine operation of Unmanned Aircraft Systems (UAS) in the National Airspace System (NAS). Among the barriers to overcome in achieving this goal is the lack of sufficient frequency spectrum necessary for the UAS control and Air Traffic Control (ATC) communications links. This shortcoming is compounded by the fact that the UAS control communications links will likely be required to operate in protected frequency spectrum, just as ATC communications links are, because they relate to “safety and regularity of flight”. In anticipation of the need to support future ITU World Radio Conference agenda items concerning new frequency allocations for UAS communications links, NASA Glenn Research Center has sponsored work to estimate the UAS control and ATC communications bandwidth requirements for routine operation of UAS in the NAS. This paper describes the process and results of this work. This study focused on long term bandwidth requirements for UAS approximately through 2030. For estimation purposes, the work was based on the concept that UAS must be compatible with current NAS operational procedures. This led to the recommendation that both ATC communications and UAS commands be provided via Air/Ground line of sight communications links using a networked ground infrastructure architecture, and assumed ATC and control communications link handoffs would occur as unmanned aircraft move through different regions of the NAS. A two pronged approach was used to accommodate the two different link types. For estimating UAS ATC communications service/message requirements, the Communication Loading Analysis model of the Concept of Operations and Communication Requirements (COCR) for the Future Radio System developed by the FAA and Eurocontrol was used as appropriate to fit UAS specific mission needs and requirements. STANAG 4586, Standard Interfaces of UAV Control System (UCS) for NATO UAV Interoperability, was used for defining key control/status message parameters for estimating aggregate UAS control communications message data requirements. Conversion of UAS communications data requirements to corresponding bandwidth requirements was performed by performing power/bandwidth tradeoffs through link analysis to identify channel bandwidth, then applying this channel bandwidth with suitable carrier access approach, along with density estimates of unmanned aircraft counts, to a multi-level cellular-type sector architecture.