European Space Agency

RPAS-HAPS - Broadband Satellite Communications to RPAS Using HAPS


The objective of the activity is to design, develop, and demonstrate a GEO satellite communication system that integrates an intermediate layer of HAPS to provide command and control links, broadband payload data communications and inter-vehicle links to swarms of unmanned vehicles. The project aims at providing Broadband Satellite Service via HAPS (BSSH), as communication services to RPAS verticals over satellites utilizing HAPS as a permanent relay, particularly for those areas with limited radio coverage or bandwidth. While several satellite solutions exist for provision of communication services to aircraft, most RPAS cannot use these solutions because of their size, weight and power constraints. Only a minority of larger RPAS can embark satellite terminals in Ku or Ka band.

To that end, the project firstly captures the technical requirements of a joint RPAS and HAPS communication system over GEO satellites based on the high-level user requirements and environmental system characteristics Secondly, the project aims to design an end-to-end broadband satellite communication system that meets those requirements. Finally, the project implements the communication system as a demonstrator for validation and verification of the system technical requirements. The targeted improvement is enabling communication between GEO satellites and RPAS using HAPS as a relay.


The core activity of the project is to specify, design, develop and demonstrate the BSSH system. The first major challenge is the system design through a balanced trade-off of design options, considering the constraints imposed by both the channel impairments and the available frequency bands assigned by regulatory while fulfilling the set of end-user requirements with respect to BSSH key performance indicators such as throughput, latency and availability. The second challenge is the implementation of a configurable real-time BSSH demonstrator for verification of the system requirements. Finally, the test campaign is considered as a time consuming workload.


The UAV verticals including drone operators and UAV air traffic management service providers are considered as main target users.

Drone operators need preferably an on-line processing and analysis of a huge amount of survey data (e.g. video and sensor data) captured by the drones. By on-line data processing, in case the collected data is not conclusive enough, the operators have the opportunity to retry the session at once and on the spot minimizing the risk for a costly reuptake of the mission on-site if an off-line analysis reveals that the collected data is incomprehensive.

The BSSH aims at providing the following Key Performance Indicators (PKI) to the UAV verticals:

  • High throughput
  • Low delay
  • Low power consumption
  • Service provision to many UAVs in swarm
  • Networking via IP Mobility

The intended BSSH system coverage area is all member states of the European Civil Aviation Conference (ECAC). The figure shows exemplary how a cluster of 6 HAPS can provide coverage over UK and Ireland.


Geographical Coverage: The satellite as core anchor of the Broadband Satellite Services via HAPS (BSSH) provides the much needed full geographical coverage to UAV verticals by utilization of HAPS as relay particularly necessary in areas with limited terrestrial radio coverage. The HAPS overcomes the last miles down to the small drones featuring limited energy and size with no satellite terminals in Ku or Ka band. The satellite can additionally provide connectivity for command and control data in case of Beyond-Radio-Line-of-Sight operational scenarios.

Broadband Communications: For the provision of user traffic such as video or earth observation data the RPAS rely on high throughput links. The broadband satellite communications offer low in price bandwidth compared with the existing and future terrestrial links such as in high price 5G technology.

System Architecture

The Broadband Satellite Service via HAPS (BSSH) provides the UAV verticals with a broadband communication services enabling the exchange of control and user data particularly for applications that require low delay, high reliability, and high throughput, such as applications in UAV air traffic management, earth observation, and public safety. The figure below shows the BSSH system overview.


Following a comprehensive review and analysis of the scope of the work and the available standards and existing regulations for HAPS and RPAS, the project defines the operational scenarios and the related system requirements as input for the specification of the technical requirements particularly for the datalink RPAS-HAPS. Starting from a complete set of technical requirements the project aims to design, develop and demonstrate the BSSH system.

The project plan comprises the following work packages and milestones, viz:

WP0: System scenario

WP1: Technical specification

WP2: System design  

WP3: System validation and verification

WP4: Demonstrator

WP5: Project management

Project Milestones

SRR:  System Requirements Review

SDR:  System Design Review

DDR:  Demonstrator Design Review

TRR:   Test Readiness Review

TRB:   Test Review Board 

Current status

Upon a successful kick-off meeting attending ESA and Frequentis members at Project Start: 15 June 2020, the Frequentis team has started developing the BSSH system scenarios and the general requirements. The next review milestone is planned as System Requirement Review (SRR) in Q4 2020 following the System Design Review (SDR) in Q1 2021.

Status date

Monday, July 6, 2020 - 13:58