Software-defined payload concepts for smallsat communication constellations

Satellite communications development is driven currently by two large disruptions: 1) Integration of satellite and terrestrial networks together, mainly advanced by 3GPP standardization and its NonTerrestrial Networking (NTN) work items. 2) Emergence of large satellite constellations to provide low delay and high-capacity connections globally. These constellations typically consist of hundreds or even thousands of small satellites. In addition to broadband systems, also machine-type communications via satellites is increasing since satellites can provide connections anywhere without the need to build terrestrial infrastructure that is not always possible nor economically feasible.

In order to provide services to very heterogeneous and all the time increasing customer base without yet knowing in detail their future needs, one needs to be able to adapt and update the satellites and satellite constellations over their lifetime. One way to do the update is to launch satellites with better functionalities as part of the constellation. The other option is to update the satellites themselves with the Software-Defined Payloads (SDP). This enables updating the software over-the-air and start using software-defined networking capabilities to integrate satellites tightly as part of 5G/6G networks. Software-defined satellites have payloads and on-board processors that can be reconfigured using commands from ground stations. Software-defined capabilities in the satellite can include beamforming antennas, routing processors, and demodulation capabilities. These payloads make it possible to adapt frequencies and transmission powers and steer antenna beams according to current end user needs. Furthermore, as the processing power of SmallSat platforms increases, it is possible to place some part of the network functions on orbit as well as to provide edge computing capacity for, e.g., task offloading.

The concepts expand the cyber-attack surface and set demands for new security solutions and architecture. For instance, opening of systems for software updates exposes satellites for the integrity violations and added control communications increases availability related risks. Security solutions—from software-defined security, software segregation, and security protocols to hardware and virtualized platform security, and to reactive and learning defences—impose costs and face unique challenges within the space domain.

In this paper, we will make a short review about the current state-of-the-art in software-defined payloads, network softwarization, and network function virtualization in order to identify the potential concepts and technologies for constrained SmallSat platforms. We further intend to include sustainability aspects by introducing SDP concepts which enable simultaneous communications and sensing capability. Moreover, we will provide an overview of SmallSat software frameworks and consider how those can be integrated with communications related SDP that would be managed and orchestrated by integrated terrestrial/non-terrestrial management system. We will discuss cybersecurity aspects as well, pointing potential vulnerabilities that software-defined payloads and remote update possibilities may have - and how to protect systems accordingly.

Finally, we will consider the performance and efficiency of the proposed solutions in order to find out what kind of network functions and Multi-access Edge Computing (MEC) functionality can be distributed to SmallSat platforms. Furthermore, we will consider how the software development pipeline should be arranged to support updating software and creating new services in such SmallSat constellations.