Survey of Software-Defined Radio and Optical Communication Techniques for Inter-Satellite Links

This paper surveys recent advances in software-defined radio (SDR) technologies and free-space optical (FSO) inter-satellite links (ISLs) for next-generation satellite networks. We review SDR architectures and heritage in spaceborne radios, discuss optical link technologies and terminal design, and examine integration strategies where SDRs control or adapt optical ISL subsystems. Key design considerations, modulation and coding choices, pointing, acquisition and tracking (PAT) mechanisms, and networking implications for constellation use cases are presented. Where possible, we cite openly available preprints and project reports to ensure references are accessible to all readers [1]–[3], [5]. Finally, we identify research gaps and propose directions to enable resilient, reconfigurable, high-capacity inter-satellite optical networks.