Error-control coding and packet processing for broadband relay satellite networks with optical and microwave links

A satellite network with a GEO data relay satellite and LEO satellites is considered. Broadband data from LEO satellites are transmitted via laser intersatellite link to the GEO relay and then via microwave downlink to the ground. The GEO relay is operated as a regenerative repeater, dominated by onboard digital processing between laser and microwave links. In order to achieve maximum independence between the network elements, all data is packetized and frames are encapsulated by superframes and hyperframes in several stages. Even with the usage of well-known traditional error-control coding schemes in LEO and GEO, the interaction between coding, framing and reframing operations and the relations between various packet error rates is challenging but essential for performance assessment. The laser terminals of the optical link are subjected to microvibrations. The vibration spectra of LEO and GEO satellites are converted into a time-variant discrete-time model of the optical link, allowing the generation of error patterns for simulation purposes. The simulation is supplemented with analytical calculations for the prediction of asymptotic error rates. Results available so far prove the performance of the data processing algorithms in particular and the GEO relay concept in general.