Up-link symbol-synchronous TDMA SATCOM system architectures

Candidate architectures for time division multiple access (TDMA) satellite communication systems wherein signal processing operations would be performed by satellite-borne subsystems are considered. These architectures require symbol-synchronous up-links to be established and maintained. Also, each up-link signal would be detected differentially - either at one or more terrestrial terminals after being relayed or by a satellite-bounce detector. These concepts provide a basis for implementing practical TDMA systems wherein one or more of the following operations would be performed within the satellites: adaptive spatial processing, spectrum collapsing and bandpass filtering, signal detection, message switching, forward error correction coding, remodulation, spectrum spreading of the downlink signal, antenna beam switching, and resource management. Selected combinations of these operations are delineated and their relative advantages and limitations are addressed. Prototype demand-assignment TDMA modems and an experimental satellite simulator, which are considered to have established that the concepts considered are both practical and effective, are also described briefly.