Throughput/channel capacity improvement issues for LEO-satellite based remote sensing systems

LEO-satellite based remote sensing systems, are often built as mono-satellite with limited on-board memory and with mono-ground station. This yields a limited visibility/in-contact interval between the space-segment and the ground station. Consequently, the remotely sensed data present in the on-board memory may not be fully downlinked. To virtually increase this visibility time or alternatively improve the throughput during this time, several techniques have to be addressed. One of the objectives of the present work is to consider the issues for attaining the above-stated goal. Moreover, having the satellite-ground segment link of radio digital data communication type, issues stemming from the analysis of the channel capacity (or throughput) equation are studied to reveal the controlling parameters and hence putting them into play. Out of the identified issues, communicated data rate adaptation is investigated. Implementation issues for rate adaptation are considered and assessment of the throughput/channel capacity improvement on the basis of STK (Satellite Tool Kit software package) is demonstrated and evaluated. The two typical cases of convolutionally encoded image data link and direct sequence spread spectrum (DSSS)-based tracking, telemetry and command links for LEO micro-satellites are considered.