What are satellite communications
Satellite communications encompasses all communication performed over a satellite link. Our interest at UMDCC lies primarily in the up-link portion of the satellite link; where uncoordinated terrestrial based transmitters contend for the resources of a single satellite receiver. This scenario provides a whole host of unique challenges not found in many other communication environments. These challenges range from long propagation delays incurred by the sheer distance the signal must travel (nearly 36,000 km one way for a geosynchronous satellite) to the localized weather effects arising from the geographic spread of users.
Why are we interested
The increase in capabilities of satellite receivers to support mobile and interactive multi-user services has been directly called for by the European Space Agency. To enable these services new techniques are required to increase the utilization of channel resources in the multi-user environment. The current work in this area focuses on achieving the single user capacity of the channel, however it is known that with modern joint detection and demodulation techniques it is possible to surpass the single user capacity in a multi-user channel such as that offered by the satellite-uplink.
How are we contributing
Multi-user cancellation based receivers are limited by their ability to accurately reconstruct the incoming signals from a number of concurrent users. The team at UMDCC is investigating iterative estimation techniques where the estimation block is coupled with the iterative demodulation process. We have proven these receiver structures are capable of reducing the problem arising from inaccurate signal reconstruction and subsequently increasing the potential throughput of the uncoordinated satellite link. Preliminaries of this work have been presented at the 8th International Turbo Coding and Iterative Information Conference, and Milcom 2014.