APSIM - Antennas and Signal Processing Techniques for Interference Mitigation in Next Generation Ka Band High Throughput Satellites

Principal investigator: Dr. Symeon Chatzinotas
Partner: Space Engineering SPA (IT), VTT (FI)
Funding: ESA-European Space Agency
Researchers: Dr. Shree Krishna Sharma, Dr. Eva Lagunas

About the Project

Future Broadband Satellite Systems target achieving system capacity approaching the terabit/s. The most efficient way for pursuing this achievement is to use all the available band in Ka for user links, moving the feeder links to Q/V band. The use of large portions of Ka band for user links by uncoordinated stations may represent therefore in the future a necessary resource for increasing the capacity of future broadband satellite communication systems. This topic is currently being investigated in different contexts.

In Europe, at CEPT level the bands 27.5-30 GHz for Earth-to-Space and 17.3-20.2 GHz in the Space-to-Earth direction are allocated to FSS, but with different rules in different portions of the band. Traditional Ka band systems mostly uses the portion of the Ka band commonly referred to as “exclusive” band in the user links, that corresponds to the band 19.7-20.2 GHz in the user forward link (Space-to-Earth) and 29.5-30 GHz in the user uplink (Earth-to- Space). On the other hand, the 17.3 – 17.7, 17.7 – 19.7 GHz and 27.5 – 29.5 GHz are shared with terrestrial fixed services (FS). As a consequence, current systems use these bands in the feeder links to make easier the coordination due to the low number of stations and their high isolation capabilities thanks to the large reflectors deployed. Nonetheless, these bands (or at least part of them) can be used by uncoordinated stations. The main problem in this band is that satellite systems cannot claim protection against other terrestrial services, allocated to the same band. These services (fixed wireless systems operating in the 18 GHz frequency band) are allowed to transmit a power of up to 10 W at the antenna input and 55 dBW of EIRP. In order to make it possible to deploy terminals in those frequency bands, different strategies are possible. Some ESA studies are currently addressing the potential of cognitive radio techniques to share the band dynamically via bandwidth segregation depending on the actual use of the channels in proximity of the user terminal. A possible alternative (or also complementary) technique is to implement interference mitigation at antenna level, using adaptive nulling. This can be achieved via different techniques and technologies. After investigating the regulatory constraints applicable in this framework, this activity will study antenna and signal processing techniques for enabling coexistence of terrestrial services and FSS. The focus is on both the forward and return link. However, it is expected that the most critical issues will be faced on the forward link for the interference of terrestrial transmitters onto the reception of the satellite signal. The study focuses on broadband consumer applications. As a consequence, particular attention is to be paid to the impact of the techniques on the terminal price