OPTIPUSH

Motivation and background

The demand for bandwidth in satellite communications increases year after year and is limited by the available spectra as well as the performance limits of satellites. Optical communications can take the strain off the ground here and is being used to an increasing extent in the satellite-to-satellite as well as satellite-to-ground communication.

Optical transmitters and receivers are lighter, smaller and require less power than traditional radio transmission techniques. The laser beams are typically modulated with unipolar NRZ-OOK (Non-Return-to-Zero, On-Off Keying) signals that require theoretically unlimited bandwidth and also do not make optimal use of the energy applied.

This fact results in a not efficient synchronization in the receiver and to an operational point away from the optimum. Bandwidth-limited transmission helps both to use more carriers in the spectrum and to obtain the same transmission capacity with less energy.

Innovation potential

In this project, we propose to use analysis, simulation and an optical test bed to verify whether a bandwidth-limited pulse uses less energy than a rectangular pulse at the same data rate. In this context, it is not only the transmission that is important, but also new Synchronization algorithms, which allow an efficient demodulation and decoding of the signal and therefore an operational point close to the channel capacity.

This would represent a very big step in optical communications because the flight hardware would use less power resources than conventional transmissions and less bandwidth would be used. Multi-carrier systems are thus feasible more efficiently. We will also investigate which conditions are necessary for suitable pulse shapes and we will develop powerful algorithms for parameter estimation and synchronization in optical satellite receivers.

In addition, with the controlled amplitude intensities, a selection of modulation types (PAM) is given, which can then be used in further respects for adaptive coding and modulation methods (ACM).

Expected Results

With the analysis, simulation and verification in the test bed, we will check whether the algorithms developed can be used for the satellite-to-satellite and satellite-to-ground communication. We will also investigate how much the spectral efficiency of optical satellite links can be increased by means of adaptive coding and modulation (ACM) methods.

In the event of a successful verification, the aim is to protect the algorithms and the principle of band-limited optical transmission with a patent and offer them to the standardization bodies of ESA (CCSDS) as well as to industry.

Coordinator

JOANNEUM RESEARCH Forschungsgesellschaft mbH

Project partner

TU Graz

JOANNEUM RESEARCH Forschungsgesellschaft mbH
DI. Michael Schmidt
Steyrergasse 17
A-8010 Graz