Scenarios for a Satellite Channel Emulator
- Paper number
IAC-07-B2.I.09
- Author
Dr. Wolfgang Kogler, Graz University of Technology, Austria
- Coauthor
Mr. Michael Schmidt, Joanneum Research, Austria
- Coauthor
Prof. Otto Koudelka, Graz University of Technology, Austria
- Year
2007
- Abstract
Developing satellite equipment starts usually with simulations, followed by prototypes, which may not fulfill the tight requirements of satellite operators, e.g. in terms of spurious emission. But the aim of these early stages is the proof of concepts. Hence a satellite channel emulator can help to test all layers starting from physical up to the access layer. The challenges for the physical layer are normally phase noise and frequency shifts. Both have significant influence on the used algorithms, which must be tested to obtain their performance curves. The access system needs for instance information about the exact round trip time variation of the envisaged satellite. All these test requirements can suitably be met by a channel emulator, where the parameters can be set and varied arbitrarily. The satellite channel emulator described and used for test scenarios in this paper was developed by the authors on a software radio platform. In contrast to existing systems it offers a high degree of flexibility. It can be easily extended for new test scenarios. Another advantage is the comparatively low cost. Currently, the parameters phase noise, AWGN noise level, signal attenuation, Doppler shift, and round-trip-time can be set and varied with fine granularity. The emulator provides an intuitive graphical user interface, which is based on JAVA and therefore perfect for remote control purposes. Due to the very accurate execution of the channel parameter sets, several emulators can be used in parallel to execute the parameter lists simultaneously and synchronized. This offers the opportunity to simulate a satellite network. Real rain attenuation measurement data from Ku- and Ka-band channels can be stored in the system which uses these data to simulate the fading channel. This is advantageous for carrying out long-term tests of adaptive transmission schemes and fade mitigation algorithms. The main application of this emulator has been the development and test of a meshed MF-TDMA satellite network with rigid phase noise requirements. The advantage of the emulator is that the influence of the outdoor units can be simulated as well using the phase noise and frequency stability specifications of the target system. Additionally long-term tests using a bandwidth of up to 36 MHz can be conducted, which saves a lot of money compared to tests on the space segment. Also failure simulations of terminals (e.g. drifting oscillators) can be carried out. For projects focused on mobile satellite terminals this emulator can provide the proper channel with high Doppler-shift and fading. Also for debugging reasons each scenario can repeated several times in a reproducible manner, and even stopped at critical points for further investigations. This paper focuses on applications of this satellite channel emulator especially for optimizing the synchronization algorithms in a digital burst modem. Several test scenarios which have been and may be possibly performed in the future (e.g. fade mitigation investigations) will be treated in the paper.
- Abstract document
- Manuscript document
IAC-07-B2.I.09.pdf (🔒 authorized access only).
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