PAGE CONTENTS
Objectives
The aim of this project was to characterize the narrowband and wideband land mobile satellite and railroad radio channel at Ku/Ka band for mobile multimedia services including multipath and rain fading effects.
An experiment simulating satellite links with the transmitter installed in an aircraft has been carried out in greater Linz area (Austria). Various mobile environments have been considered such as rural, urban, suburban, and railroad.
Characteristic model parameters have been determined for narrowband and wideband and these parameters have been included in a simulator software.
Land mobile and railroad environments have become of interest to satellite multimedia system designers. There is a significant potential of users travelling daily in various vehicles. The aim for higher bit rates and the congestion of lower frequencies have driven the designers to seek answers at Ku/Ka bands. The satellite channel in these bands is rather challenging with a multipath and rain fading and low link margin. Ku/Ka band propagation in mobile environments has not been measured extensively and the wideband behaviour at Ka-band has hardly ever been measured before.
The main objective of this activity is the modelling of the narrowband and wideband propagation effects on Ku and Ka bands, based mainly on a measurement campaign:
- Considering various land mobile environments (rural, railroad, urban, suburban, etc.),
- Considering available data and literature,
- Extract narrow and wideband model parameters for the different environments and elevations,
- Integrate these parameters in a simulation software.
Propagation mechanisms: (1) free space attenuation, (2) ground reflection, (3) reflection and scattering from multipath sources, (4) attenuation due rain cells, (5) attenuation due foliage, (6) shadowing due obstacles, (7) diffraction around objects, (8) Doppler shift due movement of the satellite and mobile receiver
Challenges
The main challenges arise from the experiment setup. The key issues were:
- Integration of RF equipment into the aircraft and the measurement van,
- Guaranteeing an exact flight pattern,
- Documentation of flight pattern,
- Data quality,
- Availability of periods of rain/no-rain.
The later issue was the major challenge and risk to the activity, since due to the complexity of the experiment, it was not possible to postpone indefinitely the campaign in the absence of rain, the campaign had to be plan based on statistics and rain predictions. Eventually, the first campaign only recorded very light rain over a few minutes. This unexpected fact was partially mitigated through additional measurements with a beacon receiver and tracking antenna on Hotbird-6 during periods of rain and no rain over the same routes.
Plan
The project main tasks were:
- Review of channel models,
- Identification of requirement for the experiment,
- Planning and design of the experiment and integration of measurement equipment,
- Execution of the Experiment,
- Narrow-and wideband data analysis,
- Model development and testing,
- Simulator software development,
- Additional satellite measurements execution and analysis.
Current Status
Completed.