New Directions in Propagation Research
Propagation research is a very old discipline. Over the years the frequencies
of interest have move up, currently addressing the bands above 3 GHz, particularly
40 or 60 GHz. Infrared
optical propagation is also being studied. Not only the pathloss,
but also the (microscopic) fading
and dispersion effects are relevant.
interview with Daniel Davarsilvatham covers trends in propagation research.
Dr Davarsilvatham is director of the Propagation and Planning Wireless Systems
Research Lab at Bellcore.
Propagation research is conducted for various reasons.
- Precise understanding of the channel allows engineers to design
better systems that can cope with multipath fading. Path loss, delay
spreads, scatter plots etc. all affect system performance. If such
systems are well designed according to accurate and reliable models,
further measurements make no sense.
- Planning and deployment, however, do require measurements.
Delay spread, Channel
- Once a system is designed and deployed, the service provision aspect
comes in. For small startup operators, it is of critical business
importance that their sales department can judge fairly reliably whether
or not a certain location can be served by their wireless network.
Unsuccessful attempts can break the economics of such companies.
The last mile.
Some scientists believe that frequency assignment
for indoor systems can be done in future, relying on accurate models
using high resolution data bases. More realistically, self-organizing
systems will be deployed, adopting a set of "rules of thumb"
for technicians in the field.
A challenging interesting new direction of propagation
research is initiated by smart antennas and Space Division Multiple
Access. Expertise in propagation, antennas and signal processing is
indoor, smart antennas.