Physical layer design of a robust low-power low-complexity optical wireless sensor system with angular diversity for metal-enclosed environments

by Trullinger, Von

The desire to apply short-range wireless communication systems to telemetry sensor

networks in a metal-enclosed chamber has prompted this study. This thesis will discuss

the design of an infrared (IR) communication system for a wireless low-power, low-data-

rate sensor network in a metal enclosure. This design requires an in-depth understanding

of the environment and how IR will propagate in it. The metal enclosure o®ers the

advantage of little background (ambient) lighting noise, which is the main noise source

in IR communication. Also, due to the small dimensions of this enclosure, the non-line-of-

sight (NLOS) communication will take advantage of the re°ected paths o® the walls. To

improve system performance in this di®use NLOS communication environment, angular

diversity will be employed and tested. It will be shown that these di®use re°ections are

an advantage at low data rates (< 1Mbps), but then become a hindrance at higher data

rates (> 10Mbps) due to inter-symbol interference (ISI) caused by channel excess delay.

All measurement results, including bit error rate (BER) versus transmitted power, will

be presented.