Demands by the communications industry for greater and greater bandwidth push the capability of conventional wireless
technology. Part of the Radio Spectrum that is suitable for mobility is very limited. Higher frequency waves above 30
GHz tend to travel only a few miles or less and generally do not penetrate solid materials very well. This offers a
sustainable solution for the current Spectrum Crunch in the lower microwave bands. One mission of this paper is to
demonstrate practical and usable networks that can select a self-limiting link distance, allowing spectrum reuse. The
motivation for operators of such bands to actually choose to self-limit is that by doing so, they improve the signal-tonoise
against competing users at a lower cost than trying to overcome interference. These characteristics of wave
propagation are not necessarily disadvantageous as they enable more densely packed communications links. Thus, high
frequencies can provide very efficient spectrum utilization through “selective spectrum reuse”, and naturally increase
the security of transmissions.
Optical systems and networks offer a far greater bandwidth. This means new devices and systems have to be developed.
Semiconductor Light Emitting Diode (LED) is considered to be the future primary lighting source for buildings,
automobiles and aircrafts. LED provides higher energy efficiency compared to incandescent and fluorescent light
sources and it will play a major role in the global reduction of carbon dioxide emissions, as a consequence of the
significant energy savings. Lasers are also under investigation for similar applications. These core devices have the
potential to revolutionize how we use light, including not only for illumination, but as well; for communications,
sensing, navigation, positioning, surveillance, and imaging.