8 research outputs found
A T-DMB navigation system for seamless positioning in both indoor and outdoor environments
Spectral density constraints on wireless communication
Environmental exposure to man-made electromagnetic field (EMF) has been rising as modern technologies
have grown and changed in social behaviour have generated more synthetic sources. For the safety of human
health, EMF levels need to be regulated. The level of EMF should be well below levels where there might be
harm, hence we do not expect to see any health effects at these levels. Current regulations fail to place a strict
limit on EMF in situations where multiple nearby devices transmit simultaneously. The way these regulations
are expressed needs great care because it will have an effect on the design of wireless communication systems.
In this paper, it is argued that transmitted power constraints on wireless communication devices should be
expressed in a different way, namely that devices should limit the EMF spectral density that they generate to
the difference between the maximum allowed, by the standard, and the amount currently present, as measured
by the device, in the spectral region where it is active. Note that the limit on EMF should be expressed in
terms of its EMF spectral density rather than as a total EMF over each of a series of separate bands. If all
devices limit their own EMF spectral density, in the spectral region where they are active, in such a way that
total EMF spectral density is below the regulated limit in that region, then it is certain that the aggregate EMF
spectral density will be below the regulated limit at all frequencies