Cellular Communications Explained

The problem with multilevel signalling is that it must be possible to distinguish between the different

signalling levels in the presence of outside interference – in particular, noise. A law known as

Shannon’s Law defines the way in which this occurs. It was formulated by Claude Shan non,

a mathematician who helped build the founda tions for the moder n computer, and it is a statement

of information theory that expresses the maximum possible data speed that can be obtained

in a data channel. Shannon’s Law says that the highest obtainable error-fre e data speed is dependent

upon the bandwi dth and the signal-to-noise ratio. It is usually expressed in the form:

C ¼ W log

2

ð1 þ S=NÞ

where C is the channel capacity in bits per second, W is the bandwidth ...