The bandwidth efficiency, or spectral efficiency, is an
important figure of communication systems.
• It is an insufficient and valuable assessment, so designers try to pack
as many bits/s in a certain amount of bandwidth as possible.
This increases the complexity of the system and also the
required SNR in order to correctly decode the received
signal.
That is why many systems provide greater capacity at
shorter distances where the signal power is greater.
Since capacity in bits/s is proportional to bandwidth in Hz,
it is common to speak of “bandwidth” in bits/s.