Question

How can we prevent the mixing up of signals

Answer 1

Mixing of different signals during propagation is a real concern in communication systems and this phenomena is referred to as signal interference. It involves the interference of one or more signals with the original desired signal and results in a signal wave which can be deviated from its original waveform and rendered useless at the receiving end. Now, the interference occurs according to the laws of wave superimposition and thus the nature of resultant wave depends upon the type of interference and thus the phases interacting. 

Interference thus needs to be minimized and possibly zeroed as it produces undesirable effects on the original signal. This can be done by using high frequency signal for communication in a process known as modulation. Now, we can also reduce interference by allotting different frequency bands (regions) to different users thus ensuring isolation.