Why must waveforms match the transmitting channel characteristics?

[zakee.fancy]

why waveforms should be compatible with transmitting channel?
What if i send a random wave without having much information about it?

 

[berkeman]

why waveforms should be compatible with transmitting channel?
What if i send a random wave without having much information about it?

Could you please give more information about your question, and preferably a few examples about the "channels" that you are asking about.

Without knowing more, I would offer that some transmission means have cutoff frequencies. So you may be limited in what frequencies you use. Coax cable is lossy at higher frequencies for example. And waveguides do not pass lower frequency EM signals...