# Signal bandwidth and channel bandwidth

I have a channel bandwidth $$B_c$$ and a signal bandwidth $$B_s$$ with $$B_s<. What is the problem when the signal bandwidth is smaller than the channel bandwidth? For example, my channel bandwidth is $$B_c=20$$ kHz and my signal bandwidth is $$B_s = 10$$ Hz.

• (there's a lot of context missing here: Why do you think it is a problem? Why should it?) – Marcus Müller Jul 23 at 14:24
• There is no problem – Hilmar Jul 23 at 18:39

No problem at all if $$B_s \ll B_c$$.
However, $$B_s = 10\text{Hz}$$ is considerably small that makes synchronization very difficult especially for low-cost receivers.
For example, Sigfox Ultra Narrow Band uses $$10\text{Hz}$$ bandwidth (are you studying the standard?) that requires precise but expensive oscillators like TCXO. Even with that, there must be random access enhancement to deal with the frequency imprecision.