# multi-user communication

For a multi-user communication, I do many signals $$s_i(t)$$ with $$i \in \{1,...,N \}$$, $$N$$ the user number. The bandwith for each $$s_i(t)$$ is the same.

But when I do the Fourier transform of $$s_i(t)$$, $$FT(s_i(t))=S_i(\nu)$$. The $$S_i(\nu)$$ are not centered in the same place. For example $$S_1(\nu)$$ is centered at $$1$$ Hz and $$S_3(\nu)$$ is centered at $$10$$ Hz.

Here is my question: In digital communication, can we transmit signals simultaneously (multi-user communication) whose fourier transforms are not centered at the same point?