# synchronization with 2 users

I have $$2$$ users with different distance from the receiver and each user's message is spread with a different waveform. The $$2$$ waveforms are orthogonals.

With a perfect synchronization, I don't have proble to find the messages. But with synchronization I use preambles to get the beginning of the messages. And I cannot find the beginning of the signals because the synchronization is ineffective.

Where is the problem with preamble synchronization?

• "the waveforms are orthogonal": is the preamble orthogonal, too? Also, does orthogonality of the preambles hold even when they are not synchronous? – Marcus Müller Jan 23 at 21:42