Estimation algorithms for Multi-User MIMO

I am interested in a question how to estimate a channel/symbol in a multi-user system. In the case of a single-user, it can used ZF/ pilot estimation/ MS/ LS algorithms. Do we have a difference in using these algorithms if we consider a multi-user system?

In the multi-user case, one signal is transmitted via some number of channels ( = number of users). As a result of the estimations algorithms, we get some number of detected signals and channel estimates.

If there is no difference in estimation algorithms, why are algorithms for multi-user studied as a separate issue?

in case of estimation of the transmit data ( e.g ZF), there are different channel, it means ZF gives different estimates of the transmit data, doesn't?

• yes, every user needs to estimate their own channel, as you've noticed. Not quite sure what you're asking here? Jul 23, 2020 at 14:25
• @MarcusMüller For example, for single user case, I can use Algorithm A for channel estimation. Can I use the same algorithm for case multi user? Should be Alg A rewrtiten for case with multi user? Jul 31, 2020 at 6:57
• Why should it have to be rewritten? It still does the same thing, under the same constraints. Things get interesting when your users see the same (or related) channels and can exchange information about these, but this is not the case for you: There's as many different channels as there is users in your case (which is the usual case for e.g. cellular networks). So, not quite sure why you think things should change. Could you edit your question to explain that? Jul 31, 2020 at 7:01
• @MarcusMüller I was thinking, if the multi-user system has more than one channel ( set of the receive antennas), the estimation algorithm will differ from the algorithm of a single user system. So.... there is no different if it is multi-user or single-user for estimation algorithms, Is that it, Aug 19, 2020 at 7:19
• Again, no, why do you think it would differ? that's just an unfounded claim, the constraints are the same. Aug 19, 2020 at 12:54