How come in SU-MIMO one TTI is shared by more than one users?

RAN
,
1

Hello Experts!
I read several articles and papers regarding SU-MIMO but still I am still confused.
In some paper, it is written that in SU-SISO, base station communicates with a single user, then how come in SU-MIMO, one TTI is shared by more than one users?

2

Because MU-MIMO means different users are scheduled in same TTI using same symbols and same PRBs just different spatial location.
Anything else is considered SU-MIMO.

3

SU-MIMO is your old traditional MIMO.
No users share same TTI.
This is your single user doing 2x1, 2x2, 4x2, 4x4.

4

So you mean all TM1 to TM4 schedules only one user per TTI?

5

You do FDM per TTI, meaning, at a particular TTI you will divide the spectrum among the scheduled UEs.
You only have a single user per PRB, while in MU-MIMO you reutilize the PRBs across UEs which as separated enough.
Separated geographically.

6

Normally eg in a 5 MHz LTE, there are 25 PRB and in 1TTI eNB schedules 50 PRBs in SU-MIMO.
So in case of MU-MIMO, whether the eNB will schedule for more than 50 PRBs?

Which means cell throughput will increase further?

7

Only 25PRBs for 5MHz.

At each TTI, the eNB will divide 25PRBs for the amount of scheduled UEs in SU-MIMO without any reuse.

If there are UEs geographically isolated enough, MU-MIMO can come to picture then the eNB can reuse the same PRBs for those UEs which were geographically isolated from one of the other. This will result in an increase on cell throughput.