1 A5-360-18 scale to 4 A5-90


#1

Hi Mimosa Team,

Very excited to get your PtMP products out in the field for testing.

A question we have regarding the A5-360s:

Our understanding when the A5-360 broadcasts and uses the benefit of mu-mimo, the A5-360 decides which quadrant to use when communicating with cpes based on spacial location. We are assuming with the above in mind an operator can scale a mimosa PtMP network easily and cost effectively by deploying a A5-360 first and then adding A5-90s to which ever quadrant is most dense first as needed until you have 4 A5-90s in the air essentially allowing you to retire the A5-360 for future expansion. Is that a correct way of thinking or will we experience a problem trying to scale this way? This also assumes the operator is using correct sync planning with the A5-90s and A5-360

The only problem I can for see with that approach is if the A5-360 still broadcasts on quadrants that have no clients on it. The clients connected to the A5-90 would hear the A5-360 as noise if they were gps sync’d which would be very problematic. If the quadrant of the A5-360 that the A5-90 is now covering doesn’t broadcast when it has no clients connected to it then I would imagine this would work. Maybe a Mimosan can clarify. If that is not how the A5-360 operates now, is there a way to implement it? It would be a huge Mimosa specific benefit to operators.

Imagine another manufacturers setup and scalability:

1- You start with an Omni to get your POP started
2- Load up the omni with clients
3- replace omni when overloaded with at least 3 120deg sectors all in one go. You cant sync the omni with any sectors since clients connected to the sectors would hear the omni as noise. You either need to replace the omni with 3 sectors all in one go or hope you have spectrum to run 3 sectors and an omni unsynced. And dont forget guard channels. If you replaced the omni you would go from theoretically Y amount of clients supplied by the omni to Y * 3. Thats a large amount of capacity to add and a large expense all in one go.

Let me know your thoughts guys and thanks for listening!
Pierre

Note- I posted this also in the A5 General Discussion 2 weeks ago and no response so I figured I should make my own topic


#2

Look forward to hearing from the engineers on this one as its something we’re also interested in using as a strategy.


#3

Actually, we are just waiting for Mimosa to bring out the PtMP software!
We will then swap out the UBNT radios with B5c’s and use the UBNT sectors that we already have up.


#4

Hey guys,

Thanks for the interest in my post!

Jaime answered me the other day in my original post under the A5 General Discussion. His response was:

Hi Pierre, very interesting question. So typically, you need to be at 180 degrees to collocate and sync reuse the same channel. So it’ll be pretty tough to not get receive side interference from clients off angle on the adjacent 90 degree sides.

There is a possibility that the chosen panel pair to reach a client on the 360 would be the one that you replaced the 90 with, obviously the patterns overlap so that we make sure we get 2 streams to every client.

Now if you flip to using a different channel on the 90, you’re good. To do 4 90’s on the same site, you’d need 2 separate channels anyways, so just plan for it and you’d be good!

So my understanding is that yes you could do that but would likely experience a negative performance hit if some of the fringe clients on the A5-90 see the A5-360’s adjacent quadrants and vice-versa which depends on how your client base is dispersed. Also there is the possibility of those fringe clients on the A5-360’s 3 used quadrants to connect to the 4th unintended quadrant that the A5-90 is serving because there is an overlap of all the quadrants. A better way to do it that Jaime describes is to use 2 channels when the first A5-90 is added. Then proceed to continue just using 2 channels as you add more A5-90s. Here is an example of a scale to 4 A5-90s from 1 A5-360 that I’ve thought of:

Phase 1
A5-360 uses channel A and syncs with nothing

Phase 2
A5-360 uses channel A and syncs with nothing
1st A5-90 added using channel B and syncs with nothing

Phase 3
A5-360 uses channel A and syncs with nothing
1st A5-90 uses channel B and syncs with 2nd A5-90
2nd A5-90 added using channel B and syncs with 1st A5-90 180deg apart (behind 1st A5-90)

Phase 4 (option 1)
remove A5-360
1st A5-90 uses channel B and syncs with 2nd A5-90
2nd A5-90 uses channel B and syncs with 1st A5-90
3rd A5-90 added using channel A and syncs with 4th A5-90
4th A5-90 added using channel A and syncs with 3rd A5-90
site is complete

You could add another phase in and continue to add only 1 sector at a time instead of adding the 3rd and 4th sector at the same time like described above. See below:

Phase 4 (option 2 if not using option 1)
A5-360 uses channel A and syncs with 3rd A5-90
NOTE (you will lose mu-mimo benefit on the A5-360 at this point since only 1 quadrant will have clients on it and may also experience a negative performance hit if clients on A5-360’s last remaining quadrant are on the fringe of that quadrant and attempt to connect to an unintended adjacent quadrant creating interference to the 3rd A5-90 in the sync group using channel A)
1st A5-90 uses channel B and syncs with 2nd A5-90
2nd A5-90 uses channel B and syncs with 1st A5-90
3rd A5-90 added using channel A and syncs with A5-360

Phase 5 (continue’d from Phase 4 option 2)
Remove A5-360 and install 4th A5-90 which syncs with the 3rd A5-90 using channel A
site complete

So the short of that is it is possible but how it works depends on how your clients are dispersed. I would not recommend using the method that leads to phase 5 and just add the 3rd and 4th sector at the same time in phase 4 option 1. If you have a loaded omni and 2 sectors already you probably have your foot in the door in that market and can afford the 3rd and 4th sector to be installed at the same time.

My 2 cents!

Pierre