Migration to A5c


Today we moved 74 customers to the new Mimosa A5c, all the CPE are with very good signal and we follow the configuration instructions, and the A5c does not manage to pass more than 25Mbps.

A single Rºck@t with 50 Customers passes more than 35Mbps.

After seeing that we have the very limited spectrum:cry: and functions disabled we hope they can help us, as we buy more than 10 A5c and plan to buy more than 20 in the next quarter.

Please, you can help us at least need to test Beta versions of the next firmware, which told us that you will have the preview completely released and functions as basic as the security by Radius that we need to use in INTEROP while we migrate.

Today we spoke with the support, very kind and willing to help us, but we only got a promise that I would try to talk to the development team to see how to solve the big problems we have.


Hi Cesar_Javier, when you talk about 30 Mbps. are you talking to the CPEs customer? Or you talk about performance of A5c in maximum capacity ?

What are the speed plans that you offfer to your customers and if you do a speed test how much can they receive.

Please post a screen captures with more inforamation, pick the tab where is PHY stats ( WIRELESS -> Clients-> PHY stats ) and post the image.



40 CPE of which we moved, were in a rocket with an average consumption of 35Mbps

César Javier F. RoblesZona Comercial La Punta – Mzana 130 Local 10 - San Luis
Tel./Fax: (54) 0266-4453540/4420710
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Hi Cesar,

Moving 74 clients into 20 MHz of spectrum is certainly a challenge, especially when many of them have low or negative SNR like we can see on the cloud. It doesn’t leave much capacity to be divided among clients considering contention overhead in WiFi Interop (CSMA). This is one of the reasons why we designed Mimosa C5s with SRS (TDMA).

Several of the clients have much lower RSSI than the others (-70 to -80 dBm), and that is likely reducing SNR at the A5. AGC at the A5 works best when clients are all above -75 dBm or so.

We recommend that you begin by addressing the clients with negative and low SNR as a first step. There is little that can be done without first addressing the poor RF conditions that they cause for other better-performing clients.

After that, adjust AGC threshold upward to improve SNR at the A5.


Iam read these¨: http://ap.help.mimosa.co/srs-protocol-comparison

INTEROP: Max Client Count 100
Authentication Modes Open, PSK, Enterprise(dont work)

and these??
Feature WiFi Interop SRS Frequency Support
(Restricted by country of operation) 5170-5835 MHz 4900-6200 MHz

there is no way to migrate large number of CPE in these condition


Hi Cesar,

Our A5 and C5 products were designed to work together as a system to deliver high performance to each connected client, rather than to support high client counts at low connection rates.

The performance you are seeing is because of low or negative SNR at several of the 74 non-Mimosa clients, and because they are using only 20 MHz channel width. I see that you have been chatting with several of our Support agents, and that they have described the troubleshooting steps.

If the Enterprise authentication mode is not working for you, I would suggest that the configuration and requirements be addressed privately with the Support team so that your network security details are not shared here with the public.

Support for 4900-6200 MHz is currently only available in SRS, but we plan to allow the wider range with CSMA in an upcoming firmware release. The wider range was not included in WiFi Interop mode because Wi-Fi compliant devices would not be able to connect to channels that are not defined for Wi-Fi use: http://ap.help.mimosa.co/ap-faq-supported-frequencies


We run one A5-14 with 60 Mikrotik clients in interop mode. I can push the A5 to a 100Mbps throughput.
This is a 40Mhz channel though but in a heavy uses spectrum.
I tried once a 80Mhz channel and could push the A5 even higher to 150+Mbps TTL client througput.

The limit in our case is the fact with 60 connected clients (I run the Mikrotik bandwidt test from 6 or 8 clients at the same time, but during this the rest of the clients are still using their connections.) airtime is limited especial when considered the spectrum is ‘dirty’

Since clients are not allowed to get more then 30 Mbps and this is very rarely seen to be used by clients (only downloads need this, most other internet usage hardly produces more then 10 Mbps per client) we see hardly ever more then 50 Mbps aggregated from these 60 clients over the AP.

Some things are important though:

  • The use of RTS/CTS is compulsory! One or two units not using this ALWAYS (so set accordingly with the lowest threshold possible = always on) it ruins the network.
  • Set the distances of each client in the client settings of AP. If not you’ll have regular 'network storms?
  • I’d like to have all clients coming in at the AP with -50 to -55dB. If the signals are lower the connection rates drop and it takes only one or two ‘slow’ clients to ruing the network. You need to upgrade client antennas to get to this signals.
  • In 20Mhz band you even under the best spectral circumstances and high s/n ratios (30 or more) you would get 50-60 Mbps tcp traffic to a client max. I see some of your clients having only MCS 6/7 meaning only 20 Mbps tcp throughput maximal! If these clients are using your network they consume so much time of AP the rest is also hammered.
  • The AGM has to be set to -60 or -65 to eliminate signals from close ranges other AP’s. Meaning your clients need at least to be 5dB better then this (for weather fading etc. “fade margine”)
  • Also try to get all associated CPE’s to work in same sort of power level at the AP (adjust output of the client to set them all in a 5 or 10dB wide range.) Yet again, if some units have much lower signal at the AP then the others, these ‘poor’ ones are molesting your network…
  • Your clients are presumably all ‘n’ type of radio’s. The Mimosa is ‘ac’ and although I’ve been reading that ubnt’s ‘ac’ is not as good as it could be (like Mikrotik’s. But yet again. both atheros) the difference in using ‘ac’ CPE’s is noticably better then only ‘n’ clients. You DO get the higher MCS rates, given the signals are good.

The Mimosa is a very powerful ‘ac’ AP. Its wireless has some features (AGM) that helps eliminating high noise levels.
The used chipset/firmware is capable to use one chain out of 2 even if the signal differences are more then 3dB (Mikrotiks tend to fall back to ‘one chain only’ working mode if the 2nd chain is more then 3dB worse that the good one. I don’t know about ubnt but since the chipsets are the same I’d presume its the same. I saw the Mimosa using 2 chains even if the difference was 6dB!)

But after all, the capacity of the network comes from the usage of the spectrum. You need higher S/N ratio to use the Mimosa to its full extend and use higher channel bandwidth to get better use of the spectrum/time available to the AP.

Last, but not completely least; The A5c is probably working in standard regulatory domain and probably only transmitting with 23-24dBm of power. I am almost sure your previous Ubiquity radio was just set to maximum? 30dBm?
If that was the case, then obviously there was twice as much signal delivered to the client, thus higher MCS rates and higher throughput.