Firmware 2.2.1 large ping A5c and C5


We start implementation of the Mimosa system, replacing old Ubnt devices. A big plus, for Mimosa, for a large packet performance and high throughput. Minus is that the system is not immune to interferences. We also make tests together with Ubnt and Mimosa devices on the same channel. Ubnt worked properly, when Mimosa lots packages and sometimes throw out subscribers. On different channels both works well, but Mimosa has 4ms latency. We are accustomed to 1ms in ac mode.
After uploading the firmware 2.2.1 has increased to 20 ms and sometimes jumps to 40. This GPS support with such latency is a failure,
Therefore I have a question, could you make the option to turn off the GPS and have lower latency?
I do not mean the wifi mode, because we have a limit as to support additional channels.




The reason that the latency is increased is because of the TDMA window (8ms I believe). Since the radios are synced via TDMA, that adds latency to sync up the timing. If you turn off GPS, you lose the frequency re-use ability. Much like other vendors, the sacrifice for sync is higher latency. There isn’t a mode that is not TDMA but not WiFi.



The ubnt AC is 1ms




The UBNT doesn’t support TDMA mode, so it must be connected via WiFi mode, which will be sub 5ms.


Hi, on Cambium gear ePMP2000 you can choose differents timings on GPS sync, I dont now if is better or not, but you have the option.


UBNT does support TDMA mode (Branded airMax) with a flexible frame size, but it does not support TDMA based on GPS timing right now. If I am not mistaken, the new AC hardware is only TDMA and does not even have a WiFi mode.


The larger the frame size, the more efficient the use of air time. As with most things, there has to be some balance. The larger frame size will yield higher latency and higher maximum throughput. The smaller frame size will yield lower latency and lower maximum throughput.

I imagine Mimosa started with an 8ms frame size with a 50/50 split as a good option to get GPS sync working correctly, and will add other frame sizes and traffic splits in the future, but I could be wrong.


I agree with you about a “balance”, but like always not all is fine for everbody . So i prefer the option to try with differents options and see what happend. For example, now only I have 2 C5 in testing mode on my A5c, so what happend if I play on my PC? I have between 15-20 ms more of ping than before,( 8 ms SRS timeframe ) and also i feel when the A5c is moving from MCS7-6-7-8, etc. For that should be an option as well to fix the max MCS, not always jumping. You can see on my another post that my parameters are very good to have MSC7 even 8, but most of the time is on 7 or go down to 6, and belive me playing FPS games for a long time ( over 20 years ).

I now that A5c is constantly checking all those parameters due to not all the time you have same conditions, noise, signal, etc. but as before in my situation all parameters seems OK to have all the time MCS7. In resume, maybe is a good idea to limit MCS6 ( lossing very small performance ) but taking more stable conecction.