Firmware:
As for firmware upgrades, I haven’t noticed any difference in wireless performance. What you call firmware here, to my understanding is a RouterBOOT bootloader, which has nothing to do with device performance after it boots to OS. But MT staff could verify if it has any effect or not.
To my understanding Firmware (/sys rout ) is 'drivers'. At least that is what has been xplained to me once by some MT guy. It is needed to have all kinds of hardware working with the software. And in writing new drivers the older drivers get updated too. That always has been my understanding but correct me if I am wrong.
Older vs newer devices:
I’m not sure, but antenna design is pretty much the same for 5HnD vs Lite5? So newer chipset has definitely got some improvements that affect performance. Regarding CPU - everyone keeps telling that faster CPU yelds better performance. While that might be true for AP, but for CPE 400MHz vs 600MHz wouldn’t make signifcant difference, especially when CPU utilization stays low during even heavy data transfers. Correct me if I’m wrong.
Well, If I upload a file (for instance a new upgrade ROS) to a new 720Mhz unit or to a 400Mhz device, even if they have the same conn. rate and signal, in the 720Mhz it goes way faster. And this is only a big package of data that has to be written in memory. I am not talking the actual upgrade process. (Or is ti because the newer memory is much faster?)
Also; if you run a bandwidth test 'over' and old 400Mhz device or a new 720Mhz device, the latter shows less cpu usage.
Which would make sense, the radio continuously has to make decisions on the conn. rate and choose 'up' or 'down' one, has to check the checksum of the packages so it was transported 'intact' and ask for a 'resend' if corrupted, receive and proces tdma time stamps and send/receive windows and encrypt or decrypt the data that is send over the wireless link. That's all work to be done each data frame again, over and over.
And since we have the CPE perform the NAT routing it also needs to store all connections ('tracking¡) and replaces src and dst IP all the time for all packages.
For all this work the CPU speed is a factor of importance. 'The faster, the better'.
Data over the wire or wireless is transported with the speed of light. The reason our 'real' data is slowed down considerably compared to the speed of light is the fact it is processed by repeaters, by routers, by radio's etc. So the faster they all work, the less delays we have.
Could this not be the reason 'old' units slow down a NV2 P2MP network if it is test to the max? Would be nice it the MT wizz kids would have some info to share....
Short GI vs Long GI:
Interesting theory there. I’ve never noticed better performance with longer guard intervals. But this actually makes sense, because longer GI should be less prone to interference just as lower modulations are. ROS itself switches to long GI when RF environment gets worse. But I don’t know if manually pinning GI is better than allowing frequent jumping between Long vs. Short.
At least the CPU doesn't have to make that decision anymore. Each and every time GI is changed traffic is halted for a split (m)second. If my modulation rate is high enough for the capacity that is needed, it gives me better CCQ and thus lower latency.
Nevertheless, I’ll continue replacing old units whatever the reason of this performance improvement is (aging, chipset features, antenna design, etc). In my opinion MT CPEs are quite good and quality units. All we need now is some magic at AP side, which is surely possible as other vendors clearly demonstrated, even with MT CPEs..
I can nothing more then to fully agree on this. Apart maybe from the noise shielding* (which in my opinion is better if the transceiver would be placed in the focus of a metal sphere (like ubnt does) these little SXT's, SXT-sq's, SEXTANT's, LHG's and now the DISC's are nice little units that with its versatile ROS can be fine tuned to levels other makers can only dream of. And for a very competitive price!
*Shielding. Once this has been heavily debated here in this forum. Soon after they came with the SXT-SA-ac models that where coated on the inside with anti shielding material. Imho this should be done on ALL SXT's (and other CPE units)
I never understood why they only choose to do the AP's units. If there are interference issues this is prone to be from the tower that has more AP's This usually is within the operator's own capacity to control (relocating units of channels).
CPE's on the other end are out in the field where sometime signals from competitors do more harm. It is not always an option to change a working channel for a P2MP setup only because one or some CPE's are hammered by some competitors AP......I would rather have better shielding here. (Or any other way of noise rejection.)
Mimosa's C5's for instance are shielded and perform so much better in the same area where we previously had SXT's. S/N levels are just higher...
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Rudy R. Puister
WISP operator based on MT routerboard & ROS.