RSSI lower level starting from firmware 3.0

Products ePMP
1

Hello there,

we're noticing a RSSI level decrease (about 3-4 dB) starting from 3.0 firmware using both ePMP1000 and Force180 or 200.

Is there any reason of this change?

Both RSSI channel 0 and 1 are unchanged from release 2.6.2.1 and 3.0, what is changing is the combined RSSI level.

No one noticed this problem?

In long distance (about 15 km or more) it seems this impact over performance instead over shorter links, this doesn't give us any problems.

I attach 2 screenshots of 2.6.2.1 and 3.0 RSSI different levels.

force180 2-6-2-1.png
force180 2-6-2-1.png1366×768 45.1 KB

force180 3-0.png
force180 3-0.png1366×768 47.2 KB

Best regards,

Paolo

2

Hi Paolo,

Thank you for sharing your observation.
I would be really grateful if you could compare SNR for 3.0 and 2.6.2.1.

Please also make sure your link is not affected by known issue in 3.0 Release:
http://community.cambiumnetworks.com/t5/ePMP-2000-and-1000/Release-3-0-EIRP-defect/m-p/58226#U58226

Do you use ePTP or TDD mode?

Thank you.

3

Thank you Fedor for your reply.

SNR is unchanged on different firmware releases...

I've also tried the last 3.0.1 noticing no changes from 3.0, except from some light bug fixes.

We work for a wireless provider in Italy and we use SM client devices all in TDD mode. Anyway I've noticed this RSSI problem also over ePTP Master/Slave link that we use from one tower to another on light weighted data links.

Have a nice day! :)

Best regards,

Paolo

4

As an observation...   both screen shots do show the exact same chain signals:

CH0: -62 dBm, CH1: -63 dBm

If you add a -62 and a -63, that should result in a combined signal of -59.46  dBm

So... perhaps the real signals are actually the same, and perhaps V3 is doing the math slightly more correctly to arrive at that -60 combined signal, and perhaps 2.6.2.1 was misreporting the -56 somehow - maybe?

1 Like
5

I do agree with you that ch0 and ch1 in both firmware releases shows the same value.

So in the last few years, they always showed up a wrong combined RSSI value??? :)

We've always got the same RSSI value, starting from 2.4.3 ePMP firmware release... till 2.6.2.1.

This is weird and not documented in 3.0 firmware release!

I post this since we're using a strict RSSI entry thresold on our SM (-75 dB) and starting from 3.0 firmware some upgraded SM won't connect to the AP since they got more than -75 dB RSSI.

That's a problem for us...

6

Hi all,

In 3.0 were delivered improvements for Combined RSSI calculation.

Today you can see most correct value for combined RSSI.

We did not expect that fix can affect anyone.
Sorry for inconveniences.


Thank you.

2 Likes
7

Hi all,

it's been some weeks that we're trying old and new firmware (to 3.0.1 stable version).

We've noticed that in one far link (17 km) between SM and AP where with 2.6.2.1 fw we had -67 RSSI combined signal and 23 dB SNR, then with 3.0.1 we get -72 RSSI level and 19 dB SNR... obviously speed decrease a lot... from 52 Mbps in download with 2.6.2.1 to 37 Mbps with 3.0.1!!

Instead with perfect LOS condition from SM to AP short link (about 7 km) but with huge RF interferences, we noticed that 3.0.1 is more reliable and we get about 15% more throughput in speed test.

Best regards,

Paolo

8

Hi,

I've sent you e-mail.

I'd like to take a look on your link for issue investigation.

Thank you.