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R52n variable performance over frequency

Posted: Thu Dec 10, 2009 5:17 pm
by zreno
Hi,

I'm running R52ns on RB411AH boards and I've done some outdoor tests which show that throughput drops with frequency.

I've been testing at 5500-5700 frequency band at 600m (SISO and 2x2 MIMO) and 2.3 km (SISO). I'm getting following throughputs (UDP, traffic):

600m - SISO
* 113 Mbps at 5500 GHz
* 103 Mbps at 5540 GHz
* 99 Mbps at 5580 GHz
* 60-90 Mbps at 5620 GHz
* 90 Mbps at 5660 GHz
* 90 Mbps at 5700 GHz

600m - MIMO
* 186 Mbps at 5500 GHz
* 156 Mbps at 5540 GHz
* 147 Mbps at 5580 GHz
* 125 Mbps at 5620 GHz
* 116 Mbps at 5660 GHz
* 87 Mbps at 5700 GHz

2.4 km - SISO
* 30,5 Mbps at 5500 GHz
* 19 Mbps at 5540 GHz
* 19 Mbps at 5580 GHz
* 14 Mbps at 5620 GHz
* 13 Mbps at 5660 GHz
* 11 Mbps at 5700 GHz

I did some RF site survey with WiSpy and haven't noticed anything above the noise level. Testing location is a couple km from the urban area, so interference shouldn't be a problem.

Didn't anybody else experience throughput drops with frequency and why does it happen?

Cheers
Zreno

Re: R52n variable performance over frequency

Posted: Thu Dec 10, 2009 9:15 pm
by astounding
It could be your antenna(s) or some other component in the RF chain performs best at one frequency and drops off the further from that frequency you get. Any antenna even rated for a set of frequency bands will have a peak optimum and drop off a bit from there.

Just speculation on my part...

Aaron out.