I'm having a nightmare when trying to use two cards in one direction.
The scheme is simple
10 km line of sight
- wlan1A (connected with wlan1A from Router1)
- wlan2B (connected with wlan2B from Router1)
The anntena is a parabolic (120 to 150 cm) antena with dual polarization feedhorn (http://www.rts-bg.com/?show=item&item=564&id=1346
The TX/RX levels are OK (between -60 and -70) on both cards and on both routers.
One by one the radio links (sets A & B in the scheme) work perfectly. The nightmare is that whatever channels and modulations we choose, when both radiocards are enabled in one router they simply work awful. We got steady 50-60 mbit/s in one direction tcp traffic on both card radiosets, but when we activate both radiolinks they work with 30-40% packet loss and rates drops to 10-12 Mbits at max. Sometimes even if there is no traffic through one of the radiolinks the other set is working badly...
The "funny" thing is that we have at least 3 links that use the same scenario and work perfectly well and another 3 that doesn't work at all.
We have changed the radio cards with various atheros 5211 (the same from Proxim MP11.a), 5213 and 5314 (3-com PCI)
Any ideas or suggestions are welcome. I am eagerly awaiting your comments on the case