On 01/25/2013 10:23 AM, Sam Leffler wrote:
On Fri, Jan 25, 2013 at 10:11 AM, Ben Greear <greearb@xxxxxxxxxxxxxxx <mailto:greearb@xxxxxxxxxxxxxxx>> wrote: I've put 3 ath9k AR9380 NICs into a single system (core-i7). Each is configured for an AP on a separate 5Ghz channel (40Mhz wide). Individually, I can get about 300Mbps transmit towards the AP on any particular radio, but when running all together, total throughput is only about 475Mbps. I assume there is some cross-channel bleeding or similar. Yes. The APs are close by, so I was wondering if perhaps there was a way to configure the radios to be less sensitive and thus pay less attention to channel cross-talk? Any suggestions for things to try are appreciated! If you cannot fully isolate the antenna the usual approach is to schedule radio usage so tx/rx is done on all radios at the same time. Ubiquity and Mikrotik do this and there have been many research papers that discuss this.
It seems basically impossible to fully isolate the NICs in a normal system. The u.fl/IPEX pigtails bleed for sure. The NICs probably bleed just as bad or worse, and I can't think of a good way to increase isolation without somehow encasing each NIC in a small RF-proof box (and somehow keeping the RF from running down the pci-e ribon cables, etc). Playing tricks with scheduling seems pretty nifty, but probably not realistic for my particular use case (emulating lots and lots of stations that should run against whatever AP(s) the customers may be using). If there were a way to decrease rx-sensitivity, wouldn't that be pretty similar to having all NICs transmit at once (in other words, the NICs could better ignore the fainter cross-talk signals and focus on the high-powered signals on their particular channel)? Thanks, Ben -- Ben Greear <greearb@xxxxxxxxxxxxxxx> Candela Technologies Inc http://www.candelatech.com -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
