From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Date: Mon, 16 Jul 2012 10:19:10 -0700 Subject: [ath9k-devel] Question about antenna throughput. In-Reply-To: References: <4FFEDAFF.5090706@candelatech.com> Message-ID: <50044D0E.1060800@candelatech.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ath9k-devel@lists.ath9k.org On 07/15/2012 02:39 AM, Adrian Chadd wrote: > On 12 July 2012 07:11, Ben Greear wrote: >> We have a 3x3 NIC (wpea-127n). A user reports that when using >> a single antenna cable to directly connect to an AP (with attenuator), >> that one of the antenna can do about 30Mbps download from AP, the >> other about 25Mbps, and the third cable can only do about 1Mbps. >> >> Is that expected results? > > If I recall what's going on, the actual signal sent out the antennas > isn't necessarily a mirrored copy from each antenna, even for 1 stream > and legacy signals. Definitely for 2 and 3 stream signals that is > absolutely to be expected. > > The baseband may decide to "scramble" it so part of the wireless > transmission goes out each antenna. Don't ask me about the details, I > don't know them. > > There's also STBC for 1 stream 11n rates. > > If you want to connect a single cable to an AP, you have to put it > into a single chain TX/RX mode and use the correct chain. On that NIC > you can configure it to be a single chain on any of chain 0, 1 or 2. > (It doesn't have to be 0.) But you have to choose a single chain. > > So, yes. I think that's totally understandable behaviour. Ok, I'm going to look into this chain configuration. This user is also reporting that our box can only communicate down to about -72dBm, whereas some off-the-shelf USB dongles are providing around 100kbps at -78 to -80dBm. Are there any published rate v/s range results for ath9k available? Perhaps the chaining issue is also involved in this? Thanks for the detailed answers on this....this is new territory for me! Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com