From owner-freebsd-wireless@FreeBSD.ORG Thu Sep 8 08:59:14 2011 Return-Path: Delivered-To: freebsd-wireless@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1353B106566C; Thu, 8 Sep 2011 08:59:14 +0000 (UTC) (envelope-from lev@freebsd.org) Received: from onlyone.friendlyhosting.spb.ru (onlyone.friendlyhosting.spb.ru [IPv6:2a01:4f8:131:60a2::2]) by mx1.freebsd.org (Postfix) with ESMTP id A44138FC16; Thu, 8 Sep 2011 08:59:13 +0000 (UTC) Received: from lion.home.serebryakov.spb.ru (unknown [IPv6:2001:470:923f:1:14f9:cfdf:caf2:2c18]) (Authenticated sender: lev@serebryakov.spb.ru) by onlyone.friendlyhosting.spb.ru (Postfix) with ESMTPA id 09AA04AC58; Thu, 8 Sep 2011 12:59:10 +0400 (MSD) Date: Thu, 8 Sep 2011 12:59:07 +0400 From: Lev Serebryakov X-Priority: 3 (Normal) Message-ID: <426917282.20110908125907@serebryakov.spb.ru> To: Adrian Chadd In-Reply-To: References: <663133681.20110907193747@serebryakov.spb.ru> <437702009.20110907235248@serebryakov.spb.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=windows-1251 Content-Transfer-Encoding: quoted-printable Cc: freebsd-wireless@freebsd.org Subject: Re: AP performance (again): txpower regulation X-BeenThere: freebsd-wireless@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Discussions of 802.11 stack, tools device driver development." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 08 Sep 2011 08:59:14 -0000 Hello, Adrian. You wrote 8 =F1=E5=ED=F2=FF=E1=F0=FF 2011 =E3., 8:02:28: > These look fine, but I don't have as much experience with the ar5212 > series stuff as I do with the AR5416+ series stuff. >> =A0It seems, registers are Ok. But clients don't see any difference! >> Maybe, it is because my Senao card is "powerful" one, with additional >> schematic (and power supply) to boost signal? > Hm. Well, how far away are they? You can do a bit of math to see what About 7 meters and 2 concrete (internal) walls :) I've repeated experiment when client and server were within 3 meters without walls -- txpower seems to work. 30 gives about -55dB (accroding to InSSIDer -- I'm not sure, that this numbers could be used as absolute ones),txpower 15 gives about -65 and txpower 1 about -75. But in any case iperf throughput is about 10-11Mbit/s with pikes up to 18= Mbit/s. It looks pessimistic: 18Mbit/s in 2m direct sight. I know, that 54Mbit/s is half-duplex, but 18Mbit/s is less than 27Mbit/s and "ifconfig wlan0 list sta" shows data like this: 00:18:de:08:e8:1d 1 9 36M 21.5 0 28696 48048 EPS AQE RSN = WME Why 36M in almost-ideal conditions!? Why -70dB in room next to my AP, when neighborhood AP (simple d-link, according to all data) is -65, and this room is furthest from other apartments)!? Also, graph of signal strength is much smoother on small distances and didn't look like mountain range. Another observation: when distance is about 5 meters txpower 30, 15 and 10 are almost indistinguishable (and grpahs are smooth, -75dB for 10, -70dB for 15, -67dB for 30), but txpower 1 gives crazy graph: it osscilate between -80 and -10 (!!!). Sometimes it gold on -77, but after 10-15 seconds raise to the sky, then drop down again, etc. > changes the TX power on the sender side would have on the receiver > signal level. > Have you ever looked at doing up a free space loss model to predict > what the signal level(s) should be? It is too complex for me :-) And I'm not sure, that I have tool to measure real signal to compare with calculations. --=20 // Black Lion AKA Lev Serebryakov