Return-path: Received: from 128-177-27-249.ip.openhosting.com ([128.177.27.249]:43105 "EHLO jmalinen.user.openhosting.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752671AbZKRXFo (ORCPT ); Wed, 18 Nov 2009 18:05:44 -0500 Date: Thu, 19 Nov 2009 01:05:06 +0200 From: Jouni Malinen To: "Luis R. Rodriguez" Cc: Pavel Roskin , David Acker , Andrey Yurovsky , Michael Renzmann , madwifi-devel@lists.sourceforge.net, madwifi-users@lists.sourceforge.net, linux-wireless Subject: Re: [Madwifi-devel] Survey: What are you using MadWifi for, and why? Message-ID: <20091118230506.GA5889@jm.kir.nu> References: <43e72e890911171337p4b0d97fcp844266137bb51b56@mail.gmail.com> <4B03193E.2080304@roinet.com> <43e72e890911171345q2dc59d66g6ac2a9eec04c577c@mail.gmail.com> <4B031B48.1090105@roinet.com> <43e72e890911171404x1a46d07alb54946768d0f9cf5@mail.gmail.com> <4B032390.3080501@roinet.com> <20091117225408.GA20540@jm.kir.nu> <43e72e890911171512k562f9329td56cc741dd1c5151@mail.gmail.com> <1258581492.10593.24.camel@mj> <43e72e890911181408r43dadf7av277b255eb9007481@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <43e72e890911181408r43dadf7av277b255eb9007481@mail.gmail.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Wed, Nov 18, 2009 at 02:08:16PM -0800, Luis R. Rodriguez wrote: > Are you aware of any regulatory rules which prohibit narrower > channels? It just seems odd. I don't remember any rules that would explicitly do that, but there may be some implicit limitations due to the slower TX rate. I don't know whether this would hit anywhere, but at least quarter width channel with 1 Mbps TX rate and maximum frame length might get pretty close to some maximum TX-without-sensing limits. Though, that is less likely to be an issue on 5 GHz band due to 6 Mbps minimum TX rate even at quarter channels could be fast enough. There could also be some rules that state the minimum TX rate, so there could potentially be need to change supported rate sets and/or fragmentation threshold in some corner cases. Actually, even with 6/4 Mbps TX rate, the channel sensing rule in Japan (carrier sense every 4 ms) (if that rule is still valid.. haven't really checked), we could hit the limit with maximum frame length. -- Jouni Malinen PGP id EFC895FA