From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0484DC4741F for ; Tue, 10 Nov 2020 01:42:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B46942065D for ; Tue, 10 Nov 2020 01:42:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730045AbgKJBme (ORCPT ); Mon, 9 Nov 2020 20:42:34 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:42615 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729452AbgKJBmd (ORCPT ); Mon, 9 Nov 2020 20:42:33 -0500 Received: from mail-il1-f198.google.com ([209.85.166.198]) by youngberry.canonical.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1kcIg3-00011F-5w for linux-wireless@vger.kernel.org; Tue, 10 Nov 2020 01:42:31 +0000 Received: by mail-il1-f198.google.com with SMTP id q5so8063678ilc.13 for ; Mon, 09 Nov 2020 17:42:31 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=+R8H+LRx4iZIaZ5oZVZMi0sukbFe8SA2wgM0zDYFRc4=; b=JFfgL6bsxzdk8UbVSc1anoxwoteFT43i1FUOjV6s6sCYuIrr6JT0M6zKfbsBzGCKwX 9wQwlkRlI/dNSJ27MqA2DS37GO26SMl28EWYM1O67q0xjewU84qQqSNV57woWQW7pwuE FxgjX9seDhjwl2YXKgfuvpsU11G3gnnMmQQtrmacL1tufPCJbdBkaDF0YAL/NI8lf+rD FcsXOHjiAMnwE7X6JQ0sW3iI2nB/T+lkymFAmVF9PjKwQ6TwpOb3nMZiCdbZ/ESm+6fM AqfpNxN6Fa47+8W4gpV6i0RKJb0OSlVMAdVFVA2Te8qjHNJpWNiY2vUDiWqgPQ9YV2eT BeRw== X-Gm-Message-State: AOAM533/GpjPwMFLBbkUBhoOEbyyb0ZEdosKSJOI6BTJ/6LQIprBhdKB m5fjUoOkWiOnGgj0/+PUzlkSqQ6T2nPPJhrRsuDjwju9V2gg12Gm57IsGLZ4MTZvLY6WQV55YuA NnYdLh3WXfbisjJeQdwDwRGlcXRgq34QiUHpcUFGN4Iwf X-Received: by 2002:a92:aa53:: with SMTP id j80mr6305990ili.88.1604972550213; Mon, 09 Nov 2020 17:42:30 -0800 (PST) X-Google-Smtp-Source: ABdhPJzmKL1iJDSiWlPOlKcqXKHV9Fm2RXfn/WFAFG8Ry2az/KqFWpyL5jPyNdx8LzOYbHLQudCT5w== X-Received: by 2002:a92:aa53:: with SMTP id j80mr6305981ili.88.1604972549997; Mon, 09 Nov 2020 17:42:29 -0800 (PST) Received: from localhost ([2605:a601:ac0f:820:89a:1dd3:9ddb:b24d]) by smtp.gmail.com with ESMTPSA id d142sm6666293iof.43.2020.11.09.17.42.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Nov 2020 17:42:29 -0800 (PST) Date: Mon, 9 Nov 2020 19:42:28 -0600 From: Seth Forshee To: bkil Cc: wireless-regdb@lists.infradead.org, linux-wireless@vger.kernel.org Subject: Re: [PATCH] wireless-regdb: restore channel 12 & 13 limitation in the US Message-ID: <20201110014228.GJ6125@ubuntu-x1> References: <840438bf70c72d2ab933aee9ae5aa6985b6c1531.1601902881.git.b.K.il.h.u+tigbuh@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <840438bf70c72d2ab933aee9ae5aa6985b6c1531.1601902881.git.b.K.il.h.u+tigbuh@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Mon, Oct 05, 2020 at 03:01:22PM +0200, bkil wrote: > The precisely allowed transmission power on channel 12 & 13 is not clear. > > I did some fact checking and document reviews in the past, but still > failed to come up with an exact reference or calculation regarding what TX > power should be allowed in general to reduce interference in the > neighboring restricted band 2483.5-2500 MHz and whether indoor vs. outdoor > and b/g/n modulation would make a difference (probably yes). > > Existing documents that discuss this are vague and pretty much out of date: > https://en.wikipedia.org/wiki/List_of_WLAN_channels#endnote_B > > Following these guidelines, I failed to come up with an approximate > formula that would prohibit usage of channel 12 & 13, but still allow > usage of channel 11 with full power, hence at least part of the argument > for prohibiting channel 12 & 13 needs to be refined. > > Until further research, just to stay safe, I propose that we restore the > previous limitation of disabling channel 12 & 13 as before. We should > work towards finding a safe transmission power to use on both and specify > that (like 50mW on channel 13 and 100mW on channel 12?). > > I've also started a discussion for investigation on Wikipedia: > https://en.wikipedia.org/wiki/Talk:List_of_WLAN_channels#Should_the_2.4GHz_channel_12_and_13_in_the_USA_need_updating? > > Signed-off-by: bkil I tried doing a little research, and it does appear that use of channels 12 and 13 is more complicated than it might seem on the surface. I cannot find any clear guidance on power limits and lack the background to determine appropriate limits from the information I did find, so it does seem prudent to restore the previous limitation. Applied, thanks! > --- > db.txt | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/db.txt b/db.txt > index ac32483..68613cf 100644 > --- a/db.txt > +++ b/db.txt > @@ -1568,8 +1568,12 @@ country UG: DFS-FCC > > # https://www.ecfr.gov/cgi-bin/text-idx?SID=eed706a2c49fd9271106c3228b0615f3&mc=true&node=pt47.1.15&rgn=div5 > # Title 47 Part 15 - Radio Frequency Devices, April 2, 2020 > +# Channels 12 and 13 are not forbidden, but are not normally used with full > +# power in order to avoid any potential interference in the adjacent restricted > +# frequency band, 2,483.5–2,500 MHz which is subject to strict emission limits > +# set out in 47 CFR § 15.205. TODO: reenable and specify a safe TX power here. > country US: DFS-FCC > - (2400 - 2483.5 @ 40), (30) > + (2400 - 2472 @ 40), (30) > # 5.15 ~ 5.25 GHz: 30 dBm for master mode, 23 dBm for clients > (5150 - 5250 @ 80), (23), AUTO-BW > (5250 - 5350 @ 80), (23), DFS, AUTO-BW