From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-x82e.google.com (mail-qt1-x82e.google.com [IPv6:2607:f8b0:4864:20::82e]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 80ECD3BA8E for ; Mon, 8 Oct 2018 16:32:46 -0400 (EDT) Received: by mail-qt1-x82e.google.com with SMTP id u34-v6so22412220qth.3 for ; Mon, 08 Oct 2018 13:32:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :content-transfer-encoding; bh=3AJgdKRvWovXHFZMpUJkcqpbfLowzWIRvsvXWvchRAE=; b=nouVhPZVyDPFrLYovX8u6PazOW9DEYTI1wpCV4EGIptbIL/s2YqiP0dtaor0pWqZlF NvoNo0av3pZ0BzivCfuNWO9XUqPWymy4vYr+9Hxqng2Plzq6udiwWuWN06ZouzMYA82c LiSfB8BqBvChJlqfGRvkjmfahsUjef/LoncIgMgAP3M/K643GfnrxR5bute4hASDNBoA ViSX50bfHLpIzxkiIFshPxHvbzRSAldCjSoD3psS8nLU1HX6XeSFSMdSRXtkooG0i0XE qBG6SUNHFDnbGiHyJ1lncCImRtyiFyxhUpngvwxXJDisPmJA7G1bxivMEaa6yCoNggtV DsNQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:content-transfer-encoding; bh=3AJgdKRvWovXHFZMpUJkcqpbfLowzWIRvsvXWvchRAE=; b=dlQf7kr90jKCIEDhsbwTTvAA7eMCR/GXZwobk9IL5WgzmDl+QBz0m4PlIvGtT9hRpx 400AOtW8lrKRZxYm0Zy1rnTZlL8Ukcqk+uThBIfbVcLlW7lEs3dkMfvNZ/ih2DEvg1rF 3H3Sg5pN5yEKu+CqincIKaJLzbynhVEZorma5vQyCRCbhVyW9uDaNoGvAwE3vZq5AtAn pYMHAf9A4KwMgUEmkBL1gxQIUc3VQrLUoCYJ1Bqrk0LPp2riS5D5GYsYBPelUgid8/qU SpQ+fFWzLrS/4BZx5KtTEzNIfQI3+JHTeGEt80djvXK9BmEe0tBVOyqUhYliT3IWv0OP 438A== X-Gm-Message-State: ABuFfoheJ9vOdk4QLqTuU51Q4LysBFIstGIizT+Qj6Qay7JMLtlsJtNU Bw2gXpqqqOQ+Nqh3cOFTYcsOFSqrrU/G/DsFpQg= X-Google-Smtp-Source: ACcGV62U+qsHffr62Qh0OOjyhAvDO61g8cCRI2m+s6f7pPjEDum/5TgZzt6XbZ5qN91TUVrv8tmleD16GSjCjflrhgc= X-Received: by 2002:a0c:fe91:: with SMTP id d17-v6mr20581808qvs.93.1539030766001; Mon, 08 Oct 2018 13:32:46 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Dave Taht Date: Mon, 8 Oct 2018 13:32:33 -0700 Message-ID: To: bkil.hu+Aq@gmail.com, Make-Wifi-fast , Ben Greear Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Make-wifi-fast] [Bloat] Is 5/10MHz wifi bandwidth legal in 2.4GHz (half/quarter-clocking)? X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 Oct 2018 20:32:46 -0000 make-wifi-fast is better here. anyway there was a long debate about making the public access channels available to folk that needed it in the ath10k patchset, I think in the end ben greer decided to leave it out lacking getting anyone at the FCC to pay attention. the second question, regarding 5Mhz channels in general - I had tried that a lot (it has worked multiple times in ath9k's lifecycle) and I *liked it*, but as it was non standard never got around to depending on it existing on anything. We definitely need more channels, not less On Mon, Oct 8, 2018 at 1:18 PM bkil wrote: > > If this is not the right forum to discuss, could you please point me > in the right direction? > > After all, channel spacing is indeed 5MHz here. Although using a new > raster instead of the 20MHz channel center frequencies would allow > full utilization of the band (16 or 8 channels respectively), using > the standard set of 11 (13) channels is better than nothing. > > Is it a good idea to use HT instead of g for such links? > > =3D > Some background and links for those who do not know this mode: > > "the 2007 version of the IEEE 802.11 standard [1] specifies 5 and 10 > MHz wide channels for use in the 4.9 GHz public safety bands" > > Although according to my reading of section 17.1, it applies to the > 5GHz bands as well: > > >> 17. Orthogonal frequency division multiplexing (OFDM) PHY specificatio= n > for the 5 GHz band > [...] > The OFDM system also provides a =E2=80=9Chalf-clocked=E2=80=9D operation = using 10 MHz > channel spacings with data > communications capabilities of 3, 4.5, 6, 9, 12, 18, 24, and 27 Mb/s. > The support of transmitting and > receiving at data rates of 3, 6, and 12 Mb/s is mandatory when using > 10 MHz channel spacing. The half- > clocked operation doubles symbol times and clear channel assessment > (CCA) times when using 10 MHz > channel spacing. The regulatory requirements and information regarding > use of this OFDM system in > 4.9 GHz and 5 GHz bands is in Annex I and Annex J.<< > > They probably did not highlight 2.4GHz usage because of mixed-mode > (non-OFDM) crowding, although nowadays we could actually move this > band to OFDM-only as well. > > It is unfortunate that this allowance has disappeared in newer > versions of the standard. Was that intentional? > > Reasons why downclocking is advantageous (up to +9dB link budget): > > * longer GI =3D better protection against multipath fading; > * higher power density allowed (2x here) =3D better SNR; > * less chance for (adjacent-channel) interference; > * reduced TX & RX power consumption for idling and low load. > > I know that 802.11ah/af are here, but there exist literally millions > of devices potentially supporting this old and trusty mode, software > permit. > > Many Atheros chipsets support it, both old and new. OpenWrt has > debugfs patches applied to enable this, while Linux has some other > patches as well, although it is not user visible. > > If this is a legal and preferred mode, it would be nice if we could > unify access. > > https://openwrt.org/docs/guide-user/network/wifi/basic?s[]=3Dchanbw > http://ccr.sigcomm.org/online/files/p135-chandra.pdf > https://kabru.eecs.umich.edu/papers/publications/2011/xyzhang_kgshin_mobi= com11.pdf > https://www.etsi.org/deliver/etsi_en/300300_300399/300328/01.08.01_60/en_= 300328v010801p.pdf > https://www.cwnp.com/forums/posts?postNum=3D305220 > https://forum.archive.openwrt.org/viewtopic.php?id=3D38590 > https://forum.openwrt.org/t/5-mhz-bandwith-option/3615 > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat --=20 Dave T=C3=A4ht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-205-9740