From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot1-x32b.google.com (mail-ot1-x32b.google.com [IPv6:2607:f8b0:4864:20::32b]) (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 2C60E3BA8E; Tue, 9 Oct 2018 01:52:40 -0400 (EDT) Received: by mail-ot1-x32b.google.com with SMTP id p23so375042otf.11; Mon, 08 Oct 2018 22:52:40 -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 :cc:content-transfer-encoding; bh=kGGmmAQpD0OBho4DcvmBo0Xs2lM+V+K6jLySAqfCKIo=; b=MQDx4tOwruR3XhMYHCvKpXhH9A5BuS4VD/0SuTRevyXvjZNvEMb7Zohpyjaz9CD4HB 2JUH+XqiO2nC6LMz7n5BvISaiF/sEU2oC8KfT+pHes+yY20Qjm8cW52YvxPxwcQeGzLA +YUI9AW8Had/mAaTKYw+/eBLjWdkxyTgw8M66bjWdQA1UyQ29WCwJL9bf0VOpQ5BN253 dU/V4A9SiPUl8MSRhTxsNYthbtieRNiQB813AIuwZYxr3SWXY3H+e0NGmN0esOUCDPCn mY7GSmgmMjBa3+MqoATgcJPaxZ37qEx5lPX3eLsl/+X25o+sC8Ne+sa0heyGvTL8w2WQ HLYg== 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:cc:content-transfer-encoding; bh=kGGmmAQpD0OBho4DcvmBo0Xs2lM+V+K6jLySAqfCKIo=; b=qqTZPbOZRu60dmdVTm0STNwvrzz7EFWjN6naGiESQ2bRIeJDvGRkDv47rNQcu6FaeI mP4YFTy0Orurnt8/IjfMwV2WFrSgr4+z9pxZ7NPRM1fGiBUrIiH+1U6xzKrjXBWQd28p itpdepc2hd+HoKZsZlmEMEI9oMKNGbvPlGC5emj0fB8fKMPf35yblkypl7whf6THEWLb KbklwCWcd/CoOArF/fy/YqE9tmw7bDx+uO9GbUiLmFGl44HN4oepo0w12gfE6xLFGG7N 6m/uKwoogTDNXtCjk1W9DVP5OqyZoDO8X3Hz0zsv0Kxyx3tfaYUm1KvTwVt0CXo+l8Hq uLNg== X-Gm-Message-State: ABuFfoji5r6BYlI8na1w4SXMW0ltpw3O4AM8kg3PqdS6kGNrAqg2EcIB fJZAKo/YQMWlcI7umYvAa23Z4p6Cam8hdrQRJb4= X-Google-Smtp-Source: ACcGV607NeTtb7GtElqcXqigDGNFORP9Ctg5BWBGshpSxkXev+WJxeMJkpqAdoful/1XXpsUe2HfvY5R4XlYH7aCIPg= X-Received: by 2002:a9d:1787:: with SMTP id j7-v6mr16020387otj.128.1539064359545; Mon, 08 Oct 2018 22:52:39 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: bkil Date: Tue, 9 Oct 2018 07:52:28 +0200 Message-ID: To: Dave Taht , bloat Cc: Make-Wifi-fast , greearb@candelatech.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [Bloat] Is 5/10MHz wifi bandwidth legal in 2.4GHz (half/quarter-clocking)? X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 09 Oct 2018 05:52:40 -0000 I wouldn't be surprised if we could patch this mode to another common chipset other than Atheros. I understand that this is not a standard mode in 2.4GHz if reading the standard to the letter, but it is close enough. If it is legal to use it, as lots of devices support it, it would still be a great choice for certain point to (mult-)point links or mesh/IoT deployments and we should "advertise" this capability better. We could get 16 orthogonal channels instead of 4 (or 13 overlapping) - so we do get more channels in the end. Also we have lots of underutilized spectrum in 5GHz, we would need to update regdb in most countries and handle additional channel numbers to use this. On Mon, Oct 8, 2018 at 10:32 PM Dave Taht wrote: > > 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 specificat= ion > > for the 5 GHz band > > [...] > > The OFDM system also provides a =E2=80=9Chalf-clocked=E2=80=9D operatio= n 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_mo= bicom11.pdf > > https://www.etsi.org/deliver/etsi_en/300300_300399/300328/01.08.01_60/e= n_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 > > > > -- > > Dave T=C3=A4ht > CTO, TekLibre, LLC > http://www.teklibre.com > Tel: 1-831-205-9740