From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-x434.google.com (mail-pf1-x434.google.com [IPv6:2607:f8b0:4864:20::434]) (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 ABB223BA8E for ; Mon, 8 Oct 2018 23:53:08 -0400 (EDT) Received: by mail-pf1-x434.google.com with SMTP id u12-v6so113064pfn.12 for ; Mon, 08 Oct 2018 20:53:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mounce.com.au; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=Ur1kDwR25rdCcXbCPhcLU6eSd6+clw4B5RUgo0SE5us=; b=E/Mc7GiBKdgq9m0tWHUg5nDYoWo5J22rUseAmyIAfc0ufa6XyjRSYIxEFcK8H2LJ7f BpJ+/6t3J0vwB5h0X8IC7dzbeB5Qq5eSf16dwi0g4yC62JyG38UATGOqDvc262wNWrRi KUzzV7NlPOCSLh9bZALto9QmVX0o5iCbpHDeLDEFDvBLj3CtEYQF6RZpzO6/JVCcrQAp MAsfTEpv2LVEmr0CWBTJi8xBWpOYZslCZxJqn8atcy+bFAVKG1sem5lNWux6vQPnnxqZ Cuu4NVpPsKm84o1erB5R/m+G57EQNRf9BF3MCYslKZOz3XVf1QUOX2zS/vtFQrFgAbEx ltyw== 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=Ur1kDwR25rdCcXbCPhcLU6eSd6+clw4B5RUgo0SE5us=; b=Cxy7g1kqUo/9rNHoTeIBOh2n/xNbdnVZjvpp53k0G2tTcUpmFa+1ppKwdmcVMgFx7/ loIm1vja1cZj1L/H7BkwTSKDWp33Bduu6JqLt4ZxEHFvxPL2DNpOnpm8t5AueNRU4W7g zDpGrH/x9Y3PAU6S+uBsR44cAufNBu6gYQQF8wshDtwSJ4KgB9yzAX+TJI7J9s3EpqQf sKl6ByJ6cNUH14Mpof6PM2cJ79wPWLlE/3fFb08knmYG7sxljrQdMaeEiwUtIbfpX4TX l+/PMi6ORNZcYELBevTX/DkBuIneQILUOi9adwmO4XzTkkU6cIJD1dBItmKpEL4sJUSA 0Uaw== X-Gm-Message-State: ABuFfogdz0ALBhLu93eMlyZ2U08ca2Jp2KsJyQIDsq0mdt0nxXRBJcew hhy8lPmAKctkMVF8ER2mwHH6alnq9/3YuKmuPUiTXA== X-Google-Smtp-Source: ACcGV612DhFqmwVqqopQlBi0HMjvzqADK+y/Fwo5H8EKUM3tx+JsWcFWqME80wLGJbVOlDQ3EBuY+plOmSM5QOi+aok= X-Received: by 2002:a62:1dca:: with SMTP id d193-v6mr8730243pfd.157.1539057187749; Mon, 08 Oct 2018 20:53:07 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Ryan Mounce Date: Tue, 9 Oct 2018 14:22:56 +1030 Message-ID: To: bkil.hu+Aq@gmail.com Cc: bloat 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 03:53:08 -0000 I'm not aware of anywhere this would be illegal. Worst case you will need to reduce power by 3/6dB (10/5MHz) if there is a power spectral density limit in a given jurisdiction and max EIRP @ 20MHz is already at that limit. On Tue, 9 Oct 2018 at 06:48, 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