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 <bkil.hu...@gmail.com> 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? > > = > 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 specification > for the 5 GHz band > [...] > The OFDM system also provides a “half-clocked” 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 = better protection against multipath fading; > * higher power density allowed (2x here) = 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[]=chanbw > http://ccr.sigcomm.org/online/files/p135-chandra.pdf > https://kabru.eecs.umich.edu/papers/publications/2011/xyzhang_kgshin_mobicom11.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=305220 > https://forum.archive.openwrt.org/viewtopic.php?id=38590 > https://forum.openwrt.org/t/5-mhz-bandwith-option/3615 > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat _______________________________________________ Bloat mailing list Bloat@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/bloat