[Cerowrt-devel] [Make-wifi-fast] more well funded attempts showing market demandfor better wifi

Sun Jun 26 18:54:37 EDT 2016

Is there a specific goal in mind?  This seems an AP tx centric proposal,
though I may not be fully understanding it.  I'm also curious as why not
scale in spatial domain vs the frequency domain, i.e. AP and STAs can also
scale using MiMO.  Why not just do that? So many phones today are 1x1, some
2x2 and few 3x3.   Yet APs are moving to 4x4 and I think the standard
supports 8x8.  (I'm not sure the marginal transistor count increase per
each approach.)  On the AP tx side, MuMIMO is also there which I think is
similar to the DAC proposal.

I'm far from a PHY & DSP expert, but I think the simultaneous AP receive is
the most difficult issue per the power variations, aka SNR.  Each of the
mobile device energies is affected per inverse square law (unless some form
of wave guide is used.)  Hence wi-fi use of time domain slots prior to
transmit (no longer simultaneous in time.)  Particularly needed for devices
that communicate with one another.  Unfortunately, "collocated"
energy/information sources must honor this TDM  even when not communication
with one another per tragedy of the commons.  (Agreed there is no such
thing as a collision so let's redefine it to mean that the receiver is
unable to receive per RF energy "confusion", still a tragedy of the
commons.  I don't know what drives the limits to DSP decode that could
minimize or eliminate  this tragedy.)

At the end of the day, would the ideal network would resemble a wired
ethernet (including ethernet switch fabric) without the waveguides (or
wires/fibers)?  From that perspective, here are some thoughts to the goals

o)  TX op/access to transmit driven to zero.  (Collision avoidance isn't
nearly as good as instantaneous collision detect in this context, though
"collision" should replaced with "confusion")
o)  RX confusion detection time propagated to stop offending TX(s) driven
to zero
o)  Support of different encodings (e..g phy rates) pushes towards virtual
output queueing prior (queuing at the transmitter)
o)  Power per bit xfered towards zero or driven per cost & energy density
of batteries.  Note: Atomic batteries not allowed per humans being involved.
o)  Transistor count (chip cost) per bit moved driven by Moore's law and
those economics
o)  Reduce "collision/confusion" domain (less STAs per AP) ideally to zero

Just some thoughts off the top of my head.  Please do comment and correct.
Thanks in advance for the discussion.

Bob

On Fri, Jun 24, 2016 at 2:24 PM, <dpreed at reed.com> wrote:

> Without custom silicon, doing what I was talking about would involve non
> standard MAC power management, which would require all devices to agree.
>
> David Lang's explanation was the essence of what I meant. the transmission
> from access point on multiple channels is just digital addition if the DACs
> have enough bits per sample. to make sure that the signals to the AP are
> equalized, just transmit at a power that makes that approximately true...
> which means a power amp with at most 30 dB of dynamic gain setting. typical
> dynamic path attenuation range (strongest to weakest ratio) among stations
> served by an AP is < 20 dB from my past experiments on well
> operating-installtions, but 25 can be seen in reflection heavy
> environments.-----Original Message-----
> From: "David Lang" <david at lang.hm>
> Sent: Fri, Jun 24, 2016 at 1:19 am
> To: "Bob McMahon" <bob.mcmahon at broadcom.com>
> Cc: "Bob McMahon" <bob.mcmahon at broadcom.com>,
> make-wifi-fast at lists.bufferbloat.net, "cerowrt-devel at lists.bufferbloat.net"
> <cerowrt-devel at lists.bufferbloat.net>
> Subject: Re: [Make-wifi-fast] more well funded attempts showing market
> demandfor better wifi
>
> well, with the kickstarter, I think they are selling a bill of goods.
>
> Just using the DFS channels and aggregating them as supported by N and AC
> standards would do wonders (as long as others near you don't do the same)
>
> David Lang
>
> On Thu, 23 Jun 2016, Bob McMahon wrote:
>
> > Date: Thu, 23 Jun 2016 20:01:22 -0700
> > From: Bob McMahon
> > To: David Lang
> > Cc: dpreed at reed.com, make-wifi-fast at lists.bufferbloat.net,
> >     "cerowrt-devel at lists.bufferbloat.net"
> >
> > Subject: Re: [Make-wifi-fast] more well funded attempts showing market
> demand
> >     for better wifi
> >
> > Thanks for the clarification.   Though now I'm confused about how all the
> > channels would be used simultaneously with an AP only solution (which is
> my
> > understanding of the kickstarter campaign.)
> >
> > Bob
> >
> > On Thu, Jun 23, 2016 at 7:14 PM, David Lang  wrote:
> >
> >> I think he is meaning when one unit is talking to one AP the signal
> levels
> >> across multiple channels will be similar. Which is probably fairly true.
> >>
> >>
> >> David Lang
> >>
> >> On Thu, 23 Jun 2016, Bob McMahon wrote:
> >>
> >> Curious, where does the "in a LAN setup, the variability in [receive]
> >>> signal strength is likely small enough" assertion come?   Any specific
> >>> power numbers here? We test with many combinations of "signal strength
> >>> variability" (e.g. deltas range from 0 dBm -  50 dBm) and per different
> >>> channel conditions.  This includes power variability within the spatial
> >>> streams' MiMO transmission.   It would be helpful to have some physics
> >>> combined with engineering to produce some pragmatic limits to this.
> >>>
> >>> Also, mobile devices have a goal of reducing power in order to be
> >>> efficient
> >>> with their battery (vs a goal to balance power such that an AP can
> >>> receive simultaneously.)  Power per bit usually trumps most other
> design
> >>> goals.  There market for battery powered wi-fi devices drives a
> >>> semi-conductor mfg's revenue so my information come with that bias.
> >>>
> >>> Bob
> >>>
> >>> On Thu, Jun 23, 2016 at 1:48 PM,  wrote:
> >>>
> >>> The actual issues of transmitting on multiple channels at the same time
> >>>> are quite minor if you do the work in the digital domain (pre-DAC).
> You
> >>>> just need a higher sampling rate in the DAC and add the two signals
> >>>> together (and use a wideband filter that covers all the channels).
> No RF
> >>>> problem.
> >>>>
> >>>> Receiving multiple transmissions in different channels is pretty much
> the
> >>>> same problem - just digitize (ADC) a wider bandwidth and separate in
> the
> >>>> digital domain.  the only real issue on receive is equalization - if
> you
> >>>> receive two different signals at different receive signal strengths,
> the
> >>>> lower strength signal won't get as much dynamic range in its samples.
> >>>>
> >>>> But in a LAN setup, the variability in signal strength is likely small
> >>>> enough that you can cover that with more ADC bits (or have the MAC
> >>>> protocol
> >>>> manage the station transmit power so that signals received at the AP
> are
> >>>> nearly the same power.
> >>>>
> >>>> Equalization at transmit works very well when there is a central AP
> (as
> >>>> in
> >>>> cellular or normal WiFi systems).
> >>>>
> >>>>
> >>>>
> >>>> On Thursday, June 23, 2016 4:28pm, "Bob McMahon" >>>
> bob.mcmahon at broadcom.com>
> >>>> said:
> >>>>
> >>>> _______________________________________________
> >>>>> Make-wifi-fast mailing list
> >>>>> Make-wifi-fast at lists.bufferbloat.net
> >>>>> https://lists.bufferbloat.net/listinfo/make-wifi-fast
> >>>>> An AP per room/area, reducing the tx power (beacon range) has been my
> >>>>> approach and has scaled very well.   It does require some wires to
> each
> >>>>>
> >>>> AP
> >>>>
> >>>>> but I find that paying an electrician to run some quality wiring to
> >>>>>
> >>>> things
> >>>>
> >>>>> that are to remain stationary has been well worth the cost.
> >>>>>
> >>>>> just my $0.02,
> >>>>> Bob
> >>>>>
> >>>>> On Thu, Jun 23, 2016 at 1:10 PM, David Lang  wrote:
> >>>>>
> >>>>> Well, just using the 5GHz DFS channels in 80MHz or 160 MHz wide
> chunks
> >>>>>> would be a huge improvement, not many people are using them (yet),
> and
> >>>>>>
> >>>>> the
> >>>>
> >>>>> wide channels let you get a lot of data out at once. If everything is
> >>>>>> within a good range of the AP, this would work pretty well. If you
> end
> >>>>>>
> >>>>> up
> >>>>
> >>>>> needing multiple APs, or you have many stations, I expect that you
> will
> >>>>>>
> >>>>> be
> >>>>
> >>>>> better off with more APs at lower power, each using different
> channels.
> >>>>>>
> >>>>>> David Lang
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> On Thu, 23 Jun 2016, Bob McMahon wrote:
> >>>>>>
> >>>>>> Date: Thu, 23 Jun 2016 12:55:19 -0700
> >>>>>>
> >>>>>>> From: Bob McMahon
> >>>>>>> To: Dave Taht
> >>>>>>> Cc: make-wifi-fast at lists.bufferbloat.net,
> >>>>>>>     "cerowrt-devel at lists.bufferbloat.net"
> >>>>>>>
> >>>>>>> Subject: Re: [Make-wifi-fast] more well funded attempts showing
> market
> >>>>>>> demand
> >>>>>>>     for better wifi
> >>>>>>>
> >>>>>>>
> >>>>>>> hmm, I'm skeptical.   To use multiple carriers simultaneously is
> >>>>>>>
> >>>>>> difficult
> >>>>
> >>>>> per RF issues.   Even if that is somehow resolved, to increase
> >>>>>>>
> >>>>>> throughput
> >>>>
> >>>>> usually requires some form of channel bonding, i.e. needed on both
> >>>>>>>
> >>>>>> sides,
> >>>>
> >>>>> and brings in issues with preserving frame ordering.  If this is just
> >>>>>>> channel hopping, that needs coordination between both sides (and
> isn't
> >>>>>>> simultaneous, possibly costing more than any potential gain.)   An
> AP
> >>>>>>>
> >>>>>> only
> >>>>
> >>>>> solution can use channel switch announcements (CSA) but there is a
> >>>>>>>
> >>>>>> cost to
> >>>>
> >>>>> those as well.
> >>>>>>>
> >>>>>>> I guess don't see any break though here and the marketing on the
> site
> >>>>>>> seems
> >>>>>>> to indicate something beyond physics, at least the physics that I
> >>>>>>> understand.  Always willing to learn and be corrected if I'm
> >>>>>>> misunderstanding things.
> >>>>>>>
> >>>>>>> Bob
> >>>>>>>
> >>>>>>> On Wed, Jun 22, 2016 at 10:18 AM, Dave Taht
> >>>>>>>
> >>>>>> wrote:
> >>>>
> >>>>>
> >>>>>>> On Wed, Jun 22, 2016 at 10:03 AM, Dave Taht
> >>>>>>>
> >>>>>> wrote:
> >>>>
> >>>>>
> >>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>
> >>>>
> https://www.kickstarter.com/projects/portalwifi/portal-turbocharged-wifi?ref=backerkit
> >>>>
> >>>>>
> >>>>>>>>
> >>>>>>>>> "Portal is the first and only router specifically engineered to
> cut
> >>>>>>>>> through and avoid congestion, delivering consistent,
> >>>>>>>>> high-performance
> >>>>>>>>> WiFi with greater coverage throughout your home.
> >>>>>>>>>
> >>>>>>>>> Its proprietary spectrum turbocharger technology provides access
> to
> >>>>>>>>> 300% more of the radio airwaves than any other router, improving
> >>>>>>>>> performance by as much as 300x, and range and coverage by as
> much as
> >>>>>>>>> 2x in crowded settings, such as city homes and multi-unit
> >>>>>>>>> apartments"
> >>>>>>>>>
> >>>>>>>>> It sounds like they are promising working DFS support.
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>> It's not clear what chipset they are using (they are claiming
> wave2)
> >>>>>>>> -
> >>>>>>>> but they are at least publicly claiming to be using openwrt. So I
> >>>>>>>> threw in enough to order one for september, just so I could
> comment
> >>>>>>>> on
> >>>>>>>> their kickstarter page. :)
> >>>>>>>>
> >>>>>>>> I'd have loved to have got in earlier (early shipments are this
> month
> >>>>>>>> apparently), but those were sold out.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>
> https://www.kickstarter.com/projects/portalwifi/portal-turbocharged-wifi/comments
> >>>>
> >>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> --
> >>>>>>>>> Dave TÃ¤ht
> >>>>>>>>> Let's go make home routers and wifi faster! With better software!
> >>>>>>>>> http://blog.cerowrt.org
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> --
> >>>>>>>> Dave TÃ¤ht
> >>>>>>>> Let's go make home routers and wifi faster! With better software!
> >>>>>>>> http://blog.cerowrt.org
> >>>>>>>> _______________________________________________
> >>>>>>>> Make-wifi-fast mailing list
> >>>>>>>> Make-wifi-fast at lists.bufferbloat.net
> >>>>>>>> https://lists.bufferbloat.net/listinfo/make-wifi-fast
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> _______________________________________________
> >>>>>> Make-wifi-fast mailing list
> >>>>>> Make-wifi-fast at lists.bufferbloat.net
> >>>>>> https://lists.bufferbloat.net/listinfo/make-wifi-fast
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>
> >>>>
> >>>>
> >>>>
> >
>
>
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