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

[Bob McMahon <bob.mcmahon@broadcom.com>]

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Hi All,

This is a very interesting thread - thanks to all for taking the time to
respond.   (Personally, I now have better understanding of the difficulties
associated with a PHY subsystem that supports a wide 1GHz.)

Not to derail the current discussion, but I am curious to ideas on
addressing the overhead associated with media access per collision
avoidance.  This overhead seems to be limiting transmits to about 10K per
second (even when a link has no competition for access.)   Is there a way,
maybe using another dedicated radio, to achieve near instantaneous
collision detect (where the CD is driven by the receiver state) such that
mobile devices can sample RF energy to get theses states and state changes
much more quickly?

Thanks,
Bob





On Mon, Jun 27, 2016 at 10:55 AM, Dave Taht <dave.taht@gmail.com> wrote:

> In terms of wifi history... since I go back to the 70s...
>
> was that we did not know how to do it - 73 we had aloha, which begat
> ethernet... and for years progress was slow. Even as late as 91 or so
> a "good" microwave link cost something like 40k an end, and required
> special cooling and permits on so on. Wifi was started as an ipx/spx
> bridge tech that didn't start to get anywhere until the mid 90s.
>
> It was far from obvious at any point that the cost reductions would
> take place that did, there was so much work in the analog domain that
> looked (at the time) resistant to moores law. As for spectrum, finding
> ways to leverage 2.4ghz cost metricom's backers in particular more
> money than I care to think about, and I'm always pointing at how the
> discovery that a more centralized clock and a retransmit at the mac
> layer is what eventually made 802.11b viable. Many other wireless
> ideas have been tried and died - wimax, for example, UWB, for another.
> Bluetooth has evolved into adding "discovery prototol", which was kind
> of unexpected... (there is even 6lopan over bluetooth now). The 5ghz
> spectrum users have tended to adopt their own mac, as has some other
> less popular bands.
>
> While I'm pretty happy that we've got much of the queuing theory for
> fixing 802.11n and 802.1ac nailed now, outstanding problems include
> the hidden station problem, the rise in the background noise levels,
> insufficient channels, and increasingly proprietary standards and
> chipsets, as well as transport, switching and routing protocols
> layered on top originally designed for isochronus transports.
>
> I like to think (or possibly delude myself), that the solutions to
> airtime fairness scheduling now emerging may one day lead to saner
> scheduling around the hidden station problem in particular. Otherwise,
> and elsewhere, there remain a lot of rocks to bang together, and a
> long list of other issues we've captured elsewhere.
>
> I am still periodically reviewing and updating this as we go along, as
> it remains the best central document we have on all that's wrong in
> wifi with some hints as to how to go about fixing them.
>
>
> https://docs.google.com/document/d/1Se36svYE1Uzpppe1HWnEyat_sAGghB3kE285LElJBW4/edit
>

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