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

[David Lang <david@lang.hm>]

On Mon, 27 Jun 2016, Bob McMahon wrote:

> 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.)

I'm not sure where you're getting 10K/second from. We do need to limit the 
amount of data transmitted in one session to give other stations a chance to 
talk, but if the AP replies immediatly to ack the traffic, and the airwaves are 
idle, you can transmit again pretty quickly.

people using -ac equipment with a single station are getting 900Mb/sec today.

>   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?

This gets back to the same problems (hidden transmitter , and the simultanious 
reception of wildly different signal strengths)

When you are sending, you will hear yourself as a VERY strong signal, trying to 
hear if someone else is transmitting at the same time is almost impossible (100 
ft to 1 ft is 4 orders of magnatude, 1 ft to 1 inch is another 2 orders of 
magnatude)

And it's very possible that the station that you are colliding with isn't one 
you can hear at all.

Any AP is going to have a better antenna than any phone. (sometimes several 
orders of magnatude better), so even if you were located at the same place as 
the AP, the AP is going to hear signals that you don't.

Then consider the case where you and the other station are on opposite sides of 
the AP at max range.

and then add cases where there is a wall between you and the other station, but 
the AP can hear both of you.

David Lang