[Make-wifi-fast] [Cerowrt-devel] closing up my make-wifi-fast lab

[Bob McMahon]

Minimizing power is rule #2 per Paul Banan.

SOME KINDERGARTEN RULES (written in 1994)

   To take the fullest advantage of our new technology with its sharing
   of a common resource requires that our smart transmitters and
   receivers cooperate. This may sound complicated, but the rules to make
   maximum effective use of the shared band are simple -- primarily a
   matter of common decency in sharing resources. The rules are somewhat
   similar to those you learned in kindergarten, assuming you lived in a
   tough neighborhood.

   Rule #1. Keep away from the big bullies in the playground. (Avoid the
   strongest signals.)

   Rule #2. Share your toys. (Minimize your transmitted power. Use the
   shortest hop distances feasible. Minimize average power density per
   Hertz.)

   Rule #3. If you have nothing to say, keep quiet.

   Rule #4. Don't pick on the big kids. (Don't step on strong signals.
   You're going to get clobbered.)

   Rule #5. If you feel you absolutely must beat up somebody, be sure to
   pick someone smaller than yourself. (Now this is a less obvious one,
   as weak signals represent far away transmissions; so your signals will
   likely be attenuated the same amount in the reverse direction and
   probably not cause significant interference.)

   Rule #6. Don't get too close to your neighbor. Even the weakest
   signals are very strong when they are shouted in your ear.

   Rule #7. Lastly, don't be a cry baby. (If you insist on using obsolete
   technology that is highly sensitive to interfering signals, don't
   expect much sympathy when you complain about interfering signals in a
   shared band.)

Bob


On Thu, Aug 30, 2018 at 12:12 PM bkil <bkil.hu+Aq at gmail.com> wrote:

> Full-duplex still needs some work, but there is definite progress:
> http://www.ti.rwth-aachen.de/~taghizadehmotlagh/FullDuplex_Survey.pdf
>
> https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/TR-1.pdf
> https://sing.stanford.edu/fullduplex/
>
> https://spectrum.ieee.org/tech-talk/telecom/wireless/new-full-duplex-radio-chip-transmits-and-receives-wireless-signals-at-once
> http://fullduplex.rice.edu/research/
>
> On Mon, Aug 27, 2018 at 9:46 PM Jonathan Morton <chromatix99 at gmail.com>
> wrote:
>
>> > On 27 Aug, 2018, at 10:11 pm, Bob McMahon <bob.mcmahon at broadcom.com>
>> wrote:
>> >
>> > I guess my question is can a WiFi transmitting device rely on primarily
>> energy detect and mostly ignore the EDCA probability game and rather search
>> for (or predict) unused spectrum per a time interval such that its digital
>> signal has enough power per its observed SNR?   Then detect "collisions"
>> (or, "superposition cases" per the RX not having sufficient SINR) via
>> inserting silent gaps in its TX used to sample ED, i.e. run energy detect
>> throughout the entire transmission?  Or better, no silent gaps, rather
>> detect if there is superimposed energy on it's own TX and predict a
>> collision (i.e. RX probably couldn't decode its signal) occurred?  If
>> doable, this seems simpler than having to realize centralized (or even
>> distributed) media access algorithms a la, TDM, EDCA with ED, token buses,
>> token rings, etc. and not require media access coordination by things like
>> APs.
>>
>> The software might be simpler, but the hardware would need to be
>> overspecified to the point of making it unreasonably expensive for consumer
>> devices.
>>
>> Radio hardware generally has a significant TX/RX turnaround time,
>> required for the RX deafening circuits to disengage.  Without those
>> deafening circuits, the receivers would be damaged by the comparatively
>> vast TX power in the antenna.
>>
>> So in practice, it's easier to measure SNR at the receiver, or indirectly
>> by observing packet loss by dint of missing acknowledgements returned to
>> the transmitter.
>>
>>  - Jonathan Morton
>>
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