<div dir="ltr">Minimizing power is rule #2 per Paul Banan. <br><br><div>SOME KINDERGARTEN RULES (written in 1994)</div><div><br></div><div> To take the fullest advantage of our new technology with its sharing</div><div> of a common resource requires that our smart transmitters and</div><div> receivers cooperate. This may sound complicated, but the rules to make</div><div> maximum effective use of the shared band are simple -- primarily a</div><div> matter of common decency in sharing resources. The rules are somewhat</div><div> similar to those you learned in kindergarten, assuming you lived in a</div><div> tough neighborhood.</div><div><br></div><div> Rule #1. Keep away from the big bullies in the playground. (Avoid the</div><div> strongest signals.)</div><div><br></div><div> Rule #2. Share your toys. (<span style="background-color:rgb(255,255,0)">Minimize your transmitted power. Use the</span></div><div><span style="background-color:rgb(255,255,0)"> shortest hop distances feasible. Minimize average power density per</span></div><div><span style="background-color:rgb(255,255,0)"> Hertz.)</span></div><div><br></div><div> Rule #3. If you have nothing to say, keep quiet.</div><div><br></div><div> Rule #4. Don't pick on the big kids. (Don't step on strong signals.</div><div> You're going to get clobbered.)</div><div><br></div><div> Rule #5. If you feel you absolutely must beat up somebody, be sure to</div><div> pick someone smaller than yourself. (Now this is a less obvious one,</div><div> as weak signals represent far away transmissions; so your signals will</div><div> likely be attenuated the same amount in the reverse direction and</div><div> probably not cause significant interference.)</div><div><br></div><div> Rule #6. Don't get too close to your neighbor. Even the weakest</div><div> signals are very strong when they are shouted in your ear.</div><div><br></div><div> Rule #7. Lastly, don't be a cry baby. (If you insist on using obsolete</div><div> technology that is highly sensitive to interfering signals, don't</div><div> expect much sympathy when you complain about interfering signals in a</div><div> shared band.)<br><br>Bob</div><br class="gmail-Apple-interchange-newline"></div><br><div class="gmail_quote"><div dir="ltr">On Thu, Aug 30, 2018 at 12:12 PM bkil <<a href="http://bkil.hu">bkil.hu</a>+<a href="mailto:Aq@gmail.com">Aq@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Full-duplex still needs some work, but there is definite progress:</div><div><a href="http://www.ti.rwth-aachen.de/~taghizadehmotlagh/FullDuplex_Survey.pdf" target="_blank">http://www.ti.rwth-aachen.de/~taghizadehmotlagh/FullDuplex_Survey.pdf</a><br></div><div><a href="https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/TR-1.pdf" target="_blank">https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/TR-1.pdf</a><br></div><div><a href="https://sing.stanford.edu/fullduplex/" target="_blank">https://sing.stanford.edu/fullduplex/</a></div><div><a href="https://spectrum.ieee.org/tech-talk/telecom/wireless/new-full-duplex-radio-chip-transmits-and-receives-wireless-signals-at-once" target="_blank">https://spectrum.ieee.org/tech-talk/telecom/wireless/new-full-duplex-radio-chip-transmits-and-receives-wireless-signals-at-once</a><br></div><a href="http://fullduplex.rice.edu/research/" target="_blank">http://fullduplex.rice.edu/research/</a><br><br><div class="gmail_quote"><div dir="ltr">On Mon, Aug 27, 2018 at 9:46 PM Jonathan Morton <<a href="mailto:chromatix99@gmail.com" target="_blank">chromatix99@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">> On 27 Aug, 2018, at 10:11 pm, Bob McMahon <<a href="mailto:bob.mcmahon@broadcom.com" target="_blank">bob.mcmahon@broadcom.com</a>> wrote:<br>
> <br>
> 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.<br>
<br>
The software might be simpler, but the hardware would need to be overspecified to the point of making it unreasonably expensive for consumer devices.<br>
<br>
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.<br>
<br>
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.<br>
<br>
- Jonathan Morton<br>
<br>
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