Re: [Cerowrt-devel] [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:

> The ~10K is coming from empirical measurements where all aggregation
> technologies are disabled, i.e. only one small IP packet per medium
> arbitration/access and where there is only one transmitter and one
> receiver.  900Mb/sec is typically a peak-average throughput measurement
> where max (or near max) aggregation occurs, amortizing the access overhead
> across multiple packets.

so 10K is minimum size packets being transmitted?or around 200 transmissions/sec 
(plus 200 ack transmissions/sec)?

> Yes, devices can be hidden from each other but not from the AP (hence the
> use of RTS/CTS per hidden node mitigation.) Isn't it the AP's view of the
> "carrier state" that matters (at least in infrastructure mode?)  If that's
> the case, what about a different band (and different radio) such that the
> strong signal carrying the data could be separated from the the BSSID's
> "carrier/energy state" signal?

how do you solve the interference problem on this other band/radio? When you 
have other APs in the area operating, you will have the same problem there.

David Lang

> Bob
>
> On Mon, Jun 27, 2016 at 12:40 PM, David Lang <david@lang.hm> wrote:
>
>> 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
>>
>