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

[dpreed@reed.com]

The actual issues of transmitting on multiple channels at the same time are quite minor if you do the work in the digital domain (pre-DAC).  You just need a higher sampling rate in the DAC and add the two signals together (and use a wideband filter that covers all the channels).  No RF problem.

Receiving multiple transmissions in different channels is pretty much the same problem - just digitize (ADC) a wider bandwidth and separate in the digital domain.  the only real issue on receive is equalization - if you receive two different signals at different receive signal strengths, the lower strength signal won't get as much dynamic range in its samples.

But in a LAN setup, the variability in signal strength is likely small enough that you can cover that with more ADC bits (or have the MAC protocol manage the station transmit power so that signals received at the AP are nearly the same power.

Equalization at transmit works very well when there is a central AP (as in cellular or normal WiFi systems).



On Thursday, June 23, 2016 4:28pm, "Bob McMahon" <bob.mcmahon@broadcom.com> said:

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> An AP per room/area, reducing the tx power (beacon range) has been my
> approach and has scaled very well.   It does require some wires to each AP
> but I find that paying an electrician to run some quality wiring to things
> that are to remain stationary has been well worth the cost.
> 
> just my $0.02,
> Bob
> 
> On Thu, Jun 23, 2016 at 1:10 PM, David Lang <david@lang.hm> wrote:
> 
>> Well, just using the 5GHz DFS channels in 80MHz or 160 MHz wide chunks
>> would be a huge improvement, not many people are using them (yet), and the
>> wide channels let you get a lot of data out at once. If everything is
>> within a good range of the AP, this would work pretty well. If you end up
>> needing multiple APs, or you have many stations, I expect that you will be
>> better off with more APs at lower power, each using different channels.
>>
>> David Lang
>>
>>
>>
>>
>> On Thu, 23 Jun 2016, Bob McMahon wrote:
>>
>> Date: Thu, 23 Jun 2016 12:55:19 -0700
>>> From: Bob McMahon <bob.mcmahon@broadcom.com>
>>> To: Dave Taht <dave.taht@gmail.com>
>>> Cc: make-wifi-fast@lists.bufferbloat.net,
>>>     "cerowrt-devel@lists.bufferbloat.net"
>>>     <cerowrt-devel@lists.bufferbloat.net>
>>> Subject: Re: [Make-wifi-fast] more well funded attempts showing market
>>> demand
>>>     for better wifi
>>>
>>>
>>> hmm, I'm skeptical.   To use multiple carriers simultaneously is difficult
>>> per RF issues.   Even if that is somehow resolved, to increase throughput
>>> usually requires some form of channel bonding, i.e. needed on both sides,
>>> and brings in issues with preserving frame ordering.  If this is just
>>> channel hopping, that needs coordination between both sides (and isn't
>>> simultaneous, possibly costing more than any potential gain.)   An AP only
>>> solution can use channel switch announcements (CSA) but there is a cost to
>>> those as well.
>>>
>>> I guess don't see any break though here and the marketing on the site
>>> seems
>>> to indicate something beyond physics, at least the physics that I
>>> understand.  Always willing to learn and be corrected if I'm
>>> misunderstanding things.
>>>
>>> Bob
>>>
>>> On Wed, Jun 22, 2016 at 10:18 AM, Dave Taht <dave.taht@gmail.com> wrote:
>>>
>>> On Wed, Jun 22, 2016 at 10:03 AM, Dave Taht <dave.taht@gmail.com> wrote:
>>>>
>>>>>
>>>>>
>>>> https://www.kickstarter.com/projects/portalwifi/portal-turbocharged-wifi?ref=backerkit
>>>>
>>>>>
>>>>> "Portal is the first and only router specifically engineered to cut
>>>>> through and avoid congestion, delivering consistent, high-performance
>>>>> WiFi with greater coverage throughout your home.
>>>>>
>>>>> Its proprietary spectrum turbocharger technology provides access to
>>>>> 300% more of the radio airwaves than any other router, improving
>>>>> performance by as much as 300x, and range and coverage by as much as
>>>>> 2x in crowded settings, such as city homes and multi-unit apartments"
>>>>>
>>>>> It sounds like they are promising working DFS support.
>>>>>
>>>>
>>>> It's not clear what chipset they are using (they are claiming wave2) -
>>>> but they are at least publicly claiming to be using openwrt. So I
>>>> threw in enough to order one for september, just so I could comment on
>>>> their kickstarter page. :)
>>>>
>>>> I'd have loved to have got in earlier (early shipments are this month
>>>> apparently), but those were sold out.
>>>>
>>>>
>>>>
>>>> https://www.kickstarter.com/projects/portalwifi/portal-turbocharged-wifi/comments
>>>>
>>>>
>>>>
>>>>> --
>>>>> Dave Täht
>>>>> Let's go make home routers and wifi faster! With better software!
>>>>> http://blog.cerowrt.org
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Dave Täht
>>>> Let's go make home routers and wifi faster! With better software!
>>>> http://blog.cerowrt.org
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>>>>
>>>>
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