From rbt at alum.mit.edu  Wed Dec 23 14:27:14 2009
From: rbt at alum.mit.edu (Brough Turner)
Date: Wed, 23 Dec 2009 14:27:14 -0500
Subject: [Rooftops] NxtGen mesh to support an end run around ILECs?
Message-ID: <4B326F12.8050209@alum.mit.edu>

If there is anyone left on this list who is still interested in Internet 
connectivity or wireless mesh networks, I'm an engineer/ entrepreneur 
investigating the feasibility of doing a wireless end run around the 
duopoly here in the US.  So far this is an investigation only - I'm not 
to the point of a business plan, but I'm getting rather optimistic. 

I'm looking for useful people to bounce ideas off.  I'm also running an 
event during IAP:  http://student.mit.edu/searchiap/iap-a194.html

My theses: 

There is a 20x cost difference between Internet connectivity at a 
competitive IXP like One Summer Street in Boston and buildings even one 
block away.  This creates enough of a gap to support a services business 
based on a freemium business model and BYOC (bring your own capital, 
i.e. subscribers purchase mesh nodes).

There's the potential for a 100x increment in mesh performance, at least 
in dense urban areas, because:
   While 5 GHz is absorbed by masonry, there is significant difference 
in propagation through air or glass btwn 5 GHz, 2.4 GHz or 700 MHz.
   MIMO makes 5 GHz more valuable than lower frequencies, at least in 
dense urban areas where MIMO is effective.
   There's vastly more spectrum available at 5 GHz (11 - 40 MHz channels 
versus 3 - 20 MHz channels at 2.4 GHz).
   DSP controlled beamforming significantly improves MIMO performance
   DSP controlled beamforming achieves the performance and SDMA 
advantages of highly directional antennas without requiring professional 
or enthusiast installers.
   802.11n today and 802.11ac in the future are leading silicon vendors 
to incorporate ever higher order MIMO and software controlled beamforming.

If there is anyone here on this list who's interested in talking, my 
contact info is below.  (You're also welcome to attend the January 27th 
IAP event).

Thanks,
Brough

Brough Turner
Ashtonbrooke.com
Mobile: +1 617 285-0433  Skype: brough
Also:  broughturner at gmail.com
Web:   http://www.broughturner.com/
Blog:  http://blogs.broughturner.com/




From michael at mkassner.net  Thu Dec 24 09:48:43 2009
From: michael at mkassner.net (Michael Kassner)
Date: Thu, 24 Dec 2009 08:48:43 -0600
Subject: [Rooftops] I assume
Message-ID: <214708130912240648nb8546dbw86dbca9185620f2f@mail.gmail.com>

Hello, Mr. Turner

Interesting concept that is already playing out. I assume you are aware of
your fellow MIT alumni that are doing this exact thing in San Francisco:

http://sf.meraki.com/

Kind regards,

Michael P. Kassner
MKassner Net

On Wed, Dec 23, 2009 at 1:27 PM, Brough Turner <rbt at alum.mit.edu> wrote:

> If there is anyone left on this list who is still interested in Internet
> connectivity or wireless mesh networks, I'm an engineer/ entrepreneur
> investigating the feasibility of doing a wireless end run around the
> duopoly here in the US.  So far this is an investigation only - I'm not
> to the point of a business plan, but I'm getting rather optimistic.
>
> I'm looking for useful people to bounce ideas off.  I'm also running an
> event during IAP:  http://student.mit.edu/searchiap/iap-a194.html
>
> My theses:
>
> There is a 20x cost difference between Internet connectivity at a
> competitive IXP like One Summer Street in Boston and buildings even one
> block away.  This creates enough of a gap to support a services business
> based on a freemium business model and BYOC (bring your own capital,
> i.e. subscribers purchase mesh nodes).
>
> There's the potential for a 100x increment in mesh performance, at least
> in dense urban areas, because:
>   While 5 GHz is absorbed by masonry, there is significant difference
> in propagation through air or glass btwn 5 GHz, 2.4 GHz or 700 MHz.
>   MIMO makes 5 GHz more valuable than lower frequencies, at least in
> dense urban areas where MIMO is effective.
>   There's vastly more spectrum available at 5 GHz (11 - 40 MHz channels
> versus 3 - 20 MHz channels at 2.4 GHz).
>   DSP controlled beamforming significantly improves MIMO performance
>   DSP controlled beamforming achieves the performance and SDMA
> advantages of highly directional antennas without requiring professional
> or enthusiast installers.
>   802.11n today and 802.11ac in the future are leading silicon vendors
> to incorporate ever higher order MIMO and software controlled beamforming.
>
> If there is anyone here on this list who's interested in talking, my
> contact info is below.  (You're also welcome to attend the January 27th
> IAP event).
>
> Thanks,
> Brough
>
> Brough Turner
> Ashtonbrooke.com
> Mobile: +1 617 285-0433  Skype: brough
> Also:  broughturner at gmail.com
> Web:   http://www.broughturner.com/
> Blog:  http://blogs.broughturner.com/
>
>
> _______________________________________________
> Rooftops mailing list
> Rooftops at mit.edu
> http://mailman.mit.edu/mailman/listinfo/rooftops
>
>


From rbt at alum.mit.edu  Tue Dec 29 18:30:06 2009
From: rbt at alum.mit.edu (Brough Turner)
Date: Tue, 29 Dec 2009 18:30:06 -0500
Subject: [Rooftops] I assume
In-Reply-To: <214708130912240648nb8546dbw86dbca9185620f2f@mail.gmail.com>
References: <214708130912240648nb8546dbw86dbca9185620f2f@mail.gmail.com>
Message-ID: <4B3A90FE.80006@alum.mit.edu>

Thanks Michael,

Yes, I'm aware of Meraki.  I haven't actually spoken to anyone there 
(Can you introduce me?), but I have read the rooftop papers and gone 
though the current Meraki website.  The goals are similar, but my 
interest differs in at least two regards.  

First I'm interested in Internet connectivity including the backbone 
connection ("Internet transit" has a recurring monthly cost, perhaps 20x 
to 50x less than what you pay today, but a monthly cost none-the-less). 
 That implies a service (versus a products business).  For this, I'm 
evaluating a freemium business model that could result in a sustainable 
business, i.e. one that wouldn't require government grants or the 
continued persistence of volunteer community enthusiasts.

Second, the next big increment in mesh performance will come by getting 
away from omni directional antennas and going to highly focused point to 
point links.  This is becoming very feasible (and consumer installable) 
with smart antenna technology.  Even without a push from me, MIMO plus 
beamforming will show up in enterprise (and then consumer) devices in 
the next 2-4 years.  (Ruckus Wireless has a first cut today).  Roofnet 
(and Meraki at least to start) focused at the mesh network protocol 
layer.  The next increment in performance will come from smart antenna 
technology.

Unfortunately, I won't be fully engaged again until  January 3rd as I'm 
out of town with family...  I apologize for slow or no responses prior 
to then.

Thanks,
Brough

Mobile: +1 617 285-0433   Skype: brough
Blog: http://blogs.broughturner.com/



Michael Kassner wrote:
> Hello, Mr. Turner
>
> Interesting concept that is already playing out. I assume you are 
> aware of your fellow MIT alumni that are doing this exact thing in San 
> Francisco:
>
> http://sf.meraki.com/
>
> Kind regards,
>
> Michael P. Kassner
> MKassner Net
>
> On Wed, Dec 23, 2009 at 1:27 PM, Brough Turner <rbt at alum.mit.edu 
> <mailto:rbt at alum.mit.edu>> wrote:
>
>     If there is anyone left on this list who is still interested in
>     Internet
>     connectivity or wireless mesh networks, I'm an engineer/ entrepreneur
>     investigating the feasibility of doing a wireless end run around the
>     duopoly here in the US.  So far this is an investigation only -
>     I'm not
>     to the point of a business plan, but I'm getting rather optimistic.
>
>     I'm looking for useful people to bounce ideas off.  I'm also
>     running an
>     event during IAP:  http://student.mit.edu/searchiap/iap-a194.html
>
>     My theses:
>
>     There is a 20x cost difference between Internet connectivity at a
>     competitive IXP like One Summer Street in Boston and buildings
>     even one
>     block away.  This creates enough of a gap to support a services
>     business
>     based on a freemium business model and BYOC (bring your own capital,
>     i.e. subscribers purchase mesh nodes).
>
>     There's the potential for a 100x increment in mesh performance, at
>     least
>     in dense urban areas, because:
>       While 5 GHz is absorbed by masonry, there is significant difference
>     in propagation through air or glass btwn 5 GHz, 2.4 GHz or 700 MHz.
>       MIMO makes 5 GHz more valuable than lower frequencies, at least in
>     dense urban areas where MIMO is effective.
>       There's vastly more spectrum available at 5 GHz (11 - 40 MHz
>     channels
>     versus 3 - 20 MHz channels at 2.4 GHz).
>       DSP controlled beamforming significantly improves MIMO performance
>       DSP controlled beamforming achieves the performance and SDMA
>     advantages of highly directional antennas without requiring
>     professional
>     or enthusiast installers.
>       802.11n today and 802.11ac in the future are leading silicon vendors
>     to incorporate ever higher order MIMO and software controlled
>     beamforming.
>
>     If there is anyone here on this list who's interested in talking, my
>     contact info is below.  (You're also welcome to attend the January
>     27th
>     IAP event).
>
>     Thanks,
>     Brough
>
>     Brough Turner
>     Ashtonbrooke.com
>     Mobile: +1 617 285-0433  Skype: brough
>     Also:  broughturner at gmail.com <mailto:broughturner at gmail.com>
>     Web:   http://www.broughturner.com/
>     Blog:  http://blogs.broughturner.com/
>
>
>     _______________________________________________
>     Rooftops mailing list
>     Rooftops at mit.edu <mailto:Rooftops at mit.edu>
>     http://mailman.mit.edu/mailman/listinfo/rooftops
>
>

-- 

Thanks,
Brough

Brough Turner
Ashtonbrooke.com
Mobile: +1 617 285-0433  Skype: brough
Also:  broughturner at gmail.com
Web:   http://www.broughturner.com/
Blog:  http://blogs.broughturner.com/




From foner at media.mit.edu  Tue Dec 29 20:54:41 2009
From: foner at media.mit.edu (Lenny Foner)
Date: Tue, 29 Dec 2009 20:54:41 -0500 (EST)
Subject: [Rooftops]  I assume
In-Reply-To: <4B3A90FE.80006@alum.mit.edu> (message from Brough Turner on Tue, 
	29 Dec 2009 18:30:06 -0500)
Message-ID: <200912300154.UAA27134@out-of-band.media.mit.edu>

Every time I think about this sort of thing, I worry about latency.
An RF mesh tends to have a lot of hops.  Even if you start transmitting
on the next hop as soon as you can, you still have to get enough of a
packet preamble to know which of your (virtual?) beams to send it on.
That means that each hop adds some amount of latency that's hard to
get around, even if it's only a few bits of header (and not, say,
all the bits of a large packet).

Mitigating factors of course include:
(a) Assume users aren't using ssh.  (I do, but I'm a fossil.)
    [And assume that Skype traffic will instead use the real trunks?
    Ick.  So there's a case millions use where real latency will
    really matter.  Simple web browsing may be one of them, too, alas.]
(b) Any increment in bits/second on the links shortens the amount of
    time you have to wait for that preamble, so speak as fast as you
    can.  You'd want that anyway, of course. :)
(c) Any increment in hop length helps.  Of course, this has a direct
    bearing on (b).  Even with beamforming, at some point you'll hit
    annoying limits (or obstacles :).
(d) Assign flow tags that can be abbreviated to a very few bits, and
    preface packets with them.  Won't help you for a coast-to-coast
    UDP query (think DNS), but those are rare.  Will help you for
    virtual circuits, which describe most of the cases where latency
    gets noticeable (ssh, voice, etc).  This is analogous to Van
    Jacobson compression back when 9600 bps modems were all the rage;
    the idea would be to use Huffman coding (for example) to identify
    streams, with some hacks for flushing old state so you only have
    to identify a few (dozens? hundreds?) of streams per node at any
    given time.  I'll bet a careful reading of the literature would be
    rewarding; I'd be shocked if there isn't a ton of research on this
    sort of thing.  This must be Cisco's bread & butter.  Zigbee might
    also be rewarding to study for whatever it does; have you?

Doing (d), in particular, assumes you can get bits as they come in
from the RF system---not after they've all be received and a packet
checksum has been computed.  Does typical 802.whatever HW allow this
under any circumstances?  Possibly, given Airsnort et al.  And what
are the implications of noise in the channel?  [Maybe you start
forwarding as soon as you think you know where the packet's going,
with an oops-never-mind-abort if some really short & simple flow
checksum comes along later and you realize you had noise, and another
never-mind-I-really-blew-it if the packet checksum fails at the end.
And if noise is rare, maybe you just don't bother letting go of the
channel early & just let the receiver drop it if a checksum's wrong.
But probably that means one error early on ripples through a -lot- of
hops before everyone abandons it, so it could cost you bandwidth.]

I also wonder if it could ever pay off to have that preamble be
a different RF modulation---using more bandwidth or more power or
whatever to get it out faster, in the assumption that even though
you're degrading the rest of the channel slightly, the decrease in
latency is worth it.  May not be worth the added RF complexity,
though.  [But it might:  20 bits of header means 20 bits of delay
per hop, plus one bit of delay per hop for the payload, assuming
optimality.  So either making that header shorter, or speaking it
faster, might have a big multiplier on end-to-end latency.  Absolutely
don't use uncompressed TCP!  40 bytes/hop, minimum.  Bleah.]