OLPC hardware: what if there was an SDR modem / chipset?

[C. Scott Ananian]

On Mon, Jan 25, 2010 at 3:35 PM, Luke Kenneth Casson Leighton
<lkcl at lkcl.net> wrote:
>  this stuff is juuust at the point where it's ready for
> mass-production.  ordinarily this stuff would be snapped up by e.g.
> qualcomm etc. but i believe this is going to be different: the
> companies involved are ... well, they're fully aware that it's
> disruptive technology.
>
>  the important thing is therefore to make an introduction into markets
> which DO NOT conflict with "The Big Boys" i.e. introduce finished
> useable modems into third world countries, emerging markets etc. which
> "The Big Boys" have completely written off due to lack of profitable
> opportunities.
>
>  in other words, because the base stations are so expensive and will
> either get eaten by cows or be stripped down for spare parts and the
> copper wire (let's be honest _and_ cynical at the same time, why
> not...) third world and emerging markets won't _get_ any WIMAX, 3G or
> LTE base stations.
>
>  so, there's therefore a wide-open opportunity to deploy SDR modems
> which can be reprogrammed as a poor-man's Base Station in a pinch,
> mayybe have a better external antenna attached to it.  if the on-board
> DSP and ARM CPU can't cope with more than 4 simultaneous users _wow_
> so what, big damn deal, that's 4 more users than they've ever had in
> the area before _and_ there's no data charges.

I'm not sure why you think this is a radical idea.  OLPC is sitting 1
floor above Vanu (http://vanu.com/) which has spent 12 years working
on software-defined radio for base station applications.  It turns out
its not as easy (or cheap) as all that, when you get down to it.  Vanu
ended up bringing in new management when the recession hit, new
management which thought it was a good idea to reimplement everything
from scratch on a Windows platform Just Because, and now I'm working
with the best and brightest formerly of Vanu at another company.

Since I'm not working for OLPC any more, I can be a bit brusque:
people seem to have this savior complex about OLPC, projecting all of
their radical fantasies on it.  In some places, that leads to lawsuits
even, in the idea that OLPC's grand vision must have a correspondingly
large company and $$$ behind it which could somehow be extracted.  In
truth, OLPC is very very very small, and can barely afford to manage
802.11 networks in its deployments, let alone anything more
complicated.  OLPC is still around because (and only because) they've
managed to shrink their vision from the "7 new things" to the 1 or 2
new things they can actually afford to develop and field.

Good luck with your SDR dreams.  I think the most you can expect from
OLPC is that, *if* the 10 improbable things you described actually
come to pass, OLPC will someday include a miniPCI slot so that they
can plug in your magic daughtercard.  (And even this step would be
horrifically expensive, in terms of retooling costs & etc.)  But
that's not going to happen until *after* that magic daughtercard is in
mass production.  So get busy!  It's only a couple months work, right?
  --scott

ps: It might also be worth your time to study manufacturing processes
in detail.  The "dozen  RF connectors" you describe *by themselves*
add a significant amount to the cost of the product.  And you probably
need connectors even if just to connect your internal antennas -- and
getting *those* right is a battle in itself.  Have Richard and John
tell you about the struggle to get repeatable performance out of the
XO ears sometime.  It's very easy to be seduced by low per unit costs
of ICs to seriously underestimate the cost of the finished product.

-- 
                         ( http://cscott.net/ )