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

rihoward1 at gmail.com rihoward1 at gmail.com
Mon Jan 25 11:07:26 EST 2010


Looks like you have the incorrect link for the Openbts.org.  
The correct link is now http://openbts.sourceforge.net/

/Robert H.

rihoward1 at gmail.com

linux - the best things in life are free

On Jan 25, 2010, at 7:42 AM, Luke Kenneth Casson Leighton wrote:

> dear olpc devel people,
> i've been doing some research and found a couple of companies with SDR
> R.F. front-end ICs.  one is 40nm and is so tiny that it will only cost
> about $2, mass-produced.  also thanks to being in 40nm, the speed of
> the (SoC / embedded) ARM9 core is so fast that it's perfectly capable
> of handling multiple protocols.  as you're no doubt aware,
> Software-Defined Radio has been "full of promise" for quite some time
> as "The" low-cost transceiver option, but it's only recently that the
> speed of embedded ICs has gone up enough and the geometry small enough
> to bring the cost down into the affordable range.
> key to making SDR "work" is of course having the software :)  but,
> i've found a company who already have GSM through EDGE; there's
> http://openbts.org and also of course there's the gnu-radio project
> which has produced part of 802.11, amongst other things.  ( but,
> remember: the nice thing about the 2.4ghz and 5ghz bands is that you
> don't _actually_ need to do 802.11, you can in fact just use the
> entire set of bands to do absolutely anything you want.  and, with
> SDR, you _could_ do anything you want).
> the neat thing about SDR is that the _same_ solution replaces:
> * a WIFI chipset ($10)
> * a GSM chipset ($12 lowest i've found in 100k+ volumes)
> * or a 3G chipset ($30 lowest i've heard about in mass-volume)
> * a GPS chipset ($6 and that's again an SDR solution,
>   you need a DSP to translate; $12 for dedicated chipset)
> * a WIMAX chipset (haven't even looked this up, but estimate $20)
> * a DVB TV chipset (approx $5 and again that's an SDR solution)
> * an FM Radio chipset (don't know its cost, don't honestly care!)
> i repeat.  all those can be replaced with _one_ i repeat _one_ single
> solution, costing roughly... $12, if that.
> issues which need to be resolved:
> * paying for a minimum of 8 40nm 10in wafers (appx 5000 ICs per wafer)
> @ $0.50 ea, running the test vectors @ $0.75 ea, packaging @ $0.50 ea
> it works out roughly at $2.00 times 40,000.
> * creating the PCB with RF MEMS filters
> (http://en.wikipedia.org/wiki/RF_MEMS) and other assorted components,
> coax connectors for antenna, the remaining components are going to be
> somewhere around $10.
> * license compliance and Certification in the countries in which the
> final modem is deployed (remember that if frequencies other than
> 2.4ghz or 5ghz @ greater than 100mW are used or 400mW in Hong Kong
> then licenses are NOT required)
> even with these issues to be costed out and resolved, i wanted to ask:
> * is the incredible low-cost and flexibility of SDR worth pursuing?
> * is the current Marvell 88688 "proprietary firmware" 802.11 blob
> _that_ acceptable / accepted?
> * is the possibility of being able to run an XO up a pole (or placed
> at the top of any tall building) and have it _be_ the GSM or WIMAX
> base station for an entire town or village and the surrounding
> countryside for miles around the kind of thing that is attractive to,
> and useful to the aims of the OLPC project, or not?
> also - one thing that also would help to have an answer to : if
> answers above turn out to be resounding "yes", what's next?  who makes
> the decision?
> l.
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