[OLPC Networking] [Server-devel] RSSI value questions

[V. Michael Bove Jr.]

The patent, like our audio process, is about sending a particular  
signal whose center can be precisely localized even in noisy,  
reverberant environments, and then using pairwise exchange of data to  
do localization even when initial delays are unknown.  In other words,  
a message goes out telling everyone to send his signal; each unit  
backs off a random amount of time to avoid collisions and then  
transmits (but starts listening immediately); pairs of units exchange  
the delay between when a unit heard itself and when it heard the  
other; the sum of those numbers is twice the time of flight with the  
delay cancelled out.
--M.

On Apr 6, 2008, at 7:27 PM, Ryan Crawford Comeaux wrote:
> Michael -
>
> Do you think the patent you're referring to would be a significant  
> roadblock in implementing this system using wifi signal strength  
> measurements?  The few patents that I've seen (though I haven't been  
> actively searching) seem to be designed with a system that has a  
> "plurality of receiving stations with known locations" in mind,  
> which wouldn't affect things here, considering this would be a  
> system with purely unknown locations.
>
> To everyone reading -
>
> I agree that the XS isn't necessary, though it would allow for more  
> applications, security being one that was pointed out earlier.   
> Also, by attaching a GPS antenna to the server, an approximate GPS  
> location could be assigned to nodes within the network.
>
> I think my initial question regarding whether or not the hardware is  
> currently capable of implementing this system overall is a  
> definitive "Yes," so I should be completing my proposal this  
> evening.  I'll post it to the three mailing lists we've been having  
> this discussion on.  Please feel free to rip it to shreds, provide  
> constructive criticism, or wish me luck as you see fit :)
>
> - Crawford