I think you would be better taking your existing hardware, which must be somewhat custom to begin with (since it works over wifi) and use something like a HopeRF module (http://www.hoperf.com/) or similar. HopeRF has transceivers with power output up 100mW, data rates up to 256kbps, and a choice of 4 different bands (315, 433, 868, 915). This sounds like it would be a far easier choice to incorporate into your already-working system than hacking OsmocomBB-capable phones.
There is a lot of development from many different companies in this area and quite a bit of hacker activity as well.
Scott
On Thu, Sep 1, 2011 at 7:11 AM, Paul Gardner-Stephen <paul@servalproject.org
wrote:
Greetings all,
At the Serval Project we have created a mobile mesh telephony system that currently works over wifi.
From the outset, we have wanted to get it working on the ISM915 and/or ISM868 bands that are located adjacent to the GSM 850/900 frequency allocations.
My initial investigations and enquiries indicate that this should be possible by creative programming of the baseband processor in many models of phones. The trick, as I suspect you well know, is the difficulty in getting the information and tools required to reprogram these radios.
I am now in a position to potentially fund further work on this.
So, as the open-source group with the most experience reprogramming baseband radios, what is the feasibility of creating a proof-of-concept using the types of phones you already work with to send and receive arbitrary data packets without reliance on a cell tower (even for time synchronisation)?
I know there are a lot of constraints and problems, but I am most interested in creative solutions that can get us to a working prototype, however crude, that can be used to demonstrate the feasibility of what I am proposing.
If this discussion is off-topic here, I am happy to hold the conversation at the serval-project-developers google group, but I am equally comfortable with it continuing here.
Thanks in advance, Paul Gardner-Stephen. Shuttleworth Telecommunications Fellow at Flinders University.