You may want to check this out: http://wush.net/trac/rangepublic/wiki At first glance, it looks like one could set up exactly what you're after. -Pete On Apr 9, 2013, at 5:21 AM, RussellMc wrote: > I'm interested in knowing what it would take at a minimum to enable > GSM cellphone to cellphone comms among a limited number of phones in > the absence of a traditional cell-site structure. ie add your own > cell-site if necessary. > > That could be tightened up somewhat to say GSM 2G platform or better > and could be just SMS, just voice, and ideally SMS and voice and data. > > Either all phones involved need to be capable of peer to peer > communications, or a cell site / base station "cellphone tower" is > needed. > > Has anyone here any experience in this area or can comment on the > feasibility of using existing in-phone GSM hardware to meet this need. > > Assume regulatory issues are not of concern (even though in many cases > they will be). > A hypothetical example application might be a "flying cell site" that > is used in look-down mode from high altitudes to provide search and > rescue radio communications in rugged terrain allowing the use of > cellphones by ground parties - which would otherwise be ineffective > in cell-site-less valleys. If you can talk to the cellphone equipped > hiker lying incapacitated with a broken leg, so much the better. (An > extremely experienced wilderness veteran died some years ago in NZ > after lying incapacitated for several weeks after a fall and not being > found until too late. He should have been carrying a locator beacon, > but with a flying cellsite a $25 phone would have saved his life. This > example would easily support the basic "$1000 solution" below > (although it would usually done for even more in that application) but > some applications would benefit from lowest possible cost. > > > Russell > > > > "Resources:" > > The minimum arrangement that I'm currently aware of is to implement a > cell site (or "cellphone tower") using a SDR (Software defined radio) > and a computer of some sort. Almost any linux box can be used and I've > recently read of people doing it with a Raspberry Pi. > > The probably most accessible, but not necessarily the best, solution > is the use of Open BTS (Open Base Transceiver Station) free software > (refs below) with a suitable SDR (Software Defined Radio). > > The usual hardware starting point is the open source USRP1 - User > Software Defined Radio transceiver. > A version of this, the USRPB100 can be bought fully assembled from > Ettus Research for $US650 retail. > Various Ettus Research SDR's here > https://www.ettus.com/product/category/USRP_Bus_Series > Add an eg Raspberry Pi and probably a GPS timing source, basic power > supply and aerial(s) and you have a workable base for around $US1000 > (assuming your time is worth zilch). > > That's a good start , but cheaper still would be better. > > _____________________ > > Android SDR anyone :-) > Agh: That opened up a whole new line of thought. eg Realtek RTL2832U > DVB stick gives you an SDR control core for under $20. > Looks like it could handle the receive size OK. > Transmit? > http://wiki.spench.net/wiki/RTL2832U > http://www.hamradioscience.com/forum/discussion/88/setting-up-your-rtl283= 2u-dongle-for-sdr-use/p1 > http://sdr.osmocom.org/trac/wiki/rtl-sdr > http://dx.com/p/rtl2832u-r820t-mini-dvb-t-dab-fm-usb-digital-tv-dongle-bl= ack-170541 > > __________________ > > Open BTS - Wikipedia http://en.wikipedia.org/wiki/OpenBTS > > OpenBTS (Open Base Transceiver Station) is a software-based GSM access > point, allowing standard GSM-compatible mobile phones to be used as > SIP endpoints in Voice over IP (VOIP) networks. OpenBTS is the first > free software implementation of the lower three layers of the > industry-standard GSM protocol stack. It is written in C++ and > released as free software under the terms of version 3 of the GNU > Affero General Public License (AGPL). > > Good GSM / Open BTS video 5m:34 > http://www.youtube.com/watch?v=3DZoWKYJ1ATeE&feature=3Dplayer_embedded > > USRP Wikipedia > http://en.wikipedia.org/wiki/Universal_Software_Radio_Peripheral > > USRP1 circuit diagram > http://code.ettus.com/redmine/ettus/attachments/download/209/usrp1.pdf > http://www.tcmaker.org/wiki/doku.php?id=3Dhamradio:ettus_research_= usrp1 > > USRP1 for sale $700 > https://www.ettus.com/product/details/USRP-PKG > > The USRP1 is the original Universal Software Radio Peripheral=99 > hardware (USRP) that provides entry-level RF processing capability. It > is intended to provide software defined radio development capability > for cost-sensitive users and applications. The architecture includes > an Altera Cyclone FPGA, 64 MS/s dual ADC, 128 MS/s dual DAC and USB > 2.0 connectivity to provide data to host processors. A modular design > allows the USRP1 to operate from DC to 6 GHz. The USRP1 platform can > support two complete RF daughterboards. This feature makes the USRP > ideal for applications requiring high isolation between transmit and > receive chains, or dual-band dual transmit/receive operation. The > USRP1 can stream up to 8 MS/s to and from host applications, and users > can implement custom functions in the FPGA fabric. > _____________________________ > > 25C3 - Running your own GSM network. > Excellent 44 minute video. > http://www.youtube.com/watch?feature=3Dendscreen&NR=3D1&v=3De_9hPRF5fzA > http://events.ccc.de/congress/2008/wiki/GSM/ > > Harald Welte This presentation will mark the first public release of a > new GPL licensed Free Software project implementing the GSM fixed > network, including the various minimal necessary functionality of BSC, > MSC, HLR. It will introduce the respective standards and protocols, as > well as a short demonstration of an actual phone call between two > mobile phones registered to the base station. On the Ethernet/IP based > Internet, we are used to Free Software and general-purpose hardware. > The worlds second largest communications network GSM couldn=92t be any > more different. Even though the protocols are standardized and > publicly available at the ETSI, all implementations are highly-guarded > proprietary secrets of a few major players in the industry. The > hardware is even more closed, as there is not a single GSM subscriber > or base station chipset with even the least bit of publicly known > information. Nonetheless, in recent years there are a number of > different projects working on driving a wedge of Openness into this > world. You might have heard about other projects like the THC GSM > sniffer project (pure wireshark-like functionality) and OpenBTS (a > software defined radio based GSM base station interfacing with the > Asterisk VOIP server). This presentation is about yet another new GSM > related Open Source project. A project that follows the GSM specs more > closely and actually aims at interoperability with existing equipment > such as hardware BTS hooked up via S2M =85 > > _____________ > > Raspberry Pi Used To Replace A 30-Foot GSM Base Station And Create A > Working Mobile Network > Uses Open BTS and a Ettus SDR > Excellent links in discussion > http://techcrunch.com/2012/12/21/raspberry-pi-used-to-replace-a-30-foot-g= sm-base-station-and-create-a-working-mobile-network/ > > Open BTS source forge redirect page > http://wush.net/trac/rangepublic > This Trac is the home of the OpenBTS public release, a FOSS version > of Range Network's self-contained SDR/GSM/VoIP stack. > > GNU Radio > http://gnuradio.org/redmine/projects/gnuradio/wiki/OpenBTS > > Freeswitch > http://en.wikipedia.org/wiki/FreeSWITCH > FreeSWITCH is free and open source communications software for the > creation of voice and messaging products. It is licensed under the > Mozilla Public License (MPL), a free software license. Its core > library, libfreeswitch, is capable of being embedded into other > projects, as well as being used as a stand-alone application. > > Open BTS =96 superb You tube intro video for Open BTS > > Uses Ettus Research SPR USRP N210, ($US 1500 list) BUT could use eg > USRPB100 at $US650 list. > > Software Radio / OpenBTS - The Well Tempered Hacker Ep 4 > 16m 20s http://www.youtube.com/watch?v=3DpTb1_v8M6iA > > Range Networks > http://www.rangenetworks.com/ > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .