Open GSM Base Station

OpenBTS is an amazing project to build a GSM base station using open source software and hardware. It uses Asterisk as the back end, and can work with standard GSM handsets. The RF side is handled using the open hardware Universal Software Radio Peripheral, a software defined radio that be programmed to transmit and receive on GSM frequencies.

OpenBTS has been created by David Burgess and Harvind Samra, with lot of contributions from Raffi Sevlian.

Here is a photo of the equipment used at some recent field trials at Burning Man:

With this technology you can build your own small scale GSM network, using commodity handsets. This would be very nice for Village Telco type applications, and would have big range advantages over Wifi technology. Getting a license for spectrum is the challenge I guess.

Great to see some open technology in this area, and quite amazing that a small team can build their own GSM base station! Fantastic work guys….

8 thoughts on “Open GSM Base Station”

  1. Its cool to see this project moving forward. The USRP is a pretty cool piece of hardware, I can not wait to see what they do with second generation hardware.

  2. Hi Dave :),

    Pretty neat :).

    It seems to me that GSM coding/protocol could be legally used in any of the
    license free bands, 915MHz, 2.4GHZ or 5GHZ in the US. Of course the handsets would have to be modified, but then the WHOLE thing would be perfectly legal, at least in the US!

    Depending on brand handset hacking should not be too hard.

    And 1 watt transmit and low-noise preamp with a high antenna ought to reach quite a distance !

    I am surprised no one has done it already!

    warm regards to all.

  3. So, if the base GSM code and transivers are done with Software Defined Radio a “Client/Handset” culd also be done with Software Defined Radio and a generic radio hardware like USRP it culd be a nice option to extend the Village Telco with out WiFi

  4. Hi All,

    It kinda makes you want to have a “general purpose” radio transceiver. You just pick the frequency and protocol and away you go. I wonder what the “best” protocol might be? Given that “white spaces” are about to become open in the US, this could be a lot of fun.

    Could there be a cheap USRP? $50 USD?

    I suppose whatever protocol, it would need to be simple, low delay, and VERY rugged.

    I have always felt that LOW bit rates for greatly extended distances are really worth looking into. Given another 40 db useful sensitivity, amazing distances should be possible at least for simple text messaging.

    Some of the lower bit rate speex encodings should even make voice possible (with long delays) over very low bit rate channels.

  5. Yes I am also interested in the possibilities of low bandwidth text messaging. I have been thinking about a cell-phone size device that could message over HF, perhaps using mesh network protocols at very low bandwidths.

  6. Hi David,

    One low bandwidth method worth mentioning is PSK31 at least for “unexpected” messages [when the portable unit just listens]. When the “far end” is in sync with tne near end methods like 802.11b, but at a much lower bandwidth probably make more sense. AMTOR and their more recent ‘versions’ for example come to mind.

    Also at HF the ambient noise level is MUCH MUCH higher which means communication from a central site to the remote is easy, but communication from the remote, assuming the remote is a small pocket carried unit, to the central site is VERY difficult.

    If I were going to design a new product, I think the 915 MHz band with some of the recent ‘protocol enhancements’ might be worth a serious look.

    I believe one pager company used it’s licensed frequency for communication to the pager and 915MHz unlicensed for communication from the pager to the hilltop paging transmitter site with pretty good results.

    warm regards,
    John

  7. Hi, great news.

    Is there any Open GSM BTS been commercialyzed yet?

    Best regards, Vagner Ricciardi

  8. “A phone call should be a human right, not a privilege”..That says all about this project.
    In this world of advanced communication, some people around the world due to problems with terrains or other geo-political reasons couldnt use mobile phones as a medium of communication and so they lag behind..
    your project is a light to this dark road for them…

    regards from India

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