Run an open source GSM mobile phone network

One caveat: A government-issued bandwidth license is currently required

Slashdot reports that Harald Welte is operating an open source GSM network at the Hacking at Random (HAR) conference.  Welte writes:

Here at the amazing HAR2009 hacker conference + camp, I have the pleasure of operating a camp-wide GSM network.

Under license of the Dutch regulatory authority, we operate two BTS with two TRX each, forming the network 204-42. The BTS are positioned on the top of a hill, with the antennas mounted back to back on a tree, each covering about half of the HAR2009 camp site. Every transceiver runs at 100mW transmit power, which is the maximum output as per our license.

From that tree, we run AC power and a single E1 line down to the GSM tent, where it runs into the Linux PC that runs our OpenBSC software.

For those of us who aren't mobile phone networking experts, "BTS" stands for Base Transceiver Stations, "TRX" stands for transceivers, and "BSC" stands for Base Station Controller.

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OpenBSC is a GPL implementation of major components of a GSM network. Welte is one of the key developers behind OpenBSC, which aims to:

  • provide a basis for experimentation and security research with GSM from the network side;
  • document, publicize, and point out any security-related issues that we find as part of that; and
  • learn more about GSM networks on a lower level, particularly the practical aspects with real-world equipment.

Unfortunately, the project is not interested in:

  • building a stable/reliable BSC/MSC for deployment in actual networks;
  • building something that follows the GSM spec to the last detail; or
  • disrupting actual commercial GSM networks.

Since a government-issued network bandwidth license is required to run a GSM network in most countries, few of us will ever run our own open source GSM networks, although it seems that countries like Russia allow the use of licensed frequencies for low-power indoor use. So the title of this blog is squarely targeted at readers in Russia.

Kidding aside, I wonder why Welte and team aren't interested in building a distribution that fully implements the GSM specification. The use of OpenBSC on Linux could be targeted at telecom operators in emerging markets. Considering the growth in mobile phone usage in emerging markets and network operators' constant search for cost reduction, there could very well be a business here.

Any takers?

Follow me on Twitter: SavioRodrigues.

p.s.: I should state: "The postings on this site are my own and don't necessarily represent IBM's positions, strategies, or opinions."

Copyright © 2009 IDG Communications, Inc.

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