Although quite different in their approach, both projects have required a deep understanding of GSM technologies, represent significant development effort and offer their own particular benefits.
OpenBTS allows a PC to be combined with generic digital radio hardware and minimal additional components to provide a mobile network service that is trivial to integrate with VoIP solutions. OpenBSC can be used in place of a proprietary BSC within an existing GSM network, or simply combined with an off-the-shelf BTS and configured to provide a turnkey network.
The difficulty and cost associated with obtaining BTS equipment at present – prices of circa 3,000 euros have been suggested for the ip.access nanoBTS – may mean that, for the time being, OpenBTS offers the lowest cost route to building a small-scale GSM network. But this may well change once the sysmoBTS is available or OpenBSC supports a handset-based BTS.
Rather than competing, the projects offer two distinct routes to building a GSM network, and indeed it has been suggested that in future it may be possible to integrate the two, thereby providing even greater flexibility.
Tim Panton believes that there are two broad categories of opportunity: "providing coverage where there isn't any" and "customizable cells". Explaining how OpenBTS could be used to provide coverage where traditional GSM technology may not be economically viable, Tim suggested that this could include "mines, rural areas and small islands". In describing the opportunity presented by customizable cells, Tim cited an actual example from Burning Man: "We let users pick their own number, permitted short outgoing calls, and only allowed incoming calls from PSTN numbers they had recently called. So your accountant or boss can't call you at the festival, but your cat sitter can call you back. The essence of this is to break the one-size-fits-all behaviour of current (huge) cell networks."
Dean Elwood is CEO of Voxygen, a communications technology design and development company that works with cellular operators, and which has received a temporary licence from Ofcom to operate an OpenBTS-based GSM test network. When asked about the opportunity presented by open source GSM he replied: "Huge." He continued: "It has the potential to disrupt the network equipment provider market where, currently, enormous fees are charged for making the smallest configuration change. Mobile operators are under incredible pressure due to competition from companies such as Skype who are encroaching on their revenues, and open source represents a future model for the delivery of network technology where costs are substantially reduced. This could spell a significant disruption to certain vendors."
Open source GSM technology has the potential to create a wealth of significant opportunities. These range from reducing the cost of building and operating traditional GSM networks, through creating new and novel products and services, to providing cost-effective and tailored solutions for use by developing nations and in disaster relief.
Andrew Back (@9600) originally trained as an electronics engineer and first used Linux in the mid-90s. He has since worked at BT's open source innovation unit, Osmosoft, founded the Open Source Hardware User Group, and more recently co-founded SolderPad – a place to collaborate on electronic design.