Kestrel Signal Processing

OpenBTS

OpenBTS is a GSM network-side protocol "stack" with a SIP network interface and integrated radio resource management functions. OpenBTS supports 2G GSM functions without the need for any supporting BSC, MSC or VLR, presenting each GSM handset to backing network as a SIP endpoint. In its simplest form, OpenBTS allows GSM handsets to be used as extensions in a SIP-capable VoIP PBX. OpenBTS can also be the foundation for a full-scale cellular system based on a VoIP core network instead of a conventional GSM hierarchy. Compared to conventional GSM systems, OpenBTS offers these advantages:

• The minimum viable network can be as small as a single cell, operated without integration into an existing GSM network.
• OpenBTS is an all-software system, including a software-defined radio, provided with full source code and portable to any POSIX environment.
• The OpenBTS VoIP-based backhaul is robust against packet loss, allowing it to traverse low-quality IP links reliably.
• When possible, OpenBTS confines all transcoding operations to the handsets, improving voice quality and reducing backhaul bandwidth.

OpenBTS distribution has been publicly demonstrated at several recent technology conferences and has been successfully operated by users around the world. OpenBTS has been successfully field testing under experimental licenses in the US and will enter its first carrier pilot test in March 2010.

The standard OpenBTS implementation uses modified USRP radio hardware, available form Kestrel, and the Asterisk PBX. However, the software is adaptable to any number of digital radios and SIP PBXs.

Using OpenBTS

• rural/village telephony and text messaging
• cellular coverage in remote areas (e.g. ships, oil rigs)
• law enforcement and security operations
• rapidly deployable emergency communications
• network emulation and handset testing
• wireless local loop service
• femtocells

Kestrel Signal Processing is the home of the founders and architects of the OpenBTS project. We are the primary source for OpenBTS support and development, and are ready to help you adapt OpenBTS to your specific applications.

OpenBTS Distribution

The public distribution of the OpenBTS system is available through the GNU Radio web site under GPLv3. Please contact us for information on commercial licensing and support.

The commercial distribution provides the following advantages:

• Access to commercial support from the original authors of the software.
• Features not yet released in public distributions.
• GPLv3 compliance. If you hold GSM patent licenses, you cannot redistribute OpenBTS under GPLv3. A commercial support agreement from Kestrel will insure your GPLv3 compliance or allow you access to other licenses.

The OpenBTS 2.x release series is in alpha tests and is already being evalated for commerical applications. This release series supports full-rate speech calling, SMS, and in-call DTMF and is configurable in real time through a command line interface, with default values taken from a file. The upcoming 3.x release series, in Spring 2010, will support multiple ARFCNs.

OpenBTS on the Web

Here are some links to news and other information regarding OpenBTS:

• OpenBTS on Sourceforge: The official project web site.
• OpenBTS at GNU Radio: The official project wiki.
• OpenBTS at eComm 2009: Video and slides from the first conference demonstation of OpenBTS, from March 2009.
• David Burgess on OpenBTS: An interview with Lee Dryburgh prior to the 2009 Emerging Communications Conference.
• BM 2009 Test: The most recent large-scale field test, Burning Man 2009.
• The OpenBTS Chronicles: The official project blog.
• David Burgess on VoIP Users Conference: An interview through the VoIP Users Conference.
• OpenBTS and Asterisk: Some comments from John Todd, open-source community director of Asterisk, on OpenBTS.