OpenBTS is a Unix application that uses a software radio to present a GSM air interface to standard 2G GSM handset and uses a SIP softswitch or PBX to connect calls.
History of OpenBTS:
The project was started by Harvind Samra and David A. Burgess back in 2008.
The main aim of the project is to reduce the cost of GSM service provision in rural areas and the developing world.
Some Important Points:
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.
Hardware Used in OpenBTS:
The main hardware device is Ettus' Universal Software Radio Peripheral (USRP).
The RF RX part of the GSM access point consists of a simple ground plane antenna (triple leg).
Software used in OpenBTS:
Software that is used in OpenBTS is Asterisk VoIP PBX.
OpenBTS uses Asterisk not only for handling VoIP calls, also for user authentication.
Every mobile user has to be registered in the sip.conf with its particular IMSI(International Mobile Subscriber Identity).
P2.6 and P2.8 models
In P2.6 the configuration is driven from a text file.
P2.8 is the latest one where the configuration is database driven.
Changes made in P2.8:
In P2.8, configuration is no longer from a text file but from an sqlite3 database at /etc/OpenBTS/OpenBTS.db which is database driven.
Database-driven configuration allows external applications to control critical operating parameters of the OpenBTS system.
No need to purchase a huge BTS equipment. Only some small hardware and one software defined radio equipment is enough to run the BTS.
Cost is 1/10 of traditional BTS installation.
Web based and automated configuration management tools.
Allows many operating parameters to be changed without disrupting the service.
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.