Telecom industry is one of the rapid growing industry all over the world. The entrance of open-source team into the telcom industry made a revolutionized change in the industry. Asterisk was a typical example for it which was a featured PBX for home users, enterprises, VoIP service providers and telecoms in such a low cost that anyone even imagined.Asterisk is both an Open Source Community and a commercial product from Digium.
Now again another open source coming which allows standard GSM-compatible mobile phones to make telephone calls without using existing telecommunication providers’ networks.ie we can build up our own network just like vodafone,airtel or any.The project was started by Harvind Samra and David A. Burgess and named it as OpenBTS.. OpenBTS is notable for being the first free software implementation of the industry-standard GSM protocol stack.Thanks to them for making it possible.:)
A normal GSM network working is as follows.The end point of the system will be BTS (Base Transceiver Station) which send radio frequency singal to and from mobile devices or a modem.The BTScomes under BSC(Base station Controller) with makes the communication between there radio signals with MSC/VLR.The MSC/VLR is responsible to authenticate the user against the database (HLR – Home Location Register, AuC -Authentication Center), call setup and call routing.A typical GSM network diagram is shown below.
The OpenBTS replaces the entire setup with USRP(Universal Software Radio Peripheral), and a computer as hardware.USRP to receive and transmit the GSM signaling(GNURadio is the driver software for this),OpenBTS package play the role of MSC/VLR and Asterisk software PBX will be used to connect calls.The below diagram shows a typical openBTS network.
Potential applications include:
- 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.
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