OpenBTS 4.0 drives commercial open-source cellular systems
By breaking the mould of proprietary, closed systems, open source will not only drive costs but boost innovation and even enable communities to initiate different business models than those currently deployed.
To this end, OpenBTS is a open source software implementation of a basestation that runs on a commodity server or servers and uses commodity IP routing equipment. All of the cellular network software runs on Linux and connects with commonly used TCP/IP and UDP/IP protocols. OpenBTS can even be run on virtualised servers in the cloud.
Recently, Range Networks, the leader of the OpenBTS software project, announced the release of OpenBTS 4.0. The software is now shipping in the company’s laboratory development kits and commercial base stations and is also available to the OpenBTS community as a free download.
OpenBTS, a software defined radio implementation of the GSM radio access network that presents normal GSM handsets as virtual SIP endpoints. In other words, through OpenBTS, any GSM handset appears as a SIP device, without the need for any special software on the phone.
The latest generation of OpenBTS offers significant improvements in processing capacity and system management features, including multi-node network scaling enhancements to Range Networks’ commercial systems. These enhancements further the migration of radio access network (RAN) infrastructure to low cost, standard hardware using open source software.
Edward Kozel, CEO of Range Networks, said: “This launch represents a significant milestone in Range Networks’ product development. In addition to the new features, OpenBTS continues to provide stability, reliability and scalability. We see this as a major leap forward in terms of what OpenBTS can do for expanding the reach of non-traditional mobile networks.”
Driving down costs
Significant cost savings from the OpenBTS approach are due to several factors, including:
- For small networks, the core network hardware can be reduced to a single commodity server, or core network applications can even be run on excess resources in the base stations themselves.
- For larger networks, the core network hardware is based on commodity servers and IP routing equipment, making it possible for the provided to have one shared IP network for both data and voice.
- Because all of the cellular network software runs on Linux and connects with commonly used TCP/IP and UDP/IP protocols, the core network can even be virtualized and run in a “cloud” service, like Amazon’s EC2.
- All of the proprietary software found in a conventional GSM network can replaced with open-source applications like open-source applications like SIP Express Router (SER), Yate, Apache web server and MySQL database server, eliminating recurring licensing fees.
- Because the new core network is based on IETF internet-age protocols, newly graduated engineers and software developers do not require additional training to deal with archaic SS7 technologies.
Beyond cost savings, the conversion of the network from legacy telco protocols to internet protocols gives the operator new opportunities to implement custom speech, text and USSD applications, using web service technologies like Apache and Ruby, or through cloud-based application platforms like Tropo or Twillio. These applications can even be installed in individual cell sites to provide locally-tailored service.
Open BTS 4.0
OpenBTS 4.0 features expanded capacity. Concurrent registration processing capacity has been increased by 14x, providing improved SIP authentication and service for over 1000 subscribers on a single node.
OpenBTS 4.0 offers fa requency scanning and system management API. This includes a built-in channel-scanning tool for transmission frequency selection when deploying systems. Also included is a newly implemented JSON API that allows mobile network operators to easily configure and manage the software remotely. This is done through a browser-based administrative console and provides third parties with an effective way to develop tools and interfaces for OpenBTS and other components
Further, seamless handover and enhanced encryption is achieved though a completely new Layer 3 architecture has significantly improved network scalability, including improved handover for multi-node networks. The software now supports the A5/1 and A5/3 GSM link encryption algorithms for enhanced security.
Going commercial
Following several weeks of field trials, OpenBTS 4.0 is the foundation of a new, multi-node, low-cost commercial network being implemented by French carrier GlobalTel that will cover the island and city of Saint Pierre (population 7000) of the French territory St. Pierre and Miquelon, located off the coast of Newfoundland.
Christophe Boutin, CEO of GlobalTel, said: “Range Networks’ OpenBTS 4.0 and base stations have been fundamental in helping us build a cost-effective carrier network in the remote territory of Saint Pierre and Miquelon. We have been testing the network thoroughly for weeks as we prepare to launch this service and are impressed by the improvements in overall stability and performance in this new release.”
Range Networks supports 2.5G today and will soon support 3G UMTS, 4G LTE (E-UTRA) and 2.75G (EDGE). Although these technologies have very different air interfaces, in their Range Networks realizations, the core network is always the same. This means that a greenfield carrier can start with a simple 2G network and over time develop a mixed 2G-3G-4G system, using whatever technology is best adapted to particular sites. Core network upgrades are just capacity upgrades, replacing existing servers with more or faster processors as the traffic volume increases, or incremental upgrades to provide new features, like MMS, as they become available.
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