computer science

Osmocom

Osmocom is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Osmocom rather than just read about it. In short: Osmocom (open source mobile communications) is an open-source software project that implements multiple mobile communication standards, including GSM, DECT, TETRA and others. History and usage In 2008 Harald Welte and Dieter Spaar experimented with a base transceiver station (BTS) from Siemens that was end-of-life and implemented the BSC side of the A-bis protocol, which eventually turned into OpenBSC.

Key takeaways

Osmocom belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Osmocom to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Osmocom from memory before moving on to harder problems.

Reference excerpt

Osmocom (open source mobile communications) is an open-source software project that implements multiple mobile communication standards, including GSM, DECT, TETRA and others.

History and usage

In 2008 Harald Welte and Dieter Spaar experimented with a base transceiver station (BTS) from Siemens that was end-of-life and implemented the BSC side of the A-bis protocol, which eventually turned into OpenBSC. After attracting more interest, support for other BTS models was added. The first release of the OpenBSC project took place at the 25th Chaos Communication Congress held in December 2008. In the following years, the software has been used at various hacker cons such as the Chaos Communication Congress, Chaos Communication Camp and Electromagnetic Field to provide a cellular network. In 2010, a telephone-side implementation of the GSM stack was developed, named OsmocomBB. Together with OpenBSC, these projects became part of the new Osmocom umbrella project. The Sysmocom GmbH company was founded by Welte and Holger Freyther in 2011 to provide commercial support. Since 2018 Osmocom software and Sysmocom hardware has been used in Villa Talea de Castro in Mexico to provide a cellular network to around 3500 people. Osmocom software has been used in research projects.

Projects

OpenBSC OpenBSC was a project to develop a free software implementation of GSM protocol stack and elements. It runs on Linux and requires an E1 interface (ISDN Primary Rate Interface, via mISDN). It is written in C and licensed using the GPL (≥v2) license. The first version implemented the GSM specification 21.12 and 08.5x, and worked for a specific Base Transceiver Station (Siemens BS11 MicroBTS). OpenBSC implemented several MSC components, including the A-bis protocol (the protocol between the BTS and the BSC), AUC, HLR, VLR (both using SQL tables), and a SMS Switching Center. OpenBSC can be accessed using telnet. OpenBSC supported the following BTS devices:

Siemens BS11 (microBTS) (E1 Primary Rate interface) ip.access nano BTS (PoE-interface) OpenBSC is now considered legacy and the features have been split into different projects: OsmoBSC, OsmoMSC and OsmoHLR.

SDR rtl-sdr was discovered by Steve Markgraf, who also created osmo-fl2k for radio transmissions. These projects deprecated the use of OsmoSDR.

OsmoTETRA The OsmoTETRA project implements the TETRA protocol. Osmo-tetra implements the lower layer of the protocol. Some conducted research revealed that some government traffic is not properly secured.

OsmocomBB OsmocomBB is a free firmware for the baseband processor of mobile phones which handles the encoding and radio communication of both voice and data. OsmocomBB is the only existing free implementation of baseband firmware, excluding failed projects like TSM30 from THC and MadOS.

OsmocomBB implements the GSM protocol stack's three lowest OSI Layers of the client side GSM protocol and device drivers. The protocol layers forming the kernel exists on the baseband processor, typically consisting of an ARM processor and a digital signal processor. It has support for the Calypso chipset produced by Texas Instruments. Karsten Nohl has extended OsmocomBB to be able to detect IMSI catchers.

See also OpenBTS, FOSS project for implementing a BTS using GNU Radio

References

External links Official website

Illustrations

Worked examples

Example 1 — a first encounter with Osmocom

Start with the simplest possible case. Write down what Osmocom claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Osmocom before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Osmocom ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Osmocom

In research: Osmocom appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Osmocom in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Osmocom is common in secondary-school and first-year university syllabi. It links to neighbouring topics Free communication software, Free software programmed in C, Free software programmed in C++, so understanding it makes those chapters shorter.
In everyday life: Look for Osmocom outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Osmocom in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Osmocom means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Osmocom out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Osmocom in simple terms?

Osmocom (open source mobile communications) is an open-source software project that implements multiple mobile communication standards, including GSM, DECT, TETRA and others. History and usage In 2008 Harald Welte and Dieter Spaar experimented with a base transceiver station (BTS) from Siemens that…

Why does Osmocom matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Osmocom?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Osmocom.