# [Openbts-discuss] CKSN clarification

Alexander Chemeris alexander.chemeris at gmail.com
Fri Apr 20 15:33:41 UTC 2012

Max,

On Fri, Apr 20, 2012 at 19:09, Max <Max.Suraev at fairwaves.ru> wrote:
> - what is CKSN IEI and how do I calculate\use it?

IEI is a Information Element Identiﬁer, which is a part of TLV-coded
(Type-Length-Value) Information Elements (IEs). In other words, IEI
represents type (T) of the data payload which follows it. TLV is an
encoding used in most of the classical GSM protocols. I don't recall
where it is described in the Standard, but here is a nice paper which
you easily find on Google which describes ciphering and described TLV
structure as well (section 6.1.2):
http://www.cs.ru.nl/~fabianbr/scriptie.pdf

--
Regards,
Alexander Chemeris.
CEO, Fairwaves LLC / ООО УмРадио
http://fairwaves.ru