Valoración del tiempo de vida de un sistema aislante

There are some specifics in LTE when establishing an emergency call. There is, for example, no HSS subscription for an UE (HSS au- thentication is optional). A special default emergency APN (Access Point Name) must be stored in MME (defining for example QoS pa- rameters or a static PDN gateway address) for the case an UE does not send its own APN.

For emergency attach a n E-UTRAN initial procedure is used after which an UE is in a limited service state and an emergency bearer is established. The limited service state is used to describe specific situation when UE can not obtain normal services. For example: UE enters in the limited service state when it is without a SIM, or UE enters in the limited service when there is no cell available like in roaming situations.[15]

When performing an emergency attach, an UE sends an attach re- quest (with TYPE set to „Emergency“) to MME. The MME can ask HSS for authentication if required. After receiving an emergency at- tach, MME sends the Create Session Request to SGW/PGW based on the address already defined APN. Based on the response the attach procedure may be completed and the UE can make an emergency

call. After finishing the call, the UE does not detach – MME releases the call.

UE can also request establishing an emergency session even after normal attach by sending PDN connectivity request with TYPE set to „Emergency“.[8]

The aim of this thesis was to provide a high-level overview of IMS emergency session handling detailed enough to be usable for IMS developers. The purpose of this challenge is to overcome a gap in communication between an IMS architect and IMS developer. In the first part of my thesis I summarized the most important facts about 3GPP IMS and SIP protocol, and provided an overview of the most commonly used mobile technologies. This created a basis to un- derstand the principles of IMS.

In the second part of my thesis I had to deeply scrutinize 3GPP doc- umentation relevant to emergency sessions. Based on my working experience as an IMS architect I attempted to compose a logically structured white paper with all information necessary to understand the behavior of the IMS emergency process without a necessity to ex- amine a large amount of documentation.

To abstract the most important emergency processes, I have also cre- ated UML diagrams to provide high-level models of the pre-initiation process, the session initiation process and the LTE emergency attach procedure.

This thesis can be used by IMS developers to get a general overview of emergency sessions handling detailed enough so that they can un- derstand the principles behind their programming. This thesis is in- tended to be distributed in my company as a white paper and also in main Internet forums focused on 3GPP IMS or Open IMS Core. Regarding emergency sessions, an improvement of this thesis would be the exploring of non-voice emergency session support already de- fined in 3GPP but not fully implemented yet. As a next step in solv- ing the problem of communication and the lack of general under- standing of IMS architecture would be creating a register of IMS core white papers providing high-level decsriptions and models of the entire IMS. This would reflect the current need for having an under-

standable general overview of IMS core components which would not be so detailed as 3GPP standard.

[1] Ip multimedia subsystem. In Wikipedia : the free ency- clopedia. [online] http://en.wikipedia.org/wiki/IP_ Multimedia_Subsystem_{. Accessed: 2014-04-03.}

[2] Rfc: 3551. rtp profile for audio and video conferences with minimal control. [online] http://www.ietf.org/rfc/ rfc3551.txt. Accessed: 2014-04-09.

[3] Rfc: 3665. session initiation protocol (sip) basic call flow exam- ples. [online] https://tools.ietf.org/html/rfc3665. Accessed: 2014-04-03.

[4] Telephone number mapping. In Wikipedia : the free encyclopedia. [online] http://en.wikipedia.org/wiki/ Telephone_number_mapping_{. Accessed: 2014-04-03.}

[5] 23.167, G. T. Ip multimedia subsystem (ims) emergency ses- sions, June. 2013.

[6] 23.228, G. T. Ip multimedia subsystem (ims); stage 2; release 11, June 2012.

[7] 23.401, G. T. Gprs and e-utran access, June 2013.

[8] 23.869, G. T. Emergency calls over general packet radio service (gprs) and evolved packet service (eps), June 2012.

[9] 24.301, G. T. Nas protocol for eps, June 2013.

[10] 29.274, G. T. Gprs and eps tunnelling protocol, June 2013. [11] BENDÍ ˇCEK, M. Ip multimedia subsystem. Master’s thesis,

Brno: Vysoké uˇcení technické v Brnˇe, Fakulta elektrotechniky a komunikaˇcních technologií, 2008.

[12] BETLACH, M. Ip multimedia subsystem a jeho využití pro za- jištˇení kvality služeb. Master’s thesis, Brno: Vysoké uˇcení tech- nické v Brnˇe, Fakulta elektrotechniky a komunikaˇcních tech- nologií, Brno, 2008.

[13] BOŽEK, M. Open ims core a ip multimedia subsystem. Mas- ter’s thesis, Brno: Vysoké uˇcení technické v Brnˇe, Fakulta elek- trotechniky a komunikaˇcních technologií, 2011.

[14] CAMARILLO, G. The 3G IP Multimedia Subsystem (IMS): Merg-

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[15] DORNAL, S. Ims emergency calls over lte. [on-

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[16] ERIK DAHLMAN, STEFAN PARKVALL, J. S. 4G: LTE/LTE- Advanced for Mobile Broadband, 1 ed. Academic Press, 2011. [17] GROUP, N. W. Rfc: 3665. session initiation protocol (sip) ba-

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[18] HEINE, G. GPRS: Gateway to Third Generation Mobile Net-

works, 1 ed. Artech House, 2003.

[19] JEANTTI, J. IMS version 9 implementation guide. A techni- cal overview, 1 ed. San Jose, CA: IBM, International Technical Support Organization, 2004.

[20] JOHNSON, C. Long Term Evolution in Bullets, 2 ed. CreateSpace Independent Publishing Platform, 2012.

[21] JOHNSTON, A. SIP: Understanding the Session Initiation Pro- tocol. Artech House, 2009.

[22] MATYÁŠ, J. Možnosti potenciálu novˇe dostupných služeb v sítích long term evolution. Master’s thesis, Univerzita Tomáše Bati ve Zlínˇe, Fakulta aplikované informatiky, 2010.

[23] MOULY, M. The GSM System for Mobile Communications. Tele- com Publishing, 1992.

[24] NAVRÁTIL, P. Modely systému lte. Master’s thesis, Vysoké uˇcení technické v Brnˇe, Fakulta elektrotechniky a komu- nikaˇcních technologií, 2013.

[25] NOLDUS, R. IMS Application Developer’s Handbook: Creating

and Deploying Innovative IMS Applications. Academic Press, 2011.

[26] OPRŠALOVÁ, S. Mobile commerce - porovnání situace v

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Cr a v zahraniˇcí. Master’s thesis, Masarykova univerzita Brno, Ekonomicko-správní fakulta, Katedra podnikového hospodáˇrství, 2007.

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[28] POIKSELKA, M. The IMS: IP Multimedia Concepts and Ser- vices. England: WILEY, 2009.

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