LTE basic signalling

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LTE Basic Signaling

2

Acknowledgement...........................................................................................3

1 eNB Declared “Radio Connection with UE lost”.............................................3

1.1 3GPP Reference.............................................................................................3

1.2 Definition.........................................................................................................3

1.3 Procedure.......................................................................................................3

1.4 Reference.......................................................................................................4

2 Authentication and Security...........................................................................5

2.1 3GPP Reference.............................................................................................5

2.2 Definition.........................................................................................................5

2.3 Procedure.......................................................................................................6

2.4 Related command...........................................................................................7

3 Dedicated EPS Bearer Setup and Release...................................................8

3.1 3GPP Reference.............................................................................................8

3.2 Definition.........................................................................................................8

3.3 Procedure.....................................................................................................10

3.4 Related command.........................................................................................11

4 CBRA, Re-synchronization of UL................................................................12

4.1 3GPP Reference...........................................................................................12

4.2 Definition.......................................................................................................12

4.3 Procedure.....................................................................................................13

4.4 Related command.........................................................................................14

5 Cell Reselection..........................................................................................15

5.1 3GPP Reference...........................................................................................15

5.2 Definition.......................................................................................................15

5.3 Procedure.....................................................................................................17

5.4 Related command.........................................................................................17

6 UE measurement reports, Intra LTE Handover...........................................18

6.1 3GPP Reference...........................................................................................18

6.2 Definition.......................................................................................................18

6.3 Procedure.....................................................................................................20

6.4 Related command.........................................................................................20

7 Intra MME Handover...................................................................................21

7.1 3GPP Reference...........................................................................................21

7.2 Definition.......................................................................................................21

7.3 Procedure.....................................................................................................22

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7.4 Related command.........................................................................................23

8 Intra LTE Release with Redirection.............................................................24

8.1 3GPP Reference...........................................................................................24

8.2 Definition.......................................................................................................24

8.3 Procedure.....................................................................................................25

8.4 Related command.........................................................................................26

9 DRX 27

9.1 3GPP Reference...........................................................................................27

9.2 Definition.......................................................................................................27

9.3 Procedure.....................................................................................................29

9.4 Related command.........................................................................................29

10 SRS 30

10.1 3GPP Reference.........................................................................................30

10.2 Definition.....................................................................................................30

10.3 Procedure...................................................................................................31

10.4 Related command.......................................................................................31

11 IRAT Release with Redirection to UTRAN.................................................32

11.1 3GPP Reference.........................................................................................32

11.2 Definition.....................................................................................................32

11.3 Procedure...................................................................................................33

11.4 Related command.......................................................................................33

12 Circuit Switched Fallback to UTRAN.........................................................35

12.1 3GPP Reference.........................................................................................35

12.2 Definition.....................................................................................................35

12.3 Procedure...................................................................................................36

12.4 Related command.......................................................................................36

13 Appendix – Logs from actual test case......................................................37

13.1 eNB Declared “Radio Connection with UE lost”..........................................37

13.2 Authentication and Security........................................................................40

13.3 Dedicated EPS Bearer Setup and Release.................................................42

13.4 CBRA, Re-synchronization of UL................................................................43

13.5 Cell Reselection..........................................................................................45

13.6 UE measurement reports, Intra LTE Handover...........................................45

13.7 Intra MME Handover...................................................................................45

13.8 Intra LTE Release with Redirection.............................................................47

13.9 DRX............................................................................................................48

13.10 SRS..........................................................................................................49

13.11 IRAT Release with Redirection to UTRAN................................................51

13.12 Circuit Switched Fallback to UTRAN.........................................................54

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Acknowledgement

This document is based on OJT report in IoDT Kista from 2012 February to August.

Here I would like to take opportunity to express my deepest appreciation to IoDT Kista

team members for their warm support and guidance during my stay.

1 eNB Declared “Radio Connection with UE lost”

1.1 3GPP Reference

36.331 rev. 9.6.0 chapter 5.3.7, 5.3.11

36.213 rev. 9.3.0 chapter 4.2.1

1.2 Definition

Due to the loss of the radio signal in the uplink, the eNB declares “Radio

Connection with UE lost. RRC Connection Release messages will be sent during

the time when the radio signal is lost. There are two types of behavior depending

on whether this message is received by the UE or not. When the signal is

returned to the good SINR (Signal to Noise interference Ration) after the eNB

releases the UE context, the connection is resumed.

1.3 Procedure

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1.4 Reference

About RRC connection re-establishment (from 3GPP 36.331; 5.3.7 RRC

connection re-establishment)

The purpose of this procedure is to re-establish the RRC connection, which

involves the resumption of SRB1 operation and the re-activation of security. A UE

in RRC_CONNECTED, for which security has been activated, may initiate the

procedure in order to continue the RRC connection. The connection re￾establishment succeeds only if the concerned cell is prepared i.e. has a valid UE

context. In case E-UTRAN accepts the re-establishment, SRB1 operation

resumes while the operation of other radio bearers remains suspended. If AS

security has not been activated, the UE does not initiate the procedure but

instead moves to RRC_IDLE directly.

E-UTRAN applies the procedure as follows:

- to reconfigure SRB1 and to resume data transfer only for this RB;

- to re-activate AS security without changing algorithms.

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2 Authentication and Security

2.1 3GPP Reference

24.301, chapter 5.4.2

33.401, chapter 6.1.1

2.2 Definition

LTE authentication and security procedure can be divided mainly into 3 parts.

"Authentication and Key Exchange Procedure" is followed by "NAS Security

Mode Command Procedure" and "AS Security Mode Command Procedure".

Authentication: The process of determining whether someone or something

is, in fact, who or what it is declared to be

NAS security: Carried out for NAS messages and belongs to the scope of UE

and MME. In this case NAS message communication between UE and MME are

Integrity protected and Ciphered with extra NAS security header.

AS security: Carried out for RRC and user plane data and belongs to the

scope of UE and eNB. PDCP layer in UE and eNB side is responsible for the

ciphering and integrity protection. RRC messages are integrity protected and

ciphered but U-Plane data is only ciphered.

The security in LTE comprises of two things same as 3G. One is the "Data

Integrity" and other is "Ciphering". In case of UMTS Integrity Protection is

mandatory while Ciphering is optional. Integrity protection is done only on

Signalling Radio Bearers whereas Ciphering is done on Signalling as well as

Data Radio Bearers.

Data Integrity: The feature that makes sure that no rogue Network will be able

to send unnecessary signalling messages with the intention or causing any

undesired effect in an ongoing call.

Ciphering: The feature that makes sure that all Signalling and Data messages

are ciphered over the air interface so that no one can eavesdrop on them.

For integrity/ciphering, there are 3 different algorithm for each.