LTE Interoperability

Course overview:

The course contains detailed information about the interoperability problems/issues that may arise due to the introduction of the Evolved UTRAN (E-UTRAN aka LTE) and the Evolved Packet Core (EPC) in 3GPP Release 8. The course covers both radio-related and CN-related issues. The radio part focuses on cell reselection and UE measurements. The core network part focuses on security, QoS and protocol interworking between ‘new’ and ‘old’ nodes in Idle and Connected mode inter-RAT mobility scenarios. Mandatory and optional mechanisms for Idle and Connected mode PS mobility/handover are investigated in detail. A thorough description of the various standardised/proposed solutions to the CS interworking ‘problem’ is included. The course also contains an overview of interworking between LTE and non-3GPP access networks such as WiMAX and cdma2000.

The course contains several message-by-message signalling flows for the purposes of explaining various inter-RAT mobility scenarios as well as to, when necessary, provide the course participants with the proper background reference knowledge. Examples of cases covered are: GPRS/EPS Attach, Inter-RAT Location Registration, CSFB Call Setup and several Inter-RAT PS Handover scenarios.

The courses primary focus is on interworking between LTE and UMTS/HSPA, with LTE/GSM interworking covered in less detail.

Pre-requisites:

Basic knowledge of the Evolved Packet System (EPS) and pre-EPS network architecture, bearer and QoS concepts as well as basic knowledge of layer 3 signalling procedures in GSM/UMTS (and LTE) is recommended.

Course contents:

Network Architecture

• EPS nodes and interfaces (R8 or later)

• Pre-EPS nodes and interfaces (R7 or earlier)

• Combined node architectures

• Network sharing options

• Gn-interface towards MME and/or PGW

Protocol Overview

• Refresh of 2G/3G protocol stacks and bearer concepts

• Overview of EPS protocol stacks and bearer concepts

Cell Selection & Reselection

• PLMN selection process

• Initial cell selection process

• Priority-based inter-RAT cell reselection

• DCCH-controlled cell reselection (SPID, re-direct)

Idle Mode Mobility

• EPS vs non-EPS mobility management

• Inter-RAT RA and TA updates

• Context storage and transfer between MME and SGSN

• Conversion between EPS and non-EPS security keys

• UE capability transfer

• Idle mode signalling reduction (ISR)

• Mapping between GUTI and PTMSI/RAI

PS Interworking

• Cell search procedure for GSM, UMTS and LTE

• Measurement quantities in GSM, UMTS and LTE

• Configuration of measurement reporting

• Inter-RAT event reporting

• Feature group indicators for inter-RAT mobility

• PS handover from LTE to GSM/UMTS (R8 and pre-R8)

• Network assisted cell change from LTE to GSM

• Direct and indirect data forwarding paths

• Conversion between EPS and non-EPS QoS attributes

• Non-3GPP interworking

• Access Network Discovery and Selection (ANDSF)

• PMIP-based S5/S8-interface

• GSM Association: LTE roaming guidelines

CS Interworking

• Combined EPS/CS attach

• Circuit Switched Fallback (CSFB)

• The SGs-interface and SGsAP protocol

• Single Radio Voice Call Continuity (SRVCC)

• The Sv-interface and extended GTP protocol

• Options for SMS over LTE

• GSM Association: voice and SMS over LTE (VoLTE)

• UE modes and user preferences

• Voice centric vs data centric UE

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