LTE System Overview

Subject: 4G LTE
Category: General
Duration: 3 days

Course outline:

Introduction to Evolved Packet System (EPS)

● Evolution steps of the 3GPP systems, the goals for LTE
● LTE bandwidths, bit rates and UE categories
● Summary of radio access techniques

EPS Network Architecture and Interfaces

● E-UTRA and Evolved Packet Core network architecture
● Nodes: UE, eNB, SGW, MME, PGW, PCRF
● Interfaces: Uu, X2, S1, S11, S5, Gx, S6a, SGi, Rx
● IP connectivity, user plane and control plane
● Access Stratum signaling and Non-Access Stratum signaling


● Fundamentals of multipath propagation (selectivity in time, frequency and space)
● Serial vs. parallel transmission, multicarrier transmission
● OFDM subcarriers and subcarrier separation, cyclic prefix, IFFT/FFT processing
● OFDM transceiver processing
● Multiuser diversity and OFDMA
● SC-FDMA as a subclass of OFDMA, comparison between SC-FDMA and OFDMA
● Multiple access with OFDMA and SC-FDMA
● Multiple antenna concept
● Open and closed loop spatial multiplexing
● Multi-user MIMO


● E-UTRAN protocol stack and channel architecture
● Downlink FDD frame structure and its elements (sub-frames, slots, resource elements, physical resource blocks, PHY channels and signals)
● Adaptive Modulation and Coding, QPSK, 16-QAM, 64-QAM
● Use of MIMO in 3GPP-LTE Release 8
● Uplink FDD frame structure and its elements (sub-frames, slots, resource elements, physical resource blocks, PHY channels and signals)
● E-UTRAN L3 and L2 protocols: RRC, PDCP, RLC, MAC

Quality of Service in LTE

● Bearer architecture including EPS bearer and end-to-end service
● Guaranteed and Non-Guaranteed Bit Rate Bearer
● QoS Classes and QoS Class Identifier
● Allocation and Retention Priority
● Bit Rate limitations
● Bearer setup, service data flows and traffic flow templates

Evolved Packet Core

● Overview of EPS protocols: PDCP, RRC, GTP, X2AP, S1-AP, S1-MME, GTP, Diameter
● NAS protocols (EMM and ESM)
● UE states (LTE-idle, LTE-active, LTE-detached)
● Subscriber identities and their relations (IMEI, IMSI, GUTI, S-TMSI, RNTIs)
● Security and keys’ derivation
● IMS network and nodes (CSCF, AAA, DNS, AS, HSS)
● Call establishment via IMS
● Voice in LTE (CS Fallback, Voice Call Continuity, VoLGA)

LTE Cross-system Procedures

● Network Attach and Detach
● Call setup (Dedicated bearer establishment)
● Tracking Area Update
● Paging
● Handover over X2
● Handover over S1

LTE Features Roadmap (Rel. 8-10)

● Overview of features in the 3GPP E-UTRAN Release 8
● Enhancements expected in 3GPP E-UTRAN release 9 including MBMS
● Features in 3GPP E-UTRAN Release 10 i.e., LTE Advanced: spectrum aggregation, relay concept, MIMO improvements

LTE Interworking Considerations

● Roaming
● Inter-working with 3GPP and non-3GPP networks

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