LTE for dummies

 Introduction  Evolution of Cellular technology  LTE air interface capabilities  LTE standards

 Network Structure  Basic components and their functions  EPC and various interfaces

 Protocol stack  User plane  Control plane  EPS NAS protocols

 Overview about channels  Some operations and procedures

Rel9 Rel8 Rel7 Rel6 Rel5 Rel99

HSUPA

HSPA+

HSDPA

WCDMA Rel8

Rel9

LTE

Rel10

 Scalable channel bandwidths  1.4Mhz to 20Mhz  TDD and FDD

 Waveforms  OFDMA in DL  SC-FDMA in UL

 Modulation for data channels  QPSk,16-QAM,64-QAM

 MIMO support  Inter-cell interference management

 DL and UL performance is better than HSPA rel6.  Coverage

 Mobility  Interworking with existing 3G and non-3G networks.

 Two possible radio frame structures  FDD

 TDD

EPC /P-GW

/P-GW

3G  Centralized radio

resource management  High latency  Usage of both circuit switched and packet networks.  Internetworking with 3GPP technologies only.

LTE  Distributed Radio resource management  Low latency  All IP packet core network.  Internetworking with

both 3GPP and non3GPP technologies.

UE

eNB

S-GW

P-GW

IP-NW

 Two protocols for NAS  Evolved Mobility Management  Evolved Session Management

 EMM registration\deregistration  ESM active\inactive

 EMM connected\idle  RRC connected\idle

UE

MME/ S-GW

eNB

P-GW

Attach request+ PDN connectivity request S1 signal connection setup

authentication Subscriber info Attach accept

EPS bearer setup accept Attach conform

Default EPS bearer setup

HSS

 Logical channels  Transport channels

 Physical channels

 Needs two synchronization signals  PSS  SSS

 Additional sys information over PBCH and PDSCH  Procedure:  Switch on the mobile  Receive the PSS signal  Receive the SSS signal

 Read the PBCH for SIB and PDSCH for MIB  Register to the network

 Single communication link between eNB and UE  No more soft handover

 Two types of handovers in LTE  Network based handover  Traditional handover process  UE based – Radio Link Failure handover  Triggered by RLF so need to be done by UE.