lte protocols and procedures introduction

8/13/2019 LTE Protocols and Procedures Introduction

http://slidepdf.com/reader/full/lte-protocols-and-procedures-introduction 1/19



> Introduction



Why learn about

› Understand the protocols andprocedures involved within the

Evolved Packet System

(EPS).

› Understand how signaling is

performed between the UE,

eNodeB, MME, Serving-

Gateway and Packet Data

Network Gateway.



Course Objectives

After the completion of this course you will be able to:

› Explain the RRC Protocol

› Explain the PDCP Protocol

› Explain the RLC and MAC Protocols

› Explain the X2/S1 Interface and the X2AP/S1AP Protocol

› Describe attach procedure and UE states and the difference

between connected and idle mode› Describe call setup

› Describe mobility over X2 and S1 Interfaces

› Describe IRAT Mobility

› Describe CS Fallback



Module Scope and Objectives

› Describe the Evolved Packet System Architecture.

› List the Control and user plane protocols

› Explain the General Protocol model and Protocol

interactions

› Describe the various traffic cases in EPS

Objectives

Scope

› Evolved Packet System Architecture

› Control and user plane protocols

› General Protocol model and Protocol interactions



> LTE Protocols and Procedures



3GPP LTE and SAE & Work Items

LTEEUTRAN Specifications

(36 series)

TSG RAN

Specification Group Work ItemResult

SAEEPC Specifications

(From Rel 8 onwards)

TSG SA

Specification Group Work ItemResult

LTE: Long Term Evolution

EUTRAN: Evolved UMTS Terrestrial Radio Access Network

SAE: System Architecture Evolution

EPC: Evolved Packet Core



Evolved Packet System Architecture

eNB

eNB

eNB

S1

X2

X2

X2

SAE

(System Architecture

Evolution)

LTE

(Long Term Evolution)

EPC

(Evolved

Packet Core)

E-UTRAN

EPS

(Evolved Packet System)

UE

Uu

MME MME

HSS

P/S-GW P/S-GW

S6a



EPS Protocol Categories

L3 Signalling L2 Transport

• Non Access Stratum (NAS)

Communication between UE and MME

• Radio Resource Control (RRC)

Communication between UE and eNodeB

• Packet Data Convergence Protocol (PDCP)

- Ciphering and integrity protection for RRC messages

- IP header compression/decompression for user plane

•

Radio Link Control (RLC)- Transfer of RRC messages and user data using:

* Acknowledged Mode (AM)

* Transparent Mode (TM) or

* Unacknowledged Mode (UM)

- Error Correction (ARQ)

• Medium Access Control (MAC)

- Error Correction (HARQ)

- Transfer of RRC messages and user data using:- Priority handling (scheduling)

- Transport Format selection• GPRS Tunneling Protocol Control (GTP-C)

- Communication between MME and SGW

- Communication between SGW and PGW

- Communication between MME and MME

• S1 Application Protocol (S1AP)

Communication between eNodeB and MME

• X2 Application Protocol (X2AP)

Communication between eNodeB and eNodeB

• GPRS Tunneling Protocol User (GTP-U)Transfers data between GPRS tunneling endpoints



General Protocol Model

›

For each layer the payload is called SDU (Service Data Unit)› For each layer SDU+Protocol Header is called PDU (Packet Data Unit)

› Layer n PDU = Layer n+1 SDU

› E.g. A PDCP PDU = RLC SDU and RLC PDU = RLC Header+RLC SDU

PayloadHeader

Layer n SDU

Layer n PDU

Layer n

Layer

n+1

Layer n+1 SDU

Payload

Layer n+1 PDU

Header



EPS Bearer Service (S1-UP)

EPS Bearer service & Signaling Connection

UE

RBS MME S/P-GW

Data RadioBearer

Signalling

Radio Bearer

NAS Signalling Connection



UE Protocol Stack

Header

Compression

TM AM

UM

Physical Layer

L2

PDCP

RLC

MAC

RRC

NAS

Integrity/

Ciphering

System Info

Aquisition

Cell

Selection

Paging

Reception

Mobility

Management

Session

Management

Connected

Mode

Mobility

NAS

Security

IP

Application

AS SecurityRRC

Connection

RB

Managementv

Measurement

Reporting

C o n t r o l / R e p o r t S A P s

RA ControlHARQ

ControlRA Control

HARQ

Control



Segmentation, ARQ

Ciphering

Header Compr.

Hybrid ARQHybrid ARQ

MAC multiplexing

Antenna and

resrouce mapping

Coding + RM

Data modulation

Antenna and

resource mapping

Coding

Modulation

Antenna and

resource

assignment

Modulation

scheme

M A C

s c h e d u

l e r

Retransmission

control

Priority handling,

payload selection

Payload selection

RLC#i

PHY

PDCP#i

User #i User # j

MAC

Concatenation, ARQ

Deciphering

Header Compr.

Hybrid ARQHybrid ARQ

MAC demultiplexing

Antenna andresrouce mapping

Coding + RM

Data modulation

Antenna and

resource demapping

Decoding

Demodulation

RLC

PHY

PDCP

MAC

eNodeB UE

R e d u n d a n c y

v e r s i o n

IP packet IP packet

EPS bearers

E-UTRAN Radio

Bearers

Logical Channels

Transport

Channels

Physical Channels

Protocol Interaction



UE – MME Control Plane

L1

IP

SCTP

S1-MME

MME

S1-AP

NAS

SCTP

L2

L1

IP

eNodeB

S1- AP

MAC

RLC

PDCP RRC

Relay

MAC

L1

RLC

PDCP

UE

RRC

NAS

L2

Uu

L1

UE P k D NW



UE–

Packet Data NW

Gateway User Plane

Serving GW PDN GW

S5/S8

UDP/IP UDP/IP

L2 L2

L1 L1

UDP/IP

L2

L1

GTP-U

IP

SGi S1 - U Uu

eNodeB

RLC

L2

PDCP

MAC

L1 L1

PDCP

RLC

MAC

L1

IP

Application

UE

UDP/IP

GTP-U

Relay

GTP-U

Relay

GTP-U



> Summary



Summary

UE control planeprotocols

RLC

MAC

PDCP

L1

IP

Application

UE user plane

protocols

PDCP

RLC

MAC

L1

RRC

NASThe control signaling between the UE

and the Evolved Packet Core is done

with NAS protocol.

The control signaling between the UE

and the E-UTRAN (eNodeB) is done

with the RRC protocol.

LTE



More Information

›

3GPP Technical Specifications 36-series – 3GPP TS 36.331 E-UTRA; RRC Protocol specification

– 3GPP TS 36.323 E-UTRA; Packet Data Convergence Protocol

(PDCP) specification

– 3GPP TS 36.322 E-UTRA; Radio Link Control (RLC) protocol

specification

– 3GPP TS 36.321 E-UTRA; Medium Access Control (MAC) protocol

specification

– 3GPP TS 36.300 E-UTRA; Overall description

http://www.3gpp.org/ftp/Specs/archive/36_series/




lte protocols and procedures introduction

Documents