UMTS

UMTS 1

What is UMTS ?

Universal Mobile Telecommunications System

(UMTS)

UMTS is an upgrade from GSM

The standardization work for UMTS is carried out

by Third Generation Partnership Project (3GPP)

UMTS 2

Evolution of UMTS

UMTS 3

UMTS Architecture High Level

UMTS 4

Functional network elementso User Equipment (UE)

interfaces with user and radio interface

o Radio Access Network (RAN, UMTS Terrestrial RAN = UTRAN) handles all radio-

related functionalityo Core Network

switches and routes calls and data connections to external networks

UMTS Architecture

UMTS 5

USIM

ME

Node BNode B

RNC

Node BNode B

RNC

MSC/VLR GMSC

SGSN GGSN

HLR

UTRAN CNUE

Exte

rnal

Netw

or k

s

Cu

Uu

Iu

IubIur

UMTS Architecture - Detailed

UMTS 6

UMTS Architecture - Detailed

UMTS 7

UMTS Architecture - Detailed

UMTS 8

SD

Mobile Station

MSC/VLR

Base StationSubsystem

GMSC

Network Subsystem

AUCEIR HLR

Other Networks

Note: Interfaces have been omitted for clarity purposes.

GGSNSGSN

BTS BSC

NodeB

RNC

RNS

UTRAN

SIM ME

USIM ME

+

PSTN

PLMN

Internet

UMTS Terrestrial Radio Access Network - UTRAN

UMTS 9

Two Distinct Elements : Base Stations (Node B) Radio Network Controllers (RNC)

Handles all Radio-Related Functionality

Soft Handover Radio Resources Management

Algorithms

Maximization of the commonalities of the PS and CS data handling

Node BNode B

RNC

Node BNode B

RNC

IubIur

RNS

RNS

UMTS Core Network

UMTS 10

CS Domain :o Mobile Switching Centre (MSC)

Switching CS transactions

o Visitor Location Register (VLR) Holds a copy of the visiting

users service profile, and the precise info of the UEs location

o Gateway MSC (GMSC) The switch that connects to

external networks

PS Domain :Serving GPRS Support Node (SGSN)

Similar function as MSC/VLR

o Gateway GPRS Support Node (GGSN)

Similar function as GMSC

Home Location Register (HLR) Stores master copies of

users service profiles Stores UE location on the

level of MSC/VLR/SGSN

MSC/VLR GMSC

SGSN GGSN

HLR Exte

rnal

Netw

or k

s

Iu-cs

Iu-ps

UMTS - CS Domain

UMTS 11

CS domain has the following elements: Mobile Switching

Centre (MSC), including Visitor Location Register (VLR)

Gateway MSC (GMSC)

UMTS - PS Domain

UMTS 12

PS domain has the following elements Serving GPRS Support

Node (SGSN) covers similar

functions as MSC for packet data, including VLR type functionality

Gateway GPRS Support Node (GGSN)

connects PS core network to other networks, e.g. to the Internet

Common Databases - Registers

UMTS 13

In addition to the two domains, the network needs various registers for proper operation Home Location Register (HLR) Equipment Identity Register (EIR)

contains the information related to the terminal equipment can be used to, e.g., prevent a specific terminal from accessing the network

Power Control

UMTS 14

Prevent Excessive Interference and Near-far Effect

Open-Loop Power Control Rough estimation of path loss from

receiving signal Initial power setting, or when no

feedback channel is exist

Fast Close-Loop Power Control Feedback loop with 1.5kHz cycle to

adjust uplink / downlink power to its minimum

Even faster than the speed of Rayleigh fading for moderate mobile speeds

Outer Loop Power Control Adjust the target SIR set point in

base station according to the target BER

Commanded by RNC

Fast Power ControlIf SIR < SIRTARGET, send power up command to MS

Outer Loop Power ControlIf quality < target, increases SIRTARGET

Handovers

UMTS 15

Softer Handover A MS is in the overlapping coverage

of 2 sectors of a base station Concurrent communication via 2 air

interface channels 2 channels are maximally combined

with rake receiver

Soft Handover A MS is in the overlapping coverage

of 2 different base stations Concurrent communication via 2 air

interface channels Downlink: Maximal combining with

rake receiver Uplink: Routed to RNC for selection

combining, according to a frame reliability indicator by the base station

These handovers provides a Kind of Macro-diversity

NodeB1

NodeB - X

NodeB - Y

UE

UE

RNC 1

RNC 2

HSDPA Vs HSUPA

UMTS 16

HSPA (High Speed Packet

Access), commonly referred to

as 3.5G, is an upgrade to

WCDMA networks that allows

for much higher data speeds

for internet connectivity.

HSDPA (High Speed Downlink

Packet Access) is the one that

improves the downlink of the data

transmission while HSUPA (High

Speed Uplink Packet Access) is the

one that improves the uplink or

transmission from the mobile

device to the network.

HSDPA

UMTS 17

High Speed Downlink Packet Access

Standardized in 3GPP Release 5

Improves System Capacity and User Data Rates in the Downlink Direction to 42Mbps in a 5MHz Channel

Adaptive Modulation and Coding (AMC) Replaces Fast Power Control :

User farer from Base Station utilizes a coding and modulation that requires lower Bit Energy to Interference Ratio, leading to a lower throughput

Replaces Variable Spreading Factor :Use of more robust coding and fast Hybrid Automatic Repeat Request (HARQ, retransmit occurs only between MS and BS)

HARQ provides Fast Retransmission with Soft Combining and Incremental Redundancy

Soft Combining : Identical Retransmissions Incremental Redundancy : Retransmits Parity Bits only

Fast Scheduling Function which is Controlled in the Base Station rather than by the RNC

UMTS 18

UMTSWhat is UMTS ?Evolution of UMTSUMTS Architecture High LevelUMTS ArchitectureUMTS Architecture - DetailedUMTS Architecture - DetailedUMTS Architecture - DetailedUMTS Terrestrial Radio Access Network - UTRANUMTS Core NetworkUMTS - CS DomainUMTS - PS DomainCommon Databases - RegistersPower ControlHandoversHSDPA Vs HSUPAHSDPASlide 18