3g basic theory

Soc Classification level Presentation / Author / Date 1 © Nokia Siemens Networks

3G BASIC THEORY


WHAT IS 3G?WHAT IS 3G?

- stands for THIRD GENERATION mobile technology

- NTC clarified it viewed 3G as enhancement and improvement of the 2nd Generation Technology

- it is a wireless technology designed to allow a certain device to access to voice, video and data services at much faster rates than can be achieved today


OBJECTIVE:OBJECTIVE:To EXPLORE:

- The History and roadmap of mobile Telecommunication

- 3G Basic Technology

- 3G Basic Network Architecture

- 3G Basic Nature and Behavior


The mobile communications industry has evolved in three stages:

Voice call Voice call,fax, data and text messaging

1G 2G – 2.5 G 3G

High speed data transfer.

New video, audio and Mobile TV,Internet browsing and Music download


3G SERVICES 3G SERVICES


3G – 3rd Generation: Digital Cellular –

1) Feature: – Wide band code division multiple access (WCDMA)

technology– digital signal– Broadband (5Mhz Bandwidth)– integrated service system integrating all current mobile

telephone system functions providing multiple services– large capacity

2) Radio Frequency Spectrum (UHF – Ultra high Frequency)– frequency spectrum around 2000MHz or 2GHz – Data rate up to 2000kbps or 2Mbps


What triggered them to implement 3G?What triggered them to implement 3G?

Voice services currently account for more than 90 percent of income, but by the year 2005 it has been forecasted that data and other non-voice services will generate 50 percent of operator income.


What is IMT-2000What is IMT-2000

"International Mobile Telecommunications – 2000 (IMT-2000)

represents the global standard for meeting the emerging needs of

mobile telecommunications in the 21st century whereby mobile

telecommunications subscribers will be able to access voice, data,

Internet, and multimedia services at any time and at any place."


The Goal of IMT 2000

- Higher transmit rate 2Mbps

- Rich and colorful service

- Good voice quality

- Larger capacity

- Lower cost

- Good security performance

- High frequency efficiency

- Increased Mobility

- Easy to transition from 2G


U101 11

IMT-2000 Candidate Harmonization

A number of technologies were submitted many of which had distinct similarities

Of course operators were generally keen on a single standard to allow global roaming and economies of scale• Operators Harmonization Group (OHG)

This led to two partnership projects being set up:• 3rd Generation Partnership Project (3GPP)

– Dealing with WCDMA (Also Known as Universal Mobile Telephone Systems UMTS) and related candidate technologies

• 3rd Generation Partnership Project 2 (3GPP2)– Dealing with cdma2000 and related candidate

technologies


IMT 2000 Roadmap

HSDPA HSUPA

3GPP 3GPP23rd Generation Partnership Project


Where is Philippines?Where is Philippines?


1920M1920M 1980M1980M

（ Uplink ： 1920-1980 ）

2110M2110M 2170M2170M

（ Downlink ： 2110-2170 ）

1920-1980 2110-2170

Uplink Downlink

NTC Spectrum Allocation for WCDMA


1920M

1920M

1980M

1980M

（ Uplink ： 1920-1940 ）

2110M

2110M

2170M

2170M

（ Downlink ： 2110-2130 ）

1920-1940 2110-2130

Uplink Downlink

NTC Allocated for GLOBE 3G (WCDMA)

1960M

1960M

1980M

1980M

（ Uplink ： 1960-1980 ）

2110M

2110M

2170M

2170M

（ Downlink ： 2110-2170 ）

1960-1980 2150-2170

Uplink Downlink


RADIO FREQUENCIES

Where IS GLOBE 3G ?Where IS GLOBE 3G ?


Globe needs these 3G frequency spectra to upgrade its current CMTS (Cellular Mobile Telephone System) services to 3G.

Globe will remit the corresponding spectrum user fees and post a performance bond equivalent to P300 million to the NTC to comply with the rules on the allocation of 3G radio frequency bands.


HIERARCHICAL CELL STRUCTURES

Pico Cell

Few meters to 100

Micro cell

200 -500 meter range

Macro Cell

Few meters to 100


HIERARCHICAL CELL STRUCTURESMacro Cells - carry the faster-moving wide-area traffic.

Micro Cells carry the higher-data-rate pedestrian traffic.

Pico Cells are deployed to cover ‘hot spots’ to relive capacity bottlenecks such as in offices or airports where user density is particularly high.


WHAT IS WCDMA?

- stands for Wide-Band Code Division Multiple Access

- is a type of Cellular Network

- it is the higher speed transmission protocol used in the UMTS (Universal Mobile Telephone Systems)


W-CDMA is a wideband spread-spectrum mobile

Air-interface that utilizes the direct-sequence spread

Spectrum method of asynchronous code division

multiple access to achieve higher speeds and

support more users compared to the implementation

of time division multiplexing (TDMA) used by

2G GSM networks.


What is Bandwidth?

Bandwidth is the difference between the upper and lower cutoff frequencies, and is typically measured in hertz


What is the Bandwidth?

1920M1920M 1930M1930M

5Mhz


What is Code?

A code is a rule for converting a piece of information (for example, a letter, word, phrase, or gesture) into another form or representation (one sign into another sign), not necessarily of the same type.


Example of a Code?


• Scrambling Codes – Are used to separate cells and terminals from each other rather than

purely channels

A UE is surrounded by Base Stations, all of them transmitting on the same CDMA Frequency.

A UE must be able to discriminate between different Sectors of different Node B’s.

The Downlink Scrambling Codes can be used in 512 different ways in a CDMA system. Each one of them constitutes a mathematical code which can be used to identify a particular sector.

.

A BCode ChannelsScrambling Code 1

Code ChannelsScrambling Code 2

WCDMA CODE Scrambling Code


What is Multiple Access?

Imagine you are in a cocktail party…

Now imagine you are trying to talk to somebody

If you are trying to listen to somebody you need to be able to pick out their speech from everybody else’s speech

Everybody is using the same medium to talk – the air in the room

There are a number of different Multiple Access strategies…

Simultaneous private use of a transmissionmedium by multiple, independent users.


What is Channel?

An individually-assigned, dedicated pathwaythrough a transmission medium for one user’s information.


What is Transmission Medium

The transmission medium is a resource that can be subdivided into individual channels according to the technology used.

Each pair of users enjoys a dedicated,

private circuit through the transmission

medium, unaware that the other users exist.

Transmission

Medium


Types of Multiple AccessA. FDMA Frequency Division Multiple Access• Each user on a different frequency• A channel is a frequency


Types of Multiple AccessB. TDMA Time Division Multiple Access• Each user on a different window period in time (“time slot”)• A channel is a specific time slot on a specific frequency


Types of Multiple AccessC. CDMA Code Division Multiple Access• A channel is a unique code pattern• Each user uses the same frequency all the time, but

mixed with different distinguishing code patterns


CDMA Code Division Multiple Access

Frequency reuse factor is 1;network design and expanding become much easier

Frequency reuse factor is 1;network design and expanding become much easier

CDMA

5 MHz

1

1

11

1

11

11

1

11

1

1

Typical Frequency Reuse N=1


TRADITIONAL COMMUNICATION SYSTEM

TRADITIONAL COMMUNICATIONS SYSTEM

SlowInformation

Sent

TX

SlowInformationRecovered

RX

NarrowbandSignal

Traditional technologies try to squeeze the signal into the minimum required bandwidth


WCDMA COMMUNICATION SYSTEM

Spread spectrum systems mix their input data with a fast spreading sequence and transmit a wideband signal

The spreading sequence is independently regenerated at the receiver and mixed with the incoming wideband signal to recover the original data

.

SPREAD-SPECTRUM SYSTEM

FastSpreadingSequence

SlowInformation

Sent

TX

SlowInformationRecovered

RX

FastSpreadingSequence

Wideband Signal


SPREAD SPECTRUM SYSTEM HISTORY


What is SPREAD SPECTRUM SYSTEM?

Spread Spectrum techniques are methods by which more frequency bandwidth is deliberately used than motivated by the actual information rate (spectrum spreading). On one hand, this implies a certain waste of valuable frequency spectrum; but on the other hand,these techniques have advantages such as increasing the resistance to interference,jamming and interception.


Spread Spectrum Principles

Shannon's FormulaShannon's Formula

C=B*log2(1+S/N)

Where, C is capacity of channel, b/s B is signal bandwidth, Hz S is average power for signal N is average power for noise

Claude Shannon is the Father of Information Theory. It was entirely new that information of any kind-- whether for use on a telegraph, telephone, radio, or television-- could be decomposed into zeros and ones, encoded, transmitted, and decoded at the other end which is called the Mathematical Theory of Communication. He went on to present the concept of the maximum rate of transmission on a channel-- the capacity or "Shannon limit"-- which provides the benchmark against which all codes and modulations are measured.

Claude Shannon is the Father of Information Theory. It was entirely new that information of any kind-- whether for use on a telegraph, telephone, radio, or television-- could be decomposed into zeros and ones, encoded, transmitted, and decoded at the other end which is called the Mathematical Theory of Communication. He went on to present the concept of the maximum rate of transmission on a channel-- the capacity or "Shannon limit"-- which provides the benchmark against which all codes and modulations are measured.


SPREAD SPECTRUM SYSTEM ILLUSTRATION

5 MHz12.2 KHz

Power is “Spread” Over a Larger Bandwidth

MATHHAMMER

MATHHAMMER


SPREAD SPECTRUM SYSTEM

I. Frequency-Hopping Spread Spectrum (FH-SS)

The SS technique Frequency-Hopping Spread Spectrum (FH-SS) involves transmitting a signal with a “normal” bandwidth over a carrier frequency that rapidly changes within a wider frequency spectrum.

To decode the signal, thereceiver in the FH-SS system needs to know the frequency-hopping sequence – the“code.”

FH-SS was first developed by scientist Nicola Tesla around 1900


SPREAD SPECTRUM SYSTEM

II. Direct Sequence Spread Spectrum (DS-SS)

It is SS principle wherein the carrier frequency stays the same, but instead the signal to be transmitted is multiplied with a high bandwidth signal.

On the receiving end, the reproducible high bandwidth signal – the “code” – is multiplied with the received signal to recover the original signal.


U101 42

Tx Bit Stream

Rx Bit Stream

Code Chip Stream (Spreading Code)

Air Interface Chip Stream

1

-1X

X

Spreading

Despreading

Spread

SPREADIND AND DESPREADING

1

-1

Code Chip Stream (Spreading Code)


What is CHIP?

It is a pulse of a direct-sequence spread spectrum (DSSS) Code

WCDMA CHIP RATE: 3.84 Mcps

1

-1

pseudo-noise code sequence


WCDMA Architecture

Iu

Iur

RNC

RNC: RadioNetwork

ControllerSGSN

GGSN

AuCHLREIR

VLR

G-MSC

MSC

cellcell

cellcell

cellcell

cellcell

cell

Uu

US

IMU

SIM

US

IM

FDD modeonly

UE: User Equipment N

od

e BN

od

e BN

od

e B

RNS: Radio Network Subsystem

RNS

CN: Core Network

IuCS

IuPSIub

Gc

Gr

Gs Gf

D

B

F C

PSTN

EE

GiGn

Gp

ME

ME

ME


WCDMA - GSM Architecture

A-bis

Iub

Interface

Interface


UTRAN (Universal Terrestrial Radio Access Network) Structure

RNS RNS

NodeB NodeBNodeB NodeB

RNC

CN

RNC

Iu Iu

Iur

Iub IubIub Iub

UE

UuUTRAN UTRAN


WCDMA Architecture

The system consists of:

• UTRAN

UTRAN performs all the functions related to wireless communication;

• CN (Core Network)

CN switches and routes voice and data services to connect them to the external network.

• UE (User Equipment)

The UE (User Equipment) is connected to the UTRAN through the air interface standard.


Functional Units

UE (User Equipment):

As the wireless terminal that performs wireless communication via the Uu interface, it contains an intelligent card, which records the user ID, performs the authentication algorithm, and stores information such as authentication information and keys.

Node B:

Transmits data streams between the Iub and the Uu interfaces, participating in radio resource management.

RNC (Radio Network Controller): Owns and controls the radio resources under its

administration. The RNC is the service access point provided by the UTRAN for the CN.


INTERFACE

Uu interface:

Serves as the air interface of the WCDMA system to connect a UE to a Node B.

Iu interface: Connects the UTRAN and the CN. It is similar to the A

interface (circuit switching) and the Gb interface (packet switching) in GSM.

Iur interface:Allows soft handover between the RNC equipment of

different manufacturers as an open interface.

Iub interface:

Connects the Node B and the RNC.


WCDMA Basic Nature and Behavior - Cell Breathing

Breath effect of cell

• With the increase of activated

terminals, interference increase

• the increase of high speed service,

the increase of interference

• The shrink of cell coverage area

• Coverage blind spot occurs

• Drop of call will happen at the edge of cell

Coverage and capacity are

relative

backback


Coverage/capacity vs Data Rate

>12.2 kbps

>64 kbps

>384 kbps

>144 kbps

Coverage decrease

Subscriber num increase

Higher rate needs higher power

High data rate transmission is only available nearby the station


Multipath Propagation

Received SignalReceived Signal

TimeTime

StrengthStrength

00

TransmitTransmit


Multipath Propagation


RAKE Receiving

RAKE improve receive capability

receiver

Single receiving

Single receiving

Single receiving

searcher calculate

combining

tt

s(t) s(t)

signal


Use handoff: minimize drop-call rateUse handoff: minimize drop-call rate

WCDMA Behavior: HANDOVER

sssssssss

Handover is the process of shifting a mobile device’s connection from one Node B to another


TYPES OF HANDOVER

I. Intra-System (WCDMA) Handover a. SOFTER HANDOVER Mobie Station handover within one node B between different sectors –

b. SOFT HANDOVER - Mobile Station handover between different Node B.

c. Hard HANDOVER - Mobile Station handover between different frequencies

II. Inter-System HandoverHandover between WCDMA <--> GSM (Hard)

Handover between WCDMA/FDD <--> TDD (Hard)


WCDMA Power ControlWhy need Power Control?

- All User Equipment transmit on the same frequency

- UE with low path loss will cause large interference

- Removes Near –Far Effect – Variation of power level and interference due to distance and fading


WCDMA Power Control

•Goal: Adjust transmit power so that all mobile terminals are received with approximately the same power

•Set PTX,1 and PTX,2 so that PRX,1 ~ PRX,2


WCDMA Power Control

Open loop power control (No feed Back from the Node B)

If received signal is stronger,then UE can transmit lowerIf received signal is weaker,then UE can transmit stronger

To provide a course initial power setting of the mobile station at the beginning of a connection.

Closed Loop - With feed back from the Node B. Base station informs mobile unit to increase or decrease the power level

3g basic theory

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