evolution of 1g to 4g

INTRODUCTION TO GSM

ObjectivesObjectives

To provide participants with a comprehensive introduction to GSM concepts, features, services and definitions, and also introduce the emerging 3G technology and the services and applications that it offers.

ContentsContents1. Realities of the Changing World2. History of Wireless Communications3. Emerging Markets4. Mobile Growth5. Radio Theory Principles6. Modulation Techniques7. Radio Fundamentals8. Global Systems for Mobile (GSM)9. Technology10. Frequency Reuse11. GSM Architecture12. Third Generation (3G) Systems13. 4G Networks14. Mobile Service Evolution

Realities of a Changing Telecon World

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Realities of a Changing Realities of a Changing Telecom WorldTelecom World


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History of Wireless History of Wireless CommunicationCommunication

1906—Human voice was successfully transmitted over RADIO.

1921—Detroit police dept. used 2 Mhz frequency in vehicular mobile radio.

1930—Amplitude Modulation was invented 1935---Frequency Modulation was invented (improved

audio quality). 1947—Bell labs. Envisions the cellular concepts. 1991—First digital cellular standard (GSM) is launched 1998—No. of subscriber world wide has grown to over

200 million.

Emerging MarketsEmerging Markets

Emerging Networks and Markets– Three Change Agents

CompetitionTechnologyCustomer Awareness

Emerging MarketsEmerging Markets

New Technologies– Mobile communications

Fixed wireless Nomadic wireless Full mobile wireless

– Internet – led to: Next-Generation-Network technology

Telecom growth globally over next five years is forecast to be:

– 350 Million new users per year, or

– 1 Million every day, or

– 10 new subscribers every second

– By the time we discussed this slide, another 1000 people will have become telecom users

For most of these it will be their first phone – probably mobile

For half of these it will be their first camera, music player or high speed Internet access

Mobile GrowthMobile Growth

Most of this growth will happen on mobile (wireless) platform


Challenge for fixed-wireline service providers:– Mobile is:

Untethered by fixed infrastructure Simplicity of service provisioning Promise of Next-Generation-Service repertoire

including:– Triple play and

– Quad-play service packages


Latest Generation – 4G – allows mobile service providers to offer services similar to fixed wireline services or betterat prices similar to fixed wireline or better



• ITU Telecom World 06 (Day 1) says:• PSTN as fixed line revenue generator is in

decline• Voice is moving to IP and mobile • Competitors are not encumbered by installed

infrastructure, especially not mobile operators• Can offer faster, cheaper, feature rich services

on mobile or fixed wireline NGN platform


• ITU Telecom World 06 (Day 1) says:• Only reason that mobile and fixed wireline

networks are not converged in most countries is due to Regulation

• Technically, there is no barrier

Mobile EvolutionMobile Evolution

Mobile networks are identified by technology applied: Generation• 1G: (first Generation): analog, voice only

• 2G: (second Generation): digital, GSM, voice and data

• 2.5G: enhanced GSM, circuit switched voice and packet switched data • GPRS circuit improved data rates from 2G GSM

• EDGE improved data rates from GSM GPRS

• 3G: WCDMA UMTS enhanced data rates, packet switched voice and data

• 4G: all IP, true broadband data

Mobile EvolutionMobile Evolution• Mobile network evolution:


1G – introduced 1983:• Analog• Voice only• No global Standards

– Northern Europe: NMTS (Nordic Mobile Telephone System)

– UK and Ireland: TACS (Total Access Communication System)

– North America: AMPS (Advanced Mobile Phone System)

• Only limited roaming and only within the same network


2G – introduced 1990:• Digital • Two technologies• North America:

– CDMA (Code Division Multiplex) developed by Qualcom

– Geographically limited application

• Europe, Asia and ROW (Rest of the World):– TDMA (Time Division Multiplex) leading to GSM

(Global System for Mobile Communication)

– Most widely used worldwide, approx. 90% of global users are on GSM platform and later


2G GSM and VAS (Value Added Services):• Addition of two platforms:

• VMS (Voice Mail System)

• SMSC (Short Message Service Centre)

• Later IN (Intelligent Services) was added to VAS:– Fraud Management

– Pre-Paid services


2.5G GSM GPRS (General Packet Radio Service):• Result of data traffic increasing to the point

where it has now overtaken voice traffic on the network • Data packet handling through a Packet Core

Network

• Network now contains servers, routers and firewall

• Maximum data speed 150Kbps

• Voice still circuit switched


2.5G GSM EDGE (Enhanced Data rates in GSM Environment):• Data rate had to be increased to handle data

traffic on the mobile network• Better coding methods

• Led to maximum data speed of 384Kbps

• Even though packetized data transfer, still behaved like a circuit switched network because voice is still circuit switched


3G UMTS: WCDMA (Wideband Code Division Multiplex Access) in UMTS (Universal Mobile Terrestrial System):• North America:

• cdma2000

• Europe, Asia and ROW:• UMTS

• WCDMA is air-interface technology for UMTS• Enables high capacity data services: video, music,

imaging

• Data speeds up to 2Mbps


4G All-IP (Internet Protocol):• Next-Generation-Network

• Lower CAPEX

• Lower OPEX

• More efficient

• Larger service repertoire

• Data rates up to 14.4Mbps, although trials at NTT DoCoMo reached 5Gbps

• Calls for open, adaptive programmable Business Model


4G All-IP (Internet Protocol):• 4G Business Model imperatives:

– Boundaries between mobile operator and content providers are clearly defined through reference points and open APIs (Application Program Interface)

– Must ensure interoperability between all parties, their respective business roles and services provided

– Different evolution cycles of individual parts of the system are built for quick adaptive actions

• Requires layered architectural approach


• 1G through 3G, including 2G, 2.5G GPRS and EDGE:• Evolution based on technology enhancements

• 4G is a convergence strategy better utilizing existing technologies• Two camps:

• WiMAX• UMTS LTE (Long Term Evolution)


• 3GPP2 (3rd Generation Partnership Project):• a collaboration between groups of telecommunications

associations supported by major cellular carriers worldwide

• Established in 1998

• Production of Technical Specifications for a 3rd Generation Mobile System based on the evolved GSM core networks

• Later expanded to include standards and specifications for continued operation, maintenance and optimization of 2G GSM, GPRS and EDGE


• 3GPP2 (3rd Generation Partnership Project 2):• Formed by Standards Development Organizations

worldwide to develop standards leading to 4G

• Supported by over 70 cellular telecommunications companies worldwide

• Established in 2003

• Introduced concept of Long Term Evolution of UMTS technology (UMTS LTE)


Network Evolution

Radio Theory Principles

FREQUENCY SPECTRUM What is Frequency Spectrum?Electric and magnetic fields that produce waves

moving through space at different frequencies Set of all possible frequencies called the

“electromagnetic” spectrum Nearly 300 billion frequencies

– ≈1% is below 300GHz fitting into Radio Spectrum– 90% of spectrum use is within this range

• Wireless communications and entertainment use– Therefore, need for spectrum allocation within this range

• To prevent congestion which can lead to interference– For proper allocation and management, spectrum is sliced

into frequency bands

FREQUENCY SPECTRUM Frequency Spectrum Subsets:

Radio spectrum: 3000Hz to 300GHz• Does not require a medium

• Travels at speed of light

• Can carry energy and messages

Long wave: below 3000Hz Light spectrum: above 300GHz

• Requires a medium (fibre optics) to be used in telecommunications

• Not under spectrum management rules

X-ray and gamma-ray frequencies even higher

WIRELESS SPECTRUMElectromagnetic SpectrumElectromagnetic Spectrum

Includes:Includes:

•Usable radio frequency spectrum Usable radio frequency spectrum (3KHz to 300 GHZ)(3KHz to 300 GHZ)

•Most usable spectrum for Most usable spectrum for communications purposescommunications purposes

•Higher frequencies are in light Higher frequencies are in light or or optical spectrumoptical spectrum

•Communications applications Communications applications are primarily fibre optics are primarily fibre optics transmissiontransmission

Source: Louis E. Keiner, Coastal Carolina UniversitySource: Louis E. Keiner, Coastal Carolina University

RADIO SPECTRUM

Radio Spectrum Radio Spectrum suitable for suitable for TelecommunicationsTelecommunications

Ranges from:Ranges from:

•3KHZ – Very Low Frequency 3KHZ – Very Low Frequency (VHF)(VHF)

toto

•300GHz – Extremely High 300GHz – Extremely High Frequency (EHF)Frequency (EHF)

Source: Source: www.wikipedia.org www.wikipedia.org

RADIO SPECTRUM

Ultra High FrequencyUltra High Frequency

Applications:Applications:

UHF = 300MHz to 3GHzUHF = 300MHz to 3GHz

•Suitable for telecommunications purposesSuitable for telecommunications purposes

•UHF television, mobile phone service, two-way radioUHF television, mobile phone service, two-way radio

•Usually frequency modulated, relatively narrow-bandUsually frequency modulated, relatively narrow-band

Radio spectrumELF SLF ULF VLF LF MF HF VHF UHF SHF EHF

3 Hz 30 Hz 300 Hz 3 kHz 30 kHz 300 kHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz

30 Hz 300 Hz 3 kHz 30 kHz 300 kHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz 300 GHz

RADIO SPECTRUM

Lower frequencies:Lower frequencies:

Generally:Generally:

•Long distanceLong distance

•Narrow bandwidthNarrow bandwidth

•Follow contour of EarthFollow contour of Earth

Radio spectrumELF SLF ULF VLF LF MF HF VHF UHF SHF EHF

3 Hz 30 Hz 300 Hz 3 kHz 30 kHz 300 kHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz

30 Hz 300 Hz 3 kHz 30 kHz 300 kHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz 300 GHz

Higher frequencies:Higher frequencies:

Generally:Generally:

•Short distanceShort distance

•High bandwidthHigh bandwidth

•Require Line of SightRequire Line of Sight

Attributes:Attributes:

RADIO SPECTRUM

• Use of the Radio Spectrum is hotly contested

• Principal uses of the various segments of the radio spectrum are:Determined by the physical characteristics of the

individual frequency bands• For instance: TV broadcasting and mobile

communications are constrained within a relatively small part of the radio spectrum

• Furthermore limited by need to cater for other uses such as aeronautical, scientific, emergency and military applications.

RADIO SPECTRUM

• Finite resourceThe radio spectrum comprises the total free space frequencies

available for telecommunicationsNo additional frequencies can be added

• Inexhaustible resourceOccupied by use but not consumedHowever, only one user per frequency band

– In a specific geographic area– At the same time– Can be reassigned for different areas provided there is sufficient

geographic separation

• FlexibleEasily deployedLess expensive than physical infrastructureHowever, application dependent on characteristic of frequency band

RADIO SPECTRUM

• Therefore,Tightly managedGlobal, regional and national control and management

• Global managementITU (International Telecommunications Union):

– Through Standards (Recommendations)

– Through World Radio Conferences

– Fostering cooperation

• Regional managementAfrican Telecommunications Union (ATU)

• Coordination of national interests

• Through Regional Radio Conferences

• Recommendations

ITU SPECTRUM REGIONSWiMAX and WiFi Frequencies by Region:WiMAX and WiFi Frequencies by Region:

Source: WiMAX Forum – A New Broadband Wireless Technology

Modulation Techniques

PHYSICAL CHARACTERISTICS

ITU Frequency Band Nomenclature

ITU Band Designation Frequency Wavelength

1 ELF 3 - 30 Hz 100,000 km - 10,000 km

2 SLF 30 - 300 Hz 10,000 km - 1000 km

3 ULF 300 - 3000 Hz 1000 km - 100 km

4 VLF 3 - 30 kHz 100 km - 10 km

5 LF 30 - 300 kHz 10 km - 1 km

6 MF 300 - 3000 kHz 1 km - 100 m

7 HF 3 - 30 MHz 100 m - 10 m

8 VHF 30 - 300 MHz 10 m - 1 m

9 UHF 300 - 3000 MHz 1 m - 10 cm

10 SHF 3 - 30 GHz 10 cm - 1 cm

11 EHF 30 - 300 GHz 1 cm - 1 mm

TRANSMISSION BASICS Radio Communications:• One-way only (Simplex):

• Transmission in one direction only

• Usually full frequency band assigned to one simplex channel

Tx Rx

Transmitter Receiver

A B

TRANSMISSION BASICS Radio Communications:• Two-way (Duplex):

• Transmission in both directions at the same time, however at different frequencies within one band

• Frequency bandwidth split into two channels (Frequency Division Duplexing – FDD)

Tx Rx


A B

Rx Tx

Receiver Transmitter

TRANSMISSION BASICSRadio Communications:• Two-way (Half-duplex):• Transmission in both directions, however at different

times at the same frequencies• Full bandwidth used for transmission in either direction

Tx

Rx

Rx

Tx


A B

Receiver Transmitter

TRANSMISSION BASICSTRANSMISSION BASICS

Information carried by carrier wave can be either analog Information carried by carrier wave can be either analog or digitalor digital

Analog SignalsAnalog Signals

Naturally produced sounds– Speech– Music– Others

First telecommunications transmissionContinuous signal made up of varying

current and voltage

Analog SignalsAnalog SignalsSine wave formSine wave form

Signal Strength = AmplitudeSignal Strength = Amplitude

Repeat of a 360Repeat of a 360º wave over time = Frequencyº wave over time = Frequency

Analog SignalsAnalog Signals Amplitude modulation is volume, strength Frequency modulation is pitch Suspect to noise and signal degradation

– Noise is added to signal distorting original sine wave– Affects frequency– Difficult to regenerate– Degradation affects amplitude– Difficult to correct

Proper grounding of all components is mandatory

Digital SignalsDigital Signals

Machine generatedState over time: 0 and 1Measured in bits/secondEasily regeneratedBetter suited for telecommunications

transmission than analogAnalog to digital conversion and vice versa:

Modem (Modulator/Demodulator)

Digital SignalsDigital Signals• State:State:

• Either ON or OFF,Either ON or OFF,

• Also “1” or “0”Also “1” or “0”

Digital SignalsDigital Signals

Source: Source: http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/info/signals/digital/digital.htmhttp://www.st-andrews.ac.uk/~www_pa/Scots_Guide/info/signals/digital/digital.htm

DIGITAL SIGNALSDIGITAL SIGNALS

More efficient use of bandwidthEasy integration with PCS devicesMaintains higher quality of voice transmission

over longer distancesMore difficult to decodeCan use lower transmit powerUses smaller and less expensive transmission

equipmentOffers voice privacy

MODULATION TECHNIQUES

Analog Modulation Techniques:• Purpose:

To place information onto a carrier wave for transmission

• Amplitude modulation• Frequency modulation• Phase modulation• Combination of different techniques


Amplitude modulation:• Information is placed onto carrier signal

affecting amplitude


Frequency modulation:• Information is placed onto carrier signal

affecting its frequency

MODULATION TECHNIQUESPhase modulation:• Information is placed onto carrier signal

affecting its timing (phase)


Amplitude and Phase modulation:• Information is placed onto carrier signal

affecting its amplitude and its timing

MODULATION TECHNIQUESMODULATION TECHNIQUES

Modulation of Analog SignalsModulation of Analog Signals

Digital Modulation TechniquesDigital Modulation Techniques

The principal classes of modulation are:

• Phase-shift keying (PSK) • Frequency-shift keying (FSK) • Minimum-shift keying (MSK) • Gaussian minimum-shift keying (GMSK) • Amplitude-shift keying (ASK) and its most common form, on-off keying (OOK) • Quadrature amplitude modulation (QAM) a combination of PSK and

ASK • Continuous phase modulation (CPM) • Polar modulation like QAM a combination of PSK and ASK, but using a different circuit architecture


Amplitude Shift Keying:• Amplitude of carrier wave is determined by logic state of

digital signal


Frequency Shift Keying:• Frequency of carrier wave is determined by logic state of

digital signal


MODULATION TECHNIQUESPhase Shift Keying:• Phase of carrier wave is determined by logic state of

digital signal

Radio Fundamentals

PROPAGATIONPROPAGATION

Propagation:

Propagation: Most common:

– Line-of sight propagation Transmitting and receiving antennae are in sight of each

other Raising either antenna will increase distance

– Ground wave propagation Signals follow curvature of the earth Looses energy to the ground

– Sky wave propagation Signals are bent by the Ionosphere Cover large distances, some signals escape



Line-of sight propagation

PROPAGATIONPROPAGATIONLine-of sight propagation• Transmitting and receiving antennas must be within

line of sight– Satellite communication – signal above 30 MHz not

reflected by ionosphere– Ground communication – antennas within effective line of

site due to refraction

• Refraction – bending of microwaves by the atmosphere– Velocity of electromagnetic wave is a function of the

density of the medium– When wave changes medium, speed changes– Wave bends at the boundary between mediums

PROPAGATIONPROPAGATIONSummary:

Source: WRAP, Aerotech Telub.seSource: WRAP, Aerotech Telub.se

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FRESNEL ZONEFRESNEL ZONE

Definition:

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Side view:

Source: Alcatel Microwave Propagation Path DesignSource: Alcatel Microwave Propagation Path Design

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Cross sectional View:


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Obstruction Effect:


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FRESNEL ZONEFRESNEL ZONEPath Clearance Requirement:Simple line of sight is not sufficient

First Fresnel Zone clearance is required


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POWERPOWER

Transmission Power:

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IMPAIRMENTSIMPAIRMENTSPropagation Losses• Free-Space Propagation

−Loss between two points in free space• Reflection

−Out of phase signals can fade 35-40 dB−In phase signals can give 6 dB upfades

• Refraction−Impact similar to reflection

• Rain Attenuation−Significant only above 7 GHz

• Fog and Clouds−Only above ~ 20 GHz

• Diffraction−Insufficient clearance over intermediate terrain

• Airborne Particles−Sand and dust−Above ~ 14 GHz

• Atmospheric Absorption−Caused by the oxygen and water molecules−Above ~ 8 GHz

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IMPAIRMENTSIMPAIRMENTSFree Space Propagation Losses

>Free Space Loss•The basic transmission loss between transmit and receive antennas in free space•This is the dominant propagation loss

>FSL(dB)= 96.6 + 20 Log D + 20 Log Fwhere: FSL=Free-space loss in dB

D=Path length in milesF=Frequency in GHz

>The bottom line•Doubling either the path length or the frequency will increase the path loss by 6 dB

Noise:

NOISENOISE

• Intermodulation noise – occurs if signals with different frequencies share the same medium– Interference caused by a signal produced at a frequency

that is the sum or difference of original frequencies• Crosstalk – unwanted coupling between signal paths• Impulse noise – irregular pulses or noise spikes

– Short duration and of relatively high amplitude– Caused by external electromagnetic disturbances, or

faults and flaws in the communications system

Atmospheric Impairments:

ATMOSPHERIC IMPAIRMENTSATMOSPHERIC IMPAIRMENTS

• Atmospheric absorption – water vapor and oxygen contribute to attenuation

• Multipath – obstacles reflect signals so that multiple copies with varying delays are received

• Refraction – bending of radio waves as they propagate through the atmosphere

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REFRACTIONREFRACTION

Types of Refraction


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Refraction:


>The ability of a medium to bend an electromagnetic wave as it passes through that medium

•The amount of bending is described by the index of refraction>Index of Refraction (“little n”)

•Measurement of the relative density of a medium•n = c / v

c = Velocity of light in free spacev = Velocity of rf signal in earth’s atmosphere

•n ~ 1.0003 under “normal” conditions in the ABL (Atmospheric Boundary Layer)

>Radio Refractivity (“big N”)•N = ( n-1 ) * 106•N ~ 300 N-units under “normal” conditions

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Refraction causes tunnelling


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Refraction causes bending


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>Radio Refractivity for signals up to about 30 GHz can be calculated using the following equation.

•N = (77.6 * P/T) + (3.73 X 105* e/T2)Where:

N = Radio Refractivity in N-unitsP = Atmospheric pressure in millibarsT = Temperature in degrees Kelvine = Water vapor pressure in millibars

>Radio Refractivity Gradient•The change in refractivity with height •For “standard” atmospheric conditions

−-100 < dN/dh < 0 N-units / km

Large radio refractivity gradients are the nemesis for line of sight microwave signals

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Refraction


RAIN ATTENTUATIONRAIN ATTENTUATION

Rain Attenuation:Rain Attenuation:

• Can limit distance between sitesCan limit distance between sites

• Can diminish available bandwidthCan diminish available bandwidth

• May call for Space Diversity protectionMay call for Space Diversity protection

• Higher frequencies are especially vulnerableHigher frequencies are especially vulnerable

• Can cause Fading (signal loss)Can cause Fading (signal loss)

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RAIN ATTENUATIONRAIN ATTENUATION

Rain Attenuation


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Fading (loss of signal):

FADINGFADING

• Fast fading• Slow fading• Flat fading• Selective fading• Rayleigh fading• Rician fading

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MULTIPATH PROPAGATIONMULTIPATH PROPAGATION

• Reflection - occurs when signal encounters a surface that is large relative to the wavelength of the signal

• Diffraction - occurs at the edge of an impenetrable body that is large compared to the wavelength of a radio wave

• Scattering – occurs when an incoming signal hits an object whose size in the order of the wavelength of the signal or less

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MULTIPATH PROPAGATIONMULTIPATH PROPAGATIONMultipath Propagation (example):

Multipath Propagation Mechanisms: R – Reflection, S – Scattering, Multipath Propagation Mechanisms: R – Reflection, S – Scattering, D - Deflection D - Deflection

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Effects of Multipath Propagation:

MULTIPATH PROPAGATIONMULTIPATH PROPAGATION

• Multiple copies of a signal may arrive at different phases

– If phases add destructively, the signal level relative to noise declines, making detection more difficult

• Intersymbol interference (ISI)

– One or more delayed copies of a pulse may arrive at the same time as the primary pulse for a subsequent bit

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Space Diversity is applied

SPACE DIVERSITYSPACE DIVERSITY

• Where reflection causes out-of-phase transmissions

– Can be over water– Can be caused by rain

• Where First Fresnel Zone can not fully clear path obstructions

• Other out-of-phase or delay problems

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SPACE DIVERSITYSPACE DIVERSITYTypical Space Diversity architecture


ANTENNA CONSIDERATIONSANTENNA CONSIDERATIONS>Antenna Gain

•A measure of how well the antenna concentrates its radiated power in a given direction•Defined as the ratio of the power radiated in a given direction to the power radiated in the same direction by a isotropic antenna


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ANTENNA ANTENNA CONSIDERATIONSCONSIDERATIONS

Radiation Pattern


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ANTENNA CONSIDERATIONSANTENNA CONSIDERATIONS

Imperfections


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Radiation Power Distribution


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Parabolic Antenna Beamwidth Example


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Link BudgetLink Budget

Components in calculating:Components in calculating:

Transmission LossAtmospheric Attenuation

Tx Rx

Tx Antenna Gain

EIRP

Filters, Feeder,etc.

Filters, CableLoss


Rx Antenna Gain

Source: WRAP, Aerotech Telub.seSource: WRAP, Aerotech Telub.se

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Link BudgetLink BudgetWhat is a Link Budget?What is a Link Budget?

Source: Wikipedia.orgSource: Wikipedia.org

A link budget is the accounting of all of the gains and losses from the transmitter, through the medium (free space, cable, waveguide, fiber, etc.) to the receiver in a telecommunication system. It takes into account the attenuation of the transmitted signal due to propagation, as well as the loss, or gain, due to the antenna. Random attenuations such as fading are not taken into account in link budget calculations with the assumption that fading will be handled with diversity techniques.

A simple link budget equation looks like this:

Received Power (dB) = Transmitted Power (dBm) + Gains (dB) - Losses (dB)

Can have different meanings:

BANDWIDTHBANDWIDTH

In an analog system:• bandwidth is the range of frequencies occupied by a

modulated carrier wave,• a measure of how wide a function is in the frequency

domain

In a digital system:• has a dual meaning

– Baud rate (speed of transmission)– Channel capacity (throughput: # of channels x speed)

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Reasons for Interference

The transmission path is very complex, ranging from the simple line-of-sight transmission to encountering such terrain as buildings, hills and trees. Wireless channels are extremely unpredictable.

Abrupt drop, or fading, of signal strength in the land mobile wireless channel is quite common. The fading feature of the mobile channel depends on the radio wave propagation environment.

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Reasons for interference

Environmental factors:

• Terrain (mountains, hills, plains, water bodies, etc.);

• The quantity, heights, distribution and materials of buildings;

• The vegetation of the region;

• Weather conditions;

• Natural and artificial electromagnetic noises;

• Frequency;

• How MS is moved.

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Co-Channel Interference

Conception: The interference among the signals of co-channel cells is called co-channel interference.

Result from :Frequency reuse

Reduction method:Co-channel cells must physically be spaced at a minimum interval to ensure adequate isolation of transmissions.

Interference

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Adjacent Channel Interference

Conception: The signal interference from the

frequency adjacent to that of the signal used is called adjacent channel interference.

Reduction method: Accurate filtering and channel allocation

(maximizing channel intervals of the cell). Interval of frequency reuse inter-cell interference, such as C/I, C/A

Interference

2G - GSM2G - GSM

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What is …?What is …?

GSM (Global System for Mobile Communication) Based on TDMA technology Mainly used in Europe, Middle-east and Africa

CDMA (Code Division Multiple Access)

Based on a spread-spectrum technology

Mainly used in North America

GSM formerly: Groupe Spéciale Mobile (founded 1982) now: Global System for Mobile Communication Pan-European standard (ETSI, European

Telecommunications Standardisation Institute) simultaneous introduction of essential services in three

phases (1991, 1994, 1996) by the European telecommunication administrations (Germany: D1 and D2) seamless roaming within Europe possible

today many providers all over the world use GSM (more than 184 countries in Asia, Africa, Europe, Australia, America)

more than 70% of all digital mobile phones use GSM over 10 billion SMS per month in Germany, > 360

billion/year worldwide

Performance characteristics of Performance characteristics of GSMGSM

Communication mobile, wireless communication; support for voice and data services

Total mobility international access, Worldwide connectivity

High capacity better frequency efficiency, smaller cells, more customers per cell

High transmission qualityhigh audio quality and reliability for wireless, uninterrupted phone

calls at higher speeds (e.g., from cars, trains)Security functions

access control, authentication

GENERATION OF GSMGENERATION OF GSM

1st generation:- Analog mobile technologies :- AMPS , TACS & NMT.

2nd generation:- digital mobile technologies :- GSM , CDMA

2.5generation:- Enhancement of GSM:- GPRS

3rd generation:- Technologies coursed by ITU-IMT

The following table lists the key events in the GSM evolution

GSM

EDGE

2.5 G

GPRS

2G

2.5 g+

UMTS 3G WCDMA

GSM STANDARDSGSM STANDARDS

GSM-900 Standard

The GSM-900 standard is a standard for digital voice transmission in the 900 MHz band. This so called “primary band" includes two sub bands of 25 MHz

GSM-1800 Standard

In GSM-1800, 1800 MHz band was allocated for digital mobile telephone services which has frequency of 75 MHz. This was three times the bandwidth allocated for GSM-900.

GSM-1900 Standard

GSM-1900 is the standard for the 1900MHz band. It includes the same network component as the GSM-900 or GSM-1800. The band width of this standard is 60 MHz.

GPRS - Wireless Data Services . EDGE -- Provides 3 times the data capacity of

GPRS. 3G --- Uses WCDMA technologies Over Air

interface (5MHz).

Basic Features Provided by GSMBasic Features Provided by GSM

Call Waiting- Notification of an incoming call while on the handset

Call Hold- Put a caller on hold to take another call

Call Barring- All calls, outgoing calls, or incoming calls

Call Forwarding- Calls can be sent to various numbers defined by the user

Multi Party Call Conferencing- Link multiple calls together

Advanced Features Provided by GSMAdvanced Features Provided by GSM

Calling Line ID- incoming telephone number displayed

Alternate Line Service- one for personal calls- one for business calls

Closed User Group- call by dialing last for numbers

Advice of Charge- tally of actual costs of phone calls

Fax & Data- Virtual Office / Professional Office

Roaming- services and features can follow customer from market to market

Advantages of GSM Advantages of GSM

Crisper, cleaner quieter calls Security against fraud and eavesdropping International roaming capability in over 100 countries Improved battery life Efficient network design for less expensive system expansion Efficient use of spectrum Advanced features such as short messaging and caller ID A wide variety of handsets and accessories High stability mobile fax and data at up to 9600 baud Ease of use with over the air activation, and all account

information is held in a smart card which can be moved from handset to handset

Future -- UMTS (Universal Mobile Future -- UMTS (Universal Mobile Telephone SystemTelephone System

Reasons for innovations- new service requirements- availability of new radio bands

User demands- seamless Internet-Intranet access- wide range of available services- compact, lightweight and affordable terminals- simple terminal operation- open, understandable pricing structures for the whole spectrum of

available services

SpectrumSpectrum

GSM uses paired radio channelsGSM uses paired radio channels

0 124 0 124

890MHz 915MHz 935MHz 960MHz

UPLINK

DOWNLINK

Capacity & Spectrum Utilization SolutionCapacity & Spectrum Utilization Solution

The need: Optimum spectrum usage More capacity High quality of service Low cost

I wish I could increase capacitywithout adding NEW BTS!

What can I do?

Network capacity at required QoSwith conventional frequency plan

Subscriber growth

Time

Out of Capacity!!!

Multiple access schemes• "keep away from my frequency" (Titanic 1912)

FDMA - Frequency Division Multiple Access (since 1920s)• radio broadcasting• regulation of frequencies was started• 1st generation mobile systems (NMT, TACS, …)

TDMA Time Division Multiple Access (1980-)• 2nd generation mobile systems: GSM, US-TDMA, PDC

(Personal Digital Cellular)• narrowband systems

Code Division Multiple Access (late 1990s-)• 3rd generation mobile systems: WCDMA, CDMA2000

Radio spectrum availability

TechnologyTechnology

FDMA (Frequency division Multiple Access)

TDMA (Time division Multiple Access)

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Technology: FDMATechnology: FDMA Transmission over Radio Frequency (800MHz – 1900MHz) Frequency Division Multiple Access

An analog system. Each user is given one channel (i.e., one frequency). Bad utilisation.

CH 1CH 2CH 3CH

4

Frequency

Time

Pow

er

DIFFERENT TYPE OF TECHNOLOGIES USED IN GSM

FDMA (Frequency division Multiple Access) In FDMA, signals from various users are assigned different frequencies.

Frequency guard bands are maintained between adjacent signal spectra to minimize crosstalk between channels.

Advantages of FDMA

1. Capacity increase can be obtained by reducing the information bit rate and using efficient digital codes.

2. Technological advances required for implementation are simple. A system can be configured so that improvement in terms of speech code bit rate reduction could be readily incorporated.

Disadvantages of FDMA The maximum bit rate per channel is fixed and low, inhibiting the flexibility in bit-

rate capability that is needed for computer file transfers

Frequency multiplexFrequency multiplex

Separation of the whole spectrum into smaller frequency bands A channel gets a certain band of the spectrum for the whole time Advantages:

no dynamic coordination necessary

works also for analog signals Disadvantages:

waste of bandwidth if the traffic is distributed unevenly

inflexible guard spaces

k2 k3 k4 k5 k6k1

f

t

c

147

Technology: TDMATechnology: TDMA

GSM uses TDMA (Time Division Multiple Access)

CDMA is a "spread spectrum" technology, allowing many users to occupy the same time and frequency allocations in a given band/space. Each mobile station has a unique digital code. The signals are spread over the entire spectrum of 1.25MHz unlike FDMA/TDMA.

Chann

el 1

Chann

el 2

Chann

el 3

Chann

el 4

Frequency

Time

Pow

er

TDMA (TIME DIVISION MULTIPLE ACCESS)

In a TDMA system, data from each user is conveyed in time intervals called “Time slots”. Several slots make up a frame . Each slot is made up of a preamble plus information bits addressed to various stations .the functions of the preamble are to provide identification and incidental information and to allow synchronization of the slot at the intended receiver .Guard times are used between each user’s transmission to minimize crosstalk between channels.

Advantage of TDMA 1) TDMA permits a flexible bit rate. 2) TDMA offers the opportunity for frame-by-frame monitoring of the signal

strength and bit error rates. 3) TDMA transmits each signal with sufficient guard time between time slots.

f

t

c

k2 k3 k4 k5 k6k1

Time multiplexTime multiplex A channel gets the whole spectrum for a certain amount of time Advantages:

only one carrier in themedium at any time

throughput high even for many users

Disadvantages: precise

synchronization necessary

f

Time and Frequency MultiplexTime and Frequency Multiplex

Combination of both methods A channel gets a certain frequency band for a certain

amount of time

t

c

k2 k3 k4 k5 k6k1

f

Time and Frequency MultiplexTime and Frequency Multiplex Example: GSM Advantages:

Better protection against tapping

Protection against frequency selective interference

Higher data rates compared tocode multiplex

But: precise coordinationrequired

t

c

k2 k3 k4 k5 k6k1

Various Access MethodVarious Access Method

153

CellsCells

The coverage area is divided into hexagonal cells A BTS is situated at three of the vertices of each cell In USA, the spectrum in each cell is divided into two bands: A-band

and B-band, each 25 MHz Each 25 MHz band is divided into 832 30 kHz channels Two channels separated by 45 MHz

forms a full-duplex channel The number of channels used in a cell

varies from as low as 4 to as many as 80

Cell Site

CellsCells

Representation of CellsRepresentation of Cells

Ideal cells Fictitious cells

Cell size and capacityCell size and capacity

Cell size determines number of cells available to cover geographic area and (with frequency reuse) the total capacity available to all users

Capacity within cell limited by available bandwidth and operational requirements

Each network operator has to size cells to handle expected traffic demand

Cell structureCell structure

Implements space division multiplex: base station covers a certain transmission area (cell)

Mobile stations communicate only via the base station Advantages of cell structures:

higher capacity, higher number of users less transmission power needed more robust, decentralized base station deals with interference, transmission area etc. locally

Problems: fixed network needed for the base stations handover (changing from one cell to another) necessary interference with other cells

Cell sizes from some 100 m in cities to, e.g., 35 km on the country side (GSM) - even less for higher frequencies

Speech Coding• GSM transmits using digital modulation - speech must be

converted to binary digits. Coder and decoder must work to

the same standard Simplest coding scheme is Pulse Code

Modulation (PCM)

• Sampling every 125 μs

• Requires data rate of 64 kbps

Frequency ReuseFrequency Reuse

The spectrum allocated for a cellular network is limited. As a result there is a limit to the number of channels or frequencies that can be used. For this reason each frequency is used simultaneously by multiple base-mobile pairs. This frequency reuse allows a much higher subscriber density per MHz of spectrum than other system. System capacity can be further increased by reducing the cell size down to radii as small as 200m

7 cell re-use pattern

f7

f7

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f6

f1

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f4

f1

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Frequency Reuse

162

“4 3” reuse mode: one group includes 3 sectors /site ,12 frequency which are

distributed to 4 sites. Every site owns 3 frequency.

Frequency Reuse

A3

D2B1

C3

B2D1

D3

A2C1

B3

C2A1

B3

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C1

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A2C1

D3

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A3

C2B1

B3

A2C1

C3

B2A1

A3

C2B1

B3

A2C1

B3

A1C1

A1

A3A2

C3

B2A1

A3A3

C3

C1

B2A1B2A1

A2C1

B3

Frequency Reuse

“3 3” reuse mode: one group includes 3 sectors /site ,9 frequency which are

distributed to 3 sites. Every site owns 3 frequency.

Frequency ReuseFrequency Reuse

GSM ArchitectureGSM Architecture

2G Architecture2G Architecture

2G mobile system has two major components: Fixed installed network Mobile subscribers


Fixed installed network has three sub networks:

Radio network Transmission network Mobile switching network, Plus

Three Management subsystems

2G Architecture2G ArchitectureComponents in a 2G GSM Network

MS: Mobile SubscriberBSS: Base Station SubsystemBS: Transmit/Receiver Cell TowerBTS: Base Transceiver StationBSC: Base Station ControllerMSC: Mobile Switching CentreHLR: Home Location RegisterVLR: Visitor Location RegisterGMSC: Dedicated Gateway MSCEIR: Equipment Identify Register (optional)

BS BSS

GMSC


Components in a 2G GSM Network


Fixed installed network has three subsystems: Base Station Subsystems (BSS) Switching and Management Subsystem (SMSS) Operation and Management Subsystem (OMSS)


Base Station Subsystems (BSS) Main tasks include:

Frequency administration Control of Base Transceiver Station Exchange functions


Base Station Subsystems (BSS) Base Station Controller (BSC) Base Transceiver Station (BTS) Base Station (BS)

Mostly combined BTS/BS


Base Station Subsystems (BSS) BTS usually located in centre of a cell

Provides radio channels for signalling and user traffic BS has between 1 to 16 BTS

Each with a separate radio frequency channel


Base Station Subsystems (BSS) Can be located

At the same site as the BTS Standalone, or At the site of the Mobile Switching Centre (MSC)


Mobile Switching Network Mobile Switching Subsystem (MSS) consists of

Mobile Switching Centres (MSC) Databases Store data required for routing Store data pertaining to service provisioning


Mobile Switching Centre (MSC) Performs same function as a Fixed Network

Switching Centre: Routing path search Signal routing


Dedicated Gateway MSC (GMSC) Passes voice traffic between fixed and mobile

networks If the fixed network is unable to connect an incoming call

to the local MSC it routes the call to the GMSC GMSC request routing information from the Home

Location Register (HLR) Connections to international mobile networks are routed

via the International Switching Centre (ISC)

2G Architecture2G ArchitectureHome and Visitor Location Registers (HLR and VLR) Synchronization of registration of subscribers and

their current location: Within the home network, subscriber is registered at the

HLR Outside his home network, subscriber is registered at the

VLR of the network he is currently in

179

Cellular ArchitectureCellular Architecture

Mobile Station

Base Station Subsystem

Network Subsystem

BTS

BSC

UmMSC

AbisABSC

HLR

VLR

EIR

AuC

PSTN

180

MSC/VLR

HLR/AUC EIR SC/VM

OMC

BSC

BTSPSTNISDN

PSPDN

MS

BSS

MSS

Um

Abis

BIEA

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C

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E

GSM Network Structure

182

Equipment used by mobile service subscribers for access to services.

Mobile Station ( MS )

Mobile EquipmentSubscriber Identity Module (SIM)

Mobile stations are not fixed to one subscriber. A subscriber is identified with the SIM card.

GSM Network Entity

Mobile StationMobile Station

MOBILE STATION (MS) :- The mobile station (MS) represents the

terminal equipment used by the wireless subscriber supported by the GSM Wireless system.

The SIM may be a removable module, while the equipment identity is not linked to a particular subscriber.

Functions of a Mobile Station :- Radio transmission termination. Radio Channel Management. Speech Encoding/Decoding Radio Link error Protection. Flow control of data. Mobility Management.

184

Base Transceiver Station (BTS)

Wireless transmissionWireless diversityWireless channel encryptionConversion between wired and wireless signalsFrequency Hopping

BaseBand Unit: voice and data speed adapting and channel codingRF Unit: modulating/demodulating, transmitter and receiverCommon Control Unit: BTS operation and maintenance

GSM Network Entity

Base Transceiver Station ( BTS )

185

Managing Wireless network-BSSMonitoring BTS

Controls:Wireless link distribution between MS and BTSCommunication connection and disconnectionMS location, handover and pagingVoice encoding, transecoding (TC), rate,

adaptation, The operation and maintenance functions of BSS.

Base Station Controller ( BSC )

GSM Network Entity

186

holds all the switching functions

manages the necessary radio resources,

updating the location registration

carrying out the inter-BSC and inter-MSC tender

Inter-working with other networks (IWF).

GSM Network Entity

Mobile Service Switching Center ( MSC )

187

Manages the mobile subscribers database

subscriber information

part of the mobile location information

3 identities essentialthe International Mobile subscriber Identity

the Mobile station ISDN Numberthe VLR address

GSM Network Entity

Home Location Register ( HLR )

Each PLMN Should have at least one HLR

188

Visitor Location Register ( VLR )Dynamically stores subscriber information needed to handle incoming/outgoing calls Mobile Station Roaming NumberWhen a roaming mobile enters an MSC area. This MSC warns the associated VLR of this situation; the mobile enters a registration procedure through which it is assigned a mobile subscriber roaming number (MSRN)

Temporary Mobile Subscriber Identity, if applicableThe location area in which the mobile has been registeredData related to supplementary service parametersCopy of the subscriber data from the HLR.One VLR is connected to several MSC ,but one MSC has one VLR

GSM Network Entity

The Network Switching System This consists of the Mobile services Switching Centre (MSC)

and its associated system-control databases and processors together with the required interfaces. This is the part which provides for interconnection between the GSM network and the Public Switched Telephone Network (PSTN).

The Operations and Maintenance System This enables the network provider to configure and maintain

the network from a central location.The Operation and maintenance Center (OMC) is the centralized maintenance and diagnostic heart of the base station system (BSS). It allows the network provider to operate, administer , and monitor the functioning of the BSS.

191

AUC

Authentication Center(s) (AUC)

Providing the authentication key used for authorizing the subscriber access to the associated GSM PLMN.

Contains subscriber authentication data called authentication key (Ki)

Generates security related parameters needed to authorize service using Ki.

Generates unique data pattern called a cipher key (Kc) needed for encrypting user speech and data.

GSM Network Entity

The Equipment Identity Register (EIR) is accessed during the equipment validation procedure when a mobile station accesses the system .It contains the identity of mobile station equipment which may be valid, suspect, or known to be fraudulent.This contains : White or Valid list – list of valid MS equipment identities.Grey or Monitored list – list of suspected mobiles under observation.Black or prohibited list – list of mobiles for which service is barred

Equipment Identity Register(s) (EIR)

Handling Mobile Station Equipment Identity

EIR

BASE STATION SYSTEM (BSS) :- (BSC+BTS) Characteristics of the Base Station System (BSS) are : The BSS is responsible for communicating with mobile stations in cell

areas. One BSC controls one or more BTS’s and can perform inter-BTS and

intra-BTS handover.

BASE STATION SYSTEM (BSS) :- (BSC+BTS)BASE STATION SYSTEM (BSS) :- (BSC+BTS)

The BSS consists of three major hardware components:

1) The Base Transceiver Station – BTS

The BTS contains the RF components that provide the air interface for a particular cell .This is the part of the GSM network which communicates with the MS. The antenna is included as part of the BTS.

2) The Base Station Controller – BSC

The BSC as its name implies provides the control for the BSS. The BSCcommunicates directly with the MSC. The BSC may control single or multipleBTSs.

3) The Transcoder – XCDR

The Transcoder (XCDR) is required to convert the speech or data output from the MSC(64 kbit/s PCM), into the form specified by GSM specifications for transmission over theair interface, that is, between the BSS and MS (64 kbit/s to 16 kbit/s and vice versa)

Characteristics of the Base Station System (BSS) are :

The BSS is responsible for communicating with mobile stations in cell areas.

One BSC controls one or more BTS’s and can perform inter-BTS and intra-BTS

handover.

196

ServicesServices SMS (Short Message Service)

http://www.gsmworld.com/technology/sms/intro.shtml Facsimile (for receiving fax on a mobile station) WAP (Wireless Application Protocol) – a standard to let

wireless equipment access the Internet. A Wireless Markup Language (WML) is used to encode the pages instead of HTML.

MMS (Multimedia Message Service) EDGE (Enhanced Data rates for GSM evolution) The ever elusive “Killer app”

2.5G: GPRS(General Packet Radio Service)

GPRS and EDGEGPRS and EDGE GPRS – General Packet Radio Services

2.5G protocol Involved only software changes to the GSM network. Used under utilized TDMA channels more effectively. Increased data rates to a max of 170 Kbps.

EDGE – Enhanced Data rates for GSM Evolution. 2.75G protocol. Required minimal hardware changes Added a new encoding scheme that allowed for more bits

to be added into each time slice. Data can now be passed optimally at 384 Kbps.

Both of these use TDMA over GSM

GPRSGPRS

Limitations of 2G networks: Low data transfer rates:

2G GSM networks primarily for voice services Voice only requires low transfer rates

Low efficiency for packet switched services: Cannot satisfy demand for Internet access, especially

when roaming Wireless Internet access over 2G GSM network is not

efficiently implemented Multiple Standards:

Due to multiple Standards between different networks, 2G network technology is semi-global

GPRSGPRS

Data traffic on 2G networks demanded by users Required a more efficient method of dealing with

non-voice traffic Essentially separation of voice from non-voice

traffic GPRS is a non-voice, data value added service on

an existing circuit switched GSM network

GPRSGPRS

That means: On an existing 2G GSM network, operator just

adds a few nodes and a few software changes Thereby upgrades the existing voice GSM system

to voice plus data on GPRS Voice traffic is circuit-switched Data traffic is packet switched

Packet switching uses network resources only when

GPRSGPRS

That means: Packet switching uses network resources only

when subscriber is actually sending and receiving data

Voice traffic requires continuous assignment of resources regardless of whether subscriber is talking or not

GPRSGPRS

Voice

Data

Basics of GPRS GSM was capable of providing a data rate of 9.6 kbps on a single time

slot. With the advent of high-speed circuit-switched data (HSCSD), the

capability of the network was increased multi-fold, to 115.2 kbps. In practice, however, it was only 64 kbps owing to the limitation of the

A-interface and the core network. The main benefit of the implementation of HSCSD was that, with limited

upgrading (i.e. minimum investment), the capacity for data transfer was increased to up to four TS on the receiving side and two TS on the transmitting side.

2.5G GPRS Network Planning2.5G GPRS Network Planning

Basics of GPRS But the traffic was still circuit-switched, which meant a long access time

to the network. As charging is proportional to the logging time, the subscriber ends up

paying more. This led to the application of packet-switched technology in the network. In this technology, the access time to the network is reduced and

charging is done solely on the usage of the network; i.e. even when a connection is there but not being used, the subscriber is not charged.


Basics of GPRS Usage of the network resources becomes more dynamic and

efficient. They are no longer reserved for a user logged to the network,

even when he is not using the resources. This system is known as a general radio packet system (GPRS).


Basics of GPRS GPRS is an addition to the existing GSM system, enabling packet-

switched transmission in the network whilst keeping the existing value-added services like SMS, etc.

Because of this, data rates increase substantially: the user now can log into the GPRS network, and can make use of all

eight TS dynamically and be charged only when using the resources. The packet data can be sent during idle times also, between speech

calls, thus making effective use of the network resources and saving money for the subscriber


Basics of GPRS GPRS technology is an addition to the existing GSM technology. Because of the introduction of packet switching, the new network

elements are those capable of performing packet switching. The main ones are the Serving GPRS Support Node (SGSN) and the

Gateway GPRS Support Node (GGSN). The GSM system is orientated towards providing a voice service. So, apart from the addition of new elements such as SGSN and GGSN,

there are only minor changes required in the GSM network elements in the BSS and HLR.

These are both hardware- and software related changes and are due to the higher-level coding schemes that are being used in the GPRS technology.


Basics of GPRS The most important change is the addition of a PCD (packet

control unit) at the base station controller. The GPRS system with all these elements looks the same as

the GSM except for the addition of the packet-handling core part, as shown in the following slide.

As all the network elements of the GSM have been explained in the Module on GSM, here only the new elements will be discussed.

But first let us look at the changes in the mobile station.


Basics of GPRS


GPRS Mobile Station The fundamental difference between a GSM mobile and

GPRS mobile is that the GPRS mobile is able to handle the packet data at a higher speed.

GPRS mobile stations have been classified into three classes, A, B and C, based on their ability to handle cellular networks.

Class A mobiles are connected to both the GSM and GPRS networks and can use them simultaneously.

Class B mobiles are connected to both the networks, but they can use only one at a time.

Class C mobiles can only connect to either one of the networks.


GPRS Mobile Station


Serving GPRS Support Node (SGSN) SGSN is the most important element in a GPRS network. It is the service access point for the mobile station. Its main functions include mobility management and registration and

authentication. It also interacts with a mobile with packet data flow and functions

related to it like compression and ciphering. These are handled by protocols such as

SNDCP (sub-network dependent convergence protocol) LLC (logical link control) and GTP (gate tunnelling protocol) tunnelling to the other support nodes.


Gateway GPRS Support Node (GGSN) The GGSN is connected to the SGSN on the network side and to the

outside world external networks such as the Internet and X.25. As it is a gateway to the external networks, its main function is to act as

a 'wall' for these external networks in order to protect the GPRS network.

When data come from the external network, after verification of the address, the data are forwarded to the SGSN.

If the address is found to be invalid, the data are discarded. On the other hand, the SGSN also routes the packets it receives from the

mobile to the correct network. Thus, for the outside networks, the SGSN acts as a router.


Border Gateway (BG) The border gateway interconnects different GPRS

operators' backbones, thereby facilitating the roaming feature.

It is based on the standard IP router technology.


Legal Interception Gateway (LlG) The LIG performs 'legal' functions in the network. Subscriber data and signalling can be intercepted by

using this gateway, thus enabling the authorities to track criminal activities.

LIG is required when launching a GPRS service.


Domain Name System (DNS) DNS does the translation of IP host names to IP

addresses, thereby making IP network configuration easier.

In the GPRS backbone, SGSN uses DNS to get GGSN and SGSN IP addresses.


Packet Control Unit (PCU) This is a new card that is inserted in the BSC to manage the

GPRS traffic. The PCU has limitations in terms of the number of transceivers

and base stations it can manage, thereby creating a bottleneck for the network design usually in terms of capacity.

Increasing the capacity of the network leads to an increase in PCU capacity, thereby increasing the hardware costs of the network.


2.5G: EDGE(Enhanced Data Rate for GSM

Evolution)

EDGEEDGE

EDGE works on TDMA and GSM networks Is an enhancement of GPRS Does not require additional network equipment Requires hardware upgrades in BTS, and Software upgrades in network

EDGEEDGE

EDGE achieves data rates up to 500Kbps Using different modulation scheme:

8-PSK (Phase Shift Keying) Provides capabilities similar to 3G on 2.5G

networks Is suitable for national roaming, however, Limitations of 2.5G global roaming capabilities and

other limitations led to introduction of 3G

Basics of EDGE Networks GPRS networks are able to handle higher bit rates than

GSM networks, but the data rates still fall short of what is required to make existing GSM networks deliver services at a speed comparable to that promised by third-generation networks.

The delay in the deployment of third-generation systems led to the emergence of a technology known as EDGE.

This was capable of delivering services similar to those of third-generation networks, yet with implementation on the existing second-generation networks (e.g. GSM).

2.5G EDGE Network Planning2.5G EDGE Network Planning

Basics of EDGE Networks EDGE stands for 'enhanced data rates for GSM evolution'. The enhancement from GSM was to GPRS (i.e. voice and

packet, while further enhancement of GPRS led to EDGE networks.

The fundamental concept remains the same, i.e. voice, CS data and PS data being carried, and the network architecture is the same as in a GPRS network.


Basics of EDGE Networks In ECSD, though user data rates do not go beyond 64 kbps,

fewer time slots are required to achieve this compared to HSCSD.

The architecture of ECSD is based on HSCSD transmission and signalling, thus having minimal impact on existing specifications.


Basics of EDGE Networks


The EDGE System EDGE system is quite similar to the GPRS system, but with the capability

for higher data rates. The most important change is the new modulation scheme. In GSM and GPRS, the GMSK modulation scheme was used. In GMSK

modulation, only one bit per symbol is used. In an EDGE network, octagonal phase-shift keying (8-PSK) modulation is

used which enables a threefold higher gross data rate of 59.2 kbps per radio time slot by transmitting three bits per symbol.

GMSK is a constant-amplitude modulation while 8-PSK has variations in the amplitude.

This amplitude variation changes the radio performance characteristics, so hardware changes in the base stations are mandatory.


The EDGE System


Third Generation (3G) Systems

Broadband for Fixed Mobile Convergence

230


231

IS-41, also known as ANSI-41, is a mobile, cellular telecommunications system

standard to support mobility management by enabling the networking of switches.

IMEI – International Mobile Equipment Identity

Cellular GenerationsCellular Generations

First Analog, circuit-switched (AMPS)

Second Digital, circuit-switched (GSM, D-AMPS) 10 Kbps

Advanced second Digital, circuit switched, Internet-enabled (WAP)

10 Kbps

2.5 Digital, packet-switched, TDMA (GPRS, EDGE)

40-400 Kbps Third

Digital, packet-switched, wideband CDMA (UMTS, cdmaX)0.4 – 2 Mbps

Fourth Data rate 100 Mbps; achieves “telepresence”

What is 3G?What is 3G?

Any standard that provided mobile users with the performance of ISDN or better (144kbps). Some 2.5G standards, such as GPRS and IS-95b might be able to do this, but only under optimal conditions.

Where does the extra capacity come from? • Extra spectrum • New modulation techniques - They tend to be based on CDMA rather than TDMA, because of its ability to add more users without reconfiguration.

Planned 3G Data RatesPlanned 3G Data Rates

144 kbps was the absolute minimum. Same as B-rate ISDN, which makes up a large proportion of ordinary telephone wires throughout Europe, especially Germany.

384 kpbs was the ideal capacity. It corresponds to H-rate ISDN, and often used for video-conferencing.

2 Mbps was the capacity that should be achievable inside a building. It corresponds to a European P-rate ISDN line, which is usually a fiber-optic, carrying 30 phone lines - parallel to NA's T1.

3G3G

3rd Generation Network was developed to: Offer high speed data

Somewhere between 144Kbps to >2Gbps Offer multimedia connectivity to mobile

subscribers IMT-2000 Standard developed (International

Mobile Telecommunications Standard developed by ITU (International Telecommunications Union)

3G3G

Three technologies are able to fulfill the requirements of IMT 2000:

CDMA2000 (Code Division Multiplex Access) UMTS (Universal Mobile Telecommunications

System EDGE for 3G

3G – CDMA20003G – CDMA2000

CDMA2000 Variants: 1X 1XEV-DO 1XEV-DV 3X

1XEV specification developed by 3GPP2 (Third Generation Partnership Project 2) Also known as High Rate Packet Data Air Interface

Specification Uses 5MHz spectrum to achieve 2 to 4Mbps

3G - UMTS3G - UMTS

UMTS uses W-CDMA (Wideband CDMA) W-CDMA succeeds GSM (2G) W-CDMA is air interface, while UMTS is complete stack of communications

protocol UMTS uses two 5MHz channels per connection

1885 – 2025 MHz channels uplink 2110 – 2200 MHz channels downlink

3G - UMTS3G - UMTS

UMTS Network Architecture Three interacting domains:

Core Network (CN) UMTS Terrestrial Radio Access Network (UTRAN) User Equipment (UE)

3G - UMTS3G - UMTS

Third-generation UMTS (universal terrestrial mobile system) networks have a predominance of data traffic, unlike GSM networks.

The rate at which this data traffic can move will be significantly higher than that offered by GSM/GPRS/EDGE networks.

For this reason, the third-generation UMTS networks are fundamentally different from the existing GSM systems.

IMT-2000IMT-2000

• 3G systems first planned in 1992, when the ITU (International Telecommunications Union) realized that mobile communications was playing an increasingly important role. • The project was called IMT-2000 (International Mobile Telecommunications). The '2000' had three meanings:

- Year 2000, when the ITU hoped the system would become available- Data rates of 2000kbps (2M)- Frequencies in the 2000MHz range, which ITU wanted to make a global standard.

• None of these goals were realized. - 1999 prototypes were the size of a truck- The data rate is possible, but only under optimal conditions.

• Most importantly, in terms of global standards, not every country has agreed to the requested frequencies. Europe and Asian countries have, but the US has made no spectrum available at all for IMT-2000.


3G networks serve a different purpose to earlier networks, and major changes from previous network types are:

maximum user bit rates up to 384 kbps efficient handover between different operators and

technologies (e.g. GSM and UMTS) an ability to deliver requested bandwidth an ability to deliver different services (both CS and PS)

with the required quality.

3G Service Classes3G Service Classes

Voice Still 'killer app'. Voicemail - eventually integrated fully with email through computerized voice recognition.

MessagingExtension of pagingCombined with Internet email. Will allow attachmentsCan also be used for payment and electronic ticketing

Switched DataTo allow compatibility with legacy equipment.Such as dial-up connections and fax

3G Service Classes – contd….3G Service Classes – contd….

Medium Multimedia - High downstream data rate for Web surfingCollaborationGamesLocation-based maps

High Multimedia Very high-speed Internet accessHigh-definition video CD-quality audio on demand

Interactive High MultimediaFairly high quality videoconferencing or videophonesBeing called 'telepresence'.

Data Rates for ServicesData Rates for Services

Upgrading to 3GUpgrading to 3GSingle Global Standard not possibleChoices...

Two main types of CDMA, and a third based on TDMA

The main reason for the dispute is whether or not to maintain compatibility with existing systems

Existing operators need to deploy an improvement on their existing system to avoid loss of income. They can...

Add packet-switching capabilitiesImproved modulation techniquesKeep existing cell sizes and channel structure.

This ‘gradual route’ limits their options: in particular 2G systems are based on TDMA, so direct upgrades must be TDMA compatible

Upgrading to 3GUpgrading to 3G

Figure 5.1 goes here

What are the Choices?What are the Choices?W-CDMA

Wideband CDMA

TD-CDMA Time Division W-CDMA

UMTS Universal Mobile Telecommunications System

CDMA2000 Upgrade from cdmaOne

EDGE Enhanced Data Rates for GSM Evolution

W-CDMAW-CDMA

Wideband CDMA - the system favored by most operators able to obtain new spectrum. - designed to allow handovers to GSM- but GSM networks cannot be upgraded to W-CDMA, though the GPRS backbone can be reused

It uses a 5MHz channel bandwidth- 25x greater than GSM's 200kHz- will allow higher data rates in low usage periods. Chipping code size varies from 4 to 128 bits, so user bandwidth can vary depending on signal strength.

Allows up to about 4Mbps per channel, exceeding IMT-2000 requirements.

UMTSUMTS

Universal Mobile Telecommunications System

• The European planned W-CDMA standard to replace GSM• UMTS Forum - industry and government group formed (1996)• Before Europe could move on the UMTS proposals (bureaucratic problems), Japan

picked it up - NTT DoCoMo and J-Phone • Both trials (Europe and Japan) began in 2000 and hope to be commercial by 2002.

DoCoMo defined three ambitious applications8kbps Voice64kbps video384kbps ‘Intelligent Transport System’

Japan's system ultimately eclipsed the European development, and when the British Government was auctioning its 3G spectrum, it even went so far as to break Europen Union rules by telling its licensees to base their services on W-CDMA rather than UMTS.

EDGEEDGE

Enhanced Data Rates for GSM Evolution

• The only 3G system that is based on TDMA rather than CDMA. • Intended to be the upgrade to GSM - Compatible with UMTS, since UMTS can hand over calls to GSM• Not designed to be a competitor for CDMA-based 3G technologies. was intended as a stopgap until UMTS was out.• But.. EDGE was adopted by the UWCC (Universal Wireless Communications Consortium), a group representing the American TDMA industry. Working with the GSM Association, they developed a way to migrate D-AMPS to EDGE.

Is GSM the Future System?Is GSM the Future System?

GSM is the most likely candidate for 2G worldwide adoption as an ultimate “universal” cellular technology standard• GPRS/EDGE is most easily co-supported in the same base system with GSM• EDGE Compact strategy, if carried out, will migrate GSM technology into the North American 800 MHz band, as well as other GSM radio bands elsewhere• 3G technology, theoretically able to provide up to 2 Mbit/s, may prove to be too costly to be popular.

– 3G allows you to view a movie like “Gone With the Wind” on your handset or mobile PC, or download a large data base.– GPRS/EDGE allows you to see a complicated web page with no perceptible delay on your handset or mobile PC.– GPRS/EDGE is likely to be more cost effective for users needing higher bit rates up to ~384 kbit/s

From GSM to UMTSFrom GSM to UMTS

UMTS = UniversalMobile TelecommSystem

EDGE = Enhanced Data Rates for GSM Evolution

GPRS = General Packet Radio System

HSCSD = High Speed Circuit Switched Data

UMTS = UniversalMobile TelecommSystem

EDGE = Enhanced Data Rates for GSM Evolution

GPRS = General Packet Radio System

HSCSD = High Speed Circuit Switched Data

SOURCE: HPY

1999 2000 2001 2002 2003

HSCSD

GPRS

EDGE

UMTS

64

170

384

2000

kbit/s

43.2

CIRCUITSW ITCHED

PACKETSW ITCHED

BUILT ON TOPOF GSM

VoIP

WCDMA

TECHNOLOGY

GMSK

GMSK

8 PSK

3G3G

Third Generation of mobile phones Standard that supports data transfer greater than 2

Mbps.• IEEE 802.11 is not a 3G standard

Wide area cellular networks that support data-intensive applications.

Not just an improvement of 2G networks.• Requires new equipment and new frequency bandwidths.

UMTSUMTS

UMTS – Universal Mobile Telephone System Most popular 3G wireless standard. Combines the infrastructure of the GSM network with

superior technology of the CDMA air interface UMTS was originally a European standard.

Widely adopted in Japan• Approx. complete deployment by the end of 2006.

3G - UMTS3G - UMTS

Uses W-CDMA 5 MHz of bandwidth for each channel. Several thousand users can be supported on each cell

site. Offers 11 Mbps download speeds in theory.

Uplink speeds are much slower• Meaning, that you wouldn’t want your cell phone to be a web

server. Speeds for moving devices are also slower. Most users are finding download throughput of about

384 Kbps.• However, this is still much faster than the 14.4 Kbps optimally

that GSM offered.

Evolution from GSM/CDMA to UMTSEvolution from GSM/CDMA to UMTS

There are several nice steps from GSM to UMTS, with the wide rollout of GPRS and EDGE.

However, to convert to UMTS, the network needs to be reengineered from the ground up. Actually uses the lower 3 layers of the OSI model.

Why EvolveWhy Evolve

Killer App – Video Telephony Never realized.

What people do use (at least in Japan): MP3 downloads.

Potential good applications: TV on a cellphone.

Other ApplicationsOther Applications

Computer / PDA replacement Blackberry

Pager replacement Videoconferencing Newspaper Diary

MySpace Credit Card replacement.

Heightened security?

UMTS ProblemsUMTS Problems

Web wasn’t designed for a 2 inch by 3 inch screen. Inputting information is much more difficult.

• Voice recognition would help.

Overweight handsets with poor battery life. Poor coverage in the US. To support full motion video on demand, base

stations will need to setup every .5 miles, which isn’t feasible in rural areas. Because it is so data intensive.

3G Network Architecture

3G3G

3rd Generation Network was developed to: Offer high speed data

Somewhere between 144Kbps to >2Gbps Offer multimedia connectivity to mobile

subscribers IMT-2000 Standard developed (International

Mobile Telecommunications Standard developed by ITU (International Telecommunications Union)

3G3G

Three technologies are able to fulfill the requirements of IMT 2000:

CDMA2000 (Code Division Multiplex Access) UMTS (Universal Mobile Telecommunications

System EDGE for 3G

3G – CDMA20003G – CDMA2000

CDMA2000 Variants: 1X 1XEV-DO 1XEV-DV 3X

1XEV specification developed by 3GPP2 (Third Generation Partnership Project 2) Also known as High Rate Packet Data Air Interface

Specification Uses 5MHz spectrum to achieve 2 to 4Mbps

3G - UMTS3G - UMTS

UMTS uses W-CDMA (Wideband CDMA) W-CDMA succeeds GSM (2G) W-CDMA is air interface, while UMTS is complete stack of communications

protocol UMTS uses two 5MHz channels per connection

1885 – 2025 MHz channels uplink 2110 – 2200 MHz channels downlink

3G - UMTS3G - UMTS

UMTS Network Architecture Three interacting domains:

Core Network (CN) UMTS Terrestrial Radio Access Network (UTRAN) User Equipment (UE)

3G - UMTS3G - UMTS

Third-generation UMTS (universal terrestrial mobile system) networks have a predominance of data traffic, unlike GSM networks.

The rate at which this data traffic can move will be significantly higher than that offered by GSM/GPRS/EDGE networks.

For this reason, the third-generation UMTS networks are fundamentally different from the existing GSM systems.


3G networks serve a different purpose to earlier networks, and major changes from previous network types are:

maximum user bit rates up to 384 kbps efficient handover between different operators and

technologies (e.g. GSM and UMTS) an ability to deliver requested bandwidth an ability to deliver different services (both CS and PS)

with the required quality.


Let us try to understand some principle that would be of use in designing a network capable of giving the desired performance.

WCDMA (wide-band code-division multiple access) technology has emerged as the preferred and most adopted technology for the third-generation air interface.


Air interface technology has changed, so there are some major differences between the WCDMA and GSM air interfaces: The WCDMA system supports higher bit rates, so a large

bandwidth of 5 MHz is used as compared to 200 kHz in GSM.

Packet data scheduling in WCDMA is load-based, while in GSM/GPRS it is time-slot based.

Theoretically, only one frequency channel is used in WCDMA, while GSM uses many frequency channels.


The limited bandwidth of 5 MHz is sufficient for radio network design.

• Multipath diversity is possible with RAKE receivers, while in GSM techniques like frequency hopping are used for (frequency) diversity.

Quality control in WCDMA is done using RRM (Radio Resource Management) algorithms,

• while in GSM it was done by implementing various techniques such as frequency planning.

Users/cells/channels are separated by codes instead of time or frequency.


Service Classes In a 3G network, mobile equipment will be able to

establish and maintain multiple connections simultaneously.

The network will also allow efficient cooperation between applications with diverse quality of service (QoS) requirements, as well as adaptive applications that will function within a wide range of QoS settings.

From the users' perspective, third generation networks will be able to give high quality for many services.


Service Classes This means that all the sections of the network RAN and

CN will be trying to achieve these quality standards (from the users' perspective and defined by the ITV).

The quality can defined by two main parameters: • guaranteed and maximum bit rate (kbps) possible • permissible delays (ms).


Service Classes• Both single-media and multi-media services will be handled in the third-

generation networks. • Based on the QoS criteria, multi-media services have been further

classified as:

– conversational – streaming – interactive – background.


Conversational Service Class is for applications like speech. It is the most delay-sensitive of the four classes. A typical example of this class is video telephony, voice-

over-IP (VolP). In this class the delay is based on the human perception

of the application, hence has strict requirements for quality.


Streaming Service Class refers to traffic flow that is steady and continuous. It is server-to-user type. The most common example in this class is the Internet. In 3G networks, the Internet will be faster because a user

will be able to see data before it is completely downloaded.

There are two components of this class: • messaging and • retrieval.

A typical example is downloading of streaming videos (e.g. news).


Interactive Service Class Web browsing is a typical example of the interactive

class. In this case the user requests data from a remote entity

(e.g. a server). Location-based services are an example of this class. A user will be able to access information like

• bus and train timetables, • flight schedules, and • any local data that might be useful.


Interactive Service Class Short messages, file transfers, etc., come into the

background class. Nearly all the traffic that does not fall under the first three

categories is included, such as e-mail. This class of service has the least stringent quality of

service requirement of all the four classes.


Elements of a UMTS Network User Equipment (UE)

• The mobile terminal is called user equipment. The basic principles remain the same as GSM, but with the addition of the capability to handle data calls.

• User equipment can be divided into three parts, USIM, ME and TE, as shown below.


Elements of a UMTS Network User Equipment (UE)

• The USIM card (also known as SIM) contains authentication information and associated algorithms, encryptions and subscriber-related information.

• In contrast, the mobile equipment (ME) is user-independent. • The Terminal equipment (TE) is responsible for termination of

the entire control and user-plane bearer with the help of the ME.


Elements of a UMTS Network Base Station (BS)

• The base station is also known as 'node B' in a UMTS radio network. • It is more complex than the base station of a GSM network. • Its functions include

– handover channel management, – base-band conversion (TX and RX), – channel encoding and decoding, – interfacing to other network elements, etc.



• Amplifiers and Filters – This unit consists of signal amplifiers and antenna filters.

The amplifiers are used to amplify the signal coming from the transceiver and going towards the RF antenna (the downlink signal),

while the filters select the required frequencies coming in from the RF antenna (the uplink signal) and amplify the signals for further processing before sending them to the receiver part of the TRX.



• Transceiver – The TRX is capable of transmitting and receiving signals, by

handling uplink and downlink traffic. – It consists of one transmitter and one or more receiver.



• Modulation/Demodulation and Spreading Unit – This unit is responsible for modulating the signal in the

downlink direction and demodulating in the uplink direction. – It is responsible for summing and multiplexing the signals

and also processing the signals. – This unit contains the digital signal processors that are

responsible for coding and decoding signals.



• Network Interface Unit – This unit acts as an interface between the BS and the

transmission network or any other network element, such as co-sited cross-connect equipment.


Elements of a UMTS Network Radio Network Controller (RNC)

• is similar to the BSC in GSM/GPRS networks, but more complicated and has more interfaces to handle.

• The RNC performs radio resource and mobility management functions such as

– handovers, – admission control, – power control, – load control, etc.


Elements of a UMTS Network Radio Network Controller (RNC)

• In fact the RNC plays a dual role in a WDCMA radio network, which should be understood from a network planning perspective.

• A radio network controller can be SRNC (serving RNC) or DRNC (drifting RNC).

– From one mobile, if the RNC terminates both the data and related signalling then it is called the serving RNC.

– If the cell that is used by this UE is controlled by an RNC other than the SRNC, then it is called the DRNC (Drift RNC).

3G Architecture3G Architecture Elements of a UMTS Network

Radio Interface Protocol Architecture• Taking the OSI model as a reference the first three layers of the

WDCMA radio interface protocols are needed for the functioning (set-up, release, configuration) of the radio network bearer services.


Elements of a UMTS Network Radio Interface Protocol Architecture

• Layer 1 is the physical layer, the actual medium of transfer. • Planning engineers should note that this layer is not just a

'physical medium' but should also be able to perform certain functions.

• The main functions of layer 1 include RF processing, modulation/demodulation of the physical channels, multiplexing/demultiplexing of the physical channels, error detection and correction, rate matching, power control, synchronisation, etc.



• Layer 2 is the link layer. • It is required because of the need to allocate minimum resources for a

constantly changing data rate. • It has two main sub-layers within itself:

– RLC and – MAC.


Elements of a UMTS Network Radio Interface Protocol Architecture There are two other layers -called the 'packet-data

convergence protocol' (PDCP) and 'broadcast -multicast control' (BMC) - but they exist only in the user plane.



• The MAC (medium access control) layer in an entity that is responsible for the mapping of the logical channels to the transport channels.

• It provides data transfer services on the logical channels. • It is an interface between L1 and L3, provides functions like

multiplexing and demultiplexing of packet data units to/from the physical layer.

• The MAC layer is also responsible for measurements related to traffic volume on the logical channels and further reporting to layer 3.



• There are three modes of configuring an RLC by layer 3: – transparent mode (no protocol overhead added), – unacknowledged mode (no re-transmission protocol in used,

so data delivery is not guaranteed), and – acknowledged mode (a re-transmission protocol is used and

data delivery is guaranteed).

Introduction

3G LTE (Long-Term Evolution) - an attempt to bring 4Gtechnology into 3G spectrum

Reason: challenge other advanced technologies (like WiMAX) meeting high data rate service demands

Cellular system advantages• Wide deployment• Mobility Support

3G Evolution

Trends of Mobile Technologies

The way to LTE: 3 main 3G limitations

1. The maximum bit rates still are factor of 20 and more behind the current state of the systems like 802.11n and 802.16e/m.2. The latency of user plane traffic (UMTS: >30 ms) and of resource assignment procedures (UMTS: >100 ms) is too big to handle traffic with high bit rate variance efficiently.3. The terminal complexity for WCDMA or MC‐CDMA systems is quite high, making equipment expensive, resulting in poor performing implementations of receivers and inhibiting the implementation of other performance enhancements.

3G LTE – Targeted features

High data rates• 100 Mbps in DL (for 20 MHz band) – Efficiency 5 bps/Hz• 50 Mbps in UL (for 20 MHz band) – Efficiency 3.5 bps/Hz

Low Latency• Between terminal and Radio control device (RAN): < 10 ms• Recovery from idle mode: < 50 ms• From standby mode: < 100 ms

Mobility• 15 km/h – optimized performance• 120 km/h – high performance• 350 km/h (or 500 km/h) – establish communication

Channel Bandwidth• 1.25 MHz, 5MHz, 10 MHz, 15 MHz and 20 MHz

• LTE is the latest standard in the mobile network technologytree that previously p y realized the GSM/EDGE and UMTS/HSxPA network technologies that now account for over 85% of all mobile subscribers. LTE will ensure 3GPP’s competitive edge over other cellular technologies.• 3GPP work on the Evolution of the 3G Mobile System started in November 2004.• Specifications scheduled finalized by the end of December2009.• Currently, standardization in progress in the form of Rel‐9 and Rel‐10.

Standardization

• Need for higher data rates and greater spectral efficiency– Can be achieved with HSDPA/HSUPA– and/or new air interface defined by 3GPP LTE

• Need for Packet Switched optimized system– Evolve UMTS towards packet only system

• Need for high quality of services– Use of licensed frequencies to guarantee quality of services– Always‐on experience (reduce control plane latency significantly)– Reduce round trip delay

• Need for cheaper infrastructure−Simplify architecture reduce number of network elements

Motivation for LTE

Targets of LTE:Targets of LTE: reduced delays, in terms of both connection establishment and

transmission latency; increased user data rates; increased cell-edge bit-rate, for uniformity of service provision; reduced cost per bit, implying improved spectral efficiency; greater flexibility of spectrum usage, in both new and pre-

existing bands; simplified network architecture; seamless mobility, including between different radio-access

technologies; reasonable power consumption for the mobile terminal.

• Data Rate:– Instantaneous downlink peak data p rate of 100Mbit/s in a 20MHz downlink spectrum (i.e. 5 bit/s/Hz)– Instantaneous uplink peak data rate of 50Mbit/s in a 20MHz uplink spectrum (i.e. 2.5 bit/s/Hz)

• Cell range– 5 km ‐ optimal size– 30km sizes with reasonable performance– up to 100 km cell sizes supported with acceptable performance

• Cell capacity– up to 200 active users per cell(5 MHz) (i.e., 200 active data clients)

LTE Performance Requirements

• Mobility– Optimized for low mobility(p y(0‐15km/h) but supports high speed

• Latency– user plane < 5ms– control plane < 50 ms

• Improved spectrum efficiency• Improved broadcasting• IP‐optimized• Scalable bandwidth of 20, 15, 10, 5, 3 and 1.4MHz• Co‐existence with legacy standards

LTE Performance Requirements …..contd..

Input to LTEInput to LTE

Network operator requirements for next generation mobile systems were formulated by the Next Generation Mobile Networks (NGMN) alliance of network operators, which served as an additional reference for the development and assessment of the LTE design.

Operator-driven requirements will also guide the development of the next phase of LTE, namely LTE-Advanced.

MIMOMIMO

LTE Targets are based on Use of MIMO (Multiple Input/Multiple Output Antennae): Multiple antenna technology allows exploitation of the

spatial-domain as another new dimension. This becomes essential in the quest for higher spectral

efficiencies. With the use of multiple antennas the theoretically

achievable spectral efficiency scales linearly with the minimum of the number of transmit and receive antennas employed in suitable radio propagation environments.

MIMOMIMO

LTE Targets are based on Use of MIMO (Multiple Input/Multiple Output Antennae): Multiple antenna technology opens the door to a large

variety of features, but not all of them easily deliver their theoretical promises when it comes to implementation in practical systems.

Multiple antennas can be used in a variety of ways, mainly based on three fundamental principles

MIMOMIMO

LTE Targets are based on Use of MIMO (Multiple Input/Multiple Output Antennae): Multiple antennas can be used in a variety of ways, mainly

based on three fundamental principles: a. Diversity gain: Use of the space-diversity provided by the

multiple antennas to improve the robustness of the transmission against multipath fading.

b. Array gain: Concentration of energy in one or more given directions via precoding or beamforming. – Allows multiple users located in different directions to be served

simultaneously (so-called multi-user MIMO).

c. Spatial multiplexing gain: Transmission of multiple signal streams to a single user on multiple spatial layers created by combinations of the available antennas.

MIMOMIMO LTE Targets are based on Use of MIMO (Multiple

Input/Multiple Output Antennae): Possible Array Arrangements:

(a) diversity gain; (b) array gain; (c) spatial multiplexing gain

Radio InterfaceRadio Interface

Radio Interface in 4G is: Packet switched 3G and earlier rely on circuit switched connection-oriented

protocols on radio interface System latency is improved by reducing packet duration

from 2ms used in 3G HSDPA to 1 ms Other optimizations over 3G UMTS WCMA:

• adaptive scheduling in both the frequency and spatial dimensions; • adaptation of the MIMO configuration including the selection of

the number of spatial layers transmitted simultaneously; • link adaptation of modulation and code-rate, including the number

of transmitted codewords; • several modes of fast channel state reporting

What are the LTE challenges?

Comparison of Throughput and Latency

Scalable Bandwidth

Increased Spectral Efficiency

Reduced Network Complexity

Multiple Access Technologies

MIMO

Advanced Antenna Techniques

MIMO - Beamforming

3G Long Term Evolution

3G LTE Requirements and Targets Defined in 3GPP Very high data rates

– Peak data rates: More than 100 Mbps (downlink) / More than 50 Mbps (uplink)– Improved cell-edge user throughput

Very low latency– Less than 10 ms (User-plane RAN RTT)– Less than 50 ms (Control-plane dormant-to-active transition)

Very high spectral efficiency Spectrum flexibility

– Deployable in a wide-range of spectrum allocations of different sizes– Both paired and unpaired spectrum

Cost-effective migration from current 3G systems

3G LTE – Key Radio – access features

3G LTE – Spectrum flexibility

3G LTE Bandwidth flexibility

3G LTE – Duplex Arrangements

4G Network

Why 4G: 3G is insufficient to support latest services and

applications Video conferencing Full motion video Affordable high speed access

4G is cheaper to deploy than 3G Higher bandwidth of 100Mbps and more Greater mobility Ability to integrate with WLAN and WAN

Requirements for 4G development:

Transportation gets faster:• Trains moving at >200km/h meaning handoff needs

to be faster, 3G can’t handle thatDownloading of high capacity content:

• Videos, music, on-line gamesAll at greater QoS than 3G

4G is not a new radio interface nor a new technology, instead

4G is a convergence strategy tying together existing technologies and combines their advantages: Hiper-LAN, Bluetooth GPRS EDGE WLAN WiMAX WiFi

Performance: provides high quality video services at data speeds exceeding 100Mbps

Bandwidth: average transmission speed 20Mbps, supporting local area hot spots

Interoperability: different standards for 3G and intranets make interoperability difficult, 4G combines these standards for effortless roaming and transfer from one network to another

Technology: therefore 4G assembles existing Standards, observes them and resembles convergence rather than new technology

On a network levels, this looks like:

*“satellite based” means networks with largest coverage which tie together the smaller networks

*

4G4G

Apart from user mobiles, 4G serves terminals, networks and applications whether mobile or not

Adaptability of features between different targets (terminations) makes integration seamless

At rates which are similar or lower than existing wireless or fixed wireline rates

This spells the death knell to fixed wireline telephony as we know it

4G4G

Two types of diversity:

External diversity:• People in different situations, mobile and non-mobile terminals,

similar to diversity of the Internet today

Internal diversity:• Accommodates different interfaces, functions and modes• Interconnection of various networks and load sharing among them

Spectrum:

4G has to provide bandwidth >20Mbps and significantly increased amount of traffic

Lower bands are heavily used by existing mobile operators Proposed band is between 3GHz and 5GHz

• 3.4GHZ to 3.6GHz currently used by satellite communications,• Strongly opposed by satellite operators

Also proposed UMTS 900 (900MHz)• For GSM operators migrating their GSM networks to 4G• ITU-R and other licensing bodies strongly supportive of UMTS 900

4G4G

Spectrum: Allocation and identification of new IMT frequency bands

at the ITU World Radiocommunication Conference in 2007 (WRC-07), when 72 megahertz of frequencies in the UHF band were identified for IMT 3G mobile services

• 790-862 MHz in Region 1 (Europe, Africa), and in• 790-862 MHz in Region 3 (Asia-Pacific), and • 698-806 MHz in Region 2 (Americas) and in some countries in

Region 3, such as Japan, China, Korea and India.

Coverage (cell radius):

Coverage by base stations decreases due to higher user number and increased bandwidth

Signals are transmitted at higher bit rates to compensate for higher noise levels

Because of higher frequencies than 2G or 4G, propagation loss increases and needs to be compensated for if operating in the 3 to 5GHz range

4G4G

Three Coding Techniques:

OFDM: orthogonal frequency division multiplexing, similar to 3G

W-OFDM: Wideband OFDM on multiple high speed radio frequencies allowing for higher security, high amount of data and more efficient use of bandwidth

MC-CDMA: OFDM with a CDMA overlay; data is spread and frequency or time for higher throughput

4G4G

OFDM in 4G is E-UTRA (Evolved Universal Terrestrial Radio Access):

Uses OFDMA for the downlink (tower to handset) and Single Carrier FDMA (SC-FDMA) for the uplink Employs MIMO with up to four antennas per station. Channel coding scheme for transport blocks is turbo coding

and a contention-free quadratic permutation polynomial (QPP) turbo code internal interleaver

4G4G

OFDM in 4G is E-UTRA (Evolved Universal Terrestrial Radio Access):

OFDM has a link spectral efficiency greater than CDMA, and when combined with modulation formats such as 64QAM, and techniques such as MIMO, E-UTRA has proven to be considerably more efficient than W-CDMA with HSDPA and HSUPA

For MIMO operation, a distinction is made between • Single user MIMO, for enhancing one users data throughput, and • Multi user MIMO for enhancing the cell throughput.

4G4G Uses MIMO (Multiple Input/Multiple Output)

technology on air interface: MIMO increases link capacity by spreading data over

several multipath signals MIMO uses multiple antennae to transmit and receive

multipath signals carrying different bits of data (similar to RAKE in 3G which operates only on the receive side though)

Benefits are:• Increased capacity• Better throughput• Improved signal quality• Lower power consumption than in 3G• High data rates

4G is all IP even on the air interface

Leads to greater efficiency of network resourcesCan accommodate non-IP networks and devices

with appropriate interface devicesRequires NGN topology in the core network

4G Evolution4G Evolution

Migration path from 2G is possible, however requires more work than from 3G: 2G requires more IP interface devices than 3G 2G, or 3G network, is treated like any other network

connecting to 4G Trick is to find out whether users are interested in 4G 4G can be a small network connecting multiple lower level

networks No need to discontinue 2G or 3G operations 4G is basically 3G on steroids using higher frequency bands

Migration path from 2G is possible, however requires more work than from 3G:

Experts expect that mobile WiMAX and LTE subscriptions will represent only a miniscule portion of the total 2G/3G/4G subscriptions over the next five years.

Even in 2013, they expect that GSM/GPRS/EDGE will account for nearly 2.8 billion subscriptions, representing more than 55 percent of the total 4.8 billion 2G/3G/4G subscriptions expected in 2013

Two Competing Path:

1. Mobile WiMAX• Driven by IEEE, a US based wireless standards body

2. UMTS LTE (Long Term Evolution)• Driven by 3GPP2 (3rd Generation Partnership Project 2)

At this point in time UMTS LTE is• Preferred by 95% of cellular carriers worldwide• Looks like it will become the evolution path to 4G

Two Competing Path:

1. Mobile WiMAX• Is an evolution from fixed wireline WiMAX local access

with nomadic mobility based on 802.16e• WiMAX is currently experimenting with full mobility• Limited test networks are in operation• Would replace most of existing cellular infrastructure if

chosen as the evolution path to 4G• Intel is leading promoter of WiMAX evolution path

Two Competing Path:

Key features of Mobile WiMAX

• up to 70 Mbps download speed• up to 70 Mbps upload speed• Actual speeds of 10 Mbps achievable @ 10km from

access point

Two Competing Path:

2. UMTS LTE• Is an evolution from GSM and 3G UMTS to 4G• Compared with WiMAX has backing of 95% of

worldwide cellular carriers• Standard development is lagging WiMAX Standards• Would utilize WiMAX as local access network as it

would WiFi and other local access technologies• Major carriers are promoters of UMTS LTE evolution

Two Competing Path:

Key Features of UMTS LTE• 4 G mobile internet• up to 100 Mbps download speed• up to 50 Mbps upload speed• trials started in 2008• Will be the next UMTS standard

Mobile Service Evolution

Mobile ServicesMobile ServicesMobile service evolution:

Mobile ServicesMobile Services

Mobile Service Evolution Users don’t care about technology Want services which fulfill their needs at affordable prices Want services which are easy (intuitive) to use

Services should be provided in a sophisticated and unobtrusive manner, cheap enough for users to use them without thinking too much about the cost.*

* ITU Telecom World 2006

Mobile ServicesMobile ServicesMobile Service Evolution Cellular service evolution proceeds from basic services

(voice/data) to intelligent services (content/applications) 4G promises full convergence of all telecom infrastructures

and capabilities Capabilities will eventually surpass those of fixed wireline

infrastructure At that time full convergence of fixed wireline and wireless

networks is achieved

Questions & Answers

KEN 3189

evolution of 1g to 4g

Documents

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