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8/7/2019 good -evolution

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Linda Doyle

Centre for Telecommunications Value-Chain Research

Department of Electronic & Electrical Engineering

Trinity College, University of Dublin, Ireland

A Tour of Some Wireless and Mobile

Communication Systems

Cellular Networks

where we are

We are still focusing on taking a tour of a variety of

communication systems

We started with a look at radio We focused on digital radio and we saw that a number of

developments are taking place

We now move to mobile communications / cellular

networks.

class exercise

break into groups

sketch out what you know about any one mobile/cellular

system

some basics

Sharing

When we go on to look at 1G, 2G and 3G systems a key issue ishow the radios share the spectrum among themselves

We use the term multiple access to describe the process of

sharing

Multiple entities have access to the shared wireless medium

How each system does multiple access is not the only defining

feature of the system as we will see later. But it is a distinctive one.

1G Separate Frequencies

90 KHz

80 KHz

70 KHz

60 KHz

50 KHz

40 KHz

30 KHz

20 KHzFrequency

FDMA - Frequency Division Multiple Access


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2G

Frequency

Time

500 KHz

400 KHz

300 KHz

200 KHz

One timeslot = 0.577 ms One TDMA frame = 8 timeslots

TDMA - Time Division Multiple Access

2G & 3G

Spread spectrum modulation originally developed for the military

resists jamming and many kinds of interference

coded modulation hidden from those w/o the code

All users share same (large) block of spectrum

one for one frequency reuse

CDMA - Code Division Multiple Access

spread spectrum

Traditional radio communications focussed on the use of narrowband signals FM radio etc.

Spread spectrum works by taking a narrow band signal and usingmathematical techniques to diffuse the signal power over a largerrange of frequencies.

Both the transmitter and receiver agree on the same technique,allowing the receiver to reconstitute the narrow band signal from thediffused signal.

Looks like noise to narrow-band receivers

Co-patented by Austrian-born actress Hedy Lamarr in 1942. Billedby Hollywoods Louis B. Mayer as the as the most beautiful womanin the world, the model for Catwoman in the original Batman comics

and the first actress to appear nude on film in a German film,Extasy, in 1932

multi- access radio techniques

Courtesy of Petri Possi, UMTS World

Courtesy of Suresh Goyal & Rich Howard Courtesy of Suresh Goyal & Rich Howard


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Cellular Concept

Instead of covering the whole area with one transmitter (basestation) of high power the idea is to deploy multiple base stations ofmoderate (lower) power.

Each base station covers some specific area.

Each base station is assigneda portion of the total number ofchannels, while neighboring base stations are assigned differentgroups of channels so that the interference between base stations(and mobile users) is minimized.

Spacing the base stations systematically and allocating thechannels appropriately results in minimizing the co-channelinterference.

what is a channel?

it is whatever the unit is with which you decide to share

the medium (a frequency for 1G systems)

what is a co- channel interference?

when a basestation interferes with another basestation

that is on the same frequency but in a DIFFERENT

geographical area.

It also features rather nice footage and photos of early

mobile phone prototypes from Motorola,

that displayed many contemporary form factors such as sliders and flip-phones.

http://www.nearfield.org/2008/05/early-visualisations-of-cellular-networks

This is Marty Cooper he worked for Motorola and is considered the father of the

mobile phone.

The Motorola researcher made the first-ever wireless

call from a busy New York street corner in April 1973,


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nice article on the phone

http://www.americanheritage.com/articles/magazine/it/2007/3/2007_3_20.shtml

Mobile phones began to proliferate through the 1980s.At this

time analogue transmission was in use in all systems. Theyused FDMA.

These systems later became known as first generation mobilephones.

In September1981 the first cell phone network with automatic

roaming was started in Saudi Arabia; it was anNordic MobileTelephony (NMT) system.

One month later the Nordic countries started an NMT networkwith automatic roaming between countries

1G

2G

Second Generation 2G

digital systems

leverage technology to increase capacity Speech compression; digital signal processing

utilize/extend Intelligent Network concepts

improve fraud prevention

add new services

whole range of standards

most successful GSM (TDMA based) other US versions (CDMA based)

GSM

GSM

GSM = Global System for Mobile Communications

Originally, the acronym GSM stood forGroupe Spcial Mobile, agroup formed by the Conference of European Posts andTelegraphs (CEPT) in 1982 to research the merits of a Europeanstandard for mobile telecommunications.

GSM was taken over in 1989 by theETSI (EuropeanTelecommunications Standards Institute) and they finalized theGSM standard in 1990.

Commercial service using the GSM system did not start until 1991.

GSM cellular phones use a combination ofTime and FrequencyDivision Multiple Access.


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From GSM World

Terrestrial GSM networks now cover more than 80% of

the worlds population.

GSM satellite roaming has also extended service accessto areas where terrestrial coverage is not available.

http://www.gsmworld.com/technology/gsm/index.htm

mobile phone usage in the UK as an example

Frequencies

GSM operates in the 900MHz and 1.8GHz bands inEurope.

The and the 1.9GHz and the 850MHz band is used inthe US.

The 850MHz band is also used for GSM and 3G inAustralia, Canada and many South American countries.

By having harmonised spectrum across most of the

globe, GSMs international roaming capability allowsusers to access the same services when travellingabroad as at home.

Basic GSM

For 1G phones people were not thinking data.

GSM supports voice calls and data transferspeeds of up

to 9.6 kbit/s, together with the transmission of SMS

(Short Message Service).

SMS became a surprise killer application.

System Architecture


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The next four or five slides are from

http://www.mobilemastinfo.com/information/masts.htm

Basestations

Radio base stations are sites that enable mobile

phones to work. They can be big or small and have

transmitters and receivers in a cabin or cabinet

connected to antennas. They can be mounted on a large

mast or tower, an existing building, rooftops or street

furniture such as street lamps.

Without base stations, mobiles will not work.

At the start of 2009 there were approximately 51,300base station sites in the UK, and this figure could rise to

approximately 52,500 by the end of 2009.

Macrocells

A macrocell provides the main coverage in a mobilenetwork.

The antennas for macrocells are mounted on ground-

based masts, rooftops and other existing structures.

They must be positioned at a height that is not

obstructed by surrounding buildings and terrain.

Macrocell base stations have a typical power output of

tens of watts.

A macrocell tends to have a range from 3-35 km.


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Microcells

Microcells provide infill radio coverage and additionalcapacity where there are high numbers of users withinmacrocells.

The antennas for microcells are mounted at street level,

typically on the external walls of existing structures, lampposts and other street furniture.

The antennas are smaller than macro cell antennas and,when mounted on existing structures, often blend inwith building features to minimise visual impact.

Typically, microcells provide radio coverage acrosssmaller distances and are placed 300m-1000m apart.

They have lower outputs than macrocells, usually a fewwatts.

Picocells

A picocell provides more localised coverage than a

microcell.

They are normally found inside buildings where

coverage is poor or where there are a high number of

users, such as airport terminals, train stations or

shopping centres.

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Nothing Stands Still

GPRS

A very widely deployed wireless data service, available

now with most GSM networks

EDGE

GSM Evolution (EDGE) technology provides up to three

times the data capacity of GPRS


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GPRS

GPRS (General Packet Radio Service) is a very widelydeployed wireless data service, available now with mostGSM networks.

In other words it is a means for the GSM network to dealwith DATA.

As we all known DATA has become so important andtaken over from VOICE.

GPRS offers throughput rates of up to 40 kbit/s, so thatusers have a similar access speed to a dial-up modem,.

ntrg.cs.tcd.ie/undergrad/4ba2.01/group1/gprs2.htm

http://irshadwap.com/web/archives/7

EDGE

Further enhancements to GSM networks are provided by EnhancedData rates for GSM Evolution (EDGE) technology, which providesup to three times the data capacity of GPRS.

Using EDGE, operators can handle three times more subscribersthan GPRS, triple their data rate per subscriber, or add extracapacity to their voice communications.

EDGE allows the delivery of advanced mobile services such as thedownloading of video and music clips, multimedia messaging, high-speed Internet access and e-mail on the move.

Simple upgradeEDGE uses the same structure, as today's GSM networks, whichallows it to be overlaid directly onto an existing GSM network. For

many existing GSM/GPRS networks, EDGE is a simple software-upgrade.

.

GSM Operators in Ireland

Vodafone

02

Meteor

Meteor

GSM Coverage


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some points

emphasis now hugely on mobility (roaming)

all operations are using licensed spectrum very regulated

standards everywhere

very successful market

3G

where we are now

We are now in the era of 3G cellular networks

Developed by the global GSM community as its chosen

path for 3G evolution, WCDMA is the air interface for

one of the International Telecommunications Union's(ITU's) family of third-generation mobile communications

systems.

3G/WCDMA (Third Generation / Wideband CodeDivision Multiple Access) enables the continued

support of voice, text and MMS services in addition to

richer mobile multimedia services such as

In Europe we call 3G systems UMTS

UMTS offers data speeds up to 384kb/s along with voice

services.

IMT- 2000 Terrestrial Radio Interfaces

i.e. 3Gwcdma and cdma200

WCDMA is an evolution of GSM, while CDMA2000 is an evolutionof CDMA.

WCDMA uses a broader spectrum and the signalling is based onGSM. CDMA's signalling is somewhat related to TDMA signalling.

Both use Code Division to get the packets in sequence and bothoffer similar data speed and voice capabilities.

WCDMA handsets use an extended SIM, called aUSIM (UMTSSubscriber Information Module) which contains additional WCDMAinformation.


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(data /GPRS side)

(voice side)

but nothing stands still!!!!!

HSPA (high speed packet access)

HSPA is the set of technologies that defines the migration path for3G/WCDMA operators worldwide.

It includes HSDPA (High Speed Downlink Packet Access), HSUPA(High Speed Uplink Packet Access) and HSPA Evolved.

In most HSPA networks, the end-user can expect to enjoy speeds ofat least 1Mbps upwards, depending upon the peak speed of thenetwork (anywhere from 1.8Mbps to 14.4 Mbps) with peak uplinkspeeds of up to 5.7Mbps.

HSPA EvolvedHSPA Evolved introduces MIMO (Multiple-Input, Multiple-Output)capabilities and higher order modulation (64QAM), enabling greaterthroughput speeds and higher performance.

mimo?


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Femtocells are low-power wireless access points

that operate in licensed spectrum to connect

standard mobile devices to a mobile operatorsnetwork using residential DSL or cable broadband

connections.

http://www.femtoforum.org/femto/index.php?id=46

but nothing stands still!!!!!

LTE


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or you get these kinds of diagrams

http://www.nsma.org/Presentations2008.htm

http://www.nsma.org/Presentations2008.htm

note

we are back to OFDM again

OFDM good for high speed and large throughputs

OFDM good for multipath

OFDM dominating in the wireless world

some questions

can you follow the evolution of mobile communicationssystems?

what is a circuit switched network?

what is a packet switched network?

what contributed to the success of GSM?

do you think 3G is successful?

are you aware whether you are using 3G or not on your

phone.

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