Cellular concept part 1
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Transcript of Cellular concept part 1
Mobile Communication Systemsy
Part 1- Introduction & Principles
Professor Z GhassemlooyProfessor Z Ghassemlooy
School of Computing, Engineering and Information Sciences
School of Computing, Engineering and Information Sciences
University of NorthumbriaU.K.
University of NorthumbriaU.K.
Prof. Z. Ghssemlooy
http://soe.unn.ac.uk/ocrhttp://soe.unn.ac.uk/ocr
Reading List
- Mobile and Data Communications Systems, D Wong, D Britland, Pub: Artech Housey , g, ,- Mobile Communications, A Jagoda, M DeVillepin, Pub: J. Wiley- Mobile Information Systems, Editor: J. Walker, Pub: Artech House- Introduction to Digital Mobile Communications, Y Akaiwa, Pub: J. Wiley
Mobile Communications 2nd Ed J Schiller ISBN 0 321 12381 6- Mobile Communications, 2nd Ed, J Schiller, ISBN 0-321-12381-6 - Wireless Communications & Networks – Stallings - Mobile Communications – Dr. J. Schiller- 3G Wireless Demystified - Hartey-Introduction to Telecommunications - Anu Gokhale - Mobile Communication Systems, Parsons J D and Gardiner J G, Blackie USA Halsted Press
Mobile Communications Engineering Lee William C Y McGraw Hill Inc- Mobile Communications Engineering, Lee, William C. Y., McGraw-Hill, Inc. - Mobile Cellular Telecommunications Systems, Lee, William C. Y., McGraw-Hill, Inc.
Websites:Websites:- IEC Online Education- How Stuff works- Teracom Training Institute
Prof. Z. Ghssemlooy
g- Telecom Writing
Contents
Frequency BandHistory Part IyPrinciplesTransmission PropertiesTransmission PropertiesCellular ConceptT ffi E i iTraffic Engineering Propagation ModulationPerformance
Prof. Z. Ghssemlooy
Frequency Bandsq y
VHF (30 MH 300 MH )VHF (30 MHz - 300 MHz)
VHF Mid B d (70 87 5 MH )– VHF Mid Band (70 - 87.5 MHz)– VHF High Band (148 - 174 MHz)
UHF (300 MHz - 3 GHz)
– UHF Band (403 - 420 MHz)– UHF Band (450 - 520 MHz)UHF Band (450 520 MHz)– UHF Band 900 MHz (820 - 960 MHz) ⎫– UHF Band 1.9 GHz (1880 - 1900 MHz) ⎫
Prof. Z. Ghssemlooy
( )
Mobile Services
Private Mobile Radio (PMR) System ⎫ate ob e ad o ( ) Syste ⎫– Conventional Mobile Radio Systems
• Simple two-way radio• Fixed frequency assignment• Fixed frequency assignment• Generally no privacy
– Trunked Mobile Radio SystemsC ll l t k hit t• Cellular network architecture
• Efficient use of the frequency spectrum• Intelligent radio equipment
Cordless Telephone Systems (e.g. DECT)– Analogue Cellular Phone Systemsg y– Digital Cellular Phone Systems ⎫– Personal Communication Systems
Prof. Z. Ghssemlooy
– Mobile Data Services
Mobile Communications - Historyy
1934 AM based: 1st Generation Analogue Cellular Systems1934-USA
AM based: 1st Generation Analogue Cellular Systems- For public safety- 5000 mobiles - Vehicle ignition noise a major problem
1935 USAE
FM based: - Frequency bands:- 800 - 900 MHz and 400 - 500 MHz - 120 kHz RF bandwidth channel spacing of 30 kHzEurope
Asia- 120 kHz RF bandwidth, channel spacing of 30 kHz- Data rate 5 - 10 kbps- No of channels 400 – 1000, half-duplex
1946-USA
First Generation Public Mobile Telephone Service:- Coverage distance: 50 km, 60 kHz bandwidth
Prof. Z. Ghssemlooy
- Single powerful transmitter
History - 1st Generation (1G) Systemsy ( ) y
1960 Cellular Radio, developed by Bell Labs., p y
19 0 C ll l M bil S t (USA)1970 Cellular Mobile System (USA)
1980 First Generation Analogue Cellular Systems
- Advanced Mobile Telephone Systems (AMPS)- Advanced Mobile Telephone Systems (AMPS)- Frequency bands: 800 - 900 MHz and 400 - 500 MHz
Ch l i 30 kH d f h l 400- Channel spacing 30 kHz and no of channels 400 – 1000
- Data rate 5 - 10 kbps
Prof. Z. Ghssemlooy
p-FM for speech, FSK for signalling, FDM
History - 2nd Generation (2G) Systems (1991 4)(1991-4)
Systems:- 1991 First Group Special Mobile (GSM) network, Finland- 1992 Commercial GSM, all major European operators- 1992 Japanese Digital Cellular (JDC) system- 1993 GSM1800 system in commercial operation, UKy p ,- 1994 Commercial operation of D-AMPS (IS-54), US - U.S. Digital Cellular (USDC) and CDMA
• Technology: TDMA, TDMA hybrid FDMATechnology: TDMA, TDMA hybrid FDMA• Characteristics:
• Digital voice and low speed data• Frequency band @ 900 MHz, RF channel spacing 200 kHz• Modulation: GMSK, DPSK, Fixed frequency assignment• Speech rate 13 kbps, Speech coding, TDMA• High security and higher capacity, • Improved speech Quality of service (QoS)
1. NEC Cellstar 500 series (1992)2. Nokia 2110 series (1994)3 N ki 5120 (1998)• Improved speech Quality of service (QoS)
• GSM 1.8 GHz, and 1.9 GHzUSDC 1 9 GH
3. Nokia 5120 (1998)4. Kyocera 2135 (2002)5. Audiovox CDM8300 (2002)6. Samsung SCH-A650 (2004)
Prof. Z. Ghssemlooy
• USDC 1.9 GHz• Digital Cordless Systems (DCS) 1.8 GHz
Current - 3rd Generation (3G) Systems (1995 )(1995 - )
Support Multimedia Services:– Especially Internet Service, 144kb/s (Outdoor and higher velocity ), – 384kb/s(from outdoor to indoor) and 2Mb/s (indoor); – Speech of QoS and other services
First Transitional System: 2 GHz2000 - 2nd Transitional Systems: 2.5 GHz2001 1st CDMA Network @ 144 k bps2001 - 1st CDMA Network @ 144 k bps2002- Handover between GSM and WCDMA by Nokia and Vodafone2003 World's 1st IPv6 over 3G UMTS/WCDMA network, Ericsson ,2003 World's 1st CDMA2000 high-speed packet data phone call ( 3.09 Mbps), Nokia2004 World's 1st Enhanced Datarate for Global Evolution2004, World's 1st Enhanced Datarate for Global Evolution EDGE-WCDMA 3G packet data handover, Nokia and TeliaSonera2005, 9 Mbps with WCDMA, HSDPA phase 2, Ericsson
Prof. Z. Ghssemlooy
, p , p ,2005, 1.5 Mbps enhanced uplink WCDMA system, Ericsson
Current - 3G Systemsy
Are referred to as:Are referred to as:Universal Mobile Telecommunications System (UMTS) in Europe International Mobile Telecommunications 2000 (IMT2000) worldwide.
“UMTS will be a mobile communications system that can offer significant user benefits including high-quality wireless multimedia services to a convergent network of fixedmultimedia services to a convergent network of fixed, cellular and satellite components. It will deliver information directly to users and provide them with access to new and innovative services and applications It will offer mobileinnovative services and applications. It will offer mobile personalised communications to the mass market regardless of location, network and terminal used”.
Prof. Z. Ghssemlooy
UMTS Forum 1997
UMTS - Main Requirements (3 Ms)q ( )
Multi-media Multi-environmentM lti t Vi t l t
Multi-operator Virtual operators
Global Different environments for UMTS
Suburban Urban
Micro-Cell In- Building H C ll
Macro-Cell Pico-Cell
Home-Cell
Prof. Z. Ghssemlooy
H. Aghvami, KCL,UK
Mobile Telephony Standardsp y
A C P id Wh t’ Will P idAccess Standard
Company Provides What’s Coming
Will Provide
CDMA / TIA Verizon Voice, Data, 1XEV-DO 300-500 kbps, to 95 PTT, 1xRTT CDMA-2000 2.4 Mbps
TDMA / TIA 136
Cingular / AT&T
Voice, Data Edge 384 kbps data136 AT&T
CDMA / PCS Sprint Voice, Data 1XEV-DV to 3.1 Mbps
TDMA / iDEN Nextel Voice, Data, PTT
Spectrum change
Address public safety concern
GSM T-Mobile Voice Data GPRS W- 115 kbps dataGSM T Mobile, AT&T
Voice, Data GPRS, WCDMA, PTT
115 kbps data
Prof. Z. Ghssemlooy Source: IEEE
Technologies - Multimedia Messaging Service (MMS)Service (MMS)
It d d iIt d d iIt send and receives:–Text messages
Graphics and Photos
It send and receives:–Text messages
Graphics and Photos–Graphics and Photos–Audio, video clips–Graphics and Photos–Audio, video clips
MultimediaIt supports:
–Image: GIF, JPEG,It supports:
–Image: GIF, JPEG,
MultimediaMessaging
Service Image: GIF, JPEG, –Video: MPEG4–Audio: MP3, MIDI
Image: GIF, JPEG, –Video: MPEG4–Audio: MP3, MIDI
Service(MMS)
For high transmission speed uses:3G
For high transmission speed uses:3G
Prof. Z. Ghssemlooy
- 3G- GPRS: General Packet Radio Service- 3G- GPRS: General Packet Radio Service
Technologies - General Packet Radio Service (GPRS)Service (GPRS)
Packet based: – subs are always on line– easy and quick accessy q
Provide high speed wireless Internet and data communicationscommunicationsSpeed four times higher than conventional GSM systemssystems
Prof. Z. Ghssemlooy
Technologies - Bluetoothg
Short range RF technologyA global standardNo wiringData and voice communicationsOffers ad hoc network and synchronicity between all personal devicespersonal devices
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Mobile Computingp g
Applications
Interface Consider
ations
Communications, Connectivity and
Network Infrastructure
UsabilityIssues
Systems
Data Repositories/
Infrastructure
Persistent Storage
Prof. Z. Ghssemlooy
Systems Integration Database
Systems
Persistent Storage Media
Number of mobile phone subscribers in UKUK
http://www.mobilemastinfo.com/information/history.htm
Prof. Z. Ghssemlooy
Mobile Internet OutlookMillions1,400
Projectedcellular1,400
1,200 More handsets than PCs
cellularsubscribers(Nokia 1999)
1,000connected to the Internet by the
end of 2003 !Projected Web800
600
Projected Webhandsets(Nokia 1999)
400 Projected PCsconnected tothe Internet
200
0
the Internet(Dataquest 10/98)
Prof. Z. Ghssemlooy 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
0
Mobile Network in UK
5 network operators
45,000 base station sites. 2/3 i t ll d i ti b ildi t t2/3 are installed on existing buildings or structures.
< 2% are mounted on schools.
Additional mobile phone base stations will need to be built to support 3G services. It is possible that the number of base station sites will rise to 50,000 by
Prof. Z. Ghssemlooy
2007.
Mobile Communications - Definition
Designed to operate over a very large area with aDesigned to operate over a very large area with a limited bandwidth A cellular mobile comms system uses a large numberA cellular mobile comms. system uses a large numberof low-power wireless transmitters (100 W oe less)
Off l it th h ll littiOffers larger capacity through cell splitting Variable power levels allow cells to be sized according to subscriber density& demand within a particular region
As mobile users travel from cell to cell theirAs mobile users travel from cell to cell, their conversations are handed off between cells
Channels (frequencies) used in one cell can be reused
Prof. Z. Ghssemlooy
in another cell some distance away
Mobile Communications - Principlesp
Wave propagation mechanism is closely affected by the wavelengths of the propagating frequencyUses a separate radio channel to talk to the cell siteC ll it t lk t bil t iCell site talks to many mobiles at once, using one channel per mobile
Channels use a pair of frequencies for:• forward link for transmitting from the cell site
li k f th ll it t i ll f th• reverse link for the cell site to receive calls from the users
Radio energy dissipates over distance so mobiles mustRadio energy dissipates over distance, so mobiles must stay near the base station to maintain communicationsBasic structure of mobile networks includes telephone
Prof. Z. Ghssemlooy
psystems and radio services
Mobile Communs. - Cellular Spectrum
Phone Transmit
A band10 MHz
B band10 MHz
825 835 845824 846.5 849
A” b
A’ b
B’ b
333 channels30kHz
333 channels30kHz
band
and
and
1 MHz 1.5 MHz 2.5 MHz33 chs 50 chan 83 chs
20 MHz Guard
870 880 890869
A band B band
Base Transmit891.5 894
A A band10 MHz
333 channels30kHz
B band10 MHz
333 channels30kHz
A” band
A’ band
B’ band
Prof. Z. Ghssemlooy
1 MHz33 chan
1.5 MHz50 chs
2.5 MHz83 chs
Mobile Comms. - Systemy
• Mobile Unit• Mobile Base Station• Mobile Switching Centre
Prof. Z. Ghssemlooy
Mobile telecommunicationsswitching office (MTSO)
Mobile Comms. - Componentsp
Mobile Base Station (MBS): includesMobile Base Station (MBS): – includes – an antenna, – a controller,a controller, – a number of receivers
Mobile telecommunications switching office (MTSO)– connects calls between mobile units
Channels between mobile unit and MBSC t l h l t h i f ti l t d t tti– Control channels: to exchange information related to setting up and maintaining calls
– Traffic channels: to carry voice or data connection between yusers
Prof. Z. Ghssemlooy
MTSO Controlled Call between Mobile UsersUsers
Steps:-Steps:-Mobile unit initializationMobile originated callMobile-originated callPagingC ll t dCall acceptedOngoing callH d ff
Functions:-Handoff Call blocking
Call terminationCall droppingCalls to/from fixed and remote
Prof. Z. Ghssemlooy
mobile subscriber
Mobile Radio Environment
P ti P th LPropagation Path LossMultipath FadingFrequency-Selective FadingDoppler ShiftppCo-Channel InterferenceAdjacent Channel InterferenceAdjacent Channel InterferenceMan-Made NoiseUrban EnvironmentUrban EnvironmentSuburban EnvironmentR l E i t
Prof. Z. Ghssemlooy
Rural Environment
System Characteristicsy
Frequency sharing amongst users
M lti th i t f i tMultipath interference environment
Line-of sight coverage (UHF)
High base station antenna (30m)
Low mobile antenna (1 5m - 3m)Low mobile antenna (1.5m - 3m)
Beyond Line-of-sight (VHF)
Long distance (HF)
Prof. Z. Ghssemlooy
Early Mobile Systemsy y
Traditional mobile similar to TV broadcastingTraditional mobile similar to TV broadcasting
One very powerful transmitter y plocated at the highest spot would cover an area with a
di f t 50 kradius of up to 50 km
Cellular concept re-structured the mobile telephone network in a different way:network in a different way:
• Using low power transmitters to cover larger area. E g dividing a metropolitan region into 100 different cells
Prof. Z. Ghssemlooy
E.g. dividing a metropolitan region into 100 different cells 12 channels each
Digital Cellular- what does it offers?g
Best quality compared with analogue system
Improved bandwidth efficiencyImproved bandwidth efficiency- Reduced from 30 kHz to 10 kHz, and then to 5 kHz.
This is achieved via 3-time-slot Time Division Multiple Access (TDMA) (i.e. three pairs of people using a 30 kHz radio channel simultaneously)
Use of micro-cellular technology to accommodate smaller and smaller cells particularly around the new frequency band
f 2 GHof 2 GHz
Improved frequency reuse
Prof. Z. Ghssemlooy
Improved frequency reuse
Transmission Typesyp
f
Simplex
f1
f2
f1Tx : f1
Rx : f
f1
f2Rx : f2
Tx Rxf f
Tx : f1Rx : f2
Tx Rx
f2 f1 2
Half Duplex
Prof. Z. Ghssemlooy
Tx : f1, Rx : f1f1 f1
Transmission Types - Full Duplexyp p
f1 f3
f fTx : f1R f
Tx : f3R f
f4f3f2f1
f2 f4Rx : f2 Rx : f4
RxTx
TxRx
Prof. Z. Ghssemlooy
Transmission - Duplex Operationp p
f1 f2RxRx((ff )) Antenna
f1 f2
F((ff11))
DupDup
AntennaF1
TxTx((ff ))MM
f2((ff22))
T LoadTx LoadReception
Tx Load
Prof. Z. Ghssemlooy RxAntenna Transmission RxAntenna
Typical Wide-Area Systemyp y
DispatcherDispatcher
Di it l
Dispatcher2
DigitalSwitch
DispatcherDispatcher11
-- Dispatcher: Communicates with the vehicles.Dispatcher: Communicates with the vehicles.C i ti d H lf D lC i ti d H lf D l
Prof. Z. Ghssemlooy
-- Communication mode: Half Duplex.Communication mode: Half Duplex.-- MobileMobile--toto--mobile communication is possible using a Talkmobile communication is possible using a Talk--Through Repeater (halfThrough Repeater (half--duplex) or duplex) or direct using Simplex mode.direct using Simplex mode.
Mobile Transmission Environment
Deep Radio Shadow + Radio HorizonDeep Radio Shadow + Radio HorizonReflection, Refraction and ScatteringFadingFading– Frequency-Selective– Multipath
Propagation Path Loss (Attenuation)Doppler ShiftDelay DistortionyNoise and InterferenceUrban Suburban and Rural Environments
Prof. Z. Ghssemlooy
Urban, Suburban, and Rural Environments
Transm. Pro. - Deep Radio Shadowp
Radio waves at low frequencies can diffract (bend) around object quit• Radio waves at low frequencies can diffract (bend) around object quit well
• In mobile systems (high frequency band), wave diffraction does not take place well, therefore a deep radio shadow occurs on the un-illuminated side of the obstruction (e.g., building, hill, truck, or even human being)
shadow
human being)
shadow
T
Prof. Z. Ghssemlooy
Tx
Transm. Env. - Radio Horizon (1/2)
• Is 30% farther from the transmitting antenna than the equivalent visible horizon due to the reduction of the refraction in the upper atmosphere as compared to that
t d l lat ground level.
Beyond radio horizon the signal strength falls very rapidlyBeyond radio horizon, the signal strength falls very rapidly so that in areas well beyond the horizon the same frequency
can be reused without causing interference.g
• The higher the transmitter antenna the further away isThe higher the transmitter antenna, the further away is its radio horizon.
Prof. Z. Ghssemlooy
Transm. Env. - Radio Horizon (2/2)
The coverage area (not the radius) is approximately proportional to the antenna heights of both transmitter and receiverand receiver.
With a higher transmitter tower the far flung horizonWith a higher transmitter tower, the far flung horizon prevents close reuse of the same frequency.Between the transmitter and horizon in open flatBetween the transmitter and horizon, in open, flat country, the received power reduces approximately as the inverse fourth power of distance from the transmitter (as we see later on).
Prof. Z. Ghssemlooy
Transmission Env. – contd.
Ei
Reflection at large obstacles
i
Er= α Ei, where α is the absorption coefficient < 1
Ei
Scattering at small obstacles Er1= α Ei
E 2= α EiEr2 α EiErk= α Ei
E 1= α E
Diffraction at edges
EiEr1 α Ei
Er2= α Ei
Prof. Z. Ghssemlooy
Diffraction at edges
Transm Env – MultipathTransm. Env. – Multipath
Dispersion
signal at Tx
Dispersion
Distortion
signal at Tx
signal at receiver
Dispersion: signal is dispersed over time, thus interfering with “neighbor” symbols --> Inter Symbol InterferenceDistortion: signal reaches a receiver directly and phase shifted:- distorted signal depending on the phases of the different parts
Prof. Z. Ghssemlooy
different parts
Transm. Pro. – Multipath Fadingp g
In a multipath propagation environment signal are:In a multipath propagation environment signal are:
- Generally added to strengthen the received signal- At some point they subtract from one another, thus causing
fading, (at approximately half wavelength intervals).- The fade power level is typically 20 dB weaker than the local
average field strength. Fades that are 40 dB weaker are not uncommon.
- The combination of shadowing and multipath fading resultsin a radio field that varies wildly over a short ranges (up to 60 or 70 dB difference between the maximum and minimum t t l l l ithi 100 2)
Prof. Z. Ghssemlooy
street level value within a 100 m2).
Transm. Env. - Attenuation
• The strength (amplitude) of the signals reduces as it• The strength (amplitude) of the signals reduces as it propagate through the channel. This is called signal attenuation or loss, which is due to:,• Absorption of energy• Scattering of energy
• Limits the maximum coverage distance. • Can be overcome by in line amplification.Can be overcome by in line amplification.
High frequencies penetrates building fairly well, mostly th h d i d d thi t lli f
High frequencies penetrates building fairly well, mostly th h d i d d thi t lli fthrough doors, windows, and thin non-metallic roofs.
Typical mean building penetration losses are 10 to 20 dB, but penetration losses as high as 40 dB have been
through doors, windows, and thin non-metallic roofs. Typical mean building penetration losses are 10 to 20 dB, but penetration losses as high as 40 dB have been
Prof. Z. Ghssemlooy
dB, but penetration losses as high as 40 dB have been encountered.
dB, but penetration losses as high as 40 dB have been encountered.
Transm. Env. - Bandwidth
• All real channels have a limited bandwidthAll real channels have a limited bandwidth.
• Not all the frequency components of transmitted signal will pass through the channel.
• At the receiver, exact regeneration of the original signalAt the receiver, exact regeneration of the original signal becomes quite difficult.
• Resulting in the received signal distortion• Resulting in the received signal distortion
Prof. Z. Ghssemlooy
Transm. Pro. - Delay Distortiony
• Critical in complex waveform transmission, such as Digital Signals, where different frequency components of the same signal travel at slightly different speedssame signal travel at slightly different speeds.
• As the propagation link increases, fast components of one bit (edges) may eventually catch up the proceeding slow ( g ) y y p p gmoving components of the bit (flat top). Thus resulting in distortion.
Prof. Z. Ghssemlooy
Transm. Pro. - Noise & Interference
. Thermal noise
. Amplifier noiseRF
RF + NoiseReceiverReceiver
RF signal
. Man made noise
. Inter-modulation: noise from other transmitters at different frequencies
. Co-channel interference: noise from other transmitter at the same frequency
Prof. Z. Ghssemlooy
frequency . Electromagnetic interference in a vehicle
Mobile Phones Technology -DisadvantagesDisadvantagesAlthough the development of mobile phones brought convenient andAlthough the development of mobile phones brought convenient and
advantages to the world. But the disadvantages brought along with the fast grown technology cannot be ignored. These problems not only influenced people personally but also the society at largeonly influenced people personally but also the society at large. Symptoms caused by the radiation of mobile phones are:– headache, earaches, blurring of vision and even causing cancer
Though, these problems are still under research. Mobile phone users are advice to reduce the usage on mobile phones if it is possible. p
Mobile phone addiction. – Mobile phone addiction is becoming one of the biggest non-drug
addictions in the 21st century in particular among the teenagersaddictions in the 21st century in particular among the teenagers.– New models of mobile phones are released almost everyday. In order
to get up-to-date, people tend to change their mobile phones once in a while These became habits among the mobile phone users causing
Prof. Z. Ghssemlooy
a while. These became habits among the mobile phone users causing them to spend unnecessary cost on mobile bills and
Mobile Phone Technology - Future DevelopmentDevelopment
Mobile phones are getting more and more sophisticatedMobile phones are getting more and more sophisticated, just like computerThe technology is growing everyday with different functions and usageFrom the network system from mobile phones, it is still developingdeveloping. – The new 3G system had just been launched not long ago, – 4G system expected in 2010. It is expected that the 4G
system will be able to deliver• a much faster speed up to 100Mb per second during connection,• tighter network security • High quality during communication no matter on voice or video calls.• security system, and surveillance on certain items. The 4G system will be
expected to be launched in 2010.
Prof. Z. Ghssemlooy
Mobile Phone Technology - Future DevelopmentDevelopment
Mobile phone, the piece of communication device itself is also becoming a multi functioned device. S t h d PDA h l dSmartphones and PDA phones are already launched in the market. M bil h ith ti f ti l iMobile phone with computing functions replacing lap-tops
Prof. Z. Ghssemlooy
Summaryy
HistoryMobile technologiesPrincipleCharacteristicsTransmission properties
Prof. Z. Ghssemlooy
Next Lecture
Cellular ConceptCellular Concept
Prof. Z. Ghssemlooy