philadelphia university faculty of engineering
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Philadelphia UniversityFaculty of EngineeringCommunication and Electronics Engineering
Dr. Omar R Daoud ١
MOBILE COMMUNICATIONS (650539) Part 1
Dr. Omar R Daoud ٢
Text Book and References
T. Rappaport, “Wireless Communications: Principles and Practice”, 2nd
Edition, Prentice Hall, 2002.
W. Stalling, “Wireless Communications and Networks”, Pearson Education, 2002.
S. Haykin, “Communications Systems”, 4th
Edition, John Wiley and
Sons., 2001.
A. Yoshihiko, “Introduction to Digital Mobile Communication”, John Wiley and Sons., 1997.
L. William, “
Mobile Cellular Telecommunications: Analog and Digital Systems”, Mc Graw Hill, 1995.
Dr. Omar R Daoud ٣
Course Contents
Introduction (1 week)
Cellular Concepts, Coverage Principle and Frequency Reuse (2 weeks)
Multichannel and Cochannel Schemes (2 weeks)
Interference: Cochannel and Adjacent Channel (2 weeks)
Fading Models and Prediction of the Median Path Loss (2 weeks)
Modulation Techniques (2 weeks)
Mobile Communication Systems (2 weeks)
Private and Public Access Mobile Radio and Radio Paging (2 weeks)
Dr. Omar R Daoud ٤
Mode of Assessment
First Exam
(20%)
Second Exam (20%)
Quizzes\Reports\or Projects
(10%)
Final Exam
(50%)
Dr. Omar R Daoud ٥
Introduction
Mobile/ Wireless Systems Definitions
Why Cellular Mobile Systems?
Mobile Systems Revolutions
Dr. Omar R Daoud ٧
Mobile/ Wireless Systems Definitions
BS: Base Station; fixed station located on either the center or the edge of a coverage region. Consists of radio channels, transmitter and receivers antennas.
MS: a station which is intended for use while in motion at unspecified location.
Forward Channel/ downlink: The transmission process from BS to MS.
Reverse Channel/ uplink: The transmission process from MS to BS.
Handoff:
a process of automatically changing frequencies as the mobile unit moves into a different frequency zone. Thus, the call can be continued in a new frequency without redialing.
Full Duplex:
Transmission and reception on two different channels.
Half Duplex:
At any time the user can only transmit or receive information.
FDD: Frequency Division Duplexing; the radio transmission channels are provided simultaneously for the subscriber and the BS.
Dr. Omar R Daoud ٨
Mobile/ Wireless Systems Definitions
TDD: Time Division Duplexing; A single radio channel can be shared in time between the subscriber and the BS.
Roaming: a MS operate in a service area different than the from which service has been subscribed.
MSC: Mobile Switching Center; connects the BS and MS to the PSTN.
SSB: Single-sideband
FCC: Federal
Communications
Commission
MTS:
Mobile Telephone Service
IMTS:
Improved Mobile Telephone Service
AMPS:
Advanced Mobile Phone Service
TACS:
Total Access Communication System
NMT:
Nordic Mobile Telephone
Dr. Omar R Daoud ٩
Mobile/ Wireless Systems Definitions
GSM: Global System for Mobile Communications
PDC:
Personal Digital Cellular
HSCSD:
High Speed Circuit Switched Data
GPRS: General Packet Radio Service
EDGE:
Enhanced Data rates for Global Evolution
Dr. Omar R Daoud ١٠
Why Cellular Mobile Systems?
To Improve:* Service Capability* Service Performance * Frequency Spectrum Utilization
Dr. Omar R Daoud ١١
Why Cellular Mobile Systems?
Improving the Service Capability
In a conventional mobile telephone system: It is usually designed by selecting one or more channels from a specific frequency allocation for use in autonomous geographic zones.
Each zone is planned to be as large as possible (the transmitted power must be as high as the federal specifications allows).
The user must reinitiate the call when moving into a new zone because the call will be dropped.
The number of active users is limited to the number of channels assigned to a particular frequency zone.
Dr. Omar R Daoud ١٢
Why Cellular Mobile Systems?
Improving the Service PerformanceIn the conventional mobile telephone systems (MTS, IMTS-MJ and
IMTS-MK)
a total of 33 channels were allocated. The large number of subscribers created a high blocking probability during the busy hours. Thus a high-capacity systems were needed
Dr. Omar R Daoud ١٣
Why Cellular Mobile Systems?
Improving the Frequency Spectrum Utilization
In a conventional mobile telephone system the frequency utilization measurement is defined as the maximum number of subscribers that
could be served by one channel at the busy hour. In such systems the channel can only serve one customer at a time in a
whole area. Thus, a new cellular system must be initiated to overcome these
limitations. This systems must be:-
SSB: divides the allocated frequency band into maximum numbers of
channels-
Cellular: reuses the allocated frequency band in different geographical
locations-
Spread-spectrum or Frequency-hopped: generates many codes over a
wide frequency band
Dr. Omar R Daoud ١٤
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Cellular Mobile Telephony
Frequency modulation
Antenna diversity
Cellular concept
Bell Labs (1957 & 1960)
Frequency reuse
Typically every 7 cells
Handoff as caller moves
Modified CO switch
HLR, paging, handoffs
Sectors improve reuse
Every 3 cells possible
Dr. Omar R Daoud ١٥
Mobile Systems Revolutions
1G (AMPS, TACS and NMT): Features:-Analogue systems -FM modulations-Cellular concepts-Hard Handoff
Dr. Omar R Daoud ١٦
First Generation
Advanced Mobile Phone Service (AMPS)
US trials 1978; deployed in Japan (’79) & US (’83)
800 MHz band —
two 20 MHz bands
TIA-553
Still widely used in US and many parts of the world
Nordic Mobile Telephony (NMT)
Sweden, Norway, Demark & Finland
Launched 1981; now largely retired
450 MHz; later at 900 MHz (NMT900)
Total Access Communications System (TACS)
British design; similar to AMPS; deployed 1985
Some TACS-900 systems still in use in Europe
Dr. Omar R Daoud ١٧
Mobile Systems Revolutions
2G (GSM, IS-95, PDC):Features:-Digital Mobile phones-Digital modulation -Data compression-Error control -Soft Handoff-SMS-High quality voice-More capacity/ each cell are divided among several users.
Dr. Omar R Daoud ١٨
Second Generation — 2G
There are a wide diversity of 2G systems
IS-54/ IS-136 North American TDMA; PDC (Japan)
iDEN
DECT and PHS
IS-95 CDMA (cdmaOne)
GSM
Dr. Omar R Daoud ١٩
D-AMPS/ TDMA & PDC
Speech coded as digital bit stream
Compression plus error protection bits
Aggressive compression limits voice quality
Time division multiple access (TDMA)
3 calls per radio channel using repeating time slices
Deployed 1993 (PDC 1994)
Development through 1980s; bakeoff 1987
IS-54 / IS-136 standards in US TIA
ATT Wireless & Cingular use IS-136 today
Plan to migrate to GSM and then to W-CDMA
PDC dominant cellular system in Japan today
NTT DoCoMo has largest PDC network
Dr. Omar R Daoud ٢٠
iDEN
Used by Nextel
Motorola proprietary system
Time division multiple access technology
Based on GSM architecture
800 MHz private mobile radio (PMR) spectrum
Just below 800 MHz cellular band
Special protocol supports fast “Push-to-Talk”
Digital replacement for old PMR services
Nextel has highest APRU in US market due to “Direct Connect”
push-to-talk service
Dr. Omar R Daoud ٢١
DECT and PHS
Also based on time division multiple access
Digital European Cordless Telephony
Focus on business use, i.e. wireless PBX
Very small cells; In building propagation issues
Wide bandwidth (32 kbps channels)
High-quality voice and/or ISDN data
Personal Handiphone
Service
Similar performance (32 kbps channels)
Deployed across Japanese cities (high pop. density)
4 channel base station uses one ISDN BRI line
Base stations on top of phone booths
Legacy in Japan; new deployments in China today
Dr. Omar R Daoud ٢٢
North American CDMA (cdmaOne)
Code Division Multiple Access
All users share same frequency band
Discussed in detail later as CDMA is basis for 3G
Qualcomm demo in 1989
Claimed improved capacity & simplified planning
First deployment in Hong Kong late 1994
Major success in Korea (1M subs by 1996)
Used by Verizon
and Sprint in US
Simplest 3G migration story today
Dr. Omar R Daoud ٢٣
cdmaOne — IS-95
TIA standard IS-95 (ANSI-95) in 1993
IS-95 deployed in the 800 MHz cellular band
J-STD-08 variant deployed in 1900 MHz US “PCS”
band
Evolution fixes bugs and adds data
IS-95A provides data rates up to 14.4 kbps
IS-95B provides rates up to 64 kbps (2.5G)
Both A and B are compatible with J-STD-08
All variants designed for TIA IS-41 core networks (ANSI 41)
Dr. Omar R Daoud ٢٤
GSM
«
Groupe
Special Mobile
», later
changed
to
«
Global System for Mobile
»
Joint European effort beginning in 1982
Focus on seamless roaming across Europe
Services launched 1991
Time division multiple access (8 users per 200KHz)
900 MHz band; later extended to 1800MHz
Added 1900 MHz (US PCS bands)
GSM is dominant world standard today
Well defined interfaces; many competitors
Network effect (Metcalfe’s law) took hold in late 1990s
Tri-band GSM phone can roam the world today
Dr. Omar R Daoud ٢٥
Mobile Systems Revolutions
2.5G (HSCSD,GPRS, EDGE):Features:2.5G is an interim solution designed to allow for
improved data rates prior to 3G implementation. A variety of 2.5G techniques are being employed to improve the speed of data for enhanced e-mail and Internet access.
Dr. Omar R Daoud ٢٦
Mobile Systems Revolutions
3G (UMTS, WCDMA):Features:
-Digital multimedia handset.
High data transmission rate > 100kbps.
Providing much more basic voice call.-Dynamic RRM.-Packet data.
Dr. Omar R Daoud ٢٧
3G Vision
Universal global roaming
Multimedia (voice, data & video)
Increased data rates
384 kbps while moving
2 Mbps when stationary at specific locations
Increased capacity (more spectrally efficient)
IP architecture
Dr. Omar R Daoud ٢٨
CDMA2000 Pros and Cons
Evolution from original Qualcomm CDMA
Now known as cdmaOne
or IS-95
Better migration story from 2G to 3G
cdmaOne
operators don’t need additional spectrum
1xEVD0 promises higher data rates than UMTS, i.e. W- CDMA
Better spectral efficiency than W-CDMA(?)
Arguable (and argued!)
CDMA2000 core network less mature
cmdaOne
interfaces were vendor-specific
Hopefully CDMA2000 vendors will comply w/ 3GPP2
Dr. Omar R Daoud ٢٩
W-CDMA (UMTS)
Wideband CDMA
Standard for Universal Mobile Telephone Service (UMTS)
Committed standard for Europe and likely migration path for other GSM operators
Leverages GSM’s
dominant position
Requires substantial new spectrum
5 MHz each way (symmetric)
Legally mandated in Europe and elsewhere
Sales of new spectrum completed in Europe
At prices that now seem exorbitant
Dr. Omar R Daoud ٣٠
TD-SCDMA
Time division duplex (TDD)
Chinese development
Will be deployed in China
Good match for asymmetrical traffic!
Single spectral band (1.6 MHz) possible
Costs relatively low
Handset smaller and may cost less
Power consumption lower
TDD has the highest spectrum efficiency
Power amplifiers must be very linear
Relatively hard to meet specifications
Dr. Omar R Daoud ٣١
CDMA
GSM
TDMA
PHS (IP-Based)
64 Kbps
GPRS
115 Kbps
CDMA 1xRTT
144 Kbps
EDGE
384 Kbps
cdma20001X-EV-DV
Over 2.4 Mbps
W-CDMA (UMTS)
Up to 2 Mbps
2G2.5G
2.75G 3G
1992 - 2000+2001+ 2003+
1G
1984 - 1996+
2003 - 2004+
TACS
NMT
AMPS
GSM/GPRS
(Overlay) 115 Kbps
9.6 Kbps
9.6 Kbps
14.4 Kbps/ 64 Kbps
9.6 Kbps
PDC
Analog Voice
Digital VoicePacket Data
IntermediateMultimedia
Multimedia
PHS
TD-SCDMA
2 Mbps?
9.6 Kbps
iDEN(Overlay)
iDEN
Source: U.S. Bancorp Piper Jaffray
Migration To 3G
Dr. Omar R Daoud ٣٣
Mobile Wireless SpectrumBands Frequencies GSM/(MHz) (MHz) Regions EDGE WCDMA CDMA2000
450 450-467 Europe x x480 478-496 Europe x800 824-894 America x x900 880-960 Europe/APAC x x1500 Japan PDC x1700 1750-1870 Korea x1800 1710-1880 Europe/APAC x x x1900 1850-1990 America x x x
2100 1885-2025 & 2100-2200
Europe/APAC x x
2500 2500-2690 ITU Proposal x
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