Post on 26-Dec-2015
transcript
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Chapter 2:Introduction of Wireless and
Mobile Systems
Associate Prof. Yuh-Shyan Chen
Dept. of Computer Science and Information Engineering
National Chung-Cheng University
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In this course
We will discuss the design, deployment, and operation of mobile wireless systems.
The term cellular communications is often interchanged with the terms personal communication service (PCS), and the third-generation (3G) service
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Cellular
One of most prolific voice communication platforms that has been deployed within the last two decades
Cellular systems have always been able to transport data, and many advancement in different modulation formats allow for the delivery of narrowband data.
Cellular systems are unable to provide broadband data service The bandwidth limitationsTypical data rate: 9 kilobits per second (Kbit/s)
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MSC
MSC (Mobile Switching Center)That in turn connects to the PSTN (Public
Switched Telephone Network) or postal, telegraph, and telephone (PTT) systems
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Their main usefulness in their capability to maintain the same contact number even if the user moves from one location to another
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Cellular
Cellular communication is the form of wireless that allows forFrequency reuseMobility of the subscriberHandoffs
Typically, the reference of cellular system is AMPS (Advanced Mobile Phone System) or TACS (Total-Access Communications System)
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Cellular
AMPS operates in the 800 –MHz band821 to 849 MHz for the base station receive869 to 894 MHz for the base station transmitNorth America
TACS890 to 915 MHz for the base station receive935 to 960 MHz for the base station transmit
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Cellular
Many other technologiesSMR (Specialized Mobile Radio)IS-136 iDEN (Integrated Dispatch Enhanced Network)
Cellular radio was initially developed by AT&T (Bell Lab.)To provide additional radio capacity for a
geographic customer service area.
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Cellular
MTS (Mobile Telephone System) Initial mobile systmes
IMTS (Improved Mobile Telephone System)One of the main problem
A mobile call could not be transferred (handed off) from one radio station to another without loss of singnal
This problem was resolved by reusing the allocated frequencies of the system
With the handoff problem solved, the market was able to offer higher radio traffic capacityAllows for more users than with the MTS or IMTS
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Cellular
The cellular systems in USA are broken into MSAs (Metropolitan Statistical Areas)
A-band system
RSAs (Rural Statistical Areas)B-band system
The A band is nonwireline system, and B band is the wireline system for the MSA and RSA.
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Advanced mobile phone system (AMPS)
The cellular standard developed for use in North America
This type of system operates in the 800-MHz frequency
Also developed in South America, Asia, and Russia
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Nordic mobile telephone (NMT)
Developed by the Nordic countries of Sweden, Denmark, Finland, and Norway in 1981.
Operate in the 450- (NMT 450) and 900-MHz (NMT 900) frequency bands.
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Code-division multiple access (CDMA)
An alternative digital cellular standard in the United States
Utilizes the IS-95 standard and is implemented as the next generation for cellular systems.
The CDMA system coexists with the current analog system
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Digial AMPS (D-AMPS)
Also called North American Digital Cellular (NADC)
The D-AMPS is designed to coexist with current cellular systems
Relies on both the IS-54 and the IS-136 standards
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Global system for mobile communication (GSM)
The European standard for digital cellular systems operating in the 900-MHs band
This technology offers international roaming, high speed quality, increased security, and the ability to develop advanced system features
It was completed by a consortium of 80 pan-European countries working togetherTo provide integrated cellular systems across
different borders and cultures
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Total-access communications system (TACS)
Derived from AMPS technologyThe first system was implemented in
EnglandLater these systems were installed in
Europe, China, Hong Kong, Singapore, and the Middle East
A variation of this standard (JTACS) was implemented in Japan
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Integrated dispatch enhanced network (iDEN)
iDEN utilizes a digital radio format called quadrature amplitude modulation (QAM) and is a derivative of GSM
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2.3 GHz
900 MHz
Modem
Wired Access Point
PoletopRadio
2.4 GHz
High-speed dedicated wired
connections
Internet and Corporate Networks
Network InterfaceFacility
The Ricochet Network Overview
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802.11
802.11a, 802.11b (WiFi), and 802.11g802.11a operates in the 5-GHz
Unlicensed national information infrastructure (UNII) band
802.11b and 802.11g operates in the 2.4 GHz ISM band along with Bluetooth
See Table 1.2
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WLAN
The 802.11 specifications were designed initially as a wireless extension for a corporate LAN for enterprise applications
Numerous devices have been manufactured to this specificationThe 802.11b protocol is a shared medium and
utilizes a listen-before-talk protocol called collision sense multiple access/collision avoidance (CSMA/CA)
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WLAN
IEEE 802.11 is important for wireless mobility It provides direct mobile data interoperability
between LAN of a corporation and the wireless operator’s system
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HiperLan/2
Developed by European Telecommunication Standards Institute (ETSI)
Physical layer (similar with 802.11a) uses orthogonal frequency-division multiplexing (OFDM) and is developed in the 5-GHz band
Media-specific access control protocol (MAC) layer uses time-division multiple access (TDMA) format as compared to 802.11a which uses OFDM
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Wireless Network Models
With Infrastructure: Without Infrastructure (ad hoc networks):
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無線隨意網路( Multi-hop Ad Hoc Network )
Laptop
PDA
LaptopLaptop
Laptop
A
B
C
D
E
PDA
Laptop
Laptop
Laptop
PDA
PDA
C'
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Bluetooth
Operates in the 2.4-GHz industrial-scientific medical (ISM) bandAllowing wireless connectivity between mobile
phones, PDAs, and other similar deviceIs meant to replace the infrared telemetry
portion on mobile phones and PDAsEnabling extended range and flexibility in
addition to enhanced service
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Bluetooth
Range is from 10 to 100 meters (m)The protocol does not require line of sight
(LOS) for establishing communicationThe pattern is omnidirectional Delivering data over radio For short distance