wireless lecture by xafran khan

7/29/2019 wireless lecture by xafran khan

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Wireless Communication

Systems

Lecture 1

Introduction to WirelessCommunication Systems


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Course Information Instructor:

Asad Khan

Office:

101, (Floor 1, EE building)

E-mail:

[email protected]

Pre-requisites:

EEE314 Data Communications and Computer Networks

EEE463 Antennas and Radio Wave Propagation

Class Homepage:

http://groups.yahoo.com/group/wirelesscomsys/

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mailto:[email protected]:[email protected]


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Recommended Books

Course material about most of the topics can be found in the following textbooks.

Wireless Communications,

Andrea Goldsmith,

Cambridge UniversityPress, 2005

Wireless Communications:

Principles and Practice,

Theodore S. Rappaport,

2nd ed., Prentice Hall, 2002


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Course Content

Lecture # Topics covered

1 Introduction to Wireless Communication Systems.

24 Cellular Concepts.

Frequency Reuse.

Channel Assignment Strategies.

Handoff Strategies.

Interference and System Capacity.

Trunking and Grade of Service.

Improving Coverage and Capacity in Cellular Systems.

57 Mobile Radio Propagation: Large-scale Path Loss.

Free-space Propagation Model.

Reflection, Diffraction and Scattering Mechanisms.

Two-ray Propagation Model.

Practical Link Budget Design using Path Loss Models. Outdoor Propagation Models: Okumara Model, Hata Model, Walfisch and Betroni Model.

Indoor Propagation Models: Wall and Floor Factor Model, ITU-R Model, COST 231 Multi-

wall Model; COST 231 LOS Model, COST 231 NLOS Model, Floor Gain Model, Physical Model,

Double Diffraction Paths, Path Loss vs. No. of Floors.

Ray Tracing and Site Specific Modeling.

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Course Content (cont.)Lecture # Topics covered

8

10 Mobile Radio Propagation: Small-scale Fading and Multipath. Doppler Shift and Power Delay Profile.

Flat Fading.

Frequency Selective Fading.

Fast and Slow Fading.

Rayleigh and Rician Distributions.

Shadowing.

Doppler Spread.

Average Fade Duration and Level Crossing Rate.

1114 Modulation Techniques for Wireless Communications.

Analog Modulation Techniques: Amplitude Modulation, Angle Modulation.

Digital Modulation Techniques: BPSK, QPSK, GMSK.

OFDM and other spread spectrum modulation techniques.

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17 Channel Equalization and Diversity Techniques. Linear and Non-linear Equalizers.

Algorithms for Adaptive Equalization.

Diversity Techniques.

1819 Multiple Access Techniques for Wireless Communications.

TDMA

FDMA

CDMA 5


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Course Content (cont.)Lecture # Topics covered

2021 Mobile Cellular Systems.

GSM

IS-95

UMTS

22 Packet Radio Networks.

GPRS

EDGE

23 Wireless Local Area Networks.

IEEE 802.11 a/b/g/n standard

24 Wireless Personal Area Networks.

Bluetooth / IEEE 802.15.1

2527 MIMO Systems.

2829 Ad Hoc Wireless Networks.

3032 Seminar Series and Course Review.

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What is wireless communication?

Any form of communication that does not require the

transmitter and receiver to be in physical contact.

Mode of transfer of information over a distance without the

use of electrical wires.

The term wireless should not be confused with the term

cordless, which is a subclass of wireless.

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Why wireless communication?

User mobility tetherless connectivity

Reduced infrastructure cost reduced cabling

Flexibility stay connected anywhere anytime

Portable devices small volume, light enough to be carried

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History of Wireless Communications

(cont.) 1896: Marconi

first demonstration of wireless telegraphy

transmission of radio waves to a ship at sea 29km away

long wave transmission, high power req. (200kW and +) 1901: Marconi

Telegraph across the Atlantic ocean

close to 3000km hop

1907: Commercial transatlantic connections

huge ground stations (30 x 100 m antennas)

1915: Wireless telephony established

NY San Francisco

Virginia and Paris

1920: Marconi

discovery of short waves (


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History of Wireless Communications (cont.)

1930s: TV broadcasting deployment

1946: first public mobile telephone service in US

single cell system

1960s: Bell Labs developed cellular concept

brought mobile telephony to masses

1960s: communications satellites launched

Late 1970s: technology advances enable affordable cellular telephony

development of highly reliable, miniature, solid-state radio frequency hardware

entering the modern cellular era

1974-1978: first field trial for cellular system

AMPS, Chicago

1983: 1st generation systems were deployed

Analog signals (AMPS, NMT, FDMA, FM)

Early 1990s: 2nd generation systems were deployed

Digital signals (GSM, IS-136, IS-95, TDMA)

2000-01: 3rd generation systems were deployed

Korea and Japan (IMT2000 standard, UMTS, CDMA2000) 10

200?: 4G

(LTE, UMB)


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History of Wireless Communications (cont.)

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cellular phones satellites wireless LANcordlessphones

1992:

GSM

1994:

DCS 1800

2001:

IMT-2000

1987:

CT1+

1982:

Inmarsat-A

1992:

Inmarsat-B

Inmarsat-M

1998:

Iridium

1989:

CT 2

1991:

DECT 199x:

proprietary

1997:

IEEE 802.11

1999:802.11b, Bluetooth

1988:Inmarsat-C

analogue

digital

1991:

D-AMPS

1991:

CDMA

1981:

NMT 450

1986:

NMT 900

1980:

CT0

1984:

CT1

1983:

AMPS

1993:

PDC

4G fourth generation: when and how?

2000:

GPRS2000:

IEEE 802.11a

200?:

Fourth Generation


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Challenges in Wireless

Communications

Wireless channel is an unpredictable and difficultcommunications medium.

Radio spectrum is a scarce resource, and can be very

expensive. It must be used extremely efficiently. Security is difficult to implement.

Wireless networking issue.

Interfacing between wireless and wired networks

with different performance capabilities is a difficulttask.


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Design Challenges

Wireless channels are a difficult and capacity-limitedbroadcast communications medium

Traffic patterns, user locations, and network

conditions are constantly changing

Applications are heterogeneous with hard constraintsthat must be met by the network

Energy and delay constraints change designprinciples across all layers of the protocol stack


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Wireless networks in comparison to fixed networks

Higher loss-rates due to interference

Emissions of, e.g., engines, lightning, congested spectrum

Restrictive regulations of frequencies

Frequencies have to be coordinated, useful frequencies arealmost all occupied

Low transmission rates

Local some Mbit/s, regional currently, e.g., 9.6kbit/s withGSM

Higher delays, higher jitter

Lower security, simpler active attacking

Radio interface accessible for everyone, base station can besimulated, thus attracting calls from mobile phones

Always shared medium

Secure access mechanisms important


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Base Station: A fixed station in a mobile radio system used for radiocommunication with mobile stations. Base stations are located at the center oron the edge of a coverage region and consist of radio channels and transmitterand receiver.

Control Channel: Radio channel used for call setup, call initiation, call requestand other beacon or control purposes.

Forward Channel: Radio channel used for transmission of information fromthe base station to the mobile

Full Duplex Systems: Communication systems which allow simultaneous two-way communication.

Half Duplex Systems: Communication systems which allow two-waycommunication by using the same radio channel for both transmission andreception. At any given time, the user can only either transmit or receiveinformation.

Handoff: The process of transferring a mobile station from one channel orbase station to another.

Mobile Station: A station in the cellular radio service intended for use while inmotion in unspecified locations. Mobile stations may be hand-held personalunits(portables) or installed in vehicles(mobiles).

Wireless Communication System Definition


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Mobile Switching Center: Switching center which coordinates the

routing of calls in large service area. In a cellular radio system, the MSC

connects the cellular base stations and the mobiles to the PSTN. An

MSC is also called a mobile telephone switching office (MTSO).

Reverse Channel: Radio channel used for transmission if information

from the mobile to base station.

Roamer: A mobile station which operates in service area(market) other

than that from which service has been subscribed .

Simplex Systems: Communication systems which provide only one

way communication.

Subscriber: A user who pays subscription charges for using a mobile

communication system.

Transceiver: A device capable of simultaneously transmitting and

receiving radio signals.

Wireless Communication System Definition


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Electromagnetic Spectrum104 102 100 10-2 10-4 10-6 10-8 10-10 10-12 10-14 10-16

104 106 108 1010 1012 1014 1016 1018 1020 1022 1024

IR UV X-RaysCosmic

Rays

Radio

Spectrum

1MHz ==100m

100MHz ==1m

10GHz ==1cm< 30 KHz VLF

30-300KHz LF

300KHz3MHz MF

3 MHz

30MHz HF30MHz300MHz VHF

300 MHz3GHz UHF

3-30GHz SHF

> 30 GHz EHF

Micro

wave

Visible light


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Wireless Communication Spectrum


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Wireless Communication Spectrum


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In Pakistan!!! Zong

GSM (Global Systems for Mobile Communication )

Uplink: 882.5 MHz

890.1 MHz = 7.6MHz Downlink: 927.5 MHz 925.1 MHz = 2.4 MHz

DCS (Digital Cellular Services)

Uplink : 1729.7 MHz - 1745.7 MHz

Downlink: 1834.7 MHz - 1840.7 MHz

Warid

GSM (Global Systems for Mobile Communication )

Uplink: 890.5 Mhz 894.9 Mhz = 40.6Mhz

Downlink: 935.1 Mhz 939.9 Mhz = 4.8Mhz


Uplink : 1710.1Mhz 1718.9 Mhz

Downlink : 1805.1 Mhz -- 1813.9 Mhz


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Ufone:

GSM ( Global Systems for Mobile Communication)

Uplink: 894.9 Mhz

902.5 Mhz = 7.6 Mhz Downlink: 939.5 Mhz - 947.5 Mhz = 8Mhz


Uplink: 1718.9 Mhz 1724.9 Mhz

Downlink: 1813.9 Mhz 1819.9 Mhz

Mobilink

GSM(Global Systems for Mobile Communication)

Uplink: 902.5 Mhz 907.3 Mhz

Downlink: 947.5 Mhz 952.3 Mhz

DCS (Digital Cellular Services) Uplink: 1724.9 Mhz 1733.7 Mhz

Downlink: 1819.9 Mhz 1828 Mhz


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Amateur radio

Cellular systems

Wireless LANs

Satellite Systems Paging Systems

Bluetooth headsets

Ultra-wide band radios

Land-sea communication systems, etc...

Examples of Wireless Communication

Systems

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Figure. Structure of a cellular network


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Examples of Wireless Communication

Systems (cont.)

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Satellite Network

Wireless Wide Area

Networks

Wireless Metropolitan Area

Networks

Wireless Local Area

Networks

Wireless Personal Area

Networks

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