Principles of Wireless Communications

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21 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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Dr. Ing. Dirk Wübben
Department of Communications Engineering
Institute for Telecommunication and High Frequency
University of Bremen, Germany
Phone: +49 421 218-2407
wuebben@ant.uni-bremen.de
www.ant.uni-bremen.de
Principles of Wireless Communications
3rd
BaSoTiSummer School, Riga, Latvia
Dirk WübbenPrinciples of Wireless Communication
2
Universität
Bremen
Course Overview
1. Introduction
Historical overview
Examples for wireless communication systems
2. Signals and Systems
Summary of mathematical description for signals and systems
3. Principles of Digital Wireless Communications
Basic components of a digital wireless communication system
4. Orthogonal Frequency Division Multiplexing
Mobile Fading Channel
OFDM: an elegant way of equalization
Dirk WübbenPrinciples of Wireless Communication
3
Universität
Bremen
Early History of Wireless Communication
Wireless Communication: Transmission of information without wires
Many people in history used light for communication
Optical telegraphs (Greece, 350 BC)
Signaling towers (flags) (China, Han-Dynasty, 206 BC –24 AC)
Smoke signals for communication (Greece, 150 BC)
Optical telegraph, Claude Chappe(1794)
Dirk WübbenPrinciples of Wireless Communication
4
Universität
Bremen
Electromagnetic Waves
Discovery of electromagnetism
1820 OerstedElectric current generates magnetic field
1831 Faradaydemonstrates electromagnetic induction
Electromagnetic Waves
1864 MaxwellTheory of electromagnetic fields, wave equations
1895 HertzProof of electromagnetic waves
Dirk WübbenPrinciples of Wireless Communication
5
Universität
Bremen
History of Communication
Application to Communication
1837 MorseFirst Telegraph
1861 ReisFirst Telephone (Patent Bell 1876)
Wireless Communication
1901 MarconiFirst transatlantic transmission
first demonstration of wireless telegraphy (digital!)
long wave transmission, high transmission power necessary (> 200kw)
Digital Communication
1948 Shannon„A Mathematical Theory of Communication“
Dirk WübbenPrinciples of Wireless Communication
6
Universität
Bremen
1. Generation of Mobile Communication
A-Netz(1958-1977)
Call set up from mobile to fixed only
No handover between cells
approx. 11000 subscriber (1971)
B-Netz(1972-1994)
Germany, Austria, Luxembourg
Call set up from fixed to mobile with knowledge of mobile‘s position
1979 13 000 Subscriber, heavy „Mobiles“mainly in cars
approx. 27.000 subscribers (1986)
less than 1 Mio. subscribers worldwide
C-Netz(1985)
Handover between cells
Automaticallocalization
Digital siginaling
approx. 850.000 subscriber (1993)
Der Abschied von ABC-Eine Zeitreise zu den wichtigsten
Stationen, Broschüre der T-Mobil, www.handy-sammler.de
Dirk WübbenPrinciples of Wireless Communication
7
Universität
Bremen
2. Generation of Mobile Communication
Digital Transmission to improve system capacity, coverage
and QoS
Typical Networks: IS-95 (US), D-AMPS (US), PDC (Japan) and
GSM
GroupeSpécialeMobile (1982)
Development of European digital mobile communication system
Global System for Mobile Communication (1992)
Germany: D-Netz(900 MHz) and E-Netz(1800 MHz)
Voice is the dominating application but systems are capable of fax, data, SMS, MMS, …
International Roaming
Data rate 9,6 kbit/s(compare ISDN: 64 kbit/sand DSL: ≥16 Mbit/s)
More than 1 Billion subscriber worldwide (2004)
Extensions for higher data rate (2.5 G)
High Speed Circuit Switched Data: 57,6 kbit/s
General Packet Radio System: 115,2 kbit/s
Enhanced Data Rate for GSM Evolution: 384 kbit/s
SonyEricssonP900, 2004
www.sonyericsson.de
Motorola International 1000
www.handy-sammler.de/Museum/13.html
Dirk WübbenPrinciples of Wireless Communication
8
Universität
Bremen
3. Generation of Mobile Communication
3G
World-wide harmonization (services, data rates)
Improved/extended data services, capacity and flexibility
Standardization at ITU: IMT-2000
User Data Rates: 144 kbit/s–2 Mbit/s
Universal Mobile Telecommunications System (UMTS)
One implementation of IMT-2000 with compatibility to GSM
New Air Interface (W-CDMA)
New frequency range (2 GHz)
Core Network from GSM/GPRS (first release, R’99),
Further evolvement in releases (R’99, R4, R5, R6)
Applications
Video-Conferencing and Video-Streaming
Mobile office
Medical emergency
Localization-based services
Download of music
Siemens U10
ww.siemens.de
NOKIA 7600,
www.nokia.com
http://www.europeanmobiles.com
Dirk WübbenPrinciples of Wireless Communication
9
Universität
Bremen
Short-range Wireless Communication
Wireless Local Area Networks (WLAN)
Wireless network connection with limited coverage
Data rates up to 54 Mbit/s
Orthogonal Frequency Division Multiplexing (OFDM)
Bluetooth
Replacement for short wired connections
Data rate ca. 1 Mbit/s
Ultra WideBand(UWB)
Very high data rates
Coexistence with other standards
Dirk WübbenPrinciples of Wireless Communication
10
Universität
Bremen
Frequencies for Communication
VLF = Very Low FrequencyUHF = Ultra High Frequency
LF = Low Frequency SHF = Super High Frequency
MF = Medium Frequency EHF = Extra High Frequency
HF = High Frequency UV = Ultraviolet Light
VHF = Very High Frequency
Frequency and wave length:
wave length λ, speed of light c0

3x108m/s, frequency f
1 Mm
300 Hz
10 km
30 kHz
100 m
3 MHz
1 m
300 MHz
10 mm
30 GHz
100 μm
3 THz
1 μm
300 THz
visible light
VLFLFMFHFVHFUHFSHFEHFinfraredUV
optical transmission
coax cable
twisted
pair
λ=
c0
f
Dirk WübbenPrinciples of Wireless Communication
11
Universität
Bremen
Frequencies and Regulations
ITU-R holds auctions for new frequencies, manages frequency bands worldwide (WRC, World Radio
Conferences)

Europe
USA
Japan
Cellular
Phones
GSM
450-457, 479-
486/460-467,489-
496, 890-915/935-
960,
1710-1785/1805-
1880
UMTS
(FDD) 1920-
1980, 2110-2190
UMTS
(TDD) 1900-
1920, 2020-2025
AMPS
,
TDMA
,
CDMA

824-849,
869-894
TDMA
,
CDMA
,
GSM

1850-1910,
1930-1990
PDC

810-826,
940-956,
1429-1465,
1477-1513

Cordless
Phones
CT1+
885-887, 930-
932
CT2
864-868
DECT
1880-1900
PACS
1850-1910, 1930-
1990
PACS-UB
1910-1930
PHS

1895-1918
JCT

254-380
Wireless
LANs
IEEE 802.11
2400-2483
HIPERLAN 2
5150-5350, 5470-
5725
902-928
IEEE 802.11
2400-2483
5150-5350, 5725-5825
IEEE 802.11

2471-2497
5150-5250
Others
RF-Control
27, 128, 418, 433,
868
RF-Control
315, 915

RF-Control

426, 868