1 Frequency

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UNIT IUNIT IWIRELESS TRANSMISSIONWIRELESS TRANSMISSION

Frequencies Signals, antennas, signal propagationMultiplexing Spread spectrum, modulation Cellular systems


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Source coding: Digital presentation of information

Block oriented: Test;ASCII,EBCDIC

Image:GIF,JPEG

Stream oriented: voice, audio music video

Line coding: NRZ, RZ, Manchester etc.

Channel coding:Linear coding, Block coding,Convolution coding, Hamming, CRC


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FREQUENCY CHARTFREQUENCY CHARTc. (infra red).

Radio transmission starts at several kHz, the very low frequency (VLF)

range. These are very long waves. Waves in the low frequency (LF) range are

used by submarines, because they can penetrate water and can follow the

earthssurface. Some radio stations still use these frequencies, e.g., between 148.5 kHz

and 283.5 kHz in Germany. The medium frequency (MF) and high frequency

(HF) ranges are typical for transmission of hundreds of radio stations either as

amplitude modulation (AM) between 520 kHz and 1605.5 kHz, as short wave

(SW) between 5.9 MHz and 26.1 MHz, or as frequency modulation (FM)

between 87.5 MHz and 108 MHz. The frequencies limiting these ranges are typi-

cally fixed by national regulation and, vary from country to country. Short

waves are typically used for (amateur) radio transmission around the world,

enabled by reflection at the ionosphere. Transmit power is up to 500 kW

which is quite high compared to the 1 W of a mobile phone.

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Frequencies for communication

VLF = Very Low Frequency UHF = 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

1 Mm

300 Hz

10 km

30 kHz

100 m

3 MHz

1 m

300 MHz

10 mm

30 GHz

100 m3 THz

1 m300 THz

visible lightVLF LF MF HF VHF UHF SHF EHF infrared UV

optical transmissioncoax cabletwisted

pair

Frequency and wave length: = c/f

wave length , speed of light c 3x108m/s, frequency f


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VHF-/UHF-ranges for mobile radio

simple, small antenna for cars deterministic propagation characteristics, reliable

connections

SHF and higher for directed radio links, satellitecommunication

small antenna, beam forming

large bandwidth available

Wireless LANs use frequencies in UHF to SHF range

some systems planned up to EHF

limitations due to absorption by water and oxygenmolecules (resonance frequencies)

weather dependent fading, signal loss caused byheavy rainfall etc.

Frequencies for mobile communications


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AM: uses 520-1605.5KHz(SW)-broadcast/500Kw (MF)

FM: uses 5.9-26.1MHz(HF)

TV:174-230MHz and 3470-790MHz 9(VHF/UHF)

DAB: 223-230MHz and 1452-1472MHz

DTV:470-862MHz

Analog Mobile: 450-465MHz(UHF)

Digital mobile (GSM):890-960MHz,1710-1880MHz

CTS(DECT): 1880-1900MHz

3G:1900-11980MHz, 2020-2025MHz,2110-2190MHz(UHF)

Microwave:2-40GHz(SHF)

IrDA:850-900nm(Infra red)

Few examples

Digital audio broadcasting


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Regulatory organization

ITU-international telecommunication union

WRC-world radio communication conference

ITU

Country

proposal WRC

International

Frequency

Allocation

table

Allocation

extension

India: national frequency allocation plan

9KHz-3000GHz-Fixed telecommunication

-Mobile communication

-Broadcasting

-Radio navigation

-Sattellite

-Aeronautical

etc


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CEPT: European conference of postal and telecommunication

Regulates international radio and telecommunications

ETSI-European telecommunication standard institute: responsioble

For standardization. Partner in 3GPP

ECC-Electronics communication committee: respobsible for radio

communication a and telecommunication

FCC- Federal communication committee:USA:

-broadband

-competition

-spectrum

-media-public safety

-homeland security

ISM: industry, scientific and medical application. Unlicensed band


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Frequencies and regulations

ITU-R holds auctions for new frequencies, manages frequency bands

worldwide (WRC, World Radio Conferences) Europe USA Japan

CellularPhones

GSM 444- ,-/- ,444444-,444444- /-,444

4444- /44444444-4444

UMTS (FDD) -

,44444444-4444UMTS (TDD) 4444-

,44444444-4444

AMPS , TDMA , CDMA 444- ,444 444-444TDMA , CDMA , GSM 4444- ,44444444-4444

PDC 444- ,444 444- ,4444444- ,4444 4444-4444

CordlessPhones

CT +4 444- ,444444-444

CT4

444-444DECT

4444-4444

PACS 4444- ,44444444-4444

PACS -UB4444-4444

PHS 4444-4444JCT 444-444

WirelessLANs

IEEE .444444444-4444HIPERLAN 44444- ,44444444-4444

444-444IEEE .444444444-44444444- ,44444444-4444

IEEE .444444444-44444444-4444

Others RF-Control

, , , ,44444444444444

RF-Control

,444444RF-Control

,444444


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ELECTROMAGNETIC SPECTRUMELECTROMAGNETIC SPECTRUM



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FREQUENCYFREQUENCY

ALLOCATIONSALLOCATIONS



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FREQUENCYFREQUENCY

REGULATIONSREGULATIONSEUROPE www.ero.dkUS- www.fcc.gov

JAPAN-www.arib.or.jp

INDIA-www.trai.gov.in



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WHY VLF ARE NOT USED FOR DATAWHY VLF ARE NOT USED FOR DATA

TRANSMISSION?TRANSMISSION?

DIFFRACTIONCURRENT INDUCED IN EARTHS SURFACE

LOW DATA RATES (SHANNON)

REQUIRE LARGE ANTENNAS FOR EFFICIENTTRANSMISSION(OPT FOR SUBMARINES)

PENETRATE MATERIAL MORE EASILY

NEED BIG CELL SIZE

FREQUENCY REUSE NOT POSSIBLE



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WHY ITU-R REGULATE LOWERWHY ITU-R REGULATE LOWER

FREQUENCIES (UP TO SOME HUNDREDFREQUENCIES (UP TO SOME HUNDRED

GHz) AND NOT HIGHERGHz) AND NOT HIGHER

FREQUENCIES(THz)?FREQUENCIES(THz)?FREQUENCIES IN THz

e.g., Infrared, visible light

Easily blocked by obstaclesNo interference with other

transmissions



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DIFFERENT APPROACHES INDIFFERENT APPROACHES IN

REGULATIONREGULATIONEUROPE

ETSI(European TelecommunicationsStandards Institute)

Creates world class standards firstand develop system

e.g., HIPERLAN, GSM

UNITED STATES FCC(Federal Communications

Commission)

Develop system and then

standardize 27/07/11 EEE620 WIRELESS MOBILENETWORKS 16


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IMPORTANCE OF ISMIMPORTANCE OF ISM

BANDSBANDSINDUSTRIAL, SCIENTIFIC AND MEDICALReserved internationally for the use of

RF electromagnetic fields for ISM

Devices are made attuned to ISMbands

e.g., WLAN adapters

Communications equipment mustaccept any interference generated byISM equipment.



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ISM BAND CHARTISM BAND CHART

LICENCE FREE ERRORTOLERANT SYSTEMS

2.4GHz(Microwave, WLAN)

915MHz(Cordlessphones)



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INTERNATIONALINTERNATIONAL

TELECOMMUNICATION UNIONTELECOMMUNICATION UNIONRegulates information and communication

technology issues

ITU is active in areas including broadbandInternet, latest-generation wireless

technologies, aeronautical and maritimenavigation, radio astronomy, satellite-basedmeteorology, convergence in fixed-mobilephone, Internet access, data, voice, TV

broadcasting, and next-generation networks. ITU is based in Geneva, Switzerland, and its

membership includes 191 Member States andmore than 700 Sector Members andAssociates.



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ITU SECTORSITU SECTORS ITU-R

Manages the international radio-frequencyspectrum and satellite orbit resources

ITU-T

Standards group(International Telephone and

Telegraph Consultative Committee or CCITT )

ITU-D

access to information and communicationtechnologies (ICT).

ITU-TELECOM

ITU TELECOM organizes events such asexhibitions.



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ITU REGIONSITU REGIONS

Region 1 comprises Europe, Africa,the Middle East west of the PersianGulf including Iraq, the former SovietUnion and Mongolia.

Region 2 covers the Americas,Greenland and some of the eastern

Pacific Islands.

Region 3 contains most of non-

former-Soviet-Union Asia, east of andincludin Iran and most of Oceania.27/07/11EEE620 WIRELESS MOBILENETWORKS 21


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THANK YOU


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1 Frequency