Overview of Radio Communication

Overview of Radio Communication

OVERVIEW OF RADIO COMMUNICATION

NTIPRIT

National Telecommunication Institute for Policy Research, Innovation and TrainingGhaziabad – 201002. www.ntiprit.gov.in

Naveen Jakhar, ITS

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Topics covered in this Presentation:1. Radio & Microwave Communication. 2. Spectrum Management.3. Digital Microwave Systems.4. Fading and measures to counter Fading effect.5. Digital Microwave link – Performance

Objectives.6. Modulation Methods.7. A word about BWA 8. Other wireless communication Applications


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Overview of Radio Communication PHz = petahertzEhz = exahertz

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+ Satellite TV+ WiFi, BluetoothCellphones +

+ Satellite TVGPS +

Short-Wave

Broadcast

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Radio Waves Propagation

• Ground Waves - < 30 MHZ (Tropospherically Reflected)• Sky Waves – reflected by ionosphere. Short Waves 30MHz – 40 MHz ( Ionospherically Reflected)• Space Wave- > 40 MHZ ( >1000 MHZ also know as LOS )

Ground Waves - suitable for frequencies < 30 M Hz.

Waves travel in troposphere.• Direct Wave.• Ground Reflected Wave.• Tropospherically Reflected Wave.

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Propagation Modes Ground-Wave

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Propagation Modes Direct-Wave

All Frequencies

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SATELLITEREPEATER

10000 KM

1500 KM750 KM

LOS

MAXIMUM COVERAGE EARTH

TROPOSPHERICSCATTER

IONOSPHERIC REFLECTION(HF RADIO)

FIG. : MODES OF COMMUNICATION8


UHF = Ultra-High Frequency applications

1000 m

3 GHZ300 MHz

10 Km

FREQUENCY

WAVELENGTH

2 GHz

UHF TV

1000 MHz

Keyless Entry 315 MHz

Analog Cell Phone

WiFi etc. 2.4 GHz

Digital Cellphone

GPS 1.575 GHz

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BLUETOOTH- 2.4 - 2.485 GHZ

WI-FI- 2.4-5.0 GHZ

GPS-: L1 (1575.42 MHz) and L2 (1227.60 MHz)

KEYLESS SYSTEMS-315 MHZ

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Overview of Radio Communication 11

Basic mechanisms that impact propagation• Reflection: electromagnetic wave impinges upon an object

which has very large dimensions when compared to the wavelength of the propagation wave.– Occurs from the surface of the earth, building and walls.

• Diffraction: occurs when the radio path is obstructed by a surface that has sharp irregularities (edges).– Secondary waves present throughout the space and even

behind the obstacles, giving rise to a bending of waves around the obstacles.

• Scattering: occurs when the medium through which the wave travel consists of objects with dimensions that are small compared to the wavelength, and where the number to obstacles per unit volume is large. foliage, atmospheric impurities.


2.Spectrum Management

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At national level, each administration has its own regulating agency like NTIA/FCC in USA, Ofcom in UK and WPC Wing in India.

WPC- Wireless Planning and Coordination Wing, under DOT,MOC &IT HQ at Sanchar Bhawan New Delhi.

Radio spectrum is divided into spectrum bands that are allocated to specific services, such as mobile, fixed, broadcast, fixed satellite and mobile satellite services on exclusive basis.

Spectrum Management

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In India the Wireless Planning & Coordination (WPC) Wing of the Ministry of Communications & IT, is the National Radio Regulatory Authority responsible for Frequency Spectrum Management, including licensing and caters for the needs of all wireless users (Government and Private) in the country.

The WPC Wing performs its functions through various divisions / groups.

The wireless services is based on National Frequency Allocation Plan (NFAP) which was made effective from 01.01.2000. The latest one is Draft NFAP 2011.

NFAP is the basis for development, manufacturing and spectrum utilization activities in the country.

Spectrum Management in India Spectrum Management in India

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Transmission Systems

Bounded media

(Optical Fiber, coaxial cable)

•Bounded media require a physical connection between two points to guide current, electromagnetic wave or light.

Unbounded media

(UHF, VHF, Microwave and Satellite)

Unbounded media needs no such physical connection .

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OF Vs MW Systems

OF Systems

• Very High Bandwidth

• up-to 40 GBps with DWDM

• High Reliability

• OF cable susceptible to cuts etc.

MW Systems

• Limited Bandwidth due to Radio.

• Max up-to STM-1 systems.

• Less Reliable.

• Quick Deployment

• Suitable for Hilly, inaccessible and difficult terrain areas.

• Mobile End links

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Microwave Systems

1. Unlike Cellular Systems, Microwave systems work on Line of Sight (LOS) principle.

3. Wideband Microwave Systems operate between stations that are hundreds of Kms apart with number of Repeaters in between.

• Station A, Station B.• Tx and Rx Antenna.• Hop Distance.

2. Microwave Systems are point to point systems.

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Radio Frequency Bands(ITU Designations)

VHF band 30 – 300 MHz

UHF 300 – 3000 MHz

beyond 1000 MHz

LOS communication

SHF 3GHz to 30 GHz

EHF 30 GHz to 300 GHz

VHF-Very High Frequency. UHF-Ultra high freq.

SHF- super high freq. EHF-Extremely High Freq. 19


L 1-2 GHz S 2-4 GHz

C 4-8 GHz

X 8-12 GHz

Ku 12-18 GHz

K 18-27GHz Ka 27-40GHz V 40-75GHz

M/W Frequency Bands

W 75-110GHz

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Frequency Usage

Some commonly used MW Bands are:

• Police Radios: Country dependent.

• FM Radio: 100 MHz Approx.

• Television: 300 MHz Approx.

• Mobile networks: 450-2000 MHz Approx.

• Trunk Routes 2-100GHz.

The frequencies used by mobile networks varies according to the standard being used.

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Spectrum Bands Identified for various wireless telecom services (INDIA)

Band Technology450MHz 2G & 3G

700 MHz Digital Mobile TV

800 MHz 2G & 3G

900MHz 2G

1800MHz 2G

1900MHz 2G & 3G

2010-2025 MHz BWA

2.1 GHz 3G

2.3 GHz BWA

2.5 GHz BWA

3.3 GHz BWA

3.4GHz BWA

2.4-2.4835, 5.15-5.35 & 5.725-5.875 GHz are de-licensed spectrum bands.

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Fading - Occurs due to multi-path signals.

Challenges of Radio Transmission

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Counter Measures For Fading

• Diversity Techniques

• Space Diversity.

• Frequency Diversity.

• Power Control

• ATPC- Automatic Transmit Power Control

• RTPC-Remote Transmit Power Control

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Classification of Radio Transmission Equipment

• Low Capacity • 2 Mbps• 8 Mbps

UHF(400-700MHz)2Ghz

• Medium Capacity

• 34 Mbps 7 & 13 GHz.

• Large Capacity

• 140 Mbps 4,6 & 11 GHz.

• Mini- Links • up-to 16 E1’s(34 Mbps)

15 & 18 GHz,.

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Commonly Used Digital MW Systems

Long Haul Systems Make

i) High Capacity 6 Ghz 140 Mb/s Systems Fujitsu, NEC, BEL, ITI

(carrying 1920 voice channels )

Used in Main Trunk Routes

ii) Medium Capacity

7Ghz, 34 Mb/s Fujitsu, NEC, BEL, ITI

Used in thin Routes

Short Haul Systems

11 Ghz, 140 Mb/s

Used for satellite End Links NEC & Others

13 Ghz, 34 Mb/s Used for junction Networking27


Microwave System configuration

Radio equipment required at the terminal :

1. Base Band (BB) Processing equipment.

2. I.F modulation equipment/ De-MOD equipment

3. UP converter/ Down Converter.

4. Power Amplifier

5 Antenna Sub. System.

6 Equalizer

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( Base Band Processing )

B.P.F. P.A. (FET)

RFCombiner

Antenna

RF(6GHz)

140 Mbps MOD

140

Mbps IF RF(6GHz)

DEMODEQUALIZER

D / C B.P.F. Amplifier

BLOCK SCHEMATC OF A 6-GHZ DIGITAL M/W SYSTEM

IF( 70MHz)

U / C

( 70MHz)IF

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Lower Band

Fr in M Hz Upper Band

Fr in M Hz

1,1x 6460 1’,1’x 6800

2,2x 6500 2’.2’x 6840

3,3x 6540 3’,3’x 6880

4,4x 6580 4’,4’x 6920

5,5x 6620 5’,5’x 6960

6, 6x 6660 6’,6’x 7000

7,7x 6700 7’,7’x 7040

8,8x 6740 8’,8’x 7080

Frequency Plan for 6 G Hz Digital M/W Systems

( 6425-7110 M Hz )

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Mini-Link

Medium Capacity point to point Microwave link of capacity 4-16 E1 links operating in 15, 18, 23 and 38 G Hz bands.

Small radio unit together with an integrated compact antenna forms ODU.

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Digital ModulationDigital Modulation

Carrier signal: Ac cos (2fct +)

Modulation: m(t)

Modulated signal: Ac (t) cos (2fc(t) t +(t))

Vary Vary Varyamplitude frequency phase

Variations are discrete!!!!!

m(t); discrete

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Digital Modulation Types

1. AMPLITUDE MODULATION(ASK or OOK)

( Amplitude Shift Keying or On off Keying)

2. FREQUENCY MODULATION(FREQUENCY SHIFT KEYING- FSK)

3. PHASE MODULATION(PHASE SHIFT KEYING -PSK)

4 QUADRATURE AMPLITUDE MODULATION (QAM)

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Required RF Bandwidth:

RF BW = Rs/Rc*(1+α ) Rs = Symbol Rate. Rc= coding rate. α = cosine roll-off factor of RRC filter.

Free Space Path Loss:

FSL = 32.2 + 20 log (f) + 20 log (d) in db. f = frequency in MHz. d = distance in kms.

Some Fundamental Formulae

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What is the Required RF Bandwidth to carry 64kbps of data stream, which is ½ Rate coded and BPSK modulation is used ? Assume RRC filters with α = 0.25.

Some Fundamental Formulae

What is the change in RF Bandwidth requirement if QPSK modulation is used instead of BPSK modulation ?

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What is ?

• WiMAX or “Worldwide Interoperability for Microwave Access” had its origins in backhaul connectivity using microwave access.

• WiMAX has become a “hot topic” in the wireless industry, with visible and aggressive backing from INTEL, among others.

• WiMAX is designed to provide “last-mile” or “backhaul” connectivity using wireless – “Last-mile” refers to a wireless connection from a major trunk line to a business or residential user

– Using IEEE 802.16 Broadband Wireless Access (BWA) standard, approved in January 2003, to provide operations in the <11GHz spectrum range

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http://www.wimaxforum.org/


WiMAX Vision: Broadband Everywhere

BWA Operator Network Backbone

INTERNETBACKBONE

Mobile Backhaul

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RESIDENTIAL & SoHo DSL LEVEL SERVICE

1

802.16d

FRACTIONAL E1 for SMALL BUSINESS

E1+ LEVEL SERVICE ENTERPRISE

BACKHAUL for HOTSPOTS

2

802.16d

HH

HHH

H

H

H

H

WMAN Nomadic Coverage --> handoff from HOT SPOTS

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= wide area coverage outside of Hot Spots

Mobility

5802.16e

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Other Applications

• RFID• Intelligent Transport System(ITS)• Amateur radio (HAM)

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RFID OperationsRFID Operations

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Technical Parameter Active RFID Passive RIDTag Power Source Internal to Tag Energy transferred from

Reader via RF

Tag Battery Yes No

Availability of Tag Power

Continuous Only within the range of Reader field

Requirement of Signal Strength from Reader to Tag

Low High

Available Signal Strength from Tag to Reader

High Low

Active and Passive TagsActive and Passive Tags

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Radio Frequency Identification Devices (Exemption from Licensing Requirement) Rules, 2005

• “Use of low power Equipment in the frequency band 865 – 867 MHz for (RFID) Radio Frequency Identification Devices (Exemption from Licensing Requirement) Rules, 2005 -rules were published in the Gazette of India, Part II, Section 3, Sub-Section (i), dated the 11th March, 2005, vide notification No.168 (E), dated the 11th March, 2005.

• Rule 3. Use of wireless equipment in the band 865 – 867 MHz.-

Notwithstanding anything contained in any law for the time being in force, no licence shall be required by any person to establish, maintain, work, possess or deal in Radio Frequency Identification Devices (RFID), on non-interference, non-protection and non-exclusive basis, in the frequency band 865 – 867 MHz with maximum 1 Watt transmitter power, 4 Watts Effective Radiated Power and 200 kHz carrier bandwidth.

• Rule 4. In case where any person to whom a licence has been issued under section 4 of the Act, informs that his licensed system is getting harmful interference from any other radio communication system exempted under these rules, the use of such unlicensed Wireless equipment shall be discontinued forthwith.

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Intelligent Transport System(ITS)

• Intelligent transport systems (ITS) are advanced applications which aim to provide innovative services relating to different modes of transport and traffic management and enable various users to be better informed and make safer, more coordinated, and 'smarter' use of transport networks.

• ITS are systems in which information and communication technologies are applied in the field of road transport, including infrastructure, vehicles and users, and in traffic management and mobility management, as well as for interfaces with other modes of transport.

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Amateur radio (HAM)

Amateur radio (also called "ham" radio) is the use of designated radio frequency spectra

• for purposes of private recreation, • Non commercial exchange of messages, • Wireless experimentation, self-training, and emergency

communication.

The term "amateur" is used to specify "a duly authorised person interested in radio-electric practice with a purely personal aim and without pecuniary interest, and to differentiate it from commercial broadcasting, public safety (such as police and fire), or professional two-way radio services (such as maritime, aviation, taxis, etc.).

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Amateur radio (HAM)

The WPC—regulates amateur radio in India. The WPC assigns call signs, issues amateur radio

licences, conducts exams, allots frequency spectrum, and monitors the radio waves.

In India, the Amateur radio Society of India (ARSI) represents amateur radio interests at various forums.

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Thank You !!

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Education

Overview of Radio Communication