Part 1 Nw Introduction

7/31/2019 Part 1 Nw Introduction

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MobileComm Technologies India Pvt. Ltd.

Introduction To Telecommunication

Dallas . Atlanta . Washington . LA . Sao Paulo . New Delhi . Toronto. Muscat.Sydney . Kenya


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Copyright 2011 MobileComm Technologies India Pvt. Ltd.All rights reserved

MobileComm is committed to providing our customers with quality instructor led

Telecommunications Training.

This documentation is protected by copyright. No part of the contents of this

documentation may be reproduced in any form, or by any means, without the prior written consent of

MobileComm Technologies .

Document Number: RK/CT/1/2010

This manual prepared by: MobileComm Technologies

MobileComm Technologies(India)Pvt. Ltd.

424, First Floor, Udyog Vihar Phase -4,

Gurgaon-122002

Headquarter:

MobileComm Professionals Inc.

1255 West 15th Street, Suite 440

Plano, TX, 75075

Tel: (972) 633-5100

Fax: (972) 633-5106

www.mcpsinc.com
http://www.mcpsinc.com/http://www.mcpsinc.com/


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Introduction Of Telecom

History of Wireless Communication

Phases of Network Deployment

Understanding of Basic Terminologies

Analog and Digital Technologies

Concept of ModulationIn depth of Multiple Access Technology

Wireless Generations

Standard Releases

Electromagnetic Propagations

Traffic TheoryConcept of decibel (dB)

Index


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Communication

It is a process of exchanginginformation on theCarrier/Signal.

Establishing link between twoentities (Transmitter andReceiver).

Purpose

Is to transmit an information bearing signal, from source,located at one point ,to a user ordestination, located at anotherpoint some distance (thats whyit is TELE).


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Wire line Telephony


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Wireless Devices

performance

Pager

receive only

tiny displays

simple text

messages

Mobile phones

voice, data

simple text displays

PDA

simple graphical displays

character recognition

simplified WWW

Palmtop

tiny keyboard

simple versions

of standard applications

Laptop

fully functional

standard applications

Sensors,

embedded

controllers


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Courtesy of Rich Howard

First Mobile Radio Telephone


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History

Many people in history used light for communication

heliographs, flags (semaphore), ...

150 BC smoke signals for communication;

(Polybius, Greece)

1794, optical telegraph, Claude Chappe

Here electromagnetic waves are

of special importance: 1831 Faraday demonstrates electromagnetic induction

J. Maxwell (1831-79): theory of electromagnetic Fields, wave

equations (1864)

H. Hertz (1857-94): demonstrates

with an experiment the wave characterof electrical transmission through space

(1886, in Karlsruhe, Germany, at the

location of todays University of Karlsruhe)


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1895 Guglielmo Marconi

first demonstration of wirelesstelegraphy (digital!)

long wave transmission, high

transmission power necessary (> 200Kw)

1901 - First radio signal across the Atlantic (Cornwall to

Newfoundland)

1914 - First wireless voice transmission

1946 - PSTN augmented with wireless

1947 - Cellular Network proposed

The first GSM network was launched in 1991 by Radiolinja in Finland with

joint technical infrastructure maintenance from Ericsson.

History
http://en.wikipedia.org/wiki/Radiolinjahttp://en.wikipedia.org/wiki/Finlandhttp://en.wikipedia.org/wiki/Ericssonhttp://en.wikipedia.org/wiki/Ericssonhttp://en.wikipedia.org/wiki/Finlandhttp://en.wikipedia.org/wiki/Radiolinja


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Some Basic Terms


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Radio Frequency

Frequency is the number of complete cycles per second. The most

common unit of frequency is Hertz.

Radio frequencies are used for many applications in the world today.

Some common uses include:

Television : 300 MHz approx FM Radio : 100 MHz approx

Police Radios : Country dependent

Mobile Networks : 300 to 2000 MHz

An MS communicates with a BTS by transmitting or receiving radio

waves which consists of electromagnetic energy.


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Wavelength

Wavelength is the length of one complete oscillation. It is measured in meter.

Radio waves travels with the speed of light 3*10^8 m/s..

Wavelength = speed/frequency

Wavelength for 900 Band = 33 cm approx

Wavelength for 1800 Band = 17 cm approx


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Bandwidth

Bandwidth is the term used to describe the amount of frequency rangeallocated to one application.

The bandwidth given to an application depends on the amount of

available frequency spectrum.

The amount of bandwidth available is an important factor in determining

the capacity of a mobile system i.e. the number of calls which can be

handled.


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ARFCN/Carrier Spacing/Frequency

Absolute Radio Frequency Channel Number (ARFCN) is the frequency or

spectrum allocated to single subscriber

For Example

In GSM: Carrier Spacing is 200 KHz

In CDMA: Carrier Spacing is 1.25 MHz

In WCDMA: Carrier Spacing is 5 MHz

NOTE: ARFCN/Carrier Spacing/Frequency of one subscriber, all are same.


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Analog & Digital

Transmission


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Digital Transmission, demanded by our customers, has continuallyincreased since its introduction in 1962. This is due, in large part, to the

fact that more of our customers require a high degree of accuracy in theinformation they are transmitting over our network. And with a digitaltransmission (as opposed to analog) system we are able to manage thequality of the signal by managing the transmission impairments.

Thus, digital systems:

Are a better switching interface Are easier to multiplex

Produce clearer signals

Why Digital Transmission


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Analog Transmission

Analog information is continuous and does not stop at discrete values.

An example of analog information is time.

ANALOG SIGNALS

An analog signal is a continuous waveform which changes in accordance

with the properties of the information being represented.


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Digital Transmission

Digital Information

It is a set of discrete values

Digital Signal

For mobile systems , digital signals may be considered to be sets of discrete waveforms.

Advantages of using Digital


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Pulse Code Modulation (PCM) converts analog signals to a digitalformat (signal).

A/D Conversion


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Frequencies below 300 Hz and

above 3400 Hz (Voice Frequencyrange) are filtered from the analog

signal . Ability of Human Ear.

The lower frequencies are filtered

out to remove electrical noiseinduced from the power lines.

The upper frequencies are filtered

out because they require additional

bits and add to the cost of a digital

transmission system.

The actual bandwidth of the

filtered signal is 3100 Hz (3400 -

300). It is often referred to as 4 kHz.

Filtering


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The analog signal is sampled 8000

times per second. The rate at whichthe analog signal is sampled is

related to the twice of highest

frequency, based on the Nyquist

sampling theorem.

Thus, the standard became a

sampling rate of 8000 Hz.

The signal that is the result of the

sampling process contains sufficient

information to accurately represent

the information contained in the

original signal.The output of this sampling

procedure is a Pulse Amplitude

Modulated, or PAM, signal.

Sampling


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Quantize the amplitude of the

samples to one of 255

amplitudes on a quantizing scale.

The purpose is to measure the

amplitude (or height) of the PAM

signal and assign a decimal value

that defines the amplitude.

Based on the quantizing scale,

each sampled signal is assigned a

number between 0 and +127 or

-127 to define its amplitude.

Quantizing And Encoding

The quantized samples are encoded into a digital bit stream (series of

digital pulses).


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Modulation


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Modulation is the process of varying the characteristics of high signal

(carrier) in accordance with instantaneous value of low signal(Modulating signal).

Modulation


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Modulation

Signals are of low amplitude strength with low frequency (20 Hz to 20 KHz).

To send the signal up to longer distance Modulation is required.

Depend on the Modulation: three types of Modulation schemes areintroduced.

Amplitude Modulation

Frequency Modulation

Phase Modulation

GMSK isused for GSM for Modulation


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Modulation Techniques

Baseband Signal

Amplitude Modulation

Frequency Modulation

0 1 0


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Phase Modulation

0 1 01


Baseband Signal


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GMSK- The modulation Techniques in GSM is Gaussian minimum shift

keying( GMSK).GMSK enables the transmission of 270kbps within a 200

KHz channel

BPSK-BPSK is the simplest form of phase shift keying (PSK). It uses twophases which are separated by 180.

QPSK-The mathematical analysis shows that QPSK can be used either to

double the data rate compared with a BPSK system while maintaining the

same bandwidth of the signal, or to maintain the data-rate of BPSKbuthalving the bandwidth needed.


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GMSK, is a form of modulation whish has an advantages of being able to

carry digital modulation while still using the spectrum efficiently. GMSK

modulation are what is known as a continuous phase scheme One of the problems with phase shift keying is that the sidebands extend

outwards from the main carrier and these can cause interference to other

radio communications systems using nearby channels.

In GMSK, there are no phase discontinuities because the frequency changes

occur at the carrier zero crossing points. This arises as a result of the uniquefactor of MSK that the frequency difference between the logical one and

logical zero states is always equal to half the data rate. This can be expressed

in terms of the modulation index, and it is always equal to 0.5

Gaussian Filter Characteristics: sharp cut-off, narrow bandwidth and its impulse

response should show no overshoot.

Gaussian Minimum Shift Keying


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Advantages of GMSK:

1) Amplified by a non-linear amplifier

2) levels of battery consumption

3) more resilient to noise

4) spectral efficiency (BT=0.5)5) impulse response should show

no overshoot

GMSK


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I/Q Modulation

I/Q (In-phase/Quadrature) Modulation: Definition Two data streams are multiplied by a common carrier frequency, but

at phase offsets of 0 degrees (cosine) and 90 degrees (sine)

Data Stream #1 Q

Data Stream #2 I

90o

SUM

cos (wt)

I cos(wt)

- Q sin(wt)

+1

-1

+1

-1


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QPSK (Quadrature Phase Shift Keying) is a phase modulation algorithm.

In this, phase of the carrier wave is modulated to encode bits of digital information in each

phase change. QPSK refers to PSK with 4 states. With half that number of states, you will have BPSK

(Binary Phased Shift Keying). With twice the number of states as QPSK, you will have 8PSK.

The Quad in QPSK refers to four phases in which a carrier is sent in QPSK: 45, 135, 225,

and 315 degrees.

Quadrature Phase Shift Keying

16QAM Modulation
http://www.tech-faq.com/binary.htmlhttp://www.tech-faq.com/8psk.htmlhttp://www.tech-faq.com/8psk.htmlhttp://www.tech-faq.com/binary.html


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16QAM Modulation

16QAM allows for twice the peak data rate

compared to QPSK Constellation diagram for 16QAM:

1 Modulation Symbol represents 4 data bits

Modulation efficiency = 4 bits/symbol

I

Q

64QAM Modulation


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64QAM Modulation

64QAM peak data rate is 50% higher in

comparison to 16QAM Constellation diagram for 64QAM:

1 Modulation Symbol represents 6 data bits

Modulation efficiency = 6 bits/symbol

I

Q


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Multiple Access Technology

Multiple Access Techniques


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Multiple Access Techniques

Multiple Access Achieved by dividing the available radio frequency

spectrum, so that multiple users can be given access at the same time.

FDMA - Frequency Division Multiple Access

( e.g.: GSM each Frequency channel is 200KHz)

TDMA - Time Division Multiple Access

( e.g.: GSM each frequency channel is divided into 8 timeslots)

CDMA - Code Division Multiple Access

(e.g.: IS95- Each User data is coded with a unique code)


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Transmission Technique

Transmission


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DuplexSimplex

two-way

Transmission

Fig. 2 (TM5108-02AEN01GLA01 Introduction to GSM, 9)

Duplex Technique


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Duplex Technique

FDD - Frequency Division Duplex

(In GSM the up link and down link of a user is separated by 45MHz )

TDD - Time Division Duplex

(the up link and down link of a user will be at the same frequency

but at different Time )



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G - 1/2/3/4 G

G refers to the different generations ofmobile devices.

First generation (1G) cell phones were analog devices.

Second generation (2G) devices were digital, and

Third Generation (3G) allows for voice, data and advanced services.


First Generation Limitations


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No Roaming

Only Speech

Supplementary services not available

No security

Second Generation - 2G


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Digital systems

Leverage technology to increase capacity Speech compression; digital signal processing

Utilize/extend Intelligent Network concepts

Improve fraud prevention

Add new services

There are a wide diversity of 2G systems

IS-54/ IS-136 North American TDMA; PDC (Japan)

iDEN

IS-95 CDMA (cdmaOne)

GSM

Second Generation-2G


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GSM

Global System for Mobile Communications

GSM is the most popular standard for mobile phonesworldwide used by 2.2 billion people on over 210 networks.*

Indian Operators= Airtel, Vodafone, BSNL etc

iDEN

Integrated Digital Enhanced NetworkA second generation (2G) mobile telecommunications standard

developed entirely by Motorola.

CDMA

Code Division Multiple AccessA second generation (2G) standard for mobile phones

working on different technologies then GSM

Indian Operators=Tata, Reliance, MTS, Virgin

Second Generation 2G

Current Telecom Market


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Current Telecom Market

Moving Ahead


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Moving Ahead

3G Vision


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Universal global roaming Multimedia (voice, data & video)

Increased data rates

Up to 2 Mbps

Increased capacity (more spectrally efficient)

IP architecture

Migration To 3G


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CDMA

GSM

TDMA

PHS(IP-Based)

64Kbps

GPRS

115Kbps

CDMA 1xRTT

144 Kbps

EDGE

384Kbps

cdma20001X-EV-DV

Over 2.4 Mbps

W-CDMA

(UMTS)

Up to 2Mbps

2G 2.5G

2.75G 3G

1992 - 2000+2001+

2003+

1G

1984 - 1996+

2003 - 2004+

TACS

NMT

AMPS

GSM/

GPRS

(Overlay)115 Kbps

9.6 Kbps

9.6 Kbps

14.4 Kbps/ 64 Kbps

9.6 Kbps

PDC

Analog Voice

Digital Voice

Packet Data

IntermediateMultimedia

Multimedia

PHS

TD-SCDMA

2 Mbps?

9.6 Kbps

iDEN

(Overlay)

iDEN

Source: U.S. Bancorp Piper Jaffray

International Standardization


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ITU (International Telecommunication Union)

Radio standards and spectrum

IMT-2000

ITUs umbrella name for 3G which stands forInternational Mobile Telecommunications 2000

National and regional standards bodies are collaboratingin 3G partnership projects

ARIB (Japan), TIA (North America), TTA (South Korea),TTC (Japan), CWTS (China). T1 (North America), ETSI(Europe)

3G Partnership Projects (3GPP & 3GPP2)

Focused on evolution of access and core networks

3GPP Releases


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S. No.

3GPP

Releases Feature

DL

Throughput

UL

Throughput

DL

Modulation

UL

Modulation Remarks

1 Rel 99 UMTS 2 Mbps 384 Kbps QPSK BPSK

2 Rel 4 UMTS

Introduction of MSS,

MGW in Core Network

3 Rel 5 HSDPA 14.4 Mbps 384 Kbps

16 QAM,

QPSK BPSK Scheduling of Codes

4 Rel 6 HSUPA 14.4 Mbps 5.76 Mbps

16 QAM,

QPSK Dual BPSK

5 Rel 7 IMS 28 Mbps 11 Mbps

HSPA+

6 Rel 8 LTE 100 Mbps 42 Mbps Fourth Generation


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Radio Wave Propagation

Understanding


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Isotropic RF Source

A point source that radiates RF energy uniformly in all directions(I.e.: in the shape of a sphere)

Theoretical only: does not physically exist.

Has a power gain of unity I.e. 0dBi.

Effective Radiated Power (ERP) Has a power gain of unity i.e. 0dBi

The radiated power from a half-wave dipole.

A lossless half-wave dipole antenna has a power gain of 0dBd or

2.14dBi.

Effective Isotropic Radiated Power (EIRP)

The radiated power from an isotropic source

EIRP = ERP + 2.14 dB

Basic Definitions


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Basic Definitions


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deciBel (dB)

dB is a relative unit of measurement used to describe power gain or loss.

The dB value is calculated by taking the log of the ratio of the measured or

calculated power (P2) with respect to a reference power (P1). This result

is then multiplied by 10 to obtain the value in dB.

dB = 10 * log10(P1/P2)

The powers P1 ad P2 must be in the same units. If the units are not

compatible, then they should be transformed.

Equal power corresponds to 0dB.

A factor of 2 corresponds to 3dB

dB Conversion


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Calculations in dB (deciBel)

Logarithmic scale

Always with respect to a reference

dBW = dB above Watt

dBm = dB above mWatt

dBi = dB above isotropic

dBd = dB above dipole

dBmV/m= dB above mV/m

Rule-of-thumb:

+3dB = factor 2

+7 dB = factor 5

+10 dB = factor 10

-30 dBm = 1 mW

-20 dBm = 10 mW-10 dBm = 100 mW

-7 dBm = 200 mW

-3 dBm = 500 mW

0 dBm = 1 mW+3 dBm = 2 mW

+7 dBm = 5 mW

+10 dBm = 10 mW

+13 dBm = 20 mW

+20 dBm = 100mW+30 dBm = 1 W

+40 dBm = 10W

+50 dBm = 100W


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Radio Wave Propagation

Path Loss


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Propagation Mechanisms


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Reflection Occurs when a wave impinges upon a smooth surface.

Dimensions of the surface are large relative to . Reflections occur from the surface of the earth and from buildings and

walls.

Diffraction (Shadowing)

Occurs when the path is blocked by an object with large dimensions relativeto and sharp irregularities (edges).

Secondary wavelets propagate into the shadowed region.

Diffraction gives rise to bending of waves around the obstacle.

Scattering Occurs when a wave impinges upon an object with dimensions on the order

of or less, causing the reflected energy to spread out or scatter in many

directions.

Small objects such as street lights, signs, & leaves cause scattering

Multipath


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Multiple Waves Create Multipath

Due to propagation mechanisms, multiple waves arrive at the receiverSometimes this includes a direct Line-of-Sight (LOS) signal

Documents

Part 1 Nw Introduction