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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/7/31/2019 Part 1 Nw Introduction
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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/Radiolinja7/31/2019 Part 1 Nw Introduction
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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
Modulation Techniques
Baseband Signal
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Modulation Techniques
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.html7/31/2019 Part 1 Nw Introduction
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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 )
Wireless Generations
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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.
Wireless Generations
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