Advanced Wireless and Mobile Computing Networks
(CSC544)
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Lecture 1 – Introduction
Dr. Sarmad Ahmed Shaikh
Email: sarmad.ahmed107@gmail.com
Sindh Madressatul Islam University (SMIU), Karachi
Spring-2022

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Course Objectives
To familiarize students to
 State-of-the-art wireless networks and their fundamental backend
– Cellular concept
 Relevant techniques for data transmission in wireless channels
– Fading channel models, digital modulation techniques, etc
– The performance in fading channels of digital modulation, antenna diversity
techniques, and multicarrier modulation techniques
 Radio Localization
– Traditional vs Massive Antenna Array

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 Instructor: Dr. Sarmad Ahmed Shaikh
 Text book:
– T. Rappaport, Wireless communications: Principles and practice, 2001
– J. G. Proakis, Digital Communications, McGraw-Hill, NewYork, 2001
– G. T. Stüber, Principles of mobile communications, KAP, 2001
 Class material
– Slides and class activities
 Grading:
– Midterm 20%
– Final 40%
– Homeworks 10%
– Quizzes 10%
– Project and presentation 15%
– Class Participation 5%
Course Information

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Course Contents
 Review of the cellular communication concept
 Baseband representation of a digital modulation system
 Mobile wireless channel: fading and its statistics
 Performance analysis of digital modulation in fading channels
 Antenna diversity techniques and performance
 Spread spectrum systems: DS-CDMA, multiple access interference,
rake receiver

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 Multicarrier modulation: OFDM and FMT
 GPS and radio localization
 Localization algorithms in EM lens assisted massive MIMO

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Project
 With the project, students will learn all necessary steps on how to
build a wireless communication system from the idea phase to the
final design and characterization phase.
 Team
– 2 students per team
 Submission of proposal
– 3rd class of the course
 Deliverable
– All project components i.e., coding, graphs, results
– Report (A-Z) in the form of IEEE-paper format
– Final presentation

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About the Classes
 You’re welcome to ask questions.
– You can interrupt me at any time.
– Please don’t disturb others in the class.
 Our responsibility is to facilitate you to learn.
– You have to make the effort.
 Spend time reviewing lecture notes afterwards.
 If you have a question on the lecture material after a class, then
– Look up a book! Be resourceful.
– Try to work it out yourself.
– Ask me during the problem class or one of scheduled times of availability.

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Introduction

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What’s Communications?
 Communication involves the transfer of information from one
point to another.
– Wired (Public Telephony)
– Wireless (mobile phone)
 Three basic elements
– Transmitter: converts message into a form suitable for transmission
– Channel: the physical medium, introduces distortion, noise, interference
– Receiver: reconstruct a recognizable form of the message

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Communication Channel
 The channel is central to operation of a communication system
– Linear (e.g., mobile radio) or nonlinear (e.g., satellite)
– Time invariant (e.g., fiber) or time varying (e.g., mobile radio)
 The information-carrying capacity of a communication system is
proportional to the channel bandwidth
 Pursuit for wider bandwidth
– Copper wire: 1 MHz
– Coaxial cable: 100 MHz
– Microwave: GHz
– Optical fiber: THz
• Uses light as the signal carrier
• Highest capacity among all practical signals

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Noise in Communications
 Unavoidable presence of noise in the channel
– Noise refers to unwanted waves that disturb communications
– Signal is contaminated by noise along the path
 External noise: interference from nearby channels, human made
noise, natural noise...
 Internal noise: thermal noise, random emission... in electronic
devices
 Noise is one of the basic factors that set limits on communications.
 A widely used metric is the signal-to-noise (power) ratio (SNR)
𝑆𝑁𝑅 =
𝑆𝑖𝑔𝑛𝑎𝑙 𝑃𝑜𝑤𝑒𝑟
𝑁𝑜𝑖𝑠𝑒 𝑃𝑜𝑤𝑒𝑟

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Transmitter and Receiver
 The transmitter modifies the message signal into a form suitable
for transmission over the channel
 This modification often involves modulation
– Moving the signal to a high-frequency carrier (up-conversion) and varying
some parameter of the carrier wave
– Analog: AM, FM, PM
– Digital: ASK, FSK, PSK (SK: shift keying)
 The receiver recreates the original message by demodulation
– Recovery is not exact due to noise/distortion
– The resulting degradation is influenced by the type of modulation
 Design of analog communication is conceptually simple
 Digital communication is more efficient and reliable; design is
more sophisticated

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Objectives of System Design
 Two primary resources in communications
– Transmitted power (should be green)
– Channel bandwidth (very expensive in the commercial market)
 In certain scenarios, one resource may be more important than
the other
– Power limited (e.g. deep-space communication)
– Bandwidth limited (e.g. telephone circuit)
 Objectives of a communication system design
– The message is delivered both efficiently and reliably, subject to certain
design constraints: power, bandwidth, and cost.
– Efficiency is usually measured by the amount of messages sent in unit
power, unit time and unit bandwidth.
– Reliability is expressed in terms of SNR or probability of error.

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Wireless Communication
What is Wireless Communication (Wirl Comm)?
 Transmitting and Receiving data and voice/video using
electromagnetic waves in open space
– The information from sender to receiver is carried over a well defined radio
frequency band (channel)
– Each channel has a fixed frequency bandwidth and capacity (bit-rate)
– Different channels can be used to transmit information in parallel and
independently

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Simple Example
 Assume a spectrum of 120 KHz is allocated over a base frequency
for communication between station A and B
 Each channel occupies 40KHz
– Not so simple in real world – no sharp cut offs.
– Receiver has a filter, which would determine the cutoff frequency
– In real life, a lot of frequency overlap takes place. Use “Guard Bands”

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Frequency spectrum allocation for the U.S. cellular radio service. Identically
labeled channels in the two bands form a forward and reverse channel pair
used for duplex communication between the base station and mobile. Note
that the forward and reverse channels in each pair are separated by 45 MHz.

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Block Diagram of a General Wirl Comm System
Carrier
Signal
Modulator Amplifier
Impedance
Matching
Network
Modulating
Signal
Transmitter Antenna
LO
RF Amplifier Mixer
IF filter and
Amplifier
Demodulator
Display
device/
Speaker
Antenna Receiver

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Types of Wirl Comm
 Mobile
– Cellular Phones (GSM/CDMA/UMTS)
 Portable
– IEEE 802.11 a/b/g (WiFi)
 Fixed
– IEEE 802.16 (Wireless MAN)

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Major Mobile Radio Standards

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Typical Frequencies
 FM Radio ~ 88MHz
 TV Broadcast ~200MHz
 GSM Phone ~900/1800 MHz
 GPS ~1.2GHz
 Bluetooth ~2.4GHz
 WiFi ~2.4GHz
 2.4GHz is not the highest frequency, there are equipment using
higher frequencies, i.e., X-band radar, millimeter wave comm
– 2.4 GHz is free band, not requiring license
– i.e., ISM (Industrial, scientific, medical) band

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Electromagnetic Spectrum

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Honeycomb

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Cellular Mobile Phone Network
 A large area is partitioned into cells
 Frequency reuse to maximize capacity
A cellular system. The towers represent base stations (BS) which provide
radio access between mobile users and the mobile switching center (MSC).

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History of Communications
Antonio Meucci, 1871

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 1983: AMPS (Advanced Mobile Phone System) released using the
800-900 MHz band. 30 kHz bandwidth for each channel. AMPS is
the first standardized cellular service in the world!
D. Ring, R. Young, 1947
R. Frenkiel, J. Engel, P. Porter,
1967
M. Cooper, 1973

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 1992: World’s first commercial SMS was sent
 2003: Subscribership in the wireless industry surpasses 150
million.
 2009: Cellular subscribers in Pakistan exceeds 90 million
 2021: Cellular subscribers in Pakistan exceeds 189 million (source:
PTA)

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 According to the research firm IHS Markit, the number of
smartphones went from four billion in 2016 to more than six
billion by 2020.
 Also, QualComm, in one report, expected that over 60 times
growth in mobile data traffic is going to be seen from 2013 to 2024
to reach 136 billion Gigabytes monthly global mobile data traffic in
2024, and 75% of this traffic is from multimedia creation and
consumption.
 All these numbers show the high load that 5G will face in the next
few years.

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Growth of Mobile Communications
 1G: analog communications
– AMPS, voice
 2G: digital communications
– GSM, voice
– IS-95
 3G: CDMA networks
– WCDMA, digital data
– CDMA2000
– TD-SCDMA
 4G: data rate up to
1 Gbps (giga bits per second)
– Pre-4G technologies: WiMax, 3G LTE
 5G: Coming soon with data rates in 10s to 100s Gbps

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But Why Wirl ?
 Freedom from Wires!
– No cost of installing wires or rewiring
– No bunches of wires running here and there
– Auto or “Magical” instantaneous communication without physical
connection!
 Global Coverage
– Communication can reach where wiring is infeasible or costly
• rural areas, battle fields, vehicles, outer space (Sattellites)
 Human desire running billions of dollars industry !!

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 Stay Connected
– Roaming allows flexibility to stay connected anywhere anytime
– Rapidly growing market attests to public need for mobility and
uninterrupted access
 Flexibility
– Services reach you wherever you go (Mobility). E.g. you don’t have to go to
lab to check email
– Connect to multiple devices simultaneously
 Increasing dependence on telecommunication services for
business and personal reasons
 Consumers and businesses willing to pay for it!
 “Stay connected – anywhere, anytime” is driving the industry

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Wi-Fi
 Wi-Fi connects “local” computers (usually within 100m range)

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IEEE 802.11 Wi-Fi Standard
 802.11b
– Standard for 2.4GHz (unlicensed) ISM band
– 1.6-10 Mbps, 500 ft range
 802.11a
– Standard for 5GHz band
– 20-70 Mbps, variable range
– Similar to HiperLAN in Europe
 802.11g
– Standard in 2.4 GHz and 5 GHz bands
– Speeds up to 54 Mbps, based on orthogonal frequency division multiplexing
(OFDM)
 802.11n
– Data rates up to 600 Mbps
– Use multi-input multi-output (MIMO)

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Satellite/Space Communication
 Satellite communication
– Cover very large areas
– Optimized for one-way transmission
• Radio (DAB) and movie (SatTV) broadcasting
– Two-way systems
• The only choice for remote-area and maritime communications
• Propagation delay (0.25 s) is uncomfortable in voice communications
 Space communication
– Missions to Moon, Mars, …
– Long distance, weak signals
– High-gain antennas
– Powerful error-control coding

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An example of next-generation location-based
communication system.
Future Wireless Networks
 Ubiquitous Communication Among People and Devices
– Wireless Internet access
– Nth generation Cellular
– Ad Hoc Networks
– Sensor Networks
– Wireless Entertainment
– Smart Homes/Grids
– Automated Highways
– All this and more…

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Challenges
Hard Delay Constraints and Hard Energy Constraints
 Efficient Hardware
– Low Power Transmitters and Receivers
– Low Power Signal Processing Tools
• Battery and Radiation
 Efficient use of finite radio spectrum
– Costly spectrum
– Cellular frequency reuse, medium access control protocols etc
 Integrated Services
– Voice, data, multimedia – all over single network
– Service differentiation, priorities, resource sharing

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 Multimedia Requirements
Voice Data Video
Delay < 100 ms - < 100 ms
Packet Loss < 1% 0 < 1%
Data Rate 8-32 Kbps 1-100 Mbps 1 – 20 Mbps
Traffic Continuous Bursty Continuous
One size doesn’t fit all!

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 Network support for user mobility
– Location identification
– Handover
 Maintaining Quality of Service (QoS) over unreliable links
 Connectivity and coverage (internetworking)
 Cost effective

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 Fading from Multipath
 Probability of data corruption
– Wireless is not robust, error detecting techniques are required
 Security mechanisms
– Privacy, authentications
– For every lock, there is a key
– Ever evolving

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Re-emphasize: Wirless Vs Mobile
 Wireless doesn’t necessarily mean mobile
 Wireless system may be:
– Fixed: Metropolitan Area Network
– Portable: Wireless interaction between laptops
– Mobile: Mobile Phone

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Project Options
 Simulation of localization algorithms i.e., MUSIC/ESPRIT/Sum-
Difference patterns in massive antenna array where as antenna
array size is 50 by 50 elements and modulation technique is
OFDM.
 Literature survey in the form of IEEE journal paper on
special/advanced topics i.e.,
– AESA radar system design and implementation
– EM lens antenna arrays for radio localization
– Wireless Communication in 5G and IoT Sensors Systems
– 6G Communication Systems – Futuristic Technology
– Fabrication techniques of EM lens antenna arrays
– Or your idea any !!!!