EE320 Telecommunications Engineering Topic 1: Propagation and Noise

EE320 Telecommunications Engineering Topic 1: Propagation and Noise
James K Beard, Ph. D. E&A 349 9/21/2018 Week 1

Essentials Text: Simon Haykin and Michael Moher, Modern Wireless Communications Prerequisites Analog and Digital Communication: EE300 Analog and Digital Communication Laboratory: EE301 SystemView Web Site URL Content includes slides for EE320 and EE521 SystemView page A few links Office Hours E&A 349 Hours Tuesday afternoons 3:00 PM to 4:30 PM MWF 10:30 AM to 11:30 AM 9/21/2018 Week 1

Topic 1 Subjects Course objectives Course Summary and Topics
Essential Technologies Introduction to Communications History Concepts Propagation Free space Local propagation effects Noise and interference Thermal noise Man-made noise Link calculations 9/21/2018 Week 1

Course Objectives, Summary and Topics
EE320 Topic 1 Course Objectives, Summary and Topics 9/21/2018 Week 1

Course Objectives Objectives
Identify Concepts of pass band coherent and non-coherent modulation systems Societal and global issues in communication regulatory affairs Apply Principles Angle modulation and demodulation to send and receive information Random processes to analyze the source and magnitude of error in information reception Signal analysis to optimal and efficient modulation systems Information theory to improve the performance of digital communication systems See Temple course web site for more information 9/21/2018 Week 1

Course Summary Fourteen weeks of classes
Two in-progress exams, one final exam In-progress on 5th and 9th weeks, 20% of grade Final on fifteenth week, 40% of grade Individually assigned project Assigned in fifth week Execute your project in SystemView 40% of grade Deductions from final grade 0.5% for each unexcused absence 1% for each missed 10 minute Pop Quiz response 9/21/2018 Week 1

Course Topics (1 of 2) Propagation and Noise Modulation Coding FDMA
Pulse shading, power spectra, and FDMA Bit Error Rate Coding Information theory, and convolutional codes Maximum likelihood decoding Noise performance TDMA 9/21/2018 Week 1

Course Topics (2 of 2) Spread spectrum Wireless architectures CDMA
Direct-sequence modulation Spreading codes and orthogonal spreading factors Gold codes Code synchronization Power control Frequency hopping and spread spectrum Wireless architectures 9/21/2018 Week 1

Introduction to Communications
EE320 Topic 1 Introduction to Communications 9/21/2018 Week 1

Essential Technologies
Probability and Statistics Behavior of channel over time Description and behavior of noise Signals and systems Time and frequency domain signal and chanel characterization Prediction and modeling of communications Coding, modulation, and demodulation 9/21/2018 Week 1

Introduction History of telecommunications Communications overview
Layers Concepts The conceptual layers Physical layer, transmitter/receiver and channel Data link layer, our primary focus Netework layer, infrastructure 9/21/2018 Week 1

History 1864 – Maxwell predicted radio waves
1887 – Hertz demonstrated radio waves 1897 – Lodge demonstrated wireless communications 1901 – Marconi demonstrated transatlantic communications 1903 – DeForest demonstrated first vacuum tube amplifier 1906 – Fessenden started first AM radio station 1927 – First TV broadcasts 1947 – Microwave relay from Boston to NYC 1947 – Bell Labs announced the transistor 1955 – TI announced production silicon transistors 1958 – First satellite voice channel 1981 – First cell phone system, in Scandinavia 1988 – First digital cell phone system in Europe 9/21/2018 Week 1

Communications Overview
Conceptual layers Physical layer – the channel Data link layer – input and output Network layer – routing Concepts Given the channel, or bandwidth Determine the coding and multiplexing, or tuning or time multiplexing and codes Route the data through the nodes to the receiver 9/21/2018 Week 1

The Conceptual Layers The physical layer is the channel
The data link layer is the information input and output The network layer routes the input and output data Together they determine The data rate The error rate The conditions for success of communications Usage of the communications 9/21/2018 Week 1

Examples Systems Physical layer: Modem, transmitter, medium
Public switched telephone network Internet Physical layer: Modem, transmitter, medium Data link layer: EDAC, grid, multiplexing Network layer: grid routing, flow control 9/21/2018 Week 1

The Physical Layer Transmitter Channel Receiver Information Source
Sink Transmitter, channel, receiver Channel may be Open RF Beamed RF Cable or fiber optic Other such as satellite links Any combination of these 9/21/2018 Week 1

The Data Link Layer Highest conceptual level is the multiple access strategy Allows multiple users to share a channel Frequency division multiple access (sub-channels) Time division multiple access (time slots) Code division multiple access (spread spectrum) Space division multiple access (beams) Objective Maximize number of users for a fixed spectrum FDMA/TDMA/CDMA/SDMA can be layered 9/21/2018 Week 1

The Network Layer Determines the routing of the information
Selection of path through available nodes Selection of open band Selection of unused code or time slot Selection of unused beam Selection of path through multiple-node network Quality of service (QoS) Keep a channel open for new calls Plan reserves for rollover for mobile netowrks 9/21/2018 Week 1

Functional Summary The layers The engineer’s perspective
The physical layer is the transmitter-channel-receiver The data link layer is the information encoding and decoding The network layer is the routing through the physical layer The engineer’s perspective The physical layer is defines the available channel The data link layer is the radio or user set The network layer is the routing infrastructure 9/21/2018 Week 1

Discussion What are the differences in the physical layer between
Cable such as telephone and Ethernet Wireless Discuss the time variation in The medium The data path 9/21/2018 Week 1

Propagation and the RF link budget
EE320 Topic 1 Propagation and the RF link budget 9/21/2018 Week 1

Propagation and Noise Text Chapter 2 Simple equations
2.2, Free-Space Propagation 2.6, Local Propagation Effects 2.8, Noise and Interference 2.9, Link Calculations Simple equations Signal power in the receiver Noise in the receiver Characterize the channel 9/21/2018 Week 1

Free-Space Propagation
Definition Line of sight Point to point No reflections or scattering Everything is simple and linear Modeling Transmitter, antennas, and gain Simple electromagnetic propagation 9/21/2018 Week 1

Concepts Transmitting power The receiving antenna as a capture area
The isotropic (omnidirectional) antenna and directional antennas with gain Spreading loss Simple equation for received power 9/21/2018 Week 1

Transmit Antenna Power density R Transmitter Power 9/21/2018 Week 1

Receive Antenna Receive effective area Incident power density
9/21/2018 Week 1

Received Power Combining the equations
We will derive the more common form We need the gain equations 9/21/2018 Week 1

Directivity and Gain What’s the difference? Conventionally speaking
Directivity is the radiated power density in a specific direction Gain is the directivity with the losses included Conventionally speaking Usually we speak of the maximum peak gain Losses are the ohmic or heating losses 9/21/2018 Week 1

Transmit Effective Area
The total power radiated is The transmit directivity can be posed as 9/21/2018 Week 1

Receive Antenna Gain The average effective transmit area is
From electromagnetic theory, this is always 9/21/2018 Week 1

The Isotropic Antenna An idealized theoretical concept
Based on a unipole concept Antennas are coupling to free space from voltage and current Antenna design maximizes energy transfer All antennas are circuits (loops), dipoles, ground surfaces, or some combination of these A unipole cannot exist in nature But, it is useful as a theoretical concept 9/21/2018 Week 1

Small Antennas Small dipoles and loaded whips Essentially isotropic
Used on Cell phones Pagers Portable RF equipment where size is more important than gain Theoretical Minimum effective antenna area is 9/21/2018 Week 1

Antenna Gain Given as peak power ratio
Power received relative to that of an isotropic (small, omnidirectional) antenna A function of direction from which the signal is coming – varies as Ae This completes our derivation 9/21/2018 Week 1

Antenna Efficiency Applicability The antenna efficiency is defined as
Reflectors, planar arrays, arrays of dipoles or loops The antenna efficiency is defined as Efficiency is always less than 1 Causes for lower efficiency are Non-uniform illumination Spill-over of reflectors Edge effects and losses on reflection and in horns 9/21/2018 Week 1

Summary: Free Space Modeling
An isotropic transmitter produces a power density at the receiver Power received at an antenna of effective area Ae in Watts Polarization is considered later 9/21/2018 Week 1

Local Propagation Effects
Two types of mobile radio Portable – stationary during communicatoins Mobile – moving during communications Fading Slow – refraction changes in the RF path Fast – path changes as radio moves Doppler Fast fading – the picket fence 9/21/2018 Week 1

Basic Physics of Fading
The path length is a large number of wavelengths Received power nearly always arrives through more than one path The amplitudes and phases of the received signals are all different The sum of the received signals exhibits amplitude changes characterized as fading 9/21/2018 Week 1

Rayleigh Fading The Rayleigh distribution
Is the distribution of the amplitude of a complex Gaussian random variable – or Gaussian RF noise Mathematical statisticians call the distribution of the squared amplitude chi-square with two degrees of freedom This is an effective result for received signal power when the received signal is from a large number of paths – a scattered signal Time variation produces fading with amplitude having a Rayleigh distribution 9/21/2018 Week 1

Rician Fading The Rician distribution
Results from the amplitude of a constant plus complex Gaussian noise Mathematical statisticians call the distribution of the squared amplitude the non-central chi-square distribution This is the effective result when a direct path signal is added to a scattered signal 9/21/2018 Week 1

Doppler A change of path length results in a corresponding change in the number of wavelengths between transmitter and receiver The frequency change is the rate of path length change in wavelengths 9/21/2018 Week 1

Numerical Example Air traffic control Aircraft velocity
Frequency about 128 MHz Wavelength about 2.34 meters Aircraft velocity About 500 kph or 310 mph Or, 140 meters per second Doppler frequency shift Maximum of 59 Hz Decreased by cosine of angle between velocity vector and the line of sight 9/21/2018 Week 1

Noise and Interference
Thermal noise in the receiver Background noise Earth’s radiation Man-made Each element of a receiver adds noise 9/21/2018 Week 1

Thermal Noise Equilibrium of RF energy with thermal energy provides a noise background with a power spectral density of Quantum theory shows that it rolls off after 1000 GHz 9/21/2018 Week 1

Earth’s Radiation Black body radiation
Noise temperature usually considered to be 290 K Noise temperature can be higher Sunlit areas Backlit clouds Large hot surfaces such as parking lots 9/21/2018 Week 1

Man-Made Noise Sources include Most significant below 100 MHz
Power lines Broadcasting and other communications, radar HID (mercury, xenon, neon) lights Car and truck engine ignition systems Spurious emissions – motor brushes, arcing… Most significant below 100 MHz About 40 dB over Earth radiation 9/21/2018 Week 1

Noise Figure Noise figure is Antenna noise figure is basis
The system noise level referred back to the receiver input Divided by baseline or reference noise from a power spectral density of N0 Antenna noise figure is basis System or element noise temperature is 270 K times the noise figure Each element of the receiver increases the overall noise figure 9/21/2018 Week 1

Antenna Noise Figure Inputs are Earth’s radiation and other ambient
Plumbing and resistive losses often increase the antenna noise figure in the real world 9/21/2018 Week 1

Cascaded Elements System noise temperature for two cascaded elements is Including the antenna and more elements 9/21/2018 Week 1

Link Calculations The communications equation Satellite systems
Signal from transmitter to receiver Noise in receiver Summarized as SNR in receiver Satellite systems Simple free-space calculations Very long range Terrestial systems Path is more complex – fading, reflection losses… Ranges much shorter 9/21/2018 Week 1

The Communications Equation
9/21/2018 Week 1

Grouping of Terms Communications engineering groups terms in the communications equation Carrier to noise density ratio is received signal power to noise power density ratio Others Often done in tables with quantities in dB 9/21/2018 Week 1

Local Propagation Effects
Two types of mobile radio Portable – stationary during communicatoins Mobile – moving during communications Fading Slow – refraction changes in the RF path Fast – path changes as radio moves Doppler Fast fading – the picket fence 9/21/2018 Week 1

Basic Physics of Fading
The path length is a large number of wavelengths Received power nearly always arrives through more than one path The amplitudes and phases of the received signals are all different The sum of the received signals exhibits amplitude changes characterized as fading 9/21/2018 Week 1

Rayleigh Fading The Rayleigh distribution
Is the distribution of the amplitude of a complex Gaussian random variable – or Gaussian RF noise Mathematical statisticians call the distribution of the squared amplitude chi-square with two degrees of freedom This is an effective result for received signal power when the received signal is from a large number of paths – a scattered signal Time variation produces fading with amplitude having a Rayleigh distribution 9/21/2018 Week 1

Rician Fading The Rician distribution
Results from the amplitude of a constant plus complex Gaussian noise Mathematical statisticians call the distribution of the squared amplitude the non-central chi-square distribution This is the effective result when a direct path signal is added to a scattered signal 9/21/2018 Week 1

Doppler A change of path length results in a corresponding change in the number of wavelengths between transmitter and receiver The frequency change is the rate of path length change in wavelengths 9/21/2018 Week 1

Numerical Example Air traffic control Aircraft velocity
Frequency about 128 MHz Wavelength about 2.34 meters Aircraft velocity About 500 kph or 310 mph Or, 140 meters per second Doppler frequency shift Maximum of 59 Hz Decreased by cosine of angle between velocity vector and the line of sight 9/21/2018 Week 1

Log Normal Fading Example 2.20 on pages 80 and 81 Problem 2.22
Text 2.13, Summary Summary of Chapter 2, Propagation and Noise Pages 94-95 9/21/2018 Week 1

See Spreadsheets Example 2.20 Problem 2.20 According to example
Details explained Problem 2.20 Modify paramters as given Availabilty: Gaussian PDF(0.675) = 0.75 9/21/2018 Week 1

Example 2.20 9/21/2018 Week 1

Problem 2.22 9/21/2018 Week 1

Spreadsheet Format Flexibility Tables similar to Table 2.3, Table 2.5
Built-in functions provide dB, Gaussian PDF Flexibility Easily modified by changing one or more parameters Example is our example and problem Example_2_20_page_80.xls 9/21/2018 Week 1

Summary Overview of telecommunications Result Conceptual layers
Free space link computations Noise and fading The link equations Result Completion of first-pass overview Next time: Modulation and FDMA 9/21/2018 Week 1

Text and Assignment SystemView User's Manual, Elanix, Inc
Look at using SystemView in the problems for Chapter 2 Assignment: Read text Chapter 3, sections 3.1, 3.2, 3.3, 3.4.1, 3.7.3/4/5, 3.8, 3.12 Antenna references Lo and Lee, Antenna Handbook, Vol. 1, ISBN R.S. Elliot, Antenna Theory and Design, IEEE classic reissue, ISBN 9/21/2018 Week 1

Summary Course summary Overview of communication
Organization and grading Topics Result Design concepts for communication networks Execute a term project in SystemView Overview of communication Physical layer: Transmitter, channel, receiver Data link layer: FDMA/TDMA/CDMA/SDMA Network layer: routing, QoS Free space propagation Introduction to antenna concepts 9/21/2018 Week 1

Summary Overview of communication, continued Result
Introduction to antenna concepts, continued Antenna gain and directivity Noise and fading The link equations Result Completion of first-pass overview Next Topic: Modulation and FDMA 9/21/2018 Week 1

Text and Assignment Text Assignment: Read Text Look at TUARC
Simon Haykin and Michael Moher, Modern Wireles Communicatinons ISBN SystemView User's Manual, Elanix, Inc Assignment: Read Text Chapter 1 Chapter 2,2.2, 2.6, 2.8, 2.9 Look at TUARC K3TU, websites 9/21/2018 Week 1

Text and Assignment SystemView User's Manual, Elanix, Inc
Look at using SystemView in the problems for Chapter 2 Assignment: Read text Chapter 3, sections 3.1, 3.2, 3.3, 3.4.1, 3.7.3/4/5, 3.8, 3.12 Books Lo and Lee, Antenna Handbook, Vol. 1, ISBN R.S. Elliot, Antenna Theory and Design, IEEE classic reissue, ISBN 9/21/2018 Week 1

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