2. EE 320
Outline
Instructor information
Motivation to study communication systems
Course descriptions and textbooks
What you will study from this course
Objectives
Coverage and schedule
Homework, projects, and exams
Other policies
Reasons to be my students
Background and Preview
3. EE 320
Motivations
Recent Development
– Satellite Communications
– Telecommunication: Internet boom at the end of last decade
– Wireless Communication: next boom? iPhone
Job Market
– Probably one of most easy and high paid majors recently
– Intel changes to wireless,
– Qualcom, Broadcom, TI, Marvell, Cypress
Research Potential
– One to one communication has less room to go, but
multiuser communication is still an open issue.
– Wimax, 3G, next generation WLAN
4. EE 320
Course Descriptions
What is the communication system?
What are the major types?
Analog or Digital
Satellite, Fiber, Wireless…
What are the theorems?
What are the major components?
How is the information transmitted?
What are the current industrial standards?
What are the state-of-art research?
Can I find a job by studying this course?
Can I find research topics?
5. EE 320
Textbook and Software
Require textbook:
Simon Haykin, Communication Systems, 4th edition, John
Wiley and Sons, Inc.
Require Software: MATLAB
http://www.mathworks.com/ or type helpwin in Matlab environment
Recommended readings
Digital communications: J. Proakis, Digital Communications
Random process: G.R. Grimmett and D.R. Stirzaker, Probability and
Random Processes
Estimation and detection: H.V. Poor, An introduction to Signal
Detection and Estimation
Information theory: T. M. Cover and J. A. Thomas, Elements of
Information Theory
Error correct coding: P.Sweeney, Error Control Coding
7. EE 320
Homework, Project, and Exam
Homework
2 questions per week for undergraduate, 3~4 for graduate
Projects: simple MATLAB programs
AM/FM Modulation
BPSK Modulation (undergraduate), BPSK/MQAM (graduate)
USRP2/GnuRadio if the hardware will be ready.
Exams
Three independent exams
Votes for the percentages for homework, projects, and exams
Participations
Attendance and Feedback
Quiz if the attendance is low
8. EE 320
Teaching Styles
Slides plus black board
Slides can convey more information in an organized way
Blackboard is better for equations and prevents you from
not coming.
Course Website
Print handouts with 3 slides per page before you come
Homework assignment and solutions
Project descriptions and preliminary codes
Feedback
Too fast, too slow
Presentation, Writing, English, …
11. Communication Process
Message Signal
Symbol
Encoding
Transmission
Decoding
Re-creation
Broadcast
Point to Point
12. Telecommunication
Telegraph
Fixed line telephone
Cable
Wired networks
Internet
Fiber communications
Communication bus inside computers to communicate
between CPU and memory
13. Wireless Communications
Satellite
TV
Cordless phone
Cellular phone
Wireless LAN, WIFI
Wireless MAN, WIMAX
Bluetooth
Ultra Wide Band
Wireless Laser
Microwave
GPS
Ad hoc/Sensor Networks
14. Analog or Digital
Common Misunderstanding: Any transmitted signals are
ANALOG. NO DIGITAL SIGNAL CAN BE TRANSMITTED
Analog Message: continuous in amplitude and over time
– AM, FM for voice sound
– Traditional TV for analog video
– First generation cellular phone (analog mode)
– Record player
Digital message: 0 or 1, or discrete value
– VCD, DVD
– 2G/3G cellular phone
– Data on your disk
– Your grade
Digital age: why digital communication will prevail
15. Source Coder
Examples
– Digital camera: encoder;
TV/computer: decoder
– Camcorder
– Phone
– Read the book
Theorem
– How much information is
measured by Entropy
– More randomness, high
entropy and more information
16. Channel, Bandwidth, Spectrum
Bandwidth: the number of bits per second is proportional to B
http://www.ntia.doc.gov/osmhome/allochrt.pdf
17. Power, Channel, Noise
Transmit power
– Constrained by device, battery, health issue, etc.
Channel responses to different frequency and different time
– Satellite: almost flat over frequency, change slightly over time
– Cable or line: response very different over frequency, change
slightly over time.
– Fiber: perfect
– Wireless: worst. Multipath reflection causes fluctuation in
frequency response. Doppler shift causes fluctuation over time
Noise and interference
– AWGN: Additive White Gaussian noise
– Interferences: power line, microwave, other users (CDMA phone)
18. Shannon Capacity
Shannon Theory
– It establishes that given a noisy channel with information capacity C and
information transmitted at a rate R, then if R<C, there exists a coding
technique which allows the probability of error at the receiver to be made
arbitrarily small. This means that theoretically, it is possible to transmit
information without error up to a limit, C.
– The converse is also important. If R>C, the probability of error at the
receiver increases without bound as the rate is increased. So no useful
information can be transmitted beyond the channel capacity. The theorem
does not address the rare situation in which rate and capacity are equal.
Shannon Capacity
s
bit
SNR
B
C /
)
1
(
log2
19. Modulation
Process of varying a carrier signal
in order to use that signal to
convey information
– Carrier signal can transmit far
away, but information cannot
– Modem: amplitude, phase, and
frequency
– Analog: AM, amplitude, FM,
frequency, Vestigial sideband
modulation, TV
– Digital: mapping digital
information to different
constellation: Frequency-shift
key (FSK)
20. Example
Figure 10
Modulation over carrier fc
s(t)=Accos(2fct) for symbol 1; -Accos(2fct) for symbol 0
Transmission from channel
x(t)=s(t)+w(t)
Correlator
Decoding
– If the correlator output yT is greater than 0, the receiver output
symbol 1; otherwise it outputs symbol 0.
0
,
5
.
0
1
,
5
.
0
)
2
cos(
)
(
0
symbol
for
w
A
symbol
for
w
A
dt
t
f
t
x
y
T
c
T
c
T
c
T
21. Channel Coding
Purpose
– Deliberately add redundancy to the transmitted information, so
that if the error occurs, the receiver can either detect or correct it.
Source-channel separation theorem
– If the delay is not an issue, the source coder and channel coder can
be designed separately, i.e. the source coder tries to pack the
information as hard as possible and the channel coder tries to
protect the packet information.
Popular coder
– Linear block code
– Cyclic codes (CRC)
– Convolutional code (Viterbi, Qualcom)
– LDPC codes, Turbo code, 0.1 dB to Channel Capacity
22. Quality of a Link (service, QoS)
Mean Square Error
Signal to noise ratio (SNR)
– Bit error rate
– Frame error rate
– Packet drop rate
– Peak SNR (PSNR)
– SINR/SNIR: signal to noise plus interference ratio
Human factor
N
i
i
i X
X
N
MSE
1
2
|
ˆ
|
1
2
2
G
P
P tx
rec
23. Communication Networks
Connection of 2 or more distinct (possibly dissimilar) networks.
Requires some kind of network device to facilitate the
connection.
Internet
Net A Net B
26. TCP/IP Architecture
• TCP/IP is the de facto
global data
communications standard.
• It has a lean 3-layer
protocol stack that can be
mapped to five of the
seven in the OSI model.
• TCP/IP can be used with
any type of network, even
different types of networks
within a single session.
27. Summary
Course Descriptions
Communication System Structure
– Basic Block Diagram
– Typical Communication systems
– Analog or Digital
– Entropy to Measure the Quantity of Information
– Channels
– Shannon Capacity
– Spectrum Allocation
– Modulation
– Communication Networks
