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Communication Systems
COMMUNICATION ENGINEERING
1 - 1Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Personal Profile
: Ph. D. University of Texas at Arlington, Texas, USA.
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Bell Northern Research (BNR) TX, USA - NORTEL Networks, TX, USA -
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Wireless, Mobile Communications ( )
Radar System Design ( )
Fiber Optics Communications ( )
Statistical Signal Processing ( )
Microwave Theory and Engineering ( )
Semiconductor Devices and Manufacture ( )
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1 - 2Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Outline
General introduction to communication systems:
Messages and signal, Elements of communication, System, Modulation,
Fundamental limitations.
Signal, Spectra, and Filters
Fourier Transforms, Convolution Correlation and Spectral Density
Random Signals and Noise
Baseband Communication, Signal distortion in Transmission, Analog anddigital transmission
Linear Modulation
Modulator, Transmitters Detection and Receivers for AM, DSB, SSB, andVSB
Exponential Modulation
FM and PM spectral Analysis, Transmitters and Receivers
1 - 3Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Grading
1. Attendance (Not Mandatory) 10%
-20 for each absence
2. Quizzes 30%
1 hour, Twice in a semester
3. Midterm Exam 25%
4. Final Test 35%
2 hour, inclass/proctored
Close book, Close notes
5. MATLAB Project 10%
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1 - 4Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Communication Systems
1. Mathematical Modeling andAnalysis
Signals and Systems
Random Signal and noise
2. Analog Communication
Linear Modulation (DSB, SSB,AM, VSB)
Angle Modulation (PM, FM)
Frequency Modulation
3. Pulsed and Digital
Communications Pulse Modulation (PAM, PTM,
PCM)
Digital Modulation (ASK, PSK,FSK, QAM, MSK)
4. Information Theory andCoding
Channel Capacity
Source coding
Channel Coding
5. Applications
Wireless Communications
Mobile radio
Fiber optics
Satellite Communications
Computer and Telcom Networks
1 - 5Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Block Diagram of Comm. System
Modulation
Easy for radiation
Reduce noise and
Interference
Channel
Assignment
Multiplexing
Equipment limitations
Other Functions
Filtering
Amplification and Coupling
Message
Analog
Digital
Emag-wave
Guided
Wave
Optical
Coding
Demodulation
Extract desired
message
SNR ratio
Bit Error Rate
Loudspeaker
Tape Recorders PC
Meters
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1 - 6Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Basic Comm. Model
1 - 7Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Types of Communications
Simplex (one-way): Radio/TV Broadcast
Duplex (Two-way)
- Full-duplex: Telephone/Cellular Phone
- Half-duplex: Telegraph comm.
- Ponint to Point link: Terrestrial comm.
- Multipoints: Satellite, Cellular phone
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1 - 8Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Transmission
Analog and Digital
- Analog(continuous): Voice, video, picture
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Digital(Discrete): Characters, symbols
Modern (modulator-demodulator): Digital
signal be sent in the form of analog signal.
Files, Data, and Signals
- Information (User data): Files
- DataSignal
Asynchronous and Synchronous
begin End
1 - 9Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Theoretical Aspects of Data Transmission
Sine and Cosine Wave Amplitude, Frequency, Phase
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Communication Systems
Fourier Series, Bandwidth and SNR
Channel, passband, bandwidth
Thermal Noise
InterferenceCrosstalk
1 - 1 1Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Transmission Media (1)
Twisted Pair
- 5~6 km for analog signal, 2~3 km for
digital signal
- Limited in distance, data rate, bandwidth
(narrow band).
- Twisting reduces low-frequency
interference.- Local Loop (hone central office)
Coaxial Cables
- Better Shielding
- Longer distance
- Higher transmission Speed
- 1~1.5 gigabits/sec ( ) of digital
transmission for 1 mile (1.6km)
- 300 MHz and higher (450MHz) for
analog transmission. (Broadband
BW > 4k Hz)
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1 - 1 2Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Transmission Media (2)
Optical Fiber
- Light Source (Laser, LED), Fiber, Photo Detector
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Refraction, Total reflection, Multimode, Singlemode- Several gigabits/sec for a long distance (22 mile)
1 - 1 3Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Transmission Media (3)
Terrestrial Microwave
- Line-of-sight (LOS), Multipath fading
- 2 - 40GHz, Higher freq.Higher BW, data
rate
- Voice, Television/Cable, building links
- Tall towers (100m),
Large horns, Dish
antennas (10 feet)
- repeaters spaced 80km
- 4G, 6G, 11G
Long Haul
- 12GTV, Cable
- 22Gbuildings
Satellite Microwave
- Microwave Relay station
(Transponder)
- uplink, downlink, 35,800km
- Point-to-point Link
- Broadcast Link
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1 - 1 4Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Telephone Network
Circuit Switching
- Space-division switching
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Digital switch: bit stream, CCS Analog link: Phone-Switch
Digital link: Switch-Switch (improve quality
using digital repeater)
- Trunks: lines connecting switches
DS-1,..., DS-4, SONET
- Data Comm. over telephone NetworkModem
- Local Center office: nearest end office
(1-10km), (972)8810405
- Toll Office
- Intermediate Switch: Country to country
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Communication Systems
Telephone Call Scenario
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Communication Systems
Switching Systems
Circuit Switching: Telephone Network
- A path is established for a conversation
Package Switch: Message transmission- Message is fragmented into smaller chunks (package)
- Package is routed along different paths, reassembled at
the receiving end
- Rules for network operationsProtocols
1 - 1 7Chapter 1: Introduction Dr. Sheng-Chou Lin
Communication Systems
Layering and Protocols
Layers
- Network origination
Protocol
- Agreements bet. communicating parties
- Layer, Entities, Interface
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Communication Systems
Spectra (Spectrum Analyzer)