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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

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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

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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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Communication Systems

Basic Comm. Model

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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

-

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

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Communication Systems

Theoretical Aspects of Data Transmission

Sine and Cosine Wave Amplitude, Frequency, Phase

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1 - 1 0Chapter 1: Introduction Dr. Sheng-Chou Lin

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)

109

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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

-

Refraction, Total reflection, Multimode, Singlemode- Several gigabits/sec for a long distance (22 mile)

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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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Communication Systems

Telephone Network

Circuit Switching

- Space-division switching

-

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

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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)