Electrical Communications Systems ECE.09.331 Spring 2010 - PowerPoint PPT Presentation

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Electrical Communications Systems ECE.09.331 Spring 2010

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Electrical Communications Systems ECE.09.331 Spring 2010 Lecture 12b April 14, 2010 Shreekanth Mandayam ECE Department Rowan University http://engineering.rowan.edu ... – PowerPoint PPT presentation

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Title: Electrical Communications Systems ECE.09.331 Spring 2010


1
Electrical Communications SystemsECE.09.331
Spring 2010
Lecture 12bApril 14, 2010
  • Shreekanth Mandayam
  • ECE Department
  • Rowan University
  • http//engineering.rowan.edu/shreek/spring10/ecom
    ms/

2
Plan
  • Digital Bandpass Communications
  • Quadrature Phase Shift Keying (QPSK)
  • M-ary PSK and M-ary QAM
  • Observing Digital Bandpass Signals
  • Constellation diagrams
  • Eye Diagrams
  • Data Processing Data Communications
  • Communications Networks
  • Packet Switched Networks
  • OSI 7-Layer Protocol Architecture
  • TCP-IP Protocol Architecture

3
ECOMMS Topics
4
Digital Communications Transceiver
Anti- aliasing Filter
Data Encryption Encoder
Error Control Encoder
Channel/ Line Encoder
Source Encoder
Sampling
Quantization
Modulator
MUX
ADC
Analog i/p
CODEC
MODEM
Multiple access channel
Analog o/p
Data Encryption Decoder
Error Control Decoder
Audio Amp
Source Decoder
Reconstruction/ DAC
Equalization / Decision Circuits
Demod-ulator
DEMUX
5
Quadrature Phase Shift Keying(QPSK)
IQ Diagram
s(t) Ac cos(2pfct f(t))
Q
3p/4
01
11
10
f(t)
p/4
00
p/4
t
I
10
-p/4
11
01
00
-3p/4
6
M-ary Phase Shift Keying(M-ary PSK)
Q
I
Octophase I-Q Constellation
7
M-ary Quadrature Amplitude Modulation(M-ary-QAM)
Q
I
16 QAM I-Q Constellation
8
Different ways of looking at a digitally
modulated signal
9
Time Frequency Domain View
Reproduced from http//www.tm.agilent.com/tmo/Not
es/pdf/5965-7160E.pdf
10
Frequency Power View
Reproduced from http//www.tm.agilent.com/tmo/Not
es/pdf/5965-7160E.pdf
11
I-Q Constellation Diagram
Matlab Demo qpsk.m
Reproduced from http//www.tm.agilent.com/tmo/Not
es/pdf/5965-7160E.pdf
12
Eye Diagram
Matlab gtgteyediagram
Reproduced from http//www.tm.agilent.com/tmo/Not
es/pdf/5965-7160E.pdf
13
Digital Communications Transceiver
Anti- aliasing Filter
Data Encryption Encoder
Error Control Encoder
Channel/ Line Encoder
Source Encoder
Sampling
Quantization
Modulator
MUX
ADC
Analog i/p
CODEC
MODEM
Multiple access channel
Analog o/p
Data Encryption Decoder
Error Control Decoder
Audio Amp
Source Decoder
Reconstruction/ DAC
Equalization / Decision Circuits
Demod-ulator
DEMUX
14
Digital Communication Paradigms
Recall
Circuit Switching
Sync bits
Packet Switching
Header bits
15
Communications Networking
16
A 3-Layer Protocol Architecture
Files and file transfer commands
File transfer application
Communications service module
Network access module
File transfer application
Communications service module
Network access module
Comm related messages
Comm network
Computer 1
Computer 2
17
ISO OSI 7-Layer Model
Please Do Not Touch Steves Pet Alligator
18
TCP-IP Protocol Architecture
19
TCP-IP Operation Example
Port or Service access point (SAP)
Logical connection (TCP)
Global network address
Subnetwork attachment point address
Logical connection
Router J
IP IP
NAP1 NAP2
Network 1
Network 2
20
TCP-IP Protocol Packet
21
IP Header
0 4 8
16 19
31
Version IHL Type of Service Total Length Total Length
Identification Identification Identification Flags Fragment Offset
Time to Live Time to Live Protocol Header Checksum Header Checksum
Source Address Source Address Source Address Source Address Source Address
Destination Address Destination Address Destination Address Destination Address Destination Address
Options Padding Options Padding Options Padding Options Padding Options Padding
20 octets
22
TCP Header
0 4 10
16
31
Source Port Source Port Source Port Source Port Source Port Source Port Source Port Source Port Destination Port
Sequence Number Sequence Number Sequence Number Sequence Number Sequence Number Sequence Number Sequence Number Sequence Number Sequence Number
Acknowledgement Number Acknowledgement Number Acknowledgement Number Acknowledgement Number Acknowledgement Number Acknowledgement Number Acknowledgement Number Acknowledgement Number Acknowledgement Number
Data Offset Reserved URG ACK PSH RST SYN FIN Window
Checksum Checksum Checksum Checksum Checksum Checksum Checksum Checksum Urgent Pointer
Options Padding Options Padding Options Padding Options Padding Options Padding Options Padding Options Padding Options Padding Options Padding
20 octets
23
Summary
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