1. Electrical Communications Systems ECE.09.433 Spring 2019
Lecture 10a April 2, 2019
Shreekanth Mandayam
ECE Department
Rowan University

2. Plan Digital Baseband Communications Pulse Amplitude Modulation
Sampling
Quantization
TDM Standards
T1 (DS-1) Line
North American TDMA Hierarchy
Line Encoding
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
Sampling
Channel/
Line
Encoder
Quantization
Source
Encoder
MUX
Modulator
ADC
Analog i/p
CODEC
MODEM
Multiple access channel
Analog o/p
Data
Encryption
Decoder
Error
Control
Decoder
Audio
Amp
Reconstruction/
DAC
Source
Decoder
Equalization /
Decision
Circuits
DEMUX
Demod-ulator

5. Pulse Code Modulation (PCM)
Standard for all digital communications
Analog
Signal
Sample &
Hold
Digital
Bitstream
Quantize
Encode
PAM
PCM

6. Pulse Amplitude Modulation: Flat-top Sampling
-0.5
0.5 1
1.5 2
2.5 3
3.5 4 -6 -4 -2 6 8
time
Analog
PAM
Matlab Demo: pam.m

7. Quantization Uniform Non-Uniform m-Law A-Law Mid-rise Mid-tread
Matlab Demos:
quantization.m
pcm.m
Mid-rise
Mid-tread
Mid-rise
Mid-tread
Matlab Demos:
companding.m
pcm_mucompand.m
pcm_mucompand2.m
pcm_acompand.m
pcm_acompand2.m

8. Digital Communications Transceiver
Anti-
aliasing
Filter
Data
Encryption
Encoder
Error
Control
Encoder
Sampling
Channel/
Line
Encoder
Quantization
Source
Encoder
Modulator
MUX
ADC
Analog i/p
CODEC
MODEM
Multiple access channel
Analog o/p
Data
Encryption
Decoder
Error
Control
Decoder
Audio
Amp
Reconstruction/
DAC
Source
Decoder
Equalization /
Decision
Circuits
DEMUX
Demod-ulator

9. Time Division Multiplexing
Message 1
Quantize
&
Encode
Message 2
Channel
Message N
Message 1
LPF
Decode
Message 2
LPF
Message N
LPF

10. T1-Line TDM Format 1 Frame = (24 Channels + F) = 125 ms Channel 1 1 87 6 5 4 3 2
Channel 2 1 8 7 6 5 4 3 2
Channel 24 1 8 7 6 5 4 3 2 F
193 bits
Frame Sync Bit
Even Frames:
Odd Frames:
Every Sixth Frame
LSB (8th bit) is a Signaling bit
Bipolar R-Z Line Encoding

11. North American TDMA Hierarchy
64 kbps
1 VF
DS-0 1 1 7
DS-2
6.312 Mbps
96 VF
3rd M U X 1 6
DS-3
Mbps
672 VF
4th M U X 1 2
DS-4
Mbps
4032 VF
5th M U X 1 4
DS-1
1.544 Mbps
24 VF
2nd M U X
1st M U X 24
DS-5
Mbps
8064 VF
Figure 3-40, p. 214 in Couch
Table 3-8, p. 215 in Couch
Table 3-9, p. 216 in Couch

12. Digital Communications Transceiver
Anti-
aliasing
Filter
Data
Encryption
Encoder
Error
Control
Encoder
Sampling
Channel/
Line
Encoder
Quantization
Source
Encoder
MUX
Modulator
ADC
Analog i/p
CODEC
MODEM
Multiple access channel
Analog o/p
Data
Encryption
Decoder
Error
Control
Decoder
Audio
Amp
Reconstruction/
DAC
Source
Decoder
Equalization /
Decision
Circuits
DEMUX
Demod-ulator

13. Line Encoding
Couch, p. 170
Couch, p. 165

14. Digital Communications Transceiver
Anti-
aliasing
Filter
Data
Encryption
Encoder
Error
Control
Encoder
Sampling
Channel/
Line
Encoder
Quantization
Source
Encoder
Modulator
MUX
ADC
Analog i/p
CODEC
MODEM
Multiple access channel
Analog o/p
Data
Encryption
Decoder
Error
Control
Decoder
Audio
Amp
Reconstruction/
DAC
Source
Decoder
Equalization /
Decision
Circuits
DEMUX
Demod-ulator

15. Digital Communication Paradigms
Recall
Digital Communication Paradigms
Multiplexer
Message 2
Message 3
Message 1 1 2 3 S
Demultiplexer
Circuit Switching
Sync bits
Packet Switching
Header
bits
Packetizing
Message 2
Message 3
Message 1 1 H 2 3
Depacket-izing

16. Communications Networking
Router
Step 1:
Step 2:
Step 3:
……..
Protocol
Sender
Medium
Receiver
Message

17. A 3-Layer Protocol Architecture
File transfer application
Communications service module
Network access module
Files and file transfer commands
File transfer application
Communications service module
Network access module
Comm related messages
Comm network
Computer 1
Computer 2

18. ISO OSI 7-Layer Model 7 Application 6 5 Presentation 4 3 Session 2 1
Physical
Data Link
Network
Presentation
Session
Transport
Application 7 6 5 4 3 2 1
Please Do Not Touch Steve’s Pet Alligator

19. TCP-IP Protocol Architecture
Physical
Network Access
Internet
Transport
(host-to-host)
Application
TCP-IP
Application
Presentation
Session
Transport
Network
Data Link
Physical
OSI
Hardware
Firmware
Software
Operating
system
User
space

20. TCP-IP Operation Example
Network access protocol #1
Physical IP
TCP
Host A
App X
App Y
Network access protocol #2
Physical IP
TCP
Host B
App X
App Y
Port or
Service access point (SAP)
Logical connection (TCP)
Global network address
Subnetwork attachment point address
Logical connection
Router J IP
NAP1
NAP2
Network 1
Network 2

21. TCP-IP Protocol Packet
TCP header
IP header
Network header
User Data
Application
Byte Stream
TCP
Segment IP
Datagram
Network
Level
Packet

22. IP Header 0 4 8 16 19 31 20 octets Version IHL Type of Service
Version
IHL
Type of Service
Total Length
Identification
Flags
Fragment Offset
Time to Live
Protocol
Header Checksum
Source Address
Destination Address
Options + Padding
20 octets

23. Acknowledgement Number
TCP Header
Source Port
Destination Port
Sequence Number
Acknowledgement Number
Data Offset
Reserved
URG
ACK
PSH
RST
SYN
FIN
Window
Checksum
Urgent Pointer
Options + Padding
20 octets

24. Summary