Telecom Systems

1
Telecom Systems

• Preface

• References
• Enslow, Preface

2
System
A collection of different things so related as
to produce a result greater than what its parts
could produce separately.
3
Technology ChangesFundamental Concepts Do Not
Change!
4
Important Dates in Telecommunications System
History

• DC Telegraph
• Bell Patent on Telephone granted
• Bell Telephone Co. formed
• Bell Telephone Co. sues American Speaking
  Telephone Co. for patent infringement
• Bell Telephone wins fight with Western Union over
  telephone patent
• First long-distance telephone line Boston
  Salem, MA
• Long distance telephone line Boston New York
• Carbon transmitter patented (Thomas A. Edison)
• Bell Telephone buys Western Electric (predecessor
  to Bell Labs)
• First wireless across water (Marconi, 8 miles
  across English channel)
• 1900-19 ATT President Theodore Vail reorganizes
  company into state and regional operations
  spanning the country. ATT is nationalized as a
  unit of U.S. Post Office, then returned to
  private status as a natural monopoly with an
  obligation to provide long-distance connections
  to all independent phone companies
• ATT acquires Western Union
• Clayton Antitrust Act ATT relinquishes Western
  Union stock
• Bell Telephone Laboratories formed
• ATT sued by U.S. Justice Department for alleged
  antitrust violations
• 1955 Consent decree settled 1949 antitrust suit

5
Important Dates in Telecommunications System
History (cont.)

• Digital Carrier systems (T1)
• 1960 Echo Satellite (NASA)
• Telstar Satellite (ATT)
• Packet Switching ARPANET
• Antitrust suit brought against ATT to dissolve
  Bell System
• 197? Ethernet
• Full-scale commercial cellular telephone approved
• 1974 Antitrust suit against ATT settled
  Breakup of the Bell System begins
• TAT-7 Atlantic cable laid
• 1984 Divestiture of the Bell System completed

6
The Key to Mastery,SystemsThinking
7
The Steps to Mastery

• Organize,
• Divide Conquer

8
Enslows Laws of Networking and Computing I.
There is no segment of business or technology
in which there are more misrepresentations made
in the name of marketing and sales than in
Networking and Computing.II. The principle
underlying cause for the perpetration of most of
these "falsehoods" is ignorance not
dishonesty.III. The mastery of a particular
subject in the field of computer systems is only
15 technology but 85 terminology.  Philip H.
Enslow Jr. 1962, 1977, 1986, 1989, 1990, 1994.
1998
9
Telecom Systems

• Chapter 1
• System Models

• References
• Enslow, Ch 1

10
SYSTEMS MODELS
WHY WE NEED SYSTEMS APPROACH GOALS AND PURPOSES
OF SYSTEM MODELS WHY BOTHER WITH MODELS
11
FEATURES OF A GOOD MODEL
THE MODEL SHOULD BE ACCURATE PRECISE
COMPLETE AN ABSTRACTION CONCISELY
DESCRIBABLE ROBUST UNDER USE
12
Basic Terminology

• Communication
• Telecommunication
• Traffic
• Service
• Facility
• Network
• Subnetwork
• System
• Subsystem
• Channel
• Information

13
The Communications Process ModelThe Basic Model
(BASIS FOR OTHER COMMUNICATIONS PROCESS MODELS)
WE MOVE SIGNALS SO THIS MODEL NOT OURS
XFER OF INFO,
INF IS MEANING OF
SIGNALS XFERED INFO
REMOVES UNCERTAINTY (HEADS OR TAILS) MEASURED IN
ONES AND ZEROs. COULD BE MEASURED IN FRACTIONS OF
BITS.
14
The Communications Process ModelThe Refined Model
ENCODING
DECODING
ANY DISTURBANCE
GOOD FOR INFORMATION TRANSFER USED EXTENSIVELY IN
INFO THEORY STUDIES
15
The Communications Service ModelThe Basic
Service Model
WE WISH TO FOCUS ON CHANNEL ITSELF
TOO HIGH LEVEL
PROVIDES SERVICE TO USERS (MOST IMPORTANT)
USED ALL TELECOMMUNICATIONS
16
TELECOMMUNICATION SYSTEM The Component
Functionality ModelThe Basic Model
MANUAL AUTOMATIC
MOVES ELECT SIGNALS
PROVIDES ELECTRICAL TERMINATION USER ACCESS
UTILIZATION
OUTSIDE TELECOM
HAS APPROX 68 BOXES
17
The Component Functionality ModelThe Complete
Model
Telecommunications
Subnetwork
CONTROL INTERACTIONS BETWEEN NETWORK, SERVICE
PROVIDED AND
Service
Service
Control
Control
User
User
18
Service Primitives
CONTROL INTERACTIONS BETWEEN NETWORK, SERVICE
PROVIDED AND USER REQUEST INDICATIONS RESPONSE CON
FIRMATIONS
19
The Component Functionality ModelThe Complete
Model
Switching
RESPOND,ORIGINATE, TRANSFER
Control
Control
Transport
ORIGINS OF SERVICE REQUEST
Access
RESPOND TO INCOMING CONTROL
End
End
ALERT TO TRAFFIC
User
User
CONTROL SHARED RESOURCES
20
The Open Systems Interconnection Reference Model
21
Application of Telecomm System Functional Model
to the Plain Old Telephone System
   
   


Figure 1 - 9 Application of
Figure 1 - 9 Application of
22
A Complete Telecommunication Example
Toll
Mux
Mux
Office
Trunk
Trunk
Loop
Loop
Mux
Mux
Central
Central
Loop
Mux
Office
Loop
Loop
Office
Mux
Mux
Trunk
Trunk
Access
X
X
Termin.
X
Transport
X
X
X
X
X
X
Switching
23
Application of Telecomm System Functional Model
to Radio Telecommunication Systems
24
Application of Telecomm System Functional Model
to an Ethernet Local Area Network System
25
Network Characteristics and Categories
Geographical Coverage Local Area Network
LAN Metropolitan Area Network MAN Wide Area
Network -- WAN

• Internal Mode of Operation
• Non-Switched
• Switched
• Combined

Form Delievered to User Type of Traffic Signal
Voice Digital Video Connection or
Connectionless
Topology Tree, Star, and Bus Ring/ Loop Mesh
26
Network Topologies
27
The Most Important Design Criteria of All
Telephone Systems is Delivery of Acceptable
Quality Voice Interconnection Service
28
The Component Functionality ModelInternetworking
with Integrated Functionality
Internetworking
Control Functions
Switching
are
Switching
Integrated
into the
Standard
Control
of the
Subnetworks
Control
Control
Control
Control
Transport
Transport
Termination
Termination
The user services
provided by the
and Access
and Access
two subnetworks
are identical
and directly
interconnectable.
Subnetwork A
Subnetwork B
End
End
User
User
The End-Users see
no Internetworking
and have
no visible or special interactions

with the
Internetworking Functions
29
The Component Functionality ModelInternetworking
with Visible Internetworking Functionality
Internet
Gateway
Switching
Switching
The
Internetworking
Control
Functions
Control
Control
Control
Control
Transport
Transport
Interface the
Standard
Control
of the
Subnetworks
Termination
Termination
and Access
and Access
Any differences
in the
user services
Subnetwork A
Subnetwork B
provided by the
two subnetworks
must be handled
by the
Internet Gateway
End
End
User
User
The End-Users see some or all aspects of
Internetworking
and have special interactions with the
Internetworking Functions

directly with the gateway and/or thropugh the
control interactions with the gateway
30
BREAK
31
Telecom Systems

• Chapter 2
• Transport and Transmission
• Functions and Operations

• References
• Enslow, Chapter 2

32
The Key to Mastery,SystemsThinking
33
The Steps to Mastery

• Organize,
• Divide Conquer

34
Transport is the overall or total collection of
all functions involved in moving signals from one
location to another.
35
A Generalized Transport System
Transport
Transmission
Transmission
Trans-
Trans-
Trans-
Transport
Transport
Media
Media
mission
mission
mission
Unit/
Unit/
Unit
Unit
Unit
Terminal
Terminal
36
A Generalized Transport System
Transport
Transmission
Transmission
Trans-
Trans-
Trans-
Transport
Transport
Media
Media
mission
mission
mission
Unit/
Unit/
Unit
Unit
Unit
Terminal
Terminal
Amplifier
Carrier
Multiplexer
Repeater
Terminal
Intermediate Terminal
37
Transport and Transmission

• Transport is the overall and total collection of
  all functions involved in moving signals from one
  location to another from one location to
  another.
• Transmission is the simple movement of signals
  from one point to another

38
Transmission ComponentFunctions

• Always Present
• Provide a Path
• Transform the signal
• Transmit the signal
• Receive the signal
• Transform the received signal
•  
• Sometimes Present
• Compensate for losses
• Compensate for distortion
• Control access
• Monitor quality
• Control quality

39
Transport ComponentFunctions

• Always Present
• Interfacing to transmission terminal
• Interfacing to transport user
•  
• Sometimes Present
• Multiplexing
• Control signal conversion
• Monitoring transmission quality Reporting
  transmission quality Error Control Quality of
  Service

40
General Concepts of CommunicationStep 1
Transfer of Signals
Source
Destination
Signals
41
General Concepts of CommunicationStep 2
Interpreting Signals to Obtain Messages
Source
Destination
Msgs
Msgs
Signals
Interpretation
Generation
of Signals
of Signals
Coordination of Signals
42
General Concepts of CommunicationStep 3
Interpreting Messages to Obtain Information
Source
Destination
Msgs
Info
Msgs
Info
Signals
Encoding
Interpretation
of Messages
of Messages
Interpretation
Generation
of Signals
of Signals
Coordination of Signals
Coordination of Messages
43
Characteristics of User Traffic

• Analog User Signals
• Sound Speech, Music
• Video
•  
• Digital
• Sound
• Data
• Video
• Remote sensing

44
Conversion of Sound Waves to Electrical Signals
45
Characteristics of Analog Signals

• Continuous with respect to value
• No discrete or instantaneous changes
• Can take on any value between limits
• Continuous with respect to time
• Value at every instant of time is of
  interest

46
Definition of Digital Signals

• Signal can assume only a finite set of discrete
  values
• And
• The signal has meaning only at discrete points in
  time.

47
Idealized Digital Waveforms
3
2
1
Allowable
0
Signal
Values
-1
-2
-3
48
Real Digital Signals - Characteristics
3
2
1
Allowable
0
Signal
Values
-1
-2
-3
49
A signal is assumed to be Digitalif and only if
it is interpreted to assume only afinite number
of discrete valuesandhas significanceonly at
discrete instants of time
50
Noise

• Definition of noise
• Distortion of the original signal
•  
• Effects of the noise
• Distortion
• Additive
•  
• Nature of the noise
• Deterministic
• Random

51
Sine WaveThe Fundamental Signal
52
Time Representation of a Sine Wave
time
53
Phasor Representation of a Sine Wave
54
Frequency Representation of a Sine Wave
time
0
1/f
1
f
frequency
1
55
Fourier Theorem

• Any periodic time function (that satisfies some
  simple conditions) can be expressed as the sum of
  the values of a collection of sine waves if the
  appropriate frequency, amplitude, and phases. For
  periodic time functions, the frequencies of the
  components present in the collection will be
  integer multiples or harmonics of the fundamental
  frequency of the waveform of the periodic
  function.

56
Adding Two Simple Tones
57
Adding Three Simple Tones
58
Effects of Noise and DistortionAmplitude
Distortion
59
Effects of Noise and DistortionPhase Distortion
60
Constant Signals