Personal Mobile Communication

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Personal Mobile Communication

• Aspects of Telecommunication Network Management

Michael Feramez M.Feramez_at_latrobe.edu.au www.ee.la
trobe.edu.au/mf
Lecture 6
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Topics

• Telecommunication Management Network
• Defining Performance Objectives
• Transmission Performance
• Switching Performance
• Quality of Speech

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Introduction

• Along with the GSM network functional units (MS,
  BSS, MSC, HLR, VLR), there is a need to operate a
  network management system for support and admin.
• In telecommunication business, this system is
  needed for performing day-t-day Operations,
  Administration, Maintenance and Provisioning
  (AOMP) functions.
• The system enables service providers to monitor
  the health of the network, add and remove
  equipment, test software and hardware, diagnose
  problems, and bill subscribers for the services.

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Telecommunication Management Network (TMN)

• Fault Management,
• Configuration management,
• Account Management,
• Performance Management, and
• Security Management

5
TMN Background

• The AOMP functions in GSM are based on the
  concept of the Telecommunication Management
  Network (TMN).
• TMN was standardised within ITU-T/ETSI/CEPT
  almost simultaneously with GSM.
• ITU-T M. series recommendations M.20 and M.30
  serve as the framework for TMN.
• TMN defines an open system that enables
  platform-independent multivendor environment for
  management of all components of a network.

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TMN / Telecommunication Network Relationship
Operational System
Operational System
Operational System
Data Communication Network
TMN
Workstation
Exchange
Transmission System
Exchange
Telecommunication Network
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Logical Layered Architecture
Business Management Layer BML
Service Management Layer SML
Network Management Layer NML
Element Management Layer EML
Network Element Layer
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TMN Architecture

• Functional architecture model
• Defines the functional components of TMN and the
  interfaces between these components
• Physical architecture model
• Identifies the physical components of TMN and
  connectivity between these components
• Information architecture model
• Provides an object-oriented methodology to model
  telecommunication networks and services and the
  management functions

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Functional Architecture
g
manager
WSF
f
WSF
f
x
MF
OSF
MF
OSF
q
q
NEF
QAF
NEF
QAF
Workstation Function (WSF) Operation System
Function (OSF) Network Element Function
(NEF) Mediation Function (MF) Q Adapter Function
(QAF)
m
Non-TMN System
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Performance Management
Network Performance Requirement
are Requirements met ?
Proactive Maintenance Actions
Continuous In-service Performance Monitoring
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Defining Telecommunication

• The Oxford Dictionary defines Telecommunication
  as a means of communication over a distance.
• Communication is in turn defined as the exchange
  of Information between Sources and Sinks.
• Information can be Voice, Data, Image, or Video.

Source
Sink
Transmission Channel
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Communication Phases
Disengagement Phase
Access Phase
Information Transfer Phase
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Communication Phases

• Access Phase
• Initiate the communications process e.g. setup a
  voice call or data session.
• Information Transfer Phase
• Transfer information from the source user to the
  destination user.
• Disengagement Phase
• Terminate the communication process e.g. hangup
  or logoff.

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Communication Phases and Performance Criteria
Framework
Performance Criteria
Speed
Accuracy
Dependability
Communication Phase
Access
Primary Performance Parameters
Information Transfer
Disengagement
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Overall Framework forPerformance Parameters
Performance Category
User-oriented Quality-of Service (QoS) Perspective
Network Performance Perspective
Communications Phase
Access and Disengagement
Traffic
Accessibility
Integrity/ Suitability
Information Transfer
Transmission
Retainability/ Robustness
Availability
All
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Relevant Telecommunications Services

• Voice
• Plain Ordinary Telephone Service
• Teleconferencing/hands-free telephony
• High-quality telephony
• Voice response applications
• Sound programming
• Data
• Private (or leased) lines
• Packet-switched
• Circuit-switched

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Relevant Telecommunications Services (Continue)

• Image
• Facsimile
• Broadcast television
• Videoconferencing
• Audio-graphic conferencing
• Videotext
• Video telephony
• Advanced/enhanced/improved television
• High-definition television (HDTV)
• High-resolution imaging

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Relevant Telecommunications Services (Continue)

• Signaling
• End-to-end user signaling
• Data base services
• Multimedia
• Combination of voice, data, and image services
  made possible by fast packet techniques (e.g.
  Asynchronous Transfer Mode (ATM)

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Defining Performance Objectives
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Voice Data Performance Requirements
Voice
High Bandwidth
Low Delay
Bulk Data
Interactive Data
High Integrity
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Defining Performance
Performance is a measure of how well a system
performs its intended functions. The performance
of telecommunication systems is viewed as

• User-Oriented Performance
• Network-Oriented Performance

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User-Oriented Performance
User-Oriented Performance is

• Directly experienced by, perceived by, or
  relevant to the user, irrespective of the network
  involved.
• Presents the highest level of consideration in a
  top-down approach to to determining network
  performance requirements.

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Defining Quality of Service
Quality of Service (QoS)
Service Operability
Service Accessibility
Service Support
Service Retainability
Service Integrity
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Quality of Service

• Ability to provide a service and assist in its
  use,
• Ability to easily use and successfully handle a
  service,
• Ability of a service to be obtained when
  requested,
• Ability of a service to be provided for a
  requested duration, and
• Ability to provide a service without excessive
  impairment.

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Telecommunication Network Functions

• Transmission
• Signalling
• Switching
• Management

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Transmission
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End-to-End Objectives
Network
CPE
CPE
End-to-End Objectives
CPE Customer Premises Equipment
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Transmission Links

• The transmission link between the Customer
  Premises Equipment (CPE) and the Switch (Exchange
  or Central Office) is often referred to as Local
  Loop or Customer Access Network (CAN).
• The transmission links between switches, or
  exchanges, normally referred to as trunks,
  bearers, or inter-exchange network.

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Transmission Media

• Open copper wire,
• Twisted Pair Cable,
• Coaxial Cable,
• Optical Fibre Cable, and
• Microwave (terrestrial satellite).

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Transmission Channel
Source
Sink
Tx
Rx
Transmission Channel
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Voice Impairments
Nature of Impairments
Transient
Continuous
Delay
Sidetone
Errors
Loss
Cross-talk
Interruptions
Noise
Interference
Echo
Distortion
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Transmission Impairments
The main transmission impairments are

• Bandwidth limitation,
• Attenuation (Loss),
• Delay and Echo,
• Distortion, and
• Noise (continuous and impulse).

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Crosstalk

• Crosstalk is undesired energy from one or more
  signals, unintentionally coupled from one or more
  disturbing circuits into a disturbed circuit
  where it is perceived.
• Can consist of intelligible or non-intelligible
  speech signals, or non-speech signals such as
  signalling tones or noise.

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Causes of Crosstalk

• Electromagnetic coupling between circuits,
• Non-Linearity in multiplexing and modulation
  systems,
• Erroneous Time-Slot Interchange in digital
  systems.

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Controlling Crosstalk

• Following an acceptable transmission planning
  practice.
• Shielding of conductors and equipment,
• Physical separation of conductors,
• Selecting the appropriate cables, and
• Controlling transmission signal levels.

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Multiplexing

• Frequency Division Multiplexing (Analogue)
• VF Channel (0.3 - 3.4 kHz)
• Group, Super-Group, Master-Group, Jumbo-Group
• Time Domain Multiplexing (Digital)
• Plesiochronous Digital Hierarchy
• Synchronous Digital Hierarchy

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Speech Compression

• Quantisation Distortion Unit
• Pulse Code Modulation (PCM 64 kbps)
• Adaptive Differential PCM (ADPCM 32 kbps)
• Other schemes (e.g. RPE-LPC 13 kbps)

ITU-T Recommendation G.711 Pulse Code Modulation
(PCM) of Voice Frequencies
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Digital Transmission Performance

• Loss (attenuation) is the basic quality measure
  for analogue transmission.
• Bit Error Ratio (BER) is the basic quality
  measure for digital transmission.
• Error performance objectives for international
  and national digital connections are given in
  ITU-T Recommendation G.821

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The Concept of Available Unavailable Time

• A period of Unavailable Time begins when BER in
  each second is worse than 1x10-3 for a period of
  Ten consecutive seconds. These Ten seconds are
  considered to be Unavailable Time.
• The period of Unavailable time terminates when
  the BER in each second is better than 1x10-3 for
  a period of Ten consecutive seconds. These Ten
  seconds are considered to be Available Time.

Ref. ITU-T G.821
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Interpretation of ITU-T Rec. G.821
Available Time
Unavailable Time
EFS E 0
ES E gt 1
SES E gt 64
DM E gt 4
92
8

• EFS Error Free Seconds
• ES Error Seconds (seconds intervals containing
  at least One error)
• SES Sever Error Seconds (seconds intervals
  containing more than 64 errors)
• DM Degraded Minutes (minutes intervals
  containing more than 4 errors)

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Jitter Wander

• Digital network impairments.
• Excessive Jitter and Wander can lead to
  transmission errors and short interruptions.
• Jitter can directly affect end user perceived
  performance for certain applications, such as
  video.

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Eye Pattern (Unimpaired)
1
0
Jitter Free Clock
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Eye Pattern (Impaired)
1
0
Jitter Clock
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National HRX
7,500 km
LE
TO
TO
LE
T
T
5,000 km
1,250 km
1,250 km
LE
Local Exchange
HRX Hypothetical Reference Connection
TO
Toll Office
International Switching Centre
ISC
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International HRX
27,000 km
International
National
National
LE
TO
ISC
ISC
TO
LE
T
T
25,000 km
1,250 km
1,250 km
2,500 km
2,500 km
20,000 km
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Signalling
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Signalling

• Alerting (ringing),
• Transmitting address information (telephone
  number of called party),
• Supervision (idle, busy, release guard),
• Transmitting information (dial tone, busy tone,
  recorded announcement, etc.).

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Signalling(Customer - Network)

• Loop Disconnect,
• Dual Tone Multi Frequency (DTMF), and
• D-Channel (ISDN).

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Signalling(Exchange - Exchange)

• Loop Disconnect
• E M
• 2E 2M
• Compelled Sequence MFC
• Common Channel Signalling (CCS 7)
• Channel Associated Signalling (CAS)
• D-Channel (ISDN)

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Common Channel Signalling
Voice/Data Trunks
Switching System Processor
Switching System Processor
CCS Data Trunks
CCS Signalling
CCS Signalling
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Switching
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Switching

• A telephone switching system consists of two
  major parts
• Control
• Switching Network
• Various switching systems have been designed and
  developed over the years
• Step-by-Step
• Crossbar
• Electronic switching systems

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Simplified Telephone Switch
Control
Switching Network
Lines (Inlets)
Lines (Outlets)
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Number of Trunks Limitation
2 x Trunks
Switch
Switch
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Grade of Service

• The probability of blockage on first attempt
  during busy hour is referred to as the Grade of
  Service (GoS).
• For example, the GoS for the busy hour could be
  0.005, or in other words, 5 calls in 1000 will
  not be successful at first attempt due to
  congestion.

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End-to-End Service Parameters

• Call Connectivity, and
• Transmission Quality.

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Call Connectivity

• Start Dial Signal Delay (Dial Tone),
• Post Dialling Delay, and
• Connection Setup Failure.

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Sidetone

• Electrical Sidetone
• user perception
• ASTIC (anti-sidetone induction coil)
• Acoustic Sidetone
• through the air
• through the telephone handset, and
• through the users head.

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Speech Quality
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Subjective Testing of Speech Quality

• Listening Tests
• Conversational Tests
• Test Conditions
• simulated impairments
• native test subjects

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Impairment Simulation
Play
Record
Impairment Simulation
Impaired Speech
Interface Filter
Source Speech
Filter Interface
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Listening Test
Interface Distribution
Impaired Speech
Native Subjects
Operator
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Five-Point Opinion Rating Scale
Opinion Numerical Proportion of Rating Weight
(i) Rating Pi
Excellent (E) 5 P5 Good (G) 4 P4 Fair
(F) 3 P3 Poor (P) 2 P2 Bad
(B) 1 P1
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Mean Opinion Score (MOS)
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Subjective Effect of Random Errors on 56 kbps
A-Law PCM Speech
BER ? 10-6 ? 10-5 ? 10-4 ? 10-3
Subjective Effect Not detectable Just
discernible on low level speech Annoying on low
level speech Serious over whole speech range
Ref. 1
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References

• 1. Gruber, John J.Transmission Performance of
  Evolving Telecommunications Networks, Artech
  House Inc., 1992.
• 2. AUSTEL, Australian Telecommunications
  Authority - Technical Standard 027, End-to-End
  Network Performance
• 3. Graham Chen, Qinzheng Kong, Integrated
  Telecommunications Management Solutions, IEEE
  Press