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Leadership in the 4th Industrial Revolution

Dr. David Molapo and Linda Khumalo

Leaders: Adapt or Disappear.

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This book is dedicated to all the leaders bold enough to face the digital challenge and aware of their need for digital empowerment and readiness for the 4th Industrial Revolution, in order to face new tech driven challenges every day, knowingly and unknowingly. May you find strength and guidance in this book on how to tackle these

challenges and prosper in the 4th Industrial Revolution.

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Leadership in the 4th Industrial Revolution © Dr. David Molapo and Linda Khumalo 2018

Dr David Molapo and Linda Khumalo

PO Box 30552, Kyalami, 1684

Gauteng, South Africa

_______________________

First Edition Published, 2018

ISBN: 978-0-620-70501-1

©Dr David Molapo and Linda Khumalo

All rights reserved; no part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic,

mechanical, photocopying, recording, or otherwise without either the prior written permission of the Author.

Typesetting by

Sollywood Publications, a division of Sollywood Investments

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TABLE OF CONTENTS PAGE

1. Introduction ___________________________________________ 8

Part 1: Leadership Evolution __________________________________ 15

2. Leadership Evolution ___________________________________ 15

Part 2: Telecommunications __________________________________ 23

3. Introduction to Telecommunications _______________________ 23

4 Terrestrial Telecommunications ___________________________ 32

5 Telecommunications Networks ___________________________ 35

6 Switching and Transmission Systems _______________________ 41

7 Wireless Communications _______________________________ 56

8 Satellite Communications ________________________________ 63

9 Telecommunications Network Management _________________ 70

10 The Regulations of Telecommunications ____________________ 73

Part 3: Broadcasting ________________________________________ 83

11 Introduction to Broadcasting _____________________________ 83

12 Telecommunications and Broadcasting _____________________ 89

Part 4: Information Technology ________________________________ 94

13 Introduction to Information Technology ____________________ 94

14 Information Technology Management in companies__________ 101

15 Telecommunications and Information Technology ___________ 102

Part 5: The Internet ________________________________________ 106

16 Introduction to the Internet _____________________________ 106

17 Convergence of Technologies ____________________________ 112

19 Business in Digital Technology ___________________________ 122

20 Digital Technology for Entrepreneurship ___________________ 130

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21 International Digital Technology Organisations ______________ 131

22 Information Gathering on Digital Technology _______________ 138

23 The Regulation of Digital Technology ______________________ 141

24 Regional Developments and Trends in Digital Technology _____ 143

25 Introduction to the 4th Industrial Revolution ________________ 154

26 The Internet of Things __________________________________ 163

27 Introduction to Cyber Security ___________________________ 165

28 PEST Analysis of Digital Technology and the 4th Industrial Revolution ___________________________________________________ 180

29 Economic Participation in the Digital Technology and the 4th Industrial Revolution _______________________________________ 187

30 Small and Medium Enterprises ___________________________ 188

31 Careers in the Digital Technology Industry __________________ 189

32 Careers in the 4th Industrial Revolution ____________________ 191

33 Education in the Digital Technology and the 4th Industrial Revolution ___________________________________________________ 193

34 Conclusion ___________________________________________ 195

35 About Dr. David Molapo ________________________________ 196

36 About Linda Khumalo __________________________________ 198

37 References __________________________________________ 200

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TABLE OF FIGURES PAGE Figure 1. Inter-relationship between the digital technology elements ................. 10 Figure 2. The Internet is the core of the 4th Industrial Revolution ....................... 11 Figure 3. Different Industrial Revolutions ............................................................. 21 Figure 4. A Basic depiction of Network elements ................................................. 24 Figure 5. A Basic view to a telecommunication link ............................................. 26 Figure 6. A basic depiction of a telecommunications network ............................. 27 Figure 7. A Basic set-up of a simple communications link .................................... 32 Figure 8. A simple point to point telecommunications link .................................. 41 Figure 9. Terminals connected via a switch .......................................................... 42 Figure 10. A simple depiction of switching systems for local and national calls ... 45 Figure 11. The PABX as a link between private premises and the PSTN ............... 46 Figure 12. The use of radio in telecommunications .............................................. 54 Figure 13. Different Satellite Technologies ........................................................... 63 Figure 14. A Typical Satellite link ........................................................................... 64 Figure 15. The basic set-up in a simple unidirectional broadcasting system ........ 89 Figure 16. A basic bi-directional broadcasting system used for communications 90 Figure 17. The basic layout of a pay TV network ................................................... 91 Figure 18. This figure shows a typical LAN computer network ............................. 97 Figure 19. Digital Technology Inventions over the years .................................... 112 Figure 20. A simple depiction of a converged network linked to content. ......... 113 Figure 21. A Technical depiction of a converged network linked to content. ..... 113 Figure 22. Universal Broadband Wireless Access and Mobility .......................... 116 Figure 23. Different Phases of Internet Connectivity .......................................... 118 Figure 24. A Typical Digital Technology Business Model ..................................... 142 Figure 25: Internet Users in the World in 2010 ................................................... 149 Figure 26. Internet Users in the World in 2017 ................................................... 149 Figure 27. World Internet Penetration Rates in 2010 ......................................... 150 Figure 28. World Internet Penetration Rates in 2017 ......................................... 151 Figure 29. Internet Users in the World by Geographic Regions in 2010 ............. 152 Figure 30. Internet Users in the World by Geographic Regions in 2017 ............. 152 Figure 31. Thomas Peter, Reuters. A robotic arm by Mitsubishi Electric assembles a toy car at the Systems Control Fair (SCF) 2015 in Tokyo, Japan December 2, 2015 ..................................................................................................................... 159 Figure 32. Demonstration of a Humanoid Robot. ............................................... 160

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LIST OF TABLES PAGE

Table 1: Distinct Categories of Fax Groups. ............................................... 28 Table 2 Categories of data speed and their corresponding bit ranges ..... 29 Table 3: Telecommunications Value Added Services ................................ 31 Table 4: Comparison of Analogue and Digital Technologies ..................... 40 Table 5: Comparison of analogues and digital switching technologies ..... 44 Table 6: Commonly Used Frequency Bands .............................................. 57 Table 7: Comparison of Fixed Terrestrial Wireless Systems ...................... 58 Table 8: Comparison of mobile terrestrial wireless communications ....... 59 Table 9: Comparison of fixed and semi-fixed satellite communications. .. 65 Table 10: Comparison of Mobile Satellite Services (MSS) ......................... 66 Table 11: Comparison of different satellite systems ................................. 66 Table 12: Examples of how different wireless technologies are used. ..... 68 Table 13: Application of different wireless technologies to different markets ...................................................................................................... 69 Table 14 Different telecommunications industries from the perspective of regulatory environment ............................................................................ 76 Table 15 Different Applications of Distance Education ........................... 120 Table 16: Different types of commercial electronic applications ............ 121 Table 17: Different Digital Technology Market Segments....................... 127 Table 18: Internet Usage Statistics for World in 2017 ............................. 144 Table 19. Population and internet users in Africa ................................... 145

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1. Introduction

Leadership throughout the world is facing the most difficult challenges ever encountered. The world has become more and mode digital, with a very thin line between digital and actual life. The more digitisation takes place, the blurrier this line becomes.

Digital technology and the 4th Industrial Revolution are considered as the main factors contributing to the transformation of life in developing, developed and least developed countries. Hopes for the economic recovery and sustained growth are now pinned on these technologies. Digital Technology has become an essential element of the infrastructure and applications underpinning competitive economies. The 4th industrial revolution is introducing the new possibilities, building on the digital technology.

Digital Technology and the 4th industrial revolution affect and influence every stage of life:

• In the womb: Sonar and X-ray are used to look at the miracle of a human and in future the genetic analysis will be made before the babies are born, with intervention whilst in the womb.

• At birth: Immediate Identity number are allocated to the child and people use social media to put their children online already and in future even school allocations will be done at birth.

• At the Pre-schools: School Cameras and Tablets are used for the education of the children and in future children will be engaged with the advanced technologies for more complex interactions than just education.

• At the primary schools: School Computer Lab, email and internet are enablers for learning and in future these technologies will be controlling the learning environment.

• At high schools: Mobile connectivity, social media and other teenage level technologies are used extensively as an option and in future these technologies will be mandatory for every learner completing high school, if high school will still be considered important to finish.

• At Universities: Online Assignments and learning is impossible without these technologies and in future the higher learning institutions will be the platform for advanced development of these technologies, if one assumes the existing hierarchy of educational configuration remains because in future new institutions of higher learning will be driven by

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these technologies and will be mostly likely be completely different from ones known.

• As Adults: Digital technology dominates adult life today and in future adult life will be controlled by the technology at a level where without technology, life will be impossible for those who will select to have their lives intertwined with technology.

• As Senior Citizens: Keeping in touch with family using social media is the way of life these days and in future Senior Citizens will be using technology to preserve memories and some will even be attempting to prolong life with the possible transfer of human consciousness into the machine.

• In After life: Holograms are beginning to be used e.g. Brenda Fassie performance using hologram, Michael Jackson album etc. and in future these afterlife Holograms will even be given artificial intelligence where new experiences will be possible with the individual even when they have passed on.

In today’s world, the ability to be innovative as well as the capability to distribute and exploit knowledge is a major source of competitive advantage towards wealth creation, and improvement in the quality of life. Information and communications technology (Digital Technology) has become the foundation of this knowledge-based society because it allows economies to acquire and share ideas, expertise, services, and technologies locally, regionally, and across the world. Furthermore, Digital Technology stimulates innovation as it encourages the creation and development of innovative ideas, products, and services. Finally, increased use of Digital Technology stimulates productivity, growth and further contributes to forging of partnership between people, countries, industries and academics.

The next level of the digital evolution is the 4th Industrial Revolution that take these possibilities to the next level.

Figure 1 shows the relationship between the different components of Digital Technology. Each of the elements depicted in figure 1 will be discussed throughout this book to provide the reader with a comprehensive view of the sector.

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Figure 1. Inter-relationship between the digital technology elements

The Digital Technology is a set of technologies that have been converging over the past few decades, to form a unified platform of communications service providing technologies. These technologies are:

• Telecommunications

• Broadcasting

• Information Technology or simply understood all the computer technology and other related technologies.

The above three technologies were traditionally separate and were regulated and managed separately by different countries and are still managed that way by many countries. User demands have led to an evolution that caused the innovators to start finding ways to combine these technologies to better satisfy user demands. Many countries are however starting to manage them as a combined industrial sector called Digital Technology.

The result is that the usage of any of these technologies is driven by convergence and hence the term and concept Digital Technology is one that will become common. The most powerful outcome and application of Digital Technology has been the Internet, a platform which is now becoming the centre of human interaction at the global level. In This Book Internet is dealt with as a dominant result of the convergence of Telecommunications, IT and Broadcasting.

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The Digital Technology Industry, now mainly driven by the applications and internet industry, is a complex and not easily manageable industry as it integrates the different players such as manufacturers, software developers, regulators, policy makers and service providers of different shapes and sizes. The Digital Technology Industry as a converged industry has not yet been completely recognised as one industry as the individual sub-industries are still very strong in their own individual rights. Nonetheless developments in the individual sub-industries are underpinned by the fact that convergence is always occurring, and these industries use the common denominator, the Internet, as the basis of their growth. So even though the different industries are managed separately, they have convergence as the underlying basis of their individual developments. So, in future these sub-industries will be seen and be treated as a combined Digital Technology Industry. The interesting aspect is also the fact that the Internet is setting standards and dictating the evolution of the Digital Technology Industry. The result of this Internet influence is the introduction of the 4th Industrial Revolution.

Figure 2. The Internet is the core of the 4th Industrial Revolution

Whilst the Digital Technology Sector is driven by convergence, it needs all the different component of the Digital Technology Industry to develop. It has also been accepted that the main driver to the development of the Digital Technology Sector is development of its three elements. This Book takes the Telecommunications sector as the main element and demonstrates its link with the other Digital Technology elements to form Digital Technology. Telecommunication can therefore be looked at as the central nervous system of the Digital Technology. The Digital Technology can then be looked at the central nervous system of the world.

This Book therefore presents these industries separately but in the key chapters there is a clear demonstration of the convergence of these industries. The chapters

Internet is the core

Digital Technologies: Telecoms, IT + Broadcasting

8 Elements of Industry 4.0

Industry Specific application

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of This Book can be read in any format for one to get a good insight into the Digital Technology Sector and the 4th Industrial Revolution. No technical experience is required to understand the book. In fact, this book attempts to simplify the technical complexities and provides the reader with a full sense of what all the different technologies are and what value they bring.

Furthermore:

• DT and Technology sectors the fastest growing in the World

• The Technology Usage is not an option anymore.

• The digital industry is the foundation of the 4th Industrial Revolution

• Technology is being underutilised today and our people are not getting the best, for example:

– Generic Email services e.g. Gmail, yahoo, webmail

– Internet Banking

– Growth of Computers/TV at homes

– Digital Migration on Broadcasting

• Globalisation Taking Place:

– International companies present in every country

– Sending their own people to the countries

• Interesting opportunities in our own communities

There are many analysis points to determine the economic impact of the digital technology in the national economy. The following are examples of the aspects to study when looking at local community, provincial and national level. • Number of homes connected to the Internet • Number of people with laptops and Tablets (iPad, Galaxy tab?) • Number of people on social media? • Number of homes with advanced Digital TV Set Top boxes? • Number of businesses with websites and social media accounts? • Number of people with skills and present on the internet? • Number of schools with websites? • Number of people with real email addresses? • Number of communities on the internet? • Number of people who are developing internet applications? • Number of Internet applications developed locally?

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The next stage of digital life is based on the 4th Industrial Revolution, made up of the following elements:

1. Internet of Things – A unique environment with the connection of almost every technology to the Internet.

2. Artificial Intelligence – A new and programmed ability for the machines to start learning according to the new developments and experiences.

3. Nanotechnology – A breakthrough ability to develop the minute technology and robots at nanometer level and use these nanorobots to solve macro challenges.

4. 3D Printing – A new and growing capability of printing real life products in form of layers, this technology is also called additive manufacturing and uses sophisticated processes to join the layers together towards the final product.

5. Autonomous Vehicles – The growing possibility of cars and aircraft that will drive themselves and controlled remotely, with the car or aircraft connected to the Internet.

6. Robotics have been growing and replacing human beings in activities that may even be dangerous for human beings.

7. Cyber Security is a complex process of using hardware, software and skills aimed at delivering security online for all the devices connected to the Internet. The same capabilities can be used to commit Cyber Crime; therefore, Cyber Security and Cyber Crime are two sides of the same coin.

8. Crypto Currency is growing as a new alternative to currency used widely. Crypto currency can be simply understood as a computer code that can be traded across borders and therefore not under the control of any government. Cryptocurrency is a commodity that is not regulated but to buy the commodity you must use the conventional currency and then start trading using the “Code” or “cryptocurrency. The main weakness of cryptocurrencies has been the absence of financial guarantees and government protection on investments made but this weakness has been receiving attention and with the new generation of cryptocurrencies being developed with more security and protection for those using them.

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This Book takes you on a journey to understand the evolution of leadership due to the impact of the Digital Technology industry and the 4th Industrial Revolution and covers the following aspects:

• Part 1. This part deals Leadership Evolution and introduces you to the fundamental elements needed to equip you to adapt to the 4th Industrial Revolution.

• Part 2: This part deals with Telecommunications and elaborates on various aspects of Telecommunications as this is one of the pillars of Digital Technology and it enables the passing of information from one point to another;

• Part 3: This part deals with Broadcasting and elaborates on various aspects of Broadcasting. Important in this part is the relationship between Broadcasting and Telecommunications;

• Part 4: This part of the book deals with Information Technology and introduces the important aspects of IT. Also covered in this part is the relationship between IT and Telecommunications;

• Part 5: This part of the book deals with the Internet and the 4th Industrial Revolution, as the major Digital Technology product from the convergence of Telecommunications, Broadcasting and Information Technology. The internet element also has a very important role to play around Cyber Security as the major threat facing human civilisation in the digital world. This part approaches Digital Technology as an integrated industry and elaborates how different countries are dealing with Digital Technology and the 4th Industrial Revolution. Also included in this Part 4 are careers and economic participation in the Digital Technology Industry.

• Part 6: This part of the book deals with ideal leadership needed in the 4th Industrial Revolution and also attempts to view and deduce the probable leadership roles in the future.

Enjoy the Journey.

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Part 1: Leadership Evolution

2. Leadership Evolution

2.1. Overview

Over the centuries leadership has evolved and has taken many forms and changes due to the environmental circumstances. At the centre of these circumstances are the following:

• Political Developments

• Economic Developments

• Social Developments

• Technology Developments

The 4th industrial revolution is driven by Economic and Technology Developments but with a direct impact on Political and Economic framework of the world. The process of leadership evolves from the environments of its birth and culminates in the environments reached to. Leadership vitality lies in the historical fact of the hierarchal order of the subordinate to commander or from sepoy to general.

“Leadership consists in mastering the calculus of dynamics of change”, Robert McNamara.

Real leadership never mushrooms rather grows from the seeds of recruitment to the shining stars of a general.

The 4th Industrial Revolution is introducing many unknown changes that cannot be predicted and predetermined, therefore difficult to prepare for. This means that leadership needs to begin to prepare to take their teams to unchartered territories. A leader in preparing and a leader in performing are two different phenomena complementing each other.

The climax of leadership is in the victory and its disaster lies in the fall.

In order to avoid disasters, a leader has to keep trace of three basic concepts to address the basic difficulties of military leadership

o Personal Control o Limitations

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o Events

2.2. Critical Leadership Aspects

Personal Control The personal control is that which a leader gains over him, to have control over the forces, which operate in an operational situation.

Balancing emotions with logic

Taking setbacks on his strides

Enduring present frustrations for better future

A leader of these modern times MUST embrace technology and understand technology at the personal level. The Born-Before-Technology syndrome that leads to technophobia is a major weakness for many senior leaders. Denial of this fact usually leads to many negative consequences because the decisions taken by the technophobic leader usually ignores the power of technology.

Limitations Limitations placed on the individual choice by the society in the light of which, strategic decisions must be made are the following: -

Moral obligations

Religious obligations

Ethical and legal obligations

Industry and Regulatory Obligations

Obligations to the stakeholders (Employees, clients and suppliers. the Tricky Triangle as well as other stakeholders such as the community.

Events Those events over which, no leader has any controls are as under: -

Natural calamities and weather

Deceptions and Betrayals

Victory or defeat by an adversary in the industry

Innovation prowess of the Fresh Players who do not subscribe to old industrial rules. Many of these players use technology to attain the highest competitive edge. An example is Uber, the global transportation company that does not own cars. More such innovations are coming.

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A leader, who relies exclusively on only one of these factors, is bound to commit mistakes. Successful leaders must keep in mind all the three undermentioned factors simultaneously, while taking any strategic or tactical decision, because they are interdependent and mutually influencing variables, which cannot be separated: -

Individual ability

Necessity

Chance A military leader will show high ability at any particular moment depends directly on the following factors: -

How the military system has functioned during the previous years?

How the system functioned, depends on the ability and vision?

Lack of one or both, of the previous leadership Similarly, though chance is beyond the control of human beings, its adverse effects can be reduced by our actions. Mastery in strategy and tactics is often accompanied by good fortune in the military field due to following contrast: -

Social system in disequilibrium

Intolerant society

Dogmatic leadership

Misfortune Even, the most brilliant leader is circumscribed by the limits imposed as under: -

The culture

History

Economics of the Society, he emerges Unless the leader is aware of these limitations, she or he is bound to commit horrendous mistakes. “Freedom”, as Spinoza so concisely says, “is the knowledge of necessity”. That is, one is free to the extent that one knows one’s limitations. Politics, as a process of maintaining the equilibrium, is the art of the possible.

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To discover the limits of the possible, one must have sound grasp of following five factors: -

History

Sociology

Economics

Technology

Politics Above all, one must have close links with the troops, because they are the source of power, if their following rights and privileges have been fulfilled: -

Needs

Dreams

Aspiration

Capabilities Nothing worthwhile can be accomplished without understanding and adhering to the following factors: -

Organizing

Mobilizing

Driving the forces into action Recent history proves that many leaders came to a tragic end, because, after having risen to power, they lost touch with the people and neglected the following measures:

Purifying and strengthening of their armies

Keep the troops in close contact with the leader

Set up an example of incorruptibility

Kept up with the major changes in their environment Indispensable Condition for A Lasting Leadership Leadership is tested, when a social system is in disequilibrium i.e. a society, which is changing, and which needs further change to continue its existence. If the leadership is unable to seize the moment and bring about the historically inevitable change, the credibility gap is bound to fall. As the former French premier, Mendes

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Frances, has said: “To govern is to choose”. The courses of action available to leadership in a crisis range from one or other as under. The successful attainment of ‘conservative change’ depends on two factors:

Leadership’s familiarity with social as well as the industry conditions and its ability to determine, which elements of the value structure need immediate change.

Leadership must strive to adjust the value-structure to the needs of the times and to formulate suitable values of practiced behaviour.

If this is accomplished, the credibility gap is bridged, and there will be no catastrophic change. Instead, there will be an instance of ‘conservative change’, i.e. change that will conserve leadership. This is precisely what the New Deal of President FD Roosevelt did during the 30s and the Reform Bill of 1832 accomplished failed to accomplish it in the 1980s. ‘Reactionary obstinacy’ The Soviet leadership pursued ‘reactionary obstinacy’, which is the blind pursuit of outdated policies which worsen rather than improve the social system in disequilibrium. This is precisely what the Bourbons did, whose policy brought about the French Revolution (1789). Even after the restoration the Bourbons struck to the old policy, since “they learnt nothing and forgot nothing”. ‘Reactionary obstinacy’ stems from an isolated leadership:

Due to a rigid class-structure

Inevitably leading to corruption and degenerations

Consequent upon blocked channels of social mobility.

Denial of major environment and industrial changes Eric Hoffer has summed up the dangers in a society in disequilibrium in these words: “When a population, undergoing drastic change is without abundant opportunities for individual action and self-advancement, it develops a hunger for radicalism. In other words, drastic change under certain conditions creates a proclivity for:

Fanatic attitudes

Desperate action

Spectacular manifestations of defiance It creates an atmosphere of revolution. We are usually told that revolutions are set in motion to

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realize radical changes. Actually, it is drastic change, which sets the state for revolution. The revolutionary mood and temper are generated by:

Irritations

Difficulties

Hungers and frustrations

Inherent realization of drastic change It is precisely for the reasons that Robert McNamara has defined leadership as mastering the calculus of the dynamics of change. If democracy anywhere is to take root and flourish, the leadership must conquer the dynamics of change, which can be accomplished only by following measures:

Organizing the system

Mobilizing the responsible

Enthusing the common people

Defence of democracy and social justice

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2.3 New and Unique Challenges brought by the 4th Industrial Revolution

Figure 3. Different Industrial Revolutions

The 4th Industrial revolution is bringing the biggest change in life experienced by humans since the first and the second industrial revolutions. These changes will challenge the leaders to the highest degree and many leaders (and their organisations) will not survive these changes. At the Centre of these changes are the following major elements:

All industry rules are changing or challenged and even be bulldozed with innovative technology developments. The Uberification of industries is the new norm and the expected change to all industries.

The fresh players, who use these technologies, do not have the patience or even follow the “industry protocols”. These fresh players have one thing in mind, use technology to attain competitive edge and use the latest technology advances at any available opportunity, including the replacement of human beings for tasks that used to be complex or menial.

Minimise costs and increase profitability by deploying the latest technology and methodologies that are improved whilst being deployed. The traditional experiment-before-you-implement mentality is the thing

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of the past. The fresh players experiment whilst implementing, something frowned upon by the Old Guard, but they can’t stop this economic Tsunami.

2.4 Equipping you to survive the 4th Industrial Revolution

This book is a tool to help you understand the 4th Industrial Revolution, in the context of your role as a leader. This process is designed to help cure those suffering from technophobia as well as strengthening those who understand the impact of technology in their environment. As a leader you are engaged to understand that at the foundation is the Digital Technology and the house is 8 elements of the 4th Industrial Revolution. The book is structured to help you link these elements and then understand how they impact you in your environment.

2.5 Industries to be affected by the 4th Industrial Revolution

Every industry will be affected by the 4th Industrial Revolution, if not already affected. The reason for this situation is because every industrial sector utilises digital technology. No industry operates outside digital technology. Therefore, every industry is seeking out innovative ideas, based on digital technology, to improve efficiencies and productivity. No industry is spared from this digital evolution of life. Examples of companies like Kodak are lessons on how a major company can fall from high revenues just because of the changing landscape, induced by digital technology developments. The present is a critical moment in our history. We must learn from history, otherwise, as George Santayana says: “Those who do not learn from history shall repeat it” or they will just perish.

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Part 2: Telecommunications

3. Introduction to Telecommunications

3.1. Overview

Communications is one of the key ingredients of life. Many ways of communicating have been used by different people since the beginning of time. These methods range from simple verbal messages to drums and light signals. When long distances separating people became a problem, better methods of communications were needed. This led to the invention of a simple telephone by Alexander Graham Bell in 1876. After his invention, additional innovations were made which enable one to make a phone call to virtually any part of the world. These innovations form the world-wide telecommunications networks made up of wired and wireless technologies. So, within telecommunications there are different sub-sectors which constitute the whole sector. These sub-sectors in telecommunications continue to grow and evolve. Telecommunications, as a sector, can be categorised as follows:

• Terrestrial Telecommunications which have two sub-categories: I. Wired and Wireless Telecommunications,

II. Fixed and Mobile Telecommunications;

• Satellite Telecommunications which can be Fixed and Mobile Telecommunications.

This Book elaborates on Terrestrial and Satellite Telecommunications chapters as well as how these technologies are used in a combined form, ultimately forming the nervous system of the Digital Technology.

3.2 Telecommunications Networks

3.2.1 Components of communications networks

A communication network is a system composed of the interconnection of basic communications components or network elements. It can be represented by nodes and links to interconnect the nodes. A node is a user terminal, such as a telephone, connecting an individual who wishes to communicate with other individuals, to a network of devices built to facilitate the connection many nodes to each other. The network devices will consist of switches and transmission equipment which will be discussed in more detail in later chapters. The picture below applies to all kinds of

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telecommunications networks, whether fixed or mobile, terrestrial or satellite based.

The nodes of the network are normally referred to as the Access part of the network. This is the part of the network that gives the subscriber access to the rest of the network, i.e. access to the switches and the transmission parts of the network.

Figure 4. A Basic depiction of Network elements

Telecommunications networks consist of three broad categories of equipment:

• Terminal equipment. This is generally located within the subscriber premises, in the case of mobile phones, on the subscriber’s person. Terminal equipment has the role of linking the subscriber to the network and transmitting and receiving information, as well as controlling signals between subscribers and the rest of the communications network.

• The switching system. This routes traffic on the network to the correct destinations, acting like a post office that identifies where certain information is meant to go and routing it that way. In the case of a telephone call, it will route the call to the intended telephone number. The switching system also has the function of interconnecting transmission facilities at various locations and adjusting traffic pathways

Terminal A Terminal B

Terminal C Terminal D

Switching

Transmission

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within the communications network to route the traffic to the correct destination.

• Transmission facilities. This provides communication pathways for transporting information between subscribers. This information is generally referred to as telecommunications traffic. In general, transmission facilities consist of transmission media such as copper wire, optic fibre, radio, satellites, and various electronic devices placed along the transmission media to boost the signal being carried. Transmission equipment also carries out the function of connecting transmission facilities to the switching system.

For the communication traffic systems of the network to be comprehensible to one another, the transmission facilities and switching systems must be able to provide signalling functions in addition to carrying communications information. Signalling refers to the process of transferring a variety of information for controlling the setting-up of communication channels within the network, as well as related operations. The information capacity required for signalling is insignificant compared to the capacity for general information transfer, hence, signalling information has up to now been transmitted as part of the general communication channel and signalling functions have been performed by transmission equipment inside the network and by switching systems.

3.3 Basic telecommunication services

The telecommunications network exists for one reason and one reason only, to provide services to subscribers. These services are transmitted as electrical or light signals on the network. The services can range from voice, data, video or fax services. All these services have specific requirements, which are controlled by technology standards. In the past, the provision of telecommunications services was restricted by the technology used to provide the service. The technology was relatively inflexible, for example voice services could not be integrated with data services. This has changed quite dramatically in the past 10-15 years in that these services can now be combined according to customer requirements. The market is now driven by demand, rather than by the limits of technological capability.

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The basic transfer of information in the telecommunications network is represented in diagrammatic form in the Figure below.

Figure 5. A Basic view to a telecommunication link

3.4 Voice

The transmission of voice over telecommunications networks is the service that most people are familiar with. Voice services on telecommunications networks can be analogue or digital. The difference between analogue and digital signals is discussed later in This Book. For a voice service the basic chain of events starts with the dialling of a telephone number. This number is sent by the user terminal equipment (their phone) to the switching network, where a connection is established between the caller’s local switch or exchange and the receiver’s exchange. The receiver’s exchange then connects to their telephone and the phone rings. When the receiver answers the phone, the connection is established. When either party speaks into their terminal device, or telephone, their speech is converted into an electrical signal. This signal is then transmitted over the network and received by the other terminal device, which will convert the signal back to recognizable speech. This system is known as the Plain Old Telephone System (POTS). The evolution of the terminals is moving from the Plain Old Telephone Systems (POTS) to Pretty Awesome New Stuff (PANS)

The POTS network is based on switches creating circuits connecting subscribers. Switches are very powerful in a telecommunications network because instead of creating a dedicated circuit (line) between two subscribers, using a switch, a bigger number of subscribers can be connected to each other as and when required. This is because a switch can create a connection (a circuit) between any set of terminals connected to the switch, i.e. a circuit can be created between terminal A and terminal B, and then later a new circuit can connect A to C because the switch acts as a central hub. Circuit based switching technology has, however, been

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superseded by newer developments using packet based technology. The way that calls are made on a packet switched network is different from the switched environment, however the fundamental principles stay the same.

On a packet switched network, when a caller dials a number, the switch still establishes a connection to the dialled number once the call has been answered. The connection between two points on a packet network is not a dedicated circuit and it shares the links with other connections. On a circuit network, a voice connection is carried on a dedicated circuit. On a packet network the voice signals converted into data packets and sent through the network in any order and then re-arranged into their proper sequence on arrival at their destination. This difference will be discussed later in switching section. The other key difference is that on a packet based voice network, the switch is referred to as a ‘Soft Switch’ because it is more software driven than hardware based. In fact, the switch is a computer like an ordinary PC, except this computer is much more superior in terms of processing power and capabilities.

Figure 6. A basic depiction of a telecommunications network

3.5 Facsimile

The facsimile or fax is the transmission of a document from one terminal device (fax machine) and reproduction of that document at another fax machine over the traditional telephone (POTS) line. This service has been available for several decades and continues to evolve. The transmission and reception of faxes is governed by standards that are developed and managed by the International

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Telecommunications Union (ITU). There are distinct categories of fax services. Table 1 illustrates the different fax categories.

Table 1: Distinct Categories of Fax Groups.

Fax Group Characteristics

Group 1 This analogue system takes about six minutes for an A4 page to be transmitted. Group 1 fax machines may still be in use, but most of these terminals have been replaced by machines based on newer standards.

Group 2 This analogue system takes about three minutes to transmit an A4 page. There are still a few in use, but most of these terminals have also been replaced by machines based on newer standards.

Group 3 This system takes less than one minute to send an A4 page. These machines can inter-work with Group 2, in which case they use a ‘handshaking’ procedure to establish the transmission speed. If the machine at the distant end is a Group 2 machine, the Group 3 machine sends information more slowly.

Group 4 This is the latest model, designed to work over digital networks. This system takes about four seconds per A4 page and has the capability to transmit colour pages.

The process for sending a fax is very similar to the process of making a phone call. The sending party dials the number to which they wish to send a fax. Their local switch connects to the receiver’s switch via the transmission network. The receiver’s switch connects to the fax machine at the receiver’s end and the fax rings. When the receive button is pressed on the receiving side, the fax is sent. As there are no people communicating during this process the fax machines need to inform each other if the remote fax is ready to receive a transmission and the sending fax also needs to communicate to the remote fax when it has completed transmission. This communication takes the form of the familiar beeps that can be heard when sending or receiving a fax. The fax machines use the ITU standards for fax communications to interpret the meaning of each beep.

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Fax machines have been used since the late 19th century. In the mid 1970’s modern fax devices and systems were introduced, these had greater ease of use and were cheaper than the older versions.

The technology of providing fax services has since evolved, now businesses and individuals use fax differently. In the past one required fax machines on both ends, however, lately it is computers with built in fax capabilities that are used to send and receive faxes. Some fax services now transmit and receive faxes between 2 or more points. More popular recently, are the fax-to-email services wherein a fax document is converted into an email. This feature makes it easy to store and print the fax document anytime. The reverse process of email to fax is also increasingly popular.

Faxes are still widely used and will probably continue to be for a long time, especially in developing countries where access to computers and e-mail, is less pervasive.

3.6 Data

As with voice, the transmission of data over networks can be analogue or digital. Data transmission started as early as 1890 when Herman Hollenth designed what he called ‘the census machine’ which was used to count balloting papers and relay the results by the use of the telegraph. There are distinct categories of data transmission as shown in the table below.

Table 2 Categories of data speed and their corresponding bit ranges

Category Speed range (Bits per second)

Low speed 64Kbit/s

Medium speed 64Kbit/s - 256Kbit/s

High speed or broadband

256Kbit/s and over

(Minimum speeds increase with the development of networks)

In recent years the transmission speeds have been increasing as a result of continuous improvements in technology. The definition of High Speed /Broadband data transmission is changing in terms of the bit per second every year. According to the ITU a Broadband connection is any connection that is 256Kilobits per second (“Kbit/s”) and above, whereas a Narrowband transmission is anything below

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256Kbit/s. It is however expected that this definition will be reviewed as new speeds redefine what constitutes Broadband. Therefore, what is considered broadband today will, most likely, be considered Narrowband in future.

3.7 Telegraph

The word telegraph is taken from a Greek expression meaning to write from a distance. It was first pioneered by Samuel Morse who was assisted by Alfred Vail in 1835.

The telegraph operated by having a telegraph operator on the sender side, tapping a series of pulses onto their telegraph terminal. These pulses would be transmitted via the cables to a receiving terminal which would replay the taps. A telegraph operator at the remote end would interpret the taps and respond with another series of taps. Each tap was either a short tap or a long tap, with the combination of long and short taps representing words. The tapping was known as Morse code, after its inventor.

Telegraphs are hardly used in the 21st century except in cases of the direst emergencies. Faxes are also joining the antique corner of not being used anymore.

3.7 Telex

The telex is an international system of telegraphy in which text is transmitted and received by the tele-printers using the Publicly Switched Telecommunications Networks (PSTN). The tele-printers replaced the telegraph operator at the receiving end. The use of telex has drastically decreased due to the introduction and growth of advanced services such as fax, e-mail and the internet.

3.8 Value Added Services

The services we have described up to now have been basic telecommunications services.

Basic telecommunications services can be augmented in order to add more value, based to customer requirements. These are generally referred to as Value Added Services (VAS), i.e. value added to basic services Table 3 gives examples of VAS.

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Table 3: Telecommunications Value Added Services

Value added services

Description

Voice mail Storage and retrieval of voice messages from a Voice Mail system on the network.

Call- forwarding Automatic forwarding of calls to a secondary telephone line

Call barring Selective or collective barring (blocking) of telephone lines by programming the telephone terminal or using the network services.

Caller line identification (CLI)

Identification of the telephone number of a caller.

Universal access number

A number allocated to customers at different geographical sites. Incoming calls are routed according to a pre-determined program designed to locate the user wherever the user may be. This technology combines both mobile and fixed telecommunications services to locate the user. This service has already been deployed with many mobile operators who allow customers to move from one network to another whilst retaining the same telephone number.

The value-added services mentioned in Table 3 depend on the capabilities of the end-user terminals and the telecommunications network. Advanced networks usually have technical capabilities, which make it easy to provide the value-added services. There are many other value-added services which are not mentioned in This Book as the value-added services offering is continuously evolving.

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4 Terrestrial Telecommunications

4.1 Overview

Terrestrial telecommunications can be defined as telecommunications taking place within the atmosphere of planet Earth only. This differs from satellite or space, based telecommunications because the signals of terrestrial communications do not exit the earth’s atmosphere. It is however, important to mention that many telecommunications networks are a combination of both terrestrial and satellite technologies.

4.2 Basic elements of terrestrial telecommunications

Figure 7. A Basic set-up of a simple communications link

4.2.1 The transducer

The transducer is a device that converts energy signals from one form to another. It converts sounds into an electronic signal which is then passed to the transmitter. It also converts the electronic signal back to sound.

4.2.2 The transmitter

The transmitter is a device which propagates the signal. As part of the end-user terminal, the transmitter is responsible for passing the signals on.

4.2.3 The encoder

The encoder is used for the processing and storage of the message. The encoder is a very complex part of the link, because it is required to perform tasks which involve reorganization, compilation, calculation and consolidation of information. The end result of this process is a transmitted signal targeted at the correct destination. A more sophisticated level of encoding is called encryption where the information is re-arranged to avoid tapping or eavesdropping.

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4.2.4 The channel

The channel is the switching and the transmission medium (TTSS in figure 3) for the distribution of information. In normal everyday situations, the medium is air when two people are talking to each other. The channel carries the information being sent to the receiver on the other end, but it may pick up impairments (interference, noise, transmission loss, echo, or other factors that may interfere with the transmission) which are detrimental to such information. A major concern of channel technology is the understanding of these impairments and their elimination or reduction.

In a fixed terrestrial system, the electronic signal is passed to the destination by a wire or cable link. At the destination, a second transducer converts the electronic signal back into the original energy form. In practice, other devices may be required, for example, amplifiers, which are usually used when it is necessary to increase the power level of signals to compensate for the losses encountered during transmission.

For a terrestrial radio system, a transmitter is required at the source to send the signal over the radio link and a receiver is needed at the destination to recover the signal before sending it to the transducer.

The electronic signal may be distorted due to a number of reasons, for example electronic noise. These are undesirable effects and must be minimized in the system design.

A circuit is normally allocated for communication between two terminals. The circuit can be thought of as a pair of wires connecting the two terminals. If there is a requirement to connect two or more terminals however it may not always economically practical for another pair of wires to be provided. A switch is used to establish multiple voice connection and the explanation on how the switch achieves this is discussed in This Book. A switch is therefore used to enable more than one voice channel to be carried on one of the following transmission media:

• co-axial cable networks: These are networks with amplifying stations every few kilometres, linking cities together. These networks carry many thousands of channels joined together in a process called multiplexing;

• radio networks: These networks operate at frequencies much higher than ordinary domestic radio sets. There are several types of radio technologies which use different frequencies in order to make up a radio network. A more detailed discussion on the Radio networks is found in the Wireless Section of This Book;

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• optic fibre networks: These are special forms of transmission in which energy representing many thousands of voice channels can be transmitted as pulses of light. The light is transmitted along a fibre optic cable, which is made from strands of glass as thin as a strand of human hair.

4.2.5 The decoder

The decoder is responsible for converting the encoded information back to a comprehensible message for the receiver. A digital satellite TV decoder is an example of the Decoder.

4.2.6 The receiver

The receiver is a party at the other end of the connection. It can be a person, a voice mail system, a computer, or any other device capable of understanding or receiving information.

4.2.7 The telecommunications traffic

Telecommunications voice and data links carry information which is referred to as telecommunications traffic. The following are examples of telecommunications traffic:

• The voice traffic. This is the conversation between two people which requires that information move in both directions, often at a same time. There are also gaps in the speech flow when people take a breath or stop to think. These idle gaps are used by speech compression systems which fill the gaps with information from other speech channels, thus increasing the efficiency of the system and reducing the number of channels required to carry traffic. In modern system voice traffic is sent as data traffic;

• Data traffic. This traffic emanates mainly from computers and computerised devices which send blocks or packets of data (which can be text, graphic, even multimedia) to other computers. With new signal processing, compression techniques and the Internet Protocol, it is now possible to send video pictures to subscribers on several types of devices.

• Fax Traffic; Machines convert images or text into codes tones which are sent over the switched or IP network in much the same way as data. Modern systems send fax traffic as data traffic.

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5 Telecommunications Networks

Telecommunications networks take on various forms, all of which have, at their core an access component, a switching component and a transmission component. In this chapter we will deal with the distinct types of networks that occur but also deal with augmentations to the basic networks.

5.1 Public telecommunications networks

Commonly known as Public Switched Telecommunications Network (PSTN) this network is the one that most people are familiar with. It is accessible to any member of the general public who wishes to subscribe to the services offered on the network. Fixed PSTN; is a PSTN where the terminal equipment is fixed to a customer’s premises, e.g. a landline telephone

Mobile PSTN: This is a PSTN where the terminal equipment is not fixed but can move around i.e. a mobile phone.

5.2 Private Networks

Private networks may have exactly the same underlying technology as public networks with the exception that they are not open to the public. They typically belong to private companies or State-Owned Enterprises also known as Parastatals and/or the military. These networks may or may not link back into the PSTN, depending on their use. Typically, all the equipment making up the network, the switching the transmission etc belong to the company. The company may lease transmission capacity where it is more economical to lease this from an operator instead of building new capacity, but they then manage the leased facilities as part of their own private network. This option used to be a very expensive way of ensuring dedicated telecommunications capabilities. However, network operators who have invested in networks can make the option establishing a private network cheaper than the establishment of a completely private network.

5.2.1 Virtual Private Networks

A cheaper alternative to building a private network for most companies is to get a Virtual Private Network (VPN). For these companies, telecommunications operators can provide a private network which will be a sub-component of the public network, partitioned off for the exclusive use of the specific customer requiring this service. A VPN customer does not have to buy or lease extensive hardware to build their own network. All that has to happen is that the telecommunications operator provides part of the PSTN to the VPN customer on an exclusive basis. The provision of private networks depends on the national regulatory environment.

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5.2.2 Value Added Networks (VANs)

The normal PSTN provides basic telecommunications services, for example a point to point connectivity. Because of the emphasis on offering value to the customer a considerable number of operators have created value added networks. A value-added network (VAN) is a network with services such as ‘call forwarding’, “push-to-talk”, “messaging” etc. Call forwarding is a service which enables a user to route their calls to a destination of their choice. The user of a landline can therefore move from one part of the country to another without having to use different telephones numbers. This is especially convenient when one is just visiting an area and does not want to lose important telephone calls. Call forwarding is possible on both fixed and mobile networks. It is also possible to establish call forwarding between countries.

Value Added Network Services (VANS) can also be supplied by third parties who rent parts of the PSTN from an operator and offer value added services to the general public. These VANS operators are a hybrid between a VPN and a PSTN. Such operators are commonly referred to as second and third tier partners as they normally lease bandwidth capacity from the main provider and in return resell to third parties.

5.2.3 Virtual Networks Operators

The PSTN can be a fixed or a mobile network. In some instances, companies establish a cross between a VANS and a VPN. These companies are called Virtual Network Operators (VNO). They basically sell telecommunications services, but do not own a telecommunications network, companies such as Virgin Mobile operating in South Africa and using Cell C network are examples of Virtual Network Operators. They may rent switching capacity or transmission capacity or even agree with a network operator that they will rent the entire network infrastructure from the operators. The VNO do not normally own a network. VNO’s can be fixed VNO or Mobile VNO which are widely known in the mobile sector simply as an MVNO.

There is a new virtual network partnership model known as Mobile Virtual Network Enabler (or MVNE). An MVNE is an entity that provides services to mobile virtual network operators, such as billing, network element provisioning, administration, operations, support of base station subsystems and operations support systems, and provision of back-end network elements, to enable provision of mobile network services like cellular phone connectivity.

A MVNE may not have a relationship with end-user customers. Instead, an MVNE provides infrastructure and services to enable Mobile Virtual Network Operators

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(MVNOs) to offer services and have a relationship with end-user customers. MVNEs offer the ability for an MVNO to focus on their core strengths of marketing, building brands and customer loyalty and leave the back-end enablement and operations, to MVNEs. They also have shared risk-reward arrangements with the MVNO based on various kinds of revenue sharing models, usually tied to the number of subscribers that the MVNO has projected in its business plan.

5.2.4 Data networks

Data networks, private or public, have been established to overcome the limitations imposed by the POTS network. Transmitting data over PSTN has ‘bandwidth’ limitations due to the way that the information is transmitted over the network. With networks designed to carry data, information is handled differently to optimize for the fact that data as opposed to voice is not delay sensitive. If data is broken up into chunks and sent down the network, these chunks can arrive at the remote end in any order and with delays in-between, without affecting the perceived quality of service.

Data networks were used primarily to connect data facilities of big businesses such as banks, to each other. These facilities were connected via what are called dedicated leased lines. These lines were only for carrying data no voice communications. Vast amounts of data can be carried via these dedicated lines as they have much greater capacity than the normal POTS line.

Various technologies are used to implement data networks, ranging from X-25 networks that carried lesser amounts of data, ATM, short for Asynchronous Transfer Mode and Frame Relay networks that carried much greater quantities of data and operate at very high transmission speeds. ATM and Frame Relay break data down into packets for transmission on the network. These technologies were also by the telecommunications companies themselves to carry telecommunications traffic in the transmission part of the network.

These technologies have been superseded by the advent of Internet based data networking technologies. The technology of choice for data networking is now based on the Internet Protocol (IP) for transmission of data. The IP protocols are the common base on which data networks are developing as these protocols are now understood and accepted by all players in the Digital Technology Sector.

5.2.5 Intelligent networks (IN)

An IN platform is a software tool that enables a network operator or service provider to provide a range of services tied to the network, beyond just making and receiving calls. These are services such as Caller Identification which provide information about who is calling, or services such as Call Prioritisation; the ability

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to allocate priority to calls, separate billing/tariff packages, etc. This is because IN platforms separate information about the content of the call, i.e. a conversation from the call itself. Whereas before the switch provided the service and also kept track of all call related information, under an IN platform these two functions are separated. This takes the provision of telecommunications services to a new level. With an IN platform, the information about a call is made available to a dedicated computer system outside of the switch. As these systems are separated from the process of physical connecting calls and only deal with call information, they can be a lot more innovative in terms of their functionality and what they can do with that information.

IN technology is really based a computer server system that stores and processes information about telephone calls as well as subscribers. What this enables the operator to do is to extend the range of services available to subscribers beyond the basic telephone call. The service provider is now able to offer services that add value to the telephone, including features such as prepaid phone services and collect call services.

IN technologies also make services such as user selected ringing tones possible. Through these types of services, the user is able to select from a range of rings provided by service providers, instead of the standard old-fashioned ring. With IN services, telecommunications have become about more than basic communications.

5.2.6 Converged networks

Due to the convergence of technologies, there is a growing need for a network with versatile capabilities. This has led to the development of Converged networks which can be defined as a digital communications network that not only provides basic fixed voice communication, but also allows the integrated provision of fixed and mobile voice, video and data services. The main feature of Converged networks is that the subscriber interfaces with the communication network through any access device. This means that several communications devices and networks can be connected to one account. Subscribers can have one number that is both their fixed and mobile number and they can access the network using their land or mobile lines. In converged networks, connection between subscribers is accomplished digitally at high speeds.

Converged networks allow the handling of various voice as well as data services in an integrated manner. This is possible because the converged network uses the IP protocol which converts both voice and data into packets and can therefore manipulate them more easily. Converged networks also provide packet switching services that allow sharing of various information resources within the

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communication network as well as versatile service provision that enables the user to access their service from anywhere and whenever they want to. The platform which makes converged networks possible is called the IMS (IP Multi-Subsystem).

5.3 Analogue versus digital

The voice from a human being is transmitted through the air as a series of waves. These waves are similar to waves in the ocean. Each wave has a starting and ending point, called the wave’s width or amplitude. Similarly, if one stood on the beach, a certain number of waves would strike the beach every second, in other words the waves would strike the beach with a certain frequency. With traditional telecommunications, the voice was converted into an analogue signal. The analogue signal retains the basic features of the wave and has the same two basic characteristics:

• Frequency: The frequency is the expression of the number of times the wave fluctuates or oscillates. This counts the number of times a wave oscillates per second. A high-pitched voice is composed of high frequency waves.

• Amplitude: The amplitude is the measure of loudness or the width of the wave. A soft voice has low amplitude.

Analogue systems therefore transmit information in the form of waves. These waves are electronic but have the same characteristics as normal waves.

Computers are based on digital technology, so unlike people when they communicate with each other, they send each other digital signals. A digital signal is made up of a sequence of on-and-off electrical pulses rather than waves. With digital systems, the electrical pulses represent either a 1 or 0, alternatively one can think of the signals as being on or off. Digital signals are easy to manipulate since the signals come as individual distinct units called bits, while analogue signals come in the form continuous streams or waves.

An example that combines digital and analogue technologies is connecting a computer to the internet using the telephone line. In order to go onto the internet using a computer and a dial-up modem, the computer has to send digital signals over an analogue network (the telephone network) using the modem. The name modem is short for modulator-demodulator. The modem modulates (converts) the digital signal into an analogue one. At the destination, another modem will then demodulate (converts back) the analogue signal back into digital in order to be understood by the computer on the internet.

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Over the past few decades, it has been generally accepted that digital systems are superior to analogue systems. Table 4 below illustrates a comparison of analogue and digital technologies in telecommunications networks.

Table 4: Comparison of Analogue and Digital Technologies

Aspect Analogue Digital

Economic benefit

It is also expensive to manufacture, operate and maintain analogue equipment. There are fewer and fewer companies who continue to manufacture analogue technology.

It is easier and cheaper to manufacture operate and maintain digital equipment.

Interference handling

Requires substantial investment to obtain optimum noise detection and elimination.

Higher quality of digital transmission enables simple noise detection and noise cancellation processes.

Multiplexing Lower capacity multiplexing capabilities. Example: 1st stage of analogue Frequency Division Multiplexing (FDM) provides 12 channels on a single co-axial cable.

Can get higher multiplexing capabilities. Example: 1st stage of digital Pulse Code Multiplexing (PCM) provides up to 30 channels on to a single co-axial cable.

Encryption Normally requires a lot of hardware and software to encrypt analogue signal

Digital signals are easy to encrypt since they come in bits rather than continuous waves. There are many software options to encrypt digital information.

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6 Switching and Transmission Systems

One of the most critical areas of telecommunications is switching. A switching system is needed to enable any terminal (a telephone, a telex, etc.) to pass information to any other terminal

6.1 Simple switched network

If the network is small, direct links can be provided between each pair of terminals if one wants to connect more terminals to each other however, direct connection become more complicated. Imagine network with 50 terminals, to connect all the terminals to each other, one would need 1225 links.

Figure 8. A simple point to point telecommunications link

As the number of people needing to be connected to the telecoms networks grew, the need for a more efficient system also grew. The need was for a different approach to allocating one-to-one permanent links connecting to terminals to each other. A more efficient solution was to connect all the terminals to a central hub Instead. By connecting to the central hub, a terminal could then connect to any other terminal connected to the same hub. For example, terminal A could connect to terminal B via the hub, exchange information then disconnect. Terminal A could then connect to terminal C through the hub, exchange information and disconnect and then connect to terminal D etc. These connections would not require permanent links between A and all the terminals it was connecting to. As long as the remote terminals were connected to the hub, Terminal A could connect to them. This hub in telecommunications is called the Exchange.

The need to connect large numbers of people to each other led to the birth of manual exchange, where a human operator was called upon to act as the one connecting terminals to each other. The operator connected the terminals via the manual exchange (switchboard) to which all terminals connected. A caller would call the switchboard operator and request to be connected to a specific telephone number. The operator would then connect the two terminals using a patch cord.

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At the end of the conversation, the operator would disconnect the two terminals. When another call came in or the same caller wanted to speak to someone else, the operator could then take the same patch cord and connect the new parties. Operators had many such cords to connect, disconnect and reconnect many terminals to each other. Figure 7 shows a simple schematic of an exchange also known as a switch.

Using the following formula where N is the number of terminals, there must be a total of:

½ N(N-1) links

1/2 x 50(50-1) = 1225 links

So, in a network with 50 terminals connected there are 1225 links that can be established.

Figure 9. Terminals connected via a switch

Due to the slowness of the human operator, the rapid increase in the number of subscribers and the tendency of the operator to listen in on calls, a better way to switch calls was needed. The legend of the birth of the automated exchange is that there were two undertakers who were competing for business in Chicago in the United States. One undertaker had an advantage over the other as his wife worked as a switchboard operator for the local telecommunication company. She therefore routed all the calls requiring the services of an undertaker to her husband. This gave her husband an advantage over the other undertaker, Almon B. Strowger, who found out about this and invented the first automated exchange

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in order to stay in business. The first automated exchanges were electromagnetic, using electromagnets open and close switches that connected terminals to each other. When a specific number was called, an electromagnet would close a connecting switch, thus establishing the connection. The electromagnet would open the switch to disconnect the line when the conversation was completed. Telecommunications exchanges are commonly known as switches.

Later as traffic increased, and the network grew more complex, the slowness of the electromagnetic automated exchange together with its high maintenance costs necessitated the invention of a better switching technology. The field of electronics was emerging at around the same time that this requirement was arising. It therefore made sense that electronic switches should be used to replace the electromagnetic switch. Electronic switches were faster, cheaper and less complex as they have virtually no moving parts.

As the electronics sector grew it gave birth to computers. Computers are basically a collection of switches that either creates a circuit when the switch is set in the on position or breaks the circuit when the switch is in the off position. A computer is basically millions of these switches going on and off and through this process making decisions and executing instructions. It therefore made sense that computers should be used as switches to connect telecommunications terminals. The computers were much faster than the early electronic switches and were programmable, therefore more intelligent.

Switching systems have made it easy and relatively cheap to interconnect a community. They have also divided the field of transmission into two distinct areas; the connection between the exchange and the subscriber, which is called the Access network, and the connection between the various exchanges which is called the junction network. The junction network is comprised of connections from one exchange to all other exchanges in the same area, for example, a city. A city may have many exchanges each connecting to a specific neighbourhood. To connect different areas, for example, different cities, we use the trunk network, carried by transmission systems which are designed for long-distance and high capacity operation. The trunk network is just an intercity connection of switches, much like a junction network, only on a bigger scale.

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Table 5: Comparison of analogues and digital switching technologies

Characteristic Electromagnetic Electronic

Technology Analogue Digital

Switching Mechanism Uses magnetic relay contact to mechanically select and establish connections

Uses computer programming to switch calls and establish connections.

Maintenance costs High Low

The information given above explains why telephone numbers are organised as they are. For example, telephone number 865-3579 means that the subscriber of that line is the 3579th subscriber in exchange number 865. The exchange can typically carry 0000 to 9999 subscribers. A subscriber with number 999-9999 will be the 9999th subscriber on the exchange number 999. These two subscribers can phone each other via their two exchanges (865 and 999) using the junction network which connects the two exchanges and other exchanges within a city. For city-to-city connectivity, we get the trunk network which is referenced by the area code, 011 for Johannesburg, 012 for Pretoria, and 031 for Durban, etc.

Regulators around the globe are currently changing and introducing new inter-exchanging methods. For example, the numbering system is being changed such that a number will no longer be confined to an exchange area. Such change has already been introduced in the mobile environment. The concept is known as mobile number portability. Mobile number portability (MNP) enables mobile telephone users to retain their mobile telephone numbers when changing from one mobile network operator to another.

It is much more complex to implement number portability on a fixed line network and thus landline number portability may take some time before it becomes commonplace. (see Figure 7 on next page)

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Figure 10. A simple depiction of switching systems for local and national calls

6.1.1 Private Automatic Branch Exchanges (PABX)

Because companies require a large number of telephone lines as well as a certain degree of privacy, they tend to utilize private exchanges (Private Automatic Branch Exchanges-PABX) which are controlled by the companies. These systems are very much like the old manual exchanges in that connections between telephones are made by person, the receptionist or operator. But this is where the similarity ends, these systems are very advanced in technology and, in fact, do not need any operator. The operator is a result of companies wanting their clients to speak to a person when calling the company as opposed to the technology needing person to drive it. A PABX would normally serve a number of lines within the company and also act as a link to the rest of the PSTN. There are PABXs which can also link up offices which are situated at different geographic locations, hence establishing a virtual private network (VPN).

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Figure 11. The PABX as a link between private premises and the PSTN

Public data networks had to be developed that have been designed to handle data transmission. (Bandwidth refers to the capacity of a transmission system.) There are two types of public data networks: packet switched data networks (PSDN) and circuit switched data network (CSDN).

CSDN has a switching similar to the PSTN where a dedicated end-to-end connection is set up between the two points before the transfer of information. At the end of the transfer the connection is terminated. PSDN, on the other hand, has no exclusive connections between users. In PSDN terminals, information is sent in packets which have ‘addresses’ on them and are delivered to the address on the packet by the network via a virtual circuit connection. In the virtual connection, the information takes the most effective route to get to its destination. The various

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virtual connections are activated only when there is a message coming in or going out. Packet switching is now the most widely used type of networking and even voice is now sent using the packed switched data networks. The best example of packet switching is the Internet.

Packet switching is termed a ‘connectionless’ mode of transmitting information. Packets of information are introduced into the network, with a destination address added to the packet and the packet can be transmitted along various routes on the network until it reaches its destination. This information is then prioritized according to its importance. A voice packet data is given a priority and enjoys priority in transmission versus a packet containing for example e-mail data. The quality of service associated with a voice service will be higher, so that the user can have a decent conversation over the data network. If the packets of a voice conversation did not arrive in time and in the proper sequence, conversations would sound garbled. An email data packet may be given a lesser priority t

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