Trends in User’s device
Developments in the manufacturing and design of user’s device, such as basic telephone, have undergone major dramatic changes over the years. Telephones have developed from the humble rotary telephone of the 30’s and 40’s to the modern day digital telephones. Telephones have also developed in their functions; no longer are telephones the simple tool to make calls. Modern phones can perform numerous functions; record messages, store phone numbers and many other functions. The development of the cellular phone has brought telecommunications service to numerous people. The convergence of information technology and telecommunications services has led to a robust design of the cellular phone. The cellular phone is not for making and receiving calls only. It also provides links to the internet, it is capable of broadcasting radio signal, has an in-built digital camera, it can receive data messages – such as fax, it has an alarm clock, a digital diary and so on.

Fig 1: User’s device such as the basic ‘phone’ has developed over the years

Trends in Transmission Technology
The trend in transmission technology is the increasing development in the capacity of transmission technology. Telecom companies require technology that offer space and capacity that will allow them carry more calls at the same time and also allow them carry voice, data and digital images at the same time. This space is referred to as bandwidth. There’s been increasing development in transmission technology with large bandwidth. The trends in the transmission technology are on broadband access and service. Transmission in the telecommunications networks of today is, more and more digital in nature and fibre optic cable is the transmission medium of choice. Transmission method has moved from the synchronized transmission method, which is the conventional way of sending information in an orderly manner, to a new technology called Asynchronous Transfer Mode (ATM). With this technology “information is labelled, made into packets and then sent in the best available path at a higher bandwidth than normal transmission. “At the destination, these packets are then connected to constitute the original message before the user detects any delay” (Khumalo and Sibanda, 1998, 24). The SONET transmission mode is a standard for optical telecommunications transport. It defines the technology for carrying many signals of different capacities through a synchronous optical hierarchy. The SONET is a high-speed transmission standard.

The need for broadband access has made satellite and the fibre optic cables, the two high bandwidth transmission media of choice in today’s telecommunications services. Fibre optic cables provide a high transmission capacity; it provides broad bandwidth and capacity to transmit all forms of communication (voice, data and video). A fibre-optic connection is faster than wireless by many orders of magnitude. A single optical fibre can carry about 3 trillion bits per second (bps). The fastest wireless service (fixed wireless access) approaches 2 million bps. So, fibre optics can be more than a million times faster.

One of Africa’s fibre optic projects is the building of a submarine cable wrapping around Africa from Europe to the Far East. This US$600 million project is Africa’s most innovative undersea fibre optic cabling project. It is estimated that about 80 percent of Africa’s country-to-country telecommunication revenue flows out of the continent, due to most African countries’ dependence on foreign operators to route their international traffic. It is anticipated that the new system will save the continent in excess of over US $300 million per year, and the link will enable African countries direct access to each other as well as enhance global connection.

Trends in the Switching Technology
If there were only three or four telephones in a locale, it would make sense
to connect each phone to all other phones and find a simple method of
selecting the desired one. However, if there are three or four thousand phones
in a locale, such a method is out of the question. Then it is appropriate
to connect each other phone to some centrally located office and
perform switching there (International Engineering Consortium, 2003)

The above citation simply explains the basic function of a central-office (CO) in the telecommunications industry. It explains the function of switching technology in the telecommunications industry. Today a lot of activities take place in the telecommunications industry; this industry has witnessed a lot of improvement. For instance, telephony has developed from basic fixed line to wireless communication and the development of the internet has brought about millions of daily on-line telecommunications activities. The central office (CO) and the switching technology have gone through a number of fundamental technological changes. To understand the technological changes in the switching technology, we shall look briefly at the evolution of the switching technologies. See Table 1 below:

Table 1: Types of End-Office Switching and their evolution (International Engineering Consortium 2003)

• In the 1800s calls were connected manually at the central office. When a call came in, an operator would plug into a horizontal bar line, then shout out to the operator who handled the customer being called, the second operator subsequently connect to the bar and finish setting up the call.

Figure 2: A depiction of an early central office switching activities. (International Engineering Consortium 2003)

• Then came the step-by-step system which used a Strowger switch. This system was an electromechanical operation, the switch responded to the dial pulses of the rotary dial.
• The Cross bar switching system of the early 1900’s was also electromechanically in nature
• When electronics came, the electromechanical control of the common control system was replaced with electronics. The network type was replaced with reed switches, so only a part of switch was electronic.
• In generation after this, the stored program operation of a digital computer was applied to the switch, although the network still remained a complex of reed switches.
• The final generation, called a digital switch, the talking path was no longer an electronically continuous circuit; rather the speech being carried was digitized into a stream of “1s” and “0s”. So this stage operates on a digital domain and not analogue as in other previous stages (International Engineering Consortium 2003. 8-9).

Having identified the evolution of switching technologies, we can see how the revolution in the telecommunications industry has gradually being taken place over the century. However, we will end this session by identifying the current trend that has changed the whole switching operation in the telecommunication process and this trend has driven the telecom revolution enormously. Going back to the switching systems, one thing must be recognized: whether the system was analog or digital, there was a particular talking path. This is a circuit from the calling party to the called party. This talking path was established at the beginning of a call and held for the duration. This is called circuit switching. Circuit switching is a type of communications in which a dedicated channel is established for the duration of a transmission. The most ubiquitous circuit-switching network is the telephone system, which links together wire segment to create a single unbroken line for each telephone call. We should note that circuit switching dominates the public switched telephone network or PSTN. It is a dedicated line for a telephone call, “it’s like having a dedicated railroad track with only one train, your call, permitted on the track at a time” (TelecomWriting.com 2003). Some observers consider circuit switching not very efficient. When one party is talking the other party listens and the circuit is being used in one direction – that is 50%. When neither party is talking, when there is silence between words, the efficiency is 0%.

In telecommunications today, there is a different connection system noticeable in numerous applications such as:

• Credit-card verification
• Automatic Teller Machine (ATM)
• Internet and World Wide web

This system is called packet switching (as compared to circuit switching) (International Engineering Consortium 2003). Packet switching refers to protocol in which messages are divided into packets before they are sent. The packets are sent individually and can follow different routes to the destination, like the train analogy, the packets use any ‘railroad track’ available to get to the destination. Other packets from other messages race upon these tracks as well, making the most use of each track, quite unlike the circuit switched calls that occupy a single path to the exclusion of all others. Upon getting to the destination, the individual packets get put back into order by a packet assembler. This is because packets arrive at different times. We see example of this when downloading a web page or file, which comes with a tiny delay that is hardly noticed. However, we notice even the tiniest delay with voice (Telecom Writing.com 2003). Circuit switching offers the best sounding call because all packets go in order. No delay. Delays in packet switching for voice cause voice quality to drop apart. We notice this when we talk on the internet. However, as the telecom revolution goes on and technology gets better, voice over packet switched networks will get better (Telecom Writing.com 2003). The Internet is based on packet switching protocol.

Normal telephone service is based on circuit switching technology, it is ideal when data must be transmitted quickly and must arrive in the same order in which it’s sent, for instance, in the case of real-time data such as live audio and video. Packet switching technologies are useful for protocols such Wide Area Network (WAN), e-mail messages and web pages. This technology exists for data communication needs of education, business and governments.

Advancement and Trends in Wireless Technology
The development in the wireless telecommunications segment has contributed immensely to the telecommunication revolution. For instance, we have seen an astronomical growth in the cellular markets world wide; from the humble beginning in Sweden and Norway in late 1981 when the first cellular networks (NMT450) were launched, to 2002 when the global cellular market passes 1 billion subscriber mark (Cellular-news.com 2003). So it took slightly over 20 years to reach the 1 billion mark, with the Asia-Pacific region by far the largest cellular market. Considering the rate of development in the cellular market, it was projected that it will only take 7 years to sign up the second billion, with a total of 2.08 billion wireless users forecast to be reached by the end of 2009 (Cellular-news.com 2003).

In Africa, people are increasingly getting connected to telecommunication networks. This has brought telecommunication services to millions of people that could not be reached by fixed line telecommunications networks. For instance, cellular technology came live in South Africa in 1994 just a decade ago, during this period there were about 4million fixed line phones. Today, the number of fixed lines has grown by another million, in contrast, the cellular market has grown considerably. There are about 16 million cell phone subscribers today (Nicol 2003). Nigeria is another case in point. Up to the late 1990’s the telecommunications scenario in Nigeria was appalling, with few people connected to the fixed line network. The introduction of cellular technology and the issuance of licenses to cellular network operators have leapfrogged the telecommunications market enormously. With a highest population figure in Africa, Nigeria has the potential to be the largest cellular market in Africa.
Some of the reasons accountable for cellular boom are:

• The possibility of wireless technology to reach every nook and cranny in a locale. It has circumvented the physical connection of laying telecommunication cables typical of the fixed line network. The wireless technology has become very appropriate for most developing countries, where millions of people reside in the rural areas unreachable by the fixed line network
• The ease of use of the cellular phone. The portability, the mobility and the ubiquity that the cellular phone offers
• The prepaid technology. This also contributes to the ease of use of the cellular phone. Subscribers can design their use to suit their financial capabilities.
• The development of the Global System for Mobile Communication (GSM) and the international / global compatibility for cellular communication.

The improvement in wireless technology is not limited to the cellular technology. Advancement in satellite, fixed mobile, microwave technologies and WIFI technologies have all contributed to the revolution in the telecommunications sector.

Figure 3: Advancement in wireless technologies has brought telecommunication services, such as the cellular phone, to numerous people who are not reached by the fixed line

Picture: vodacom/Sunday Times