MOBILE COMMUNICATIONS

Mobile communications marks a technological shift in traditional communication given the popularity of advanced communication devices and the decentralized infrastructure network behind them. For example, mobile technology is playing an increasingly important role in the preparedness and quick response of emergency units when attending to natural disasters that strike in different parts of the world, thereby increasing the reach and effectiveness of an emergency response team when first learning about a disaster and subsequently calling others for help.
The introduction of mobile communication technology has had its largest impact in the developing world where the traditional landline telephone infrastructure was largely underdeveloped, which lead to sparse and unreliable service. Advances in satellite technology have made it possible for mobile phone service to reach just about every corner of the world where satellite transmissions can be received. Moreover, small business owners in many communities globally have made the decision to run their businesses exclusively through the use of mobile communication technologies, which are often more accessible and inexpensive compared to traditional phone technologies within rural areas. Text messaging, also known as Short Message Service (SMS), has become one of the most common ways of communicating throughout the world. In places where mobile phone calls are more expensive, text messaging is a cheap and effective alternative to communicating with others via mobile communication technology. The cost of messaging and talking to people wirelessly is significantly lower than traditional phone use (generally speaking) given that only a minimal amount of infrastructure is required to support widespread usage. For example, mobile phones opposed to traditional landline telephones do not require the installation of phone cables across long stretches of land, which can be very expensive and environmentally damaging. Beyond their impact on individual members of the global community, mobile phones are playing an important role in the transmission of vital information during many local and global protests and social movements. For example, text messaging played a major role in a number of large protests, from the 1999 anti-WTO protests in Seattle, to protests of a million Filipinos against President Estrada, to a series of anti-Japanese protests in China in 2005. In China in particular, news of the protests was censored from government-controlled media, which included mobile phone calls, leaving text messaging as one of the only forms of communication available. The use of text messages to aid and assist the communication of information for the purposes of protest is commonly referred to as smart mobs.

MODERN OPERATION

Optical fiber provides cheaper bandwidth for long distance communication
In an analogue telephone network, the caller is connected to the person he wants to talk to by switches at various telephone exchanges. The switches form an electrical connection between the two users and the setting of these switches is determined electronically when the caller dials the number. Once the connection is made, the caller's voice is transformed to an electrical signal using a small microphone in the caller's handset. This electrical signal is then sent through the network to the user at the other end where it is transformed back into sound by a small speaker in that person's handset. There is a separate electrical connection that works in reverse, allowing the users to converse.
The fixed-line telephones in most residential homes are analogue — that is, the speaker's voice directly determines the signal's voltage. Although short-distance calls may be handled from end-to-end as analogue signals, increasingly telephone service providers are transparently converting the signals to digital for transmission before converting them back to analogue for reception. The advantage of this is that digitized voice data can travel side-by-side with data from the Internet and can be perfectly reproduced in long distance communication (as opposed to analogue signals that are inevitably impacted by noise).
Mobile phones have had a significant impact on telephone networks. Mobile phone subscriptions now outnumber fixed-line subscriptions in many markets. Sales of mobile phones in 2005 totalled 816.6 million with that figure being almost equally shared amongst the markets of Asia/Pacific (204 m), Western Europe (164 m), CEMEA (Central Europe, the Middle East and Africa) (153.5 m), North America (148 m) and Latin America (102 m). In terms of new subscriptions over the five years from 1999, Africa has outpaced other markets with 58.2% growth. Increasingly these phones are being serviced by systems where the voice content is transmitted digitally such as GSM or W-CDMA with many markets choosing to depreciate analogue systems such as AMPS.
There have also been dramatic changes in telephone communication behind the scenes. Starting with the operation of TAT-8 in 1988, the 1990s saw the widespread adoption of systems based on optic fibres. The benefit of communicating with optic fibres is that they offer a drastic increase in data capacity. TAT-8 itself was able to carry 10 times as many telephone calls as the last copper cable laid at that time and today's optic fibre cables are able to carry 25 times as many telephone calls as TAT-8. This increase in data capacity is due to several factors: First, optic fibres are physically much smaller than competing technologies. Second, they do not suffer from crosstalk which means several hundred of them can be easily bundled together in a single cable. Lastly, improvements in multiplexing have led to an exponential growth in the data capacity of a single fibre.
Assisting communication across many modern optic fibre networks is a protocol known as Asynchronous Transfer Mode (ATM). The ATM protocol allows for the side-by-side data transmission mentioned in the second paragraph. It is suitable for public telephone networks because it establishes a pathway for data through the network and associates a traffic contract with that pathway. The traffic contract is essentially an agreement between the client and the network about how the network is to handle the data; if the network cannot meet the conditions of the traffic contract it does not accept the connection. This is important because telephone calls can negotiate a contract so as to guarantee themselves a constant bit rate, something that will ensure a caller's voice is not delayed in parts or cut-off completely. There are competitors to ATM, such as Multiprotocol Label Switching (MPLS), that perform a similar task and are expected to supplant ATM in the future.

BASIC ELEMENTS

A basic telecommunication system consists of three elements:
a transmitter that takes information and converts it to a signal;
a transmission medium that carries the signal; and,
a receiver that receives the signal and converts it back into usable information.
For example, in a radio broadcast the broadcast tower is the transmitter, free space is the transmission medium and the radio is the receiver. Often telecommunication systems are two-way with a single device acting as both a transmitter and receiver or transceiver. For example, a mobile phone is a transceiver.
Telecommunication over a telephone line is called point-to-point communication because it is between one transmitter and one receiver. Telecommunication through radio broadcasts is called broadcast communication because it is between one powerful transmitter and numerous receivers.

EARLY TELECOMMUNICATIONS

Early telecommunications included smoke signals and drums. Drums were used by natives in Africa, New Guinea and South America, and smoke signals in North America and China. Contrary to what one might think, these systems were often used to do more than merely announce the presence of a camp.
In 1792, a French engineer, Claude Chappe built the first visual telegraphy (or semaphore) system between Lille and Paris. This was followed by a line from Strasbourg to Paris. In 1794, a Swedish engineer, Abraham Edelcrantz built a quite different system from Stockholm to Drottningholm. As opposed to Chappe's system which involved pulleys rotating beams of wood, Edelcrantz's system relied only upon shutters and was therefore faster. However semaphore as a communication system suffered from the need for skilled operators and expensive towers often at intervals of only ten to thirty kilometres (six to nineteen miles). As a result, the last commercial line was abandoned in 1880.

HISTORY OF TELECOMMUNICATION

The history of telecommunication began with the use of smoke signals and drums in Africa, the Americas and parts of Asia. In the 1790s the first fixed semaphore systems emerged in Europe however it was not until the 1830s that electrical telecommunication systems started to appear. This article details the history of telecommunication and the individuals who helped make telecommunication systems what they are today. History of telecommunication is an important part of the larger history of communication.

TELECOMMUNICATION

Telecommunication is the assisted transmission over a distance for the purpose of communication. In earlier times, this may have involved the use of smoke signals, drums, semaphore, flags or heliograph. In modern times, telecommunication typically involves the use of electronic devices such as the telephone, television, radio or computer. Early inventors in the field of telecommunication include Alexander Graham Bell, Guglielmo Marconi and John Logi Baird. Telecommunication is an important part of the world economy and the telecommunication industry's revenue was estimated to be $1.2 trillion in 2006.