Prepared by: Ellicia Chen
University of Central
Oklahoma
Edmond, Oklahoma
Contents:
· Types of Telecommunications
Network
· Telecommunications Media
· Telecommunications
Processors
· Telecommunications Network
Topologies
Managers, end users, and organizations need to electronically exchange data and information with other end users, customers, suppliers, and other organizations. Many organizations today could not survive without interconnected networks of computers to service the information processing and communications need of their end users.
Telecommunications is the sending of information in any form of voice, data, text and images from one place to another using electronic or light-emitting media. Data communications is a more specific term that describes the transmitting and receiving of data over communication links between one or more computer systems and a variety of input/output terminals. All forms of telecommunications rely heavily on computers and computerized devices.
Major trends occurring in the field of telecommunications have a significant impact on management decisions.
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Industry Trends
The competitive arena for telecommunications service has changed dramatically in the United States, from a few government regulated monopolies to many fiercely competitive suppliers of telecommunications services. Local and global telecommunications networks and services became available from a variety of large and small telecommunications companies. The services and vendor options available to meet a company’s telecommunications needs have increased significantly.
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Technology Trends
Telecommunications is being revolutionized by a change from analog to digital network technologies. Local and global telecommunications networks are rapidly converting to digital transmission technologies, which transmit information in the form of discrete pulses, as computers do. This provides significantly higher transmission speeds, the movement of larger amounts of information, greater economy, and much lower error rates than analog systems. Another major trend in telecommunications technology is a change in communications media. Many telecommunications networks are switching from copper wire-based media and land-based microwave relay systems to fiber optic lines and communications satellite transmission.
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Application Trends
The trend towards more vendors, services, advanced technologies, and open system dramatically increases the number of feasible applications. Telecommunications is playing a more important role in support of the operations, management, and strategic objectives of both large and small companies. It has become an integral part of local and global networks of computers which are used to cut costs, improve the collaboration of work groups, develop online operational process, share resources, lock in customers and suppliers, and develop new products and services.
Types of Telecommunications Networks
There are many different types of telecommunications networks and the two basic types are wide area networks (WANs) and local area networks (LANs). Telecommunications networks covering a large geographic are called wide are networks (WANs). Such large networks have become a necessity for carrying out the day-to-day activities of many business and government organizations and their end users. WANs are used by manufacturing firms, banks, retailers, distributors, transportation companies, and government agencies to transmit and receive information among their employees, customers, suppliers, and other organizations across cities, regions, countries, or the world.
Local are networks (LANs) connect computers and other information processing devises within a limited physical area, such as an office, a building, manufacturing plant, or other work site. LANs have become commonplace in many organizations for providing telecommunications network capabilities that link end users in offices, departments, and other work groups. LANs use a variety of telecommunications media, such a ordinary telephone wiring, coaxial cable, or even wireless radio systems to interconnect microcomputer workstations and computer peripherals. To communicate over the network, each PC must have a circuit board installed called a network interface card. LANs allow end users in a work group to communicate electronically; share hardware, software, and data resources; and pool their efforts when working on group projects. LANs rely on internetwork processors, such as bridges, routers, hubs, or gateways, to make internetworking connections to other LANs and WANs. The goal of such internetwork architectures is to create a seamless network of networks within each organization and between organizations that have business relationship.
Telecommunications Media
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Twisted-Pair Wire
Ordinary telephone wire, consisting of copper wire twisted into pairs, is the most widely used media for telecommunications. These lines are used in established communications networks throughout the world for both voice and data transmission. Twisted-pair wiring is used extensively in home and office telephone system and many local area networks and wide area networks.
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Coaxial Cable
Coaxial cable consists of a sturdy copper or aluminum wire wrapped with spacers to insulate and protect it. The cable’s cover and insulation minimize interference and distortion of the signals the cable carries. Groups of coaxial cables may be bundled together in a big cable for ease of installation. These high-quality lines can be placed underground and laid on the floors of lakes and oceans. They allow high-speed data transmission and can be used extensively in office buildings and other work sites for local area networks.
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Fiber Optics
Fiber optics uses cable consisting of one or more hair- thick filaments of glass fiber wrapped in a protective jacket. Fiber optics cable provides substantial size and weight reductions as well as increased speed and greater carrying capacity. Fiber optic cables are not affected by and do not generate electromagnetic radiation; therefore, multiple fibers can be placed in the same cable. Fiber optics also has a much lower data error rate than other media and is harder to tap than electrical wire and cable.
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Terrestrial Microwave
Terrestrial microwave involves earthbound microwave systems, which transmit high-speed radio signals in a line-of-sight path between relay stations spaced approximately 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks, and they are a familiar sight in many sections of the country.
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Communications Satellites
There are several dozen communications satellites from several nations placed into stationary geosynchronous orbits approximately 22,000 miles above the equator. Satellites are powered by solar panels and can transmit microwave signals at a rate of several hundred bits per second. Earth stations use dish antennas to beam microwave signals to the satellites, which amplify and retransmit the signals to other earth stations thousands of miles away.
Telecommunications Processors
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Modems
Modems are the most common type of communication processor. They convert the digital signals from a computer or transmission terminal at one end of a communications link into analog frequencies, which can be transmitted over ordinary telephone lines. A modem at the other end of the communications line converts the transmission data back into digital form at a receiving terminal. This process is known as modulation and demodulation.
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Multiplexers
A multiplexer is a communications processor that allows a single communications channel to carry simultaneously data transmission from many terminals. A single communications line can be shared by several terminals. In frequency division multiplexing (FDM), a multiplexer effectively divides a high-speed channel into multiple slow-speed channels. In time division multiplexing (TDM), the multiplexer divide the time each terminal can use high-speed line into very short time slots, or time frames.
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Internetwork Processors
Many local area networks are interconnected by internetwork processors such as bridge, routers, hubs, or gateways to other LANs or WANs. A bridge is a communications processor that connects two similar LANs that is LANs based on the same network standards or protocols. A router is a communications processor that connects LANs to networks based on different protocol. A hub is a port switching communications processor. Networks that use different communications architectures are interconnected by using a communications processor called a gateway.
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Private Branch Exchange
The private branch exchange (PBX) is a communications processors that serves as a switching device between the telephone lines within a work are and the local telephone company’s main telephone lines, or trunks. They not only route telephone calls within an office but also provide other services, such as automatic forwarding of calls, conference calling, and least-cost routing of long-distance calls. Some PBX can integrate the switching of voice, data, and images in integrated digital services networks (ISDN).
Telecommunications Network Topologies
There are three basic topologies used in WANs and LANs telecommunications networks. A star network ties end user computers to a central computer. In a ring network, local computer processors are tied together in a ring on a more equal basis. A bus network is a network in which local processors share the same bus, or communications channel. Star networks take the form of hierarchical networks. A variation of the ring network is the mesh network that uses direct communications lines to connect some or all of the computers in the ring to each other. Another variation is the tree network, which joins several bus networks together. The star network is more centralized, while ring and bus networks have a more decentralized approach.