Telecommunication and networks
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This document defines basic concepts of telecommunications and networks. It describes different types of communication including synchronous, where the receiver gets the message immediately, and asynchronous, where there is a delay. It also defines telecommunications as electronic communication of signals like telephone, radio and television. The document outlines different types of telecommunications media including twisted pair cable, coaxial cable, fiber optic cable, microwave transmission, and wireless transmission. It provides details on characteristics of each type of media such as speed and applications.
Telecommunication and networks
- 2. Telecommunications and Networks, describes basic concepts and components of networks used for data communications. Communications is defined as the transmission of a signal over a medium from a sender to a receiver.
- 4. Communication FlowCommunication Flow Synchronous communicationSynchronous communication Asynchronous communicationAsynchronous communication
- 5. Synchronous CommunicationSynchronous Communication In synchronous communication, the receiver gets the message immediately. Telephone conversations are examples of synchronous communication
- 6. Asynchronous CommunicationAsynchronous Communication asynchronous communication, the receiver gets the message at a late time – possibly even days after the message is sent. Sending a letter is an example of asynchronous communication, as is e- mail.
- 8. TelecommunicationsTelecommunications TelecommunicationsTelecommunications is the electronicis the electronic communication of signals, such ascommunication of signals, such as telephone, radio and television.telephone, radio and television. Data communications is a subset ofData communications is a subset of telecommunications referring to thetelecommunications referring to the electronic collection, processing, &electronic collection, processing, & distribution of data.distribution of data.
- 9. Telecommunications MediaTelecommunications Media BandwidthBandwidth The range of frequencies that an electronicThe range of frequencies that an electronic signal occupies on a given transmissionsignal occupies on a given transmission medium.medium. BroadbandBroadband Telecommunications in which a wide band ofTelecommunications in which a wide band of frequencies is available to transmitfrequencies is available to transmit information, allowing more information to beinformation, allowing more information to be transmitted in a given amount of time.transmitted in a given amount of time.
- 10. Data Transmission SpeedsData Transmission Speeds Measured in bits per second (bps)Measured in bits per second (bps) Kilobits per second (kbps)Kilobits per second (kbps) Megabits per second (Mbps)Megabits per second (Mbps) Gigabits per second (Gbps)Gigabits per second (Gbps)
- 11. Data communications is characterized byData communications is characterized by the speed at which the data is sent,the speed at which the data is sent, measured in bits per second. The mostmeasured in bits per second. The most common data transmission speeds rangecommon data transmission speeds range from thousands to millions of bits perfrom thousands to millions of bits per second, or kilobits to megabits persecond, or kilobits to megabits per second. Some networks can supportsecond. Some networks can support transmission of billions of bits, or gigabits,transmission of billions of bits, or gigabits, per second.per second.
- 12. Computer NetworksComputer Networks Telecommunications mediaTelecommunications media Telecommunications devicesTelecommunications devices SoftwareSoftware Hardware devicesHardware devices
- 13. Types of MediaTypes of Media Twisted-PairTwisted-Pair Coaxial CableCoaxial Cable Fiber-Optic CableFiber-Optic Cable Microwave TransmissionMicrowave Transmission
- 14. The first 3 types of media – twisted pair,The first 3 types of media – twisted pair, coaxial cable, and fiber optic cable – arecoaxial cable, and fiber optic cable – are usually referred to asusually referred to as guided or conductedguided or conducted media.media. That is, a signal is conducted overThat is, a signal is conducted over a physical medium.a physical medium. Microwave and other forms of wirelessMicrowave and other forms of wireless transmission are called broadcast media.transmission are called broadcast media.
- 15. Twisted-Pair Wire CableTwisted-Pair Wire Cable
- 16. Twisted-Pair Wire CableTwisted-Pair Wire Cable consisted of pairs of twisted copper wireconsisted of pairs of twisted copper wire used for both analogue and digital transmissionused for both analogue and digital transmission low in costlow in cost low in transmission speedlow in transmission speed
- 17. Twisted pair cabling is made of pairs of copper wires twisted together. Twisted pair is used for the phone connection to your house. In networking it is common to see cable consisting of 4 pairs of wires. Each pair is twisted together to reduce electrical interference between neighboring pairs, or crosstalk. The more twists there are per foot, the less interference there will be. Twisted pair is classified by the number of twists per foot. Data grade cable has more twists per foot than does voice grade cable. Shielded twisted pair cabling includes additional shielding against external electro-magnetic interference. Unshielded twisted pair, although it doesn’t have the extra shielding, is used more often because of its lower costs and greater practicality.
- 19. Coaxial CableCoaxial Cable A thick insulated copper wireA thick insulated copper wire Can transmit large volumes of data quicklyCan transmit large volumes of data quickly Faster and more interference free mediumFaster and more interference free medium Speed up to 200MB per secondSpeed up to 200MB per second Cannot support analogue phoneCannot support analogue phone conversationsconversations
- 20. Like twisted pair, coaxial cable, or “co-ax”, is also made from copper. However, because of extra shielding and insulation, coax has less interference, and therefore a higher capacity, or bandwidth, than does twisted pair. Data can be sent over coax at about 500 Mbps, whereas data transmission speeds over twisted pair for long distances are typically well below that, although in a local area network fast speeds can be attained using twisted pair.
- 21. A type of coaxial cable is used for cable TV to your home. Cable modems can be used for Internet access several hundreds as times as fast as a modem and dial-up phone line.
- 22. Fiber Optic CableFiber Optic Cable
- 23. Fiber optic cableFiber optic cable Consists of strands of clear glass fiberConsists of strands of clear glass fiber Has the thickness of a human hairHas the thickness of a human hair Data are transformed into pulses of lightData are transformed into pulses of light Rate 500kb – several trillion bit per secondRate 500kb – several trillion bit per second
- 24. Fiber optic cableFiber optic cable Faster lighter and more durable than wireFaster lighter and more durable than wire mediamedia Suitable to transfer large volumes of dataSuitable to transfer large volumes of data More expensiveMore expensive
- 25. Fiber optic cableFiber optic cable Difficult to work withDifficult to work with Harder to installHarder to install Used for backbone cablingUsed for backbone cabling that handle the major trafficthat handle the major traffic a primary patha primary path No delays and no degradation in qualityNo delays and no degradation in quality
- 26. Unlike twisted pair and coax, fiber optic cable is made of thin filaments of glass or plastic, not of copper wire. Whereas a data signal travels over twisted pair or cable as electricity, signals are transmitted as light pulses over fiber. Lasers or LCDs produce the light. A thin coating, called cladding, prevents the light from leaving the strand. Also unlike copper media, fiber is not vulnerable to electro-magnetic interference.
- 27. Fiber has a much higher bandwidth than does copper media – that is, it can carry more data faster. Fiber can have a capacity of billions of bits per second. Fiber is also the most secure medium around today. The biggest drawback of fiber is that labor costs to install and repair fiber are very high.
- 29. MicrowaveMicrowave High frequency radio signals areHigh frequency radio signals are transmitted trough the atmosphere fromtransmitted trough the atmosphere from one terrestrial transmission station toone terrestrial transmission station to anotheranother A high volumeA high volume long distancelong distance point – to – point transmission methodpoint – to – point transmission method
- 30. The expense of physical media can be great. Whereas broadcast media, such as microwave, don’t require the purchase of physical media, the hardware required is more expensive. Microwave is a high frequency radio signal. In terrestrial microwave, a signal travels directly between microwave transmission towers. This requires an unobstructed straight path between towers. Also, due to the curvature of the earth, towers must be spaced about 30 miles apart.
- 32. Satellite transmission involves sending a signal from a microwave tower to the satellite, which is basically a microwave station, then back to another microwave tower. Although this eliminates the need for a line-of- sight between towers, the delays to upload and download the signal often make satellite transmission impractical for sending signals short distance.
- 33. Wireless transmissionWireless transmission Sends signals through air or spaceSends signals through air or space Technologies includeTechnologies include microwave transmissionmicrowave transmission communication satellitescommunication satellites pagerspagers cellular phonescellular phones smart phonessmart phones PDAsPDAs
- 34. Infrared TransmissionInfrared Transmission Line of sightLine of sight Short distancesShort distances Infrared transmission can be used to send data short distances, for example, from a handheld computer to a desktop or a printer. Infrared transmission can also be used to connect peripherals, such as a mouse, to a computer.
- 35. Telecommunications DevicesTelecommunications Devices Telecommunications devices areTelecommunications devices are hardware that make an electronichardware that make an electronic transmission occur or make it moretransmission occur or make it more efficient.efficient. Modems, multiplexers, and front-endModems, multiplexers, and front-end processors are examples ofprocessors are examples of telecommunications devices.telecommunications devices.
- 36. ModemsModems Analog signals: continuousAnalog signals: continuous Digital signals: discreteDigital signals: discrete Modulation: translating digital data toModulation: translating digital data to analoganalog Demodulation: translating analog data toDemodulation: translating analog data to digitaldigital Modems modulate & demodulate dataModems modulate & demodulate data
- 37. Often, data is sent over the regularOften, data is sent over the regular telephone network, which transmits analogtelephone network, which transmits analog signals.signals. An analog signal is a continuous signal;An analog signal is a continuous signal; the transmission line varies smoothlythe transmission line varies smoothly among an infinite number of states.among an infinite number of states. Analog waves can carry a continuousAnalog waves can carry a continuous range of datarange of data
- 38. computers produce digital signals. Digitalcomputers produce digital signals. Digital signals send discrete pulses andsignals send discrete pulses and represent a limited number of states.represent a limited number of states. In the case of a computer, two states areIn the case of a computer, two states are represented.represented.
- 39. In order to send a digital signal over anIn order to send a digital signal over an analog line, the signal must first beanalog line, the signal must first be modulated, or changed to a form that canmodulated, or changed to a form that can be carried over an analog line. When thebe carried over an analog line. When the signal is received, it must be demodulatedsignal is received, it must be demodulated so the computer can understand it.so the computer can understand it. This is what a modem does.This is what a modem does.
- 42. MultiplexersMultiplexers are devices that combineare devices that combine signals from several computers to allowsignals from several computers to allow them to be sent over a single transmissionthem to be sent over a single transmission line.line.
- 43. Networks & DistributedNetworks & Distributed ProcessingProcessing Telecommunications networks areTelecommunications networks are becoming increasingly important sincebecoming increasingly important since they allow work to be done wherever andthey allow work to be done wherever and whenever it is most advantageous. Data,whenever it is most advantageous. Data, software, hardware, and other resourcessoftware, hardware, and other resources are becoming ubiquitous – that is, easilyare becoming ubiquitous – that is, easily accessible by anyone, anytime, any place.accessible by anyone, anytime, any place.
- 44. Basic Processing StrategiesBasic Processing Strategies Centralized processingCentralized processing Decentralized processingDecentralized processing Distributed processingDistributed processing
- 45. There are 3 basic processing strategies whenThere are 3 basic processing strategies when more than 2 computer systems are used.more than 2 computer systems are used. In centralized processingIn centralized processing, all processing is, all processing is done at one location. This is the easiestdone at one location. This is the easiest strategy for the IS department to control and isstrategy for the IS department to control and is appropriate when an enterprise needs a highappropriate when an enterprise needs a high level of security.level of security.
- 46. In decentralized computingIn decentralized computing, different locations, different locations have their own processing devices. Devices athave their own processing devices. Devices at different locations aren’t connected together.different locations aren’t connected together. This strategy works well when there areThis strategy works well when there are independent operating units and no dataindependent operating units and no data interchange between units.interchange between units.
- 47. In distributed processingIn distributed processing, computers at, computers at different locations are connected by adifferent locations are connected by a communications network. Data and processingcommunications network. Data and processing are located where it is most efficient andare located where it is most efficient and effective. For example, data and programs usedeffective. For example, data and programs used most by the Miami office would be located inmost by the Miami office would be located in Miami, and those used most by the Boston officeMiami, and those used most by the Boston office would be in Boston. Users at both locationswould be in Boston. Users at both locations could access data and programs at the othercould access data and programs at the other site when needed.site when needed.
- 48. Network Concepts &Network Concepts & ConsiderationsConsiderations Network topologyNetwork topology Network typesNetwork types Local Area NetworksLocal Area Networks Wide Area NetworksWide Area Networks International networksInternational networks Home & small business networksHome & small business networks
- 49. Network TopologyNetwork Topology Network topology describes how aNetwork topology describes how a network is logically organized – that is,network is logically organized – that is, how the data flows in the network.how the data flows in the network. Depending on the distance betweenDepending on the distance between nodes and the services provided,nodes and the services provided, networks may be classified as local areanetworks may be classified as local area networks or wide area networks.networks or wide area networks.
- 51. A bus network contains devices connectedA bus network contains devices connected directly in a straight line. Each device candirectly in a straight line. Each device can communicate directly with every othercommunicate directly with every other device one the network.device one the network.
- 52. RingRing
- 53. In a ring network, devices are connectedIn a ring network, devices are connected in a ring and message are routed aroundin a ring and message are routed around the ring from one device to the next.the ring from one device to the next. In bus and ring topologies, there is noIn bus and ring topologies, there is no central coordinating computer.central coordinating computer.
- 54. StarStar
- 55. A star network has a central, coordinatingA star network has a central, coordinating device; each computer on the network isdevice; each computer on the network is directly attached only to the central device.directly attached only to the central device. The central device is the vulnerability ofThe central device is the vulnerability of the network – it can become a bottleneckthe network – it can become a bottleneck under heavy traffic and the whole networkunder heavy traffic and the whole network fails if it fails.fails if it fails.
- 56. Network TypesNetwork Types Logical Area Network (LAN)Logical Area Network (LAN) Limited geographical areaLimited geographical area Any topology possibleAny topology possible Network Interface Card (NIC)Network Interface Card (NIC) DesignsDesigns Peer-to-peerPeer-to-peer Client-serverClient-server Wide Area Network (WAN)Wide Area Network (WAN)
- 57. LANLAN Local Area Networks connect processingLocal Area Networks connect processing devices within a limited geographic areadevices within a limited geographic area and do not usually use common carrierand do not usually use common carrier facilities.facilities. Devices are attached to the media usingDevices are attached to the media using network interface cards, also callednetwork interface cards, also called network adaptersnetwork adapters..
- 58. WANWAN Wide Area Networks connect devices overWide Area Networks connect devices over large geographic distances using commonlarge geographic distances using common carrier facilities. Companies may usecarrier facilities. Companies may use wide area networks provided by others,wide area networks provided by others, such as AT&T long distance service orsuch as AT&T long distance service or may deploy their own WAN usingmay deploy their own WAN using enterprise facilities along with commonenterprise facilities along with common carrier facilities.carrier facilities.