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TELECOMMUNICATIONS AND NETWORKS

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Telecommunications: the electronic transmission of signals for ... Low earth obit (LEO) - 400 to 1,000 miles. Radio. High bandwidth. Marina G. Erechtchoukova ... – PowerPoint PPT presentation

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Title: TELECOMMUNICATIONS AND NETWORKS


1
CHAPTER 4
  • TELECOMMUNICATIONSAND NETWORKS

2
Basic Definitions
  • Telecommunications the electronic transmission
    of signals for communications
  • Telecommunications medium anything that carries
    an electronic signal and interfaces between a
    sending device and a receiving device

3
The Components of Telecommunications Systems
  • Hardware
  • Sending/receiving unit
  • Computers, Telephones, Fax, Radio sets, TV sets
  • Telecommunications devices
  • Telecommunications media
  • Telecommunications network

4
The Components of Telecommunications Systems
(cont)
  • Communications software
  • Communications protocols
  • Communications applications
  • E-mail
  • Facsimile
  • EDI, EFT.
  • Communications provider

5
The Components of Telecommunications Systems
Telecommunications Device
Telecommunications Device
Receiving Unit
Sending Unit
Communications Channels and Media
Receiver
Transmitter
6
Data and Signals
  • Data
  • Raw facts
  • Static
  • Signals
  • Transmit data
  • Dynamic
  • Data and signals may be digital or analog

7
Digital and Analog Data
  • Analog data is represented as continuous waveform
  • Example audio tape
  • Digital data is computer data sequence of
    binary 0s and 1s
  • Example data stored on the hard drive

8
Analog vs. digital signals
9
Signals
  • Analog signals
  • Amplitude height of wave above or below a
    reference point
  • Frequency a number of oscillations per time
    unit
  • Phase determines the shift in time when wave
    obtains maximal value
  • Digital signals
  • Baud rate

10
Data Transmission
  • Digital data using digital signals
  • Encoding
  • Digital data using analog signals
  • Modulation
  • Analog data using digital signals
  • Pulse code modulation
  • Analog data using analog signals
  • AM, FM radio, broadcast television

11
Telecommunications Devices
  • Modem
  • an analog network is used to transmit digital
    data
  • Fax modem
  • Transmits images via standard telephone line
  • Multiplexer
  • an electronic device that allows a single
    communications channel to carry data transmitted
    simultaneously from many sources
  • Private Branch Exchange
  • a private telephone network used within an
    organization. Users of the PBX share a certain
    number of outside lines for making telephone
    calls external to the PBX.

12
Media for Data Transmission
  • Conducted (cable) media
  • Twisted-pair wire
  • Coaxial cable
  • baseband transmission a single signal is used
  • broadband transmission available medium is
    divided into multiple channels.
  • Fiber optic cable
  • Wireless transmitting

13
Wireless Media
14
Wireless Media (continued )
  • Terrestrial microwave
  • Satellite - digital transmission
  • Geostationary earth orbit (GEO) - 22,300 miles
  • Medium earth orbit (MEO) - 6,000 miles
  • Low earth obit (LEO) - 400 to 1,000 miles
  • Radio
  • High bandwidth

15
Wireless Media (continued )
  • Cellular radio technology
  • transfers calls from one cell to another
  • Mobile computing
  • occurs on radio-based networks that transmit data
    to and from mobile computers
  • Personal communications services
  • use lower-power and higher-frequency means
  • Infrared
  • commonly used in remote control units

16
Data Communications Links
  • Switched Lines
  • Telephone lines
  • Message is routed by switches from a sender to a
    receiver
  • Dedicated Lines
  • provide a constant connection between two devices
    and require no switching or dialing

17
Telecommunications Carriers
  • Local exchange carrier (LEC) a public telephone
    company that provides service to homes and
    businesses within its defined geographical area
  • Competitive local exchange carrier (CLEC) a
    company that is allowed to compete with the LECs,
    such as a wireless, satellite, or cable service
    provider
  • Long-distance carrier a traditional
    long-distance phone provider, such as ATT,
    Sprint, or MCI

18
Telecommunications Services
  • Telephone and Dialing Services
  • Integrated Services Digital Network (ISDN)
  • transfer data in different formats simultaneously
  • Digital Subscriber Lines (DSL)
  • provide high-speed, digital data transmission
  • Cable modem
  • T1
  • Very fast broadband service
  • Wireless data communications

19
Networks
  • Personal Area Networks interconnect IT devices
    within 33 feet
  • Local Area Networks connect two or more
    communications devices within 2,000 feet
  • Metropolitan Area Networks networks that serve an
    area of 3 to 30 miles
  • Wide Area Networks large networks that serve
    large geographical regions
  • International Networks link systems between
    countries

20
Computer Networks
  • Computer network computers and the
    communications media, devices, and software
    needed to connect two or more computer systems or
    devices
  • Network nodes the computers and/or devices on
    the networks

21
Network Communications Software
  • Functions
  • Message formatting
  • Error checking
  • Communications log
  • Data security
  • Translation
  • Main groups
  • Network Operating Systems
  • Protocols
  • Network Management Software

22
Protocols
  • NOS refers to a protocol to implement data
    transmission
  • Protocol set of rules for data exchange
  • Main conceptual components
  • Syntax
  • Semantics
  • Timing

23
Protocol Functions
  • Line access
  • To avoid collisions
  • Device identification in the communications path
  • Detection of transmission errors
  • Recovery after errors
  • Verification of correct transmission

24
OSI Model
  • Open Systems Interconnection network
    architecture model
  • Consists of layers
  • Each layer describes the services provided.

25
Seven Layers of the OSI Model
26
A mnemonic for remembering the layers of the OSI
Model
27
Devices Connecting Networks
  • Bridges connect LANs of the same type
  • Switches rout incoming signals from input ports
    to output ports
  • Routers connect LANs and WANs, route messages
    through the network
  • Hubs receive signals from a sending unit and
    retransmit the signals to all connected units
  • Gateways connect dissimilar networks

28
Types of Data Processing in Organizations
  • Centralized processing all processing occurs in
    a single location or facility
  • Decentralized processing processing devices are
    placed at various remote locations
  • Distributed processing computers are placed at
    remote locations but connected to each other via
    a network

29
Types of Distributed Data Processing in the
Organizations
  • Terminal-to-Host Processing
  • Peer-to-peer processing
  • File Server Processing
  • Client/Server Architecture and Processing

30
Client/Server Configuration
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