SC161-Lecture4-1

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SC161-Lecture4-1

  1. 1. Chapter 4 SC161: Principles of Information Technology Communication and Network Part 1: Data Communication Thiti Theerathean Center for Teaching Excellence University of the Thai Chamber of Commerce E-mail : thiti_the@utcc.ac.th
  2. 2. 2 • Introduction to Data Communication. - Data Communicationand Telecommunication - Type of Signals - The Basic Components of Communication • Data Transmission. - Line configurations - Directionof Transmisssion - TransmissionMode • Communication Channel. - Guided Media - Unguided Media • Wireless Technology. - Long-distance wireless communication - Short-range wirelesscommunication SC161: Principlesof Information Technology
  3. 3. 3SC161: Principlesof Information Technology Data Communications is any transfer of data within a computer, between a computer and another device, or between two computers. Telecommunication is communications over a distance. Tele- distance
  4. 4. 4SC161: Principlesof Information Technology Data and Information travels through a communication system in the form of eletromagnetic signals. Signals are represented in two ways • Continuous waveform. • Three basic components : - Amplitude (Volt) - Frequency (Hz) - Phase (Radian) • Infinite number of points between minimum and maximum amplitude. • Use an Amplifier to increase power for transmission over long distances and reduce noise by Filter. • Used for Voice Communication.
  5. 5. 5SC161: Principlesof Information Technology Data and Information travels through a communication system in the form of eletromagnetic signals. Signals are represented in two ways • Discrete waveform. • Only two different values: - 1 is high voltage/on electrical pulses. - 0 is low voltage/off electrical pulses. • The number of times a signal changes value per second is called “Baud rate” • Use Repeater to transmission the data over long distances. • Used for Data Communication. time amplitude(power)
  6. 6. 6SC161: Principlesof Information Technology Sender Communication Channel Receiver Step 1: …… Step 2: …... Step 3: …... Step 1: …… Step 2: …... Step 3: …... Protocol Message The Basic Components of Communication.
  7. 7. 7SC161: Principlesof Information Technology
  8. 8. 8SC161: Principlesof Information Technology There are two principal line configurations.
  9. 9. 9SC161: Principlesof Information Technology When two computers are in communication, data can flow in three ways: A B Only transmits. Only receives. A B Transmits when B receives. Transmits when A receives. A B Transmits and receives while B transmits and received. Transmits and receives while A transmits and received.
  10. 10. 10SC161: Principlesof Information Technology Data is transmitted in two ways. Sender Receiver 01110011 01110011 1 1 0 0 1 1 1 0 Sender Receiver 01110011 01110011 0 1 1 1 0 0 1 1 Bits are transmitted sequentially, one after the other. Bits are transmitted through separate lines simultaneously.
  11. 11. 11SC161: Principlesof Information Technology How does the receiving equipment know where one byte ends and another begins ? Sender Receiver 1 1 0 0 1 1 1 0 11001110 01011100 0 1 0 1 1 1 0 0 100 1 Start bit 0 Stop bit 1 Parity check bit • Start bit and Stop bit are added. • High overhead. • low-speed communication
  12. 12. 12SC161: Principlesof Information Technology How does the receiving equipment know where one byte ends and another begins ? Sender Receiver Parity check bit 1 • basic unit transmitted is called a “packet” • Use sync bytes to announce the beginning and end of an entire packet. SyncSyncSync Sync Sync byte 1 1 0 0 1 1 1 00 1 0 1 1 1 0 0 Packet 11001110 01011100
  13. 13. 13SC161: Principlesof Information Technology
  14. 14. 14SC161: Principlesof Information Technology Communication channels are the means by which data are transmitted from one device in a network to another. A channel can utilize different kinds of communication transmission media : - Twisted-Pair Cable - Coaxial Cable - Fiber Optics Cable - Infrared Transmission - Radio Frequency - Microwave and Satellite
  15. 15. 15SC161: Principlesof Information Technology Twisted-Pair Cable • Two insulated copper wires that are twisted together. • The pairs can be shielded (STP) or unshielded (UTP). • The standard connector for unshielded twisted pair cabling is an RJ-45 connector.
  16. 16. 16SC161: Principlesof Information Technology Advantages: • High availability. • Low installation cost. Disadvantages: • Limited data rates. • Limited range. • High susceptibility to electromagnetic and radio frequency interference. Twisted-Pair Cable Categories: 1 - primarily for voice, less than 9600 bps 2 - T-1 and ISBN line, 4 Mbps 3 - 16 MHz of bandwidth; 10Mbps 4 - 20 MHz of bandwidth; 16Mbps 5/5e - 100 MHz of bandwidth; 100 Mbps (4 pairs/cable) 6 - 400 MHz of bandwidth; 1Gbps (4 pairs/cable)
  17. 17. 17SC161: Principlesof Information Technology Twisted-Pair Cable
  18. 18. 18SC161: Principlesof Information Technology Coaxial Cable • A single copper wire, surrounded by an insulator and an outer conductor. • Two primary types : Thick coaxial (10mm) and Thin coaxial (4mm). • Speed : 56 kbps to 200 Mbps.
  19. 19. 19SC161: Principlesof Information Technology Coaxial Cable Advantages: • High capacity (370-1000 times more than twisted pair) • Low susceptibility to noise and crosstalk (because of shielding) Disadvantages: • Requites Amplifier or Repeater every few km. • High installation cost. Common Uses: • Cable TV (Old: RG-59; New: RG-6) • Ethernet (RG-58:10Base2 ; RG-8:10Base5) • Amateur radio.
  20. 20. 20SC161: Principlesof Information Technology Fiber Optic Cable A thin glass core surrounded by cladding that reflects light into the core, surrounded by a protective plastic buffer/jacket. • Light source is called a photo diode. • Light travels through the core and bounces off of the cladding to "make turns" • The signal degrades because of impurities in the glass cladding core
  21. 21. 21SC161: Principlesof Information Technology Fiber Optic Cable The two basic types of optical fiber. Multi-mode optical fiber Single-mode optical fiber Step-indexmultimode Graded-indexmultimode
  22. 22. 22SC161: Principlesof Information Technology Advantages: • High capacity. • Reduce size and weight cable. • no crosstalk and lower bit error rates. • Signal security and difficult to tap. Disadvantages: • Can be bent. • Each fiber is one-way transmission of data. • High cost of interfaces. • Lack of standardization.
  23. 23. 23SC161: Principlesof Information Technology Guided Media Typical use Data Rate Range Twistedpair Category 1 - 2 Category 3 - 6 Telephone system LANs Less than 2 Mbps 100 Mbps 5 km. 100 m (328 feet) Coaxial Cable Thin (Single channel) Thick (Multi channel) LANs LANs Cable TV 10 Mbps 10 Mbps 100 m. 5 km. Fiber Optic Cable Single-mode Multi-mode LANs WANs HD interconnection 10 Gbps 160 km.
  24. 24. 24SC161: Principlesof Information Technology Electromagnetic Spectrum.
  25. 25. 25SC161: Principlesof Information Technology Infrared Transmission • Using infrared-light waves at a frequency too low. • Short-range communication (no more than 5 meters) in IrDA standard. • Cannot penetrate walls and work only in the direct "line of sight" • Speed less than 4 Mbps. Radio Frequencies • Distributes radio signals through the air. • Speed more than 2 Mbps. • Long distances: cellular phone, broadcast radio and TV. • Short distances: Bluetooth and Wi-Fi
  26. 26. 26SC161: Principlesof Information Technology Microwave • Transmits data more than 45 Mbps as High frequency radio wave. • Sending signals from one microwave station to another. • Line-of-sight transmission.
  27. 27. 27SC161: Principlesof Information Technology Satellite • Microwave relay station in orbit around the earth. • Transmitting a signal from a ground station is called “uplink”, the reverse is called “downlink”
  28. 28. 28SC161: Principlesof Information Technology
  29. 29. 29SC161: Principlesof Information Technology Long-distance wireless communication The global Positioning System (GPS) consists of 24 earth-orbiting satellites continuously transmitting timed radio signals that can be used to identify earth locations.
  30. 30. 30SC161: Principlesof Information Technology Long-distance wireless communication Evolution of Mobile wireless Technology 1st Generation 2nd Generation 3rd Generation 4th Generation • Analog cellphones • Only voice communication. • Digital cellphones • launched on the GSM standard. • Voice and data service. • Standards defined by the ITU. • Voice data and multimedia communication. • High speed data rate. • Support VoIP and interactive TV.
  31. 31. 31SC161: Principlesof Information Technology Short-range wireless communication The Bluetooth is a short-range wireless digital standard aimed at linking devices via a piconet. The piconet typically has a range of about 10 m and a transfer rate between about 400 and 700 kbps.
  32. 32. 32SC161: Principlesof Information Technology Short-range wireless communication The WiFi is a short-range wireless digital standard aimed at helping devices to communicate with hi-speed at distances up to 10 m from access points. It is known formally as an 802.11 Network.
  33. 33. 33SC161: Principlesof Information Technology

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