1 / 36

Computer Communication & Networks

Computer Communication & Networks. Lecture 8 Physical Layer: Transmission Media http://web.uettaxila.edu.pk/CMS/coeCCNbsSp09/index.asp. Waleed Ejaz waleed.ejaz@uettaxila.edu.pk. Physical Layer. Physical Layer Topics to Cover. Signals. Digital Transmission. Analog Transmission.

elroy
Télécharger la présentation

Computer Communication & Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Computer Communication & Networks Lecture 8 Physical Layer: Transmission Media http://web.uettaxila.edu.pk/CMS/coeCCNbsSp09/index.asp Waleed Ejaz waleed.ejaz@uettaxila.edu.pk

  2. Physical Layer

  3. Physical Layer Topics to Cover Signals DigitalTransmission AnalogTransmission Multiplexing TransmissionMedia

  4. Transmission Medium and Physical Layer

  5. Twisted-pair Cable

  6. Categories of unshielded twisted-pair cables

  7. Twisted Pair Cable (a) Category 3 UTP (b) Category 5 UTP

  8. UTPconnector

  9. Twisted Pair Cables (Example) • ADSL • Ethernet networks - 10BASE-T - 100BASE-TX - 1000BASE-T - 1000BASE-TX (Cat5e (enhanced))

  10. UTP Performance

  11. Twisted Pair Cable (Pros & Cons) Pros: • easy to understand • mass production - low cost • most widely used medium Cons: • prone to electromagnetic interference • in power plants, airport buildings, military facilities, cars… Note: In-building networks at our university are almost all twisted pair

  12. Coaxial cable

  13. BNCconnectors

  14. Performance Coaxial Cable

  15. Bending of light ray

  16. Optical fiber

  17. Propagation Modes

  18. Modes

  19. Fiber types

  20. Fiber construction

  21. Fiber-optic Cable Connectors

  22. Performance Optical Fiber

  23. Optical Fiber (Pros & Cons) Pros: • Low attenuation • Large bandwidth Cons: • Relatively “new” technology • “Expensive”

  24. Comparing optical fiber to UTP Pros: • Immune to electro-magnetic interference • no crosstalk • Reduced need for error detection and correction • Enables longer link distances • Attenuation unaffected by transmission rate • Easier network upgrade • Can combine different services: telephony, TV, internet… Cons: • Optical components have higher cost • Expensive deploying protocols

  25. Unguided Media: Wireless • Unguided media transport electromagnetic waves without using a physical conductor. This type of communication is often referred to as wireless communication.

  26. Wireless • Modern wireless digital communication began in the Hawaiian Islands • What is “the best” frequency to use for communication?

  27. Propagation Methods

  28. Bands

  29. Wireless Transmission Waves

  30. Omni directional Antenna

  31. Note Radio waves are used for multicast communications, such as radio and television, and paging systems.

  32. Unidirectional Antennas

  33. Note Microwaves are used for unicast communication such as cellular telephones, satellite networks,and wireless LANs.

  34. Note Infrared signals can be used for short-range communication in a closed area using line-of-sight propagation.

  35. Readings • Chapter 7 (B.A Forouzan) • Section 7.1, 7.2

More Related