1. 7.1 Chapter 7 Transmission Media Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 7.2 Transmission Media The transmission media lies below the Physcial Layer It can be considered the Level-0 layer in our Network Models.

3. 7.3 Figure 7.1 Transmission medium and physical layer

4. 7.4 Transmission Media Guided media Twister pair copper wire Coaxial cable Fiber optic cable Unguided media Wireless

5. 7.5 Figure 7.2 Classes of transmission media

6. 7.6 Twisted Pair The twisted pair wire One wire carries signal The other wire acts as a ground Twisting cancels out unwanted signal (noise)

7. 7.7 Figure 7.3 Twisted-pair cable

8. 7.8 Figure 7.4 UTP and STP cables

9. 7.9 Table 7.1 Categories of unshielded twisted-pair cables

10. 7.10 Figure 7.5 UTP connector

11. 7.11 Wire Guage 40 Guages Based on wire diameter Bigger wire guage number implies smaller diameter. n = -39log92( d/.005 ) + 36

12. 7.12 Wire Guage If the diameter of a wire is doubled, The guage decreases by 6. Thin wires have greater resistance Similar to a pipe carrying water.

13. 7.13 Figure 7.6 UTP performance

14. 7.14 Figure 7.7 Coaxial cable

15. 7.15 Coaxial Cable The inner conductor carries the signal. The shielding also acts as a ground.

16. 7.16 Table 7.2 Categories of coaxial cables

17. 7.17 Figure 7.8 BNC connectors

18. 7.18 Figure 7.9 Coaxial cable performance

19. 7.19 Fiber Optic Cable Capable of carrying greater bandwidth compared to copper wire. Copper wire carries frequencies below 100KHz Fiber optic carries frequencies beyond 10THz More expensive than copper wire

20. 7.20 Fiber Optic Cable Incident – incoming wave Refraction – transmitted across the boundary Reflection – reflected within the boundary Critical Angle Total internal reflection Index of refraction – a function of density

21. 7.21 Fiber Optic Cable Cladding – a transparent material less dense than the inner core of an optical cable. Prevents refraction which leads to less loss of signal

22. 7.22 Figure 7.10 Bending of light ray

23. 7.23 Figure 7.11 Optical fiber

24. 7.24 Figure 7.12 Propagation modes

25. 7.25 Figure 7.13 Modes

26. 7.26 Fiber Optic Cable Multimode step-index fiber: The sudden change in density between cable and cladding will result in some distortion of the signal.

27. 7.27 Fiber Optic Cable Multimode graded-index fiber: A gradual change in density from the cable center to the outer cladding and will result in less distortion of the signal compared to step- index fiber. Graded-index fiber is more costly

28. 7.28 Fiber Optic Cable Single-mode fiber: A narrow diameter of low index of refraction step-indexed glass fiber. A very focused beam of coherent light (similar to a laser) passes near parallel to the fiber edges.

29. 7.29 Table 7.3 Fiber types

30. 7.30 Figure 7.14 Fiber construction

31. 7.31 Figure 7.15 Fiber-optic cable connectors

32. 7.32 Figure 7.16 Optical fiber performance

33. 7.33 Fiber Optic Cable High bandwidth measured in THz Less attenuation Immunity to interference Light weight Tapping is more difficult Unidirectional Expensive compared to copper wire.

34. 7.34 7-2 UNGUIDED MEDIA: WIRELESS Unguided media transport electromagnetic waves without using a physical conductor. This type of communication is often referred to as wireless communication. Radio Waves Microwaves Infrared Topics discussed in this section:

35. 7.35 Figure 7.17 Electromagnetic spectrum for wireless communication

36. 7.36 Figure 7.18 Propagation methods

37. 7.37 Satellite Satellite is direct line of sight communication (Covered in chapter 16)

38. 7.38 Table 7.4 Bands

39. 7.39 Figure 7.19 Wireless transmission waves

40. 7.40 Multicast vs Broadcast Broadcast implies a single transmission to all. (Analog radio or analog TV broadcast) Multicast delivers data to a group of destinations simultaneously; creating copies when links to the destinations split. (guided network transmissions)

41. 7.41 Figure 7.17 Electromagnetic spectrum for wireless communication

42. 7.42 Radio Wave Properties Frequency range from 3KHz-3GHz Radio waves can pass through walls FM, AM, TV, Cell Phone, etc.

43. 7.43 Figure 7.20 Omnidirectional antenna

44. 7.44 Figure 7.21 Unidirectional antennas

45. 7.45 Figure 7.17 Electromagnetic spectrum for wireless communication

46. 7.46 Microwaves are used for unicast communication such as cellular telephones, satellite networks, and wireless LANs. Note

47. 7.47 Microwaves Range from 3GHz to 300GHz High frequency microwaves do not pass through walls The bottom of the frequency range can pass through walls Capable of high bandwidth Bluetooth is in the microwave range.

48. 7.48 Figure 7.17 Electromagnetic spectrum for wireless communication

49. 7.49 Infrared signals can be used for short- range communication in a closed area using line-of-sight propagation. Note

50. 7.50 Infrared Waves Range from 300GHz to 400THz Do not pass through walls Capable of high bandwidth Lots of bands can be created reducing the likelihood of interference from other infrared devices. Remote control devices