Chapter 7 Transmission Media Kyung Hee University 1

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Chapter 7 Transmission Media Kyung Hee University 1

Chapter 7 Transmission Media Kyung Hee University 1

7 장 Transmission media o Transmission medium and physical layer Kyung Hee University 2

7 장 Transmission media o Transmission medium and physical layer Kyung Hee University 2

Transmission media(전송매체) 7. 1 Guided Media(유도매체) 7. 2 Unguided media(비유도매체) : Wireless Kyung Hee

Transmission media(전송매체) 7. 1 Guided Media(유도매체) 7. 2 Unguided media(비유도매체) : Wireless Kyung Hee University 3

Transmission Media(cont’d) ~ Can be divided into two broad categories : 유도매체, 비 유도매체

Transmission Media(cont’d) ~ Can be divided into two broad categories : 유도매체, 비 유도매체 o. Classes of transmission media Kyung Hee University 4

7. 1 Guided Media(유도매체) o Twisted-Pair Cable • two copper conductors • one carries

7. 1 Guided Media(유도매체) o Twisted-Pair Cable • two copper conductors • one carries signals, the other is the ground reference • interference may affect both wires • receiver operates on the difference between the signals • this is why they are twisted, to maintain balance • more twists mean better quality Kyung Hee University 5

유도매체(cont’d) o. Twisted-Pair Cable ~ comes in two forms : unshielded (비 차 폐

유도매체(cont’d) o. Twisted-Pair Cable ~ comes in two forms : unshielded (비 차 폐 ) and shielded(차폐) o. UTP(Unshielded Twisted-Pair) Cable ~ is the most common type of telecommunication medium in use today. o. Frequency range for twisted-pair cable Kyung Hee University 6

유도매체(cont’d) o Twisted-Pair Cable consists of two conductors (usually copper), each with its own

유도매체(cont’d) o Twisted-Pair Cable consists of two conductors (usually copper), each with its own Color-banded for identification colored plastic insulation PVC : polyvinyl chloride • two copper conductors • one carries signals, the other is the ground reference • interference may affect both wires • receiver operates on the difference between the signals • this is why Kyung Hee they are twisted, to maintain balance • more twists mean better quality University 7

유도매체(cont’d) o. Effect of noise on parallel lines Kyung Hee University 8

유도매체(cont’d) o. Effect of noise on parallel lines Kyung Hee University 8

유도매체(cont’d) o. Effect of noise on twisted-pair lines Kyung Hee University 9

유도매체(cont’d) o. Effect of noise on twisted-pair lines Kyung Hee University 9

유도매체(cont’d) o. Advantage of UTP cheap, flexible, and easy to install. 2 ~ 12

유도매체(cont’d) o. Advantage of UTP cheap, flexible, and easy to install. 2 ~ 12 twists per foot o. Cable with 5 unshielded twisted pairs of wires Kyung Hee University 10

유도매체(cont’d) o. UTP standards has developed to grade by quality Category Bandwidth Data Rate

유도매체(cont’d) o. UTP standards has developed to grade by quality Category Bandwidth Data Rate Digital/Analog Use 1 very low < 100 kbps Analog Telephone 2 < 2 MHz 2 Mbps Analog/digital T-1 lines 3 16 MHz 10 Mbps Digital LANs 4 20 MHz 20 Mbps Digital LANs 5 100 MHz 100 Mbps Digital LANs 6 (draft) 200 MHz 200 Mbps Digital LANs 7 (draft) 600 MHz 600 Mbps Digital LANs Kyung Hee University 11

유도매체(cont’d) o. UTP connectors • RJ – Registered Jack • keyed connector, can be

유도매체(cont’d) o. UTP connectors • RJ – Registered Jack • keyed connector, can be inserted one way Kyung Hee University 12

Performance Kyung Hee University 13

Performance Kyung Hee University 13

Applications of UTP o telephone lines for voice and data o DSL o LAN

Applications of UTP o telephone lines for voice and data o DSL o LAN – 10 Base-T and 100 Base-T Kyung Hee University 14

유도매체(cont’d) o. STP(Shielded Twisted-Pair) cable has the same quality consideration as UTP (more expensive,

유도매체(cont’d) o. STP(Shielded Twisted-Pair) cable has the same quality consideration as UTP (more expensive, less susceptible to noise) l eliminating most of the effects of crosstalk Kyung Hee University 15

유도매체(cont’d) o동축 케이블(Coaxial Cable) carries signals of higher frequency ranges o. Frequency range of

유도매체(cont’d) o동축 케이블(Coaxial Cable) carries signals of higher frequency ranges o. Frequency range of coaxial cable Kyung Hee University 16

유도매체(cont’d) o. Coaxial cable Kyung Hee University 17

유도매체(cont’d) o. Coaxial cable Kyung Hee University 17

유도매체(cont’d) o. Coaxial Cable Standards ~ are categorized by RG(radio government) rating Category Impedance

유도매체(cont’d) o. Coaxial Cable Standards ~ are categorized by RG(radio government) rating Category Impedance Use RG-59 75 W Cable TV RG-58 50 W Thin Ethernet RG-11 50 W Thick Ethernet Kyung Hee University 18

유도매체(cont’d) o Coaxial Cable Connectors Kyung Hee University 19

유도매체(cont’d) o Coaxial Cable Connectors Kyung Hee University 19

유도매체(cont’d) o Performance Kyung Hee University 20

유도매체(cont’d) o Performance Kyung Hee University 20

유도매체(cont’d) o Applications Cable TV traditional Ethernet LANs, 10 Base-2, 10 Base-5 Kyung Hee

유도매체(cont’d) o Applications Cable TV traditional Ethernet LANs, 10 Base-2, 10 Base-5 Kyung Hee University 21

유도매체(cont’d) o. Optical Fiber(광섬유) ~ is made of glass or plastic and transmits signals

유도매체(cont’d) o. Optical Fiber(광섬유) ~ is made of glass or plastic and transmits signals in the form of light o. Nature of Light ~ is a form of electromagnetic energy. It travels at its fastest in a vacuum : 300, 000 km/s. This speed decreases as the medium through which the light travels become denser. Kyung Hee University 22

유도매체(cont’d) o굴절(Refraction) Kyung Hee University 23

유도매체(cont’d) o굴절(Refraction) Kyung Hee University 23

유도매체(cont’d) o임계각(critical angle) As the angle of incidence(입사각) increase, it moves away from vertical

유도매체(cont’d) o임계각(critical angle) As the angle of incidence(입사각) increase, it moves away from vertical and closer to the horizontal. Kyung Hee University 24

유도매체(cont’d) o반사(Reflection) When the angle of incidence becomes greater than the critical angle, a

유도매체(cont’d) o반사(Reflection) When the angle of incidence becomes greater than the critical angle, a new phenomenon occurs called reflection Kyung Hee University 25

유도매체(cont’d) o Optical Fiber Kyung Hee University 26

유도매체(cont’d) o Optical Fiber Kyung Hee University 26

유도매체(cont’d) o. Propagation Models current technology supports two models for propagating light along optical

유도매체(cont’d) o. Propagation Models current technology supports two models for propagating light along optical channel. Kyung Hee University 27

유도매체(cont’d) o. Multimode step-index ~ multiple beams from a light source move through the

유도매체(cont’d) o. Multimode step-index ~ multiple beams from a light source move through the core in different paths. Kyung Hee University 28

유도매체(cont’d) o. Multimode graded-index fiber with varying densities highest density at the center of

유도매체(cont’d) o. Multimode graded-index fiber with varying densities highest density at the center of the core Kyung Hee University 29

유도매체(cont’d) o. Single Mode ~ uses step-index fiber and a highly focused source of

유도매체(cont’d) o. Single Mode ~ uses step-index fiber and a highly focused source of light that limits beams to a small range of angles, all close to the horizontal. Kyung Hee University 30

유도매체(cont’d) o. Fiber sizes ~ are defined by the ratio of the diameter of

유도매체(cont’d) o. Fiber sizes ~ are defined by the ratio of the diameter of their core to the diameter of their cladding. Fiber Type 62. 5/125 50/125 100/140 8. 3/125 Kyung Hee University Core(microns) Cladding(microns) 62. 5 50 100 8. 3 125 140 125 31

유도매체(cont’d) o. Cable Composition Fiber can be made of either glass or plastic Inner

유도매체(cont’d) o. Cable Composition Fiber can be made of either glass or plastic Inner core must be ultrapure and completely regular in size and shape Outer jacket can be made Teflon coating, plastic coating, fibrous plastic, metal tubing, and metal mesh Kyung Hee University 32

유도매체(cont’d) o Cable Composition Kyung Hee University 33

유도매체(cont’d) o Cable Composition Kyung Hee University 33

유도매체(cont’d) o Applications of Fiber-optic network backbones cable TV LANs, 100 Base-FX, 1000 Base-X

유도매체(cont’d) o Applications of Fiber-optic network backbones cable TV LANs, 100 Base-FX, 1000 Base-X Kyung Hee University 34

유도매체(cont’d) o. Fiber-Optic Connectors must be as precise as the cable itself. All of

유도매체(cont’d) o. Fiber-Optic Connectors must be as precise as the cable itself. All of the popular connector are barrel(원통) shaped and come in male and female versions. Kyung Hee University 35

유도매체(cont’d) o Fiber-optic Cable Composition Kyung Hee University 36

유도매체(cont’d) o Fiber-optic Cable Composition Kyung Hee University 36

유도매체(cont’d) o Optical Fiber Performance Kyung Hee University 37

유도매체(cont’d) o Optical Fiber Performance Kyung Hee University 37

유도매체(cont’d) o. Advantages of Optical Fiber Noise resistance Less signal attenuation Higher bandwidth o.

유도매체(cont’d) o. Advantages of Optical Fiber Noise resistance Less signal attenuation Higher bandwidth o. Disadvantages of Optical Fiber Cost Installation/maintenance Fragility Kyung Hee University 38

7. 2 비유도 매체(Unguided media) owireless osignals are broadcasted through air Kyung Hee University

7. 2 비유도 매체(Unguided media) owireless osignals are broadcasted through air Kyung Hee University 39

비유도 매체(cont’d) o. Radio Frequency Allocation Kyung Hee University 대류층 전리층 40

비유도 매체(cont’d) o. Radio Frequency Allocation Kyung Hee University 대류층 전리층 40

비유도 매체(cont’d) o. Propagation of radio waves Types of propagation Kyung Hee University 41

비유도 매체(cont’d) o. Propagation of radio waves Types of propagation Kyung Hee University 41

비유도 매체(cont’d) o Type of propagation Surface Propagation l Radio waves travel through the

비유도 매체(cont’d) o Type of propagation Surface Propagation l Radio waves travel through the lowest portion of the atmosphere(대기권) Tropospheric (대류권) Propagation l can work two ways( signal can be directed in a straight line from antenna to antenna. It can be broadcast at an angle into the upper layers of troposphere where it is reflected back down to the earth’s surface) Kyung Hee University 42

비유도 매체(cont’d) Ionospheric (전리층) Propagation l High-frequency radio waves radiate upward into the ionosphere

비유도 매체(cont’d) Ionospheric (전리층) Propagation l High-frequency radio waves radiate upward into the ionosphere where they are reflected back to earth Line-of-Sight Propagation l Very high frequency signals are transmitted in straight lives directly from antenna to antenna Space Propagation l Utilizes satellite relays in place of atmospheric refraction Kyung Hee University 43

비유도 매체(cont’d) Band Range Propagation Application VLF 3– 30 KHz Ground Long-range radio navigation

비유도 매체(cont’d) Band Range Propagation Application VLF 3– 30 KHz Ground Long-range radio navigation LF 30– 300 KHz Ground Radio beacons and navigational locators MF 300 KHz– 3 MHz Sky AM radio HF 3– 30 MHz Sky Citizens band (CB), ship/aircraft communication VHF 30– 300 MHz Sky and line-of-sight VHF TV, FM radio UHF 300 MHz– 3 GHz Line-of-sight UHF TV, cellular phones, paging, satellite SHF 3– 30 GHz Line-of-sight Satellite communication EHF 30– 300 GHz Line-of-sight Long-range radio navigation Kyung Hee University 44

비유도 매체(cont’d) o Wireless Transmission Waves Kyung Hee University 45

비유도 매체(cont’d) o Wireless Transmission Waves Kyung Hee University 45

비유도 매체(cont’d) o Omnidirectional antennas Kyung Hee University 46

비유도 매체(cont’d) o Omnidirectional antennas Kyung Hee University 46

비유도 매체(cont’d) • Radio waves are used for multicast communications, such as radio and

비유도 매체(cont’d) • Radio waves are used for multicast communications, such as radio and television, and paging systems. Kyung Hee University 47

비유도 매체(cont’d) o. Terrestrial microwaves require line-of-sight transmission and reception equipment. The distance coverable

비유도 매체(cont’d) o. Terrestrial microwaves require line-of-sight transmission and reception equipment. The distance coverable by a line-of-sight signal depends on a large extent on the height of the antenna : the taller the antenna, the longer the sight distance Kyung Hee University 48

비유도 매체(cont’d) o. Repeaters To increase the distance served by terrestrial microwave, a system

비유도 매체(cont’d) o. Repeaters To increase the distance served by terrestrial microwave, a system of repeaters can be installed with each antenna. Kyung Hee University 49

비유도 매체(cont’d) o Antennas two types of antenna ¬ Parabolic dish is based on

비유도 매체(cont’d) o Antennas two types of antenna ¬ Parabolic dish is based on the geometry of a parabola Kyung Hee University 50

비유도 매체(cont’d) Horn antenna looks like a gigantic scoop Kyung Hee University 51

비유도 매체(cont’d) Horn antenna looks like a gigantic scoop Kyung Hee University 51

비유도 매체(cont’d) o. Satellite Communication is much like line of sight microwave transmission in

비유도 매체(cont’d) o. Satellite Communication is much like line of sight microwave transmission in which one of the station is a satellite orbiting the earth Kyung Hee University 52

비유도 매체(cont’d) o. Geosynchronous (geostationary) satellites @ the view from the North Pole Kyung

비유도 매체(cont’d) o. Geosynchronous (geostationary) satellites @ the view from the North Pole Kyung Hee University 53

비유도 매체(cont’d) o. Frequency bands for satellite communication Band Downlink Uplink C 03. 7

비유도 매체(cont’d) o. Frequency bands for satellite communication Band Downlink Uplink C 03. 7 - 04. 2 GHz 05. 925 - 06. 425 GHz ` Ku 11. 7 - 12. 2 GHz 14. 000 - 14. 500 GHz Ka 17. 7 - 21. 0 GHz 27. 500 - 31. 000 GHz Kyung Hee University 54

비유도 매체(cont’d) o Cellular telephony is designed to provide stable communications connections between two

비유도 매체(cont’d) o Cellular telephony is designed to provide stable communications connections between two moving device or between one mobile unit and one stationary(land) unit. Kyung Hee University 55

Cellular and PCS telephony o 서비스 별 비교 항목 주파수대역 IS-95 A IS-95 B

Cellular and PCS telephony o 서비스 별 비교 항목 주파수대역 IS-95 A IS-95 B IS-95 C(CDMA 2000 1 X) 셀룰러 800 MHz 대역, PCS 1. 7 ~ 1. 8 GHz IMT 2000(MC 3 X) 1. 9 ~ 2. 1 GHz 단말기 대기시간 1(기준) 1. 3~1. 5 3 3이상 데이터 속도 14. 4 Kbps 64 Kbps 144 Kbps 384 Kbps ~ 2 Mbps A 4 100장 전송 55 초 12 초 6초 2. 5 초 미만 동영상통화 Kyung Hee University 불가 가능 IS : Interim Standard 56

Wireless Transmission o Radio waves are used for multicast communications, such as radio and

Wireless Transmission o Radio waves are used for multicast communications, such as radio and television, and paging systems o. Microwaves are used for unicast communication such as cellular telephones, satellite networks, and wireless LANs. o Infrared signals can be used for short-range communication in a closed area using line-ofsight propagation Kyung Hee University 57