1Conducted and Wireless Media (Part I)School of BusinessEastern Illinois University © Abdou Illia, Fall 2014(October 6, 2014)2Learning Objectives Outline characteristics of conducted media Select conducted media in LAN design3Major categories of Media Conducted Media– Physically connect network devices Wireless Media– Use electromagnetic waves/radiation24Conducted Media Twisted Pair cable Coaxial cable Optical Fiber cable5Twisted Pair wire Typically 2 or more Twisted pair wires & different standards for different applications http://en.wikipedia.org/wiki/Twisted_pair Shielded Twisted Pair (STP) Versus Unshielded Twisted Pair (UTP)6Twisted Pair wire2Q: Are Shielded Twisted Pairs (STP) affected by interference ?37Coaxial cable Cable can be thick or thin Provides for wide range of frequencies A single wire wrapped in a foam (or plastic) insulation surrounded by a braided metal shield, then covered in a plastic jacket8Coaxial cable Two major coaxial technologies:Baseband Coaxial tech. Broadband Coaxial tech.Uses digital signaling Transmits anal./digital signalsOne channel of digital data Multiple channels of data Thin coaxial cable– Typically used for digital data transmission in Ethernet LANs– Typically used for baseband transmission Thick coaxial cable– Typically for broadband transmission– Typically used for video transmissionLess noise/interference compared to twisted pairs~1 kilometer w/o repeater ~ 4 kilometer w/o repeater9Coaxial cable Coaxial cable standards: RG (Radio Guide) specifies characteristics like wire thickness, insulation thickness, electrical properties, etc. Ohm is the measure of resistance within the mediumType①Ohm rating②UseRG-11 75 ohm Used in 10Base5 Ethernet (known as Thick Ethernet)RG-58 50 ohm Used in 10Base2 Ethernet10Base5Speed:10 MbpsSignal type:Baseband transmissionDistance:500 meters410Fiber Optic A thin glass cable approximately a little thicker than a human hair Two concentric layers termed Core and CladdingCladdingCore Common types:– 62.5/125 microns– 50/125 microns11Fiber Optic Photo diode (light/laser source) at the transmitting end– Generate light/laser and modulate it to represent binary data received from Source Photo receptor (optic sensor) at the receiving end– Receive the light/laser and convert it into digital signalSourcePhoto diode(LED or LD)DestinationPhoto receptor(LED or LD)Fiber optic cable12Fiber Optic Many advantages over Twisted pair and Coaxial cable– Speed– No significant noise– No interference– Less signal attenuation, i.e. longer distance– Low-power transceivers could be used (less electric consumption) Typical use in Businesses513Conducted Media14Case study The following figure shows a common situation in LANs. Remember : – Using Category 5 UTP, the maximum segment length is 100 meters.– A wall jack is a passive device that does not regenerate signalsCat 5-UTPCrossover cable15Case studyCat 5-UTPCrossover cable What kind of problem there will be if the distance between the Workstation and the Hub is more than 100 meters? What solution can be applied ? If the cable that connects the workstation and the hub passes through a noisy environment (Heating or cooling mechanical room) what action could be taken to prevent interference?616Case studyCat 5-UTPCrossover cable If the needed data rate is higher than 100 Mbps, what are the possible solutions?17Summary Questions What does cross talk interference mean ? How can crosstalk interference be reduced ?If transmission wires are placed side by side, electromagnetic radiation is emitted by one wire and picked up by the other. Twisting pair of wire reduce crosstalk interference. What categories of twisted pair are usually used in LANs ?Categories 3, 4, 5, 6, 7, 8 What are the advantages and disadvantages of STP compared to UTP ?Advantage: better level of isolation from interference. Disadvantage: cost What is the main difference between baseband coaxial cable and broadband coaxial cable ?Baseband carries digital signals with a single channel. Broadband carries analog or digital signals with multiple channels. What are the advantages of Optical fiber compared twisted pair and coaxial cable ?Speed, No significant noise, No interference, Long distance Can you transmit video signal over twisted pair wire ? ExplainYou can. Noise used to be a limitating factor, but it’s no longer the case.18Baseband signaling Single transmission channelOnly one bit at a time1010100 T1110010 r1100001 a1101110 n1110011 s1100110 f1100101 e1110010 r0100000 space0100100 $0110001 10110010 20110000 00110000 00101110 .0110000 00110000 0.....1110011 1101110 1100001 1010100 1010100 Uses TDM (Time Division Multiplexing)TimeVoltage10110719Broadband signaling Multiple transmission channelsMultiple bits at a time1010100 T1110010 r1100001 a1101110 n1110011 s1100110 f1100101 e1110010 r1111111 Uses FDM (Frequency Division