1.4 Transmission media

Question 1

cable

Answer 1

wired

devices are physically connected using either copper wire, fibre optic cable, or telephone lines

Question 2

copper wire/unshielded twisted pair

Answer 2

transmits data as electric signals

cheaper than fibre optic
flexible and easy to install

normally used to connect desktop computers and a switch

Question 3

fibre optic cable

Answer 3

transmits data as pulses of light

transmits signals at faster speeds and over greater distances than copper wire

more expensive than UTP
higher bandwidth than copper

normally used for longer distance WANs

Question 4

bandwidth

Answer 4

the amount of data that can be transmitted per second

measured in bits per second (bps)

copper cable: up to 1 Gbps
fibre optic: up to 10 Gbps
wireless: up to 600 Mbps

Question 5

radio waves (wireless)

Answer 5

wireless networks use radio waves (part of the EM spectrum) to communicate

the most commonly used frequencies for data transmission are 2.4 GHz and 5 GHz
(1 GHz = 1 billion cycles per second)

the frequency range is divided into 14 channels spaced 5 MHz apart

users can change the operating channel of their wif-fi device to prevent interference

Question 6

protocols and security

Answer 6

protocols are the rules that computers must follow when communicating over a network

ethernet protocols are used in cable networks

wifi protocols are used in wireless networks

wifi is one wireless technology that uses radio waves

other wireless protocols include bluetooth, 3G, 4G and wifi direct

Question 7

bandwidth of cable and wireless

Answer 7

cable: high, up to 10 Gbps
wireless: low, up to 600 Mbps

Question 8

installation of cable and wireless

Answer 8

cable: difficult, must run cables throughout the site
wireless: easy, just need wireless access points

Question 9

cost of cable and wireless

Answer 9

cable: expensive, cost of cables and installation
wireless: cheap, just cost of wireless access points

Question 10

security for cable and wireless

Answer 10

cable: good, need to plug computer into a socket

wireless: poor, anyone within range can access the network
must use security passwords

Question 11

interference for cable and wireless

Answer 11

cable: good, there is no interference with cables
wireless: not so good, signal can be affected by walls and other electronic equipment

Question 12

mobility for cable and wireless

Answer 12

cable: poor, need to plug computer into a socket
wireless: good, access can be from anywhere within range

Question 13

a) State two types of cable that can be used to network computers [2]
b) State one other transmission medium that can be used to connect computers to form a network [1]

Answer 13

a) copper wire and fibre optic cable

b) microwaves or radio waves (wifi)

Question 14

A school is considering whether to install a cable or wireless network.

Explain three benefits of each type of network when used in a school situation [6]

Answer 14

wired network:

• higher bandwidth and more suitable for multimedia use in schools
• delays in lessons would be unacceptable and the higher bandwidth will prevent this
• better security and easier for the school to monitor how students are using the network
• no interference caused by walls and other electronic devices

wireless:

• students can use their own devices
• it allows devices to be used in outside lessons
• easier and cheaper to install new network areas
• less disruption during installations as no drilling is required for cables
• devices that do not have network ports can connect
• students and teachers can remain connected as they move from room to room