Use the following chart to discuss the advantages and disadvantages of various types of wireless network links: Communications Link Advantages Disadvantages Radio waves Longer range; does not require line-of-sight transmission Before you can use a frequency for communication, it must be licensed from the FCC Infrared transmissions An FCC license is not required transmission range; requires line-of-sight transmission Microwave transmissions Long range; can be aimed in one direction; has higher capacity when compared to radio waves Microwaves cannot penetrate metal; requires line-of-sight transmission; microwave stations cannot be more than 25 or 30 miles apart Satellite links A GEO satellite provides continuous coverage over a particular area; an LEO satellite offers transmission delays of only a few hundredths of a second A GEO satellite requires a delay of 24 seconds to transmit data; an LEO satellite requires a web of satellites List the advantages and disadvantages of wireless networks. Explain that Wi-Fi specifies the hardware, the type of transmission medium, and the transmission speed. FIGURES Figure 5-25, Figure 5-26 TEACHER TIP Most students will be familiar with the use of radio waves for data communication. Students also may be familiar with satellite transmission if they have used a GPS system. However, many will not be familiar with the use of infrared transmissions, even though they use some infrared devices, such as television remote controls. Discuss examples of each of these technologies. CLASSROOM ACTIVITIES Class Discussion: If your building has a wireless network, ask the class if they use it. Is it reliable? Quick Quiz: Most wireless networks transport data using which type of signal? (Answer: RF) True/False: Infrared light can be used to carry data signals, but only for short distances and between devices with clear line of sight. (Answer: True) True/False: Workstations, peripheral devices, and network devices can be equipped with transceivers to send and receive data on wireless networks. (Answer: True)
role that it played in German dominance early in the war. How did the machine work to encrypt the messages of the German military? Quick Quiz: _________ key encryption uses the same key to encrypt the message as to decrypt it. (Answer: Symmetric) A(n) __________ is a procedure for encrypting or decrypting a message. (Answer: cryptographic algorithm) WHAT DO YOU THINK? 053100 Have you ever accessed a free WLAN? a. Yes b. No c. Not sure 053200 Do you believe that rogue WLANs can survive alongside for-profit broadband ISPs? a. Yes b. No c. Not sure 053300 Are broadband providers justified in limiting the terms of their service agreements to “one subscription, one customer”? a. Yes b. No c. Not sure Glossary of Key Terms AES, 285 Application server, 249 Bandwidth, 251 Bluetooth, 267 Bridge, 250 Broadband, 251 Bus topology, 250 Ciphertext, 285 Circuit switching, 253 Client/server mode, 249 Communications channel, 251 Communications protocol, 252 Cryptographic algorithm, 285 Cryptographic key, 285 CSMA/CD, 259 Decryption, 285 DHCP, 255 Drive mapping, 276 Encryption, 285 Ethernet, 258 Ethernet adapter, 261 File server, 249 Gateway, 251 Handshaking, 252 HomePNA, 257 Infrared 265 IP address, 255 LAN, 247 LAN jacking, 282 LAN party, 280 MAC address, 254 MAN, 247
Mesh topology, 250 Microwaves, 265 MIMO, 268 Narrowband, 251 Network attached storage, 248 Network device, 248 Network hub, 261 Network interface card, 248 Network router, 261 Network switch, 261 Networked peripheral, 248 Node, 248 Octet, 255 Packet, 253 Packet switching, 253 PAN, 246 Peer-to-peer mode, 249 PGP, 287 Physical topology, 250 Piconet, 267 Plaintext, 285 Powerline network, 258 server, 249 PSK, 283 Public key encryption, 286 RF signals, 265 Ring topology, 250 RJ45 connector, 262 Shared resources, 274 SSID, 272 Star topology, 250 Strong encryption, 285 Symmetric key encryption, 286 Transceiver, 265 Tree topology, 250 WAN, 247 Weak encryption, 285 WEP, 283 Wi-Fi, 268 Wi-Fi adapter, 269 network, 256 Wireless access point, 270 Wireless ad-hoc network, 270 Wireless encryption, 283 Wireless infrastructure network, 270 Wireless network, 265 Wireless network key, 284 Wireless router, 270 WPA, 283