Small problems
1. Explain why the MAC protocol is more important in wireless LANs than in wired LANs.

2. Explain why there is more attenuation in a wireless LAN than in a wired LAN, ignoring the noise and the interference.

3. What is multipath propagation? What is its effect on wireless networks?

4. An AP may connect a wireless network to a wired network. Does the AP need to have two MAC addresses in this case?

5. How does the access point know whether a wireless data packet is intended for its network?

6. Unlicensed bands are part of the radio spectrum that are available nationwide to all users without requiring a license. However, a drawback is that, because there are no licenses, there can be interference between devices. Use the Internet to identify a list of devices that can interference with WLANs in either the ISM or U-NII bands.

True/False & Multiple Choice Questions:
1. In ad hoc mode, the wireless clients communicate directly with the AP. True or False?

2. On a regular basis, wireless clients will scan all the radio frequencies to determine if a different AP can provide better service. True or False?

3. A wireless NIC performs the same functions as a wired NIC except that it_____.

a. does not transmit the packet
b. uses an antenna instead of a wired connection
c. contains special memory
d. does not use parallel transmission

4. Which of the following is not a function of an AP?
a. sends and receives RF signals
b. connects to the wired network
c. serves as a router
d. acts as a bridge between the wired and wireless networks

5. The highest data rate for an 802.11g RF WLAN is about ______ Mbps.
a. 22
b. 1
c. 2
d. 54

6. The IEEE 802.11b standard that outlines the specifications for RF WLANs is based on _____.
a. FHSS
b. DSSS
c. infrared
d. OFDM

7. Because all the IEEE WLAN features are isolated in the PHY and _____ layers, any network operating system or LAN application will run on a WLAN without any modification.
a. MAC
b. network
c. PLCP

d. PMD

8. The Physical Layer standards for 802.11b are based on _____ spread spectrum.
a. frequency hopping
b. QAM
c. direct sequence
d. BPSK

9. The method used in 802.11 to implement CSMA/CA is based on ______.
a. DSSS
b. DCF
c. FHSS
d. PCF

10. If the AP does not send the SSID of the WLAN in the beacon, client devices can still obtain the SSID by _______.
a. sending an associate request frame
b. transmitting an SSID request frame
c. sending a probe frame
d. transmitting a special data frame

11. The maximum data rate of an IEEE 802.11a WLAN, according to the standard, is _______.
a. 11 Mbps
b. 24 Mbps
c. 54 Mbps
d. 108 Mbps

12. In PCF, the client devices cannot transmit unless ________.
a. the WLAN is operating in peer-to-peer mode
b. the AP sends an ACK frame
c. the AP sends data first
d. the client is "polled" by the AP

13. The Federal Communications Commission (FCC) has segmented the 555 MHz of the original UNII spectrum into four segments or bands, and each band has a maximum power limit. True or False?

14. The most important change made to the MAC layer of 802.11a was ______.
a. to make the frames shorter
b. to increase security
c. to make the frames longer for efficiency
d. none of the above

15. IEEE 802.11a achieves its increase in speed and flexibility over 802.11b by each of the following except ______________.
a. higher frequency
b. using less bandwidth
c. more transmission channels
d. a new multiplexing technique

16. The Unlicensed National Information Infrastructure (U-NII) band operates at the _____ frequency.
a. 2.4 GHz
b. 33 GHz
c. 5 GHz
d. 16 KHz

17. All 5 GHz bands are available to WLANs worldwide. True or False?

18. Although such devices as 2.4 GHz cordless phones, microwave ovens, and Bluetooth devices may cause interference problems with 802.11b networks in the 2.4 GHz ISM band, they are not a problem with 802.11a. True or False?

19. Each frequency channel in an 802.11a WLAN is 20 MHz wide and supports ______ subcarrier signals.
a. 56
b.114
c. 52
d. 48

20. One of the reasons that 802.11n achieves a higher bandwidth is that it bonds two ISM or U-NII channels. Another important reason is that it_____________.
a. eliminates multipath interference
b. uses antenna diversity
c. can transmit using multiple spatial streams
d. can transmit in any two frequency channels simultaneously

21. When actively using a network while roaming in an ESS, the process of connecting and disconnecting from the APs in one's path is called ________.
a. MIMO
b. handoff
c. switching
d. nomadic

22. IEEE 802.11n devices can be as far as 375 feet apart and can send and receive data at up to ________ million bits per second (Mbps).
a. 75
b. 600
c. 100
d. 54

23. Why is the 802.11a standard not backwardly compatible with the 802.11b/g standard?
A. 802.11a uses the 5GHz frequency band
B. 802.11a uses OFDM instead of DSSS
C. 802.11b or 802.11g was a proprietary standard.
D. 802.11b or 802.11g causes interference.