Wireless Network Technologies and Standards: Key Concepts

1. Introduction to Wireless

1. Which of the following accurately describes the goal of RF technology?
   R: To send as much data as far as possible and as fast as possible.
2. Which of the following is a significant problem experienced with wireless networks?
   R: Interference.
3. Which two of the following are unlicensed frequency bands used in the United States?
   R: 2.4 GHz, 5.0 GHz.
4. Each 2.4-GHz channel is how many megahertz wide?
   R: 22 MHz.
5. How many non-overlapping channels exist in the 2.4 GHz ISM range?
   R: 3.
6. The 5.0 GHz range is used by which two of the following 802.11 standards?
   R: 802.11n, 802.11a.
7. Which three of the following modulation techniques do WLANs today use?
   R: OFDM, DSSS, MIMO.
8. DSSS uses a chipping code to encode redundant data into the modulated signal. Two examples of chipping codes that DSSS uses?
   R: Barker code, Complementary Code Keying (CCK).
9. DSSS binary phase-shift keying uses what method of encoding at the 1-Mbps data rate?
   R: 11-chip Barker code.
10. With DRS, when a laptop operating at 11 Mbps moves farther away from an access point, what happens?
    R: The rate shifts dynamically to 5.5 Mbps.

2. Standards Bodies

1. The FCC regulates wireless usage in which of the following countries?
   R: United States of America.
2. True or False: The U.S. complies with ETSI standards of EIRP.
   R: False.
3. What is the maximum EIRP for point-to-multipoint in Europe?
   R: 20 dBm, 17 dBm.
4. The FCC regulates EIRP in the U.S. to a maximum of ___ for point-to-point and ___ for point-to-multipoint.
   R: 36 dBm, 36 dBm.
5. The IEEE committees work on which of the following wireless standards?
   R: 802.11a, 802.11g, 802.11b.
6. True or False: The IEEE is a regulatory body in the U.S. that controls the usage of wireless frequencies.
   R: False.
7. In Europe, can a professional installer increase the gain on wireless antennas?
   R: Yes, provided that he or she decreases the transmit power using a 1:1 ratio.
8. The FCC regulates that professional installers maintain what ratio of gain to transmit power when increasing the gain of an antenna?
   R: 3:1.
9. Which organization certifies interoperability for wireless equipment?
   R: Wi-Fi Alliance.
10. Certification of wireless equipment includes which protocols and standards for interoperability?
    R: 802.11a/b/g, Zigbee.

3. WLAN RF Principles

1. Which of the following best describes a frequency that is seen 1 million times per second?
   R: 1 MHz.
2. What does amplitude measure?
   R: Height of wave from lowest crest to highest crest.
3. EIRP is calculated using which of the following formulas?
   R: EIRP = transmitter power - cable loss + antenna gain.
4. Metal desks, glass, light fixtures, and computer screens can contribute to which influence on wireless transmissions?
   R: Reflection.
5. Carpet, human bodies, and walls can contribute to which influence on wireless transmission?
   R: Absorption.
6. In the free path loss model, objects that are farther away from a transmitter receive the same amount of signal as those that are closer to the transmitter. True or False?
   R: False.
7. If a signal is being spread about by microparticles, it is experiencing which influence on wireless transmissions?
   R: Scattering.
8. Multipath causes which of the following issues?
   R: The signal becoming out of phase, which can potentially cancel the signal, Portions of the signal being reflected and arriving out of order.
9. Scattering is caused by humidity. True or False?
   R: True.
10. For line of sight (LOS) transmissions, what can determine where signals can become out of phase?
    R: Fresnel Zone.
11. Link Budget is used to do which of the following?
    R: Account for all the gains and losses, Factor in EIRP and attenuation for a transmission.

4. WLAN Technology and Topology

1. Which of the following topologies can be used with clients closer than 20 feet?
   R: WPAN.
2. True or False: A WLAN uses 802.16b.
   R: False.
3. What topology is most often seen in a LAN and is designed to connect multiple devices to the network?
   R: WLAN.
4. In what frequency ranges does a wireless LAN operate?
   R: 2.4 GHz, 5 GHz.
5. What type of speed can you expect from a WLAN?
   R: Broadband.
6. What is the name of the common WMAN technology?
   R: WiMAX.
7. True or False: Deploying a WWAN is relatively inexpensive, so it's common for Enterprise customers to deploy their own.
   R: False.