Chapter 6 – Wireless Network Fundamentals
TRUE/FALSE
1. In wireless networks, infrared signals are used most often for data communications.
2. RF signals can pass through walls and other objects while IR cannot.
3. The Fresnel zone is the dispersal pattern of waves as they travel from sending to receiving antennas.
4. The Independent Basic Service Set is a wireless network that uses an AP.
5. The 802.11i standard maps to the WPA2 security protocol.
MULTIPLE CHOICE
1. Which of the following is defined as the maximum departure of a wave from the undisturbed state?
a.
amplitude
c.
frequency
b.
spectrum
d.
wavelength
2. Which of the following is true about RF transmissions?
a.
EM radiation is measured in volts
c.
frequency is the distance between waves
b.
frequency has an inverse relationship with
wavelength
d.
cooler objects produce higher-frequency
radiation than hotter objects
3. Which of the following is true about infrared transmissions?
a.
directed IR transmission relies on
reflected light
c.
the intensity of the light pulse indicates
the on or off status of each bit
b.
diffused IR transmission requires emitter
and detector to be aligned
d.
IR transmissions have speeds up to 25
Mbps.
4. Which of the following pairs represents a medium frequency band and its common use?
a.
300 KHz-3MHz, AM radio
c.
30-300 KHz, cordless phones
b.
144-174 MHz, TV channels
d.
3-30 MHz, CB and shortwave radio
5. In which frequency range are you likely to find WLANs?
a.
30-300 GHz
c.
2.9-30 GHz
b.
174-328 MHz
d.
3-30 MHz
6. What is a potential problem with having too many APs in a given area?
a.
refraction
c.
multipath
b.
fading
d.
co-channel interference
7. Which of the following is defined as the positive difference in amplitude between two signals?
a.
fading
c.
reflection
b.
gain
d.
attenuation
8. Which of the following causes of signal loss is defined as differences in density between air masses
over distance?
a.
reflection
c.
scattering
b.
absorption
d.
refraction
9. Which term is the measurement of the difference between two signals?
a.
watt
c.
amp
b.
decibel
d.
volt
10. What does a measurement of +3 dB equal in power measured in mW?
a.
double the power
c.
one third the power
b.
3 times the power
d.
one half the power
11. What is used to convert an analog RF signal into digital format?
a.
spectrum
c.
modulator
b.
EIRP
d.
carrier
12. Which type of analog modulation changes the number of waves representing one cycle?
a.
amplitude modulation
c.
phase modulation
b.
frequency modulation
d.
relative modulation
13. Which binary signaling technique uses a scheme in which zero voltage represents a 0 bit and the
voltage for a 1 bit does not drop back to zero before the end of the bit period?
a.
RTZ
c.
polar NRZ
b.
NRZ
d.
polar RTZ
14. Which digital signal modulation method is a binary modulation technique in which the carrier signal’s
frequency is changed to represent a 1 or 0 bit?
a.
ASK
c.
PSK
b.
FSK
d.
FDM
15. Which RF transmission method uses an expanded redundant chipping code to transmit each bit?
a.
FHSS
c.
CDMA
b.
OFDM
d.
DSSS
16. Which wireless transmission method uses a hopping code?
a.
infrared
c.
narrowband
b.
OFDM
d.
FHSS
17. Which of the following tasks does an AP typically perform?
a.
bridges between the wired and wireless
network
c.
routes packets from subnet to subnet
b.
acts as a hub for a wired network
d.
divides data into packets
18. What term is given to a device that is designed to generate radio signals, not including those from the
antenna?
a.
oscillator
c.
intentional radiator
b.
conductive medium
d.
EIRP
19. What is a Basic Service Set?
a.
a group of wireless devices served by a
single AP
c.
a wireless network that does not use an AP
b.
multiple APs are set up to provide some
overlap
d.
wireless devices set up as a basic ad-hoc
network
20. Which wireless networking standard uses the 2.4 GHz band and has a maximum bandwidth of 54
MBps?
a.
802.11a
c.
802.11ac
b.
802.11b
d.
802.11g
COMPLETION
1. Cosmic objects emit different types of energy, known as _________________ radiation.
2. A _________________ IR transmission relies on reflected light that can bounce off walls and other
objects.
3. RF transmits a _______________ signal which can change based on the signal’s voltage and direction.
4. A wireless _______________ combines management and security into a single appliance and can
perform authentication, encryption, intrusion detection, and other functions.
5. The _____________________ wireless standard will use the 5 GHz band and will provide multistation
WLANs with up to 1 Gbps bandwidth.
MATCHING
a.
absorption
f.
fading
b.
amplitude
g.
free space path loss
c.
antenna
h.
Fresnel zone
d.
chipping code
i.
hopping code
e.
diffraction
j.
polarization
1. a form of interference/power loss in which the signal is reflected or refracted by
the atmosphere, ground, or other obstacles, and the reflected path interferes with the
direct path
2. a type of loss in which certain materials absorb the RF signal
3. a device used to transmit or receive radio waves
4. the sequence of changing frequencies in FHSS that determines the sequence
and speed of frequency hops
5. the loss of signal strength resulting from the dispersion of the signal
over distance
6. the bit pattern used in direct sequence spread spectrum
7. the plane on which radio waves propagate, or the orientation of the radio
waves as they leave the antenna
8. an area in which you can determine RF signal strength, identify potential
obstacles, and determine the potential for multipath distortion
9. a phenomenon tin which a signal bends around objects in its path
10. the maximum departure of a wave from its undisturbed state; the height of the
carrier wave
SHORT ANSWER
1. What is the difference between directed IR transmission and diffused IR transmission?
2. Why should you use caution when using multiple APs?
3. Describe multipath interference.
4. Describe how RF power is measured.
5. Compare and contrast analog and digital RF signals.
6. Describe two of the three methods of analog modulation.
7. Describe two of the four methods of digital signal modulation.
8. Describe OFDM.
9. Describe how RF waves are transmitted and received by an antenna.
10. Discuss how an ESS works.