FACULTY OF

COMPUTER SCIENCE & ENGINEERING

Chapter 03. Spread Spectrum Technologies

QUESTION 1

1. Increasing the dwell time for an FHSS

system will increase the throughput.

A. This statement is always true

B. This statement is always false

C. It depends on the manufacturer of the

equipment

QUESTION 2

2. Which one of the following dwell times will

result in the greatest throughput in a FHSS

system and will still be within FCC

regulations?

A. 100 ms

B. 200 ms

C. 300 ms

D. 400 ms

QUESTION 3

3. An 802.11b compliant wireless LAN

configuration using DSSS can have a

maximum of ___ non-overlapping, co-located

access points.

A. 3

B. 15

C. 26

D. 79

QUESTION 4

4. Consider the following two wireless LAN

configurations: System 1. IEEE 802.11 compliant FHSS

system, 6 co-located access points running at maximum

data rate.

System 2. IEEE 802.11b compliant DSSS system, 3 co-

located access points running at 50% of maximum data

rate.

Which one of the following statements is true?

A. System 1 will have more throughput

B. System 2 will have more throughput

C. System 1 and System 2 will have the same throughput

QUESTION 5

5. Channels on direct sequence systems for

802.11b equipment are ___ MHz wide.

A. 5

B. 20

C. 22

D. 83

QUESTION 6

6. Which of the following are advantages of

802.11b DSSS over 802.11 FHSS?

Choose all that apply.

A. Cost

B. Throughput

C. Security

D. Resistance to narrowband interference

QUESTION 7

7. If having compatible equipment from

different manufactures were an important

factor when purchasing wireless LAN

equipment, which of the following spread

spectrum technologies would be the best

choice?

A. FHSS

B. DSSS

QUESTION 8

8. The FCC has two sets of rules regarding

FHSS that are known as before and after

which of the following dates?

A. 06/30/2000

B. 08/31/1999

C. 08/31/2000

D. 08/31/2001

QUESTION 9

9. The latest published FCC rules regarding

power output for FHSS states a maximum

output of which one of the following?

A. 100 mW

B. 125 mW

C. 200 mW

D. 1 W

QUESTION 10

10. The FCC specifies how many channels in

the 2.4 GHz ISM band that can be used for

DSSS in the United States?

A. 3

B. 6

C. 9

D. 11

QUESTION 11

11. You have been hired on as a consultant to increase the

capacity of an existing wireless LAN based on FHSS

technology. After your research is completed you

recommend that a replacement system based on DSSS

would be better. Which of the following could be your

arguments to defend your position? Choose all that apply.

A. The DSSS devices will cost less and have more throughput

B. The DSSS devices will cost more but have more throughput

C. Additional new FHSS devices may not be compatible with the

older devices

D. DSSS is more secure than FHSS

QUESTION 12

12. The statement, “802.11b wireless LAN

devices are backward compatible with

802.11 wireless LAN devices” is:

A. Always true

B. Always false

C. Sometimes true

QUESTION 13

13. What is considered to be the maximum

number of co-located FHSS access points in a

wireless LAN, if non-synchronized radios are

to be used?

A. 3

B. 16

C. 20

D. 26

QUESTION 14

14. In Frequency Hopping wireless LAN systems,

the term hopping refers to which one of the

following?

A. Switching between throughput speeds from 11

Mbps to 5.5 Mbps

B. What happens when the carrier frequency is

changed

C. The change that occurs as a result of the RF

signal getting weaker

D. Changing technologies from FHSS to DSSS

QUESTION 15

15. A DSSS channel is more susceptible to narrowband

interference than a FHSS channel because of which of the

following? Choose all that apply.

A. The DSSS channel is much smaller (22 MHz wide instead of the

79 MHz wide band used by FHSS)

B. The information is transmitted along the entire band

simultaneously instead of one frequency at a time

C. FHSS systems simply avoid the frequency on which the

narrowband interference is located

D. FHSS systems only use one frequency at a time, so the

narrowband interference must be on the same exact frequency at

the same time

QUESTION 16

16. The noise floor is defined by which one of

the following?

A. The general level of RF noise in the

environment around the wireless LAN

B. The noise that is generated as a result of foot

traffic

C. A fixed level of -100 dBm

D. The level of noise at which a wireless LAN

starts working

QUESTION 17

17. Which one of the following is not

described by the IEEE and OpenAir standards

regarding FHSS systems?

A. What frequency bands may be used

B. Hop sequences

C. Allowable levels of interference

D. Dwell times

E. Data rates

QUESTION 18

18. An RF signal is considered spread spectrum when

which of the following are true?

Choose all that apply.

A. The system sending the signal is using infrared

technology

B. The power required to send the information is

significantly greater than is necessary

C. The bandwidth used is much wider than what is

required to send the information

D. The bandwidth used is much less than what is used to

send the information

QUESTION 19

19. Some 2.4 GHz FHSS systems operate at 3

Mbps or more. Which of the following is true

regarding these systems?

A. They are always IEEE 802.11 compliant

B. They may not interoperate with other FHSS

systems

C. They are always OpenAir compliant

D. They are backwards compatible with 900 MHz

systems

QUESTION 20

20. How many different types of

implementations of spread spectrum

technology does the FCC specify for the 2.4

GHz ISM band?

A. 1

B. 2

C. 3

D. 4

The END