Chapter 6 - Medium Access Methods and QoS Frame Exchanges

Question 1

What is the shortest IFS used on all PHYs?
a. SIFS
b. DIFS
c. EIFS
d. AIFS

Answer 1

SIFS

Question 2

What is defined as a range of integers from which a single integer is chosen for the random backoff timer?
a. NAV
b. Contention window
c. PIFS
d. Access Category

Answer 2

Contention window

Question 3

Which AC has the highest priority with default WMM parameters?
a. AC_VI
b. AC_VO
c. AC_BK
d. AC_BE

Answer 3

AC_VO

Question 4

What is the default parameter for CWmin in the AC_VI AC using WMM parameters?
a. 3
b. 15
c. 31
d. 7

Answer 4

7 - 15

Voice (3-7)
BK/BE (15-1023)

Question 5

You see two WMM parameter sets in an AP configuration and they differ. What does this usually indicate?
a. The AP uses the same parameters as the clients
b. The AP uses different parameters than the clients
c. The vendor has implemented a non-standard method
d. You have blurry vision

Answer 5

The AP uses different parameters than the clients

Question 6

What frame does not contain the WMM parameter settings?
a. Probe Request
b. Probe Response
c. Beacon
d. Association Response

Answer 6

Probe request

Question 7

A client station must do what when it detects a change in the WMM parameter settings in a Bacon frame when it is associated with the transmitting AP?
a. Nothing
b. Disconnect
c. Change its WMM parameters to match every time
d. Change its WMM parameters to match if not using Voice

Answer 7

Change it’s WMM parameters to match every time

Question 8

What is the purpose of the duration field in relation to the DCF and EDCA procedures?
a. configure the NAV timer in the hearing STAs
b. Configure the random backoff timer in the hearing STAs
c. Hearing stations can select the appropriate IFS based on the value
d. Nothing, it does not play a role in either procedure

Answer 8

configure the random backoff timer in the hearing STAs

Question 9

What is a key differentiator between DCF and EDCA?
a. EDCA requires the use of SIFS and DCF does not
b. EDCA requires the use of a random backoff timer and DCF does not
c. EDCA allows for variable contention window ranges and DCF does not
d. EDCA can use shorter slot times than DCF

Answer 9

EDCA allows for variable contention window ranges and DCF does not