GATE | GATE-CS-2016 (Set 2) | Question 64
For the IEEE 802.11 MAC protocol for wireless communication, which of the following statements is/are TRUE?
I. At least three non-overlapping channels are available for transmissions. II. The RTS-CTS mechanism is used for collision detection. III. Unicast frames are ACKed.
(A) All I, II, and III
(B) I and III only
(C) II and III only
(D) II only
Explanation: 802.11 uses 5 GHz Radio Band(High Frequency) which has 23 overlapping channels rather than the 2.4 GHz frequency band which has only three non-overlapping channels.
RTS(Request To Send) and CTS(Clear To Send) are control frames, which facilitate the exchange between stations and help in collision reduction and not DETECTION. As Station 1 would send data frame to Station 2, only when it receives a CTS frame.
First Station 1 sends a RTS to Station 2, in response Station 2 sends back CTS. After data is received by Station 2, it send Acknowledgement frame(ACKed). As Station 2 sends a Acknowledgement to a single recipient on a network, Unicast Frames are acknowledged.
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