Project ForgeFor 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.
- AAll I, II, and III
- I and III only
- CII and III only
- DII only
Explanation
I is TRUE: the 2.4GHz band offers 3 non-overlapping channels (1, 6, 11). II is FALSE: RTS-CTS is used for collision AVOIDANCE (CSMA/CA), not detection — wireless networks generally can't reliably detect collisions while transmitting. III is TRUE: 802.11 uses link-layer ACKs for unicast frames precisely because wireless links are unreliable. So I and III only.
Source: GATE CS 2016 (Session 2 / Set B) (2016)
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