In the 802.11 frame, what kind of control message should the terminal send to obtain access to the wireless medium?

Question

Options

• ARTS
• BCTS
• CACK
• DPS-Poll

• A
  71% (15)
• B
  10% (2)
• C
  5% (1)
• D
  14% (3)

Explanation

RTS (Request to Send) is the message a terminal transmits when it wants to gain access to the wireless medium under the 802.11 RTS/CTS collision-avoidance mechanism. The terminal sends RTS first; the access point then responds with CTS (Clear to Send), which is why B is wrong - CTS originates from the access point, not the terminal. ACK (option C) is sent after a frame is successfully received to confirm delivery, so it comes at the end of an exchange, not the beginning. PS-Poll (option D) is a power-management frame used by stations in sleep mode to retrieve buffered data from the access point - it has nothing to do with requesting medium access.

Memory tip: Think of the sequence as a conversation - the terminal Requests to Send (RTS), then waits for the network to say it's Clear to Send (CTS). The terminal always speaks first with an R before the network replies with a C.

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