In IEEE 802.11 Wireless LAN, the signals are propagated through which media ?
A. (a) Coaxial cable
B. (b) Optical fiber
C. (c) Twisted pair
D. (d) Space (air)
E. (e) Power Line
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What are the purposes of RTS and CTS control frames used in IEEE 802.11 wireless LAN ?
A. (a) Reserve the wireless channel for a time period
B. (b) Informs all nearby nodes that a transmission is about to begin
C. (c) These two frames also contain data to transmit.
D. (d) The sender is asking the receiver to send back a frame after a time period
E. (e) The duration field in the RTS and CTS frames is used to specify the time period
For IEEE 802.11 CSMA/CA protocol, which of the following statements are correct for any node that sees a CTS frame ?
A. (a) It is close to the sender and therefore it can transmit for the period of time specified in the CTS frame.
B. (b) It is close to the receiver and therefore cannot transmit for the period of time specified in the CTS frame..
C. (c) It is not close enough to the receiver to interfere with it, so is free to transmit..
D. (d) It is not close enough to the sender to interfere with it, so is free to transmit.
E. (e) It is close to the receiver and therefore can transmit for the period of time specified in the CTS frame.
For IEEE 802.11 CSMA/CA protocol, which of the following statements are correct for any node that sees an RTS frame ?
A. (a) It is close to the sender and therefore cannot transmit for the period of time specified in the RTS frame.
B. (b) It is close to the sender and therefore can transmit for the period of time specified in the RTS frame.
C. (c) It is not close enough to the receiver to interfere with it, so is free to transmit.
D. (d) It is not close enough to the sender to interfere with it, so is free to transmit.
E. (e) It is close to the receiver and therefore can transmit for the period of time specified in the RTS frame.
For IEEE 802.11 CSMA/CA protocol, what happens if nodes A and B detect an idle link and transmit an RTS frame at the same time ? Assume that nodes A and B are located within the transmission range of each other.
A. (a) Both the RTS frames will be transmitted successfully without collision.
B. (b) These two RTS frames will collide with each other
C. (c) The senders realize the collision has happened when they do not receive the CTS frame after a period of time
D. (d) The senders realize the collision has happened by using a collision detection algorithm like the Ethernet.
E. (e) Collison will happen, and each sender waits a random amount of time before trying again, where the amount of time is defined like the exponential backoff algorithm used in the Ethernet CSMA/CD protocol.
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