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Unformatted text preview: WLAN Assignment I Question: Consider a CSMA/CA 802.11 WLAN with three stations A, B and C. The following are values used in the BSS: DIFS = 34sec SIFS = 16sec Slot Time = 9sec ACK = 20sec The three nodes have following data packets in their output MAC queues waiting to be transmitted: (The numbers indicate the transmission time of a frame in the medium in Slot Times ). The three frames have not experienced any previous collisions. Within brackets we show the type of application data the node is attempting to transmit. Node A: 10 Slot times (ftp) Node B: 5 Slot times (video-conferencing) Node C: 7 Slot times (e-mail) The following table gives the values of back-offs chosen by the nodes incase of collisions. Node First Attempt Collision 1 A 3 3 B 3 4 C 5 4 Assume that some node X has finished transmitting an ACK frame at time t = 0. Draw a time chart to show what happens in the medium starting at time t = 0 to the end of transmission of all 3 frames. How do you think the protocol performed in terms of fairness to the application data? (a)...
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- Fall '08