802.11 CSMA/CA WITHOUT Hidden Terminals The Access Point hears all mobile stations. Each mobile station can hear the other mobile stations. Access Point SER Mobile Station There is one access point and three mobile stations. The mobile stations can hear each other's transmissions. To operate the animation, first click on "Start". Then click on a station button whenever you want that station to emit a frame. Reset Start Simulation is ready Emit frame Station 1 Station 2 Station 3 Access Point Legend Frame types Carrier sensing RTS Medium free CTS Medium busy Data frame NAV Medium considered busy ACK Countdown Queue BackOff 0 0 0 0 0 0 Consider the snippet from a trace from an 802.11 simulator, one of them found here: https://wps.pearsoned.com/ecs_kurose_compnetw 6/216/55463/1419 8702.cw/index.html. Some observations: At A, we can see that station 3's transmission overlaps station 1's. At B, we see station 3's transmission ends before 2's begins. At C, we see the first part of a countdown from station 1. What type of simulator are we running? (5 Points) 802.11 with no hidden terminals 802.11 with hidden terminals A combination of the two 802.11 CSMA/CA WITH Hidden Terminals The Access Point hears all mobile stations. A mobile station can hear the access point but cannot hear any of the other mobile stations. CD I C Access Point SASA Mobile Station There is one access point and three mobile stations. To operate the animation, first click on "Start". Then click on a station button whenever you want that station to emit a frame. Simulation is ready Reset Start Emit frame Station 1 Station 2 Station 3 Access Point Legend Frame types Carrier sensing RTS Medium free CTS Medium busy Data frame NAV Medium considered busy ACK Countdown Queue BackOff 0 0 0 0 0 0 Continuing, assuming the access point functions properly, will any station receive a CTS based on this snippet? (5 Points) Yes, station 1 since it began first. Yes, station 2, since it is in the last row, right above the AP and thus able to overwhelm station 1's transmission. Yes, station 3, since its request is unobstructed Nobody will receive a CTS until each completes a collision countdown. 3 Continuing, based on the time marked as C, what could happen immediately next? Choose 3. (10 Points) Station 1 will be the next to transmit a packet based on the fact that it is in countdown Station 1 could finish its countdown and begin sending a request-to-send. The AP could transmit a CTS for station 2 The AP could transmit a CTS for station 1 Station 3 could start a countdown Station 3 could begin transmitting an RTS with no countdown needed