$1.$ In comparison to Aloha protocols, why does listening to the channel first before transmission help improve throughput?

$2.$ Consider Frame Slotted Aloha. Assume there are N devices sharing a channel, and the frame length is F$.$ Consider the following scenarios: $($i$)$ N is much bigger than F$,$ and $($ii$)$ N is much smaller than F$.$ For each scenario, discuss the probability of collisions, successful transmissions, and slots with no transmissions $($aka idle slots$).$

$3.$ In CSMA$/$CA$,$ nodes send a RTS and CTS message. Why do these messages ensure collision won$$t happen during data transmission?

a$.$ Will RTS or CTS message experience collision? Yes$/$No$?$

b$.$ The duration field in each RTS or CTS message indicates $\_\_\_\_\_?$

$4.$ For each question, answer True$/$False

a$.$ TDMA has no packet collisions. That is$,$ nodes using TDMA experience no collisions.

b$.$ Slotted Aloha doubles the throughput of basic $($pure$)$ Aloha.

c$.$ A node using CSMA hears that a channel is busy. It should always transmit immediately

when the channel is busy to avoid collision.

d$.$ Assume nodes use CSMA on a channel, where they can hear each other. They are

guaranteed to experience no collision.

e$.$ The binary exponential backoff $($BEB$)$ algorithm guarantees collision free transmissions.

$5.$ In HDLC$,$ the primary user coordinates channel access. This method or MAC is also called $\_\_\_\_\_\_\_?$

$6.$ Assume a wireless network where all devices can hear each other. A network engineer disables the

use of RTS$/$CTS on all devices. Is this wise? If so$,$ why?

$7.$ In the backoff process, a device selects a random number. What does this number correspond to$?$

$8.$ The binary exponential backoff $($BEB$)$ algorithm requires the contention window size to double

whenever there is a collision. How does this help reduce collision?

$9.$ In a frequency hopping system, a sender and its corresponding receiver must have the same

frequency hopping sequence. True$/$false$?$

$10.$ In the CSMA$/$CD channel access method, a sender must transmit and listen at the same time.

True$/$False$?$

$11.$ Identify the corresponding Medium Access Control Protocol for each behaviour