Carrier Sense Multiple Access: CSMA In WIFI systems, nodes adopt CSMA MAC protocol to access to the shared media through contention. At the beginning, CWmin = 31 meaning that there are 32 slots available for users. Answer the following questions and assume that there are three active node A, and node B where Nusr = 2.

1. At the beginning, if node A pick up the back off counter BC = 16, what is probability to win the channel contention?
2. However, after 8 slots node A detected that some other node began to send package. Does node a have a better chance to win the contention in next round? What is the probability then?
3. Finally, node A won the channel content and sent package but did not get ACK after SIFS and assumed that a collision occurred. What is the probability for node A to win the next round content to channel then?
4. If there were 1200 packets sent successfully during a certain period. How many packets are sent by node A?

Assume that there is one active user, Nusr=1. The packet size is 2048byte and date rate 24Mbits/s. What are the minimal, maximum and average of throughputs?