$(15$ Points $)$

$4$

a$)$

i$.$ What is CSMA$/$CA in WLAN MAC and how it works?

ii$.$ Describe CSMA CA that uses RTS and CTS frames in channel reservation $($use diagram to explain$).$

iii. What are the differences between WLAN and Cellular networks?

b$)$ Describe with two examples how SDN is used in overwriting routing on$-$demand $($use examples you have learned in class$)$

$4$