1. (10 points) Assuming total 6 bytes of addresses, what is the maximum size of IEEE 802.15.4 frame? 2. (10 points) What is the duty cycle? How to achieve a low duty cycle in a wireless sensor mode? network in general? How to achieve a low duty cycle in IEEE 802.15.4 a beacon-enable 3. (15 points) How to configure the parameters of SD and Bl to have the inactive period of 802.15.4 MAC superframe is equal to the active period? Is it possible to have the duty cycle of 20%? 4. (10 points) If the external sensors connected to a sensor node is very energy consuming for sampling an observation, how to reduce the energy consumption of the sensors? Does the reduction of node's duty cycle help? Please explain 5. (25 points) In the 802.15.4 backoff algorithm, let macMaxCSMABackoff-4, CW-2, then what is the possible maximum number of CCAs before a frame is sent out? Show your solution process 6. (15 points) What are RTS and CTS frames for in the IEEE 802.11 (i.e., WiFi)? Suppose the WiFi RTS and CTS frames are longer than the standard DATA frame, would RTS and CTS are useful? Why or Why not? 7. (15 points) Briefly discuss the similarities and differences between WiFi and IEEE 802.15.4 protocols