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Internet of Things, Exam– July 28, 2014 Total Available time: 2 hours Family Name Given Name Student ID 1 – Exercise (7 points) A personal area network (PAN) is operated according to the IEEE 802.15.4 beacon enabled mode. • The Collision Access Part (CAP) of the superframe is composed of 20 slots. • The inactive part of the beacon interval is composed of 1600 slots and the duty cycle is 2.02%. • Each slot (of CAP and CFP) carries 127 [byte] packets. • The nominal data rate is 250 [kb/s]. How many slots are available in the CFP? What is the rate of the channel defined as “one slot per beacon interval”? Using the numbers found above, suppose that two motes (Mote 1 and Mote 2) are active in the PAN with the following traffic patterns Ø P(amount of data generated in one BI=508[byte])= 0.3 Ø P(amount of data generated in one BI =0 [byte])= 0.3 Ø P(amount of data generated in one BI=635 [byte])= 0.4 1. Define a consistent slot assignment in the CFP for the two motes (the motes do not use the CAP). 2. How many additional motes requiring a channel of 150 [bit/s] could be added to the network? 3. Find the average energy consumption of the two motes (assume that the two motes do not overhear the transmissions of each other). The total energy for receiving in a slot is Erx=20 [uJ], the total energy to transmit in a slot is Etx=30[uJ], the energy of being idle in a slot is Eidle = 15 [uJ] and the energy for sleeping in a slot is Esleep = 0.5 [uJ] 4. What is the total capacity of the CAP? Exercise 2 (7 points) A sensor network is composed of a three nodes and a sink (see figure). Node 1, Node 2 and Node 3 periodically have to deliver to the sink packets whose length is l=128 [byte]. Assuming that: • the energy required to operate the TX/RX circuitry is Ec=50 [nJ/bit], • the energy…