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Internet of Things, Exam– July 1, 2015 Family Name Given Name Student ID Total Available time: 2 hours 1 – Exercise (7 points) The two-hop personal area network (PAN) in the figure is composed of 4 motes and a PAN Coordinator. The PAN works in beacon-enabled mode. Ø Mote 1 and Mote 2 have statistical (non-deterministic) traffic towards the PAN coordinator characterized by the following probability distribution: P(required rate=75[bit/s])=0.5, P(required rate=225 [bit/s])=0.1, P(required rate=0 [bit/s])=0.4. Ø Mote 3 and Mote 4 have deterministic traffic towards the PAN coordinator with a required rate of 450 [bit/s]. Assuming that: Ø the active part of the Beacon Interval (BI) is composed of Collision Free Part only Ø The collision free part is divided in two: the first part is dedicated to the transmissions from Motes 1, 2 and 3 towards Mote 4, the second part is used by Mote 4 to deliver its own traffic and the relayed one to the PANC. Ø the motes use b=128 [bit] packets to communicate with the PANC which fit exactly one slot in the CFP Ø the nominal rate is 250 [kb/s] Find the duration of the single slot, the duration of Beacon Interval (BI), the duration of the CFP and the duration of the inactive part, a consistent slot assignment for the four motes, and the duty cycle 2 – Exercise (4 points) The nodes in the figure exchange packets of L=128[byte] which are acknowledged with ACKs of the same size. The figure reports for each wireless link the corresponding link capacity C and Expected Transmission Count (ETX) in the form <ETX – C>. Find the Expected Transmission Time (ETT) metric for all the wireless links (assume negligible propagation delay); find the shortest path from node A to node B using the ETT as routing metric. 1" 2" 3" 4" PANC" A" B" 1.2"'"100"[kb/s]"…