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Exam July 27, 2016 July 7, 2016 21 PANC 3 45 6 78 Figure 1: Reference topology for Ex. 1. Exercise–1 (July 27, 2016) The Personal Area Network in the figure is operated according to the IEEE 802.15.4 beacon enabled mode with the following parameters: (i) active part composed of CFP only (no CAP) with slots of 128 [byte] packets; (ii) nominal data rate is 250 [kbit/s]. The 8 motes in the figure are characterized by the following uplink tra c requirements: •motes 1, 3, 5 and 7 generate uplink tra c whose rate has the following distribution: P(r=25[bit/s])=0.4 P(r=50[bit/s])=0.6 •motes 2, 4, 6 and 8 generate uplink tra c whose rate has the following distribution: P(r=50[bit/s])=0.2 P(r=1[kbit/s])=0.8 Motes 1 and 2, besides sending up to the PANC their own tra c, have to relay in each BI the tra c generated by their siblings nodes. Define a consistent Beacon Interval structure including the number of slots in the CFP, the Beacon Interval duration, and the duty cycle. Define a consistent slot assignment in the CFP for all the devices in the network. Solution of Exercise–1 The lowest required rate is 25 [bit/s]. Thus, the BI can be set as: BI= 128[byte] 25[bit/s]= 40.96[s]. Motes 1, 3, 5 and 7 require 2 slots in the BI for their own tra c. Motes 2, 4, 6 and 8 require 40 slots in the BI for their own tra c. Moreover, Mote 1 1 and Mote 2 also require extra slots for receiving and delivering tra c from their sibling nodes. Namely, Mote 1 requires extra 88 slots and Mote 2 requires extra 164 slots. To sum up, we have: N3=N5=N7= 40 N4=N6=N8=2 N1= 90 N2= 204 which leads to:NCFP= 40⇥3+2⇥3 + 90 + 204 = 422. The slot duration isTs=128[byte] 250[kbit/s]=4.096[ms]. The duration of the active and inactive parts and the duty cycle are, respectively: Tactive=(NCFP+ 1)⇥Ts=1.72[s] Tinactive=BI…