06 02 17

Page 1

Internet of Things, Exam 6-2-2017 Available time: 1 hour, 30 minutes 1 – Exercise (7 points) A personal area network (PAN) is composed of 4 motes and a PAN Coordinator. The PAN works in beacon-enabled mode. Mote 1 and Mote 2 have statistical (non-deterministic) traffic towards the PAN coordinator characterized by the following probability distribution: P(r1,2=75[bit/s])=0.6, P(r1,2=225 [bit/s])=0.2, P(r1,2=0 [bit/s])=0.2. Motes 3 and 4 have deterministic traffic towards the PAN coordinator with a required rate, r3,4 of 225 [bit/s]. The PAN coordinator has to deliver downlink traffic towards the four nodes according to the following pattern: traffic towards Mote 1 and Mote 2 P(r1,2PANC=75[bit/s])=0.5, P(r1,2PANC =225 [bit/s])=0.1, P(r1,2PANC =0 [bit/s])=0.4; traffic towards Mote 3 and 4 deterministic with required rate r3,4PANC 75 [bit/s]. Assuming that: (i) the active part of the Beacon Interval (BI) is composed of Collision Free Part only; (ii) the motes and the PAN coordinator use b=128 [bit] packets for their transmissions which fit exactly one slot in the CFP, (iii) 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, the duration of the inactive part, a consistent slot assignment for all the transmissions (UPLINK AND DOWNLINK), and corresponding the duty cycle. Assuming that the energy consumption parameters are the following ones, find the average energy consumption in a beacon interval for the PAN coordinator; energy for receiving a packet Erx =4[uJ], energy for transmitting a packet Etx =7[uJ], energy for being idle in a slot Eidle = 3[uJ], energy for sleeping in a slot Esleep = 3[nJ]. 2 – Exercise (6 points) 3 – Exercise (4 points) A RFID system based on Dynamic Frame ALOHA is…