Cyber-Physical Systems

552 Cyber-Physical Systems: From Theory to Practice

0 500 1000 1500 2000 2500 3000 3500 4000

200

400

600

800

1000

1200

1400

1600

1800

2000

Number of alive nodes

Events

a=0

a = 0.25

a=0.5

a = 0.75

a=1

FIGURE 21.8 Alive nodes over time (varying α).

slices that this special charger is responsible for. More precisely, special charger k transfers to mobile

charger m an amount of energy

e = c

m

·



min{E

lack

m

, E

k

}



with c

m

=



i∈D

m

E

lack

i



j∈C

k



i∈D

j

E

lack

i

∈ (0, 1),

where E

lack

i

= E

max

node

− E

i

is the amount of energy that node i can receive until it is fully

charged.

21.6.6 PROTOCOL EVALUATION

We conduct a performance evaluation of the hierarchical collaborative charging protocols. In