LABORATOIRE DE RECHERCHE EN
I NFORMAT I QUE
Energy and Routing Optimization in Wireless Sensor Networks
Joseph Rahmé Advisors:Aline C.Viana and Khaldoun Al Agha
hipercom.lri.fr
Introduction
Energy is a scarce resource in sensor networks.It is thus important to opti
mize energy consumption in order to extend the life of the sensor network.
We introduce a model that quantiﬁes perstate energy consumption (Recep
tion,Sleep,Transmission and Overhearing),and approximates the remaining
energy of a node.
Our cost functions use the information about the remaining energy to calcu
late energyefﬁcient routes.
The Energy Model
We use our model,represented by the following formulas,to quantify the
energy consumed for each node state:
(k) = I
k
[
k
+
2
2
(
2
6
ln(
e
2
k
e
2
k
1
) +
1
2e
2
2
k
+
1
3e
3
2
k
)]
r
(k) = I
k
[
k
+
2
2
(ln(
e
2
(L
k
)
e
2
k
e
2
(L
k
)
1
)
1
2
(
1
e
2
2
L
1
e
2
(L
k
)
)
1
3
(
1
e
3
2
L
1
e
3
2
(L
k
)
)]
Where
(k);
r
(k) are the energy consumed per state with and without recovery,re
spectively.I
k
represents the current value during state duration
k
L is the total duration of a node state including idle time, is the rate at
which the active charges are replenished at the battery’s electrode surface
Our Cost Functions
Our approach consists of four cost functions,and takes the following criteria
into account:
First Cost Function
Goal:minimize the endtoend energy needed to route a packet between a
source and a destination
E
1
(k;i) = E
TX
+
X
n
1
2N
1
(k)
E
RX
+
X
n
2
2N
2
(k)
E
I
(1)
,where
• N
1
(k) is the set of 1hop neighbors of node k;
• N
2
(k) is the set of 2hop neighbors of node k;
• E
TX
,E
RX
and E
I
are the energy consumed for a transmission,recep
tion and overhearing respectively.
Second Cost Function
Goal:Find a route in which intermediate nodes,between a source and a
destination,possess high remaining energy:
E
2
(k;i) = minf(E
r
(k) E
TX
);
min
n
1
2N
1
(k)
(E
r
(n
1
) E
RX
)
min
n
2
2N
2
(k)
(E
r
(n
2
) E
I
)g
(2)
,where
• E
r
(k) is the remaining energy of node k;
• E
r
(n
1
),E
r
(n
2
) are the remaining energy of the 1hop and 2hop neigh
bors affected by the transmission of node k
Third Cost Function
Goal:Find a path with intermediate nodes that have high remaining energy
E
3
(k;i) = min f
E
r
(k)
E
TX
;min
n
1
2N
1
(k)
E
r
(n
1
)
E
RX
;min
n
2
2N
2
(k)
E
r
(n
2
)
E
I
g
(3)
Fourth Cost Function
Goal:Optimize the ﬁrst cost function by considering the remaining energy of
the neighbors
E
4
(k;i) = c
f
E
1
(k;i)
E
r
(i)
;8i 2 N
1
(k) (4)
Results
Illustration of the First and Fourth Cost Functions
Conclusion and Future Work
Simulation results demonstrate that the fourth cost function signiﬁ
cantly increases the network’s lifetime.This is expected since it con
siders both the remaining energy and the endtoend energy consumed.
We next plan to implement the fourth cost functions as a routing metric,
using the OLSR routing protocol,in order to make the routing protocol
energy efﬁcient.
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