
154 Energy-Efficient Cooperative Wireless Communication and Networks
Direct transmission
Proposed approach
Random relay
10
0
10
–1
Normalized average power consumption
10
–2
5678
Number of nodes
910
ε
0
= 0.1
ε
0
= 0.01
ε
0
= 0.001
FIGURE 10. 4 Normalized average power consumption per node versus the
number of nodes, where α =3,
0
= {0.1, 0.01, 0.001}, R =1.
approach consumes less energy than both the random relay selection ap-
proach and direct transmission by a factor of 1/2 and 1/9 when
N =5,
respectively; this gain becomes larger when
N increases. Furthermore, as
the network density increases, the average energy consumption of both the
proposed approach and the