
32 Wireless Networks Resources Trading for QoS Performance
0.2
0.4
0.6
0.8
1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
x 10
5
w
t
E
Figure 2.2: Energy per bit versus bandwidth per bit and delay time.
and Table 2.1 imply that there exists the minimum energy consumption by
trading other resources. Because we need to derive the trading relationships
between energy consumption and bandwidth/delay, respectively, we analyze
each trading relationship with the fixed value of another resource.
For fixed t, the relationship between E and W is given by (setting t =1
for simplicity)
E
bt
=
2
1
W
− 1
WN
0
g
+ WP
cir
+ P
sb
(2.6)
For fixed W , the relationship between E and t is expressed ...