
Energy Efficient RNs in Cellular Networks 89
Figure 3.12: Cellular system.
Normally, the received signal from a BS suffers from path-loss, slow fading
and fast fading. A simple model taking path-loss into consideration is given
as [64]
PL(dB)=15.3+37.6log
10
(d), (3.66)
where d is the BS-UE distance in meters. The shadowing SF(dB) follows a
log-normal law with mean 0 and shadowing standard deviation SD.Based
on this propagation model, the long-term power received by a UE from a BS
(BS
i
) can be expressed in dB as
P (BS
i
→ UE)=P
Tx
+ G
UE
+ G − PL(d) − SF(BS
i
→ UE), (3.67)
where P
Tx
is the transmission power of the BS, G is the antenna gain, d is
the BS-UE distance