The first is used to determine what fraction of the total NodeB transmit
power is required to meet a certain performance target. The second is used to control the amount of
interference seen by the UE, by introducing a dependency on distance separated from the NodeB.
We will use these variables plus others to help in the system performance study.
We will consider two values from the downtown London geometry values, specifically Ior/Ioc10
and 5 dB. These geometry values correspond to approximately 97% and 5% occurrence. These
G
Ior
Ioc
I^
or
aEc
IorbCommon
aEc
IorbShared
aEc
IorbDedicated
aEc
IorbOCNS
1
386 CHAPTER SEVEN
FIGURE 7.56 Definition of NodeB power allocation.
U
E
+
Common
+
Shared
+
Dedicated
+
OCNS
Ior
Ior
Ioc
Other Cell Interference
Io = Ior + Ioc + N
Path Loss
N
Noise NodeB
?†
?†
values were chosen to represent the UE location near the NodeB and at the cell edge, respectively.
Generally speaking, the Eb/No equation assuming QPSK modulation is given below.
(7.64)
The assumed power allocation for P-CCPCH is Ec/Ior12 dB. The SNR per bit of the P-CCPCH
is given as follows
(7.65)
Similarly, we have
(7.66)
We can clearly see the difference in Eb/No and expect significant difference in BER, depending on the
channel conditions.
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