Figure 4-1 Close-Loop Power Control - Huawei Airbridge BTS3606A Technical Manual

Technical Manual
Airbridge BTS3606A CDMA Base Station
As the CDMA2000 1x system supports the high-speed data service, the
requirement on forward power control becomes higher.
The forward quick power control can control the transmit power of forward channel
accurately. As a result, the interference is reduced and the capacity is increased.
II. Reverse power control
Reverse power control includes open-loop power control and closed-loop power
control. The closed-loop power control can be further classified into inner-loop power
control and outer-loop power control.
Open-loop power control
l
The MS determines the transmit power to access the BTS according to the
strength of the received pilot signal.
Close-loop power control
l
The BTS issues a power control command to the MS, and makes further
adjustment according to the feedback from the MS.
Figure 4-1 illustrates the principle of closed-loop power control.
Power Control Bit
MS

Figure 4-1 Close-loop power control

In the inner-loop power control, the BTS issues the power control bit according to the
received Eb/Nt value.
In the outer-loop power control, the BSC adjusts the Eb/Nt value according to the
Frame Error Rate (FER) of the received reverse signal. Then the BTS uses the newly
set Eb/Nt value to issue the power control bit. In this way, the transmit power of the MS
can be controlled.
III. Rate control (only applied to 1xEV -DO forward link)
1) Forward link
The AT controls the rate of the forward traffic channel through Data Rate Control
(DRC) channel assignment.
2) Reverse link
Eb/Nt
BTS
Inner loop
FER
BSC
Outer loop
4-2
System Description
Chapter 4 Main Functions