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The CDMA2000 1X system supports high-speed data services, which has high
requirements on forward power control. The forward fast power control can accurately
control the transmit power of forward channels. As a result, the interference is
minimized and the capacity increases.
4.1.2 Reverse Power Control
Reverse power control includes open-loop power control and closed-loop power
control. The closed-loop power control is further categorized into inner-loop power
control and outer-loop power control.
I. Open-Loop Power Control
The MS determines its transmit power to access the network according to the strength
of the received pilot signal.
II. Closed-Loop Power Control
The BTS sends a power control command to the MS, and adjusts its transmit power
according to the feedback from the MS.
Figure 4-1 shows the closed-loop power control.
Power control bit
MS
Figure 4-1 Closed-loop power control
In the inner-loop power control, the BTS sends the power control bit to the MS
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 reverse signal received. Then the BTS sends power control bits
to the MS based on the new Eb/Nt value. In this way, the transmit power of the MS can
be controlled accordingly.
4.2 Handoff
When the MS moves out of the serving cell/sector or the signal quality deteriorates to
an unacceptable level, the MS hands off to another cell/sector to maintain the ongoing
traffic.
If the system determines that a handoff can help improve the call quality and network
performance, it also triggers a handoff procedure.
Commercial in Confidence
Eb/Nt
BTS/DBS
Inner loop
RRU3606 CDMA Base Station Product Description
FER
BSC
Increment/
decrement of Eb/Nt
Outer loop
Page 16 of 43
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