Sometimes RSL is out of the ATPC threshold range when the ATPC function is enabled. The possible cause can be one of the following:
1. The ATPC function is during break time.
To prevent continuous adjustments from occupying a large amount of system resources, the ATPC function does not always adjust the transmit power. There is a break between the ATPC adjustments, which is about 5 minutes. Hence, RSL may be out of the ATPC threshold range during the break time.
2. The ATPC adjustment speed is lower than the instantaneous fading speed.
The ATPC adjustment speed may be lower than the instantaneous speed of certain fadings. In this case, the transmit power adjusted by the ATPC function fails to offset the fading in a timely manner and hence, RSL is out of the ATPC threshold range.
3. The transmit power reaches the threshold of the ATPC control range and cannot be increased or decreased.
