RF power control is a process of adjusting the power level of a mobile radio as it moves closer to and further away from a transmitter. RF power control is typically accomplished by the sensing the received signal strength level and the relaying of power control messages from a transmitter to the mobile device with commands that are used to increase or decrease the mobile device's output power level.

RF power control is very important to the CDMA system, as the power level that is received from each mobile device must be approximately the same power level as the signals received from other mobile devices. If one mobile device were received at a much higher power level than the other devices, the reception of the lower power channels would be lost in the noise. As a result, more accuracy in power level control can results in received signals of the same level. This results in higher levels of system capacity (more customers can simultaneously operate on the same channel).

To accurately control the RF power level, The IS-95 CDMA RF channel uses a combination of course (open loop) control and precise (closed loop) power control.

Open loop power control is a process of controlling the transmission power level for a mobile device using the received power level and an indicator to how much RF power it should transmit. As the received signal level goes down, the transmitter signal level is increased. Open loop power control provides for...