Automatic power control system for a code division multiple access (CDMA) communications system

DETAILED DESCRIPTION The present invention includes a system and method for closed loop automatic power control (APC) for a base radio carrier station (RCS) and a group of subscriber units (SUs) of a spread-spectrum communication system.
The SUs transmit spread-spectrum signals, the RCS acquires the spread-spectrum signals, and the RCS detects the received power level of the spread-spectrum signals plus any interfering signal including noise.
The APC system includes the RCS and a plurality of SUs, wherein the RCS transmits a plurality of forward channel information signals to the SUs as a plurality of forward channel spread-spectrum signals having a respective forward transmit power level, and each SU transmits to the base station at least one reverse spread-spectrum signal having a respective reverse transmit power level and at least one reverse channel spread-spectrum signal includes a reverse channel information signal.
The APC includes an automatic forward power control (AFPC) system, and an automatic reverse power control (ARPC) system.
The AFPC has the steps of each SU measuring a forward signal-to-noise ratio of the respective forward channel information signal, generating a respective forward channel error signal which includes a measure of the forward error between the respective forward signal-to-noise ratio and a pre-determined signal-to-noise value.
The forward channel error signal also includes a measure of the uncorrelated noise in the channel.
The respective forward channel error signal is transmitted by the SU as part of a respective reverse channel information signal.
The RCS includes a plural number of AFPC receivers for receiving the reverse channel information signals and extracting the forward channel error signals from the respective reverse channel information signals.
The RCS also adjusts the respective forward transmit power level of each one of the respective forward spread-spectrum signals responsive to the respective forward error signal.
The portion of the ARPC system in the RCS measures a reverse signal-to-noise ratio of each of the respective reverse channel information signals, generates a respective reverse channel error signal which includes a measure of the error between the respective reverse channel signal-to-noise ratio and a respective pre-determined signal-to-noise value