A code-division-multiple-access (CDMA) system employing spread-spectrum modulation.
The CDMA system has a base station (BS), and a plurality of subscriber units. The
signals transmitted between the base station and subscriber unit use spread-spectrum
modulation. The improvement method for adaptive reverse power control (APC) from
a subscriber unit (SU) to a base station (BS), comprises the steps of sending from
the subscriber unit, using spread-spectrum modulation, a SU-spreading code on a
reverse channel. The base station despreads the SU-spreading code on the reverse
channel as a despread signal, determines a first power level Pd which
includes power of the despread signal plus noise and a second power level PN,
which includes despread-noise power. The base station determines a first error
signal e1, from the first power level Pd, the second power
level PN, and a required signal-to-noise ratio SNRREQ for
service type, and a second error signal e2, from a measure of total
received power Prt at the base station, and an automatic gain control
(AGC) set point Po. The base station forms a combined error signal from
the first error signal e1, the second error signal e2, a
first weight a1, and a second weight a2, and hard limits
the combined error signal to form a single APC bit. The APC bit is transmitted
to the subscriber unit. In response to the APC bit, the subscriber adjusts transmitter
power to the base station.