Disclosed is an apparatus for performing power control on a reverse
channel quality indicator channel (CQICH) received from a mobile station
by a base station in a mobile communication system including the base
station for transmitting a power control bit for power control on reverse
channels and the mobile station for controlling transmission power of the
reverse channels according to the power control bit. An erasure detector
determines whether to perform an erasure process by measuring reception
power of the reverse channel quality indicator channel. An erasure rate
calculator accumulates the erasure-determined result for N slots and
calculates an erasure rate for the N slots. A control bit generator
determines a ratio control bit to be transmitted to the mobile station
according to the erasure rate, to issue a command to increase or decrease
a CQICH traffic-to-pilot ratio.