A method and apparatus for efficiently controlling uplink traffic rates, performing scheduling accompanied by fast rate ramping, and transmitting uplink rate assignment information in an asynchronous WCDMA communication system. A Node B determines an allowed current rate for an uplink channel. If the difference between the current rate and the previous rate is two or more levels, the Node B transmits a rate indication indicating the current rate. If the difference between the current rate and the previous rate is zero or one level, the Node B transmits a rate up/down indicating a rate change from the previous rate to the current rate. Also the Node B may transmit the rate indication instead of the rate up/down, periodically or in an event-triggered manner.