Adapting a wireless communications link between a transmitter and a receiver involves reducing the RF bandwidth of an uplink communications channel to achieve a desired channel quality. The RF bandwidth of the uplink communications channel is reduced when the desired channel quality is not achieved using the entire available RF bandwidth for uplink communications. Reducing the RF bandwidth of an uplink channel enables the uplink limit of a subscriber unit to be extended beyond what is possible when the entire available RF bandwidth is used for uplink communications. Additional uplink time slots can be allocated to the uplink communications channel with the reduced RF band so that a constant overall transmission rate can be maintained between the transmitter and the receiver.