A method includes generating an indicator of interference introduced by a transmitter into a spectrum of an output transmit signal outside a target channel of the transmitter. The indicator is generated based on the output transmit signal. The method includes adjusting a power level of the output transmit signal based on the indicator and a predetermined interference indicator level. The indicator may indicate a carrier-to-interference (C/I) ratio of the output transmit signal, and the adjusting comprises setting the power level of the output transmit signal to a maximum power level that maintains the C/I ratio of the output transmit signal above the predetermined interference indicator level. The output transmit signal may be based on a radio-frequency output of a power amplifier of the transmitter prior to transmission over a channel and the generating comprises generating a baseband version of the output transmit signal.