A mobile terminal transmits one or more first communication channels in a first frequency region and one or more second communication channels in a second frequency region. With the channels experiencing different fading conditions, the terminal receives separate transmit power control (TPC) commands. Instead of simply adjusting the transmit power of the channels as commanded, the terminal computes a power offset indicative of the difference between the commanded power of one or more of the first channels and the commanded power of one or more of the second channels. The terminal then selectively performs transmit power control of the first and second channels on either an independent basis, according to the respective TPC commands, or a joint basis, depending on whether the computed power offset falls outside of a pre-determined range of values. In doing so, the terminal allows independent control of channels, while also mitigating self-interference and/or spectral emissions.