The present invention provides a system and method for transmitting an ultrawideband (UWB) signal that is composed of an orthogonal frequency-division multiplexing (OFDM) based signal that is transmitted in an underlay manner and an impulse radio based signal that is transmitted in an overlay manner. The system and method are effective in determining an interference temperature for each of multiple carriers within the UWB signal and classifying each one of the multiple carriers of the channel as being an interfered carrier or a non-interfered carrier based on the interference temperature for each one of multiple carriers. The desired signal is then transmitted on the interfered carriers at a signal power that is not greater than the power limit of the underlay UWB policy and on the non-interfered carriers at a signal power that is greater than the power limit of the underlay UWB policy.