A communication device (1 ) for communicating in a multiple channel communication system comprises means (9) for calculating an effective noise level of one of the channels of the system by applying an expectation operator to an estimated noise level affecting the channel based on time varying characteristics of the estimated noise level. The calculation of the effective noise level may also be based on an estimated path loss. The calculation of the effective noise level may also be based on an initial power level allocated to the respective channel. The effective noise level calculated for each channel may be employed in calculating power levels to be allocated to the respective channels.