A method for dynamically controlling the transmit power of transmission streams transmitted via multiple antennas is disclosed. A transmit power level for multiple streams is determined based on a first reference channel. The difference of signal to interface ratios (SIRs) between two reference channels may represent a power offset. The power offset may be used to determine gain factors used to transmit data channels on the secondary stream with reference to the gain factor of the first reference channel. The power offset may be used to determine other parameters, such a serving grant or transport block sizes of channels carried on the secondary stream. The power offset may allow transmission parameters of channels on the secondary stream to be determined based on the transmit power level of the primary stream and a gain factor for a reference channel transmitted via the primary stream.