In a combination of control signals on data signals and the data signals where the combination contains data signals to be assigned respectively to a plurality of streams, a control unit assigns a control signal contained in a leading combination and assigns a data signal, contained in the leading combination, to a position posterior to the assigned control signal. The control unit appends a known signal to at least one of the remaining combinations and then assigns sequentially the remaining combinations to a position posterior to the assigned data signal so as to generate packet signals.