1. A radio apparatus, comprising: an input unit which inputs a plurality of data signals each of the data signals being composed of a plurality of streams; a generation unit which generates a single packet signal composed of a plurality of streams, based on the plurality of data signals inputted in said input unit; and a transmitter which multiplies the packet signal, generated by said generation unit, by a weight vector for each of the plurality of streams and which transmits the packet signal multiplied by the weight vector, wherein said generation unit appends a common known signal to a leading part of the plurality of data signals and appends a dedicated known signal to a position anterior to a data signal by which a dedicated weight vector is to be multiplied in said transmitter among the plurality of data signals, and wherein, among the packet signals generated by said generation unit, said transmitter multiplies the dedicated known signal and a data signal placed posterior thereto by the dedicated weight vector and, among the packet signals generated by said generation unit, said transmitter multiplies a part, where no dedicated weight vector is to be multiplied, by a common weight vector.