Patent ID: 8228921

Claim:
A radio apparatus, comprising: an interface which inputs a plurality of data signals to be transmitted in parallel from a plurality of antennas, each data signal being assigned to at least one stream; a generator which generates a packet signal by arranging the plurality of data signals in a manner that, among the plurality of data signals inputted in said interface, a data signal of a higher data rate is assigned in an anterior part, the packet signal comprising training signals to be assigned to M streams, respectively and the data signals to be assigned to N of M streams, respectively, wherein N and M are integers, N<M, and N is greater than 0; a specifier which specifies a terminal apparatus to which a training signal to be assigned to a stream other than the N of M streams, is to be transmitted, among terminal apparatuses to which the plurality of data signals contained in the packet signal generated by said generator are to be transmitted respectively; an adding unit including: a first adder which appends a training signal to be assigned to a stream other than the N of M streams, to a position anterior to a leading data signal when a data signal which is to be transmitted to the terminal apparatus specified by said specifier is contained in an anterior part of the packet signal generated by said generator; and a second adder which moves a data signal to a posterior part of the packet signal and then appends a training signal to be assigned to a stream other than the N of M streams, to an anterior part preceding the moved data signal and which appends a training signal to be assigned to the N of M streams, to a position anterior to the leading data signal when the data signal which is to be transmitted to the terminal apparatus specified by said specifier is not contained in the anterior part of the packet signal generated by said generator; and a transmitter which transmits the packet signal to which the training signal has been appended by said adding unit.