Patent ID: 7688901

Claim:
A method of transmitting modulation signals comprising: generating a plurality of modulation signals each of which is to be transmitted from a different one of a plurality of antennas, each modulation signal is to include one or more preamble symbol groups each consisting of a plurality of preamble symbols used for demodulation, inserting the one or more preamble symbol groups at the same one or more temporal points in each modulation signal, wherein the one or more preamble symbol groups at the one or more temporal points are orthogonal to other preamble symbol groups at the same one or more temporal points with zero mutual correlation among the plurality of modulation signals, each preamble symbol having a non-zero amplitude, and each preamble symbol group consisting of preamble symbols the quantity of which is greater than that of the plurality of modulation signals to be transmitted; and transmitting the plurality of modulation signals, each comprising transmission data, which is different between the plurality of modulation signals, and the one or more preamble symbol groups, from the plurality of antennas, respectively, in an identical frequency band.