Patent ID: 8116389

Claim:
A radio apparatus, including: a generation unit configured to generate a packet signal formed by a plurality of streams, by using a plurality of subcarriers for forming a bandwidth and by selectively using a first packet format including first legacy known signals for a first radio communication system different from a second radio communication system, second legacy known signals for the first radio communication system, and first MIMO known signals for the second radio communication system, the first legacy known signals, the second legacy known signals, and the first MIMO known signals being arranged in that order, or a second packet format including a second MIMO known signals for the second radio communication system and the first MIMO known signals, the second MIMO known signals and the first MIMO known signals being arranged in that order, no first and second legacy known signals being included in the second packet format; and a transmitter which transmits the packet signal generated by the generation unit, wherein the first legacy known signals and the second MIMO known signals are for AGC (auto gain control) estimation, the second known legacy signals and the first MIMO known signals are for channel estimation, subcarriers for the first MIMO known signals have a bandwidth which has the same center frequency as that of subcarriers for the second legacy known signals and which is broader than that of subcarriers for the second legacy known signals, said generation unit executes a cyclic time shifting for the first and second MIMO known signals and the first and second legacy known signals with shift amounts being varied across the plurality of streams, a maximum absolute shift amount among absolute shift amounts for the first MIMO known signals in the plurality of streams is greater than absolute shift amounts for the second legacy known signals in the plurality of streams, and a maximum absolute shift amount among absolute shift amounts for the second MIMO known signals in the plurality of streams is greater than absolute shift amounts for the first legacy known signals in the plurality of streams.