Transmission method and transmission apparatus for packet format detection

A transmission apparatus comprises circuitry that generates a physical protocol data unit (PPDU) that contains a legacy signal field and a first signal field wherein both of the legacy signal field and the first signal field comprise an Orthogonal Frequency Division Multiplexing (OFDM) symbol, and the first signal field is derived from the legacy signal field, and a transmitter, which, in operation, transmits the PPDU. A format of the PPDU is indicated based on whether a part of bits of the first signal field is inverted or not. The format of the PPDU is a first format or a second format, and data subcarriers of the first signal field in the second format have inverted values of corresponding values in the legacy signal field, and pilots of the first signal field in the second format are not inverted and have same values of corresponding values in the legacy signal field.