Method and apparatus for generating/transmitting a frame for wireless communication, and synchronization estimation method for wireless communication

A method of transmitting a frame for wireless communication, the method comprising:

• transmitting a plurality of repeated signals in time domain for automatic gain control (AGC) during a first orthogonal frequency-division multiplexing (OFDM) symbol interval of the frame;
• and
• transmitting a first sequence on every N-th sub-carrier of a first set of sub-carriers and a second sequence on every N-th sub-carrier of a second set of sub-carriers during a second OFDM symbol interval of the frame, the second OFDM symbol interval immediately following the first OFDM symbol interval,
• wherein sub-carriers other than the every N-th sub-carrier of the first set of sub-carriers and sub-carriers other than the every N-th sub-carrier of the second set of sub-carriers are nulled,
• wherein N is a natural number greater than 1,
• wherein the second sequence is the first sequence multiplied by −1, and
• wherein the first set of sub-carriers and the second set of sub-carriers are non-overlapped with each other.