A wireless transmitting device for communicating with a wireless receiving device by using a first wireless packet, the wireless transmitting device comprising: a first signal generator configured to generate a signal of the first wireless packet, the first wireless packet including: a short-preamble used for a first automatic gain control at the wireless receiving device, a first long-preamble following the short-preamble, used for a first estimation of a first channel response between the wireless transmitting device and the wireless receiving device, a first signal field following the first long-preamble, and used for conveying first information regarding the first wireless packet, a second signal field following the first signal field, and used for conveying second information regarding the first wireless packet, an AGC preamble (105A to 105D) following the second signal field, and used for a second automatic gain control performed after the first automatic gain control at the wireless receiving device, a second long-preamble (106A to 106D, 107A to 107D, 108A to 108D, 109A to 109D) used for a second estimation of a second channel response between the wireless transmitting device and the wireless receiving device, and a data field (110A to 110D) conveying data, wherein a signal of the AGC preamble is to be transmitted via at least a first antenna and a second antenna, a signal of the AGC preamble to be transmitted via the first antenna is the same as a signal obtained by performing a cyclic shift in the time domain on a signal of the AGC preamble to be transmitted via the second antenna, a signal of the second long-preamble is to be transmitted via at least the first and second antennas, a signal of the second long-preamble to be transmitted via the first antenna and a signal of the second long-preamble to be transmitted via the second antenna are subject to orthogonalization based on a Walsh sequence, and a signal of the data field is to be transmitted via at least the first antenna and the second antenna. a first signal generator configured to generate a signal of the first wireless packet, the first wireless packet including: a short-preamble used for a first automatic gain control at the wireless receiving device, a first long-preamble following the short-preamble, used for a first estimation of a first channel response between the wireless transmitting device and the wireless receiving device, a first signal field following the first long-preamble, and used for conveying first information regarding the first wireless packet, a second signal field following the first signal field, and used for conveying second information regarding the first wireless packet, an AGC preamble (105A to 105D) following the second signal field, and used for a second automatic gain control performed after the first automatic gain control at the wireless receiving device, a second long-preamble (106A to 106D, 107A to 107D, 108A to 108D, 109A to 109D) used for a second estimation of a second channel response between the wireless transmitting device and the wireless receiving device, and a data field (110A to 110D) conveying data, wherein a short-preamble used for a first automatic gain control at the wireless receiving device, a first long-preamble following the short-preamble, used for a first estimation of a first channel response between the wireless transmitting device and the wireless receiving device, a first signal field following the first long-preamble, and used for conveying first information regarding the first wireless packet, a second signal field following the first signal field, and used for conveying second information regarding the first wireless packet, an AGC preamble (105A to 105D) following the second signal field, and used for a second automatic gain control performed after the first automatic gain control at the wireless receiving device, a second long-preamble (106A to 106D, 107A to 107D, 108A to 108D, 109A to 109D) used for a second estimation of a second channel response between the wireless transmitting device and the wireless receiving device, and a data field (110A to 110D) conveying data, wherein a signal of the AGC preamble is to be transmitted via at least a first antenna and a second antenna, a signal of the AGC preamble to be transmitted via the first antenna is the same as a signal obtained by performing a cyclic shift in the time domain on a signal of the AGC preamble to be transmitted via the second antenna, a signal of the second long-preamble is to be transmitted via at least the first and second antennas, a signal of the second long-preamble to be transmitted via the first antenna and a signal of the second long-preamble to be transmitted via the second antenna are subject to orthogonalization based on a Walsh sequence, and a signal of the data field is to be transmitted via at least the first antenna and the second antenna.