A transmission device, comprising: a signal processing circuit that is configured to generate an aggregate physical layer convergence protocol data unit, A-PPDU, by adding a guard interval to each of a first part of a first physical layer convergence protocol data unit, PPDU, a second part of the first PPDU, and a second PPDU (2002, 2003); wherein the first PPDU includes a legacy STF, a legacy CEF, a legacy header field, a non-legacy STF, a non-legacy CEF, a non-legacy header field including one or more non-legacy headers, and one or more data fields including one or more payload data, wherein the first part of the first PPDU includes: - the legacy STF and N-1 duplicates of said legacy STF in a frequency axis direction, - the legacy CEF and N-1 duplicates of said legacy CEF in a frequency axis direction, - the legacy header field and N-1 duplicates of said legacy header field in a frequency axis direction, and - the non-legacy header field and N-1 duplicates of said non-legacy header field in a frequency axis direction; and the second part of the first PPDU includes the non-legacy STF, the non-legacy CEF, and the one or more data fields; and wherein the second PPDU (2002, 2003) includes one or more non-legacy header fields (2011, 2013) including one or more non-legacy headers, and one or more data fields (2012, 2014) including one or more payload data; and a wireless circuit that is configured to transmit the A-PPDU, wherein: - each of the legacy STF, the legacy CEF, the legacy header field, the non-legacy header field of the first PPDU, the N-1 duplicates of said legacy STF, the N-1 duplicates of said legacy CEF, the N-1 duplicates of said legacy header field, and the N-1 duplicates of said non-legacy header field of the first PPDU is transmitted using a predetermined channel bandwidth; - the second part of the first PPDU and the second PPDU (2002, 2003) are transmitted using a variable channel bandwidth that is N times the predetermined bandwidth; and - in a case where the wireless circuit transmits the first PPDU and the second PPDU (2002, 2003) by single carrier, each of the one or more non-legacy header fields (2011, 2013) of the second PPDU (2002, 2003) includes a non-legacy header that has been repeated N times. a signal processing circuit that is configured to generate an aggregate physical layer convergence protocol data unit, A-PPDU, by adding a guard interval to each of a first part of a first physical layer convergence protocol data unit, PPDU, a second part of the first PPDU, and a second PPDU (2002, 2003); wherein the first PPDU includes a legacy STF, a legacy CEF, a legacy header field, a non-legacy STF, a non-legacy CEF, a non-legacy header field including one or more non-legacy headers, and one or more data fields including one or more payload data, wherein the first part of the first PPDU includes: - the legacy STF and N-1 duplicates of said legacy STF in a frequency axis direction, - the legacy CEF and N-1 duplicates of said legacy CEF in a frequency axis direction, - the legacy header field and N-1 duplicates of said legacy header field in a frequency axis direction, and - the non-legacy header field and N-1 duplicates of said non-legacy header field in a frequency axis direction; and - the legacy STF and N-1 duplicates of said legacy STF in a frequency axis direction, - the legacy CEF and N-1 duplicates of said legacy CEF in a frequency axis direction, - the legacy header field and N-1 duplicates of said legacy header field in a frequency axis direction, and - the non-legacy header field and N-1 duplicates of said non-legacy header field in a frequency axis direction; and the second part of the first PPDU includes the non-legacy STF, the non-legacy CEF, and the one or more data fields; and wherein the second PPDU (2002, 2003) includes one or more non-legacy header fields (2011, 2013) including one or more non-legacy headers, and one or more data fields (2012, 2014) including one or more payload data; and a wireless circuit that is configured to transmit the A-PPDU, wherein: - each of the legacy STF, the legacy CEF, the legacy header field, the non-legacy header field of the first PPDU, the N-1 duplicates of said legacy STF, the N-1 duplicates of said legacy CEF, the N-1 duplicates of said legacy header field, and the N-1 duplicates of said non-legacy header field of the first PPDU is transmitted using a predetermined channel bandwidth; - the second part of the first PPDU and the second PPDU (2002, 2003) are transmitted using a variable channel bandwidth that is N times the predetermined bandwidth; and - in a case where the wireless circuit transmits the first PPDU and the second PPDU (2002, 2003) by single carrier, each of the one or more non-legacy header fields (2011, 2013) of the second PPDU (2002, 2003) includes a non-legacy header that has been repeated N times. - each of the legacy STF, the legacy CEF, the legacy header field, the non-legacy header field of the first PPDU, the N-1 duplicates of said legacy STF, the N-1 duplicates of said legacy CEF, the N-1 duplicates of said legacy header field, and the N-1 duplicates of said non-legacy header field of the first PPDU is transmitted using a predetermined channel bandwidth; - the second part of the first PPDU and the second PPDU (2002, 2003) are transmitted using a variable channel bandwidth that is N times the predetermined bandwidth; and - in a case where the wireless circuit transmits the first PPDU and the second PPDU (2002, 2003) by single carrier, each of the one or more non-legacy header fields (2011, 2013) of the second PPDU (2002, 2003) includes a non-legacy header that has been repeated N times.