A transmission apparatus comprising: a generation circuit that generates a transmission signal in which a plurality of protocol data units in a physical layer are aggregated; an insertion circuit that inserts a preamble into each of a first protocol data unit and a second protocol data unit among the plurality of protocol data units; and a transmission circuit that performs spatial processing on the transmission signal with the preamble inserted and transmits the transmission signal, characterized in that the transmission apparatus further comprises: an MCS change detection circuit that detects a change in modulation and coding scheme, MCS, between two consecutive protocol data units on a basis of the code rates and the data modulation schemes of the plurality of protocol data units; wherein the spatial processing uses a precoding matrix and the precoding matrix is changed in accordance with the MCS; wherein the insertion circuit determines whether to insert the preamble into the latter of the two consecutive protocol data units on a basis of the detected change, the preamble being used for at least one of synchronization of a transmission channel and estimation of the transmission channel; wherein if the number of MIMO (Multiple-Input and Multiple-Output) streams to be used is greater than 1 and if the change is detected, the insertion circuit inserts the preamble into the latter; if the number of MIMO streams to be used is greater than 1 and if the change is not detected, the insertion circuit does not insert the preamble into the latter; and if the number of MIMO streams to be used is 1, the insertion circuit does not insert the preamble into the latter. a generation circuit that generates a transmission signal in which a plurality of protocol data units in a physical layer are aggregated; an insertion circuit that inserts a preamble into each of a first protocol data unit and a second protocol data unit among the plurality of protocol data units; and a transmission circuit that performs spatial processing on the transmission signal with the preamble inserted and transmits the transmission signal, characterized in that the transmission apparatus further comprises: an MCS change detection circuit that detects a change in modulation and coding scheme, MCS, between two consecutive protocol data units on a basis of the code rates and the data modulation schemes of the plurality of protocol data units; wherein the spatial processing uses a precoding matrix and the precoding matrix is changed in accordance with the MCS; wherein the insertion circuit determines whether to insert the preamble into the latter of the two consecutive protocol data units on a basis of the detected change, the preamble being used for at least one of synchronization of a transmission channel and estimation of the transmission channel; wherein if the number of MIMO (Multiple-Input and Multiple-Output) streams to be used is greater than 1 and if the change is detected, the insertion circuit inserts the preamble into the latter; if the number of MIMO streams to be used is greater than 1 and if the change is not detected, the insertion circuit does not insert the preamble into the latter; and if the number of MIMO streams to be used is 1, the insertion circuit does not insert the preamble into the latter. an MCS change detection circuit that detects a change in modulation and coding scheme, MCS, between two consecutive protocol data units on a basis of the code rates and the data modulation schemes of the plurality of protocol data units; wherein the spatial processing uses a precoding matrix and the precoding matrix is changed in accordance with the MCS; wherein the insertion circuit determines whether to insert the preamble into the latter of the two consecutive protocol data units on a basis of the detected change, the preamble being used for at least one of synchronization of a transmission channel and estimation of the transmission channel; wherein if the number of MIMO (Multiple-Input and Multiple-Output) streams to be used is greater than 1 and if the change is detected, the insertion circuit inserts the preamble into the latter; if the number of MIMO streams to be used is greater than 1 and if the change is not detected, the insertion circuit does not insert the preamble into the latter; and if the number of MIMO streams to be used is 1, the insertion circuit does not insert the preamble into the latter.