The present disclosure provides communication apparatus and communication method for channel estimation. The communication apparatus comprises a transmitter, which in operation, transmits a physical layer protocol data unit (PPDU) to one or more other communication apparatus in a multiple-input multiple-output (MIMO) wireless network, the PPDU including a long training field (LTF) that facilitates the one or more other communication apparatus to estimate respective channels for respective communications with the communication apparatus; and a controller, which in operation, establishes the number of LTF symbols (NLTF) for generating the LTF in the PPDU, wherein the NLTF depends on a maximum value (NSTSMAX) of the number of space-time streams for each resource unit (RU) in the PPDU.