Communication apparatus and communication system

A communication method, comprising:

• generating, in a first communication apparatus, a first reference signal to enable a second communication apparatus to estimate a propagation environment;
• transmitting the first reference signal from the first communication apparatus to the second communication apparatus;
• storing, in the first communication apparatus, a known signal known between the first communication apparatus and the second communication apparatus;
• obtaining, in the first communication apparatus, correlation between the known signal and a second reference signal transmitted from the second communication apparatus, and generating, in the first communication apparatus, a delay profile as an estimation value of the propagation environment;
• reading out, in the first communication apparatus, first data associated with the generated delay profile, from a reference table that associates the delay profile with the first data;
• and
• decoding, in the first communication apparatus, a transmission signal encoded and transmitted using an estimation value of the propagation environment estimated by the second communication apparatus using the first reference signal, to second data using the first data read out.