Channel information acquisition method and device and codebook construction method

The invention discloses a channel information acquisition method and a device and a codebook construction method, which solve the technical defect that in the existing technology, a terminal can not flexibly send channel information according to the specific needs. The acquisition method comprises the following steps that: the terminal sends information R1 information PMI1 and information PMI2 of the current channel to a base station, wherein information R1 indicates rank (upsilon) of the current channel, and upsilon is a positive integer being less than or equal to 8; the base station finds a matrix W1 being 8*upsilon according to the information R1 and the information PMI1, and finds a corresponding matrix W2 according to information PMI2 or the information R1 and the information PMI2; and the base station adjusts the phase of each element in the matrix W1 according to the function F (W1, W2) to acquire an adjustable matrix which is used to be as channel information of a sonband. Compared with the prior art, the channel information feedback technology provided by the technical scheme of the invention can solve the feedback problem when in each Rank.