The invention discloses a multi-user cognitive 
MIMO (Multiple-Input Multiple-Output) 
system concurrent transmission and user scheduling method based on IAC (interactive application communication). The method comprises the following steps that: (1) an authorized user and an authorized 
base station obtain channel information H0, cognitive users obtain channel information H0, Hi and H<s>i, and a 
cognitive base station obtains all channel information; (2) the authorized user, the authorized 
base station, the cognitive users and the 
cognitive base station respectively implement 
singular value decomposition on the H0; (3) all the cognitive users respectively calculate an intermediate 
matrix norm value, and the 
cognitive user with the maximum value is selected to be scheduled; (4) the 
cognitive base station gives notice to the scheduled 
cognitive user SUxi, and the authorized user and the 
cognitive user SUxi respectively construct a 
precoding matrix P0 and a 
precoding vector pxi; (5) data of the authorized user and the activated cognitive user are respectively pre-treated by P0 and pxi and then are sent to a 
base station; (6) the authorized base 
station solves a primary 
data stream x01 of the authorized user and sends the primary 
data stream x01 to the cognitive base 
station; (7) filter 
waves are received by utilizing F<H>, x01 is removed from a received mixed 
signal, a secondary 
data stream x02 of the authorized user and a data 
stream x(xi) of the cognitive user are respectively solved, and x02 is sent to the authorized base 
station.