Efficient transmission apparatus and method based on beam

A beam-based transmission apparatus and a method thereof are provided to increase sector throughput by increasing the number of ATs(Access Terminals) which participate in a multi-user MIMO(Multiple Input Multiple Output) system and optimize the MIMO system by increasing the number of terminals participating in the MIMO system. An AN(Access Node) estimates a spatial channel matrix, which is formed by its Rx antennas and the Tx antennas of ATs within its own coverage, and a channel rank(S100). An AT selection part selects an AT set within the coverage of the AN(S102). A precoding matrix selection part selects one among the combinations of the precoding matrix of the selected AT set and forms a new spatial channel matrix containing the selected precoding matrix(S104). Using the new spatial channel matrix, a performance estimation calculation part obtains an estimated performance value and stores it in a spatial channel matrix storage part. A control part compares the obtained estimated performance value with a previously stored estimated performance value and stores a better one in an optimum AT set storage part(S106). The control part judges whether a new spatial channel matrix has been formed for every precoding matrix combination(S108). If so, the control part judges whether performance estimation has been completed for the spatial channel matrixes of all the AT sets within the coverage of the AN(S110). If so, the control part executes scheduling using the optimum AT set which shows the optimum performance value stored in the optimum AT set storage part(S112).