Complexity reduction for higher order MIMO decoder using block diagonalization

In this paper, we propose a complexity reduction technique for the high order multiple input multiple output (MIMO) system by using the block diagonalization (BD) technique in the MIMO receiver. In wireless communication, the BD technique is well known for canceling the inter user interference (IUI) as a precoding method in a multi-user (MU) MIMO access point (AP). The proposed technique employs the BD technique for single-user (SU) MIMO receiver's MIMO decoding to reduce the complexity of high order MIMO decoder. By using the BD technique, the proposed high order MIMO receiver can decompose perfectly channel state information (CSI) matrix into sub-matrices of MIMO channel matrix. Therefore the proposed MIMO receiver does not require higher order MIMO decoder. This means that the hardware circuit area of the proposed MIMO decoder becomes smaller than the conventional one. This paper shows the proposed high order MIMO decode technique achieves higher accuracy than the conventional MIMO decoder methods such as Linear minimum mean square error (MMSE), and lattice reduction aided-MMSE (LRA-MMSE).