A QR Decomposition algorithm with Partial Greedy Permutation for Zero-forcing Block Diagonalization

摘要

A new zero-forcing block diagonalization (ZF-BD)scheme that enables both a more simplified ZF-BD and further increasein sum rate of MU-MIMO channels is proposed in this paper. The proposedscheme provides the improvement in BER performance for equivalent SUMIMOchannels. The proposed scheme consists of two components. First,a permuted channel matrix (PCM), which is given by moving the submatrixrelated to a target user to the bottom of a downlink MIMO channel matrix,is newly defined to obtain a precoding matrix for ZF-BD. ExecutingQR decomposition alone for a given PCM provides null space for the targetuser. Second, a partial MSQRD (PMSQRD) algorithm, which adoptsMSQRD only for a target user to provide improvement in bit rate and BERperformance for the user, is proposed. Some numerical simulations are performed,and the results show improvement in sum rate performance of thetotal system. In addition, appropriate bit allocation improves the bit errorrate (BER) performance in each equivalent SU-MIMO channel. A successiveinterference cancellation is applied to achieve further improvement inBER performance of user terminals.