Minimum Sum-Mean-Square Square-Error Frequency-Domain Pre-Coding Coding for Downlink Multi-User User MIMO System in the Frequency-Selective Frequency Selective Fading Channel
Abstract: This paper proposes a new frequency-domain frequency pre-coding coding algorithm for the downlink multi-user user MIMO system in a frequency-selective frequency selective fading channel, where each user is equipped with multiple antennas. The proposed algorithm is based on the minimum sum-mean mean-square-error (Min-SMSE) SMSE) criterion, which is able to eliminate both the multi-user multi and multi-antenna antenna interferences, resulting in an improved bit error rate (BER) performance. Compared with the traditional optimal Min-SMSE SMSE algorithm, the proposed algorithm can reduce the computational complexity through simplifying the iterative and power allocation processes. Furthermore, the theoretical BER and ergodic sumsum-rate are derived in detail. In addition, we define and analyze the complexity of the pre-coding pre algorithms. s. Simulation results show that the proposed algorithm compares favorably with the optimal Min-SMSE Min SMSE and traditional block diagonalization (BD) algorithms in the sense of the ergodic sum sum-rate rate due to the approximately equal power allocation. The BER performa performance nce of the proposed algorithm is close to that of the optimal one and much better than that of the BD algorithm in both the uncorrelated and correlated channels. Moreover, the computational complexity of the sub-optimal Min-SMSE SMSE algorithm is significantly less than that of its optimal counterpart, especially in the low SNR region.