A Per-User Successive MMSE Precoding Technique in Multiuser MIMO Systems

We propose a per-user successive minimum mean-squared error (PU-SMMSE) precoding technique suitable for the use in multiuser multiple-input multiple-output (MU-MIMO) downlink systems. Its preceding complexity is much simpler as compared with that of the successive MMSE (SMMSE) technique (V. Stankovic and M. Haardt, 2004), without any performance loss. The new technique also takes both the high capacity benefit achievable with MIMO multiplexing and the benefit of space division multiple access (SDMA), assuming channel state information (CSI) at both the transmitter and receiver sides. In the new technique, the columns of the precoding matrix are obtained by computing successively reduced-rank MMSE precoding solutions on a per-user basis. Then, a per-user virtual channel which consists of the per-user channel through precoding is decomposed into orthogonal transmission modes. Finally, a proper power assignment can be applied to the decomposed modes according to some assignment policy. We compare the proposed technique with the SMMSE technique in terms of the bit error rate (BER) performance. We also analyze the computational complexity of the PU-SMMSE technique in comparison with the SMMSE and BD techniques. From computer simulations and complexity analyses, we see that the PU-SMMSE and SMMSE techniques have the same BER performance in both cases of dominant mode transmission (DMT) and multiple mode transmission (MMT). However, the computational complexity of the proposed technique is much lower than that of the SMMSE technique, and also is lower than that of the simple block diagonalization (BD) technique.

[1]  Martin Haardt,et al.  Successive optimization Tomlinson-Harashima precoding (SO THP) for multi-user MIMO systems , 2005, Proceedings. (ICASSP '05). IEEE International Conference on Acoustics, Speech, and Signal Processing, 2005..

[2]  Martin Haardt,et al.  Linear MMSE Multi-User MIMO Downlink Precoding for Users with Multiple Antennas , 2006, 2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications.

[3]  Andrea J. Goldsmith,et al.  On the capacity of multiple input multiple output broadcast channels , 2002, 2002 IEEE International Conference on Communications. Conference Proceedings. ICC 2002 (Cat. No.02CH37333).

[4]  Josef A. Nossek,et al.  Transmit Wiener filter for the downlink of TDDDS-CDMA systems , 2002, IEEE Seventh International Symposium on Spread Spectrum Techniques and Applications,.

[5]  Tony F. Chan,et al.  An Improved Algorithm for Computing the Singular Value Decomposition , 1982, TOMS.

[6]  Tung-Sang Ng,et al.  Multi-user MIMO antenna systems using semi-orthogonal space division multiplexing and single-user QR-triangular detection , 2003, 2003 IEEE International Conference on Acoustics, Speech, and Signal Processing, 2003. Proceedings. (ICASSP '03)..

[7]  Martin Haardt,et al.  Zero-forcing methods for downlink spatial multiplexing in multiuser MIMO channels , 2004, IEEE Transactions on Signal Processing.

[8]  M. Haardt,et al.  Efficient multi-user MIMO downlink precoding and scheduling , 2005, 1st IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing, 2005..

[9]  A.J. Paulraj,et al.  Multiuser diversity for MIMO wireless systems with linear receivers , 2001, Conference Record of Thirty-Fifth Asilomar Conference on Signals, Systems and Computers (Cat.No.01CH37256).

[10]  Kai-Kit Wong.  Adaptive space-division-multiplexing and bit-and-power allocation in multiuser MIMO flat fading broadcast channels , 2003, 2003 IEEE 58th Vehicular Technology Conference. VTC 2003-Fall (IEEE Cat. No.03CH37484).

[11]  Martin Haardt,et al.  An introduction to the multi-user MIMO downlink , 2004, IEEE Communications Magazine.