Improved signal estimation based on combined forward and backward lattice reduction in MIMO systems

Lattice reduction aided (LRA) detection with the LLL algorithm has been investigated to achieve the MIMO channel capacity with low computational complexity. This paper proposes an improved LRA-MMSE detection using the forward and the backward reduction LLL algorithms for the 8times8 MIMO to obtain more reliable estimates of the transmitted signals. The proposed method achieved much better BERs than the conventional LRA detection. The transmit signal energy could be saved about 3.5 dB at BER=10^-5, and the BER slope became much steeper, which is almost the same as that with the maximum likelihood detection.