WLCp1-13: How to Gain 1.5 dB in Vector Precoding

A vector-precoding technique known as "vector-perturbation" achieves near-capacity on a multi- antenna multi-user wireless channel. However, the technique currently requires choices for certain regularization and perturbation parameters and these parameters are currently chosen in a rather ad-hoc manner. We analyze the statistical properties of the vector- perturbation scheme and provide guidelines for choosing these parameters in a more systematic manner. These properties suggest that a large perturbation-parameter can give better performance at low SNR. We also propose a receiver that incorporates the statistical properties of the perturbation, thereby improving receiver performance over known methods. Finally, we incorporate an iteration loop between the demodulator and inner decoder. The net result of these improvements puts us approximately 1.5 dB closer to capacity.