A performance-complexity tradeoff for vector perturbation precoding

We investigate he performance-complexity tradeoff for vector perturbation (VP) precoding in he downlink of multiuser multiple input multiple output (MU-MIMO) systems. To his end, we introduce a VP design ha applies a performance-determined threshold o he desired norm of he preceded signal, o reduce he search through multiple candidate perturbation vectors by he sphere encoder. Once his threshold is me, the search for the perturbation vectors finishes thus saving significant computational burden at the transmitter. Contrary o conventional VP which performs a compuationally intense sphere search to find the absolute minimum of the transmit signal norm, he proposed scheme can trade off error rate performance for a much reduced complexity of precoding. The presented analysis and results show ha he proposed thresholded VP (TVP) offers a complexity reduction of up o 90% in a 4 × 4 and 99% in a 10 × 10 MIMO, for a moderately increased error rate.