Vector Perturbation Channel Inversion for SWIPT MU-MISO Systems

TL;DR

This paper explores vector perturbation precoding in MU-MISO systems to enhance simultaneous information transfer and energy harvesting, proposing a modified technique that optimizes power delivery while maintaining data capacity.

Contribution

It introduces a novel VP-EH scheme that maximizes energy harvesting by optimizing integer offsets, and proposes a trade-off method between information and energy transfer.

Findings

VP improves energy harvesting due to extended constellation.

VP-EH maximizes power delivery through lattice point optimization.

A convex combination balances information capacity and energy harvesting.

Abstract

This letter investigates the employment of vector-perturbation (VP) precoding to convey simultaneously information and energy in multiple-user multiple-input single-output (MU-MISO) downlink channel. We show that the conventional VP in addition to the information capacity benefits that provides to linear channel inversion techniques, it enhances the harvested energy at the receivers due to the extended symbol constellation. To further boost harvesting performance, the proposed modified VP technique (named VP-EH) designs the VP integer offsets in order to maximize the delivered power. The proposed scheme incorporates an integer least square problem to find the closest lattice point to a point which is given by a Rayleigh quotient optimization problem. Finally, a convex combination between conventional VP and VP-EH is proposed to achieve a trade-off between maximizing information or energy. Theoretical and simulations results validate that VP is a promising technique to simultaneously convey information and energy in MU-MISO systems.