Abstract
We propose an energy-efficient vector perturbation (VP) technique for the downlink of multiuser multiple-input-single-output (MU-MISO) systems. In contrast to conventional VP where the search for perturbation vectors involves all users' symbols, here, the perturbation is applied to a subset of the transmitted symbols. This, therefore, introduces a performance-complexity tradeoff, where the complexity is greatly reduced compared to VP by limiting the dimensions of the sphere search, at the expense of a performance penalty compared to VP. By changing the size of the subset of perturbed users, the aforementioned tradeoff can be controlled to maximize energy efficiency. We further propose three distinct criteria for selecting which users' symbols to perturb, each of which yields a different performance-complexity tradeoff. The presented analytical and simulation results show that partially perturbing the data provides a favorable tradeoff, particularly at low-power transmission where the power consumption associated with the signal processing becomes dominant. In fact, it is shown that diversity close to the one for conventional VP can be achieved at energy efficiency levels improved by up to 300% compared to VP.
Highlights
T HE need to produce power- and cost-efficient mobile devises has recently stimulated interest towards precoding schemes for the multiple input multiple output (MIMO) downlink transmission
For reasons of clarity we list the contributions of the present work: 1) We introduce a new selective vector perturbation (VP) scheme that reduces the complexity with respect to conventional VP schemes, 2) To optimize the performance-complexity tradeoff, we further propose three distinct criteria for the selection of the transmit symbols to perturb, 3) We calculate and compare analytically the complexity of conventional and proposed techniques, and prove the complexity benefits of the proposed approach mathematically, based on the volume of the search space associated with each of the techniques, 4) We quantify the performance-complexity tradeoff of conventional and proposed VP, by introducing a energy efficiency metric that combines sum rate, transmit power and complexity and prove the enhanced tradeoff for the proposed scheme
We focus on the performance and complexity comparisons and tradeoff between VP and SELECTIVE VECTOR PRECODING (SVP)
Summary
T HE need to produce power- and cost-efficient mobile devises has recently stimulated interest towards precoding schemes for the multiple input multiple output (MIMO) downlink transmission. For reasons of clarity we list the contributions of the present work: 1) We introduce a new selective VP scheme that reduces the complexity with respect to conventional VP schemes, 2) To optimize the performance-complexity tradeoff, we further propose three distinct criteria for the selection of the transmit symbols to perturb, 3) We calculate and compare analytically the complexity of conventional and proposed techniques, and prove the complexity benefits of the proposed approach mathematically, based on the volume of the search space associated with each of the techniques, 4) We quantify the performance-complexity tradeoff of conventional and proposed VP, by introducing a energy efficiency metric that combines sum rate, transmit power and complexity and prove the enhanced tradeoff for the proposed scheme We demonstrate that this metric can be used to design an energy efficient communication link by optimizing the number of perturbed users required in the proposed VP.
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