Exploiting Constructive Interference for Simultaneous Wireless Information and Power Transfer in Multiuser Downlink Systems

IEEE Trans. Wireless Commun.

Wong

et al. 2020

Self Cite

In this paper, we propose a series of novel coordination schemes for multi-cell downlink communication. Starting from full base station (BS) coordination, we first propose a fully-coordinated scheme to exploit beneficial effects of both inter-cell and intra-cell interference, based on sharing both channel state information (CSI) and data among the BSs. To reduce the coordination overhead, we then propose a partially-coordinated scheme where only intra-cell interference is designed to be constructive while inter-cell is jointly suppressed by the coordinated BSs. Accordingly, the coordination only involves CSI exchange and the need for sharing data is eliminated. To further reduce the coordination overhead, a third scheme is proposed, which only requires the knowledge of statistical inter-cell channels, at the cost of a slight increase on the transmission power. For all the proposed schemes, imperfect CSI is considered.We minimize the total transmission power in terms of probabilistic and deterministic optimizations.Explicitly, the former statistically satisfies the users' signal-to-interference-plus-noise ratio (SINR) while the latter guarantees the SINR requirements in the worst case CSI uncertainties. Simulation verifies that our schemes consume much lower power compared to the existing benchmarks, i.e., coordinated multipoint (CoMP) and coordinated-beamforming (CBF) systems, opening a new dimension on multi-cell coordination.

Section: B Constructive Interferencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multi-Cell Interference Exploitation: Enhancing the Power Efficiency in Cell Coordination

Wei

IEEE Trans. Wireless Commun.

Wong

et al. 2020

Self Cite

“…In contrast to the conventional techniques where the knowledge of the interference is used to cancel it, the main idea of the CI is to use the interference to improve the system performance. Specifically, the CI precoding technique exploits interference that can be known to the transmitter to increase the useful signal received power [13]- [16]. That is, with the knowledge of the users' data symbols and CSI, the interference can be classified as constructive and destructive.…”

Section: Introductionmentioning

confidence: 99%

Sum Rate and Fairness Analysis for the MU-MIMO Downlink Under PSK Signalling: Interference Suppression vs Exploitation

Salem

Wong

2019

IEEE Trans. Commun.

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In this paper, we analyze the sum rate performance of multi-user multiple-input multiple-output (MU-MIMO) systems, with a finite constellation phase-shift keying (PSK) input alphabet. We analytically calculate and compare the achievable sum rate in three downlink transmission scenarios: 1) without precoding, 2) with zero forcing (ZF) precoding 3) with closed form constructive interference (CI) precoding technique. In light of this, new analytical expressions for the average sum rate are derived in the three cases, and Monte Carlo simulations are provided throughout to validate the analysis. Furthermore, based on the derived expressions, a power allocation scheme that can ensure fairness among the users is also proposed. The results in this work demonstrate that, the CI strictly outperforms the other two schemes, and the performance gap between the considered schemes increases with increase in the MIMO size. In addition, the CI provides higher fairness and the power allocation algorithm proposed in this paper can achieve maximum fairness index.Index Terms-Finite constellation signaling, zero forcing, constructive interference, phase-shift keying signaling, multiple-input multiple-output.

“…Further studies on the optimization-based CI beamforming schemes can be found in [20]- [23]. Due to the performance benefits over conventional schemes, the concept of CI has been extended to many wireless application scenarios, including cognitive radio [24], [25], constant envelope precoding [26], wireless information and power transfer [27] and mutual coupling exploitation [28]. The above studies show that MIMO systems can benefit from the CI with a symbollevel beamforming.…”

mentioning

confidence: 99%

Interference Exploitation Precoding Made Practical: Optimal Closed-Form Solutions for PSK Modulations

IEEE Trans. Wireless Commun.

2018

Self Cite

114

179

In this paper, we propose closed-form precoding schemes with optimal performance for constructive interference (CI) exploitation in the multiuser multiple-input single-output (MU-MISO) downlink. We first consider an optimization where we maximize the distance between the constructive region and the detection thresholds. The cases of both strict and non-strict phase rotation are considered and can further be formulated as convex optimization problems. For optimization with strict phase rotation, we mathematically derive the optimal beamforming structure with Lagrangian and Karush-Kuhn-Tucker (KKT) conditions. By formulating its dual problem, the optimization problem is further shown to be equivalent to a quadratic programming (QP) over a simplex, which can be solved more efficiently. We then extend our analysis to the case of non-strict phase rotation, where it is mathematically shown that a Kdimensional optimization for non-strict phase rotation is equivalent to a 2K-dimensional optimization for strict phase rotation in terms of the problem formulation. The connection with the conventional zero-forcing (ZF) precoding is also discussed. Based on the above analysis, we further propose an iterative closedform scheme to obtain the optimal beamforming matrix, where within each iteration a closed-form solution can be obtained. Numerical results validate our analysis and the optimality of the proposed iterative scheme, and further show that the proposed closed-form scheme is more efficient than the conventional QP algorithms with interior-point methods, which motivates the use of CI beamforming in practical wireless systems.