On the Superiority of Improper Gaussian Signaling in Wireless Interference MIMO Scenarios

Lagén, Sandra; Agustín, Adrián; Vidal, Josep

doi:10.1109/tcomm.2016.2584601

Cited by 46 publications

(53 citation statements)

References 39 publications

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“…Similar DoF results were derived for the four-user interference channel in [14]. After that, a number of new works has emerged, and the payoffs of improper signaling have been revealed for different multiuser scenarios such as the interference channel [3][4][5]15], Z-interference channel [6,[16][17][18], broadcast channels with linear precoding [19,20], underlay and overlay cognitive radio networks [7,8,21] and relay channels [22,23]. More recently, in [24], the authors showed the advantages of improper signaling in a multiuser scenario where a point-to-point link coexists with a multiple access channel.…”

Section: Introductionsupporting

confidence: 57%

Information-Theoretic Analysis of a Family of Improper Discrete Constellations

Santamarı́a

Crespo

Lameiro

et al. 2018

Entropy

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Non-circular or improper Gaussian signaling has proven beneficial in several interference-limited wireless networks. However, all implementable coding schemes are based on finite discrete constellations rather than Gaussian signals. In this paper, we propose a new family of improper constellations generated by widely linear processing of a square M-QAM (quadrature amplitude modulation) signal. This family of discrete constellations is parameterized by κ, the circularity coefficient and a phase φ. For uncoded communication systems, this phase should be optimized as φ * (κ) to maximize the minimum Euclidean distance between points of the improper constellation, therefore minimizing the bit error rate (BER). For the more relevant case of coded communications, where the coded symbols are constrained to be in this family of improper constellations using φ * (κ), it is shown theoretically and further corroborated by simulations that, except for a shaping loss of 1.53 dB encountered at a high signal-to-noise ratio (snr), there is no rate loss with respect to the improper Gaussian capacity. In this sense, the proposed family of constellations can be viewed as the improper counterpart of the standard proper M-QAM constellations widely used in coded communication systems.

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Section: Introductionsupporting

confidence: 57%

Information-Theoretic Analysis of a Family of Improper Discrete Constellations

Santamarı́a

Crespo

Lameiro

et al. 2018

Entropy

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“…Finally, it should be pointed out that the channel model we consider here (the standard pointto-point Gaussian MIMO channel under interference constraints at the transmitter) is different from the Gaussian interference channel (G-IC) where multi-user interference is present at each receiver and there is no interference constraint at the transmitters, as in e.g. [21]- [29]. In the latter case, the capacity and optimal signaling are not known in general, even for the 2-user SISO channel [21] (it is not even known whether Gaussian signaling is optimal in general), except for some special cases, such as strong and weak interference regimes [22] [23], so that various bounds [24][25] and ad-hoc signaling techniques [26]- [29] are used instead.…”

mentioning

confidence: 99%

“…[21]- [29]. In the latter case, the capacity and optimal signaling are not known in general, even for the 2-user SISO channel [21] (it is not even known whether Gaussian signaling is optimal in general), except for some special cases, such as strong and weak interference regimes [22] [23], so that various bounds [24][25] and ad-hoc signaling techniques [26]- [29] are used instead. On the contrary, optimal signaling is known to be Guassian for the channel model considered here and the capacity can be expressed as an optimization problem over all feasible transmit covariance matrices.…”

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confidence: 99%

The Capacity and Optimal Signaling for Gaussian MIMO Channels Under Interference Constraints

Loyka

2020

IEEE Trans. Commun.

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Gaussian MIMO channel under total transmit and interference power constraints (TPC and IPC) is considered. A closed-form solution for the optimal transmit covariance matrix in the general case is obtained using the KKT-based approach (up to dual variables). While closed-from solutions for optimal dual variables are possible in special cases, an iterative bisection algorithm (IBA) is proposed to find the optimal dual variables in the general case and its convergence is proved for some special cases.Numerical experiments illustrate its efficient performance. Bounds for the optimal dual variables are given, which facilitate numerical solutions. An interplay between the TPC and IPC is studied, including the transition from power-limited to interference-limited regimes as the total transmit power increases.Sufficient and necessary conditions for each constraint to be redundant are given. A number of explicit closed-form solutions are obtained, including full-rank and rank-1 (beamforming) cases as well as the case of identical eigenvectors (typical for massive MIMO settings). A bound on the rank of optimal covariance is established. A number of unusual properties of optimal covariance matrix are pointed out.

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“…In the second type, we derive the whole rate region for a specific channel realization. It is worth mentioning that both types of numerical examples are common for rate region analysis (please refer to [6], [9], [11]).…”

Section: Numerical Resultsmentioning

confidence: 99%

Robust Improper Signaling for Two-User SISO Interference Channels

Soleymani

Lameiro

Santamarı́a

et al. 2019

IEEE Trans. Commun.

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It has been shown that improper Gaussian signaling (IGS) can improve the performance of wireless interferencelimited systems when perfect channel state information (CSI) is available. In this paper, we investigate the robustness of IGS against imperfect CSI on the transmitter side in a two-user singleinput single-output (SISO) interference channel (IC) as well as in a SISO Z-IC, when interference is treated as noise. We assume that the true channel coefficients belong to a known region around the channel estimates, which we call the uncertainty region. Following a worst-case robustness approach, we study the rate-region boundary of the IC for the worst channel in the uncertainty region. For the two-user IC, we derive a robust design in closed-form, which is independent of the phase of the channels by allowing only one of the users to transmit IGS. For the Z-IC, we provide a closed-form design for the transmission parameters by considering an enlarged uncertainty region and allowing both users to employ IGS. In both cases, the IGS-based designs are ensured to perform no worse than proper Gaussian signaling. Furthermore, we show, through numerical examples, that the proposed robust designs significantly outperform nonrobust solutions.

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On the Superiority of Improper Gaussian Signaling in Wireless Interference MIMO Scenarios

Cited by 46 publications

References 39 publications

Information-Theoretic Analysis of a Family of Improper Discrete Constellations

Information-Theoretic Analysis of a Family of Improper Discrete Constellations

The Capacity and Optimal Signaling for Gaussian MIMO Channels Under Interference Constraints

Robust Improper Signaling for Two-User SISO Interference Channels

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