Benefits of Improper Signaling for Underlay Cognitive Radio

Lameiro, Christian; Santamarı́a, Ignacio; Schreier, Peter J.

doi:10.1109/lwc.2014.2360179

Cited by 55 publications

(124 citation statements)

References 14 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: 55%

“…Since the PU is typically unaware of the SU, it is also assumed that the PU always transmits proper Gaussian signals, whereas the SU may transmit either proper or improper Gaussian signals depending on which signaling scheme performs better. This problem has been analyzed in [7], where it has been proven that the SU improves its rate by transmitting Gaussian improper signals if and only if (cf. Theorem 1 in [7]):…”

Section: A Motivating Examplementioning

confidence: 99%

“…This problem has been analyzed in [7], where it has been proven that the SU improves its rate by transmitting Gaussian improper signals if and only if (cf. Theorem 1 in [7]):…”

Section: A Motivating Examplementioning

confidence: 99%

“…Furthermore, Theorem 1 in [7] also gives us the optimal circularity coefficient κ s that must be used by the SU depending on its power budget. For example, let us suppose that the cross-link channel is a = 4; the power budgets for the PU and SU are 100 and 20, respectively; and the loading factor is ξ = 0.4.…”

Section: A Motivating Examplementioning

confidence: 99%

“…In more complex interference-limited scenarios, such as the interference channel, transmitting proper Gaussian signals is in general suboptimal, so assuming this input distribution in such cases is not theoretically justified. As a matter of fact, recent works have shown that, when treating interference as noise, a higher transmitted rate may be achieved in interference-limited networks by transmitting improper Gaussian signals, which are correlated with their complex conjugate [2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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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: 55%

Section: A Motivating Examplementioning

confidence: 99%

“…This problem has been analyzed in [7], where it has been proven that the SU improves its rate by transmitting Gaussian improper signals if and only if (cf. Theorem 1 in [7]):…”

Section: A Motivating Examplementioning

confidence: 99%

Section: A Motivating Examplementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Information-Theoretic Analysis of a Family of Improper Discrete Constellations

Santamarı́a

Crespo

Lameiro

et al. 2018

Entropy

Self Cite

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Spectrum sharing framework in full duplex mode with minimum interference in 5G cellular network

Rajput,

Malathi

2024

Multimed Tools Appl

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Spectral sharing with in-band full-duplex (FD) primary users (PUs) in cognitive radio (CR) systems is a difficult and challenging task. The ability of the secondary user (SU) to access the spectrum could be substantially impeded by the primary network's self-interference. We propose a novel dynamic spectrum sharing (DSS) scheme while satisfying In-band FD technology is the mitigation of strong self-interference in the 5G cellular networks platform. In particular, the in-band FD-PU pair implements the normal proper Gaussian signal, although it is intended for SU downlink transmission with an inappropriate Gaussian signal. First, we derive the closed-form expression and the upper bounds of the default probabilities for SU and PU, respectively. While discussing major concerns in the 5G cellular networks system, the second stage optimization is carried out utilizing the optimal spectrum sharing approach, and a self-interference game methodology based on the proportional enthalpy based sigmoid solution is applied. This method is primarily employed to reduce computational complexity and overheads. In terms of SINR, Spectral efficiency, and other metrics, the computational studies shows that the provided method outperforms existing methods.

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Performance Analysis and Fairness Maximization in NOMA Systems With Improper Gaussian Signaling Under Imperfect Successive Interference Cancellation

Hong

Bahk

2020

IEEE Access

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In this paper, we investigate a downlink non-orthogonal multiple access (NOMA) system consisting of a base station (BS) and two users, where each user decodes its own signal through successive interference cancellation (SIC). When the signal of one user, called the weak user (WU) who has a bad channel, is being decoded, the signal of the other user, called the strong user (SU) who has a good channel, acts as interference. In an interference channel, we can increase the achievable rate by applying improper Gaussian signaling (IGS). Therefore, we apply IGS to SU, aiming to mitigate the interference. We also consider imperfect SIC at SU, which is a more general assumption for a NOMA system. For the considered NOMA system model, we derive the outage probability of each user in a closed form, provide its asymptotic expression, and obtain its diversity order. We also derive the ergodic rate of each of the two users in a closed form. We propose two algorithms to maximize the fairness of the NOMA system based on the primal decomposition method. Through simulation, we verify that our analysis is correct, and confirm that applying IGS improves the fairness of the NOMA system. INDEX TERMS Ergodic rate, fairness, imperfect successive interference cancellation (SIC), improper Gaussian signaling (IGS), non-orthogonal multiple access (NOMA) system, outage probability, primal decomposition.

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Benefits of Improper Signaling for Underlay Cognitive Radio

Cited by 55 publications

References 14 publications

Information-Theoretic Analysis of a Family of Improper Discrete Constellations

Information-Theoretic Analysis of a Family of Improper Discrete Constellations

Spectrum sharing framework in full duplex mode with minimum interference in 5G cellular network

Performance Analysis and Fairness Maximization in NOMA Systems With Improper Gaussian Signaling Under Imperfect Successive Interference Cancellation

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