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In this work, we consider an advanced noise reduction differential chaotic shift keying (NR-DCSK) system in which a single antenna source communicates with a single antenna destination under the attack of a single antenna jammer. We devote our efforts to design a novel anti-jamming (AJ) receiver for the considered system. Particularly, we propose a variational mode decomposition-independent component analysis-wavelet packet decomposition-based (VMD-ICA-WPD-based) structure, in which the VMD method is firstly exploited to generate multiple signals from the single received one. Secondly, the ICA method is applied to coarsely separate chaotic and jamming signals. After that, the WPD method is used to finely estimate and mitigate jamming signals that exist on all outputs of the ICA method. Finally, an inverse ICA procedure is carried out, followed by a summation, and the outcome is passed through the conventional correlation-based receiver for recovering the transmitted information. Simulation results show that the proposed receiver provides significant system performance enhancement compared to that given by the conventional correlation-based receiver with WPD, i.e. 8 dB gain at BER =0.03 and Eb/N0 = 20 dB., 5 pages, 5 figures

For cooperative systems, in which an eavesdropper overhears source information through relays' transmission, an optimal relay selection (ORS) scheme has recently been proposed to improve the system secrecy performance. In this letter, we evaluate the secrecy outage probability (SOP) of the ORS scheme with an amplify-and-forward system over independent and non-identically distributed Rayleigh fading. More specifically, we derive a tight approximation on the SOP. Thereafter, by analyzing asymptotic behaviour of the derived approximation, novel insights are revealed. The derivations are confirmed through Monte Carlo simulations.

We consider a cooperative non-orthogonal multiple access system with radio frequency energy harvesting, in which a user with good channel harvests energy from its received signal and serves as a decode-and-forward relay for enhancing the performance of a user with poor channel. We here aim at maximizing the weighted sum rate of the system by optimizing the power allocation coefficient used at the source and the power splitting coefficient used at the user with good channel. By exploiting the specific structure of the considered problem, we propose a low-complexity one-dimensional search algorithm which can provide optimal solution to the problem. As a benchmark comparison, we derive analytic expressions and simple high signal-to-noise ratio (SNR) approximations of the ergodic rates achieved at two users and their weighted sum with fixed values of the power allocation and the power splitting coefficients, from which the scaling of the weighted sum in the high SNR region is revealed. Finally, we provided numerical results to demonstrate the validity of the optimized scheme. Index Terms-Cooperative NOMA, RF-energy harvesting, weighted sum rate analysis and optimization., Comment: 5 pages, 3 figures

We consider the inefficiencies of conventional multimedia broadcast multicast systems (CVM) limited by the user with worst signal-to-noise-ratio (SNR) and we present a novel technique based on amortized weighted averaging (AWG) of users' SNR. We model the system using ordered statistics of exponential and uniform distribution and derive statistics for the density functions. We then apply the modelling results to study the performance of wireless multicasting over Rayleigh fading channels. More specifically, we obtain the outage probability and mean capacities for broadcast and multicast systems. Finally we compare our proposed scheme with the conventional scheme. Numerical results show that proposed AWG is reliable, avoids outage, accommodates more users and is more efficient than the conventional multicasting especially in the low SNR region.

The relay selection method is a promising technique for improving the performance of cooperative systems. Most of the existing studies assume that wireless channels are statistically independent. However, in reality, channel correlation is more likely to be non-negligible. In this study, we investigate the dependence of the performance of cooperative systems with single relay selection in equally correlated environments. A tight upper bound of the system outage probability is given as a function of the channel correlation coefficients. We show that even though the system performance is considerably degraded in the high signal-to-noise ratio (SNR) region when the channel correlations are sufficiently large, yet less than one, the system still achieves a diversity order equal to the number of available relays.

In this paper, we consider an overlay cognitive radio network, in which a secondary transmitter (ST) is willing to relay the information of a primary transmitter toward a primary receiver. In return, ST can access the licensed band to send its own information superimposed with the primary signal to a secondary receiver. The power-limited ST uses a power splitting protocol to harvest energy from its received signal to increase its transmit power. We analyze the performance of the primary and the secondary systems under independent Nakagami- ${m}$ fading by deriving their corresponding outage probabilities in integral-based expressions. In addition, by considering the high signal-to-noise ratio, we obtain very tight closed-form approximations of the outage probabilities. Thereafter, by further analyzing the approximations, we reveal novel insights on the diversity orders and coding gains of the two systems. Our analytical results are validated through extensive Monte-Carlo simulations.

In this paper, we consider amplify-and-forward (AnF) cooperative systems under correlated fading environments. We first present a brief overview of existing works on the effect of channel correlations on the system performance. We then focus on our main contribution which is analyzing the outage probability of a multi-AnF-relay system with the best relay selection (BRS) scheme under a condition that two channels of each relay, source-relay and relay-destination channels, are correlated. Using lower and upper bounds on the end-to-end received signal-to-noise ratio (SNR) at the destination, we derive corresponding upper and lower bounds on the system outage probability. We prove that the system can achieve a diversity order (DO) equal to the number of relays. In addition, and importantly, we show that the considered correlation form has a constructive effect on the system performance. In other words, the larger the correlation coefficient, the better system performance. Our analytic results are corroborated by extensive Monte-Carlo simulations.

This paper investigates single relay selection problem for secure communication in a cooperative system with multiple full-duplex decode-and-forward relays, in which an eavesdropper may overhear the source confidential message through relays' transmission. We propose an opportunistic relay selection scheme which selects the relay that maximizes the system secrecy capacity. We then evaluate performance of the proposed scheme in terms of secrecy outage probability. As a comparison, we also derive the secrecy outage probability of the conventional Max-Min relay selection scheme proposed for full-duplex relaying systems without the existence of eavesdroppers. We show that our proposed scheme outperforms the conventional counterpart. Our analytic derivations are also extensively verified by Monte-Carlo simulations.

In this work, we consider the relay selection (RS) method for an Amplify-and-Forward (AnF) relaying system in multi-cell environments. The selection scheme aims to maximize the instantaneous received signal-to-noise and interference ratio (SINR). We propose an idea of combining RS with interference cancellation (IC) at the receiver. Furthermore, we analyze the system outage probability performance with the proposed scheme. We use approximation approach to simplify the derivation of the probability distributed function (PDF) of the received SINR. The system outage probability bound is also given. Simulation results validate our analysis, and show that our scheme greatly improves the system outage probability as well as bit-error-rate (BER) performances.

In this paper, the behavior of relay networks in interference environments is investigated. It has been shown that the effect of interference during Amplify-and-Forward process at relays bounds the diversity slope of the system at a well-defined static point. Moreover, the conventional relay selection criteria are also shown to be inefficient. To help our systems to improve its performance, the power allocation issue is taken into account with relay selection. However, solving a jointly optimization problem, optimizing transmitted power and maximizing the received SNR corresponding with the potential relay simultaneously, are difficult. In other words, it requires high complexity manipulation procedures. By proposing a power allocation and a relay selection separately, then combining these two methods, we form a new relay selection with power allocation-based mechanism that is less complex and has comparable performance with the optimal process.

Loop-interference (LI) from relay transmission to reception reduces the channel capacity and makes the relay system unstable in full-duplex (FD) multi-input multi-output (MIMO) relay systems. conventional schemes to suppress LI still have drawbacks: 1) incur a dispensable signal-to-noise ratio (SNR) loss in low SNR regions; 2) increase the system complexity due to the requirement of weighting matrices; and 3) make insufficient practical sense due to varying signal-to-interference ratios (SIRs). In this paper, we propose a new LI suppression scheme using transmit antenna selection in order to solve the above problems. Simulation results show that the proposed scheme outperforms a conventional scheme, especially in low SNR and high SIR regions, even though the proposed scheme has a lower complexity.