Secure half-duplex dual-hop AF relaying networks with partial relay selection

In this study, secrecy outage performance is studied for partial relay selection (PRS) schemes in cooperative systems over Rayleigh fading channels. In the considered systems, there are one source (S), one destination (D), one eavesdropper, one jammer that can send interference to the eavesdropper, and N ( N > 1) relay candidates, one of which is selected as the relay (R). By considering the practical scenarios and to protect the transmitted information over R–D link from being eavesdropped, the authors propose a new transmission scheme: let D send random information to R while S sending information to R. Then, R processes the messages from S and D by XOR operation in order to prevent the eavesdropper's interception while the information is delivered between R and D. They study the secrecy outage performance for two PRS schemes: (i) the optimal source–relay link (OSRL) scheme; and (ii) the optimal source–relay–destination link (OSRDL) scheme. The closed‐form expressions for the secrecy outage probability (SOP) of the two PRS schemes are derived, as well as the closed‐form upper bound for SOP under OSRL scheme and the lower bound for SOP under OSRDL scheme. Finally, simulation results are given to verify the presented analytical models and the proposed transmission scheme.

This paper investigates the performance of amplify-and-forward (AF) cognitive relay networks with partial relay selection (PRS) in a spectrum-sharing context. The PRS schemes can be divided into two different types: source-relay PRS and relay-destination PRS, which are respectively called SR-PRS and RD-PRS for short. Different from most of the existing studies which only consider interference power constraint on secondary source and relay nodes, transmit power constraint on secondary relay nodes is further considered in our work. In this condition, we derive the lower bound on symbol error rate and the upper bound on ergodic capacity of the two schemes aforementioned over Rayleigh fading channels, which has never been studied before. According to the analyses, the power constraints and the number of secondary relay nodes are the main factors affecting the system performance. Furthermore, the performances of the two schemes are compared by simulations and the correctness of the analytical results are verified by Monte Carlo simulations.

This paper investigates the impacts of hardware impairments (HIs) and partial relay selection (PRS) scheme on non-orthogonal multiple access (NOMA)-based integrated satellite-terrestrial multi-relay networks (ISTMRNs). NOMA technology can bring us significant spectral efficiency, high frequency utilization ratio and reliability for it can transmit signal to multiple destinations simultaneously. Besides, we utilize PRS scheme to obtain better system performance. Specifically, we derive the closed-form expression of the outage probability (OP) for the considered system in the presence of HIs and PRS scheme. To gain further insights at high signal-to-noise ratios (SNRs), the asymptotic expression for the OP is also derived. Numerical Monte Carlo (MC) results are provided to verify the correctness

This paper investigates the impact of relay selection (RS) on the performance of cooperative non-orthogonal multiple access (NOMA), where relays are capable of working in either full-duplex (FD) or half-duplex (HD) mode. A number of relays (i.e., K relays) are uniformly distributed within the disc. A pair of RS schemes are considered insightfully: 1) single-stage RS (SRS) scheme; and 2) two-stage RS (TRS) scheme. In order to characterize the performance of these two RS schemes, new closed-form expressions for both exact and asymptotic outage probabilities are derived. Based on analytical results, the diversity orders achieved by the pair of RS schemes for FD/HD cooperative NOMA are obtained. Our analytical results reveal that: 1) the FD-based RS schemes obtain a zero diversity order, which is due to the influence of loop interference at the relay; and 2) the HD-based RS schemes are capable of achieving a diversity order of K , which is equal to the number of relays. Finally, simulation results demonstrate that: 1) the FD-based RS schemes have better outage performance than HD-based RS schemes in the low signal-to-noise ratio (SNR) region; 2) as the number of relays increases, the pair of RS schemes considered are capable of achieving the lower outage probability; and 3) the outage behaviors of FD/HD-based NOMA SRS/TRS schemes are superior to that of random RS and orthogonal multiple access based RS schemes.

Real-time and energy-efficient transmissions are two critical demands for status update systems, however it is difficult to meet these requirements simultaneously. This paper focuses on the tradeoff between the average age of information (AoI) and the average energy cost (EC) for two-hop decode-and-forward (DF) relaying networks with short packet transmissions. Both the partial relay selection (PRS) and max-min relay selection (MMRS) schemes are considered. The expressions for the average AoI and the average EC of two-hop relaying networks are derived, and the age-energy tradeoff is also achieved by minimizing the weighted sum of them. Numerical simulations show that both PRS and MMRS schemes have their own advantages to minimize the age and energy cost under different channel conditions, where MMRS is a fairness scheme that takes the channel conditions of two hops into account. In addition, an optimal packet length can always be found to tradeoff the average AoI and average EC in two-hop relaying networks.

In this paper, we propose to optimize the power of Primary User (PU) and secondary relays R k to maximize the Detection Probability (DP). We suggest to maximize the detection probability of cooperative spectrum sensing with relay selection. One relay is chosen to amplify the PU signal to the fusion center D where spectrum sensing using the Energy Detector (ED) is performed. The selected relay offers the highest instantaneous Signal to Noise Ratio (SNR) and allows to increase the DP since the best relay is selected. Optimal power allocation allows 0.7 dB gain with respect to Uniform Power Allocation where the same power is allocated to PU and selected relay. The proposed optimal power allocation is applied for opportunistic Amplify and Forward (AF) relaying, Partial and Reactive Relay Selection (PRS and RRS).

The outage probability and bit error rate averaged over the distribution of the number of relays in Nakagami- m fading channels are analyzed for full and partial relay selection (RS) schemes. This analysis considers a random number of relays caused by the relay's own on-off traffic. Based on this analysis, optimization of the relaying time is performed, and the optimal values of the relaying time are obtained. Numerical results show that there do exist locally optimal values of the relaying time for different system settings. For average outage probability, the optimal value increases when the threshold increases, the m parameters decrease, or partial selection is used instead of full selection. For an average bit error rate, the optimal value increases when the average signal-to-noise ratio (SNR) decreases, the m parameters decrease, the number of relays increases, or partial selection is used instead of full selection.

Considering existing eavesdroppers, this paper analyzes the secrecy outage probability (SOP) of the full-duplex (FD) relaying network with imperfect channel state information (CSI), where the decode-and-forward relay protocol is adopted. To enhance the physical-layer security, two relay selection schemes are proposed. The first scheme uses the maximum-minimum principle to select the optimal relay. The other selection scheme is based on partial signal-to-interference-plus-noise ratio. Then, the tight closed-form approximations of the SOP are obtained for three special CSI cases, respectively. Moreover, based on these approximated results, the effects of some system parameters are analyzed for the SOP of the relay system, including the CSI error, the number of relays, the signal-to-noise ratio (SNR) of the eavesdropper, and the residual self-interference caused by the FD model. The numerical results show that at low SNR of the eavesdropper, residual self-interference has a significantly impact on SOP, while at high SNR of the eavesdropper, this effect is negligible. In addition, the SOP of FD model is always superior to the half-duplex (HD) model when the number of relays changes.

This article derives the packet error probability (PEP) of different relay selection techniques for cognitive radio networks (CRN). The power of secondary source and relays is adaptive to not cause high interference to primary receiver $$P_R$$. Secondary nodes harvest energy from radio frequency signals to be able to communicate. CRN with secondary nodes transmitting with adaptive power was already studied in the literature. However, in all previous studies, secondary nodes use their own batteries to transmit. The main motivation of our paper is to study CRN with energy harvesting and adaptive transmit power (ATP). We derive new expressions of PEP and throughput for CRN with energy harvesting and ATP. Our results are valid for opportunistic relaying, partial relay selection and reactive relay selection. Our main contribution is to optimize harvesting duration to maximize the system throughput.

본 논문에서는, 증폭 후 재전송하는 부분 릴레이 선택 방식의 듀얼홉 릴레이 시스템에 대한 성능을 분석한다. 증폭 후 재전송하는 릴레이 이득은 채널과 잡음을 동시에 고려한 이득이다. 수신 SNR 모델을 이용하여 닫힌형태의 end-to-end SNR 확률밀도함수와 누적분포함수를 유도한다. 또한, 부분 릴레이 선택 방식을 갖는 듀얼홉 릴레이 시스템의 정확한 닫힌 형태의 채널 용량을 분석한다. 마지막으로 본 논문의 이론적인 분석은 Monte-Carlo 시험을 통하여 검증한다. In this paper, we analyze the performance of dual-hop amplify-and-forward (AF) relaying in cooperative networks with partial relay selection. An AF relay gain considered in this paper includes channel-noise-assisted relay gain. Leveraging a received signal-to-noise ratio (SNR) model, we derive exact closed-form expressions for the probability density function (pdf) and cumulative distribution function (cdf) of the end-to-end SNR. Moreover, an exact closed-form expression of the ergodic capacity for dual-hop AF relaying with channel-noise-assisted relay gain and partial relay selection is investigated. The analytical results shown in this paper are confirmed by Monte-Carlo simulations.

In this paper, we compare the performance in terms of symbol error probability, data rate and power consumption of the use of fixed transmit power (FTP) and adaptive transmit power (ATP) in underlay cognitive radio networks. The use of FTP alleviates the signaling requirements of underlay cognitive radio networks compared to the ATP. Nevertheless, the use of FTP influences the performances of the underlay cognitive radio networks. To study this influence, we consider three relay selection schemes using FTP: opportunistic decode and forward with FTP (O-DF with FTP), opportunistic amplify and forward with FTP (O-AF with FTP) and partial relay selection with FTP (PR with FTP). We compare the performances of these schemes in terms of symbol error probability, data rate and power consumption with three relay selection schemes using ATP: opportunistic decode and forward with ATP (O-DF with ATP), opportunistic amplify and forward with ATP (O-AF with ATP) and partial relay selection with ATP (PR with ATP). We provide exact and/or lower bound expressions of the symbol error probabilities of O-DF, O-AF and PR with FTP. The analytical study for the data rate and the power consumption is also provided. Our comparison study shows that FTP has a positive impact on the data rate and power consumption performance while it deteriorates the symbol error probability performance.

In this article, the physical layer security (PLS) is investigated for reconfigurable intelligent surface (RIS)-aided wireless communication systems, where one RIS is deployed to assist the communications between a pair of transmitter (Alice) and receiver (Bob), under a passive eavesdropper (Eve) attack. For the Eve, different from the bounded channel state information uncertainty model, the distribution of the Eve's location is introduced into the wiretap link. In the proposed system, considering that the Eve can overhear signals transmitted from Alice or reflected by the RIS, two scenarios are studied for RIS-aided secure communication systems: one is that the Eve distributes close to Alice without the RIS orientation, and the other is that the Eve locates close to Bob and in the presence of the RIS. After investigating the probability distribution functions of the Eve's location and the wiretap link, the novel cumulative density functions (CDFs) of the received signal-to-noise ratios (SNRs) at the Eves are, respectively, derived for the two considered scenarios, taking into account the effects of RIS reflection coefficients, pathloss, and Eve's location distribution. The closed-form expressions for the probability of the nonzero secrecy capacity and the ergodic secrecy capacity are obtained, providing insights into the impact of the Eve's location uncertainty and the RIS design on the secrecy performance. Moreover, based on the derived CDFs for received SNRs at Eves, the secrecy outage probabilities are, respectively, analyzed. Specifically, under the constraint of the secrecy outage probability, the closed forms of the minimum required SNRs at Bob and the number of RIS elements are also obtained. Simulation and analytical results corroborate the derived expressions and reveal the tradeoff between the system's energy efficiency and the number of RIS elements.

The paper derives the detection probability of cooperative spectrum sensing (CSS) algorithms with energy harvesting. There are three phases with the same duration. The first phase is the energy harvesting phase done by primary user (PU) and relay nodes. They harvest energy from radio frequency (RF) signal received from node H. In the second phase, PU transmits its signal that will be received by relays. In the last phase, a selected relay amplifies the PU signal to a fusion center (FC) where spectrum sensing is performed using the energy detector. Our analysis is valid for opportunistic amplify and forward (OAF), partial (PRS) and reactive relay selection (RRS). A Nakagami fading channel is assumed between all nodes.

This paper investigates the integration of relay-assisted Internet of Things (IoT) systems, focusing on the use of multiple relays to enhance the system performance. The central metric of interest in this study is system outage probability, evaluated in terms of latency. Our research provides a comprehensive analysis of system outage probability, considering different relay selection criteria to optimize the system’s transmission performance. Three relay selection strategies are employed to enhance the system transmission performance. Specifically, the first strategy, optimal relay selection, aims to identify the relay that minimizes the latency and maximizes the data transmission reliability. The second approach, partial relay selection, focuses on selecting a subset of relays strategically to balance the system resources and achieve the latency reduction. The third strategy, random relay selection, explores the potential of opportunistic relay selection without prior knowledge. Through a rigorous investigation, our paper evaluates the impact of these relay selection criteria on the performance of relay-assisted edge computing systems. By assessing the system outage probability in relation to latency, we provide valuable insights into the trade-offs and advantages associated with each selection strategy. Our findings contribute to the design and optimization of reliable and efficient edge computing systems, with implications for various applications, including the IoT and intelligent data processing.

This paper studies on the relaying selective matter in amplify-and-forward (AF) cooperation communication with full-duplex (FD) activity. Various relay choice models supposing the present of different instant information are investigated. We examine a maximal relaying choice that optimizes the instant FD channel capacity and asks for global channel state information (CSI) as well as partial CSI learning. To make comparison easy, accurate outage probability clauses and asymptote form of these strategies that give a diversity rank are extracted. From that, we can see clearly that the number of relays, noise factor, the transmittance coefficient as well as the information transfer power had impacted on their performance. Besides, the optimal relay selection (ORS) model can promote than that of the partial relay selection (PRS) model.