Outage Probability Analysis Research Articles

Performance analysis of dynamic ordered NOMA system

Non-orthogonal multiple access (NOMA) has emerged as a key enabling technology for the fifth generation (5G) and beyond networks. NOMA supports massive mobile connectivity, increases spectral efficiency, and ensures user fairness by providing access to various users to share common wireless resources. In this work, the analysis of sum-rate and outage probability (OP) has been carried out in the case of a downlink (DL) dynamic ordered NOMA (D-NOMA) system. Sum-rate of the system has been maximized using Karush-Kuhn-Tucker (KKT) technique. Expressions of OP are obtained over the Rayleigh fading channel. Finally, simulations are done to confirm the expressions obtained for OP and sum-rate. Also, a sum-rate comparison between the D-NOMA system and the fixed NOMA (F-NOMA) system has been done.

Outage Probability and Capacity Analysis for NOMA based 5G and B5G Cellular Communication

This study presents a non-orthogonal multiple access (NOMA) solution for 5G that unifies communication betweenmacro-cells via the S-R NOMA link and communication between small cells via the R-D NOMA link. S-R NOMA isused to decode own signal by respective relay. Separate studies of outage performance in S-R and R-D connectionsmay formerly be used to get an accurate definition of system outage likelihood. Our mathematical analysis issupported by simulation findings, which indicate that NOMA-assisted relaying systems outperform OrthogonalMultiple Access systems in terms of lower outage probability and better cumulative capacities (OMA).

Intelligent Wireless Monitoring Technology for 10kV Overhead lines in Smart Grid Networks

Promoted by the rapid development of information technology, 10kV overhead line has been widely used in the majority of cities, and it is of great significance to monitor the distribution network effectively, in order to ensure the normal operation of the system. Most of traditional distribution network monitoring methods are based on manual work, which causes inconvenience to the distribution network fault location, repair, maintenance and real-time monitoring, and reduces the efficiency of the distribution network emergency repair and the reliability of power supply. Aiming at the automatic monitoring problem of 10kV overhead network, this paper adopts an intelligent wireless monitoring technology, where a monitoring node is employed to monitor the network transmission status through wireless links. We evaluate the system monitoring performance by using the metric of outage probability, depending on the wireless data rate over wireless channels. For the considered system, we derive analytical outage probability, in order to measure the system performance in the whole range of signal-to-noise ratio (SNR). The simulation results are finally presented to verify the analytical expressions on the system monitoring outage probability in this paper.

Outage probability analysis of FSO system with Airy beam as carrier

Outage probability analysis of FSO system with Airy beam as carrier

NOMA-Based Cognitive Satellite Terrestrial Relay Network: Secrecy Performance Under Channel Estimation Errors and Hardware Impairments

Nonorthogonal multiple access (NOMA) and cognitive integrated satellite terrestrial relay networks are the promising and key part for the next-generation wireless networks. This article researches the joint effects of channel estimation errors (CEEs) and hardware impairments on the secrecy performance of cognitive integrated satellite terrestrial relay networks. The noncolluding eavesdropping scheme is applied in the multiple eavesdroppers, where the eavesdropper with the highest eavesdropping capacity is selected to overhear the legitimate transmission signal. Moreover, the detailed analysis for the secrecy outage probability (SOP) is obtained based on the utilized partial terrestrial relay selection strategy. To obtain the insightful conclusions, the asymptotic analysis along with the secrecy coding gain and secrecy diversity order for the SOP are further derived, which gives the effective methods to valuate the impacts of CEEs and hardware impairments on the considered system with the NOMA scheme in high signal-to-noise ratio regime. Moreover, simulations are derived for the secrecy energy efficiency. Finally, Monte Carlo simulations are given to prove the correctness of the theoretical SOP analysis.

On the Power-Splitting Relaying Protocol for SWIPT with Multiple UAVs in Downlink NOMA-IoT Networks

Unmanned aerial vehicle (UAV) communication and non-orthogonal multiple access (NOMA) are two promising technologies for wireless 5G networks and beyond. The UAVs can be used as flying base stations to form line-of-sight communication links to the Internet of things devices (IDs) and to enhance the performance of usual terrestrial cellular networks. Moreover, the UAVs can also be deployed as flying relay nodes for forwarding data from a base station (BS) to the IDs. On the other hand, non-orthogonal resource sharing for many concurrent users is exploited in NOMA, thus improving spectrum efficiency (SE) and supporting massive connections. The NOMA combined with energy harvesting (EH) in an amplify-and-forward (AF) with cooperative UAV systems is researched. Specifically, the UAVs act as rotary-wing relays to forward data from the BSs to two IDs. This paper focuses on the analysis of outage probabilities (OPs), system throughput, and energy efficiency (EE) for two IDs. Besides, we also do the asymptotic analysis of OPs at high signal-to-noise ratios (SNRs). Furthermore, this paper also inspects the impacts of the UAV-based relaying on the OP, system throughput, and EE of the proposed NOMA scheme. The derived asymptotic expansions show that the suggested model can enhance user fairness and the analytical results match the simulation results.

Security Outage Probability Analysis of Cognitive Networks With Multiple Eavesdroppers for Industrial Internet of Things

The Industrial Internet of Things (IIoT) has been recognised as having the potential to benefit a range of industrial sectors substantially. However, widespread development and deployment of IIoT systems are limited for some reasons, the most significant of which are a shortage of spectrum resources and network security issues. Given the heterogeneity of IIoT devices, typical cryptographic security techniques are insufficient since they can suffer from challenges including computation, storage, latency, and interoperability. This paper presents a physical layer security analysis of the underlying cognitive radio networks for IIoT. Through consideration of the spectrum, IIoT devices can opportunistically utilise the primary spectrum, thereby improving spectrum efficiency and allowing access by an increased number of devices. Specifically, we propose two cognitive relay transmission (CRT) schemes, optimal single CRT (O-SCRT) and multiple CRT (MCRT), to improve transmission reliability further. Since it is challenging to obtain channel state information in the wiretap link, we provide a sub-optimal single CRT scheme and derive closed-form expressions of security outage probability by invoking both selection combination and maximal ratio combination techniques at the eavesdropper. To provide a benchmark, the round-robin single CRT scheme is also analyzed. Simulation results are provided to verify our analysis and show that O-SCRT provides the best system security outage performance.

Timeliness optimization of unmanned aerial vehicle lossy communications for internet-of-things

Information freshness is a key factor for Internet-of-Things (IoT) to make appropriate decisions and operations. This paper proposes an analytical framework for evaluating the timeliness performance of the IoT system based on Unmanned Aerial Vehicle (UAV) lossy communications. The performance analysis consists of the outage probability analysis and the Age-of-Information (AoI) analysis with outages. To begin with, we solve a lossy coding problem formulated from the UAV communication system, and derive a closed-form expression of the outage probability based on Shannon’s lossy source-channel separation theorem. Then, we characterize the Peak AoI (PAoI) for the considered system, and further minimize the PAoI by deriving the optimal rate for generating information. Moreover, we analyze the system performance through theoretical calculations and simulations. The results indicate that the optimal server utilization ratio is always no larger than 0.5. In practical applications, we can utilize the proposed analytical framework to determine the system parameters which guarantee the timeliness performance of UAV lossy communications.

Outage Analysis of NOMA-Enabled Backscatter Communications With Intelligent Reflecting Surfaces

Intelligent reflecting surface (IRS) has emerged as a potential technology to achieve smart wireless communications and high energy efficiency. On the other hand, nonorthogonal multiple access (NOMA)-enabled backscatter communications have shown a great potential in large-scale Internet of Things (IoT) networks. In this article, we consider a downlink IRS-assisted backscatter communication with NOMA. We further consider a two-user scenario with channel disparity from the base station. We first derive the probability density function of the sum of the modulus of reflected channels, where each channel follows the Rayleigh distribution with dissimilar variances. The respective and generalized closed-form outage probability expressions are derived for the considered scenario. Simulation results validate the accuracy of the analytical outage probability expressions. We demonstrate that the far user can achieve a superior performance with the increase of reflecting elements or the reflection coefficients.

Outage Probability and Finite-SNR DMT Analysis for IRS-Aided MIMO Systems: How Large IRSs Need to be?

Intelligent reflecting surfaces (IRSs) are promising enablers for high-capacity wireless communication systems by constructing favorable channels between the transmitter and receiver. However, general, accurate, and tractable outage probability analysis for IRS-aided multiple-input-multiple-output (MIMO) systems is not available in the literature. In this paper, we first characterize the distribution of the mutual information (MI) for IRS-aided MIMO systems by capitalizing on large random matrix theory (RMT). Based on this result, a closed-form approximation for the outage probability is derived and a gradient-based algorithm is proposed to minimize the outage probability with statistical channel state information (CSI). We also investigate the diversity-multiplexing tradeoff (DMT) with finite signal-to-noise ratio (SNR). Based on these theoretical results, we further study the impact of the IRS size on system performance. In the high SNR regime, we provide closed-form expressions for the ergodic mutual information (EMI) and outage probability as a function of the IRS size, which analytically reveal that the benefit of increasing the IRS size saturates quickly. Simulation results validate the accuracy of the theoretical analysis and confirm the increasing cost to improve system performance by deploying larger IRSs. For example, for an IRS-aided MIMO system with 20 antennas at both the transmitter and receiver, we need to double the size of the IRS to increase the throughput from 90% to 95% of its maximum value.

Secrecy Outage Analysis of Relay-User Pairing for Secure Hybrid Satellite-Terrestrial Networks

In this paper, we study the physical-layer security of a hybrid satellite-terrestrial network composed of a satellite, multiple terrestrial decode-and-forward (DF) relays and users in the presence of a terrestrial eavesdropper who attempts to tap legitimate information from both satellite and relays. We consider two different scenarios: I) the channel state information (CSI) of wiretap links is known, and II) the CSI of wiretap links is unknown. Accordingly, optimal and suboptimal relay-user pairing schemes are proposed for the aforementioned two scenarios, respectively. Specifically, a relay-user pair maximizing the secrecy rate is chosen as the optimal one to participate in the transmission, where all links’ CSI is used to perform relay-user pairing. However, suboptimal relay-user pairing scheme is designed only relying on the main links’ CSI without requiring wiretap links’ CSI, where a relay-user pair with the maximal transmission rate of main link is selected. Also, closed-form expressions of secrecy outage probability with both integer and rational fading severity parameter are derived in the case of satellite links undergo Shadowed-Rician fading and terrestrial links subject to Rayleigh fading. Furthermore, asymptotic secrecy outage probability analysis is conducted in the high signal-to-noise ratio region. Numerical results reveal that relay-user pairing is beneficial to further improve physical-layer security of the hybrid satellite-terrestrial network.

Outage Probability Analysis of STAR-RIS Assisted NOMA Network With Correlated Channels

In this letter, we investigate the outage probability of a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) assisted downlink non-orthogonal multiple access (NOMA) network over spatially correlated channels. To evaluate the impact of channel correlations on the system performance, we first approximate the distribution of the composite channel gain as a gamma random variable via a moment-matching approach and then derive new close-form outage probability expressions for a pair of NOMA users. Based on the approximate results, the diversity of each user is studied. Numerical results are provided to validate the effectiveness of the theoretical analysis and illustrate the performance loss due to channel correlations.

Copula-Based Modeling of RIS-Assisted Communications: Outage Probability Analysis

Statistical characterization of the signal-to-noise ratio (SNR) of reconfigurable intelligent surface (RIS)-assisted communications in the presence of phase noise is an important open issue. In this letter, we exploit the concept of copula modeling to capture the non-standard dependence features that appear due to the presence of discrete phase noise. In particular, we consider the outage probability of RIS systems in Rayleigh fading channels and provide joint distributions to characterize the dependencies due to the use of finite resolution phase shifters at the RIS. Numerical assessments confirm the validity of closed-form expressions of the outage probability and motivate the use of bivariate copula for further RIS studies.

Secrecy performance of two‐way integrated satellite terrestrial relay networks with multiple users

This letter studies the secrecy performance for a two-way integrated satellite terrestrial relay networks. Particularly, multiple legitimate users along with maximal user scheduling scheme are applied in the considered networks. In addition, the closed-form expression for the secrecy outage probability of the considered two-way networks is obtained. Moreover, to investigate the impacts of the system parameters on the secrecy performance in high signal-to-noise ratio regime, the asymptotic analysis for the secrecy outage probability is further derived. Finally, Monte Carlo simulation results are provided to prove the theoretical results.

Throughput Enhancement in FD- and SWIPT-Enabled IoT Networks Over Nonidentical Rayleigh Fading Channels

Simultaneous wireless information and power transfer (SWIPT) and full-duplex (FD) communications have emerged as prominent technologies in overcoming the limited energy resources in Internet of Things (IoT) networks and improving their spectral efficiency (SE). This article investigates the outage and throughput performance for a decode-and-forward (DF) relay SWIPT system, which consists of one source, multiple relays, and one destination. The relay nodes in this system can harvest energy from the source’s signal and operate in the FD mode. A suboptimal, low-complexity, yet efficient relay selection scheme is also proposed. Specifically, a single relay is selected to convey information from a source to a destination so that it achieves the best channel from the source to the relays. An analysis of outage probability (OP) and throughput performed on two relaying strategies, termed static power splitting-based relaying (SPSR) and optimal dynamic power splitting-based relaying (ODPSR), is presented. Notably, we considered independent and nonidentically distributed (i.n.i.d.) Rayleigh fading channels, which pose new challenges in obtaining analytical expressions. In this context, we derived exact closed-form expressions of the OP and throughput of both SPSR and ODPSR schemes. We also obtained the optimal power splitting ratio of ODPSR for maximizing the achievable capacity at the destination. Finally, we present extensive numerical and simulation results to confirm our analytical findings. Both simulation and analytical results show the superiority of ODPSR over SPSR.

Differential STBC NOMA: A new approach to downlink cooperative NOMA

Abstract Due to the ability of massive connectivity, large bandwidth, and low latency, the non-orthogonal multiple access (NOMA) is considered the best approach for the 5th generation and beyond. However, the system performance is declined when the number of users is increased as each user will experience a great number of successive interface cancelations (SIC) in the downlink. To improve system performance, the NOMA is combined with cooperative communication which gives more spectral efficiency and fairness as compared to non-cooperative NOMA. Furthermore, space-time block code (STBC)- cooperative NOMA-based users experienced less SIC as compared to conventional CNOMA. This paper evaluates the performance of differential STBC-CNOMA with keeping in mind the imperfect SIC, channel state information (CSI), and timing synchronization between distributed cooperating users. The simulations results show that differential STBC-CNOMA gives high performance in terms of outage probability and sum rate analysis as compared to simple STBC-NOMA and conventional CNOMA. Hence, the differential STBC-CNOMA seems to be a better and more effective solution to enhance system performance.

Outage probability analysis of a vertical underwater wireless optical link subject to oceanic turbulence and pointing errors

The reliability of an underwater wireless optical communication (UWOC) network is seriously impacted by beam misalignment between transmitters (Txs) and receivers (Rxs). Also, the performance of UWOC systems can be affected by oceanic turbulence-induced fading due to fluctuations in the water refractive index as a result of variations in the pressure, water temperature, and salinity. In this work, we investigate the performance analysis of a vertical UWOC link subject to oceanic turbulence and pointing errors and further investigate the appropriate selection of link parameters to optimize link performance. This study is based on an accurate mathematical framework for link modeling while taking into account realistic Tx/Rx and channel parameters under different turbulence and beam misalignment conditions. We provide an analytical expression for calculating the link outage probability, whose accuracy is validated through numerical simulations. Last, the necessity of optimal Tx/Rx parameter selection to minimize the link outage is demonstrated. A laser beam is considered at the Tx, as well as an ultra-sensitive photodetector (silicon photo-multiplier) at the Rx to enable working at relatively long link ranges. The presented results give valuable insight into the practical aspects of deployment of UWOC networks.

Splitting Energy of Transmit Power Serving Grouping Users in Full-Duplex Networks under Imperfect Hardware

In this paper, we consider a wireless system providing power allocation fairness for grouping users by conducting a non-orthogonal multiple access (NOMA). In particular, a rigorous analysis is performed to evaluate performance of destination in a downlink of wireless system. With advances of NOMA, the user grouping scheme allows users to be shared the same frequency/power domain, and hence, fairness is guaranteed. In this regard, we focus on evaluation of the performance of a cell-center user and a cell-edge user in dedicated group. To enable forwarding function at cell-center user, we require the assistance of a full-duplex– (FD–) based relay to serve the cell-edge user. These users are assigned a fixed power allocation scheme. To characterize system performance, the closed-form expressions of the outage probability are computed for two users. To generalize channels in such system, Nakagami-m fading channels could be adopted to achieve complete theoretical analysis. Furthermore, we provide some comparisons of such FD NOMA under the impact of hardware impairment. We find that a significant improvement of outage probability can be achieved when the signal-to-noise ratio (SNR) at the source is high. Numerical results illustrate that both the analytical outage probability of the central user and the cell-edge user match the simulation results.

Secrecy outage probability analysis in a free-space optical system based on partially coherent beams through anisotropic non-Kolmogorov turbulent atmosphere

In this paper, the secrecy outage probability of a partially coherent beam free-space optical communication system considering the combined effect of anisotropic non-Kolmogorov strong turbulent atmosphere and the eavesdropper’s position is investigated. The Fisher–Snedecor distribution is chosen to model the atmospheric turbulence because it is not only suitable for weak to strong turbulence conditions but is also mathematically simple. Based on the fading channel model and the generalized pointing error model, we derive analytical expressions for the lower bounded secrecy outage probability. Also, we obtain asymptotic closed-form expression at a high signal-to-noise regime. The obtained expressions are corroborated by Monte Carlo simulations. The calculation results based on the analytical expressions show that increasing the source coherence parameter makes the secrecy interruption probability performance first better and then worse for a given condition, and an optimal value is observed. The anisotropic coefficient and power law have a positive effect on the secrecy outage probability of the free-space optical communication system. Under the given conditions, the performance of the secrecy outage probability is significantly improved by the divergent beam, although the increased spot size at the receiver makes it easier for eavesdroppers to tap the link. The secrecy outage probability performance deteriorates as the vertical component of Bob, the jitter variance, and the refractive index structure constant increase.

Bit error rate and outage probability analysis for multi-hop decode-and-forward relay-aided NOMA with imperfect SIC and imperfect CSI

This paper investigates a multi-hop decode-and-forward (DF) relay-aided non-orthogonal multiple access (MH-DF-R-NOMA) scheme. The model overcomes the problems associated with poor channel quality and disconnection communication with the broadcast station for the users through the path from the intermediate relay nodes to deliver the signal to the users. We assume that we have multiple intermediate relay nodes that constitute the path to transmit the signal to two users who have different channel qualities. Consequently, the closed-form expressions for bit error rate (BER) and outage probability (OP) at all intermediate relay nodes and users are derived. In the analysis, the imperfect channel state information (CSI) and imperfect successive interference cancellation (SIC) are taken into account. Computer simulation are presented to validate theoretical analyzes. The results indicate that the degradation of BER and OP performances for the near user is higher than the far user. We also show the superiority of our model over the single relay scheme. Furthermore, the OP of MH-DF-R-NOMA outperforms its counterpart in OMA.