Outage Probability Analysis Research Articles

UAV Selection and Link Switching Policy for Hybrid Tethered UAV-Assisted Communication

Unmanned aerial vehicles (UAVs) have been a frontier of communication technology research for their unique advantages. Their mobility and flexibility enable their use in next-generation wireless networks. This letter explores tethered UAV-assisted hybrid cooperative communication to improve the end-to-end performance of the links between base stations and user equipment. We propose a simple, novel, channel state information (CSI)-free UAV selection policy and a hybrid PHY layer (RF or mmWave or FSO) link switching policy. We develop an insightful outage probability analysis of the proposed policy. The policy and its analysis serve as a useful analytical benchmark for UAV-assisted wireless systems.

Outage analysis of cognitive non‐orthogonal multiple access downlink system with secondary source selection in Nakagami‐m fading environment

SummaryCognitive inspired non‐orthogonal multiple access (Cognitive‐NOMA) technique allows multiple primary and secondary users to utilize the same time and frequency resources to explore the reliability and spectral efficient requirements of 5G communication networks. In this paper Cognitive‐NOMA downlink system with multiple secondary source (SS) nodes is proposed. An optimal SS node is selected based on the signal to interference plus noise ratio (SINR) requirements of both near and far primary users and the secondary user node. Each optimal SS node incorporates simultaneous wireless information and power transfer (SWIPT) and full‐duplex technique to harvest energy and transceiver operation. Analytical outage probability expressions of the proposed system are derived over Nakagami‐m fading environment with the assumption that SS transmission links are correlated. Numerical results infer that the outage performance of the proposed system depends on the number of SS nodes, self‐interference at the SS node, and the SINR constraint for the selection of optimal SS node.

Performance Analysis and Prediction for Mobile Internet-of-Things (IoT) Networks: A CNN Approach

With the increasingly mature sensor technology and the increasing popularity of broadband network, “the Internet-of-Everything” era is coming, and the mobile Internet of Things (IoT) is booming around the world. However, the mobile IoT communication networks face serious challenges, which are caused by the complex and variable communication environments. The mobile IoT applications can produce large-scale data, which will consume substantial energy. The transmit antenna selection (TAS) and cooperative communication schemes are commonly used to reduce the complexity and the energy consumption, which directly impact the performance of mobile IoT networks. To evaluate the performance of mobile IoT networks, it is important to analyze outage probability (OP) performance. In this article, we investigate the OP performance analysis of mobile IoT communication networks and propose an OP intelligent prediction algorithm based on an improved convolutional neural network (CNN). First, the mobile OP performance is analyzed by combining the TAS and decode-and-forward cooperative schemes, and the exact OP expressions are derived. Then, an improved CNN is designed to avoid the loss of important information, which contains the input layer, three-convolution layer, one fully connected layer, and output layer. The proposed CNN-based prediction approach is compared with the radial basis function (RBF), generalized regression (GR), Elman, and extreme learning machine (ELM) methods. The simulation results validate that the proposed CNN prediction approach can achieve a better prediction effect than RBF, Elman, GR, and ELM methods. For the CNN approach, it has a 44% increase in the prediction accuracy.

Outage probability analysis of overlay cognitive two‐way relaying scheme with opportunistic relay selection

The authors investigate an overlay cognitive two-way relaying system where max-min (MM) relay selection scheme is employed for improving the reliability of the considered system. Furthermore, they design the process of the data forwarding and relay selection in the overlay cognitive two-way relaying system. Based on the MM relay selection criterion, the exact close-form expression of outage probability is derived. From numerical simulations, it is observed that there is an outage probability floor appearing in the high signal-to-noise ratio (SNR) region, and the reason for its occurrence is stated. Besides, the approximate result of outage probability in high SNR is provided, which shows that the ratio of interference channel' transmit power and main channel' transmit power will not affect the outage probability in low SNR region, but it will significantly affect it in the high SNR region. Although each individual channel state information (CSI) will not be able to control the outage performance of this considered system in the high SNR region, the ratio of each channel's CSI will be able to do the same.

Lower and upper bound form for outage probability analysis in two-way of half-duplex relaying network under impact of direct link

In this paper, the system performance of the two-way of half-duplex (HD) relaying network under the impact of the direct link is studied. The model system has two sources (S) and one destination (D) communicate by direct link and via relay (R). For system performance analysis, we derived the lower and upper bound for outage probability (OP). Furthermore, the analytical expressions of the system performance are verified by using the Monte Carlo simulation in the effect of main parameters. As shown in the results, we can the simulation and analytical results have a good agreement.

Performance Evaluation of Downlink Multiple Users NOMA-Enable UAV-Aided Communication Systems Over Nakagami-m Fading Environments

We evaluate a downlink non-orthogonal multiple access (NOMA)-enable UAV-aided communication system to address the demand of spectrum usage of unmanned aerial vehicles (UAVs). In this paper, multiple NOMA users are served by an UAV to improve the effective spectrum usage. Over Nakagami- $m$ fading model, the performance of the system was investigated based on the analysis of outage probabilities (OPs) of the NOMA users, the ergodic rate, and symbol error rate of the system under two scenarios, i.e., perfect successive interference cancellation (pSIC) and imperfect successive interference cancellation (ipSIC). Additionally, the effects of the system parameters such as the transmit power and altitude of the UAV, the coefficients of channel model on the system performance were studied. The results demonstrate that the performance of the NOMA-based system is better compared with that of the conventional orthogonal multiple access (OMA)-based system in terms of OP, throughput and ergodic rate. Considering outage probabilities at the users, the system in the ipSIC case achieves the same performance as the pSIC case at a low transmit power of the UAV. In addition, an increase in the height of the UAV decreases the ergodic capacity of each user.

Throughput Analysis of In-Band Full-Duplex Transmission Networks With Wireless Energy Harvesting Enabled Sources

In this paper, we investigate a two-hop communication system in which the source utilizes radio frequency (RF) energy harvesting for the transmission of information. An intermediate relay works in a half-duplex (HD) mode in the energy harvesting (EH) phase to provide energy to the source. In the information transmission phase, the relay works in a full-duplex (FD) mode to receive information signals from the source and simultaneously transmit information signals to the destination in the same frequency band. The paper provides the analysis of outage probability and throughput of a FD relaying system and two HD relaying systems. The first HD system ( $HD_{1}$ ) has the same EH duration as the FD system while the second HD one ( $HD_{2}$ ) has the same transmitting power from the source as the FD one. The results show that the throughput with respect to the time split between the EH phase and the information transmission one is a concave function and the optimal time split can be calculated numerically. Besides, the polarization dissimilarity factor of the antennas used has an influence on the system throughput, which is maximized when polarization states are orthogonal. The FD system can double the system throughput while having the outage probability as low as that of the $HD_{1}$ system, at a cost of adopting the extra polarization-enabled digital cancellation (PDC) scheme. Meanwhile, the FD system can nearly double the system throughput while having the outage probability superior to that of the $HD_{2}$ system. Simulations are run to confirm the above analyses.

Outage probability analysis for relay-based cognitive radio network

This paper is delineating with relay-based subjective radio system (CRN) with different optional source hubs and numerous auxiliary goal nodes. The quality of service is mainly ability can be enhanced with proper resource allocation. The link value is preserved by keeping SNR above a threshold called minimum protection ratio. Uplink resource allocation based on hybrid cooperative CR network (HCCRN) is considered in which licensed radio and cognitive radio are combined. Cognitive relay is utilised for range extension to attain greater capacity. CRN stands for cognitive radio network. Medium access layer network coding (MALNC) is connected with two sorts of full duplex transfer to be specific amplify and forward (AF), decode and forward (DF) for the fruitful transmission of data. Identification of data at the collector is anticipated by multiple range groups. Utilisation of MALNC lessens to the quantity of vacancies required for correspondence. Log typical conveyances are utilised for divert parameter investigation within the sight of shadowing of sign because of huge hindrances in versatile radio correspondence. Blackout likelihood is portrayed for blurring channel. A variety of the estimation of mean, fluctuation and transmission rate is done to accomplish an effective framework.

Security in IoT-Enabled Digital Twins of Maritime Transportation Systems

The purposes are to explore the safety performance of the Maritime Transportation System (MTS) based on Digital Twins (DTs) Internet of Things (IoT) and develop maritime transportation towards intelligence and digitalization. Because the comprehensive operational security of modern MTS is not yet mature, historical transportation data of the Maritime Silk Road are acquired and preprocessed. Afterward, DTs are introduced, and relay nodes are added to data transmission paths to construct a maritime transportation DTs model based on relay cooperation IoT. Eventually, this model's security performance is validated through simulation experiments. Relay security analysis suggests that interference information is a vital guarantee to assist in information non-disclosure, from which the constructed model can harvest energy to increase the data transmission power, thereby improving communication performance and secrecy rate. Outage probability analysis reveals that the simulated and the theoretical results are almost the same; moreover, given the system's multi-hop paths in the same environment, the more the relays and the greater the fading index, the better the system performance and the lower the outage probability. Once the iterations reach a particular number, the node secrecy rate becomes optimal and cannot cause excessive burden to the system; besides, the power distribution can establish a new equilibrium when the nodes are in different locations, so that system security performance gets improved. The simulated value is closest to the actual result under 100% successful transmission probability and 0.01~0.05 λ value. To sum up, the constructed maritime transportation DTs model presents extraordinary transmission and security performance, providing an experimental basis for intelligent and secure maritime transportation in the future.

Outage probability analysis for relay-based cognitive radio network

This paper is delineating with relay-based subjective radio system (CRN) with different optional source hubs and numerous auxiliary goal nodes. The quality of service is mainly ability can be enhanced with proper resource allocation. The link value is preserved by keeping SNR above a threshold called minimum protection ratio. Uplink resource allocation based on hybrid cooperative CR network (HCCRN) is considered in which licensed radio and cognitive radio are combined. Cognitive relay is utilised for range extension to attain greater capacity. CRN stands for cognitive radio network. Medium access layer network coding (MALNC) is connected with two sorts of full duplex transfer to be specific amplify and forward (AF), decode and forward (DF) for the fruitful transmission of data. Identification of data at the collector is anticipated by multiple range groups. Utilisation of MALNC lessens to the quantity of vacancies required for correspondence. Log typical conveyances are utilised for divert parameter investigation within the sight of shadowing of sign because of huge hindrances in versatile radio correspondence. Blackout likelihood is portrayed for blurring channel. A variety of the estimation of mean, fluctuation and transmission rate is done to accomplish an effective framework.

Throughput and Outage Probability Analysis for Cognitive Radio-Non-Orthogonal Multiple Access in Uplink and Downlink Scenarios

Non orthogonal multiple access (NOMA) in cognitive radio (CR) network has been recognized as potential solution to support the simultaneous transmission of both primary and secondary users. In addition, CR-NOMA can also be used to serve multiple secondary networks in overlay cognitive radio networks. The aim of our work is to increase the secondary user’s throughput without compromising in QoS requirements of the primary users. Our presented work analyses the performance of power domain NOMA in cognitive radio networks for both uplink and downlink scenarios. The primary aspect of the work is to investigate the impact of power allocation on spectrum efficiency and fairness performance of CR-NOMA. Objective function is to maximize the overall throughput under the QOS constraints of the users. We have derived closed form expressions for optimized power allocation coefficient(α) for CR-NOMA uplink and downlink communications. Parameters causing the channel outage, have been examined and conditions for outage probability is derived for CR-NOMA communication. Finally, we have presented the simulation results to validate the mathematical models that are developed for power allocation coefficient and outage probability.

Outage Probability Analysis of Decode-and-Forward Two-Way Relaying System with Energy Harvesting Relay

In this paper, we evaluate a two-way relay system consisting of two terminals and an intermediate relay. In this model, two terminals do not have a direct link but exchange data with each other via the relay in three phases. The relay utilizes energy harvesting technology to collect energy from the received signals of two terminals in the first two phases and then uses the obtained energy for signal transmission in the third phase. Each node is equipped with a single antenna and operates under a half-duplex mode. All wireless channels are influenced by reversible independent flat Rayleigh fading. Using analytical methods, we provide the exact and approximate closed-form expressions of user outage probability and system outage probability. The approximate expressions of these outage probabilities are more explicit and straightforward, providing a better understanding of the influences of network parameters on the system quality. Monte-Carlo simulations are used to confirm the correctness of mathematical analyses.

Secrecy outage probability analysis for RIS‐assisted NOMA systems

In this Letter, the physical layer security for a novel reconfigurable intelligent surface (RIS)-assisted non-orthogonal multiple access (NOMA) system in a multi-user scenario is investigated, where the authors consider the worst case that the eavesdropper also utilises the advantage of the RISs. More specifically, they derive analytical results for the secrecy outage probability (SOP). From the numerical results, they observe that the use of RISs can improve the secrecy performance compared to traditional NOMA systems. However, for the worst case that the received signals at the eavesdropper come from the RISs and source, increasing the number of intelligent elements on the RIS has a negative impact on the secrecy performance. At high signal-to-noise ratios, the system's SOP tends to a constant. Finally, the secrecy performance can be improved through group selection.

Analysis of Outage Probability in Wavelength Diversity Based FSO Link Under Gamma–Gamma Fading with Varying Atmospheric Attenuation

Free space optical (FSO) communication links offers an emerging alternative to RF communication links because of high speed, secure and cost-effective options to provide the last mile connectivity to end-users. They may be deployed for quick network access temporarily during link failure and natural disaster. This paper focusses on the performance of FSO communication link impaired with strong turbulence and atmospheric attenuation added through varying climatic conditions. A closed-form expression for outage probability is derived to evaluate the performance under different levels of atmospheric attenuation and turbulence strengths. The mathematical analysis clearly shows inimical effects added by atmospheric attenuation over the performance of the communication link. The impact of wavelength diversity on the outage probability of such a link is analyzed with three carrier wavelengths 1550 nm, 1310 nm and 850 nm. The simulation results with wavelength diversity for different atmospheric attenuation levels and turbulence are plotted and analyzed.

Performance Analysis of OSTBC-NOMA System in the Presence of Practical Impairments

This paper investigates the performance of a power-domain downlink non-orthogonal multiple access (NOMA) system in the presence of practical impairments such as channel estimation error (CEE), feedback delay (FBD) and imperfect successive interference cancellation (SIC), where the base station communicates with multiple users by applying orthogonal space-time block coding (OSTBC) technique in order to exploit the benefits of transmit diversity. Outage probability (OP), ergodic capacity and fairness index analyses are conducted in case channels are subjected to Nakagami-m fading in order to illustrate the level of system performance, and closed-form mathematical expressions are obtained. Furthermore, to demonstrate the impact of CEE and FBD, asymptotic OP is also maintained. The analytical results validated by Monte Carlo simulations demonstrate that all performance metrics reach a non-zero fixed value in high signal-to-noise region due to the CEE and FBD while imperfect SIC worsens the performance of user with the lowest power allocation to the full outage. In addition, NOMA outperforms its counterpart orthogonal multiple access in terms of OP and ergodic capacity generally. Also, G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -OSTBC code has higher fairness index than G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -OSTBC code.

Outage probability analysis in DF power-splitting full-duplex relaying network with impact of Co-channel interference at the destination

Nowadays, improving the WPCN efficiency problem is the leading research direction in the communication network. In this research, the outage probability (OP) analysis in DF power-splitting (PS) full-duplex (FD) relaying network with impact of co-channel interference at the destination is proposed and investigated. In the system model section, we present the DF PS FD Relaying Network with Impact of Co-channel interference at the destination. Then in the system performance section, we analyze and derive the closed-form expression of the OP and investigate the effect of the main system parameters on the system network performance. Then, we perform the Monte Carlo simulation to verify the analytical section. This research can provide a new recommendation for the communication network.

Outage probability and achievable rate analysis for massive MIMO downlink with mixed-DAC and MF precoding

This paper analyses of the outage probability and the achievable rate of massive multi-input-multi-output (MIMO) systems, in which the base station (BS) is equipped with digital-to-analog-converters (DACs) of mixed-level resolution. And the matched-filter (MF) precoding is used on the BS. Closed-form expressions are derived by the distribution of user-interference power and other statistical properties in the signal-to-interference-plus-noise-ratio. Then, the combination of mixed-DACs resolution profile is chosen about outage probability and achievable rate with the BS energy consumption. And the resolution configurations between the outage probability and the achievable rate and the BS energy consumption are given. Meanwhile, Effects of related parameters and channel errors are analysed about outage probability and achievable rate. The numerical results show that the correctness of the formula derivations. As the number of users increases the system's achievable rate increases and the outage probability decreases. The selected resolution configuration system has better comprehensive performance.

Energy-efficiency maximization bidirectional direct and relay transmission

Energy-efficient transmission (EET) has become a very important problem in wireless communication. Optimal power allocation (OPA) is one of the general methods to achieve EET. But when OPA is only considered in EET, it maybe cannot analyze EET problems accurately. This paper aims at analyzing energy-efficient bidirectional direct and relay transmission (RT) through joint optimization of transmit power (TP) and transmit time (TT) allocation. In RT, direct links (DLs) are existed. The EET problems are given with three optimization cases: (i) maximizing sum throughput (ST) to maximize energy efficiency (EE), in such case, optimal TT (OTT), optimal relay position (ORP), and outage probability analysis are given; (ii) minimizing total energy consumption (TEC) to maximize EE, in such case, optimal TP (OTP), OTT with gradient-descent algorithm, and influences of asymmetry and asymmetry transmission tasks are given; and (iii) maximizing ST and minimizing TEC simultaneously to maximize EE, in such case, Dinkelbach’s algorithm and one-by-one optimal algorithm are given. Simulation results are presented to validate theoretical analysis. Results reveal that relay technique and DLs in RT can improve system’s EE.

Copula function‐based analysis of outage probability and coverage region for wireless multiple access communications with correlated fading channels

From practical and theoretical viewpoints, performance analysis of communications with correlated fading channels is important. In this study, the authors exploit a novel approach based on Copula function concept to investigate the impact of correlation of Rayleigh fading channels on communication performances. One of the most convenient ways to describe the dependence between several variables is using Copula functions. For this purpose, by applying the Farlie–Gumbel–Morgenstern Copula function, they derive closed-form expressions for outage probability as well as coverage region in a wireless multiple access channel. It is shown that the fading correlation improves the outage probability and coverage region for negative dependence structure. Specifically, whenever the dependence structure tends to negative values, the outage and coverage region performance improvement is increased. Finally, the efficiency of the analytical results is illustrated numerically.

Outage Probability Analysis and Minimization in Intelligent Reflecting Surface-Assisted MISO Systems

Intelligent reflecting surface (IRS) is gradually being recognized as a promising technology for improving spectral and energy efficiency of wireless systems. In this letter, we study an IRS-assisted multiple-input single-output (MISO) system where a base station (BS) with multiple antennas arranged in a uniform rectangular array (URA) serves a single-antenna user with the help of an IRS with multiple elements arranged in a URA. We consider a Rician fading model, where the non-line of sight (NLoS) components vary slowly and the line of sight (LoS) components do not change. To reduce costs for channel estimation and phase adjustment, we adopt fixed maximum-ratio transmission (MRT) at the BS, fixed phase shifts at the IRS and constant rate transmission. First, we obtain the expression of the outage probability. Then, we minimize the outage probability by optimizing the phase shifts of the IRS. Finally, we obtain the expression of the asymptotically optimal outage probability in the high signal-to-noise ratio (SNR) regime. We also characterize the impacts of several key system parameters on the optimal outage probability to reveal important design insights.