Fading Channel Model Research Articles

Performance Analysis of Physical-Layer Security Over Fluctuating Beckmann Fading Channels

In this paper, we analyse the performance of physical layer security over Fluctuating Beckmann (FB) fading channel, which is an extended model of both the κ - μ shadowed and the classical Beckmann distributions. Specifically, the average secrecy capacity (ASC), secure outage probability (SOP), the lower bound of SOP (SOPL), and the probability of strictly positive secrecy capacity (SPSC) are derived using two different values of the fading parameters, namely, m and μ which represent the multipath and shadowing severity impacts, respectively. Firstly, when the fading parameters are arbitrary values, the performance metrics are derived in exact expressions in terms of the extended generalised bivariate Fox's H-function (EGBFHF) that has been widely implemented in the open literature. In the second case, to obtain simple mathematically tractable expressions in terms of analytic functions as well as to gain more insight on the behaviour of the physical layer security over Fluctuating Beckmann fading channel models, m and μ are assumed to be integer and even numbers, respectively. In addition, the asymptotic behaviour for all the studied performance metrics has been provided. The numerical results of this analysis are verified via Monte Carlo simulations.

Performance Analysis of Full-Duplex Vehicle Relay-Based Selection in Dense Multi-Lane Highways

This paper considers a dual-hop vehicle-to-vehicle (V2V) communication system equipped with full-duplex relays (FDRs) in the millimeter-wave networks. The performance of this network is studied in a dense multi-lane highway considering cooperative best vehicular relay selection strategy. In fact, two different FDR schemes are analyzed for the given network. In the first scheme that is called self-interference (SI) vehicle relaying selection, the FDR models the source-relay and the relay-relay links by one channel state information (CSI) coefficient (i.e., a single channel estimation of the two links), while in the second scheme that is called individual SI vehicle relaying selection, the CSI of the source-relay and the relay-relay links are estimated separately. Moreover, relay-destination link is modeled by one CSI coefficient in both aforementioned schemes. Dissimilar to traditional V2V schemes where either line-of-sight (LOS) or non-line-of-sight (NLOS) propagation is considered, and the effect of the blockage on V2V communications is not taken into account when analyzing the performance, in this paper, we propose a probabilistic model capturing the occurrences of LOS and NLOS propagations, which depend on the movement of the vehicles between the central and adjacent lanes. Thus, the movement of the vehicles between any two adjacent lanes is assumed to take place independently and is deemed to be according to the Poisson distribution. This vehicle movement model considers the blockage between the source and destination links. In this vein, a LOS link is considered available when the center lane is clear of vehicles between the source and destination nodes, and an NLOS link is assumed otherwise. Furthermore, a Nakagami-m fading channel model is considered due to its excellent representation of the V2V communication environment. The LOS/NLOS probabilities combined together with the probability of blockage are used to analyze the system performance. The cumulative density function expression of the signal-to-interference-plus-noise ratio at the relay is derived for both relaying schemes. Moreover, the lower bound expressions of the end-to-end outage probabilities are developed and used to express throughput. Finally, the theoretical results postulated and presented here are verified by the numerical simulation for a variety of parameters.

Block-Circulant Inverse Orthogonal Jacket Matrices and Its Applications to the Kronecker MIMO Channel

This paper presents a note on the block-circulant generalized Hadamard matrices, which is called inverse orthogonal Jacket matrices of orders $$N=2p, 4p, 4^kp, np$$ , where k is a positive integer for the Kronecker MIMO channel. The class of block Toeplitz circulant Jacket matrices not only have many properties of the circulant Hadamard conjecture but also have the construction of block-circulant, which can be easily applied to fast algorithms for decomposition. The matrix decomposition is with the form of the products of block identity $$I_2$$ matrix and block Hadamard $$H_2$$ matrix. In this paper, a block fading channel model is used, where the channel is constant during a transmission block and varies independently between transmission blocks. The proposed block-circulant Jacket matrices can also achieve about 3db gain in high SNR regime with MIMO channel. This algorithm for realizing these transforms can be applied to the Kronecker MIMO channel.

New Deterministic and Stochastic Simulation Models for UAV-MIMO Ricean Fading Channels

For the practical simulation and performance evaluation of unmanned aerial vehicle (UAV) multiple-input multiple-output (MIMO) Ricean fading channels, it is desirable to develop accurate UAV-MIMO channel simulation models for more realistic scenarios of non-isotropic scattering. In this study, using a two-cylinder reference model to describe the distribution of scatterers, we propose new deterministic and stochastic simulation models. Analytical and numerical results indicate that both simulation models provide good approximations to the desired statistical properties of the reference model, and the stochastic simulation model results in a better performance under comparable computational complexity.

Statistical Characterization of Second-Order Scattering Fading Channels

We present a new approach to the statistical characterization of the second-order scattering fading (SOSF) channel model, which greatly simplifies its analysis. Exploiting the unadvertised fact that the SOSF channel can be seen as a continuous mixture of Rician fading channels, we obtain expressions for its probability density function and cumulative density function that are numerically better-behaved than those available in the literature. Our approach allows for obtaining new results for the SOSF model, such as a closed-form expression for its moment-generating function, as well as the characterization of the average channel capacity. Relevantly, and somehow counterintuitively, we observe that in the presence of a strong line-of-sight (LOS) component, the channel capacity of a LOS plus double-Rayleigh scattered diffuse component is larger than its LOS plus Rayleigh (i.e., Rician-like) counterpart.

3D Modeling and Analysis of the Space–Time Correlation for 5G Millimeter Wave MIMO Channels

The deployment of millimeter waves (mmW) in 5G mobile networks is considered as a challenging issue due to the lack of knowledge regarding the propagation of mmW in such multipath fading environments. Therefore, the analysis and modeling of such mobile fading channels is required. In this paper, we investigate the space–time correlation functions for multiple-input multiple-output (MIMO) channels in mmW frequency bands. We develop a 3-D geometry-based channel model for Rician channel to overcome the multipath fading. Such a model is able to provide a realistic channel propagation with multiple antenna elements surrounded by a scattering environment. We derive the space–time correlation functions for the scattering environments in terms of the different system parameters of the MIMO fading channel. We present the numerical evaluations to study the influence of the system parameters such as normalized time delay, vertical and horizontal antenna polarization, and separation between antenna elements on the performance of the space–time correlation functions.

A channel-aware expected energy consumption minimization strategy in wireless networks

With the rapid development of wireless network technology, energy saving has become a very important topic to build a green network in wireless networks. Due to the time-varying characteristics of the channel, it is possible to obtain a higher utilization for energy by using the channel with good state in wireless communications. From the view of the data transmission energy consumption of the whole wireless network, this paper proposes an expected energy consumption minimization strategy (E2CMS) for data transmission based on the optimal stopping theory. Considering the maximum transmission delay and a given receiving power, E2CMS delays data to transmit until the best expected channel state is detected. In order to solve the problem, firstly, we construct an energy consumption minimization problem with quality of service constraints. Then, we prove that E2CMS is a pure threshold strategy by the optimal stopping theory and obtain the power threshold by solving a fixed-point equation using backward induction. Finally, simulations are performed in a typical small-scale fading channel model. E2CMS is compared with a variety of different transmission scheduling strategies. The results show that E2CMS has lower average energy consumption for per unit data and significantly improves the network performance.

Performance analysis of physical layer security over α-η-κ-μ fading channels

In this paper, we consider the secure data transmission over α-η-κ-μ fading channels, which are recently proposed to encompass nearly all the well-known statistical models adopted in the literature. In particular, we address the secrecy performance in terms of the average secrecy capacity (ASC) and the secrecy outage probability (SOP), for which novel analytical expressions are derived. Simulation results verify the analysis and demonstrate the impact of the physical parameters on the secrecy performance of this new channel fading model.

Sliced Spectrum Sensing—A Channel Condition Aware Sensing Technique for Cognitive Radio Networks

Cognitive radio technology, which helps to alleviate spectrum scarcity problem, plays an important role in future wireless communication systems. Spectrum sensing is the key technique of cognitive radio. The upcoming fifth generation (5G) communications need to deal with fast time-varying channels (i.e., channel state is non-static within a sensing window), while existing sensing methods are based mainly on conventional quasi-static channels. Consequently, traditional sensing methods may not work well in 5G communications. This paper aims to propose a sliced sensing technique, which can support 5G cognitive radio applications working in fast time-varying channels. We analyze the impact of non-static channels on the performance of traditional sensing methods and disclose a negative factor, i.e., out-of-phase feature distortion effect. Accordingly, we propose a sliced spectrum sensing scheme and probe its feasibility via several relevant trials. Based on the aforementioned works, a complete version of the sliced sensing technique is designed, which can adapt to channel variation and choose the optimal slicing strategy. Simulation results manifest that the sliced sensing technique outperforms traditional sensing methods in both Rayleigh fading and 3GPP spatial channel models.

Energy efficient resource matching algorithm for multi-homing services in dynamic wireless environment

This paper investigates the matching problem between radio resources and multi-homing services in a dynamic heterogeneous wireless environment. A mobile terminal with a multi-homing service simultaneously transmits data to multiple radio access networks using multiple air interfaces. This paper proposes an energy-efficient resource matching algorithm to statistically guarantee the service rate requirements of each user with the lowest power consumption. First, according to the concept of resource matching and the dynamic characteristics of wireless channels, this paper defines two matching probability metrics and subsequently selects the most appropriate metric to build a resource matching model to realize the maximum energy efficiency of each user while meeting the statistical guarantee constraints. In particular, the Rayleigh fading channel model is introduced in this paper to accurately reflect the dynamics of the wireless channel, and a complete expression of the matching probability metric is deduced. Second, according to the optimal solution characteristics of the optimization model, the original problem is decomposed into the inner power minimization problem and the outer matching probability maximization problem, and the convex optimization and the equality constrained optimization are separately used to solve the problem. Hence, the two-layer distributed solution algorithm is proposed. In particular, this paper conducts rigorous mathematical analyses on the convergence, optimality and complexity of the algorithm and constructs an improved resource matching model by relaxing the statistical guarantee parameters in the case of no solution to the model. Finally, the simulation results show that this algorithm has better performance than the three existing resource matching algorithms, can achieve lower user power consumption, and can realize the goal of the best match between the network resources and service requirements in a dynamic environment.

Performance assessment of correlated Rayleigh‐inverse Gaussian fading channel over distributed MIMO systems with ZF detectors

Composite fading channel modelling of terrestrial wireless propagation is crucial for the design of communication system and its performance analysis. In this study, a systematic characterisation of Rayleigh-inverse Gaussian (RIG) distribution is provided for modelling the channel of distributed multiple-input multiple-output (MIMO) systems with zero-forcing (ZF) receiver in the presence of transmit antenna correlation. At the outset, the closed-form expression for probability density function of instantaneous signal-to-noise ratio (SNR) is derived followed by its associated moments and cumulative density function. In the subsequent analysis, exact closed-form analytical expression of ergodic capacity with its bounds are derived and their asymptotic expressions are obtained in high and low SNR regime. Then the closed-form expressions are deduced for average symbol error rate (ASER) and outage probability (OP). Additionally, the authors propose to formulate simplified expressions for asymptotic ASER as well as OP and assess their approximation accuracy. Numerical results are presented to compare the performance of RIG model with the existing generic models and illustrate that RIG is superior in terms of ergodic capacity, ASER and OP. Finally, the derived analytical expressions are validated through Monte Carlo simulations which demonstrate the effectiveness of RIG model in the diverse environmental scenario for various system and channel parameters.

A General 3-D Non-Stationary 5G Wireless Channel Model

A novel unified framework of geometry-based stochastic models for the fifth generation (5G) wireless communication systems is proposed in this paper. The proposed general 5G channel model aims at capturing small-scale fading channel characteristics of key 5G communication scenarios, such as massive multiple-input multiple-output, high-speed train, vehicle-to-vehicle, and millimeter wave communications. It is a 3-D non-stationary channel model based on the WINNER II and Saleh-Valenzuela channel models considering array-time cluster evolution. Moreover, it can easily be reduced to various simplified channel models by properly adjusting model parameters. Statistical properties of the proposed general 5G small-scale fading channel model are investigated to demonstrate its capability of capturing channel characteristics of various scenarios, with excellent fitting to some corresponding channel measurements.

Asymptotic Performance Analysis of the $k$th Best Link Selection Over Wireless Fading Channels: An Extreme Value Theory Approach

We consider a general selection-diversity scheme in which the kth best link is selected from a number of links. We use extreme value theory to derive simple closed-form asymptotic expressions for the average throughput, effective throughput, and average bit error probability for the kth best link over various channel models that are widely used to characterize fading in wireless communication systems. As an application example, we consider the Weibull fading channel model and verify the accuracy of the derived asymptotic expressions through Monte Carlo simulations.

Energy-Efficient Data Collection in UAV Enabled Wireless Sensor Network

In wireless sensor networks, utilizing the unmanned aerial vehicle (UAV) as a mobile data collector for the sensor nodes (SNs) is an energy-efficient technique to prolong the network lifetime. In this letter, considering a general fading channel model for the SN-UAV links, we jointly optimize the SNs’ wake-up schedule and UAV’s trajectory to minimize the maximum energy consumption of all SNs, while ensuring that the required amount of data is collected reliably from each SN. We formulate our design as a mixed-integer non-convex optimization problem. By applying the successive convex optimization technique, an efficient iterative algorithm is proposed to find a sub-optimal solution. Numerical results show that the proposed scheme achieves significant network energy saving as compared to benchmark schemes.

Generalized MGF based analysis of line-of-sight plus scatter fading model and its applications to MIMO-OFDM systems

In this paper, we analyze a newly introduced fading channel model that consists of several specular and diffused scatter components. This model unifies the non-central chi, generalized Ricean and κ – μ models into a single fading model. A closed form expression for the generalized moment generating function (MGF) for this model is derived. This novel result acts as a base for calculating various other performance metrics of communication systems like nth moment of signal to noise ratio (SNR), amount of fading (AF) and outage probability. We also derive closed form expressions for performance of energy detection in Single input Single Output (SISO) systems as well as in the case of diversity combining. This includes probability of detection, probability of false alarm and the area under receiver operating characteristic (ROC) curve. Further, closed form expressions of average bit error rate (ABER) have been derived for SISO and Multiple Input Multiple Output (MIMO) based Orthogonal Frequency Division Multiplexing (OFDM) system over fading channel using MGF approach. The results obtained from derived expressions are verified with the help of benchmark results and Monte Carlo simulations.

Distributed Power Allocation for Multi-Flow Carrier Aggregation in Heterogeneous Cognitive Cellular Networks

In this paper, we study distributed power allocation for multiflow carrier aggregation in cognitive cellular networks. Our approach differs from the conventional water filling (WF) algorithm since we deal with heterogeneous fading channels, wherein all of the Lagrange multipliers are not handled equally over the heterogeneous cells. The distributed power control solution is carried out over heterogeneous fading channels that are considered nonidentically distributed Nakagami- $m$ fading channels. We first formulate the optimization problem, and we then solve it using the alternating direction method of multipliers (ADMM), which allows the required decomposition for each channel and the required statistical learning among the different subproblem solutions. We also provide comparison with the dual decomposition method and WF solutions considered as solutions without cognition. Simulation results highlight the performance gain of ADMM in terms of the number of iterations. Furthermore, we provide a multiuser application scenario, where the analysis on the fading channel model with Nakagami- $m$ distribution is carried out. We distinguish into the synchronous and the asynchronous ADMM implementations tackling the asynchronous user updates that can be found in a heterogeneous network deployment. The simulation results are obtained to highlight the impact of the partial barrier and the bounded delay in the asynchronous use case.

New closed-form expressions for SNR estimates of Nakagami fading channels by the method of moments

Method of moments has been a parameter estimation technique appropriate to calculate signal-to-noise ratio (SNR) estimates in fading channel models in which an optimal technique like maximum likelihood estimation is not mathematically tractable. In this article, the ratio of the second moment squared to the fourth moment of the received signal envelope is considered to calculate an exact expression for the SNR estimate in Nakagami-m fading channel for M-QAM and $$\theta $$ -MQAM modulations as well as expressions to evaluate the variance and the mean of the estimate. The paper presents two useful contributions for SNR estimation theory on Nakagami fading. Besides the exact algebraic expression for the estimate for a generalized QAM modulation scheme, its performance is evaluated through a statistical linearization argument.

Optimal Power Control and Scheduling for Real-Time and Non-Real-Time Data

We consider a joint scheduling-and-power-allocation problem of a downlink cellular system. The system consists of two groups of users: real-time (RT) and non-real-time (NRT) users. Given an average power constraint on the base station, the problem is to find an algorithm that satisfies the RT hard deadline constraint and NRT queue stability constraint. We propose two sum-rate-maximizing algorithms that satisfy these constraints as well as achieving the system's capacity region. In both algorithms, the power allocation policy has a closed-form expression for the two groups of users. However, interestingly, the power policy of the RT users, which we call the Lambert-power policy, differs in structure from the water-filling policy for the NRT users. The first algorithm is optimal for the on–off channel model with a polynomial-time scheduling complexity in the number of RT users. The second, on the other hand, works for any channel fading model, which is shown through simulations to have an average complexity that is close to linear. We also show the superiority of the proposed algorithms over existing approaches using extensive simulations.

Multiple antenna channel characterisation for wearable devices in an indoor stairwell environment

Any building with more than one floor will have stairwells of some form, yet this area is often neglected in channel characterisation studies. The authors present fading channel models and examine attainable spatial diversity gains at 90% signal reliability for an off-body multiple-antenna system at frequencies of 3, 4, and 5 GHz in an indoor stairwell. Additionally, they investigate received power, mutual coupling and channel cross-correlation, signal combining modelling, and antenna spatial diversity; the authors believe this is a valuable advancement beyond current knowledge to understand wearable multiple-input multiple-output technology in stairwell environments. Results reveal that two-branch spatial diversity techniques offer signal gains over individual single channels in the range of 1.7-3.3 dB for line of sight (LOS) and 1.8-3.4 dB for non-LOS (NLOS) for each of the three investigated frequencies, while three-channel diversity combining appears to offer no significant additional gain over the two-branch combinations. Furthermore, for NLOS cases the best-fit statistical distribution channel models were found to change when spatial diversity was utilised; this highlights mitigated channel fading and increased signal reliability.

A Glider-Assisted Link Disruption Restoration Mechanism in Underwater Acoustic Sensor Networks.

Underwater acoustic sensor networks (UASNs) have become a hot research topic. In UASNs, nodes can be affected by ocean currents and external forces, which could result in sudden link disruption. Therefore, designing a flexible and efficient link disruption restoration mechanism to ensure the network connectivity is a challenge. In the paper, we propose a glider-assisted restoration mechanism which includes link disruption recognition and related link restoring mechanism. In the link disruption recognition mechanism, the cluster heads collect the link disruption information and then schedule gliders acting as relay nodes to restore the disrupted link. Considering the glider’s sawtooth motion, we design a relay location optimization algorithm with a consideration of both the glider’s trajectory and acoustic channel attenuation model. The utility function is established by minimizing the channel attenuation and the optimal location of glider is solved by a multiplier method. The glider-assisted restoration mechanism can greatly improve the packet delivery rate and reduce the communication energy consumption and it is more general for the restoration of different link disruption scenarios. The simulation results show that glider-assisted restoration mechanism can improve the delivery rate of data packets by 15–33% compared with cooperative opportunistic routing (OVAR), the hop-by-hop vector-based forwarding (HH-VBF) and the vector based forward (VBF) methods, and reduce communication energy consumption by 20–58% for a typical network’s setting.