Nakagami-m Channels Research Articles

Secrecy Outage Analysis of UAV Assisted Relay and Antenna Selection for Cognitive Network Under Nakagami-${m}$ Channel

In view of the scarcity of spectrum resources in wireless communication, it is studied in this paper over the two-hop cognitive secrecy transmission scheme of decoding and forwarding (DF) unmanned aerial vehicles (UAVs) assisted relay with energy harvesting under Nakagami-m channel. It is worth noting that the terminal node is equipped with multiple antennas and the optimal antenna selection can be adopted for signal reception. Meanwhile, the UAV assisted relay uses time switching (TS) and power splitting (PS) energy harvesting techniques and adopts optimal secrecy capacity selection scheme. It is successfully derived for the exact closed form expressions of non-zero secrecy capacity probability and optimal secrecy outage probability while the eavesdropper has no channel state information (CSI). Moreover, the system asymptotic secrecy outage probability demonstrates the secrecy diversity order and secrecy diversity gains of the UAV assisted relay cognitive network under Nakagami-m channel. Furthermore, joint optimization of power splitting factor and other parameters can effectively increase the system secrecy capacity and improve the system secrecy performance. Simulation results verify the correctness of the theoretical derivation and the effectiveness of the proposed scheme, which demonstrate that the proposed algorithm outperforms the other compared schemes.

Novel multiple access for cooperative networks with nakagami-m fading: system model and performance analysis

This study considers the performances of a downlink non-orthogonal multiple access (NOMA) network over Nakagami-m fading channels. This scheme employs two hop transmission. We first examine the analytical outage probability expression for each user and then these results are verified by Monte Carlo simulations. Based upon the outage probability, the maximal throughput are obtained and analyzed under different parameters. Furthermore, the effects of Nakagami-m channel fading on the probability and throughput are investigated. The results indicate that the performance of the NOMA system is excellent as appropriate selection of simulated parameters. This analysis can be recommended for designing the NOMA systems in the future fifth-generation wireless communication.

Novel multiple access for cooperative networks with nakagami-m fading: system model and performance analysis

<p>This study considers the performances of a downlink non-orthogonal multiple access (NOMA) network over Nakagami-m fading channels. This scheme employs two hop transmission. We first examine the analytical outage probability expression for each user and then these results are verified by Monte Carlo simulations. Based upon the outage probability, the maximal throughput are obtained and analyzed under different parameters. Furthermore, the effects of Nakagami-m channel fading on the probability and throughput are investigated. The results indicate that the performance of the NOMA system is excellent as appropriate selection of simulated parameters. This analysis can be recommended for designing the NOMA systems in the future fifth-generation wireless communication.</p>

Joint power-location optimization in AF cooperative relay systems with Nakagami-m channel

Cooperative relay system (CRS) is an efficient wireless communication approach, with the advantage of creating diversity. In order to minimize the average symbol error rate (ASER) of a CRS with amplify-and-forward relaying protocol (AF-CRS) in the Nakagami-m fading channel, the optimum relay location and allocating optimal power is determined. To achieve this goal, the ASER for the AF-CRS in the Nakagami-m channel for different modulations is calculated. Then, three scenarios are considered. First, an algorithm, based on fixed point theory to determine the optimal location of the AF relay with a given power allocation for the source and relay, is proposed. Second, the problem of optimizing power allocation for different relay locations is solved. Finally, an algorithm for joint optimization of the power-location that leads to more efficient system operation, is proposed. In this paper, it is shown that the optimum power allocation and relay location is independent of the parameter m of the Nakagami channel. Also, the effect of the path-loss exponent (PLE) on the optimal relay location in the CRS, which shows that the relay should be located closer to the source in dense channels (like near-Earth environments relative to free-space), is investigated. Finally, Simulations and numerical results, which confirm the theoretical achievements, are presented.

Quasi Orthogonal Space Time Block Code Over Nakagami-m Frequency Selective Fading Channels with Simple Decoding Complexity

In this paper, a Quasi Orthogonal Space Time Coding (QOSTBC) system over Nakagami-m frequency selective fading channels is introduced. The proposed scheme is carried out for the M-QAM modulation schemes assuming imperfect channel state information at the receiver. Inter symbol interference effect introduced due to the assumption of the frequency selective fading channels is eliminated by using the Orthogonal Frequency Division Multiplexing (OFDM) technology. Through the Bit Error Rate (BER) versus Signal to Noise Ratio (SNR) simulation results under different values of both Nakagami-m parameter and channel estimation error, the validity of the proposed technique is demonstrated. The results confirm that the BER in the case of frequency selective fading is overlapped with that of flat fading. This implies that the use of OFDM technology mitigates the effect of Inter-Symbol Interference (ISI) caused by frequency selectivity in the channel. Also, the results show that as the imperfect channel estimation error increases the performance degrades.

Physical Layer Security in NOMA-Enabled Cognitive Radio Networks With Outdated Channel State Information

In this article, we investigate physical layer security (PLS) in non-orthogonal multiple access-enabled (NOMA-enabled) underlay cognitive radio networks (CRNs) with outdated channel state information (CSI). Considering the influence of outdated CSI on the interference of secondary transmitter (Alice) to primary user (PU), the constraint for the power is adopted to guarantee the quality-of-service (QoS) of PU over Nakagami-m channels. To further analyze the NOMA-enabled underlay CRNs with outdated CSI in PLS perspective, the secrecy performance is evaluated by the closed-form expressions for connection outage probability (COP), the intercept probability (IP) and effective secrecy throughput (EST). In addition, Monte Carlo simulations are provided to verify the derived analytical results. From the analytical results and simulations, it is concluded that a) with the increment of the channel parameter m, the secrecy performance of the considered networks increases in the low SNR region and decreases in the high SNR region, b) the connection performance with the outdated CSI of the interference links only reduce in the high SNR region, because the power margin factor changes significantly in this region, c) considering the impact of the constraint for the power, the secrecy performance and EST performance of the considered networks with the outdated CSI of the interference links increase in the high SNR region, d) the considered networks with NOMA scheme can achieve higher EST than that with orthogonal multiple access (OMA) scheme.

On the Energy Detection Performance of Arbitrarily Correlated Dual Antenna Receiver for Vehicular Communication

In this letter, we investigate the energy detection performance over arbitrarily correlated Nakagami-m channels under vehicle mobility. We consider that vehicle is under the protection range of the primary user. We derive the probability density function of the received signal-to-noise ratio by means of the ratio of two distributions. Next, closed-form expression for the average probability of detection is derived considering maximal ratio combining diversity for dual-antenna branches under vehicle mobility. The numerical results demonstrate that that the impact of the arbitrary correlation under vehicle mobility in terms of receiver operating characteristic. Detection performance may vary under various antenna correlation types, such as exponential or uniform. Based on the numerical results obtained, we posit that the joint effect of high-antenna correlation and mobility of vehicle can degrade detection performance with a single antenna; furthermore, dual-antenna branches can provide a remedy to the deterioration.

Signal-to-noise ratio estimation for M-QAM signals in \u03b7\u2212\u03bcand \u03ba\u2212\u03bcfading channels

In this paper, signal-to-noise ratio (SNR) estimation is carried out by the method of moments (MOM) for fading channels modeled by probability distributions η−μ and κ−μ, considering M-ary quadrature amplitude modulation (M-QAM) with constellation energy normalized to one. New expressions are presented for the SNR estimation and for the mean, variance, and normalized mean square error (NMSE) of the estimates, obtained by a statistical linearization argument. Additionally, it is shown how to obtain the SNR estimate for Nakagami-m channel from the estimation derived for the models η−μ and κ−μ. The results obtained from the analytical expressions are corroborated by simulation results and show that the MOM is a suitable alternative for scenarios in which the mathematical tractability does not suggest the application of other estimation techniques.

Joint Effects of Residual Hardware Impairments and Channel Estimation Errors on SWIPT Assisted Cooperative NOMA Networks

In this paper, we investigate the effects of residual hardware impairments (RHIs), channels estimation errors (CEEs) and imperfect successive interference cancellation (ipSIC) on the cooperative non-orthogonal multiple access (NOMA) system over Nakagami-m channels, where the amplify-and-forward (AF) relay can harvest energy from the source. The exact expressions for outage probability and ergodic sum rate are derived in closed-form. In addition, the asymptotic outage analyses in the high signal-to-noise (SNR) regime are carried out. The results show that the outage probability exists an error floor due to the existence of CEEs and compared with RHIs, CEEs have a more serious impact on the system outage performance. The close simulation results of Monte Carlo verify the accuracy of our theoretical derivation. Finally, the performance of energy efficiency is examined with RHIs, CEEs and ipSIC.

Performance analysis of two-way full-duplex relay with antenna selection under Nakagami channels

This paper focuses on a full-duplex (FD) two-way relay network with one base station (BS), one FD amplify-and-forward (AF) relay, and one user, and the BS is equipped with massive multiple-input multiple-output (MIMO) antennas. To reduce the complexity and cost of BS, the paper proposes a practical antenna selection way in BS to complete transmission in two-way FD relay networks to optimize the system performance of outage probability or bit error ratio (BER). In the proposed scheme, BS can implement transmit antenna selection (AS) based on the instantaneous channel state information (CSI), thereby improving the system performance compared to the traditional FD relay networks. Furthermore, closed-form expressions for the outage probability and average BER are derived under Nakagami-m channels. The analytical results show that the superiority of proposed scheme compared with the conventional AF relay scheme and the correctness of the theoretical analysis verified by the Monte Carlo simulations.

Probabilities of False Alarm for Vital Sign Detection on the Basis of a Doppler Radar System.

Vital detection on the basis of Doppler radars has drawn a great deal of attention from researchers because of its high potential for applications in biomedicine, surveillance, and finding people alive under debris during natural hazards. In this research, the signal-to-noise ratio (SNR) of the remote vital-sign detection system is investigated. On the basis of different types of noise, such as phase noise, Gaussian noise, leakage noise between the transmitting and receiving antennae, and so on, the SNR of the system has first been examined. Then the research has focused on the investigation of the detection and false alarm probabilities of the system when the transmission link between the human and the radar sensor system took the Nakagami-m channel model. The analytical model for the false alarm and the detection probabilities of the system have been derived. The proposed theoretical models for the SNR and detection probability match with the simulation and measurement results. These theoretical models have the potential to be used as good references for the hardware development of the vital-sign detection radar sensor system.

Cognitive Tropospheric Scatter Communication

Tropospheric scatter as a promising communication for beyond line-of-sight links between remote geographic areas, regains its predominance especially in military applications recently when considering microwave and cable systems are not feasible. In this paper, we propose cognitive troposcatter (short for tropospheric scatter) communication, which aims to improve the quality and capacity of troposcatter communication. Hybrid cognitive troposcatter communication scenarios and cognitive system architecture are established at first. Physical awareness objects including link geometry, nonhomogeneities, and meteorological conditions, are studied and then optimal working frequency has been calculated for specific link scenarios. More importantly, we investigate the potential of applying cognitive radio techniques in troposcatter communication due to the requirement of expanding services and capacity. Focusing on maximal ratio combing (MRC), we derive exact series-form expression of detection probability for diversity reception over Nakagami-m channel. Finally, we evaluate the performance of detection based on MRC techniques over fading channel. Numerical and simulation results demonstrate diversity promotes the detection performance in case of rain, low signal-to-noise ratio, and high antenna elevation.

Nakagami-m channel secrecy: a receiver assisted scheme

This paper considers the effect of an end-user assisted jamming scheme to achieve a secure transmission of information over Nakagami-m fading channel in wireless broadcast system. In this work, full duplex (FD) antenna at the legitimate receiver (LR) was introduced in a way that the LR will contribute additional noise to the system to degrade the eavesdropper's channel. The approach achieves secured transmission with improved secrecy when compared to the conventional method that artificial noise (AN) scheme is transmitted from the transmitter only. Numerical analysis and simulation results show an improvement in the secrecy performance metrics.

Nakagami-m channel secrecy: a receiver assisted scheme

Nakagami-m channel secrecy: a receiver assisted scheme

Performance of Differential-Phase OFDM Systems over Selective Multipath Fading Channels

This paper investigates the performance of differential-phase Orthogonal Frequency Division Multiplexing (OFDM) over frequency-selective multipath Nakagami-m radio fading channels. A closed form for the average signal to noise/interference ratio in the presence of the selective multipath fading channel and additive white Gaussian noise (AWGN) is derived. The results reveal that the system performance is impacted by the interference between the adjacent OFDM frames in two successive signaling intervals which is called Inter-Symbol-Interference (ISI). In addition, the system will possibly be distorted when the orthogonality between the adjacent subcarriers is ceased, creating Inter-Channel-Interference (ICI). This paper also studies the bit-error-rate (BER) performance of the differential-phase OFDM system over the Nakagami-m channel in the presence of AWGN, ISI, and ICI under different conditions and parameters. Moreover, the effect of adding the guard period and the number of subchannels on the probability of error is analyzed. The IEEE 802.11a standard parameters with 64 subcarriers and a decaying exponential power delay profile with root-mean-square value of 129 ns are used in this study. The system performance is also simulated at different guard intervals, number of OFDM subcarriers, Nakagami severity parameter values, and different numbers of possible differential phases.

Performance of mixed RF/FSO systems in exponentiated Weibull distributed channels

This paper presented the performances of asymmetric mixed radio frequency (RF)/free-space optical (FSO) system with the amplify-and-forward relaying scheme. The RF channel undergoes Nakagami-m channel, and the Exponentiated Weibull distribution is adopted for the FSO component. The mathematical formulas for cumulative distribution function (CDF), probability density function (PDF) and moment generating function (MGF) of equivalent signal-to-noise ratio (SNR) are achieved. According to the end-to-end statistical characteristics, the new analytical expressions of outage probability are obtained. Under various modulation techniques, we derive the average bit-error-rate (BER) based on the Meijer’s G function. The evaluation and simulation are provided for the system performance, and the aperture average effect is discussed as well.

Pairing and Scheduling for Large Array MIMO Using Regularized Channel Inversion Receivers Over Nakagami-m Fading

Multiple-antenna (MIMO) technology is becoming mature for wireless communications and has been incorporated into wireless broadband standards like LTE and WiFi. Basically, the more the number of antennas the transmitter/receiver is equipped with, the more the possible independent signal paths and the better the performance in terms of data rate and link reliability. Massive MIMO (also known as large-scale antenna systems, very large MIMO, hyper MIMO and full-dimension MIMO) makes a clean break with current practice through the use of a very large number of service antennas (e.g., hundreds or thousands) that are operated fully coherently and adaptively. Extra antennas help by focusing the transmission and reception of signal energy into ever-smaller regions of space. This brings huge improvements in throughput and energy efficiency, in particularly when combined with simultaneous scheduling for a large number of user terminals (e.g., tens or hundreds). This Paper focuses on the efficiency of the throughput and fairness of large MIMO. In multi-user MIMO (MU-MIMO), fewer antennas were used, so the only concern was to mitigate the interference of the users. The interference was mitigated by using zero forcing (ZF) receivers while the fairness of the system was maintained by using Rayleigh Fading channel. MU-MIMO was sufficient for only smaller number of users as the number of antennas were fixed and all the users had to be entertained within the same bandwidth. But, in Massive MIMO, along with the interference of the users, the interference of the antennas themselves is also a big concern, as, the number of antennas were increased contrary to the fixed fewer number of antennas in MU-MIMO. Rayleigh Fading channel and ZF receivers were not sufficient for increased number of users and antennas respectively. The problem of interference amongst the antennas was addressed by using regularized channel inversion receivers that increase the throughput of the system while, the fairness of the system is increased by using Nakagami-m channel.

Capacity Analysis of MIMO in Non-Uniform Nakagami Channel with Linear Receiver

ABSTRACTMultiple-input–multiple-output (MIMO) systems have emerged as a promising solution to provide high data rate wireless services in a rich scattering environment. This paper deals with the performance analysis of the MIMO system in correlated non-uniform phase distributed Nakagami-m channel with linear receiver. Authors have considered spatial diversity scheme i.e, vertical bell laboratories layered space-time (V-BLAST) systems in correlated MIMO Nakagami-m fading channels with equal power distribution among the transmitter side antennas. Also, they consider that the channel state information (CSI) is available only at the receiver. The paper presents a detailed analysis of the channel capacity in correlated and uncorrelated channel condition and validated the result with appropriate mathematical model. The effect of Doppler shift and Nakagami-m fading parameter m on the channel ergodic and outage capacity has been analyzed here.

On the Outage Performance of Reactive Relay Selection in Cooperative Cognitive Networks Over Nakagami-m Fading Channels

This paper evaluates outage performance of reactive relay selection in cognitive radio networks over Nakagami-m fading channels under consideration of imperfect channel information on both interference and transmission channels, peak transmit power constraint, long-term power constraint, interference from primary users (PUs), and direct channel between secondary source and destination. Toward this end, power allocation for secondary transmitters is first proposed to satisfy both power constraints and account for imperfect Nakagami-m channel information and interference from PUs. Then, exact closed-form outage probability representation for secondary destination is suggested to promptly assess system performance and provide useful insights into performance limits. Various results show validity of the proposed expressions, substantial system performance degradation due to imperfect channel information and interference from PUs, error floor in secondary network, performance trade-off between secondary and primary networks, and considerable performance enhancement with respect to the increase in the number of secondary relays and larger fading severity parameter.

Energy Detection with Diversity Reception

We characterize the performance of energy detector (ED) over square-law, square-law selection, and switch-and-stay diversity combining schemes. The exact average probabilities of a miss (Pm), and a false alarm (Pf) are derived in closed-form. To derive Pm for versatile Nakagami-m and Rician fading channels, a twofold approach, using the probability density function (PDF) and the moment generating function (MGF), is applied. Using the PDF method, the achievable diversity order over the Nakagami-m channel is derived. However, this method becomes intractable when analyzing Pm of the aforementioned combiners in Rician channels, but the MGF method can handle this case. Our analysis helps to quantify the performance gains of ED due to diversity reception. Theoretical derivations are verified through numerical Monte-Carlo simulation results.