Leakage rate analysis with imperfect channel state information for cooperative nonorthogonal multiple access networks

This paper investigates the imperfect channel state information that is caused by the channel estimation error and feedback delay effects on the leakage rate analysis for the cooperative nonorthogonal multiple access networks. The investigation considers a dual hop one‐/two‐way nonorthogonal multiple access‐based information exchange process with the aid of half‐/full‐duplex untrustworthy wireless relaying network for the leakage rate analysis. The channel estimation error causes system coding gain losses while the feedback delay does not have any effect on the users' outage performance at untrustworthy relay terminal in low signal‐to‐noise ratio regimes. Conversely, the channel estimation error effects become negligible while the feedback delay causes system coding gain losses on the users' outage performance at untrustworthy relay terminal in high signal‐to‐noise ratio. Results also reveal that the untrustworthy relay terminal, which is under the effect of the channel estimation error and feedback delay, is being active between and ‐  dB. Beyond ‐  dB, the untrustworthy relay terminal becomes out of order and saturates. The Monte Carlo–based simulation results are in agreement with the analytical and asymptotic derivations.     

Pilot-aided 1 × 2 and 2 × 2 space-time line code systems with transmit antenna selection

The space-time line code (STLC), which has been recently proposed in the literature, assumes fully known channel state information at the transmitter and not the receiver. However, the effective channel gain is still required at the receiver to coherently detect $M$-ary quadrature amplitude modulation ( $M$QAM) symbols. In this paper, we propose pilot-aided STLC systems, which do not require the effective channel gain at the receiver to detect the $M$QAM symbols. In order to further improve the error performance of the proposed schemes, we present the pilot-aided STLC systems with transmit antenna selection (TAS). Using a more direct and simpler approach, we derive the average symbol error probability (ASEP) of the coherent $1\times 2$ STLC systems with TAS, which represents the lower bound of the pilot-aided $1\times 2$ STLC systems with TAS. For comparison, in a similar manner, we also derive the ASEP of the coherent $2\times 2$ STLC systems without TAS, which represents the lower bound of the pilot-aided $2\times 2$ STLC systems. For pilot-aided $1\times 2$ STLC systems with TAS, the gap between the simulated symbol error rate (SER) and the derived theoretical ASEP lower bound is very small. For a given number of transmit antennas, the simulated SER and theoretical ASEP also show that the error performance of the pilot-aided $2\times 2$ STLC systems with or without TAS is superior to the pilot-aided $1\times 2$ STLC systems with TAS by at least 1.8 dB.     

On the performance of energy harvesting-assisted Nth best relay cooperative networks in Nakagami-m fading

We study the energy harvesting (EH)-assisted system model based on the performance of a dual-hop cooperative communication system that is subjected to Nakagami- $m$ fading. Through the partial relay selection method, the selection of $N$th best relay (BR) is performed among $M$ amplify and forward (AF) relays, which can harvest energy from radio frequency signals. At the receiver, the selection combining scheme is considered to select between the signals of $N$th best relaying path and the direct path. For this considered system, we compute the closed-form expressions of outage probability (OP) and the average symbol error rate (ASER) for higher order quadrature amplitude modulation (QAM) techniques, especially for rectangular QAM, cross QAM, and hexagonal QAM. Further, a new moment-generating function expression is obtained which is used to derive the ASER expression related to the generalized non-coherent modulation technique. We also give the asymptotic expression of OP to find out the diversity order. Furthermore, we study the effect of fading parameters, $N$th BR, and other factors on system behavior. Finally, we verify the derived expressions with Monte Carlo simulations.     

Generalized solution to symbol error probability integral containing over different fading models

This paper presents a generalized solution to the symbol error probability (SEP) integral containing the product of two Gaussian Q‐functions . Numerical integration technique is first used to approximate the polar form of as a sum of exponentials. This approximation is then used to derive a closed‐form solution to the related SEP integral. Due to the exponential nature of the approximation, solution to the integral is expressed in terms of moment generating function (MGF) of a fading distribution. Therefore, the solution to integral exists for all fading distributions which have well‐defined MGF. The mathematical complexity of the proposed solution is directly proportional to the complexity of MGF expression. For most of the fading models, the corresponding MGF involves power or exponential functions, which guarantees algebraic simplicity of the proposed solution. Further, this generalized solution is used to evaluate the SEP of various modulation schemes over different fading channels. Various computer simulations run in MATLAB for wide range of scenarios confirm the accuracy of the proposed approximation and solution.     

A deep learning based latency aware predictive routing model for network-on-chip architectures

Network on Chip (NoC) is an evolving platform for communications related applications, which are executed on a single silicon chip. There are several routing models in NoC architectures, but the accuracy of these models is limited, and the existing models are degraded because of over and under fitting issues. This research introduces the new deep learning-based latency aware predictive routing model for on-chip networks to route packets with better performance and power efficiency. The deep learning model used in this research is a new convolutional residual gated recurrent unit (CRGRU) with queuing theory. Moreover, the source and channel queuing delay is comprised of features to learn spatial and sequential information that improves the overall prediction accuracy. This router is modified by the intrusion of the Router States Monitor unit and the CRGRU hardware engine. The work is executed using the Xilinx platform, and the performance measures like latency and throughput are obtained by varying the network size as $4\times 4$, $8\times 8$, and $12\times 12$ and also varying the buffer space and length as $L=4,B=9$, $L=9,B=4$, and $L=14,B=3$, respectively. In addition, the squared correlation coefficient (SCC) and normalized root mean square error (NRMSE) are evaluated and compared with existing learning models to validate the proposed model.     

Exploiting W. Ellison model for seawater communication at gigahertz frequencies based on world ocean atlas data

Electromagnetic (EM) waves used to send signals under seawater are normally restricted to low frequencies () because of sudden exponential increases of attenuation () at higher . The mathematics of EM wave propagation in seawater demonstrate dependence on relative permeability (), relative permittivity (), conductivity (), and of transmission. Estimation of and based on the W. Ellison interpolation model was performed for averaged real‐time data of temperature () and salinity () from 1955 to 2012 for all oceans with latitude/longitude points and 101 depth points up to 5500 m. Estimation of parameters such as real and imaginary parts of , , , , loss tangent (tan ), propagation velocity (), phase constant (), and contributes to absorption loss () for seawater channels carried out by using normal distribution fit in the 3 GHz–40 GHz range. We also estimated total path loss () in seawater for given transmission power and antenna (dipole) gain. MATLAB is the simulation tool used for analysis.     

Performance analysis of intelligent reflecting surface-assisted mobile wireless networks subjected to generalized Gaussian noise

Different from the prior works, this paper presents the performance analysis of an intelligent reflecting surface (IRS)-assisted communication link in a static and mobile scenario impaired by Rayleigh fading and additive white generalized Gaussian noise (AWGGN). Precisely, the IRS is configured as an intelligent access point, and the mobile behavior of the nodes is characterized by the random waypoint (RWP) model. To this end, closed-form expressions of average bit error rate (BER), average channel capacity (ACC), and outage probability (OP) in both static and mobile scenarios are obtained. To gain further insight into the system performance at high signal-to-noise ratio (SNR), asymptotic expressions are obtained. Moreover, the effect of the number of reflective elements ( $N$) and the shaping parameter ( $\lambda$) on the system performance is thoroughly studied. The results indicate that introduction of IRS leads to significant improvement in the overall system performance. The derived results are corroborated with Monte Carlo simulations.     

Improved error performance of a 3/4‐Sezginer space‐time block codes

The Alamouti space‐time block code (STBC) achieves full diversity gain at a rate of 1/2. However, the Alamouti scheme does not provide multiplexing gain. The Silver code offers both diversity and multiplexing gain. It has a minimum normalization determinant of . The Golden code is another STBC that offers both diversity and multiplexing gain. The Golden code is ranked higher than the Silver code because of its lower minimum normalization determinant of , however, the golden code suffers from a high detection complexity in the modulation order of M⁴. The 3/4‐Sezginer code is another STBC, which compromises between the Alamouti scheme and the Golden code in terms of diversity gain and multiplexing gain. The 3/4‐Sezginer code achieves full diversity and half of multiplexing gain. The uncoded space‐time labeling diversity (USTLD) is a recent scheme that improves the error performance when applied to the STBC in multiple‐input multiple‐output (MIMO) systems and will be applied to the 3/4‐Sezginer STBC to improve the error performance in this paper. The theoretical error probability for both the 3/4‐Sezginer STBC and the improved system is formulated using the union bound in this paper. The theoretical error probabilities of both 16‐QAM and 64‐QAM are validated through Monte Carlo simulation. The simulation and theoretical results show that the proposed system with 4 N_R can achieve an SNR gain of 1 dB for 16‐QAM and 1.2 dB 64‐QAM at a bit error rate (BER) of 10^?6.     

Joint routing,link capacity dimensioning,and switch port optimization for dynamic traffic in optical networks

This paper considers a challenging problem: to simultaneously optimize the cost and the quality of service in opaque wavelength division multiplexing (WDM) networks. An optimization problem is proposed that takes the information including network topology, traffic between end nodes, and the target level of congestion at each link/node in WDM networks. The outputs of this problem include routing, link channel capacities, and the optimum number of switch ports locally added/dropped at all switch nodes. The total network cost is reduced to maintain a minimum congestion level on all links, which provides an efficient trade-off solution for the network design problem. The optimal information is utilized for dynamic traffic in WDM networks, which is shown to achieve the desired performance with the guaranteed quality of service in different networks. It was found that for an average link blocking probability equal to 0.015, the proposed model achieves a net channel gain in terms of wavelength channels ( ) equal to 35.72 , 39.09 , and 36.93 compared to shortest path first routing and equal to 29.41 , 37.35 , and 27.47 compared to alternate routing in three different networks.     

Multitier heterogeneous network using stochastic geometry and factorial moment approaches

The rapid growth of small cells is driving cellular network toward randomness and heterogeneity. Usually, cellular networks are modeled by placing each tier (eg, macro, pico, and relay nodes) deterministically on a grid. In such a heterogeneous cellular network, the rational approach to characterize the base stations (BSs), user, and relay locations is by using random spatial models. When calculating the metric performances such as coverage probability, these networks are idealized without consideration of interference. Therefore, interference modeling remains the key issue for the deployment of small cells. This paper developed a single and multitier cellular network model that captures the downlink heterogeneous cellular network with variable parameters such as the target signal‐to‐interference ratio (SIR), transmitted power, and deployment density. In particular, we model ‐tier transmission and compare it with a single‐tier and traditional grid model to obtain tractable coverage probability using stochastic geometry and factorial moment. The obtained results demonstrate the effectiveness and analytical tractability to study the heterogeneous performance.     

Spectrum sensing performance of wireless cognitive radio sensor network with hard-decision fusion over generalized α−μ fading channels

The analysis of spectrum sensing performance of energy detection (ED)-based wireless cognitive radio sensor network (ED-WCRSN) with hard-decision combining (HDC) is presented in this paper. Particularly, several network parameters are derived to estimate the performance of ED-WCRSN, considering channel errors, noise, and generalized $\alpha -\mu$ fading. In the considered network, first, cognitive radio sensor (CRS) senses a primary user (PU), gets sensing data, and then uses an ED to make a local binary decisions about PU's active or inactive status. In both sensing and reporting channels, the channel error probability is also taken into account. Next, HDC technique is used at control center (CC) to combine the locally obtained decisions, and a final decision about the status of the PU is made. To do so, first, the expression for the novel and analytical, which incorporates noise and $\alpha -\mu$ fading, detection probability in a CRS is derived and validated using Monte Carlo simulations in MATLAB and using an experimental setup. Then, utilizing derived mathematical expressions, closed-form expressions of an average error rate (AER), optimal numbers of CRSs, and detection thresholds under noisy and $\alpha -\mu$ fading conditions are developed. The substantial influence of channel and network factors is assessed using receiver operating characteristics (ROC), complementary ROC, and AER. Finally, the impacts of channel and network parameters on ED-WCRSN performance are explored. For numerous parameters of the considered network, the optimal values detection threshold and number of CRSs are also found.     

A methodology to benchmark flexible payload architectures in a megaconstellation use case

This paper proposes a methodology to benchmark satellite payload architectures and find the optimal trade‐offs between high flexibility and low complexity. High flexibility would enable the satellite to adapt to various distributions of user terminals on the ground and fulfill the data rate demand of these users. Besides, low complexity is required to keep satellite networks competitive in the context of emerging 5G networks. To estimate the flexibility of a payload, an indicator to characterize the non‐uniformity of user distributions is proposed. Each benchmarked payload may be characterized by a graph relating the throughput to this parameter further denoted . The payload provides the same throughput trends for different scenarios of user distributions with the same parameter. As a consequence, the average capacity of the system may be estimated by (a) calculating the probability distribution of over the orbit and (b) integrating the throughput based on this payload response. It thus results in a straightforward way for benchmarking payloads directly on an estimation of the averaged capacity, accounting for the user distribution over the earth. A simulation platform has been developed to characterize the payload throughput including the implementation of a resource allocation algorithm that accounts for constraints of various payloads. Using this definition and the developed tool, we benchmark a bent‐pipe architecture, a beam hopping architecture and a hybrid beam‐steering architecture for a LEO megaconstellation use case. The methodology showcases the interest for investigating different payload architectures depending on realistic traffic scenario analysis.     

Quantum-based exact pattern matching algorithms for biological sequences

In computational biology, desired patterns are searched in large text databases, and an exact match is preferable. Classical benchmark algorithms obtain competent solutions for pattern matching in time, whereas quantum algorithm design is based on Grover's method, which completes the search in time. This paper briefly explains existing quantum algorithms and defines their processing limitations. Our initial work overcomes existing algorithmic constraints by proposing the quantum-based combined exact (QBCE) algorithm for the pattern-matching problem to process exact patterns. Next, quantum random access memory (QRAM) processing is discussed, and based on it, we propose the QRAM processing-based exact (QPBE) pattern-matching algorithm. We show that to find all occurrences of a pattern, the best case time complexities of the QBCE and QPBE algorithms are , and the exceptional worst case is bounded by . Thus, the proposed quantum algorithms achieve computational speedup. Our work is proved mathematically and validated with simulation, and complexity analysis demonstrates that our quantum algorithms are better than existing pattern-matching methods.     

An eight-element sequentially rotated crescent-slot-coupled dielectric resonator antenna array for WIFI applications

In this communication, the author presents an eight-element sequentially rotated (SR) circularly polarized (CP) dielectric resonator antenna (DRA) for operation in the IEEE 802.11a standard. A novel resonating element composed of a crescent slot (CS) used to excite a rectangular dielectric resonator (RDR) is proposed that has two orthogonal modes ${\mathit{TE}}_{1\delta 1}^y$ and ${\mathit{TE}}_{\delta 21}^x$ as required for CP radiation. An SR series–parallel geometry is used to prototype the array feed network to allocate the array elements to symmetrical positions. The phase progression of each element was 45° along the array, and the signal magnitude was distributed evenly based on the binomial theory to enhance the antenna performance. The prototyped SR array had a size of $46\times 46\times 0.813$ mm³ and was measured and characterized in order to authenticate the design. The resonance bandwidth (S₁₁ ˂ −10 dB) was found to be 14.28% with a 3 dB axial ratio (AR) of 17.7% for right-hand CP. The gain varied from 15.71 to 16.26 dBi within the operating band. The size, gain, and impedance bandwidth of the proposed array make it a potential candidate for devices operating in the IEEE 802.11a band.     

A novel analytical model for interference estimation in CR‐enabled femtocells

Commercial, multideployed cognitive femtocell base stations (CFBSs) with cognitive capabilities are envisioned as a promising approach to meet the requirement of the higher data rate in today's wireless communications with nomadic users. However, random deployment of CFBSs results in interference between primary links, ie, the link between a macrocell base station (MBS) and macrocell user equipment (MUE), and secondary links, ie, the link between a femtocell base station (FBS) and femtocell user equipment (FUE). In this research paper, different analytical expressions for statistical measures such as cumulative distribution function of outage probability (F_out) and probability distribution function (P_out) have been proposed for the CFBS system. The fading channel for the secondary and primary links is taken as mixture gamma (MG) and Rayleigh distribution, respectively. It should be noticed that MG fading is one of the most generic fading channels and has not been included for analysis of the CFBS system to date. In addition, this paper presents average detection probability ( ) for cognitive radio (CR)–enabled femtocells or the CFBS system. The numerical analysis presents the effects of various parameters such as spatial density of CFBS nodes (λ), interference tolerance threshold (β_th), and transmitting power of MBS (p) and fading parameters of the channel on F_out, P_out, and . Also, the numerical analysis shows perfect agreement with the theoretical background .     

Outage analysis of SWIPT‐based full‐duplex cognitive NOMA downlink system over Nakagami‐m fading channels

Cognitive nonorthogonal multiple access (NOMA) technique allows multiple users to share the same time and same frequency resources to fulfil the reliability and spectral efficiency requirements of 5G communication standards. In this paper, simultaneous wireless information and power transfer (SWIPT)–based full‐duplex cognitive NOMA downlink system is proposed. In this system, secondary source (SS) serves as a relay to far primary user as there is no direct link from the primary source. NOMA technique is used at SS to transmit information to far primary user and secondary user. The time switching mechanism is adopted at SS for harvesting energy and information decoding. Analytical closed‐form expressions are derived for the outage probabilities of both primary and secondary users. Outage analysis is carried out in Nakagami‐ fading environment in the presence of self‐interference at SS. In addition to that, the optimal harvesting time to maximize the instantaneous throughput of the far primary user is also derived. Numerical results are plotted to validate the derived expressions. It is inferred that the outage probability of the proposed system depends on the fading environment, harvesting parameters, and self‐interference at SS.     

Design and investigations on a compact,UWB, monopole antenna with reconfigurable band notches for 5.2/5.8 GHz WLAN and 5.5 GHz Wi‐MAX bands

This article represents a microstrip line–fed novel circular monopole antenna with ultra‐wideband (UWB) characteristics. The compact antenna provides reconfigurable notches at WLAN (5.2/5.8 GHz) and Wi‐MAX (5.5 GHz) frequency bands. The band rejection is achieved by etching an open‐ended L‐shaped slot in the ground plane, which effectively mitigates the interference between WLAN, Wi‐MAX, and UWB systems with an effective patch area of 36.26%. The proposed antenna operates from 3.05 to 12.11 GHz with VSWR 2 except at stopband (3.89‐5.93 GHz) to filter the WLAN and Wi‐MAX signals. The simulated return loss, gain, and radiation pattern of the proposed antenna has been experimentally verified with the fabricated one which holds a good agreement.     

Exact analysis of maximal ratio transmission-based decode-and-forward relaying with arbitrary number of co-channel interferers

This paper analyzes the performance of maximal ratio transmission (MRT)-based cooperative communication system over Nakagami- $m$ fading channels in the existence of co-channel interference which is becoming a critical factor since the limited spectrum bands are shared by growing number of devices. In particular, a dual-hop decode-and-forward relaying is investigated when multiple interferers affect the relay and the destination nodes. Firstly, the cumulative distribution function (CDF) and the probability density function (PDF) of the signal-to-interference-plus-noise ratio (SINR) are derived. Then, the exact expressions for the outage probability (OP), average bit error probability (ABEP), and ergodic capacity are obtained. Furthermore, asymptotic expressions for OP and ABEP are provided to find the diversity and coding gains. Finally, simulation results are presented to validate our theoretical findings.     

Path loss model based on exponential water cycle algorithm for wireless sensor network

Wireless sensor networks (WSNs) are frequently employed in the agriculture field to improve the quality and crop yield. The WSN might reduce the quality of the communication link because of the absorption, dispersion, and attenuation through the leaves of plants. Therefore, estimating the path loss due to signal attenuation before WSN deployment is crucial for the smooth operation of the network. In this research paper, three innovative path loss models are defined based on the MATLAB curve fitting tool: polynomial water cycle (PWC), exponential water cycle (EWC), and Gaussian water cycle (GWC) algorithm. Here, the path loss between the router node and the coordinator node is modeled on the basis of the received signal strength indicator (RSSI) and time of arrival (TOA) measurements in a sugarcane field. The correlation coefficient between the RSSI measurement and the distance must be increased to create a precise path loss model. This paper integrates the exponential, polynomial, and Gaussian functions with the water cycle algorithm (WCA) to evaluate the optimal coefficients that would lead to precise path loss models. The performance of the proposed models that determines the optimum linear fit between RSSI and distance is validated using the correction coefficient $R^2$. The results show that the proposed path loss model is superior to existing path loss models. The correlation coefficient $R^2$ of the proposed EWC model is 0.9993, whereas the existing PE-PSO, LNSM, and PSO-Exponential models yield 0.98, 0.87, and 0.93, respectively. Also, the proposed models attain the best mean absolute error (MAE) of 0.2187, 0.2951, and 0.3457 dBm for EWC, PWC, and GWC algorithms, respectively.     

ASER analysis of generalized hexagonal QAM schemes for NOMA systems over Nakagami-m fading channels

To achieve high data rates expected from beyond 5G communications, higher-order modulation techniques have been explored. The energy-efficient modulation technique with a high data rate has encouraged researches towards an optimum two-dimensional hexagonal-shaped constellation, namely, hexagonal quadrature amplitude modulation (HQAM). Thus, in this work, we analyze the average symbol error rate (ASER) of HQAM schemes by considering a two-user nonorthogonal multiple access (NOMA) pair. Closed-form expressions for ASER of HQAM schemes for users are derived over generalized Nakagami- $m$ fading channels. Further, for the HQAM constellation feasibility in two-user downlink NOMA systems, the power allocation criterion for the users is presented. Furthermore, the impact of modulation order of the users over the systems ASER analysis is investigated and valuable insights are drawn.