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By figuring out the best numbers for the inductor, capacitor, and duty cycle of the boost converter, this method makes it possible to match the PV system to the configuration of the DC/AC converter. The suggested numerical antenna model shows good agreement with the performance of the built antenna prototype within the human muscle-mimicking liquid phantom. This paper "Multi -objective Naked Mole -Rat Algorithm for UWB Antenna Design", introduces a novel multi-objective naked mole-rat (MONMR) algorithm for the optimization of two printed monopole patch antenna structures for ultrawideband (UWB) applications. In "Improved Switched-Capacitor Switched-Inductor Z-source Inverter for Increasing Boost Factor and Decreasing Voltage Capacitors Stress", the authors uses a switched-inductor Z-source inverter to improve a switched-capacitor inductor ZSI. [Extracted from the article]

The second paper, titled "Design and Analysis of Zeta Converter for Power Factor Correction using Cascade PSO-GSA Tuned PI and Reduced-Order SMC" describes a single-phase power factor correction method employing a DCDC Zeta converter in continuous conduction mode.To increase converter performance, it presents a non-linear cascade control of particle swarm optimization-gravitational search algorithm (PSO-GSA) tuned proportional-integral and sliding mode controller in outer and inner loops. In particular, an optimisation framework is developed that accounts for several processes, including data gathering from various sources, KPI description, and the optimisation procedure itself. Wind farm plan optimization or WFLOP, is a difficult optimisation problem with many constraints. Heuristic optimisation techniques outperformed standard methods in the study. [Extracted from the article]

This paper focuses on symbol detection for a multi‐user single‐input multiple‐output (MU‐SIMO) uplink using supervised machine learning techniques. An extreme learning machine (ELM) is chosen as the equalizer at the receiver end due to its super‐fast learning ability and minimum training error. To tune the parameters, a pilot based online training for an ELM network is proposed, and those parameters are further used to detect the unknown transmitted symbols. Conventionally, the channel matrix is estimated using known pilot symbols explicitly and then the transmitted symbol is recovered using a linear equalizer. Here, instead of directly estimating the channel coefficients, the symbols are detected using an ELM based direct equalizer followed by a hard decision rule. To reduce the pilot requirement of the proposed model, a method is discussed where the channel is estimated using a small number of pilot symbols and the ELM network is trained using a separate training dataset along with the channel estimate. Furthermore, the performance comparison between the proposed ELM based equalizers, linear equalizers, and nonlinear detection techniques is shown. [ABSTRACT FROM AUTHOR]

This paper investigates the channel capacity of coherent reception with antenna diversity in Rayleigh fading using asymmetric constellations, such as nonbinary two-sided amplitude-shift keying (ASK) and quadrature amplitude modulation (QAM) with ≥ 8 levels. Due to the asymmetries, the capacity achieving input or a priori probability distributions deviate from uniformity. To perform the investigation, an analytical expression for the mutual information, in terms of an integral over a single variable, between the input (transmitted symbol) and the output (received signal vector comprising signals at receive antennas), is derived. For two-sided ASK, 8-QAM with cross constellation, and 16-QAM, analytical closed form expressions for the high and low signal-to-noise (SNR) approximations, respectively, of the capacity achieving input probability distribution, the capacity, and the relative gain in mutual information (between using the uniform and the capacity achieving input probability distributions) are obtained. Numerical results show that at low SNRs, the use of the capacity achieving nonuniform input probability distribution offers significant advantage over the use of the uniform input probability distribution, while at high SNRs, this advantage is significant only for configurations with one receive antenna. Furthermore, the high and low SNR approximations are shown to be reasonably accurate. [ABSTRACT FROM AUTHOR]

A receive diversity power line communication (PLC) system subject to correlated multipath channel fading and corrupted by additive Nakagami- $m$ background noise is considered. The optimal receiver employing a 4-ary imbalanced-phase-amplitude modulation (I-PAM) scheme for data transmission is obtained, using which closed form expressions for the symbol error probability (SEP) in the union bound sense and the SEP in the asymptotic sense at high signal-to-noise ratio (SNR) are derived. The diversity order of the system is found to be independent of the shape parameter of the additive noise. Furthermore, the optimal 4-ary I-PAM constellation minimizing the SEP at lower SNR values is computed numerically. The optimal 4-ary I-PAM constellation is found to be elliptical in shape as opposed to the traditional circular QPSK constellation generally employed in wireless communication systems. The effects of the correlation among the multipath channel gains and the shape parameter of the noise on the optimality of the considered constellation are also presented via numerical studies. [ABSTRACT FROM AUTHOR]

An $N$ -branch receive diversity power line communication (PLC) system subject to Rayleigh fading and corrupted by additive Nakagami- $m$ background noise is considered. A suboptimal maximal-ratio-combining (MRC), an optimal diversity combining, and a Gauss-optimal receiver are proposed for the PLC system. A closed form expression for the exact symbol error probability (SEP) and a union bound SEP expression are obtained for the proposed MRC and Gauss-optimal receivers, respectively, using a characteristic function (c.f.) approach for the system employing $M$ -ary phase-shift keying (MPSK) at the transmitter, conditioned to $mN$ being an integer. The asymptotic expression for the SEP obtained for the MRC receiver at high signal-to-noise (SNR) demonstrates that the diversity order of the system is independent of the shape parameter $m$ of the additive noise which is identical to the diversity order of the optimal and the Gauss-optimal receivers. Further, numerical studies justify the advantages of employing receive diversity to achieve superior SEP performance. The effect of increasing the diversity branches on the PLC system performance with varying $m$ and the power efficiency of the PLC system are also presented. [ABSTRACT FROM AUTHOR]

The current issue of the IETE Journal of Research contains a variety of articles covering topics in communications, electromagnetics, computers and computing, control engineering, electronic circuits, devices and components, instrumentation and measurement, medical electronics, and power electronics. The articles provide research studies, methodologies, and findings related to specific topics within these fields. The aim of the articles is to provide valuable insights for readers and researchers in the academic community. [Extracted from the article]

A noncoherent diversity detection power line communication (PLC) system employing multi-level amplitude-shift keying (ASK) modulation in the presence of Middleton Class-A impulsive noise is considered. Hermite numerical integration technique is used iteratively to obtain the statistics of the decision variable of an asymptotically optimal detector, which is utilized to derive series expressions for the symbol error probability (SEP). Numerical optimization of the ASK levels is done to achieve the minimum SEP, which results in the optimal solution being close to the equally spaced ASK constellation. The asymptotic optimality of the proposed detector is validated by the SEP variation with the impulsive index of the noise. [ABSTRACT FROM AUTHOR]

We consider two low-complexity receivers, namely, the energy detection (ED) receiver and the weighted envelope detection (WENVD) receiver, employing receive diversity, operating in flat Rayleigh fading with multi-level amplitude-shift keying, and having only channel magnitude information, that is, knowledge of the magnitudes of the fading gains of the receive diversity branches. A closed form expression for the approximate symbol error probability (SEP) of the WENVD receiver for high signal-to-noise ratio (SNR) is derived. Furthermore, analytical results on the optimization of the transmit symbol amplitude levels to minimize the SEP subject to a total energy constraint for high SNR and large number of receive diversity branches for both the ED and the WENVD receivers are presented. The performance improvement obtained by using these optimal levels over using symbol amplitude levels with equal spacing, that is, in arithmetic progression, for both the receivers is shown through numerical results. [ABSTRACT FROM AUTHOR]

The IETE Journal of Research's first issue of Volume 70 covers a wide range of topics in communications, electromagnetics, opto-electronics, computers and computing, control engineering, electronic circuits, devices and components, instrumentation and measurement, medical electronics, and power electronics. The articles in this issue discuss various subjects, including improved network performance in wireless sensor networks, machine learning-based classification of cervical cancer, optimal energy reduction in 5G communication systems, and secure data transmission in the Internet of Things. The issue also includes papers on photonic sensors, detection of diabetic retinopathy, optimisation models for home health care scheduling and wind-integrated power systems, and efficient task scheduling in cloud computing environments. One research paper introduces a smartwatch-based machine learning model for monitoring epilepsy and detecting seizures, achieving a high accuracy of 99.40% in cross-validation. The document provides a summary of articles published in the journal, with authors who are experts in their fields and provide experimental findings and simulations to support their research. [Extracted from the article]

The current issue of the IETE Journal of Research (Volume 69 Number 12, December 2023) contains seventy articles covering various fields of technology and engineering. These articles discuss topics such as error rate analysis, antenna development, optical DEMUX, computer science, and engineering. Each paper presents a unique study or proposal, highlighting methodologies, techniques, and findings. The articles cover a wide range of topics, including IoT security, keyphrase extraction, deep learning, object detection, emotion recognition, insulin dose prediction, antenna array synthesis, cardiac MRI segmentation, fire detection systems, fault detection in rolling bearings, medical image processing, and optimization techniques for photovoltaic systems. The authors of these articles are experts in their respective fields and have made significant contributions to their areas of study. [Extracted from the article]

The November 2023 issue of the IETE Journal of Research features 70 articles covering a wide range of topics in communications, electromagnetics, opto-electronics, computers and computing, control engineering, electronic circuits, devices and components, instrumentation and measurement, medical electronics, and power electronics. The publication committee has announced that certain areas will be excluded from future issues starting in January 2024. The articles in this issue cover topics such as bidirectional RoF systems, double-link failure protection, downlink NOMA transmission protocols, joint antenna and user scheduling, coplanar waveguide antennas, low-cost high-gain antennas, body-centric communication links, circularly polarized wearable antennas, and more. The articles provide valuable insights and information for researchers and practitioners in the field of electronics and control engineering. [Extracted from the article]

In this paper, we propose a new relaying scheme, referred to as priority-based max-link relay selection, for buffer-aided decode-and-forward cooperative networks. We give the first priority to the relay buffers having status full, the second priority to the relay buffers having status empty, and the third priority to the relay buffers having status neither full nor empty. The best relay node is selected corresponding to the link having the highest channel gain among the links within a priority class. By adopting a Markov chain approach to analyze the state transition matrix that models the evolution of the buffers status, we derive analytical expressions for the outage probability and the average bit error rate. Analytical expressions for the steady-state probability vector are also obtained, and through these expressions, it is shown that states with the same probabilities can be grouped, thus reducing the size of the state transition matrix. We propose a general state-grouping-based method to obtain the reduced state transition matrix, which in turn reduces the computational complexity in obtaining the steady-state distribution. Our analytical and simulation results demonstrate that the proposed relaying scheme has better performance gain over the conventional max-link scheme. [ABSTRACT FROM AUTHOR]

In a communication system employing coherent reception, pilot symbols are used for estimating the channel state information (CSI) at the receiver. The amount of training, which is quantified by the fractional pilot duration for a fixed-length pilot-plus-data frame, should be kept as low as possible for saving bandwidth and increasing data rate. However, reducing training leads to degraded error performance due to poor CSI estimate although it increases data rate, while increasing training improves error performance but reduces data rate. Expressing the tradeoff between symbol error probability (SEP) and data rate by the normalized error-free data rate, we present an analytical framework for its maximization with respect to pilot symbol duration fraction in a pilot-aided single-input multiple-output wireless communication system with reception over independent and identically distributed flat Rayleigh fading diversity branches, employing $M$ -ary phase-shift keying, and using maximal-ratio combining. Closed-form expressions for the approximate optimal pilot symbol duration fraction are derived for the high signal-to-noise ratio (SNR) case. Numerical results are presented to highlight the system behavior with changes in parameters like SNR, pilot symbol quality, and number of receive diversity branches. It is found that the optimization maximizes normalized error-free data rate with close to minimum SEP. [ABSTRACT FROM AUTHOR]

The October 2023 issue of the IETE Journal of Research contains 70 articles covering various topics in the fields of Communications, Electromagnetics, Optoelectronics, Computers and Computing, Control Engineering, Electronic Circuits, Devices and Components, Instrumentation and Measurement, Medical Electronics, and Power Electronics. The issue includes articles on topics such as the performance of hybrid FSO/RF systems, complexity reduction in UFMC systems, lossless compression of hyperspectral imagery, miniaturized substrate integrated waveguide filters for 5G applications, object tracking using thermal and visible imaging, MIMO diversity antennas for UWB applications, metamaterial-based SWB-MIMO antennas, and more. The issue also features articles on spintronic ripple carry adders, lattice-shifted twist-induced photonic crystal waveguides, software project effort estimation, neural machine translation, supply chain financial risk management, brain computer interfaces, reversible data hiding schemes, IoT-based airshed management, lemmatizers, content-based image retrieval, and named entity recognition. [Extracted from the article]

The September 2023 issue of the IETE Journal of Research features 60 articles covering a wide range of topics in electrical engineering. These include communications, electromagnetics, opto-electronics, computers and computing, control engineering, electronic circuits, devices and components, instrumentation and measurements, medical electronics, and power electronics. The articles discuss ongoing research and recent advancements in these fields, presenting innovative approaches and techniques. Some specific examples include securing sensitive data in communications, improving the performance of OFDM systems through deep learning, antenna design and bandwidth enhancement in electromagnetics, and the application of artificial intelligence in the legal field. The issue also covers topics such as image data security and medical applications of electronics. Each research paper in the issue focuses on a specific problem, proposes a solution or method, and provides results and comparisons to demonstrate its effectiveness. The authors of the papers are experts in their respective fields, with extensive experience and qualifications. [Extracted from the article]

A novel low complexity energy detection receiver, which utilizes knowledge of the magnitudes of the fading gains of the receive diversity branches, is presented. Its error performance in flat Rayleigh fading with multi-level amplitude-shift keying is analyzed, resulting in a closed form expression for the symbol error probability (SEP) as well as analytical results for high signal-to-noise ratios. These show that the receiver has the same diversity order as that of coherent receivers but maintains the low complexity structure of energy detectors. Numerical results show that the SEP performance of the energy detection receiver is much closer to that of a coherent receiver than to that of a noncoherent one. Furthermore, we also consider transmit constellation optimization and conclude that an equally spaced amplitude level constellation performs close to the optimal solution in Rayleigh fading. A significant advantage of this receiver is that it performs much better than noncoherent detection but maintains the low complexity structure of noncoherent detectors. Training to obtain the channel magnitudes is, however, required but the low complexity receiver can be used to perform that with the only additional overhead being the training time. [ABSTRACT FROM PUBLISHER]

This paper analyzes the performance of a buffer-aided multi-hop relaying system using the max-link relay selection scheme for decode-and-forward cooperative networks. A Markov chain approach is adopted to analyze the state transition matrix that models the evolution of the status of relay buffers. Analytical expressions for the steady-state probability vector are obtained for a three-hop buffer-aided system, and through these expressions, we observe that states with the same probabilities can be clustered, thus reducing the size of the state transition matrix. We propose a state-clustering-based method to obtain the reduced state transition matrix, which is further used to derive an analytical expression for the outage probability with reduced computational complexity. The method is general in the sense that it does not require any prior knowledge about the steady-state probability vector and the state transition matrix. Furthermore, we illustrate, in detail, the construction of the reduced state transition matrix and the related steady-state distribution by an example. An analytical expression for the average packet delay is also derived. Both analytical and simulation results are provided to investigate the performance of buffer-aided multi-hop relaying networks. [ABSTRACT FROM AUTHOR]

A noncoherent quadratic diversity reception system for multilevel amplitude-shift keying (ASK) signals in Rayleigh fading with different cases of the channel covariance matrix is considered. These include the important case of distributed antennas, which exhibit uncorrelated fading with distinct mean-squared channel gains (uncorrelated nonidentical fading) and weighted energy detectors, and the cases of exponentially correlated and uniformly correlated channels with equal mean-squared channel gains. For these cases, closed-form expressions for the symbol error probability (SEP) of the system are derived using the decision statistics obtained from the maximum likelihood receiver. The problem of determining the optimal amplitude levels that minimize the SEP under a total signal energy constraint is formulated and solved analytically for the high signal-to-noise ratio (SNR) configuration and numerically for the general configuration. For the high SNR configuration, it is shown that the optimal ASK levels should follow an approximately geometric progression. It is also observed that an equally spaced ASK constellation is not optimal in terms of achieving the minimum SEP. Numerical results are presented to highlight performance trends for channel gain imbalance and correlation. [ABSTRACT FROM PUBLISHER]

Multihop communication is considered to be a useful approach for improving the coverage area with reduced transmit power. In this paper, we consider a path-selection-based multihop decode-and-forward (DF) cooperative system. A simple parallel multihop path-based cooperative communication system is considered. It is assumed that all hops in all cooperative paths are subject to independent Rayleigh fading. The best path, that is, the best multihop link between the source and the destination, is selected based on the max–min selection criterion. The relays in the selected cooperative path use the symbol-wise DF protocol, in which they demodulate the received data from the preceding node in a symbol-wise manner and forward it to the succeeding node. An analytical framework is developed for finding an accurate (almost close to exact) error performance of the considered system. To be more specific, we derive an accurate expression of the average bit error rate of the max–min-criterion-based best-path selection scheme, in terms of convergent power series. The coding gain and the diversity order of the scheme are also analytically obtained. [ABSTRACT FROM AUTHOR]

In this paper, the transmission of orthogonal space–time block codes (OSTBCs) in amplify-and-forward (AF) multiple-input–multiple-output (MIMO) relay networks, with imperfect channel state information (CSI), is considered. Individual channel estimation and time-efficient cascaded (for estimating the product of channel matrices) channel estimation protocols are used for estimating the channel matrices required for decoding of OSTBC data at the destination. We derive tight approximations for the moment-generating function (m.g.f.) of the received signal-to-noise ratio at the destination node with imperfect CSI, by ignoring higher order noise terms, in Rayleigh fading. Using the derived m.g.f. expression, we obtain the analytical symbol error rate (SER) of the AF MIMO relay system for general OSTBCs with $M$-ary phase-shift keying constellation. The diversity order of the MIMO OSTBC relay system is also derived for some special cases by using the SER expression. [ABSTRACT FROM PUBLISHER]

The use of repeaters (relays) has recently been introduced in power line communication (PLC) systems for long-distance data transfer and thus, it becomes important to analyze the performance of relay based PLC systems. A simplified system model with distance dependent signal attenuation and additive white Gaussian noise may not cover all the factors affecting the data transfer, such as variation in amplitude (fading) and occurrence of impulsive noise. Hence, a more realistic system model with log-normal fading, distance dependent signal attenuation, and a Bernoulli-Gaussian impulsive noise is considered in this paper to study the end-to-end average bit error rate (BER) and the end-to-end average channel capacity of a PLC system equipped with amplify-and-forward (AF) relays. Approximate closed-form expressions of the end-to-end average BER for binary phase-shift keying and the average channel capacity for high signal-to-noise ratio are obtained. The performance of the PLC system with AF relays is found to be superior compared to that of a direct transmission PLC system for fixed transmission power. [ABSTRACT FROM PUBLISHER]

We consider signal design for multiple-input multiple-output (MIMO) systems with spatial multiplexing and noncoherent reception in a flat Rayleigh fading environment. We obtain the symbol vector error probability (SEP) of noncoherent detection as a function of the signal amplitude levels and the effective precoder matrix, which depends on the precoder structure and the channel transmit covariance matrix. It is found that at high values of average signal-to-noise ratio (SNR) per symbol vector per diversity branch, the SEP tends to reach saturation. To obtain the best error performance, we need to find the optimal precoder and constellation parameters that minimize the saturation value of the SEP. Optimization of the saturation value of the SEP is carried out using the binary signal constellations {0,1} and \1,-r\, $r > 1$, two transmit antennas, a real valued transmit covariance matrix with equal diagonal elements, and a diagonal precoder. Results show that the optimal values of the parameters are almost independent of the number of receive antennas when the number of receive antennas is large. We also observe that the error performance of MIMO noncoherent reception is better than that of MIMO coherent reception with imperfect channel state information for a certain range of average SNR. [ABSTRACT FROM PUBLISHER]

In the presence of heterogeneous service provider (SP) networks such as wireless local area networks and cellular networks, users have to make a choice. The quality of service provided and the price charged by an SP play a crucial role in this decision process. In this paper, we study the network selection behavior of mobile users. A novel probabilistic framework is presented, with explicit analytical expressions for the transition and steady state network selection probabilities of the users. The proposed framework utilizes the price charged and the utility obtained at the SPs in obtaining the transition probabilities, even in the presence of multi-homing users. Furthermore, network-level parameters such as call blocking probabilities and throughput are obtained in terms of the steady state probabilities. Numerical results indicate that the prices and utilities at the heterogeneous SPs have considerable impact on the overall network performance. [ABSTRACT FROM PUBLISHER]

It also reports simulation-based comparison study with other optimization algorithms such as particle swarm optimization, differential evolution, and whale optimization algorithm. The experiment results of the algorithm in the form of precision are compared with conventional algorithms to draw conclusions about the efficacy of the proposed algorithm. In the paper titled "Analysis of Amplitude Scintillation and Positioning Error of IRNSS/GPS/SBAS Receiver for Heavy Rainy Days", the authors examine the characteristics of amplitude scintillation on an IRNSS/SBAS/GPS receiver with all seven satellites of the Indian Regional Navigation Satellite System (IRNSS) at the low-altitude station IITRAM, Ahmedabad, on days with heavy rain. In the paper "Model Order Reduction Based Power System Stabilizer Design Using Improved Whale Optimization Algorithm", the authors present an optimization technique I viz i . improved whale optimization for designing a power system stabilizer using model-order reduction for a modified single machine infinite bus system. [Extracted from the article]

The paper presents the antenna's parameters from simulation study and from measurements done on a fabricated antenna and comparisons are made between them to draw inferences. The next paper on "A Pi-Shaped Slot Antenna for 5.2 GHz WLANMIMO Application" presents the design of a rectangular patch antenna with shaped slot as a miniaturized antenna element for WLAN applications. In "Wideband Reflectarray Antennas Using Concentric Ring-Based Elements for Ku-Band Applications" authors present the design of two wideband reflectarray antennas in the X-Ku band (10-15 GHz). The first paper in the issue "Simulation and Synchronous Generation of Radar Signals at Geographically Distributed Sensors for Testing Emitter Location System" presents a simulation study of location fixing of radar emitters using sensors that are distributed over tens of kilometers. [Extracted from the article]

The authors of the paper titled "Towards Neuro-Fuzzy Compensated PID Control of Lower Extremity Exoskeleton System for Passive Gait Rehabilitation" designed a neuro-fuzzy compensated PID control for passive gait rehabilitation using a lower extremity exoskeleton system. In the paper "A Comparative Survey of Convex Combination of Adaptive Filters", the authors evaluate the convex combination of adaptive filters, which are mostly based on the least mean square (LMS) algorithm, the affine projection (AP) algorithm, and the recursive least mean square (RLS) algorithm. The paper "A Novel Weighted Superposition Attraction Algorithm-based Optimization Approach for State of Charge and Power Management of an Islanded System with Battery and Super Capacitor-based Hybrid Energy Storage System" proposes a Hybrid Energy Storage System (HESS) employing a Battery and a Super Capacitor (SC). The authors of the paper titled "Computer-Aided Detection and Diagnosis of Thyroid Nodules Using Machine and Deep Learning Classification Algorithms" propose a computer-assisted method for detecting and segmenting tumour regions in ultrasound thyroid images using machine and deep learning classification algorithms. [Extracted from the article]

We consider a communication system with receive diversity in flat Rayleigh fading employing multi-level amplitude-shift keying (ASK) and noncoherent reception. Using the statistics of the decision variable of the quadratic receiver, a closed form expression for the symbol error probability (SEP) is derived. A formulation to determine the optimal signal amplitude levels of ASK constellation that minimize the SEP subject to a total signal energy constraint is presented. By approximating the derivative of the objective function, an approximate semi-analytical solution is obtained. We also present an asymptotic SEP expression that shows the variation of the SEP at high signal-to-noise ratio (SNR) and the diversity order of the system. An important result is that the optimum signal amplitude levels at high SNRs follow an approximately geometric progression in contrast to the more typical case of signal amplitude levels in arithmetic progression. Numerical results show the superiority of error performance of ASK with optimal signal amplitude levels as compared to that of ASK with signal amplitude levels in arithmetic progression. [ABSTRACT FROM PUBLISHER]

We consider a wireless system with a multi-branch diversity receiver employing noncoherent reception. The receiver has information on the channel statistics instead of the instantaneous channel state information, and the average branch signal-to-noise ratios (SNRs) are all distinct. In such a scenario, a deterministically weighted square-law combining scheme can be used to improve the error performance over conventional square-law combining. We focus on such a scheme for a system with orthogonal signaling in uniformly correlated Rayleigh fading. We obtain suboptimal weights, by least squares fit of the matrix elements of the characteristic functions of the decision variables of the weighted square-law combining and the optimum quadratic combining receivers, in closed form that are computed easily using an iterative algorithm. For the case of a dual-diversity system, an implicit expression for the optimal weights, chosen to minimize the symbol error probability, is obtained; for binary signaling, we derive closed form expressions for the weights. It is found that weighted square-law combining offers significant performance improvement over conventional square-law combining at a cost of increased complexity, and the performance gap increases with increasing branch SNR imbalance and number of branches. [ABSTRACT FROM PUBLISHER]

Cooperative diversity achieves enhanced data rates and throughput using distributed spatial diversity techniques. We consider a cooperative diversity system comprising of a source, a relay, and a destination, with decode and forward (DF) protocol at the relay. The drawback of conventional instantaneous signal-to-noise ratio (SNR) based selection combining is that it fails to use the instantaneous SNR of the source-relay channel at the destination while selecting the best channel from source-destination and relay-destination channels. Full channel state information (CSI) selection combining, which effectively utilizes the instantaneous SNR of the source-relay channel at the destination, is used to overcome this drawback. The exact end-to-end symbol error probability (SEP) of full CSI selection combining for this DF system, with M-ary phase-shift keying in a flat Rayleigh fading environment, is derived. The analysis is validated through simulations. The diversity gain analysis is also studied for this scheme. Further, we compare the full CSI selection combining scheme with some other existing schemes. Numerical results show that full CSI selection combining has performance similar to that of instantaneous SEP based selection combining, but offers SNR gain over instantaneous SNR based selection combining, max-min selection, and selection cooperation. [ABSTRACT FROM PUBLISHER]

In the paper entitled "Design and Analysis of Dual Band-Notched UWB Antenna Using a Slot in Feed and Asymmetrical Parasitic stub" the authors present a novel elliptically slotted antenna (ESA), with two notched bands for Ultra-wideband (UWB) applications. The authors of the paper "Compact Corner Truncated Fractal Slot Antenna for Cognitive Radio Sensor Network" propose a novel compact antenna for wide spectrum sensing in wireless cognitive radio sensor networks (WCRSN). The author of the work titled "Optimizing Dimensions of Cassegrain Antenna System with Large Magnification Factor" describes a computer-aided design method for optimising Cassegrain antenna dimensions when the feed antenna is located directly behind the main reflector. To improve the image quality, a gain-controlled bi-histogram equalisation operation is conducted on the detailed component of V. In the study entitled "An Effective Brain Tumor Detection System Using Extended Linear Boosting (ELB) Classification Algorithm", tumour cells are found in brain Magnetic Resonance Imaging (MRI) using the Extended Linear Boosting (ELB) classification method, which is a form of soft computing. [Extracted from the article]

Cooperative diversity through decode-and-forward (DF) relaying is an effective method for improving the performance of mobile wireless systems. We consider here the performance of a cooperative diversity system in which the relay employs the DF protocol to transmit data from a source to a destination using binary phase-shift keying (BPSK). A flat Rayleigh fading environment with statistically independent links is assumed. The optimum receiver for this system is presented, and from the decision rule, the end-to-end symbol error probability (SEP) is derived. Numerical results on the SEP are obtained and compared with those for a suboptimum receiver, which does not need the channel state information of the source-to-relay link. [ABSTRACT FROM PUBLISHER]

Consider a cooperative diversity network that consists of a source, N cooperating relays, and a destination. The relays cooperate with the source through the decode and forward protocol to transmit a data symbol from the source to the destination. In a conventional signal-to-noise ratio based selection combining scheme at the destination, the effect of the source-to-relay links is not accounted for when choosing one link from the set consisting of the source-to-destination and N relay-to-destination links. To overcome this drawback, we modify the conventional scheme by including, in the selection process, a deterministic scale factor that incorporates the effect of the source-to-relay links. For statistically independent links that undergo flat Rayleigh fading, we derive, in closed form, the exact end-to-end symbol error probability (SEP) of this modified scheme, which we call a scaled selection combining scheme for M-ary phase-shift keying constellation. We also give a method of obtaining the optimum scale factor that minimizes the end-to-end SEP. A system designer should select the optimum scale factor to achieve the best performance of the scheme. [ABSTRACT FROM PUBLISHER]

We consider a space-time coded system in a correlated Rayleigh flat fading environment with imperfect channel estimation. Two receiver structures are considered: a suboptimum receiver and the optimum maximum likelihood receiver. The system performance of both receivers is analyzed in terms of the pairwise error probability. [ABSTRACT FROM AUTHOR]

A transmit-receive diversity system in correlated Rayleigh fading in which the receiver estimates the channel through pilot symbols, and feeds this information back to the transmitter through a feedback path, is considered. The imperfect channel state information (CSI) is used by the transmitter to obtain the transmit weight vector for data transmission. The optimum receiver in the maximum-likelihood (ML) sense obtained from the conditional distribution of the received signal vector, conditioned on the imperfect CSI and the transmit weight vector, is derived for the system. For the case of M-ary phase-shift keying (MPSK), an analytical expression for the conditional symbol error probability (SEP), conditioned on the channel estimate and the transmit weight vector, is obtained, with the transmit weight vector chosen to minimize this conditional SEP. For the receive-only and transmit-only correlation scenarios with ill-conditioned eigenvalues of the receive and transmit covariance matrices (that is, some of the eigenvalues are very small), we derive expressions for the diversity gain. Numerical results are presented to compare the performance of our receiver with that of a conventional receiver in case of exponentially correlated fading. These results show that the optimum receiver typically has about a 0.5-dB gain over a conventional receiver when the correlation coefficient exceeds 0.5 and the number of receive antennas is much larger than the number of transmit antennas. [ABSTRACT FROM AUTHOR]

The average of the product of two Gaussian Q-functions having arguments as different scaled versions of the same Nakagami distributed fading gain magnitude is derived in closed-form. Both the cases when (1) the fading parameter is an integer, and (2) the fading parameter is an odd multiple of one-half, are considered. The results are applied to evaluating in closed-form (a) the symbol error probability (SEP) of rectangular quadrature amplitude modulation with maximal-ratio combining in independent Nakagami fading, and (b) the outage probability of a two-user synchronous code-division multiple-access system having signal-to-noise ratio (SNR) imbalance among users in Nakagami fading. It is found in application (a) that with increase in the degree of fading, the robustness to decision distance imbalance between in-phase and quadrature signals increases. In addition, there exists an optimum decision distance ratio at which the SEP has a minimum. In application (b), we find that the outage probability increases sharply with SNR imbalance factor at low SNR imbalance and tends to reach saturation as the imbalance increases. [ABSTRACT FROM AUTHOR]

This paper investigates detection mechanisms for time hopping pulse position modulated (TH-PPM) multiple access systems in both additive white Gaussian noise and fading environments. In such systems, the raw data is not linearly related to the received signal. One technique is to express the pulse position modulated signal as the sum of linearly modulated signals with the input being a nonlinear function of the raw data. This reduces the system to an equivalent pulse amplitude modulated system with a significant increase in complexity. We present two new lower complexity detectors. The first detector, which is a frame-level maximum likelihood (ML) detector, uses the proper- ties of the pulse correlation matrix to develop a lower complexity detection method. The second detector, which is a chip-level ML detector, relies on the knowledge of the time hopping sequence to despread the received signal. The detection is then done on a chip-by-chip basis. The performance of these detectors is compared in terms of the bit error rate for the user with weakest power and the average number of correctly decoded users. [ABSTRACT FROM AUTHOR]

Some bounds on the entries and on the norm of the inverse of triangular matrices with nonnegative and monotone entries are found. All the results are obtained by exploiting the properties of the fundamental matrix of the recurrence relation which generates the sequence of the entries of the inverse matrix. One of the results generalizes a theorem contained in a recent article of one of the authors about Toeplitz matrices. [ABSTRACT FROM AUTHOR]

We consider a space-time block coded system having L time slots and using decision feedback channel estimation with a finite window size. The channel matrix estimate is updated every L time slots by: 1) a least-squares (LS) estimate and 2) a minimum mean-square error (MMSE) estimate. Using a Markov model of the decision process, we analyze the decoding error probability (DEP) of this scheme in Rayleigh fading. The transition probability matrix is obtained by simulation of the decision process for a system using the Alamouti code. From this matrix, the DEP can be computed for any time shift. We find from computations that the DEP increases with increase in the time shift but tends to saturate with time to a steady-state value. It is also observed that both the state and the transition probabilities tend to saturate with the increase in average signal-to-noise ratio per diversity branch. [ABSTRACT FROM AUTHOR]

We consider a space-time block coded system having L time slots and using decision feedback channel estimation with a finite window size. The channel matrix estimate is updated every L time slots by: 1) a least-squares (LS) estimate and 2) a minimum mean-square error (MMSE) estimate. Using a Markov model of the decision process, we analyze the decoding error probability (DEP) of this scheme in Rayleigh fading. The transition probability matrix is obtained by simulation of the decision process for a system using the Alamouti code. From this matrix, the DEP can be computed for any time shift. We find from computations that the DEP increases with increase in the time shift but tends to saturate with time to a steady-state value. It is also observed that both the state and the transition probabilities tend to saturate with the increase in average signal-to-noise ratio per diversity branch. [ABSTRACT FROM AUTHOR]

In a communication system using receive diversity and linear combining in the presence of cochannel interference (CCI), optimum combining (OC) is known to give the best error performance since it maximizes the instantaneous signal-to-interference-plus-noise ratio of the combiner output, and consequently, in the presence of Gaussian interference plus noise, it minimizes the error rate. However, this is based on the assumption that a perfect estimate of the channel is available. Channel estimation methods in reality use some overhead. When the channel is time-invariant, the estimation error decreases with increase in the amount of overhead, like the number of pilot symbols. With the growing need for high data rate applications, the amount of overhead that can be allocated for the estimation of the channel needs to be reduced, and the channel estimation error cannot be ignored. In this situation, replacing the channel by its imperfect estimate in the OC weight vector no longer results in an optimum scheme. We have to find an optimum scheme based on the channel estimation method and the detection criterion, which results in what we call optimized diversity combining (ODC). Here we focus on ODC resulting from a pilot symbol based maximum likelihood (ML) channel estimation method applied to a correlated flat Rayleigh fading channel in the presence of CCI and additive noise. The channel is randomly time-invariant during the reception of pilot and data symbols. The decision rule, which is optimum in the ML sense, is derived using concepts of Gaussian and Wishart statistics. Numerical results show that ODC can perform significantly better than OC with imperfect channnel estimates by appropriate choice of system parameters. [ABSTRACT FROM AUTHOR]

Consider a wireless communication system in flat fading with N transmit and M receive antennas using space-time block coding, where N ⊗ 1 code vectors are transmitted over L symbol intervals, resulting in an N ⊗ L code matrix. A least-squares estimate (LSE) as well as a minimum mean-square estimate (MMSE) of the M ⊗ N channel matrix is obtained from a sequence of pilot code vectors. For the case of linear square (i.e., with N = L) orthogonal codes over constant envelope constellations, we obtain an expression for the exact decoding error probability (DEP) for coherent maximum-likelihood decoding. We also find the coding gain for high average signal-to-noise ratio (SNR) per diversity branch in the case of Rayleigh fading. A comparison between both channel-estimation techniques is done in terms of the average pilot-power-to-signal-power ratio (APPSPR). It is found that MMSE requires lower pilot power than LSE for the same DEP and the same average SNR per diversity branch. In addition, the error performance with LSE approaches that with MMSE, with an increase of average SNR per branch or an increase of APPSPR. [ABSTRACT FROM AUTHOR]

We analyze the error performance of minimum selection generalized selection combining (MS-GSC), in which the minimum number of diversity branches are selected such that their combined signal-to-noise ratio (SNR) is above a given threshold. A flat Rayleigh fading channel with independent and distinctly distributed branch SNRs is considered. By transforming the ordered instantaneous branch SNRS to their differences, we derive the distribution of the number of selected branches in closed form. We then modify the derivation of this distribution to get the characteristic function (cf.) of the combiner output SNR. This cf. is used to obtain the symbol error probability for different coherent digital modulation schemes. [ABSTRACT FROM AUTHOR]

The pseudo-Wishart distribution arises when a Hermitian matrix generated from a complex Gaussian ensemble is not full-rank. It plays an important role in the analysis of communication systems using diversity in Rayleigh fading. However, it has not been extensively studied like the Wishart distribution. Here, we derive some key aspects of the complex pseudo-Wishart distribution. Pseudo-Wishart and Wishart distributions are treated as special forms of a Wishart-type distribution of a random Hermitian matrix generated from independent zero-mean complex Gaussian vectors with arbitrary covariance matrices. Using a linear algebraic technique, we derive an expression for the probability density function (pdf) of a complex pseudo-Wishart distributed matrix, both for the independent and identically distributed (i.i.d.) and non-i.i.d. Gaussian ensembles. We then analyze the pseudo-Wishart distribution of a rank-one Hermitian matrix. The distribution of eigenvalues of Wishart and pseudo-Wishart matrices is next considered. For a matrix generated from an i.i.d. Gaussian ensemble, we obtain an expression for the characteristic function (cf) of eigenvalues in terms of a sum of determinants. We present applications of these results to the analysis of multiple-input multiple-output (MIMO) systems. The purpose of this work is to make researchers aware of the pseudo-Wishart distribution and its implication in the case of MIMO systems in Rayleigh fading, where the transmitted signals are independent but the received signals are correlated. The results obtained provide a powerful analytical tool for the study of MIMO systems with correlated received signals, like systems using diversity and optimum combining, space-time systems, and multiple-antenna systems. [ABSTRACT FROM AUTHOR]

Consider a Rake receiver for coherent binary antipodal signaling with: 1) a delayed received signal configuration; 2) weight estimation by matched filtering using the reference signal along with the decisions of the previous M symbol intervals; and 3) predetection maximal ratio combining (MRC). The weight estimation errors here are not independent of the additive noise, and do not fit into the Ganssian weighting error model for MRC. Here we analyze the error performance of the receiver by obtaining the conditional symbol error probability, conditioned on past decisions, from the characteristic function of the decision variable, and getting the unconditional error probability (UEP) for a block of M consecutive symbols using a Markov model of the decision process. The channel is Rayleigh fading with independent and identically distributed branch gains. Results show that the error performance of the Gaussian distributed weighting error model is a bound for that of multiple symbol weight estimation by matched filtering, and the steady state UEP decreases with increase of M, but the amount of decrease reduces as M increases. [ABSTRACT FROM AUTHOR]

Presents the expressions for multivariate Rayleigh and exponential probability density functions (pdfs) generated from correlated Gaussian random variables. Presentation of a general integral form of the pdfs; Derivation of a general expression for the multivariate exponential characteristic function in terms of determinants; Use of the series and determinant expressions for the exponential cfs.

We analyze the error performance of a wireless communication system employing transmit-receive diversity in Rayleigh fading. By focusing on the complex Gaussian statistics of the independent and identically distributed entries of the channel matrix, we derive a formula for the characteristic function (c.f.) of the maximum output signal-to-noise ratio. We use this c.f. to obtain a closed-form expression of the symbol error probability (SEP) for coherent binary keying. The method is easily extended to obtain the SEP for the coherent reception of M -ary modulation schemes. [ABSTRACT FROM AUTHOR]

Presents a study which derived the bit error probability for coherent detection of binary signals with dual-diversity predetection equal gain combining using the Beauliue series. Analysis of predetection equal gain combining with dual diversity in Rayleigh fading; Expression for the bit error probability; Mechanism of the equal gain combining.