Minimum symbol error rate multiuser detection using an effective invasive weed optimization for MIMO/SDMA–OFDM system

Space division multiple access–orthogonal frequency division multiplexing system has become a potential wireless communication system by offering high spectral efficiency, performance and capacity. This article deals with minimum symbol error rate (MSER)‐based multiuser detection (MUD) technique for the space division multiple access–orthogonal frequency division multiplexing system using an efficient invasive weed optimization (IWO) algorithm. The IWO algorithm is used for finding optimal weights such that the probability of error is directly minimized rather than minimizing the mean square error. Because of this, the MSER MUD is able to detect users even in overload scenario, where the number of users is more than the number of receiving antennas, unlike several classical detection techniques. The IWO is inspired from the nature of invasive colonization of weeds and relatively simple compared with other optimization techniques. The bit error rate performance of the proposed IWO‐aided MSER MUD is found to be better than minimum means square error and differential evolution algorithm‐aided MSER MUDs. Simulation results show that the proposed IWO MSER achieves faster convergence and lower complexity compared with the differential evolution MSER MUD. Copyright © 2013 John Wiley & Sons, Ltd.     

Piezoelectric micromachined ultrasonic transducers: modeling the influence of structural parameters on device performance

Piezoelectric micromachined ultrasonic transducers (pMUTs), a potential alternative for conventional one-dimensional phased array ultrasonic transducers, were investigated. We used a modeling approach to study the performance of lead zirconate titanate (PZT)-driven pMUTs for the frequency range of 2-10 MHz, optimized for maximum coupling coefficient, as a function of device design. Using original tools designed for the purpose, a comprehensive build-test finite element model was developed to predict and measure the device performance. In particular, the model estimates the device coupling coefficient and the acoustic impedance, besides the readily extractable resonance frequency and bandwidth. To validate the model, a prototype device was built and tested, showing good agreement between the model predictions and experimental results. Modeling results indicate that the coupling coefficient is significantly affected by silicon membrane, PZT, and top electrode thickness as well as the top electrode design. Results also indicate considerable flexibility in maximizing the coupling coefficient while maintaining the device acoustic impedance at a level matching that of the human body. The bandwidth proved to be superior to that of conventional transducers, reaching 102% in some cases.     

Channel Models for Inter-body Communication in Ultra Wideband-Based Body Area Networks

Wireless Personal Communications - Body area networks (BANs) are evolving tremendously over the years and with the progress in the area of internet of things, the BANs are more important than ever....     

CL-AGKA: certificateless authenticated group key agreement protocol for mobile networks

Wireless Networks - Wireless group communication has gained much popularity recently due to the increase in portable, lightweight devices. These devices are capable of performing group...     

The role of electrical property in determining the response of 20H-80S composite thin films fabricated for biological applications

Journal of Materials Science - The exploration of exquisite electrical properties of biomaterials for clinical applications is driven by natural design. Inspired by the idea, composite thin films...     

Development of La-impregnated TiO2 based ethanol sensors for next generation automobile application

Journal of Materials Science: Materials in Electronics - Bio-fuel, a blend of ethanol (~?10 to 85%) and gasoline with various compositions, is one of the promising next generation energy...     

Acoustics and rheological studies of aqueous ethylene glycol blend copper oxide nanofluids

Experimental investigations have been performed to synthesize copper oxide nanoparticles by conventional chemical precipitation method and nanofluids were prepared by two-step method using CuO nanoparticles in different proportions of ethylene glycol–water mixtures (EG–water). Powder X-ray diffraction (PXRD), energy dispersive X-ray (EDX), scanning electron microscope (SEM), particle size, and zeta potential analysis have been studied to characterize both solid and fluid samples for their sizes, shapes, stability, and arrangement. Besides, acoustics and rheological properties such as ultrasonic velocity, density, and viscosity have been measured for all fluid samples at three different temperatures. Interpretations of all these parameters have been made on the basis of particle stability and dispersion capacity of nanoparticles in different proportions of base fluids. The variation of dynamic viscosity with shear rate shows the nanofluids to be behaved like non-Newtonian fluids at very less shear rate but shows Newtonian behavior as the shear rate increases.     

Proposed Prediction Framework for Improving the Accuracy of Path loss Models of WiMAX Network

Wireless Personal Communications - Worldwide interoperability for Microwave Access (WiMAX) is an advanced wireless broadband access technology for delivering high speed voice, video and multimedia...