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Panda S.,Kalam Institute of Technology | Sarangi A.,Siksha O' Anusandhan University
AEU - International Journal of Electronics and Communications | Year: 2014

This paper makes use of shuffled frog-leaping algorithm (SFLA) as a training algorithm to train multi-layer artificial neural network (ANN). Next, The SFLA ANNs are used for channel equalization. We, in this paper, also introduce SFLA for channel equalization that is formulated as an optimization problem. In short, this paper introduces a novel strategy for training of ANN and also proposes two novel approaches for channel equalization problem using shuffled frog-leaping algorithm (SFLA). The proposed strategies are tested both in time-invariant and time varying channels and interestingly yield better performance than contemporary approaches as evidenced by simulation results. © 2014 Elsevier GmbH. All rights reserved.

Sahu T.,Indian National Institute of Engineering | Palo S.,Kalam Institute of Technology | Panda A.K.,Indian National Institute of Engineering
Journal of Applied Physics | Year: 2013

We analyze the low temperature multisubband electron mobility in Al xGa1-xAs-GaAs parabolic double quantum well structures in which the outer barriers are delta doped with Si. The structural parabolic potential, obtained from gradual variation of the alloy fraction x (from 0 to xp), partly compensates the triangular like potential profile near the outer interfaces inducing the electrons to move towards the centre of the wells. We study the effect of interplay of ionized impurity (II) scattering and alloy disorder (AD) scattering on the subband mobility. We show that when single subband is occupied both II- and AD-scatterings govern the mobility. However, once second subband is occupied, the mobility is influenced by II-scattering mediated by intersubband effects. It is gratifying to show that the mobility is considerably enhanced in parabolic double quantum wells (0.3 ≥ xp > 0) compared to the square double quantum well structures (xp = 0) at large well widths where double subband is occupied. By increasing the electron density (Ns), the enhancement increases further. We also show that in case of a parabolic single quantum well structure large enhancement in mobility is obtained compared to that of square single quantum well structure as long as single subband is occupied, unlike the double quantum well systems. Our results of mobility in parabolic double quantum wells can be utilized for low temperature device applications. © 2013 American Institute of Physics.

Sahu T.,Indian National Institute of Engineering | Palo S.,Kalam Institute of Technology | Sahoo N.,Berhampur University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2012

We analyze the enhancement of multisubband electron mobility due to an external electric field in a pseudomorphic GaAs/In xGa 1-xAs coupled double quantum well structure. An electric field, applied perpendicularly to the interface plane, changes the potential energy profile of the structure. This change alters the energy level, wave function as well as the occupation of a subband. By varying the field, the system can be transformed from double subband occupancy to single subband occupancy resulting in an enhancement of the mobility due to the suppression of the intersubband effects. We consider scatterings due to the ionized impurities, interface roughness and alloy disorder and study the variations in the intrasubband and intersubband scattering matrix elements as a function of the electric field. The novelty of our work is the analysis of the effect of structure parameters like well width, barrier width and doping concentration on the field dependent multisubband electron mobility. We show that a large enhancement in mobility can be achieved through application of an external electric field by suitably choosing the material parameters. © 2012 Elsevier B.V.

Subudhi P.K.,Maharaja Institute of Technology | Palo S.,Kalam Institute of Technology | Sahu T.,Berhampur University
Superlattices and Microstructures | Year: 2012

We analyze the strain induced changes in the low temperature multisubband electron mobility mediated through the intersubband interactions in a pseudomorphic GaAs/In xGa 1-xAs coupled double quantum well structure. We consider the non-phonon scattering mechanisms and study the effect of strain on them. We show that strain reduces the mobility due to ionized impurity (imp-) scattering μ imp but enhances the mobility due to interface roughness (IR-) scattering μ IR. For alloy disorder (AL-) scattering as long as the lowest subband is occupied, the effect of strain enhances the mobility μ AL. However, once the second subband is occupied, there is almost no change, rather decrease in μ AL for larger well widths. It is gratifying to note that for single subband occupancy, the effect of strain enhances the total mobility μ. On the other hand, for double subband occupancy, initially there is almost no change, but with increase in well width the total mobility reduces. We vary the In composition x from 0.15 to 0.2 and 0.25 and the barrier width between the two wells to analyze their effects on the mobility which shows interesting results. Our study of multisubband mobility can be utilized for the low temperature device applications. © 2012 Elsevier Ltd. All rights reserved.

Panda S.,Kalam Institute of Technology | Mohapatra P.K.,Orissa Engineering College, Bhubaneswar
Applied Soft Computing Journal | Year: 2015

This paper deals with the problem of equalization of channels in a digital communication system. In the literature, arti.cial neural network (ANN) has been increasingly used for the said problem. However, traditional methods of ANN training fall short of desired performance in the problem of equalization. In this paper, we propose a recently proposed training method for ANN for the problem. This training uses directed search optimization (DSO) as a trainer to neural networks. Then, we apply the same to the problem of nonlinear channel equalization and in that way, this paper introduces a novel strategy for equalization of nonlinear channels. Proposed method of channel equalization performs better than contemporary equalization methods used in the literature, as evident from extensive simulation results presented in this paper. © 2014 Elsevier B.V. All rights reserved.

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