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Arti M.K.,Northern India Engineering College
IEEE Transactions on Communications | Year: 2016

In this paper, we consider the two-way relaying of the data of two earth stations (ESs) via satellite links. The satellite is considered to be of transparent type, which only receives the signals over the uplink and broadcasts these signals with some transponder gain over its downlink frequencies. The two-way relaying signals are perturbed by the self-interference, which can only be removed with perfect knowledge of the uplink and downlink channels of the ESs. In satellite communication, it is difficult to generate the perfect information of the uplinks in the ESs due to the practical limitations, such that uplink and downlink channels of the ESs do not follow the reciprocity, and impossibility of reverse training as the satellite cannot transmit over uplink frequencies due to the transmit power limitations. Another factor that is highly undesirable from the channel state information (CSI) estimation perspective is large propagation delays of the satellite links. In this paper, we consider the design of a training protocol for two-way satellite relaying (TWSR) system, which is in complete agreement with (or does not violate) the practical limitations involved in the CSI estimation in satellite communications. It is found by analysis that if both ESs transmit orthogonal training sequences, then the satisfactory value of CSI for self-interference cancellation and decoding of the unknown symbols can be generated in each ES. Then, in order to analytically demonstrate the effect of CSI estimation over the performance of the TWSR system, we derive the average bit error rate and average capacity of the scheme over the Shadowed-Rician fading channels. © 2016 IEEE. Source


Chawla V.,Northern India Engineering College | Saraf S.A.,Babu Banarasi Das National Institute of Technology and Management
JAOCS, Journal of the American Oil Chemists' Society | Year: 2011

The aim of this study was to explore the use of glyceryl behenate (GB) as a candidate lipid for the production of solid lipid nanoparticles (SLN) using the anti-inflammatory drug, aceclofenac, as an example. SLN were produced using the Gasco microemulsion method with three different lipids, namely GB, glyceryl palmitostearate (GP) and cetyl alcohol (CA). The prepared SLN were subjected to determination of entrapment, zeta potential, particle size, in vitro dissolution, entrapment efficiency and biodistribution. Stable SLN of GB having size 245 ± 5 nm were prepared with a polydispersity index of 0.470. The size range was higher with other lipids i.e., CA and GP. It was found that as the drug lipid molar concentration was raised, particles with a smaller size were obtained irrespective of the nature of the lipid. The surfactant poloxamer 188 gave best results when used at a concentration of 2.5% w/v of dispersion. The study recommends GB as a suitable candidate for the production of SLN. © 2010 AOCS. Source


Arti M.K.,Northern India Engineering College
2015 21st National Conference on Communications, NCC 2015 | Year: 2015

The maximal ratio combining (MRC) scheme for Shadowed-Rician (SR) fading land mobile satellite (LMS) channels with estimated channel gains is studied, in this paper. For this set-up, a maximum-likelihood decoder is derived under the assumption of the perfectly known channel state information (CSI); then perfect CSI is replaced with the estimated CSI in the decision metric. The MRC scheme for SR fading LMS channels has been studied in existing literature mostly with the perfect CSI assumption; moreover, most of the existing analytical results are in the form of infinite power series, which are not in closed-form. In this paper, we derive approximate closed-form expressions of the probability density function and moment generating function (MGF) of the received signal-to-noise ratio of the MRC based receiver in SR fading LMS channels with estimated channel gains. Analytical expression for the symbol error rate of M-ary phase shift keying constellation is derived by using the MGF expression. We also provide approximate closed-form expression of the average capacity with estimated channel gains of the considered scheme. It is shown from analysis and simulation that estimation error does not affect the diversity order of the system. © 2015 IEEE. Source


Shukla P.K.,Northern India Engineering College | Tripathi S.P.,Institute of Engineering and Technology
Proceedings - 2011 5th International Conference on Genetic and Evolutionary Computing, ICGEC 2011 | Year: 2011

Obtaining high degree of Interpretability and Accuracy in the design of complex high dimensional fuzzy systems is contradictory in nature. It is well known by Interpretability-Accuracy (I-A) Trade-Off. Several methods have been proposed to find good I-A Trade-Off. These includes Multiobjective Optimization, Context Adaptation, Hierarchical Fuzzy Modeling and other issues related to fuzzy partition, membership functions, rules, rule bases etc. This paper is the survey of different approaches developed regarding the issue of I-A Trade-Off in designing fuzzy systems in the last decade. Also, the techniques for assessing the interpretability and accuracy have been surveyed. © 2011 IEEE. Source


The maximal ratio combining (MRC) scheme for Shadowed-Rician (SR) fading land mobile satellite (LMS) channels with estimated channel gains is studied, in this paper. It is assumed that satellite contains a single antenna and earth station (ES) has multiple antennas. For this set-up, a maximum-likelihood decoder is derived under assumption that perfect channel state information (CSI) is known; then the perfect CSI is replaced with estimated CSI in decision metric at ES. The MRC scheme for SR fading LMS channels has been studied in existing literature mostly with perfect CSI assumption. We derive approximate closed-form expressions of the probability density function, cumulative distribution, moment generating function (MGF), and analytical diversity order for the MRC based receiver in independent and identically distributed SR fading LMS channels with estimated channel gains. The author also provides approximate closed-form expressions of the outage probability and capacity of the considered scheme with estimated channel gains. Next, the author considers correlated SR fading LMS links and derive approximate bit error rate of the satellite system with estimated channel gains. It is shown from analysis and simulation that channel estimation error and correlation do not affect the diversity order but reduce the capacity of the considered system. © 2015. The Institution of Engineering and Technology. Source

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