Open Science Research Excellence

Rajoo Pandey

Publications

3

Publications

3
3859
Complex-Valued Neural Networks for Blind Equalization of Time-Varying Channels
Authors:
Abstract:

Most of the commonly used blind equalization algorithms are based on the minimization of a nonconvex and nonlinear cost function and a neural network gives smaller residual error as compared to a linear structure. The efficacy of complex valued feedforward neural networks for blind equalization of linear and nonlinear communication channels has been confirmed by many studies. In this paper we present two neural network models for blind equalization of time-varying channels, for M-ary QAM and PSK signals. The complex valued activation functions, suitable for these signal constellations in time-varying environment, are introduced and the learning algorithms based on the CMA cost function are derived. The improved performance of the proposed models is confirmed through computer simulations.

Keywords:
Blind Equalization, Neural Networks, Constant Modulus Algorithm, Time-varying channels.
2
5139
An Improved ICI Self-Cancellation Scheme for Multi-Carrier Communication Systems
Abstract:
For broadband wireless mobile communication systems the orthogonal frequency division multiplexing (OFDM) is a suitable modulation scheme. The frequency offset between transmitter and receiver local oscillator is main drawback of OFDM systems, which causes intercarrier interference (ICI) in the subcarriers of the OFDM system. This ICI degrades the bit error rate (BER) performance of the system. In this paper an improved self-ICI cancellation scheme is proposed to improve the system performance. The proposed scheme is based on discrete Fourier transform-inverse discrete Fourier transform (DFT-IDFT). The simulation results show that there is satisfactory improvement in the bit error rate (BER) performance of the present scheme.
Keywords:
OFDM, Intercarrier Interference, InterferenceCoefficients, DFT based Self-ICI Cancellation.
1
11752
An Improved Switching Median filter for Uniformly Distributed Impulse Noise Removal
Authors:
Abstract:
The performance of an image filtering system depends on its ability to detect the presence of noisy pixels in the image. Most of the impulse detection schemes assume the presence of salt and pepper noise in the images and do not work satisfactorily in case of uniformly distributed impulse noise. In this paper, a new algorithm is presented to improve the performance of switching median filter in detection of uniformly distributed impulse noise. The performance of the proposed scheme is demonstrated by the results obtained from computer simulations on various images.
Keywords:
Switching median filter, Impulse noise, Imagefiltering, Impulse detection.