Interference Cencellation for Ds-Ss using Rectagular Window LTV Filter and Sliding Discrete Time Fourier Transforms (DSTFT) Techniques
N. Murugendrappa1, A. G Ananth2

1N. Murugendrappa, Department of electronics, Jnana Sahyadri, Shankaraghatta, Shimoga
2A.G Ananth, RV center for Cognitive Technologies, RVCE Campus, Bangalore.
Manuscript received on June 04, 2013. | Revised Manuscript received on June 28, 2013. | Manuscript published on July 05, 2013. | PP: 136-138 | Volume-3 Issue-3, July 2013. | Retrieval Number: C1635073313/2013©BEIESP
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Abstract: Interference suppression in spread spectrum communication systems is very essential for achieving maximum system performance. Existing interference suppression methods do not perform well for most types of non stationary signals. First the interference suppression schemes based on orthogonal timefrequency decomposition, wavelets and arbitrary time-frequency signals are considered. These methods often reduce interference substantially; however the minor changes in interference characteristics such as the center frequency may require changes in the mathematical modeling. The rectangular window methods for fractional Fourier transform with accompanying blind interference excision scheme appears very promising for mitigating time-frequency dominated interference. The present work includes simulations with narrowband interference and comparison of the performance and illustration with different methods. The performance of the rectangular window is evaluated with existing Discrete Short time Fourier Transform algorithm (DSTFT) for filtering with various Jamming-to-Signal Ratios (JSR) starting from 40 dB to 100 dB in steps of 10 dB. Model simulation results with proposed algorithm shows considerable improvement in Signal-to-Noise Ratio (SNR) for the DS-SS signal compared to that of STFT filtering. The results are presented and discussed in the paper.
Keywords: (SDTFT), (JSR), (SNR), DS-SS.