Loading...
Search for:
khaleghi--s
0.016 seconds
Analysis of throughput and delay in a spectrally phase-encoded optical CDMA packet network
, Article 4th IEEE and IFIP International Conference on Wireless and Optical Communications Networks, WOCN 2007, Singapore, 2 July 2007 through 4 July 2007 ; 2007 ; 1424410045 (ISBN); 9781424410040 (ISBN) ; Khaleghi, S ; Jamshidi, K ; Sharif University of Technology
2007
Abstract
In this paper, analysis of the throughput and delay in a spectrally phase-encoded optical code-division multiple-access (OCDMA) system, using a simplified slotted packet network protocol is conducted. Steady-state throughput and average packet delay of the system are derived. In evaluating the performance of the system, only multiple access interference is considered and other sources of noise are neglected. Comparing different systems with the fixed bit rate and chip duration leads us to conclude that increasing the code length will improve the performance of networks with small average activity; but in highly active networks, decreasing the code length will result in a significant...
Fundamental limit for gain and resolution in analog optical edge detection
, Article Optics Express ; Volume 28, Issue 2 , 2020 , Pages 898-911 ; Khavasi, A ; Mousavi Khaleghi , S. S ; Sharif University of Technology
OSA - The Optical Society
2020
Abstract
In this paper, the relation between gain and resolution of an ideal analog optical differentiator in two different cases and their fundamental limits are investigated. Based on this relation, a figure of merit for comparison of the designed differentiators in recent papers is proposed. The differentiators are optimized using this figure of merit, and they are compared with each other to determine the best one. Also, a new differentiator is presented based on the dielectric slab waveguide in which the trade-off between its gain and resolution is easily controllable, and its best operating point is determined. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing...
Compensation of channel and noise distortions combining maximum likelihood based spectral subtraction and Normalization
, Article 2007 IEEE International Conference on Signal Processing and Communications, ICSPC 2007, Dubai, 14 November 2007 through 27 November 2007 ; 2007 , Pages 508-511 ; 9781424412365 (ISBN) ; Babaali, B ; Manzuri Shalmani, M. T ; Sameti, H ; Khaleghi, S ; Sharif University of Technology
2007
Abstract
Channel distortion may dramatically degrade speech recognition performance in a distant environment. Authors in their recent work [1] proposed a novel spectral subtraction method which they named it maximum likelihood based spectral subtraction (MLBSS). They indicated that recognition performance could be improved dramatically by adjusting filter parameters based on recognition results. Previous results show effectiveness of this method in dealing with additive distortion. In this paper we propose an approach for increasing robustness of this method against channel distortion in distant talking environment. We add Cepstral Mean Normalization (CMN) in designing MLBSS filter and show that by...