Habibulla Khan

Multiuser detection for DS-CDMA systems over Nakagami-m fading channels using particle swarm optimization

This paper presents a robust multiuser detection technique for direct sequence-code division multiple access (DS-CDMA) systems over Nakgami-m fading channels in the presence of impulsive noise. Robust M-decorrelating detector to demodulate non-coherent DPSK signals is implemented by using the particle swarm optimization (PSO) algorithm. The PSO algorithm is used to obtain optimum M-estimates by minimizing an objective function, which is a sum of less rapidly increasing function of residuals. Simulation results are provided to show the evolutionary behavior and efficacy of the modified-Hampel based M-estimator in comparison with linear decorrelating detector, the Huber and the Hampel estimator based detectors.

Speech Enhancement and Recognition of Compressed Speech Signal in Noisy Reverberant Conditions

Speech compression, enhancement and recognition in noisy, reverberant conditions is a challenging task. In this paper a new approach to this problem, which is developed in the framework of probabilistic random modeling. speech coding techniques are commonly used in low bit rate analysis and synthesis . Coding algorithms seek to minimize the bit rate in the digital representation of a signal without an objectionable loss of signal quality in the process. Speech enhancement aims to improve speech quality by using various algorithms This paper deals with multistage vector quantization technique used for coding of narrow band speech signals. The parameter used for coding of speech signals are the line spectral frequencies, so as to ensure filter stability after quantization. A new approach incorporates the information about statistical random nature of uncompressed speech signal using LBG algorithm .The code books used for quantization are generated by using Linde, Buzo and Gray(LBG) algorithm. Speech model is characterized by LPC coefficients and parameterized by the coefficients of the reverberation filtersThe results of the multistage vector quantizer are compared with unconstrained vector quantization Technique. The performance of quantization is measured in terms of spectral distortion measured in dB, Computational complexity measured in KFlops and Memory Requirements measured in Floats. From the results it can be proved that multistage vector quantization is having better spectral distortion performance, less computational complexity and memory requirements when compared to unconstrained vector quantization. The proposed approach yields significantly estimating the parameters from the data , better performance in both signal to noise ratio and subjective filter methods.

Multiuser detection using comprehensive learning PSO over GK fading channels in impulsive noise

The direct sequence-code division multiple accesses (DS-CDMA) signals are transmitted over multipath channels that introduce fading and shadowing. Combined effect of multipath fading and shadowing along with multiple access interference (MAI) and inter-symbol interference (ISI) worsens the system performance. Further, experimental results have confirmed the presence of impulsive noise in wireless mobile communication channels. Hence, this paper presents a comprehensive learning particle swarm optimization (CLPSO) based multiuser detection technique for DS-CDMA systems over generalized-K (GK) fading channels in presence of impulsive noise. Maximal ratio combining (MRC) receive diversity is also incorporated to mitigate the effects of fading and shadowing. Performance of proposed M-decorrelator is studied by evaluating average error rate. Simulation results show that the proposed M-decorrelator performs better in the presence of fading, shadowing and heavy-tailed impulsive noise when compared to least squares, Huber and Hampel M-estimator based detectors.

Blind Multiuser Detection in Nakagami-m Fading Channels with Impulsive Noise

Experimental results have confirmed the presence of impulsive (heavy-tailed) noise in different wireless communication channels. In direct sequence-code division multiple accesses (DS-CDMA) systems, the signals are transmitted over multipath channels that introduce fading. Multipath fading along with multiple access interference (MAI) and inter-symbol interference (ISI) in impulsive noise environment degrades the system performance. This paper presents a technique for blind multiuser detection in DS-CDMA communication systems over Nakagami-m fading channels with impulsive non- Gaussian noise. Expression for average probability of error of an M-decorrelator is derived for the demodulation of BPSK signals over single-path Nakagami-m fading channel. A new M -- estimator is proposed for robustifying the detector and its performance is studied and analyzed by evaluating probability of error with the derived expression. Simulation results indicate that the proposed blind multiuser detector performs better in highly impulsive noise environment.

Robust blind multiuser detection in DS-CDMA systems over Nakagami-m fading channels with impulsive noise including MRC receive diversity

This paper presents robust blind multiuser detection in direct sequence-code division multiple access systems (DS-CDMA) over Nakagami-m fading channels with impulsive noise including maximal-ratio combining diversity. An M-estimator based structure for non-coherent demodulation of differentially phase shift keyed (DPSK) signals transmitted over a synchronous CDMA flat-fading Nakagami channels with impulsive noise is studied and analyzed. A new M-estimator is proposed for robustifying the detector and an approximate expression for average probability of error of non-coherent DPSK signals is derived using an approximation to generalized Marcum-Q function over single-path Nakagami-m fading channels. Simulation results are presented to evaluate the performance of the proposed robust blind multiuser detector in comparison with the linear decorrelating detector, Huber and Hampel estimator based detectors.

Reduction of False Microaneurysms in Retinal Fundus Images using Fuzzy C-Means Clustering in terms NLM Anisotropic Filter

The identification of MAs is an important phase in the research and grading of suffering from diabetes retinopathy. We present clustering strategy to identify the microaneurysms from the optic disk and cup in the retinal fundus pictures. Fuzzy C-Means (FCM) Clustering is used for clustering the information in which the information factors are grouped with different account level. The first and major phase is preprocessing function, in which the optic cup and disk of the feedback picture is being turned. Originally the optic hard disk is turned in some position and the range between the information factors is calculated and a group is established in accordance with the centroid. For retrieving micro aneurysms in all retinal images in our previous work we used SVM Classification filter in Fuzzy C-Means Clustering. In this paper we propose an effective filtering technique for micro aneurysms detection in retinal image preprocessing. Instead of SVM Filtering technique we used NLM in terms of Anisotropic Filter to process retinal images. Tested on the various simulated retina data repositories combining rotation and scaling, the developed method presents good results and shows robustness to rotations and scale changes.

Robust Multiuser Detection in Asynchronous DS-CDMA Systems over Nakagami-m Fading Channels

This paper presents a new M-estimator based robust multi-user detection technique in asynchronous direct sequence-code division multiple access systems over Nakagami-m fading channels with impulsive noise. A new M-estimator, which performs well in the heavy-tailed impulsive noise, is proposed and analyzed for robustifying the detector. Average probability of error is derived and the performance of the new M-estimator based multi-user detector is evaluated in comparison with the linear decor relating detector, Huber and Hampel estimator based detectors. Simulation results show that the proposed M-estimator based detector performs well with little attendant increase in computational-complexity. The proposed robust multi-user detection technique is also extended to blind version of asynchronous CDMA channels.

Outage performance analysis of basic receive diversity combining schemes in Nakagami-0.5 fading channel

This paper presents a study on the outage performance analysis of basic receive diversity combining schemes in terms of outage probability and average outage duration over Nakagami-0.5 fading channels. Recent attention has been given to Nakagami-0.5 fading channel as a special case of Nakakgami-m fading channel with m = 0.5 and as a worst-case (severe) fading scenario. Closed-form expressions for outage probability and average outage duration are derived for selection combining (SC), equal gain combining (EGC) and maximal-ratio combining (MRC) diversity schemes. The expressions derived are numerically evaluated to study the effect of diversity order and multipath intensity profile (MIP) on the system performance.

Implementation of Running Average Background Subtraction Algorithm in FPGA for Image Processing Applications

In this paper a new background subtraction algorithm was developed to detect moving objects from a stable system in which visual surveillance plays a major role. Initially it was implemented in MATLAB. Among all existing algorithms running average algorithm was choosen because of low computational complexity which is the major parameter of time in VLSI. The concept of the background subtraction is to subtract the current image with respect to the reference image and compare it with to the certain threshold values. We propose a new real time background subtraction algorithm which was implemented with verilog hdl in order to detect moving objects accurately. Our method involves three important modules background modelling; adaptive threshold estimation and finally fore ground extraction. Compared to all existing algorithms our method having low power consumption and low resource utilization. Here we have written the core processor Microblaze is designed in VHDL (VHSIC hardware description language), implemented using XILINX ISE 8.1 Design suite the algorithm is written in system C Language and tested in SPARTAN-3 FPGA kit by interfacing a test circuit with the PC using the RS232 cable. Area and the speed of the algorithm are also evaluated.

sEMG based human computer interface for robotic wheel

In this paper, a real-time experimental of Hand Gesture sEMG signal using artificial neural networks for Wheel Vehicle Control is proposed. The raw SEMG signals been captured from SEMG amplifier, up to 8 channels of NI-DAQ card responses data will be combined and a fine tuning step by using pattern classification. The database then been build and use for real-time experimental control classification. Captured data will send through serial port and Wheel Machine will receive and move accordingly. The detail of the experiment and simulation conducted described here to verify the differentiation and effectiveness of combined channels sEMG pattern classification of hand gesture for real-time control.