Ijaz Mansoor Qureshi

Correction of faulty sensors in phased array radars using symmetrical sensor failure technique and cultural algorithm with differential evolution.

Three issues regarding sensor failure at any position in the antenna array are discussed. We assume that sensor position is known. The issues include raise in sidelobe levels, displacement of nulls from their original positions, and diminishing of null depth. The required null depth is achieved by making the weight of symmetrical complement sensor passive. A hybrid method based on memetic computing algorithm is proposed. The hybrid method combines the cultural algorithm with differential evolution (CADE) which is used for the reduction of sidelobe levels and placement of nulls at their original positions. Fitness function is used to minimize the error between the desired and estimated beam patterns along with null constraints. Simulation results for various scenarios have been given to exhibit the validity and performance of the proposed algorithm.

A GA-FRBS Based Rate Enhancement Scheme for OFDM Based Hyperlans

Adaptive communication is need and feature of every current communication system. In this technique the transmission parameters are adapted in such a way that overall system throughput may be enhanced while satisfying certain number of constraints. In short this is a constrained optimization problem. In this paper a similar constrained optimization problem is focused and solved by making certain parameters adaptive that are code rate, modulation scheme and transmit power in a multicarrier OFDM environment. For adapting the said parameters a Fuzzy Rule Base System (FRBS) is used in conjunction with Genetic Algorithm (GA). So FRBS and GA suggest the optimum code rate, modulation symbol and power with respect to the channel state information (CSI) given at any instance that can maximize the throughput while satisfying constraints like power and bit error rate (BER). Product codes and Quadrature Amplitude Modulation (QAM) are used as coding and modulation schemes respectively. Simulation results show the significance of proposed scheme.

A fuzzy rule base system aided rate enhancement scheme for OFDM systems

Adaptive communication is one of the key attributes of almost all communication systems nowadays. In this way, available resources are optimally used to enhance the overall throughput of system while satisfying certain constraints. In this paper a similar constrained optimization problem is formulated. A fuzzy rule based system (FRBS) is designed and used for solution of the problem. The parameters being optimized for the system are forward error correction (FEC) code and modulation scheme. FRBS suggests how to change these parameters according to varying channel state information (CSI) on Orthogonal Frequency Division Multiplexing (OFDM) channel that throughput can be maximized. Multilevel codes, Quadrature Amplitude Modulation (QAM) are used as FEC and Modulation scheme respectively. Moreover, a modified iterative algorithm is used for decoding the multilevel codes. Significance of proposed scheme is shown by simulations.

Adaptive resource allocation for OFDM systems using fuzzy rule base system water-filling principle and product codes

Adaptive resource allocation is one the key characteristics of almost all communication systems nowadays. In this technique, available resources are optimally used to enhance the overall throughput of system while satisfying certain number of constraints. In this paper a similar constrained optimization problem is formulated and a fuzzy rule based system (FRBS) is designed and used for solution of the problem. The parameters being optimized for the system are practical channel codes, modulation symbol and the transmit power. FRBS suggests how to change coding scheme and modulation symbol while water-filling algorithm suggests the adaptive power according to varying channel state information in Orthogonal Frequency Division Multiplexing (OFDM) channel so that throughput can be maximized. Product codes, Quadrature Amplitude Modulation (QAM) are used as FEC and Modulation scheme respectively. Moreover, a modified iterative algorithm is used for decoding the product codes. Significance of proposed scheme is shown by simulations.

Robust watermarking for medical images resistant to geometric attacks

Digital image watermarking is considered as a patent method to enhance medical data security, confidentiality and integrity. Medical image watermarking requires extreme care when embedding additional data, given their importance to clinical diagnosis, treatment, and research. In this paper, a novel image watermarking for medical images is presented which is robust to geometric attacks like rotation, scaling, translation or combination of these. The watermark is embedded in the feature space of the image, as embedding the watermark in feature space makes it invariant against geometric attacks (translation, scaling, rotation and combination of these) and then Arnold transform which is considered as a chaotic scrambling is applied on the watermarked image to make the watermark more secure. Moreover, the proposed watermarking scheme is blind as the watermark is extracted without knowing the original image at receiver end. Experiment results demonstrate that watermark is robust against geometric attacks.