Muhammad Tahir Naseem

Reversible watermarking using Residue Number System

Reversible watermarking is a process in which the watermark is embedded in such a way that when the watermarked image passes through the authentication process, the original image is also recovered exactly along with watermark. Restoring the original image is important for the applications such as medical, military and law-enforcement etc. Reversible fragile watermarking scheme is presented by introducing the Residue Number System (RNS). One redundant bit is added as a watermark to some of the pixels and rest is changed into residues. By adding an extra bit, the watermarked pixel becomes nine bits and the residues became nine bits which makes the medical image secure by confusing the attacker that where the watermark is embedded.

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.

QoS and rate enhancement in DVB-S2 using fuzzy rule based system

Adaptive Coding and Modulation (ACM) is one of the most promising features in many communication systems like WIFI, WiMAX and DVB-S2, in terms of throughput and link utilization. In this way the transmission parameters like power, code rate and modulation symbol are adapted according to the varying link conditions. In this paper we propose a Fuzzy Rule Based System (FRBS) for an efficient ACM in DVB-S2 standard. We have taken it as a constrained optimization problem in which the link reliability and throughput is maximized, while power constraint is satisfied. To do so we have selected the standard transmission Modulations and Codes (MODCODs) optimally using FRBS, according to the DVB-S2 downlink channel state information (CSI) at different sites. The FRBS module can easily be embedded in the ACM management module (AMM) which is a software module. Significance of the proposed scheme over other schemes is shown through simulations.

Chaos based invertible authentication of medical images

Digital image watermarking is used as a data hiding method to enhance medical confidentiality, integrity and data security. Extreme care should be done in medical image watermarking because the added additional information should not degrade the image quality. In this paper we are presenting a fragile and reversible watermarking based on chaotic key. ROI and NROI part of image are separated and data is embedded in NROI part of image based on a chaotic key. Image quality is measured with a well known figure-of-merit such as PSNR. Our results show that the watermark is highly secure, fragile and imperceptible after embedding.

Dynamic resource allocation in OFDM systems using DE and FRBS

Dynamic allocation of the resources for optimum utilization is one of the most important fields of study in engineering as well as other disciplines nowadays. In this process the available resources are allocated in such a way that these resources are maximally utilized to enhance the overall system throughput while satisfying certain constraints at the same time. In this paper a similar constrained optimization problem is focused for Orthogonal Frequency Division Multiplexing OFDM environment, in which the transmission parameters namely code rate, modulation scheme and power are adapted in such a way that overall system data rate is maximized with a constrained bit error rate and transmit power. This is a highly non-linear problem that cannot be solved by ordinary linear optimization techniques. A Fuzzy Rule Base System FRBS is proposed for adapting the code rate and modulation scheme while Differential Evolution is used for choosing the optimum power vector. The proposed scheme is compared with other schemes.

Efficient link adaptation in OFDM systems using a hybrid intelligent technique

Adaptive communication for rate enhancement and link survival is a recent area of interest. In adaptive communication, transmission parameters like transmit power, code rate and modulation scheme are chosen in an adaptive manner to match the link conditions and quality of service demand at that transmission interval. But this is a highly non linear phenomenon and a constrained optimization problem. In this paper, we have investigated Simulated Annealing algorithm in conjunction with a fuzzy rule base system (SAFRBS) for adaptive coding, modulation and power in an orthogonal frequency division multiplexing environment. The cases of fixed and adaptive communication are compared and results are shown through the simulations.

An intelligent link adaptation scheme for OFDM based hyperlans

Adaptive communication is becoming requirement of every communication system for effective utilization of available radio resources. In this approach the transmission parameters like code rate, modulation size and available power are dynamically chosen so that the overall system throughput is maximized while certain constraints like bit error rate are satisfied. In this paper a similar constrained optimization problem is solved by optimally choosing the said parameters with the help of Differential Evolution algorithm with a Fuzzy Rule Based System (DE-FRBS) in an OFDM environment, in this proposal the FRBS is used to adapt the code rate and the modulation scheme according to channel state information (CSI) and desired quality of service (QoS) while DE is employed to find the optimum power vector (OPV) to be transmitted over OFDM subcarriers. Product codes and Quadrature Amplitude Modulation (QAM) are used as coding and modulation schemes respectively. Product codes are considered much powerful in terms of error correction capability. Significance of the proposed scheme is shown by the simulations.

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.