Maaruf Ali

Chaotic Communications, their applications and advantages over traditional methods of communication

The discovery of randomness in apparently predictable physical systems have evolved into a new science, the science of chaos. Chaotic systems are unstable and aperiodic, making them naturally harder to identify and to predict. Recently, many researchers have been looking at ways to utilize the characteristics of chaos in communication systems and have actually achieved quite remarkable results. This field of communication is called chaotic communication. Chaotic communication signals are spread spectrum signals, which utilize large bandwidth and have low power spectrum density. In traditional communication systems, the analogue sample functions sent through the channel are weight sums of sinusoid waveforms and are linear. However, in chaotic communication systems, the samples are segments of chaotic waveforms and are nonlinear. This nonlinear, unstable and aperiodic characteristic of chaotic communication has numerous features that make it attractive for communication use. It has wideband characteristic, it is resistant against multi-path fading and it offers a cheaper solution to traditional spread spectrum systems. In chaotic communications, the digital information to be transmitted is placed directly onto a wide-band chaotic signal. This paper provides an overview of chaotic communication, chaotic modulation schemes such as: chaos shift keying (CSK), differential chaos shift keying (DSK), additive chaos modulation (ACM) and multiplicative chaos modulation (MCM). Synchronized chaotic systems and direct chaotic communication are also described in this paper.

Highly secured chaotic block cipher for fast image encryption

Highly secured block ciphering with high encryption speed.Combination of chaos and linear Diophantine equation (LDE).Fast and dynamical generation of large permutations.Exploitation of the true accuracy of the computer.Adaptability of the cipher to any type of chaotic system. The real-time constraint for the codec execution and high security level protection are the two most important multimedia encryption requirements. In this paper, a method is presented for the fast generation of large permutation and diffusion keys, which are based on the sorting of the solutions of the linear Diophantine equation (LDE). The coefficients of the LDE are integers which can be dynamically generated from any type of dynamical chaotic systems, as the maximum precision of the computer can be used for the conversion of floating-point chaotic values into integers. This technique yields a fast image block encryption algorithm in which the security level is considerably strengthened. Although the architecture used in this cipher is the one for which the permutation and diffusion are considered as two separate stages, the generation speed of permutation and diffusion keys allows reducing the computational time required by the duplication of the image-scanning stage during the permutation and diffusion operations.

The three-state test for chaos detection in discrete maps

The three-state test (3ST) - a new approach for chaos detection in discrete chaotic maps is presented. The scheme is based on statistical analyses of patterns obtained from ascending sorting of the system states. In addition to its ability for clear discernment between chaotic, quasi-periodic and periodic dynamical systems, the detection of periods of stable cycles is also automated with 3ST. The method is directly applied on data series generated by chaotic maps and does not require a priori knowledge of the equations of the underlying system. It also presents the advantage of not having to depend on the nature of the vector field as well as its dimensionality and is computationally low cost. The effectiveness of the 3ST is confirmed using two well known and widely studied chaotic maps: the logistic map and the Henon 2D map.

Radio Frequency Identification (RFID) Based Toll Collection System

An efficient utilization of communication link between RF Modems over a wireless channel to facilitate vehicle monitoring, vehicle authentication and automated toll collection on the highways is proposed. The system is implemented to automatically register vehicles getting on or off a motorway or highway, cutting the amount of time for paying toll in large queues. The detailed monthly bills will be sent to the customer at the end of the month. The customers could register and get a transmitter module and thereafter would not need to stop at toll booth whenever they get on or off the motorway. The implementation is divided into the design of two modules- the Vehicle Module (Active Tag) and the Base Module. The two modules communicate via RF modem connected to each module. These RF modules communicate over the ISM Frequency Range of 902 -- 928 MHz. The Vehicle module revolves around Atmel 8051 microcontroller. This module contains an LCD panel (16x2), keypad (4x3) and an RF modem interfaced to the microcontroller through Max-232 chip. Microcontroller contains user-specific data associated with vehicle, such as the Registration Number, Engine Number and owners information along with the billing address. The base module comes with a user-interface that allows the administrator to monitor the current activities in the range, including the vehicles in range, their status, and the detailed information about any registered vehicle. Moreover both, base and vehicle module can communicate with each other through chat session.

Diophantine Solutions Based Permutation for Image Encryption

A permutation technique based on the resolution of the system of three independent Diophantine equations is presented. Each Diophantine equation parameters are two positive integers generated from a chaotic system. The resulting solutions are then used for rearranging the positions of the bits and pixels in the ciphered sequence. The performance of such a technique is compared to GRP and Xiang permutation algorithms. From this permutation algorithm an efficient chaos-based block cipher using a chaotic logistic map is proposed. Statistical analyses of this system show a high security level and non-propagation of errors.

The Latest MPEG Standards and Industrial Requirements for Media Streaming

This paper presents an overview of image compression covering JPEG, the MPEG Standards, H.262, H.263 and H.264, VQ, Wavelet and Fractal Transforms. Error resilience in terms of an unequal error protection (UEP) scheme is also covered. The report concludes with a very brief mention of the protocols used in streaming multimedia data.

Fractal Antenna and their Multi-band Performance Evaluation

This paper describes fractal antennas and compares their performance with a standard dipole antenna. Characteristics such as compactness, multi-band operation, broad bandwidth and high efficiency all play an important role these days in wireless communications. However, conventional technologies being used are reaching their limits of improvement to meet the market requirements. An alternative to these conventional technologies is applying fractal structure to antenna design. The fractal properties of self-symmetry and structure at all scales can provide great advantages when applied to antenna designs. Here a very simple fractal antenna -a 2nd stage Koch curve dipole antenna is simulated using the MMANA software and is compared to a standard dipole antenna simulated in the same environment. Results obtained prove the superiority in performance of the Koch curve dipole to that of the standard dipole antenna.