A combinatorial approach for enhancing the performance of TH-PPM UWB systems: chaotic vs. classical codes sequences

Abstract

In this paper, we propose a method to minimize the Multi-User Interference (MUI) caused by Multiple Access (MA) in a Time Hopping Ultra Wide Band (TH-UWB) system with Line-Of-Sight (LOS) multipath channel in a residential environment IEEE 802.15.4a. We consider both synchronous and asynchronous cases.The choice of codes allowing multiple access is crucial for minimizing the MUI and for enhancing the system performance. The minimization of the MUI is formulated as a Combinatorial Optimization Problem (COP) and solved by means of an efficient generic optimization method called Guided Local Search (GLS) (Voudouris in Guided local search for combinatorial optimisation problems, 1997). In this context, we exploit the richness of chaotic sequences with respect to topologic properties. Simulation results based on the Binary Error Rate (BER) show that optimized chaotic sequences outperforms the classical code sequences.

A New Chaos-based Text Encryption/Decryption to Secure Cloud Computing

“…Chaos means how simple systems can generate complex behavior and therefore chaos based encryption refers to how complicated the encryption and decryption process can be. Indeed, the chaotic defines a particular state of a system whose behavior is never repeated, very sensitive to the initial conditions and unpredictable in the long term [28][29][30]. For this, chaos is one of the most theories with several advantages, such as high speed, high security, efficient and adaptable to real-time encryption.…”

A New Chaos-based Text Encryption/Decryption to Secure Cloud Computing

“…The identification of the characteristics of chaotic systems is made using tools such as: the bifurcation diagram and the Lyapunov exponents and moreover [12,29,30].…”

Fast chaotic optimization algorithm based on spatiotemporal maps for global optimization

“…It represents the relative importance of penalties with respect to the solution cost and is of great significance because it provides the means to control the influence of the information gathered during the search process. In this paper initial value of this parameter is usually set to λ p = 0.0001 [3]. The penalty vector is defined such as:…”

“…Chaotic systems are currently in use in a number of different areas such as watermarking, cryptography, communication and so on [1][2][3]. In general, chaos characterized by their high sensitivity to initial conditions assessed by Lyapunov exponents and some properties like stochasticity and ergodicity, strange attractor with self-similar fractal pattern and pseudo-random behavior of chaotic sequences are the most attractive features that caused significant interest.…”