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CHAOTIC COMMUNICATION ,

THEIR APPLICATION AND ADVANTAGES

OVER TRADITIONNAL METHODS OF

COMMUNICATION

BY:RUDRAPPA J SHETTI1KN05EC084

AGENDA• INTRODUCTION• DEFINITION OF CHAOS• CHAOTIC SYSTEM• CHAOTIC SIGNALS• ATTRACTORS• GENERATION OF CHAOTIC COMMUNICATION • PROPERTIES OF CHAOTIC COMMUNICATION • COMPARSION• ADVANTAGES OVER TRADITIONAL METHODS• APPLICATIONS•CONCLUSION• QUESTIONS

CHAOSChaos is aperiodic time-asymptotic behaviour in a deterministic system which exhibits sensitive dependence on initial conditionsThis definition contains three main elements: 1.Aperiodic time-asymptotic behaviour--this implies the existence of phase-space trajectories which do not settle down to fixed points or periodic orbits. For practical reasons, we insist that these trajectories are not too rare. We also require the trajectories to be bounded: i.e., they should not go off to infinity. 2.Deterministic--this implies that the equations of motion of the system possess no random inputs. In other words, the irregular behaviour of the system arises from non-linear dynamics and not from noisy driving forces. 3.Sensitive dependence on initial conditions--this implies that nearby trajectories in phase-space separate exponentially fast in time.

CHAOTIC SYSTEMS

1.Deterministic systems These are systems for which for a given set of conditions the result can be predicted and the output does not vary much with change in initial conditions

All systems can be basically divided into three types:

2. Stochastic systems These systems, which are not as reliable as deterministic systems. Their output can be predicted only for a certain range of values. 3. Chaotic systems Chaotic systems are the most unpredictable of the three systems. Moreover they are very sensitive to initial conditions and a small change in initial conditions can bring about a great change in its output. 

CHAOTIC SIGNALS• Chaotic signals has broadband spectrum , hence the presence of information does not necessarily change the properties of the signal • Power output remains constant regardless of information content• It is resistant against multipath fading and offers cheaper solution to traditional spread spectrum systems• Chaotic signals are aperiodic therefore limited predictability

• Chaotic signals are complex in structure and impossible to predict over long time• chaotic signals appear noise like

•Hence chaotic signal can be used for providing security at physical level

ATTRACTORS

DEFINITION

TYPES OF ATTRACTORSFIXED POINT

LIMIT CYCLE

Chaotic attractor is also known as a strange attractor, a type of attractor (i.e., an attracting set of states) in a complex dynamical system's phase space that shows sensitivity to initial conditions

An attractor is informally described as strange if it has non-integer dimension or if the dynamics on it are chaotic. The term was coined by David Ruelle and Floris Takens

1.FIXED POINTAn attractor that is represented by a particular point in phase space, sometimes called an equilibrium point. As a point it corresponds to a very limited range of possible behaviors of the system.2. LIMIT CYCLE

A limit cycle is a periodic orbit of the system that is isolated.

HISTROY OF CHAOTIC SECURE COMMUNICATION SYSTEM (cscs)First generation 1.Additive chaos masking 2.Chaotic shift keyingSecond generation 1.Chaotic parameter modulation 2.Chaotic non-autonomous modulationThird generation 1.Chaotic cryptosystemForth generation 1.impulsive synchronization based cscs

FIRST GENERATION

channel

The additive chaos masking scheme

The Chua’s oscillator

The state equations for the Chua’s oscillator are given by

At transmitter At receiver

The chaotic shift keying scheme

SECOND GENERATIONThe chaotic parameter modulation.

message signal and its recovered

.

The chaotic non-autonomous modulation.

THIRD GENERATIONchaotic cryptosystem

FOURTH GENERATIONThe impulsive synchronization based chaotic secure communication system.

Time-frame and its components

Within every time frame, the synchronization region has a length of Q and the remaining time interval T -Q is the scrambled signal region

Properties for Communications :-

•Why are we interested in chaos?Certain properties of chaotic systems are appealing for communications such as

1. Low power2. Broadband spectra3. Noise-like appearance4. Auto and cross correlation

properties5. Low multipath interference6. Self-synchronization property

WHY TO BOTHER WITH CHAOTIC COMMUNICATION WHEN THE CONVENTIONAL COMMUNICATION SYSTEM IS MANAGING PERFECTLY

Digital msg sent at Gbps speeds over 115KmsBER of one in ten million [ BER said to be

limited by the equipment rather than the technique itself ]

Hard to detect by eavesdroppersLess risk of interception

Conventional Sinusoidal-based Communication vs. Chaos-based Communication

Conventional Chaotic History: over 100 years old; less than 10 years matured technology Emerging technology

Industrial Heart of world wide None existing base inform. Tech.

Transmission Transmit either Transmit at wide BW bandwidth at information BW or at wide BW (Spread Spectrum)

Relation between Distinct separation Many CC theory & Tech. between info. the./ sys. schemes comm. sys./comm. are described circuits-hardware by chaotic implementation circuits

Contd.

Conventional Chaotic

Single-link Communication System

Conventional ChaoticModulation non-BW expansion BW expansionFormats: Anti-podal signals; Chaotic masking; BPSK; BFSK Parametric modulation Dynamic feedbackSynchronization implementational Chaotic sync. is theory is only loss of fraction still an active research of a dB; No sync. Needed for area; loss from BFSK performance due to implementation is more significant

Contd.

Conven. ChaoticEncryption: No yes

Bit Prob. Error: Exist No known analytic expr. analytic error expr.Complexity: simple complex

Advantages over Traditional Methods

1. At high speed it is easier to generate strong , high power chaotic signals than periodic signals.2. Chaotic signals are not sensitive to initial conditions and have a noise like time series.3. Chaotic transmission has less risks of interception and are hard to detect by eavesdropper.4. In chaotic communication, then on linear characteristic of communication devices are utilized instead of being avoided, this eliminates the complicated measures to maintain linearity.5. Chaotic communication systems can function over a larger dynamical range, with fewer complex components and operate at higher power levels than traditional communication systems

Application of chaos in digital communication

Digital information received information S CHAOS

source encoder

encryptor

channel encoder

modulator

Communication channel

channel decoder

source decoder

CHAOS

demodulator

decryptor

Applications

Used in Ultra Wide Band radio. Used in radar and sonar. Used in oscillator. Used in Chaotic masking . Used in spread spectrum. Used for secure communication

CONCLUSIONA very brief overview on Chaotic communication has been described, explaining the systems, signals,synchronisations and a brief of histroy Chaotic communication .The majority of research carried out , to prove Chaotic communication has advantages over traditinal communication system . At last but not least application of Chaotic communication

BY : RUDRAPPA J SHETTI