Informatics Publishing Limited

R. Raja Kumar ¹, A. Sampath ¹, P. Indumathi ²

Affiliations
1 Mathematics Department, Sathyabama University, Chennai, IN
2 Electronics Engineering Department, M.I.T Campus, Anna University, Chennai, IN

Abstract

The principal design objective of this paper is to facilitate extremely secure digital communication using chaotic shift keying in existing frequency-hop spread spectrum systems. Generally in chaotic shift keying, the incoming digital bit stream is mapped onto one of the available chaotic signals. Our scheme proposes the use of antipodal chaotic signals, which means they are signals which are out of phase with each other by 180°. Data bits 0 and 1 can be mapped onto either of the antipodal signals using required convention. Also, in FH-spread spectrum (FH-SS) techniques, there exists a p-n code generator based on the output of which the frequency synthesizer selects a particular carrier frequency. Usual FH-SS systems use MFSK modulation in the stage following the frequency hopper. As our case involves the use of chaotic reference signals and their basic shapes need to be preserved throughout, we propose the use of binary frequency shift keying. The digital data, which is now in the form of chaotic signals, is turned into a BFSK signal. This resultant signal is mixed with a carrier frequency at the frequency synthesizer. This carrier is chosen by the frequency hopper, whose output, in turn depends on the output of a p-n sequence. We assume the transmission channel to contribute additive white noise. At the receiver, we propose to perform FSK demodulation as a first stage recovery to get back the chaotic signal. Now this recovered signal is either an exact copy of the chaotic reference signal or its inverse. To decide which of the two was sent by the transmitter, we can use a correlator receiver, which uses a locally generated chaotic reference signal. Keywords: Chaotic shift keying, orthogonal chaotic

Keywords

Chaotic Shift Keying, Orthogonal Chaotic Shift Keying, Pulse Code Modulation

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R. Raja Kumar ¹, A. Sampath ¹, P. Indumathi ²

Affiliations
1 Mathematics Department, Sathyabama University, Chennai-600119, IN
2 Electronics Engineering Department, MIT Campus, Anna University Chennai-600044, IN

Abstract

In this paper we demonstrate a way to secure optical communication. Chaos as a tool for information security is gaining wide acceptance for its inherent simplicity and ability to secure a communication link from the physical layer compared to other application layer-software encryption methods. Though they are lesser secured than the physical layer systems, the software techniques are still the order of the day. Since the physical layer techniques are still in the nascent stages of growth, this paper tries to go one step further, to utilise the chaotic scheme in securing optical communication. The idea is to generate a chaotic signal in the form of current and adding it to the message at the transmitter where the whole of this current drives an optical source-laser. At the receiver the same chaos signal is generated by prior synchronization. The received signal is photodetected to get the equivalent current. The difference between this current and the internally generated matched chaos yields the message. The efficiency of this technique is investigated for line of sight communication by modelling a free space optic channel (FSO) and accounting for attenuation caused by the same.

Keywords

Chaos, Cryptography, Secure Optical Communication

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R. Raja Kumar ¹, A. Sampath ¹, P. Indumathi ²

Affiliations
1 Mathematics Department, Sathyabama University, Chennai-119, IN
2 Electronics Engineering Department, MIT Campus, Anna University, Chennai, IN

Abstract

This paper proposes a Frequency Hopped Spread Spectrum (FHSS) communication system using chaos and its synchronization. The spread spectrum technique of frequency hopping uses pseudorandom number (PN) generator to produce a random sequence of frequencies. A new class of signature sequences for use in Frequency Hopped Spread Spectrum communication systems is proposed. In arriving at these sequences, the theory of chaos has been used. The correlation properties of these chaotic sequences are similar to random white noise. The numbers and lengths of chaotic sequences are not restricted like m sequences. The performances of chaotic sequences in multiple access communication are shown to be similar to that of PN sequences. Furthermore, due to their noise like appearance, chaotic sequences outperform PN sequences in low probability of intercept. In this method the spreading sequences change from one bit to the next in very random like fashion, causing undesired interception to be very difficult. The synchronization of the system is also proposed.

Keywords

Chaotic Sequences, Chaotic System, FHSS, PN Sequences, Synchronization.

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R. Raja Kumar ¹, A. Sampath ¹, P. Indumathi ²

Affiliations
1 Mathematics Department, Sathyabama University, Chennai-119, IN
2 Electronics Engineering Departments, MIT Campus, Anna University, Chennai, IN

Abstract

In this paper we examine one of the recently proposed chaotic image encryption algorithms, based on chaotic map lattices (CML). We also study and examine another algorithm that could satisfy expectations of efficiency and security in the case of digital colour image encryption. The proposed algorithm provides more security and secrecy to the colour digital images as compared to the security provided by the existing CML based algorithm suggested by Pisarchik. At the end, we show the results of a security analysis and a comparison of both schemes.

Keywords

Chaotic Map Lattice, Digital Image, Image Encryption, Security.

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A. Gangopadhyay ¹, A. Sampath ¹, B. Velury ², D. P. Sen Gupta ¹, D. R. Ahuja ¹

Affiliations
1 National Institute of Advanced Studies, IISc Campus, Bengaluru 560 012, IN
2 Power System Operation Corporation Limited, 29, Race Course Cross Road, Bengaluru 560 009, IN

Abstract

Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected to persist despite planned additions of conventional power. Using four illustrative scenarios based on different assumptions, we estimate the additional contributions wind and solar power sources could make to reduce these deficits by FY2022. The method developed estimates expected hourly deficits in FY2022 from projected unrestricted demands and expected availability from conventional sources. We estimate that additional 8000-8700 MW (11 BU) of wind and 3300-3500 MW (5 BU) of solar power would reduce the annual deficit by approximately three-fourths. A recommended pumped hydro storage facility will reduce the deficits further by 10% and help in meeting the daily peaks in demand.

Keywords

Conventional Energy Sources, Electricity Shortage, Pumped Hydro Storage, Wind and Solar Power.

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B. R. Srinivasan ¹, A. Sampath ²

Affiliations
1 Bharathidasan University, Tiruchirapalli— 620 023 Tamilnadu, IN
2 Sri Vasavi College, Erode-631 316, Tamihiadu, IN

Abstract

An Elementary Proof of the Prime Number theorem with a Remainder Term.

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