Mitigating Drawbacks of Logistic Map for Image Encryption Algorithms

This paper identifies and analyses some drawbacks of the logistic map which is still one of the most used chaotic maps in image encryption algorithms. As some of the disadvantages are caused by inappropriate implementations of the logistic map, this paper proposes a set of rules which should lead to enhancement of the desired chaotic behavior. Probably the most important rule introduces alternating value of parameter utilized by the logistic map. With careful choice of values and an adapted quantization technique, some of the issues should be fixed and theoretically also the values of numerical parameters should be improved. These assumptions are verified by applying the proposed set of rules on an algorithm from our prior work. Effects of the proposed rules on the used algorithm are investigated and all necessary modifications are thoroughly discussed. The paper also compares obtained values of commonly used numerical parameters and computational complexity with some other image encryption algorithms based on more complex chaotic systems

Demonstration of Multimode Optical Fiber Communication System using 1300 nm Directly Modulated VCSEL for Gigabit Ethernet

In the recent years, the optical networks have grown to unexpected dimensions. The growth of active users and growing demand for data services set high requirements to network providers. Driving forces of this growth are multimedia, cloud computing and web services which set high bandwith demand. The majority of currently deployed optical networks utilize passive or active network structure using dominantly singlemode optical fiber (SMF). SMF is believed to be the better choice over multimode optical fiber (MMF) for high speed optical fiber communication systems. And in some applications it definitely is. MMF has found use especially for short distance communication as it easily supports distances required for interconnecting building, data centres or campuses. In this paper we present a simulation model of 1000BASE-LX Ethernet with MMF using different optical modulation techniques. The aim of this article is to demonstrate possibilities of MMF based 1000BASE-LX Ethernet with directly modulated vertical-cavity surface-emitting laser (VCSEL)

Utilization of 10 Gbps DWDM System with Duobinary Modulation into Passive Optical Network

Passive optical networks are considered to be the most promising solution for future access networks. Growing demand for capability and high bit rate transmission has become an important part of metropolitan optical communication networks in recent years. Currently deployed 1 Gbps passive optical networks do not seem to be suitable for future demands. This paper deals with the utilization of 10 Gbps DWDM (Dense Wavelength Division Multiplex) in PON (Passive Optical Network) using simulation tool OptSim. Our goal was to create passive optical network based on the real passive optical distribution path using OTDR and to show the possibility of utilization of DWDM in such network. We also describe optical duobinary modulation as a future candidate for such network and its advantages over commonly used intensity modulation. Performance of DWDM-PON with optical duobinary modulation and intensity modulation with direct detection is analyzed using BER (Bit Error Rate) and Q factor measurements

Utilization of 10 Gbps DWDM System with Duobinary Modulation into Passive Optical Network

Passive optical networks are considered to be the most promising solution for future access networks. Growing demand for capability and high bit rate transmission has become an important part of metropolitan optical communication networks in recent years. Currently deployed 1 Gbps passive optical networks do not seem to be suitable for future demands. This paper deals with the utilization of 10 Gbps DWDM (Dense Wavelength Division Multiplex) in PON (Passive Optical Network) using simulation tool OptSim. Our goal was to create passive optical network based on the real passive optical distribution path using OTDR and to show the possibility of utilization of DWDM in such network. We also describe optical duobinary modulation as a future candidate for such network and its advantages over commonly used intensity modulation. Performance of DWDM-PON with optical duobinary modulation and intensity modulation with direct detection is analyzed using BER (Bit Error Rate) and Q factor measurements

Image Encryption Algorithm with Plaintext Related Chaining

This paper describes a plaintext related image encryption algorithm that utilizes the Mojette transform for computation of bins that are subsequently combined with pixels of the processed image. While the bins are computed solely from pixel intensities of a plain image and also the combination depends only on intensities of plain image pixels, the parameters of bins are rearranged according to used key. This design results in a great sensitivity of the proposed image encryption algorithm to both plain images and keys, which is verified by a set of experiments. The paper also tests the resistance of the proposal against statistical and differential attacks by means of commonly used measures as correlation coefficients, entropy, NPCR and UACI. Furthermore, the paper analyses computation speed reached by the proposed solution. Computed values of all parameters are discussed and then compared with results obtained by some recent plaintext related image encryption algorithms

On the 100 Gbps DWDM with Optical Carrier Suppression Modulation

This paper investigates the transmission performance of 16-channel DWDM (Dense Wavelength Division Multiplexing) system with two complex Optical Differential Quadrature Phase Shift Keying modulator configurations using 2 LiNb MZM (Mach-Zehnder Modulator) and 3 LiNb MZM. The link performance is evaluated for 100 Gbps data rate per channel in a total 750 km single mode fiber link. The perfomance is analyzed in terms of forward power, reflected power and bit-error rate of the received signal. From the simulation results we prove, that the link performance can be improved by adopting the high efficiency optical modulation

Mitigation of Fiber Nonlinear Effects in 1.28 Tbps DQPSK Modulated DWDM System

The main limitation factor of high capacity multichannel DWDM (Dense Wavelength Division Multiplexing) systems are fiber nonlinear effects. The optical signal is severely degraded due to fiber nonlinear effects also known as Kerr fiber nonlinearity. Nonlinear effects under investigation are self-phase modulation (SPM) and cross-phase modulation (XPM). There are several methods to compensate these nonlinear distorts, some less or more effective. Nonlinear distort due to SPM and XPM can be effectively mitigated through implementation of optical DQPSK modulation over commonly used intensity modulation known as OOK (On-Off Keying). This paper presents a numerical simulation model of 1.28 Tbps DWDM system with optical DQPSK modulation. We present several scenarios and methods to mitigate fiber nonlinear effects including Fractional Fourier Transform (FrFT). Linear and nonlinear effects are considered together, so we implement the inline FrFT module in the optical domain which causes a time-frequency plane rotation to mitigate combined linear and nonlinear effects. The performance of proposed 1.28 Tbps DQPSK modulated DWDM system is evaluated in term of bit error rate (BER) and Q factor value

Analysis of possibilities for measurement effect of visibility in experimental FSO system

Nowadays, wireless optical systems are very popular because they offer a a lot of advantages including high speed transmission, high security levels, and low maintenance costs. One of these wireless optical systems is Free Space Optics (FSO). However, their primary drawback relates to the type of transmission medium used. Atmospheric channel is chosen to be the transmission medium for FSO systems. The resulting attenuation relates with all inhomogeneities that occur in the atmosphere. Concentration of water particles represents inhomogeneities which increase the levels of attenuation. Weather conditions are characterized by speciffc concentration of these particles. Visibility is one of the most crucial parameters for FSO communication. It is very important to monitor this parameter in order to switch between primary optical line and backup secondary Radio Frequency (RF) line. The focus of this paper is to analyze and evaluate visibility measurement in FSO system deployed in TUKE (Technical University of Kosice) campus. The measurement of different weather parameters for this system is triggered on TUKE. The Switching method is based on monitoring visibility as the primary parameter. Different measurement approaches provide different processing speeds. Faster and more accurate switching ensures stable system without disruption