Transactions on Networks and Communications

Enhancement of Maximal Ratio Combiner over Log-Normal Fading Channel using Firefly Algorithm

2019-06-24T15:15:55+00:00

Wireless communication system has a great impact in the world of telecommunication and is expected to be a leading role in the developing a nation. However, the system is characterized by multipath propagation effects that lead to signal fluctuation at the receiver, thereby degrading the performance of the system. Maximal Ratio Combiner (MRC) being used to address this problem is characterized with hardware complexity that results in long processing time. Therefore, in this paper enhancement of MRC with closed form expression over Log-Normal fading channel is carried out using Firefly Algorithm (FA) at the receiver. FA create a flashing light in associated with Signal to Noise Ratio (SNR) of the received signal and output the signal with highest SNR. Randomly generated bits used as source data are modulated using M-ary Quadrature Amplitude Modulation (M-QAM) and transmitted over Log-Normal fading channel to generate resultant signals. The resultant signals at varying paths ‘L’ (2, 3, 4) are optimized by FA. The outputs of the FA are combined by MRC to obtain the received signal and converted to baseband through demodulation. A mathematical expression using the Probability Density Function (PDF) of Log-Normal fading channel at varying paths ’L’ for Bit Error Rate (BER) is also derived. The technique is simulated using MATLAB 7.4. The performance is evaluated using Signal-to-Noise Ratio (SNR), Bit Error Rate (BER) and Processing Time (PT). The result shows that, the enhanced MRC (eMRC) gave lower BER values when compared with conventional MRC with reduction in hardware complexity. The eMRC carried out can be used to enhance the performance of wireless communication system.

A New Type of NLFSR Functions with Maximum Periods

2019-06-24T15:15:54+00:00

Nonlinear feedback shift registers (NLFSRs) have received much attention in designing various cryptographic algorithms such as stream ciphers and light weight block ciphers in the provision of high-level security in communication systems. The main purpose of NLFSRs is to generate pseudorandom sequences of bits. NLFSRs are known to be more secure than their linear counterparts. However, there is no mathematical foundation on how to construct an NLFSR with optimal period. In this paper, we propose a new type of NLFSR function of degree 2 with optimal periods. Using our construction method, we propose 639 new functions of this type with optimal periods.

About Some Methods for Software Security

2019-06-24T15:15:55+00:00

This study reviews software security, etc. It studies the methods for the analysis of software security. The problems of software protection are identified. The risks for software projects, their management, determination and categories are studied. Software development process includes the construction of an agreed structure for software development. The design of large distributed systems uses many programming languages, which in turn causes certain difficulties. That is, security in these cases is not provided. Software security is a set of measures aimed at its protection. Security in software exploitation is also a key issue. Software security is understood as its functioning without any problems. Information security threats arise in the process of software exploitation.

Selecting the Optimal Web Service Composition Based on QoS

2019-06-24T15:15:53+00:00

The fast spread of web services in our businesses and day-to-day lives has made QoS an essential aspect for both the service providers and consumers. The main problem is how the consumer obtains a high comprehensive quality composite service when there are a large number of web services available; the choice of the optimal path depends on the QoS for every atomic service. Our contribution is studying the influence of the reputation factor in the process of selecting the optimal path in the absence of one of four factors (Availability, Reliability, Response Time, and Price) and the possibility of covering for this absence. We have used the reputation factor when calculating the QoS by using artificial bee colony algorithm for selecting the optimal web service composition; then we analyzed the impact of reputation on the process of selecting web service composition in terms of the QoS and accuracy of the solution. Also, we studied the impact of the reputation factor in the case of the absence of one of the four factors through three experiments and a set of comparisons. The result was that the reputation factor could cover factors such as availability, Response Time, and technical support. We used multiple linear regression and polynomial regression to show the prediction of the reputation factor using the four other factors. The result had higher confidence when we used multiple polynomial regression where the Residual Sum of Squares (RSS) was less than the multiple linear regression. In addition, we analyzed the association between reputation and the four other factors using ANOVA test; the result indicates that there is a significant association between reputation and (availability, response time, and price), but the association is not significant with the reliability.