IJCNIS Vol. 12, No. 5, Oct. 2020
Cover page and Table of Contents: PDF (size: 268KB)
Use of spread spectrum systems in telecommunications is studied. It is shown that spread spectrum techniques can substantially enhance noise and interference immunity in the currently deployed information transmission networks. Primitive polynomials are proposed to obtain respective spreading codes. A spreading code consisting of 1023 chips is synthesized and its characteristics are studied.
It is deduced that powerful interferences can exceed dynamic range of the receiving part of the system and, as a result, deteriorate information transmission. To overcome this problem, utilization of limiters is proposed, in which limitation level equals that of the internal noise of the receiving part. Computer simulation is employed to test the performance of the proposed solution. Performance of the spread spectrum system for information transfer is studied both without the limiter and with the limiter.
Research results show that, for binary modulation, performance of the system with limitation and without limitation is nearly identical while limiters can substantially reduce requirements for the dynamic range.
Compared to the existing approaches, it is proposed to use the synthesized spreading coding sequence with the limitation technique in practical implementations of those telecommunication networks, in which noise immunity and transmission concealment are required, such as in unmanned aerial vehicles. This can replace currently used approaches, such as frequency hopping, transmission power adjustment and antenna pattern changes.
This paper introduces PREFAP, an approach to solve the multi-sensor patrolling problem in unknown environment. The multi-sensor patrolling problem consists in moving a set of sensors on a pre-set territory such that each part of this territory is visited by the sensor agents as often as possible. Eachsensor has a communicational radius and a sensory radius. indeed, optimal patrol can only be achieved if the duration between two visits of the same area of the environment is as minimal as possible. This time between two visits is called idleness. Thus, an effective patrol technique must make it possible to minimize idleness in the environment.That is why after a deep analysis of the existing resolution’s approaches, we propose a hybrid approach of resolution with three components: perception-reaction, field of strength and learning. In absence of obstacles, the perception-reaction component gives to the sensors a purely reactive behavior, as a function of their local perceptions, which permit them to move easily in their environment. The strength module enables the sensors to avoid the obstacles in the environment. As regards to the learning module, it allows the sensors to get out of blocking situations encountered during obstacle avoidance. This approach, called PREFAP, must be able to minimize idleness in different areas of the environment. The simulation results obtained show that the approach developed effectively minimizes idleness in the environment. This allows on the one hand, to have a regular patrol in the environment; on the other hand, thanks to the minimization of idleness of the areas of the environment, PREFAP will allow the sensors to quickly detect the various possible events which can occur in different areas of the environment.[...] Read more.
This paper is to examine the IPv6 in Palestine and to examine where are Palestinian companies in the deployment process. Also, to examine if the infrastructure can withstand the transition to IPv6 or not. This study used quantitative research methods and collect the data through a survey from the Internet companies in Palestine as reported anonymously. Due to the lack of research related to the internet in Palestine, we saw that it is necessary to discover the internet companies and how much they achieved of the deployment process. The collected data have been analyzed and described using SPSS. The data analysis showed that one internet company representing 11% of the companies in Palestine did apply the transition process to IPv6, and the percentages have set a positive indicator for the transition process. It turns out that the other companies on their way to start deploying the IPv6.[...] Read more.
The article addresses the issue of balanced placement of mobile software applications of mobile users in cloudlets deployed near base stations of Wireless Metropolitan Area Networks (WMAN), taking into account their technical capabilities. It is noted that the proposed model is more efficient in meeting the demand for computing and memory resources of mobile devices, eliminating network delays and using a reliable communication channel. At the same time, a minimum of cloudlet-based communication channels with a mobile user was suggested, reducing the network load and reliability of the communication channel when using multimedia software on mobile devices. The article reviews the balanced distribution of the tasks in the cloudlet network. If a user offloads the task to the nearest cloud and resolves it there, then the delays and energy consumption will be less. When the cloudlet is far from the mobile device, as the number of communication channels increases the delays are observed. Moreover, the article discusses the issue of selecting the cloudlets that meet some of the user requirements. Using the possible values that determine the importance of cloudlets (vacant resources in cloudlets, closeness of cloudlets to the user, high reliability, etc.), the conditions, according to which the user's application is offloaded to the certain cloudlet, are studied and a method is proposed.[...] Read more.
With the advent of new applications, different service needs come up. These needs could be in the form of reliability in delivering data, capacity amount in a particular range and certain amount of permissible delay. In order to provide high Quality of service to Networks, it is essential to provide a path between a given source and multiple destinations which satisfy certain constraints. For a domain catering to high QoS, there is a request of resources with certain constraints by all the applications. Speed and Scalability which are not flexible in terms of Network size and Topology are the basic issues to be considered here. Multimedia applications in general make use of k shortest paths whenever communication is to be carried out between a single source and one or more than one destination. In this paper, a genetic algorithm is used, which helps in determination of k shortest paths from a source node to more than one destination node, with bandwidth constraint. The algorithm makes use of the connection matrix as well as link bandwidth for determination of k shortest paths. The significance of using K shortest paths in a network is to increase Throughput and Packet delivery ratio.[...] Read more.