Laszlo Bacsardi

On the way to quantum-based satellite communication

Quantum-mechanics-based techniques are receiving much interest from engineers. Although a working quantum computer is still a promising tool of the far future, there are many different quantum algorithms and protocols that can be used in communication. To exploit the advantages of free-space quantum channels, it will be necessary to use space and satellite technology.

BIONETS architecture: from networks to SerWorks

This paper presents the networking framework as conceived within the European project BIONETS. The case for such a framework comes from the idea of a ldquoDisappearing Networkrdquo paradigm. In the disappearing network, the network ceases to exist as an independent entity and becomes an appendix of the distributed services running on user devices. The overall BIONETS system exploits the presence of embedded devices to provide context-awareness and leverages peer-to-peer interactions among mobile devices in order to ensure system-wide dissemination of data and services. Some of the current networking solutions developed within the project are also presented, highlighting the use of bio-inspired techniques and tools. The paper presents then a first version of the SerWorks architecture, which takes a unifying view on networks and services. In SerWorks, the network becomes a set of particular services, aimed at general connectivity purposes, which can be created and modified at runtime in order to accommodate for specific system conditions and higher-level constraints.

Novel Information Dissemination Solutions in Biologically Inspired Networks

Nowadays mobile communications gain more and more importance. The increased usage requires more sophisticated services. In this paper a possible, future network architecture is examined, called BIONETS. In this case the mobile nodes for the entire network, without dedicated backbone is present. We pursue the goal of finding an optimal information dissemination model over some mobility model. The investigation covers our previously defined protocol called IOBIO, classical broadcast and a newly developed adaptive broadcast algorithm. We run several simulations-with an own simulator created in OMNeT++ in order to decide which one is the optimal information dissemination method for the given mobility environment. The results give us the advantage to further improve the communication in such networks.

Overhead reducing information dissemination strategies for opportunistic communications

We examined the efficiency of information dissemination assuming a disconnected network architecture where highly mobile nodes form the network. The nodes have different limitations, like short battery life and low computing capabilities. We created IOBIO and MIOBIO, two protocols for information dissemination in this environment. In this article we present the results of several simulations - with a simulator created in OMNeT++ to analyze opportunistic communications - to compare the performance of the two information dissemination methods for a given mobility environment. The results give us an insight how to decrease the cost of communication in such networks.

Natural selection of message forwarding algorithms in Multihop wireless networks

The need for self-managing Multihop MANETs (Mobile Ad Hoc Networks) arose recently, where the network rapidly adapts to the changes of the environment without any central control. One of the challenges is how to spread the information fast and resource-effectively in the network. This paper presents a novel adaptive framework, which utilizes natural selection for choosing the adequate message forwarding algorithms for changing environments. The survival of the competing algorithms depends on their efficiency, while the fitness evaluation is made locally without overhead generating performance feedback. Performance evaluations were carried out in our simulation platform tailored to a self-managing MANET environment, to analyze the performance measures of different message forwarding algorithms.

Strategies for reducing information dissemination overhead in disconnected networks

The information dissemination was examined in a special disconnected network architecture where the moving nodes form the network. The nodes have certain kind of limitations, in terms of battery and computing capabilities. We created APF and IOBIO, two protocols for information dissemination in this environment. In this article we present the results of several simulations - run in a simulator created in OMNeT++ -to decide which information dissemination method is optimal for a given mobility environment. The results give us information to further improve the communication in such networks.

Towards to decision support generalization: The Universal Decision Support System concept

Mankind has always pursued knowledge. Over the philosophy questions by Paul Gauguin (“where do we come from, what are we, where are we going”), the science may answer these questions. In every scientific field, empirical and theoretical researches are making to describe natural processes, to better understand the universe. The questions are modified by the scientists: are these two variables correlated, do two or more independent dataset show some connection to each other, does a selected parameter have effect on the second parameter, which prediction can we state from independent variables for the dependent variable. But the effort for seeking the knowledge is the same. In this paper, our Universal Decision Support System concept is presented to help to answer questions related to different scientific field.

Quantum Based Information Transfer in Satellite Communication

The first electronic computer, the ENIAC (Electronic Numerical Integrator And Computer) was developed in 1943 at the University of Pennsylvania to calculate artillery firing tables. It contained around 17500 vacuum tubes and it weighed about 27 tonnes. Since that we construct smaller and smaller computers from year to year, whose performance is becoming higher and higher. Gordon Moore, co-founder of the Intel Corporation examined the number of transistors that can be placed inexpensively on an integrated circuit in 1965. He found that this number had doubled every second year. In his original paper he examined the time interval between 1958 and 1965. However, the trend – called Moore-law has continued more than half a century and is not expected to stop in the next five years (Moore, 1965). The law is represented on Fig. 1. Capabilities of many electronic devices are linked to the Moore-law, for example processor speed, memory capacity etc. We can observe a continuing size decreasing in the field of integrated circuits as well. The growth in the performance of the processor is due to putting more and more transistors on the microchip of same size. This requires smaller and smaller transistors, which can be achieved if we are able to draw thinner and thinner lines onto the surface of a semiconductor disk. The big question is how long this trend can continue? We will reach the limit of our technology and won’t be able to place more transistors on an integrated circuit. Researches offer different solutions for this problem like using parallel computers, DNS-technology or informatics based on quantum mechanics. Why quantum mechanics? If we want to place more transistors on an integrated circuit of a given size, the size of transistors have to be decreased. At a point we will cross the line to the world of the atoms. In that world the classical Ebers-Moll equals are not valid anymore, and quantum mechanical equals have to be used instead. Informatics based on quantum mechanical models is called quantum informatics. In the last years, quantum theory has appeared in satellite communications offering answers for some of nowadays’ technical questions. Although quantum computers are going to be the tools of the far future, there exist already algorithms to solve problems which are very difficult to be solved by traditional computers (Imre & Ferenc, 2005). The quantum informatics can play a key role in the field of cryptography. In present classical cryptographic methods, the key exchange is generally based on public key 19

Quantum circuit-based modeling of continuous-variable quantum key distribution system

The second generation Continuous-Variable Quantum Key Distribution is one of the most promising application of quantum mechanics in communications. This paper investigates a state-of-the-art Continuous-Variable Quantum Key Distribution solution from circuit modeling point of view in order to build an appropriate simulation framework. This framework allows detailed evaluation of the systems performance and adjusting the system parameters. Copyright

Quantum Key Distribution over Space-Space Laser Communication Links

The quantum based satellite communication offers a secure way for key distribution which is essential for symmetric keys based transmi ssion. For modeling this type of communication, we created a mathematical model which is based on the behavior of singlephoton sources and detectors and on the losses orig inated from beam spreading and pointing error. Based on this model, we developed a simulator software to study the quantum communication over space-space links, e.g., between two satellites. We analyzed the performance of three quantum key distribution protocols—BB84, B92, S09—on different space-space links. Two of the main parameters during the analysis were the size of the necessary aperture for a successful space-space communication and the length of the communication channel. Our results show that the three mentioned QKD protocols are feasible when using satellite-satellite links.