Róbert Horváth

Standardized languages for telecommunication systems

In this paper, we give a survey of the most important ITU-T languages used in the system modeling and development process. We discuss the goals, the most important features, and the basic syntactic and semantic rules of the languages and notations. We compare the capabilities of the ITU-T languages and the OMGs Unified Modeling Language, considering the modeling and development aspects they support. At the end of the paper, we give an informative example to demonstrate the use of the languages during the different phases of the development process.

Peer-to-peer based distributed file systems

In this paper, we present the problem of building a file system on top of a peer-to-peer network. While peer-to-peer networks are offering an increasing number of services, the scale of network file systems is increasing to that of distributed storage systems spanning the globe. The convergence of the two fields should give birth to decentralised, distributed and self-configuring storage networks. We show here the evolution of peer-to-peer networks and network file systems, and the difficulties that have prevented offering file system type services in peer-to-peer networks so far. We present CFS and Ivy, two DHT-based file systems that fail, however, to solve key problems, and outline possible solutions in the future.

On the Sign-Stability of Finite Difference Solutions of Semilinear Parabolic Problems

The sign-stability property is one of the important qualitative properties of the one-dimensional heat conduction equation, or more generally, of one-dimensional parabolic problems. This property means that the number of the spatial sign-changes of the solution function cannot increase in time. In this paper, sufficient conditions will be given that guarantee the fulfillment of a numerical analogue of the sign-stability for the finite difference solution of a semilinear parabolic problem. The results are demonstrated on a numerical test problem.

Experimental UWB impulse transmission with receiver and transmitter built with discrete parts

This paper shows the design and implementation of an UWB transmitter and a receiver built with discrete parts. The transmitter is based on a step recovery diode and the receiver is built around an ultra-high speed comparator. The circuits are designed in a manner, that all components are low cost discrete elements and both the transmitter and the receiver can be easily interfaced to low speed and low power micro controller systems. With the proposed transmitter and receiver devices we implemented an experimental UWB data transmitting link with a simple UART like transmission protocol that is able to transmit 8 bit packets.