REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

DESIGN OF A Secure communication SYSTEM IN DIGITAL TECHNOLOGIES FOR WIRELESS SENSOR NETWORKS

STEVAN BERBER

The University of Auckland, Auckland, s.berber@auckland.ac.nz

Abstract: This paper presents theoretical modelling and simulation of the physical layer communication system for wireless sensor network application. To investigate properties of the system by simulation the blocks of the system are analyzed including the transmitter, receiver and the channel. These blocks are separately designed and then integrated into one body. The system was implemented with binary spreading sequences proposed for wireless sensor networks. In order to enhance the security of the system, a theoretical model of the system based on the use of non-binary sequences (like chaotic sequences) was analyzed and confirmed by simulation. A particular contribution is the system design, which is based on the theoretical model developed in the discrete time domain. This system is suitable for direct design in digital technology. Furthermore, exact expressions for the system’s bit error probabilities are derived in closed form and confirmed by simulations. In order to mitigate severe fading influence, the system is analyzed and simulated with interleaver and deinteleaver blocks present. It was confirmed that these blocks improve substantially the system performance in the presence of fading.

Keywords: wireless sensor networks, discrete signal processing, BER expressions, transceiver design, fading channel design.