Abstract: The development of direct sequence spread spectrum systems allowed design of code division multiple access systems (CDMA), which are based on the application of orthogonal sequences to multiplex users’ information. Initially the design of these systems was based on application of spreading sequences like short and long pseudo-random sequences, Walsh functions or wavelets. In recent years, the non-binary sequences have been applied in these systems, primarily chaotic sequences produced by chaotic maps or random sequences produced by the random number generators. This lecture presentsresults of research conducted in recent years related to the theoretical analysis, simulation and practical design of systems that use non-binary spreading sequences.In particular the characteristics of chaos based systems for a single and multiple users in the presence of noise and fadingarepresented.Due to the random nature of sequences generated, the synchronization of these systems is a particular problem that attracted significant attention in communication community. The lecture will present the latest findings related to the methods of efficient synchronisation of these systems. Due to the random nature of orthogonal sequences, which are used to spread the message signal, these systems can be used for secure signal transmission and protect the information content from jamming and interception. It will be shown, using example designs in DSP technology, that the theoretical analysis of these systems is demanding, but the design and implementation of the simulators and devices based on this theory are possible. In addition, the possible applications of these systems in wireless sensor networks will be addressed.

Brief Biography of the Speaker:
Dr Stevan M. Berber was born in Stanisic, Serbia, former Yugoslavia. He completed his undergraduate studies in electrical engineering in Zagreb, master studies in Belgrade, and PhD studies in Auckland, New Zealand. Currently Stevan is with the Department of Electrical and Computer Engineering at Auckland University, New Zealand. He was appointed Visiting Professor at the University of Novi Sad in 2004 and Visiting Scholar at the University of Sydney in 2008. His teaching interests are in communication systems, information and coding theory, discrete stochastic signal processing and wireless sensor and computer networks.His research interests are in the fields of digital communication systems and signal processing with the emphasis on applications in CDMA systems and wireless computer, communication and sensor networks. He is the author of more than 80 refereed journal and conference papers, 8 books and 3 book chapters. Hi filed three patent applications. Dr Berber is a referee for papers in leading journals and conferences in his research area. He has been leading or working on a large number of research and industry projects. Dr Berber is a senior member of IEEE, a member of New Zealand Scientists, and an accredited NAATI translator for English language.