New preamble structures for synchronization and cell searching in OFDM systems

Abstract

This thesis proposes two new preamble structures for synchronization and cell searching in cellular based Orthogonal Frequency Division Multiplexing (OFDM) systems. The proposed preamble structures are to impose Pseudo Noise sequences (PN-sequences) on the OFDM transmitted signal in time-domain for time and frequency synchronization. This scheme make it possible to achieve a good performance at a low SNR, therefore, it can guarantee a reliable communication to a mobile located at the cell edge. Herein, the PN-sequences occupies the whole or part of the preamble according to the two different preamble structures. The proposed preamble structures are compared each other in terms of frame and frequency synchronization, cell searching and mean acquisition time. The simulation results elucidate that the proposed preamble structures are appropriate for cellular based OFDM systems.