Performance study of a reduced complexity time synchronization approach for OFDM systems

Abstract

This paper presents a performance analysis of a recently proposed preamble based reduced complexity two-stage synchronization technique. The preamble, composed of two identical sub-sequences, is first used to determine an uncertainty interval based on Cox and Schmidl algorithm. Then, a differential correlation is carried using a new sub-sequence obtained by element wise multiplication of the preamble sub-sequence and a shifted version of it. This second step is exploited to fine tune the coarse estimate by carrying the differential correlation over the uncertainty interval. We here study the effect of the training sequence choice on the synchronization performance in the general case of multipath channels. We also discuss some complexity issues compared to previously proposed algorithms. We show that the frame start detection is greatly sensitive to the training sequence class and choice. Computational load evaluation ensure that the reduced complexity approach, which was found to provide almost equal performance to those obtained by higher complexity algorithms in [10, 11], has much lower complexity load comparable to that of simple sliding correlation based approaches. To further reduce the computational load, an optimal choice of the uncertainty interval, used in the fine stage, can also be adapted to the operating SNR.