A Study of Synchronization Algorithms in OFDM/WiMAX Systems

Erick R. Sousa, Karlo G. Lenzi, Luís G.P. Meloni

DOI: 10.14209/sbrt.2009.57825

Evento: XXVII Simpósio Brasileiro de Telecomunicações (SBrT2009)

Keywords: OFDM WiMAX software defined radio synchronization FPGA

Abstract

A review of OFDM synchronization algorithms applied to IEEE 802.16 standard is presented. An extended Morelli algorithm is proposed and compared with classical synchronization methods: Schmidl and Tufvesson (Matched-Filter). The timing metric of that extended algorithm is close to matchedfilter timing detection. The frequency offset is calculated using a BLUE approach, resulting in an estimation range of [−𝐺/2, 𝐺/2] subcarriers, where 𝐺 is the number of repeated patterns in the preamble. The detection probabilities in Rice, Rayleigh and static ISI channels is also simulated, and interesting results are obtained for each algorithm studied. algorithm that uses a Maximum-Likelihood timing estimation along with a BLUE frequency offset estimation. Also, in order to make calculations less complex, most algorithms consider the channel as Additive-White-Gaussian. In general, this is not the case in real communication systems, so it is important to compare the algorithms’ behaviour under other channel types, such as Rice, Rayleigh and cable channels.

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