Symbol timing synchronization for OFDM-based WLAN systems
Cavallaro, Joseph R.
Master of Science
In this work, we address the problem of symbol timing synchronization for Orthogonal Frequency Division Multiplexing (OFDM) WLAN systems. OFDM systems are known to be sensitive to synchronization errors and improving the accuracy of timing offset estimation can help improve the overall system performance. We propose a method that reduces computational complexity while achieving performance comparable to the autocorrelation method commonly employed at the wireless receiver. The proposed method is based on the average magnitude difference function (AMDF). We present performance results for the proposed method for AWGN and Raleigh-fading channels in the context of IEEE 802.11a short preamble sequence. We also propose a preamble sequence based on Golomb sequence, a sequence with low auto-correlation properties, and compare its timing estimation performance with that of the IEEE 802.11a short-sequence. Simulation results show significant performance improvements for AWGN as well as Raleigh-fading channels. We also present an experimental Field-Programmable Gate Array (FPGA) implementation of the symbol timing estimation block using a Intermediate-frequency based hardware transceiver and LabVIEW using fixed-point arithmetic.
Electrical engineering; Computer science