On timing offset estimation for OFDM systems

Abstract

Two timing offset estimation methods for orthogonal frequency division multiplexing (OFDM) systems as modifications to Schmidl and Cox's method [6] are presented. The performances of the timing offset estimators in additive white Gaussian noise channel and intersymbol interference channel are compared in terms of estimator variance obtained by simulation. Both proposed methods have significantly smaller estimator variance in both channel conditions.

Time synchronization algorithms for IEEE 802.11 OFDM systems

“…Incorrect timing can introduce inter-symbol interference (ISI) and intercarrier-interference (ICI), which can degrade the system performance severely [5]. Several approaches [6,7,8] have been proposed on the basis of using preamble symbols or using cyclic prefix and pilot subcarriers. For burst mode transmission such as wireless LAN, the method of using preamble symbols [6] is preferred for fast time synchronization.…”

Low Complexity Time Synchronization Algorithm for OFDM Systems with Repetitive Preambles

“…Other algorithms make use of repeated preambles [8]- [11] similar to the IEEE 802.11a/g preamble, so they can be easily adapted to this standard. Some methods employ training symbols specifically designed to improve the performance of the proposed algorithm, such as [12]- [15]; these solutions cannot be used in the synchronization of existing systems with a defined preamble. And finally, some time synchronization techniques have been specifically designed for the IEEE 802.11a/g standard, such as [16]- [23].…”

An overlap S&C method for OFDM synchronization

“…Many methods have been proposed to reduce the plateau problem. H. Minn [4] provides a four-repetition preamble to have a sharp timing metric for the timing synchronization. However, if the length of the inserted Cyclic Prefix (CP) equals to N/4, N is the number of subcarriers, its performance is poor.…”

“…However, if Timing Offset (TO) and Carrier Frequency Offset (CFO) exist between the Transmitter (Tx) and Receiver (Rx), OFDM system will suffer the Inter-Symbol Interference (ISI) and Inter-Carrier Interference (ICI) that degrade the system performance dramatically. To correctly decode the received signals, an OFDM system has to establish the timing and frequency synchronization [1,2,3,4,5] firstly to avoid the Bit Error Rate (BER) degradation.…”