A New Symbol Timing and Frequency Synchronization Design for OFDM-based WLAN Systems

Low Complexity Time Synchronization Algorithm for OFDM Systems with Repetitive Preambles

“…To accomplish this objective, the proposed algorithm is divided in two parts: fine and coarse time synchronization. The fine time estimation is based on a cross-correlation, as some of the algorithms found in the literature [16], [22], [23]. On the other hand, the coarse time estimation is performed using a new metric.…”

“…The algorithm proposed in this paper also calculates a cross-correlation between the received signal and the transmitted short symbols for fine time synchronization such as Chang & Kelly [16], Zhou & Saito [22] and Kim & Park [23], but a new metric is proposed for coarse time estimation. As will be demonstrated later, the proposed algorithm achieves good performance for low signal to noise ratio (SNR) and has a low-cost VLSI implementation that would facilitate its integration in a multi-standard processor for OFDM communications [24].…”

“…Manusani et al [21] performs a fine time estimation exploiting the conjugate property of the symbols for channel estimation, whereas Troya et al [19] makes use of a simplified cross-correlation with the first 32 complex samples of the symbols for channel estimation (carrier frequency offset (CFO) is estimated and compensated before doing this cross-correlation). The algorithms proposed by Chang & Kelly [16], Zhou & Saito [22] and Kim & Park [23] calculate a cross-correlation between the received signal and the transmitted short symbols for fine time synchronization. For coarse time estimation [16] performs a maximum-likelihood auto-correlation, [22] an auto-correlation based on [8], and [23] uses the same cross-correlation for coarse and fine time estimation.…”

“…The algorithms proposed by Chang & Kelly [16], Zhou & Saito [22] and Kim & Park [23] calculate a cross-correlation between the received signal and the transmitted short symbols for fine time synchronization. For coarse time estimation [16] performs a maximum-likelihood auto-correlation, [22] an auto-correlation based on [8], and [23] uses the same cross-correlation for coarse and fine time estimation. For all these three algorithms, time synchronization only employs the short symbols of the preamble and finishes before the symbols for channel estimation (LS).…”

“…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].…”