Low complexity estimation of carrier and sampling frequency offsets in burst‐mode OFDM systems

Abstract

We study communications under slowly varying channels, and consider three cases of knowledge of the channel impulse response (CIR): full knowledge, no knowledge, and partial knowledge of the CIR. By partial knowledge, we refer to knowing only either the CIR magnitudes or the CIR phases. It is known that obtaining the exact joint maximum‐likelihood estimate (MLE) of the CFO and the SFO requires a two‐dimensional search. Here, we present a new estimation method which uses the Taylor expansion of the MLE cost function, combined with the best linear unbiased estimator, to obtain a method which does not require such a search. The computational complexity of the new method is evaluated. Numerical simulations demonstrate that the new method approaches the corresponding Cramér‐Rao bound for a wide range of signal‐to‐noise ratios, and has superior performance compared to all other existing methods for approximating the solution for the joint MLE, while maintaining a low computational complexity. Copyright © 2015 John Wiley & Sons, Ltd.

Efficient Joint Estimation of Carrier Frequency and Sampling Frequency Offsets for MIMO-OFDM ATSC Systems

“…Combining Equations (33) and (34) with Equation (35), the MSE expression of the joint frequency-offset estimator can be respectively obtained by…”

“…The received signal y r (t) is sampled at time instants t = nT , which leads to a SFO ξ = (T − T)/T. At the receiver, the sampled signal at time instants t = nT becomes [34] y r (nT ) = e 2πεnT /NT…”

“…To maximize the advantages of MIMO-OFDM, it is therefore of crucial importance to accurately estimate the CFO and SFO [22,23]. In the literature, a number of pilot-assisted approaches, from maximum likelihood estimation (MLE) to linear least-squares estimation (LSE) strategies [22][23][24][25][26][27][28][29][30][31][32][33][34][35], have been presented to obtain accurate CFO and SFO estimates. The MLE is well known to be capable of achieving high accuracy in joint estimation of CFO and SFO, but its high complexity limits its practical use [22][23][24][25].…”

“…The MLE is well known to be capable of achieving high accuracy in joint estimation of CFO and SFO, but its high complexity limits its practical use [22][23][24][25]. To solve the complexity issue, a considerable amount of research has been devoted to the low complexity variants of joint MLE [26][27][28][29][30][31][32][33][34][35]. In [26][27][28][29][30][31][32], the ad-hoc-based CFO and SFO estimation strategy was developed calculating the phase difference from two consecutive pilot symbols with symmetric and uniform distribution across DC.…”

“…In [26][27][28][29][30][31][32], the ad-hoc-based CFO and SFO estimation strategy was developed calculating the phase difference from two consecutive pilot symbols with symmetric and uniform distribution across DC. In [33][34][35], a decoupled estimation of CFO and SFO was proposed, which is still computation-intensive for real-time processing. Hence, more efficient frequency estimation and its complete performance analysis in a multipath fading channel is a key challenge in realizing high-performance MIMO-OFDM receivers.In this paper, the performance analysis of joint CFO and SFO estimator for the MIMO-OFDM ATSC broadcast system is presented in a the multipath fading channel.…”