A spectrum‐efficient integer frequency offset estimator of mobile OFDM system in double selective channels

Abstract

SUMMARYWe put forward a novel frequency offset estimator for burst orthogonal frequency division multiplexing (OFDM) systems under double selective fading channels. With the help of pilot bits and channel estimates in frequency domain, we calculate the delay power spectrum (DPS) of multi-path channels and estimate the integer carrier frequency offset (CFO), in which the FFT-realized (Fast Fourier Transform) algorithm is computation effective. Additionally, the pseudo noise (PN) sequence is proposed to act as a pilot signal to extend the estimation range. Yet the algorithm uses pilots instead of preambles, resulting in higher spectrum efficiency than conventional methods. Simulations show high accuracy and robustness in a wide range of terminal velocities (time-selectivity) and signal-to-noise ratios (SNRs).

Joint carrier frequency offset and channel estimation for OFDM systems with two receive antennas

“…However, his estimator requires a separate channel estimator, that is requires a known channel. Several methods have also been proposed to deal with fractional CFO [12,13] or to estimate the integer part of the CFO [14,15]. compensated for, and hence they perform channel estimation.…”

“…In [11], time-domain channel estimates (which retain CFO information) are used for CFO estimation using an approximate maximum likelihood (ML) approach. Several methods have also been proposed to deal with fractional CFO [12,13] or to estimate the integer part of the CFO [14,15]. However, because the CFO in general can take any value (integer with a fractional part), these approaches do not provide a complete solution to the problem.…”

Accurate estimation of Doppler shift in mobile communications with high vehicle speed

“…Unfortunately, all of the aforementioned Doppler shift estimators, except for that in , did not explicitly give consideration to the noise effect in Doppler shift estimation; thus, they experienced significant performance degradations as a result of the influence of additive white Gaussian noise (AWGN). In addition, the AWGN had been taken into account for the carrier frequency offset estimation ; however, the carrier frequency offset is very different from the Doppler shift in the mechanism as well as the influence and therefore is beyond the scope of this paper. Accordingly, we only focus on the Doppler shift estimation in our study.…”

Frequency acquisition synchronization for multiple antenna systems

“…By converting a multipath channel into a set of flat fading subchannels, an OFDM system is insensitive to frequency‐selective fading problem. Meanwhile, MIMO systems have been widely employed because of their higher capacity and higher spectral efficiency than SISO systems using the same bandwidth .…”