Successive Interference Cancellation-Based Weighted Least-Squares Estimation of Carrier and Sampling Frequency Offsets for WLANs

Xiaoping Zhou,Kan Zheng,Bin Wu,Hui Zhao

doi:10.1109/access.2020.3034582

Abstract

A successive interference cancellation (SIC)-based weighted least-squares (WLS) estimation for the carrier frequency offset (CFO) and the sampling frequency offset (SFO) is presented for wireless local area networks (WLANs) based on orthogonal frequency division multiplexing (OFDM). The proposed SIC-based WLS performs the estimation by exploiting the phase rotation in the frequency domain caused by the CFO and the SFO. SIC-based WLS estimates the CFO and the SFO successively instead of by traditional simultaneous estimation. The estimation of CFO based on the Taylor series is performed first, and then the WLS estimation of SFO based on successive cancellation of the CFO is carried out. The simulation results show that the SIC-based WLS can estimate the CFO and the SFO effectively. Compared to the WLS scheme, a performance improvement of more than 0.6 dB is achieved by SIC-based WLS, and nearly 10 percent of the complexity is reduced.

Highlights

Orthogonal frequency division multiplexing (OFDM) achieves high spectral efficiency and offers an effective solution in overcoming frequency selectivity [1], [2]; it has been widely used in wireless local area networks (WLANs) systems [3].Synchronizer error in OFDM systems, such as the carrier frequency offset (CFO) and the sampling frequency offset (SFO), can lead to intolerable performance loss [4]–[6]
DA schemes perform estimations based on the phase rotation in the frequency domain, which consists of the common phase error (CPE) and sample timing error (STE) [18], [19] caused by the CFO and the SFO, respectively
Since only limited pilot subcarriers are embedded in the WLAN system, this paper focuses on improving the accuracy of linear CFO and SFO estimation

Summary

Introduction

Orthogonal frequency division multiplexing (OFDM) achieves high spectral efficiency and offers an effective solution in overcoming frequency selectivity [1], [2]; it has been widely used in WLAN systems [3].Synchronizer error in OFDM systems, such as the carrier frequency offset (CFO) and the sampling frequency offset (SFO), can lead to intolerable performance loss [4]–[6]. Dantas [16] presented a pilot frequency index-related SFO estimation method that neglected the different levels of fading of the pilot subcarriers and obtained a limited performance gain. X. Zhou et al.: SIC-Based WLS Estimation of Carrier and SFOs for WLANs squares (WLS) to achieve good performance.

Results

Conclusion