Pilot-Aided Fine Synchronization for SC-FDE Systems on Multipath Fading Channels

Abstract

With single-carrier frequency-domain equalization (SC-FDE), the carrier-frequency offset (CFO) and samplingfrequency offset (SFO) are embedded in the phase rotations of the complex frequency-domain signal components at the output of the fast Fourier transform (FFT). To extract the phase rotations and estimate the CFO and SFO, the frequency-domain signal components need to be known. However, they are, in general, not known to the receiver, since they are a mixture of the data and pilot symbols. To solve this difficulty sub-block processing is proposed, such that joint estimation of the CFO and SFO can be applied. For the joint estimation, both the linear least-squares (LLS) and simple weighted least-squares (SWLS) regressions are considered, where the latter is shown to be robust to the channel frequency-selectivity. Finally, the SC-FDE receiver with proposed closed-loop tracking algorithm is tested on both quasi-static and time-varying multipath fading channels and its effectiveness is demonstrated.

Joint Estimation of Carrier-Frequency and Sampling-Frequency Offsets for SC-FDE Systems on Multipath Fading Channels

“…During each block, the channel frequency response is, in general, unknown before synchronization takes place. However, we can simply use the channel estimate of the last block in the synchronization for the present block, i.e., w k,i = | Ĥk,i−1 | 2 and w k,0 = 1, where Ĥk,i can be obtained by using a pilotaided channel estimation based on the sub-block structure [10]. Noteworthily, the SWLS estimator reduces to the LLS estimator, provided that equal weights (i.e.…”