This paper proposes a preamble structure for joint estimation of carrier frequency offset (CFO) and I/Q imbalance. Because existing methods cannot guarantee correct solutions within all range of CFOs, we derive two constraints of phase rotations applied to repetition patterns. By using the preamble based on the presented constraints, CFO is optimally estimated, and I/Q imbalance estimation is p...

In this paper, carrier frequency offset (CFO) estimation schemes robust to the non-Gaussian noise for orthogonal frequency division multiplexing (OFDM) systems are proposed. Applying the probability density function of the cyclic prefix of OFDM symbols to the maximum-likelihood (ML) criterion, we propose the ML and low-complexity ML estimation schemes. Simulation results show that the proposed ...

Abstract Single-carrier (SC) transmission is an appropriate transmission scheme for uplink transmission because of its low peak-to-average power ratio (PAPR). Spread spectrum (SS) transmission achieves higher frequency diversity gain and hence improves the bit error rate (BER) performance. The authors have recently proposed SC with frequency-domain spread spectrum (SC-FDSS) transmission with or...

one of the limitations of orthogonal frequency division multiplexing (ofdm) in many applications is its sensitivity to frequency shifts, errors normally referred to as carrier frequency offset (cfo). although, this small offset is negligible in conventional single carrier communication systems, it is a severe problem in the ofdm systems. because, the carriers in ofdm are inherently closely spac...

The characteristics of the propagation in indoor environments at a carrier frequency of 24 GHz are investigated by means of wideband directional measurements. The data shows that indoor radio propagation is dominated by impinging waves that exhibit discrete character. Furthermore, a global characterization of the investigated radio environment suitable for stochastic channel modeling by means o...

ABSTRACT: In this paper, by modifying a conventional method which requires two training symbols, we propose a timing and frequency synchronization algorithm for OFDM systems which requires one training symbol. While the frame/symbol timing is obtained by using the conventional method, the carrier frequency offset is efficiently estimated by the proposed method. Key features of the proposed meth...

AbstmctWe propose a carrier frequency offset recovery (CFOR) module for CDMA to operate with STAR, the spatietemporal array-receiver. The new CFOR module implements simple linear regression (LR), similar in approach to that implemented for time-delay synchronization in STAR. Simulations in selective Rayleigh-fading channels at various mobile speeds show that an increasing carrier frequency offs...

In this paper, we propose an estimator which jointly estimates the carrier frequency offset (CFO) and channel state without a prior knowledge of channel length (CL) for a multiple-input multiple-output orthogonal frequency-division multiplexing system. A preliminary CFO/channel estimate is first reached based on the maximum-likelihood criterion. To improve the over-determined problem, a CL esti...