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We propose a maximum a-posteriori (MAP) based blind algorithm for carrier frequency offset (CFO) and symbol timing offset (STO) estimation, for a convolutionally coded orthogonal frequency division multiplexing (COFDM) system, in an additive white Gaussian noise (AWGN) channel. We derive the MAP estimators mathematically. It is observed that though the MAP metric for CFO estimation gives a good performance...
This paper addresses problems related to time and frequency synchronization as well as blind CP (cyclic prefix) type identification in 3GPP LTE system. We start with a general framework based on maximum likelihood (ML) parameter estimation. Then, simplified practical algorithms for estimating time and frequency offset as well as blind CP length are described. Finally, a robust hierarchical scheme...
Time domain synchronous orthogonal frequency division multiplex (TDS-OFDM) is an effective multi-carrier modulation scheme to improve spectrum efficiency. Conventional synchronization algorithm based on the time-domain differential correlation of the pseudo noise (PN) sequence may not work well in severe multipath fading channels. In this paper, a robust synchronization algorithm is proposed where...
A new method for frequency synchronization based upon Zero-Intermediate Frequency (zero-IF) receiver and characteristics of the received signal's power spectrum for MC-DS-CDMA-Uplink system is proposed in this paper. The variance for Carrier Frequency Offset (CFO) estimators of MC-DS-CDMA-Uplink is compared with that of an OFDM system to estimate the CFO. Our study and results show that the MC-DS-CDMA...
Contraposing the diffuse characteristic of HF channel and low data rate in HF communication systems, the technology which combines AMC and OFDM was presented. The models of transmitter and receiver were also put forward. The key technologies such as time synchronization, carrier frequency offset estimation, channel estimation and PAPR reduction were analyzed and corresponding resolutions were given...
This paper presents a hardware-efficient autocorrelation scheme for the synchronization of MIMO-OFDM based wireless local area network (WLAN) systems, such as IEEE 802.11n. Carrier frequency offset (CFO) estimation for the frequency synchronization requires high complexity autocorrelation operations of many training symbols. In order to reduce the hardware complexity of the MIMO-OFDM synchronization,...
Carrier Frequency Offset (CFO) estimation and correction is a critical issue in all OFDM receivers. For WiMAX Physical layer it is even more challenging to introduce a suitable CFO sub-system since WiMAX system supports complex features for future applications such as multiuser, multi-access and high mobility operation. This paper is concerned with low cost hardware implementation of CFO sub-system...
An uplink OFDMA systems is considered. Different users use different transmit antennas, thus, each user contributes a different carrier frequency offset (CFO) at the receiver. The multiple CFOs introduce intercarrier interference, thus impeding user separation and transmit signal recovery. A low complexity CFO estimation approach is proposed for estimating multiple CFOs. The proposed approach relies...
Considering the features of Underwater Acoustic channel and the sensitivity versus synchronization for CI/OFDM system, A time and frequency synchronization method based on Constant Amplitude Zero Auto-Correlation(CAZAC) sequence is presented. The time offset estimation and carrier frequency offset estimation can be achieved simultaneously. The fractional part and integral part of carrier offset estimation...
A novel data-aided joint symbol timing and carrier frequency offset estimation method based on selective superimposed pilot for OFDM system is proposed in this paper, where the pilot sequence is superimposed on a data sequence and transmitted together, and thus it has a high spectral efficiency. The selective pilot sequence owns low correlation with data sequence to reduce the interference. By taking...
In this paper, a new joint frame synchronization and carrier frequency offset estimation scheme in orthogonal frequency division multiplexing (OFDM) systems is proposed. The new scheme needs only one training symbol to perform both frame synchronization and carrier frequency offset estimation, and the carrier frequency offset acquisition range of the new scheme is as large as one half of the total...
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