phase noise correction
213221493
A Phase Noise Correction Scheme for Multi channel Multi echo SWI Processing
In a GRE acquisition, effect of noise in each voxel can be minimized through the knowledge of prior information about the phase error, which can result in more robust estimation of susceptibility related features. However, estimating the error in the given phase image of GRE acquisition is difficult. Moreover, the errors can significantly affect the resolution of the resulting phase mask at regions where the magnitude intensities are significantly low. Even though there are methods like non linear least square fitting, smoothness introduced by these methods in the filtered phase reduces resolution and contrast to noise ratio (CNR) In order to maintain the resolution at voxel level, we propose a new filtering scheme where a series of local weights estimated from the probability density function of the phase measurements conditioned on the magnitude intensity and the noise variance. With an estimate of the local noise variance made available through a noise scan, the CNR improvement attained with the proposed noise correction scheme is compared using magnitude SWI images reconstructed at different acceleration factors.
Sreekanth Madhusoodhanan Joseph Suresh Paul
119636217
Phase noise correction for OFDM signal based on DCT approach and variational inference
Abstract A novel scheme to joint phase noise (PHN) correcting and channel noise variance estimating for orthogonal frequency division multiplexing (OFDM) signal was proposed. The new scheme was based on the variational Bayes (VB) method and discrete cosine transform (DCT) approximation. Compared with the least squares (LS) based scheme, the proposed scheme could overcome the over fitting phenomenon and thus lead to an improved performance. Computer simulations showed that the proposed VB based scheme outperforms the existing LS based scheme
Peng Chen Nan Li Ju-Hu Li Zhiqiang He Weilin Wu
6731042
Joint Iterative Transmitter and Receiver Phase Noise Correction using Soft Information
In this paper we discuss the effect of phase noise at both, transmitter and receiver in an OFDM system. We study an iterative equalization system at the receiver. The system is based on a joint linear MMSE estimation of the transmitter and receiver phase noise. We propose a receiver module which can be considered as a serial concatenation of an outer decoder with an inner phase noise correction/metric computation block. For intercarrier interference (ICI) suppression we introduce a method to only use the most reliable decoded symbols, which results in a significant performance improvement. The performance is shown by simulation results for different oscillator qualities and an ETSI HiperLan A channel.
2007 IEEE International Conference on Communications
Steffen Bittner Wolfgang Rave Gerhard Fettweis
29923316
Phase Noise Correction Based on TPS Symbols for the Chinese DTTB System
In orthogonal frequency division multiplexing (OFDM) system, phase noise (PHN) from oscillator can severely reduce the performance by causing: common phase error (CPE) and inter carrier interference (ICI) The impact of PHN on received signal can be characterized by the circular convolution of the transmitted signal and the discrete Fourier transform (DFT) of PHN signal in frequency domain. Digital television/terrestrial multimedia broadcasting (DTMB) announced as the Chinese digital television terrestrial broadcasting (DTTB) standard, adopted the time domain synchronous OFDM system (TDS OFDM) system which has 36 continuous transmission parameter signaling (TPS) symbols in frequency domain which be used for PHN suppression. Based on a linearized parametric model for PHN, least squared (LS) estimation and fast Fourier transform (FFT) approaching method for PHN correction are proposed in this paper. The effects of the PHN on channel estimation in both TDS OFDM system and conventional cyclic prefix OFDM (CP OFDM) are also investigated. Simulations show that the proposed algorithm can effectively reduce the PHN and improve the symbol error rata (SER) of TDS OFDM systems over both additive white Gaussian noise (AWGN) and broadcasting multipath channel. In practice, the FFT approaching method can be applied to the DTMB receiver chip design directly with low implementation cost.
IEEE Transactions on Broadcasting
Fang Yang Jun Wang Jian Song Zhixing Yang
1274108
Time domain phase noise correction for OFDM signals
We introduce an algorithm for compensating for carrier phase noise in an OFDM communication system. Through the creation of a linearized parametric model for phase noise we generate a least squares (LS) estimate of the transmitted symbol. Simulation results using digitized DVB T RF signals created in a laboratory, and a DVB T compliant receiver model are presented to evaluate the effectiveness of the algorithm in practical environments.
Conference Record of the Thirty Sixth Asilomar Conference on Signals, Systems and Computers, 2002.
Raul A Casas Stephen L Biracree Andrew E Youtz
61037608
Time domain phase noise correction for OFDM signals
We introduce an algorithm for compensating for carrier phase noise in an OFDM communication system. Through the creation of a linearized parametric model for phase noise we generate a least squares (LS) estimate of the transmitted symbol. Simulation results using digitized DVB T RF signals created in a laboratory, and a DVB T compliant receiver model are presented to evaluate the effectiveness of the algorithm in practical environments.
Stephen L Biracree Raul A Casas Andrew E Youtz
30006871
Multiple phase noise correction for OFDM/SDMA
It has been proposed in the literature that phase noise causes severe performance degradation of OFDM systems and therefore need to be corrected A combined OFDM/SDMA approach has been proposed in the literature allowing simultaneous transmitted user terminals which give rise to multiple phase noise. Conventional correction methods proposed in the literature are targeted for single phase noise and do not apply for multiple phase noise. We therefore propose a new multiple phase noise correction (MPNC) scheme which takes advantage of spatial diversity and mitigates the effects of multiple phase noise on the OFDM/SDMA receiver performance. The MPNC scheme presents quite good performance with few pilots involved per user. Numerical results are given to illustrate the effectiveness of the proposed scheme for an uplink OFDM/SDMA system.
GLOBECOM '03. IEEE Global Telecommunications Conference (IEEE Cat. No.03CH37489)
Songping Wu Yeheskel Bar-Ness
69215487
Phase noise correction circuit, a transmitter, a receiver, a radio device, a radio communication system and a phase noise correction method
Object of the present invention is a full carrier reproduction performance in a radio device having a transmitter and a receiver and performing radio communication. Phase noise correction circuit provided in a radio device transmitter comprising: a phase error information acquisition unit that acquires phase error information by the receiver radio device is detected; and a phase noise correction unit that acquires the phase error information using means the acquired phase error information, when the correction of the phase noise radio transmission between the transmitter and the receiver local oscillator is shared baseband signal generated for execution.
7218161
Soft information aided phase noise correction for OFDM systems
Orthogonal Frequency Division Multiplexing (OFDM) systems suffer from severe performance degradation in the presence of phase noise. In particular, phase noise leads to a common phase error (CPE) as well as intercarrier interference (ICI) in the frequency domain. In this contribution, we present a novel code aided CPE estimation algorithm. The Expectation Maximization (EM) algorithm is used to approach the Maximum Likelihood (ML) estimate of the CPE. The estimator accepts soft information from the decoder in the form of a posteriori probabilities of the coded symbols, which can be interpreted as performing joint data detection and decoding. The performance of the proposed algorithm is verified through computer simulations. Impressive performance gains are obtained as compared to conventional data aided CPE correction.
Mohamed Marey Mamoun Guenach Heidi Steendam
125698226
Phase noise correction interferometry absolute distance meter