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Underwater acoustic (UA) channel is often affected by strong impulsive noise. In this paper, a compressive sensing based iterative algorithm is proposed to accurately estimate the channel state information and mitigate the impulsive noise, which is important to ensure high-speed data transmission in UA orthogonal frequency-division multiplexing communication systems. By exploiting the sparsity of...
In this paper, we present the baseband receiver design for IEEE 802.11ah. We study several key receiver algorithms, including coarse frequency offset estimation and coarse timing synchronization, fine frequency offset estimation, fine timing synchronization, channel estimation and MIMO equalization. For channel estimation, we propose to use decoded SIG field to improve its estimation. To further improve...
A novel blind time-frequency joint synchronization based on the cyclostationary of orthogonal frequency division multiplexing with offset quadrature amplitude modulation (OFDM/OQAM) systems is conceived in multipath channels conditions. The cyclic cumulants of OFDM/OQAM signals are derived firstly, symbol timing offset (STO) and carrier frequency offset (CFO) are estimated by employing two groups...
In this paper the dynamic compressed sensing (DCS) estimation of time varying underwater acoustic (UWA) channel is investigated. By modeling the time varying UWA channels as sparse set consisting with constant and time-varying supports, the estimation of time varying UWA channel is transformed into a problem of dynamic compressed sensing (DCS) sparse recovery. Employing the combination of Kalman filter...
In this paper, we propose and analyze new spectrum-efficient communication and radar sensing systems (named ComSens) operating in full-duplex mode with frequency division duplex scheme. ComSens simultaneously use the pilot overhead for channel estimation and radar sensing. The performances of ComSens are analyzed in terms of ergodic communication data-rate and radar estimation rate. The total system...
Underwater acoustic (UWA) channel estimation based on fast Bayesian matching pursuit (FBMP) is investigated in this paper. In UWA multipath channel, the positions of UWA channel taps usually obey the Bernoulli distribution, while the coefficients of UWA channel taps obey the complex-valued Gaussian distribution. Such knowledge of distribution is considered as a prior for UWA channel estimation based...
This paper researches on millimeter-wave (mm-wave) channel estimation based on interference cancellation (IC) and DOA (Direction of Angles) estimation in hybrid massive MIMO systems. According to the ray-tracing model, the mm-wave channel estimation problem can be solved by converting into the estimation of parameters including the angles of departure (AOD), the angles of arrival (AOA) and the path...
Generalized frequency division multiplexing (GFDM) with the flexible structure is one of the promising candidates for the fifth generation wireless communication system. This paper focuses on training sequence design that is used in the estimation of in-phase(I) and quadrature(Q) imbalance parameters on GFDM receivers as well as frequency selective channel. Combining with the structure of low complexity...
Due to the sparsity that contained in underwater acoustic (UWA) channels, in recent years tremendous attention has been drawn in designing sparse channel estimation algorithms for improve the performance of channel equalizer, which is driven by channel estimator. However, experimental evaluation and comparison is limited regarding enhancing the performance of different norm constraint sparse channel...
In underwater acoustic time-varying multipath channels, the traditional block Doppler estimation algorithm performs poorly. In this paper an improved Doppler estimation algorithm using virtual time reversal mirror is proposed. The proposed algorithm automatically matches multipath time-varying channels by focusing synchronous head of two adjacent fame-signals in the time domain, then measures the...
Underwater acoustic channel is a time varying, strong multipath, serious Doppler frequency shift, and high noise interference channel. Aiming at the requirements of strong stability and high reliability to support reliable transmission over long distance, a direct sequence spread spectrum based on single carrier underwater acoustic communication system using dual spread spectrum code (SC-CDMA/DSSC)...
In multi-channel high-resolution and wide-swath SAR signal processing, Doppler centroid (DC) is essential for channel phase bias estimation and SAR focusing. By exploiting that an inaccurate Doppler centroid would introduce linear errors in phase bias estimation and consequently deteriorate the reconstructed Doppler spectrum, the Doppler centroid can be accurately estimated by Doppler spectrum optimisation...
In this paper we study the initialization step of decoding algorithms for efficient error-control coding techniques, and its dependence of the channel characteristics over which transmission is performed. LDPC and Polar codes are selected as efficient error-control codes operating over different channels. Channels under study are the classic Additive White Gaussian noise channel, the Rayleigh fading...
A maximum correntropy criterion (MCC) algorithm with a flexible zero attractor is proposed, whose estimation performance is investigated for estimating a multi-path channel in mixed Gaussian environment. The proposed algorithm is denoted as flexible zero attraction MCC (FZA-MCC), in which the flexible zero attractor (FZA) is implemented by an approximation parameter adjustment function. The estimation...
Various channels can be denoted by sparse channels and many algorithms have been proposed to exploit their sparsity. In this paper, we propose a mixed algorithm based on Greedy and LS algorithms for sparse channel estimation. Analyses of the proposed and commonly used algorithms in terms of performance and complexity are performed considering the channel's sparsity, the length of training sequence...
Transmission Power Control (TPC) protocols are poised for wide spread adoption in wireless sensor networks (wSNs) to address energy constraints. The link quality properties that need to be captured in order to identify the optimum transmission power (TP) have not been clearly defined and previous works have presented conflicting views on the matter. This has led to several current TPC protocols using...
Electronic fetal heart rate (fHR) monitoring is standard in clinical practice to detect deviations from the normal fHR pattern. Typically, an ultrasound (US) transducer, operating in a pulsedwave Doppler mode, measures the periodic motion of the fetal heart, from which the fHR can be derived. However, as the fetus moves through the birth canal, the fetal-heart location (fHL) changes continuously....
Error correction coding based on soft-input decoding can significantly improve the reliability of flash memories. Such soft-input decoding algorithms require reliability information about the state of the memory cell. This work proposes a channel model for soft-input decoding that considers the asymmetric error characteristic of multi-level cell (MLC) and triple-level cell (TLC) memories. Based on...
Spectral efficiency and capacity of Land Mobile Satellite (LMS) systems can be enhanced by using MIMO (Multiple Input Multiple Output). Polarization diversity is an efficient technique to realize MIMO in LMS communications. Polarization diversity employs different polarization to realize multiple independent propagation paths. Dual polarized antennas offer a space and cost effective alternative compared...
Digital images captured in hazy conditions suffer from colour distortion and loss of contrast, posing difficulties in being applied for further applications. Due to the existed challenge and its great significance, a large amount of research has been conducted for image de-hazing. Among the image haze removal methods, the algorithm based on dark channel prior is proved to be the most effective. Furthermore,...
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