Browsing by Subject "Channel estimation"
Now showing items 1-19 of 19
-
A low-complexity KL expansion-based channel estimator for OFDM systems
Authors:
Publisher and Date:(2005)This paper first proposes a computationally efficient pilot-aided linear minimum mean square error (MMSE) batch channel estimation algorithm for OFDM systems in unknown wireless fading channels. The proposed approach employs a convenient representation of the discrete multipath fading channel based on the Karhunen-Loeve (KL) orthogonal expansion and finds MMSE estimates of the uncorrelated KL series expansion coefficients. Based on such an expansion no matrix inversion is required in the proposed ...
-
Artificial neural network based estimation of sparse multipath channels in OFDM systems
Authors:
Publisher and Date:(SPRINGER, VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS, 2021-01)In order to increase the transceiver performance in frequency selective fading channel environment, orthogonal frequency division multiplexing (OFDM) system is used to combat inter-symbol-interference. In this work, a channel estimation scheme for an OFDM system in the presence of sparse multipath channel is studied using the artificial neural networks (ANN). By means of ANN's learning capability, it is shown that how to model and obtain a channel estimate and how it allows the proposed technique ...
-
Channel Estimation and Equalization for Alamouti SF-Coded OFDM-UWA Communications
Authors:
Publisher and Date:(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2021-02)In this paper, a new channel estimation and equalization algorithm for underwater acoustic (UWA) communications is presented. The proposed algorithm is developed to meet the requirements of underwater time-varying sparse channels that undergo Rayleigh fading. In addition, the algorithm takes into consideration a path-based channel model which describes each received path with significant power by an attenuation factor, a Doppler scale, and a delay. Transmit diversity enabled by Alamouti space-frequency ...
-
Channel Estimation for Realistic Indoor Optical Wireless Communication in ACO-OFDM Systems
Authors:
Publisher and Date:(Springer, 2018)In this paper channel estimation problem in a visible light communication system is considered. The information data is transmitted using asymmetrical clipped optical orthogonal frequency division multiplexing. Channel estimation and symbol detection are performed by the Maximum Likelihood and the Linear Minimum Mean Square Error detection techniques respectively. The system performance is investigated in realistic environment that is simulated using an indoor channel model. Two different channels ...
-
Channel Estimation for Residual Self-Interference in Full-Duplex Amplify-and-Forward Two-Way Relays
Authors:
Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2017)Training schemes for full duplex two-way relays are investigated. We propose a novel one-block training scheme with a maximum likelihood estimator to estimate the channels between the nodes as well as the residual self-interference (RSI) channel simultaneously. A quasi-Newton algorithm is used to solve the estimator. As a baseline a multi-block training scheme is also considered. The Cramer-Rao bounds of the one-block and multi-block training schemes are derived. By using the Szego's theorem about ...
-
Channel Estimation for Spatial Modulation Orthogonal Frequency Division Multiplexing Systems
Authors:
Publisher and Date:(IEEE, 2015)A combination of spatial modulation and orthogonal frequency division multiplexing (SM-OFDM) has been recently proposed for multicarrier systems while assuming the perfect channel state information (P-CSI) available at the receiver. But in practical scenarios the estimation of CSI is crucial in order to detect the transmitted data coherently. In this work(1) a new frame structure and pilot symbol aided channel estimation (PSA-CE) technique with a piecewise linear interpolation is proposed for the ...
-
Channel Estimation for TDS-OFDM Systems in Rapidly Time-Varying Mobile Channels
Authors:
Publisher and Date:(IEEE-Inst Electrical Electronics Engineers Inc, 2018)This paper explores the performance of time-domain synchronous orthogonal frequency-division multiplexing (TDS-OFDM) systems operated under rapidly time-varying mobile channels. Since a rapidly time-varying channel contains more unknown channel coefficients than the number of observations, the mobile channel can conveniently be modeled with the discrete Legendre polynomial basis expansion model to reduce the number of unknowns. The linear minimum mean square error (LMMSE) estimate can be exploited ...
-
Distributed estimation over parallel fading channels with channel estimation error
Authors:
Publisher and Date:(IEEE, 2008)We consider distributed estimation of a source observed by sensors in additive Gaussian noise where the sensors are connected to a fusion center with unknown orthogonal (parallel) flat Rayleigh fading channels. We adopt a two-phase approach of (i) channel estimation with training and (ii) source estimation given the channel estimates where the total power is fixed. We prove that allocating half the total power into training is optimal and show that compared to the perfect channel case a performance ...
-
Iterative channel estimation techniques for uplink MC-CDMA systems
Authors:
Publisher and Date:(IEEE, 2007)In this work maximum likelihood (ML) channel estimation for uplink multicarrier code-division multiple-access (MC-CDMA) systems is considered in the presence of frequency fading channel. The expectation-maximization (EM)- and a space-alternating generalized expectation-maximization (SAGE) algorithm are introduced to avoid matrix inversion for the ML channel estimation problem. We compare the both algorithms in terms of the number of used iteration and show that the proposed algorithms converge the ...
-
Iterative channel estimation techniques for uplink MC-CDMA systems
Authors:
Publisher and Date:(IEEE, 2007)In this work maximum likelihood (ML) channel estimation for uplink multicarrier code-division multiple-access (MC-CDMA) systems is considered in the presence of frequency fading channel. The expectation-maximization (EM)- and a space-alternating generalized expectation-maximization (SAGE) algorithm are introduced to avoid matrix inversion for the ML channel estimation problem. We compare the both algorithms in terms of the number of used iteration and show that the proposed algorithms converge the ...
-
On Channel Estimation in DC Biased Optical OFDM Systems Over VLC Channels
Authors:
Publisher and Date:(IEEE Computer Society, 2016)Visible Light Communication(VLC) has been considered as a potential access option for 5G wireless systems to solve performance limitation due to bandwidth shortage at radio frequency (RF) band. In (VLC) system illumination infrastructure has dual usage at the same time namely illumination and wireless data transmission. DC Biased optical (DCO)-OFDM has been proposed for VLC systems to provide optically power efficient solution and easy implementation. Wireless communication systems generally require ...
-
Performance Investigation of IEEE 802.11af Systems Under Realistic Channel Conditions
Authors:
Publisher and Date:(IEEE, 2015)As the analog TV broadcasting channels have become less frequently used in the last decade there has been a great interest in these frequency bands for the deployment of metropolitan local and personal area networks. Among them the local area network standard IEEE 802.11af defines PHY and MAC layer implementation of such networks in these unused frequency bands also named television white space (TVWS). According to the standard the systems may use contiguous or non-contiguous channels during their ...
-
Performance of Distributed Estimation Over Unknown Parallel Fading Channels
Authors:
Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2008)We consider distributed estimation of a source in additive Gaussian noise observed by sensors that are connected to a fusion center with unknown orthogonal (parallel) flat Rayleigh fading channels. We adopt a two-phase approach of i) channel estimation with training and ii) source estimation given the channel estimates and transmitted sensor observations where the total power is fixed. In the second phase we consider both an equal power scheduling among sensors and an optimized choice of powers. ...
-
Pilot assisted channel estimation for asymmetrically clipped optical OFDM over visible light channels
Authors:
Publisher and Date:(Institute of Electrical and Electronics Engineers Inc., 2017)The Visible Light Communication(VLC) has drawn significant attention recently for wireless communication in addressing the performance limitations of wireless systems due to the scarcity of bandwidth. In VLC system the visible lights is used not only for illuminating rooms but also for an optical data transmission. Asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM) has been proposed for VLC systems to provide optically power efficient solution in the optical domain. ...
-
Pilot Symbol Aided Channel Estimation for Spatial Modulation-OFDM Systems and its Performance Analysis with Different Types of Interpolations
Authors:
Publisher and Date:(Springer, 2017)Spatial modulation orthogonal frequency division multiplexing (SM-OFDM) system has been recently proposed as an alternative for multiple-input multiple-output (MIMO)-OFDM systems to increase spectral efficiency by keeping a low-complexity implementation. In the literature SM-OFDM systems assume a perfect channel state information (P-CSI) available at the receiver for coherent detection and the channel estimation problem is not considered. It is clear that the channel estimation is a critical issue ...
-
Rapidly Time-Varying Channel Estimation for Full-Duplex Amplify-and-Forward One-Way Relay Networks
Authors:
Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2018)Estimation of both cascaded and residual self-interference (RSI) channels and a new training frame structure are considered for full-duplex (FD) amplify-and-forward (AF) one-way relay networks with rapidly time-varying individual channels. To estimate the RSI and the rapidly time-varying cascaded channels we propose a new training frame structure in which orthogonal training blocks are sent by the source node and delivered to the destination over an FD-AF relay. Exploiting the orthogonality of the ...
-
Semiblind joint channel estimation and equalization for OFDM systems in rapidly varying channels
Authors:
Publisher and Date:(2010)We describe a new joint iterative channel estimation and equalization algorithm for joint channel estimation and data detection for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency selective and rapidly timevarying channels. The algorithm is based on the expectation maximization-maximum a posteriori (EM-MAP) technique which is very suitable for the multicarrier signal formats. The algorithm leads to a receiver structure that yields the equalized output using ...
-
Sparse channel estimation and data detection algorithms for ofdm-based underwater acoustic communication systems
Authors:
Publisher and Date:(Kadir Has University, 2018)Communication over acoustic signals in underwater results into a multi-scale multilag channels which occurs due to the multipath propagation. Hence a robust channel estimation technique has to be present at the receiver and the solutions of the terrestrial-based systems are not applicable. in this work using path-based channel model that characterizes underwater channels by a delay a Doppler shift and an attenuation factors three new pilot assisted time domain-based channel estimation algorithms ...
-
Sparse Channel Estimation with Clipping Noise in DCO-OFDM Based VLC Systems
Authors:
Publisher and Date:(IEEE, 2020)In this paper a new computationally efficient and high performance channel estimation algorithm is proposed for DC-biased optical OFDM (DCO-OFDM) systems in indoor visible light communications (VLC) in the presence of a clipping noise. The sparse structure of the channel is taken into consideration in the channel estimation algorithm. The algorithm has an iterative structure and aims at reducing the effect of the clipping noise, inevitably generated by the DCO-OFDM systems. In te algorithm, the ...
