The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Signal estimation in MIMO communications typically suffers from performance degradations due to imperfect channel state information (CSI). Traditional robustification schemes rely on assumptions about the model uncertainty and may result in conservative performance. We introduce a rank-reduction approach that enhances the performance in training-based applications. A sequence of reduced-rank channel...
In this paper, a low overhead preamble structure is proposed for the interference approximation method — complex (IAM-C) method in offset quadrature amplitude modulation based orthogonal frequency division multiplexing (OQAM-OFDM) systems. Compared with the conventional preamble structure with three columns of symbols, the proposed preamble structure only requires two columns of symbols as the preamble...
A novel noise whitening technique of blind subspace channel estimations is proposed for cyclic prefixing multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. A fast convergence subspace channel estimation for cyclic prefixed MIMO-OFDM systems was presented in [1] where the repetition index was used to increase the number of equivalent received signals. However,...
Correntropy has been successfully applied in non-Gaussian signal processing, but the superior performance achieved is depends on appropriate selection of the kernel width. How to select a proper kernel width is a crucial problem in correntropy applications. In this paper, we propose an adaptive algorithm to update the kernel width, which is set at a maximum between the absolute value of instantaneous...
The development of wireless communications created broad opportunities in mobile communications. However, poor channel estimation and lack of proper Doppler shift compensation techniques limit the mobility considerably. Therefore, a high quality and low-complexity channel estimation is one of the most important conditions for high mobility. In this paper we propose a low-complexity delay-Doppler search...
We study the problem of amplify-and-forward relaying in a hybrid satellite-terrestrial communication system with imperfect channel gains. Signals are received by masked destination earth station (ES) with the help of a relaying ES, situated at the ground with good line-of-sight. No direct transmission is possible from the satellite to the destination ES. The satellite-relay ES link is assumed to be...
In the setting of the two-user single-input single-output X channel, recent works have explored the degrees-offreedom (DoF) limits in the presence of perfect channel state information at the transmitter (CSIT), as well as in the presence of perfect-quality delayed CSIT. Our work shows that the same DoF-optimal performance — previously associated to perfect-quality current CSIT — can in fact be achieved...
In this paper, a new spectrum sensing framework is proposed for radar communications, which recovers other informative states associated with realistic radar environments, e.g. fading channel gains and unknown noise variance, when detecting the occupancy of primary-band. We firstly formulate a dynamic state-space model by full considering the unknown noise variance and time-variant flat fading channel...
The intersymbol interference (ISI) caused by multipath propagation becomes the major challenge for designing efficient equalization methods for underwater acoustic communications. Even at moderate bit-rates, the computational complexity of adaptive equalizers is high enough to challenge their realtime implementation. Hence, reducing their complexity by either low-complexity algorithms or efficient...
In this paper, robust channel estimation and detection is considered for impulse radio ultra-wideband systems (UWB) subject to non-Gaussian noise and a frequency-domain receiver is proposed. In the proposed receiver, robust recursive least square algorithm is used for channel estimation and the least favorable density approach is employed within the detector module. A convergence analysis is presented...
Blind identification of a wireless communication channel is an important issue in communication system design. Most existing blind system identification techniques process the unknown information of the system from its output only. However, in many practical situation partial knowledge of the system transfer function is available. By relying on this known information, the performance of channel identification...
The least-squares and the subspace methods are well known approaches for blind channel identification/equalization. When the order of the channel is known, the algorithms are able to identify the channel, under the so-called length and zero conditions. Furthermore, in the noiseless case, the channel can be perfectly equalized. Less is known about the performance of these algorithms in the cases in...
An algorithm for discrimination and detection of the two phenomena double talk and abrupt changes in the echo path is proposed for fading channels. Being able to discriminate and detect these two phenomena is crucial since the echo canceler must react differently. The suggested detection scheme is based on a sequential detection approach. The communication channel is modeled as a randomly time-varying...
We investigate the identifiability conditions for blind and semi-blind FIR multichannel estimation in terms of channel characteristics, data length and input symbol excitation modes. Parameters are identifiable if they are determined uniquely by the probability distribution of the data. Two models are presented: in the deterministic model, both channel coefficients and input symbols are considered...
This paper examines the application of nonlinear signal processing techniques to the development of adaptive equalisers for frequency domain multiple access (FDMA) and multi-user detectors for code division multiple access (CDMA). Current issues are discussed and key problems identified.
This work deals with the problem of linear polyphase blind equalization (BE), i. e. we are interested in equalizing the output of a single-input-multiple-output (SIMO) channel, without observing its input. A recent result by Liu and Dong [1] showed that if the sub-channel polynomials are co-prime, the equalizer output whiteness suffices for the equalization of a white input. Based on this observation,...
Maximum a posteriori (MAP) sequence detection for channels with intersymbol interference (ISI) has previously required knowledge of the channel sampled impulse response (SIR). Generally the SIR coefficients are determined via least mean square (LMS) or recursive least squares (RLS) estimation algorithms. For many unguided media channels such as mobile radio and high frequency radio which exhibit a...
Sparse estimation has received a lot of attention due to its broad applicability. In sparse channel estimat ion, the parameter vector with sparsity characteristic can be well estimated from noisy measurements through sparse adaptive filters. In previous studies, most works use the mean square error (MSE) based cost to develop sparse filters, which is rat ional under the assumption of Gaussian distributions...
Subspace based methods provide a good compromise between performance and complexity. However, these methods are exposed to performance breakdown at the low SNR and/or small sample size region. It has been known for a long time that a major reason for such performance breakdown is the subspace swap phenomenon. However, in some scenarios such as the case of closely spaced sources, the breakdown happens...
Beamforming and channel equalizers can be formulated as optimal multichannel filter-and-sum operations with different objective criteria. It has been shown in previous studies that the combination of both concepts under a common framework can yield results that combine both the spatial robustness of beamforming and the dereverberation performance of channel equalization. This paper introduces an additional...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.