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In this paper, a general feedback structure is proposed to improve the performance of existing digital notch filters. With the feedback structure, the notch filter can have a narrower stopband. This structure can be applied to any type of existing notch filter. We first derive the improved design of existing one-dimensional (1-D) filters. Then, by suitably extending the 1-D concept, the design of...
An adaptive modulation scheme designed for optical camera communication (OCC) applications was proposed. Compared with conventional modulation schemes such as on off keying (OOK), pulse amplitude modulation (PAM), pulse position modulation (PPM), the proposed scheme can improve data link quality under combined channel impairments such as the ambient light noise from background illuminations. The resulting...
In this paper, we proposed an embedded particle swarm optimization/parallel iterative update (PSO/PIU) scheme to concurrently search users' cooperative transmit beamformers (CBTFs) for the uplink of multiuser MIMO systems. This proposed scheme is a modified PSO approach by embedding the PIU mechanism into the conventional PSO. With the help of the PIU mechanism, the interference can be effectively...
To address the problems of high sampling rates, shadow fading and additive noise from the receiver, in this paper, a distributed compressed sampling (DCS) and centralized reconstruction approach which utilize the spatial diversity against fading channels is proposed. Unlike traditional centralized reconstruction, in this paper, we centralized recover the spectrums by exploiting the block-sparsity...
This paper presents a novel Distributed Streaming Compressive Spectrum Sensing (DSCSS) algorithm for wide-band spectrum sensing under decentralized cognitive radio network (CRN) scenario. In contrary to traditional compressive sensing (CS) that only focuses on fixed-length signal's compressive sampling and reconstruction, DSCSS follows streaming CS framework, where Analog-to-Information Converter...
In traditional compressive sampling approach, it's always assumed the sparsity of a signal is known. However, we always can't get this in Cognitive Radio (CR) network. This makes a great barrier to the practical usage of compressive sampling. This paper develops an Adaptive Compressive Sampling (ACS) approach for wideband signals. It doesn't need the sparsity as a priori knowledge. Also, once the...
Statistical estimators of the magnitude-squared spectrum are derived based on the assumption that the magnitude-squared spectrum of the noisy speech signal can be computed as the sum of the (clean) signal and noise magnitude-squared spectra. Maximum a posterior (MAP) and minimum mean square error (MMSE) estimators are derived based on a Gaussian statistical model. The gain function of the MAP estimator...
This paper presents three multiuser detectors (MUDs) for the uplinks of spatial-frequency-time-domain (SFT-domain) spread multi-carrier (MC) direct sequence code division multiple access (DS-CDMA) systems. First, aiming at achieving significant performance gain, we propose a joint optimum SFT-domain MUD based on minimum mean square error (MMSE) decision rules. Further, to reduce the computational...
This paper presents a novel speech enhancement algorithm that can substantially improve the signal-to-residual spectrum ratio by combining statistical estimators of the spectral magnitude of the speech and noise. The noise spectral magnitude estimator is derived from the speech magnitude estimator, by appropriately transforming the a priori and the a posteriori SNR values. By expressing the signal-to-residual...
In this paper, we present a multistage group-decision-aid MUD (MG-MUD) for the uplink multirate code division multiple access (CDMA) systems. To provide good tradeoff between the performance and computational complexity, the new MUD is based on the widely MMSE criterion and constructed by a bank of group detectors in each stage. First, the users are classified into different groups according to their...
In this paper, we propose a semi-blind channel estimation algorithm for amplify-and-forward (AF) relay networks. The algorithm fits well for the recently developed space-time coding (STC) technique in AF relay network that serves for small size terminal and achieve the transmission diversity. Compared to the optimal training based estimators, e.g., maximum likelihood (ML) or linear minimum mean square...
A rate control approach is proposed to deal with the low delay H.264/AVC video transmission over channels with burst errors by applying stochastic optimization technique. Based on the exponential rate-distortion and the linear variance prediction model, the one pass rate control algorithm will take into account the channel state and round trip delay, and make an immediate decision on the optimal rate...
A rate control approach is proposed to deal with the low delay H.264/AVC video transmission over channels with burst errors by applying stochastic optimization technique. Based on the exponential rate-distortion and the linear variance prediction model, the one pass rate control algorithm will take into account the channel state and round trip delay, and make an immediate decision on the optimal rate...
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