Filter and nested-lattice code design for fading MIMO channels with side-information

Linear-assignment Gel'fand-Pinsker coding (LA-GPC) is a coding technique for channels with interference known only at the transmitter, where the known interference is treated as side-information (SI). As a special case of LA-GPC, dirty paper coding has been shown to be able to achieve the optimal interference-free rate for interference channels with perfect channel state information at the transmitter (CSIT). In the cases where only the channel distribution information at the transmitter (CDIT) is available, LA-GPC also has good (sometimes optimal) performance in a variety of fast and slow fading SI channels. In this paper, we design the filters in nested-lattice based coding to make it achieve the same rate performance as LA-GPC in multiple-input multiple-output (MIMO) channels. Compared with the random Gaussian codebooks used in previous works, our resultant coding schemes have an algebraic structure and can be implemented in practical systems. A simulation in a slow-fading channel is also provided, and near interference-free error performance is obtained. The proposed coding schemes can serve as the fundamental building blocks to achieve the promised rate performance of MIMO Gaussian broadcast channels with CDIT or perfect CSITComment: submitted to IEEE Transactions on Communications, Feb, 200

Clean relaying aided cognitive radio under the coexistence constraint

We consider the interference-mitigation based cognitive radio where the primary and secondary users can coexist at the same time and frequency bands, under the constraint that the rate of the primary user (PU) must remain the same with a single-user decoder. To meet such a coexistence constraint, the relaying from the secondary user (SU) can help the PU's transmission under the interference from the SU. However, the relayed signal in the known dirty paper coding (DPC) based scheme is interfered by the SU's signal, and is not "clean". In this paper, under the half-duplex constraints, we propose two new transmission schemes aided by the clean relaying from the SU's transmitter and receiver without interference from the SU. We name them as the clean transmitter relaying (CT) and clean transmitter-receiver relaying (CTR) aided cognitive radio, respectively. The rate and multiplexing gain performances of CT and CTR in fading channels with various availabilities of the channel state information at the transmitters (CSIT) are studied. Our CT generalizes the celebrated DPC based scheme proposed previously. With full CSIT, the multiplexing gain of the CTR is proved to be better (or no less) than that of the previous DPC based schemes. This is because the silent period for decoding the PU's messages for the DPC may not be necessary in the CTR. With only the statistics of CSIT, we further prove that the CTR outperforms the rate performance of the previous scheme in fast Rayleigh fading channels. The numerical examples also show that in a large class of channels, the proposed CT and CTR provide significant rate gains over the previous scheme with small complexity penalties.Comment: 30 page

Assessing the quality of steady-state visual-evoked potentials for moving humans using a mobile electroencephalogram headset.

Recent advances in mobile electroencephalogram (EEG) systems, featuring non-prep dry electrodes and wireless telemetry, have enabled and promoted the applications of mobile brain-computer interfaces (BCIs) in our daily life. Since the brain may behave differently while people are actively situated in ecologically-valid environments versus highly-controlled laboratory environments, it remains unclear how well the current laboratory-oriented BCI demonstrations can be translated into operational BCIs for users with naturalistic movements. Understanding inherent links between natural human behaviors and brain activities is the key to ensuring the applicability and stability of mobile BCIs. This study aims to assess the quality of steady-state visual-evoked potentials (SSVEPs), which is one of promising channels for functioning BCI systems, recorded using a mobile EEG system under challenging recording conditions, e.g., walking. To systematically explore the effects of walking locomotion on the SSVEPs, this study instructed subjects to stand or walk on a treadmill running at speeds of 1, 2, and 3 mile (s) per hour (MPH) while concurrently perceiving visual flickers (11 and 12 Hz). Empirical results of this study showed that the SSVEP amplitude tended to deteriorate when subjects switched from standing to walking. Such SSVEP suppression could be attributed to the walking locomotion, leading to distinctly deteriorated SSVEP detectability from standing (84.87 ± 13.55%) to walking (1 MPH: 83.03 ± 13.24%, 2 MPH: 79.47 ± 13.53%, and 3 MPH: 75.26 ± 17.89%). These findings not only demonstrated the applicability and limitations of SSVEPs recorded from freely behaving humans in realistic environments, but also provide useful methods and techniques for boosting the translation of the BCI technology from laboratory demonstrations to practical applications

Modeling Chinese post-90\u272 tourism loyalty to the ex-rival state using the perceived value approach

Purpose – A recent trend in tourism research involves the study of independent Chinese tourists. Yet while post-90s or Generation Z (i.e., born in the 1990s) comprises an important share of nondomestic visitors to Taiwan and other tourist destinations, this segment of the tourist population is currently under-analyzed. As a pioneering piece of research in this area, this survey attempts to understand Chinese tourists of this cohort visiting the long-divided state. Design – This research incorporates the social dimension of perceived value in the ordinarily employed perceived-value model to better understand why Chinese post-90s would like to recommend Taiwan. Methodology – This study samples Chinese students from 12 universities located in the northern, central, southern, and western regions of Taiwan. They were investigated with the selfadministered survey which is composed of five constructs, for a total of 17 questions. Structural equation modeling was employed to analyze the collected data and testify the hypotheses. Findings – The finding provides insights in the specific tourism behaviors of this cohort and how they are found distinct from their predecessors. The emotional dimension of the post-90s’ tourismrelated perceived value is a strong determinant of their loyalty to Taiwan as a tourist destination. The prior-rival situation between both sides of the Taiwan Strait might signify that social dimension significantly predict their loyalty, through the mediator of satisfaction. Originality – This research provides important information for tourism businesses regarding place management and marketing strategies, enabling them to receive this new generation of Chinese customers

Experimental and Numerical Study on the Semi-Closed Loop Control of a Planar Parallel Robot Manipulator

This paper implements the model predictive control to fulfill the position control of a 3-DOF 3-RRR planar parallel manipulator. The research work covers experimental and numerical studies. First, an experimental hardware-in-the-loop system to control the manipulator is constructed. The manipulator is driven by three DC motors, and each motor has an encoder to measure the rotating angles of the motors. The entire system is designed as a semiclosed-loop control system. The controller receives the encoder signals as inputs to produce signals driving the motors. Secondly, the motor parameters are obtained by system identification, and the controllers are designed based on these parameters. Finally, the numerical simulations are performed by incorporating the manipulator kinematics and the motor dynamics; the results are compared with those from the experiments. Both results show that they are in good agreement at steady state. There are two main contributions in this paper. One is the application of the model predictive control to the planar parallel manipulator, and the other one is to overcome the effects of the uncertainties of the DC motors and the performance of the position control due to the dynamic behavior of the manipulator

Reliability of clinical examination methods for postoperative pain after primary root canal treatment

Background/purpose: Clinical test results may have lower reliability due to the varying range of test stimulation or patient subjectiveness. This study aimed to verify a reliable clinical test method by comparing pain intensity levels of a tooth at rest, during function, and after the clinical tests of percussion and chewing.Materials and methods: A total of 36 asymptomatic necrotic teeth that required root canal treatment, one in each patient, were included. All treatment procedures were performed in a single visit by an experienced endodontist. Patients were asked to mark their pain levels on a vertical visual analog scale (VAS) while the relevant tooth was at rest and during function 24 h after the treatment. In addition, patients marked their pain levels after the clinical tests of percussion and chewing. Finally, the pain levels were compared using Pearson's correlation for the reliability of the test methods at a significance level of 95%.Results: The postoperative pain levels measured during the clinical tests and functions were significantly higher than the pain levels at rest (P < 0.05). The pain levels after percussion tests were significantly higher than that during the function and chewing tests (P < 0.05). Pain intensity during the function was simulated with a higher correlation when using the chewing strip method rather than the percussion method.Conclusion: The bite test using the chewing strips as a pain intensity assessment can mimic the actual postoperative pain experience, whereas the percussion test fails to provide the accuracy of this pain experience