Iterative Receiver with Joint Rake-Equalizer and Channel Estimation for DS-UWB System

Yi-Jen Chiu,Szu-Lin Su 대한전자공학회 2006 ITC-CSCC :International Technical Conference on Ci Vol.2006 No.2

A Robust Estimation/Compensation Scheme of IQ Imbalance with Frequency Offset in Communication Receivers

Yi-Jen Chiu,Szu-Lin Su,Shao-Ping Hung 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7

Direct conversion receiver is widely utilized in today’s communication system. However, it usually faces a common problem of front-end distortions such as IQ imbalance and frequency offset. When treated separately, effective algorithms exist for estimating and compensating for IQ imbalance as well as frequency offset. With both effects present, such algorithms do not lead to useful estimates of the related parameters. OFDM is sensitive to nonidealities in the receiver front-end. This leads either to stringent front-end specifications and, thus, an expensive device, or large performance degradations. A good summary, Guanbin [1] discusses the transmitter calibration briefly and proposes an estimation technique for calculating the imbalance parameters. For the IEEE 802.11a OFDM standard, Tubbax observe that additional effects from OFDM channel estimation and correction can affect the IQ correction circuits and proposes a smoothing procedure to compensate. The above procedure is not effective when the CFO is too small. This paper extends the previous results mentioned above by developing a simple and adaptive least-square (LS) algorithm to estimate and compensate for IQ imbalance assuming the IQ imbalance compensation is not affected by the CFO, then the CFO is estimated using any of several conventional algorithms. With the additional requirement of a known periodic training sequence (see Su and Chiu ) this process extends the results of to practical cases when CFO is small. Our compensation scheme eliminates the IQ imbalance based on one OFDM symbol and performs well in the presence of CFO. The compensation scheme has fast convergence and small residual degradations. The solution is implemented with an adaptive filter to adjust the parameters of estimation and is computationally relatively inexpensive. With the proposed method as shown in Fig. 1, we can estimate the effect of IQ imbalance without knowing CFO exactly by means of an repetitive training sequence as depicted in Fig.2. Two set of I/Q mismatch parameters, (εr=1.5㏈, ?φr=1.5˚) and (εr=3㏈, ?φr=3˚), are used in the simulations. Fig. 3 shows the performance comparison between the systems with and without I/Q imbalance compensation. It shows that the proposed algorithm can give a satisfactory performance for CFO > 5㎑. To reduce the drawback of high sensitivity under low CFO channel, we modify the adaptive scheme and the fine IQ estimation method to solve the problem of performance degradation when CFO is small. Therefore, our IQ imbalance estimation/compensation scheme potentially leads to low-cost and low-complexity receivers. The simulation results show that the modified scheme can achieve much better performance as shown in Fig. 4.

Adaptive MMSE Rake-Equalizer Receiver Design with Channel Estimation for DS-UWB System

Yi-Jen Chiu,Szu-Lin Su 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7

The UWB systems have a fine path resolution by transmitting information with ultra short pulses. The Rake receiver is known to be a technique that can effectively combine paths with different delays and obtain the path diversity gain. However, the UWB multipath channel is spread over dozens of symbols in the case of ultra high-speed communications of several hundreds Mbps, which results in a strong frequency selective channel. Consequently, the Rake receiver needs a large number of fingers and the computational complexity of the Rake receiver becomes high. The conventional Rake receiver employs the weight vector to perform the maximal ratio combining (MRC) which maximizes the output signal-to-noise ratio (SNR) when the interference is modeled as additive white Gaussian noise. But for its complexity and cost to remain low, the number of fingers that can be afforded is too small to capture the ample energy provided by the UWB channel, which entails a large number of paths (often>50). In this paper, we introduce a robust receiver design incorporating a channel estimation scheme for DS-UWB over a realistic indoor multipath channel in Fig. 1. The proposed receiver reduces intense multi-path destruction and severe ISI by using a combined adaptive Rake and equalizer structure referred to as the adaptive MMSE Rake-equalizer receiver in Fig. 2. Relevant receiver parameters are estimated using the MMSE algorithm. This has motivated studies of multipath combining receivers that process only a subset of the available Lp resolved multipath components. We obtain more robust signal detection at the receiver side by the adaptive channel estimation in order to extract more accurate channel state information. The channel characteristics are first estimated using the LMS adaptive algorithm on the training sequence of the preamble. The proposed receiver is able to employ the energy of a few paths and obtain better performance by the proposed receiver design. Simulation results show that channel estimation is necessary and that increasing the number of Rake fingers is effective in improving system performance. We also show that DS-UWB with adaptive MMSE Rake-equalizer has better BER performance than DS-UWB with MRC Rake receiver, especially when the number of fingers is large. In particular it is shown that the performance of an adaptive MMSE Rake-equalizer receiver of number of Rake fingers equal to 5 (L=5) outperforms an MRC Rake receiver of number of Rake fingers equal to 10 (L=10) over CM4 channels. Finally, the LMS algorithm does give a satisfactory performance with fast convergence in Fig. 3 and Fig. 4. The proposed adaptive MMSE Rake-equalizer receiver is able to employ the energy of a few paths and obtain better performance by the suitable receiver design. It shows that the adaptive algorithm gives a satisfactory performance.

Professionals’ experiences and attitudes toward use of Traditional Chinese Medicine in hospice palliative inpatient care units: A multicenter survey in Taiwan

Yu-Jia Lin,Hsiao-Ting Chang,Ming-Hwai Lin,Ru-Yih Chen,Ping-Jen Chen,Wen-Yuan Lin,Jyh-Gang Hsieh,Ying-Wei Wang,Chung-Chieh Hu,Yi-Sheng Liou,Tai-Yuan Chiu,Chun-Yi Tu,Yi-Jen Wang,Bo-Ren Cheng,Tzeng-Ji Ch 한국한의학연구원 2021 Integrative Medicine Research Vol.10 No.2

Background: Medical staff may have difficulties in using conventional medicine to manage symptoms among terminally ill patients, including adverse effects of the treatment. Traditional Chinese medicine (TCM) is regarded as a complementary or alternative medicine, and has been increasingly used in the field of palliative medicine in recent years. This study aimed to investigate the experiences of and attitudes toward using TCM among palliative care professionals, and to provide preliminary information about its use in palliative care. Methods: This was a cross-sectional survey study conducted in eight inpatient hospice wards in Taiwan between December 2014 and February 2016. The questionnaire was self-administered, and was analyzed with descriptive statistics including Pearson’s Chi-square test and Fisher’s exact test. Results: A total of 251 palliative care professionals responded to the questionnaire, of whom 89.7% and 88.9% believed that the use of TCM could improve the physical symptoms and quality of life in terminally ill patients, respectively. Overall, 59.8%, of respondents suggested that TCM had rare side effects, and 58.2% were worried that TCM could affect the liver and kidney function of patients. In total, 89.7% and 88.0% of professionals agreed there were no suitable clinical practice guidelines and educational programs, respectively, for TCM use in palliative care. Conclusions: Most of the respondents agreed there was insufficient knowledge, skills-training, and continuing education on the use of TCM in terminally ill patients in Taiwan. These results show that to address patient safety considerations, guidelines about use of TCM in palliative care should be established.

Health Care Utilization and Expenditures of Patients with Diabetes Comorbid with Depression Disorder: A National Population-Based Cohort Study

Chun-Jen Huang,Hui-Min Hsieh,Herng-Chia Chiu,Peng-Wei Wang,Mei-Hsuan Lee,Chih-Yi Li,Ching-Hua Lin 대한신경정신의학회 2017 PSYCHIATRY INVESTIGATION Vol.14 No.6

Objective: The study investigated to compare health care utilization and expenditures between diabetic patients with and without depression in Taiwan. Methods: Health care utilization and expenditure among diabetic patients with and without depression disorder during 2000 and 2004 were examined using Taiwan’s population-based National Health Insurance claims database. Health care utilization included outpatient visits and the use of inpatient services, and health expenditures were outpatient, inpatient, and total medical expenditures. Moreover, general estimation equation models were used for analyzing the factors associated with outpatient visits and expenditures. Multiple logistic regression analysis was applied for identifying the factors associated with hospitalization. Results: The average annual outpatient visits and annual total medical expenditures in the study period were 44.23–52.20; NT$87,496–133,077 and 30.75–32.92; NT$64,411–80,955 for diabetic patients with and without depression. After adjustment for covariates, our results revealed that gender and complication were associated with out-patient visits. Moreover, the time factor was associated with the total medical expenditure, and residential urbanization and complication factors were associated with hospitalization. Conclusion: Health care utilization and expenditures for diabetic patients with depression were significantly higher than those without depression. Sex, complications, time, and urbanization are the factors associated with health care utilization and expenditures.

Taurine Attenuates Hepatic Inflammation in Chronic Alcohol-Fed Rats Through Inhibition of TLR4/MyD88 Signaling

Chao-Jen Lin,Chun-Ching Chiu,Yi-Chen Chen,Mu-Lin Chen,Tsai-Ching Hsu,Bor-Show Tzang 한국식품영양과학회 2015 Journal of medicinal food Vol.18 No.12

Accumulating evidence indicates that overconsumption of ethanol contributes in many ways to the pathogenesis of hepatic injury. Although studies indicate that taurine decreases lipogenesis, oxidative stress, and inflammatory cytokines, the protective effect of taurine against alcohol-induced liver injury is still unclear. To clarify the precise signaling involved in the beneficial effect of taurine on alcohol-induced liver injury, rats were randomly divided into four treatment groups: (1) control (Ctl), (2) alcohol (Alc), (3) Alc + taurine (Tau), and (4) Alc + silymarin (Sil). The Tau and Sil groups had lower lymphocyte infiltration and significantly lower TLR-4/MyD88 and IκB/NFκB compared to the Alc group. The inducible nitric oxide synthase (iNOS), C-reactive protein (CRP), tumor necrosis factors (TNF)-α, interleukin (IL)-6, and IL-1β were also significantly lower in the Tau and Sil groups than in the Alc group. The experimental results indicated that hepatoprotection against alcohol-induced inflammation may be mediated by decreased TLR-4/MyD88 signaling.

A Novel I/Q Imbalance Compensation Scheme for the Communication Channels with Frequency Offset

Szu-Lin Su,Yi-Jen Chiu,Shao-Ping Hung 대한전자공학회 2005 ITC-CSCC :International Technical Conference on Ci Vol.2005 No.2

Three-Level Bi-Directional Half-Bridge CLLC Resonant Converter for DC Micro-Grid

Hsuan-Yu Yueh,Jing-Yuan Lin,Haung-Jen Chiu,Chen-Yen Chu,Yu-Chen Chang,Sih-Yi Lee 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

A Three-Level Bi-Directional Half-Bridge CLLC Resonant DC-DC converter for DC micro-grid application is studied on this paper, which uses dual resonant tanks to achieve wide range voltage regulation and meanwhile employs bi-directional capability. All power switches on this converter can achieve ZVS function at the whole load and the voltage stress on all power switches at both sides can be clamped at half of input voltage and output voltage since the three-level circuit architecture using the proposed synchronous rectifier (SR) control, therefore, the voltage stresses of the transformer, resonant tanks, power switches and other components are only half compared with conventional half-bridge CLLC resonant converter, the downsizing rated of components selection can be more flexible. Finally, the laboratory prototype is built to verify the performance of voltage balancing on input/output capacitor, voltage stress on switches and efficiency, the measured efficiency can be up to 95.6% over different load conditions.

Design of Three Phase Wye-Delta LLC Converter with Time Domain Analysis

Kuan-Hung Chen,Jing-Yuan Lin,Yi-Feng Lin,Yu-Chen Chang,Huang-Jen Chiu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

In the paper, the performance of a 5 kW DC/DC Wye-Delta-based series resonant converter designed for 400V input voltage and 48V output voltage server power supply is evaluated. The paper also performs operation modes analysis, circuit characteristics analysis, and use time domain analysis on Wye-Delta-based series resonant converter for circuit design to replace FHA analysis due to waveform distortion. Finally, a full-load efficiency up to 96.07% and power-density up to 2.84W/cm3 server power supply is implemented.

Antioxidative and Hepatoprotective Effects of Magnolol on Acetaminophen-induced Liver Damage in Rats

Yung-Hsiang Chen,Feng-Yen Lin,Po-Len Liu,Yi-Tsau Huang,Jen-Hwey Chiu,Yi-Chun Chang,Kee-Ming Man,Chuang-Ye Hong,Yen-Yi Ho,Ming-Tsung Lai 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.2

Acute liver failure (ALF), an often fatal condition characterized by massive hepatocyte necrosis, is frequently caused by drug poisoning, particularly with acetaminophen (N-acetyl-p-aminophenol/APAP). Hepatocyte necrosis is consecutive to glutathione (GSH) depletion and mitochondrial damage caused by reactive oxygen species (ROS) overproduction. Magnolol, one major phenolic constituent of Magnolia officinalis, have been known to exhibit potent antioxidative activity. In this study, the anti-hepatotoxic activity of magnolol on APAP-induced toxicity in the Sprague-Dawley rat liver was examined. After evaluating the changes of several biochemical parameters in serum, the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) were elevated by APAP (500 mg/kg) intraperitoneal administration (8 and 24 h) and reduced by treatment with magnolol (0.5 h after APAP administration; 0.01, 0.1, and 1 μg/kg). Histological changes around the hepatic central vein, lipid peroxidation (thiobarbituric acid-reactive substance/TBARS), and GSH depletion in liver tissue induced by APAP were also recovered by magnolol treatment. The data show that oxidative stress followed by lipid peroxidation may play a very important role in the pathogenesis of APAP-induced hepatic injury; treatment with lipid-soluble antioxidant, magnolol, exerts anti-hepatotoxic activity. Our study points out the potential interest of magnolol in the treatment of toxic ALF.