One of the major modern medical issues, obstructive sleep apnea (OSA), particularly at moderate to severe levels, may potentially cause cardiovascular morbidity and mortality. However, polysomnography (PSG), a gold standard tool in diagnosing OSA, is cumbersome, has limited availability, and is costly and time-consuming. Clinical prediction models thus are absolutely necessary in screening patients with OSA. Furthermore, the performance of the published prediction formulas is not satisfactory for Chinese populations. The aim of this study was to develop and validate a simple and accurate prediction system for the diagnosis of moderate to severe OSA by integrating an expert-based feature extraction technique with decision tree algorithms which have automatic feature selection capability in screening the moderate to severe OSA cases in Taiwan. Moreover, the backward stepwise multivariable logistic regression model and four other decision tree algorithms were also employed for comparison. The results showed that the proposed best prediction formula, with an overall accuracy reaching to 96.9 % in sensitivity = 98.2 % and specificity = 93.2 %, could present a good tool for screening moderate and severe Taiwanese OSA patients who require further PSG evaluation and medical intervention. Results also indicate that the proposed best prediction formula is simple, accurate, and reliable, and outperforms all the other prediction formulae considered in the present study. The proposed clinical prediction formula derived from three non-invasive features (Sex, Age, and AveSBP) may help prioritize patients for PSG studies as well as avoid a diagnosis of PSG in subjects who have a low probability of having the disease.

The popularity of handheld devices, which are usually powered by batteries, has made power saving an important and practical issue in recent years. Techniques of power saving for user devices using mobile communication systems such as WiMAX and LTE (Long-Term Evolution) are parts of the major focuses in the literature. In this paper, two revised schemes of the authors' previously proposed power saving schemes for IEEE 802.16 are proposed to be applied in LTE. The proposed schemes, namely LTE-LBPS-Aggr and LTE-LBPS-Merge, estimate the input load by traffic measurement and the channel capacity by channel quality indicator (CQI) reports, calculate the length of the sleep cycle, and notify related user equipments (UEs) of the next radio-on time for receiving data. The difference between LTE-LBPS-Aggr and LTE-LBPS-Merge lies in the grouping of UEs for sleep scheduling. LTE-LBPS-Aggr treats all UEs in a group, while LTE-LBPS-Merge allows multiple groups of UEs in sleep scheduling. The simulation study shows that in comparison with standard-based mechanisms, the proposed schemes can achieve better power saving efficiency at the cost of moderate increase on delays and the signaling overhead.

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To support multimedia service with the Broadband Wireless Access (BWA), the IP layer QoS is one of the keys to success. The IEEE 802.16 technology provides the wide area, high speed and non-light-of-sight wireless network. In the standard, the layer 2 technology ofthe IEEE 802.16 supports the QoS service with four service types. To improve the performance of the IEEE 802.16 network, we should consider how both the IP layer QoS and 802.16 QoS cooperate. In this paper, we propose a framework of cross-layer QoS support in the IEEE 802.16 network. Two novel mechanisms are proposed in the framework for performance improvement. Fragment Control and Remapping. Fragment Control handles the data frames that belong to the same IP datagram in an atomic manner to reduce useless transmission. Remapping is concerning about the mapping rules from IP QoS to 802.16 QoS and is designed to reduce the impact of traffic burstiness on buffer management. Simulation study has shown that the proposed scheme has higher goodput and throughput than the contrast.

As one of the promising techniques in Broadband Wireless Access (BWA), IEEE 802.16 also namely WiMax provides wide-area, high-speed, and non-line-of-sight wireless transmission to support multimedia services. Four service types are defined in the specification of IEEE 802.16 for QoS support. In order to achieve end-to-end multimedia services, 802.16 QoS must be well integrated with IP QoS. In this paper, we propose a framework of cross-layer QoS support in the IEEE 802.16 network. Two novel mechanisms are proposed in the framework for performance improvement: Fragment Control and Remapping. Fragment Control handles the data frames that belong to the same IP datagram in an atomic manner to reduce useless transmission. Remapping is concerned with the mapping rules from IP QoS to 802.16 QoS and is designed to reduce the impact of traffic burstiness on buffer management. Simulation study has shown that the proposed scheme has higher goodput and throughput, and lower delay than the contrast.