Hsiu-Hui Lee

A Scalable Multi-tier Architecture for the National Taiwan University Hospital Information System based on HL7 Standard

This article describes the successful experiences of National Taiwan University Hospital (NTUH) in moving from IBM Mainframe to connected networking computer systems. We use multi-tier architecture and HL7 standard to implement our new outpatient hospital information system (HIS). The NTUH HIS is a complex environment with several operating systems, databases, and information systems. We adopt service-oriented architecture (SOA) to reduce the complex relations between systems and solve data consistency problems among databases. We also show that the distributed architecture can provide us stable and reasonable system performances. Our main contribution is proving that the distributed environment with HL7 standard and SOA can sustain in a highly demanding environment

A conference key agreement protocol with fault-tolerant capability

Secure communication is of utmost importance to participants of Internet conferences. Secure communication thwarts eavesdropping. In an Internet conference, all conference participants together establish a common conference key to enable multi-party and secure exchange of messages. However, malicious conference participants may try to obtain the conference key through unfair means, and this could result in the generation of different conference keys. This paper is intended as a proposal of a new form of conference key agreement protocol. It emphasizes the filtering of malicious participants at the beginning of the conference to ensure that all participants obtain the same conference key. The proposed method also has fault-tolerant capability. Efficiency and security of a protocol is important in practice. The security of the proposed protocol is based on discrete logarithm problem assumption. The protocol is executed in computationally secure environment. The secret information of a user cannot be determined from its corresponding public information and therefore ensures privacy. Since efficiency of a protocol depends on low computation cost, the protocol attempts to achieve lower computation cost without compromising on security.

An idle listening-aware energy efficient scheme for the DCF of 802.11n

802.11 wireless local area network (WLAN) technology is now common in power sensitive devices like smart phones and personal digital assistants (PDAs). However, the energy efficiency of such devices will be very low, especially for next generation WLAN technology. The reasons for this include the existence of a large number of active stations, short data time and ultra high physical layer (PHY) data rate, which are the characteristics of next generation WLAN technology. This poor energy efficiency will be due to the fact that the device will consume a lot of idle-listening energy during the Distributed InterFrame Space (DIFS) and back-off time, and that the energy consumed for idle listening is similar to the energy consumed while receiving data. In this article, we propose an intelligent scheme for reducing the energy consumed in idle listening. Our analysis and simulation programs show that our scheme can lengthen the battery endurance due to the shortening in idle-listening time effectively especially when the number of active stations is large. An important characteristic of our scheme is that it is fully compatible with legacy Distributed Coordinated Function (DCF), and there will be no throughput reduction if this power saving scheme is applied to the DCF of 802.11. We also propose an accurate power consumption model in the MAC layer which to the best of our knowledge has not been presented in any earlier research.

Application of Portable CDA for Secure Clinical-document Exchange

Health Level Seven (HL7) organization published the Clinical Document Architecture (CDA) for exchanging documents among heterogeneous systems and improving medical quality based on the design method in CDA. In practice, although the HL7 organization tried to make medical messages exchangeable, it is still hard to exchange medical messages. There are many issues when two hospitals want to exchange clinical documents, such as patient privacy, network security, budget, and the strategies of the hospital. In this article, we propose a method for the exchange and sharing of clinical documents in an offline model based on the CDA—the Portable CDA. This allows the physician to retrieve the patient’s medical record stored in a portal device, but not through the Internet in real time. The security and privacy of CDA data will also be considered.

Design and Analysis of Enhanced Grouping DCF Scheme for the MAC Layer Enhancement of 802.11n with Ultra-high Data Rate

The 802.11 has emerged as the prominent wireless LAN technology as the mobile computing devices such as notebooks and PDA have replaced the desktop computers to be the main trend products. However, if the number of active stations is large, that is high-loading condition for the legacy DCF of 802.11, the capacity will be very low due to high collision costs. In this paper, <i>we</i> <i>introduce</i> <i>the</i> <i>TDMA</i> <i>concept</i> <i>to</i> <i>partition</i> <i>all</i> <i>numerous</i> <i>active</i> <i>stations</i> <i>into</i> <i>several</i> <i>groups</i> <i>to</i> <i>avoid</i> <i>all</i> <i>stations</i> <i>transmitting</i> <i>the</i> <i>frames</i> <i>simultaneously</i>. When Point Coordinator (PC, generally referring to AP) finds that the number of active stations (<i>M</i>) is large i.e. bigger than 8, it broadcasts number of groups (<i>N</i>), group head (<i>Nh</i>) bits and start grouping bit sequence (<i>k</i>) (such as 00000100 00000000 00000000) information in the TIM field of the beacon frame. Once all stations receive this instruction, the stations which last two LSB bits (because <i>k</i>=0, <i>N</i>=4) of the MAC address (IEEE EUI-48 or EUI-64) are 00 belonging to group 0 will transfer their frame first. On the contrary, all stations belonging to other groups will set their waiting time, that is, Network Allocation Vector (NAV) much more precisely. In this article, we also proposed a fast selection scheme to get the optimal start grouping bit sequence which aims to partition all the active stations into a few groups more uniformly to reduce the number of members in each group so that we can reduce the Contention window Minimum (<i>CWMiri</i>), that is, backoffs idle overhead.

WLC34-5: GDCF: Grouping DCF for the MAC layer enhancement of 802.11

The 802.11 has emerged as the prominent wireless LAN technology as the mobile computing devices such as notebooks and PDA have replaced the desktop computers to be the main trend products. However, if the number of active stations is large for the legacy backoff algorithm (DCF) of the 802.11, the capacity will be very low due to high collision cost. In this paper, we introduce the TDMA concept to partition all numerous active stations into several groups to avoid all stations transmitting the frames simultaneously. When Point Coordinator (PC, generally referring to AP) finds that the number of active stations (M) is large i.e. bigger than 16, it broadcasts grouping number and grouping head bits (such as 00000100 00000000) information in the TIM field of the beacon frame. Once all stations receive this instruction, the stations which last two LSB bits of the MAC address are 00 belonging to group 0 will transfer their frame first. On the contrary, all stations belonging to other groups will set their waiting time, that is, Network Allocation Vector (NAV) much more precisely. Analysis shows that the capacity of our GDCF will be near to the theoretical capacity of 802.11 WLAN even if the distributions of all active stations among all groups are not so uniform. This capacity could be independent of the number of active stations and CWmax (contention window maximum).

Design and Implementation of Web-based Discharge Summary Note Based on Service-Oriented Architecture

Discharge summary note is one of the essential clinical data in medical records, and it concisely capsules a patient’s status during hospitalization. In the article, we adopt web-based architecture in developing a new discharge summary system for the Healthcare Information System of National Taiwan University Hospital, to improve the traditional client/sever architecture. The article elaborates the design approaches and implementation illustrations in detail, including patients’ summary query and searching, model and phrase quoted, summary check list, major editing blocks as well as other functionalities. The system has been on-line and achieves successfully since October 2009.

Design and analysis of grouping-based DCF (GB-DCF) scheme for the MAC layer enhancement of 802.11 and 802.11e

The 802.11 has emerged as the prominent wireless LAN technology as the mobile computing devices such as notebooks and PDA have replaced the desktop computers to be the main trend products. However, if the number of active stations is large, that is high-loading condition for the legacy DCF of 802.11, the capacity will be very low due to high collision costs. In this paper, we introduce the TDMA concept to partition all numerous active stations into several groups to avoid all stations transmitting the frames simultaneously. When Point Coordinator (PC, generally referring to AP) finds that the number of active stations (M) is large i.e. bigger than 8, it broadcasts number of groups (Ng) and group head (Nh) bits (such as 00000100 00000000) information in the TIM field of the beacon frame. Once all stations receive this instruction, the stations which last two LSB bits of the MAC address (IEEE EUI-48 or EUI-64) are 00 belonging to group 0 will transfer their frame first. On the contrary, all stations belonging to other groups will set their waiting time, that is, Network Allocation Vector (NAV) much more precisely. Analysis shows that the capacity of our GB-DCF will be near to the theoretical capacity limit of 802.11 WLAN even if the distributions of all active stations among all groups are not so uniform. This capacity could be independent of the number of active stations and CWMax (Contention window maximum). This grouping technique can also be applied to all DCF-based protocols such as EDCA (Enhanced Distributed Coordination Access), called GB-EDCA. In this article, we also simulate the behaviors of GB-EDCA and demonstrate that GB-EDCA can solve the delay jittering problem arising too many QoS stations running simultaneously.

A collaborative knowledge management process for implementing healthcare enterprise information systems

This paper illustrates a feasible health informatics domain knowledge management process which helps gather use- ful technology information and reduce many knowledge misun- derstandings among engineers who have participated in the IBM mainframe rightsizing project at National Taiwan University Hospital (NTUH). Our health informatics domain knowledge management process can be used to publish and retrieve docu- ments dynamically. It effectively creates an acceptable discussion environment and even lessens the traditional meeting burden among development engineers. An overall description on the current system development status is presented. Then, the knowl- edge management implementation of hospital information sys- tems is proposed. Its related effects on the environment pressure, user requirements and project management are also discussed. Keywords—knowledge management, environment design, pro- ject management