• ETRI Journal
• /
• v.21 no.4
• /
• pp.52-64
• /
• 1999

QoS monitoring is a kind of real-time systems which allows each level of the system to track the ongoing QoS levels achieved by the lower network layers. For these systems, real-time communications between corresponding transport protocol objects is essential for their correct behavior. When two or more entities are employed to perform a certain task as in the case of communication protocols, the capability to do so is called interoperability and considered as the essential aspect of correctness of communication systems. This paper describes a formal approach on modeling and interoperability test case generation of a real-time QoS monitoring protocol. For this, we specify the behavior of flow monitoring of transport layer QoS protocol, i.e., METS protocol, which is proposed to address QoS from an end-to-end's point of view, based on QoS architecture model which includes ATM net work in lower layers. We use a real-time Input/Output finite State Machine to model the behavior of real-time flow monitoring over time. From the modeled real-time I/OFSM, we generate interoperability test cases to check the correctness of METS protocol's flow monitoring behaviors for two end systems. A new approach to efficient interoperability testing is described and the method of interoperability test cases generation is shown with the example of METS protocol's flow monitoring. The current TTCN is not appropriate for testing real-time and multimedia systems. Because test events in TTCN are for message-based system and not for stream-based systems, the real-time in TTCN can only be approximated. This paper also proposes the notation of real-time Abstract Test Suite by means of real-time extension of TTCN. This approach gives the advantages that only a few syntactical changes are necessary, and TTCN and real-time TTCN are compatible. This formal approach on interoperability testing can be applied to the real-time protocols related to IMT-2000, B-ISDN and real-time systems.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.11C
• /
• pp.123-132
• /
• 2001

This paper proposes a sound multicast packet-switching method which can less affect QoS(Quality of Service) degradation. The method includes a switch fabric with extra switching paths dedicated f()r multicast packets. Presented also are both a buffering structure and a scheduling algorithm for the proposed method. Simulation analysis for the method shows that the switching delay of unicast packets is decreased even though arrival rate of multicast packets is increased.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.07a
• /
• pp.556-558
• /
• 2005

대용량의 고속 멀티미디어 데이터 전송 서비스, 주문형비디오 (VoD)와 같이 네트워크 어플리케이션 서비스를 포함하는 서비스들은 높은 대역폭을 요구한다. 이로 인하여, 네트워크에서 혼잡이 일어날 가능성이 증가된다. 네트워크의 혼잡을 피하기 위해서는 물리적인 방법과 논리적인 방법으로 나눌 수 있다. 물리적인 방법은 시간과 고성능의 장비를 필요로 하기 때문에 논리적인 방법으로 제한적인 네트워크의 자원을 효율적으로 사용할 필요성이 있다. 본 논문에서는 멀티미디어 데이터 QoS를 보장하기 위해 트래픽의 특성을 고려하는 차별적인 큐 관리 적용 방안을 제시하고, OPNET을 사용하여 이를 검증한다.

• IE interfaces
• /
• v.22 no.1
• /
• pp.95-103
• /
• 2009

During the past few years, design of experiments (DOE) has been gaining acceptance in the telecommunications research community as a mean for designing and analyzing experiments economically and efficiently. In addition, the need for introducing a systematic robust design methodology (i.e., one of the most popular DOE methodologies) to network simulations has been increasing. In this paper, we present an architecture of voice over IP (VoIP) application and the E-Model for calculating the perceived quality of service (QoS). Then, we apply the Taguchi robust design methodology to optimize the perceived QoS of VoIP application, and describe the detailed step-by-step procedures. We have used ns-2 simulator to collect experimental data in which the SN ratio, a robustness measure, is analyzed to determine an optimal design condition. The analysis shows that "initial delay time in playout buffer" is a major control factor for ensuring robust behaviors of the perceived QoS of VoIP. Finally, we verify the proposed optimal design condition using a confirmation experiment.

• Korean Journal of Adult Nursing
• /
• v.14 no.4
• /
• pp.501-509
• /
• 2002

Purpose: This study was performed to identify the illness intrusiveness, quality of life, and their relationships in patients with chronic liver disease. Method: Data was collected using scales of illness intrusiveness developed by Devins et al and Korean health related quality of life (KoQoLS) developed by Shim et al to measure the illness intrusiveness and quality of life from 141 chronic liver disease patients. Result: The total mean score of illness intrusiveness was $38.85{\pm}18.45$. The domain of illness intrusiveness which showed the highest mean score was health ($4.60{\pm}2.02$), and the lowest mean score domain was relationship with spouse ($20.4{\pm}1.69$). The subcategory of KoQoLS which showed the highest mean score was bodily pain ($6.96{\pm}2.98$), and the lowest mean score subcategory was vitality ($2.75{\pm}1.20$). There were negative relationships between illness intrusiveness and KoQoLS in all subcategories. Abovel all, Illness intrusiveness had the strongest negative relationship with role limitation (r=-0.641) among the KoQoLS subcategories. Conclusion: Because the illness intrusiveness had negative influence on the quality of life in patients with chronic liver disease, further research will need to specify detailed illness intrusiveness and to explore influencing factors on quality of life in them.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.3
• /
• pp.53-58
• /
• 2019

This paper proposes a class-based FQ-CoDel(Flow Queue-Control Delay) algorithm. A variety of application system services create bottlenecks in tactical communication network and the bottlenecks cause some problems such as traffic loss and delay. Therefore, more research on effective traffic processing is needed. The proposed class-based FQ-CoDel algorithm, suggests dynamic buffer management and scheduling, classifies specific packets in each queue according to service attribute and criticality and checks periodically latency of the packets in each queue. Also, it abandons the packets if some packets stay in queue above schedule time and manages the total amount of traffic stored in queue with certain level.

• Journal of KIISE:Information Networking
• /
• v.34 no.5
• /
• pp.396-404
• /
• 2007

In this paper, an Ad-hoc Routing Protocol which works in wireless Ad-hoc communication networks with multiple radios and multiple channels, and controls call admission based on bandwidth measurement is proposed. Unlike the conventional Ad-hoc node with a single radio using a single channel, an Ad-hoc node of the protocol proposed, MCQosR(Multiple Channel Quality of Service Routing), has multiple radios and uses multiple channels, which makes full duplex transmission between wireless Ad-hoc nodes, and reduces the intra interference on a route. Also, a fixed channel only for reception at each node enables the measurement of the available bandwidth, which is used to control the call admission for QoS provision. The performance of MCQosR is verified by simulation.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.16 no.2
• /
• pp.160-168
• /
• 2013

In tactical environment, tactical wireless networks are generally comprised of Tactical MANETs(T-MANETs) or Tactical WMNs(T-WMNs). The most important services in tactical network are voice and low rate data such as command control and situation awareness. These data should be forwarded via multi-hop in tactical wireless networks. Urgent and mission-critical data should be protected in this environment, so QoS(Quality of Service) must be guaranteed for specific type of traffic for satisfying the requirement of a user. In IEEE 802.11s, TDMA-based MAC protocol, MCCA(MCF Controlled Channel Access), has a function of resource reservation. But 802.11s protocol can not guarantee the end-to-end QoS, because it only supports reservation with neighbors. In this paper, we propose the routing protocol, R-HWMP(Reservation-based HWMP) which has the resource reservation to support the end-to-end QoS. The proposed protocol can reserve the channel slots and find optimal path in T-WMNs. We analyzed the performance of the proposed protocol and showed that end-to-end QoS is guaranteed using NS-2 simulation.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.1
• /
• pp.11-23
• /
• 2014

Wireless Mesh Network(WMN) has drawn much attention due to easy deployment and good scalability. Recently, major power utilities have been focusing on R&D to apply WMN technology in Smart Grid Network. Smart Grid is an intelligent electrical power network that can maximize energy efficiency through bidirectional communication between utility providers and customers with ICT(Information Communication Technology). It is necessary to guarantee QoS of some important data in Smart Grid system such as real-time data delivery. In this paper, we suggest QoS enhancement method for WMN based Smart Grid system using IEEE 802.11s. We analyze Smart Grid Application characteristics and apply IEEE 802.11s WMN scheme for Smart Grid in domestic power communication system. Performance evaluation is progressed using NS-2 simulator implementing IEEE 802.11s. The simulation results show that the QoS enhancement scheme can guarantee stable bandwidth irrespective of traffic condition due to IEEE 802.11s reservation mechanism.

• The Journal of Korean Medicine
• /
• v.41 no.2
• /
• pp.34-42
• /
• 2020

Background and Objectives: The purpose of this study was to examine the relationship between between one's quality of life (QoL) level and the arterial stiffness estimated by the second derivative of photoplethysmogram (SDPTG) for women patients. Methods: A retrospective chart review was performed on charts of 407 women patients (38.38±11.82 years) who visited Gangdong Kyung Hee Hospital between April 1st and September 30th, 2011. Vascular aging index (VAI, (b-c-d)/a), b/a, c/a, and d/a were considered as the arterial stiffness indexes, and the Korean version of the Short-Form 36 (SF-36) were completed to estimate one's physical and mental QoL. Results: Physical and mental components of the SF-36 in older group (50, 60, and 70 years-group) were lower than those in younger group (20 and 30 years-group). Large arterial stiffness-related b/a in older group was higher that in younger group, while small arterial stiffness-related d/a in older group was lower that in younger group. Physical and mental component scores of the SF-36 had the negative correlations with VAI and b/a (r; -0.153~-0.195), while had the positive correlations with c/a and d/a (r; 0.147~0.228). Conclusions: In conclusion, this study suggests that convenient and cost-effective SDPTG test may serve as an auxiliary tool to estimate one's physical and mental QoL.