• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.3
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• pp.465-474
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• 2001

In the network with small cell radius, a mobile terminal which has large mobility should perform frequent handover. This requires that handover mechanism must be done fastly. The currently existing method for handover uses an algorithm in which the bandwidth corresponding to the adjacent cells is supposed to be allocated. However, this method leads to the problem of requiring bandwidth allocation for many-unknown cells, due to the lack of information toward moving direction in mobile terminal. In this paper, we propose an efficient dynamic bandwidth allocation algorithm for solving those problem above, based on both path rerouting handover and soft handover mechanism with wireless ATM. As for the QoS, it has been shown that proposed algorithm shows better performance than that with static bandwidth allocation algorithm.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.322-324
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• 2000

본 논문에서는 이동 컴퓨팅 환경에서 이동 호스트에게 실시간 서비스의 Quality of Service(QoS)를 제공하기 위한 자원 예약 프로토콜을 제시, 설명한다. 실시간 서비스를 제공하는데 있어 이동성은 통신 경로의 변경으로 인해 QoS에 심각한 영향을 끼치게 된다. 그러나 현재 QoS를 위한 signaling 프로토콜인 자원 예약 프로토콜(Resource ReServation Protocol , RSVP)은 고정 호스트만을 가정하고 있으므로 이동 컴퓨팅 환경에서 그대로 사용하기에는 적합하지 않다. 이에 본 논문에서는 이동 호스트를 지원하는 Integrated Network에서 RSVP Agent를 사용하여 Mobile IP와 연동하는 새로운 signaling프로토콜을 제안한다. RSVP Agent는 RSVP tunnel을 사용하여 이동호스트를 대신해서 주위의 ？들에 미리 자원을 예약해 주는 역할을 하게 된다. 이 후 이동 호스트는 RSVP Agent가 미리 예약해준 자원을 사용하게 됨으로써 고정 호스트에게 상대 노드의 이동성을 고려하여 자원을 예약하지 않아도 되도록 지원해주며, 경로 마다 관리해야 하는 soft-state 유지비용의 감소를 가져오고, 불필요한 bandwidth의 예약을 막고, 패킷 지연을 줄여 주는 효과를 가져오게 되며 그 결과를 시뮬레이션을 통하여 확인해 본다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7B
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• pp.638-646
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• 2003

In this paper, we propose a group communication approach which can provide quality of service for soft real-time applications. This proposed scheme combining the explicit multicast, end-point measure-based admission control scheme(EMBAC), and diffserv, removes the need of maintaining state information in the network, so that it would be easily deployable in real networks. We propose the scheme of node configuration to measure the quality of the diffserv network, and that of managing EMBAC over group communication environment. By simulation, we validate the QoS of the proposed multicast service network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.1
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• pp.38-55
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• 2013

Wireless network systems provide fast data transmission rates and various services to users of mobile devices such as smartphones and smart pads. Because many people use high-performance mobile devices, the use of real-time multimedia services is increasing rapidly. However, the preoccupation of resources by real-time traffic users is causing harm to other services-for example, frequent call interference, lowered service quality, and poor network performance. This paper suggests a resource allocation algorithm for effective traffic service support in a hybrid network. The main objective is to obtain an optimum value of data rates by comparing user requirements with the amount of resources that can be allocated. A new mechanism based on Adaptive-Quality of Service (QoS) and a monitoring system based on Queue-Aware are proposed. Adaptive-QoS supports effective resource control according to the type of traffic service, and the monitoring system based on Queue-Aware measures the amount of resources in order to calculate the maximum that can be allocated. We apply our algorithm to a test system and use Qualnet 4.5.1 to evaluate its performance.

• Journal of Communications and Networks
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• v.7 no.2
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• pp.178-191
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• 2005

Fourth-generation (4G) wireless networks will be the IP-based cellular networks integrating Internet with the existing cellular networks. Two important issues should be concerned in the IP-based cellular networks, IP mobility, and quality-of-service (QoS) guarantees. In this paper, we proposed two mechanisms to solve the problems with IP mobility and RSVP-based QoS provisioning. First, virtual-IP (VIP) allocation scheme in areas with a large rate of handoff can minimize the wireless signaling overhead due to IP mobility. The access routers (ARs) create dynamically the VIP zone by using the measured handoff rate derived from the history of the handoff into neighboring ARs. We show that VIP allocation scheme reduces the binding update messages in the wireless link than hierarchical mobile IPv6. Second, the new advance resource reservation protocol called proportional aggregate RSVP (PA-RSVP) can minimize waste of bandwidth and soft state refresh overhead due to IP mobility. It allocates the bandwidth in advance between the mobility anchor point and neighboring ARs using proportional aggregate reservation. We also show that PA-RSVP provides an improved performance over existing protocols.

• Journal of information and communication convergence engineering
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• v.8 no.1
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• pp.1-5
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• 2010

In this paper, we propose for improving QoS in wireless micro cellular network using Cellular-IP/PRC(Paging Route Cache) with Paging Cache and Route Cache in Cellular-IP and propose for performance of realtime and non-real time handoff service using Handoff state machine Paging Route Cache. Although the Cellular-IP/PRC technology is devised for mobile internet communication, it bas its vulnerability in frequent handoff environment. On the other hand, Cellular IP combines the capability of cellular networks to provide high performance handoff and efficient location management of active and idle mobile users with the inherent flexibility, robustness and scalability found in IP networks. Also Cellular-IP/PRC use semi-soft handoff. During semi-soft hand off a mobile host may be in contact with either of the old and new base stations and receive packets from them. Packets intended to the mobile node are sent to both base stations and buffered, so when the mobile host eventually moves to the new location it can continue to receive packets without interruption. It should be suitable for realtime service such as multimedia traffic. But, much waste of resource will occur in this method, especially for non-real time services such as FTP and E-mail. Therefore, a new algorithm that performs different handoff according to characteristic of each traffic by use of reserved field in IP packet is proposed in this thesis. This hand off state machine using differentiated handoff improves quality of services in Cellular-IP/PRC. Suggested algorithm shows better performance than existing technology in wireless mobile internet communication environment. Matlab simulation results are improving QoS, show call drop and call blocking provided to Paging Router Cache during handoff state machine in Cellular-IP/PRC.

• Archives of Plastic Surgery
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• v.51 no.2
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• pp.212-233
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• 2024

This is a retrospective review of surgical management for primary lymphedema. Data were extracted from 55 articles from PubMed MEDLINE, Web of Science, SCOPUS, and Cochrane Central Register of Controlled Trials between the database inception and December 2022 to evaluate the outcomes of lymphaticovenous anastomosis (LVA) and vascularized lymph node transfer (VLNT), and outcomes of soft tissue extirpative procedures such as suction-assisted lipectomy (SAL) and extensive soft tissue excision. Data from 485 patients were compiled; these were treated with LVA (n = 177), VLNT (n = 82), SAL (n = 102), and excisional procedures (n = 124). Improvement of the lower extremity lymphedema index, the quality of life (QoL), and lymphedema symptoms were reported in most studies. LVA and VLNT led to symptomatic relief and improved QoL, reaching up to 90 and 61% average circumference reduction, respectively. Cellulitis reduction was reported in 25 and 40% of LVA and VLNT papers, respectively. The extirpative procedures, used mainly in patients with advanced disease, also led to clinical improvement from the volume reduction, as well as reduced incidence of cellulitis, although with poor cosmetic results; 87.5% of these reports recommended postoperative compression garments. The overall complication rates were 1% for LVA, 13% for VLNT, 11% for SAL, and 46% for extirpative procedures. Altogether, only one paper lacked some kind of improvement. Primary lymphedema is amenable to surgical treatment; the currently performed procedures have effectively improved symptoms and QoL in this population. Complication rates are related to the invasiveness of the chosen procedure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.271-281
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• 2005

This paper for establishing the reliability of the TPC command is introduced, where the soft symbol of the TPC command itself is directed used as a reliability indicator. In addition to the new reliability estimation, the concept of parallel use of TPC algorithms is presented. The results show that the soft symbol reliability estimation decrease the $P_{tx}$ levels with 0.3 dB, thus providing a useful capacity gain. The parallel use of 2 to 4 algorithms is also shown to decrease the sensitivity of the algorithms to the algorithm thresholds used, and thus increase the feasibility of the algorithms in a real world networks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.10
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• pp.3361-3377
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• 2014

Synchronous computing models provided by real-time synchrony protocols, such as TTA [1] and PALS [2], greatly simplify the design, implementation, and verification of real-time distributed systems. However, their application to real systems has been limited since their assumptions on underlying systems are hard to satisfy. In particular, most previous real-time synchrony protocols hypothesize the existence of underlying fault tolerant real-time networks. This, however, might not be true in most soft real-time applications. In this paper, we propose a practical approach to a synchrony protocol, called Quality-Aware PALS (qPALS), which provides the benefits of a synchronous computing model in environments where no fault-tolerant real-time network is available. qPALS supports two flexible global synchronization protocols: one tailored for the performance and the other for the correctness of synchronization. Hence, applications can make a negotiation flexibly between performance and correctness. In qPALS, the Quality-of-Service (QoS) on synchronization and consistency is specified in a probabilistic manner, and the specified QoS is supported under dynamic and unpredictable network environments via a control-theoretic approach. Our simulation results show that qPALS supports highly reliable synchronization for critical events while still supporting the efficiency and performance even when the underlying network is not stable.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.571-574
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• 2002

In a recent wireless network environments, dynamic host configuration protocol (BHCP) service is used to assign IP addresses to mobile terminals. In IPv6 networks, it is necessary to introduce the concept of handoff to support a seamless service to mobile terminals. In a general soft handoff technique used by code-division multiple acces (CDMA) communication systems, the powers received to base station are simply compared to determine which base station will handle the signal to and from each mobile termins. However, in IPv6 network, to transmit data-oriented services, it is necessary to support an enhanced soft handoff technique with more security and quality of service. In this paper, we propose a scheme to reduce a signaling process of handoff in IPv6 network. Also, we propose a technique to reduce wasted reservation resources and to guarantee quality of service (QoS) using DHCP.