• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.21-24
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• 2001

For very large multimedia traffic to be supported successfully in wireless network environment, it is necessary to provide Quality-of-Service(QoS) guarantees between mobile hosts(clients). In order to guarantee the Qos, we have to keep the call blocking probability below target value during handoff session. However, the QoS negotiated between the client and the network may not be guaranteed due to lack of available channels for traffic in the new cell, since mobile clients should be able to continue their on-going sessions. In this paper we propose a efficient load-balancing algorithm based on the adaptive bandwidth reservation scheme for enlarging available channels in a cell. We design a new method to predict the mobility of clients using MPT(mobility profile table). This method is then used to reserve a part of bandwidths for handoff calls to its adjacent cells and this reserved bandwidth can be used for handoff call prior to new connection requests. If the number of free channels is also under a low threshold value, our scheme use a load-balancing algorithm with a adaptive bandwidth reservation. In order to evaluate the performance of our algorithm, we measure the metrics such as the blocking probability of new calls and dropping probability of handoff calls, and compare with other existing schemes.

• Journal of Korea Multimedia Society
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• v.5 no.4
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• pp.441-449
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• 2002

For multimedia traffics to be supported successfully in wireless network environment, it is necessary to provide Qualify-of-Service(QoS) guarantees among mobile hosts(clients). In order to guarantee the QoS, we have to keep the call blocking probability below a target value during hand-off session. However, the QoS negotiated between the client and the network may not be guaranteed due to lack of available channels for traffic of a new cell, since on service mobile clients should be able to continue their sessions. In this paper, we propose an efficient load-balancing algorithm based on the adaptive bandwidth reservation scheme for enlarging available channels in a cell. Proposed algorithm predicts the direction of clients in a cell and adjusts the amount of the channel to be reserved according to the load status of the cell. This method is used to reserve a part of bandwidths of a cell for hand-off calls to its adjacent cells and this reserved bandwidth can be used for hand-off call prior to new connection requests. If the number of free channels is also under a low threshold value, our scheme use a load-balancing algorithm with an adaptive bandwidth reservation. In order to evaluate the performance of our algorithm, we measure metrics such as the blocking probability of new calls and dropping probability of hand-off calls, and compare with those of existing schemes.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.1401-1404
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• 2004

점증하고 있는 무선망에서의 다양한 멀티미디어 서비스를 안정적으로 지원하기 위해서는 효율적인 대역폭 관리가 필수적이다. 본 논문에서는 차세대 네트워크의 기반이 되는 계층 셀 구조에서, 대역폭의 효율적인 관리를 지원하기 위한 통합 프레임워크를 제안하였다. 현재 트래픽의 과밀도와 사용자의 이동성을 기반으로 적절한 셀 선택, 대역폭 예약 및 재설정, 버퍼링 등의 알고리즘을 설계하였으며, 이들을 유기적으로 통합, 시스템 전반의 QoS를 향상시켰다.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.4
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• pp.430-440
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• 2000

To support Integrated Services in the Internet, the Internet Engineering Task Force(IETF) has developed new mechanisms. These new mechanisms include Resource Reservation Protocol(RSVP) and Integrated Services model. RSVP and Integrated Services are independent of the underlying link layer technologies and it is necessary to define the mapping of RSVP and Integrated Services specifications onto specific link layer technologies. IETF proposed a Subnet Bandwidth Manager(SBM) providing a method for mapping RSVP onto IEEE802 style networks. However, the SBM has several constraints and problems. For solving these constraints and problems, we design and implement a new Ethernet Bandwidth Manager(EBM). This paper discusses (1) new bandwidth management mechanism independent of RSVP, (2) simulation of Ethernet bandwidth to analyze the characteristics of Ethernet and accomplish Ethernet bandwidth management, (3) design and implemetation of EBM that allows Controlled-Load Service, and (4) results of our experiments on EBM.

• The KIPS Transactions:PartC
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• v.12C no.5 s.101
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• pp.701-708
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• 2005

The mobility prediction algorithm and the channel reservation scheme have been reported as an effective means to provide QoS guarantees and the efficient resource reservation in wireless networks. Among these prediction algorithms, the recently proposed Detailed-ZMHB algorithm makes use of the history of the user's positions within the current cell to predict the next cell, which provides the better prediction accuracy than the others. The handoff prioritizing schemes are proposed to provide improved performance at the expense of an increase in the blocking probability of new calls. In the soft handoff of the CDMA systems, a mobile can communicate via two adjacent cells simultaneously for a while before the actual handoff takes place. In this paper, we propose a new channel reservation scheme making use of the user mobility pattern information in order to reduce the call dropping probability. Our results show that the proposed scheme gives about 67.5-71.1$\%$ lower call dropping probability, compared to the existing scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.114-121
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• 2000

The problem of an input-buffered switch is the HOL(head-of-line) blocking which limits the maximum throughput but it is easy to implement in hardware. However, HOL blocking can be eliminated using aVOQ(virtual-output-queueing) technique. 0 this paper, we propose a new cell-scheduling algorithm for aninput-buffered ATM switch. The proposed algorithm, called PPIM(Probabilistic Parallel Iterative Matching), imposesa weight to every request based on the reserved bandwidth. It is shown that the input-buffered ATM switch withthe proposed PPIM algorithm not only provides high throughput and low delay but it also reduces the jitter,compared with the existing WPIM(Weighted PIM).

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.562-564
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• 1998

다수의 수신자에게 동일한 데이터를 전송할 경우에 경로가 동일한 라우터까지는 단일의 데이터만을 전송하고 라우터에서 다음에 가야 할 곳에 각각의 데이터를 전송하는 멀티캐스트가 개발되어 정보전송에 필요한 대역폭의 축소와 비용절감 등의 효과를 가져왔다. 이러한 멀티캐스트를 이용하는 서비스의 질을 보장해 주기 위해서 자원예약 프로토콜이 사용된다. 본 논문에서는 멀티캐스트 라우팅 프로토콜과 자원예약 프로토콜과 멀티캐스트 그룹멤버가 RP(Rendezvous Point)를 중심으로 모든 수신자에 이르는 경로를 설정하는 PIM-SM과, 서비스 질을 보장해 주기 위한 자원예약 프로토콜 중에서 수신자가 요구하는 QoS를 만족시켜 주기 위한 수신자 관점의 자원예약 프로토콜 RSVP를 사용하여 데이터를 전송시에 RSVP의 적용시점을 고려하여 효율적인 QoS를 보장한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.7
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• pp.696-708
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• 1992

In this study, we have several objectives. First, In spite of a fixed bandwidth waste of reservation channel, we maximize the efficiency of transmission channel by the multiple access algorithm that performs channel reservation and data transmission independently, eliminating the frame structure of transmission channel and reserving it by the slot unit . Second, In order to improve the entire system performance, we accommodate the variation of traffic at each earth station more effectively, and accomplish the stable delay characteristics and the equlity of service #or users. For this purpose, we design the satellite channel that consists of reservation channel and transmission channel which are logically separate and operate Independently. We also design a demand assignment multiple access algorithm based on the satellite channel structure.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.948-951
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• 2010

네트워크 기술의 발전과 하드웨어의 발전으로 인해 많은 네트워크 응용 서비스 기술이 등장하고 있다. 이 중에서도 IPTV 와 같은 멀티미디어 스트리밍 기술은 그 수요에 의해 기하급수적으로 증가하고 있는 실정이다. 만족할만한 IPTV 서비스를 제공해 주기 위해서는 안정적인 네트워크 자원의 확보가 필수적이다. 이에 본 논문에서는 IPTV 서비스를 위한 네트워크 자원 확보를 위해 기존의 AVB 기술을 기반으로 하여 안정적인 QoS 를 보장하는 방법을 제안한다. IPTV 서비스에 해당하는 각 트래픽에 대한 대역폭 예약 방법과, 대역폭 예약 실패 상황에 대해 처리할 수 있는 개선된 MSRP를 이용하여 IPTV 서비스의 QoS 를 보장하고자 한다. 본 논문의 성능 평가를 위해 OPNET 을 이용하여 기존 방법들에 대한 시간동기의 정확성, 트래픽의 단대단지연, 네트워크 자원 활용률을 측정하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1512-1520
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• 2000

The wireless communication network is evolving toward IMT-2000 for providing various multimedia services. In order to accomplish this ultimate goal the effective schemes are required which can dynamically utilize the limited wireless resources based on different traffic characteristics of various services. This paper proposes a novel bandwidth allocation and call admission control scheme to transmit multimedia traffic based on the bandwidth reservation procedure using direction estimation in the IMT-2000 This scheme estimates the position of mobiles based on the mliticriteria decision making in which uncertain parameters such as RSS(Received Signal Strength), the distance between mobile and base station the moving direction and the previous location are participated in the decision process using aggregation function in fuzzy set theory. Its effectiveness is investigated by simulation.