• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권3호
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• pp.997-1010
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• 2014

Today, as the hierarchical cellular system is getting more attention than before, some recent studies introduce delay based admission control (AC) scheme which delays the admission to the macro-embedded small cell for a relatively short time to prevent unnecessary handover caused by the short-term visitors of the small cell area. In such delay based ACs, when we use improper delay parameter, the system frequently makes incorrect handover decisions such as where unnecessary handover is allowed due to too short delaying, or where necessary handover is denied due to too long delaying. In order to avoid these undesirable situations as much as possible, we develop a new delay parameter decision method based on probabilistic cell residence time approximations. By the extensive numerical and analytical evaluations, we determine the proper delay parameter which prevents the incorrect handover decision as much as possible. We expect our delay parameter decision method can be useful system administration tips in hierarchical cellular system where delay based AC is adopted.

• 한국통신학회논문지
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• 제37B권12호
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• pp.1174-1185
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• 2012

본 논문은 무선메쉬네트워크 환경에서 패킷의 지연 보장을 위한 호 접속 제어 방안을 제안하였다. 각 노드에서 클래스별 가용 대역폭을 구하여 지연 성능을 예측하고 이를 기반으로 호 접속 허용 여부를 결정짓는다. 새로운 트래픽 증가로 인해 영향 받는 모든 노드들을 호 접속 제어에 반영하여 기존 트래픽의 지연 성능이 보전되도록 하였다. 그 과정에서 추가적인 메시지 교환 없이 간섭 노드들의 가용 대역폭을 효과적으로 관측하는 방안을 제시하였다. 클래스 간의 차별화된 지연 제어는 큐잉 정책으로 수용하여 MAC 동작을 간결하게 하였다. 컴퓨터 시뮬레이션을 이용하여 제안된 방식의 타당성을 확인하였다. 새로운 호 추가에 따르는 지연 예상이 적절하게 이루어짐을 확인하였고, 호 접속 제어 기능으로 지연 성능이 보장되는 것을 보였다.

• 한국통신학회논문지
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• 제23권9A호
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• pp.2184-2196
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• 1998

Admission control is one of the most important congestion control mechanism to be executed at the call set up phase by regulating traffic into a network in a preventive way. An efficient QOS evaluation or bandwidth estimation method is required for call admission to be decided in real time. In this paper, we spropose a computtionally simple approximation method of estimating cell loss probability and mean cell delay for admission control of both delay sensitive and loss sensitive calls. Mixed input queueing system, where a new call combines with the existing traffic, is used as a queueing model for QOS estimation. Also traffic parameters are suggested to characterize both a new call and existing traffic. Aggregate traffic is approximated by a renewal process with these traffic parameters and then mean delay and cell loss probability are detemined using appropriate approximation formulas. The accuracy of this approximation approach is examined by comparing their results with exact analysis or simulation results of vrious mixed unput queueing systems. Based on this QOS estimation method, call admission control scheme which is traffic independent and computable in yeal time are proposed.

• 정보처리학회논문지A
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• 제8A권3호
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• pp.217-226
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• 2001

본 논문은 클러스터 기반의 분산 구조를 갖는 CCMSS(Clustered Continuous Media Storage Server) 시스템의 미디어 검색 동작에 대해 디스크의 입출력 지연 시간 뿐맘 아니라 내부 네트워크의 통신 지연 시간을 함께 고려한, 열린 큐잉 네트워크 기반의 해석적 모델을 제시하고 이를 이용하여 전체 서비스 지연 시간에 대한 확률적 모델을 정의한다. 그리고 정의된 확률적 모델을 바탕으로 허용된 서비스 실패율 범위에서 최대 서비스 가능한 사용자 요구 수를 구하고 이 값을 이용하여 승인 제어를 수행하는 통합형 통계적 승인 제어 모델을 제안한다. 제안된 승인 제어 기법의 성능 분석을 위해 단순히 디스크 성능만을 고려한 확률적 모델과 본 논문에서 제안한 디스크 성능과 내부 네트워크의 성능을 함께 고려한 확률적 모델을 통해 산출한 마감시간 실패율과 실제 클러스터 기반 서버 환경에서 모의 실험을 통해 얻은 결과를 비교하였으며, 실험 결과에 대한 분석을 통해 제안된 승인 제어 기법이 CCMSS 시스템의 실제 서비스 지연 요소를 정확히 반영하고 있다는 것을 알 수 있었다.

• ETRI Journal
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• 제39권3호
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• pp.345-352
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• 2017

Traffic management is a highly beneficial mechanism for satisfying quality-of-service requirements and overcoming the resource scarcity problems in networks. This paper introduces an optimal connection admission control mechanism to decrease the packet loss ratio and end-to-end delay in cognitive radio sensor networks (CRSNs). This mechanism admits data flows based on the value of information sent by the sensor nodes, the network state, and the estimated required resources of the data flows. The number of required channels of each data flow is estimated using a proposed formula that is inspired by a graph coloring approach. The proposed admission control mechanism is formulated as a semi-Markov decision process and a linear programming problem is derived to obtain the optimal admission control policy for obtaining the maximum reward. Simulation results demonstrate that the proposed mechanism outperforms a recently proposed admission control mechanism in CRSNs.

• ETRI Journal
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• 제22권4호
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• pp.40-50
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• 2000

We apply a "sliding-window" Maximum Likelihood(ML) estimator to estimate traffic parameters On-Off source and develop a method for estimating stochastic predicted individual cell arrival rates. Based on these results, we propose a simple Connection Admission Control(CAC)scheme for delay sensitive services in broadband onboard packet switching satellite systems. The algorithms are motivated by the limited onboard satellite buffer, the large propagation delay, and low computational capabilities inherent in satellite communication systems. We develop an algorithm using the predicted individual cell loss ratio instead of using steady state cell loss ratios. We demonstrate the CAC benefits of this approach over using steady state cell loss ratios as well as predicted total cell loss ratios. We also derive the predictive saturation probability and the predictive cell loss ratio and use them to control the total number of connections. Predictive congestion control mechanisms allow a satellite network to operate in the optimum region of low delay and high throughput. This is different from the traditional reactive congestion control mechanism that allows the network to recover from the congested state. Numerical and simulation results obtained suggest that the proposed predictive scheme is a promising approach for real time CAC.

• 한국콘텐츠학회논문지
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• 제12권4호
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• pp.69-75
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• 2012

본 논문에서는 다양한 서비스의 QoS를 제공하기 위하여 호 수락 제어(Call Admission Control : CAC) 알고리즘에 트래픽 혼잡비를 적용했을 때 평균 데이터 전송율과 평균 패킷 지연시간을 비교 평가하였다. 우선권 기반의 트래픽 혼합비가 1:1:4:4일 때 호 수락 제어 알고리즘을 적용하지 않았을 경우 FTP 서비스는 0.4일 때, 웹 서비스는 0.6일 때, 스트리밍 서비스는 0.7일 때 패킷 지연 요구사항을 만족하지 못하는 것과는 달리 제안하는 호 수락 제어 알고리즘을 적용하였을 경우 성능 평가를 수행한 모든 도착률에 대해 모든 서비스의 패킷지연을 만족함을 보였다. 또한 WWW, FTP, Video, VoIP 서비스를 대상으로 호 수락 제어 알고리즘을 적용하여 트래픽 혼합비 환경에서 서비스의 QoS를 보장할 수 있음을 확인하였다.

• ETRI Journal
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• 제24권1호
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• pp.43-55
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• 2002

This paper proposes a flow-based admission control algorithm through an Asynchronous Transfer Mode (ATM) based Multi-Protocol Label Switching (MPLS) network for multiple service class environments of Integrated Service (IntServ) and Differentiated Service (DiffServ). We propose the Integrated Packet Scheduler to accommodate IntServ and Best Effort traffic through the DiffServ-aware MPLS core network. The numerical results of the proposed algorithm achieve reliable delay-bounded Quality of Service (QoS) performance and reduce the blocking probability of high priority service in the DiffServ model. We show the performance behaviors of IntServ traffic negotiated by end users when their packets are delivered through the DiffServ-aware MPLS core network. We also show that ATM shortcut connections are well tuned with guaranteed QoS service. We validate the proposed method by numerical analysis of its performance in such areas as throughput, end-to-end delay and path utilization.

• 조명전기설비학회논문지
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• 제24권7호
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• pp.26-40
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• 2010

We propose a new routing protocol, MCQosR, that is based on bandwidth estimation, admission control, and a routing metric, MCCR - suitable for wireless ad-hoc networks with multiple radios and channels. To use the full capacity of a wireless link, we assume a node with multiple radios for full duplex operation, and a radio using multiple channels to exclude route-intra interference. This makes it possible to use the capacity of a wireless link. Then, to provide bandwidth and delay guarantee, we have a radio with a fixed channel for layer-3 data reception at each node, used to estimate the available bandwidth and expected delay of a wireless link. Based on the estimate of available bandwidth and delay, we apply the call admission control to a new call requiring bandwidth and delay guarantee. New calls with traffic that will overflow link or network capacity are rejected so the accepted calls can use the required bandwidth and delay. Finally, we propose a routing metric, MCCR, which considers the channel contentions and collisions of a wireless link operating in CSMA/CA. MCCR is useful for finding a route with less traffic and distributing traffic over the network to prevent network congestion as much as possible. The simulation of the MCQosR protocol and the MCCR metric shows traffic is distributed and guaranteed service is provided for accepted calls.

• 한국IT서비스학회지
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• 제9권3호
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• pp.83-93
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• 2010

P2P streaming technology has advantages of scalability and availability comparing to the popular IP multicast. This paper proposes an approach to apply the P2P streaming technology to the delay-sensitive multimedia multicast applications. In order for the P2P streaming to be applied to the delay-sensitive applications, prior construction of delay-guaranteed overlay network is necessarily required. Moreover, the delay-guaranteed overlay network should be able to be kept even when the hand-overs occur owing to the departures of the intermediate P2P peers. This paper proposes a delay-guaranteed overlay network construction method by using the bandwidth and end-to-end delay based admission control and the backup peer based hand-over control mechanism.