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ATM 망에서 효율적으로 ABR 서비스를 제공하는 확장된 VS/VD 스위칭 알고리즘
전광탁,양해권 群山大學校 情報通信技術硏究所 1999 情報通信技術硏究論文集 Vol.3 No.-
The ATM Forum has been focusing on flow control mechanism for ABR traffic management. The goal of this activity is to efficiently manage the leftover network bandwidth and fairly distribute it among contending ABR VC so that communication links can be optimally utilized. ABR traffic is difficult to predict traffic shape because it has bursts and variable behavior. Also it's sensitive to lose but not to delay. This behavior makes difficult to UPC function in network and cause of congestion in switch, thus performance is degraded. To resolve this problem, various flow control mechanism has been worked in the ATM Forum. Especially, the rate-based flow control mechanism for ABR traffic has been standardized in the ATM Forum, Sept. 1994. Thus, various flow control mechanism has been working which liked EFCI, ER, VS/VD. VS/VD control is superior than existed ER ontrol because it isolate different networks from each other. In this paper, we propose an expanded VS/VD flow control algorithm and compare with existed VS/VD flow control algorithm. Simulation result shows that this algorithm improve a problem in aspect of delay and buffer occupancy and provide a better performance to ABR service in response time, throughput and link rate.
무선 ATM망에서의 동적 대역폭 할당 알고리즘에 대한 QoS 성능 연구
류기훈,김지연,전광탁,양해권 군산대학교 정보통신기술연구소 2000 情報通信技術硏究論文集 Vol.4 No.-
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. As cell size is smaller, signal power level is lower Handover is implemented by the network to give the users freedom of motion beyond a limited wireless coverage area while they are communication. The handover is procedure by which a user's radio link is transferred from one radio port to another through the network without an interruption of the user collection. 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 hangover mechanism with wireless ATM. Thus, only the bandwidth for corresponding adjacent cell, that is from estimation, is chosen to be reserved; this method drastically reduces the waste of bandwidth, and improves the efficiency in performance. Comparing with static bandwidth allocation algorithm, the proposed algorithm make a bandwidth allocation more efficient. As for the QoS, it has been shown that proposed algorithm shows better performance than that with static bandwidth allocation algorithm.