The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform
Yasuo Okabe - One of the best experts on this subject based on the ideXlab platform.
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competitive buffer management for multi queue switches in qos networks using Packet Buffering algorithms
Theoretical Computer Science, 2017Co-Authors: Koji M Kobayashi, Shuichi Miyazaki, Yasuo OkabeAbstract:Abstract In this paper, we consider the online buffer management problem, which formulates the problem of managing network switches supporting Quality of Service guarantee. We improve competitive ratios of the 2-value multi-queue switch model, where the value of a Packet is restricted to 1 or α ( ≥ 1 ) . We use a similar approach as Azar and Richter (STOC 2003 and Algorithmica 43(1-2), 2005) did for the multi-value multi-queue switch model. Namely, we show that the competitive ratio of “the relaxed model” of the 2-value multi-queue switch model is at most x = min { c + 2 − c α ( 2 − c ) + c − 1 , c α } , if the competitive ratio of an online algorithm for the unit-value multi-queue switch model is at most c. Azar and Richter's technique implies that if the competitive ratio of the 2-value single-queue switch model is x ′ , then the competitive ratio of the 2-value multi-queue switch model is at most x x ′ . We obtain several results using known c and x ′ .
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competitive buffer management for multi queue switches in qos networks using Packet Buffering algorithms
ACM Symposium on Parallel Algorithms and Architectures, 2009Co-Authors: Koji M Kobayashi, Shuichi Miyazaki, Yasuo OkabeAbstract:The online buffer management problem formulates the problem of queuing policies of network switches supporting QoS (Quality of Service) guarantee. We focus on multi-queue switches in QoS networks proposed by Azar et al. They introduced so-called "the relaxed model". Also, they showed that if the competitive ratio of the single-queue model is at most c, and if the competitive ratio of the relaxed model is at most c2, then the competitive ratio of the multi-queue switch model is cc2. They proved that c2d2, and obtained upper bounds on the competitive ratios for several multi-queue switch models.In this paper, we propose an online algorithm called DS (Dual Scheduling) for the competitive ratio of the relaxed model and obtain some better competitive ratios of the 2-value multi-queue switch model, where the value of Packets is restricted to 1 and α(e1). DS uses as subroutine any online algorithms A for the non-preemptive unit-value switch model, which has also been extensively studied. We prove that if the competitive ratio of A is at most c, then the competitive ratio of DS is at most αc(2--c) + c2--2c+2Dα(2--c)+c--1, which is strictly better than 2.The followings are a couple of examples of the improvement on the competitive ratios of the 2-value multi-queue switch models using our result: (i) We have improved the competitive ratio of deterministic algorithms for the non-preemptive 2-value multi-queue switch model from 4 to 3.177 for large enough B, where B is the number of Packets each queue can simultaneously store. (ii) We have proved that the competitive ratio of randomized algorithms for the non-preemptive 2-value multi-queue switch model is at most 17D2--30≈3.023 for large enough B.
Koji M Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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competitive buffer management for multi queue switches in qos networks using Packet Buffering algorithms
Theoretical Computer Science, 2017Co-Authors: Koji M Kobayashi, Shuichi Miyazaki, Yasuo OkabeAbstract:Abstract In this paper, we consider the online buffer management problem, which formulates the problem of managing network switches supporting Quality of Service guarantee. We improve competitive ratios of the 2-value multi-queue switch model, where the value of a Packet is restricted to 1 or α ( ≥ 1 ) . We use a similar approach as Azar and Richter (STOC 2003 and Algorithmica 43(1-2), 2005) did for the multi-value multi-queue switch model. Namely, we show that the competitive ratio of “the relaxed model” of the 2-value multi-queue switch model is at most x = min { c + 2 − c α ( 2 − c ) + c − 1 , c α } , if the competitive ratio of an online algorithm for the unit-value multi-queue switch model is at most c. Azar and Richter's technique implies that if the competitive ratio of the 2-value single-queue switch model is x ′ , then the competitive ratio of the 2-value multi-queue switch model is at most x x ′ . We obtain several results using known c and x ′ .
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competitive buffer management for multi queue switches in qos networks using Packet Buffering algorithms
ACM Symposium on Parallel Algorithms and Architectures, 2009Co-Authors: Koji M Kobayashi, Shuichi Miyazaki, Yasuo OkabeAbstract:The online buffer management problem formulates the problem of queuing policies of network switches supporting QoS (Quality of Service) guarantee. We focus on multi-queue switches in QoS networks proposed by Azar et al. They introduced so-called "the relaxed model". Also, they showed that if the competitive ratio of the single-queue model is at most c, and if the competitive ratio of the relaxed model is at most c2, then the competitive ratio of the multi-queue switch model is cc2. They proved that c2d2, and obtained upper bounds on the competitive ratios for several multi-queue switch models.In this paper, we propose an online algorithm called DS (Dual Scheduling) for the competitive ratio of the relaxed model and obtain some better competitive ratios of the 2-value multi-queue switch model, where the value of Packets is restricted to 1 and α(e1). DS uses as subroutine any online algorithms A for the non-preemptive unit-value switch model, which has also been extensively studied. We prove that if the competitive ratio of A is at most c, then the competitive ratio of DS is at most αc(2--c) + c2--2c+2Dα(2--c)+c--1, which is strictly better than 2.The followings are a couple of examples of the improvement on the competitive ratios of the 2-value multi-queue switch models using our result: (i) We have improved the competitive ratio of deterministic algorithms for the non-preemptive 2-value multi-queue switch model from 4 to 3.177 for large enough B, where B is the number of Packets each queue can simultaneously store. (ii) We have proved that the competitive ratio of randomized algorithms for the non-preemptive 2-value multi-queue switch model is at most 17D2--30≈3.023 for large enough B.
Doo-seop Eom - One of the best experts on this subject based on the ideXlab platform.
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a handoff Packet marker for diffserv in mobile ip based networks with Packet Buffering
IEEE Transactions on Consumer Electronics, 2009Co-Authors: Seung Beom Lee, Kyeong Hur, Jongkook Kim, Doo-seop EomAbstract:Performance of TCP can be severely degraded in mobile IP-based wireless networks where Packet losses not related to network congestion occur frequently during inter-subnetwork handoffs by user mobility. To solve such a problem in the networks using Mobile IP, the Packet Buffering method at a base station recovers those Packets dropped during handoff by forwarding the buffered Packets at the old base station to the mobile users. But, when the mobile user moves to a congested base station in a new foreign subnetwork, those buffered Packets forwarded by the old base station are dropped and TCP transmission performance of a mobile user degrades severely. In this paper, a PBM (Packet Buffering marker) at a base station is proposed to prevent burst losses of out-of-profile Packets during handoffs for DiffServ Assured Services. From simulation results, it is shown that PBM scheme improves TCP throughputs of an Assured Service flow during handoffs.
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A Packet forwarding controller for mobile IP-based networks with Packet Buffering
IEEE Transactions on Consumer Electronics, 2009Co-Authors: Seung Beom Lee, Kyeong Hur, Jongsun Park, Doo-seop EomAbstract:Performance of TCP can be severely degraded in Mobile IP-based wireless networks where Packet losses not related to network congestion occur frequently during inter-subnetwork handoffs by user mobility. To solve such a problem in the networks using Mobile IP, the Packet Buffering method at a base station recovers those Packets dropped during handoff by forwarding the buffered Packets at the old base station to the mobile users. But, when the mobile user moves to a congested base station in a new foreign subnetwork, those buffered Packets forwarded by the old base station are dropped and TCP transmission performance of a mobile user degrades severely. In this paper, we propose a PFC (Packet Forwarding Controller) required at a base station to increase TCP throughput in Mobile IP-based networks. The PFC at the old base station forwards or discards the buffered Packets during handoffs according to the current status of RED (Random Early Detection) buffer at the congested FA (Foreign Agent) router. Simulation results show that PFC increases throughputs of TCP flows and link utilization.
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priority forwarding for improving the tcp performance in mobile ip based networks with Packet Buffering
Computer Communications, 2007Co-Authors: Kyeong Hur, Doo-seop Eom, Yeonwoo Lee, Jaeho Lee, Seokjoong KangAbstract:Packet losses during the handoff operation by the route optimization extension of the Mobile IP causes performance degradation at the transmission control protocol (TCP). To prevent such degradation a number of Packet Buffering based methods have been proposed in the literature. However, as the mobile host user continually changes location and can sometimes move into a congested BS in a new foreign subnetwork, its buffered Packets are likely to be dropped at the new BS. This can lead to losses at the TCP connections of the mobile user host in the new subnetwork, as well as at the TCP connections of the new BS which experiences severe performance degradation due to the abrupt increase in congestion by the forwarded burst of Packets (i.e., global synchronization). This paper proposes a priority forwarding (PF) scheme designed to significantly improve the performance of the Packet Buffering methods. The proposed PF scheme does not require any modification to the Mobile IP protocol with route optimization extension. The simulation results show that by using the PF scheme the period of global synchronization at the inter-subnetwork handoff is made shorter due to the reduction in Packet droppings in the random early detection (RED) buffer. This improves the TCP performance in wireless networks employing Mobile IP with Packet Buffering.
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tcp performance enhancement by implicit priority forwarding ipf Packet Buffering scheme for mobile ip based networks
Journal of Communications and Networks, 2005Co-Authors: Young Sup Roh, Kyeong Hur, Doo-seop Eom, Yeonwoo Lee, Kyun Hyon TchahAbstract:The smooth handoff supported by the route optimization extension to the mobile IP standard protocol should support a Packet Buffering mechanism at the base station (BS), in order to reduce the degradation in TCP performance caused by Packet losses within mobile network environments. The purpose of Packet Buffering at the BS is to recover the Packets dropped during inter-subnetwork handoff by forwarding the Packets buffered at the previous BS to the new BS. However, when the mobile host moves to a congested BS within a new foreign subnetwork, the buffered Packets forwarded by the previous BS are likely to be dropped. This subsequently causes global synchronization to occur, resulting in the degradation of the wireless link in the congested BS, due to the increased congestion caused by the forwarded burst Packets. Thus, in this paper, we propose an implicit priority forwarding (IPF) Packet Buffering scheme as a solution to this problem within mobile IP based networks. In the proposed IPF method, the previous BS implicitly marks the priority Packets being used for inter-subnetwork handoff. Moreover, the proposed modified random early detection (M-RED) buffer at the new congested BS guarantees some degree of reliability to the priority Packets. The simulation results show that the proposed IPF Packet Buffering scheme increases the wireless link utilization and, thus, it enhances the TCP throughput performance in the context of various inter-subnetwork handoff cases.
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tcp performance analysis of Packet Buffering in mobile ip based networks
IEICE Transactions on Communications, 2004Co-Authors: Kyeong Hur, Kyun Hyon Tchah, Doo-seop EomAbstract:To prevent performance degradation of TCP due to Packet losses in the smooth handoff by the route optimization extension of Mobile IP standard, a few Packet Buffering methods have been proposed. The Packet Buffering at the BS recovers the Packets dropped during an inter-subnetwork handoff, by forwarding the buffered Packets at the previous BS to the new BS to which the mobile host is connected after handoff. However, when the mobile host user moves to a congested BS in a new foreign subnetwork, those buffered Packets are likely to be dropped at the new BS. Thus, as well as the TCP connections of the mobile host which have moved into the new BS, the already existing TCP connections of the new BS experience severe performance degradation. This effect is due to the increased congestion by the forwarded burst Packets; all of the TCP connections can initiate their congestion control algorithms simultaneously, i.e., global synchronization. This paper will consider a general case where a mobile host user moves into a congested BS of a new foreign subnetwork. We analyze the influence of the Packet Buffering on the TCP performance in the new BS, for the Drop-Tail and Random Early Detection (RED) buffers. Simulation results show that although the RED buffer gives better handoff performance than the Drop-Tail buffer, it cannot avoid a large decrease in the TCP throughputs due to global synchronization, when a TCP connection is added at the BS by an inter-subnetwork handoff. Finally, we discuss some methods that can address the negative effect of the Packet Buffering method.
Haijun Yang - One of the best experts on this subject based on the ideXlab platform.
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All-optical variable Buffering strategies and switch fabric architectures for future all-optical data routers
Journal of Lightwave Technology, 2005Co-Authors: Haijun YangAbstract:Future compact and power-efficient all-optical data routers can benefit from versatile all-optical Buffering strategies and switch fabric architectures to achieve high performance. This paper reports two novel variable all-optical-buffer-based optical Packet switching (OPS) fabric architectures and corresponding all-optical contention resolution schemes designed towards this goal. The combined input-queued-and-output-queued OPS (CIOQ-OPS) architecture incorporating enhanced K-stage output buffer units achieves lowest Packet rates with an optimized input and output buffer capacity partition ratio of 0.5, while the multiple-input-queued OPS (MIQ-OPS) architecture achieves the best performance when each input parallel all-optical buffer contains two variable all-optical buffer queues. Simulation results demonstrate that the newly proposed OPS architectures achieve much lower Packet loss rates, Packet Buffering delay, and jitter for a relatively high traffic load level of 0.7. The performance improvement is typically by one or two orders of magnitude compared to the previously reported OPS architectures with all-optical variable delay buffers with a given reasonable all-optical buffer size of 1000 B.
Shuichi Miyazaki - One of the best experts on this subject based on the ideXlab platform.
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competitive buffer management for multi queue switches in qos networks using Packet Buffering algorithms
Theoretical Computer Science, 2017Co-Authors: Koji M Kobayashi, Shuichi Miyazaki, Yasuo OkabeAbstract:Abstract In this paper, we consider the online buffer management problem, which formulates the problem of managing network switches supporting Quality of Service guarantee. We improve competitive ratios of the 2-value multi-queue switch model, where the value of a Packet is restricted to 1 or α ( ≥ 1 ) . We use a similar approach as Azar and Richter (STOC 2003 and Algorithmica 43(1-2), 2005) did for the multi-value multi-queue switch model. Namely, we show that the competitive ratio of “the relaxed model” of the 2-value multi-queue switch model is at most x = min { c + 2 − c α ( 2 − c ) + c − 1 , c α } , if the competitive ratio of an online algorithm for the unit-value multi-queue switch model is at most c. Azar and Richter's technique implies that if the competitive ratio of the 2-value single-queue switch model is x ′ , then the competitive ratio of the 2-value multi-queue switch model is at most x x ′ . We obtain several results using known c and x ′ .
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competitive buffer management for multi queue switches in qos networks using Packet Buffering algorithms
ACM Symposium on Parallel Algorithms and Architectures, 2009Co-Authors: Koji M Kobayashi, Shuichi Miyazaki, Yasuo OkabeAbstract:The online buffer management problem formulates the problem of queuing policies of network switches supporting QoS (Quality of Service) guarantee. We focus on multi-queue switches in QoS networks proposed by Azar et al. They introduced so-called "the relaxed model". Also, they showed that if the competitive ratio of the single-queue model is at most c, and if the competitive ratio of the relaxed model is at most c2, then the competitive ratio of the multi-queue switch model is cc2. They proved that c2d2, and obtained upper bounds on the competitive ratios for several multi-queue switch models.In this paper, we propose an online algorithm called DS (Dual Scheduling) for the competitive ratio of the relaxed model and obtain some better competitive ratios of the 2-value multi-queue switch model, where the value of Packets is restricted to 1 and α(e1). DS uses as subroutine any online algorithms A for the non-preemptive unit-value switch model, which has also been extensively studied. We prove that if the competitive ratio of A is at most c, then the competitive ratio of DS is at most αc(2--c) + c2--2c+2Dα(2--c)+c--1, which is strictly better than 2.The followings are a couple of examples of the improvement on the competitive ratios of the 2-value multi-queue switch models using our result: (i) We have improved the competitive ratio of deterministic algorithms for the non-preemptive 2-value multi-queue switch model from 4 to 3.177 for large enough B, where B is the number of Packets each queue can simultaneously store. (ii) We have proved that the competitive ratio of randomized algorithms for the non-preemptive 2-value multi-queue switch model is at most 17D2--30≈3.023 for large enough B.
