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Throughput Optimization for TCP with an Active Proxy in Long-Delay Satellite Environments
Hui, Wang,Osada, Shigeyuki,Yokohira, Tokumi,Fukushima, Yukinobu,Chaolong, Deng,Okayama, Kiyohiko,Yamai, Nariyoshi 통신위성우주산업연구회 2006 Joint Conference on Satellite Communications Vol.2006 No.-
Although Transmission Control Protocol (TCP) is widely used in the Internet, its performance is poor in networks with long delays. To improve TCP performance in such networks as long-delay satellite environments, the use of a PEP (Performance Enhancing Proxy) has been proposed. The PEP operates on a router that connects a terrestrial link and a satellite link along a TCP connection. When a data packet arrives at the PEP, it forwards the packet to the destination host, transmits the corresponding ACK(premature ACK) to the source host on behalf of the destination host, and stores a copy of the packet in a local buffer (PEP buffer) in case retransmission of the packet is required. As a congestion control method on the PEP, a method that keeps the number of prematurely acknowledged packets in the PEP buffer below a threshold (watermark) value has been proposed. However, an optimization method of the watermark value has not been proposed. In this paper, we propose an adaptive watermark value optimization algorithm that maximizes the average throughput of each connection in response to dynamic establishment and release of connections, under a fairness condition that the average throughputs of connections are equal to each other. Numerical examples using the NS2 simulator for a simple network model show the effectiveness of the proposed algorithm.
Consensus Building using Deep Reinforcement Learning for Energy Management
Yuya Tarutani,Isato Oishi,Yukinobu Fukushima,Tokumi Yokohira 대한전자공학회 2022 IEIE Transactions on Smart Processing & Computing Vol.11 No.4
A variety of information is collected from IoT devices. As those devices become more familiar to users, network services must consider the influence of the user. We propose a method to maximize the value from power consumption and minimize the cost incurred to ensure user satisfaction. However, one problem is that user satisfaction cannot increase because it is considered a constraint on power consumption. In this paper, we propose a consensus building method to minimize power consumption and maximize user satisfaction. An exhaustive search incurs a large calculation overhead to determine device parameters. Thus, the proposed method uses reinforcement learning to solve this problem. From its evaluation, we clarify that the proposed method attains about 1.5 times the total reward compared with the conventional method. Moreover, we also clarify that 99.9% of the total reward can be achieved, compared to the exhaustive search.
Candidate Path Selection Method for TCP Performance Improvement in Fixed Robust Routing
Yukinobu Fukushima,Takashi Matsumura,Kazutaka Urushibara,Tokumi Yokohira 대한전자공학회 2016 IEIE Transactions on Smart Processing & Computing Vol.5 No.6
Fixed robust routing is attracting attention as routing that achieves high robustness against changes in traffic patterns without conducting traffic measurement and performing dynamic route changes. Fixed robust routing minimizes the worst-case maximum link load by distributing traffic of every source-destination (s-d) router pair onto multiple candidate paths (multipath routing). Multipath routing, however, can result in performance degradation of Transmission Control Protocol (TCP) because of frequent out-of-order packet arrivals. In this paper, we first investigate the influence of multipath routing on TCP performance under fixed robust routing with a simulation using ns-2. The simulation results clarify that TCP throughput greatly degrades with multipath routing. We next propose a candidate path selection method to improve TCP throughput while suppressing the worst-case maximum link load to less than the allowed level under fixed robust routing. The method selects a single candidate path for each of a predetermined ratio of s-d router pairs in order to avoid TCP performance degradation, and it selects multiple candidate paths for each of the other router pairs in order to suppress the worst-case maximum link load. Numerical examples show that, provided the worst-case maximum link load is less than 1.0, our proposed method achieves about six times the TCP throughput as the original fixed robust routing.
Dynamic splitting of light trails for increasing throughput in light trail networks
Yukinobu Fukushima,Kota Tanaka,Wenjie Chen,Tokumi Yokohira 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7
As a promising medium access control method in light trail networks, ART MAC based on token passing has been proposed. In order to increase throughput of ART MAC, we propose a dynamic light trail splitting method. Our method increases throughput of a light trail by splitting a light trail into two trails at the token holding node and enabling simultaneous data transmission on both trails. Simulation results show that our method achieves 23-32 % higher throughput than a light trail without splitting.
Yukinobu Fukushima,Yuta Sagawa,Yuya Tarutani,Tokumi Yokohira 대한전자공학회 2024 IEIE Transactions on Smart Processing & Computing Vol.13 No.2
In this paper, we tackle a virtual network embedding problem in network virtualization. For this problem, an algorithm (VNE-TD) based on temporal difference learning has been proposed. VNE-TD, however, does not consider the node and link resource constraints in selecting the candidate solutions. Therefore, when attempting to construct a virtual network, the embedding of a virtual network may fail due to insufficient resources. In this paper, we modify VNE-TD to select only those candidate solutions that satisfy the node and link resource constraints. We add a function to check the satisfiability of the node and link resource constraints to VNE-TD. The simulation results show that our modified methods reduce the blocking ratio of virtual network requests by up to 80% compared to VNE-TD.
Yuichi NISHIDA,WANG Hui,Hiroaki MATSUMOTO,Hiroyuki ISHIHARA,Tokumi YOKOHIRA,Yukinobu FUKUSHIMA 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7
In wired and wireless mixed networks, split-connection type proxies have been proposed to improve TCP (Transmission Control Protocol) throughput. A proxy is placed at the boundary between a wired network and a wireless one and splits a TCP connection which is established between a host in one of these networks and a host in the other networks into two virtual TCP connections. In this paper, under such environment that IEEE 802.11 WLANs are used as wireless networks, we first investigate throughputs of TCP connections with a proxy and show that although throughputs of downflows (flows from hosts in a wired network to a host in a WLAN) are improved, throughputs of upflows (the reverse of downflows) become smaller compared to those of TCP connections without the proxy. And we clarify that such throughput degradation is caused by congestion of a WLAN, and we propose a method to suppress such congestion.
A Prototype Virtual Network Embedding System using OpenStack
Yukinobu Fukushima,Kohei Sato,Itsuho Goda,Heung-Gyoon Ryu,Tokumi Yokohira 대한전자공학회 2017 IEIE Transactions on Smart Processing & Computing Vol.6 No.1
Network virtualization enables us to make efficient use of resources in a physical network by embedding multiple virtual networks in the physical network. In this paper, we develop a prototype of a virtual network embedding system. Our system consists of OpenStack, which is an open source cloud service platform, and shell scripts. Because OpenStack does not provide a quality of service control function, we realize bandwidth reservation for virtual links by making use of the ingress policing function of Open vSwitch, which is a virtual switch used in OpenStack. The shell scripts in our system automatically construct the required virtual network on the physical network using the OpenStack command-line interface, and they reserve bandwidth for virtual links using the Open vSwitch command. Experimental evaluation confirms that our system constructs the requested virtual network and appropriately allocates node and link resources to it.