Browsing by Author "Lin, Chia-Liang"

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Can: A context-aware NAT traversal scheme
(2013-07-01)
Tseng, Chien-Chao
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Lin, Chia-Liang
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Yen, Li-Hsing
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Liu, Jyun-Yan
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Ho, Cheng-Yuan
Network Address Translation (NAT) is a technique commonly used to share one public IPv4 address among several hosts located behind a NAT device. NAT devices typically block session requests originating from outside, causing NAT traversal problem that prevents the establishment of peer-to-peer (P2P) sessions. There have been many proposals for the NAT traversal problem. However, existing methods induce high connectivity check delay and resource demand when finding a communicating path, calling for a routine that determines the path best suited for a given pair of communicating peers. This study proposes CAN, a Context-Aware NAT traversal scheme which gathers and exchanges network-context information to find the most appropriate path for two communicating peers behind NAT devices. We have implemented CAN and conducted extensive experiments with off-the-shelf NAT devices to compare the performance of CAN with Interactivity Connectivity Establishment (ICE), the most acknowledged approach to creating a session across NATs. Experimental results show that CAN outperforms ICE in terms of direct communication ratio, connectivity check delay and message overload when checking connectivity. (c) 2013 Elsevier Ltd. All rights reserved.
CODE TCP: A competitive delay-based TCP
(2010-06-01)
Chan, Yi-Cheng
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Lin, Chia-Liang
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Chan, Chia-Tai
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Ho, Cheng-Yuan
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資訊工程學系
TCP Vegas is a well-known delay-based congestion control mechanism. Studies have indicated that TCP Vegas outperforms TCP Reno in many aspects. However, Reno currently remains the most widely deployed TCP variant in the Internet. This is mainly because of the incompatibility of Vegas with Reno. The performance of Vegas is generally mediocre in environments where it coexists with Reno. Hence, there exists no incentive for operating systems to adopt Vegas as the default transport layer protocol. In this study, we propose a new variant of Vegas called COmpetitive DElay-based TCP (CODE TCP). This variant is compatible with Reno and it can obtain a fair share of network resources. CODE is a sender-sided modification and hence it can be implemented solely at the end host. Simulations and experiments confirm that CODE has better fairness characteristics in network environments in which it coexists with Reno while retaining the good features of Vegas. (C) 2010 Elsevier B.V. All rights reserved.
Fast Handover Techniques for ESS-Subnet Topology Mismatch in IEEE 802.11
(2013)
Tseng, Chien-Chao
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Lin, Chia-Liang
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Chang, Yu-Jen
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Yen, Li-Hsing
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資訊工程學系
With the advances in wireless communication technology, mobile applications are gradually being introduced as part of our life. IEEE 802.11 is one of the most popular wireless communication technologies. Prior studies toward layer-2 and layer-3 handoffs assume that Extend Service Set (ESS) exactly matches a dedicated subnet. However, an inter-ESS with intra-subnet handoff and an intra-ESS with inter-subnet handoff may also be possible. Such mismatching ESS-subnet configurations result in performance degradation. This paper proposes FCS, a Further Check Scheme which detects the change of subnet after an intra-ESS handoff and eliminates unnecessary handoff latency after an inter-ESS handoff. The experimental results show that FCS outperforms the conventional implementation of NetworkManager under Linux in terms of handoff latency.
KPAT: A Kernel and Protocol Analysis Tool for Embedded Networking Devices
(2014-01-01)
Wang, Ming-Hung
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Yu, Chia-Ming
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Lin, Chia-Liang
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Tseng, Chien-Chao
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Yen, Li-Hsing
Sniffer tools capture protocol data. Kernel-profiling tools track function calls and events occurring in the kernel. These two types of tools help us observe external and internal behaviors of networking protocols, respectively. We need both types of data for a comprehensive view of protocol behavior. However, none of existing tools performs these two tasks in an integrated way. We developed Kernel and Protocol Analysis Tool (KPAT). KPAT injects software probes into Linux kernel to track interested function calls and event occurrences in the kernel. Probe injection is done systematically and does not require recompiling the kernel. A module in KPAT finds the association between the tracked functions and protocol data captured by an independent sniffer. The result as an integrated log allows users to identify two-way relationship between protocol data and the execution sequence of network functions in the kernel. We successfully used KPAT to identity accurate latency of each handover phase in IEEE 802.11 wireless networks. Experimental results show that KPAT causes light overhead to the patched kernel.
Quick Vegas: Improving performance of TCP Vegas for high bandwidth-delay product networks
(2008-04-01)
Chan, Yi-Cheng
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Lin, Chia-Liang
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Ho, Cheng-Yuan
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資訊工程學系
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Department of Computer Science
An important issue in designing a TCP congestion control algorithm is that it should allow the protocol to quickly adjust the end-to-end communication rate to the bandwidth on the bottleneck link. However, the TCP congestion control may function poorly in high bandwidth-delay product networks because of its slow response with large congestion windows. In this paper, we propose an enhanced version of TCP Vegas called Quick Vegas, in which we present an efficient congestion window control algorithm for a TCP source. Our algorithm improves the slow-start and congestion avoidance techniques of original Vegas. Simulation results show that Quick Vegas significantly improves the performance of connections as well as remaining fair when the bandwidth-delay product increases.
SIP-enabled Surveillance Patrol Robot
(2013-04-01)
Tseng, Chien-Chao
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Lin, Chia-Liang
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Shih, Bih-Yaw
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Chen, Chen-Yuan
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資訊工程學系
Robots are gradually being introduced as part of our life. With the advances in computational power and sophisticated sensors, home safety is being ensured with the help of robots. This study proposes SSPR, a SIP-enabled Surveillance Patrol Robot which tracks a moving object actively and informs the householder of security issues for the home environment. Such a robot is equipped with a camera and is aware of session initiation protocol (SIP). When SSPR senses a moving object, it starts tracking and initiates a SIP call to the mobile device of the householder. SIP will establish both audio and video streams between SSPR and the mobile device. Thus, the householder is able to get the whole picture of the home status through his/her mobile device. With the mobility support in SIP, SSPR can switch its wireless link adaptively to another access point (AP) and the audio and video streams will continue after handoff. As a result, SSPR can complement the security routine and make a home smarter and safer. (C) 2012 Elsevier Ltd. All rights reserved.
Topology-aware handoff scheme for surveillance patrol robot
(2013-08-01)
Tseng, Chien-Chao
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Lin, Chia-Liang
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Shih, Bih-Yaw
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Chen, Chia-Yen
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Chen, Chen-Yuan
With the advances in wireless communication technology and artificial intelligence, robots are gradually being introduced as a part of our life. Similarly to most mobile devices, mobile robots suffer from handoff latency. This paper proposes TASPR, a Topology-Aware Surveillance Patrol Robot, which can integrate the robotic status and topology information to assist handoff between access points (APs). TASPR uses Topology-Aware Hand-Off Scheme (TAHOS) to find the most promising AP from a list of candidate APs. When TASPR decides to initiate a handoff procedure, it analyzes moving direction, received signal strength and topology information to filter out unnecessary scannings. Thus, TAHOS has less handoff latency compared to conventional handoff procedure and neighbor graph algorithm (NGA).
WiFi assisted NAT traversal scheme for surveillance patrol robot
(2014-04-01)
Tseng, Chien-Chao
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Lin, Chia-Liang
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Shih, Bih-Yaw
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Chen, Chia-Yen
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Chen, Chen-Yuan
With the advances in wireless communication technology and artificial intelligence, robots are gradually being introduced as part of our life. Previous research proposed a SIP-enabled Surveillance Patrol Robot (SSPR), which tracks a moving object actively and informs the householder of such security alarm. However, the underlying signaling protocol for communication and data streams suffer from the network address translation (NAT) traversal problem as most peer-to-peer (P2P) applications. NAT is a commonly adopted technique to share one public IPv4 address among several hosts located behind a NAT device for alleviating the exhaustion of IPv4 address. NAT devices typically block session requests originating from outside, prevent the establishment of peer-to-peer (P2P) sessions and cause NAT traversal problem. This study proposes WANTS, a WiFi Assisted NAT Traversal Scheme for SSPR. When SSPR is activated, it retrieves the topology information from a server to choose the candidate access point (AP) for handoff. Then SSPR uses the collected network context information to assist its NAT traversal procedure after handoff. Experimental results confirm that WANTS reduces not only connectivity check delay but also protocol messages as compared to the Interactivity Connectivity Establishment (ICE), which is the most acknowledged approach to creating a session across NATs.