Browsing by Author "Cheng, Chien-Ming"

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A Real-Time Road Traffic Information System based on a Peer-to-Peer Approach
(2008)
Yang, Ya-Chu
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Cheng, Chien-Ming
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Lin, Pei-Yun
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Tsao, Shiao-Li
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資訊工程學系
Conventional traffic information systems based on client-server approaches allow car drivers to navigate real-time road traffics, but the cost for maintaining the centralized traffic centers is high. On the other hand, decentralized traffic information systems that traffic conditions are exchanged between vehicles via inter-vehicle communication (IVC) significantly reduce the construction cost and efforts. Unfortunately, while the penetration of vehicles with such the system is insufficient, the systems suffer from problems to disseminate traffic conditions in disconnected vehicular ad-hoc networks. Therefore, we propose a novel road traffic information system which utilizes both IVC and infrastructure-based peer-to-peer communications. The system is organized as a two-tier hierarchical architecture where all vehicles broadcast traffic conditions over lower-tier vehicular ad-hoc networks. Moreover, parts Of vehicles with infrastructure communication facilities further form a high-tier peer-to-peer overlay and exchange traffic information and look-ups to redeem the dis-connectivity of the vehicular ad-hoc networks. Simulation results demonstrate that the proposed system performs well in terms of both delay for traffic information lookup and message exchanging overheads.
A Two-Tier VANET/P2P System for Information Retrieval in Vehicular Environments
(2013)
Cheng, Chien-Ming
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資訊工程學系
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Department of Computer Science
With advances in information and communication technologies, vehicles on roads can cooperatively share and retrieve information in a distributed manner to support Intelligent Transportation Systems (ITS) services such as traffic management and infotainment services. A system is needed to retrieve information and data from moving vehicles and roadside facilities in an efficient manner. However, existing distributed vehicular systems rely on either vehicular ad hoc networks (VANETs) or application-layer peer-to-peer (P2P) protocols over an infrastructure-based wireless network suffering from low success rate or long latency in information retrieval. In this work, we propose a two-tier VANET/P2P system that integrates low-tier VANETs and a high-tier infrastructure-based P2P overlay. The proposed two-tier system aims to achieve high success rate, reduce latency, and minimize overhead for information retrieval in vehicular environments.
Adaptive Lookup Protocol for Two-Tier VANET/P2P Information Retrieval Services
(2015-03-01)
Cheng, Chien-Ming
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Tsao, Shiao-Li
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資訊工程學系
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Department of Computer Science
Intelligent transportation system (ITS) services have attracted significant attention in recent years. To support ITS services, architecture is required to retrieve information and data from moving vehicles and roadside facilities in an efficient manner. A two-tier system that integrates low-tier vehicular ad hoc networks (VANETs) and a high-tier infrastructure-based peer-to-peer (P2P) overlay, which can achieve a high lookup success rate and low lookup latency for information retrieval, has been developed. However, conventional information lookups in the two-tier VANET/P2P system may introduce extra lookup messages and latencies because the lookup queries are simultaneously performed over the VANET/P2P networks. This paper proposes an adaptive lookup protocol for the two-tier VANET/P2P system to improve the efficiency of information retrieval. The proposed protocol uses a Bloom filter, which is a space-efficient data structure, to collect reachability information of road segments; therefore, adaptive routing of queries between low-and high-tier networks according to reachability probability can be employed. Simulations based on the SUMO traffic simulator and QualNet network simulator demonstrate that compared with the conventional two-tier lookup mechanism, the adaptive lookup protocol can reduce the lookup latency by 12%, reduce the P2P lookup overhead by 20%-33%, and achieve a high success rate in information lookups.
An Adaptive Routing Algorithm for Two-Tier Traffic Information System
(2012)
Lu, Kowen
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Cheng, Chien-Ming
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Tsao, Shiao-Li
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資訊工程學系
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Department of Computer Science
Intelligent Transportation Systems (ITSs) have attracted much attention recently. One of the most important services for ITSs is to provide real-time traffic information service. To reduce the deployment cost and achieve high service availability, decentralized approaches such as vehicular ad hoc network (VANET)-based or infrastructure-based peer-to-peer (P2P) traffic information systems were proposed. To further improve the success rate and lookup latency of traffic information lookups, a new two-tier traffic information system which integrates low-tier VANET and high-tier P2P overlay has been developed. However, conventional two-tier traffic information system may introduce extra routing overheads since the information lookups are broadcasted over two tier networks and introduce redundant lookup messages. This paper proposes an adaptive routing mechanism in the two-tier traffic information system to improve the efficiency of traffic information lookup. Simulation results demonstrate that the proposed adaptive scheme reduces the lookup latency and overhead while achieving the same lookup success rate compared with the conventional approach.
Design and Evaluation of a Two-Tier Peer-to-Peer Traffic Information System
(2011-05-01)
Tsao, Shiao-Li
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Cheng, Chien-Ming
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資訊工程學系
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Department of Computer Science
Decentralized traffic information systems realize real-time traffic information services without the need for a server infrastructure. However, existing systems rely on either the vehicular ad hoc network or application-layer peer-to-peer protocols over a broadband wireless network suffering from low lookup success rate, high lookup latency, and maintenance overhead of the P2P network. This article proposes a two-tier VANET/P2P architecture that exploits both VANET and P2P technology. In the low tier, vehicles form a VANET via intervehicle communication to exchange traffic information. On top of the VANET, a portion of the vehicles further establish a P2P overlay through a broadband wireless infrastructure to mitigate the disconnectivity problems of the VANET. Simulation results demonstrate that the two-tier architecture can significantly improve the lookup success rate compared to the single-tier VANET systems while reducing lookup latency and maintenance overhead compared to the single-tier P2P systems.
SEEDS: A Solar-Based Energy-Efficient Distributed Server Farm
(2015-01-01)
Cheng, Chien-Ming
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Tsao, Shiao-Li
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Lin, Pei-Yun
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資訊工程學系
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Department of Computer Science
Distributed renewable energy has emerged as a promising resource because of its environmental friendliness and economic considerations. However, most renewable energy sources are unreliable and may require considerable effort to be efficiently utilized in a computing center for providing services. In this paper, we exploit distributed renewable energy (e.g., solar energy) and peer-to-peer (P2P) technologies to aggregate distributed computing resources to provide an infrastructure called solar-based energy-efficient distributed server (SEEDS) farm for distributed computing and distributed storage. Energy-efficient devices (e.g., embedded devices) powered by solar energy form a P2P computing system to provide their computing resources to end-users. Specifically, this paper uses a Web-based service as a case study. A group of solar-powered embedded devices acts as a front-end cooperative caching system for Web servers. Web objects may be accessed through the distributed caching system without going through servers, and thus we can reduce brown energy consumption of the servers. This paper also develops an analytical model to evaluate the total energy consumption of Web-based services with and without SEEDS. Theoretical and simulation results show that the SEEDS system can support services and achieve significant improvements in energy efficiency by aggregating distributed energy resources.
Unstructured peer-to-peer session initiation protocol for mobile environment
(2007)
Cheng, Chien-Ming
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Tsao, Shiao-Li
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Chou, Jin-Chang
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資訊工程學系
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Department of Computer Science
Session Initiation Protocol (SIP) has been widely used as the call setup protocol for multimedia communications such as Voice over IP (VoIP). The client-server architecture, however, exposes SIP servers to the risks of performance bottleneck and the single point of failure. Peer-to-Peer (P2P) SIP which is implemented by using the Distributed Hash Table (DHT)-based Chord is consequently proposed with the advantages of scalability and reliability by replacing centralized servers with the self-organized P2P network. Unfortunately, previous studies on P2P SIP have not yet considered the mobility issue which is an essential property of mobile Internet. While users roam in wireless networks, to ensure a stable DHT-based Chord introduces serious problems. In this paper, we propose a new unstructured P2P SIP system for mobile Internet telephony. An unstructured P2P network is less influenced by the chum property than a structured P2P network, and it is suitable for mobile environment. Moreover, the proposed unstructured P2P SIP network is constructed according to the relationships between SIP users and their friends. Therefore, SIP users can find their friends in the proposed P2P SIP network very easily. Also, the social network exhibits the small-world property, and an SIP user can locate non-friends in the proposed network within a small number of hops. Simulations results demonstrate that the proposed method introduces less maintenance overhead and achieves better performance than the conventional Chord-based approach.