Browsing by Author "Liu, Kuang-Che"

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Evaluating and Improving the TCP/UDP Performances of IEEE 802.11(p)/1609 Networks
(2008)
Wang, Shie-Yuan
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Chao, Hsi-Lu
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Liu, Kuang-Che
;
He, Ting-Wei
;
Lin, Chih-Che
The IEEE 802.11(p)/1609 standard is an emerging technology for vehicular communication networks. It amends the IEEE 802.11-2007 standard and defines a new WAVE operational mode for vehicular environments. The WAVE mode utilizes a combined FDMA/TDMA scheme to manage network bandwidth. In this mode, a node must periodically switch its frequency channel between two different channels over time. Such a design may result in bandwidth wastage due to the residual time caused by channel switching. In this paper, we propose two easy-to-implement schemes to mitigate this problem and compare their TCP/UDP performances with those of the original scheme. Our simulation results provide many insights into the operations of these schemes on IEEE 802.11(p)/1609 networks and show that the proposed schemes always outperform the original scheme.
On Multi-hop Forwarding over WBSS-based IEEE 802.11(p)/1609 Networks
(2009)
Wang, Shie-Yuan
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Lin, Chih-Che
;
Liu, Kuang-Che
;
Hong, Wei-Jyun
;
資訊工程學系
The IEEE 802.11(p)/1609 network is a promising candidate for future vehicular communication networks. Due to the deployment cost consideration, roadside units (RSUs) in such networks are usually installed only at hot spots and intersections, causing the service coverage of RSUs to be discontinuous. To overcome this problem, multihop data forwarding among vehicles can be used to extend the service coverage of RSUs. In this paper, we propose a receiver-centric WBSS (Wave Basic Service Set)-creating scheme to support multihop data forwarding in WBSS-based IEEE 802.11(p)/1609 networks and evaluate its performances using simulations. Our simulation results show that this scheme outperforms a typical sender-centric WBSS-creating scheme on end-to-end flow goodputs under different traffic loads.
On the performances of forwarding multihop unicast traffic in WBSS-based 802.11(p)/1609 networks
(2011-08-04)
Wang, Shie-Yuan
;
Lin, Chih-Che
;
Hong, Wei-Jyun
;
Liu, Kuang-Che
;
資訊工程學系
The IEEE 802.11(p)/1609 network is a promising candidate for future vehicular communication networks. In this new network, the operation of a new Wave Basic Service set (WBSS) is defined for vehicular environments. Due to the deployment cost consideration, roadside units (RSUs) in such networks are usually installed only at hot spots and intersections, causing the service coverage of RSUs to be discontinuous. To overcome this problem, multihop data forwarding among vehicles can be used to extend the service coverage of RSUs. The multihop geocasting problem has been studied and addressed in our previous work [1], where we proposed a receiver-centric WBSS geocasting scheme to increase multihop geocasting performances in WBSS-based networks. However, multihop unicasting, a more common facility in many network applications and services, was not dealt with in [1]. In this paper, we propose a new Receiver-centric WBSS Forwarding Scheme for Unicast traffic (called RWFS-U), which uses a prioritized receiver-centric WBSS creation design to efficiently support unicast data forwarding in WBSS-based networks. Extensive performance evaluations using both analyses and simulations are presented to understand the effects of the designs of WBSS forwarding schemes on the goodputs of end-to-end flows. Our results show that RWFS-U can significantly outperform the traditional sender-centric schemes on multihop unicasting in WBSS-based networks. (C) 2011 Elsevier B.V. All rights reserved.