Browsing by Author "Wang, Tsan-Pin"

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A Fair Scheme for Multi-channel Selection in Vehicular Wireless Networks
(2013-12-01)
Wang, Kuo-Lung
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Wang, Tsan-Pin
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
In recent years, the IEEE 802.11p/1609 wireless access in vehicular environments standards adopt the dedicated short-range communications multi-channel architecture for vehicular wireless networks. To utilize the multi-channel architecture, each vehicle equipped with two sets of transceivers can operate concurrently on three different channels. For example, in cluster-based multi-channel schemes, a cluster head vehicle coordinates and assigns an appropriate channel to its cluster members. However, these schemes are unsuitable for a single channel device performing on only one RF channel at a time which would waste channel resource and increase time to allocate a channel. Another approach, called LEACH-based scheme, selects channels randomly and ensures that each channel is selected once within a round in each vehicle. However, this leads to a situation that different vehicles might select the same channel in short-term duration. In this paper, we propose a multi-channel selection scheme, called minimum duration counter (MDC) scheme, which could apply to a single channel device, while utilizing the multi-channel architecture of an 802.11p/1609 network. In addition, we compare the MDC scheme with pure random (PR) and LEACH-based schemes in terms of fairness index (FI) and utilization to emphasize the fairness and to balance the traffic of multi-channel usage. Furthermore, we analyze the counter overflow probability distribution and propose solutions to the MDC scheme. Numerical results show that our scheme outperforms the PR and LEACH-based schemes in terms of multi-channel usage, traffic balancing, and fairness.
A network address translation approach to the inbound session problem in private networks
(2007-02-01)
Hsieh, Ming-Deng
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Chang, Hung-Chun
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Tseng, Chien-Chao
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Wang, Tsan-Pin
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資訊工程學系
This paper proposes a Dynamic-Configurable NAT (DCNAT) approach to the inbound session problem for private networks behind NAT routers. DCNAT is a port-based NAT scheme that adopts a registration procedure for a host to register a session with a DCNAT router before originating a communication session to a host behind the DCNAT router. With the registration procedure, the DCNAT router can create NAT binding entries dynamically for address: port translation before the inbound session starts. Furthermore the dynamic creation of NAT binding entries makes DCNAT very flexible in supporting inbound accesses to a large number of services opened dynamically by the private nodes behind an NAT router. Although DCNAT requires minor modification to the originating host and the NAT router, it is highly suitable for proxy-based applications, such as web browsing, or instant message delivery.
Adaptive RSU re-routing under delay constraint in multi-hop vehicular networks
(2016)
Wang, Kuo-Lung
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Wang, Tsan-Pin
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
Vehicular wireless networks (VWNs) offer wireless multi-hop communications between vehicles and roadside units (RSUs). A multi-hop wireless network with carry-and-forward routing may suffer from longer delay in packet delivery. However, the applications may demand stringent delay requirement in multi-hop VWNs. Therefore, this paper proposes an adaptive RSU re-routing strategy to alter the current associated RSU to the best RSU under delay or throughput constrains for applications in multi-hop VWNs. Performance results show that the proposed strategy is able to adaptively select a suitable packet size for the trade-off between delay and throughput to satisfy the diverse requirements of applications in multi-hop VWNs.
Reducing Multi-hop Wireless Delay for High-Priority Applications in Vehicular Wireless Networks
(2015-03-01)
Wang, Kuo-Lung
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Wang, Tsan-Pin
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
Vehicular wireless networks (VWNs) offer both high-priority safety and low-priority non-safety applications. In VWNs, the high-priority applications are urgent. Transmitting urgent information demands low delay and high bandwidth. When the traffic is heavy, how to reduce the multi-hop wireless delay will be critical for urgent information. In this paper, we propose a blocking strategy to preempt the transmission of low-priority vehicles and to decrease the number of contending vehicles. Thus, the multi-hop wireless delay of high-priority vehicles will be greatly reduced even if the traffic is heavy. Moreover, we also propose a mathematical model to evaluate the performance of the proposed strategy and compare the existing strategy. Performance results show that the proposed strategy can reduce the multi-hop wireless delay significantly.
Reducing wireless multi-hop delay via RSU re-routing in vehicular wireless networks
(2015-10-01)
Wang, Kuo-Lung
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Wang, Tsan-Pin
;
Tseng, Chien-Chao
;
資訊工程學系
;
Department of Computer Science
Vehicular wireless networks offer wireless multi-hop communications between vehicles and roadside units (RSUs). To reduce deployment cost, the distance between two RSUs could be long; that is,the communications between an RSU and a vehicle may be carried out through multi-hops among intermediate vehicles. When a vehicle is driven from one RSU to another, the wireless multi-hop delay becomes more serious as the number of multi-hop relays increases. The wireless multi-hop delay is critical for some emergency service. For instance, in a traffic accident, when a patient was sent to the hospital by ambulance, the life information of the patient must be transmitted to the hospital on time through the multi-hop wireless network. If the ambulance is moved from one RSU to another, the wireless multi-hop delay becomes more and more serious as the ambulance is closing to another RSU. In this paper, we propose an RSU re-routing strategy that dynamically alters multi-hop communications until the best RSU with the shortest path using location information is found. Moreover, we compare the proposed strategy with the existing strategy in terms of broadcasting costs, re-routing delay, and wireless multi-hop delay of data transmission. Performance results show that the proposed strategy can reduce the wireless multi-hop delay significantly. Copyright (c) 2014 John Wiley & Sons, Ltd.