學術出版;;Publications

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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

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Design and implementation of a SIP-based mobile and vehicular wireless network with push mechanism
(2007-11-01)
Tseng, Yu-Chee
;
Chen, Jen-Jee
;
Cheng, Yu-Li
;
資訊工程學系
;
Department of Computer Science
As portable devices are gaining more popularity, maintaining Internet connectivity anytime and anywhere becomes critical, particularly for mobile and vehicular networks. Network mobility (NEMO) and Internet Protocol mobility are gaining more and more importance. In this paper, we develop a Session Initiation Protocol (SIP)-based mobile network architecture to support NEMO for vehicular applications. We propose to form a mobile ad hoc network (MANET) by the mobile hosts (MHs) inside a vehicle or a cluster of vehicles. The MANET is connected to the outside world via a SIP-based Mobile Network Gateway (SIP-MNG), which is equipped with one or multiple external wireless interfaces and some internal IEEE 802.11 interfaces. The external interfaces of the SIP-MNG support Internet connectivity by aggregating user traffic to and from the Internet. In addition, exploiting the session information carried by SIP signaling, the SIP-MNG supports resource management and call admission control for the MHs. However, wireless access incurs charges, power consumption, and overhead of mobility management. So, it is desirable to allow the SIP-MNG to disconnect its external interfaces when necessary. To guarantee that users inside the mobile network will not lose any incoming request, we propose a push mechanism through short message service to wake up these wireless interfaces in an on-demand manner. We show the detailed signaling to support such a mechanism. The proposed system is fully compatible with existing SIP standards. Our real prototyping experience and some experimental results are also reported.
An Energy Efficient Sleep Scheduling Considering QoS Diversity for IEEE 802.16e Wireless Networks
(2010)
Chen, Jen-Jee
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Liang, Jia-Ming
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Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
Power management is one of the most important issues in IEEE 802.16e wireless networks. In the standard, it defines three types of power saving classes (PSCs) for flows with different QoS characteristics. It allows a mobile device to turn off its wireless radio when all its PSCs are in sleep states. In this paper, we consider the scheduling of power saving classes of type II in an IEEE 802.16e network with a BS and multiple MSSs (mobile subscriber stations). Previous work proposes to enforce all MSSs to have the same sleep cycle, thus leading to higher energy cost for those MSSs with less strict delay bounds. We observe that if the sleep cycles of MSSs can be assigned according to their delay bounds, MSSs can significantly reduce their duty cycles. We propose an efficient tank-filling algorithm, which is standard-compliant and can allocate resources to MSSs according to their QoS characteristics with the least number of active frames. Simulation results verify that our algorithm incurs less power consumption and leads to higher bandwidth utilization than the previous schemes.
Discriminant Minimization Search for Large-Scale RF-Based Localization Systems
(2011-02-01)
Kuo, Sheng-Po
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Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
In large-scale fingerprinting localization systems, fine-grained location estimation and quick location determination are conflicting concerns. To achieve finer grained localization, we have to collect signal patterns at a larger number of training locations. However, this will incur higher computation cost during the pattern-matching process. In this paper, we propose a novel discriminant minimization search (DMS)-based localization methodology. Continuous and differentiable discriminant functions are designed to extract the spatial correlation of signal patterns at training locations. The advantages of the DMS-based methodology are threefold. First, with through slope of discriminant functions, the exhaustive pattern-matching process can be replaced by an optimization search process, which could be done by a few quick jumps. Second, the continuity of the discriminant functions helps predict signal patterns at untrained locations so as to achieve finer grained localization. Third, the large amount of training data can be compressed into some functions that can be represented by a few parameters. Therefore, the storage space required for localization can be significantly reduced. To realize this methodology, two algorithms, namely, Newton-PL and Newton-INT, are designed based on the concept of gradient descent search. Simulation and experiment studies show that our algorithms do provide finer grained localization and incur less computation cost.
Traffic-Attracted Mobile Relay Deployment in a Wireless Ad Hoc Network
(2012)
Wu, Fang-Jing
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Hsu, Hsiu-Chi
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Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
This paper considers an ad hoc network, where a set of energy-rich mobile nodes, termed mobile relays, are used to facilitate relaying packets so as to mitigate the energy consumption of static nodes. Existing work has focused on link-level relaying behaviors. In this work, we show how to achieve route-level relaying by overhearing route control and data packets. This allows mobile relays to redirect the traffic of static nodes and thus reduce their energy consumption. As the relocation of mobile relays needs to dynamically adjust the current traffic condition, a dynamic relocation scheme of mobile relays needs to be designed. In this paper, we refer to the mobile relay deployment (MRD) problem and design a distributed protocol for mobile relays. In our protocol, mobile relays do not necessarily participate in the routing discovery process, so static nodes can quickly switch back to their original routing paths without reconstruction efforts once mobile relays leave their communication ranges. Simulations by QualNet are presented to evaluate the performance of our protocol as compared to link-level relaying.
A request control scheme for data recovery in DVB-IPDC systems with spatial and temporal packet loss
(2013-07-01)
Yang, Wen-Hsin
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Wang, You-Chiun
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Tseng, Yu-Chee
;
Lin, Bao-Shuh Paul
;
資訊工程學系
Recently, digital video broadcasting-handheld (DVB-H) and IP datacast over DVB-H (DVB-IPDC) have been developed to support broadcasting services. DVB-H is designed to support digital video broadcast for handheld devices, whereas DVB-IPDC can integrate with an IP-relay network to complement the data loss problem in DVB-H. Assuming that WiMAX networks are adopted to support DVB-IPDC, this paper points out two critical problems: group packet loss (GPL) and broadcast data handover (BDH). GPL occurs when there is a burst of retransmission requests for the same pieces of data with high spatial or temporal correlation. BDH happens when some devices that made the above requests handover to new serving cells. To solve these problems, we propose lazy wait and group acknowledgement schemes to alleviate duplicate requests by exploiting their spatial and temporal correlations. This not only reduces the requests submitted by neighboring devices in both space and time domains but also avoids handovering devices from sending duplicate requests in new cells. Through mathematical analysis, we show how to adaptively adjust the timers of lazy wait and group acknowledgement based on channel quality. Simulation results prove that our schemes can efficiently reduce retransmission requests and retransmission packets, thus alleviating congestion in the IP-relay network. Copyright (c) 2011 John Wiley & Sons, Ltd.
k-Angle Object Coverage Problem in a Wireless Sensor Network
(2012-12-01)
Tseng, Yu-Chee
;
Chen, Po-Yu
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Chen, Wen-Tsuen
;
資訊工程學系
;
Department of Computer Science
One of the fundamental issues in sensor networks is the coverage problem, which reflects how well a field is monitored or tracked by sensors. Various versions of this problem have been studied, such as object, area, barrier, and hole coverage problems. In this paper, we define a new k-angle object coverage problem in a wireless sensor network. Each sensor can only cover a limited angle and range, but can freely rotate to any direction to cover a particular angle. Given a set of sensors and a set of objects at known locations, the goal is to use the least number of sensors to k-angle-cover the largest number of objects such that each object is monitored by at least k sensors satisfying some angle constraint. We propose centralized and distributed polynomial-time algorithms to solve this problem. Simulation results show that our algorithms can be effective in maximizing coverage of objects. A prototype system is developed to demonstrate the usefulness of angle coverage.
Managing Power Saving Classes in IEEE 802.16 Wireless MANs: A Fold-and-Demultiplex Method
(2011-09-01)
Tseng, Yu-Chee
;
Chen, Jen-Jee
;
Yang, Yen-Chih
;
資訊工程學系
;
Department of Computer Science
In IEEE 802.16, power management at the Mobile Subscriber Station (MSS) side is always an important issue. The standard defines three types of power saving classes (PSCs). A PSC can bind one or multiple traffic flows. However, given multiple flows in an MSS, the standard does not define how to form PSCs, how to organize the cooperation of multiple PSCs to obtain better energy efficiency, and how to guarantee QoS of these flows. Given a set of flows and their QoS parameters, the objective of this paper is to define multiple PSCs and their listen-and-sleep-related parameters and packet-scheduling policy such that the unavailability intervals of the MSS can be maximized and the QoS of each flow can be guaranteed. To achieve this, we propose a novel fold-and-demultiplex method for an IEEE 802.16 network with PSCs of types I and II together with an earliest-next-bandwidth-first packet scheduler. Given a set of traffic flows in an MSS, the fold-and-demultiplex method first gives each flow a tentative PSC satisfying its bandwidth requirement. Then we fold them together into one long series so as to calculate the total bandwidth requirement. Finally, we demultiplex the series into multiple PSCs, each supporting one or multiple flows. It ends up with high energy efficiency of MSSs while meets flows' bandwidth requirements. Furthermore, our packet scheduler ensures that real-time flows' delay constraints can be met. To the best of our knowledge, this is the first result offering bounded packet delays under MSS's sleep-and-listen behaviors.
Efficient Packet Recovery Using Prioritized Network Coding in DVB-IPDC Systems
(2012-03-01)
Yang, Wen-Hsin
;
Wang, You-Chiun
;
Tseng, Yu-Chee
;
資訊工程學系
;
Department of Computer Science
The DVB-H standard is proposed to disseminate videos to mobile devices. However, packet loss is inevitable due to the broadcasting nature. To deal with this issue, DVB-IPDC suggests incorporating another wireless network for data retransmission. This paper takes a WiMAX network as an example in DVB-IPDC and models its channel as repetitive frames. During each frame, mobile devices sends their recovery requests of lost packets to a WiMAX base station and the base station adopts network coding to broadcast these packets. This paper then formulates a prioritized network coding (PNC) problem that asks how the base station uses at most tau coded packets in each frame such that it can recover the maximum aggregate number of lost packets while minimize the aggregate number of packets discarded due to out of deadlines. We develop a solution using XOR coding, which constructs a weighted bipartite graph to calculate the benefit to broadcast each coded packet. Then, the solution tries to maximize the overall benefit by finding a maximum-weighted tau dominating set. The contribution of this paper is to propose a new PNC problem in DVB-IPDC systems and develop an efficient PNC solution.
Spatial and Temporal Packet Recovery Schemes for DVB-H Systems through IP-Relay Wireless Networks
(2009)
Yang, Wen-Hsin
;
Wang, You-Chiun
;
Tseng, Yu-Chee
;
Lin, Bao-Shuh P.
;
資訊工程學系
The DVB-H standard has been defined to provide digital video broadcast to mobile handheld devices. However, without a request channel, a handheld device may encounter data loss and thus it requires an additional recovery architecture to relieve this problem. In this paper, we follow the DVB-IPDC standard and propose combining a DVB-H system with an IP-relay wireless network. A handheld device losing DVB-H data can thus request the relay network for retransmission. Under this architecture, we identify two critical issues, group packet loss (GPL) and broadcast data handover (BDH). The GPL problem occurs when there are bursty requests for retransmissions of the same data with high spatial and temporal locality, causing network congestion. The BDH problem occurs when these requesting devices move out of their current serving cells. In this paper, we propose a bulk request recovery (BRR) scheme to solve these problems by exploiting spatial and temporal locality of recovery requests. Our scheme can efficiently reduce duplicate requests and schedule retransmissions of lost packets, so both GPL and BDH problems are relieved. Simulations results are also presented to verify the effectiveness of our result.
Distributed protocols for ensuring both coverage and connectivity of a wireless sensor network
(2007-03-01)
Huang, Chi-Fu
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Tseng, Yu-Chee
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Wu, Hsiao-Lu
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資訊工程學系
;
Department of Computer Science
Wireless sensor networks have attracted a lot of attention recently. Such environments may consist of many inexpensive nodes, each capable of collecting, storing, and processing environmental information, and communicating with neighboring nodes through wireless links. For a sensor network to operate successfully, sensors must maintain both sensing coverage and network connectivity. This issue has been studied in Wang et al. [2003] and Zhang and Hou [2004a], both of which reach a similar conclusion that coverage can imply connectivity as long as sensors' communication ranges are no less than twice their sensing ranges. In this article, without relying on this strong assumption, we investigate the issue from a different angle and develop several necessary and sufficient conditions for ensuring coverage and connectivity of a sensor network. Hence, the results significantly generalize the results in Wang et al. [2003] and Zhang and Hou [2004a]. This work is also a significant extension of our earlier work [Huang and Tseng 2003; Huang et al. 2004], which addresses how to determine the level of coverage of a given sensor network but does not consider the network connectivity issue. Our work is the first work allowing an arbitrary relationship between sensing ranges and communication distances of sensor nodes. We develop decentralized solutions for determining, or even adjusting, the levels of coverage and connectivity of a given network. Adjusting levels of coverage and connectivity is necessary when sensors are overly deployed, and we approach this problem by putting sensors to sleep mode and tuning their transmission powers. This results in prolonged network lifetime.

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