學術出版;;Publications

Permanent URI for this communityhdl:11536/1

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.

Browse

🏛️國立陽明交通大學機構典藏

Search Results

Now showing 1 - 10 of 11

Introduction to blueweb: A decentralized scatternet formation algorithm for Bluetooth ad hoc networks
(2008-09-01)
Yu, Chih-Min
;
Huang, Chia-Chi
;
電信工程研究所
;
Institute of Communications Engineering
In this letter, a decentralized scatternet formation algorithm called Bluelayer is proposed. First. Bluelayer uses a designated root to construct a tree-shaped subnet and propagates an integer variable k 1 called counter limit as well as a constant k in its downstream direction to determine new roots. Then each new root asks its upstream master to start a return connection procedure to convert the tree-shaped subnet into a web-shaped subnet for its immediate upstream root, At the same time, each new root repeats the same procedure as the root to build its own subnet until the whole scatternet is formed, Simulation results show that Bluelayer achieves good network scalability and generates an efficient scatternet configuration for various sizes of Bluetooth ad hoc network.
A new BlueRing scatternet topology for Bluetooth with its formation, routing, and maintenance protocols
(2003-06-01)
Lin, TY
;
Tseng, YC
;
Chang, KM
;
資訊工程學系
;
Department of Computer Science
The basic networking unit in Bluetooth is piconet, and a larger-area Bluetooth network can be formed by multiple piconets, called scatternet. However, the structure of scatternets is not defined in the Bluetooth specification and remains as an open issue at the designers' choice. It is desirable to have simple yet efficient scatternet topologies with good supports of routing protocols, considering that Bluetooths are to be used for personal area networks with design goals of simplicity and compactness. In the literature, although many routing protocols have been proposed for mobile ad hoc networks, directly applying them poses a problem due to Bluetooth's special baseband and MAC-layer features. In this work, we propose an attractive scatternet topology called BlueRing, which connects piconets as a ring interleaved by bridges between piconets, and address its formation, routing, and topology-maintenance protocols. The BlueRing architecture enjoys the following fine features. First, routing on BlueRing is stateless in the sense that no routing information needs to be kept by any host once the ring is formed. This would be favorable for environments such as Smart Homes where computing capability is limited. Second, the architecture is scalable to median-size scatternets easily (e.g. around 50 similar to 70 Bluetooth units). In comparison, most star- or treelike scatternet topologies can easily form a communication bottleneck at the root of the tree as the network enlarges. Third, maintaining a BlueRing is an easy job even as some Bluetooth units join or leave the network. To tolerate single-point failure, we propose a protocol-level remedy mechanism. To tolerate multipoint failure, we propose a recovery mechanism to reconnect the BlueRing. Graceful failure is tolerable as long as no two or more critical points fail at the same time. As far as we know, the fault-tolerant issue has not been properly addressed by existing scatternet protocols yet. In addition, we also evaluate the ideal network throughput at different BlueRing sizes and configurations by mathematical analysis. Simulation results are presented, which demonstrate that BlueRing outperforms other scatternet structures with higher network throughput and moderate packet delay. Copyright (C) 2003 John Wiley Sons, Ltd.
Optimizing the packet forwarding throughput of multi-hop wireless chain networks
(2003-09-01)
Wang, SY
;
資訊工程學系
;
Department of Computer Science
In the literature, it has been shown that due to signal interferences between neighboring stations, the maximum packet forwarding throughput of a N-hop wireless chain network decreases as N increases and is only 1/N of the wireless bandwidth. This 1/N trend continues until the throughput finally stabilizes at only 1/5 or even less when N becomes large. To solve this problem, this paper proposes an approach that optimizes the forwarding throughput of a wireless chain network. In this approach, which we call the 'two-frequency scheme', the wireless interface cards of some nodes in the wireless chain network will swap their operating frequency channels between two different channels to avoid interferences. Using this approach, even when N is large, the forwarding throughput can be cost-effectively improved to 1/2, which is the optimal forwarding throughput that can be achieved by a half-duplex wireless interface. (C) 2003 Elsevier Science B.V. All rights reserved.
Energy-efficient topology control for wireless ad hoc sensor networks
(2004-01-01)
Tseng, YC
;
Chang, YN
;
Tzeng, BH
;
資訊工程學系
;
Department of Computer Science
Energy-saving is a critical issue in mobile computing. Given a set of hosts which forms a wireless ad hoc network and an initial energy for each host, this paper considers the topology control problem by tuning the transmission powers of hosts to control the structure of the network. The target topology includes 1-edge-, 1-vertex-, 2-edge-, and 2-vertex-connected graphs. The goal is to maximize the lifetime of the network, i.e., the amount of time when all hosts remain alive. Two variations of the problem, where hosts' powers can be fixed or variable during the lifetime of the network, are discussed. We show that optimal lifetimes can be obtained by using a simple minimum spanning tree construction under the fixed power assumption.
A two-tier heterogeneous mobile ad hoc network architecture and its load-balance routing problem
(2004-08-01)
Huang, CF
;
Lee, HW
;
Tseng, YC
;
資訊工程學系
;
Department of Computer Science
The mobile ad hoc network (MANET) has attracted a lot of interest recently. However, most of the existing works have assumed a stand-alone MANET. In this paper, we propose a two-tier, heterogeneous MANET architecture which can support Internet access. The low tier of the network consists of a set of mobile hosts each equipped with a IEEE 802.11 wireless LAN card. In order to connect to the Internet and handle the network partitioning problem, we propose that the high tier is comprised of a subset of the mobile hosts, called gateways, which can access to cellular/infrastructure networks. The high tier is heterogeneous in the sense that the network interfaces in the gateway hosts could be IEEE 802.11 cards, PHS handsets, or GPRS handsets characterized by different bandwidths and latencies. Observing that the gateways could become the bottlenecks of the two-tier network, we propose a set of solutions, namely boundary-moving, host-partitioning, and probabilistic solutions, to solve the load-balance routing issue. Implementation issues/concerns of these schemes are discussed. Simulation results are presented to compare these load-balance routing schemes.
NICE - A decentralized medium access control using neighborhood information classification and estimation for multimedia applications in ad hoc 802.11 wireless LANs
(2003)
Chen, A
;
Wang, LC
;
Su, Y
;
Zheng, YX
;
Yang, B
The desired properties of a medium access control (MAC) protocol in mobile ad hoc network (MANET) include (1) meet quality of service (QoS) requirements for real-time nodes, (2) be decentralized, (3) achieve fairness from viewpoint of throughput or energy consumption, and (4) be immune to the hidden node problem. Though there have been numerous proposed MAC protocols for the IEEE 802.11 WLAN, few of them possesses all of the above four properties. In this paper, we propose a new MAC scheme satisfying all of above four properties. Our protocol can support real-time traffic and satisfy QoS requirements, and can achieve fairness among non-real-time nodes. Also, without using any centralized control, it can be easily deployed in MANET. An analytic model of the protocol's throughput has also been developed. We compare the protocol's throughput obtained from its analytic model and simulation to validate each other.
A probabilistic signal-strength-based evaluation methodology for sensor network deployment
(2005)
Kuo, SP
;
Tseng, YC
;
Wu, FJ
;
Lin, CY
;
資訊工程學系
The deployment of senor networks have attracted a lot of attention recently. In essence this issue is concerned with how well a sensing field is monitored by sensors to achieve a particular coverage. In this paper, we propose a signal-strength-based approach to evaluate how well a sensing field is covered/monitored. We first formulate object tracking by a single sensor as a Gaussian-error model. Then we establish an error model on location estimation given that the location of an object is known. This leads to a model to evaluate a sensor network with given locations of sensors. We then apply the result to several applications, such as adding more sensor nodes for error reduction and scheduling power modes (awake or sleep) of sensors, and demonstrate our simulation results.
The coverage problem in a wireless sensor network
(2005-08-01)
Huang, CF
;
Tseng, YC
;
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 sensor network is monitored or tracked by sensors. In this paper, we formulate this problem as a decision problem, whose goal is to determine whether every point in the service area of the sensor network is covered by at least k sensors, where k is a given parameter. The sensing ranges of sensors can be unit disks or non-unit disks. We present polynomial-time algorithms, in terms of the number of sensors, that can be easily translated to distributed protocols. The result is a generalization of some earlier results where only k=1 is assumed. Applications of the result include determining insufficiently covered areas in a sensor network, enhancing fault-tolerant capability in hostile regions, and conserving energies of redundant sensors in a randomly deployed network. Our solutions can be easily translated to distributed protocols to solve the coverage problem.
Distributed protocols for ensuring both coverage and connectivity of a wireless sensor network
(2007-03-01)
Huang, Chi-Fu
;
Tseng, Yu-Chee
;
Wu, Hsiao-Lu
;
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.
On the architecture design and performance evaluation of a configurable Blueweb network
(2007-05-01)
Yu, Chih-Min
;
Huang, Chia-Chi
;
電信工程研究所
;
Institute of Communications Engineering
Blueweb is a self-organizing Bluetooth-based multihop network equipped with a scatternet formation algorithm and a modified source routing protocol. In this paper, we first review the basic Blueweb network. Then we focus on a heuristic automatic configuration algorithm which can be used to partition a large-scale Blueweb network. This algorithm contains three main functional blocks including route master selection, node assignment, and subnet number decision. The route master selection block selects new route masters at a low computation cost. The node assignment block assigns nodes to each newly configured subnet in order to minimize the average route query cost. The subnet number decision block determines the optimal number of subnet which achieves the largest system performance improvement ratio at minimum operation cost. With these three functional blocks, optimal network configuration for Blueweb routing protocol can be determined. Computer simulations show that a configured Blueweb achieves higher network capacity than an unconfigured Blueweb.

學術出版;;Publications

Browse

Filters

Settings

Sort By

Results per page

🏛️國立陽明交通大學機構典藏

Search Results