Browsing by Author "Jan, RH"

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A cell-based location-sensing method for wireless networks
(2003-06-01)
Chu, HC
;
Jan, RH
;
資訊工程學系
;
Department of Computer Science
One of the most important applications for mobile commerce is location-based application and the core technology of location-based applications is the location-determination technology. In this paper, we present a location-sensing method, called cell-based location-sensing method and its positioning accuracy for the wireless networks with hexagonal structure and mesh structure. In addition, the accuracy of the method is optimized by tuning the transmitting power of base stations. In the optimal transmitting power, an accuracy of within 9.1667% (7.2182%) cell area for hexagonal structure (mesh structure) can be achieved by the cell-based location-sensing method. We believe that the results are useful for deploying wireless networks for location-based applications. Copyright (C) 2003 John Wiley Sons, Ltd.
A cell-numbering plan for seamless handoff in a wireless ATM network
(2000-01-01)
Jan, RH
;
Wu, KR
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資訊工程學系
;
Department of Computer Science
This paper proposes a cell-numbering plan for mobile stations to handoff seamlessly to the cells in a wireless Asynchronous Transfer Mode (ATM) network. It also proposes a minimum-hop rerouting (MHR) method to perform the rerouting of user connections during the handoff. The cell-numbering plan assigns each cell an integer from 1 to 5, ensuring that neighboring cells will have different numbers. Any mobile station that performs a handoff beween any two cells can easily calculate if a reroute is needed. Furthermore, by using the MHR, the path between the originating and terminating mobile stations will be the shortest whenever either of them moves. The signaling bandwidth used for this kind of rerouting is believed to be the smallest among the methods reported to date. (C) 2000 Elsevier Science B.V. All rights reserved.
A GPS-less self-positioning method for sensor networks
(2005)
Chu, HC
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Jan, RH
;
資訊工程學系
;
Department of Computer Science
One challenging issue in sensor networks is to determine where a given sensor node(SN) is physical located. This problem is especially crucial for very small SNs. In this paper we present a GPS-less self-positioning method for sensor networks. In our method, a set of nodes, called as reference points (RPs), are deployed in the sensor network with overlapping regions of coverage. The RP periodically broadcasts beacon frames which contain localization data. The SN collects the beacon frames from RPs and processes the data in the frame, and then it can localize itself simply. The analysis of positioning accuracy are also given to show how well a SN can correctly localize itself.
A hybrid routing method for multi-hop wireless local area networks
(2004-10-01)
Jan, RH
;
Lin, YL
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資訊工程學系
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Department of Computer Science
A multi-hop wireless local area network (LAN) is an adhoc wireless network that connects to the Internet backbone via an access point. Routing paths between mobile hosts and a fixed host can be divided into two sub-paths, wireless and wired. In this paper, we apply the Hierarchical Routing Tree (HRT) concept to finding wireless sub-paths. That is, by constructing an HRT. each mobile host can find a routing path to an access point (i.e.. the HRT root) quickly and thus gain the access to Internet. In addition, we choose the Ad-hoc On-demand Distance Vector (AODV) routing protocol as a point-to-point routing method for sources and destinations located in the same ad-hoc network in order to improve upon a weakness in the HRT method. Numerical experiments are given to show the effectiveness of the hybrid routing method.
A reassembly strategy for reducing IN/PCS signalling traffic
(1996-11-01)
Wu, KR
;
Jan, RH
;
資訊工程學系
;
Department of Computer Science
This paper proposes a simple assembly/disassembly part (ADP) for the signalling system no. 7 (SS7) protocol to reduce the signalling traffic loads in intelligent networks (IN) and personal communication service (PCS) networks. The ADP combines two or more messages with the same destinations into a single message, thereby reducing signalling traffic without affecting SS7 protocol operations, The numerical results show that the proposed method can reduce traffic among signalling points 9 similar to 17%.
A reassembly strategy for reducing IN/PCS signalling traffic
(1996-11-01)
Wu, KR
;
Jan, RH
;
資訊工程學系
;
Department of Computer Science
This paper proposes a simple assembly/disassembly part (ADP) for the signalling system no. 7 (SS7) protocol to reduce the signalling traffic loads in intelligent networks (IN) and personal communication service (PCS) networks. The ADP combines two or more messages with the same destinations into a single message, thereby reducing signalling traffic without affecting SS7 protocol operations, The numerical results show that the proposed method can reduce traffic among signalling points 9 similar to 17%.
An adaptive web system for heterogeneous browsing devices
(2002)
Lin, ME
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Jan, RH
;
資訊工程學系
;
Department of Computer Science
With the development of information technology, the popularity of Internet is out of our imagination, and communication devices are characterized by various capabilities. Facing to the diversity of communication devices and environments, Internet content providers must offer the most adequate services relevant with individual characteristics. Composite Capabilities and Preference Profiles (CC/PP), proposed by the World Wide Web Consortium (W3C), is a protocol of describing a client's capabilities and environments. WWW clients convey capabilities and preferences by means of CC/PP exchange protocol, and then capabilities negotiation is made. In this paper, an adaptive web system, which can adapt various capabilities and preferences of clients, is proposed. In addition, a well-designed content generator in our system produces adequate responses according to CC/PP descriptions. Thus, content personalization is realized and network payloads are alleviated indirectly.
An adjustable structure for topology control in wireless ad hoc networks
(2005)
Jeng, AAK
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Jan, RH
;
交大名義發表
;
National Chiao Tung University
In wireless ad hoc networks, the resources, such as energy, computation power bandwidth and etc, available to each node are scare. Thus to improve the overall performance, the expenditures from the network operations should be balanced through the entire topology. One approach of solving such a problem is to keep the maximum node degree among all nodes as less as possible. However a node,having lower degree often prevents it from choosing, better routes consuming less power between two ends. Therefore, a tradeoff is between the maximum node degree and the energy efficiency. In this paper we propose an adjustable structure, named r-neighborhood graph, to construct the topology of wireless ad hoc networks. The maximum node degree and energy efficiency of the topology can be adjusted through a parameter r 0 r <= 1. Theoretic results show there must be some r such that the worst maximum node degree and the power stretch factor are bounded separately. The connectivity and planarity of the proposed structure are also guaranteed.
An approach for seamless handoff among mobile WLAN/GPRS integrated networks
(2005-12-01)
Jan, RH
;
Chiu, WY
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資訊工程學系
;
Department of Computer Science
Wireless local area networks (WLAN) and General Packet Ratio Service (GPRS) networks are two of the most widely used wireless network systems. In this paper, we propose a mobility support for mobile host roaming between WLAN and GPRS networks. In addition, a handoff decision model is presented to reduce the latency of the handoff procedure. The experimental results, including throughput, packet delay and handoff latency are given to show the performance of our approach. (c) 2005 Elsevier B.V. All rights reserved.
An efficient multiple paths routing protocol for Ad-hoc networks
(2001)
Jiang, MH
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Jan, RH
;
資訊工程學系
;
Department of Computer Science
In this paper we present an efficient routing protocol, called as Multiple Next Hops (MNH) routing protocol, which is based on Ad-hoc On-demand Distance Vector (AODV) routing protocol for ad-hoc networks. The proposed MNH protocol establishes multiple paths during the route discovery procedure. This saves network bandwidth and reduces route reconstruction time when a routing path fails. The numerical experiments are given to show the effectiveness of the MNH routing protocol.
An efficient multiple-path routing protocol for ad hoc networks
(2002-03-15)
Jiang, MH
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Jan, RH
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Wang, CF
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資訊工程學系
;
Department of Computer Science
An ad hoc network is a cooperative engagement of a collection of mobile hosts that requires no intervening of any centralized access point or existing infrastructure, Each mobile host, operating as a specialized router, forwards packets from other mobile hosts. The possibility of fast movement of mobile hosts means network topologies may change frequently. Thus, applying traditional routing schemes to ad hoc networks is inappropriate. In this paper, we present an efficient routing protocol called the multiple next hops (MNH) routing protocol, which is based on the ad hoc on-demand distance vector (AODV) routing protocol for ad hoc networks. The proposed MNH protocol establishes multiple paths for a route discovery procedure, thus conserving network bandwidth and reducing route reconstruction times when routing paths fail. Numerical experiments are given to show the effectiveness of the MNH routing protocol. (C) 2002 Elsevier Science B.V. All rights reserved.
An energy aware, cluster-based routing algorithm for wireless sensor networks
(2005)
Chang, JH
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Jan, RH
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資訊工程學系
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Department of Computer Science
Cluster-based routing protocol has special advantages to enhance scalability and efficiency of the routing protocol. The technique to network clustering that maximizes the network lifetime is an important topic of research in wireless sensor networks. In this paper, we present all energy aware cluster-based routing algorithm (ECRA) for the wireless sensor networks such that the network lifetime can be maximized. ECRA randomly selects some nodes as cluster-heads to construct Voronoi diagram and rotates the intra-cluster nodes to distribute the energy load to all sensors in the network. The simulations show that ECRA algorithm outperforms than direct communication, static clustering and LEACH. The system lifetime of ECRA is approximately 2 times than LEACH. This is because the ECRA rotates intra-cluster-heads to balance the load to all nodes in the sensor networks.
An indoor geolocation system for wireless LANs
(2003)
Jan, RH
;
Lee, YR
;
資訊工程學系
;
Department of Computer Science
With the development of Wireless Local Area Networks(WLANs), people are interested in developing the location-based services for WLAN users, especially in an indoor environment. The core technology of location-based services is the location-sensing technology. In this paper, we present a location-sensing method which is based on the location fingerprinting approach for WLAN in an indoor environment. This paper focuses on the implementation issues of constructing an indoor location-sensing system. These issues include how to increase accuracy of position, how to reduce the efforts of constructing a fingerprint database and what factors influencing the characteristic of the location fingerprint. The experimental results show that our method can achieve a better accuracy.
An optimization model for Web content adaptation
(2006-05-15)
Jan, RH
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Lin, CP
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Chern, MS
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資訊工程學系
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Department of Computer Science
This paper considers Web content adaptation with a bandwidth constraint for server-based adaptive Web systems. The problem can be stated as follows: Given a Web page P consisting of n component items d(1), d(2),...,d(n) and each of the component items d(i) having J(i) versions d(i1), d(i2),... d(ut), for each component item d(i) select one of its versions to compose the Web page such that the fidelity function is maximized subject to the bandwidth constraint. We formulate this problem as a linear multi-choice knapsack problem (LMCKP). This paper transforms the LMCKP into a knapsack problem (KP) and then presents a dynamic programming method to solve the KP. A numerical example illustrates this method and shows its effectiveness. (c) 2005 Elsevier B.V. All rights reserved.
Cell-based positioning method for wireless networks
(2002)
Chu, HC
;
Jan, RH
;
資訊工程學系
;
Department of Computer Science
One of the most important applications for mobile commerce is location-based application and the core technology of location-based applications is the location determination technology. In this paper, we present a positioning method, called as cell-based positioning method and its positioning accuracy measure for the wireless networks with hexagon structure and mesh structure. In addition, the positioning accuracy is optimized by tuning the base stations' transmission power In the optimal transmission power an accuracy of within 9.1% (7.2%) cell area for hexagonal structure, (mesh structure) can be achieved by cell-based positioning method. We believe that the results are useful to deploy wireless networks for location-based applications.
Energy-aware, load balanced routing schemes for sensor networks
(2004)
Huang, SC
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Jan, RH
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資訊工程學系
;
Department of Computer Science
This paper presents two energy-aware, load balanced routing schemes, called as maximum capacity path (MCP) scheme and MCP with path switching (MCP-PS) scheme, for sensor networks. In the MCP scheme, the sensor network is constructed into a layered network at first. Based on the layered network, every sensor node selects a shortest path with maximum capacity to sink. In MCP-PS, the node may switch its routing path to its sibling neighbors in order to share the traffic. The simulation results show that our MCP and MCP-PS schemes can achieve a better load-sharing and better endurance on network lifetime.
Heuristic algorithms for packing of multiple-group multicasting
(2002-06-01)
Wang, CF
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Liang, CT
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Jan, RH
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資訊工程學系
;
Department of Computer Science
Multicast communication is an efficient routing method for multimedia data distribution, since it can save network bandwidth during the communication session. Thus, the multicast routing problems have received much attention from many researchers. In this paper, we consider a multicast routing problem with multiple multicast sessions under a capacity limited constraint. This problem is formulated as a tree packing problem. We propose two heuristic algorithms, Steiner-tree-based heuristic (STH) algorithm and cut-set-based heuristic (CSH) algorithm, for solving this problem. The simulation results show that the STH algorithm can find a better approximate solution in a shorter computation time compared to CSH. In addition, if the available bandwidth for the service is just enough, the STH and CSH algorithms may fail to find a solution even if the solution exists. The simulation results also indicate that CSH has a higher probability than STH to find a solution. Thus, it is suggested that one can apply the STH algorithm first to solve the tree packing problem. In case STH fails, CSH algorithm will be used instead.
Improving the accuracy of cell-based positioning for wireless networks
(2004-12-20)
Jan, RH
;
Chu, HC
;
Lee, YF
;
資訊工程學系
;
Department of Computer Science
One fundamental issue for location-based services and applications is solving the location-sensing problem, i.e., determining where a given node is physically located in a network. In a previous paper, we have presented a location-sensing method, called the cell-based positioning method, and its positioning accuracy for the wireless networks with a hexagonal structure and mesh structure. Unfortunately, in real situations, a wireless network may not have a hexagonal or mesh structure. Thus, in this paper we consider networks with irregular structures and present an algorithm to determine the positioning accuracy of the cell-based method in such networks. In addition, we use the simulated annealing (SA) method to determine the locations and transmission ranges of base stations in order to achieve the best possible positioning accuracy. Simulation results show that the accuracy can be improved up to 30% by the SA method. The results are useful for deploying a wireless network for location-based applications. (C) 2004 Elsevier B.V. All rights reserved.
Internetting connectionless data networks with a wide area public ATM network
(1997-08-01)
Tsai, IF
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Jan, RH
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資訊工程學系
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Department of Computer Science
Connectionless data services on ATM-based B-ISDN can be realized directly by means of the connectionless service function which is provided in connectionless servers. In this paper, we consider how to locate a certain amount of connectionless servers among the switching nodes in a public ATM network for the internetworking of connectionless data networks. The problem is formulated as a network optimization problem which is similar to the p-median problem. Two algorithms, one based on the greedy method and the other using branch-and-bound strategy, are presented to determine the locations of connectionless servers. By finding the optimal locations of connectionless servers, an optimal virtual overlay network which has minimized total transport costs for the connectionless data traffics can be constructed. (C) Elsevier Science B.V.
Optimum multicast of multimedia streams
(1999-04-01)
Wang, CF
;
Lai, BR
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Jan, RH
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資訊工程學系
;
Department of Computer Science
In a VOD system, multicast is a preferred method for saving network bandwidth. That is, customers requesting the same video program over a small time interval can be arranged in a multicast tree (group), and then the video server sends a video stream via this tree to customers. In this research, we considered how to arrange a set of multicast trees such that the number of customers served is maximized and the link capacity constraint is maintained. For a directed acyclic graph (DAG), we proposed a branch-and-bound algorithm to solve this problem and the solution method is illustrated by example. Next, we extended the algorithm to find an approximate solution for a general graph case. It is shown, through simulations on randomly generated graphs that the solution for our approximation method is very close to the optimal solution. (C) 1999 Elsevier Science Ltd. All rights reserved.