Browsing by Author "Wang, JT"

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Admission control for variable spreading gain CDMA wireless packet networks
(2000-03-01)
Lee, TH
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Wang, JT
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電信工程研究所
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Institute of Communications Engineering
A technique for variable spreading gain code-division multiple access (VSG-CDMA) with transmit power control has recently been proposed [4], [5] to provide integrated services in a wireless packet network. System capacities of VSG-CDMA networks with and without considering user activity factors were derived. The analysis gives a lower bound of system capacity because a user's transmitted power is considered part of the interference to its own signal. In this paper, we present an optimistic upper bound assuming that there is no multipath fading or the energy of a signal in all multipath components can be fully resolved. An optimum power vector assignment and a simple criterion for all users to simultaneously achieve their quality of service (QoS) requirements tin terms of bit energy-to-interference density ratios) are derived. We found from numerical examples that, compared with the lower bound given in [4] and [5], significant improvement can be obtained if multipath fading can be satisfactorily handled. Several access control schemes are also studied to guarantee delay bound requirements. Simulation results reveal that more connections can be further accommodated with access control.
Admission control for VSG-CDMA systems supporting integrated services
(1998)
Lee, TH
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Wang, JT
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電信工程研究所
;
Institute of Communications Engineering
Variable spreading gain CDMA (VSG-CDMA) technique with transmitting power control has recently been proposed [4] to provide integrated services in a wireless packet network System capacities of VSG-CDMA systems with and without considering user activity factors were derived based on some intuitive arguments. The analysis is imprecise because a user's transmitted power is considered part of the interference to its own signal. In this paper, we present a more precise analysis. An optimal power vector assignment and a simple criterion for all users to achieve simultaneously their quality of service. requirements (in terms of bit energy-to-interference density ratios) are derived. We found from numerical examples that, compared with the rough analysis given in [4], significant improvement can be obtained. An access control scheme is also studied to guarantee delay bound requirements. Simulation results reveal that more connections can be further accommodated with access control.
Admission control for VSG-TDMA/SS multimedia cellular networks
(1998)
Wang, JT
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Lee, TH
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電信工程研究所
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Institute of Communications Engineering
In this paper, we address the admission control issue for the TDMA/SS (Time division multiple access with spread spectrum) system for multimedia services. In the TDMA/SS system, time is divided into frames and each frame is further divided into slots. Only one user is allowed to transmit in a slot and thus spread spectrum technique is adopted to combat inter-cell interference. A packet can occupy more than one slot, depending on the user's data rate and quality of service requirement. We derive a necessary and sufficient condition for a group of users to be admissible for the TDMA/SS system and prove that its admission region contains that of the TDMA/CDMA system. In the TDMA/CDMA system, time is also divided into frames and each frame consists of several slots. The difference is that every packet occupies exactly one slot and multiple users can transmit their packets in the same slot. Numerical results show that the admission region of the TDMA/SS system can be significantly larger than that of the TDMA/CDMA system. To further increase bandwidth utilization and guarantee delay bound requirements, several access control schemes are proposed. Simulation results are obtained for these access control schemes.
An algorithm for converting the contour of a 2D workpiece into a rectilinear polygon
(1996-08-01)
Wu, MC
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Wang, JT
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交大名義發表
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工業工程與管理學系
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National Chiao Tung University
This paper presents an algorithm for converting the contour of a 2D workpiece into a rectilinear polygon. The purpose of providing such a conversion is to model the global shape information of the workpiece. Using an existing algorithm, the rectilinear polygon can further be modeled by a tree structure of line segments, known as the simplified skeleton, which can concisely model the global shape information of a workpiece. That is, workpieces with similar global shape can be classified into the same group by considering the similarity among their simplified skeletons. This algorithm is helpful to enhance the modeling capability of the traditional group technology coding schemes.
An intelligent agent-based mobile resource reservation scheme
(2005)
Wang, JT
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Yang, JS
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Tseng, CC
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資訊工程學系
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Department of Computer Science
This paper presents an Intelligent Agent-based Resource reservation aPproach (IARSVP) to support Quality of Service (QoS) aware packet transmissions for mobile networks. Mobile Intelligent Agents (MIAs) are characterized by their ability to move across wide-area networks, operate autonomously on foreign hosts, and perform tasks on behalf of the originating hosts. With MIAs, IARSVP can pre-allocate resources in advance for anticipated location an MN may visit next. Because MIAs carries the MN's W requirement and administration specification, and mobility association together with the necessary executable codes, they can adjust themselves in accordance with the network topology and current resource usage in locating forwarding points for the anticipated locations the MNs may visit next. Therefore, IARSVP can support route optimization and regional registration naturally, avoid redundant resource reservations made in common routes, and discover alternative route dynamically. Furthermore, MIAs can also perform location updates on behalf of MNs. Simulation results show that IARSVP outperforms Mobile RSVP and Hierarchical Mobile RSVP in terms of forced termination, reservation blocking, and session completion probabilirties.
Non-reinitialized fully distributed power control algorithm
(1999-12-01)
Wang, JT
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Lee, TH
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電信工程研究所
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Institute of Communications Engineering
A fully distributed power control (FDPC) algorithm has been recently proposed for cellular mobile systems. In the algorithm, the connection which has the smallest initial carrier-to-interference (CIR) ratio is removed if CIR requirements are not satisfied after L iterations of power control, The transmitter power levels of surviving connections are then reset to the maximal allowed values and the algorithm is executed again. We prove in this paper that, if the transmitter power levels are not reset after a connection is removed, then a feasible power set can be found faster and the power levels employed are smaller.