Browsing by Author "Wang, TP"

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A fair protocol for fast resource assignment in wireless PCS networks
(1999)
Wang, TP
;
Tseng, CC
;
Hwang, SY
;
資訊工程學系
;
Department of Computer Science
Efficient sharing of communication resources is essential to PCS networks since the wireless bandwidth is limited. The Resource Auction Multiple Access (RAMA) protocol was recently proposed for fast resource assignment and handover in wireless PCS networks. The RAMA protocol assigns available communication resources (e.g., TDMA time slots or frequency channels) to subscribers one at a time using a collision resolution protocol based on subscriber ID's. However, the RAMA protocol encounters an unfairness problem; furthermore, performance results also indicate that it is inefficient at transmitting fixed-length subscriber ID's. Moreover, the emerging services such as teleconferencing have been presenting new challenges to dynamic-priority resource assignment. Tn this paper, we propose a modification to the RAMA protocol to improve its performance and resolve the unfairness problem. The proposed protocol also adopts dynamic priority assignment to improve the QOS for subscribers in overload environments.
Automatic chromosome classification using medial axis approximation and band profile similarity
(2006)
Kao, JH
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Chuang, JH
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Wang, TP
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資訊工程學系
;
Department of Computer Science
Automated chromosome classification is an essential task in cytogenetics and has been an important pattern recognition problem. Numerous attempts were made in the past to characterize chromosome to perform clinical and cancer cytogenetics research. It is important to determine optimum features and develop feature extraction schemes for chromosome classification. In this paper we propose novel approaches for medial axis determination and profile matching of human chromosome. The medial axis determination plays a critical role for precise and complete extraction of band patterns of chromosomes. The features of the band profile obtained along the axis are then used in the classification process. In particular, the medial axis is obtained by simple cross-section analysis and the classification is accomplished through iterative pairing of band profiles. According to the experimental results, the developed automatic system can efficiently extract band profiles of the chromosomes along their medial axes, and satisfactory chromosome classification results can be obtained.
HLR replication protocols for global mobility management in PCS networks
(2003-01-01)
Lee, GC
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Wang, TP
;
Tseng, CC
;
資訊工程學系
;
Department of Computer Science
The new trend for PCS networks is to provide mobile users with large-scale mobile capability across many service areas. In this scenario, global database management for PCS networks has become an increasingly important research issue. In this paper, we examined two replicated database strategies, single-replica (SR) and multiple-replica (MR), for large-scale mobility of per-user data management in personal communication networks. The SR strategy uses a single replica approach of HLR. The MR strategy replicates the per-user data of HLR in many regions. The two strategies are based a partial replication scheme, and a primary copy method is used to maintain replicas' consistency. Our numerical results show that the MR strategy outperforms the SR strategy in most situations; however, it may be worse when the probability of a mobile user visiting a foreign region is high and the query rates from other foreign regions are low. Additionally, the number of replicas should be compact in the MR strategy in order to achieve a reasonable query response time. Therefore, we propose an adaptive multiple replication protocol to choose a suitable replication strategy and to decide the optimized number of replicas.
HMRSVP: A hierarchical mobile RSVP protocol
(2003)
Tseng, CC
;
Lee, GC
;
Liu, RS
;
Wang, TP
;
資訊工程學系
In this paper, we propose a hierarchical Mobile RSVP (HMRSVP) that can achieve mobility independent QoS-guaranteed services in mobile computing environments. The HMRSVP integrates RSVP with Mobile IP regional registration and makes advance resource reservations only when an inter-region movement may possibly occur. We first show that, by NS simulator, our HMRSVP can achieve the same QoS guarantees as MRSVP does with fewer resource reservations. Then, we show that HMRSVP outperforms MRSVP in terms of reservation blocking, forced termination and session completion probabilities.
Registration area planning for PCS networks using genetic algorithms
(1998-08-01)
Wang, TP
;
Hwang, SY
;
Tseng, CC
;
資訊工程學系
;
Department of Computer Science
In a personal communication services (PCS's) network, the signaling traffic required to support user mobility is extremely high due to the huge numbers of users and the small sizes of cells. The requirement to minimize this traffic increases the importance of registration area (RA) planning in the PCS network design. In the literature, several heuristic algorithms have been proposed for RA planning, however, they may get trapped into local minimums and may lack robustness. In this paper, we reformulate the problem of RA planning as a cost-optimization problem and propose genetic algorithms for RA planning in PCS networks. Simulation results show that genetic algorithms are robust for RA planning.
Resetting forwarding pointers with delay propagation schemes in a distributed HLR environment
(2001-04-01)
Lee, GC
;
Wang, TP
;
Tseng, CC
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose a new location tracking method for pointer forwarding with distributed HLRs schemes to decrease the location tracking cost. Similar to the distributed HLR schemes, the location information is replicated on all HLRs in our scheme. However, unlike the traditional distributed HLR schemes, we propagate the most recent location changes from an HLR to reset the forwarding pointers in other HLRs, and thus reduce the cost of location tracking for call deliveries. The signaling cost of location propagation may be too costly to be practical. Therefore, we allow some inconsistency to exist among the location data of HLRs and defer the propagation of location changes to reduce the propagation cost. Three delay propagation policies are also proposed and analyzed using simulation. The performance result shows that the delay propagation policies reduce the propagation cost and the propagation resetting process degrades the location tracking cost. Our method preserves a low total cost for call deliveries, registrations and propagations in distributed HLRs.
Resource reservation with pointer forwarding schemes for the mobile RSVP
(2001-07-01)
Lee, GC
;
Wang, TP
;
Tseng, CC
;
資訊工程學系
;
Department of Computer Science
In this letter, we propose a pointer forwarding scheme for the Mobile Resource reSerVation Protocol (MRSVP) to reduce the resource reservation cost on the wireless Internet, We show the pointer forwarding scheme could significantly degrade the reservation cost when a mobile host performs locality movement.
Stateful session handoff for mobile WWW
(2006-05-08)
Hsieh, MD
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Wang, TP
;
Tsai, CS
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Tseng, CC
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資訊工程學系
This paper proposes a web session handoff system that can hand over not only stateless but also stateful sessions between homogenous and heterogeneous user devices to enable uninterrupted and seamless web access. The proposed system adopts a proxy-based approach and an optional client-assisted scheme in order to track and hand over session information. In the proposed system, a session is registered at a User Agent Proxy (UAP) and then tracked by the UAP so that the session can be handed over from one device via the UAP to another device. In addition to session information tracked by a UAP, the UAP can hand over more comprehensive session information by using the client-assisted scheme. Compared with client-based approaches, our design has several advantages, such as less modification to user devices, practicability, and fault tolerance. We have implemented a UAP on a PC and client programs for both PC and PDA. The implementation can successfully hand over between PC and PDA a stateful session for online shopping applications. (C) 2005 Elsevier Inc. All rights reserved.