Browsing by Author "Pang, AC"

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An all-IP approach for UMTS third-generation mobile networks
(2002-09-01)
Lin, YB
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Pang, AC
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Haung, YR
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Chlamtac, I
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交大名義發表
This article describes the UMTS all-IP approach for third-generation mobile systems, with emphasis on the core network architecture. Followng the introduction of the core network nodes, we elaborate on application-level registration, circuit-switched call origination, packet-switched call origination, and packet-switched call termination.
Comparing soft and hard handoffs
(2000-05-01)
Lin, YB
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Pang, AC
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資訊工程學系
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Department of Computer Science
This paper studies the soft-handoff mechanism and compares its performance with hard handoff, Our study indicates that although a handset may potentially consume extra radio links in soft handoff, the mechanism provides better opportunity to transfer the link successfully in the handoff procedure. Thus, by carefully planning the overlay areas of cells, soft handoff can outperform hard handoff.
Impact of mobility on mobile telecommunications networks
(2005-11-01)
Lin, YB
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Pang, AC
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Rao, HCH
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資訊工程學系
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Department of Computer Science
This paper describes the mobility management mechanisms for mobile telecommunications networks. There are two major types of mobility: radio network mobility and core network mobility. Radio network mobility supports radio link switching of a mobile user during conversation, and core network mobility provides roaming and tunnel-related management for packet re-routing due to user movement. Impact of mobility on both the radio and the core networks is addressed in this paper. Also, potential research issues on these topics are discussed. Copyright (C) 2005 John Wiley & Sons, Ltd.
Implicit deregistration with forced registration for PCS mobility management
(2001)
Pang, AC
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Lin, YB
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Fang, YG
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資訊工程學系
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Department of Computer Science
Registration/deregistration with a mobility database called Visitor Location Registers (VLRs) is required in a PCS network when a mobile phone moves between registration areas. Several schemes were proposed to deregister a mobile phone after it moves out of a registration area. A simple scheme, called implicit deregistration, is studied in this paper, which does not specifically deregister any obsolete record in the VLR. If the VLR is full when a mobile phone arrives, a record in the VLR is deleted and the reclaimed storage is reassigned to the incoming mobile phone. It is possible that a valid record will be deleted. If so, the VLR record of a mobile phone may be deleted before a call to the mobile phone arrives. Our previous work assumed that the incoming call setup would be lost. In this paper, we propose forced registration to restore the VLR record before the call setup operation can proceed. With this modification, implicit deregistration totally eliminates the deregistration traffic at the cost of creating some forced registration traffic. We derive the record-missing probability and the portion of the network traffic saved by implicit deregistration. Our study indicates that implicit deregistration with forced registration may significantly reduce the deregistration traffic if the user mobility is high and the number of mobile phones in a registration area is not very large.
Modeling mis-routing calls due to user mobility in wireless VoIP
(2000-12-01)
Pang, AC
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Lin, P
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Lin, YB
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資訊工程學系
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Department of Computer Science
This letter proposes an analytic model to study the mis-routing problem caused by user mobility in a wireless VoIP system. We derive the probability that there are n mis-routed calls when a subscriber moves from IP network to the GSM network. Our study indicates that if the user residence times in GSM location areas, inter-call origination times and the inter-call delivery times are of the same order, then the mis-routing effect can not be ignored.
Repacking on demand for hierarchical cellular networks
(2005-11-01)
Tsai, HM
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Pang, AC
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Lin, YC
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Lin, YB
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資訊工程學系
In mobile telecommunications operation, radio channels are scarce resources and should be carefully assigned. One possibility is to deploy the hierarchical cellular network (HCN). This paper studies a HCN channel assignment scheme called repacking on demand (RoD). RoD was originally proposed for wireless local loop networks. We expend this work to accommodate mobile HCN. A simulation model is proposed to study the performance of HCN with RoD and some previously proposed schemes. Our study quantitatively indicates that RoD may significantly outperform the previous proposed schemes.
Repacking on demand for speed-sensitive channel assignment
(2005-01-14)
Tsai, HM
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Pang, AC
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Lin, YC
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Lin, YB
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資訊工程學系
In mobile telecommunications networks, radio channels are limited resources that should be carefully allocated. To increase network capacity, channel assignment can be exercised in a hierarchical cellular network (HCN). By considering the speeds of MSs, we propose an HCN channel assignment approach called repacking on demand (RoD). A simulation model is developed to investigate the performance of RoD and some previously proposed approaches for HCN. Our study quantitatively shows that RoD significantly outperforms the previous proposed approaches. (C) 2004 Elsevier B.V. All rights reserved.
Serving radio network controller relocation for UMTS All-IP network
(2004-05-01)
Pang, AC
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Lin, YB
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Hsien-Ming, T
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Agrawal, P
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資訊工程學系
To support real-time multimedia services in UNITS all-IP network, Third-Generation Partnership Project TR 25.936 proposed two approaches to support real-time serving radio network controller (SRNC) switching, which require packet duplication during SRNC relocation. These approaches significantly consume extra system resources. This paper proposes the fast SRNC relocation (FSR) approach that does not duplicate packets. In FSR, a packet buffering mechanism is implemented to avoid packet loss at the target RNC. We propose an analytic model to investigate the performance of FSR. The numerical results show that packet loss at the source RNC can be ignored. Furthermore, the expected number of packets buffered at the target RNC is small, which does not prolong packet delay.
vGPRS: A mechanism for voice over GPRS
(2003)
Chang, MF
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Lin, YB
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Pang, AC
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資訊科學與工程研究所
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Institute of Computer Science and Engineering
This paper proposes vGPRS, a voice over IP (VoIP) mechanism for general packet radio service (GPRS) network. In this approach, a new network element called VoIP mobile switching center (VMSC) is introduced to replace standard GSM MSC. Both standard GSM and GPRS mobile stations can be used to receive real-time VoIP service, which need not be equipped with the VoIP (i.e., H.323) terminal capabilities. The vGPRS approach is implemented using standard H.323, GPRS, and GSM protocols. Thus, existing GPRS and H.323 network elements are not modified. Furthermore, the message flows for vGPRS registration, call origination, call release and call termination procedures are described to show the feasibility of our vGPRS system.
vGPRS: A mechanism for voice over GPRS
(2001)
Lin, YB
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Pang, AC
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Chang, MF
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資訊工程學系
;
Department of Computer Science
This paper proposes vGPRS, a voice over IP (VoIP) mechanism for general packet radio service (GPRS) network. In this approach, a new network element called VoIP mobile switching center (VMSC) is introduced to replace standard GSM MSG. The vGPRS approach is implemented using standard H.323, GPRS, and GSM protocols. Thus, existing GPRS and H.323 network elements are not modified. Furthermore, both standard GSM and GPRS mobile stations can be used to receive vGPRS service, which need not be equipped with the VoIP (i.e., H.323) terminal capabilities.
Voice over wireless local area network
(2006-02-01)
Shen, XM
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Lin, YB
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Pang, AC
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Pan, JP
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資訊工程學系