Browsing by Author "Lin, YB"

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A graphical user interface design for network simulation
(1997-02-01)
Lin, YB
;
Geigel, J
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資訊工程學系
;
Department of Computer Science
This article describes a prototyping effort of a flexible graphical user interface (GUI) for a simulation tool called COPS. The GUI is designed to allow parameter setup for all modules in simulation model, and can be easily replaced by new GUIs implemented in different languages/graphical tools. This article provides design guidelines and implementation details of the flexible GUI. (C) 1997 by Elsevier Science Inc.
A mobile service platform using proxy technology
(2006-02-01)
Chen, MF
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Lin, YB
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Rao, HCH
;
Wu, Q
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資訊工程學系
This paper proposes iMobile, a proxy-based platform for developing mobile services for various mobile devices and wireless access technologies. iMobile acts as a message gateway that allows mobile devices to relay messages to each other through various protocols on different access networks. It allows mobile devices to access internet services, corporate databases and to control various network devices. iMobile implements three key abstractions: dev-let, info-let and app-let. An info-let provides abstract view of information space. An app-let implements service or application logic by processing information from various info-lets. A dev-let receives and sends messages through any particular protocols for mobile devices. The let engine supports user and device profiles for personalization and transcoding, and invokes proper app-lets and info-lets to answer requests from a dev-let. The Mobile modular architecture allows developers to write device drivers, information access methods and application logic independently from each other. Copyright (c) 2005 John Wiley & Sons, Ltd.
A mobility management strategy for GPRS
(2003-11-01)
Lin, YB
;
Yang, SR
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資訊工程學系
;
Department of Computer Science
In general packet radio service (GPRS), a mobile station (MS) is tracked at the cell level during packet transmission, and is tracked at the routing-area (RA) level when no packet is delivered. A READY timer (RT) mechanism was proposed in 3GPP 23.060 to determine when to switch from cell tracking to RA tracking. In this mechanism, a threshold interval T is defined. If no packet is delivered within T, the MS is tracked at the RA level. When a packet arrives, the MS is tracked at the cell level again. However, the RT mechanism has a major fallacy in that the RTs in both the MS and the serving GPRS support node may lose synchronization. This paper considers another mechanism called READY counter (RC) to resolve this problem. In this approach, a threshold K is used. Like the RT approach, the MS is tracked at the cell level during packet transmission. If no packets are delivered after the MS has made K cell crossings, the MS is tracked at the RA level. We also devise an adaptive algorithm called dynamic RC (DRC). This algorithm dynamically adjusts the K value to reduce the location update and paging costs. We propose analytic and simulation models to investigate RC, RT, and DRC. Our study indicates that RC may outperform RT. We also show that DRC nicely captures the traffic-mobility patterns and always adjusts the K threshold close to the optimal values.
A mobility management strategy for UMTS
(2003)
Yang, SR
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
Universal Mobile Telecommunications System (UMTS) utilizes a three-level location management strategy to reduce the net costs of location update and paging in the packet-switched service domain. Within a communication session, a mobile station (MS) is tracked at the cell level during packet transmission. In the idle period of an ongoing session, the MS is tracked at the UTRAN registration area (URA) level to avoid frequent cell updates while still keeping the radio connection. If the MS is not in any communication session, the MS is tracked at the routing area (RA) level. The inactivity counter mechanism was proposed in 3GPP 25.331 to determine when to switch between the three location tracking modes. In this mechanism, two inactivity counters are used to count the numbers of cell updates and URA updates in an idle period between two packet transmissions. If the number of cell updates reaches a threshold K-1, the MS is switched from the cell tracking to the URA tracking. After that, if the number of URA updates reaches a threshold K-2, the MS is tracked at the RA level. This paper proposes simulation model to investigate the performance of the inactivity counter mechanism. Our study provides guidelines for K-1 and K-2 selection to achieve lower net costs of location update and paging.
A multicast mechanism for mobile networks
(2001-11-01)
Lin, YB
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資訊工程學系
;
Department of Computer Science
This letter proposes a multicast table approach to support GSM/UMTS multicast that minimizes the paging cost. The implementation and execution of the multicast tables are very efficient. The costs for updating these tables can be ignored compared with the costs of standard location update procedures. Furthermore, our mechanism can be implemented within the mobility databases without modifying the standard location update messages. We show that our mechanism always outperforms the existing GSM/UMTS multicast mechanisms.
A new random walk model for PCS networks
(2000-07-01)
Akyildiz, IF
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Lin, YB
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Lai, WR
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Chen, RJ
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資訊工程學系
This paper proposes a new approach to simplify the two-dimensional random walk models capturing the movement of mobile users in Personal Communications Services (PCS) networks. Analytical models are proposed for the new random walks. For a PCS network with hexagonal configuration, our approach reduces the states of the two-dimensional random walk from (3n(2) + 3n - 5) to n(n + 1)/2, where n is the layers of a cluster. For a mesh configuration, our approach reduces the states from (2n(2) - 2n + 1) to (n(2) + 2n + 4)/4 if n is even and to (n(2) + 2n + 5)/4 if n is odd. Simulation experiments are conducted to validate the analytical models. The results indicate that the errors between the analytical and simulation models are within 1%, Three applications (i.e., microcell/macrocell configuration, distance-based location update, and GPRS mobility management for data routing) are used to show how our new model can be used to investigate the performance of PCS networks.
A performance study of CDPD
(1999-10-01)
Tsai, WN
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Lin, YB
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資訊工程學系
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Department of Computer Science
Cellular digital packet data (CDPD) is a wireless extension to data networks, which utilizes the idle capacity (radio channels) of cellular systems. This paper studies the performance of the CDPD system to investigate how the CDPD traffic and the voice traffic affect the CDPD blocking probability. The results offer guidelines for the CDPD network planning. (C) 1999 Published by Elsevier Science Inc. All rights reserved.
A push mechanism for GPRS supporting private IP addresses
(2003-01-01)
Lin, YB
;
Lo, YC
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Rao, HCH
;
資訊工程學系
;
Department of Computer Science
General Packet Radio Service (GPRS) provides packet switched data service for mobile users. However, the existing GPRS specification does not provide the push mechanism and it is difficult to support GPRS services such as call termination (incoming call) for wireless voice over IP (VoIP). Based on short message service, this paper proposes a push mechanism for GPRS supporting private IP addresses. Our approach does not need to modify the existing GPRS structure.
A software architecture for GPRS session management
(2002-03-01)
Haung, YR
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Lin, YB
;
資訊工程學系
;
Department of Computer Science
General packet radio service (GPRS) provides efficient access to the integrated services Internet from wireless networks. When the GPRS-attached mobile station attempts to send or receive data, a packet data protocol (PDP) context shall be established. The GPRS session management (SM) supports the PDP context handling, which consists of PDP context activation, deactivation, and modification procedures. In this paper, we propose an SM software architecture for the serving GPRS support node. Our design goals are to achieve compatibility. modularity, and flexibility. More importantly, our approach can accommodate the design of the SM software architecture for third-generation wireless networks. Copyright (C) 2001 John Wiley Sons, Ltd.
A statistic approach for deriving the short message transmission delay distributions
(2004-11-01)
Hung, HN
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Lin, YB
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Lu, MK
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Peng, NF
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統計學研究所
Short Message Service (SMS) is one of the most popular mobile data services. This paper develops a web-based short message system and analyzes the short message transmission delays based on 40 000 measured data collected from commercial operation. We investigate the distributions of SMS round-trip transmission delays. These distributions are roughly approximated by truncated normal, gamma, log-normal, and Weibull distributions with various parameters, which can be utilized in theoretical analysis. Furthermore, with the nonparametric fitting approach, we use the rejection method to develop random number generators for these delays, which can be used in any simulation models that employ SMS transmission delays.
Active, programmable, and mobile code networking
(2000-03-01)
Morreale, P
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Sohraby, K
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Li, B
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Lin, YB
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資訊工程學系
Active, programmable, and mobile code networking
(2000-03-01)
Morreale, P
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Sohraby, K
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Li, B
;
Lin, YB
;
資訊工程學系
Active, programmable, and mobile code networking
(2000-04-01)
Morreale, P
;
Sohraby, K
;
Li, B
;
Lin, YB
;
資訊工程學系
Adaptive algorithms for reducing PCS network authentication traffic
(1997-08-01)
Lin, YB
;
Mohan, S
;
Sollenberger, N
;
Sherry, H
;
資訊工程學系
Two authentication schemes (AS's) ha ce been proposed in the Electronic Industry Association/Telecommunications Industry Association's (EIA/TIA) Telecommunications Systems Bulletins (TSB's) 51 for incorporation in the cellular industry Interim Standard IS 41 Revision C. In the first scheme, which we refer to as the RS scheme, a unique secret key [also known as shared secret data (SSD)] is Shared only between the authentication center (AC) and handset. In the second scheme, referred to as the S scheme, the SSD is also shared with the visited system. The performance of the two schemes can be compared by using the expected number of call originations/terminations between two consecutive registrations or call-to-mobility ratio (CMR). Based on the message flow (accesses to databases), it is apparent that the S scheme outperforms the WS schemes if the CMR ratio is large. The CMR's of users will likely span a wide range and, even for the same user, will perhaps vary from time to time. It is therefore desirable to switch between the AS's based on the users' CMR to reduce the signaling network traffic. We propose two adaptive algorithms to determine how and when to switch between the AS's for a given user. Our performance study indicates that as the CMR of a user changes, the adaptive algorithms automatically select the best AS in real time.
Adaptive algorithms for reducing PCS network authentication traffic
(1997-08-01)
Lin, YB
;
Mohan, S
;
Sollenberger, N
;
Sherry, H
;
資訊工程學系
Two authentication schemes (AS's) ha ce been proposed in the Electronic Industry Association/Telecommunications Industry Association's (EIA/TIA) Telecommunications Systems Bulletins (TSB's) 51 for incorporation in the cellular industry Interim Standard IS 41 Revision C. In the first scheme, which we refer to as the RS scheme, a unique secret key [also known as shared secret data (SSD)] is Shared only between the authentication center (AC) and handset. In the second scheme, referred to as the S scheme, the SSD is also shared with the visited system. The performance of the two schemes can be compared by using the expected number of call originations/terminations between two consecutive registrations or call-to-mobility ratio (CMR). Based on the message flow (accesses to databases), it is apparent that the S scheme outperforms the WS schemes if the CMR ratio is large. The CMR's of users will likely span a wide range and, even for the same user, will perhaps vary from time to time. It is therefore desirable to switch between the AS's based on the users' CMR to reduce the signaling network traffic. We propose two adaptive algorithms to determine how and when to switch between the AS's for a given user. Our performance study indicates that as the CMR of a user changes, the adaptive algorithms automatically select the best AS in real time.
An adaptive measured-based preassignment scheme with connection-level QoS support for mobile networks
(2002-07-01)
Luo, XY
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Li, B
;
Thng, ILJ
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Lin, YB
;
Chlamtac, I
This paper presents a new adaptive bandwidth allocation scheme to prevent handoff failure in wireless cellular networks, known as the measurement-based preassignment (MPr) technique. This technique is particularly useful in micro/pico cellular networks which offers quality-of-service (QoS) guarantee against call dropping: The proposed MPr scheme distinguishes itself from the well-known guarded channel (GC) based schemes in that it allows the handoff calls to utilize a prereserved channel. pool before competing for the shared channels with new call arrivals. The key advantage of the proposed MPr scheme is that it enables easy derivation of the number of channels that needs to be reserved for handoff based on a predetermined handoff dropping probability, without the need for solving the often complex Markov chain required in GC schemes; thus, making the proposed MPr scheme-simple and efficient for implementation. This is essential in handling multiple traffic types with potentially different QoS requirements. In addition, the MPr scheme is adaptive in that it can dynamically adjust the number of reserved channels for the handoff according to the periodical measurement of the traffic status within a local cell; thus completely eliminating the signaling overhead for status information exchange among cells mandated in most existing channel allocation schemes. Numerical results and comparisons are given to illustrate the tradeoff.
An all-IP approach for UMTS third-generation mobile networks
(2002-09-01)
Lin, YB
;
Pang, AC
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Haung, YR
;
Chlamtac, I
;
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.
Asynchronous parallel discrete event simulation
(1996-07-01)
Lin, YB
;
Fishwick, PA
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資訊工程學系
;
Department of Computer Science
Complex models may have model components distributed over a network and generally require significant execution times. The field of parallel and distributed simulation has grown over the past fifteen years to accommodate the need of simulation the complex models using a distributed versus sequential method. In particular, asynchronous parallel discrete event simulation (PDES) has been widely studied, and yet we envision greater acceptance of this methodology as more readers are exposed to PDES introductions that carefully integrate real-world applications. With this in mind, we present two key methodologies (conservative and optimistic) which have been adopted as solutions to PDES systems. We discuss PDES terminology and methodology under the umbrella df the personal communications services application.
Asynchronous parallel discrete event simulation
(1996-07-01)
Lin, YB
;
Fishwick, PA
;
資訊工程學系
;
Department of Computer Science
Complex models may have model components distributed over a network and generally require significant execution times. The field of parallel and distributed simulation has grown over the past fifteen years to accommodate the need of simulation the complex models using a distributed versus sequential method. In particular, asynchronous parallel discrete event simulation (PDES) has been widely studied, and yet we envision greater acceptance of this methodology as more readers are exposed to PDES introductions that carefully integrate real-world applications. With this in mind, we present two key methodologies (conservative and optimistic) which have been adopted as solutions to PDES systems. We discuss PDES terminology and methodology under the umbrella df the personal communications services application.
Authenticated public-key distribution over WLAN/cellular dual networks
(2005)
Hwu, JS
;
Chen, RJ
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
Public-key cryptosystems are characterized by the use of two keys, one held privately and the other available publicly. The main concern in a public-key setting is the authenticity of the public key. This authentication problem is typically resolved by the use of verifiable information called certificate, which is issued by a trusted third party and consists of the user name and his public key. The integrated WLAN/cellular networks enable simultaneous access to both cellular network and wireless LAN. This paper proposes a certificate-free public-key distribution scheme over WLAN/cellular dual networks.