Browsing by Author "Chi, Kuang-Hui"

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A Fast Authentication Scheme for WiMAX-WLAN Vertical Handover
(2013-07-01)
Huang, Kuei-Li
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Chi, Kuang-Hui
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Wang, Jui-Tang
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Tseng, Chien-Chao
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資訊工程學系
In view that authentication has made a significant determinant in handover delay, this paper presents a fast authentication mechanism for mobile stations roaming within a WiMAX-WLAN interconnected environment. Incorporating a key reuse design that prevents repeated transactions at a remote server, our mechanism distributes security contexts ahead of handover to a local trusted key holder which manages several sites. A target site, upon receiving a mobile station, retrieves the contexts locally for authentication purpose and thus completes handover efficiently. While employing a target prediction algorithm as an option, our mechanism distributes the contexts to target candidates as dictated, which further improves handover performance if target prediction hits and maintains its advantage even in a miss. In addition, the handover optimization design specified in WiMAX is extended to support WiFi-to-WiMAX handovers. We reason that the proposed mechanism does not compromise the system in any sense as well. Analytical and simulation results show that, despite key pre-distribution misses, our mechanism leads to marked improvement over counterpart schemes in terms of handover delay and packet loss, meeting delay-sensitive application requirements.
An IP-decoupling approach to host mobility
(2007-01-01)
Wang, Chun-Chieh
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Chi, Kuang-Hui
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
This paper presents the design, implementation, and performance evaluation of an approach to supporting host mobility in the wireless Internet. We observe that a single IP address conventionally serves dual purposes: a network-level routing directive and an endpoint identity of a certain session in transport or upper layers. Therefore, when a host affiliates with a new IP address due to movements, any pre-established active session thereupon suffers outage. Unlike prior schemes exploiting mobility agents, we propose to let a host use two IP addresses for network- and transport-layer identifications, respectively, and introduce a translation table that associates the two identities. Such an association results from querying or dynamic updates to the Domain Name System, or from direct message exchanges between two communication peers so as to optimize delivery paths. Simulation results show that our scheme outperforms counterpart Mobile IP and Mobile IPv6, in terms of communication delay, packet error rate, message space overhead, and potential packet loss during handoffs. Additionally, qualitative discussions conclude that our proposal lends itself to IPv4 and IPv6 interconnected networks, or multi-tier environment such as wireless Local Area Networks and mobile telecommunication overlay systems.
Fast Handoff among IEEE 802.11r Mobility Domains
(2010-07-01)
Chi, Kuang-Hui
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Tseng, Chien-Chao
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Tsai, Ya-Hsuan
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資訊工程學系
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Department of Computer Science
This paper deals with secure fast handoff among access points (APs) of different IEEE 802.11r mobility domains. We leverage standard IEEE 802.11i mechanisms to let a station preauthenticate and establish a pairwise transient key with some target AP beforehand. Upon reassociation, the new AP aware of the preauthenticated station can thus complete handoff sooner than would otherwise be required. In order to resolve target APs timely, we introduce a location server that maintains network topology of an autonomous system covering multiple mobility domains. The location server assesses with which AP(s) the mobile station may reassociate next using its migration tendency. Accordingly the station is instructed to preauthenticate with fewer potential next APs than unnecessary. Performance discussions indicate that our proposal is effective in practice. Our approach is not only complementary to emerging IEEE 802.11r-based techniques but also useful to any network-layer fast handoff schemes for streamlined communication.
Fast Handoff in Secure IEEE 802.11s Mesh Networks
(2011-01-01)
Chi, Kuang-Hui
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Shih, Yung-Chien
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Liu, Ho-Han
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Wang, Jui-Tang
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Tsao, Shiao-Li (Charles)
While mesh networking is gaining momentum with widespread application, we are concerned with fast handoff in a secure mesh environment. To this end, this paper presents a means in the context of IEEE 802.11s of letting a mesh portal act as an IEEE 802.1X authenticator to reduce costly IEEE 802.1X authentication processes during handoff. Our approach is developed for alignment with IEEE 802.11s and 802.11i, keeping protocols at the station side operable with no changes. As another strength, our design applies to generic multihop wireless networks. Both analytical and simulation modeling are conducted to evaluate our scheme as well. Performance results show that our approach reduces handoff delay by up to 268% or achieves comparable performance resulting from the counterpart IEEE 802.11i scheme with high likelihood of 70%-85% successful preauthentication. Moreover, our performance analysis suggests an optimal number of access points managed by one mesh portal in a network. Qualitative and quantitative discussions indicate that our approach is applicable in pragmatic settings.
Group-Based Authentication and Key Agreement
(2012-02-01)
Chen, Yu-Wen
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Wang, Jui-Tang
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Chi, Kuang-Hui
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Tseng, Chien-Chao
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資訊工程學系
This paper presents an authentication and key agreement protocol to streamline communication activities for a group of mobile stations (MSs) roaming from the same home network (HN) to a serving network (SN). In such a roaming scenario, conventional schemes require the SN to interact with the HN for authenticating respective MSs, at the cost of repeated message exchanges and communication delay. Instead, in our design, when the first MS of a group visits, the SN performs full authentication with the concerned HN and thereby obtains authentication information for the MS and other members. Thus when any other MS of the same group visits, the SN can authenticate locally without subsequent involvement of the HN, so as to simplify protocol operations. We will show that our scheme does not trade performance for security and robustness to the extent that security requirements are unduly weakened. Both qualitative and quantitative discussions indicate that our proposed scheme lends itself to pragmatic settings.