Fong-Hao Liu

Bio: Fong-Hao Liu is an academic researcher from National Defense University. The author has contributed to research in topics: Handover & Wireless network. The author has an hindex of 2, co-authored 2 publications receiving 15 citations.

An efficient pre-scanning scheme for handoff in Cooperative Vehicular Networks

Abstract: In Wireless Access in Vehicular Environments (WAVE), the terminal devices are usually highly mobile vehicles or transportation tools, which handoff much more frequently than those in wireless networks However, the quality of network services, like VoIP and multimedia streaming, will be seriously influenced by too frequent handoff or too long handoff latency As a result, traditional handoff mechanisms no longer satisfy the need of vehicular communications At present, most existing fast handoff mechanisms are based on the signal strength of the APs, which does not suit vehicular communications fully Generally speaking, the regional traffic in Vehicular Ad-hoc Networks (VANETs) keep changing and varying For example, on busy roads or in rush hours, the increase of number of vehicles may lead to the network congestion and degrade the performance of vehicular communications substantially Therefore, this paper presents the QualityScan scheme, an efficient pre-scanning method to improve the handoff performance in VANETs With the attempt to reduce the handoff latency and maintain the load balance among the APs, our proposed scheme regularly collects the loading states of the nodes by the pre-established AP controller (APC), and predicts the network traffic of the next moment Consequently, Mobile Nodes (MNs) can select the most suitable AP for the best QoS according to the parameters received by passive scanning, while more QoS parameters should participate in cooperation The simulation result proves that our proposed scheme not only maintains the QoS and the load balance among the nodes, but also further enhances the handoff performance in VANETs

SeMIPv6: Secure and Efficient Roaming Mechanism Based on IEEE 802.11r and MIH

Abstract: The Mobile IPv6 (MIPv6) allows nodes to remain reachable while moving around in the IPv6 Environment. In order to protect the Mobile Node (MN) from being attacked by the forged Binding Updates from anywhere else in the Internet, the MIPv6 protocol presents a security mechanism between the mobile node and the corresponding node, Return Routability (RR), which can provide security authorization between them. However, the procedure is built on network layer, and it needs constant processing time to finish the handover. The IEEE 802.11r is based on MAC protocol of IEEE 802.11 standard, and it decreases the authorization time in the IEEE 802.11i by providing the fast handover. In this paper, we provide a new authorization mechanism, SeMIPv6, in MIPv6 integrating IEEE 802.11r and MIH, which not only enhances the handover security between the nodes, but also decreases the handover delay during the roaming.

Fundamentals of Queueing Theory

Abstract: Praise for the Third Edition: "This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented."IIE Transactions on Operations EngineeringThoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than presenting a narrow focus on the subject, this update illustrates the wide-reaching, fundamental concepts in queueing theory and its applications to diverse areas such as computer science, engineering, business, and operations research.This update takes a numerical approach to understanding and making probable estimations relating to queues, with a comprehensive outline of simple and more advanced queueing models. Newly featured topics of the Fourth Edition include:Retrial queuesApproximations for queueing networksNumerical inversion of transformsDetermining the appropriate number of servers to balance quality and cost of serviceEach chapter provides a self-contained presentation of key concepts and formulae, allowing readers to work with each section independently, while a summary table at the end of the book outlines the types of queues that have been discussed and their results. In addition, two new appendices have been added, discussing transforms and generating functions as well as the fundamentals of differential and difference equations. New examples are now included along with problems that incorporate QtsPlus software, which is freely available via the book's related Web site.With its accessible style and wealth of real-world examples, Fundamentals of Queueing Theory, Fourth Edition is an ideal book for courses on queueing theory at the upper-undergraduate and graduate levels. It is also a valuable resource for researchers and practitioners who analyze congestion in the fields of telecommunications, transportation, aviation, and management science.

SPAM: A Secure Password Authentication Mechanism for Seamless Handover in Proxy Mobile IPv6 Networks

Abstract: The Internet Engineering Task Force NETLMM Working Group recently proposed a network-based localized mobility management protocol called Proxy Mobile IPv6 (PMIPv6) to support mobility management without the participation of mobile nodes in any mobility-related signaling. Although PMIPv6 reduces the signaling overhead and the handover latency, it still suffers from packet loss problem and long authentication latency during handoff. In addition, there are many security threats to PMIPv6. In this paper, we perform a bicasting scheme for avoiding the packet loss problem, use the piggyback technique to reduce the signaling overhead, and provide a secure password authentication mechanism (SPAM) for protecting a valid user from attacks in PMIPv6 networks. SPAM provides high security properties, including anonymity, stolen-verified attack resistance, location privacy, mutual authentication, forgery attack resistance, no clock synchronization problem, modification attack resistance, replay attack resistance, fast error detection, choose and change password free, and session key agreement. Moreover, SPAM is an efficient authentication scheme that performs the authentication procedure locally and has low computational cost. From the analysis, we demonstrate that our scheme can resist various attacks and provides better performance than existing schemes.

Roadside Unit Caching: Auction-Based Storage Allocation for Multiple Content Providers

Abstract: Recent improvements in vehicular ad hoc networks are accelerating the realization of intelligent transportation system (ITS), which not only provides road safety and driving efficiency, but also enables infotainment services. Since data dissemination plays an important part in ITS, recent studies have found caching as a promising way to promote the efficiency of data dissemination against rapid variation of network topology. In this paper, we focus on the scenario of roadside unit (RSU) caching, where multiple content providers (CPs) aim to improve the data dissemination of their own contents by utilizing the storages of RSUs. To deal with the competition among multiple CPs for limited caching facilities, we propose a multi-object auction-based solution, which is sub-optimal and efficient to be carried out. A caching-specific handoff decision mechanism is also adopted to take advantages of the overlap of RSUs. Simulation results show that our solution leads to a satisfactory outcome.

Design of a Fast Location-Based Handoff Scheme for IEEE 802.11 Vehicular Networks

Abstract: IEEE 802.11 is an economical and efficient standard that has been applied to vehicular networks. However, the long handoff latency of the standard handoff scheme for IEEE 802.11 has become an important issue for seamless roaming in vehicular environments, because more handoffs may be triggered due to the higher mobility of vehicles. This paper presents a new and fast location-based handoff scheme particularly designed for vehicular environments. With the position and movement direction of a vehicle and the location information of the surrounding access points (APs), our protocol is able to accurately predict several APs that the vehicle may possibly visit in the future and to assign these APs different priority levels. APs on higher priority levels will be scanned first. A blacklist scheme is also used to exclude those APs that showed no response to the scanning during previous handoffs. Thus, time spent on scanning APs is supposed to be significantly reduced. The simulation results show that the proposed scheme attains not only a lower prediction error rate but also lower link layer handoff latency and that it has a smaller influence on jitter and throughput. Moreover, these results show that the proposed scheme has a smaller total number of handoffs than other handoff schemes.