Publications (24)2.17 Total impact
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Article: Enabling Multi-Hop Concurrent Transmissions in 60 GHz Wireless Personal Area Networks.
IEEE Transactions on Wireless Communications. 01/2011; 10:3824-3833. -
Article: Resource management for video streaming in ad hoc networks.
Ad Hoc Networks. 01/2011; 9:623-634. -
Article: Bounds estimation and practical stability of AIMD/RED systems with time delays.
Computer Networks. 01/2010; 54:1069-1082. -
Article: Supporting voice and video applications over IEEE 802.11n WLANs.
Wireless Networks. 01/2009; 15:443-454. -
Conference Proceeding: Downlink Resource Allocation for OFDMA-Based Multiservice Networks with Imperfect CSI.
Proceedings of IEEE International Conference on Communications, ICC 2009, Dresden, Germany, 14-18 June 2009; 01/2009 -
Article: Resource Management and QoS Provisioning for IPTV over mmWave-based WPANs with Directional Antenna.
MONET. 01/2009; 14:210-219. -
Article: Air interface switching and performance analysis for fast vertical handoff in cellular network and WLAN interworking
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ABSTRACT: The integration of wireless local area network (WLAN) hotspot and the 3G cellular networks is imminently the future mode of public access networks. One of the key elements for the successful integration is vertical handoff between the two heterogeneous networks. Service disruption may occur during the vertical handoff because of the IP layer handoff activities, such as registration, binding update, routing table update, etc. In this paper, the network interface switching and registration process are proposed for the integrated WLAN/cellular network. Two types of fast vertical handoff protocols based on bicasting and non-bicasting supporting real-time traffic, such as voice over IP, are modeled. The performance of a bicasting based handoff scheme is analyzed and compared with that of fast handoff without bicasting. Numerical results and the simulation are given to show that packet loss rate can be reduced by the bicasting during handoff scheme without increasing bandwidth on both wireless interfaces. Copyright © 2006 John Wiley & Sons, Ltd.Wireless Communications and Mobile Computing 05/2007; 7(5):581 - 594. · 0.88 Impact Factor -
Article: Mobile location estimation for DS‐CDMA systems using self‐organizing maps
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ABSTRACT: In this paper, a self-organizing map (SOM) scheme for mobile location estimation in a direct-sequence code division multiple access (DS-CDMA) system is proposed. As a feedforward neural network with unsupervised or supervised and competitive learning algorithm, the proposed scheme generates a number of virtual neurons over the area covered by the corresponding base stations (BSs) and performs non-linear mapping between the measured pilot signal strengths from nearby BSs and the user's location. After the training is finished, the location estimation procedure searches for the virtual sensor which has the minimum distance in the signal space with the estimated mobile user. Analytical results on accuracy and measurement reliability show that the proposed scheme has the advantages of robustness and scalability, and is easy for training and implementation. In addition, the scheme exhibits superior performance in the non-line-of-sight (NLOS) situation. Numerical results under various terrestrial environments are presented to demonstrate the feasibility of the proposed SOM scheme. Copyright © 2006 John Wiley & Sons, Ltd.Wireless Communications and Mobile Computing 02/2007; 7(3):285 - 298. · 0.88 Impact Factor -
Chapter: AAA Architecture and Authentication for Wireless Lan roaming
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ABSTRACT: A wireless LAN service integration architecture based on current wireless LAN hotspots is proposed to make migrating to new service cost effective. The AAA (Authentication, Authorization and Accounting) based mobile terminal registration signaling process is discussed. An application layer end-to-end authentication and key negotiation protocol is proposed to overcome the open air connection problem existing in wireless LAN deployment. The protocol provides a general solution for Internet applications running on a mobile station under various authentication scenarios and keeps the communications private to other wireless LAN users and foreign networks. A functional demonstration of the protocol is also given. The research results should contribute to rapid deployment of wireless LANs hotspot service.12/2006: pages 273-294; -
Chapter: Promoting Identity-Based Key Management in Wireless Ad Hoc Networks
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ABSTRACT: In wireless ad hoc networks, mobile peers communicate with other peers over wireless links, without the support of preexisting infrastructures, which is an attractive form of peer communications for certain applications. Although many enabling technologies have progressed significantly in recent years, the highly-anticipated deployment of large-scale, heterogeneous wireless ad hoc networks still faces considerable technical challenges, among which achieving secure, trustworthy and dependable peer communications is a major one. In this chapter, we promote identity-based key management, which serves as a prerequisite for various security procedures. We first identify that peer identity plays an irreplaceable role in wireless ad hoc networks, where autonomous peers can join or leave such systems and change their location in these systems at any time. Next, we show that identity-based key management schemes are effective and efficient for bootstrapping any chosen security procedures, especially in wireless ad hoc networks where both over-the-air communication and on-board computing resources can be severely constrained. Finally, we illustrate identity-based secure communication schemes with a security enhancement to the Dynamic Source Routing protocol. We find that identity-based schemes are intrinsically suitable for and practically capable of securing wireless ad hoc networks and may have great impact on dealing with other network security issues.12/2006: pages 83-102; -
Article: VoIP over WLAN: voice capacity, admission control, QoS, and MAC
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ABSTRACT: Voice over Internet Protocol (VoIP) is one of the fastest growing Internet applications. It is a viable alternative to the traditional telephony systems due to its high resource utilization and cost efficiency. Meanwhile, Wireless Local Area Networks (WLANs) have become a ubiquitous networking technology that has been deployed around the world. Driven by these two popular technologies, Voice over WLAN (VoWLAN) has been emerging as an infrastructure to provide low-cost wireless voice services. However, VoWLAN poses significant challenges since the performance characteristics of wireless networks are much worse than that of their wireline counterparts, and the IEEE 802.11-based WLAN was not originally designed to support delay-sensitive voice traffic. In this paper, we provide a survey of recent advances in VoWLAN voice capacity analysis, call admission schemes, and medium access control (MAC) layer quality of service (QoS) enhancement mechanisms. Some open research issues are presented for further investigation. Copyright © 2006 John Wiley & Sons, Ltd.International Journal of Communication Systems 04/2006; 19(4):491 - 508. · 0.41 Impact Factor -
Article: Improving TCP Performance over Wireless Ad Hoc Networks with Busy Tone Assisted Scheme.
EURASIP J. Wireless Comm. and Networking. 01/2006; 2006. -
Article: Power Allocation and Scheduling for MAC Layer Design in UWB Networks
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ABSTRACT: This paper proposes a practical joint power allocation and scheduling scheme for medium access control (MAC) layer design in ultra-wideband (UWB) networks. The scheme increases system spectral efficiency and reduces power consumption by fully considering the properties of the UWB, such as its capacity in supporting parallel transmission and providing accurate positioning, and its stringent constraint on computational complexity. Practical implementations of the proposed scheme is achieved by introducing a margin based power allocation scheme and an exclusive region based scheduling scheme. The margin based power allocation scheme is carried out based on each link?s own information, and is simple to implement, while the exclusive region based scheduling scheme takes into account the interaction among different links. Simulation results show that the proposed power allocation and scheduling schemes exhibit good performance in terms of the average number of slots per frame and the power consumption reduction.Quality of Service in Heterogeneous Wired/Wireless Networks, International Conference on. 08/2005; -
Article: QoS Support for Multimedia Traffic
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ABSTRACT: In this paper, we study how to select the transport layer protocol parameters with considerations of wireless link characteristics and application QoS requirements. In our approach, the inter-layer interactions only exchange protocol parameters between layers. We demonstrate that by appropriately selecting the AIMD protocol parameters, AIMD-controlled flows can efficiently utilize wireless resources and provide satisfactory QoS to time-sensitive multimedia applications. Extensive simulations are performed to validate the analytical results, evaluate the performance, and show that AIMD protocols can outperform the non-responsive UDP protocol when they are used to support multimedia applications over hybrid networks. Since AIMD and TCP protocols share the same congestion control mechanism, AIMD protocols are compatible with the legacy and scalable to be deployed incrementally. In addition, with satisfactory QoS provisioning, end-systems have more incentives to voluntarily regulate multimedia traffic with an AIMD-based congestion controller, which is vital for network stability and integrity.06/2004; -
Article: Performance Analysis of AIMD-Controlled
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ABSTRACT: In this paper, we develop a novel analytical framework for quantifying the performance of Additive Increase and Multiplicative Decrease (AIMD) flows in hybrid wireless/IP networks. By using token emulation, we obtain the queuing delay distribution, the probability of delay jitter exceeding a threshold, and the packet loss rate of AIMD-controlled multimedia flows, which is a function of the wireless link throughput distribution visible to the transport layer. The wireless link throughput is a function of the wireless link characteristics and the link layer protocol. As an illustration, the specific cases of a Rayleigh fading wireless link with link layer persistent and optimal packet transmission schemes are considered, respectively. Our QoS performance analysis matches well with simulation results, and can offer insights for tuning AIMD protocol parameters to efficiently utilize network resources and to effectively guarantee QoS for time-sensitive multimedia applications over hybrid networks.06/2004; -
Article: Admission control and concurrent scheduling for IPTV over mmWave-based WPANs
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ABSTRACT: Communications at 60 GHz millimeter-wave (mmWave) band is a promising technology for future wireless personal area networks (WPAN) supporting high data rate applications. Internet Protocol TV (IPTV) is anticipated to be one of the next killer applications, which requires high data rate and stringent quality of services (QoS) in terms of delay and loss. In this paper, we propose how to efficiently support IPTV flows in a mmWave-based WPAN with QoS guarantee, considering the characteristics of both the IPTV traffic and the mmWave communication technology. We first quantify the effective bandwidth of IPTV video sources using a simple, two-level Markov traffic model. By considering the overheads of the protocol stack in mmWave WPANs, we then quantify the minimal channel time needed for each IPTV flow. Since mmWave-based WPANs will deploy directional antennae to not only extend the transmission range, but also achieve higher spatial multiplexing gain, we further propose an admission control scheme and scheduling algorithm which take advantage of concurrent transmissions. Extensive simulations with NS-2 using real video traces have validated our analysis and demonstrate the efficiency and effectiveness of the proposed schemes, which will be an enabling technology for future mmWave-based WPANs supporting IPTV services. -
Article: Capacity of UWB networks supporting multimedia services
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ABSTRACT: We analyze the capacity of UWB networks supporting multimedia services by calculating the number of multimedia connections that can be supported in a UWB network based on IEEE 802.15.3 Medium Access Control (MAC) protocol, taking into consideration the overheads from different layers. We then propose how to increase the capacity by improving the MAC protocol design. To fully explore the potential of UWB technologies which favor concurrent transmissions if the interference is appropriately controlled, we study the capacity of cellular-like UWB networks. Our findings, which should provide important guidelines for UWB network planning, are a) the inter-cell interference of UWB networks is closely related to the Riemann Zeta function, and to guarantee the bounded inter-cell interference of UWB networks, the path loss exponent α must be larger than 2; b) the total throughput in an area is a concave function of the cell size; c) the best distance between adjacent cells is a function of path loss exponent, background noise level, and cross-correlation of the target signal and the interfering signal; and d) with the optimal cell size, a single flow's throughput is reduced by 2/α due to inter-cell interference. Simulation results are given to demonstrate the accuracy of the analysis. -
Article: User authentication and undeniable billing support for agent-based roaming service in WLAN/cellular integrated mobile networks
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ABSTRACT: In this paper, a framework of authentication and undeniable billing support for an agent-based roaming service in WLAN/cellular networks interworking networks is proposed. This framework circumvents the requirement of peer-to-peer roaming agreements to provide seamless roaming service between WLAN hotspots and cellular networks operated by independent wireless network service providers. Within the framework, an adaptive authentication and an event-tracking scheme have been developed, which allow the application of undeniable billing service to cellular network even when it still uses a traditional authentication scheme. The proposed modified dual directional hash chain (MDDHC) based billing support mechanism features mutual non-repudiation. Security analysis and overhead evaluation demonstrate that the proposed framework is secure and efficient.Computer Networks. -
Article: Identity-based secure collaboration in wireless ad hoc networks
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ABSTRACT: Voluntary peer collaboration is often assumed in media access, route discovery, packet forwarding, and upper-layer protocols designed for wireless ad hoc networks. This assumption has been seriously challenged when peers are autonomous, selfish, or malicious in large-scale, heterogeneous networks. In this paper, based on the latest advances in identity-based cryptography, we design a lightweight and cheat-resistant micropayment scheme to stimulate and compensate collaborative peers that sacrifice their resources to relay packets for other peers. We also demonstrate that when security and collaboration measures are properly enforced, profitable collaboration is a preferable strategy for all peers in ad hoc networks.Computer Networks. -
Article: An adaptive handoff priority scheme for wireless MC-CDMA cellular networks supporting realtime multimedia applications
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ABSTRACT: An adaptive handoff priority scheme is proposed for a packet switching multicode (MC)-CDMA cellular network supporting realtime multimedia applications. The scheme jointly considers the physical, link and network layer characteristics, and gives service priority to handoff calls by exploiting the transmission rate adaptability of multimedia calls to the available radio resources. Based on the scheme, a call admission region is derived with the estimated cell capacity and the proposed packet scheduling and partial packet integration scheme and used for call admission control and handoff management with the satisfaction of quality of service requirements for all multimedia traffic, where the QoS parameters include the wireless transmission bit error rate, packet loss rate and delay requirement. Simulation results are given to demonstrate the viability of the proposed scheme.Computer Communications.
Top co-authors
Top Journals
Institutions
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2005–2006
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University of Waterloo
- Department of Electrical & Computer Engineering
Waterloo, Ontario, Canada
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