Xuemin (Sherman) Shen

University of Waterloo, Ватерлоо, Ontario, Canada

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Publications (214)173.34 Total impact

  • Source
    Ning Lu, Nan Cheng, Ning Zhang, Xuemin (Sherman) Shen, Jon W. Mark, Fan Bai
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    ABSTRACT: In this paper, we investigate the cost-effectiveness of Wi-Fi solution for vehicular Internet access. We define the cost-effectiveness as the cost saving by deploying and operating a low-cost Wi-Fi infrastructure instead of a costly benchmark cellular network. To characterize the service quality of Wi-Fi deployment, we also define the normalized service delay which is the service time to fulfill a data application via the Wi-Fi network normalized by that via the cellular network. To derive the service time, we analyze the average throughput capacity of a generic vehicle in the Wi-Fi network and the average downlink capacity in the cellular network. Especially, we propose deploying Wi-Fi access point at signalized intersection and study the fundamental influence of traffic signals (which yield an interrupted vehicle traffic) on Wi-Fi access. Then, we examine the tradeoff between cost-effectiveness and normalized service delay by identifying interplays between controllable (e.g., the density of Wi-Fi deployment and user's satisfaction) and uncontrollable parameters (e.g., vehicle traffic statistics). Our results are very useful for network operators to make strategic planning of Wi-Fi deployment for vehicular Internet Access.
    IEEE Transactions on Vehicular Technology 06/2015; DOI:10.1109/TVT.2015.2443808 · 2.64 Impact Factor
  • Xiaoxia Zhang, Xuemin Sherman Shen, Liang-Liang Xie
    IEEE Transactions on Vehicular Technology 01/2015; DOI:10.1109/TVT.2015.2416714 · 2.64 Impact Factor
  • Sandra Céspedes, Xuemin (Sherman) Shen
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    ABSTRACT: The supporting infrastructure and communications technologies for vehicular networking contexts are heterogeneous by nature. Large coverage access networks, such as 3G/4G, coexist with wireless local area networks and dedicated short-range communications. In such a scenario, we investigate the seamless provision of mobile Internet access and general IP services over the heterogeneous network, in particular for loosely coupling architectures. We propose a hybrid global mobility scheme that allows for the ongoing IP sessions to be transferred across dissimilar radio access networks that may belong to different administrative domains. In order to achieve the global mobility, our scheme combines host- and network-based mobility. The solution focuses on urban vehicular scenarios and enables seamless communications for in-vehicle networks, passengers with mobile devices, and users of public transportation commuting along the system. By means of analytical evaluations and simulations of realistic urban vehicular scenarios, we show that our hybrid scheme can achieve seamless IP communications for mobile Internet access over the heterogeneous vehicular network.
    IEEE Transactions on Intelligent Transportation Systems 01/2015; DOI:10.1109/TITS.2015.2442251 · 2.47 Impact Factor
  • IEEE Transactions on Intelligent Transportation Systems 01/2015; DOI:10.1109/TITS.2015.2416257 · 2.47 Impact Factor
  • Jian Qiao, Xuemin (Sherman) Shen, Jon W. Mark, Qinghua Shen, Yejun He, Lei Lei
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    ABSTRACT: Millimeter-wave communication is a promising technology for future 5G cellular networks to provide very high data rate (multi-gigabits-per-second) for mobile devices. Enabling D2D communications over directional mmWave networks is of critical importance to efficiently use the large bandwidth to increase network capacity. In this article, the propagation features of mmWave communication and the associated impacts on 5G cellular networks are discussed. We introduce an mmWave+4G system architecture with TDMA-based MAC structure as a candidate for 5G cellular networks. We propose an effective resource sharing scheme by allowing non-interfering D2D links to operate concurrently. We also discuss neighbor discovery for frequent handoffs in 5G cellular networks.
    IEEE Communications Magazine 01/2015; 53(1):209-215. DOI:10.1109/MCOM.2015.7010536 · 4.46 Impact Factor
  • Amila Tharaperiya Gamage, Hao Liang, Ran Zhang, Xuemin (Sherman) Shen
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    ABSTRACT: To satisfy the ever increasing wireless service demand, it is effective to form a converged network by utilizing interworking mechanisms, such that the resources of heterogeneous wireless networks can be allocated in a coordinated and efficient manner. Despite the potential advantages of a converged network, its performance needs further improvement, especially at cell edges and rural areas where only one network is available. In this article, we investigate how to leverage device-to-device, D2D, communication to further improve the performance of a converged network which consists of an LTE-A cellular network and IEEE 802.11n WLANs. Three main technical challenges that complicate resource allocation are identified: allocation of resources capturing diverse radio access technologies of the networks, selection of users' communication modes for multiple networks to maximize hop and reuse gains, and interference management. To address these challenges, we propose a resource allocation scheme that performs mode selection, allocation of WLAN resources, and allocation of LTE-A network resources in three different timescales. The resource allocation scheme is semi-distributedly implemented in the underlying converged D2D communication network, and the achievable performance improvements are demonstrated via simulation results.
    IEEE Wireless Communications 12/2014; 21(6):98-107. DOI:10.1109/MWC.2014.7000977 · 6.52 Impact Factor
  • Source
    Lei Lei, Xuemin (Sherman) Shen, Mischa Dohler, Chuang Lin, Zhangdui Zhong
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    ABSTRACT: In this paper, we study the performance of mode selections in device-to-device (D2D) communications in terms of end-to-end average throughput, average delay, and dropping probability, considering dynamic data arrival with non-saturated buffers. We first introduce a general framework that includes three canonical routing modes, namely D2D mode, cellular mode, and hybrid mode, which can be combined with different resource allocation restrictions to represent the semi-static and dynamic selections of the three resource sharing modes. A queuing model is developed when the routing mode for every D2D connection is chosen, and an exact numerical analysis and an approximate decomposition and iteration approach are proposed. The performance measures are obtained from the decomposition approach and validated by means of simulation. We further introduce a mode selection scheme that adaptively chooses to semi-statically or dynamically select the resource sharing modes according to the estimated performance measures.
    IEEE Transactions on Wireless Communications 12/2014; 13(12):6697-6715. DOI:10.1109/TWC.2014.2335734 · 2.76 Impact Factor
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    ABSTRACT: This paper proposes a novel base station (BS) coordination approach for intercell interference mitigation in the orthogonal frequency-division multiple access based cellular networks. Specifically, we first propose a new performance metric for evaluating end user's quality of experience (QoE), which jointly considers spectrum efficiency, user fairness, and service satisfaction. Interference graph is applied here to capture and analyze the interactions between BSs. Then, a QoE-oriented resource allocation problem is formulated among BSs as a local cooperation game, where BSs are encouraged to cooperate with their peer nodes in the adjacent cells in user scheduling and power allocation. The existence of the joint-strategy Nash equilibrium (NE) has been proved, in which no BS player would unilaterally change its own strategy in user scheduling or power allocation. Furthermore, the NE in the formulated game is proved to lead to the global optimality of the network utility. Accordingly, we design an iterative searching algorithm to obtain the global optimum (i.e., the best NE) with an arbitrarily high probability in a decentralized manner, in which only local information exchange is needed. Theoretical analysis and simulation results both validate the convergence and optimality of the proposed algorithm with fairness improvement.
    IEEE Transactions on Wireless Communications 12/2014; 13(12):6928-6942. DOI:10.1109/TWC.2014.2334673 · 2.76 Impact Factor
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    ABSTRACT: Wireless Body Area Networks (WBANs), as a promising health-care system, can timely monitor human physiological parameters. Due to the limitation of communications, power, storage and computation in WBANs, a cloud assisted WBAN flourishes and provides more reliable, real-time, and intelligent health-care services for patients and mobile users. However, it is still critical to efficiently aggregate the different types of WBAN data to the cloud server. In addition, security and privacy concerns are also of paramount importance during the communications between WBAN and cloud. In this paper, we propose a priority based health data aggregation (PHDA) scheme with privacy preservation for cloud assisted WBANs to improve the aggregation efficiency among different types of health data. Specifically, we first explore social spots to help forward health data and enable users to select the optimal relay according to their social ties. According to different data priorities, the adjustable forwarding strategies can be selected to forward the user's health data to the cloud servers with the reasonable communication overheads. The security analysis demonstrates that the PHDA can achieve identity and data privacy preservation, and resist the forgery attacks. Finally, the performance evaluation shows that the PHDA achieves the desirable delivery ratio with reasonable communication costs and lower delay for the data in different priorities.
    Information Sciences 11/2014; 284:130-141. DOI:10.1016/j.ins.2014.06.011 · 3.89 Impact Factor
  • Khaled H. Almotairi, Xuemin Sherman Shen
    Wireless Communications and Mobile Computing 10/2014; 14(14):1365-1381. DOI:10.1002/wcm.2266 · 1.29 Impact Factor
  • Fangqin Liu, Tom H. Luan, Xuemin Sherman Shen, Chuang Lin
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    ABSTRACT: The packet loss burstiness over wireless channels is commonly acknowledged as a key impacting factor on the performance of networking protocols. An accurate evaluation of the packet loss burstiness, which reveals the characteristics and performance of the wireless channels, is crucial to the design of wireless systems and the quality-of-service provisioning to end users. In this paper, a simple yet accurate analytical framework is developed to dimension the packet loss burstiness over generic wireless channels. In specific, we first propose a novel and effective metric to characterize the packet loss burstiness, which is shown to be more compact, effective, and accurate than the metrics proposed in existing literature for the same purpose. With this metric, we then develop an analytical framework and derive the closed-form solutions of the packet loss performance, including the packet loss rate and the loss-burst/loss-gap length distributions. Lastly, as an example to show how the derived results can be applied to the design of wireless systems, we apply the analytical results to devise an adaptive packetization scheme. The proposed packetization scheme adaptively adjusts the packet length of transmissions based on the prediction of the packet loss rate and loss-burst/loss-gap lengths of the wireless channel. Via extensive simulations, we show that with the proposed packetization scheme, the channel throughput can be enhanced by more than 10% than the traditional scheme.Copyright © 2012 John Wiley & Sons, Ltd.
    Wireless Communications and Mobile Computing 08/2014; 14(12):1160-1175. DOI:10.1002/wcm.2262 · 1.29 Impact Factor
  • Source
    Rong Jiang, Rongxing Lu, Jun Luo, Chengzhe Lai, Xuemin Sherman Shen
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    ABSTRACT: In this paper, in order to simultaneously resolve the transmission security and availability in Supervisory Control And Data Acquisition (SCADA) group communications, we propose a robust and efficient group key management scheme, called LiSH+, which is characterized by developing a secure self-healing mechanism with t-revocation and collusion resistance capability. A dual direction hash chain is utilized to guarantee the backward secrecy and forward secrecy of group key. A novel self-healing mechanism is constructed to ensure availability of the group member in case of devices failure and prevent the collusive users from exploiting the group key in the proposed scheme. In addition, the compromised users can be revoked from the group dynamically by broadcasting message. Detailed security analysis shows that the proposed LiSH+ scheme meets the requirements of group communication and is secure in terms of t user collusion-free. Performance evaluation also demonstrates its efficiency in terms of low storage requirement and communication overheads. Copyright © 2014 John Wiley & Sons, Ltd.
    Security and Communication Networks 08/2014; 8(6):n/a-n/a. DOI:10.1002/sec.1057 · 0.72 Impact Factor
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    ABSTRACT: Carrier Aggregation is considered as a key revolution in Long Term Evolution-Advanced systems to meet the explosively increasing aspiration for high data rates. Unlike extensive simulative evaluations on CA in literature, current theoretical analysis on CA is not convincing due to lack of effective interference modeling. In this paper, we exploit the theory of stochastic geometry to provide tractable statistical interference modeling for downlink CA in LTE-A systems. Our objective is to demonstrate the benefits of CA by comparing the user performance between the legacy LTE users and LTE-A users. Specifically, we first model the distributions of base stations and users into Poisson Point Processes. Then, the user service probability and subchannel usage in each carrier are calculated for LTE and LTE-A users, respectively. The obtained probabilities are applied to derive the user SINR distribution and ergodic rates. To better clarify the impact of system/user parameters on the investigated performance, a special case is presented where the network is interference-limited and the channel fast fading is considered as Rayleigh fading. Finally, simulation results validate our analytical model and demonstrate that LTE-A users can achieve significantly better SINR and ergodic-rate performance than LTE users when the cell is not heavily loaded.
    ICC 2014 - 2014 IEEE International Conference on Communications; 06/2014
  • Hongwei Li, Rongxing Lu, Liang Zhou, Bo Yang, Xuemin (Sherman) Shen
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    ABSTRACT: Smart grid has emerged as the next generation of power grid, due to its reliability, flexibility, and efficiency. However, smart grid faces some critical security challenges such as the message injection attack and the replay attack. If these challenges cannot be properly addressed, an adversary can maliciously launch the injected or replayed message attacks to degrade the performance of smart grid. To cope with these challenging issues, in this paper, we propose an efficient authentication scheme that employs the Merkle hash tree technique to secure smart gird communication. Specifically, the proposed authentication scheme considers the smart meters with computation-constrained resources and puts the minimum computation overhead on them. Detailed security analysis indicates its security strength, namely, resilience to the replay attack, the message injection attack, the message analysis attack, and the message modification attack. In addition, extensive performance evaluation demonstrates its efficiency in terms of computation complexity and communication overhead.
    IEEE Systems Journal 06/2014; 8(2):655-663. DOI:10.1109/JSYST.2013.2271537 · 1.75 Impact Factor
  • Younghyun Kim, Haneul Ko, Sangheon Pack, Xuemin Sherman Shen
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    ABSTRACT: In this paper, we propose a vehicular passenger mobility-aware bandwidth allocation (V-MBA) scheme in mobile hotspots. The V-MBA scheme consists of both call admission control and bandwidth adjustment functions to lower handoff vehicle service dropping probability and efficiently utilize resource of base station. Specifically, a handoff priority scheme with guard bandwidth is employed to protect handoff vehicle service. Also, bandwidth is dynamically assigned to each vehicle by exploiting vehicular passenger movement pattern that includes getting on and off events at a station. We evaluate the V-MBA scheme by developing a continuous-time Markov chain model. Simulation results demonstrate that the V-MBA scheme can guarantee low new vehicle service blocking probability and handoff vehicle service dropping probability through flexible bandwidth allocation.
    IEEE Transactions on Wireless Communications 06/2014; 13(6):3281-3292. DOI:10.1109/TWC.2014.041714.131222 · 2.76 Impact Factor
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    ABSTRACT: This paper investigates energy efficient uplink communications for battery-constrained mobile terminals (MTs). We consider a heterogeneous wireless medium where MTs communicate with base stations (BSs) and access points (APs) of different networks with overlapped coverage. Unlike the existing research, we develop a joint bandwidth and power allocation framework that maximizes energy efficiency for a set of MTs, in different service areas, with best effort service and multi-homing capabilities. The problem formulation captures the heterogeneity of the medium, in terms of different service areas, channel conditions, available resources at BSs/APs of different networks, and different available maximum power at the MTs. In addition, the framework is implemented in a decentralized manner which is desirable in a case that different networks are operated by different service providers. Simulation results are presented to demonstrate the performance of the proposed framework.
    ICC 2014 - 2014 IEEE International Conference on Communications; 06/2014
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    ABSTRACT: In this paper, cooperative sensing for multi-channel cognitive radio networks (CRNs) is studied, whereby the secondary users (SUs) cooperate with each other to sense the multiple channels owned by the primary users (PUs). The objective is to better protect the primary system while satisfying the SUs' requirement on the expected access time. A general scenario is considered, where the channels present different usage characteristics and the detection performance of individual SUs varies due to the channel conditions between the PUs and SUs. With the dynamics in the channel usage characteristics and the detection capacities, each SU chooses one channel for sensing to minimize the interference to the PUs. The problem is formulated as a nonlinear integer programming problem which is NP-complete in general. To find the solution efficiently, the original problem is transformed into a variant of convex bipartite matching problem by constructing a complete bipartite graph and defining proper weight vectors. Based on the problem transformation, a channel assignment algorithm is proposed for computing in polynomial time the solution in terms of the number of SUs, the number of channels, and the maximum value of weights. Simulation results are presented to validate the performance of the proposed algorithm.
    ICC 2014 - 2014 IEEE International Conference on Communications; 06/2014
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    ABSTRACT: Millimeter wave (mmWave) communication is a promising technology to support high-rate (e.g., multi-Gbps) multimedia applications because of its large available bandwidth. Multipacket reception is one of the important capabilities of mmWave networks to capture a few packets simultaneously. This capability has the potential to improve medium access control layer performance. Because of the severe propagation loss in mmWave band, traditional backoff mechanisms in carrier sensing multiple access/collision avoidance (CSMA/CA) designed for narrowband systems can result not only in unfairness but also in significant throughput reduction. This paper proposes a novel backoff mechanism in CSMA/CA by giving a higher transmission probability to the node with a transmission failure than that with a transmission success, aiming to improve the system throughput. The transmission probability is adjusted by changing the contention window size according to the congestion status of each node and the whole network. The analysis demonstrates the effectiveness of the proposed backoff mechanism on reducing transmission collisions and increasing network throughput. Extensive simulations show that the proposed backoff mechanism can efficiently utilize network resources and significantly improve the network performance on system throughput and fairness. Copyright © 2014 John Wiley & Sons, Ltd.
    Wireless Communications and Mobile Computing 06/2014; DOI:10.1002/wcm.2492 · 1.29 Impact Factor
  • Kai Fan, Jie Li, Hui Li, Xiaohui Liang, Xuemin Sherman Shen, Yintang Yang
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    ABSTRACT: Radio frequency identification (RFID) has been regarded as one of the 10 important technologies in the 21st century. Because of its capability to rapidly and accurately collect and process data in real-time, RFID has been widely applied in many areas, such as Internet of Things and Smart Grid. However, the existing security threats become more severe toward RFID authentication scheme. The traditional security mechanisms cannot be used in RFID directly because of the limitations of processing capability, storage space, and power supply of RFID tags. In this paper, we propose a revocable secure efficient lightweight RFID authentication scheme (RSEL). To achieve authentication efficiency, the key of the tag is chosen to reduce the number of hash computing in the database. Furthermore, the key is stored in the database and updated constantly with the tag to prevent the tracking and synchronization attacks. The valid period of each tag is stored in the database so that RSEL can revoke the expired tag. The correctness of RSEL has been proved using GNY logic. The performance of RSEL in terms of security and efficiency is evaluated. Compared with other existing approaches, RSEL achieves stronger security and higher efficiency. Copyright © 2013 John Wiley & Sons, Ltd.
    Concurrency and Computation Practice and Experience 04/2014; 26(5):1084-1096. DOI:10.1002/cpe.3065 · 0.78 Impact Factor
  • Source
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    ABSTRACT: With the proliferation of smart grid research, the Advanced Metering Infrastructure (AMI) has become the first ubiquitous and fixed computing platform. However, due to the unique characteristics of AMI, such as complex network structure, resource-constrained smart meter, and privacy-sensitive data, it is an especially challenging issue to make AMI secure. Energy theft is one of the most important concerns related to the smart grid implementation. It is estimated that utility companies lose more than $25 billion every year due to energy theft around the world. To address this challenge, in this paper, we discuss the background of AMI and identify major security requirements that AMI should meet. Specifically, an attack tree based threat model is first presented to illustrate the energy-theft behaviors in AMI. Then, we summarize the current AMI energy-theft detection schemes into three categories, i.e., classification-based, state estimation-based, and game theory-based ones, and make extensive comparisons and discussions on them. In order to provide a deep understanding of security vulnerabilities and solutions in AMI and shed light on future research directions, we also explore some open challenges and potential solutions for energy-theft detection.
    Tsinghua Science & Technology 04/2014; 19(2):105-120. DOI:10.1109/TST.2014.6787363

Publication Stats

2k Citations
173.34 Total Impact Points


  • 2003–2015
    • University of Waterloo
      • Department of Electrical & Computer Engineering
      Ватерлоо, Ontario, Canada
  • 2011
    • McMaster University
      • Department of Electrical and Computer Engineering
      Hamilton, Ontario, Canada
  • 2010
    • Tohoku University
      • Graduate School of Information Sciences
      Miyagi, Japan
  • 2009
    • Northeastern University (Shenyang, China)
      • College of Information Science and Engineering
      Feng-t’ien, Liaoning, China
  • 2008
    • Dalian Maritime University
      Lü-ta-shih, Liaoning, China
  • 2007
    • University of Tsukuba
      Tsukuba, Ibaraki, Japan
    • Korea University
      • Department of Electrical Engineering
      Seoul, Seoul, South Korea
    • University of Victoria
      • Department of Electrical and Computer Engineering (ECE)
      Victoria, British Columbia, Canada
  • 2006
    • Microsoft
      Washington, West Virginia, United States