Wenjing Lou

Illinois Institute of Technology, Chicago, Illinois, United States

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Publications (131)76.47 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: The dominant spectrum sharing paradigm of today is the interweave paradigm. This paper advocates a new and alternative paradigm called United network of Primary and Secondary networks (UPS). UPS allows a complete cooperation between primary and secondary networks at the node level to relay each other's traffic, in addition to existing dynamic spectrum access (DSA) in time, space, and frequency domains. Such cooperation allows the primary and secondary networks to access a much richer network resources from the combined network. As a case study, we consider a problem with the goal of supporting the rate requirement of the primary network traffic while maximizing the minimum throughput of the secondary sessions. For this problem, we develop an optimization model and formulate a combinatorial optimization problem. Although this problem is in the form of mixed integer linear program (MILP), we can use CPLEX to solve it efficiently. Simulation results show that the UPS paradigm offers much better throughput performance than the interweave DSA paradigm.
    Mobile Ad-Hoc and Sensor Systems (MASS), 2013 IEEE 10th International Conference on; 01/2013
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    ABSTRACT: Personal health record (PHR) is an emerging patient-centric model of health information exchange, which is often outsourced to be stored at a third party, such as cloud providers. However, there have been wide privacy concerns as personal health information could be exposed to those third party servers and to unauthorized parties. To assure the patients' control over access to their own PHRs, it is a promising method to encrypt the PHRs before outsourcing. Yet, issues such as risks of privacy exposure, scalability in key management, flexible access, and efficient user revocation, have remained the most important challenges toward achieving fine-grained, cryptographically enforced data access control. In this paper, we propose a novel patient-centric framework and a suite of mechanisms for data access control to PHRs stored in semitrusted servers. To achieve fine-grained and scalable data access control for PHRs, we leverage attribute-based encryption (ABE) techniques to encrypt each patient's PHR file. Different from previous works in secure data outsourcing, we focus on the multiple data owner scenario, and divide the users in the PHR system into multiple security domains that greatly reduces the key management complexity for owners and users. A high degree of patient privacy is guaranteed simultaneously by exploiting multiauthority ABE. Our scheme also enables dynamic modification of access policies or file attributes, supports efficient on-demand user/attribute revocation and break-glass access under emergency scenarios. Extensive analytical and experimental results are presented which show the security, scalability, and efficiency of our proposed scheme.
    IEEE Transactions on Parallel and Distributed Systems 01/2013; 24(1):131-143. · 1.80 Impact Factor
  • Lu Shi, Shucheng Yu, Wenjing Lou, Y.T. Hou
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    ABSTRACT: Lacking trusted central authority, distributed systems have received serious security threats from Sybil attack, where an adversary forges identities of more than one node and attempts to control the system. By utilizing the real-world trust relationships between users, social network-based defense schemes have been proposed to mitigate the impact of Sybil attacks. These solutions are mostly built on the assumption that the social network graph can be partitioned into two loosely linked regions - a tightly connected non-Sybil region and a Sybil region. Although such an assumption may hold in certain settings, studies have shown that the real-world social connections tend to divide users into multiple inter-connected small worlds instead of a single uniformly connected large region. Given this fact, the applicability of existing schemes would be greatly undermined for inability to distinguish Sybil users from valid ones in the small non-Sybil regions. This paper addresses this problem and presents SybilShield, the first protocol that defends against Sybil attack utilizing multi-community social network structure in real world. Our scheme leverages the sociological property that the number of cutting edges between a non-Sybil community and a Sybil community, which represent human-established trust relationships, is much smaller than that among non-Sybil communities. With the help of agent nodes, SybilShield greatly reduces false positive rate of non-Sybils among multiple communities, while effectively identifying Sybil nodes. Analytical results prove the superiority of SybilShield. Our experiments on a real-world social network graph with 100,000 nodes also validate the effectiveness of SybilShield.
    INFOCOM, 2013 Proceedings IEEE; 01/2013
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    ABSTRACT: Interference alignment (IA) is a major advance in information theory. Despite its rapid advance in the information theory community, most results on IA remain point-to-point or single-hop and there is a lack of advance of IA in the context of multi-hop wireless networks. The goal of this paper is to make a concrete step toward advancing IA technique in multi-hop MIMO networks. We present an IA model consisting of a set of constraints at a transmitter and a receiver that can be used to determine a subset of interfering streams for IA. Based on this IA model, we develop an IA optimization framework for a multihop MIMO network. For performance evaluation, we compare the performance of a network throughput optimization problem under our proposed IA framework and the same problem when IA is not employed. Simulation results show that the use of IA can significantly decrease the DoF consumption for IC, thereby improving network throughput.
    INFOCOM, 2013 Proceedings IEEE; 01/2013
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    ABSTRACT: Cloud computing is envisioned as the next generation architecture of IT enterprises, providing convenient remote access to massively scalable data storage and application services. While this outsourced storage and computing paradigm can potentially bring great economical savings for data owners and users, its benefits may not be fully realized due to wide concerns of data owners that their private data may be involuntarily exposed or handled by cloud providers. Although end-to-end encryption techniques have been proposed as promising solutions for secure cloud data storage, a primary challenge toward building a full-fledged cloud data service remains: how to effectively support flexible data utilization services such as search over the data in a privacy-preserving manner. In this article, we identify the system requirements and challenges toward achieving privacy-assured searchable outsourced cloud data services, especially, how to design usable and practically efficient search schemes for encrypted cloud storage. We present a general methodology for this using searchable encryption techniques, which allows encrypted data to be searched by users without leaking information about the data itself and users¿ queries. In particular, we discuss three desirable functionalities of usable search operations: supporting result ranking, similarity search, and search over structured data. For each of them, we describe approaches to design efficient privacy-assured searchable encryption schemes, which are based on several recent symmetric-key encryption primitives. We analyze their advantages and limitations, and outline the future challenges that need to be solved to make such secure searchable cloud data service a reality.
    IEEE Network 01/2013; 27(4):56-62. · 2.85 Impact Factor
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    ABSTRACT: There has been a growing interest to employ the so-called degree-of-freedom (DoF) based models to study multihop MIMO networks. Existing DoF-based models differ in their interference cancelation (IC) behavior and suffer from either loss of solution space or possible infeasible solutions. Recently, a DoF model based on a novel node-ordering concept was proposed to overcome the limitations of the exiting DoF models. In this paper, we apply this new DoF model to study a throughput maximization problem in a multi-hop network. The problem formulation jointly considers half duplex, node ordering, DoF consumption constraints and flow routing and is in the form of a mixed integer linear program (MILP). Our main contribution is the development of an efficient polynomial time algorithm that offers a competitive solution to the MILP through a series of linear programs (LPs). The key idea in the algorithm is to explore (i) the impact of node ordering on DoF consumption for IC at a node, and (ii) route diversity in the network while ensuring DoF constraints are satisfied at each node throughout the iterations. Simulation results show that our solutions by the proposed algorithm are competitive and feasible.
    Mobile Ad-Hoc and Sensor Systems (MASS), 2013 IEEE 10th International Conference on; 01/2013
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    ABSTRACT: Wireless energy transfer is a promising technology to fundamentally address energy and lifetime problems in a wireless sensor network (WSN). On the other hand, it has been well recognized that a mobile base station has significant advantages over a static one. In this paper, we study the interesting problem of co-locating the mobile base station on the wireless charging vehicle (WCV). The goal is to minimize energy consumption of the entire system while ensuring none of the sensor nodes runs out of energy. We develop a mathematical model for this complex problem. Instead of studying the general problem formulation (OPT-t), which is time-dependent, we show that it is sufficient to study a special subproblem (OPT-s) which only involves space-dependent variables. Subsequently, we develop a provably near-optimal solution to OPT-s. The novelty of this research mainly resides in the development of several solution techniques to tackle a complex problem that is seemingly intractable at first glance. In addition to addressing a challenging and interesting problem in a WSN, we expect the techniques developed in this research can be applied to address other related networking problems involving time-dependent movement, flow routing, and energy consumption.
    INFOCOM, 2013 Proceedings IEEE; 01/2013
  • Liang Xiao, Qiben Yan, Wenjing Lou, Y.T. Hou
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    ABSTRACT: In this paper, we propose a privacy-preserving proximity-based security strategy for location-based services in wireless networks, without requiring any pre-shared secret, trusted authority or public key infrastructure. More specifically, radio clients build their location tags according to the unique physical features of their ambient radio signals, which cannot be forged by attackers outside the proximity range. The proximity-based authentication and session key generation is based on the public location tag, which incorporates the received signal strength indicator (RSSI), sequence number and MAC address of the ambient radio packets. Meanwhile, as the basis for the session key generation, the secret location tag consisting of the arrival time interval of the ambient packets, is never broadcast, making it robust against eavesdroppers and spoofers. The proximity test utilizes the nonparametric Bayesian method called infinite Gaussian mixture model, and provides range control by selecting different features of various ambient radio sources. The authentication accuracy and key generation rate are evaluated via experiments using laptops in typical indoor environments.
    Communications (ICC), 2013 IEEE International Conference on; 01/2013
  • Huacheng Zeng, Yi Shi, Y.T. Hou, Wenjing Lou
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    ABSTRACT: Degree-of-Freedom (DoF)-based model is a simple yet powerful tool to analyze MIMO's spatial multiplexing (SM) and interference cancellation (IC) capabilities in a multi-hop network. Recently, a new DoF model was proposed and was shown to achieve the same rate region as the matrix-based model (under SM and IC). The essence of this new DoF model is a novel node ordering concept, which eliminates potential duplication of DoF allocation for IC. In this paper, we investigate DoF scheduling for a multi-hop MIMO network based on this new DoF model. Specifically, we study how to perform DoF allocation among the nodes for SM and IC so as to maximize the minimum rate among a set of sessions. We formulate this problem as a mixed integer linear programming (MILP) and develop an efficient DoF scheduling algorithm to solve it. We show that our algorithm is amenable to local implementation and has polynomial time complexity. More importantly, it guarantees the feasibility of final solution (upon algorithm termination), despite that node ordering establishment and adjustment are performed locally. Simulation results show that our algorithm can offer a result that is close to an upper bound found by CPLEX solver, thus showing that the result found by our algorithm is highly competitive.
    INFOCOM, 2013 Proceedings IEEE; 01/2013
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    ABSTRACT: This paper explores the so-called “transparent coexistence” paradigm for spectrum sharing between primary and secondary nodes in a multi-hop network environment. Although such paradigm has been studied in the information theory and communications communities, it is not well understood in the wireless networking community, particularly for multihop networks. Under this paradigm, a secondary network is allowed to use the same spectrum simultaneously with the primary network as long as their activities are “transparent” (or “invisible”) to the primary network. Such transparency can be accomplished through a systematic interference cancellation (IC) by the secondary nodes without any impact on the primary network. This paper offers an in-depth study of this paradigm in a multi-hop network environment and addresses issues such as channel selection, IC to/from primary network, and IC within the secondary network. Through a rigorous modeling and formulation, we develop an optimization problem under this paradigm with the objective of maximizing secondary user's throughput. Through simulation results, we show that such paradigm offers significant improvement to a multi-hop network in terms of spectrum efficiency and throughput performance as compared to the prevailing interference-avoidance paradigm.
    Sensor, Mesh and Ad Hoc Communications and Networks (SECON), 2013 10th Annual IEEE Communications Society Conference on; 01/2013
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    ABSTRACT: Passive monitoring by distributed wireless sniffers has been used to strategically capture the network traffic, as the basis of automatic network diagnosis. However, the traditional monitoring techniques fall short in cognitive radio networks (CRNs) due to the much larger number of channels to be monitored, and the secondary users' channel availability uncertainty imposed by primary user activities. To better serve CRNs, we propose a systematic passive monitoring framework for traffic collection using a limited number of sniffers in WiFi like CRNs. We jointly consider primary user activity and secondary user channel access pattern to optimize the traffic capturing strategy. In particular, we exploit a non-parametric density estimation method to learn and predict secondary users' access pattern in an online fashion, which rapidly adapts to the users' dynamic behaviors and supports accurate estimation of merged access patterns from multiple users. We also design near-optimal monitoring algorithms that maximize two levels of quality-of-monitoring goals respectively, based on the predicted channel access patterns. The simulations and experiments show that our proposed framework outperforms the existing schemes significantly.
    INFOCOM, 2013 Proceedings IEEE; 01/2013
  • Ming Li, Shucheng Yu, Ning Cao, Wenjing Lou
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    ABSTRACT: Making new connections according to personal preferences is a crucial service in mobile social networking, where an initiating user can find matching users within physical proximity of him/her. In existing systems for such services, usually all the users directly publish their complete profiles for others to search. However, in many applications, the users' personal profiles may contain sensitive information that they do not want to make public. In this paper, we propose FindU, a set of privacy-preserving profile matching schemes for proximity-based mobile social networks. In FindU, an initiating user can find from a group of users the one whose profile best matches with his/her; to limit the risk of privacy exposure, only necessary and minimal information about the private attributes of the participating users is exchanged. Two increasing levels of user privacy are defined, with decreasing amounts of revealed profile information. Leveraging secure multi-party computation (SMC) techniques, we propose novel protocols that realize each of the user privacy levels, which can also be personalized by the users. We provide formal security proofs and performance evaluation on our schemes, and show their advantages in both security and efficiency over state-of-the-art schemes.
    IEEE Transactions on Wireless Communications 01/2013; 12(5):2024-2033. · 2.42 Impact Factor
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    ABSTRACT: The cost of energy consumption is an important concern for network operators. In this paper, we study an energy-related problem that focuses on network-wide energy consumption. In the first part of this work, we study how to maximize throughput under a network-wide energy constraint. We formulate this problem as a mixed-integer nonlinear program (MINLP). This formulation differs from prior efforts as it considers a non-zero device power, which complicates the problem. We propose a novel piece-wise linear approximation to transform the nonlinear constraints into linear constraints. We prove that the solution developed under this approach is near-optimal with a guaranteed performance bound. In the second part, we generalize the problem in the first part via a multicriteria optimization framework, which simultaneously optimizes throughput and total network energy. We show how weakly Pareto-optimal solutions can characterize an optimal throughput-energy curve. We offer some interesting properties of the optimal throughput-energy curves, which are useful to both network operators and end-users. Our results fill in some important gaps in the current understanding on optimizing total network energy.
    IEEE Transactions on Wireless Communications 01/2013; 12(3):1255-1267. · 2.42 Impact Factor
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    C. Wang, Q. Wang, K. Ren, W. Lou
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    ABSTRACT: As one of the emerging services in cloud paradigm, cloud storage enables users to remotely store their data into the cloud so as to enjoy the on-demand high quality applications and services from a shared pool of configurable computing resources. While cloud storage relieves users from the burden of local storage management and maintenance, it is also relinquishing users’ ultimate control over the fate of their data, which may put the correctness of outsourced data into risks. In order to regain the assurances of cloud data integrity and availability and enforce the quality of cloud storage service for users, we propose a highly efficient and flexible distributed storage verification scheme with two salient features, opposing to its predecessors. By utilizing the homomorphic token with distributed erasure-coded data, our scheme achieves the integration of storage correctness insurance and data error localization, i.e., the identification of misbehaving server(s). Unlike most prior works, the new scheme further supports secure and efficient dynamic operations on outsourced data, including: block modification, deletion and append. Extensive security and performance analysis shows the proposed scheme is highly efficient and resilient against Byzantine failure, malicious data modification attack, and even server colluding attacks.
    IEEE Transactions on Services Computing 01/2012; · 2.46 Impact Factor
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    ABSTRACT: Capacity scaling laws offer fundamental understanding on the trend of user throughput behavior when the network size increases. Since the seminal work of Gupta and Kumar, there have been active research efforts in developing capacity scaling laws for ad hoc networks under various advanced physical layer technologies. These efforts led to many custom-designed solutions, most of which were intellectually challenging and lacked universal properties that can be extended to address scaling laws of ad hoc networks with other physical layer technologies. In this paper, we present a set of simple yet powerful tool that can be applied to quickly determine the capacity scaling laws for various physical layer technologies under the protocol model. We prove the correctness of our proposed criteria and demonstrate their usage through a number of case studies, such as ad hoc networks with directional antenna, MIMO, multi-channel multi-radio, cognitive radio, and multiple packet reception. These simple criteria will serve as powerful tools to networking researchers to obtain throughput scaling laws of ad hoc networks under different physical layer technologies, particularly those to be developed in the future.
    Proceedings - IEEE INFOCOM 01/2012;
  • Ning Zhang, Ming Li, Wenjing Lou, Y.T. Hou
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    ABSTRACT: Multiple Level Security (MLS) has always been a center of focus since the usage of computers in military and intelligence systems. Extensive studies have been done on how to utilize virtualization technologies to provide multiple level secured execution in the cloud, yet the general assumption is that all components in the cloud service provider are trusted. With the advanced persistent threats currently faced by the military and intelligence community, it is unrealistic to assume complex information systems can remain trustworthy all the time. In this work, we present MUltiple level Security cloud with strong Hardware level Isolation (MUSHI), a novel framework that can provide hardware level isolation and protection to individual guest virtual machine (VM) execution. With MUSHI, a user can maintain confidentiality and integrity of her VM in a multicore environment even in the presence of malicious attacks from both within and outside the cloud infrastructure.
    MILITARY COMMUNICATIONS CONFERENCE, 2012 - MILCOM 2012; 01/2012
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    ABSTRACT: There is a growing interest in exploiting interference (rather than avoiding it) to increase network throughput. In particular, the so-called successive interference cancellation (SIC) scheme appears very promising, due to its ability to enable concurrent receptions from multiple transmitters as well as interference rejection. Although SIC has been extensively studied as a physical layer technology, its research and advances in the context of multi-hop wireless network remain limited. In this paper, we try to answer the following fundamental questions. What are the limitations of SIC? How to overcome such limitations? How to optimize the interaction between SIC and interference avoidance? How to incorporate multiple layers (physical, link, and network) in an optimization framework? We find that SIC alone is not adequate to handle interference in a multi-hop wireless network, and advocate the use of joint SIC and interference avoidance. To optimize a joint scheme, we propose a cross-layer optimization framework that incorporates variables at physical, link, and network layers. This is the first work that combines successive interference cancellation and interference avoidance in multi-hop wireless network. We use numerical results to affirm the validity of our optimization framework and give insights on how SIC and interference avoidance can complement each other in an optimal manner.
    Proceedings - IEEE INFOCOM 01/2012;
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    ABSTRACT: Conserving network-wide energy consumption is becoming an increasingly important concern for network operators. In this work, we study network-wide energy conservation problem which we hope will offer insights to both network operators and users. In the first part of this work, we study how to maximize throughput under a network-wide energy constraint. We formulate this problem as a mixed-integer nonlinear program (MINLP). We propose a novel piece-wise linear approximation to transform the nonlinear constraints into linear constraints. We prove that the solution developed under this approach is near-optimal with guaranteed performance bound. In the second part, we generalize the problem in the first part by exploring throughput and network-wide energy optimization via a multi-criteria optimization framework. We show that the weakly Pareto-optimal points in the solution can characterize an optimal throughput-energy curve. We offer some interesting properties of the optimal throughput-energy curve which are useful to both network operators and end users.
    Proceedings - IEEE INFOCOM 01/2012;
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    ABSTRACT: This paper presents a theoretical study of the throughput of mobile content distribution (MCD) in vehicular ad hoc networks (VANETs). Since VANET is well-known for its fast-changing topology and adverse wireless channel environments, various protocols have been proposed in the literature to enhance the performance of MCD in a vehicular environment, using packet-level network coding (PLNC) and symbol-level network coding (SLNC). However, there still lacks a fundamental understanding of the limits of MCD protocols using network coding in VANETs. In this paper, we develop a theoretical model to compute the achievable throughput of cooperative MCD in VANETs using SLNC. By considering a one-dimensional road topology with an access point (AP) as the content source, the expected achievable throughput for a vehicle at a certain distance from the AP is derived, for both using PLNC and SLNC. Our proposed model is unique since it captures the effects of multiple practical factors, including vehicle distribution and mobility pattern, channel fading and packet collisions. Through numerical results, we provide insights on optimized design choices for network coding-based cooperative MCD systems in VANETs.
    IEEE Journal on Selected Areas in Communications 01/2012; 30:484-492. · 3.12 Impact Factor
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    ABSTRACT: Recently, an interesting primary transmitter authentication scheme was proposed. The main idea of this scheme is to have the primary transmitter embed cryptographic authentication tag at the physical layer. There are a number of features that make this scheme attractive. In this paper, we investigate the effective coverage areas for the primary and secondary receivers before and after applying this scheme. During the process, we reveal a serious limitation of this scheme, which may prohibit its application in practice.
    Wireless Communications Letters, IEEE. 01/2012; 1(4):324-327.

Publication Stats

1k Citations
76.47 Total Impact Points

Institutions

  • 2007–2012
    • Illinois Institute of Technology
      • Department of Electrical & Computer Engineering
      Chicago, Illinois, United States
  • 2011
    • University of Arkansas at Little Rock
      Little Rock, Arkansas, United States
  • 2004–2011
    • Worcester Polytechnic Institute
      • Department of Electrical and Computer Engineering
      Worcester, Massachusetts, United States
  • 2010
    • University of California, Davis
      • Department of Computer Science
      Davis, CA, United States
  • 2006
    • New Jersey Institute of Technology
      • Department of Electrical and Computer Engineering
      Newark, NJ, United States
  • 2001–2006
    • University of Florida
      • Department of Electrical and Computer Engineering
      Gainesville, FL, United States