Wireless Ad-Hoc Networks: Models, Optimization and Protocols


Canceled due to weather
Location: --

Kin K. Leung
Imperial College London

Abstract
In this seminar, the speaker will give an overview of his current research work in the area of wireless ad-hoc, mesh and sensor networks at Imperial College. By focusing on vehicular networks, the speaker will present new stochastic traffic models for vehicular ad-hoc networks (VANETs) in urban environments and their applications to quantify communication connectivity and identify locations for placing road-side communication nodes to optimize connectivity. Results on distributed optimization techniques for ad-hoc networks with power control will also be discussed briefly. The seminar will then be concluded with a discussion on future work to extend the traffic models, optimization techniques and cross-layer protocol designs for VANETs.

Bio
After receiving his Ph.D. degree from University of California at Los Angeles, Kin K. Leung joined AT&T Bell Labs in New Jersey in 1986 and worked at its successor companies, AT&T Labs and Lucent Technologies Bell Labs, until 2004. Since then, he has been the Tanaka Chair Professor in the Electrical Engineering and Computing Departments at Imperial College in London. He also serves as the Head of Communications and Signal Processing Group and the Deputy Director for the University Defense Research Center in the Electrical Engineering Department. He received a number of honors and awards for his technical contributions, including the IEEE Fellow. He is interested in network protocols, control algorithms, and optimization of wireless broadband, sensor and ad-hoc networks. His website is located at www.commsp.ee.ic.ac.uk/~kkleung/

FlashLinQ: A Clean Slate Design for Ad Hoc Networks

Date: June 9
Time: 4:30-5:30pm
Location: EQuad B327

Xinzhou Wu
Qualcomm Flarion Technologies

Abstract
In this talk, we present a recent design of a synchronous ad hoc network -- FlashLinQ, which can discover peers up to one mile range autonomously, set up links with peers of interest in a secure manner and enable peer communications with much higher spectrum efficiency as compared to existing technologies, e.g. WiFi Direct. FlashLinQ is the enabling technology of the proximate wireless internet -- which we believe is one of the evolution trends of wireless networks. In this talk, we will focus on the PHY/MAC challenges in designing such a network and how we address these challenges in the FlashLinQ design. Both analytical and simulation results will be presented to prove the design concepts behind FlashLinQ.

Bio
Xinzhou Wu received the B.E. degree from Tsinghua University, China in 1998, the M.S. and Ph.D. degrees from University of Illinois at Urbana-Champaign in 2000 and 2004, all in electrical engineering. From 2005 to 2006, he was a member of technical staff at Flarion Technologies, a startup company which designed and deployed the first OFDMA based WAN technology - FlashOFDM. Flarion Technologies was acquired by Qualcomm in January 2006. Dr. Wu is currently a senior staff engineer/manager at Qualcomm Flarion Technologies, Bridgewater, NJ. He is the one of key inventors and developers of the next generation wireless peer-to-peer networks. He co-authored more than 20 technical papers and 100 US patent applications in the area of wireless communications and wireless networking. His current research interests are in distributed algorithms with applications in wireless networks, resource allocation in cellular networks, and network information theory.

Synthesizing Distributed Algorithms for Combinatorial Network Optimization

Date: June 16
Time: 4:30-5:30pm
Location: EQuad B327

Minghua Chen
The Chinese University of Hong Kong

Abstract
Many important network design problems can be formulated as a combinatorial optimization problem. A large number of such problems, however, cannot readily be tackled by distributed algorithms. The Markov approximation framework we presented in this talk is a general technique for synthesizing distributed algorithms. We show that when using the log-sum-exp function to approximate the optimal value of any combinatorial problem, we end up with a solution that can be interpreted as the stationary probability distribution of a class of time reversible Markov chains. Certain carefully designed Markov chains among this class yield distributed algorithms that solve the log-sum-exp approximated combinatorial network optimization problem. From our study in several networking problems, we found Markov approximation technique not only can provide fresh perspective to existing distributed solutions, but also can help us generate new distributed algorithms in various domains with provable performance. We believe the Markov approximation techniques will find application in synthesizing distributed algorithms for solving network optimization problems, and this talk intends to serve as a call for participation.

This is a joint work with Soung Chang Liew, Ziyu Shao, Caihong Kai, and Shaoquan Zhang, all in Information Engineering Department.

Bio
Minghua Chen received his B.Eng. and M.S. degrees from the Department of Electronics Engineering at Tsinghua University in 1999 and 2001, respectively. He received his Ph.D. degree from the Department of Electrical Engineering and Computer Sciences at University of California at Berkeley in 2006. He spent one year visiting Microsoft Research Redmond as a Postdoc Researcher. He joined the Department of Information Engineering, the Chinese University of Hong Kong, in 2007, where he currently is an Assistant Professor. He received the Eli Jury award from UC Berkeley in 2007 (presented to a graduate student or recent alumnus for outstanding achievement in the area of Systems, Communications, Control, or Signal Processing), the ICME Best Paper Award in 2009, and the IEEE Transactions on Multimedia Prize Paper Award in 2009. His research interests include complex systems (currently focusing on smart grid) and networked systems, distributed and stochastic network optimization and control, multimedia networking, p2p networking, wireless networking, multi-level trust data privacy, secure network coding and network coding for security.

Optimality, Fairness, and Robustness in Speed Scaling Designs

Date: June 21
Time: 4:30-5:30pm
Location: EQuad B327

Lachlan Andrew
Swinburne University of Technology

Abstract
System design must strike a balance between energy and performance by carefully selecting the speed at which the system will run. In this work, we examine fundamental trade-off s incurred when designing a speed scaler to minimize a weighted sum of expected response time and energy use per job. We prove that a popular dynamic speed scaling algorithm is 2-competitive for this objective and that no "natural" speed scaler can improve on this. Further, we prove that energy-proportional speed scaling works well across two common scheduling policies: Shortest Remaining Processing Time (SRPT) and Processor Sharing (PS). Third, we show that under SRPT and PS, gated-static speed scaling is nearly optimal when the mean workload is known, but that dynamic speed scaling provides robustness against uncertain workloads. Finally, we prove that speed scaling magni es unfairness, notably SRPT's bias against large jobs and the bias against short jobs in non-preemptive policies. However, PS remains fair under speed scaling. Together, these results show that the speed scalers studied here can achieve any two, but only two, of optimality, fairness, and robustness.

Distributed Interference Management and Scheduling in LTE-A Wireless Femto Networks

Date: June 30
Time: 4:30-5:30pm
Location: EQuad B327

Ashwin Sampath and Ritesh Madan
Qualcomm Flarion Technologies

Abstract
Femto base stations deployed at homes and offices offer cell-splitting gains, and can help improve the performance of mobile applications. However, Femto networks are unplanned; moreover, they may operate in closed subscriber group (CSG) mode where only a few specific mobiles are allowed to connect to a given Femto base station. Such a deployment can lead to high interference; thus distributed interference management techniques become essential. Moreover, since only a few (or just one) mobile may be connected to a Femto base station, statistical multiplexing of resources in one cell is infeasible. Thus, the scheduling and resource allocation across cells needs to be at a fast time scale and coordinated. In addition, it is desirable to keep the control overhead for this coordination to be low.

In this talk, we focus on the design of distributed scheduling and interference management algorithms with very low overhead. We describe a framework for distributed scheduling across multiple Femto cells where a limited amount of information is exchanged between interfering links. Specifically, each transmitter has a limited knowledge of the buffer and channel states in its neighborhood. The framework can be incorporated into current 4G standards such as LTE with little overhead. In this framework, we design a scheduling heuristic to achieve rate fairness across cells for best effort applications (e.g., FTP), and at the same time obtain low latency for delay sensitive applications (e.g., voice, real time video). The heuristic is motivated by the maximum weight scheduling algorithm in wireless networks. We also discuss the impact of scheduling delay on the mechanism and algorithm design.

This is joint work with Ashwin Sampath.

Bio
Ritesh Madan received the B. Tech. degree from IIT Bombay, and the MS. and Ph.D. degrees from Stanford University, all in Electrical Engineering. He was a Sequoia Capital Stanford Graduate Fellow at Stanford. He is currently at the New Jersey Research Center (NJRC) of Qualcomm. His current work involves architecting of interference management mechanisms for heterogeneous networks in 4G standards, and the design of relevant distributed scheduling and interference management algorithms. In the past, he held short term appointments at the Mitsubishi Electric Research Labs (MERL), Cambridge, MA, and the Tata Institute of Fundamental Research (TIFR), Mumbai, India. His research interests are in MAC layer technology and algorithm design, optimization techniques for wireless systems, and stochastic control.

Peeking into Facebook Applications: Activity Graphs & Fake Profiles

Date: July 1
Time: 1:00-2:00pm
Location: EQuad B327

Chen-Nee Chuah
University of California, Davis

Abstract
The collection of Online Social Networks (OSNs) in the Internet today has over half a billion users. Given OSN's growing contribution to Internet traffic, it is important to consider general trends in online user engagement, the approaches taken to achieve this engagement, and its effects on the structure of the underlying social graph. We previously studied a number of user interactions and application characteristics by launching our own highly popular Facebook third-party applications. In a more recent study, we examined how the associated activity graphs evolve and whether the relevant graph theoretic properties remain stable over time.

As more social interaction shifts to the Internet, new social phenomena and social problems may emerge. For example, crime in the cyber space relies crucially on fake identities. Through a measurement-based study of a Facebook gaming application that is known to attract phantom profiles, we show statistical differences among a subset of features associated with genuine and phantom profiles. We then explored using supervised learning techniques to detect/classify such phantom profiles.

Bio
Chen-Nee Chuah is a Professor in the Electrical and Computer Engineering Department at the University of California, Davis. She received her Ph.D. in Electrical Engineering and Computer Sciences from the University of California, Berkeley. Her research interests are in the general area of computer networks, distributed systems, and wireless/mobile computing. Specific topics include: Internet measurements, anomaly detection, network management, and online social networks. She received the NSF CAREER Award in 2003, and the Outstanding Junior Faculty Award from the UC Davis College of Engineering in 2004. In 2008, she was selected as a Chancellor's Fellow of UC Davis. She has served on the executive/technical program committee of several ACM and IEEE conferences and is currently an Associate Editor for IEEE/ACM Transactions on Networking.

Robust Video Duplicates Detection and Localization in Large Video Repository

Date: August 4
Time: 2:30-3:30pm
Location: EQuad B327

Zhu Li
The Hong Kong Polytechnic University

Abstract
Advances in video storage and communication are fueling an explosive growth of online video content at an unprecedented pace. Finding video duplicates in large video repositories is a challenging technical problem that can have many applications in copyright protection, content and product search, and social networks. In this work we develop a likelihood maximization formulation in duplicate detection and localization in large repositories. The likelihood of a probe frame has a (near) duplicate in the repository is evaluated by a multiple feature/multiple indexed locality searching scheme, which approximate the Mahalanobis distance to the repository frames. At sequence level a fast randomized likelihood pruning scheme is applied to reduce the candidate matching sequence set until a match is found or the probe is rejected. The solution offers flexible tradeoffs in detection robustness, localization accuracy, and computational complexity, and now achieves 98% precision on 100% recall in duplicate detection and probe localization within 0.5 second of a 116 hour video repository with a time complexity of 3 ms on a desktop PC with Matlab implementation.

Bio
Zhu Li is currently an Assistant Professor with the Dept of Computing, Hong Kong Polytechnic University. He received his PhD in Electrical & Computer Engineering from Northwestern University, Evanston, USA in 2004. He was a Principal Staff Research Engineer with the Multimedia Research Lab (MRL), Motorola Labs, Schaumburg, USA, 2000~2008.

His research interests include video coding and communication, video network optimization, video analytics and large scale multimedia search and retrieval. He has 12 issued or pending patents, 45 publications in book chapters, journals and conference proceedings in these areas. He received the Best Poster Paper Award at IEEE Int'l Conf on Multimedia & Expo (ICME), Toronto, 2006, and the Best Paper Award at IEEE Int'l Conf on Image Processing (ICIP), San Antonio, 2007.

Heterogeneous networks and Open Cellular Architectures

Date: Sept -- (postponed)
Time: 4:30-5:30pm
Location: EQuad B327

Sundeep Rangan
Polytechnic Institute of New York University

Abstract
Cellular networks today are the archetype of vertical integration: operators currently own and manage the spectrum, backhaul networks and base stations, and exercise considerable control over devices and key applications such as voice. While this model has provided tremendous performance and standardization, the high cost, highly optimized networks deployed by operators to date simply cannot be scaled in a cost effective manner to meet the exploding demand for cellular wireless data. Operators are thus considering alternative heterogenous networks where traditional macrocellular networks are supplemented with low cost femtocells, relays and WiFi offload.

Such heterogeneous networks will introduce many more players into the delivery of wireless data, including subscribers, private ISPs and enterprises. How to coordinate communication in such open cellular environments is a fundamental challenge for the design of next generation networks. In this talk, I will present new ideas in interference coordination and dynamic spectrum access from the perspective of distributed optimization. I will discuss various aspects of heterogeneous networks including backhaul network architectures, spectrum sharing and control messaging.

Bio
Sundeep Rangan received the B.A.Sc. at the University of Waterloo, Canada and the M.Sc. and Ph.D. at the University of California, Berkeley, all in Electrical Engineering. He has held postdoctoral appointments at the University of Michigan, Ann Arbor and Bell Labs. In 2000, he co-founded (with four others) Flarion Technologies, a spin off of Bell Labs, that developed Flash OFDM, the first cellular OFDM data system. Flarion grew to over 150 employees with trials worldwide. In 2006, Flarion was acquired by Qualcomm Technologies. Dr. Rangan was a Director of Engineering at Qualcomm involved in OFDM infrastructure products including femtocells. He joined the ECE department at the Polytechnic Institute of NYU in 2010, where he is an Associate Professor. His research interests are in wireless communications, signal processing, information theory and control theory.

Cognitive Virtual Network Operator Games

Date: August 25
Time: 4:30-5:30pm
Location: EQuad B327

Jianwei Huang
The Chinese University of Hong Kong

Abstract
Abstract: Cognitive virtual network operator (CVNO) is an operator who provides services to the secondary unlicensed wireless devices without actually owning the wireless spectrum. Compared with a traditional virtual network operator who often leases spectrum via long-term contracts, a CVNO can acquire spectrum dynamically in short-term by both sensing the "spectrum holes" of licensed bands and leasing from the spectrum owner. As a result, a CVNO can make flexible investment and pricing decisions to match the current demands of the secondary unlicensed users.

We discuss two scenarios in this talk. In the first case, a monopoly CVNO makes the optimal investment and pricing decisions with supply uncertainty. The system can be modeled as a four-stage Stackelberg game. In the second case, two CVNOs compete with each other to attract the demands from the same pool of end-users. We model this system as a three-stage multi-leader dynamic game. In both cases, we characterize the existence and uniqueness of the subgame perfect equilibrium, and show various interesting structures in terms of operators' investment/pricing decisions and the end-users' QoS. This is a joint work with Lingjie Duan and Biying Shou.

Bio
Jianwei Huang has been an Assistant Professor in the Department of Information Engineering at the Chinese University of Hong Kong since 2007. He received B.S. in Electrical Engineering from Southeast University (Nanjing, Jiangsu, China) in 2000, M.S. and Ph.D. in Electrical and Computer Engineering from Northwestern University (Evanston, IL, USA) in 2003 and 2005, respectively. He worked as a Postdoc Research Associate in the Department of Electrical Engineering at Princeton University during 2005-2007, and as a summer intern in Motorola (Arlington Heights, IL, USA) in 2004 and 2005. Dr. Huang leads the Network Communications and Economics Lab (ncel.ie.cuhk.edu.hk) at the Chinese University of Hong Kong. He conducts research in the area of nonlinear optimization and game theoretical analysis of communication networks, with current focus on network economics, cognitive radio networks, broadband communication networks, and multimedia over wireless. He is the recipient of the IEEE GLOBECOM Best Paper Award in 2010, the IEEE ComSoc Asia-Pacific Outstanding Young Researcher Award in 2009, Asia-Pacific Conference on Communications Best Paper Award in 2009, and Walter P. Murphy Fellowship at Northwestern University in 2001.

Dr. Huang is or has served as Editor of IEEE Transactions on Wireless Communications (2010-), Associate Editor of (Elsevier) Journal of Computer & Electrical Engineering (2007-2010), the Lead Guest Editor of IEEE Journal of Selected Areas in Communications special issue on "Game Theory in Communication Systems", a Guest Editor of (Wiley) Wireless Communications and Mobile Computing special issue on "Innovative Communications for a Better Future", the Lead Guest Editor of Journal of Communications special issue on "Cognitive-Radio Enabled Communications and Networking", the Lead Guest Editor of Journal of Advances in Multimedia special issue on "Collaboration and Optimization in Multimedia Communications", and a Guest Editor of Journal of Advances in Multimedia special issue on "Cross-layer Optimized Wireless Multimedia Communications".

Dr, Huang is or has served as Vice Chair of IEEE Communications Society Multimedia Communications Technical Committee (2010-2012), Director of IEEE Communications Society Multimedia Communications Technical Committee E-letter (2010), the Student Activities Co-Chair of International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt) 2011, the TPC co-chair of the International Conference on Game Theory for Networks (GameNets) 2009, the TPC co-chair of IEEE Globecom Wireless Communications Symposium 2010, the TPC co-chair of the International Wireless Communications and Mobile Computing Conference (IWMobile Computing Symposium 2010, and TPC member of many conferences such as INFOCOM, MobiHoc, ICC, GLBOECOM, DySPAN, WiOpt, and WCNC.