|
 |
 |
 |
|
 |
|
 |
|
|
 |
|
Telecommunications & Networking EventsSpring 2007 SeminarsCharles Kalmanek, (AT&T) CARRIER-GRADE IP: RESEARCH IN IP NETWORK & SERVICE MANAGEMENT Abstract: The service expectation for IP networks has increased dramatically in the last five years, to the point that businesses and even consumers typically expect IP services to be “carrier-grade.” Yet, in many ways, management of IP networks and services remains a challenge. These networks and services are increasingly complex; they are subject to a bewildering combination of possible hardware and software faults; and they face security concerns unknown three decades ago when the Internet Protocol was developed. This talk presents some of the technical challenges facing network operators today, and describes research in advanced fault management tools, and network automated control, providing practical examples of the current state-of-the-art in network management technology.
Biography: Charles R. Kalmanek is Vice President of Internet and Network Systems Research at AT&T Labs. Chuck is responsible for AT&T's research program in IP network and performance management; optical systems; wireless systems; network design and optimization; converged services; and fundamental algorithms. Some specific areas of research in Chuck's lab include IP traffic monitoring and analysis, IP control plane monitoring and analysis, large scale data correlation, advances in 4G wireless technologies, IMS-based solutions for wireless-wireline convergence, and ultra-long-haul and passive optical networks. Chuck joined AT&T Bell Labs in 1980, and was a founding member of AT&T Labs when it was created from Bell Labs in 1995. Chuck has extensive experience in network architecture, protocols and distributed systems. Chuck's research spans IP network management, access network architectures, IP routing, voice over IP, multimedia streaming, content distribution networks, as well as packet switch and host interface design. Chuck received his undergraduate degree from Cornell University, and M.S. degrees in Electrical Engineering and Computer Science from Columbia University and New York University respectively. Chuck is a recipient of AT&T's Strategic Patent and Strategic Standards Awards, and was co-chair of the IEEE Internet Technical Committee from 2000-2004. Click here to view Dr. Kalmanek's slide presentation. Xiaodong Wang, (Columbia University) INTERFERENCE SUPPRESSION TECHNIQUES FOR MULTIUSER MIMO SYSTEMS Abstract: We consider a slow-fading narrowband MIMO multiple access channel (MAC) in which multiple users, each equipped with multiple transmit antennas, communicate to a receiver equipped with multiple receive antennas. The users are unaware of the channel state information (CSI) whereas the receiver has perfect CSI and employs a successive group decoder (SGD). We obtain achievable outage probabilities for the case where an outage must be declared simultaneously for all users (common outage) as well as the case where outages can be declared individually for each user (individual outage). We then derive the optimum successive group decoder (OSGD) that simultaneously minimizes the common outage probability and the individual outage probability of each user, over all SGDs of permissible decoding complexity. Limiting expressions for the relevant capacities as the number of users and the number of receive antennas approach infinity are also obtained. We also also briefly discuss efficient interference suppression techniques for downlink MIMO systems. Biography: Xiaodong Wang received the Ph.D degree in Electrical Engineering from Princeton University. He is now on the faculty of the Department of Electrical Engineering, Columbia University. Dr. Wang's research interests fall in the general areas of computing, signal processing and communications, and has published extensively in these areas. Among his publications is a recent book entitled ``Wireless Communication Systems: Advanced Techniques for Signal Reception'', published by Prentice Hall in 2003. His current research interests include wireless communications, statistical signal processing, and genomic signal processing. Dr. Wang received the 1999 NSF CAREER Award, and the 2001 IEEE Communications Society and Information Theory Society Joint Paper Award. He has served as an Associate Editor for the IEEE Transactions on Communications, the IEEE Transactions on Wireless Communications, the IEEE Transactions on Signal Processing, and the IEEE Transactions on Information Theory.
Michael Neely, (USC) Crosslayer Optimization for Wireless Networks with Multi-Receiver Diversity Abstract: We consider the problem of communicating data from multiple traffic streams over an ad-hoc wireless network with time varying channels, user mobility, and possible transmission errors. Our network model is well suited for stochastic environments where exact channel conditions are difficult to assess, such as underwater networks of acoustic transmitters (where ocean dynamics and large delays create channel uncertainty), and land networks with mobility (where knowledge of which receivers are currently within transmission range may be uncertain). To communicate in these extreme environments, we exploit the broadcast advantage of wireless networks. Specifically, a single transmission might be overheard by a set of potential receivers. This creates a natural multi-receiver diversity gain, where the probability that at least one node successfully receives the transmission can be much larger than the success probability of any pre-specified receiver. To fully exploit the multi-receiver diversity gain, network routing algorithms must be designed with the flexibility of dynamically adjusting routing decisions after each packet is transmitted. This functionality affects network design at all networking layers, and is a hot topic of current research. In this talk, we present novel cross-layer control algorithms for routing, resource allocation, and flow control, with the goal of optimizing performance metrics of throughput, fairness, and power expenditure. A simple set of distributed flow control and routing algorithms are presented and shown to achieve optimality subject to a given multiple access structure, and the challenge of choosing a good multiple access structure is also discussed. Our results are based on the stochastic network optimization techniques developed in our recent work (Ph.D. Thesis 2003, INFOCOM 2003, 2005, CISS 2006, NOW Foundations & Trends 2006). Biography: Michael J. Neely received B.S. degrees in both Electrical Engineering and Mathematics from the University of Maryland, College Park, in 1997. He was then awarded a 3-year Department of Defense NDSEG Fellowship for graduate study at the Massachusetts Institute of Technology, where he received an M.S. degree in 1999 and a Ph.D. in 2003, both in Electrical Engineering. During the Summer of 2002, he worked in the Distributed Sensor Networks group at Draper Labs in Cambridge. In 2004 he joined the faculty of the Electrical Engineering Department at the University of Southern California where he is currently an Assistant Professor. His research is in the area of stochastic network optimization for wireless networks, mobile ad-hoc networks, and queueing systems. Michael is a member of Tau Beta Pi and Phi Beta Kappa. Danijela Cabric , (University of California, Berkeley) Cognitive Radios: Systems Design Perspective Abstract: A major shift in wireless communications is now emerging with the development of cognitive radios, which attempt to share spectrum in a fundamentally new way. Cognitive radios address the problem of poor spectrum utilization exhibited in many frequency bands. On a conceptual level, cognitive radio networks sense the spectral environment and adapt transmission parameters to dynamically re-use available spectrum. The novelty of this approach requires us to re-architect the mechanisms for using radio frequencies and find a way for multiple systems to co-exist through sharing rather than fixed allocations. This talk addresses fundamental questions in cognitive radios system design and investigates its feasibility by briding the theoretical and practical aspects of the physical and network layers. We begin with spectrum sensing, the key enabling functionality for cognitive radios, which requires detection of very weak signals of different t ypes in a minimum time with high reliability. We show that the biggest barrier for sensing in very low signal to noise ratio regimes is the variability in the noise and interference that cannot be perfectly calibrated during sensing time. Robustness can be increased by differentiating signals from noise by detecting signal features or by exploiting channel diversity with network cooperation. Through physical implementation and experiments of proposed sensing methods, we identify the minimum possible sensing times and detectable signal levels. Moreover, we include the sensitivities exhibited by these methods to radio and channel impairments. Next, we consider radio architecture for wideband spectrum sharing radios and show that large dynamic range requirements present major challenge in their implementation. This calls for the development of novel mixed signal techniques. By exploiting spatial dimension for selective processing of desired signals through antenna array architectures, strong interferers can be adaptively suppressed. We conclude with a discussion of the requirements for the signaling and protocol designs that support dynamic spectrum access and spectrum sensing coordination. Biography: Danijela Cabric received the Dipl. Ing. degree from the University of Belgrade, Serbia, in 1998 and the M.S. degree in electrical engineering from the University of California, Los Angeles in 2001. She is currently working toward the Ph.D. degree at the University of California at Berkeley, where she is a member of the Berkeley Wireless Research Center. Her current research interests include cognitive radio physical and network layer design, and use of multiple antennas in spectrum sharing. In particular, she is interested in novel architectures and signal processing algorithms for wideband radios such as spectrum sensing, spatial filtering and adaptive modulations.
Ken Zeger, (University of California, San Diego) Theory of Network Coding Abstract: In network coding, instead of simply routing information, input data can be "combined" at nodes that are allowed to perform arbitrary processing. It is known that network coding can increase the transmission rate of information compared to routing. This talk will give a tutorial on the basic ideas of network coding and then will focus on recent research results aimed at establishing a theoretical basis for this new and exciting field. Specific network coding topics to be discussed include: linearity, solvability, bi-directionality, point-to-point mode, broadcast mode, alphabet size, capacity, vector coding, reversibility, coding constraints, achievable rate regions, multicast, and multiple unicast. A diverse collection of mathematical topics used to obtain many of our network coding results will be discussed, including: linear algebra, probability, graph theory, matroids, latin squares, projective geometry, information theory, complexity theory, groups, rings, fields, and modules.
Biography: Ken Zeger received both the SB and SM degrees in EECS from MIT in 1984, and both the MA degree in Mathematics and the PhD in EE at UCSB, in 1989 and 1990, respectively. He was an Assistant Professor of EE at the University of Hawaii from 1990 to 1992. He was in the Department of ECE and the Coordinated Science Laboratory at the University of Illinois at Urbana-Champaign, as an Assistant Professor from 1992 to 1995, and as an Associate Professor from 1995 to 1996. He has been in the Department of ECE at UCSD, as an Associate Professor from 1996 to 1998, and as a Professor from 1998 to present. He received an NSF Presidential Young Investigator Award in 1991. He served as Associate Editor-At-Large for the IEEE Transactions on Information Theory during 1995-1998, as a member of the Board of Governors of the IEEE Information Theory Society during 1998-2000 and 2005-2007, and became an IEEE Fellow in 2000.
Nazanin Rahnavard, (Georgia Institute of Technology) Monday, March 26, 2007 12:00 noon - 1:00 pm, 337 Towne Building Modern Error-Control Coding and Its Applications in Wireless Ad-Hoc and Sensor Networks Abstract: Error-correcting codes are ubiquitous in communication systems, and their application is expanding along with the growing influence of communication technology in everyday life. They have played an indispensable role in the development of wireless systems, data storage devices such as CDs and DVDs, computer networks, and satellite communications. A very important and new application of coding is in the emerging field of Wireless Sensor Networks (WSNs). Our research at the Georgia Institute of Technology has shown that modern error-control codes, namely low-density parity-check (LDPC) codes and rateless codes, can substantially improve the efficiency of data transmission in error-prone wireless networks.
The goal of this talk is to present the application of modern coding schemes in wireless networks to enhance data transmission efficiency. The main focus of the talk will be on efficient one-to-all data broadcasting in WSNs. The scarce resources of sensor nodes demand protocols that are energy efficient and have low complexity. Our proposed scheme, referred to as Collaborative Rateless Broadcast (CRBcast), is designed based on these requirements. CRBcast employs rateless codes to achieve reliability and improve energy efficiency, without the need for any prior knowledge of the network topology. I discuss CRBcast in detail and illustrate our results. I also briefly present our research accomplishment in the design of coding schemes that provide unequal error protection and are suitable for multimedia transmission in wireless networks. The presentation concludes with a discussion of future challenges and open areas for further study. Biography: Nazanin Rahnavard received her B.S. and M.S. degrees in electrical engineering from Sharif University of Technology, in 1999 and 2001, respectively. She then joined the Georgia Institute of Technology, w here she is c urrently pursuing a Ph.D. degree in the School of Electrical and Computer Engineering. Her research interests lie in the area of telecommunications with a focus on error-control coding and wireless ad hoc and sensor networks.
Chris T.K. Ng (Stanford University) Monday, April 9, 2007 10:00 am - 11:00 am, Berger Auditorium (Skirkanich Building) Cross-Layer Design and Cooperation in Wireless Networks Abstract: Traditionally, the design of communication networks has been studied under the disparate disciplines of communication theory, computer networks, and information theory with little interdisciplinary interaction. While this segmented approach to wireless network design was viable in the past, its poor performance has failed to keep up with the rapid growth of emerging wireless network applications. Optimizing network performance to support applications that will emerge over the next several decades requires a multidisciplinary approach that jointly considers communication, network, and application design. In this talk, we discuss cross-layer design in wireless networks, including: i) source-channel coding; and ii) cooperative communications. Under ideal conditions without delay contraints, there is no penalty in separately performing source coding and channel coding. However, under more practical operating conditions where there is a constraint on delay and the transmitter does not know the channel perfectly, we show that the optimal source-channel coding scheme jointly depends on the statistics of both the source and the channel. Moreover, when neighboring wireless nodes cooperate in the transmission, relaying, and reception of information, capacity gain over non-cooperative can be realized, but only with the right cooperation strategy based on the network topology, channel side information, and power allocation assumptions. We conclude with a discussion on combining source coding with cooperative transmission, where end-to-end performance is optimized when uncertainty in side information is taken into account. Biography: Chris Ng received his Bachelor of Applied Science in Engineering Science from the University of Toronto. He is a PhD candidate in Electrical Engineering at Stanford University. At Wireless Systems Lab, his research interests include cooperative communications, joint source-channel coding, cross-layer wireless network design, and network information theory.
Mehul Motani (National University of Singapore) Friday, April 13, 2007 11:00 am - 12:00 noon, 337 Towne Building Cooperative Networking -- Theoretical & Experimental Approaches Abstract: In the last 60 years or so, information theory has helped to characterize many fundamental limits of communication and has driven innovation at the physical layer. In that same time, networking for wireline networks has matured but wireless networks have advanced in a somewhat ad-hoc manner. One of the main challenges is that nodes in wireless networks can interact and cooperate in complex ways, often blurring the line between physical and network layer functions. My research group aims to understand this interaction, which we term cooperative networking, through a multi-faceted approach. On one hand, we take an information theoretic approach to explore efficient routing strategies in cooperative networks. On the other hand, we take an experimental approach to evaluate the real world behavior of algorithms for communication and cooperation in networks. I will discuss a few examples including our design and evaluation of protocols for cooperative multichannel MAC and opportunistic acknowledgment in wireless networks. Biography: Mehul Motani is currently with the department of Electrical & Computer ENgineering at the National University of Singapore. He graduated with a PhD from Cornell University, focusing on information theory and coding for CDMA systems. Prior to his PhD, he was a hardware/systems engineer at Lockheed Martin in Syracuse, New York. Recently he has been working on research problems which sit at the boundary of information theory, communications and networking, including the design of wireless ad-hoc and sensor network systems. He was awarded the Intel Foundation Fellowship for work related to his PhD in 2000. He is on the organizing committees for ISIT 2006 and 2007 and the technical program committees of MobiCom 2007 & Infocom 2008 and several other conferences. He participates actively in IEEE & Sigmobile/ACM and has served as the secretary of the IEEE Information Theory Society Board of Governors.
Rajeev Agrawal, (Motorola) Abstract: This talk will consider the problem of downlink scheduling in OFDM systems. The scheduling problem is to determine the sub-channels allocated to each user, and for each sub-channel the modulation and coding scheme (MCS) and power level for the user to whom it is allocatd. We have shown earlier that scheduling for elastic traffic for a broad class of channels can by asymptotically solved by a dradient-based policy. The gradient optimization problem can be viewed as a weighted rate optimization problem over a suitably defined rate region that depends on the "channel" state and system and user parameters. For an OFDM system the "channel" state depends on the channelization structure, feedback granularity, etc. Given the "channel" state we formulate the weighted rate maximization problem as a convex optimization problem. The solution is obtained by solving the dual problem through a combination of analytic steps and a one-dimensional numerical search with geometrically fast convergence to the optimal. The dual approach also reveals key structural propertise and a finite-time algorithm for optimal power allocation when the sub-channel allocation is given. Using the general solution we specialize to different channelization and feedback schemes used in practice. We also consider a channel model where the channel response is not completely known; this induces a model with self noise that upper bounds the achievable SINR. (This work is joint with Vijay Subramanian, Randall Berry and Jianwei Huang). Biography: Rajeev Agrawal is a Fellow of the Technical Staff in the Networks Advanced Technology organization of Motorola's Networks and Enterprise Business. He heads the Advanced Networks and Performance Department and his responsibilities include the architecture, design and optimization of Motorola's next generation wireless systems. Prior to joining Motorola in 1999, Rajeev was Professor of Electrical and Computer Engineering and Computer Science departments at the University of Wisconsin--Madison. While at UW-Madison, he conducted research on stochastic control, traffic control and QoS in communication networks, scheduling and resource allocation in wireless systems. He also spent a sabbatical year at IBM T.J. Watson Research, British Telecom Labs, and INRIA-Sophia Antipolis. Rajeev received his M.S. (1987) and Ph.D. (1988) degrees in electrical engineering-systems from the University of Michigan, Ann Arbor and his B.Tech (1985) degree in electrical engineering from the Indian Institute of Technology, Kanpur.
Conor Madigan , (Massachusetts Institute of Technology) Abstract: Electronic and optoelectronic devices composed of disordered, nano-structured thin films are increasingly making major technological contributions to the world. Two well-publicized examples that have already made the transition from the lab to the market are organic light emitting devices (OLEDs) and TNT sensors. In labs across the globe work also continues on solar emitting devices (OLEDs) and TNT sensors. In labs across the globe work also continues on solar cells, photodetectors, lasers, transistors, and chemical sensors. In my work I have investigated the design and fabrication of a variety of thin film devices employing disordered, nano-structured materials such as amorphous small molecule organics, polymers, inorganic oxides, and inorganic semiconductor nanocrystals. In this talk I will describe the opportunities and challenges in developing devices in this material space and in understanding their behavior. I will discuss TNT chemical sensors as a case study in the synthesis of novel materal properties and device engineering. I will then develop a general approach to device physics based on nano-scale models that is well adapted to the entire field. Finally, I will make a case for where the field is heading and where the next breakthroughs are waiting. Biography: Dr. Madigan earned his B.S.E. in Electrical Engineering from Princeton University and M.S. and Ph.D. in Electrical Engineering from M.I.T. His research interests include computational algorithms, nanoscale physical modeling and simulation, amorphous thin film deposition technology, and novel electrical and optoelectronic devices utilizing disordered, nanostructured thin films. He is the author of 10 journal articles and co-inventor on 3 patents which have been licensed by a number of small and large companies.
|
|||
|
|||
