Past Events

Gossip algorithms are a class of decentralized solutions to theproblem of achieving consensus in a network of agents. Theyhave attracted recent research interest because they are simpleand robust -- attractive qualities for wireless ad-hoc and sensornetworks. Unfortunately, the standard gossip protocol convergesvery slowly for many popular network models. I will discuss threeways to leverage properties of the network to achieve fasterconvergence : routing, broadcast, and mobility. Joint work with Alex G. Dimakis, Tuncer Can Aysal, Mehmet ErcanYildiz, Martin Wainwright, and Anna Scaglione.

WiMAX 2 is a key component of the 4G wireless system. Among many new techniques adoptedin WiMAX 2, transmit beamforming plays an essential role in delivering mobile broadbandservice reliably over an extended coverage. It enhances the received signal quality byexploiting the channel knowledge at the transmitter. In practice, channel feedback isrequired for the base station to acquire the channel knowledge. Since the channelfeedback consumes a large overhead, several schemes were proposed in the IEEE 802.16mtask group for efficient feedback.

Summary: In this talk we will present a brief overview of the MIMAX project, whose goal is to develop a compact and low-power consuming RF-MIMO transceiver, which performs adaptive signal combining in the radio-frequency (RF) domain. Assuming perfect channel knowledge, we will consider in detail the problem of designing the transmit and receive RF beamformers under orthogonal frequency division multiplexing (OFDM) transmissions.

Abstract:Radio frequency interference (RFI) is a key limiting factor in communication performance of Wi-Fi, WiMax, cellular, and other wireless data communication systems. Sources of RFI include 1. other wireless users/services operating in the same frequency band, a.k.a. co-channel interference, 2. nearby electronic equipment, such as microwave ovens radiating in the 2.4 GHz band, and 3. the computational platform itself, including clock circuitry and power saving subsystems in laptops and notebooks.

Abstract In this talk we will present a fundamental role that directed information and causal conditioning has in communication with feedback, gambling with causal side information and estimation.We will begin by defining and establishing some key properties of the notions of causal conditioning and directed information.

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Abstract:The design goal of communication networks is to transport information from a generating source to an intended destination. Of the many ways this can be accomplished, there are networks designed to maximize properly selected optimality criteria. This talk is concerned with basic principles governing the associated optimization problem for wireless communication networks in the presence of fading.

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AbstractThe performance of complex systems depends on joint decision-making by a large number of components. As the system size increases, designs that require global coordination do not scale well, while designs based on just local knowledge perform poorly. Using examples from networking and medical imaging, I will show that global objectives can be achieved via simple local rules that exchange the right amount of information.The first application concerns data measurement in networks. Networks collect detailed statistics on the data (bytes, packets, etc) sent by each flow.

Abstract We are ushering into the era of ubiquitous large-scale complex systems that will offer high-speed data communication, reliable low-power data storage and efficient data inference -- all occurring on a massive scale. An indispensable step towards a systematic innovation in such high-performance systems is the identification of the appropriate performance metric, and the subsequent development of a methodology for efficient system evaluation based on this metric.