For an exhausive list of publications, see Publications.

Transcoding: A new strategy for relay channels

Overview

The relay channel is a traditional information-theoretic problem which has important applications in the Internet of Things (IoT) and other future communication networks. In this work, we focus on the simplest possible relaying model: the so-called separated (or two-hop) relay channel where there is no direct link between the source and the destination.

Previous work has shown that for this channel, the decode-and-forward (DF) relaying strategy is capacity-achieving under the assumption of asymptotic block lengths. In this paper, however, we are interested in the finite-delay regime where simpler sub-optimal techniques like amplify-and-forward (AF) can be used to avoid the need for buffering at the relay. We present a new strategy called transcoding which presents a tradeoff between the low-latency advantages of amplify-and-forward and the high-rate, high-latency decode-and-forward scheme. Our results indicate that our simple, intuitive transcoding schemes outperform traditional relaying schemes in the finite-delay regime.

Conference papers & talks

Noisy Beam Alignment Techniques for Reciprocal MIMO Channels

Overview

The focus of this work is on beam alignment for time-division duplexing (TDD) systems, for which we propose a number of novel algorithms. These algorithms seek to obtain good estimates of the optimal beamformer/combiner pair (which are the dominant singular vectors of the channel matrix). They are motivated by the power method, an iterative algorithm to determine eigenvalues and eigenvectors through repeated matrix multiplication.

In contrast to the basic power method which considers only the most recent iteration and assumes noiseless links, the proposed techniques consider information from all the previous iterations of the algorithm and combine them in different ways.

Preprint

  • arXiv: D. Ogbe, D. J. Love, and V. Raghavan, “Noisy Beam Alignment Techniques for Reciprocal MIMO Channels,” arXiv:1609.03601 [cs.IT], Sept. 2016.

Publisher Link

Conference papers & talks

We presented this work at ICASSP 2017.

I also gave a poster presentation of this work at the 2017 North American School of Information Theory. Please contact me if you are interested in obtaining the poster.

Resources

I am still going over the simulation code before I can post it here. Stay tuned.


DARPA Spectrum Collaboration Challenge

Overview

I am a key member of BAM! Wireless, a team of academics competing in the ongoing DARPA Spectrum Collaboration Challenge, DARPA's grand challenge to overcome spectrum scarcity. Our team has developed a state-of-the art software-defined collaborative radio (BAM! Radio), which has so far placed among the top ten finishers after phase 1 of the challenge and won $750,000 in prize money.

Video

A recap of the "finale" of Phase 1, held at John's Hopkins Applied Physics Lab in Laurel, MD.


Maximizing wireless power transfer using distributed beamforming

Conference papers & talks