Abstract

Cooperation in communication networks results when terminals use their energy and bandwidth resources to mutually enhance their transmissions. Cooperation can be induced in many ways and each approach entails a different tradeoff of power, bandwidth, complexity, and costs to achieve spatial diversity gains characteristic of antenna arrays. In this talk, we present a specific cooperative network - a multiaccess relay channel (MARC) - where cooperation is induced via a dedicated relay node in a network where multiple independent users communicate with one destination.

We first extend the classical relaying strategies of decode-and-forward (DF), compress-and-forward (CF), and amplify-and-forward (AF) to the MARC. Next we compare this approach of inducing cooperation in a multiaccess channel using a relay (relay cooperation) to the approach of allowing the users to cooperate with each other (user cooperation). Using the total transmit and processing power consumed as a cost metric, we compare the DF and AF outage probabilities for the two networks. We model processing costs as a function of transmission rates and use geometry-inclusive outage analyses as well as area-averaged numerical results to show that cooperation is most desirable in the regime where processing power is significantly smaller than the transmit power. We also show that the maximum spatial diversity gains resulting from user cooperation may not always be achievable in SNR regimes of practical interest without trading off delay and complexity. Finally, our results also reveal that relay cooperation is on average more energy efficient than user cooperation.

Speaker Bio 

Lalitha Sankar received the B.Tech degree in Engineering Physics from the Indian Institute of Technology, Bombay in 1992, the MS degree in Electrical Engineering from the University of Maryland, Baltimore County in 1994, and the Ph.D degree in Electrical Engineering from Rutgers University in June 2007. She is presently a Science and Technology postdoctoral fellow at Princeton University.

From August 1994 to August 1995 she was with the Engineering R&D division of Polaroid Corporation in Cambridge, MA. Following this, she was a Senior Member of Technical Staff at AT&T Shannon Labs in Florham Park, NJ until March 2002. She holds three U.S. patents in the area of digital subscriber line communications.

For more information please contact:

Yingying Chen
Assistant Professor & NIS Graduate Program Director
Burchard
Room 210
Phone: 201.216.8066
Fax: 201.216.8246
yingying.chen@stevens.edu