“Round-Trip Carrier Synchronization for Distributed Transmit Beamforming”

Abstract

Distributed transmit beamforming is a technique in which two or more single-antenna wireless transmitters work  together to transmit common information as a virtual antenna array. Like conventional transmit beamforming, distributed transmit  beamforming offers potential gains in range, energy efficiency, and/or security with respect to single-antenna transmission.  Unlike conventional antenna arrays, however, each antenna (individual source node) in a distributed beamformer has its own  imperfect local oscillator. The carriers generated by each source node must be accurately synchronized in both phase and  frequency in order to direct a beam towards an intended destination. We review the relevant literature in this area and describe  two new "round-trip" approaches to this problem. We analyze the performance of our proposed "round-trip" carrier  synchronization techniques in terms of phase offset at the intended destination and the required synchronization overhead under  several channel models. Our results suggest that near-ideal beamforming gains can be achieved by a two-source collaborative  beamformer, even under half-duplex constraints, and that the synchronization overhead can be small with respect to the  potential beamforming gains.

Bio

D. Richard Brown III is an Associate Professor in the Department of Electrical and Computer Engineering at Worcester  Polytechnic Institute. He received a PhD in Electrical Engineering from Cornell University in 2000 and MS and BS degrees in  Electrical Engineering from The University of Connecticut in 1996 and 1992, respectively. He is currently on sabbatical leave  from WPI with an appointment as a Visiting Associate Professor at Princeton University until June 2008.