title: Experimental observations of channel reciprocity in single-mode free-space optical links.
abstract: This article describes observations made during a recent series of single-mode lasercom experiments in which high-rate data transmission was demonstrated between a small aircraft and a ground station separated by distances up to 80 km. A significant result of the subsequent data analysis was the discovery of near-unity correlations between the signal fluctuations observed by power monitors at the two ends of the link. This evidence of reciprocity is presented, along with the description of a preliminary concept for utilizing this channel state information to improve link performance.
authors.affiliation: Massachusetts Institute of Technology Lincoln Laboratory, Lexington, Massachusetts 02420-9108, USA. parenti@ll.mit.edu
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Parenti
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Roth
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Shapiro
authors.forename: Frederick G
authors.initials: FG
authors.lastname: Walther
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Greco