Overview of the Laser Communications Relay Demonstration Project

Abstract

This paper provides an overview of the Laser Communications Relay Demonstration Project (LCRD), a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). LCRD will provide two years of continuous high data rate optical communications in an operational environment, demonstrating how optical communications can meet NASA's growing need for higher data rates, or for the same data rate provided by a comparable RF system, how it enables lower power, lower mass communications systems on user spacecraft. In addition, LCRD's architecture will allow it to serve as a testbed in space for the development of additional symbol coding, link and network layer protocols, etc. This paper reviews the current concepts and designs for the flight and ground optical communications terminals, the critical technologies required, and the concept of operations. It reports preliminary conclusions from several trade studies conducted at GSFC, JPL, and MIT/LL. The flight optical communications terminals will be flown on a commercial communications satellite in geosynchronous orbit to be launched no earlier than December 2016, and will demonstrate a technology critical for NASA's Next Generation Tracking and Data Relay Satellite.

Performance evaluation of optically-preamplified hybrid QPSK M-ary PPM systems with finite extinction ratios

“…Due to their relative design simplicity, direct-detection PPM systems have been considered in several studies [6,7,2,3,12,10,11]. Also, coherent-detection PPM systems have attracted an equal amount of attention owing to their proven bandwidth efficiency [13,14,9].…”

“…Owing to its superior sensitivity, M-ary pulse position modulation (PPM) has been considered in numerous applications such as unrepeatered terrestrial optical fiber links, large split-ratio passive optical networks, and free-space optical communications [1][2][3][4][5][6][7][8][9][10][11][12].…”

Multi-rate DPSK optical transceivers for free-space applications

“…In view of the recent success of the Lunar Laser Communication Demonstration (LLCD) program 1, 2 , NASA's Laser Communication Relay Demonstration (LCRD) program 3,4 is exploring next-generation space-based lasercom transceivers that can support higher Gbit/s-class bidirectional data rates and longer mission duration. Towards that end, we recently reported the proof-of-concept demonstration of a high-sensitivity multi-rate transceiver employing optical differential phase-shift-keying (DPSK) modulation 5 with performance suitable for this application.…”

Influences of hybrid phase-shift error on the performance of optical coherent receivers

“…Satellite optical coherent technologies have been validated by the German in-orbit validation laser communication terminals, which were designed for low earth orbit (LEO) to optical ground station (OGS) links (5.625 Gbps) [6], as well as LEO-LEO links [4,5]. Both the German LEO-geosynchronous earth orbit (GEO) link (1.8 Gbps) [7] and the American laser communications relay demonstration (LCRD) (2.88 Gbps) [8] are based on coherent receiving technologies. Japanese next-generation optical communication terminals (2.5 Gbps) are expected to adopt coherent technologies as well [9,10].…”