Link budget assessment for GEO feeder links based on optical technology

Abstract

Summary Nowadays, large geostationary orbit (GEO) satellites can offer capacities up to 260 Gbps. In the midterm, in order to cope with the forecasted traffic demand, multibeam high throughput satellite systems are already being deployed. Optical GEO feeder link technology may provide transmission data rates up to the order of several terabits per second by making use of wavelength division multiplexing schemes. This work identifies physical layer techniques that enable the transmission of DVB‐S2X RF modulated signals over optical carriers. The techniques reported here are the analog transparent (AT), digital transparent (DT), and the digital regenerative schemes, which require different satellite payload architectures. The effects of atmospheric turbulence over the traveling wave are addressed and discussed, along with a methodology to calculate the link budget in the feeder uplink channel. Link budget calculations for two different selected ground station locations are presented, for the both the AT and DT options. It is shown that for high altitude locations, the transmission using the AT and DT options works well. For midaltitude locations, typical 36 MHz signal are feasible, whereas for higher bandwidths, the DT option could work when an error correction code is used.

Link budget analysis of bi-directional LEO and GEO optical feeder links advancing the beam wander model’s accuracy

“…In literature, several examples of link budget analysis for OFLs have been reported [8][9][10][11][12][13][14] that show several limits. The majority of the existing literature works is focused on the link budget calculation for specific scenarios of interest, often modeling only one propagation direction, i.e., only uplink 12 or only downlink 13 , while others consider just one propagation theory 10,12,14 . The numerical tool proposed in this paper presents several advantages and novelties with respect to them.…”

Pre-distortion adaptive optics: experimental results from bi-directional tracking links between DLR’s optical ground station and Alphasat’s TDP-1 terminal

“…Such links can be used in isolation to establish high-speed and secure connectivity to regions where conventional communication networks are nonexistent or infeasible, 1 or merged with radio frequency communication links to enable the distribution of data across urban centers-the latter of which is known as GEO feeder links. [4][5][6] These GEO feeder links benefit from the GEO satellite's wide field-of-view and high altitude, enabling uninterrupted coverage at continental scales, 7 and the extraordinary data rates provided by FSOC technology, exceeding terabit-per-second levels. 5,8 However, the performance of the bi-directional FSOC link that comprises a GEO feeder link suffers from atmospheric turbulence-i.e., refractive index fluctuations within the atmosphere that distort the propagating laser beams.…”

Optical feeder links for GEO satellites at Viasat Inc.

“…The satellite telecommunication industry has seen significant growth in demand for capacity over the past decade and GEO Optical Feeder Links (OFL) are a promising technology to complement the Radio Frequency (RF) baseline to increase the throughput of satellites [1], [2]. Indeed, the near-infrared optical spectrum intrinsically allows for several THz of communication bandwidth [3] as opposed to a few GHz available in the radio frequency range (e.g., Ka-, Q/V-, and Eband). Also, with the implementation of optical feeder links, the full RF spectrum can potentially be dedicated entirely to the user, massively increasing the available capacity.…”