Optical inter-satellite link terminals for next generation satellite constellations

Carrizo, Carlos Eduardo; Knapek, Markus; Horwath, Joachim; Gonzalez, Dionisio Diaz; Cornwell, Paul

doi:10.1117/12.2545629

Cited by 32 publications

(21 citation statements)

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“…This delay is incurred whenever new LISLs are required to be established between pairs of satellites when there is a change in the shortest path between source and destination ground stations and one or more new satellites are introduced in the path requiring creation of new LISLs. Currently, this delay can vary from a few seconds to tens of seconds, e.g., Mynaric's CONDOR laser communication terminal needs approximately 30 seconds to establish LISLs between pairs of satellites in the OWSN for the first time but once the position and altitude of the satellites are exchanged, this delay reduces to 2 seconds [35]. This delay could be incorporated in the end-to-end latency of the shortest paths over the OWSN for a more accurate comparison of OWSN and OFTN in terms of latency.…”

Section: Incorporating Extra Distance To Account For the Zig-zag Path...mentioning

confidence: 99%

When to Crossover From Earth to Space for Lower Latency Data Communications?

Chaudhry

Yanıkömeroğlu

2022

IEEE Trans. Aerosp. Electron. Syst.

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For data communications over long distances, optical wireless satellite networks (OWSNs) can offer lower latency than optical fiber terrestrial networks (OFTNs). However, when is it beneficial to switch or crossover from an OFTN to an OWSN for lower latency data communications? In this work, we introduce a crossover function that enables to find the crossover distance, i.e., a distance between two points on the surface of the Earth beyond which switching or crossing over from an OFTN to an OWSN for data communications between these points is useful in terms of latency. Numerical results reveal that a higher refractive index of optical fiber (or 𝑖) in an OFTN and a lower altitude of satellites (or ℎ) in an OWSN result in a shorter crossover distance. To account for the variation in the end-to-end propagation distance that occurs over the OWSN, we examine the crossover function in four different scenarios. Numerical results indicate that the crossover distance varies with the end-to-end propagation distance over an OWSN and is different for different scenarios. We calculate the average crossover distance over all scenarios for different ℎ and 𝑖 and use it to evaluate the simulation results. Furthermore, for a comparative analysis of OFTNs and OWSNs in terms of latency, we study three different OFTNs having different refractive indices and three different OWSNs having different satellite altitudes in three different scenarios for long-distance intercontinental data communications, including connections between New York and Dublin, Sao Paulo and London, and Toronto and Sydney. All three OWSNs offer better latency than OFTN2 (with 𝑖 2 = 1.3) and OFTN3 (with 𝑖 3 = 1.4675) in all scenarios. For example, for Toronto-Sydney connection, OWSN1 (with ℎ 1 = 300 km), OWSN2 (with ℎ 2 = 550 km) and OWSN3 (with ℎ 3 = 1,100 km) perform better than OFTN2 by 18.11%, 16.08%, and 10.30%, respectively, while they provide an improvement in latency of 27.46%, 25.67%, and 20.54%, respectively, compared to OFTN3. The OWSN1 performs better than OFTN1 (with 𝑖 1 = 1.1) for Sao Paulo-London and Toronto-Sydney connections by 2.23% and 3.22%, respectively, while OWSN2 outperforms OFTN1 for Toronto-Sydney connection by 0.82%. For New York-Dublin connection, all OWSNs while for Sao Paulo-London connection, OWSN2 and OWSN3 exhibit higher latency than OFTN1 as the corresponding average crossover distances are greater than the shortest terrestrial distances between cities in these scenarios. Multiple satellites (or laser inter-satellite links) on its shortest paths drive up the propagation distance to the extent that OWSN3 ends up with a higher latency than OFTN1 for the Toronto-Sydney inter-continental connection scenario although the related average crossover distance is less than the shortest terrestrial distance between Toronto and Sydney. The challenges related to OWSNs and OFTNs that may arise from this work in future are also highlighted.

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Section: Incorporating Extra Distance To Account For the Zig-zag Path...mentioning

confidence: 99%

When to Crossover From Earth to Space for Lower Latency Data Communications?

Chaudhry

Yanıkömeroğlu

2022

IEEE Trans. Aerosp. Electron. Syst.

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“…In the literature, there are various studies that consider link budget analysis for optical satellite communications as can be seen in [6]- [10] and the references therein. Different from the current literature, we investigate both optical inter-satellite link between LEO satellites and optical uplink/downlink between LEO satellites and ground stations that can establish FSOSNs in space.…”

Section: Related Workmentioning

confidence: 99%

“…In the link budget analysis of FSOSNs, we first vary the link distance and set the required received power as -35.5 dBm, data rate as 10 Gbps, and bit error rate as 10 −12 [6]. We observe that the link transmission power increases with the increase in link distance.…”

Section: Introductionmentioning

confidence: 99%

Link Budget Analysis for Free-Space Optical Satellite Networks

Liang¹,

Chaudhry²,

Erdoğan³

et al. 2022

Preprint

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Free-space optical satellite networks (FSOSNs) will employ free-space optical links between satellites and between satellites and ground stations, and the link budget for optical inter-satellite links and optical uplink/downlink is analyzed in this paper. The satellites in these FSOSNs will have limited energy and thereby limited power, and we investigate the effect of link distance and link margin on optical inter-satellite link transmission power, and the effect of slant distance, elevation angle, and link margin on optical uplink/downlink transmission power. We model these optical links and compute the results for various parameters. We observe that the transmission power increases when the link distance increases for inter-satellite and uplink/downlink communications, while the transmission power decreases when the elevation angle increases for uplink/downlink transmission. We also observe an inverse relationship between link margin and link distance. Furthermore, we highlight some practical insights and design guidelines gained from this analysis.

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“…Due to constraint of link distance, each satellite is typically equipped with four bidirectional ISLs: two intra-plane ISLs and two inter-plane ISLs. As optical ISLs have lots of advantages over RF ISLs [16], there is a trend to adopt optical ISLs in satellite constellations. However, optical ISLs face challenging problems of pointing, acquisition and tracking (PAT).…”

Section: A Satellite Constellationmentioning

confidence: 99%

A Distributed Survivable Routing Algorithm for Mega-Constellations With Inclined Orbits

Zhang

Qiu

2020

IEEE Access

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Mega-constellations consisting of hundreds to thousands of low-earth-orbit (LEO) satellites are an attractive solution for providing global ubiquitous network access. Due to good coverage properties for populated areas, inclined orbits are gaining popularity among commercial constellations. A scalable routing algorithm with survivability plays a key role in such systems. In this paper, we propose a distributed survivable routing algorithm for mega-constellations with inclined orbits. First, the special topology characteristic of inclined constellations is identified and formalized. Based on the topology characterization, a basic X-Y routing algorithm is presented to determine multiple primary and secondary paths towards each destination utilizing the regularity of the network topology with minimal computation overhead. Then, a failure recovery mechanism which consists of a restricted flooding mechanism and a pre-detour mechanism is proposed to reduce end-to-end delay and signaling overhead in case of link failures. Besides, a partialrecord loop avoidance mechanism is proposed to deal with routing loops with minimal overhead. Finally, a vector-based next hop selection mechanism is proposed to facilitate the selection of next hop while incorporating various criteria. The performance of the proposed routing algorithm is evaluated through simulation on the Starlink constellation. Simulation results show that our proposal achieves scalability by reducing signaling overhead and provides better quality of service in terms of end-to-end delay under link failures.

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Optical inter-satellite link terminals for next generation satellite constellations

Cited by 32 publications

References 0 publications

When to Crossover From Earth to Space for Lower Latency Data Communications?

When to Crossover From Earth to Space for Lower Latency Data Communications?

Link Budget Analysis for Free-Space Optical Satellite Networks

A Distributed Survivable Routing Algorithm for Mega-Constellations With Inclined Orbits

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