On Crossover Distance for Optical Wireless Satellite Networks and Optical Fiber Terrestrial Networks

TL;DR

This paper extends the crossover function to include intermediate satellites in optical wireless satellite networks, analyzing how hops, satellite altitude, and fiber refractive index influence the crossover distance and link lengths for optimized low-latency data transmission.

Contribution

It introduces an extended crossover function accounting for multiple hops in satellite networks, providing a more realistic model for latency comparison with terrestrial fiber networks.

Findings

Crossover distance increases with the number of hops and satellite altitude.

Higher refractive indexes in fiber reduce the crossover distance.

Number of hops inversely affects the length of laser inter-satellite links.

Abstract

Optical wireless satellite networks (OWSNs) can provide lower latency data communications compared to optical fiber terrestrial networks (OFTNs). The crossover function enables to calculate the crossover distance for an OWSN and an OFTN. If the distance between two points on Earth is greater than the crossover distance, then switching or crossing over from the OFTN to the OWSN results in lower latency for data communications between these points. In this work, we extend the previously proposed crossover function for a scenario such that intermediate satellites (or hops) are incorporated between ingress and egress satellites in the OWSN for a more realistic calculation of the crossover distance in this scenario. We consider different OWSNs with different satellite altitudes and different OFTNs with different optical fiber refractive indexes, and we study the effect of the number of hops on the crossover distance and length of a laser inter-satellite link (LISL). It is observed from the numerical results that the crossover distance increases with an increase in the number of hops, and this increase is higher at higher satellite altitudes in OWSNs and lower refractive indexes in OFTNs. Furthermore, an inverse relationship between the crossover distance and length of a LISL is observed. With an increase in the number of hops, the length of a LISL decreases as opposed to the crossover distance.