Effects of Correlated Multivariate FSO Channel on Outage Performance of Space-Air-Ground Integrated Network (SAGIN)

Abstract

In order to share the global information and resources efficiently over a huge network topology, the Space-Air-Ground Integrated Network (SAGIN) system integrates a number of networks for optimal utilization. Nonetheless, the related communication units between the mobile platforms and air-to-ground links are constrained to a low-bit rate radio-based technology. In addition, the required services to be supported demand a high capacity link. This will ensure effective management of multiple information in parallel and in real-time. One of attractive systems with inherent features to support the network demands is the free-space optical (FSO) communication system. Nevertheless, drift support in the SAGIN could be challenging for the FSO system. This is due to the required line-of-sight link alignment between the receiver and transmitter modules. Besides, FSO system is susceptible to the atmospheric turbulence-induced fading. This can be addressed by operating unmanned aerial vehicles in the SAGIN system in swarm mode. Conversely, this can bring about channel correlation eventually resulting into system performance impairments. This paper considers the effect of correlated FSO channel on the SAGIN system outage performance. To accomplish this, we consider exponential model for modeling the correlations between the apertures. Moreover, to account for the spatial correlation for different diversity orders in the air-to-ground as well as air-to-air communications, we employ a multivariate Gamma–Gamma (\(\varGamma \varGamma\)) distribution. The results of the analysis appropriately quantify the effects of the atmospheric turbulence-induced fading as well as correlation on the system outage performance.