Multidirectional all-optical precompensation and forward relay for HAPS-assisted free-space optical communications

Abstract

This study introduces an all-optical multidirectional channel precompensation method for use in HAPS-assisted FSO scenarios. The proposed method leverages two or more automatic power-control erbium-doped fiber amplifiers (APC-EDFAs) to achieve the compensation and precompensation of multiple arbitrary channels in an all-optical manner, utilizing the cross-gain modulation characteristics of the APC-EDFA. The performance of the proposed method is theoretically and numerically analyzed. The results indicate a significant increase in the average output power of the relay node as well as a reduction in the power fluctuation at the receiver. Consequently, an enhanced bit error rate performance is observed when compared with that of conventional all-optical relays; however, the average pump power used for each relay node is decreased.