**5. Conclusions**

The proper understanding of the high-end hardware, protocols, techniques and schemes used in FSO-QKD systems allow to improve the performance parameters such as secret key rate, distance link, security level, among others. In particular, although there are wide suitable options for the subsystems required for FSO-QKD systems, it is necessary that the high-end subsystems are more accessible and compact in order to increase their uses in traditional optical networks.
