## 6 Conclusions and Future Research  
Presently, the environmental, and socio-economic demands are requesting the development of new satellite applications that provides accurate, and near-real-time information. For that reason, new satellite architectures have emerged to satisfy these demands. The FSS paradigm promotes the collaboration between satellites, known as a federation, to share unused resources, such as storage capacity or downlink opportunities which are presently becoming critical in Earth Observation missions. However, satellite dynamics make that direct point-to-point communications (i.e., the ISL) are available during a specific lapse of time. This behavior limits thus the establishment of a federation to these periods [23]. Figure 19: Sequence of packets exchanged in federations for storage. Figure 20: Buffer usage of Balloon A (blue) and Balloon B (red) during the federation for storage (data packet unit). The IoSat paradigm aims at addressing this situation by promoting the establishment of temporal networks between satellites following the opportunistic nature of the federations. Both approaches pose multiple technology challenges that need to be solved before they can be used in the space. One of those challenges is related to the establishment and properly management of a federation. Please note that due to the opportunistic nature of the federation, traditional techniques cannot be applied directly, as in [16]. For that reason, this work has presented the protocol FeDeCoP, which enables the deployment of federations by executing an initial negotiation between the satellites. This negotiation becomes crucial because the amount of resources to be shared is agreed between the satellites. After this negotiation, the federation is established, and the resources consumed according to its type. The OSADP and the FeDeCoP protocols compose the federation protocol suite, which enables the deployment of federations in a network. The proposed protocols have been evaluated in a realistic scenario with three stratospheric balloons. These balloons were launched sequentially to assess the capabilities of the protocols when balloons were on the ground, raising, and flying. The variability of the scenario helped to achieve the following conclusions: (1) the coverage of a ground station is enhanced employing the proposed protocols with federations as data relays; (2) the proposed protocols can balance the storage usage by sharing data among the balloons; and (3) the proposed protocols establish federations between ground devices and balloons to forward data, extending the original FSS concept to a hybrid network of terrestrial and non-terrestrial nodes. The metrics retrieved from the campaign enable the quantification of the performance of the proposed protocols in a real environment. Among them, the PER metric characterizes the number of packets that the protocols cannot correct, and they are discarded or lost. It is driven by the quality of the communications channel. Despite the unexpected radio frequency interference which increased the PER, the proposed solution could establish federations thanks to its ARQ procedure. In all cases, the FeDeCoP protocol was able to detect and correct erroneous bits that allowed the correct delivery of more than a third of the data packets. Its robustness against channel effects has been demonstrated. In contrast, the RTT of the packets increases due to the large number of retransmissions. The resulting absolute throughput remained always bounded between 96.2 bps and 184.7 bps for download-based federations, and 107.6 bps for storage-based ones. Despite these absolute values may not be suitable for current satellite needs, if they are evaluated considering the channel environment (reflected on the PER) the achieved throughput was enclosed between 49.2% and 63.0% of its maximum value for download-based federations, and 94.4% for storage-based ones. This concludes that the proposed solution can achieve at least half of its maximum throughput depending on the channel conditions.