## 6 Conclusions and Future Research
As a summary, the FeDeCoP provides a reliable communication while trying to achieve the maximum throughput. Despite these characteristics, this campaign also helped to identify **future enhancements** of the protocol. Regarding the throughput, other ARQ techniques can be applied to optimize the available capacity of the channel, such as Go-back-N or selective ARQ. Although the absolute values of the achieved throughput (hundred of bps) may not be suitable for satellite applications, the percentage of measured throughput with respect to its maximum value encourage to apply FeDeCoP with devices that provide larger data rates. In this case, the absolute performance could have potential interest for satellite data. Additionally, the results present large RTT values in federations due to retransmissions and the existence of an intermediate node. This indicates that the implementation of the protocol may not be optimal. Specifically, the use of no-real-time threads has been key on this behavior, which must be improved in future implementations. Finally, the use of an omnidirectional antenna in the balloon limited the maximum communication range due to its gain, and the reception of interferent signals. This type of antenna was selected to mitigate the rotation of the balloon. In this case, the separation of a control and a data planes could benefit. Combining decoupled and independent planes it is then possible to isolate network managing tasks and traffic, which is used to optimize the data transmission on the other plane. Therefore, the control plane could provide omnidirectional patterns with long range techniques and low data rates. Meanwhile, the data plane would ensure large data rate and long range using directive antennas. The benefits of using this configuration for satellite federations has already been highlighted in a previous work [15]. Different conclusions and future approaches for FeDeCoP have been extracted from the campaign. Table 2 summarizes them by highlighting the relevant concepts of this manuscript. This stratospheric balloon campaign has become a demonstrator of the FeDeCoP and OSADP capabilities to deploy federations. These results encouraged to integrate the FSSExp payload with the OSADP and FeDeCoP protocols in the FSSCat mission [24]. This mission aims at demonstrating the benefits of applying the FSS concept to EO missions. In this mission, multiple payloads are distributed in two 6U CubeSats, known as \({}^{3}\)Cat-5/A and \({}^{3}\)Cat-5/B include the Flexible Microwave Payload-2 [25] a dual L-band microwave radiometer and GNSS-Reflectometer, and HyperScout-2 [26] a VNIR and TIR compact hyperspectral imager. which orbit following a train formation (i.e., one after the other). Additionally, to those EO payloads, both spacecraft include as technology demonstrator an Optical ISL (OISL) for CubeSat platforms [27] and the FSSExp payload. On 3 September 2020 both satellites were correctly launched, and they are in the operational phase. Apart of this CubeSat mission, the FeDeCoP and OSADP protocols need still to be studied in other scenarios in which considerable transmission time may impact their performance, such as interactions between Low Earth Orbit (LEO) and Geostatonary (GEO) satellites. The achieved results will be followed by future research to deploy federations in space. All authors have read and agreed to the published version of the manuscript. This work has been (partially) funded by \"CommSensLab\" Excellence Research Unit Maria de Maeztu (MINECO grant MDM-2016-0600), the Spanish Ministerio MICINN and EU ERDF project \"SPOT: Sensing with pioneering opportunistic techniques\" (grant RTI2018-099008-B-C21/AEI/10.13039/501100011033), by the grant PID2019-106808 RA-100/ AEI/FEDER/UE from the EDRF and the Spanish Government, and by the Secretaria d'Universitats i Reecerca del Departament d'Empresa i Coneixement de la Generalitat de Catalunya (2017 SGR 376, and 2017 SGR 219). Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.