# A Review of SATis5: Perspectives on Commercial and Defense 5G SATCOM Integration
## 7 Discussion and Conclusions  
Our survey results presented here have captured a wide range of SATis5 efforts that are fully complied with 3 GPP/5G-NTN standards and specifications. Specific SATis5 architectures for eMBB and mMTC-NB-IoT were discussed. The outlooks on potential SATis5 architectures were provided. As discussed above, the outlooks were derived based on separate SATCOM enterprise perspectives. For the COMSATCOM perspective, the outlook provided in Section 6.1 comprises 3 GPP/SATis5 architecture standards and the roadmaps. The outlook for COMSATCOM can be extended to civilian SATCOM applications. From the defense SATCOM perspective concerning the use of MILSATCOM services integrated with 5G technologies, the outlook for long-term vision is the development of an emerging business model. This is an enterprise model that allows a cost-effective approach for accessing a virtual \"unified integrated enterprise infrastructure\" (IEI). The virtual IEI can support a wide range of user types. The IEI can be viewed as a unified enterprise infrastructure that virtually connects civilian, commercial, and defense SATCOM systems with all future global 5G networks. This IEI can also be envisioned as a \"virtual\" enterprise satellite network (EnVSaN) providing diverse communication services, including land, air, sea, and space, to support various user types. The EnVSaN would include all desired VNFs and related edge computing functions to support all global communications services for all user types. To achieve this long-term vision, the following investigations and studies are recommended:  
* Investigate implementation approaches of the new 5G-NR air interfaces for existing and planned defense SATCOM payloads taking into consideration (i) Direct and Non-Direct access satellite links, (ii) satellite payload size-weight-power-and-cost (SWAP-C), (iii) MILSATOM users' QoS and Quality of Experience (QoE), (iv) satellite operation requirements and resource constraints, (v) 5G-UE SWAP-C, (vi) 5G users' QoS and QoE, and (vii) Battery life of 5G UE and satellite user terminal. The key technical area is the modification of existing 3 GPP 5G-NR PHY/Datalink/MAC layers taking into account the long RTT associated with MILSATCOM satellites. These layers include waveforms, data formats, and data frames, time synchronization, RRC timer procedure, RAR time window size, and timing advance. * Study implementing approaches for modifying the 5G-NR air interfaces for defense SATCOM satellites at NTN-NT-UE and NTN-LT/5G-gNB which can allow the SATCOM users and 5G users access to 5G-NGC and hence data networks. The key technical task is the incorporation of the existing ComPEMaC technique into the MILSATCOM payloads and 5G-Gateway based on the channel quality reported by either 5G-UE or MILSATCOM user terminals. * Examin existing 5G-NGC's CP, including but not limited to AMF, SMF, UDM, PCF, and UPF, and propose control plan modifications taking into consideration of the newly modified 5G-NR air interfaces for defense SATCOM satellites. * Develop innovative cost-effective business models which are derived based on the IEI perspective incorporating (i) Cost of IEI deployment, (ii) Cost of enterprise network maintenance and operations, (iii) Revenues for SATis5 services' providers and related vendors, (iv) Government cost saving for using SATis5 services and meeting defense mission needs, and (v) 5G and MILSATCOM users' QoS and QoE. There is another study that is of interest to both commercial and defense users, this is the integration of GNSS with 5G networks. This study recommends focusing on providing PNT services to global 5G-UE and defense SATCOM user terminals in remote areas. Finally, the wireless communication industry is currently working on 6G addressing the proliferation of data-intensive applications that are not fully tackled by 5G systems due to limited bandwidth [33]. The emerging 6G technology offers new capabilities that eventually force the SATis5 transition to SATis6 architectures.