## 9 Future Outlook toward 6G-Era
### NTNs in 3 GPP Releases 18 and 19  
Enhancements in 3 GPP Release 18 (Rel-18) for NTNs encompass support for frequencies above 10 GHz, integration with 3 GPP New Radio (NR), improved mobility management, handover procedures, power-saving features, and enhanced security and reliability [12; 148]. These improvements are projected to facilitate diverse use cases, including global broadband connectivity, support for remote and underserved areas, disaster relief, connected vehicles, drones, and Industrial IoT. Furthermore, Rel-18 is expected to introduce the option to disable Hybrid Automatic Repeat Request (HARQ) feedback for NTN IoT by default, which can significantly improve throughput for devices with sporadic data traffic. In the context of Release 19 (Rel-19), support for satellite-based 3 GPP communication implies the availability of a backhaul network between the radio access node and the core network, as well as the wireless device's ability to utilize existing Global Navigation Satellite System (GNSS) functionality [149]. For the Rel-19 discussion, 3 GPP will explore scenarios involving discontinuous backhaul connections. For example, a satellite could regularly orbit Earth and receive data from a location without direct transmission. In this scenario, it is necessary for satellite communication to have hold-and-forward capabilities. Figure 4: Overview of planned 3 GPP standard releases on NTN. While devices may use a 3 GPP-based satellite communication architecture to determine their location in certain scenarios, the primary driver behind the upcoming 3 GPP specifications for NTNs is the development of direct links with both user equipment (UE) and IoT devices. In addition, Rel-19 is projected to integrate support for ambient power-enabled remote IoT devices, enabling them to harvest energy from their surroundings to power their operations. Apart from this, the Hold-and-Forward (HF) feature, which is also expected and being studied in Rel-19, is designed to overcome the issues of latency and reliability that are commonly encountered in satellite communications as it enables the satellite to temporarily hold data packets prior to their transmission to the ground station. Consequently, the hold-and-forward technique plays a crucial role in guaranteeing the integrity of data in challenging and remote conditions by storing packets that could potentially be lost as a result of interference or obstacles. The scientific community has consistently emphasized that adherence to the 3 GPP standards for NTNs is crucial to the successful implementation of future enterprise strategies [150]. This recognition of NTN's significance as a key work item and research area within the 3 GPP has attracted a growing number of companies seeking to participate in this burgeoning field. However, the organization is actively exploring potential collaborations with emerging space companies and established corporate entities to harness the potential of 3 GPP-based NTNs and expand their reach. Energy Efficiency Challenges  
In 3 GPP Rel-18, significant focus has been directed towards enhancing the energy efficiency of NTNs [12]. These enhancements are intended to reduce power consumption in NTN base stations and user UEs while maintaining or even improving overall performance. One noteworthy improvement involves refining beamforming techniques, enabling more precise targeting of signals from NTN base stations towards UEs. This targeted signal delivery minimizes the power required for data transmission and reception. Furthermore, introducing new power-saving modes for NTN UEs is another crucial addition. These modes allow UEs to conserve power during periods of inactivity or when data transmission or reception is not actively in progress. In addition, network-assisted power management is incorporated to assist UEs in effectively managing power consumption. The network will provide valuable information about traffic conditions and available energy sources, empowering UEs to optimize their power usage efficiently [151].