In the uplink, NR-DC outperforms satellite-only operation but remains below terrestrial-only performance, indicating that the benefit depends on traffic direction and transport behaviour, and an integrated terrestrial–LEO 5G network using a customised Simu5G framework.
Abstract
Terrestrial–non-terrestrial (TN–NTN) integration can extend 5G coverage, but maintaining high goodput and low delay is challenging when a 28 GHz terrestrial layer is combined with moving LEO satellites. Existing studies mainly address architectures, analytical models, or handover-based operation, leaving the system-level behaviour of NR Dual Connectivity (NR-DC) with moving satellite secondary nodes insufficiently evaluated. This paper evaluates an integrated terrestrial–LEO 5G network using a customised Simu5G framework with NR-primary master cell group (MCG) operation, dynamic satellite secondary cell group (SCG) selection, PDCP split-bearer forwarding with MCG fallback, and a hybrid TN–NTN channel model. The NR-DC configuration is compared with satellite-only and terrestrial-only baselines under identical topology, traffic, and channel settings. Results show that NR-DC improves downlink delivery: CBR goodput increases by 321.29% and 28.95% over the satellite-only and terrestrial-only baselines, respectively, with corresponding delay reductions of 71.16% and 62.75%. TCP downlink goodput also improves, although delay increases because of heterogeneous path effects. In the uplink, NR-DC outperforms satellite-only operation but remains below terrestrial-only performance, indicating that the benefit depends on traffic direction and transport behaviour.
Direct-to-cell (D2C) non-terrestrial networks (NTNs) based on 5G technology are emerging as a key complement to terrestrial cellular networks, extending connectivity to underserved and remote areas while enabling integration with existing mobile ecosystems. As these systems begin operating in frequency bands already used by terrestrial International Mobile Telecommunications (IMT) networks, coexistence becomes critical. This paper presents a victim-centric methodology for evaluating D2C interference into terrestrial 5G networks in the 694/698 MHz-2.7 GHz regulatory study range. Seven downlink carrier cases and four uplink carrier cases between 734 and 2620 MHz are evaluated. For a prescribed external interference-to-noise ratio, the external contribution is referenced to receiver thermal noise, while terrestrial intra-network interference remains part of the baseline and interfered signal-to-interference-plus-noise ratio (SINR). The resulting throughput loss is translated into candidate power-flux-density (PFD) and equivalent-power-flux-density (EPFD) protection levels. A reference non-geostationary-satellite-orbit (NGSO) system is used only to motivate the assumed receiver-exposure fractions; the numerical network results are therefore conditional on those exposure assumptions. The same external interference level produces approximately three times greater network throughput loss at base stations than at user equipment, so direction-specific protection levels are required. For downlink protection, the tested 3 dB noise-rise case gives candidate PFD levels from −109.23 to −98.17 dB(W/(m2·MHz)); for opposite-direction cross-border uplink protection, I/N = −6 dB gives candidate EPFD levels from −138.23 to −130.18 dB(W/(m2·MHz)) for non-AAS base stations. The approximately 11 dB offset for AAS cases results from the maximum-gain normalization used in EPFD and should not be interpreted as evidence of greater satellite exposure. These values are tested candidate levels rather than estimates of an exact 5% crossing point.
Low Earth orbit (LEO)-based non-terrestrial networks (NTN) are emerging as a key component of 6G systems, enabling seamless connectivity over wide geographical areas. However, in Earth-moving cell (EMC)-based NTN scenarios, rapid beam movement induces frequent cell boundary crossings, resulting in excessive handover operations and significant signaling overhead. This makes efficient mobility management a critical challenge. Recently, L1/L2-triggered mobility (LTM) and conditional LTM (C-LTM), specified in 3GPP Releases 18 and 19, respectively, have been proposed as advanced handover mechanisms to enhance mobility robustness. Despite their potential, their effectiveness in highly dynamic NTN environments has not yet been systematically evaluated. This paper presents a comprehensive system-level evaluation of 3GPP handover mechanisms in NTN, including baseline handover (BHO), conditional handover (CHO), LTM, and C-LTM. A dedicated simulator is developed to capture the unique characteristics of LEO satellite networks and realistic handover procedures under EMC conditions. The results show that schemes based on LTM and C-LTM significantly improve mobility robustness by reducing radio link failures and interruption time. However, these gains come at the cost of increased handover frequency and potentially increased signaling overhead associated with frequent mobility events and measurement reporting in EMC-based NTN environments. This reveals a fundamental tradeoff between mobility robustness and signaling efficiency. The findings provide quantitative insights into the performance of emerging 3GPP mobility solutions in NTN and offer practical guidelines for designing efficient handover strategies in highly dynamic 6G NTN environments.
Gyoungmin Been, Byung-Kwan Lim, Junsu Kim et al.· IEEE Access· 0 citations
Low Earth orbit mobile satellite system (LEO-MSS) is a major system that provides communication support for mobile terminals beyond the coverage of terrestrial communication systems. However, passive handover happens frequently, caused by the quick movement of LEO satellites, making it hard to guarantee quality of service (QoS) for handover users while maintaining a large number of users. To tackle this problem, we propose a novel soft handover scheme and combine it with uplink power-domain non-orthogonal multiple access (PD-NOMA) for the first time to guarantee QoS for handover users and improve uplink throughput. We analyze the uplink PD-NOMA-based soft handover scheme with three users in two beams and give the closed-form expression of the optimal uplink transmission power allocation. Afterward, we introduce this method into a practical multi-beam LEO-MSS system with multiple users and sub-channels and formulate the optimization problems to maximize system throughput. Numerical results show that the proposed uplink PD-NOMA-based soft handover scheme provides much better performance on throughput and fairness for heavy loads.
Hu-Lin Li, Cong Huang, Zhong-Yu Yang et al.· Telecom· 0 citations
Simulation results demonstrate that the proposed GNN-RSMA interference management algorithm outperforms conventional multiple access schemes while achieving fairness and worst-user performance comparable to successive convex approximation (SCA)-based optimization at only a fraction of its computational cost.
Afsoon Alidadi Shamsabadi, Animesh Yadav, H. Yanikomeroglu· 0 citations
In this work, we optimize unicast and multicast traffic delivery over non‐terrestrial networks (NTNs) to users on the ground through direct satellite downlink (DL). We consider a gateway‐free mesh architecture with low Earth orbit (LEO) satellites interconnected via inter‐satellite links (ISLs), where unicast and multicast services compete for both ISL and DL resources. The (E2E) problem is decomposed into: (i) a space‐segment multicast distribution problem over capacity‐constrained ISLs, modeled via Steiner‐tree approximations; and (ii) a DL resource allocation problem aligned with a 3GPP cell‐based NTN RAN model, where we formulate a demand‐aware allocation scheme for mixed multicast/unicast traffic. Results show that Steiner‐based multicast reduces ISL utilization and risk of bottlenecks, achieving up to lower load at the cost of a moderate delay increase below compared to shortest‐path unicast routing. These gains are further amplified in scenarios with spatially correlated satellites. In the DL segment, demand‐aware allocation maximizes service availability and improves throughput by up to 700% compared to a proportional fair benchmark through flexible resource allocation.
Unknown authors· International Journal of Sat...· 0 citations
Efficient Non-Access Stratum (NAS) timer configuration is critical for reliable and energy-efficient Fifth Generation (5G) registration in Non-Terrestrial Network (NTN)-Terrestrial Network (TN) integrated systems, where Low Earth Orbit (LEO) satellite access introduces large registration bursts, heterogeneous propagation paths, and multi-hop satellite routing. Existing 3GPP NAS timers use fixed values, while prior closed-form timer models compute a global timer under network-level assumptions; both fail to capture user equipment (UE)-level differences in propagation delay, Access and Mobility Management Function (AMF) arrival position, and path reliability. In this paper, we propose a location-aware, UE-specific NAS timer optimization method for LEO NTN-TN integrated networks. The proposed method models the path-delay component using service-link geometry, ground-station distance, and Inter-Satellite Link (ISL) hop count, and adapts the endpoint-delay component according to each UE's expected AMF queue exposure and path reliability. Simulation results show that our method reduces registration latency, UE energy consumption, and avoidable registration attempts compared with fixed and global timer configurations, especially when timer over-provisioning causes unnecessary waiting.
Cheng Liu, Peng Hu· arXiv.org· 0 citations
We use cookies to run the site and, with your consent, for analytics and to show ads.
See our Cookie Policy.
