5th meeting
precomputation improvement
papers on delay models
(04/jul/2025)
precomputation improvement
Commit Link: https://gitlab.com/thiagomiyazaki/nr-ntn-dev/-/commit/4df9654969588cea302d9a52e108e2ce3e4e206e
precomputation improvement
precomputation improvement
t = 0
t = 1
Commit Link: https://gitlab.com/thiagomiyazaki/nr-ntn-dev/-/commit/4df9654969588cea302d9a52e108e2ce3e4e206e
precomputation improvement
1 plane - 16 satellite nodes
precomp. improvement
previous implementation
delay models
PropagationDelayModel in ns-3
delay models
Implementation of a Channel Model for Non-Terrestrial Networks in ns-3
Conclusions
(...) As part of our future work, we plan to further extend our NTN module to incorporate additional functionalities, for example a delay model able to accurately characterize the propagation time (...)
delay models
Ns3 meets Sionna: Using Realistic Channels in Network Simulation
Abstract
Network simulators are indispensable tools (...) to simulate real-world network behavior. However, traditional simulators, such as the widely used ns-3, exhibit limitations in accurately modeling indoor and outdoor scenarios due to their reliance on simplified (...) models, which often fail to accurately capture physical phenomena like multipath signal propagation and shadowing by obstacles in the line-of-sight path. We present Ns3Sionna, which integrates a ray tracing-based channel model, implemented using the Sionna RT framework, within the ns-3 network simulator. (...) Additionally, a mobility model based on ray tracing was developed to accurately represent device movements within the simulated 3D space. Ns3Sionna provides more realistic path and delay loss estimates for both indoor and outdoor environments than existing ns-3 propagation models, particularly in terms of spatial and temporal correlation. Moreover, fine-grained channel state information is provided, (...). This enables the efficient simulation of scenarios with a small to medium number of mobile nodes.
delay models
Modeling and simulation for delay estimation of a generic packet transferred in a satellite data network
I was not able to access this one: https://journals.sagepub.com/doi/10.1177/00375497251322572
Abstract
This article presents the findings of a simulation model designed to elucidate the delays experienced within a satellite data communication network. (...) The analysis focuses on Geostationary orbit (GEO) satellites, using the Ku-band (…). This simulation model estimates the average response time for a generic packet (“ping”) to travel through this network and its probability distribution in the total delay. This analysis considered some fixed and predefined values, such as the outbound carrier rate, the packet size, the satellite delay, and also some others that are influenced by the condition of the equipment (...).
delay models
Delay in Multi-link Operation in ns-3: Validation and Impact of Traffic Splitting
Abstract
Wi-Fi is evolving towards enhanced support for real-time applications such as video conferencing and virtual reality (VR) gaming. The latest IEEE 802.11be draft standard introduces various advancements including multi-link operation (MLO) at the medium access control (MAC) layer. Such multi-link operation (effectively carrier aggregation) is anticipated to increase data throughput, and reduce access delay. Notably, the recent release of the ns-3 network simulator (ns-3.41) incorporates an implementation of MLO, enabling novel simulation-based analysis on the potential impact of link scheduling strategies on network delay. This paper begins with validation of end-to-end delay for the MLO implementation in ns-3 in a baseline scenario, (...).
delay models
TR 38.811 - Study on New Radio (NR) to support non-terrestrial networks
delay models
TR 38.811 - Study on New Radio (NR) to support non-terrestrial networks
https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=3234
7.1 Specific constraints associated to NTN
Propagation Delay Characteristics
Satellite systems feature much larger propagation delays than terrestrial systems. The one-way delay between the UE and the RAN (whether on-board the satellite/HAPS or on the ground) may reach up to 272.4 ms for GSO (Geostationary Synchronous Orbit) systems, and is greater than 14.2 ms for NGSO (Non-Geosynchronous Orbit) systems. In the case of HAPS, the one way delay is less than 1.6 ms and hence comparable with cellular networks. This larger delay will likely impact all signalling loops especially at access and transport (data transfer) levels. The analysis of the propagation delay is detailed in clause 5.3.��
7.2 NR features/protocols potentially affected
Propagation Delay Characteristics - Physical Layer, Access Layer (MAC, RLC)
(...)��
delay models
NTN-Overview (3GPP)
Timing, Synchronization and HARQ enhancements (WG RAN1)
The network broadcasts ephemeris information and common Timing Advance (common TA) parameters in each NTN cell. (...)
To achieve uplink synchronisation, before performing random access, the UE shall autonomously pre-compensate the Timing Advance, as well as the frequency Doppler shift by considering the common TA (information from the gNB), the UE position, the satellite position and satellite velocity through the satellite ephemeris. In connected mode, the UE shall continuously update the Timing Advance and frequency pre-compensation. (...)
While the pre-compensation of the instantaneous Doppler shift (...) is to be performed by the UE for the uplink, the management of Doppler shift experienced over the feeder link is left to the network implementation.
To accommodate the propagation delay in NTNs, several timing relationships are enhanced by a Common Timing Advance (Common TA) and two scheduling offsets Koffset and kmac. Common TA is a configured offset that corresponds to the Round Trip Time (RTT) between the Reference Point (RP) and the NTN payload. Koffset is a configured scheduling offset that approximately corresponds to the sum of the service link RTT and the common TA. kmac is a configured offset that approximately corresponds to the RTT between the Reference Point (RP) and the gNB.
To mitigate the impact of HARQ stalling in NTN, the HARQ feedback can be disabled in the presence of ARQ re-transmissions at the RLC layer (e.g., in GSO satellite systems) and/or the number of HARQ processes for re-transmissions at the MAC layer can be increased to 32 (e.g., in NGSO satellite systems).
next steps
References
Propagation Delay in ns-3: https://www.nsnam.org/docs/models/html/propagation.html#propagationdelaymodel�Implementation of a Channel Model for Non-Terrestrial Networks in ns-3: https://dl.acm.org/doi/10.1145/3592149.3592158
Ns3 meets Sionna: Using Realistic Channels in Network Simulation: https://arxiv.org/pdf/2412.20524
Modeling and simulation for delay estimation of a generic packet transferred in a satellite data network: https://journals.sagepub.com/doi/10.1177/00375497251322572
NTN-Overview (3GPP): https://www.3gpp.org/technologies/ntn-overview�TR 38.811 - Study on New Radio (NR) to support non-terrestrial networks: https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=3234
Delay in Multi-link Operation in ns-3: Validation and Impact of Traffic Splitting: https://doi.org/10.1145/3659111.3659116
Sionna Framework: https://developer.nvidia.com/sionna