5G Non-Terrestrial Networks (NTN): Integration into 5G NR

Describe how 5G uses PDU sessions over IP to deliver services, with multiple QoS flows identified by QoS IDs, each differing in data rate, latency, and priority.

Link PDU session from user equipment to 5G core via UPF, mapping each QoS flow to a radio bearer on the Nr interface through a transparent payload based satellite transponder.

Explains the PDU session in regenerative payload-based 5G NTN, with on-board Gnp and Nr interface to the satellite, plus next-generation core interface, mapping QoS flows to bearers and tunnels.

Explore PDU sessions in regenerative NTN with split GNP, ground GNP central unit and on-board GNP distributed unit, mapping QoS to radio bearers and the user plane function via F1.

Explore 5g dual connectivity where a user equipment links to two ndbs, with a master and a secondary node across terrestrial and non-terrestrial networks.

Explore how dual connectivity between an NTN gNB with a transparent payload and a terrestrial gNB enables data split over the x n interface, preserving continuous coverage in underserved areas.

Explore connectivity between NTN gNBs with a transparent payload, where one acts as master and the other as secondary, connected to the 5G core for wide coverage and low latency.

Describes a dual connectivity setup where a regenerative payload satellite hosts the NB distributed unit, linking to the terrestrial gNB to enhance coverage and reduce latency versus transparent payload.

Describe dual connectivity between an NTN gNB-DU with regenerative payload and a terrestrial gNB, where central and distributed units are onboard, lowering latency and cost.

Explore dual connectivity in 5g NTN, where non-terrestrial satellites with regenerative payloads connect via x n interfaces, enabling data split and master-node options between leo and geo satellites.

Explore mobility between terrestrial networks and non terrestrial networks, including primary and secondary connections with gnb, leo and geo satellites, and scenarios for pedestrians, vehicles, planes, and ships.

5g non-terrestrial networks favor circular polarization to resist Faraday rotation and satellite rotation. A circularly polarized antenna at the receiver detects RHCP or LHCP waves.

Understand how 5G tracking areas partition cells, idle mode location, and when tracking area updates versus paging affect network signaling load; balance area size for optimal performance.

Explore moving versus fixed tracking areas in 5g ntn. Moving areas travel with the satellite, increasing signaling load from area updates; fixed areas adjust to geography with changing area codes.

Compare hard and soft switch in fixed tracking area updates for 5G NTN: hard switch boosts border updates, soft switch reduces them but increases paging load.

Explore how mobility procedures in 5G non-terrestrial networks differ from terrestrial networks, showing that handover and cell selection require location-based or time-based conditions beyond signal strength.

System information block 19 defines a reference location and a distance threshold for mobility control. If within threshold, UE avoids mobility actions; t service requires mobility before expiry.

Learn how conditional handover in 5g ntn lets the user equipment autonomously trigger handover when execution conditions are met, using configurations from source and target gnps.

Explore how physical cell IDs are derived in 5G NTN from the SSB and synchronization sequences, how NID one and NID two yield PCI (0–1007) and planning across beams.

Explore PCI planning fundamentals by contrasting collision-free and confusion-free principles, showing why neighboring cells must use distinct PCI values and how PCI reuse distance prevents misidentification and handover errors.

Earth-fixed cells use fixed tracking area codes and PCI values, while earth-moving satellites risk PCI conflicts; resolve by unique PCI assignments or grouped reuse, with the Xn interface for detection.

Explain the feeder link switchover in 5G NTN, switching from the source to the target gateway as a satellite nears the threshold, avoiding disruptions with soft and hard switchover.

Explore soft feeder link switchover in 5g ntn, where a transparent leo satellite connects to two gateways during transition, broadcasting both pcis and enabling blind or time-based handover.

Explain hard feeder link switchover in transparent LEO NTN, switching from gateway one to gateway two and triggering conditional handover of UEs from NB1 to NB2, with PCI changes.

Examine how a regenerative satellite with a full gnb on board performs feeder link switchover between gateways, broadcasting the same PCI, preserving security keys, and remaining transparent to user equipment.

Define uplink synchronization in 5g networks and explain how timing advance compensates two-way propagation delay to align uplink with downlink at the base station, and timing advance offset in tdd deployments.

Analyze uplink synchronization in 5G NTN, focusing on a Leo satellite at 600 km and its changing propagation delay, and timing advance requirements for transparent payloads.

Explain how timing advance for 5G NTN with transparent payload combines feeder-link and service-link advances, and how NTN uses open-loop timing advance unlike terrestrial closed-loop timing advance.

Explore open-loop timing advance in 5g nr for ntn, detailing common timing advance on feeder link to satellite and ue-specific timing on the service link, with epoch-time and drift-rate parameters.

Explore how the user equipment specific timing advance is computed from the UE and satellite locations, using GPS and ephemeris data in two formats: state vectors and orbital parameters.

Explore uplink synchronization for 5g non-terrestrial networks, detailing reg access, random access procedures, and RRC connected timing using SSB, MCB, core sets, and MAC timing advance.

Explain the validity duration of open-loop timing advance parameters, including common timing advance and satellite ephemeris data, and how a period reduces user equipment processing by aligning with SSP blocks.

K2 offset aligns uplink timing with downlink control information in 5G NTN, while K offset, including cell-specific and UE-specific values, optimizes scheduling via SIB 19 and PUSCH timing.

Explore the HARQ mechanism in 5G NR for non-terrestrial networks, combining forward error correction with ARQ at the MAC, using transport blocks and retransmission.

Explore HARQ stalling in 5G NTN caused by long propagation delays and limited hard processes, and learn solutions like disabling HARQ feedback or increasing HARQ processes with ARC/RLC retransmission.

Compute the minimum HARQ processes by summing TSF, t_g, t_h, and processing times, using half-round-trip times for transport and ACK across LEO, MEO, GEO, then divide by slot duration.

Examine how 5g ntn adjusts harq processes for leo and geo satellites, with the g node b signaling 32 and 600 to the user equipment via downlink control information.

Enable signaling between gNB and user equipment via mac control elements, with mac c commands carried in mac transport blocks and delayed by k_mac after haq to align downlink timing.

3GPP's working groups structure 5G specifications into radio access, core and terminals, and service and system aspects, covering layers 1-3, interfaces, maintenance, radio performance, core protocols, and non-terrestrial networks.

Examine 3GPP releases 17 and 18 for 5G NTN, detailing how four working groups address transparent payload type architecture, RAN timing and synchronization, user-plane protocols, SIP 19, and satellite backhauling.

Explore how release 18 groups develop 5G non-terrestrial network specifications. Inspect study and work items, including radio enhancements, narrowband internet of things, enhanced machine type communication, and satellite backhaul.