NTN Uplink Timing Adjustment for Satellite Delay Variation
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Solution Overview
Problem
Non-terrestrial wireless communications face significant challenges due to large propagation delays and varying round trip delays caused by the high mobility of satellites, leading to synchronization issues and inefficiencies in uplink timing adjustments.
Innovation Solution
The UE adjusts uplink transmission timing by accounting for both propagation delay and its variation, using either a gateway or satellite timing reference, with network signaling providing RTD and RTD variation information to ensure synchronized communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE uses traditional terrestrial timing advance mechanisms in non-terrestrial networks, then the system can support basic communication, but the large and varying propagation delays cause synchronization failures and communication inefficiency
Solution Approach 1:
The patent changes the timing advance parameter from a fixed terrestrial value to a dynamic value that accounts for non-terrestrial propagation characteristics. The network device determines a first timing advance value based on the non-terrestrial propagation delay, and a second timing advance value is derived by adjusting the first value based on the difference between non-terrestrial and terrestrial propagation delays. This parameter transformation enables reliable synchronization despite large propagation delays.
2Measurement precision
If the network provides detailed round trip delay and variation information to assist UE timing determination, then uplink timing accuracy is improved, but signaling overhead and system complexity increase
Solution Approach 1:
The network device acts as an intermediary that pre-calculates and provides timing advance information to the UE. Instead of requiring the UE to independently measure and calculate complex propagation delays, the network device determines the first timing advance value and provides adjustment information based on the difference between non-terrestrial and terrestrial propagation delays. This intermediary approach simplifies the UE's task while maintaining high timing accuracy.
3Stability of the object's composition
If the system accounts for propagation delay variation due to satellite movement, then uplink timing synchronization is maintained, but the complexity of timing adjustment mechanisms increases
Solution Approach 1:
The patent implements dynamic timing adjustment to accommodate satellite movement. The network device determines timing advance values that account for varying propagation delays caused by satellite motion. The second timing advance value is dynamically adjusted based on the difference between non-terrestrial and terrestrial propagation delays, enabling the system to maintain synchronization stability despite the dynamic nature of satellite-based communications.
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described in which UEs may communicate with satellites and base stations or gateways in a non-terrestrial network (NTN). Due to the large distances between transmitting devices and receiving devices in a NTN, timing adjustments to account for propagation delay communications links via a satellite may include a propagation delay between a UE and a satellite, a propagation delay between a base station and a satellite, as well as a variation in the propagation delays due to movement of the satellite. In accordance with various techniques discussed herein, a UE may account for variation in propagation delay, in addition to determined propagation delay, when determining an uplink timing for uplink communications via a satellite.