Timing Advance Range Extension via Segmented NTN Offsets
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Solution Overview
Problem
Existing 5G NR systems face challenges in extending the range of timing advance (TA) to compensate for propagation delays in non-terrestrial networks (NTN) due to satellite distances exceeding the maximum allowed TA range, leading to unsynchronized user equipment (UE) and potential interference.
Innovation Solution
Implicitly providing timing advance (TAd) offsets through various methods, such as time/frequency dependent offsets, DCI allocation, multiple ra-responseWindow timers, and different T-CRNTI ranges, to enhance TA range without altering the RAR message format.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the timing advance range is extended to compensate for propagation delays in non-terrestrial networks, then the coverage distance is improved, but the RAR message format complexity increases
Solution Approach 1:
The timing advance offset is segmented into two parts: a common timing advance offset applied to all UEs in the NTN cell, and a UE-specific differential timing advance offset. This segmentation allows the common offset to handle the bulk of the propagation delay compensation for satellite distances, while the differential offset handles finer adjustments, thereby extending coverage without requiring a complete overhaul of the RAR message format
Solution Approach 2:
Different timing advance offset characteristics are applied to different UE locations and scenarios. UEs closer to the satellite receive smaller differential offsets, while UEs at the cell edge receive larger differential offsets. This local differentiation enables precise timing synchronization across extended distances while maintaining compatibility with existing RAR message structures
2Adaptability or versatility
If implicit timing advance offsets are provided through multiple methods, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The common timing advance offset is pre-calculated and broadcast to all UEs in the NTN cell before random access procedures begin. This preliminary action allows UEs to apply the common offset immediately, reducing the burden on the UE-specific differential offset and simplifying the overall offset management while maintaining high adaptability
Solution Approach 2:
The differential timing advance offset acts as an intermediary that bridges the gap between the common timing advance offset and the precise timing requirements of individual UEs. This intermediary mechanism provides flexible adaptation to different UE scenarios without requiring complex reconfiguration of the entire timing advance system
3Ease of manufacture
If the TA range is expanded without altering the RAR message format, then the ease of manufacture is improved, but the measurement precision may be reduced
Solution Approach 1:
The common timing advance offset handles the majority of the timing advance requirement for NTN scenarios, allowing the differential offset to use a smaller, more precise range. This partial action approach maintains high precision for UE-specific adjustments while enabling extended overall coverage, all within the existing RAR message format constraints
Data Source
AI summary
A method may include sending, by a user equipment, a random access preamble message to a network element. The method may also include receiving an uplink grant in a random access response message in response to the random access preamble message. The method may further include adding an implicit timing advance offset to an uplink time domain resource allocation of the uplink grant to establish synchronization of radio transmissions between the user equipment and the network element. The method may also include transmitting a scheduled transmission message including the implicit timing advance offset to the network element. Further, the implicit timing advance offset may be added to the uplink time domain resource before the scheduled transmission message is transmitted.