NTN MAC-CE Timing Control for Ambiguous Uplink Activation
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Solution Overview
Problem
Existing 5G NR systems face challenges in accurately determining the action timing of MAC-CE commands in non-terrestrial networks due to uncertainties in timing advance and propagation delays, leading to potential ambiguities and inefficiencies in communication.
Innovation Solution
The proposed solution involves adjusting the timing of uplink transmissions based on a timing advance command received from the base station, using a common delay (Koffset) broadcast to multiple UEs and a UE-specific delay (k), and calculating the activation of MAC-CE commands based on specific slot adjustments to align with the satellite's reference point, thereby clarifying the timing relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MAC-CE command timing is determined using existing 5G NR specifications, then the system can operate with standard timing procedures, but ambiguities and inefficiencies arise due to uncertainties in timing advance and propagation delays in NTN
Solution Approach 1:
The patent modifies the timing parameters by introducing a new parameter Koffset that represents the time difference between when a MAC-CE command is received at the gNB and when it should be applied at the UE. This parameter change resolves the timing ambiguity by providing a clear reference point for when the command takes effect, eliminating uncertainties in NTN timing determination.
Solution Approach 2:
The patent applies the MAC-CE command in advance by defining the application timing as slot n+Koffset+1, where n is the slot when the command is received. This preliminary action ensures that the timing adjustment is prepared and applied before the next uplink transmission opportunity, avoiding timing ambiguities and ensuring reliable command execution.
2Productivity
If timing advance commands are applied immediately without additional delays, then uplink transmissions can start quickly, but propagation delays and processing time cause timing misalignment in NTN
Solution Approach 1:
The patent applies the timing advance command in advance by scheduling the application time as slot n+Koffset+1, where n is the reception slot. This preliminary application ensures that the timing adjustment is ready before the next uplink transmission opportunity, maintaining both speed and precision.
Solution Approach 2:
The patent introduces the parameter Koffset to represent the time difference between command reception and application. By changing the timing parameter from immediate application to delayed application by Koffset slots, the system achieves both fast transmission and precise timing alignment in NTN scenarios.
3Device complexity
If MAC-CE commands are applied without considering PDSCH-PUSCH alignment, then the command application is simplified, but timing errors occur when downlink and uplink slots are non-aligned at the base station
Solution Approach 1:
The patent modifies the command application timing based on the alignment status of PDSCH and PUSCH. When non-aligned, the command is applied in slot n+Koffset+1; when aligned, it is applied in slot n+Koffset. This parameter change based on alignment status maintains simplicity while achieving precise timing measurement and correction.
Solution Approach 2:
The patent uses the alignment information between PDSCH and PUSCH as feedback to determine the correct application timing. This feedback mechanism allows the system to adapt the command application timing based on actual network conditions, ensuring accurate timing without increasing processing complexity.
Data Source
AI summary
Some present implementations provide a method for a user equipment (UE) connected to a non-terrestrial network (NTN). The method may receive, from a base station (BS) of the NTN at a downlink (DL) slot n, a timing advance (TA) command. The method may also adjust a timing of uplink (UL) transmissions to the BS according to the received TA command. The method may also include applying the adjusted timing for the UL transmissions by performing the UL transmissions from a beginning of a UL slot n+k+1+Koffset. Koffset may be a common delay broadcast by the BS to a plurality of UEs connected to the NTN including the UE, and k may be an additional delay specific to the UE.