CG-SDT Random Access Retransmission for Inactive UE Latency Recovery
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Solution Overview
Problem
The existing Configured Grant Small Data Transmission (CG-SDT) procedure in NR is prone to resource wastage and latency due to frequent periodicity configurations, leading to potential transmission failures without immediate recovery options, especially for low-priority UEs.
Innovation Solution
Introduce the capability for User Equipment (UE) to perform a Random Access (RA) procedure during ongoing CG-SDT when specific criteria are met, such as no response received within a certain time and the next CG occasion being too far off, allowing retransmission of data without waiting for the next scheduled occasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CG-SDT uses frequent periodicity configurations, then resource utilization is improved, but transmission reliability deteriorates due to potential failures without immediate recovery options
Solution Approach 1:
The patent introduces dynamic behavior to the CG-SDT procedure by allowing UEs to autonomously switch from configured grant transmission to random access procedure when transmission failures are detected. This dynamic adaptation enables the system to maintain high resource utilization through frequent CG-SDT periodicity while ensuring transmission reliability through immediate recovery via random access when failures occur, thus resolving the contradiction between productivity and reliability.
2Productivity
If CG-SDT uses frequent periodicity configurations, then data transmission efficiency is improved, but latency increases due to waiting for next scheduled occasion upon failure
Solution Approach 1:
The patent implements a mechanism where UEs can skip the waiting period for the next scheduled CG-SDT occasion by initiating a random access procedure immediately upon detecting transmission failure. This allows the system to rush through the recovery process without adhering to the fixed periodicity schedule, thereby maintaining high data transmission efficiency while minimizing latency penalties associated with transmission failures.
3Loss of energy
If CG-SDT occasions are spaced further apart, then resource wastage is reduced, but latency increases for retransmission of critical data
Solution Approach 1:
The patent enables dynamic recovery behavior that allows the system to use spaced-out CG-SDT occasions (reducing resource wastage) while maintaining low retransmission latency through immediate random access initiation upon failure detection. The UE autonomously decides to switch to random access procedure when transmission failure is detected, eliminating the need to wait for the next CG-SDT occasion and thus resolving the contradiction between resource efficiency and retransmission speed.
4Device complexity
If CG-SDT is used without random access capability, then device complexity is reduced, but adaptability deteriorates when transmission failures occur
Solution Approach 1:
The patent implements a self-service mechanism where the UE autonomously monitors its own transmission status and independently decides to initiate a random access procedure when failure is detected, without requiring complex network control or coordination. This self-service approach enhances adaptability and recovery capability while adding minimal complexity, as the UE simply needs to monitor its own transmission outcomes and switch to the standard random access procedure when needed.
Data Source
AI summary
Systems and methods are disclosed for random access during Configured Grant (CG) Small Data Transmission (SDT). In one embodiment, a method performed by a User Equipment (UE) comprises, while in an inactive state, transmitting, to a network node, a Radio Resource Control (RRC) Resume Request with first data using a CG occasion from among a plurality of CG occasions configured for the UE and determining that one or more criteria for performing a Random Access (RA) have been satisfied. The method further comprises, responsive to determining that the one or more criteria for performing a RA have been satisfied, performing a RA during which the UE retransmits the RRC Resume Request with the first data. In this manner, the UE does not have to wait for the next CG occasion to send a retransmission or time critical data, e.g., in the case of failure of the initial transmission.