RRC Inactive Small Data Transmission With DL-RSRP-Based UL Grants
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Solution Overview
Problem
The need for improved wireless communication methods in next-generation systems like 5G NR for small data transmission in a radio resource control (RRC) inactive state is not adequately addressed, particularly in handling uplink configured grants and random access procedures.
Innovation Solution
A method and device for performing small data transmission (SDT) in a RRC inactive state by configuring multiple uplink Configured Grant (UL-CG) configurations with DL-RSRP thresholds, allowing UEs to select and apply appropriate UL-CG configurations based on measured DL-RSRP, and initiating random access procedures when necessary, with mechanisms for timer management and mobility handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single UL-CG configuration is used for SDT in RRC inactive state, then the configuration is simple, but it cannot adapt to varying downlink signal conditions and may fail when DL-RSRP is below threshold
Solution Approach 1:
The patent divides the single UL-CG configuration into multiple configurations (first UL-CG configuration, second UL-CG configuration, etc.), each associated with different DL-RSRP thresholds. This segmentation allows the system to handle different signal conditions with appropriate configurations, improving adaptability while managing complexity through structured division.
Solution Approach 2:
The patent implements dynamic selection of UL-CG configurations based on measured DL-RSRP values. The UE dynamically chooses which configuration to use by comparing measured DL-RSRP against threshold values, allowing the system to adapt to changing radio conditions without requiring complex reconfiguration procedures.
2Reliability
If multiple UL-CG configurations are provided for different DL-RSRP conditions, then adaptability improves, but the UE must measure and compare multiple thresholds increasing processing complexity
Solution Approach 1:
The network pre-configures multiple UL-CG configurations with associated DL-RSRP thresholds before the UE enters RRC inactive state. This preliminary action allows the UE to simply compare measured DL-RSRP against pre-defined thresholds during SDT, reducing real-time processing complexity while maintaining high reliability through appropriate configuration selection.
3Loss of time
If the UE stays in RRC inactive state for small data transmission, then connection establishment time is reduced, but random access procedures may be needed increasing latency
Solution Approach 1:
The patent introduces configured grant resources as an intermediary mechanism that allows data transmission in RRC inactive state without full random access procedures. When DL-RSRP conditions are favorable, the UE can use pre-configured uplink resources directly, bypassing lengthy connection establishment while maintaining transmission efficiency. Random access is only invoked when necessary.
Data Source
AI summary
A method for a user equipment for performing a small data transmission (SDT) procedure is provided. The method includes receiving, from a base station, an SDT configuration including a plurality of uplink configured grant (UL-CG) configurations for the SDT procedure, each of the plurality of UL-CG configurations being associated with a downlink reference signal received power (DL-RSRP) threshold; applying one of the plurality of UL-CG configurations for the SDT procedure in a case that a DL-RSRP measurement result of a synchronization signal block (SSB) associated with the one of the plurality of UL-CG configurations is higher than one of a plurality of DL-RSRP thresholds; and initiating, during the SDT procedure, a random access (RA) procedure in a case that none of a plurality of DL-RSRP measurement results of a plurality of SSBs associated with the plurality of UL-CG configurations is higher than any of the plurality of DL-RSRP thresholds.