Time Alignment Management for 5G Small Data in RRC Inactive State
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Solution Overview
Problem
The 5G NR RAN faces inefficiencies in managing time alignment for user equipment (UE) in the RRC_INACTIVE state, leading to unnecessary power consumption and signaling overhead due to frequent connection setups for small data transmissions, as existing technologies do not support data transmission in this state without transitioning to RRC_CONNECTED.
Innovation Solution
A method for user equipment (UE) and network nodes to manage time alignment (TA) configurations, including receiving TA-related configurations based on current beam, detected reference signals, and configured grant settings, allowing for small data transmission in a non-connected state by determining and applying valid TA configurations, and handling TA invalidation during transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UE transitions to RRC_CONNECTED state for small data transmission, then data transmission can be performed, but power consumption and signaling overhead increase
Solution Approach 1:
The network node performs preliminary actions by configuring and activating small data transmission resources for the UE in RRC_INACTIVE state before actual data transmission occurs. This includes pre-configuring downlink and uplink resources, establishing timing alignment, and setting up measurement configurations, so that when data needs to be transmitted, the UE can do so directly in INACTIVE state without first transitioning to CONNECTED state, thereby reducing power consumption while maintaining data transmission capability
2Productivity
If UE transitions to RRC_CONNECTED state for small data transmission, then data transmission can be performed, but signaling overhead increases
Solution Approach 1:
The network node performs preliminary configuration of small data transmission resources including downlink and uplink resource allocation, timing alignment parameters, and measurement configurations before the UE needs to transmit data. This preliminary setup eliminates the need for complex state transition signaling and resource allocation procedures, reducing signaling overhead while enabling data transmission in RRC_INACTIVE state
Solution Approach 2:
The invention extracts the essential data transmission functionality from the RRC_CONNECTED state and makes it available in RRC_INACTIVE state by separating the core data transmission procedures from the full connection establishment procedures. This allows small data transmissions to occur without requiring the complete RRC connection setup, thereby reducing signaling overhead
3Reliability
If multiple TA related configurations are provided for different beams and reference signals, then TA validity can be accurately determined, but configuration complexity increases
Solution Approach 1:
The network node provides different TA related configurations tailored to specific local conditions, such as different beams, reference signals, and their associated parameters (RSRP, RSRQ, SINR thresholds). Each configuration is optimized for its specific local context, allowing the UE to determine TA validity accurately for each beam and reference signal combination while managing complexity through localized rather than global configuration
Solution Approach 2:
The system dynamically selects and applies the appropriate TA related configuration based on current measurement conditions. The UE measures current RSRP, RSRQ, and SINR values and dynamically determines which configuration applies, allowing flexible adaptation to changing radio conditions without requiring all configurations to be actively maintained simultaneously, thereby managing complexity
Data Source
AI summary
The present disclosure is related to methods, user equipments (UEs), and network nodes for managing time alignment (TA). The method at a UE for managing TA related configuration comprises: receiving, from a net-work node, one or more TA related configurations; determining a TA related configuration from the received one or more TA related configurations at least partially based on at least one of a beam in which the UE is currently camped, a reference signal which is currently detected by the UE, and a configured grant (CG) configuration which is currently applied at the UE; and applying the determined TA related configuration.