WTRU Dual Connectivity in RRC Inactive State
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing dual connectivity (DC) mode operations, particularly in transitioning between RRC_INACTIVE and RRC_CONNECTED states while minimizing signaling overhead and maintaining accurate DC configurations.
Innovation Solution
The implementation of systems, methods, and instrumentalities that provide system information (SI) for DC configurations applicable to the RRC_INACTIVE state, allowing WTRUs to perform mobility-related procedures, determine quality metrics, and transition to RRC_CONNECTED states based on secondary node mobility triggers, while maintaining valid DC configurations and reducing signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If WTRUs transition to RRC_CONNECTED state for data reception, then data transmission can be established, but signaling overhead increases
Solution Approach 1:
The network pre-configures WTRUs with SCG bearer information and secondary cell lists while in RRC_INACTIVE state. When data needs to be transmitted, the network can directly send data on the pre-configured SCG bearer without requiring the WTRU to transition to RRC_CONNECTED, thus avoiding signaling overhead while maintaining data transmission capability.
Solution Approach 2:
WTRUs in RRC_INACTIVE state can autonomously monitor paging messages and initiate random access procedures on secondary cells when data is available. The WTRU self-manages the data reception process on SCG bearers without requiring full connection establishment, reducing dependency on network-controlled state transitions.
2Adaptability or versatility
If WTRUs maintain DC configuration in RRC_INACTIVE state, then mobility procedures can be performed, but device complexity increases
Solution Approach 1:
The DC configuration is segmented into essential mobility parameters that are maintained in RRC_INACTIVE state and detailed connection parameters that are only activated when transitioning to RRC_CONNECTED. This allows WTRUs to perform basic mobility procedures without managing the full complexity of DC configuration, reducing device complexity while maintaining adaptability.
3Reliability
If WTRUs perform cell selection from SCG list, then data reception on SCG bearer is enabled, but measurement precision requirements increase
Solution Approach 1:
WTRUs perform measurements on a subset of secondary cells from the SCG list rather than all possible cells. The network configures a limited SCG list with cells that are most likely to be suitable, allowing WTRUs to perform partial measurements that are sufficient for reliable data reception without requiring exhaustive measurement of all potential cells, thus reducing measurement precision requirements.
Data Source
AI summary
A wireless transmit receive unit (WTRU) may operate in a dual connectivity (DC) context. While in a RRC_INACTIVE state, the WTRU may receive a paging message from a first cell, which may be associated with a master cell group (MCG). The paging message may indicate that the WTRU is to respond to the paging message on another cell. Also, or alternatively, the paging message may indicate that data for the WTRU is available on an SCG bearer. The WTRU may select a second cell (e.g., a cell other than the first cell) from a secondary cell group (SCG) list, which may include one or more secondary cells. The WTRU may initiate a random access channel procedure with the second cell based on receiving the paging message from the first cell. The WTRU may receive data from the second cell via the SCG bearer while in the RRC_INACTIVE state.