RRC Connected Sub-States for Uplink Sync Without GNSS
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Solution Overview
Problem
In wireless communications systems, when a user equipment (UE) loses its global navigation satellite system (GNSS) connection while in a radio resource control (RRC) connected state, it may lose uplink synchronization with the network entity, leading to unnecessary transitions to an RRC idle state and increased signaling overhead and latency.
Innovation Solution
The UE operates in one or more sub-states of the RRC connected state, maintaining uplink synchronization by applying a first uplink synchronization procedure when GNSS is unavailable and a second procedure when GNSS is available, using timers and signaling to indicate GNSS status to the network entity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transitions to RRC idle state when GNSS is unavailable, then uplink synchronization can be reestablished through random access procedure, but latency and signaling overhead increase
Solution Approach 1:
The RRC connected state is segmented into two sub-states: one for when location information is available and another for when it is unavailable. This allows the UE to maintain a connected sub-state even without GNSS, using alternative uplink synchronization procedures rather than transitioning to idle state, thereby reducing latency while maintaining synchronization reliability.
Solution Approach 2:
The system dynamically switches between different uplink synchronization procedures based on GNSS availability. When GNSS is unavailable, the UE transitions to a different sub-state that employs alternative synchronization methods, enabling adaptive maintenance of uplink synchronization without fixed state transitions, thus reducing unnecessary latency.
2Reliability
If the UE transitions to RRC idle state when GNSS is unavailable, then uplink synchronization can be reestablished, but signaling overhead increases
Solution Approach 1:
By segmenting the connected state into sub-states based on location information availability, the UE可以避免 unnecessary RRC state transitions and associated signaling. The segmentation allows maintaining connected sub-state with simplified synchronization procedures, reducing signaling overhead while ensuring synchronization reliability.
Solution Approach 2:
The patent extracts the location information availability condition from the RRC state management decision process. Instead of requiring GNSS availability for maintaining connected state, the system separates the synchronization procedure selection from the RRC state transition, allowing the UE to remain in connected sub-state without GNSS, thereby eliminating unnecessary signaling overhead.
3Device complexity
If the UE uses a single uplink synchronization procedure, then the system is simpler to manage, but it cannot adapt to GNSS unavailability
Solution Approach 1:
The system employs dynamic selection of uplink synchronization procedures based on GNSS availability status. The UE can adaptively switch between different synchronization procedures while maintaining a connected sub-state, providing versatility without requiring complex RRC state transitions. This dynamic adaptation balances procedural complexity with adaptability to varying GNSS conditions.
Solution Approach 2:
Different uplink synchronization procedures are applied locally based on the specific condition of GNSS availability. When GNSS is unavailable, a specific alternative procedure is applied in that local context (connected sub-state without location information), while the standard procedure applies when GNSS is available. This local quality approach provides adaptability without requiring global system complexity.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. The described techniques provide for provide for a user equipment (UE) to operate according to one or more sub-states of a radio resource control (RRC) connected state when the UE loses positioning information, which may support the UE maintaining uplink synchronization with a network entity without transitioning to an RRC idle state. The UE may maintain one or more timers associated with operations in sub-states of the RRC connected state, and may use respective uplink synchronization parameters according to a current sub-state. For example, the UE may indicate location information status to the network entity and may receive resource adjustment parameters or random access channel (RACH) resources for determining resource adjustment values with or without location information.