Multi-Cell UE Time Alignment Timer Management
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Solution Overview
Problem
Current wireless communication systems face challenges in managing multiple cells for efficient multi-cell communications, particularly in handling timing alignment and random access procedures across primary and secondary cells, leading to complexities in uplink transmission timing and resource allocation.
Innovation Solution
A User Equipment (UE) is configured with multiple time alignment timers, where a primary cell (PCell) timer determines the expiry of a secondary cell (SCell) timer, allowing for shared uplink transmission timing and resource management, with infinity expiry values for SCells to simplify operational costs and implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple time alignment timers are configured for each cell, then timing alignment management becomes more precise, but device complexity and operational overhead increase
Solution Approach 1:
The patent merges the time alignment timer management by allowing a secondary cell (SCell) timer to be determined based on the primary cell (PCell) timer status. When the PCell timer expires or is stopped, the SCell timer is accordingly expired or stopped, reducing the need for independent timer management while maintaining timing alignment precision across cells.
Solution Approach 2:
The PCell time alignment timer serves a universal function by controlling both the PCell and SCell timing alignment. The same timer mechanism is used across multiple cells, reducing overall system complexity while ensuring consistent timing management throughout the multi-cell communication system.
2Measurement precision
If independent time alignment timers are used for each secondary cell, then timing control accuracy improves, but operational costs and implementation complexity increase
Solution Approach 1:
The patent combines the timing control mechanism by determining SCell timer status based on PCell timer status rather than using completely independent timers. This merging approach maintains timing control accuracy through the primary cell's timer management while reducing implementation complexity by avoiding duplicate timer infrastructure.
Solution Approach 2:
The system performs preliminary action by establishing the PCell timer as the primary control mechanism before configuring SCell timers. The SCell timer configuration is predetermined to follow the PCell timer status, simplifying the implementation by avoiding complex real-time coordination between multiple independent timers.
3Reliability
If multiple independent timers are managed for primary and secondary cells, then timing alignment reliability improves, but resource overhead and operational complexity increase
Solution Approach 1:
The patent merges timer management resources by making the SCell timer status dependent on the PCell timer status. This reduces the quantity of actively managed timers while maintaining timing alignment reliability, as the PCell timer serves as the authoritative source for timing decisions across all cells.
Solution Approach 2:
The PCell time alignment timer is designed with universal functionality to control both primary and secondary cells. This multi-functional approach reduces resource overhead by using a single timer mechanism for multiple cells while maintaining the reliability needed for accurate timing alignment across the entire cell group.
Data Source
AI summary
A User Equipment (UE) configured for multi-cell communications is disclosed. The UE includes a processor and instructions stored in memory that is in electronic communication with the processor. The UE determines a primary cell (PCell) with a corresponding PCell time alignment timer. The UE also determines a secondary cell (SCell) with a corresponding SCell time alignment timer. The UE further determines whether the PCell time alignment timer is expired. The UE additionally sets the SCell time alignment timer as expired if the PCell time alignment timer is expired.