Uplink Timing Control for Multi-Cell Synchronization
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Solution Overview
Problem
In LTE radio communication systems, uplink signal synchronization management across multiple synchronization groups is challenging, particularly when uplink transmission timing differs between component carriers or cells, leading to potential interference and system performance deterioration due to mismatched synchronization status recognition between the radio base station and radio terminal.
Innovation Solution
A radio communication system where the radio station calculates and notifies uplink signal transmission timing adjustment values for each cell group, allowing the radio terminal to manage synchronization status across multiple cell groups using a shared synchronization timer, thereby detecting and preventing loss of synchronization and avoiding interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single common uplink transmission timing adjustment value is used for multiple component carriers, then control complexity is reduced, but synchronization accuracy deteriorates when uplink transmission timing differs between carriers
Solution Approach 1:
The patent segments the multiple component carriers into multiple TA groups, where each group is assigned a separate uplink transmission timing adjustment value. This allows independent timing control for each group while reducing the overall complexity compared to fully independent control of all carriers. The segmentation resolves the contradiction by providing a hierarchical structure that balances control simplicity with synchronization accuracy.
Solution Approach 2:
The patent applies local quality by allowing different timing adjustment characteristics for different TA groups based on their specific requirements. Each TA group can have its own timing adjustment value that is optimized for its local conditions (frequency band, propagation characteristics), while still using a unified synchronization timer mechanism. This enables precise local timing control without requiring completely independent control systems for all carriers.
2Measurement precision
If uplink transmission timing is independently controlled for each cell group, then synchronization accuracy is improved, but control complexity increases
Solution Approach 1:
The patent merges the control mechanisms by using a single unified synchronization timer that governs all TA groups. While each TA group has its own timing adjustment value for accurate local control, the shared timer provides a common reference framework that simplifies overall system management. This merging approach reduces complexity by eliminating the need for multiple independent timer mechanisms while preserving synchronization accuracy through group-specific adjustment values.
Solution Approach 2:
The unified synchronization timer serves multiple functions across different TA groups, acting as a universal time reference that coordinates timing adjustments for all cell groups. This multi-functional timer reduces control complexity by providing a single coordination mechanism that works across all groups, while the group-specific timing adjustment values maintain the necessary synchronization accuracy for each group's unique requirements.
3Device complexity
If a single synchronization timer is used for all cell groups, then device complexity is reduced, but reliability of synchronization management deteriorates when timing differs between groups
Solution Approach 1:
The patent segments the synchronization management into TA group-specific timing adjustment values while maintaining a unified timer. Each TA group's timing adjustments are independently calculated and applied, ensuring that synchronization management remains reliable even when timing characteristics differ between groups. The segmentation allows the system to handle diverse timing requirements without compromising overall reliability.
Solution Approach 2:
The patent applies local quality by tailoring timing adjustment values to each TA group's specific characteristics while using a common timer framework. This ensures that each group receives appropriate timing management for its local conditions (frequency band, propagation delays), maintaining synchronization reliability without requiring completely separate timer systems for each group.
4Measurement precision
If timing adjustment values are notified separately for each cell group, then synchronization accuracy is improved, but transmission overhead increases
Solution Approach 1:
The patent merges the notification mechanism by including timing adjustment values for multiple TA groups within a single MAC control element or notification message. This reduces transmission overhead by consolidating what would otherwise be multiple separate notifications into one unified message, while still providing the accurate, group-specific timing information needed for proper synchronization.
Solution Approach 2:
The notification mechanism is designed to be universal, capable of carrying timing adjustment information for multiple TA groups simultaneously. This multi-functional notification structure reduces overhead by transmitting all necessary timing adjustments in a single communication event, while maintaining the precision of group-specific timing values through efficient data encoding and structure.
Data Source
AI summary
A radio station, a radio terminal, and a method for transmission timing control in a radio communications system are provided that facilitate uplink-signal synchronization management in a plurality of cell groups. The radio station (10) calculates uplink-signal transmission timing adjustment values TA1 and TA2 for respective cell groups (1, 2), each of which includes at least one cell including an available uplink radio resource, and notifies the calculated uplink-signal transmission timing adjustment values TA1 and TA2 to the radio terminal (20) at a time.