Uplink Synchronization via Timing Alignment Groups
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Solution Overview
Problem
In wireless communication systems, particularly in multiple carrier systems, achieving uplink synchronization across multiple serving cells (SSCs) is complex due to varying time delays, leading to increased overhead and complexity in the random access procedure, which existing methods struggle to efficiently manage.
Innovation Solution
The implementation of a Timing Alignment Group (TAG) configuration method, where a mobile station receives TAG configuration information from a base station, transmitting a random access preamble to a representative serving cell, and receiving a Timing Advance Command (TAC) to adjust the uplink timing of all serving cells within the TAG, allowing for a single Timing Alignment Value (TAV) to be applied across multiple SSCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate random access procedures are performed for each serving cell in multiple carrier systems, then uplink synchronization can be achieved for each cell, but the overhead and complexity of the random access procedure increases significantly
Solution Approach 1:
The patent divides multiple serving cells into separate Timing Alignment Groups (TAGs), where each TAG contains one or more serving cells that share a common timing advance value. This segmentation allows the system to manage timing synchronization at the group level rather than requiring separate procedures for each individual cell, thereby reducing overall complexity while maintaining synchronization reliability.
Solution Approach 2:
The patent combines multiple serving cells into TAGs that share common timing advance values. By merging cells with similar propagation characteristics into the same TAG, the system performs a single random access procedure per TAG rather than per cell, significantly reducing overhead and complexity while achieving uplink synchronization for all cells in the group.
2Measurement precision
If multiple Timing Advance Values are configured for multiple serving cells, then accurate uplink timing alignment is achieved, but the overhead for managing multiple TAVs increases
Solution Approach 1:
The patent merges multiple serving cells into TAGs that share common timing advance values. By combining cells with similar propagation delay characteristics into the same TAG, the system reduces the total number of TAVs from one per cell to one per TAG, thereby reducing overhead while maintaining sufficient timing alignment accuracy for grouped cells.
Solution Approach 2:
The patent makes a single timing advance value universal for all serving cells within a TAG. Each TAV serves multiple cells simultaneously, allowing one value to perform the timing alignment function for multiple cells rather than requiring dedicated TAVs for each cell, thus reducing the quantity of TAVs needed.
3Reliability
If separate timing alignment is performed for each serving cell, then precise uplink synchronization is achieved for each cell, but the number of random access procedures increases
Solution Approach 1:
The patent combines multiple serving cells into TAGs and performs a single random access procedure per TAG to establish timing synchronization for all cells in that group. This merging approach reduces the number of random access procedures from one per cell to one per TAG, improving procedure efficiency while maintaining synchronization reliability through the shared timing advance value.
Solution Approach 2:
The patent segments serving cells into TAGs based on their timing characteristics, allowing efficient grouping for random access purposes. This segmentation enables the system to perform fewer random access procedures by processing groups of cells together rather than individually, thereby improving overall procedure efficiency.
Data Source
AI summary
This specification relates to an apparatus and method for performing random access in a wireless communication system. This specification discloses a mobile station, including a reception unit for receiving TAG configuration information on which at least one serving cell configured in the mobile station is classified as a Timing Alignment Group (TAG) from a base station and a transmission unit for transmitting a random access preamble to the base station on one representative serving cell within the TAG. In accordance with this specification, a procedure of obtaining a TAV for a serving cell in order to secure and maintain uplink timing synchronization becomes clear, the time taken to obtain uplink synchronization for a serving cell may be reduced, and overhead due to excessive random access attempts may be reduced by obtaining a TAV for a plurality of serving cells through one random access procedure.