Base Station Synchronization via Cell Grouping
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Solution Overview
Problem
In LTE systems, the difference in Timing Advances (TAs) used by Primary Cells (Pcells) and Secondary Cells (Scells) on different frequency bands increases the number of PRACH procedures and time alignment timers needed for user equipment to perform uplink communications, leading to higher overheads.
Innovation Solution
Divide cells into groups based on a predetermined rule, allowing user equipment to perform PRACH procedures on groups rather than individual cells, thereby reducing the number of TAs and PRACH procedure overheads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If user equipment performs PRACH procedures in respective cells to obtain cell-specific TAs, then uplink communication accuracy is improved, but the number of TAs and TATs increases and PRACH overhead increases
Solution Approach 1:
The patent merges multiple cells into a single TA group, allowing user equipment to use a single TA for all cells in the group rather than maintaining separate TAs for each cell. This reduces the number of TAs and TATs while maintaining uplink communication accuracy through group-based timing alignment.
Solution Approach 2:
A single TA acquired through PRACH procedure on a reference cell is made universally applicable to all cells within the same TA group. This multi-functional TA serves multiple cells simultaneously, reducing overhead while ensuring accurate uplink timing for all grouped cells.
2Measurement precision
If user equipment performs PRACH procedures in respective cells to obtain cell-specific TAs, then uplink communication accuracy is improved, but PRACH procedure overhead increases
Solution Approach 1:
The patent combines multiple cells into TA groups, reducing the number of required PRACH procedures from one per cell to one per TA group. This significantly reduces PRACH overhead and time consumption while maintaining timing accuracy for all cells in the group through the shared TA.
3Device complexity
If cells use the same TA as being located in the same frequency band, then device complexity is reduced, but uplink communication accuracy deteriorates when cells are on different frequency bands
Solution Approach 1:
The patent segments cells into TA groups based on frequency band and other characteristics, creating a hierarchical structure where cells are first divided by frequency band and then further grouped. This segmentation allows for reduced complexity within groups while maintaining the precision needed for different frequency bands.
Data Source
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AI summary
Embodiments of the present invention disclose a method and device for synchronization in base stations and user equipments. Specially, a method for synchronization in base stations is disclosed, which includes: dividing cells into one or more group(s) based on a predetermined rule, such that a Physical Random Access Channel (PRACH) procedure is performed with respect to a group from the one or more group(s) of cells, so as to acquire for a user equipment a Timing Advance (TA) for use in transmissions.