Small Cell Synchronization via Timing Offset Relay
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Solution Overview
Problem
In LTE wireless communication systems, small cells within a cluster may not synchronize accurately with each other when macro cells are not synchronized, leading to estimation errors due to multiple hops in the synchronization hierarchy, and existing solutions either limit the number of synchronizing small cells or require costly GNSS receivers and backhaul connections.
Innovation Solution
A method and system that enable small cells to synchronize with a macro cell by measuring and transmitting timing offset values, allowing small cells without GNSS reference to align with a macro cell, and averaging offset values for precise synchronization, even when macro cells are not synchronized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If small cells use multiple hops to synchronize with macro cells, then small cells can obtain synchronization without GNSS receivers, but estimation errors accumulate and synchronization accuracy deteriorates
Solution Approach 1:
The patent introduces a master small cell as an intermediary node that receives synchronization information directly from the macro cell and relays it to other small cells. This single-hop intermediary approach prevents multi-hop error accumulation while enabling small cells without GNSS to achieve accurate synchronization through the master small cell's timing reference
Solution Approach 2:
The master small cell copies the synchronization timing information from the macro cell and distributes it to other small cells in the cluster. This copying mechanism ensures that all small cells receive identical timing references directly from the macro cell via the master small cell, eliminating the need for multiple independent measurement hops and reducing estimation errors
2Device complexity
If the network limits the number of synchronizing small cells to one per macro cell, then synchronization hierarchy complexity is reduced, but the number of small cells that can synchronize is restricted
Solution Approach 1:
The patent segments the small cell cluster into a master small cell and multiple slave small cells. The master small cell maintains a direct synchronization link with the macro cell, while slave small cells synchronize to the master. This segmentation creates a hierarchical structure that reduces overall complexity while allowing multiple small cells to synchronize through the segmented roles
Solution Approach 2:
The patent merges the synchronization function for multiple small cells into a single master small cell that serves as a centralized timing source. Instead of each small cell independently synchronizing with the macro cell, the master small cell consolidates the synchronization function and distributes timing information to all slave small cells, reducing complexity while supporting multiple synchronizing nodes
3Adaptability or versatility
If small cells use existing SON configuration transfer procedures, then network architecture compatibility is maintained, but timing offset information cannot be accurately shared among small cells
Solution Approach 1:
The patent performs preliminary measurement of timing offsets between the master small cell and the macro cell before distributing synchronization information to slave small cells. By pre-measuring and calculating the timing offset at the master small cell level, the system preserves accurate timing information that can then be shared with slave small cells through existing SON procedures, preventing information loss
Solution Approach 2:
The patent implements a feedback mechanism where the master small cell measures timing offsets from the macro cell and uses this feedback information to calculate and distribute appropriate timing adjustments to slave small cells. This feedback loop ensures that accurate timing offset information is maintained and propagated throughout the small cell cluster using existing network procedures
Data Source
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AI summary
A timing offset value between at least one macro node and a common global navigation satellite system, GNSS, derived reference time is measured. The timing offset value is transmitted to at least a cell node that does not have a GNSS reference for transmission timing adjusting at the cell node. In some embodiments, where no small cell in a cluster has a GNSS reference time, a timing of a macro base station is used as a reference for synchronizing small cells in the cluster.