Inter-Cell Synchronization in Heterogeneous Wireless Networks
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Solution Overview
Problem
In heterogeneous wireless communication networks, especially with Continuous Time Division Duplexing (TDD) frequency spectrums, synchronization issues among cells from different operators or with different synchronizing manners lead to interference and degrade network performance, affecting both inter-operator and intra-operator cell clusters.
Innovation Solution
A method and device for inter-cell synchronization that involves cell information interaction to determine a source and target cell, followed by initial frame-level synchronization, synchronization information interaction to determine a synchronization subframe position, and symbol-level synchronization using either MBSFN or special subframes, ensuring accurate synchronization even across different operators and manufacturers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cells from different operators use the same frequency range without synchronization, then each operator can independently operate its cells, but serious interference occurs among cells leading to degraded network performance
Solution Approach 1:
The patent introduces a synchronization server as an intermediary that coordinates timing information among cells from different operators. The server receives synchronization requests from base stations, determines appropriate synchronization parameters, and returns timing information to enable synchronized operation without direct operator interaction, thus resolving the interference problem while maintaining independent operation capability
Solution Approach 2:
The synchronization server provides a universal synchronization mechanism that works across multiple operators and different synchronizing manners (GPS-based, network listening-based, or mutual synchronization). This multi-functional approach enables different operator networks to operate on the same frequency range by providing a common reference timing source
2Adaptability or versatility
If cells from the same operator use different synchronizing manners due to manufacturer problems, then each cell can operate with its chosen method, but synchronization errors occur among cell clusters beyond prescribed ranges
Solution Approach 1:
The patent creates a common synchronization reference level by having all base stations (regardless of manufacturer or chosen method) ultimately reference the same synchronization server. This equalizes the synchronization potential across different cell clusters, ensuring that GPS-based, network listening-based, and mutual synchronization methods all achieve the same accuracy level and prevent synchronization errors beyond prescribed ranges
3Measurement precision
If GPS synchronization is used, then synchronization accuracy can be maintained, but GPS signals may be blocked in indoor or dense urban environments
Solution Approach 1:
The synchronization server acts as an intermediary that receives GPS synchronization information from base stations with clear GPS signals and redistributes this synchronized timing information to base stations in GPS-denied environments. This allows indoor or dense urban base stations to achieve accurate synchronization without direct GPS signal access, effectively transferring the synchronization capability through the server mediator
Solution Approach 2:
The synchronization server creates copies of the GPS-derived synchronization timing information and distributes them to multiple base stations. Base stations in blocked environments receive these copied timing references, allowing them to maintain synchronization accuracy without needing direct GPS signal access
4Adaptability or versatility
If network listening method is used for synchronization, then cells can synchronize without GPS, but additional signaling overhead and complexity are introduced
Solution Approach 1:
The patent implements a self-service synchronization mechanism where base stations automatically perform network listening to detect synchronization signals from neighboring cells, automatically determine their synchronization status, and self-adjust their timing without requiring complex manual configuration or extensive signaling overhead. The synchronization server simply provides the initial reference, and the network autonomously maintains synchronization
Data Source
AI summary
There is provided a method and device in a wireless communication system, the method comprising: a cell information interacting step of interacting information about a first cell and a second cell having interference with each other between the first cell and the second cell to determine a source cell and a target cell among the first cell and the second cell, wherein the target cell performs synchronization with the source cell being a synchronization source; an initial synchronizing step of performing initial frame-level synchronization by the target cell with the source cell being the synchronization source; a synchronization information interacting step of interacting information about a synchronization subframe position between the source cell and the target cell to determine a synchronization subframe position configurable for both the source cell and the target cell; and a symbol-level synchronizing step of performing symbol-level synchronization between the source cell and the target cell according to the determined synchronization subframe position. According to the disclosure, it is possible to realize synchronization among cells belonging to different operators and/or adopting different synchronizing manners.