Small Cell Synchronization Using Independent Base Station Selection
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Solution Overview
Problem
In LTE networks, small cell eNBs face challenges in achieving reliable time and frequency synchronization, especially when the macro cell layer is not synchronized, leading to poor Signal-to-Interference plus Noise Ratio (SINR) and inaccurate synchronization due to the need for separate eNBs for frequency and time synchronization.
Innovation Solution
The method involves independently selecting eNBs for frequency and time synchronization based on signal quality and synchronization status, allowing for separate eNB sources for each, and computing timing offsets for macro cells even when signals are not received reliably, using a combination of offsets measured by small cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single eNB is used for both frequency and time synchronization, then the synchronization process is simplified, but synchronization accuracy deteriorates when macro cells are not synchronized
Solution Approach 1:
The patent segments the synchronization function into two independent parts: frequency synchronization and time synchronization. A small cell eNB can independently select different macro cell eNBs for each function, allowing optimization of each synchronization aspect separately rather than being constrained by a single reference eNB
2Adaptability or versatility
If small cell eNBs synchronize to unsynchronized macro cells, then network deployment flexibility is improved, but SINR and synchronization reliability deteriorate
Solution Approach 1:
The small cell eNB performs self-service by autonomously measuring signal quality from multiple macro cell eNBs and independently selecting the most suitable reference eNBs for frequency and time synchronization. This self-selection mechanism ensures reliable synchronization even when macro cells are not synchronized, without requiring external coordination
3Ease of operation
If the same macro cell eNB is selected for both frequency and time synchronization, then the selection process is simplified, but synchronization performance deteriorates when signal quality varies
Solution Approach 1:
The patent applies local quality by allowing different macro cell eNBs to be selected for frequency and time synchronization based on their respective signal qualities at the small cell location. The small cell eNB evaluates signal quality metrics for each macro cell and independently selects the optimal reference for each synchronization function, rather than uniformly using the same reference for both
Data Source
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AI summary
Systems and methods related to time and frequency synchronization of a base station in a cellular communications network; are disclosed. In some embodiments, a method of operation of a synchronizing base station comprises selecting a first base station for frequency synchronization and a second base station for time synchronization, where the second base station can be different than the first base station selected for frequency synchronization. The method further comprises performing frequency synchronization using a signal transmitted from a radio interface of the first base station and performing time synchronization using a signal transmitted from a radio interface of the second base station, in this manner, the synchronizing base station is enabled to independently select the first and second base stations used for frequency and time synchronization, respectively.