C-RAN Clock Synchronization via Master Controller
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Solution Overview
Problem
Existing centralized radio access network (C-RAN) configurations face challenges in synchronizing local clocks of radio points with a single controller, especially when multiple carriers or increased capacity are required within a given coverage area.
Innovation Solution
The proposed C-RAN system includes a plurality of controllers and radio points, each with a local clock, where controllers are communicatively coupled to a core network and a master clock source over a backhaul network. Each controller determines if it should serve as a timing master, synchronizes its local clock with the master clock source, and transmits synchronization messages over a fronthaul network to other controllers and radio points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple radio points are deployed to provide multiple carriers or increased capacity, then the system capacity and coverage are improved, but the complexity of synchronizing local clocks across multiple controllers and radio points increases
Solution Approach 1:
The patent merges the clock synchronization function into a centralized role performed by a designated master controller. Instead of each controller independently synchronizing with the master clock source, one controller is selected as master and performs all synchronization operations, combining multiple synchronization tasks into a single coordinated function.
Solution Approach 2:
The master controller acts as an intermediary between the master clock source and all other controllers and radio points. It receives synchronization data from the master clock source and distributes it to all other nodes, mediating the synchronization process and simplifying the overall system architecture.
2Ease of operation
If each controller independently synchronizes with the master clock source, then synchronization autonomy is improved, but differential errors and timing precision deteriorate
Solution Approach 1:
The patent merges all synchronization operations through a single master controller that maintains a unified timing reference. All controllers and radio points synchronize to the same source through the master controller, ensuring consistent timing and eliminating differential errors that would arise from independent synchronization paths.
Solution Approach 2:
The master controller is given special properties and responsibilities compared to other controllers. It is designated as the sole entity authorized to synchronize with the master clock source and distribute timing information, creating a hierarchical structure where the master controller has enhanced functional characteristics.
3Measurement precision
If a single controller serves as timing master for all radio points, then clock synchronization precision is improved, but the system requires a hierarchical control structure increasing operational complexity
Solution Approach 1:
The patent segments the control function by designating one controller as master and others as slaves. This segmentation creates a clear hierarchical structure where the master controller handles synchronization with the external clock source, while slave controllers handle local radio point management, dividing operational complexity into manageable segments.
Solution Approach 2:
The master controller performs multiple functions: it synchronizes with the master clock source, distributes synchronization data to all slave controllers, and coordinates timing across all radio points. This multi-functionality consolidates control operations into a single entity, improving precision while managing complexity through role consolidation.
Data Source
AI summary
Embodiment are directed to systems and methods for use with a central radio access network (C-RAN) comprising a plurality of controllers and a plurality of radio points. Each of the controllers is configured to determine if that controller should serve as a timing master for the controllers and the radio points and, if that controller should serve as the timing master, synchronize the local clock of that controller with a master clock source over a backhaul network and transmit synchronization messages from that controller over a fronthaul network for reception by the other controllers and the radio points and for use by the other controllers and the radio points in synchronizing the local clocks thereof with the local clock of that controller. Other embodiments are disclosed.