Multimode Base Station Clock Synchronization Across Dual BBUs
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Solution Overview
Problem
Current multimode base stations are limited in the number of wireless standards they can support due to the limited slots in a single Base Band Unit (BBU), typically only able to support two standards, restricting their functionality.
Innovation Solution
The implementation of a multimode base station that integrates two BBUs (BBU0 and BBU1) with boards of different standards connected through a common public radio interface (CPRI), where BBU1 achieves frequency and time synchronization with BBU0 using a synchronous Ethernet clock and IEEE1588 clock respectively, enabling support for multiple standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single BBU is used to overlay boards of different standards, then the base station can support multiple standards, but the number of supported standards is limited to two due to limited slots
Solution Approach 1:
The base station is divided into multiple independent BBUs (first BBU and second BBU), each capable of overlaying standard boards. This segmentation allows each BBU to handle specific standards while collectively supporting more standards than a single BBU could accommodate, directly resolving the limitation of supporting only two standards.
Solution Approach 2:
The system transitions from a single-dimension architecture (one BBU with limited slots) to a multi-dimensional architecture where multiple BBUs are connected through a backhaul network. This adds a new dimension of scalability, allowing standard boards to be distributed across different BBUs and enabling support for more than two standards through the expanded resource pool.
2Adaptability or versatility
If multiple BBUs are integrated to support more standards, then the adaptability increases, but synchronization complexity between BBUs increases
Solution Approach 1:
A backhaul network acts as an intermediary between the first BBU and second BBU, providing standardized interfaces for clock signal transmission. This intermediary simplifies the synchronization architecture by establishing clear signal paths and protocols, reducing the complexity that would otherwise arise from direct peer-to-peer synchronization between multiple BBUs.
Solution Approach 2:
The system implements feedback mechanisms where clock signals are transmitted from one BBU to another through the backhaul network, and synchronization status is monitored and adjusted. This feedback loop ensures that frequency and time synchronization are maintained across multiple BBUs, managing the synchronization complexity through active control rather than passive connection.
3Adaptability or versatility
If standard boards are distributed across multiple BBUs, then more standards can be supported, but clock synchronization between BBUs becomes critical
Solution Approach 1:
The system establishes clock synchronization relationships in advance between BBUs before operational use. By pre-configuring the clock signal transmission paths and synchronization parameters through the backhaul network, the system ensures that when multiple standard boards are activated across different BBUs, the clock synchronization is already in place, preventing reliability issues during dynamic operations.
Data Source
AI summary
The present invention relates to a method includes: implementing, by the board in the BBU1, frequency synchronization between a system clock of the board in the BBU1 and a system clock of the board in the BBU0 by using a synchronous Ethernet clock that is output by the board in the BBU0; and implementing, by the board in the BBU1, time synchronization between the system clock of the board in the BBU1 and the system clock of the board in the BBU0 by using an IEEE1588 clock that is output by the board in the BBU0. The present invention can enable the multimode base station to support more standards.