CPRI Frame Synchronization Over Ethernet Using Timestamp Embedding
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Solution Overview
Problem
The existing CPRI protocol is inadequate for ensuring a timing relationship in data transmission between internal radio base station devices connected via Ethernet, as it cannot transmit frame numbers and frame phases effectively.
Innovation Solution
A method and system that convert the frame number of a CPRI data frame into a value of a second and generate a pulse per second signal with a phase corresponding to the frame phase, allowing for the transmission of a timestamp to synchronize the frame number and phase over Ethernet, enabling accurate synchronization between devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If CPRI protocol is used for point-to-point direct connection, then timing relationship of data transmission is ensured, but Ethernet technology cannot be used for connecting internal radio base station devices
Solution Approach 1:
The patent introduces Ethernet as an intermediary transmission medium between REC and RE devices, replacing the direct point-to-point connection. To maintain timing relationship reliability over this intermediary medium, the patent embeds timing information (frame numbers and frame phases) within Ethernet packets, allowing the intermediary connection to preserve the timing characteristics required by CPRI protocol while enabling Ethernet's versatility benefits.
2Adaptability or versatility
If Ethernet technology is used to connect REC and RE, then connection versatility is improved, but frame number and frame phase transmission capability is lost
Solution Approach 1:
The patent merges the timing information (frame number and frame phase) with the data transmission by embedding these critical parameters directly within the Ethernet packet structure. This combining approach ensures that the timing information travels alongside the data through the Ethernet medium, preventing any loss of synchronization information while maintaining Ethernet's versatility advantages.
Solution Approach 2:
The patent performs preliminary encoding of frame numbers and frame phases into the Ethernet packet format before transmission. By preparing and embedding the timing information in advance within the packet structure, the system ensures that receiving devices can immediately extract and use this information for synchronization, preventing information loss during the Ethernet transmission process.
Data Source
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AI summary
Embodiments of the present invention disclose a data transmission method, so as to transmit a frame number and a frame phase of a CPRI data frame in Ethernet. The present invention further provides a corresponding communications device and communications system. In some feasible implementation manners of the present invention, the method includes: selecting, by a first communications device, a CPRI data frame, and converting a frame number of the selected CPRI data frame into a value of a second; generating a pulse per second signal, where a phase of the pulse per second signal is a frame phase of the selected CPRI data frame; generating a timestamp according to the pulse per second signal and the value of a second; and sending, to a second communications device, a synchronization message that carries the timestamp, to enable the second communications device to obtain the frame number and the frame phase of the selected CPRI data frame according to the timestamp.