Remote Radio Unit Clock Synchronization Over Switched Ethernet
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Solution Overview
Problem
Current radio access networks face challenges in providing consistent and high-quality radio frequency (RF) coverage within densely populated locations, such as buildings, due to limitations in existing Distributed Antenna Systems (DAS) and Ethernet-based transmission methods, which often result in transmission collisions and inefficiencies in data scheduling and synchronization.
Innovation Solution
A communication system comprising remote units with RF antennas and a controller connected through a switched Ethernet network, where the controller performs real-time scheduling and synchronization of RF signals using modems, and employs techniques like time stamp messaging and frequency domain compression to optimize data transmission and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional Distributed Antenna Systems (DAS) are used for in-building coverage, then RF coverage can be provided, but transmission collisions and synchronization issues occur
Solution Approach 1:
The patent introduces an Ethernet network as an intermediary transmission medium between the baseband unit and remote radio units, replacing traditional direct RF connections. This Ethernet-based transmission system acts as a mediator that carries digital baseband signals and synchronization information, thereby eliminating transmission collisions while maintaining RF coverage quality.
Solution Approach 2:
The patent replaces the traditional mechanical/electrical synchronization system with an electronic/digital synchronization mechanism. By using Ethernet packets to carry timing information and digital baseband signals instead of analog RF signals, the system eliminates transmission collisions inherent in traditional DAS while maintaining synchronization across distributed antenna elements.
2Adaptability or versatility
If Ethernet-based transmission is used to connect controller and remote units, then data transmission flexibility is improved, but transmission collisions occur
Solution Approach 1:
The patent implements preliminary scheduling and timing control at the baseband unit before transmission over the Ethernet network. By pre-allocating transmission time slots and sequencing Ethernet packets carrying baseband signals, the system maintains the flexibility of Ethernet transmission while preventing transmission collisions through advance planning and coordination.
3Productivity
If multiple remote units communicate with the controller simultaneously, then network capacity increases, but interference between transmissions occurs
Solution Approach 1:
The patent segments the network into multiple independent baseband units, each capable of simultaneous communication with its own set of remote radio units. This segmentation allows multiple communication streams to occur in parallel without interference, as each baseband unit operates independently with its own scheduling and timing control, thereby increasing overall network capacity while eliminating transmission interference.
Data Source
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Figure 2B~2C
AI summary
Among other things, a communication system comprising remote units and a controller is described. Each of the remote units comprises one or more radio frequency (RF) units to exchange RF signals with mobile devices. At least some of the RF signals comprise information destined for, or originating from, a mobile device. The controller comprises one or more modems and is connected to an external network. At least one of the modems is a baseband modem and is configured to pass first data corresponding to the information. The at least one of the modems is configured to perform real-time scheduling of the first data corresponding to the information. The controller is separated from the remote units by an intermediate network. The intermediate network comprises a switched Ethernet network over which second data corresponding to the information is carried in frames between the controller and the remote units.