Radio Unit Cascading for 5G RAN Simplification
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Solution Overview
Problem
The existing architecture of radio access networks (RANs) for 5G cellular communication, which includes radio units (RUs), distributed units (DUs), and centralized units (CUs), faces challenges with the use of hardware switches and long cables connecting multiple RUs to a DU, leading to complex installations and management issues, particularly for RUs at long physical distances from the DU.
Innovation Solution
Implementing radio unit cascading or daisy chaining, where multiple RUs are connected to a single hardware interface at a DU, with RU processors configured to receive, process, and multiplex both uplink and downlink data, allowing them to forward data to and from other RUs via southbound and northbound interfaces, respectively, thereby reducing the need for multiple cables and switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a hardware switch is used to couple multiple RUs to a DU, then connectivity between RUs and DU is achieved, but installation complexity and management overhead increase
Solution Approach 1:
The patent merges the functions of multiple individual RU-DU connections into a single daisy-chained topology where RUs are sequentially connected. This eliminates the need for a central hardware switch and multiple independent cable connections, thereby reducing installation complexity and hardware requirements while maintaining full connectivity between all RUs and the DU.
Solution Approach 2:
Each RU in the daisy-chained configuration is designed to perform multiple functions: it processes its own uplink and downlink data, forwards data from upstream RUs to downstream RUs, and maintains bidirectional communication capabilities. This multi-functionality eliminates the need for dedicated switching hardware, simplifying the overall system architecture.
2Length of moving object
If long cables are used to connect RUs at distant locations to the DU, then coverage distance is extended, but cable installation difficulty increases
Solution Approach 1:
The patent segments the overall RU-DU connection into multiple shorter segments through daisy-chaining, where each RU connects to its immediate neighbor rather than requiring a single long cable from every RU to the DU. This segmentation reduces cable installation difficulty while achieving the same coverage distance through sequential connections.
3Reliability
If multiple separate connections are made from each RU to the DU, then individual connection reliability is maintained, but system complexity increases
Solution Approach 1:
The patent introduces intermediate RUs as mediators in the daisy-chained topology. Each intermediate RU acts as a relay station that forwards data between upstream and downstream connections. This intermediary approach maintains reliable data transmission paths while reducing overall system complexity by eliminating the need for a central switching device and multiple independent connections.
Data Source
AI summary
The described technology is generally directed towards radio unit cascading in radio access networks. Radio units (RUs) can be configured with processors adapted to support daisy chaining of multiple RUs, so that the multiple RUs can connect to one hardware interface at a distributed unit (DU). An RU processor for a given RU can be configured to receive downlink data, including downlink data for the given RU as well as downlink data for other downstream RUs. The RU processor can extract the downlink data for the given RU and forward the downlink data for other downstream RUs via a southbound interface. The RU processor can also be configured to receive uplink data from the other RUs, multiplex the received uplink data from the other RUs with uplink data from the given RU, and send the resulting multiplexed data towards the DU via a northbound interface.