Distributed Base Station Test Bus Architecture
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Solution Overview
Problem
The distributed architecture of Distributed Base Stations (DBS) poses challenges for system testing and field updates due to the limited serial channel between local and remote backplanes, leading to propagation delays and difficulties in testing and updating configuration PROMs, as well as the need for robust remote field updates without on-site visits.
Innovation Solution
A novel distributed boundary scan test bus architecture that transmits IEEE 1149.1 Boundary Scan TAP signals over a serial channel, utilizing field programmable gate arrays (FPGAs) and optical/digital transceivers to create virtual test bus connections, enabling system testing and remote field updates as if the distributed units were on a shared backplane, with features like ASP address assignment and a fail-safe mechanism to ensure integrity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a distributed architecture with separate BBUs and RFUs connected by long fiber cables is used, then deployment flexibility and coverage capability are improved, but system testing and field update operations become difficult due to propagation delays and lack of dedicated test channels
Solution Approach 1:
The patent introduces a test bus intermediary system that spans between BBU and RFU, providing a dedicated test channel that mediates testing operations across the distributed connection. This intermediary test bus allows boundary scan operations to function despite the physical separation and propagation delays inherent in distributed architecture.
Solution Approach 2:
The patent adds a temporal dimension to the test bus architecture by implementing synchronized clocking mechanisms and time-stamped data transfer across the distributed system. This allows the test bus to function correctly over long fiber cables by accounting for and compensating for propagation delays through temporal coordination.
2Adaptability or versatility
If BBUs and RFUs are deployed at distant locations connected by long fiber cables, then coverage capability is improved, but test clock frequency must be reduced due to propagation delays
Solution Approach 1:
The patent implements dynamic clock frequency adjustment and adaptive timing mechanisms that allow the test bus to operate efficiently at various distances. The system dynamically synchronizes clock edges and data sampling times based on measured propagation delays, maintaining effective test operations regardless of the BBU-RFU distance.
Solution Approach 2:
The patent changes the temporal parameters of the test bus operation by introducing variable clock timing and adjustable data transfer intervals. These parameter changes allow the system to accommodate different fiber cable lengths and propagation delays while maintaining functional testing capability.
3Device complexity
If only a serial functional channel exists between local and remote backplanes, then device complexity is reduced, but testing and programming of configuration PROMs becomes difficult
Solution Approach 1:
The patent makes the serial channel multi-functional by implementing a universal test bus protocol that can perform both functional data transmission and boundary scan testing through the same physical medium. This allows the single serial channel to serve dual purposes: normal operational communication and comprehensive system testing, eliminating the need for separate dedicated test channels.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution facilitates efficient distributed system testing and remote field updates, reducing test and programming duration, enhancing reliability, and allowing for cost-effective and timely maintenance of DBS units, even over long distances, by treating distributed units as if they were on a shared backplane.
Implementation Method 1
a first optical/digital transceiver in the BBU and a second optical/digital transceiver in the RFU to create a virtual connection between the BBU and the RFU over the serial channel
Data Source
AI summary
A distributed test architecture of transmitting boundary scan Test Access Port (TAP_signals over a serial channel is disclosed. The architecture facilitates the system testing and remote field update of distributed base stations in a wireless network. The distributed test architecture enables system testing as if the distributed units are on a backplane within the same chassis by creating a plurality of logical connections between the distributed unit and the test bus using a single bit fiber line and a five bit TAP test bus.