Digital VSWR Measurement for AAS Antenna Arrays Under Mutual Coupling
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Solution Overview
Problem
Mutual coupling between antenna elements in advanced antenna systems (AAS) severely impacts voltage standing wave ratio (VSWR) measurements, making it difficult to accurately detect antenna failures and monitor transmission efficiency, especially in large 5G AAS systems where physical switches and connectors are not feasible due to space constraints.
Innovation Solution
Grouping antenna branches by alternating polarization directions and using digital signal processing to cross-correlate forward and reflected signals, reducing mutual coupling effects while minimizing hardware complexity by using a small number of connections between the antenna system and radio unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical switches and connectors are added to each antenna port for VSWR measurement, then measurement accuracy improves, but hardware space requirements cannot be met due to the large number of ports in 5G AAS systems
Solution Approach 1:
The patent segments the antenna ports into multiple groups, where each group shares common measurement resources. Instead of providing dedicated switches and connectors for each of the 32 ports, the system divides ports into groups that can be measured using shared hardware resources, significantly reducing the total number of physical components required while maintaining measurement capability across all ports.
Solution Approach 2:
The patent implements multi-functional measurement resources that can serve multiple antenna ports. The same set of switches and connectors is reused across different port groups through time-division or code-division multiplexing, allowing a single hardware configuration to perform VSWR measurements on all 32 ports without requiring dedicated components for each port.
2Power
If antenna elements are placed in close proximity to increase radiation gain and beam steering capability, then antenna performance improves, but mutual coupling between elements increases and severely impacts VSWR measurement accuracy
Solution Approach 1:
The patent introduces specialized measurement signal sequences as intermediaries between the transmitted signal and the reflected signal. These known reference sequences are inserted into the transmission, allowing the receiver to correlate and identify the reflected portion even in the presence of strong mutual coupling. The intermediary reference signals enable the system to distinguish true reflections from coupled signals, maintaining measurement accuracy despite close element spacing.
Solution Approach 2:
The patent implements a feedback mechanism where the measured VSWR information and channel state information are used to adjust the measurement process. By continuously monitoring the received signals and comparing them against expected patterns, the system can identify and compensate for mutual coupling effects, improving the accuracy of VSWR measurements in high-gain antenna configurations.
Data Source
AI summary
A method and transmitter for determining voltage standing wave ratios, VSWR, of an antenna array having multiple subarrays, each subarray having two branches. According to one aspect, a method includes grouping the branches of the 5 antenna array to form a number of groups, each group being formed so that nearest branches in group are separated by at least one branch not in the group. For each group, the method includes combining reflected signals from the branches of the group to produce a first signal YREFL and combining forward signals from the 10 branches of the group to produce a second signal YFWD; calculating a reflected power PREFL and a forward power PFWD and calculating a VSWR for the group based on the reflected power PREFL and the forward power PFWD.