Array Antenna Impedance Matching for Beam Steering Accuracy
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Solution Overview
Problem
The existing beam alignment procedure in 5G New Radio (NR) systems fails to guarantee optimal alignment of uplink and downlink beams due to impedance mismatch and frequency-dependent variations in phased arrays, leading to reduced directional gain, increased interference, and degraded power amplifier performance.
Innovation Solution
The implementation of an RF front end module with electrically switchable matching circuits that adjust impedance matching for antenna elements across different beam steering angles, ensuring optimal impedance matching and reduced beam non-correspondence scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single impedance matching circuit is used for all beam steering angles, then the device complexity is reduced, but the beam alignment accuracy and power amplifier performance deteriorate due to impedance mismatch at different steering angles
Solution Approach 1:
The patent implements dynamically switchable impedance matching circuits that adapt to different beam steering angles. The system transitions from a static single matching circuit to a dynamic multi-mode matching system where multiple matching circuits are selectively activated based on the current beam steering angle, ensuring optimal impedance matching across all operating conditions
Solution Approach 2:
The patent changes the impedance parameters of the matching circuits to optimize performance at different beam steering angles. By designing multiple matching circuits with different impedance characteristics and switching between them based on the operating angle, the system maintains optimal impedance matching across the entire beam steering range
2Device complexity
If beamforming is based solely on downlink measurements, then the procedure simplicity is maintained, but the uplink beam alignment accuracy deteriorates due to frequency-dependent impedance differences between transmission and reception
Solution Approach 1:
The patent introduces feedback mechanisms where the terminal device measures downlink reference signals, determines the optimal downlink beam steering angle, and feeds back this information to the access node. The access node then uses this feedback to configure the uplink beamforming parameters, creating a closed-loop system that improves uplink alignment accuracy while maintaining procedural simplicity
Solution Approach 2:
The patent performs preliminary downlink beam measurements and determines the optimal beam steering angle before configuring the uplink beamforming. By pre-determining the beam parameters based on downlink measurements and applying them to uplink transmission, the system achieves accurate uplink alignment without requiring complex uplink measurement procedures
3Ease of operation
If impedance matching is not adjusted for different beam steering angles, then the ease of operation is maintained, but the power amplifier efficiency and linearity deteriorate due to impedance mismatch
Solution Approach 1:
The patent implements dynamic impedance matching adjustment where the matching circuit configuration automatically changes based on the beam steering angle. This dynamic adaptation ensures optimal power transfer and amplifier efficiency at all operating angles without requiring manual intervention, maintaining ease of operation while improving energy efficiency
Solution Approach 2:
The system performs self-adjustment of impedance matching by automatically selecting the appropriate matching circuit based on the current beam steering angle. The beamforming controller monitors the operating conditions and autonomously configures the impedance matching parameters, eliminating the need for external intervention and maintaining operational simplicity while optimizing amplifier efficiency
Data Source
AI summary
According to an aspect, there is provided a radio frequency front end (202) for a beamforming transceiver (201) having an antenna array comprising a plurality of antenna elements. The radio frequency front end comprises, for each antenna element, at least two radio frequency beamforming branches (218, 219). Each of at least one of said at least two radio frequency beamforming branches comprises an electrically tunable phase shifting element (221, 231), first and second transmission/reception switches (223, 233), a low-noise amplifier (225, 235) for reception and a power amplifier (224, 234) for transmission. Moreover, each of at least one of said at least two radio frequency beamforming branches comprises an electrically switchable matching circuit (226, 236). The electrically switchable matching circuit comprises two or more matching circuit settings selectable via switching. Each of the two or more matching circuit settings is configured for providing impedance matching for an antenna element at one or more beam steering angles in transmission.