Composite FDRSB Estimation for 5G MIMO IQ Mismatch
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Solution Overview
Problem
5G New Radio (NR) systems face challenges in estimating and compensating for frequency-dependent residual side band (FDRSB) due to multiple IQ modulators and antennas, leading to increased hardware requirements and power consumption, especially with larger bandwidths and more RX antennas, which affects communication reliability and latency.
Innovation Solution
The system estimates a composite FDRSB over-the-air (OTA) on the receiver side and reports it back to the transmitter, allowing for a single filter compensation across multiple IQ modulators, reducing the need for separate estimations and feedback loops, thus saving resources and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate FDRSB estimation is performed for each antenna and IQ modulator, then estimation accuracy is improved, but device complexity and hardware requirements increase
Solution Approach 1:
The patent combines separate FDRSB estimation operations for multiple antennas and IQ modulators into a single composite FDRSB estimation process. The receiver estimates a composite FDRSB value that represents the combined effect of all antennas and modulators, eliminating the need for separate estimation circuits for each component while maintaining overall estimation accuracy.
Solution Approach 2:
The composite FDRSB estimation mechanism serves multiple functions simultaneously: it estimates FDRSB effects from all antennas, all IQ modulators, and their interactions in a single process. This universal estimation approach replaces multiple specialized estimation circuits, reducing hardware complexity while providing comprehensive coverage.
2Manufacturing precision
If separate feedback loops are implemented for each antenna and IQ modulator, then compensation accuracy is improved, but power consumption increases
Solution Approach 1:
The patent merges multiple separate feedback loops into a single feedback mechanism. Instead of implementing independent feedback paths for each antenna and IQ modulator, the system uses one unified feedback loop that operates on the composite FDRSB value, significantly reducing the number of active components and power consumption while maintaining compensation effectiveness.
Solution Approach 2:
The single composite feedback loop provides sufficient compensation accuracy without requiring the excessive resources of multiple separate loops. By working with the aggregated FDRSB effect rather than individual components, the system achieves adequate compensation with minimal overhead.
3Measurement precision
If multiple dedicated pilot signals are transmitted for each antenna, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent combines multiple dedicated pilot signals into a single composite pilot signal that represents the combined transmission from all antennas and IQ modulators. This allows the receiver to estimate composite FDRSB effects using one pilot signal instead of multiple separate signals, reducing training time while maintaining measurement accuracy.
Solution Approach 2:
The composite pilot signal is designed to preliminarily establish the FDRSB characteristics of the entire system before actual communication begins. By preparing the composite estimation in advance using a single pilot, the system avoids the time-consuming process of separately characterizing each antenna and modulator.
Data Source
AI summary
Aspects of the present disclosure also allow for a more efficient way to correct or compensate for IQ mismatch in an environment with multiple TX antennas and multiple IQ modulators. In these environments, a received signal is a beamformed signal which is a combination of all TX antennas passing through different channels and may be received in a single RX antenna. Specifically, the RX side may estimate the composite FDRSB for the TXs and signal back a composite FDRSB to allow the TX to use a single filter to compensate for the composite FDRSB. The composite FDRSB may correspond to the equivalent FDRSB received as a sum of the individual FDRSBS of each of the IQ modulators and IQ antennas at a base station.