MIMO Transmit Receive Chain Calibration Correction Matrices
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Solution Overview
Problem
In MIMO communication systems, accurately calibrating transmit and receive chains is challenging due to variations in circuitry within transmitter and receiver units, which affects channel estimation and overall performance, especially in systems where downlink and uplink share a single frequency band.
Innovation Solution
The proposed solution involves pre-calibration, field calibration, and follow-on calibration techniques to determine and account for the responses of transmit and receive chains by obtaining overall gains for each unit, deriving correction matrices, and updating them based on pilot signals and error estimation, allowing for improved channel estimation and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration techniques are performed to account for transmit and receive chain variations, then channel estimation accuracy is improved, but device complexity and calibration process complexity increase
Solution Approach 1:
The patent applies preliminary action by performing pre-calibration during manufacturing to determine initial correction matrices for transmit and receive chains. This advance calibration stores correction data that can be applied during operation, eliminating the need for complex real-time calibration procedures while maintaining high channel estimation accuracy.
Solution Approach 2:
The patent implements feedback through field calibration and follow-on calibration procedures where pilot signals are transmitted and received to measure actual chain responses. These measurements feed back into updating correction matrices, allowing the system to adapt to environmental changes and maintain accuracy without requiring complete recalibration.
2Reliability
If pre-calibration and field calibration are performed to determine transmit and receive chain responses, then system performance is improved, but loss of time during calibration increases
Solution Approach 1:
The patent performs pre-calibration during manufacturing before deployment, establishing baseline correction matrices in advance. This preliminary action ensures system reliability is optimized before field operation, eliminating the need for extensive calibration time during actual system deployment and operation.
Solution Approach 2:
The patent implements a tiered calibration approach where pre-calibration provides sufficient correction for most conditions, and field calibration is performed only when necessary to update specific parameters. This partial recalibration strategy maintains system performance while minimizing calibration time by avoiding complete recalibration cycles.
Data Source
AI summary
Techniques for calibrating the transmit and receive chains at a wireless entity are described. For a pre-calibration, N first overall gains for a receiver unit and N transmitter units in the transmit chain are obtained, where N>1. Each first overall gain is for a combined response for the receiver unit and the associated transmitter unit. N second overall gains for a transmitter unit and N receiver units in the receive chain are also obtained. Each second overall gain is for a combined response for the transmitter unit and the associated receiver unit. The gain of each transmitter unit and the gain of each receiver unit are determined based on the first and second overall gains. At least one correction matrix is then derived based on the gains of the transmitter and receiver units and is used to account for the responses of these units.