Antenna Array Gain Normalization for Accurate Channel Estimation
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Solution Overview
Problem
The 3GPP wireless communication protocols face issues with scaling errors in channel estimation and precoding matrix selection due to unequal energy in antenna patterns, leading to erroneous PMI-CQI pairs and channel quality indicators, particularly in closely spaced antenna arrays.
Innovation Solution
A method for wireless communication devices to normalize antenna patterns by using a gain correction factor based on a complex matrix Q, which is calculated or provided by the base station, to ensure equal energy across all precoding matrices, allowing accurate channel estimation and PMI-CQI pair selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If no gain normalization correction is applied to antenna patterns, then the system complexity is reduced and operation is simpler, but channel estimation accuracy and PMI-CQI pair selection deteriorate due to scaling errors
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing gain normalization correction factors for each precoding matrix indicator (PMI) in lookup tables at the base station. These correction factors are computed in advance based on antenna array characteristics and stored for later retrieval during channel estimation, eliminating the need for real-time complex calculations while ensuring accurate channel estimation and PMI-CQI pair selection
Solution Approach 2:
The patent uses copying by creating and storing pre-computed correction factor tables that replicate the normalization relationships. These lookup tables contain pre-calculated gain correction values that are copied and applied during operation, replacing complex real-time normalization calculations with simple table lookups and multiplications, thus reducing computational complexity while maintaining precision
2Reliability
If equal energy is assumed for all precoding matrices, then the protocol implementation is simpler, but the PMI-CQI pair selection becomes erroneous due to unequal antenna pattern energy
Solution Approach 1:
The patent applies local quality by introducing PMI-specific gain normalization correction factors that are tailored to each individual precoding matrix. Instead of using a universal equal energy assumption, the system applies localized correction factors that account for the specific energy characteristics of each PMI, ensuring accurate channel estimation and reliable PMI-CQI pair selection for each precoding option
Solution Approach 2:
The patent implements parameter changes by modifying the channel estimation process to include PMI-dependent gain correction factors. The correction factor for each PMI adjusts the channel estimate to compensate for unequal antenna pattern energies, transforming the estimation accuracy parameter while maintaining protocol feasibility through pre-computed lookup tables
Data Source
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AI summary
A wireless communication device and a method therein includes estimating a channel for each of a plurality of transmit antenna ports using a reference symbol received from the corresponding antenna port, determining a composite channel estimate based on the estimated channels and based on a precoding matrix, and determining an updated composite channel estimate using the composite channel estimate and using a gain correction corresponding to the precoding matrix. The gain correction can be obtained over-the-air or computed at the wireless communication device.