Beamforming Weight Matrix Computation for Phase Noise Robustness
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Solution Overview
Problem
In 5G wireless communication systems, especially in millimeter wave bands, phase noise significantly affects the accuracy of angular channel estimation, leading to increased sensitivity and reduced coverage and capacity due to the use of large antenna arrays, making existing null-forming techniques in MIMO transmission schemes unreliable.
Innovation Solution
A modified Zero-Forcing (ZF) transmission scheme is introduced, where the beamforming weight matrix is computed as the inverse of a weighted channel estimate matrix, using a Hadamard matrix product to smooth the antenna array beam pattern and reduce sensitivity to phase noise, thereby stabilizing channel quality and maintaining low computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If large antenna arrays are used in mmw bands to achieve sufficient coverage, then coverage and capacity are improved, but sensitivity to phase noise increases and channel estimation accuracy deteriorates
Solution Approach 1:
The patent modifies the channel estimate matrix by applying a weighting factor to its elements before computing the beamforming weight matrix. This parameter change in the channel estimate matrix compensates for phase noise effects, thereby maintaining channel estimation accuracy despite using large antenna arrays for enhanced coverage
2Object-generated harmful factors
If null-forming techniques are used in MIMO transmission to reduce interference, then interference is reduced, but reliability decreases due to increased sensitivity to phase noise
Solution Approach 1:
The patent modifies the channel estimate matrix by applying a weighting factor to its elements before computing the beamforming weight matrix. This parameter change stabilizes the null-forming process against phase noise variations, thereby maintaining transmission reliability while preserving interference reduction capabilities
3Productivity
If standard ZF transmission is used to achieve orthogonal data streams at receiver, then spectral efficiency is improved, but robustness to phase noise deteriorates
Solution Approach 1:
The patent modifies the channel estimate matrix by applying a weighting factor to its elements before computing the beamforming weight matrix. This parameter change maintains the orthogonality of data streams at the receiver while reducing sensitivity to phase noise, thereby preserving spectral efficiency while improving robustness
Data Source
AI summary
A method for wireless backhaul inter-node communication between a first backhaul node and a second backhaul node is provided. The method includes computing a beamforming weight matrix W; and the first backhaul node using the beamforming weight matrix W to transmit and/or receive data to and/or from the second backhaul node. The beamforming matrix W is computed as the inverse of a weighted channel estimate matrix (Formula I), such that W=(Formula II), where Ĥ is a channel estimate matrix and ρ is a weighting factor matrix such that (Formula III) where ρ has dimension Nrx by Ntx, where Nrx is the number of receive antennas and Ntx is the number of transmit antennas, where Ntx,=Nrx, and ρ is a scalar between 0 and 1, and where ∘ denotes a Hadamard matrix product.