Adaptive Beamforming Antenna for OFDM Uplink Interference Rejection
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Solution Overview
Problem
In 5G NR systems, link reciprocity may not provide the best beam selection for uplink transmissions due to interfering signals, making it challenging to accurately receive data streams, especially in ultra-high frequency ranges.
Innovation Solution
The method involves forming matrices from cyclic prefix and tail values of OFDM symbols to determine a beam identifier, which selects an optimal beam pattern for uplink transmissions without relying on signal characteristics typically used for beamformer selection, allowing for adaptive beam selection and interference rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If beam selection is based on downlink beamformer feedback using link reciprocity, then the beam selection process is simplified and can be implemented efficiently, but the accuracy of beam selection deteriorates in the presence of interfering signals
Solution Approach 1:
Instead of using downlink feedback to determine uplink beams (conventional approach), the patent inverts the approach by using uplink signal characteristics (cyclic prefix and tail values) to determine the optimal uplink beam. This inversion allows the system to directly optimize for uplink reception quality rather than relying on reciprocity assumptions that fail in interfered environments.
Solution Approach 2:
The system uses the uplink transmission signal itself (its cyclic prefix and tail values) to determine the optimal beam for receiving that same uplink signal. The uplink signal serves its dual purpose of both data transmission and beam selection feedback, eliminating the need for separate downlink feedback mechanisms.
2Adaptability or versatility
If conventional beam selection methods are used that rely on signal characteristics, then beam selection can be performed with available information, but the system cannot reject interfering signals effectively
Solution Approach 1:
The patent converts the harmful effect of interfering signals into a useful measurement tool. By analyzing differences in cyclic prefix and tail values, the system can identify and reject beams that are contaminated by interference, turning the presence of interference into an opportunity for improved beam selection through differential analysis.
Solution Approach 2:
The cyclic prefix and tail value analysis serves as an intermediary mechanism between the uplink transmission and beam selection decision. This intermediary process extracts beam quality information from the signal structure itself, enabling interference rejection without requiring direct knowledge of interfering signal characteristics.
3Measurement precision
If the system requires knowledge of signal statistics for beam selection, then beam selection can be optimized, but the complexity of the selection process increases
Solution Approach 1:
The system extracts all necessary beam selection information from the signal structure itself (cyclic prefix and tail values) without requiring external signal statistics or additional training sequences. The OFDM signal's own structure provides the measurement data needed for beam selection.
Solution Approach 2:
The patent changes the measurement parameters from traditional signal strength or quality metrics to structural parameters (cyclic prefix and tail value differences). This parameter change enables beam selection based on the inherent structure of OFDM signals rather than requiring statistical knowledge of the transmitted signal.
Data Source
AI summary
Methods and apparatus for providing an adaptive beamforming antenna for OFDM-based communication systems. In one embodiment, a method includes forming a matrix (A) of cyclic prefix values and a matrix (B) of tail values from an orthogonal frequency division multiplexed (OFDM) symbol, and forming a summation matrix (S) and a difference matrix (D) from the matrix A and the matrix B. The method also includes multiplying a beamformer preset matrix (W) with the matrix S and the matrix D to determine a matrix (P) and a matrix (Q), and determining a beam identifier from the P and Q matrices.