Frequency-Range Channel Estimation for Preserved Signal Orthogonality
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Solution Overview
Problem
Conventional channel estimation methods in New Radio (NR) radio communication systems fail to maintain orthogonality between cyclic shifts of base sequences and/or demodulation reference signals (DM-RS) due to averaging techniques that are not suitable for dispersive channels.
Innovation Solution
Perform initial channel estimation over frequency ranges where signal sequences are orthogonal, followed by applying a filter with a length greater than the frequency ranges to obtain a filtered channel estimate, maintaining orthogonality and suppressing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional averaging techniques are applied to channel estimation, then noise is reduced, but orthogonality between cyclic shifts of base sequences and DM-RS is destroyed
Solution Approach 1:
The patent segments the frequency domain into multiple frequency ranges, where each range is designed to maintain orthogonality of signal sequences. By performing channel estimation separately in each frequency range and then combining results, the method reduces noise while preserving orthogonality within each segment.
Solution Approach 2:
The patent applies different processing approaches to different frequency ranges based on local characteristics. Each frequency range is treated independently with respect to orthogonality maintenance, allowing the system to adapt to local channel conditions while preserving the critical orthogonality property needed for multi-user multiplexing.
2Loss of information
If channel estimation is performed over the entire frequency band, then more channel information is obtained, but orthogonality between signal sequences cannot be maintained in dispersive channels
Solution Approach 1:
The patent divides the entire frequency band into multiple smaller frequency ranges, each maintaining orthogonality of signal sequences. This segmentation allows the system to collect channel information across the full bandwidth while ensuring that orthogonality is preserved within each range, solving the contradiction between comprehensive information gathering and orthogonality maintenance.
Solution Approach 2:
The patent introduces a new dimension of processing by operating in both the frequency range dimension (for orthogonality) and the combination dimension (for comprehensive information). By structuring the estimation process across these dimensions, the system achieves both goals simultaneously.
3Object-affected harmful factors
If filtering is applied to channel estimates, then noise suppression is improved, but the filter length must be carefully managed to maintain orthogonality
Solution Approach 1:
The patent segments the filtering operation to be applied within each frequency range separately, with filter lengths adapted to the specific orthogonality requirements of each range. This segmented approach simplifies filter length management compared to applying a single long filter across the entire bandwidth, as each filter operates on a smaller, more manageable frequency subset.
Data Source
AI summary
A method of performing channel estimation for a radio channel between a transmitter and a receiver of a radio access network, RAN comprises the step of performing an initial channel estimation (204) of the radio channel for each of a plurality of frequency ranges (502), based on a radio signal received on the radio channel from the transmitter, the radio signal comprising a signal sequence (510) out of the set of signal sequences (510) in each of the frequency ranges (502), to obtain an initial channel estimate (504) for each frequency range (502), and applying a filter (206) to the initial channel estimates (504) for the frequency ranges (502), a length (508) of the filter (206) in the frequency domain being greater than lengths of the frequency ranges (502), to obtain a filtered channel estimate (506) for all subcarriers (406) in the respective one of the frequency ranges (502).