DSS Reference Signal Cancellation for LTE-to-NR CRS Interference
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Solution Overview
Problem
Dynamic spectrum sharing (DSS) in 5G NR networks faces interference from LTE cell-specific reference signals (CRS) that compromise spectral efficiency, particularly due to non-colliding interference from neighboring LTE cells, which limits system throughput and capacity.
Innovation Solution
Implementing non-collider CRS interference cancellation techniques that account for differences in DC subcarrier usage and OFDM modulation between LTE and NR, including CRS extraction, phase compensation, and frequency offset estimation to mitigate interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DSS is implemented to share spectrum between LTE and NR cells, then spectrum utilization is improved, but interference from LTE CRS on NR cells increases
Solution Approach 1:
The patent extracts the harmful LTE CRS interference from the received signal and reconstructs it using channel estimation and reference signal knowledge. By inverting the harmful interference into a reconstructible component, the system can then subtract it to reveal the underlying NR data signal, effectively converting the harmful interference into a removable artifact.
Solution Approach 2:
The patent employs rate matching techniques to identify and extract resource elements occupied by LTE CRS from the composite received signal. By separating the CRS components from the NR signal in the frequency domain, the system isolates the interference for subsequent cancellation operations.
2Object-affected harmful factors
If rate matching is used to avoid LTE CRS resources, then interference is reduced, but spectral efficiency deteriorates due to unused resources
Solution Approach 1:
Instead of leaving CRS-occupied resources idle as traditional rate matching requires, the patent actively cancels the CRS interference from these resources. This allows NR data to be transmitted on the same resource elements, transforming previously wasted spectral resources into productive communication channels.
Solution Approach 2:
The patent changes the approach from passive resource avoidance to active interference cancellation. By modifying the received signal through subtraction of the reconstructed CRS component, the system enables data transmission on resources that would traditionally be excluded, thereby improving spectral efficiency.
3Productivity
If interference cancellation is implemented, then spectral efficiency is improved, but device complexity increases
Solution Approach 1:
The patent performs channel estimation and CRS reconstruction before the actual interference cancellation operation. By preparing the interference template in advance using known reference signal structures and estimated channel responses, the system simplifies the final subtraction operation and reduces real-time processing requirements.
Solution Approach 2:
The patent creates a reconstructed copy of the LTE CRS interference based on channel estimation and reference signal knowledge. This copy serves as a template that can be subtracted from the received signal, avoiding the need for complex real-time interference characterization and simplifying the cancellation process.
Data Source
AI summary
The present application relates to devices and components including apparatus, systems, and methods for canceling reference signal interference in dynamic spectrum sharing networks.