Multichannel Receiver Phase Noise Correction via Common Estimate
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Solution Overview
Problem
Multichannel communication systems, such as cable and OFDM systems, face performance degradation due to phase noise, which existing methods struggle to effectively address, especially in systems using higher-order modulation schemes like 256 or 1024 QAM, as phase noise from one subcarrier acts as additive noise to others, affecting receiver performance.
Innovation Solution
A method and apparatus that process multiple received signals simultaneously to estimate and correct phase noise by generating a common noise estimate, which is then provided to demodulators to improve receiver performance, involving weighting of phase error signals and combining them to generate a common phase error feedback signal for noise correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase noise correction is performed using traditional single-channel methods, then phase noise can be suppressed within a single channel, but phase noise from each subcarrier creates a noise skirt that acts as additive noise to other subcarriers and cannot be removed
Solution Approach 1:
The patent combines phase noise correction across multiple channels by merging phase error signals from different subcarriers. Instead of treating each channel independently, the system aggregates phase error information from multiple subcarriers to create a comprehensive phase noise estimate that accounts for inter-subcarrier interference, thereby resolving the noise skirt problem.
Solution Approach 2:
The invention creates a universal phase noise correction mechanism that serves multiple subcarriers simultaneously. A single phase noise estimate derived from multiple channels is applied across all subcarriers, making the correction system multi-functional rather than dedicated to individual channels, thus eliminating the noise skirt effect on other subcarriers.
2Productivity
If higher-order modulation schemes such as 1024-point QAM are used to accommodate additional bandwidth demand, then bandwidth capacity increases, but phase noise performance requirements become more stringent and receiver performance degrades
Solution Approach 1:
The patent implements a feedback mechanism where phase error signals from multiple subcarriers are continuously monitored and fed back to generate corrected phase estimates. This feedback loop allows the system to dynamically adjust phase correction based on actual received signal conditions, maintaining receiver performance even with higher-order modulations that are more susceptible to phase noise.
Solution Approach 2:
The invention creates a composite phase correction approach by combining phase error information from multiple different subcarriers. Rather than relying on a single channel's phase information, the system synthesizes a composite phase noise estimate from multiple sources, providing more robust correction for high-order QAM systems where phase noise critically impacts performance.
3Measurement precision
If multiple channels are processed simultaneously to generate a common phase noise estimate, then phase noise is suppressed across the entire spectrum and demodulation accuracy improves, but processing complexity increases
Solution Approach 1:
The patent segments the phase noise correction process into distinct stages: first collecting phase error signals from multiple subcarriers, then processing these signals to generate a common phase estimate, and finally applying the correction. This segmentation allows the system to manage processing complexity by breaking down the simultaneous multi-channel processing into manageable sequential operations while still achieving spectrum-wide phase noise suppression.
Data Source
AI summary
Methods and apparatus for processing multichannel signals in a multichannel receiver are described. In one implementation, a plurality of demodulator circuits may provide a plurality of outputs to a processing module, with the processing module then simultaneously estimating noise characteristics based on the plurality of outputs and generating a common noise estimate based on the plurality of outputs. This common noise estimate may then be provided back the demodulators and used to adjust the demodulation of signals in the plurality of demodulators to improve phase noise performance.