Multichannel Receiver Phase Noise Correction Using Common Error Feedback
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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 each subcarrier creates additive noise affecting other subcarriers.
Innovation Solution
A method and apparatus that process multiple received signals simultaneously to determine multiple estimates of phase noise, combining these estimates to generate a common noise estimate, which is then provided to demodulators to correct noise errors, thereby enhancing receiver performance by weighting and combining raw phase error signals to generate a common phase error feedback signal for correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase noise correction is performed using traditional single-channel methods, then phase noise in individual channels can be suppressed, but phase noise from other subcarriers acts as additive noise and cannot be removed
Solution Approach 1:
The patent combines phase noise correction across multiple channels by merging phase error measurements from multiple subcarriers to generate a common phase error estimate. This is achieved by collecting phase error measurements from multiple channels, combining them through weighted averaging or other fusion techniques, and applying the common correction to all channels simultaneously, thereby resolving the issue where traditional single-channel methods leave residual phase noise from other subcarriers.
Solution Approach 2:
The patent implements a feedback mechanism where phase error measurements from multiple channels are continuously monitored, combined to generate a common phase error estimate, and fed back to correct the phase noise in real-time. The system measures phase errors, processes them through a feedback loop that combines information from multiple channels, and applies corrective feedback to suppress phase noise across all channels, improving overall system reliability.
2Productivity
If higher-order modulation schemes like 1024 QAM are used to accommodate additional bandwidth demand, then data bandwidth increases, but phase noise performance requirements become more stringent and performance degradation increases
Solution Approach 1:
The patent applies multi-channel phase noise correction that merges phase error information from multiple subcarriers to generate a more accurate common phase error estimate. This combined approach provides better phase noise suppression performance that is essential for maintaining reliable operation of higher-order modulation schemes like 1024 QAM, allowing the system to achieve high data bandwidth while meeting stringent phase noise performance requirements.
3Reliability
If multiple channels are processed simultaneously to generate a common phase error estimate, then phase noise suppression across the entire spectrum is improved, but system complexity increases
Solution Approach 1:
The patent segments the phase noise correction process into distinct functional blocks: phase error measurement units for each channel, a combination unit that processes measurements from multiple channels, and a correction application unit. This segmentation allows the complex multi-channel processing to be organized into manageable modules, reducing implementation complexity while maintaining the benefit of spectrum-wide phase noise suppression.
Solution Approach 2:
The patent creates a universal phase error correction mechanism that serves all channels simultaneously through a common phase error estimate. The combination unit generates a single common correction value that is universally applied to correct phase noise across the entire spectrum, eliminating the need for separate correction mechanisms for each channel and thereby reducing overall system complexity.
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.