Adaptive Phase Tracking for Wireless Radio Receivers
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Solution Overview
Problem
High throughput wireless communication systems operating at high carrier frequencies face significant impairments due to phase noise, which deteriorates signal quality and channel estimation accuracy, particularly in 5G systems where phase variations are more pronounced.
Innovation Solution
A wireless radio receiver is designed with a post-equalization phase tracking unit that estimates and compensates for phase drift by computing absolute phase rotations, subdividing signal blocks into groups, and interpolating phase drift using accumulated phases to generate phase compensation signals, combined with pre-equalization phase tracking for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oscillators are used to generate sinusoidal signals for up-conversion and down-conversion, then frequency and phase generation is achieved, but phase noise and random phase variation occur that deteriorate signal quality
Solution Approach 1:
The patent converts the harmful phase noise into a measurable parameter by using pilot symbols to estimate phase rotation. The estimated phase rotation is then used to compensate for the phase noise effects, transforming the harmful phase variation into a correctable parameter that improves signal quality.
Solution Approach 2:
The patent implements feedback by continuously estimating the phase rotation from pilot symbols and using this estimation to adjust the phase compensation. The feedback loop measures the actual phase noise, computes the compensation, and applies it to correct the signal, thereby maintaining high signal quality despite oscillator imperfections.
2Measurement precision
If phase variations are not accounted for correctly, then signal processing can be simplified, but channel estimation quality and signal quality measures deteriorate
Solution Approach 1:
The patent segments the signal processing into distinct phases: pilot symbol processing for phase estimation, channel estimation, equalization, and phase compensation. This segmentation allows each component to be optimized independently, improving channel estimation quality while managing processing complexity through modular design.
Solution Approach 2:
The patent performs preliminary phase estimation using pilot symbols before the main signal processing. By pre-compensating for phase noise effects using the estimated phase rotation from pilot symbols, the system simplifies subsequent channel estimation and equalization processes, improving overall measurement precision without excessive complexity.
3Productivity
If 5G wireless systems operate at higher carrier frequencies, then throughput is improved, but phase noise becomes a dominating impairment
Solution Approach 1:
The patent changes the parameter approach by adapting the phase compensation based on the operating frequency and channel conditions. The system estimates phase rotation and adjusts compensation parameters dynamically, allowing 5G systems to operate at higher carrier frequencies with improved throughput while mitigating the dominating phase noise impairment through frequency-adaptive compensation.
Data Source
AI summary
A post-equalization phase tracking unit, for each signal block of a received series: computes beginning absolute phase rotation using equalized preceding pilot symbols; subdivides the block into a time sequence of groups of equalized symbols; initializes accumulated phase associated with the first-in-time group with the absolute phase rotation. For each group, the unit: computes a de-rotated version of each symbol using the previous group's accumulated phase used to blindly estimate a residual group phase; assigns the group's accumulated phase with a sum of the group's residual phase and the previous group's accumulated phase; estimates phase drift within the group by using at least the group's accumulated phase to compute a phase compensation signal. A pre-equalization phase tracking unit computes a phase of autocorrelation between identical-as-transmitted initial/terminal sequence portions; estimates a start phase using the autocorrelation phase and the previous signal block start phase; interpolates start phases to estimate phase drift.