CFO and STO Estimation Using Shifter-Based Band Extraction
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Solution Overview
Problem
Current communication receiver designs face complexity in estimating Carrier Frequency Offset (CFO) and Symbol Timing Offset (STO) due to dependencies and sensitivity issues, leading to inaccurate estimations and performance degradation, especially in low power devices.
Innovation Solution
The system replaces multipliers with shifters and uses a band extraction block to extract upper and lower band edges for concurrent CFO and STO estimation, incorporating a Phase Lock Loop (PLL) and leaky average filter to generate error values and compensate for spectrum tilt, reducing implementation complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If spectrum shape based CFO estimation is used, then implementation complexity is reduced and adaptability is improved, but measurement precision deteriorates due to spectrum tilt impairments
Solution Approach 1:
The patent introduces an intermediary compensation mechanism that uses STO estimation results to correct spectrum tilt effects in CFO estimation. The STO estimator acts as a mediator that provides timing offset information, which is then used to compensate the CFO estimation process, thereby maintaining both low complexity and high accuracy.
Solution Approach 2:
The patent implements a feedback loop where the STO estimation result is fed back to compensate the CFO estimation. This feedback mechanism allows the system to correct spectrum tilt impairments dynamically, improving measurement precision while maintaining the simplicity of spectrum shape based methods.
2Productivity
If concurrent CFO and STO estimation is performed, then acquisition time is reduced and productivity is improved, but device complexity increases due to mutual dependencies
Solution Approach 1:
The patent segments the concurrent estimation process into two independent modules: a CFO estimation module using spectrum shape methods and an STO estimation module using energy maximization. These segmented modules operate independently without mutual dependencies, eliminating the complexity of coordinated control while maintaining concurrent execution capability.
Solution Approach 2:
The patent designs universal estimation algorithms that can independently estimate both CFO and STO parameters. The CFO estimator uses spectrum shape information that is also useful for STO estimation, and vice versa, allowing both functions to be performed by independent but complementary algorithms.
3Ease of operation
If low pass filters are used for band extraction, then filtering performance is improved, but measurement precision deteriorates due to error propagation in filter output
Solution Approach 1:
The patent performs preliminary band extraction using simple filtering operations before the main estimation process. By extracting band edges early in the processing chain and using them directly for estimation without repeated filtering, the system avoids error propagation while maintaining good filtering performance.
Solution Approach 2:
The patent uses simple, computationally inexpensive filtering operations for band extraction rather than complex recursive filters. These simple filters are applied once for band extraction and then the extracted band edges are used directly, avoiding the need for continuous complex filtering that would propagate errors.
Data Source
AI summary
A system and method for reducing implementation complexity for estimation of a Carrier Frequency Offset (CFO) and a Symbol Timing Offset (STO) for an input signal for spectrally shaped multiple communication standards. The system is implemented by replacing multiplier with shifters. The system includes a CFO estimation block, a STO estimation block, and a band extraction block that extracts a lower band edge and an upper band edge of the input signal. The STO estimation block includes (i) a sample error generation block that computes a sampling timing error value, and (ii) a Phase Lock Loop block that estimates a frequency error and a phase error corresponding to the sampling timing error value. The CFO estimation block includes (i) a carrier offset error generation block that generates a carrier offset error value, and (ii) a leaky average block for performing a filter operation.