Baseband Frequency Offset Circuit for Payload Tracking Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for removing frequency offset in wireless communication systems face a trade-off between tracking characteristic and accuracy, and often fail to accurately track frequency offset in payload sections due to errors in detecting access codes and recognizing preamble data patterns.
Innovation Solution
A circuit and method that samples the baseband signal at 0.5 symbol intervals, calculates first and second difference absolute values, and sets the frequency offset based on predetermined determination values, allowing for precise and rapid tracking of frequency offset throughout the payload section without requiring a preamble detection circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the predetermined time period for calculating amplitude average value is set short, then tracking characteristic of frequency offset removal is increased, but accuracy of frequency offset removal is relatively low
Solution Approach 1:
The patent dynamically adjusts the time period for calculating amplitude average value based on the current state of frequency offset tracking. When tracking characteristic needs improvement, the time period is shortened; when accuracy needs improvement, the time period is lengthened. This dynamic adjustment resolves the contradiction by allowing the system to optimize between speed and precision based on real-time requirements.
Solution Approach 2:
The patent changes the parameter of time period duration to balance tracking characteristic and accuracy. By making the time period adjustable rather than fixed, the system can optimize performance for different operational conditions, resolving the trade-off between rapid tracking and precise measurement.
2Measurement precision
If frequency offset is calculated from preamble data pattern, then frequency offset removal accuracy is improved, but the offset cannot be tracked to the extent of payload section when offset occurs in payload section
Solution Approach 1:
The patent performs preliminary frequency offset calculation using preamble data pattern to establish an initial accurate offset value. This preliminary action provides a starting point for subsequent tracking into the payload section, allowing the system to maintain accuracy while adapting to changing offset conditions in the payload.
Solution Approach 2:
The patent continues the frequency offset calculation and tracking action from the preamble through the payload section without interruption. By maintaining continuous monitoring and calculation, the system ensures that frequency offset changes occurring in the payload section are detected and tracked, extending the useful action beyond the preamble into the payload.
3Measurement precision
If preamble data pattern recognition is used for frequency offset calculation, then accuracy is improved, but frequency offset cannot be calculated when error occurs in detecting access code
Solution Approach 1:
The patent introduces an intermediary mechanism that provides alternative paths for frequency offset calculation. When access code detection fails and preamble recognition cannot proceed, the system uses alternative methods or default values to maintain frequency offset calculation, ensuring reliability while preserving accuracy when conditions permit.
Solution Approach 2:
The patent prepares backup methods and fallback mechanisms in advance for frequency offset calculation. By having pre-established alternative calculation paths, the system cushions against failures in access code detection and preamble recognition, maintaining reliability even when primary methods fail.
Data Source
AI summary
A circuit and a method for removing a frequency offset and a communication apparatus including the circuit, capable of removing the frequency offset by tracking rapidly and accurately in a payload section. A sequence of sample levels is obtained by sampling a frequency level of the baseband signal at every 0.5 symbol interval. Absolute values of differences between the frequency levels adjacent to each other at every 1 symbol are calculated as first difference absolute values. Absolute values of differences between the frequency levels adjacent to each other at every 1 symbol are calculated as second difference absolute values. When the first difference absolute values are greater than a predetermined first determination value or the second difference absolute values are less than a predetermined second determination value, the average value calculated is set as the frequency offset.