Reference Signal Placement for Single-Filter Frequency Offset Estimation
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Solution Overview
Problem
Devices with low-precision oscillators or no crystal oscillator, such as wake-up receivers, suffer from frequency drift, leading to inaccurate filtering of target signals and reduced demodulation performance due to the inability to estimate frequency offset effectively, especially when only one filter is present.
Innovation Solution
A method for frequency offset estimation using a first reference signal transmitted at specific frequency domain positions within a bandwidth, allowing for envelope detection with a single filter, expanding the applicability of frequency offset estimation to scenarios with limited filter resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple filters are used for frequency offset estimation, then frequency offset estimation accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The bandwidth is divided into multiple frequency bands (first frequency band, second frequency band, etc.), with each band containing specific frequency domain positions. The reference signal is transmitted at these segmented frequency positions, allowing a single filter to process different frequency components separately, achieving frequency offset estimation without requiring multiple filters.
Solution Approach 2:
The solution transitions from using multiple filters in the frequency domain to using a single filter processing signals at different frequency domain positions. By exploiting the frequency domain dimension and transmitting reference signals at specific frequency positions (first frequency domain position, second frequency domain position), the system achieves the functionality of multiple filters using only one filter.
2Device complexity
If a single filter is used in the receiver, then device cost and complexity are reduced, but frequency offset estimation capability is lost
Solution Approach 1:
The single filter is designed to handle multiple frequency bands and multiple frequency domain positions within those bands. By making the filter universal and configurable to process different frequency ranges, the system achieves frequency offset estimation capability with only one filter, rather than requiring dedicated filters for each frequency band.
Solution Approach 2:
The system changes the frequency domain position parameter of the reference signal transmission. By transmitting reference signals at different frequency domain positions (first frequency domain position, second frequency domain position) within different frequency bands, the single filter can estimate frequency offset for various frequency ranges by processing these parameter-varying reference signals.
3Device complexity
If frequency offset is not estimated and corrected, then processing simplicity is maintained, but demodulation performance deteriorates
Solution Approach 1:
Frequency offset estimation is performed in advance before demodulation by processing the reference signal transmitted at specific frequency domain positions. This preliminary frequency offset estimation allows the system to correct frequency drift before the actual demodulation process, ensuring high demodulation performance without adding complex real-time correction mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the precision of frequency offset estimation in devices with limited filter capabilities, improving demodulation performance by accurately determining and adjusting for frequency offsets.
Implementation Method 1
the first device performs envelope detection on a reference signal used for frequency offset estimation by using each of multiple filters
Data Source
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AI summary
A signal transmission method and communication device are provided. The method includes the following. A first device receives a first reference signal at a target frequency domain position within a first bandwidth. The first reference signal is used for frequency offset estimation. The target frequency domain position includes one or more of a first frequency domain position and a second frequency domain position. The first frequency domain position is within a first frequency band in the first bandwidth, where a frequency of the first frequency band is higher than a frequency domain of each frequency band other than the first frequency band in the first bandwidth. The second frequency domain position is within a second frequency band in the first bandwidth, where a frequency of the second frequency band is lower than a frequency domain of each frequency band other than the second frequency band in the first bandwidth. In the disclosure, the first reference signal is transmitted at the first frequency domain position and/or the second frequency domain position within the first bandwidth. Compared with a frequency offset estimation method based on multiple filters, the method in the embodiments of the disclosure does not overly limit the number of filters in the first device, which helps to expand the applicable scenarios of the frequency offset estimation method.