Dual-Branch Receiver Frequency Offset Correction for Accurate Demodulation
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Solution Overview
Problem
In wireless communication systems, frequency offset errors in local oscillator signals lead to demodulation performance issues, as they result in errors in the baseband signal obtained by demodulating received signals.
Innovation Solution
A communication apparatus is designed to perform frequency offset correction on its local oscillator signal, using amplitude information obtained from frequency mixing processes. This correction is achieved by adjusting the local oscillator signal based on the amplitude information, thereby reducing frequency offset errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If frequency mixing is performed using a local oscillator signal with frequency offset, then down-conversion processing is completed, but frequency offset errors are introduced in the baseband signal
Solution Approach 1:
The patent applies preliminary action by performing frequency offset correction before the frequency mixing process. The receiving device estimates the frequency offset in advance and compensates for it in the local oscillator signal generation stage, preventing the introduction of frequency offset errors during down-conversion. This ensures that the frequency mixing operation uses a corrected local oscillator signal, thereby maintaining baseband signal accuracy while preserving processing speed.
2Adaptability or versatility
If a larger linear working interval is used for frequency-amplitude conversion, then frequency offset tolerance is improved, but demodulation precision is reduced
Solution Approach 1:
The patent resolves this contradiction by performing frequency offset correction before the frequency-amplitude conversion process. By estimating and compensating for frequency offset in advance, the system can use a frequency-amplitude converter with a larger linear working interval to accommodate frequency variations, while the preliminary correction ensures that the actual operating point remains within the precise demodulation range. This sequential approach allows both tolerance and precision to be optimized.
Solution Approach 2:
The patent employs feedback by implementing a frequency offset estimation and correction loop. The receiving device continuously monitors the received signal for frequency offset, estimates the offset amount, and feeds back a correction signal to adjust the local oscillator frequency. This closed-loop feedback mechanism dynamically maintains accurate demodulation despite frequency variations, allowing the use of a larger linear working interval without sacrificing precision.
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
The proposed solution effectively reduces errors in the baseband signal, thereby improving demodulation performance by correcting frequency offset errors in the local oscillator signal.
Implementation Method 1
The first frequency-amplitude converter is configured to obtain first amplitude information of a third signal, where the third signal is a signal obtained by performing frequency mixing on the first signal and a first local oscillator signal
Data Source
AI summary
An apparatus with a first branch and a second branch that is configured to receive a first signal and a second signal from a same device, where the second signal indicates the apparatus to enter a connected state. The first branch includes a first frequency-amplitude converter configured to obtain first amplitude information of a third signal which is obtained by performing frequency mixing on the first signal and a first local oscillator signal. The second branch is configured to demodulate a fourth signal which is obtained by performing frequency mixing on the second signal and a second local oscillator signal which is obtained by performing frequency offset correction on the first local oscillator signal based on the first amplitude information, the second branch includes a second frequency-amplitude converter, and a linear working interval of the second frequency-amplitude converter is smaller than that of the first frequency-amplitude converter.