Kalman PLL Re-Encoded Phase Detection for Offset Tracking
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Solution Overview
Problem
In wireless communications systems, frequency and phase offsets between the local oscillator of the receiving device and the carrier wave generated by the transmitting device introduce errors in data recovery, necessitating effective techniques for offset estimation and compensation.
Innovation Solution
A method and device employing a Kalman filter based phase-locked loop with a re-encoding-based phase detector to compute error signals, generate correction signals, and use modified Viterbi decoders for improved phase and frequency tracking, incorporating soft-decision decoding and re-encoding techniques to enhance data recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional phase-locked loop techniques are used for frequency and phase offset compensation, then the system can maintain basic coherence, but the accuracy of data recovery deteriorates due to noise and frequency drift
Solution Approach 1:
The patent applies preliminary action by performing soft-decision decoding and re-encoding to generate a preliminary decoded signal before phase detection. This preliminary processing prepares more accurate reference information in advance, allowing the phase detector to work with pre-refined data that has already undergone error correction processing, thereby improving both measurement precision and reliability
Solution Approach 2:
The patent implements feedback by using the preliminarily decoded signal to generate a re-encoded reference signal that feeds back to the phase detector. This closed-loop feedback mechanism continuously refines the phase offset estimation using decoded information, improving the accuracy of both phase measurement and subsequent data recovery through iterative correction
2Reliability
If the traceback length of Viterbi decoder is increased to improve decoding accuracy, then data recovery reliability improves, but processing time and system complexity increase
Solution Approach 1:
The patent applies partial action by using a preliminary traceback length that is shorter than the full traceback length for generating the preliminary decoded signal. This allows the system to obtain sufficiently accurate decoded information faster, without waiting for the complete Viterbi decoding process, thereby reducing processing delay while maintaining adequate decoding accuracy for phase detection purposes
Data Source
AI summary
A wireless communications device includes a receiver having a phase detector configured to extract frequency offset and provide a corresponding error signal generated based on a baseband version of a received radio frequency signal and an expected transmitted data signal. The receiver has a phase-locked loop configured to generate an error correction signal based on a phase of the error signal and a predicted instantaneous phase of the error signal. The receiver has a correction circuit configured to provide a corrected baseband version of the received radio frequency signal based on the baseband version of the received radio frequency signal and the error correction signal. The receiver may have a re-encoding-based processing circuit configured to provide the expected transmitted data signal based on a preliminarily decoded symbol.