Pilot-Based Sampling Timing Compensation in Multi-Carrier Receivers
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Solution Overview
Problem
Multi-carrier communication systems face performance degradation due to accumulated sampling timing offset caused by synchronization errors, leading to inter-symbol interference (ISI) and inter-carrier interference (ICI), which existing technologies fail to effectively compensate for.
Innovation Solution
Incorporating pilot signals in the system to estimate and compensate sampling timing offset through a pilot subchannel estimator, timing offset estimator, and phase rotator, allowing for accurate phase rotation and cyclic prefix adjustments to correct symbol boundary errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If guard interval is added to prevent inter-symbol interference, then signal reliability is improved, but system bandwidth efficiency deteriorates
Solution Approach 1:
The patent applies preliminary action by estimating and compensating sampling timing offset before signal demodulation. The timing offset estimator calculates the offset using pilot signals, and the compensation unit corrects the received signal accordingly, preventing ISI degradation before it impacts the main data transmission, thus maintaining both reliability and efficiency
2Measurement precision
If sampling frequency offset compensation is performed, then sampling timing accuracy is improved, but system complexity increases
Solution Approach 1:
The patent uses pilot signals as an intermediary to estimate sampling timing offset. These known pilot signals are inserted in the time domain, and their correlation with received signals provides a straightforward method to calculate timing offset without requiring complex algorithms, thus achieving high accuracy with moderate complexity
Solution Approach 2:
The patent replaces complex mechanical or hardware-based timing synchronization mechanisms with a signal-processing approach. By using mathematical correlation between pilot signals and received signals, the system achieves precise timing offset estimation through software/algorithms rather than complex hardware circuits
Data Source
AI summary
The present invention provides an apparatus and an associated method for sampling timing compensation, which can estimate sampling frequency offset between the receiver and transmitter of a multi-carrier system according to estimated frequency responses of two consecutive received symbols within each pilot subchannel, and compensate an accumulated sampling timing offset resulted from the sampling frequency offset. When the accumulated timing offset is not large, the apparatus uses a phase rotator to compensate with a corresponding accumulated phase rotation in frequency domain. When the accumulated timing offset is large, the apparatus first compensates with a specific timing offset in time domain, and then uses the phase rotator to compensate with a phase rotation corresponding to the remaining timing offset in frequency domain. A timing controller is used to compensate with the specific timing offset by adjusting a clock generator or a cyclic prefix remover of the receiver.