Low Complexity Sampling Recovery Method and Apparatus
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Solution Overview
Problem
Existing sampling recovery methods in communication systems face challenges in achieving high precision at low sampling rates, particularly in mobile environments, due to limitations in phase and frequency offset correction, hardware resource utilization, and complexity in OFDM and spread spectrum systems.
Innovation Solution
A method and apparatus that utilize a sampling rate conversion module, time domain impulse response estimation, high order interpolation, and sampling error information extraction to achieve high precision sampling phase locking and frequency offset correction at a relatively low sampling rate, employing a digitally controlled oscillator and smoothing filters to reduce noise influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If early-late gate algorithm is employed to extract sampling phase offset information, then sampling recovery precision is improved, but system operating rate must be increased which leads to increased implementation complexity
Solution Approach 1:
The patent changes the operating parameter from high sampling rate to low sampling rate by introducing a sampling rate conversion module. This module converts the received signal from low sampling rate to a higher intermediate rate for processing, then converts back to low rate for output, allowing the use of complex algorithms like early-late gate without the hardware complexity of continuously operating at high rate
Solution Approach 2:
The patent segments the signal processing into distinct stages: sampling rate conversion to intermediate rate, channel impulse response estimation, optimal sampling point detection using early-late gate algorithm, and final rate conversion back to original rate. This segmentation allows complex operations to be performed only when needed at intermediate stages rather than continuously at high rate
2Measurement precision
If pilot-based sampling recovery method is used, then sampling phase offset can be estimated, but performance is affected by number of pilots and may fail in mobile environments with fading
Solution Approach 1:
The patent introduces channel impulse response estimation as an intermediary step between signal reception and sampling recovery. By estimating the channel impulse response first (using methods like matched filtering or correlation), the system obtains a channel-compensated signal where sampling phase offset can be more accurately detected even in mobile fading environments, and the method does not rely heavily on pilot signals
3Measurement precision
If continuous tracking of strongest path is performed at symbol rate to correct sampling frequency offset, then sampling frequency recovery is achieved, but the method is affected by mobile environment and multipath distribution changes
Solution Approach 1:
The patent implements dynamic adaptation by continuously estimating channel impulse response and re-detecting optimal sampling points based on current channel conditions. The system can track changes in multipath distribution and fading conditions by repeatedly performing channel estimation and sampling point detection, allowing it to adapt to mobile environments rather than relying on continuous tracking of a single strongest path
Solution Approach 2:
The patent employs feedback mechanisms where the detected sampling phase and frequency offset information is used to adjust the sampling clock, and the process is repeated with updated channel estimates. This closed-loop feedback allows the system to continuously correct for drift and adapt to changing channel conditions in mobile environments
Data Source
AI summary
Method and apparatus for achieving high precision sampling recovery at a relatively low sampling rate. The apparatus includes: a sampling rate conversion module for converting the sampling rate of a received signal to an required sampling rate; a time domain impulse response estimation module for estimating a time domain impulse response of a transmission channel according to data output by the sampling rate conversion module; a high order interpolation module for performing high order interpolation to one or more selected transmission paths after obtaining the time domain impulse response; and a sampling error information extraction module for extracting sampling phase offset information and sampling frequency offset information based on interpolation results and drifts in two consecutive interpolation results of the high order interpolation step. The apparatus is capable of realizing fast high precision locking of sampling phase and correction of sampling frequency offset at a relatively low sampling rate.