DSL Timing Recovery Using Dual-Domain PLL Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In time-division duplexing (TDD) systems, receivers face challenges in maintaining accurate timing synchronization due to discontinuous signal transmission, leading to excessive timing errors and poor system performance.
Innovation Solution
A digital subscriber line (DSL) communication device employs a dual-stage timing recovery method, using a time domain process based on a predefined cyclic prefix portion of a symbol during a downstream TDD frame period to tune a phase locked loop circuit, followed by a frequency domain process on subsequent symbols, ensuring accurate clock signal generation and phase locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the receiver stops receiving signals during upstream frame period in TDD system, then the discontinuous signal transmission is achieved, but timing synchronization accuracy deteriorates and excessive timing errors accumulate
Solution Approach 1:
The patent applies preliminary action by performing timing recovery processes during the downstream frame period before the upstream frame period begins. The time domain timing recovery using cyclic prefix correlation and frequency domain timing recovery using pilot symbol correlation are executed in advance to establish accurate timing synchronization before signal transmission stops, preventing timing error accumulation during the upstream period
Solution Approach 2:
The patent ensures continuity of useful action by implementing a dual-stage timing recovery mechanism that continuously updates timing synchronization parameters during the downstream frame period. The phase-locked loop circuit maintains continuous operation to track timing variations, ensuring uninterrupted timing adjustment capability despite the discontinuous nature of TDD signal transmission
2Device complexity
If single-stage timing recovery is used, then the device complexity is reduced, but timing synchronization accuracy and convergence speed deteriorate
Solution Approach 1:
The patent applies segmentation by dividing the timing recovery process into two distinct stages: time domain timing recovery using cyclic prefix correlation for initial timing acquisition, and frequency domain timing recovery using pilot symbol correlation for fine timing adjustment. This segmented approach allows each stage to specialize in specific aspects of timing synchronization, improving overall accuracy while maintaining manageable complexity through modular processing
Solution Approach 2:
The patent implements local quality by applying different timing recovery methods to different parts of the signal structure. The time domain method processes the cyclic prefix portion for coarse timing alignment, while the frequency domain method processes the pilot symbol portion for precise timing refinement. Each method is optimized for its specific processing target, achieving high overall timing synchronization accuracy
Data Source
AI summary
A timing recovery method includes the following operations: performing a time domain timing recovery process according to a predefined cyclic prefix portion of a first symbol during a downstream time-division duplexing frame period to tune a phase locked loop circuit; and performing a frequency domain timing recovery process according to at least one second symbol that follows the first symbol during the downstream time-division duplexing frame period to tune the phase locked loop circuit.