TDD Synchronization Using Slide Window Normalization
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Solution Overview
Problem
Time division duplex (TDD) systems face challenges in synchronization due to strong UE-to-UE interference, which can prevent a receiver from detecting the network, especially during uplink periods, leading to difficulties in cell search and network access.
Innovation Solution
A method and apparatus that utilize a slide window based normalization of the decision time metric, correlating the received signal with a replica signal to detect synchronization patterns, and applying a long enough time window to accommodate the uplink period, enhancing robustness against interference and improving cell detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional autocorrelation-based synchronization is used in TDD systems, then the method is simple and computationally efficient, but the synchronization performance deteriorates under strong UE-to-UE interference during uplink periods
Solution Approach 1:
The patent segments the received signal into multiple candidate synchronization patterns and processes each segment separately through autocorrelation. By dividing the search space into discrete candidates and evaluating them individually, the system can identify the true synchronization pattern even when strong interference affects other segments, thereby improving synchronization reliability under UE-to-UE interference
Solution Approach 2:
The patent changes the parameter being measured from raw correlation magnitude to a normalized metric that accounts for interference characteristics. By computing a decision metric that compares autocorrelation values across multiple candidates and selecting based on relative performance rather than absolute values, the system becomes robust to varying interference levels during uplink periods
2Reliability
If the time window for normalization is extended to accommodate the uplink period, then interference robustness is improved, but the computational complexity and processing time increase
Solution Approach 1:
The patent performs preliminary autocorrelation computations for all candidate synchronization patterns before making the final selection decision. By pre-computing correlation values for multiple candidates and storing them, the system avoids repeated computations during the selection phase, thereby reducing overall processing time while maintaining robustness through the use of extended normalization windows
Solution Approach 2:
The patent computes autocorrelation for a limited set of candidate synchronization patterns rather than exhaustively searching all possible patterns. By focusing computational resources on a selective subset of likely candidates and using normalized comparison to identify the best match, the system achieves interference robustness with reduced processing time compared to exhaustive search methods
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 significantly enhances cell detection performance by making synchronization more robust to interference, achieving up to 9dB performance gain compared to conventional methods, even under high interference conditions, and ensures reliable network access in TDD systems.
Implementation Method 1
obtaining a decision time metric by correlating said received signal with a replica signal in order to detect a synchronization pattern provided in said first time period
Implementation Method 2
applying to said decision time metric a slide window based normalization with a time window long enough to accommodate said second time period
Data Source
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AI summary
The present invention relates to a method, apparatus, system and computer program product, wherein a time division multiplex signal is received with a periodic first time period allocated to a downlink transmissions and a periodic second time period allocated to uplink transmissions. A decision time metric is obtained by correlating the received signal with a replica signal in order to detect a synchronization pattern provided in the first time period. Then, a slide window based normalization with a time window long enough to accommodate said second time period is applied to the decision time metric.