Cyclic Correlation Window for Cellular Round Trip Delay
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Solution Overview
Problem
Existing methods for estimating round trip delays in cellular communication systems using a fixed correlation window result in increased self noise and decreased accuracy, particularly when minimizing the size of the signature receiving time slot.
Innovation Solution
A method that optimizes the signature receiving time slot size by using a cyclic correlation process with a fixed correlation window, employing CAZAC sequences and cyclic extensions to accurately determine round trip delays while minimizing interference with scheduled traffic data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a fixed correlation window is used to minimize the size of the signature receiving time slot, then the time slot size is reduced, but the self noise generated by the correlation process increases and round trip delay estimation accuracy decreases
Solution Approach 1:
The patent applies dynamics by making the correlation window size adaptive rather than fixed. The correlation window dynamically adjusts its size based on the detected round trip delay value, allowing the system to minimize the signature receiving time slot for small delays while expanding the window for larger delays to maintain estimation accuracy. This resolves the contradiction by making the window size variable according to actual channel conditions.
Solution Approach 2:
The patent changes the parameter of correlation window size based on the detected round trip delay. By adjusting this key parameter dynamically, the system optimizes the balance between time slot minimization and estimation accuracy. The correlation window size is modified as a function of the measured delay, allowing the system to adapt to different propagation conditions and resolve the trade-off between slot size and accuracy.
2Measurement precision
If a sliding correlation window or comb correlating architecture is used, then round trip delay estimation accuracy is maintained, but the signature receiving time slot size cannot be minimized
Solution Approach 1:
The patent implements a dynamic correlation window that adapts its size based on the detected round trip delay, replacing the need for sliding windows or comb architectures. This dynamic approach allows the system to use a fixed, minimized time slot while achieving accurate estimation by adjusting the window size according to the actual delay value detected within that slot.
Solution Approach 2:
The patent segments the correlation process into two stages: first, a coarse detection phase using a minimized fixed time slot to identify the rough delay position; second, a refined estimation phase using an adaptive correlation window sized according to the detected delay. This segmentation allows the system to minimize the overall time slot while maintaining accuracy through staged processing.
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
This approach enhances the accuracy of round trip delay estimation while maintaining a minimized signature receiving time slot size, reducing self noise and improving synchronization in cellular communication systems.
Implementation Method 1
When using a usual correlation process in time domain the size of the signature receiving time slot cannot be minimized while limiting the self noise generated by the correlation process
Data Source
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AI summary
The method for estimating a propagation round trip delay, existing between a base station and a terminal, and comprised within a predetermined round trip delay range, comprises the following steps: transmitting from the base station on a downlink a start order signal (30) to the terminal, after reception by the terminal of the end of the start order signal, sending a signature signal from the terminal to the base station on a uplink, receiving at the base station within a signature receiving time slot (28) the signature signal (34, 38, 42), processing at the base station the received signature signal to provide a round trip delay information. The processing step comprises a cyclic correlation step performed within a fixed correlation time window (54) by using a unique reference sequence (48).