TDD Subframe End Detection via Power Curve Integration
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Solution Overview
Problem
Conventional distributed antenna systems are not suitable for Time-Division Duplex (TDD) RF transmission schemes, such as WIMAX, due to their design for Frequency Division Duplex (FDD) systems, and GPS receivers often fail to provide synchronization inside buildings, leading to signal interference and loss.
Innovation Solution
A method for determining the end of a subframe in a TDD system involves sampling signals, integrating power curves, and identifying peaks to determine switching times between uplink and downlink directions, allowing for synchronization without the need for GPS receivers or signal demodulation in distributed antenna systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS receivers are used to provide precise time reference for synchronizing devices in TDD system, then synchronization accuracy is improved, but GPS receivers do not work inside buildings leading to loss of information
Solution Approach 1:
The patent uses signal power integration and peak detection as an intermediary method to determine subframe ends. Instead of relying on GPS receivers that fail indoors, the system processes received TDD signals through integration and rotation operations to identify timing information, effectively mediating between the need for synchronization and the unavailability of GPS signals in building environments.
2Adaptability or versatility
If conventional distributed antenna systems designed for FDD are used for TDD RF transmission, then device compatibility is improved, but signal interference and loss occur due to unsuitability for TDD schemes
Solution Approach 1:
The patent changes the operational parameters of the distributed antenna system by implementing a method that processes TDD-specific signal characteristics. The system performs signal integration over time and applies rotation to the integrated power curve to identify subframe boundaries, adapting the FDD-designed system to handle TDD timing and switching requirements without requiring complete system redesign.
3Measurement precision
If signal demodulation and decoding are performed to extract subframe length information, then synchronization precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential timing information needed for synchronization by integrating signal power and detecting peaks in the rotated power curve. Instead of performing complete signal demodulation and decoding, the system extracts merely the subframe end timing information from the power characteristics of the received signal, significantly reducing processing complexity while maintaining synchronization precision.
Data Source
AI summary
A method for determining an end of a first period in which signals are communicated in a first direction is provided. The method comprises sampling a signal for a period of time up to at least as long as the longest expected length of the first period to obtain a sampled signal. The sampled signal is integrated to obtain an integrated power curve. A reference line is subtracted from the integrated power curve to obtain a rotated power curve. A peak in the rotated power curve is selected as an end of the first period.