Downlink Frame Boundary Detection in TDD Wireless Systems
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Solution Overview
Problem
In wireless communication systems using Time Division Duplexing (TDD), detecting the boundary of a downlink frame is challenging due to interference from uplink frames, especially in poor channel environments, which can lead to failed detection and increased time required for synchronization.
Innovation Solution
An apparatus and method that utilize preamble correlation energy and reception signal strength to detect the boundary of a downlink frame by removing samples with a correlation energy-to-strength ratio below a reference value, and controlling the amplifier gain of the RF/IF module to enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional frame boundary detection methods are used in TDD systems, then the system can operate with dynamic time slot allocation, but the detection accuracy deteriorates due to uplink frame interference especially in poor channel environments
Solution Approach 1:
The patent extracts and removes samples corresponding to uplink frames from the received signal before performing frame boundary detection. By identifying and eliminating the interfering uplink portion, the detection algorithm operates only on clean downlink samples, significantly improving detection accuracy in TDD systems.
Solution Approach 2:
The patent segments the received signal into uplink and downlink portions based on timing information, then processes only the downlink segment for frame boundary detection. This segmentation isolates the detection process from uplink interference while preserving the benefits of dynamic time slot allocation.
2Measurement precision
If hypothesis verification for uplink frame is performed to remove interference, then the detection accuracy improves, but the processing time and complexity increase
Solution Approach 1:
The patent performs preliminary removal of uplink frame samples based on predetermined timing information before the actual frame boundary detection. This preliminary action eliminates the need for complex hypothesis verification during detection, reducing processing time while maintaining high precision.
Solution Approach 2:
The patent changes the parameter being measured by using the ratio of correlation energy to received signal strength as a criterion for identifying uplink samples. This parameter-based approach enables efficient identification and removal of interference without requiring exhaustive hypothesis testing.
3Reliability
If the amplifier gain of RF/IF module is controlled to enhance detection, then the detection capability in poor channel environments improves, but the system complexity increases
Solution Approach 1:
The patent dynamically adjusts the amplifier gain of the RF/IF module based on the detected signal conditions and the identified downlink frame boundary. This dynamic control optimizes the signal level for detection in varying channel conditions while maintaining system simplicity through adaptive rather than fixed complexity.
Data Source
AI summary
Disclosed is an apparatus and a method for detecting a boundary of a frame in a wireless communication system. The apparatus includes: a controller for measuring correlation energy with preambles with respect to received signals transmitted from a transmitter, measuring strength of the received signals, and removing a sample from frames constituting the received signals, the preambles predetermined and used by the system, the sample having a ratio of the correlation energy with respect to the strength of the received signals, the ratio being smaller than a reference value; and a classifier for extracting a maximum value from the correlation energy received from the controller, and determining a boundary of a downlink of the frames constituting the received signals.