TDD Repeater Switching Timing via Cyclic Prefix Correlation

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Solution Overview

Problem

Conventional communication repeater devices face challenges in accurately estimating the switching timing between uplink and downlink signals in time division duplexing (TDD) systems due to differences in signal level characteristics, requiring expensive demodulation integrated circuits and being inefficient in handling signal rising characteristics.

Innovation Solution

A communication repeater device with a controller and storage that detects switching timing based on the similarity between certain sections of the original and time-shifted radio frames, using orthogonal frequency division multiplexing symbols and cyclic prefixes, and estimates subsequent switching timing from pre-defined frame information, eliminating the need for demodulation ICs and improving accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the repeater detects the waveform of a downlink signal to detect switching timing, then the repeater can identify timing transitions, but accurate estimation of switching timing becomes difficult due to differences in signal level characteristics among different radios

Engineering Contradiction:

Improveswitching timing detection accuracyVSAvoidsignal level characteristic variation

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent uses cyclic prefixes which are copies of previous signal portions to detect switching timing. The correlation processing compares the received signal with a copy of the cyclic prefix to accurately identify timing transitions without being affected by signal level variations.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent changes the detection parameter from absolute signal level to correlation value between signal portions. This parameter transformation makes the detection robust against signal level characteristic variations while maintaining accurate switching timing detection.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If the repeater uses conventional waveform detection methods, then the implementation is simple, but expensive demodulation integrated circuits are still required and accuracy is compromised

Engineering Contradiction:

Improvedetection method simplicityVSAvoidswitching timing estimation accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The method uses cyclic prefix copying and correlation processing instead of complex demodulation. By comparing the received signal with a copy of the cyclic prefix, the system achieves accurate timing detection with simpler processing that eliminates the need for expensive demodulation ICs.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces complex mechanical/demodulation-based timing detection with a correlation-based signal processing approach. This substitution maintains simplicity while significantly improving accuracy and eliminating hardware requirements for demodulation ICs.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If the repeater detects signal level threshold crossings, then the detection process is straightforward, but accurate switching timing estimation is difficult due to signal rising characteristics

Engineering Contradiction:

Improvedetection process simplicityVSAvoidswitching timing estimation accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

Instead of detecting absolute signal level crossings, the method correlates the received signal with a copy of the cyclic prefix. This copying approach transforms the detection process into a correlation operation that is both simple to implement and highly accurate in determining switching timing.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The cyclic prefix correlation acts as an intermediary between the received signal and the switching timing determination. This intermediary process filters out signal level variations and directly provides accurate timing information while maintaining operational simplicity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10735083B2Communication repeater device, control method, and computer program product

Publication Date: 2020.08.04 KK TOSHIBA

AI summary

According to an embodiment, a communication repeater device includes storage and a controller which detects, upon receiving a radio frame including pairs of orthogonal frequency division multiplexing symbols and cyclic prefixes from the radio base station, switching timing between uplink and downlink according to similarity between certain sections of an original radio frame and a time-shifted radio frame. The controller estimates the subsequent switching timing between the uplink and the downlink from the detected switching timing and frame information stored in the storage.