Time Reversal Signal Focusing Quality Estimation
Solution Overview
Problem
In radio communication systems using time reversal techniques for signal pre-equalization, the estimation of the propagation channel can become erroneous due to relative movement between communicating entities, leading to signal de-focusing and degradation of the quality of service, especially when there is latency between channel measurement and signal transmission.
Innovation Solution
A method to estimate the focusing quality of a pre-equalized signal by evaluating the spatio-temporal properties of the time reversal technique, including the use of power curve representation, relative movement estimation, temporal and power symmetry analysis, and auto-correlation of the propagation channel, allowing for precise evaluation of focusing quality without requiring direct measurement of received signal power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If time reversal pre-equalization is applied to cancel propagation channel effects, then signal focusing quality is improved, but relative movement between communicating entities causes decorrelation between channel estimate and actual channel, leading to de-focusing and reduced received power
Solution Approach 1:
The patent applies preliminary action by performing time reversal pre-equalization based on channel estimates obtained before signal transmission. The system pre-processes the signal using estimated channel characteristics to compensate for expected propagation effects, thereby improving signal focusing quality at the receiver before actual transmission occurs
Solution Approach 2:
The patent addresses dynamics by introducing adaptive mechanisms that account for relative movement between communicating entities. The system dynamically adjusts to changes in propagation conditions by updating channel estimates and re-calculating pre-equalization coefficients to maintain focusing quality despite mobility-induced decorrelation
2Device complexity
If channel estimation is performed at a given instant for signal pre-distortion, then processing complexity is reduced, but latency delay between measurement and transmission causes the focal point to shift, degrading service quality
Solution Approach 1:
The system performs channel estimation and pre-equalization coefficient calculation in advance before signal transmission. By obtaining channel characteristics at the transmitter before transmission occurs, the system prepares the pre-distorted signal ahead of time, reducing processing complexity at transmission while maintaining service quality through anticipatory channel compensation
Solution Approach 2:
The patent implements beforehand cushioning by compensating for expected latency effects through predictive channel estimation. The system anticipates the focal point shift caused by latency delay and pre-adjusts the pre-equalization coefficients to compensate for this expected degradation, thereby cushioning against service quality deterioration
3Adaptability or versatility
If the destination antenna position changes relative to the focal point due to movement during latency period, then adaptability to mobile scenarios is improved, but the focusing quality deteriorates because the antenna is no longer at the optimal convergence point
Solution Approach 1:
The patent implements dynamics by making the pre-equalization system adaptive to mobile scenarios. The system continuously updates channel estimates and recalculates pre-equalization coefficients based on current relative positions of communicating entities, enabling the system to adapt to movement while maintaining optimal focusing quality at the destination antenna
Solution Approach 2:
The system employs feedback mechanisms where channel estimates obtained at the destination are fed back to the transmitter for updating pre-equalization coefficients. This feedback loop enables the system to adapt to changing positions and maintain focusing quality by continuously adjusting the pre-processing based on actual channel conditions
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 enables a simple and fast evaluation of focusing quality, improving the accuracy of signal focusing and maintaining service quality even with relative motion between communicating entities, by considering the carrier frequency and latency effects.
Implementation Method 1
Time reversal is a technique for focusing waves, typically acoustic waves, which is based on the invariance by time reversal of the wave equation. The time reversal of the propagation channel applied to the signal makes it possible to cancel the effect of this channel during the transmission of the signal thus pre-distorted from the point of origin, and to focus the signal on a destination antenna.
Data Source
Figure 1~3
Figure 4~8
AI summary
Method of estimating the quality of focusing of a signal pre-equalized by time reversal of an estimated propagation channel between an original antenna (A1) of an original communicating entity (EC1) and a destination antenna (A2) of a destination communicating entity (EC2), the method comprising a step of evaluating a quality of focusing (Qv , Qβessel, Qv, Qsym, Qsymp, QDS, QEQ) of the signal received on the destination antenna, with respect to a value, for a focal point (FO), of a representation (QUAL1, QUAL2) of a curve of power received as a function of a distance (L) between the destination antenna and the focal point.