Time-Reversal Wireless Communication Spatial Focusing
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Solution Overview
Problem
Current broadband communication systems face challenges in high-speed wireless communications due to severe inter-symbol interference (ISI) in rich scattering environments, which requires complex multi-carrier modulation and equalization, increasing complexity and power consumption.
Innovation Solution
The implementation of time-reversal division multiple access (TRDMA) in wireless communication systems, which leverages multi-path propagation for spatial focusing, reducing complexity and power consumption by using time-reversed signals to concentrate energy at intended locations, and exploiting unique multi-path profiles for each communication link.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-carrier modulation and equalization are used to resolve inter-symbol interference in rich scattering environments, then communication reliability is improved, but device complexity and power consumption increase prohibitively
Solution Approach 1:
The patent applies time-reversal inversion to the transmitted signal. By inverting the channel impulse response and transmitting the time-reversed signal, the multi-path effects are reversed to produce constructive interference at the intended receiver location, automatically canceling out inter-symbol interference without requiring complex equalization algorithms
Solution Approach 2:
The patent converts the harmful multi-path propagation effect into a beneficial focusing mechanism. The same multi-path reflections that cause inter-symbol interference are exploited through time-reversal to concentrate signal energy at the target location, transforming the adverse effect into a spatial focusing advantage
2Reliability
If multi-carrier modulation is used to alleviate inter-symbol interference, then communication quality is improved, but power consumption increases prohibitively
Solution Approach 1:
The patent converts the harmful multi-path propagation into a beneficial energy-focusing mechanism. Time-reversal processing causes the signal energy to be concentrated at the intended receiver through constructive interference of multi-path components, improving signal quality while reducing the need for high transmit power and complex receiver processing
Solution Approach 2:
The channel itself serves as the processing mechanism. The time-reversed signal automatically exploits the channel's impulse response to achieve spatial focusing and interference cancellation, eliminating the need for separate equalization stages and reducing overall system power consumption
3Reliability
If complicated equalization is applied at the receiver to resolve inter-symbol interference, then communication reliability is improved, but device complexity increases prohibitively
Solution Approach 1:
The patent moves the processing complexity from the receiver to the transmitter by applying time-reversal inversion at the transmitting end. This inversion pre-compensates for channel effects, allowing the receiver to simply correlate with the known time-reversed signal without requiring complex equalization algorithms
Solution Approach 2:
The channel compensation action is performed preliminarily at the transmitter through time-reversal processing. By pre-processing the signal with the time-reversed channel impulse response before transmission, the receiver only needs to perform simple correlation detection, eliminating the need for complicated equalization
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
TRDMA achieves high-resolution spatial focusing and energy efficiency by simplifying receivers, reducing interference, and maintaining quality of service (QoS) without the need for complex equalization, while improving spectral efficiency and bit-error ratio (BER) performance.
Implementation Method 1
the energy of the TR acoustic waves from transmitters could be refocused primarily at the intended location with very high spatial resolution (several-wavelength level)
Implementation Method 2
By utilizing channel reciprocity, the TR waves can retrace the incoming paths, ending up with a 'spiky' signal-power spatial distribution focused primarily at the intended location
Data Source
AI summary
There is provided a communication system including a transmitting section and a receiving section which includes a plurality of receivers. The transmitting section includes a communication unit which receives a plurality of signals respectively from the plurality of receivers, and stores a plurality of time-reversed signals corresponding to the received plurality of signals with respect to the plurality of receivers, and a first conversion unit which converts, by a first factor, a plurality of information sequences to be respectively transmitted to the plurality of receivers and forward the plurality of converted information sequences to the communication unit. The communication unit generates, based on the plurality of converted information sequences, a plurality of output signals to be respectively transmitted to the plurality of receivers, each of the plurality of the output signals including a location-specific signature unique to the corresponding receiver.