Adaptive OTFS-OFDM Switching for Doppler-Aware Wireless Links
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Solution Overview
Problem
OTFS modulation increases power consumption due to high computation per bit symbol, which is not efficient when the Doppler effect is small, while OFDM modulation is more power-efficient but less effective in high velocity environments.
Innovation Solution
A transmission and receiving station that can dynamically switch between OTFS and OFDM modulation based on the influence of the Doppler effect, using velocity and Doppler frequency estimation to optimize modulation methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OTFS modulation is applied to mitigate Doppler effect, then communication reliability in high velocity environments is improved, but power consumption increases due to high computation per bit symbol
Solution Approach 1:
The patent implements dynamic switching between OTFS and OFDM modulation schemes based on real-time Doppler effect conditions. The base station determines the Doppler shift magnitude and selects the appropriate modulation mode, allowing the system to adapt its computational complexity and power consumption to the actual channel conditions rather than always using the more complex OTFS modulation.
Solution Approach 2:
The patent changes the modulation parameter (switching between OTFS and OFDM) based on the Doppler shift parameter. When the Doppler shift exceeds a threshold, OTFS modulation is activated; otherwise, the more power-efficient OFDM modulation is used. This parameter-based switching resolves the contradiction by only applying the computationally intensive OTFS modulation when necessary.
2Use of energy by moving object
If OFDM modulation is used instead of OTFS modulation, then power consumption is reduced and communication capacity is improved, but effectiveness in high velocity environments deteriorates due to significant Doppler effect
Solution Approach 1:
The system dynamically adjusts the modulation scheme based on the relative velocity between transmitter and receiver. By continuously monitoring Doppler shift conditions and switching between OFDM and OTFS, the system maintains communication effectiveness in high velocity environments while minimizing power consumption during normal conditions.
Solution Approach 2:
The patent uses the Doppler shift magnitude as a decision parameter to switch between modulation schemes. When velocity-induced Doppler effects are significant, the system transitions to OTFS modulation which is specifically designed to handle such conditions, thereby maintaining communication reliability without unnecessarily consuming extra power during low-velocity operation.
3Reliability
If OTFS modulation is applied, then frequency diversity effect and time diversity effect are improved, but computation complexity increases by the cube compared to OFDM modulation
Solution Approach 1:
The patent implements dynamic selection of modulation schemes based on channel conditions. The base station evaluates the Doppler shift and relative velocity to determine whether the computational complexity of OTFS is justified by the diversity benefits. This dynamic approach ensures that high-complexity OTFS modulation is only applied when the diversity effects are actually needed to maintain communication reliability.
Solution Approach 2:
The system changes the modulation parameter based on the Doppler shift threshold. When the Doppler effect is significant, OTFS modulation with its superior frequency and time diversity is activated; otherwise, the simpler OFDM modulation is used. This parameter-based switching resolves the contradiction between diversity effect and computation complexity.
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
Reduces power consumption and maintains high communication capacity by switching to OFDM in low Doppler environments and OTFS in high Doppler environments, balancing efficiency and performance.
Implementation Method 1
There is a phenomenon in which, when there is a relative velocity between a transmission station and a receiving station, radio waves are received at a frequency different from the actual frequency of the radio waves. This phenomenon is commonly called the Doppler effect.
Data Source
AI summary
A transmission station that performs wireless communication with a receiving station at a predetermined carrier frequency performs orthogonal frequency division multiplexing on a symbol sequence, performs orthogonal time frequency space multiplexing on a symbol sequence, performs switching between orthogonal frequency division multiplexing and orthogonal time frequency space multiplexing to input a symbol sequence obtained by mapping a bitstream to only one of them, obtains a relative velocity between the transmission station and a receiving station, controls the switching based on a velocity; and transmits a switching notification that is a control signal to the receiving station, when the switching is controlled.