OTFS Wireless Device Self-Interference Compensation
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Solution Overview
Problem
Existing wireless communication systems, particularly in high mobility environments like vehicle-to-vehicle (V2V) communication, face performance degradation due to Doppler spreads and mismatched time-frequency grids, leading to inefficiencies in orthogonal frequency-division multiplexing (OFDM) and other modulation schemes.
Innovation Solution
The implementation of a wireless communication device with a processing module that uses a minimum mean square equalizer to compensate for self-interference by dynamically adjusting the time-frequency grid and pulse matching based on channel conditions, allowing for improved equalization and reduced computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OFDM modulation is used in high mobility environments, then the system achieves good performance in static or low mobility scenarios, but performance degrades substantially due to Doppler spreads
Solution Approach 1:
The patent applies OTFS modulation which dynamically adapts to high mobility environments by spreading data symbols across the entire time-frequency grid using symplectic finite Fourier transform. This dynamic time-frequency spreading allows the system to maintain reliability in high Doppler spread conditions where static OFDM fails, while still functioning in lower mobility scenarios.
Solution Approach 2:
The patent changes the fundamental modulation parameters from OFDM's orthogonal subcarriers to OTFS's time-frequency spread symbols with tailored pulse shapes. By adjusting the pulse duration and bandwidth parameters in the time-frequency domain, the system adapts to varying channel conditions and mobility levels, transforming the modulation approach to handle Doppler effects effectively.
2Reliability
If perfect grid-matching is assumed for OTFS, then theoretical performance is maximized, but practical implementation complexity increases and computational feasibility decreases
Solution Approach 1:
The patent implements partial grid-matching where the time-frequency grid is approximately matched to channel characteristics rather than perfectly matched. This partial matching approach achieves sufficient performance improvement over non-matched grids while avoiding the excessive computational complexity of perfect matching, providing a practical compromise between performance and implementation feasibility.
Solution Approach 2:
The patent employs minimum mean square equalization that automatically adapts to the channel conditions without requiring complex iterative optimization. The equalizer self-adjusts its parameters based on the received signal statistics, reducing the need for complex training sequences and manual tuning, thereby lowering implementation complexity while maintaining good performance.
3Reliability
If sophisticated equalizers with accurate channel information are used, then reliability and robustness increase for high mobility users, but computational complexity and processing requirements increase
Solution Approach 1:
The patent extracts and compensates for self-interference terms separately in the equalization process. By identifying and removing the dominant self-interference components caused by time-frequency spreading, the equalizer can use simpler processing for the remaining signal, reducing overall complexity while maintaining robustness in high mobility scenarios.
Solution Approach 2:
The patent introduces an intermediate channel estimation step that provides sufficient accuracy for equalization without requiring full sophisticated channel knowledge. This intermediary estimation approach bridges the gap between simple and complex equalizers, providing adequate performance with reduced computational burden compared to full maximum likelihood equalization.
Data Source
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AI summary
Embodiments of the present disclosure relate to wireless communication devices, systems comprising wireless communication devices, and to an apparatus, a method and a computer program for a wireless communication device. The apparatus comprises a transceiver module for transmitting and receiving wireless transmissions. The apparatus comprises a processing module that is configured to control the transceiver module. The processing module is configured to communicate with a further wireless communication device via the transceiver module. The communication with the further wireless communication device is based on a transmission of data frames between the wireless communication device and the further wireless communication device. Each data frame is based on a two-dimensional grid in a time-frequency plane having a time dimension resolution and a frequency dimension resolution. The two-dimensional time-frequency grid is derived from a two-dimensional grid in a delay-Doppler plane having a delay dimension and a Doppler dimension. The processing module is configured to perform equalization on received data frames. The equalization is performed using a minimum mean square equalizer. The minimum mean square equalizer comprises a term to compensate for self-interference.