Affine Fourier Waveform Multiplexing Under High Doppler
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Solution Overview
Problem
Existing 5G NR waveforms, such as OFDM and DFT-s-OFDM, suffer from poor link-level performance in high-mobility scenarios due to the channel becoming linear time-variant (LTV) under high Doppler frequency, leading to significant challenges in spectrum control and multiplexing different waveform types.
Innovation Solution
The implementation of a spectrum-controlled affine Fourier based waveform that allows for flexible subcarrier allocation and multiplexing of different waveforms within the same bandwidth, using subcarrier mapping and precoding techniques to address the challenges of Doppler frequency and multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OFDM or DFT-s-OFDM waveforms are used in high-mobility scenarios, then the system can support standard 5G NR deployments, but link-level performance deteriorates significantly due to Doppler frequency causing the channel to become linear time-variant
Solution Approach 1:
The patent transforms the time-domain signal to frequency-domain using Fourier transform, applies phase rotation to subcarriers based on Doppler compensation algorithms, then transforms back to time-domain. This parameter transformation approach compensates for Doppler effects by adjusting frequency-domain parameters (phase shifts) to counteract channel variations caused by high mobility
Solution Approach 2:
The patent introduces dynamic Doppler compensation mechanisms that adapt to changing channel conditions in real-time. The system continuously estimates Doppler frequency shifts and adjusts the waveform parameters dynamically, allowing the communication system to maintain performance under varying mobility conditions rather than being fixed to static waveform assumptions
2Productivity
If spectrum control is implemented for waveform multiplexing in high-Doppler environments, then resource utilization improves, but system complexity increases due to the need for specialized waveform processing and multiplexing coordination
Solution Approach 1:
The patent divides the available spectrum into distinct subcarriers and allocates different waveforms to different subcarrier groups. By segmenting the frequency spectrum and applying specialized Doppler-resistant waveforms to specific segments, the system achieves efficient resource utilization while managing complexity through modular processing of individual subcarrier groups rather than treating the entire spectrum uniformly
Solution Approach 2:
The patent designs a unified waveform processing framework that can handle both standard 5G NR waveforms and Doppler-compensated waveforms through the same Fourier transform-based architecture. This multi-functional approach allows the system to support multiple waveform types and multiplexing schemes without requiring completely separate processing chains, thereby improving resource utilization while controlling overall system complexity
Data Source
AI summary
In one embodiment, a method includes accessing symbol sequences with each including multiple symbols, generating a respective frequency-domain signal for each of the symbol sequences based on a respective signal transformation algorithm that is based at least in part on a Fourier transform, mapping each of the frequency-domain signals to a respective subset of subcarriers out of all subcarriers in an allocated bandwidth, generating a waveform based on the frequency-domain signals and their respective subset of subcarriers based at least in part on an inverse Fourier transform, and transmitting the waveform to a second electronic device.