OTFS Modulation Time-Frequency Spreading for High-Mobility Wireless
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Solution Overview
Problem
Current 4G wireless networks face challenges in supporting increasing data usage, particularly in dense urban areas, and fail to provide the necessary quality of service for emerging applications like immersive reality and remote robotic operations, due to limitations in data capacity and mobility, especially at high speeds.
Innovation Solution
The method involves encoding information symbols into a two-dimensional array of modulation symbols and transmitting them using mutually orthogonal waveforms across multiple frequency sub-bands, employing techniques like OFDM and OTFS modulation to achieve efficient time-frequency spreading and channel equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM modulation is used to increase data capacity, then data transmission rate is improved, but channel coherence time decreases
Solution Approach 1:
The patent transitions from traditional one-dimensional frequency-domain OFDM modulation to two-dimensional time-frequency domain OTFS modulation. By spreading information symbols across both time and frequency dimensions using orthogonal waveforms, the system achieves improved channel coherence time while maintaining high data transmission rates through the combined time-frequency diversity.
2Productivity
If more antennas are added to increase throughput, then data capacity is improved, but device complexity increases
Solution Approach 1:
The patent segments the transmission resource into multiple orthogonal waveforms in the time-frequency domain, allowing information symbols to be distributed across these waveforms. This segmentation approach enables linear scaling of throughput with the number of antennas while keeping each antenna's processing relatively simple, as the orthogonal waveforms naturally separate the signal components.
3Duration of action of moving object
If time-frequency spreading is applied to increase channel coherence time, then signal stability is improved, but signaling complexity increases
Solution Approach 1:
The patent changes the modulation parameters by using orthogonal waveforms with specific time-frequency spreading characteristics. By carefully selecting the waveform parameters and spreading factors, the system achieves extended channel coherence time while controlling signaling complexity through the structured orthogonal nature of the waveforms, which simplifies both transmission and reception processing.
Data Source
AI summary
A system and method for orthogonal time frequency space communication and waveform generation compatible with OFDM. The method includes receiving a plurality of information symbols and encoding an N×M array containing the plurality of information symbols into a two-dimensional array of modulation symbols by spreading each of the plurality of information symbols with respect to both time and frequency. The two-dimensional array of modulation symbols is then transmitted along with one or more OFDM symbols using a plurality of narrowband subcarriers.