Delay-Doppler Guard Interval for Inter-Carrier Interference Suppression
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Solution Overview
Problem
Wireless communication systems face challenges in high mobility scenarios due to Doppler effects, which cause inter-carrier interference (ICI) and degrade performance, especially for devices like those on high-speed trains, where frequency shifts and spreads lead to signal attenuation and interference.
Innovation Solution
The implementation of a guard interval in the delay-Doppler domain using orthogonal time frequency space (OTFS) precoding, where the guard interval is arranged at the head or tail of the delay domain, helps in tracking channel variations and suppressing inter-symbol interference, allowing for enhanced channel tracking and improved signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OFDM processing is used in high mobility scenarios, then the system can maintain basic communication functionality, but Doppler effects cause inter-carrier interference and signal attenuation that degrade communication reliability
Solution Approach 1:
The patent transforms the communication signal from the conventional time-frequency domain to the delay-Doppler domain, changing the fundamental representation parameters of the signal. This parameter transformation allows the system to inherently compensate for Doppler effects by processing the signal in a domain where frequency shifts are represented as discrete delays, thereby eliminating inter-carrier interference and improving communication reliability in high mobility scenarios
Solution Approach 2:
The patent introduces a new processing dimension by implementing OTFS precoding that operates in the delay-Doppler domain rather than the traditional time-frequency domain. This dimensional change enables the system to handle Doppler spread and delay spread simultaneously, transforming the harmful Doppler effects into manageable delay components that can be easily equalized, thus resolving the inter-carrier interference problem
2Reliability
If guard interval is added in time domain to mitigate interference, then inter-symbol interference is reduced, but transmission time increases and spectral efficiency decreases
Solution Approach 1:
Instead of adding guard interval in the time domain (which directly increases transmission time), the patent places the guard interval in the delay-Doppler domain. This dimensional shift allows the guard interval to function as a buffer against interference while occupying minimal time resources, as it is processed during the OTFS precoding operation rather than being appended to the time-domain signal, thus suppressing inter-symbol interference without significant time penalty
Data Source
AI summary
Certain aspects of the present disclosure provide techniques for using a guard interval in a delay-Doppler domain. A method of wireless communication includes converting information in a delay-Doppler domain to a time-frequency domain, wherein the information includes data and at least one guard interval (GI); mapping the converted information to time and frequency resources of an orthogonal frequency domain multiplexing (OFDM) resource grid in the time-frequency domain; generating a time-domain waveform based on the OFDM resource grid, wherein the time-domain waveform includes one or more GIs; and outputting the time-domain waveform for transmission to a node.