Adaptive Waveform Design for High-Mobility Wireless Systems
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Solution Overview
Problem
Wireless telecommunications systems face challenges in mitigating impairments such as infra-symbol and inter-symbol interference, as well as Doppler-shift effects, which affect signal quality and latency in radio communications.
Innovation Solution
The system employs modulated radio-frequency carrier signals with waveforms that differentiate between direct-path and multipath images, using temporally-longer and shorter waveforms to prevent infra-symbol interference and adapt to latency tolerance, enabling simultaneous multiple access in the same communications channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temporally-longer waveforms are used to prevent infra-symbol interference, then signal quality is improved, but latency increases
Solution Approach 1:
The system dynamically adapts waveform duration based on service requirements. Different waveform lengths are selected depending on whether the traffic is latency-sensitive (e.g., voice) or latency-tolerant (e.g., file transfer), allowing the system to optimize between signal quality and latency on a per-transmission basis
Solution Approach 2:
The system changes the temporal parameter of waveforms to match service requirements. Temporally-longer waveforms are used when signal quality is paramount, while temporally-shorter waveforms are used when latency is critical, with the parameter selection being adaptive to current network conditions and service type
2Productivity
If multiple transmitters transmit simultaneously in the same channel, then spectral efficiency is improved, but signal separation becomes more difficult
Solution Approach 1:
The system segments the shared channel into distinct signal spaces using orthogonal waveforms. Each transmitter is assigned a unique waveform signature that is mathematically orthogonal to others, effectively dividing the channel into non-interfering segments that can be simultaneously transmitted and easily separated at the receiver
Solution Approach 2:
Orthogonal waveforms act as intermediaries that facilitate simultaneous multiple access. These waveforms serve as unique identifiers and separation mechanisms, allowing the receiver to distinguish between different transmitters without requiring complex signal processing, thus enabling multiple users to share the channel efficiently
3Loss of time
If temporally-shorter waveforms are used for low latency tolerant data, then latency is reduced, but infra-symbol interference increases
Solution Approach 1:
The system adjusts the temporal parameter of waveforms based on service requirements. For latency-sensitive applications, shorter waveforms are selected to minimize transmission time, while for latency-tolerant applications, longer waveforms are used to provide better interference mitigation through their extended duration
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
This approach effectively reduces infra-symbol and inter-symbol interference, adapts to latency requirements, and allows multiple transmitters to transmit simultaneously, enhancing signal quality and spectral efficiency while managing latency in wireless communications.
Implementation Method 1
radio-frequency environment that comprises natural and man-made radio-frequency carrier signal-path impairments (e.g., objects, etc.) that reflect, refract, diffract, and absorb the modulated radio-frequency carrier signal
Implementation Method 2
radio-frequency environment that comprises natural and man-made radio-frequency carrier signal-path impairments (e.g., objects, etc.) that reflect, refract, diffract, and absorb the modulated radio-frequency carrier signal
Implementation Method 3
radio-frequency environment that comprises natural and man-made radio-frequency carrier signal-path impairments (e.g., objects, etc.) that reflect, refract, diffract, and absorb the modulated radio-frequency carrier signal
Implementation Method 4
radio-frequency environment that comprises natural and man-made radio-frequency carrier signal-path impairments (e.g., objects, etc.) that reflect, refract, diffract, and absorb the modulated radio-frequency carrier signal
Implementation Method 5
use a modulated radio-frequency carrier signal to convey data items wirelessly through a radio-frequency environment
Implementation Method 6
the radio receiver receives both direct-path and multipath images of the signal, which can cause infra-symbol and inter-symbol interference
Implementation Method 7
the illustrative embodiments are also particularly effective remediating the effects of Doppler-shift impairments in the radio channel
Data Source
AI summary
A wireless telecommunications system that mitigates infrasymbol interference due to Doppler-shift and multipath and enables multiple access in one radio channel. Embodiments of the present invention are particularly advantageous for wireless telecommunications systems that operate in high-mobility environments, including high-speed trains and airplanes.