OTFS Multi-User Multiplexing on Delay-Doppler Resource Grids
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Solution Overview
Problem
Current wireless communication networks face bandwidth limitations due to the rapid growth in wireless data traffic, necessitating efficient methods for multiplexing signals from multiple user devices in SISO and MIMO systems to maintain high-quality service.
Innovation Solution
The implementation of orthogonal time frequency space (OTFS) transformation for multiplexing signals in both uplink and downlink directions using a multi-dimensional grid of resources, allowing for logical partitioning and allocation of transmission resources, and performing joint equalization and forward error correction to improve signal decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple user devices transmit simultaneously using conventional methods, then network throughput increases, but bandwidth limitations and interference increase
Solution Approach 1:
The patent transforms the conventional two-dimensional time-frequency resource grid into a four-dimensional delay-Doppler grid by applying OTFS modulation. This dimensional expansion allows multiple user devices to be multiplexed along delay and Doppler dimensions in addition to time and frequency, effectively increasing the available resource dimensions for simultaneous transmissions without requiring additional bandwidth.
Solution Approach 2:
The patent divides the delay-Doppler resource grid into multiple segments and assigns different segments to different user devices. This segmentation allows simultaneous transmissions from multiple devices to be separated and decoded independently, enabling increased network throughput while managing bandwidth resources efficiently through structured resource allocation.
2Productivity
If conventional multiplexing methods are used for multiple users, then resource utilization improves, but reception performance degrades due to interference
Solution Approach 1:
The patent introduces a joint equalization process as an intermediary step between signal reception and decoding. This joint equalization operates in the delay-Doppler domain to separate and compensate for signals from multiple user devices simultaneously, effectively managing multi-user interference while maintaining high resource utilization and improving reception performance.
3Device complexity
If traditional signal processing methods are used, then system complexity is low, but decoding accuracy decreases in multi-user scenarios
Solution Approach 1:
The patent replaces conventional time-frequency domain signal processing with OTFS modulation and joint equalization in the delay-Doppler domain. This substitution transforms the signal representation and processing approach, enabling accurate separation and decoding of multiple user signals while maintaining manageable system complexity through structured transformation and resource allocation.
Data Source
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AI summary
A method for performing downlink transmissions from a transmitting device to multiple user devices using transmission resources from a multi-dimensional grid of resources is described. The method includes logically partitioning the transmission resources into multiple segments, assigning, to a given user device of the multiple user devices, transmission resources of one or more of the multiple segments, and performing, using at least some of the assigned transmission resources for the given user device, a downlink transmission using an orthogonal time frequency space (OTFS) transformation on data or signals to be transmitted to the given user device.