MU-MIMO Nonlinear Precoding Signaling for Interference Suppression
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Solution Overview
Problem
In wireless communication systems, existing MU-MIMO technologies face limitations in suppressing inter-user interference due to low orthogonality of channels, especially when using linear precoding, which restricts frequency use efficiency and requires complex demodulation processes in terminal apparatuses for nonlinear precoding.
Innovation Solution
A base station apparatus notifies terminal apparatuses of nonlinear precoding setting information through the radio resource control layer, allowing terminals to blindly estimate whether signals are linear or nonlinear precoded and perform appropriate demodulation processes, thereby enabling efficient signaling and power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If linear precoding is used in MU-MIMO, then device complexity is reduced, but transmission efficiency deteriorates due to inability to efficiently suppress inter-user interference when channel orthogonality is low
Solution Approach 1:
The patent changes the precoding parameter from linear to nonlinear (specifically Tomlinson-Harashima Precoding or Vector Perturbation Precoding), which fundamentally alters the interference suppression capability. This parameter change enables efficient IUI suppression even when channel orthogonality is low, thereby improving transmission efficiency without requiring increased terminal complexity since the complex processing is performed at the base station side.
2Productivity
If nonlinear precoding is used in MU-MIMO, then transmission efficiency is improved, but device complexity increases due to modulo calculation and perturbation vector processing
Solution Approach 1:
The patent inverts the conventional architecture by performing the complex nonlinear precoding processing at the base station (transmission side) rather than at the terminal (reception side). This inversion allows the terminal to simply receive and demodulate signals without implementing complex modulo calculations or perturbation vector processing, thereby achieving high transmission efficiency while keeping terminal complexity low. The base station handles the computational burden through its greater processing capabilities.
3Productivity
If channel orthogonality is low in MU-MIMO, then frequency use efficiency is improved by spatial multiplexing more users, but inter-user interference suppression deteriorates
Solution Approach 1:
The patent applies nonlinear precoding (THP or VP precoding) which fundamentally changes the interference management parameter. Unlike linear precoding that relies on high channel orthogonality, nonlinear precoding actively suppresses interference through modulo operations and perturbation vectors, enabling efficient spatial multiplexing of multiple users even when channel orthogonality is low, thereby maintaining high frequency use efficiency while controlling inter-user interference.
Data Source
AI summary
A terminal apparatus can be notified whether an MU-MIMO signal transmitted from a base station apparatus is linear-precoded or nonlinear-precoded by using effective signaling. According to the present invention, the base station apparatus decides whether the nonlinear precoding is used in an own cell, includes the decided nonlinear precoding setting information in system information or a layer 3 message, and notifies the terminal apparatus of the decided nonlinear precoding setting information by using a physical broadcast channel, a physical downlink share channel, or the like. The terminal apparatus performs a demodulation process for user data destined for the own terminal apparatus based on the nonlinear precoding setting information acquired from the notified system information or layer 3 message.