Hybrid Precoding for Multi-User MIMO Interference Management

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current multi-user MIMO systems face challenges in efficiently eliminating interference while managing complexity and error processing performance, particularly with methods like block diagonalization and Tomlinson-Harashima precoder, which incur channel capacity loss and increased complexity as the number of users increases.

Innovation Solution

A precoding method combining vector perturbation (VP) and block Tomlinson-Harashima precoder (BTHP) is employed, where VP is used to eliminate interference between sub-channels and BTHP is used to handle inter-user interference, shifting complexity from user terminals to the base station and optimizing error processing performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If block diagonalization method is used to eliminate inter-user interference, then error processing performance is improved, but channel capacity loss increases when the number of users increases

Engineering Contradiction:

Improveerror processing performanceVSAvoidchannel capacity loss

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent combines block diagonalization (BD) and Tomlinson-Harashima precoding (THP) methods into a hybrid precoding scheme. The BD component handles inter-user interference by diagonalizing the channel matrix, while the THP component compensates for channel inversion effects. This merging allows the system to achieve both interference elimination and channel capacity preservation, resolving the contradiction between error processing performance and channel capacity loss.

Inventive Principle:

Principle #5Merging (Combining)

2Loss of information

If Tomlinson-Harashima precoder (THP) is used to reduce channel capacity loss, then channel capacity is preserved, but system complexity increases and error processing performance deteriorates when the number of users is small

Engineering Contradiction:

Improvechannel capacity lossVSAvoidsystem complexity

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The patent segments the precoding function into two distinct components: block diagonalization for interference management and Tomlinson-Harashima precoding for channel capacity preservation. By dividing the overall precoding task into separate functional blocks, the system can selectively apply each method where it is most effective, reducing overall complexity compared to applying a single complex method across all users.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The hybrid precoding scheme applies THP selectively rather than universally. The BD component handles the majority of users through simple diagonalization, while THP is applied only where needed to compensate for channel inversion effects. This partial application of the more complex THP method reduces overall system complexity while still preserving channel capacity where necessary.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If maximum likelihood (ML) receiving method is applied to BTHP, then error processing performance is improved, but user terminal complexity increases significantly

Engineering Contradiction:

Improveerror processing performanceVSAvoiduser terminal complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a hybrid precoding structure that acts as an intermediary between the transmitter and receiver, preprocessing the signal to eliminate interference before transmission. This intermediary processing at the transmitter side (through BD and THP) simplifies the receiver's task, allowing user terminals to use simpler detection algorithms instead of complex ML receivers, thus reducing terminal complexity while maintaining error processing performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Object-generated harmful factors

If vector perturbation (VP) method is used to eliminate interference, then interference cancellation is achieved, but complexity increases steeply as the number of antennas increases

Engineering Contradiction:

Improveinterference cancellationVSAvoidsystem complexity

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces the computationally expensive VP method with a hybrid BD-THP approach that uses simpler, more efficient algorithms. The BD component uses straightforward matrix diagonalization, and the THP component uses structured precoding with reduced computational requirements. This substitution achieves comparable interference cancellation performance without the steep complexity increase associated with VP methods as antenna numbers grow.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS8625688B2Precoding method and device

Publication Date: 2014.01.07 SAMSUNG ELECTRONICS CO LTD

AI summary

A method for a transmitting terminal in a multi-user multi-antenna environment to perform precoding includes: receiving feedback information from a plurality of receiving terminals; estimating a channel between the transmitting terminal and the plurality of receiving terminals by using the feedback information; and generating a plurality of transmission symbols by applying a first nonlinear precoding method and a second nonlinear precoding method to a plurality of symbols and the estimated channel to be transmitted to the plurality of receiving terminals. The first nonlinear precoding method is used to eliminate interference between subchannels of the same receiving terminal, and the second nonlinear precoding method is used to eliminate interference between the receiving terminals.