M-MIMO Spatial Null Creation for Interference Management

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Solution Overview

Problem

Massive Multiple Input Multiple Output (M-MIMO) communication systems face interference issues between base stations due to shared time and frequency resources, leading to reduced system capacity and unsuitable solutions like Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) that compromise throughput.

Innovation Solution

Employing a large M-MIMO antenna array to create precise spatial nulls in select directions or areas, allowing simultaneous operation without TDMA, FDMA, or power control schemes, by using a processor to generate transmit and receive precoder matrices that control the M-MIMO antenna array to minimize interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If base stations share time and frequency resources simultaneously, then system capacity and throughput are improved, but interference between base stations increases

Engineering Contradiction:

Improvesystem capacityVSAvoidinterference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating spatially selective nulls in specific directions rather than uniformly reducing transmission in all directions. The M-MIMO antenna array generates precoder matrices that direct nulls toward interfering base stations while maintaining full transmission strength toward intended users, achieving localized interference suppression without sacrificing overall system capacity

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the harmful interference into a beneficial spatial filtering opportunity. By identifying the directions of interfering base stations, the system uses precoding to create nulls that actively suppress interference in those specific spatial directions, transforming the interference problem into an opportunity for spatial multiplexing and capacity enhancement

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If TDMA or FDMA schemes are used to reduce interference, then interference between base stations is reduced, but system throughput and capacity are compromised

Engineering Contradiction:

ImproveinterferenceVSAvoidthroughput

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent transitions from traditional time-frequency resource division (1D/2D) to spatial dimension-based interference management (3D). By utilizing the spatial domain through M-MIMO antenna arrays and precoder matrices, the system creates nulls in specific spatial directions, adding a third dimension for resource management that allows simultaneous operation without TDMA/FDMA while maintaining high throughput

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Object-affected harmful factors

If M-MIMO antenna arrays are used to create spatial nulls, then interference is reduced, but device complexity increases

Engineering Contradiction:

ImproveinterferenceVSAvoidantenna array complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent manages complexity by dynamically adjusting precoder matrix parameters based on channel state information and interference conditions. The system changes parameters such as null direction angles, null depths, and precoding weights adaptively, allowing the M-MIMO array to achieve interference suppression with optimized complexity rather than requiring maximum processing power at all times

Inventive Principle:

Principle #35Parameter changes

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

Enables full simultaneous operation of base stations with minimal or no interference, maintaining system capacity and supporting high throughput in cellular networks by shaping transmit and receive beam patterns to reduce power in interfering areas.

Implementation Method 1

shaping transmit and receive beam patterns to reduce power in interfering areas

Methodology Applied

Scientific EffectBeamforming:

Implementation Method 2

create precise spatial nulls in select directions or areas

Methodology Applied

Scientific EffectSpatial null creation:

Data Source

PatentUS9749026B2Spatial null creation using massive MIMO (M-MIMO)

Publication Date: 2017.08.29 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

In a base station having a Massive Multiple Input Multiple Output (M-MIMO) antenna array, the availability of the M-MIMO antenna array is exploited to manage the interference caused by the base station to neighboring cells. In one embodiment, the large number of antenna elements of the M-MIMO antenna array are used to create precise transmit and/or receive spatial nulls at specific User Equipments (UEs) being served by a neighboring cell and/or in select areas of the neighboring cell. Depending on whether the spatial null is partial or full, transmissions by the base station may have reduced or even zero receive power within the neighboring cell.