Access Point Phase Alignment Correction for Distributed MIMO Networks

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Solution Overview

Problem

Existing distributed multiple-input multiple-output (D-MIMO) systems face challenges in maintaining phase alignment across a large number of access points, leading to poor performance for user equipment (UEs) located between different access point groups.

Innovation Solution

The solution involves allowing access points to belong to multiple access point groups, with each access point maintaining multiple phase alignment correction factors (PACFs). Depending on the user equipment (UE) being served, the appropriate PACF is selected for downlink beamforming, ensuring phase alignment across different access point groups.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If access points are divided into separate groups for phase alignment, then phase alignment can be maintained within each group, but user equipment located between different access point groups experiences poor performance due to phase misalignment

Engineering Contradiction:

Improvephase alignment reliabilityVSAvoidcoverage area adaptability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Each access point is configured to maintain multiple PACFs corresponding to different access point groups, enabling it to serve multiple functions. When a UE is served by a subset of access points from a particular group, the appropriate PACF for that group is selected and applied, allowing the same access point to adaptively serve UEs in different spatial locations with appropriate phase alignment for each group configuration

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of operation

If a single PACF is used for all access points, then the system is simple to operate, but phase alignment cannot be maintained across large networks with many access points

Engineering Contradiction:

Improvesystem operation simplicityVSAvoidphase alignment accuracy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The network is segmented into multiple access point groups, with each group having its own PACF. This segmentation allows the system to maintain phase alignment accuracy within each group while scaling to larger networks. The segmentation is transparent to operation simplicity because the network node automatically selects the appropriate PACF based on which access points are serving the UE

Inventive Principle:

Principle #1Segmentation

3Reliability

If access points use multiple PACFs for different groups, then phase alignment is maintained for UEs in different locations, but the device complexity increases

Engineering Contradiction:

Improvephase coherence across groupsVSAvoidaccess point configuration complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The network node automatically determines which access points are serving each UE and selects the appropriate PACF based on this information. This self-service mechanism eliminates the need for manual configuration of multiple PACFs at each access point, reducing operational complexity while maintaining the ability to apply group-specific phase alignment corrections

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20250047326A1Transmitting a signal

Publication Date: 2025.02.06 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Methods and apparatus are provided. In an example aspect, a method in a first access point of transmitting a signal is provided. The method includes, for each of a plurality of User Equipments (UEs), determining a phase alignment correction factor (PACF) for the UE based on an access point group associated with the UE, and transmitting a respective first signal to the UE, wherein the first signal is phase adjusted using the PACF determined for the UE.