Synchronized MU-MIMO Candidate Selection in Massive MIMO

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Solution Overview

Problem

Conventional MU-MIMO solutions split SRS capacity between downlink and uplink, leading to reduced sizes of MU-MIMO candidate UE lists, which is not desirable.

Innovation Solution

Implement synchronized selection of mMIMO/MU-MIMO candidate UEs for both downlink and uplink, using a common pool of UEs and selection criteria to maximize SRS capacity utilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If SRS capacity is dimensioned for both DL and UL MU-MIMO solutions separately, then both DL and UL can support MU-MIMO operations, but the SRS capacity is split between DL and UL candidate UE lists, leading to reduced list sizes

Engineering Contradiction:
ImproveMU-MIMO operation supportVSAvoidMU-MIMO candidate UE list size
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent merges the DL and UL MU-MIMO candidate UE selection processes into a unified synchronized selection mechanism. A common pool of candidate UEs is maintained for both DL and UL MU-MIMO operations, eliminating the separate candidate lists that previously divided SRS capacity. The selection criteria and SRS resource allocation are coordinated across both directions, allowing full utilization of SRS capacity for supporting both DL and UL MU-MIMO without reducing candidate list sizes.

Inventive Principle:
Principle #5Merging (Combining)

2Quantity of substance

If SRS capacity is increased to support both DL and UL MU-MIMO, then more candidate UEs can be supported, but SRS periodicity limitation prevents capacity increase

Engineering Contradiction:
ImproveSRS capacityVSAvoidSRS periodicity
Core Design Contradiction:
Quantity of substanceVSProductivity

Solution Approach 1:

The patent implements dynamic SRS resource allocation where the same SRS resources are reused alternately for DL and UL MU-MIMO operations based on scheduling needs. The system dynamically switches between DL and UL MU-MIMO candidate selections using the same SRS capacity, effectively doubling the operational capacity without increasing physical SRS resources or changing periodicity. This dynamic time-division approach allows full utilization of limited SRS capacity for both directions.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If parallel DL and UL candidate UE selections are implemented, then both directions can independently optimize their candidate lists, but the already limited SRS capacity is divided, reducing efficiency

Engineering Contradiction:
ImproveIndependent optimizationVSAvoidSRS capacity utilization efficiency
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The patent creates a universal candidate UE pool that serves both DL and UL MU-MIMO operations simultaneously. The same set of candidate UEs is evaluated for both downlink and uplink MU-MIMO suitability using coordinated selection criteria. This multi-functional approach allows the candidate list to be optimized for both directions without requiring separate lists, thereby maximizing SRS capacity utilization efficiency while maintaining independent optimization capabilities for each transmission direction.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4117193B1Synchronized downlink and uplink multi-user MIMO candidate selection in massive-MIMO system
Publication Date: 2025.06.11 MAVENIR NETWORKS INC
  • EP4117193B1 patent drawingFigure 1
  • EP4117193B1 patent drawingFigure 2
  • EP4117193B1 patent drawingFigure 3

AI summary

A method for synchronized selection of user equipments (UEs) for both downlink (DL) Multi-User Multiple Input Multiple Output (MU-MIMO) operation and uplink (UL) MU-MIMO operation includes: applying a common set of selection criteria for selecting a common pool of UE candidates for both DL and UL MU-MIMO operations, wherein the common set of selection criteria are applied in Stage-1 selection process to select Stage-1 candidates for a UE candidates list; and if the Stage-1 selection process applying the common set of selection criteria is not able to find UE candidates to fill available slots in the UE candidates list, initiating Stage-2 selection process involving 1) applying a first set of Stage-2 selection criteria to select DL-only traffic UEs as Stage-2 candidates for the UE candidates list, and 2) applying a second set of Stage-2 selection criteria to select UL-only traffic UEs as Stage-2 candidates for the UE candidates list.