Iterative Downlink PIM Spatial Avoidance Algorithm

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing downlink passive intermodulation (PIM) spatial avoidance algorithms in wireless communication systems face challenges in non-stationary environments due to lack of adaptive null steering mechanisms, especially with frequency-dependent hardware impairments and antenna calibration errors, leading to inefficient PIM reduction.

Innovation Solution

Implementing an iterative downlink PIM spatial avoidance algorithm with a built-in blind subspace tracking feature, using feedback-assisted methods to estimate and correct downlink PIM subspaces, and applying recursive least squares algorithms to adaptively adjust null steering weights, thereby reducing PIM across multiple uplink channels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional downlink PIM spatial avoidance algorithms are used, then PIM reduction is achieved, but the system cannot adapt to non-stationary environments with frequency-dependent hardware impairments and antenna calibration errors

Engineering Contradiction:

Improveadaptability to non-stationary environmentsVSAvoidPIM reduction effectiveness

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements dynamic null steering weights that are continuously updated through iterative algorithms to track time-varying PIM sources. The system adapts to non-stationary environments by dynamically adjusting the spatial filters based on current channel conditions, thereby maintaining reliable PIM reduction despite environmental changes and hardware impairments.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs feedback mechanisms where the system monitors uplink PIM levels and uses this information to adjust downlink null steering weights iteratively. This closed-loop feedback enables the system to compensate for frequency-dependent hardware impairments and antenna calibration errors, improving adaptability while maintaining PIM reduction effectiveness.

Inventive Principle:

Principle #23Feedback

2Object-affected harmful factors

If null steering is applied to reduce PIM, then PIM interference is minimized, but the system becomes sensitive to estimation errors due to mutual coupling and antenna imperfections

Engineering Contradiction:

ImprovePIM interference levelVSAvoidspatial subspace estimation accuracy

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent incorporates robustness measures that anticipate and compensate for estimation errors before they significantly impact performance. By using iterative algorithms that gradually refine null steering weights and incorporating regularization techniques, the system cushions against the effects of mutual coupling and antenna imperfections, maintaining effective PIM reduction despite measurement uncertainties.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent dynamically adjusts null steering parameters through iterative optimization to account for estimation errors. By changing parameters such as weighting factors and convergence criteria based on observed performance, the system maintains effective PIM suppression even when spatial subspace estimation is affected by hardware imperfections.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If iterative algorithms with blind subspace tracking are implemented, then adaptability to changing PIM sources is improved, but computational complexity increases

Engineering Contradiction:

Improvetracking of changing PIM sourcesVSAvoidcomputational complexity of algorithm

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements partial subspace tracking by focusing computational resources on tracking only the dominant PIM sources rather than all possible signals. This selective approach maintains adaptability to changing PIM conditions while reducing computational complexity by processing only the most significant interference components.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent segments the computational task into distinct phases: initial subspace estimation, iterative weight optimization, and performance monitoring. This segmentation allows the system to achieve effective blind subspace tracking through manageable computational steps, reducing overall algorithmic complexity while maintaining adaptability.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20240380423A1Method and system for iterative downlink passive intermodulation spatial avoidance

Publication Date: 2024.11.14 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method, network node and wireless transceiver, for implementing iterative downlink passive intermodulation (PIM) spatial avoidance algorithms are provided. According to one aspect, a method in a wireless transceiver includes determining an uplink signal power. The method also includes determining an estimate of a downlink PIM subspace that minimizes a cost function that depends on the uplink signal power and a previous estimate of the downlink PIM subspace. The method further includes applying a correction to a downlink antenna signal to reduce the PIM, the correction being based at least in part on the estimate of the downlink PIM subspace