Distributed Non-Convex Beamforming for Inter-Cell Interference

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Solution Overview

Problem

Existing wireless cellular networks face limitations in optimizing wireless communication due to inter-cell interference, which reduces spectral efficiency and throughput, especially when inter-cell interference is not adequately mitigated in current beamforming designs.

Innovation Solution

The system employs distributed non-convex optimization across multiple base stations to determine optimal linear beamforming vectors and precoders that account for inter-cell interference, using Karush-Kuhn-Tucker equations and leakage matrices to maximize weighted sum-rate, while managing power constraints and channel estimates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If distributed non-convex optimization is used to determine optimal beamforming vectors, then spectral efficiency is improved, but computational complexity increases

Engineering Contradiction:
Improvespectral efficiencyVSAvoidcomputational complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent divides the network into multiple cells, each handled by a separate base station performing local optimization. This segmentation allows the global optimization problem to be broken into manageable local problems, reducing computational complexity while maintaining spectral efficiency improvements through coordinated beamforming across cells.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transforms the non-convex optimization problem into a convex form by changing parameters through successive convex approximation. This allows the use of efficient convex optimization algorithms to achieve near-optimal beamforming vectors, reducing computational complexity while maintaining high spectral efficiency.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If coordinated processing across multiple cells is implemented, then inter-cell interference is reduced, but network infrastructure complexity increases

Engineering Contradiction:
Improveinter-cell interferenceVSAvoidnetwork infrastructure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent segments the coordinated processing into cell-level operations where each base station independently optimizes its beamforming vectors based on local channel state information and interference conditions. This reduces network infrastructure complexity by avoiding centralized coordination while still mitigating inter-cell interference through distributed optimization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each base station performs self-service optimization by locally determining its beamforming vectors to minimize interference to other cells while maximizing its own spectral efficiency. This distributed self-service approach reduces the need for complex centralized coordination infrastructure while effectively managing inter-cell interference.

Inventive Principle:
Principle #25Self-service

3Productivity

If beamforming vectors are optimized based on inter-cell channel qualities, then throughput is improved, but information sharing requirements increase

Engineering Contradiction:
ImprovethroughputVSAvoidinformation sharing requirements
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent extracts only the essential information needed for beamforming optimization—channel quality indicators and interference measurements—from the full channel state information. This selective extraction reduces information sharing requirements between cells while maintaining throughput improvements through optimized beamforming vectors.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent transforms detailed channel state information into simplified parameters such as channel quality indicators and signal-to-interference-plus-noise ratios. These transformed parameters require less information sharing bandwidth while still enabling effective beamforming optimization and throughput improvement across cells.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS8218422B2Coordinated linear beamforming in downlink multi-cell wireless networks
Publication Date: 2012.07.10 NEC CORP
  • US8218422B2 patent drawing
  • US8218422B2 patent drawing
  • US8218422B2 patent drawing

AI summary

System and methods are disclosed for optimizing wireless communication for a plurality of mobile wireless devices. The system uses beamforming vectors or precoders having a structure optimal with respect to the weighted sum rate in a multi-cell orthogonal frequency division multiple access (OFDMA) downlink. A plurality of base stations communicate with the mobile devices and all base stations perform a distributed non-convex optimization exploiting the determined structure.