Distributed Precoding Weight Computation for CoMP Interference

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Solution Overview

Problem

Conventional centralized CoMP architectures in mobile communication networks suffer from uncoordinated inter-cell interference, leading to service quality disparities and scalability issues, as well as increased costs and complexity due to large CoMP cells and extensive backhaul connections.

Innovation Solution

A distributed method for computing linear precoding weights allows base stations in each serving cell to use both their own and neighboring antennas, forming 'floating' CoMP cells that overlap, with power availability scaling to minimize interference and adhere to power constraints, enabling coordinated multipoint transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a centralized CoMP architecture is used to coordinate transmissions within a CoMP cell, then interference among UEs within the same cell is reduced, but uncoordinated interference from neighboring CoMP cells increases service quality disparity

Engineering Contradiction:
Improveinter-cell interferenceVSAvoidservice quality
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention divides the network into multiple CoMP cells, each independently coordinating its transmissions. This segmentation allows distributed decision-making at each CoMP cell level, enabling interference coordination between neighboring cells while maintaining coordination within each cell, thus resolving the service quality disparity issue.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention implements feedback mechanisms where CoMP cells exchange information about their transmission coordinates and interference levels. This feedback enables dynamic adjustment of precoding weights and transmission parameters to mitigate inter-CoMP-cell interference, improving overall service quality.

Inventive Principle:
Principle #23Feedback

2Object-affected harmful factors

If the number of cells in each CoMP cell is increased to reduce uncoordinated interference, then interference mitigation improves, but synchronization difficulty and backhaul cost increase

Engineering Contradiction:
Improveuncoordinated interferenceVSAvoidsynchronization complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of creating large CoMP cells with many cells, the invention segments the network into smaller CoMP cells that can be independently managed. This reduces the synchronization complexity and backhaul requirements while still achieving interference mitigation through coordinated transmission between neighboring CoMP cells.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention employs dynamic coordination where CoMP cells can flexibly adjust their boundaries and participating cells based on traffic conditions and interference levels. This dynamic approach allows the system to optimize interference mitigation without being constrained by fixed large cell structures, reducing synchronization overhead.

Inventive Principle:
Principle #15Dynamics

3Object-affected harmful factors

If the number of cells in each CoMP cell is increased to reduce uncoordinated interference, then interference mitigation improves, but backhaul cost increases

Engineering Contradiction:
Improveuncoordinated interferenceVSAvoidbackhaul cost
Core Design Contradiction:
Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The invention segments the network into smaller CoMP cells, reducing the backhaul connectivity requirements compared to large CoMP cells. Each CoMP cell only needs backhaul connections to its neighboring CoMP cells for coordination, rather than connecting all cells to a central processor, thereby reducing backhaul cost.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses distributed coordination mechanisms where each CoMP cell acts as an intermediary for its own coordination needs. This eliminates the need for a centralized backhaul infrastructure connecting all cells, as each CoMP cell independently manages its coordination with neighbors, reducing overall backhaul cost.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Object-affected harmful factors

If a centralized architecture is used to compute precoding weights, then coordination within a CoMP cell is achieved, but scalability to future traffic increase is limited

Engineering Contradiction:
ImproveinterferenceVSAvoidscalability
Core Design Contradiction:
Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The invention segments the precoding weight computation function to be performed independently at each CoMP cell based on local channel state information. This distributed computation approach eliminates the scalability bottleneck of centralized architectures, as each CoMP cell can independently adapt to traffic increases without requiring changes to a central processor.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each CoMP cell autonomously computes its precoding weights using local CSI and coordination information from neighboring cells. This self-service capability enables each CoMP cell to independently scale with traffic increases, improving overall system scalability without requiring centralized control changes.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2430772B1Distributed computation of precoding weights for coordinated multipoint transmission on the downlink
Publication Date: 2015.02.25 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP2430772B1 patent drawingFigure 1
  • EP2430772B1 patent drawingFigure 2
  • EP2430772B1 patent drawingFigure 3

AI summary

In a Coordinated Multi-point (CoMP) system, the base station (BS) in each serving cell ( or sector) is allowed to use not only its own antennas, but also the antennas of neighboring BSs to transmit to mobile terminals in the serving cell to form a floating CoMP cell The serving BS in each floating CoMP cell computes tentative linear preceding weights for transmissions from the coordinating BSs in the floating CoMP cell to users in the serving cell of the floating CoMP cell. The serving RS determines the power availability for transmit antennas in the floating CoMP cell that are shared with other floating CoMP cells, and scales the tentative preceding weights based on the power availability of the shared transmit antennas to determine final preceding weights so that the power constraints of the shared transmit antennas will not be violated.