Dynamic TDD Cross-Subframe Interference Coordination

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Solution Overview

Problem

Dynamic TDD systems face significant cross-subframe interference, particularly BS-BS interference, which degrades system performance due to asymmetric UL-DL configuration allocations in response to varying traffic conditions, leading to reduced throughput.

Innovation Solution

A method and apparatus for cross-subframe interference coordination in dynamic TDD systems, which involves obtaining UL-DL configurations across cells and determining beamforming vectors for interfering cells to minimize interference, thereby improving system throughput.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If dynamic UL-DL configuration allocation is implemented to match traffic conditions, then system adaptability and throughput are improved, but cross-subframe interference between neighboring cells increases significantly

Engineering Contradiction:

Improvetraffic condition matchingVSAvoidcross-subframe interference

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the beamforming vector parameters of interfering base stations based on their UL-DL configurations and channel state information. By dynamically adjusting these parameters, the system maintains adaptability to traffic conditions while controlling cross-subframe interference through coordinated parameter modification across multiple cells.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where channel state information and interference levels are continuously monitored and used to adjust beamforming vectors. This feedback loop enables the system to adapt to changing traffic conditions while actively managing interference by responding to real-time channel conditions.

Inventive Principle:

Principle #23Feedback

2Object-affected harmful factors

If beamforming vectors are adjusted to reduce cross-subframe interference, then interference levels are reduced, but system complexity increases due to coordination requirements

Engineering Contradiction:

Improvecross-subframe interferenceVSAvoidcoordination complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent segments the interference coordination problem by treating each cell's beamforming adjustment independently based on its specific UL-DL configuration and channel conditions. This segmentation allows complex multi-cell coordination to be broken down into manageable per-cell optimizations, reducing overall system complexity while maintaining interference reduction benefits.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If static UL-DL configuration is used across all cells, then coordination complexity is minimized, but system throughput decreases due to inability to match asymmetric traffic demands

Engineering Contradiction:

Improveconfiguration coordinationVSAvoidsystem throughput

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent embraces asymmetric UL-DL configurations across different cells to match asymmetric traffic demands, rather than forcing symmetric configurations. By allowing and managing asymmetric configurations through beamforming coordination, the system achieves higher throughput while controlling interference, resolving the contradiction between simplicity and performance.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS9807776B2Method and apparatus for cross-subframe interference coordination

Publication Date: 2017.10.31 NEC CORP

AI summary

Embodiments of the disclosure provide a method and apparatus for cross-subframe interference coordination in a dynamic TDD system. The method comprises steps of: obtaining UL-DL configurations employed by a plurality of cells in the dynamic TDD system; and determining, based on the UL-DL configurations, a beamforming vector of at least one interfering cell which has cross-subframe interference on at least one interfered cell, so as to reduce the cross-subframe interference.