Directional TDD Restriction for Cross-Link Interference Mitigation
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Solution Overview
Problem
Cross-link interference (CLI) occurs between neighboring cells operating with different Time Division Duplex (TDD) configurations, leading to significant interference, especially in cell-edge areas and overlapping geographical regions, which hinders efficient spectrum utilization and network performance.
Innovation Solution
Implementing a restricted TDD configuration that excludes transmission in time units with differing configurations and applying this configuration in specific physical directions to minimize CLI, using beamforming techniques to manage interference in overlapping network areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If neighboring cells use different TDD configurations to dynamically adapt to traffic patterns, then spectrum utilization and network flexibility improve, but cross-link interference between cells increases significantly
Solution Approach 1:
The patent applies local quality by allowing different TDD configurations in different spatial locations (neighboring cells) while managing interference through directional transmission. Each cell can have optimized TDD configuration for its local traffic needs, but beamforming restricts transmission to specific directions to avoid interfering with adjacent cells using different configurations.
Solution Approach 2:
The patent introduces spatial dimension (beamforming direction) to resolve the time-domain conflict of different TDD configurations. By adding the spatial dimension of directional transmission, the system allows temporal diversity in TDD configurations while preventing interference through spatial separation of transmission beams.
2Reliability
If UEs use high transmit power to compensate for large path losses to their serving base stations, then coverage and connectivity improve, but interference to neighboring cells operating on adjacent frequencies increases
Solution Approach 1:
The patent segments the transmission in both time and space dimensions. Time segmentation through TDD configuration divides transmission into uplink and downlink slots, while spatial segmentation through beamforming divides the transmission space into directional beams. This dual segmentation allows high transmit power for reliability while confining interference to specific directions and time slots.
Solution Approach 2:
The patent uses periodic TDD configurations that alternate between uplink and downlink transmission in a regular pattern. This periodic action creates predictable interference patterns that can be managed through coordination, allowing UEs to use high power during their allocated uplink slots while neighboring cells know when to expect and can prepare for potential interference.
3Ease of operation
If a fixed TDD pattern is mandated for coexistence between operators, then interference management simplifies, but potential spectrum utilization improvement from dynamic TDD is not utilized
Solution Approach 1:
The patent introduces dynamics by allowing TDD configurations to adapt to traffic conditions while maintaining coordination mechanisms. Rather than completely fixed or completely independent configurations, the system enables dynamic adjustment within a coordinated framework, allowing operators to optimize for their traffic patterns while maintaining simplicity through established coordination protocols.
Data Source
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AI summary
The method is performed in network node for reducing the impact of interference in a cell from at least another neighbouring cell. The cell operates using a time division duplex, TDD, configuration, and the neighbouring cell operating using another TDD configuration. The TDD configurations are divided into different time units for at least downlink, DL, and uplink, UL, transmissions. The method includes identifying time units in the TDD configuration. The identification of a time unit is based on whether the time unit has a different configuration compared to the time unit in the another TDD configuration used in the neighbouring cell. The method further includes defining a restricted TDD configuration for use in the cell, where the restricted TDD configuration excludes transmission in the identified time units. Furthermore, the method further includes identifying a physical direction in which to apply the restricted TDD configuration. A network node, a computer program, and a computer program product for reducing the impact of interference from at least another wireless device operating in a neighbouring cell using another TDD configuration are also provided.