Radio Network Node Interference Mitigation in TDD Flexible Subframes
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Solution Overview
Problem
In radio communication networks using Time Division Duplex (TDD) configurations, interference occurs between neighboring cells due to flexible subframes where uplink and downlink transmissions overlap, affecting downlink signals received by victim User Equipment (UE) from uplink transmissions by aggressor UEs in other cells, which is unpredictable and difficult to control.
Innovation Solution
A method and system where radio network nodes detect and notify each other about overlapping subframes, allowing them to execute interference mitigation actions, such as adjusting transmission power or using more robust modulation schemes, to alleviate interference between UEs in neighboring cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flexible subframes are used in TDD configurations to allow variable uplink and downlink directions in neighboring cells, then network adaptability and resource utilization are improved, but interference between neighboring cells increases due to overlapping transmissions
Solution Approach 1:
The system performs preliminary detection of flexible subframe configurations in neighboring cells before interference occurs. By detecting the TDD configuration and identifying flexible subframes in advance, the system can proactively apply interference mitigation actions such as adjusting transmission power or applying interference coordination patterns during the overlapping subframes, thereby preventing severe interference before it degrades downlink reception.
Solution Approach 2:
The system establishes a feedback mechanism where radio network nodes detect and share information about flexible subframe configurations with neighboring cells. This feedback loop enables coordinated interference mitigation by allowing neighboring base stations to adjust their transmissions based on real-time knowledge of overlapping subframes, thus reducing interference while maintaining the adaptability benefits of flexible TDD configurations.
2Productivity
If different TDD configurations are applied in neighboring cells to meet varying uplink and downlink bandwidth needs, then resource allocation efficiency is improved, but unpredictable interference occurs during flexible subframes
Solution Approach 1:
The system detects and identifies flexible subframes in advance by examining TDD configurations of serving and neighboring cells. This preliminary identification allows the system to prepare and execute interference mitigation actions before the overlapping subframes occur, ensuring that downlink signal reception remains reliable during periods when different TDD configurations create interference conditions.
Solution Approach 2:
The system converts the harmful interference effect into a manageable condition by detecting the precise timing and configuration of flexible subframes. By knowing exactly when interference will occur based on TDD configuration analysis, the system can apply targeted mitigation strategies such as power adjustment or interference coordination patterns only during those specific subframes, thereby maintaining high resource allocation efficiency while ensuring signal reception reliability.
3Reliability
If uplink transmission power from aggressor UEs is increased to improve uplink signal quality, then uplink communication quality is improved, but interference to downlink signals in neighboring cells increases
Solution Approach 1:
The system applies interference mitigation actions periodically during flexible subframes where interference occurs. By detecting the TDD configuration and identifying when flexible subframes overlap between neighboring cells, the system can periodically adjust transmission parameters or apply interference coordination patterns specifically during those overlapping periods, thereby allowing high uplink power when needed while preventing downlink interference during vulnerable periods.
Data Source
AI summary
Methods and radio network nodes (BS1, BS2) for alleviating interference on downlink radio signals in a victim User Equipment, UE (T1, T2), caused by uplink transmission from an aggressor UE (T2, T1). The interference occurs during a flexible subframe in which the direction of signal transmission is variable between uplink and downlink in different radio frames. A first radio network node (BS1) detects (4:1) that a first UE (T1) that is served by the first radio network node (BS1) is one of the victim and aggressor UEs. The first radio network node (BS1) identifies (4:2) a second radio network node (BS2) employing a subframe scheme such that uplink transmission from the aggressor UE may overlap at least partly with downlink reception in the victim UE during the flexible subframe. The first radio network node (BS1) sends (4:3) a notification to the second radio network node, indicating that the first UE is served by the first radio network node. The second radio network node (BS2) is thereby triggered to execute (4:5) an interference mitigation action for alleviating the interference when serving a second UE (T2) being the other one of the victim and aggressor UEs.