Quasi Full Duplex TDD Access Point Interference Mitigation
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Solution Overview
Problem
Time division duplexing (TDD) systems face desensitization of receiver components due to strong RF transmission signals, and traditional self-interference cancellation methods struggle to achieve unconditional cancellation in dynamic environments, leading to interference and reduced signal quality for user equipment (UEs) at a distance from the base station.
Innovation Solution
A communication system that monitors signal quality and adjusts transmission power in quasi-full duplex mode, either by fully muting or proportionally reducing Tx power when signal quality falls below a threshold, and restoring full power once quality improves, while also using intelligent resource block management to assign UEs to subchannels based on their distance from the base station, minimizing interference and ensuring reliable signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-interference cancellation systems are used to prevent desensitization of Rx path, then receiver sensitivity is improved, but device complexity increases and cancellation capability is limited in dynamic environments
Solution Approach 1:
The patent implements dynamic UL-DL switch point adjustment based on real-time signal quality monitoring. The system continuously monitors Rx signal quality and adapts the TDD switching points to prevent desensitization events, transitioning from static to dynamic operation to maintain receiver sensitivity without requiring complex SIC systems.
Solution Approach 2:
The system employs feedback mechanisms where Rx signal quality is continuously monitored and used to adjust UL-DL switch points. This closed-loop control enables the system to respond to changing channel conditions and prevent desensitization by adapting transmission parameters based on received signal quality measurements.
2Object-affected harmful factors
If Tx power is reduced to prevent desensitization during UL transmission, then receiver protection is improved, but downlink signal quality for distant UEs deteriorates
Solution Approach 1:
The system dynamically adjusts UL-DL switch points based on monitored signal quality and UE distance. For distant UEs, the system maintains higher Tx power longer by adjusting switch points, while for near UEs it reduces Tx power earlier to prevent desensitization. This dynamic adaptation resolves the contradiction between protecting the Rx path and maintaining downlink quality for distant UEs.
Solution Approach 2:
The system applies different Tx power reduction strategies based on local conditions, specifically UE distance from the base station. Distant UEs receive full or reduced power during DL transmissions while near UEs experience more aggressive power reduction to prevent desensitization, allowing differentiated treatment based on spatial location and signal conditions.
3Area of stationary object
If Tx power is increased to serve distant UEs, then coverage is improved, but interference to Rx path increases causing desensitization
Solution Approach 1:
The system maintains extended coverage by using high Tx power for DL transmissions to distant UEs while dynamically adjusting UL-DL switch points to prevent desensitization during UL reception. The dynamic switching enables the system to operate in quasi-full-duplex mode, maintaining coverage area while managing self-interference through adaptive timing adjustments.
4Device complexity
If traditional TDD switch points are used, then system simplicity is maintained, but signal quality for near UEs during UL reception deteriorates due to desensitization
Solution Approach 1:
The system implements dynamic UL-DL switch point adjustment that adapts to UE distance and signal conditions. For near UEs, the switch points are adjusted to occur earlier, preventing desensitization of the Rx path during their UL transmissions. This maintains simple TDD operation while improving UL signal quality for near UEs through adaptive timing control.
Data Source
AI summary
A method of reducing interference in a time division duplexing access point during a quasi-full duplex mode in a communication system is provided. The method includes monitoring a signal quality of received signals from at least one user equipment (UE) at a base station. Transmission power used to a transmit signals from the base station is lowered when the monitored signal quality goes below a threshold. Full transmission power to transmit signals is restored once the signal quality of the received signals is above the threshold.