Reverse Link Feedback for Interference Control in Wireless Systems
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Solution Overview
Problem
Wireless communication systems face interference issues due to non-orthogonal transmissions from multiple terminals, leading to decreased performance, as complete orthogonality is often not achieved due to channel conditions and receiver imperfections.
Innovation Solution
The system employs reverse link feedback techniques to determine a maximum transmit power that minimizes interference, using channel quality and interference data from serving and neighboring sectors, and provides power amplifier headroom feedback to adjust transmit power, allowing the serving sector to assign optimal power levels based on quality of service and system parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple terminals transmit simultaneously on the reverse link, then system capacity and communication services are improved, but interference between terminals increases due to non-orthogonal transmissions
Solution Approach 1:
The patent implements a feedback mechanism where the serving sector measures interference caused by each terminal and sends interference measurements back to the terminal. The terminal uses this feedback to adjust its transmit power, creating a closed-loop control system that dynamically manages interference while maintaining system capacity.
Solution Approach 2:
The patent dynamically adjusts the transmit power parameter of each terminal based on measured interference levels. By changing the power parameter in response to interference conditions, the system maintains optimal performance while reducing harmful interference effects.
2Reliability
If terminal transmit power is increased to improve communication quality, then signal quality is improved, but interference to other terminals increases
Solution Approach 1:
The serving sector continuously measures the interference caused by each terminal and provides this information as feedback. The terminal uses this real-time feedback to adjust its transmit power, ensuring communication quality is maintained while preventing excessive interference to other terminals.
Solution Approach 2:
The patent implements dynamic power adjustment where the terminal's transmit power is not fixed but continuously adapted based on current interference conditions. This dynamic approach allows the system to optimize communication quality while responding to changing interference environments.
3Object-generated harmful factors
If complete orthogonality is enforced between terminal transmissions, then interference is reduced, but system flexibility and adaptability to channel conditions decrease
Solution Approach 1:
Instead of enforcing fixed orthogonality constraints, the patent allows terminals to operate with flexible power parameters that are dynamically adjusted based on actual interference measurements. This approach maintains adaptability to channel conditions while controlling interference through measured feedback.
Solution Approach 2:
Each terminal autonomously adjusts its own transmit power based on interference feedback from the serving sector, without requiring centralized scheduling or strict orthogonality enforcement. This self-service approach maintains system flexibility while achieving interference control.
Data Source
AI summary
Systems and methodologies are described that provide techniques for generating and utilizing reverse link feedback for interference management in a wireless communication system. Channel quality and/or interference data can be obtained by a terminal from a serving sector and one or more neighboring sectors, from which an interference-based headroom value can be computed that contains interference caused by the terminal to an allowable range. The interference-based headroom value can then be provided with power amplifier (PA) headroom feedback to the serving sector. Based on the provided feedback from the terminal, the serving sector can assign resources for use by the terminal in communication with the serving sector. Further, the serving sector may choose to honor or disregard a received interference-based power value based on quality of service and/or other system parameters.