UE Feedback Power Control for Cross-Link Interference Mitigation
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Solution Overview
Problem
Existing communication networks face challenges in managing cross-link interference (CLI) between uplink and downlink transmissions in non-overlapping sub-bands, particularly intra-cell UE-to-UE interference, which degrades signal-to-interference noise ratio (SINR) and affects user equipment performance.
Innovation Solution
Implementing a method for user equipment (UE) to report a power headroom report value (PHR) based on expected cross-link interference, allowing the network to adjust uplink transmit power and schedule transmissions to minimize CLI, using techniques such as CSI-IM based CLI-RSSI reporting and conditional PHR triggering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uplink transmit power is increased to improve signal quality, then communication reliability is improved, but cross-link interference to downlink transmissions increases
Solution Approach 1:
The patent dynamically adjusts the uplink transmit power parameter based on detected cross-link interference conditions. When CLI is detected in mixed slots, the UE reduces uplink power by a calculated offset (e.g., 6dB), transforming the fixed power parameter into a variable one that adapts to interference conditions, thereby resolving the contradiction between maintaining communication reliability and reducing harmful interference.
Solution Approach 2:
The patent implements a feedback mechanism where the UE monitors downlink transmissions for CLI, determines the interference level, and adjusts uplink power accordingly. The network node receives power headroom reports and can request power adjustments, creating a closed-loop feedback system that continuously balances communication reliability against interference generation.
2Object-generated harmful factors
If power headroom reporting is always performed to enable interference mitigation, then cross-link interference is reduced, but signaling overhead and device complexity increase
Solution Approach 1:
The patent applies partial action by triggering power headroom reporting only in specific conditions rather than continuously. The UE determines whether to report based on whether it is in a mixed slot and whether CLI is detected, performing the reporting action only when necessary to mitigate interference, thereby reducing unnecessary signaling overhead while still achieving CLI mitigation when needed.
Solution Approach 2:
The patent applies local quality by differentiating reporting behavior across different slot types. In mixed slots where CLI is possible, the UE reports power headroom information; in pure uplink or downlink slots, reporting is suppressed. This localized approach to quality control ensures interference mitigation is achieved precisely where needed without imposing system-wide signaling complexity.
3Productivity
If simultaneous downlink and uplink transmissions are scheduled in mixed slots to improve spectral efficiency, then network capacity increases, but UE-to-UE cross-link interference occurs
Solution Approach 1:
The patent introduces dynamics into the power control system by making uplink transmit power variable based on real-time interference detection. In mixed slots where simultaneous DL/UL transmissions occur, the UE dynamically adjusts power based on detected CLI levels, allowing the system to maintain high spectral efficiency through concurrent transmissions while adaptively managing the harmful interference they generate.
Solution Approach 2:
The patent converts the harmful effect of uplink transmissions (which cause CLI to downlink) into a beneficial control mechanism. By detecting the interference caused by uplink power and using that information to adjust power levels, the system transforms the harmful CLI into useful feedback for optimization, allowing mixed slot operations to proceed with controlled interference rather than avoiding them entirely.
Data Source
AI summary
An apparatus comprising: at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to: determine whether to report a power headroom report value to a network node, the power headroom report value being applicable to a mixed slot where simultaneous transmissions in downlink and uplink are scheduled in non-overlapping sub-bands of the same carrier; wherein the power headroom report value is based on a difference between an uplink transmit power given an expected cross link interference for a user equipment, and an uplink transmit power at the mixed slot; and determine whether to reduce the uplink transmit power at the mixed slot, based on information received from the network node.