Closed-Loop Uplink Power Control for Interference Management
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Solution Overview
Problem
Existing uplink power control methods in cellular networks often lead to uncontrolled power ramp-up in user equipment (UE) when the set of desired target SINRs is not feasible, resulting in excessive interference and reduced battery life, especially near cell edges.
Innovation Solution
Implementing a closed-loop power control system that adaptively adjusts the desired target SINR based on current and prior SINR, interference, and transmission power control measurements to ensure feasible and optimized UE transmit power levels, preventing unnecessary power increases while maintaining SINR gains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open loop power control is used to simplify the system, then device complexity is reduced, but transmit power is excessively high causing system-level interference and reduced battery life
Solution Approach 1:
The patent implements closed-loop power control where the base station measures the achieved SINR for each mobile station and feeds back transmission power control commands to adjust UE transmit power. This feedback mechanism enables dynamic power adjustment based on actual channel conditions, reducing system-level interference while maintaining reliable communication.
2Reliability
If closed loop power control with fixed TPC command set is implemented, then power control capability is improved, but uncontrolled power ramp-up occurs when target SINR is not feasible
Solution Approach 1:
The patent dynamically adjusts the target SINR value based on the mobile station's position relative to the cell edge and channel conditions. For cell-edge UEs where high target SINR would cause uncontrolled power ramp-up, the system lowers the target SINR to feasible levels. This dynamic adaptation prevents excessive power increases while maintaining power control effectiveness for non-cell-edge UEs.
3Productivity
If high transmit power is used to guarantee highest SNR for maximizing link throughput, then link throughput is improved, but battery life is reduced and unnecessary interference is caused
Solution Approach 1:
The patent changes the target SINR parameter dynamically based on mobile station location and channel conditions. By adapting the target SINR to match actual channel quality, the system achieves optimal throughput without unnecessarily high transmit power. This parameter adaptation ensures UEs transmit at the minimum power needed to achieve reliable communication, extending battery life while maintaining throughput.
4Adaptability or versatility
If distributed power control is implemented independently for each eNB-UE link, then system adaptability is improved, but uncontrolled power ramp-up occurs when target SINR set is not jointly feasible
Solution Approach 1:
The patent applies local quality by differentiating power control behavior based on mobile station location. Cell-edge UEs receive adjusted target SINR values to prevent uncontrolled power ramp-up, while non-cell-edge UEs maintain standard target SINR for optimal performance. This localized adaptation resolves the contradiction between distributed adaptability and network-wide interference control.
Data Source
AI summary
Systems and methods are disclosed that provide a closed loop power control system including adaptively adjusting the desired target SINR over time so as to ultimately achieve a feasible SINR. In one implementation, a method is provided of optimizing uplink closed loop power control in a RAN in which one or more base stations each service a plurality of mobile stations, including: determining a power level for each mobile station for its respective uplink transmissions, including measuring a current achieved SINR for each mobile station; and for each mobile station, adjusting the power level to be sufficiently high to meet desired transmission characteristics but not so high as to cause unnecessary interference with transmissions from other mobile stations, by adjusting a desired target SINR based on factors selected from the following: current and prior achieved SINRs, current and prior interference measurements, and current and prior transmission power control commands.