Wireless Transmit Power Control via Pilot Interference Cancellation
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Solution Overview
Problem
Current transmit power control methods in wireless communications, particularly in WCDMA/HSPA systems, fail to independently control pilot and data power, leading to potential interference increase and reduced benefits from interference cancellation techniques, as they only consider the performance of a single user.
Innovation Solution
A method that involves obtaining the channel quality of a pilot channel, performing interference cancellation, and adjusting the transmit power of user equipment based on threshold values to optimize power control, ensuring better DPCCH quality for effective interference cancellation and minimizing interference impact on other users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transmit power control is used that only considers single user performance, then the power control implementation is simple, but interference increases after interference cancellation and the benefits from interference cancellation are reduced
Solution Approach 1:
The power control is segmented into two independent parts: pilot power control based on DPCCH quality before interference cancellation, and data power control based on data channel quality after interference cancellation. This segmentation allows each part to be optimized independently, resolving the contradiction between maintaining simplicity and achieving reliable interference cancellation benefits.
Solution Approach 2:
The patent performs preliminary power control adjustment on the pilot channel before interference cancellation is applied. By ensuring the DPCCH quality meets requirements before IC processing, the system prepares the necessary conditions for effective interference cancellation, thereby improving reliability without significantly increasing overall complexity.
2Productivity
If pilot power is decreased to optimize data rate, then data channel performance improves, but channel estimation quality deteriorates which negatively impacts interference cancellation
Solution Approach 1:
The patent separates pilot power control from data power control. Pilot power is controlled independently to ensure sufficient channel estimation quality, while data power can be optimized separately for maximum data rate. This segmentation resolves the contradiction by allowing both objectives to be pursued simultaneously without compromise.
Solution Approach 2:
Different quality requirements are applied to different parts of the signal: the pilot channel is maintained with high quality to ensure accurate channel estimation, while the data channel can operate at lower quality levels optimized for throughput. This local quality differentiation resolves the contradiction between estimation accuracy and data rate optimization.
3Productivity
If data power is increased to improve throughput, then data rate increases, but interference to other users increases
Solution Approach 1:
The patent implements feedback-based power control where the base station monitors data channel quality after interference cancellation and sends power control commands to the mobile station. This closed-loop feedback mechanism allows the system to increase data power when conditions permit (improving throughput) while automatically reducing power when interference becomes problematic, thus resolving the contradiction dynamically.
Solution Approach 2:
The power control parameters are made dynamic rather than fixed. The system continuously adjusts pilot and data power levels based on current channel conditions, interference levels, and quality requirements. This dynamic adjustment allows the system to maximize throughput when possible while minimizing interference, resolving the contradiction between these conflicting objectives.
Data Source
AI summary
A method for transmit power control (TPC) is provided. The method includes obtaining a first channel quality of a pilot channel for a user equipment (UE); performing an interference cancellation on the pilot channel to obtain a second channel quality of the channel; and instructing the UE to adjust the transmit power based on at least the first channel quality.