Uplink Power Control for Soft Handover Interference
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Solution Overview
Problem
In wireless communication systems, particularly in WCDMA, uplink transmission power control during soft handover is challenging due to conflicting power control commands from multiple base stations, leading to unnecessary interference and inadequate signal reception by high-power base stations, especially in heterogeneous networks and CoMP scenarios.
Innovation Solution
A user equipment (UE) method for combining transmission power control (TPC) commands from multiple base stations to robustly control uplink transmission power, adjusting the βHS parameter based on received commands to ensure reliable high-speed dedicated physical control channel transmission while minimizing interference to other base stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE transmits at high power to ensure reliable reception by all base stations during soft handover, then reception reliability improves, but unnecessary interference to neighboring cells increases
Solution Approach 1:
The patent applies local quality by differentiating power control treatment for different base stations. The serving high-power base station receives enhanced power control to ensure reliable reception, while low-power base stations experience reduced interference through coordinated power management. This selective approach optimizes reception reliability for critical connections while minimizing harmful interference to other cells.
2Object-generated harmful factors
If a UE reduces transmit power to minimize interference to neighboring cells, then interference levels decrease, but signal reception quality by the serving base station deteriorates
Solution Approach 1:
The patent implements feedback mechanisms where base stations transmit power control commands to the UE based on received signal quality measurements. The serving high-power base station provides feedback to maintain adequate signal quality, while the system coordinates with low-power base stations to manage interference levels. This closed-loop control resolves the contradiction by dynamically adjusting power based on actual reception needs.
3Object-generated harmful factors
If the UE follows the operational rule to reduce power when any DOWN command is received, then interference is reduced, but the serving high-power base station may not receive the signal adequately
Solution Approach 1:
The patent segments the power control command processing by base station type. Instead of applying a uniform operational rule from all base stations, the system identifies and prioritizes commands from the serving high-power base station. This segmentation allows the UE to maintain adequate power levels for critical serving cell communication while still considering interference management instructions from other base stations.
Solution Approach 2:
The patent applies preliminary action by having the UE identify and prioritize power control commands from the serving high-power base station before applying commands from other base stations. This ensures that the serving base station's reception requirements are met first, and interference management is handled in a secondary manner that does not compromise critical signal quality.
Data Source
AI summary
A method by a user equipment node controls uplink transmission power during soft handover of the user equipment node from a first base station to a second base station. A transmission power control command is received by the user equipment node from each of the first and second base stations during the soft handover. Uplink transmission power by the user equipment node of a high-speed dedicated physical control channel is controlled responsive to the received transmission power control commands.