F-DPCH Outer Loop Power Control for Soft Handover
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Solution Overview
Problem
In 3rd generation mobile telecommunication systems, particularly in HSDPA with F-DPCH, user equipment faces challenges in setting a suitable SIR target for inner loop power control during soft handover due to varying uplink TPC BER across different radio links, leading to potential transmit power issues and interference.
Innovation Solution
The user equipment maps the target TPC BER to the SIR target using pre-simulated tables or mathematical relations based on propagation parameters, adjusts the SIR target by estimating the TPC BER from reliable radio links, and generates TPC commands to maintain the required quality on all links, employing a max weighted function to account for different radio link conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the user equipment sets the SIR target based on the worst radio link to ensure all links maintain TPC BER below target, then the downlink quality is maintained on all links, but the downlink power is wasted due to overly conservative SIR target
Solution Approach 1:
The patent applies local quality by differentiating the treatment of radio links based on their individual TPC BER performance. Instead of uniformly applying the worst-link SIR target to all links, the system identifies reliable links (those with TPC BER below threshold) and applies a more optimized SIR target specifically to them, while maintaining the conservative target only on unreliable links. This localized approach ensures quality where needed while reducing power waste on already-reliable links.
Solution Approach 2:
The patent introduces dynamic adjustment of SIR targets based on real-time TPC BER measurements. The system continuously monitors TPC BER on each radio link and dynamically adjusts the SIR target for reliable links based on their actual performance, rather than statically applying the worst-link target. This dynamic adaptation allows the system to respond to changing propagation conditions and optimize power usage accordingly.
2Ease of operation
If the user equipment uses a fixed SIR target setting, then the system operation is simple, but the SIR target cannot be adjusted correctly in dynamic propagation environment leading to unreliable TPC command detection
Solution Approach 1:
The patent implements feedback mechanisms where the user equipment continuously measures TPC BER on each radio link and uses this feedback to dynamically adjust the SIR target. The system monitors the performance of TPC command detection and adjusts the SIR target accordingly to maintain reliable detection. This closed-loop feedback ensures the system adapts to dynamic propagation conditions while maintaining operational simplicity through automated adjustment.
Solution Approach 2:
The system performs self-adjustment of the SIR target based on its own measurements of TPC BER performance. The user equipment autonomously identifies reliable links, calculates optimized SIR targets based on measured performance, and applies these adjustments without external intervention. This self-service capability allows the system to adapt to changing conditions while maintaining ease of operation.
3Productivity
If the user equipment derives SIR target from uplink TPC BER in single link case, then the power control is efficient, but the method is not specified for soft handover where different radio links have different TPC BER
Solution Approach 1:
The patent segments the radio links into distinct categories: reliable links (TPC BER below threshold) and unreliable links. This segmentation allows the system to apply different SIR target derivation methods to different links. For reliable links in soft handover, the system derives optimized SIR targets based on individual link performance, while maintaining the conservative worst-link approach for unreliable links. This segmented approach extends the efficient single-link method to multi-link soft handover scenarios.
Solution Approach 2:
The patent introduces dynamic selection of SIR target derivation method based on the handover state and link conditions. In single-link cases, the system uses the efficient uplink TPC BER-based derivation. In soft handover, the system dynamically identifies reliable links and applies optimized derivation to them while maintaining compatibility with the standard worst-link approach for unreliable links. This dynamic adaptation maintains power control efficiency across different operational modes.
Data Source
AI summary
A method and arrangement are described herein for power control for the F-DPCH (Fractional-Dedicated Physical Control Channel) for a 3rd generation mobile telecommunication system applying HSDPA, in particular for a user equipment in soft handover.