Uplink Power Offset Control for WCDMA Data Flows
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Solution Overview
Problem
In WCDMA systems, the control of transmission power for uplink data flows is inefficient when there are differences in interleaving gain and soft handover gain due to varying frame lengths and the number of receiving base stations, leading to suboptimal link quality and increased latency.
Innovation Solution
A method where mobile stations transmit data flows to different base stations with specific power offsets, and the base stations and radio network controller collaborate to adjust these offsets based on retransmission occurrences and target error rates, ensuring simultaneous efficient transmission power control for multiple data flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single power offset control method is used for multiple data flows, then the control mechanism is simple, but transmission efficiency decreases when data flows have different frame lengths and soft handover gains
Solution Approach 1:
The patent segments the power offset control by creating separate control loops for different data flows (DCH and EUDCH). Each data flow has its own power offset parameter (PO_DCH and PO_EUDCH) that can be independently adjusted based on its specific requirements, such as frame length and soft handover gain, thereby resolving the contradiction between control simplicity and transmission efficiency.
2Reliability
If transmission power is increased to improve link quality, then link quality improves, but power consumption increases
Solution Approach 1:
The patent implements feedback mechanisms through outer loop power control that monitors block error rates and adjusts power offsets accordingly. The system uses ACK/NACK feedback from the receiver to dynamically adjust transmission power, ensuring that power is increased only when necessary to maintain link quality, thus resolving the contradiction between link quality and power consumption.
3Productivity
If separate power offsets are used for different data flows, then transmission efficiency improves, but control complexity increases
Solution Approach 1:
The patent introduces dynamic adjustment of power offsets through separate outer loop control mechanisms for different data flows. The power offsets (PO_DCH and PO_EUDCH) are dynamically adjusted based on individual flow conditions such as frame length variations and soft handover gains, allowing the system to adapt to changing conditions while maintaining efficiency. This dynamic approach resolves the contradiction by making the control mechanism flexible rather than statically complex.
Data Source
AI summary
A mobile station (MS) transmits a first data flow to a first group of base stations with a first power offset, transmits a second data flow to a second group of base stations, and further transmits a pilot signal. A radio network controller (RNC) controls the power of the pilot signal power based on reception errors of the second data flow, calculates the first power offset based on signaled required level of the first power offset from base stations (BTS) of the first group which calculate the required level of the first power offset based on an occurrence of retransmission, signals the calculated first power offset to the mobile station.