Uplink Power Scaling for Multi-RAB Wireless Systems
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Solution Overview
Problem
Current power scaling methods in wireless communication networks, particularly in UMTS W-CDMA systems, face limitations in maintaining signal quality as user equipment moves away from the base station, leading to reduced radio coverage due to total transmit power constraints, especially at the cell edge or in deep signal fades.
Innovation Solution
A method and user equipment configuration that performs power scaling on uplink transmissions by reducing E-DPDCH gain factors and applying discontinuous transmission (DTX) on E-DPCCH when the total transmit power exceeds the maximum limit, allowing for situational power adjustments and optimizing power allocation between DPDCH and DPCCH channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power scaling is applied to reduce total transmit power to the maximum limit, then power utilization is optimized, but signal quality deteriorates due to reduced power on individual channels
Solution Approach 1:
The patent applies different power scaling strategies to different channels based on their specific requirements. Control channels (DPCCH, E-DPCCH) maintain higher power levels to ensure reliable power control signaling, while data channels (DPDCH, E-DPDCH) are scaled down more aggressively. This local differentiation of power allocation allows the system to optimize overall power utilization while maintaining minimum signal quality thresholds for critical channels.
Solution Approach 2:
The power scaling factors for different channels are dynamically adjusted based on current transmission conditions, channel quality indicators, and power headroom reports. The system continuously adapts the power distribution among channels rather than using fixed scaling ratios, allowing it to respond to changing conditions and maintain signal quality when possible while maximizing power efficiency.
2Reliability
If transmit power is increased to maintain signal quality as UE moves away from base station, then signal quality is maintained, but total power limit is exceeded
Solution Approach 1:
The patent segments the total transmit power into distinct allocations for control channels and data channels. By separating the power allocation into these functional segments, the system can ensure that control channels receive sufficient power to maintain basic communication and power control functionality, while data channels can be scaled down when the total power limit is approached. This segmentation allows the system to operate within power limits while maintaining essential signal quality.
3Power
If E-DPDCH gain factors are reduced to comply with power limits, then power scaling is achieved, but data transmission performance deteriorates
Solution Approach 1:
The system uses feedback mechanisms including power headroom reports from the UE and channel quality indicators from the base station to dynamically adjust E-DPDCH gain factors. When power headroom is sufficient, E-DPDCH can transmit at higher gain factors for better performance. When power limits are approached, the feedback loop triggers reduction of E-DPDCH gain factors. This feedback-based adaptation allows the system to maintain data transmission performance when possible while achieving necessary power scaling when required.
Data Source
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AI summary
The present disclosure relates to a method and user equipment, UE, in a wireless communication network of performing power scaling on uplink transmission to a receiving radio access node, RAN. In particular, the disclosure relates to a method and user equipment for power scaling on uplink transmissions on a multi-radio access bearer, multi-RAB, wherein a Dedicated Physical Data Channel, DPDCH, and enhanced Data Channels, E-DCHs are configured for uplink transmission from the UE to the receiving RAN. The method comprises determining (S31) a total UE transmit power exceeding a predetermined maximum power limit value. The total UE transmit power is reduced (S32) to the predetermined maximum power limit value by reducing one or more E-DPDCH gain factors by an equal scaling factor. When a predetermined minimum E-DPDCH gain factor, 'smallest quantised βed,k value', is reached for all E-DPDCH gain factors βed,k, and DTX is applied for all E-DPDCHs, the method comprises applying (S33) DTX on E-DPCCH.