HS-DPCCH Power Scaling for Multi-RAB UE
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Solution Overview
Problem
In wireless communication networks, user equipment (UE) operating in multi-radio access bearer (multi-RAB) scenarios often face power limitations, leading to insufficient transmit power for dedicated physical control and data channels, resulting in call drops due to insufficient allocated transmit power.
Innovation Solution
The UE reduces uplink transmission power by scaling the high-speed dedicated physical control channel (HS-DPCCH) independently of other channels, particularly when there is no downlink activity, and signals power-limited conditions to the serving cell, allowing for appropriate power management and maintaining higher power levels for vital channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transmits all channels at full power in multi-RAB mode, then the transmit power for each channel is sufficient, but the total transmit power exceeds the allocated power limit causing call drops
Solution Approach 1:
The patent segments the uplink transmission channels into critical channels (DPCCH, DPDCH for voice) and non-critical channels (HS-DPCCH for data feedback). By independently controlling the power of each segment, the system ensures that critical channels receive sufficient power to maintain call stability while non-critical channels have their power reduced to stay within the total power allocation, thereby resolving the contradiction between call reliability and power consumption.
Solution Approach 2:
The patent applies local quality by assigning different power priorities to different channels based on their importance. Critical channels maintaining full power while non-critical channels experience power reduction. This localized differentiation in power allocation ensures that the most important communication functions (voice calls) are protected while allowing flexibility in less critical functions (data feedback), thus maintaining call stability within power limits.
2Power
If the UE reduces HS-DPCCH power to stay within allocated power limits, then total transmit power is controlled, but the transmit power for control channels becomes insufficient potentially affecting channel quality feedback
Solution Approach 1:
The patent implements dynamic power scaling where the HS-DPCCH power is adjusted based on real-time conditions. When downlink data transmission is active, the HS-DPCCH maintains higher power to ensure accurate channel quality feedback. When no downlink activity is detected (timer expiration), the power is reduced. This dynamic adjustment allows the system to adapt power allocation to actual needs, maintaining measurement precision when necessary while reducing power consumption during idle periods.
Solution Approach 2:
The patent uses periodic downlink activity detection with a timer mechanism to determine when to reduce HS-DPCCH power. The timer is reset upon receiving downlink data and expires when no data is received for a predetermined period. This periodic monitoring creates a rhythm of high-power transmission during active communication and low-power transmission during idle periods, allowing the system to maintain channel quality feedback accuracy during data transmission while saving power during idle intervals.
3Measurement precision
If the UE maintains full power transmission for all channels during idle periods, then channel quality feedback is maintained, but power consumption is unnecessarily high
Solution Approach 1:
The patent employs periodic monitoring of downlink activity with a timer that triggers power scaling decisions. When the timer expires (indicating no downlink activity for a predetermined period), the UE scales down the HS-DPCCH power. This periodic action allows the system to maintain high measurement precision during active communication periods while significantly reducing power consumption during extended idle periods, optimizing the trade-off between feedback quality and energy usage.
Solution Approach 2:
The patent implements a self-service mechanism where the UE autonomously monitors its own downlink activity and automatically adjusts its transmit power accordingly. The UE uses an internal timer to detect idle periods and independently decides to scale down HS-DPCCH power without external intervention. This self-service approach enables the system to dynamically optimize power consumption based on actual communication needs, maintaining feedback quality when necessary while reducing energy usage during idle times.
Data Source
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AI summary
The disclosure provides for reducing uplink control channel overhead at a user equipment (UE). The UE may determine that a total transmit power of the UE exceeds an allocated power. The UE may then scale a transmit power of a high-speed dedicated physical control channel (HS-DPCCH) relative to a dedicated physical control channel (DPCCH) in response to the determination that the UE is power limited. The UE may scale the transmit power of the HS-DPCCH when there is no downlink activity as determined, for example, by expiration of a timer. In an aspect, the UE may transmit an indication that the UE is power limited, for example, by using a most-significant bit of a transport format combination index. In another aspect, the UE may receive an indication that a downlink transmission is imminent and, in response, the UE may transmit the HS-DPCCH without scaling its corresponding transmit power.