Uplink Power Control via UE-Specific Reference Signals
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Solution Overview
Problem
In heterogeneous radio communication networks, uplink power control is inefficient due to uneven output powers of different base stations, leading to excessive interference and high power consumption, as UEs often regulate their transmit power based on macro RBSs despite having lower path loss with pico RBSs, causing interference and suboptimal resource utilization.
Innovation Solution
A base station system dynamically controls uplink power by detecting excessive power usage and transmitting a communication device-specific reference signal with adjusted power, allowing UEs to calculate a lower path loss value and reduce their output power, thereby minimizing interference and conserving battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UEs regulate transmit power based on macro RBSs, then downlink coverage is maintained, but uplink interference increases and power consumption rises
Solution Approach 1:
The patent applies local quality by enabling UEs to use different reference signals for downlink coverage assessment versus uplink power control. Specifically, UEs continue to use macro RBS CRS for downlink coverage maintenance while simultaneously using pico RBS PCRS for uplink power regulation, allowing optimal local power control at the UE level without compromising overall downlink coverage reliability
Solution Approach 2:
The patent segments the power control function into two independent components: downlink coverage assessment (using macro RBS CRS) and uplink power regulation (using pico RBS PCRS). This segmentation allows each function to operate independently with its own reference signal, resolving the contradiction between maintaining downlink coverage and reducing uplink interference
2Reliability
If UEs transmit with higher power to ensure sufficient received power at serving RBS, then uplink signal quality improves, but battery life decreases
Solution Approach 1:
The patent implements feedback-based power control where the base station measures the actual uplink received power and compares it against target levels, then sends power control commands to adjust UE transmit power. This closed-loop feedback mechanism ensures sufficient uplink signal quality while minimizing power consumption by transmitting only the necessary power level
Solution Approach 2:
The patent changes the reference power parameter from macro RBS CRS to pico RBS PCRS, which has lower nominal power. This parameter change directly reduces the calculated path loss and consequently the required UE transmit power, improving battery life while maintaining adequate uplink signal quality through the feedback control mechanism
3Device complexity
If UEs use open-loop power control based on downlink measurements, then implementation is simpler, but power control accuracy decreases
Solution Approach 1:
The patent introduces dynamic power control by implementing closed-loop feedback mechanisms that continuously adjust UE transmit power based on real-time base station measurements. The system transitions from static open-loop control to dynamic closed-loop control, improving power control accuracy while managing complexity through standardized feedback procedures
Solution Approach 2:
The patent uses the base station as an intermediary that performs the complex measurement and calculation functions. Instead of requiring UEs to perform complex closed-loop control, the base station acts as the intermediary that measures uplink power, calculates required adjustments, and sends control commands back to UEs, simplifying UE implementation while achieving accurate power control
Data Source
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AI summary
According to some embodiments, there is provided a base station, system configured to, among other things, (a) detect whether a particular UE is using too much power to transmit uplink data and (b) in response, transmit a message to the UE instructing the UE to detect a power control RS (PCRS) that is intended only for the particular UE. In some embodiments, the PCRS is transmitted such that the power (actual or nominal) of the PCRS as received by the UE is higher than the power of the previous CRS detected by the UE, thereby leading the UE to calculate a lower PL values which ears lead to the UE lowering its output power.