NB-IoT Uplink Power Control Scheme Selection
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Solution Overview
Problem
Current power control schemes in NB-IoT systems, particularly in LTE and Rel. 17 NB-IoT, face challenges in efficiently managing uplink power consumption due to limitations in feedback mechanisms and channel condition variability, leading to suboptimal power adjustment for extended transmission durations and varying channel conditions.
Innovation Solution
The implementation of a method that selects from multiple power control schemes based on parameters such as subcarrier spacing, scheduling delay, RU size, repetition number, transmission gap, and RRC signaling, including closed loop power control with power ramping, scaling factors, and multi-time unit power adjustment indicators to determine optimal uplink transmission power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open loop power control is used, then device complexity is reduced, but power efficiency deteriorates due to inability to adapt to channel condition variability
Solution Approach 1:
The patent implements closed-loop power control by introducing a feedback channel that transmits power adjustment indicators from the network to the UE. The network evaluates uplink reception quality and sends TPC commands to adjust UE transmission power dynamically, enabling adaptation to channel conditions while maintaining reasonable device complexity.
Solution Approach 2:
The patent transitions from static open-loop power control to dynamic closed-loop power control. The system continuously adjusts transmission power based on real-time channel conditions through feedback mechanisms, allowing the power control parameters to adapt dynamically rather than remaining fixed.
2Use of energy by moving object
If feedback channel is introduced for closed loop power control, then power efficiency is improved, but device complexity increases
Solution Approach 1:
The patent segments the power control adjustment into discrete steps through quantized TPC commands. Instead of continuous power adjustment, the feedback channel transmits discrete power adjustment indicators that the UE applies in predetermined steps, simplifying the processing complexity while maintaining power control effectiveness.
Solution Approach 2:
The patent changes the power control parameter adjustment mode by introducing scaling factors and offsets. The network can configure different scaling factors (e.g., 0.5, 0.75, 1.0) and power offsets to adapt the power adjustment magnitude to specific scenarios, improving power efficiency without requiring complex processing at the UE side.
3Reliability
If power ramping is implemented, then reliability is improved for extended transmissions, but loss of time increases due to multiple power adjustment steps
Solution Approach 1:
The patent implements preliminary power ramping where the UE proactively increases transmission power in predetermined steps before attempting extended transmissions. The power ramping parameters (number of steps, step size) are configured in advance by the network, allowing the UE to quickly adapt to poor channel conditions without waiting for feedback loops, thus improving reliability while minimizing time loss.
4Adaptability or versatility
If multiple power control schemes are supported, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent creates a universal power control framework that can operate in multiple modes (open-loop, closed-loop with/without power ramping). The system uses a unified set of parameters and procedures that can be configured to achieve different power control behaviors, allowing the UE to adapt to various scenarios without requiring separate complex implementations for each mode.
Data Source
AI summary
Embodiments of the present application are directed to a method and apparatus for power control. In an embodiment of the present application, the method includes transmitting an uplink signal, wherein a transmission power of the uplink signal is determined according to a power control scheme, and the power control scheme is selected from at least one of an open loop power control scheme, a first closed loop power control scheme, a second closed loop power scheme with power ramping step selection, a third closed loop power scheme with scaling factor to power adjustment indicator, a fourth closed loop power scheme with later uplink signal corresponding power adjustment indicator adoption.