Independent SRS and Data Power Control in LTE User Equipment
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Solution Overview
Problem
Current power control methods in LTE networks fail to independently adjust the transmission power of sounding reference signals (SRS) and data, leading to undetectable SRS at macro base stations and unnecessary interference, especially in heterogeneous cell deployments where SRS are destined for a macro base station but data is intended for a pico base station.
Innovation Solution
Implementing independent path loss estimation and closed-loop power control for SRS and data transmissions, using different CSI-RS patterns and separate power control instances to adapt to varying channel conditions, allowing SRS power control to prioritize macro base station reception while data power control focuses on pico base station requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If independent power control for SRS and data is implemented, then SRS detectability at macro base station is improved, but device complexity increases
Solution Approach 1:
The patent segments the power control mechanism into two independent control loops: one for SRS transmissions and another for data transmissions. Each loop has its own path loss estimation and power adjustment logic, allowing SRS power to be optimized for macro base station reception while data power is optimized for pico base station reception, thereby resolving the detectability issue without requiring complete redesign of the power control system
Solution Approach 2:
The patent applies different power control parameters and path loss estimates locally to different transmission types. SRS transmissions use path loss estimates specific to the macro base station link, while data transmissions use path loss estimates for the pico base station link. This localized optimization ensures each transmission type achieves its specific reliability goal without unnecessarily increasing overall system complexity
2Reliability
If SRS power is increased for macro base station reception, then SRS detectability is improved, but interference to other cells increases
Solution Approach 1:
The patent implements closed-loop power control with feedback mechanisms where the base station measures the received SRS signal quality and sends power adjustment commands back to the user equipment. This feedback loop allows the system to dynamically adjust SRS power levels to achieve reliable detection at the macro base station while automatically preventing excessive power that would cause harmful interference to other cells
Solution Approach 2:
The patent changes the power control parameters specifically for SRS transmissions, using separate path loss estimates and power offset values that are optimized for macro base station reception. By adjusting these parameters independently from data transmission parameters, the system achieves reliable SRS detection without applying excessive power that would create interference, as the parameter changes are precisely tailored to the SRS detection requirement
3Measurement precision
If separate path loss estimation is used for SRS and data, then power control accuracy is improved, but processing overhead increases
Solution Approach 1:
The patent segments the path loss estimation process into separate estimations for SRS and data transmissions. Each estimation uses measurements and parameters specific to its transmission type and target base station, improving accuracy by accounting for different channel conditions and base station locations, while the segmentation allows parallel processing that minimizes additional time overhead
Data Source
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AI summary
Disclosed are methods and apparatuses in user equipments (1400) and network nodes (1410, 420) for controlling transmission power of the user equipments when the user equipments are connected to a wireless network. The disclosed methods and apparatuses deals with independently controlling transmission power of SRS signals and signals comprising traffic data from the user equipment (1400). Thereby, it is possible to use different power levels for SRS signals intended to e.g. a macro node and for traffic data intended to e.g. a pico node.