Sounding Reference Signal Power Control for LTE-A Coverage
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Solution Overview
Problem
In wireless communication systems, the conventional maximum power reduction (MPR) scheme for sounding reference signals (SRS) reduces cell coverage when used in coordinated multi-point (COMP) operations, especially in LTE-A systems with carrier aggregation (CA), leading to decreased coverage and stability in data transmission.
Innovation Solution
Independently setting a higher power backoff for SRS transmission between cells or coordinated cells, allowing for optimized SRS power adjustment and using adaptive modulation coding (AMC) to enhance data throughput, while maintaining cell coverage through PUCCH over-provisioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional maximum power reduction (MPR) scheme is applied for sounding reference signals, then transmission power is reduced to meet spectral emission limits, but cell coverage is reduced and data transmission stability deteriorates
Solution Approach 1:
The patent segments the power backoff application by introducing separate MPR parameters for different signal types (MPR_SRS for sounding reference signals and MPR_PUSCH for uplink shared channel). This allows independent optimization of power reduction for SRS transmissions, enabling higher SRS power relative to data transmissions, thereby maintaining cell coverage while still meeting spectral emission limits through controlled power reduction on other signals.
Solution Approach 2:
The patent changes the power control parameters by introducing new MPR parameters (MPR_SRS, MPR_PUSCH) with different values and adjustment mechanisms. The base station can independently adjust MPR_SRS to be lower than MPR_PUSCH, allowing SRS to transmit at higher power to maintain coverage, while PUSCH uses higher power reduction to meet emission limits. This parameter differentiation resolves the contradiction between emission compliance and coverage maintenance.
2Object-affected harmful factors
If maximum power reduction is applied uniformly to all uplink signals, then spectral emission limits are met, but data transmission rate and reliability deteriorate due to reduced SRS quality
Solution Approach 1:
The patent segments power control into separate domains for control/signaling signals (SRS) and data signals (PUSCH) by introducing distinct MPR parameters. This segmentation allows SRS to maintain higher power for reliable channel state information feedback, while PUSCH applies greater power reduction to meet emission limits, thus maintaining data transmission reliability without violating spectral constraints.
Solution Approach 2:
The patent introduces adjustable MPR parameters that can be independently configured by the base station. By setting MPR_SRS < MPR_PUSCH, the system prioritizes SRS transmission quality for reliable channel estimation and feedback, while ensuring emission compliance through higher power reduction on data transmissions. The parameters can be dynamically adjusted based on channel conditions and network requirements.
3Area of stationary object
If higher SRS transmission power is used to maintain cell coverage, then spectral emission limits may be exceeded, but if lower power is used, coverage is reduced
Solution Approach 1:
The patent introduces flexible MPR parameters (MPR_SRS, MPR_PUSCH) that can be independently adjusted by the base station according to network conditions, UE capabilities, and regulatory requirements. This allows the system to optimize the balance between coverage and emission compliance dynamically, rather than using a fixed uniform power reduction that would force a compromise between these conflicting objectives.
Solution Approach 2:
The patent implements dynamic power control where the base station can adjust MPR parameters in real-time based on channel conditions, interference levels, and network load. This dynamic adjustment allows the system to maintain coverage when needed by reducing MPR_SRS, while ensuring emission compliance by increasing MPR_PUSCH when spectral limits are approached, resolving the static contradiction through adaptive control.
Data Source
AI summary
One embodiment of the present invention provides a method for transmitting a signal in a terminal. The method for transmitting a signal in a terminal comprises the steps of: setting a maximum power reduction (MPR) value for signal transmission power, wherein the maximum power reduction value is independently set for a sounding reference signal (SRS), and the maximum power reduction value which is set for the SRS is different from a maximum power reduction value which is set for another signal; and transmitting the SRS with transmission power which is set according to the set maximum power reduction value.