Multi-Pilot PA Nonlinearity Compensation for Base Station Signals
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Solution Overview
Problem
The non-linearity of power amplifiers (PAs) in wireless communication systems, particularly in high-output power regions, leads to signal distortion and reduced coverage due to the back-off process needed to prevent non-linear operation, which in turn limits the transmission power and data reception performance.
Innovation Solution
A method involving multi-pilot operations for channel estimation and non-linearity compensation using accurate channel and non-linearity information acquisition, facilitated by a base station and terminal with transceivers and controllers, to improve data reception performance by compensating for PA non-linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If transmission power is increased through power amplifier to improve coverage and data rate, then transmission power and coverage are improved, but signal distortion occurs due to PA non-linearity
Solution Approach 1:
The patent applies preliminary action by performing digital pre-distortion (DPD) on the transmission signal before it enters the power amplifier. The controller pre-compensates for the expected non-linear distortion by applying an inverse distortion function, so that when the signal passes through the PA, the distortions cancel out and the output signal remains linear and undistorted.
Solution Approach 2:
The patent implements feedback by having the reception node measure the actual non-linearity characteristics of the PA using pilot signals, then feed back this non-linearity information to the transmission node. The transmission node uses this feedback to adjust and refine the pre-distortion parameters, creating a closed-loop system that continuously optimizes compensation accuracy.
2Reliability
If back-off process is applied to prevent non-linear operation, then signal distortion is reduced, but transmission power is limited and coverage decreases
Solution Approach 1:
The patent eliminates the need for back-off by applying preliminary pre-distortion compensation. Instead of limiting the PA operating power to stay within linear region, the system pre-compensates for non-linearity, allowing the PA to operate at maximum power while still producing linear output signals through the cancellation of distortions.
Solution Approach 2:
The patent converts the harmful non-linear characteristic of the PA into a beneficial property by characterizing the non-linearity through pilot signal measurements and then using this knowledge to pre-distort signals in the opposite direction. The non-linearity that causes distortion is transformed into a predictable, compensatable property that enables full-power operation without distortion.
3Device complexity
If single pilot is used for both channel estimation and non-linearity compensation, then device complexity is reduced, but measurement precision deteriorates due to conflicting requirements
Solution Approach 1:
The patent applies segmentation by dividing the single pilot function into two separate pilots: one dedicated to channel estimation and another dedicated to non-linearity compensation measurement. This segmentation allows each pilot to be optimized for its specific purpose, with the channel estimation pilot using lower power for accurate channel characterization and the non-linearity pilot using full power for accurate PA characteristic measurement.
Solution Approach 2:
The patent implements local quality by assigning different power levels and optimization criteria to different pilots based on their specific functions. The channel estimation pilot is transmitted at a power level optimized for channel measurement accuracy, while the non-linearity compensation pilot is transmitted at full PA power to accurately capture the PA's non-linear behavior under actual operating conditions.
Data Source
AI summary
The disclosure relates to a 6G communication system for achieving high data transmission rates and ultra-low latency after 4G and 5G communication systems. A method performed by a base station in a communication system according to an embodiment of the disclosure may include identifying a first pilot for channel estimation or a second pilot for non-linearity compensation of a PA, identifying pilot information related to at least one of the first pilot and the second pilot, and transmitting, to a terminal, control information including the pilot information.