Remote Radio Head Power Amplifier Linearization for Field Reconfiguration
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Solution Overview
Problem
Current remote radio head units (RRUs) are power inefficient, costly, and inflexible, limiting their ability to support evolving wireless communication standards and high data-traffic growth, particularly due to poor DC to RF power conversion and lack of software upgradability.
Innovation Solution
The implementation of adaptive digital predistortion techniques to linearize RF power amplifiers, combined with crest factor reduction and power efficiency boosting methods, enables field-reconfigurable RRU systems that support multi-frequency bands, multi-modulation schemes, and multi-channels, utilizing a hybrid system of digital and analog modules for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional RF power amplifiers are used in RRUs, then the RRU can provide basic wireless communication functionality, but the DC to RF power conversion efficiency is poor and the device size becomes large
Solution Approach 1:
The patent replaces traditional analog RF power amplification with a digital signal processing approach. Digital predistortion algorithms are implemented in software to linearize the power amplifier output, eliminating the need for complex analog compensation circuits and reducing the overall device volume while improving power efficiency through optimized digital signal processing.
Solution Approach 2:
The patent employs digital predistortion techniques that dynamically adjust the input signal parameters to compensate for power amplifier nonlinearities. By changing the signal characteristics in the digital domain before amplification, the system achieves higher power conversion efficiency and reduces the thermal management requirements, thereby reducing housing size.
2Adaptability or versatility
If RRU hardware is designed to support multiple wireless standards, then versatility is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a universal RRU platform where a single hardware configuration can support multiple wireless communication standards (GSM, HSPA, LTE, WiMAX) through software configuration. The digital signal processing architecture is designed to be standards-agnostic, allowing the same physical device to be reconfigured for different standards without hardware changes, thereby reducing complexity while maintaining versatility.
Solution Approach 2:
The patent introduces dynamic reconfigurability through software that can adapt the RRU's operating parameters, modulation schemes, and signal processing algorithms in real-time based on the required wireless standard. This dynamic approach allows a single static hardware platform to perform multiple functions, eliminating the need for multiple specialized devices.
3Manufacturing precision
If RRU is designed with fixed functionality at manufacturing, then manufacturing precision is improved, but flexibility for field upgrades is lost
Solution Approach 1:
The patent incorporates preliminary software configuration capabilities during manufacturing that establish baseline operating parameters, while simultaneously embedding the infrastructure for future field upgrades. The digital signal processing framework is pre-configured with support for multiple standards, allowing consistent manufacturing while preserving the ability to perform additional configuration and updates in the field through software downloads and parameter adjustments.
Data Source
AI summary
A remote radio head unit (RRU) system is disclosed. The present invention is based on the method of adaptive digital predistortion to linearize a power amplifier inside the RRU. The power amplifier characteristics such as variation of linearity and asymmetric distortion of the amplifier output signal are monitored by a wideband feedback path and controlled by the adaptation algorithm in a digital module. Therefore, embodiments of the present invention can compensate for the nonlinearities as well as memory effects of the power amplifier systems and also improve performance, in terms of power added efficiency, adjacent channel leakage ratio and peak-to-average power ratio. The present disclosure enables a power amplifier system to be field reconfigurable and support multi-modulation schemes (modulation agnostic), multi-carriers, multi-frequency bands and multi-channels. Consequentially, the remote radio head system is particularly suitable for wireless transmission systems, such as base-stations, repeaters, and indoor signal coverage systems.