Remote Radio Head Predistortion for Efficient Multi-Band Operation
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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 functions, but the DC to RF power conversion efficiency is poor and the device size becomes large
Solution Approach 1:
The patent applies digital predistortion techniques that dynamically adjust signal parameters to optimize power amplifier efficiency. By modifying the input signal characteristics through digital processing, the system achieves better DC to RF power conversion efficiency without increasing physical size, directly resolving the contradiction between energy efficiency and device volume.
2Adaptability or versatility
If RRUs are designed with fixed functionality for current standards, then the device can be manufactured cost-effectively, but the system lacks flexibility to support evolving wireless communication standards
Solution Approach 1:
The patent implements dynamically reconfigurable RRUs where software can be updated in the field to support new wireless standards. The system transitions from static, fixed-functionality designs to dynamic, adaptable architectures that can change their operational characteristics through software updates, directly addressing the need for evolutionary standard support while managing complexity through modular design.
Solution Approach 2:
The patent creates universal RRU platforms capable of supporting multiple wireless communication standards (GSM, HSPA, LTE, WiMAX) through a single device architecture. By designing the RRU to perform multiple functions across different standards, the system achieves adaptability without proportionally increasing complexity, as the underlying hardware remains consistent while software configurations vary.
3Adaptability or versatility
If RRUs are designed to support multiple frequency bands and modulation schemes, then the system becomes more versatile, but the cost and complexity of the RRU platform increases
Solution Approach 1:
The patent implements a universal RRU platform that supports multiple frequency bands, modulation schemes, and wireless standards through a single integrated architecture. By designing the system to handle diverse functions within one platform, the patent achieves high versatility while controlling complexity through shared hardware resources and software-defined configurations, rather than requiring separate dedicated hardware for each function.
Solution Approach 2:
The patent segments the RRU functionality into modular components that can be independently configured for different frequency bands and modulation schemes. This segmentation allows the system to support multiple functions by combining and configuring modular building blocks, reducing overall platform complexity compared to monolithic designs that must accommodate all functions simultaneously.
4Use of energy by moving object
If power amplifier efficiency is improved through advanced techniques, then the RRU becomes more energy-efficient, but the system complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces traditional analog power amplifier optimization approaches with digital signal processing techniques. By using digital predistortion and software-based control instead of complex analog circuitry, the system achieves improved power amplifier efficiency while actually reducing overall system complexity and manufacturing cost, as digital processing is more scalable and easier to manufacture than high-precision analog components.
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.