Massive MIMO Transmitter Architecture for Low-PAR Modulation

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Solution Overview

Problem

Current transmitter architectures for massive MIMO systems face challenges in achieving low Peak-to-Average Ratios (PARs) for power amplifiers, leading to inefficiency and high complexity due to the need for Crest Factor Reduction (CFR) and predistortion, which become impractical with hundreds of antennas.

Innovation Solution

A transmitter architecture that adjusts modulator input signals to reduce the PAR of the modulated signal, potentially eliminating the need for CFR and predistortion by using an actuator and adaptor to apply adjustments and configure modulation operations, thereby enhancing Power Amplifier efficiency and reducing system complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional transmitter architecture with CFR and DPD is used, then signal quality is maintained, but power amplifier efficiency deteriorates and device complexity increases

Engineering Contradiction:
Improvepower amplifier efficiencyVSAvoidtransmitter complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies preliminary Crest Factor Reduction (CFR) processing to the aggregated MIMO signal before distribution to individual power amplifiers. By reducing the peak-to-average power ratio in advance, the system enables power amplifiers to operate more efficiently without requiring complex real-time CFR or predistortion circuits at each antenna, thus resolving the contradiction between energy efficiency and device complexity

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent combines the CFR processing function into a centralized unit that processes the aggregated signal from all MIMO antennas before distribution. This merging approach eliminates the need for separate CFR and DPD circuits at each antenna, reducing overall device complexity while maintaining power amplifier efficiency through centralized pre-processing

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If hundreds of CFR and DPD circuits are deployed for Massive-MIMO, then signal quality is maintained, but power consumption increases

Engineering Contradiction:
Improvesignal qualityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements a universal centralized CFR processing unit that serves all MIMO antennas simultaneously. This single multi-functional unit performs crest factor reduction for the aggregated signal, eliminating the need for separate CFR and DPD circuits at each antenna, thereby maintaining signal quality while dramatically reducing power consumption

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent extracts the CFR and DPD functions from individual antenna circuits and consolidates them into a centralized processing unit. By removing these complex circuits from each antenna and replacing them with simpler amplifiers, the system maintains signal quality through centralized processing while reducing overall power consumption

Inventive Principle:
Principle #2Taking out (Extraction)

3Loss of energy

If PAR is reduced to improve PA efficiency, then power amplifier efficiency improves, but signal distortion may increase

Engineering Contradiction:
Improvepower amplifier efficiencyVSAvoidsignal distortion
Core Design Contradiction:
Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The patent employs feedback mechanisms in the centralized CFR processing unit to monitor and adjust the processed signal characteristics. This feedback control ensures that crest factor reduction is achieved while maintaining signal integrity and minimizing distortion, allowing power amplifiers to operate efficiently without generating harmful signal distortion

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3476042A1Transmitter architecture for massive-mimo
Publication Date: 2019.05.01 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Embodiments of a transmitter having an architecture that reduces power consumption and complexity are disclosed. In some embodiments, a transmitter comprises a modulator comprising an actuator, modulation circuitry, and an adaptor. The actuator is operable to apply at least one adjustment to at least one modulator input signal to provide at least one adjusted modulator input signal. The modulation circuitry is operable to perform a modulation operation on the at least one adjusted modulator input signal to provide a modulated signal, and the adaptor is operable to adaptively configure the at least one adjustment applied to the at least one modulator input signal such that a Peak-to-Average Ratio (PAR) of the modulated signal is reduced.